TY - JOUR TI - Emissions estimation at multilane roundabouts AU - Salamati, K. AU - Coelho, M. AU - Fernandes, P. AU - Rouphail, N. AU - Frey, H. AU - Bandeira, J. T2 - Transportation Research Record AB - This paper reports on research that explored how multilane roundabouts located on urban corridors have affected traffic performance and pollutant emissions generated from vehicles. The research also compared the emissions of vehicles moving through the roundabouts as they used either the left or right entry lanes. The methodology can be generalized to measure the emissions of any multilane roundabout. The paper identified a representative speed profile for each speed trajectory type, no stop, one stop, and multiple stops, from field data collected at four multilane roundabouts in Aveiro, Portugal. The vehicle-specific power emissions methodology was employed to estimate the second-by-second emissions generated from a vehicle during different acceleration–deceleration cycles. Congestion-specific vehicle speed profiles for two-lane roundabout approaches were used to develop regression models to predict the percentage of vehicles that would experience different speed trajectory types in the roundabout. The analysis tested hypotheses about how differences in the following characteristics have affected the amount of emissions generated from vehicles in each lane: (a) the speed profiles in each lane (left versus right), (b) the conflicting flows for the left and right lanes, (c) the lane flow, and (d) the overall congestion levels. Under low congestion levels, vehicles in the right lane emitted more pollutant because they had on average higher speed and sharper acceleration and deceleration rates. For high congestion levels, given equal flow rates for the left and right lanes, vehicles in the left lane produced more emissions because vehicles in the left lane experienced longer stop-and-go cycles and had different speed profiles than did vehicles in the right lane. DA - 2013/// PY - 2013/// DO - 10.3141/2389-02 IS - 2389 SP - 12-21 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84897133284&partnerID=MN8TOARS ER - TY - JOUR TI - Public voices and energy choices: Citizens speak out at the North Carolina Utilities Commission AU - Kinsella, W.J. AU - Kelly, A.R. AU - Kittle Autry, M. T2 - Communication Currents DA - 2013/// PY - 2013/// VL - 8 IS - 5 ER - TY - JOUR TI - Assessment of de facto wastewater reuse across the U.S.: Trends between 1980 and 2008 AU - Rice, Jacelyn AU - Wutich, Amber AU - Westerhoff, Paul T2 - Environmental Science and Technology AB - De facto wastewater reuse is the incidental presence of treated wastewater in a water supply source. In 1980 the EPA identified drinking water treatment plants (DWTPs) impacted by upstream wastewater treatment plant (WWTP) discharges and found the top 25 most impacted DWTPs contained between 2% and 16% wastewater discharges from upstream locations (i.e., de facto reuse) under average streamflow conditions. This study is the first to provide an update to the 1980 EPA analysis. An ArcGIS model of DWTPs and WWTPs across the U.S. was created to quantify de facto reuse for the top 25 cities in the 1980 EPA study. From 1980 to 2008, de facto reuse increased for 17 of the 25 DWTPs, as municipal flows upstream of the sites increased by 68%. Under low streamflow conditions, de facto reuse in DWTP supplies ranged from 7% to 100%, illustrating the importance of wastewater in sustainable water supplies. Case studies were performed on four cities to analyze the reasons for changes in de facto reuse over time. Three of the four sites have greater than 20% treated wastewater effluent within their drinking water source for streamflow less than the 25th percentile historic flow. DA - 2013/// PY - 2013/// DO - 10.1021/es402792s VL - 47 IS - 19 SP - 11099-11105 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84885128868&partnerID=MN8TOARS ER - TY - JOUR TI - Geotechnical Aspects of OCAES Vessel and Anchoring System AU - Gabr, M.A. AU - Xia, JinFu AU - Rahman, Shamim AU - Evans, T.M. T2 - GEOSTRATA, American Society of Civil Engineering (ASCE) DA - 2013/6// PY - 2013/6// VL - 19 IS - 3 ER - TY - CONF TI - Assessment of Scour Potential of Silty Sand Using ISEEP AU - Kayser, M. AU - Gabr, M. T2 - 18th International Conference on Soil Mechanics and Geotechnical Engineering C2 - 2013/9// C3 - Proceedings of the 18th International Conference on Soil Mechanics and Geotechnical Engineering CY - Paris, France DA - 2013/9// PY - 2013/9// ER - TY - CONF TI - Estimating Incident Propensity Analysis in the Highway Capacity Manual AU - Aghdashi, S. AU - Rouphail, N.M. AU - Hajbabaie, A. T2 - 92nd Annual Meeting of the Transportation Research Board C2 - 2013/// C3 - The 92nd Annual Meeting of the Transportation Research Board CY - Washington, DC DA - 2013/// PY - 2013/1/13/ ER - TY - CONF TI - Incorporating Weather Effects in HCM Reliability Analysis AU - Chase, R.T. AU - Hajbabaie, A. AU - Schroeder, B.J. T2 - 92nd Annual Meeting of the Transportation Research Board C2 - 2013/// C3 - The 92nd Annual Meeting of the Transportation Research Board CY - Washington, DC DA - 2013/// PY - 2013/1/13/ ER - TY - THES TI - Satisfying Multiple Priorities with a Diversity Preserving Evolutionary Algorithm AU - Chmielewski, H.T. DA - 2013/// PY - 2013/// M3 - Masters thesis PB - North Carolina State University UR - http://www.lib.ncsu.edu/resolver/1840.16/8866. ER - TY - CONF TI - Understanding and predicting the adsorption of trace organic micropollutants by granular activated carbon AU - Kennedy, A. AU - Reinert, A. AU - Knappe, D. AU - Summers, R.S. C2 - 2013/// C3 - 2013 Water Quality Technology Conference and Exposition, WQTC 2013 DA - 2013/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84890451391&partnerID=MN8TOARS ER - TY - CONF TI - The effect of background matrix and competition of GAC Adsorption of Carcinogenic VOCs in Natural Waters AU - Kempisty, D.M. AU - Summers, R.S. AU - Knappe, D. C2 - 2013/// C3 - 2013 Water Quality Technology Conference and Exposition, WQTC 2013 DA - 2013/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84890544639&partnerID=MN8TOARS ER - TY - CONF TI - The influence of climate change on hydro generation in Brazil AU - Scianni, L.A. AU - Queiroz, A.R. AU - Lima, L.M.M. AU - Lima, J.W.M. AB - More than 85% of the total electricity generation in Brazil comes from Hydro Plants. The hydroelectricity is a good example of renewable resources which, in this case, depends greatly on the precipitation. An optimization program is used in order to determine the dispatches of the plants and to minimize the operational costs. Given a set of hydro plants it is possible to calculate the power system assured energy or the amount of energy available to supply the load at a deficit risk of 5%. However, climate change can cause great variation on the assured energy. The problem drastically aggravates for the new available hydro potentials located in the Amazon region which probably will be affected by the global warming. This paper provides the initial results of a research project sponsored by generation companies and the regulatory agency in Brazil. C2 - 2013/// C3 - 2013 IEEE Grenoble Conference PowerTech, POWERTECH 2013 DA - 2013/// DO - 10.1109/PTC.2013.6652402 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84890889216&partnerID=MN8TOARS ER - TY - JOUR TI - Sharing cuts under aggregated forecasts when decomposing multi-stage stochastic programs AU - De Queiroz, A.R. AU - Morton, D.P. T2 - Operations Research Letters AB - Sampling-based decomposition algorithms (SBDAs) solve multi-stage stochastic programs. SBDAs can approximately solve problem instances with many time stages when the stochastic program exhibits interstage dependence in its right-hand side parameters by appropriately sharing cuts. We extend previous methods for sharing cuts in SBDAs, establishing new results under a novel interaction between a class of interstage dependency models, and how they appear in the stochastic program. DA - 2013/// PY - 2013/// DO - 10.1016/j.orl.2013.03.003 VL - 41 IS - 3 SP - 311-316 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84875926459&partnerID=MN8TOARS ER - TY - BOOK TI - Development of an oversaturated speed-flow model based on the highway capacity manual AU - Xu, Y. AU - Williams, B. AU - Rouphail, N. AU - Chase, R. AB - Oversaturated speed, flow, and density relationships are of key importance to studies of freeway operations. The Highway Capacity Manual (HCM) oversaturated model, which is defined by a linear transition from the flow and the density at capacity to a zero flow at jam density in the flow–density space, provides a reasonable representation of this relationship but does not provide an unbiased representation for all freeway facilities with different road conditions or driver behavior. This study proposes a method for fitting the HCM model to oversaturated flow and density. Fifteen-minute aggregated flow rate and speed data were collected in 2010 from Traffic.com fixed-location sensors at three sites on North Carolina urban freeways. Density was calculated as the flow rate divided by the speed. The fitted models for these sites were compared with the default HCM model. A set of thresholds was defined to identify eligible sensor observations that represented the steady-state congested traffic conditions. The results revealed that data observations during inclement weather, lane closures, or incidents biased the model-fitting results and therefore needed to be filtered out. The steady-state congestion data identified in the manner proposed in this study fit well with the HCM-based linear flow–density oversaturated model. This method avoids possible bias caused by capacity and jam density differences between the default HCM model and the site-specific models; therefore, the fitted models represented the actual traffic characteristics relationships better than the default HCM models did. Fitting a site-specific HCM-based model is recommended for sites with sufficient speed and flow data. DA - 2013/// PY - 2013/// DO - 10.3141/2395-05 SE - 41-48 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84897034574&partnerID=MN8TOARS ER - TY - CONF TI - In-Plane Shear Behavior of Nuclear Power Plant Wall Elements with High-Strength Reinforcing Bars AU - Bae, G.-M. AU - Proestos, G.T. AU - Lee, S.-C. AU - Bentz, E.C. AU - Collins, M.P. AU - Cho, J.-Y. T2 - 22nd Conference on Structural Mechanics in Reactor Technology C2 - 2013/8/18/ C3 - Transactions, SMiRT-22: 22nd Conference on Structural Mechanics in Reactor Technology CY - San Francisco, California, USA DA - 2013/8/18/ PY - 2013/8/18/ ER - TY - JOUR TI - Development of integrated reactors for domestic garbage and town sludge AU - Wu, Z. AU - Zhi, Y. AU - He, Q. AU - Tang, S. AU - Ling, J. AU - Pan, M. T2 - Chongqing Daxue Xuebao/Journal of Chongqing University DA - 2013/// PY - 2013/// VL - 36 IS - 1 SP - 127-132 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84874961358&partnerID=MN8TOARS ER - TY - SOUND TI - New Tools to Assess the Potential Risk of FOG deposit Accumulation in a Wastewater Collection System AU - Ducoste, J.J. DA - 2013/// PY - 2013/// ER - TY - CONF TI - Experimental and Numerical Evaluation of a UV-LED Point of Use Disinfection Device AU - Jenny, R.M. AU - Simmons, O.D. AU - Ducoste, J. T2 - North Carolina Section of the American Water Works Association (NC AWWA) Water Environment Association (WEA) C2 - 2013/11/10/ CY - Concord, NC DA - 2013/11/10/ PY - 2013/11/10/ ER - TY - CONF TI - Simulating the Formation of Fats, Oils, and Grease (FOG) Deposits in a Sewer Collection System AU - Yousefelahiyeh, R. AU - Dominic, C.C.S. AU - Ducoste, J. T2 - North Carolina Section of the American Water Works Association (NC AWWA) Water Environment Association (WEA) C2 - 2013/// CY - Concord, NC DA - 2013/// PY - 2013/11/10/ ER - TY - CONF TI - Quantifying Fat, Oil, and Grease (FOG) Deposits Formation Kinetics in Sewer Collection System AU - Iasmin, M. AU - Ducoste, J. T2 - North Carolina Section of the American Water Works Association (NC AWWA) Water Environment Association (WEA) C2 - 2013/11/10/ CY - Concord, NC, DA - 2013/11/10/ PY - 2013/11/10/ ER - TY - SOUND TI - Solid Waste Engineering: Test Tubes, Landfills and Models AU - Barlaz, M.A. DA - 2013/// PY - 2013/// M3 - Invited Lecture ER - TY - CONF TI - What is the Optimal Way for a Suburban U.S. City to Sustainably Manage Future Solid Waste? Perspectives from a Solid Waste Optimization Life-cycle Framework (SWOLF) AU - Barlaz, M.A. AU - Levis, J. AU - DeCarolis, J. AU - Ranjithan, S.R. T2 - Fourteenth International Waste Management and Landfill Symposium C2 - 2013/// CY - Cagliari, Italy DA - 2013/// PY - 2013/// ER - TY - CONF TI - Modernizing Models and Data on Methane Production from U.S. Municipal Solid Waste AU - Barlaz, M.A. T2 - Engineering Society of Detroit 23rd Annual Solid Waste Technical Conference C2 - 2013/// CY - Detroit, MI DA - 2013/// PY - 2013/4/17/ ER - TY - JOUR TI - Structural Composites Thermally Efficient Precast Concrete AU - Lucier, G. AU - Sennour, L. AU - Rizkalla, S. T2 - Concrete Plant International, CPI DA - 2013/// PY - 2013/// VL - 2 IS - 1 SP - 1–10 ER - TY - JOUR TI - Innovative Use of FRP for Sustainable Precast Structures AU - Rizkalla, S. AU - Lunn, D. AU - Lucier, G. AU - Sennour, L. AU - Gleich, H. AU - Carson, J. T2 - Precast Concrete Façade Tectonics Journal DA - 2013/2// PY - 2013/2// IS - 8 SP - 55–63 ER - TY - JOUR TI - Precast Concrete Wall Panels AU - Rizkalla, S. AU - Lunn, D. AU - Lucier, G. AU - Sennour, L. AU - Gleich, H. T2 - Journal of the Concrete Plant International Journal DA - 2013/3/15/ PY - 2013/3/15/ ER - TY - JOUR TI - Anchorage Systems for FRP Strengthening of Infill Masionry Structures AU - Lunn, D. AU - Maeda, S. AU - Rizkalla, S. AU - Ueda, T. T2 - International Journal of Sustainable Materials and Structural Systems DA - 2013/9// PY - 2013/9// VL - 1 IS - 2 SP - 142–160 ER - TY - JOUR TI - Torsion Simplified: A Failure Plan Model for Design of Spandrel Beams AU - Klein, G.L. AU - Lucier, G. AU - Rizkalla, S. AU - Zia, P. AU - Gleich, H. T2 - ACI Structural Journal DA - 2013/10// PY - 2013/10// VL - 110 IS - 5 ER - TY - RPRT TI - DBP Precursor and Micropollutant Removal by Powdered Activated Carbon AU - Dunn, S.E. AU - Knappe, D.R.U. A3 - Water Research Foundation DA - 2013/// PY - 2013/// M1 - 4294 M3 - Executive Summary PB - Water Research Foundation SN - 4294 ER - TY - CONF TI - Applying Multi-objective Niching Co-evolutionary Algorithm to Generate Insight for Water Resources Management Problems AU - Shafiee, M. E. AU - Kandiah, V. K. AU - Barrett, E. AU - Zechman, E. M. T2 - World Environmental and Water Resources Congress 2013 AB - Real-world engineering problems typically involve multiple objectives that should be addressed simultaneously. A set of Pareto-optimal solutions that represents the trade-off among conflicting objectives can be identified to provide knowledge about the performance of alternative solutions for design and management problems. Many multi-objective evolutionary algorithms (MOEA) have been developed and designed to efficiently identify a set of nondominated solutions, and these algorithms have been successfully applied for realistic engineering problems. Realistic design problems may require more analysis and solution generation capabilities than provided by a typical MOEA. The fitness landscapes for realistic design problems are often nonlinear, complex, and multi-modal, and, in addition, water resources planning and management problems typically involve a diverse set of stakeholders with a set of preferences that are not represented mathematically and included in an optimization model. Identification of alternative sets of nondominated solutions that are similarly Pareto-optimal can address the problem of multi-modality in the decision space and provide additional insight to problem solution and options for implementation. The Multi-objective Niching Co-evolutionary Algorithm (MNCA) was designed to use a multi-population optimization search to evolve multiple nondominated solution sets. MNCA is demonstrated here for solution of two illustrative water resources management problems, including a water supply network design problem and a water quality management problem. Results are analyzed to demonstrate the use of MNCA to generate new insight and options for addressing difficult problems. C2 - 2013/5/28/ C3 - World Environmental and Water Resources Congress 2013 CY - Cincinnati, Ohio DA - 2013/5/28/ PY - 2013/5/19/ DO - 10.1061/9780784412947.228 PB - American Society of Civil Engineers SN - 9780784412947 UR - http://dx.doi.org/10.1061/9780784412947.228 ER - TY - CONF TI - An Agent-based Modeling Approach to Simulate the Influence of Consumer Behavior on Infrastructure Performance for Urban Water Reclamation Management AU - Kandiah, V. K. AU - Zechman, E. M. AU - Binder, Andrew R. T2 - World Environmental and Water Resources Congress 2013 AB - Water reuse introduces new interconnections among urban water infrastructure services. For both decentralized and centralized systems, water recycling influences the burden on the stormwater, wastewater, and drinking water systems. Reductions in drinking water demands, caused by an uptake in water reuse, can cause changes in system pressures and new hydraulic conditions in the network. The proposed research will explore the interconnections among urban water infrastructure for water reuse strategies and develop a new agent-based modeling framework to simulate the interactions among consumer behaviors, water reuse technologies, and existing water supply infrastructure. An agent-based model of consumers will be coupled with water infrastructure systems models, and both the water distribution system and water reclamation system infrastructure will be simulated using EPANET. Each agent, representing a household, will be associated with a node in the drinking water system where its demand is exerted. As agents adopt reclaimed water, demand inputs to the drinking water model and reclamation system model are updated accordingly. The framework will be used to simulate the emergence of the adoption of water reclamation and infrastructure performance based on metrics, including extreme pressures, changes in flows, and utilization of existing capacity. C2 - 2013/5/28/ C3 - World Environmental and Water Resources Congress 2013 CY - Cincinnati, Ohio DA - 2013/5/28/ PY - 2013/5/19/ DO - 10.1061/9780784412947.226 PB - American Society of Civil Engineers SN - 9780784412947 UR - http://dx.doi.org/10.1061/9780784412947.226 ER - TY - CONF TI - A Mechanistic-Stochastic Approach to Classify Water Consumers and Simulate Urban Water Demand AU - Kanta, Lufthansa AU - Zechman, Emily M. T2 - World Environmental and Water Resources Congress 2013 AB - Stochasticity in urban water demand arises due to the unpredictability and randomness of consumer behavior, which is influenced by population growth, climatic conditions, and conservation programs. Most urban water demand estimation methodologies are based on end-use models or stochastic models. End-use models describe the uses of water by households at the appliance level and require extensive and detailed data about water activities and water appliances. Stochastic models, however, predict water use using empirical relationships based on predictors, such as population size and water pricing. Integration of mechanistic end-use modeling with stochastic modeling can aid in better understanding of consumers' water use behavior and, therefore, can aid in better estimation of water availability in planning and management of urban water resources. A novel mechanistic-stochastic water demand model is developed here through the integration of an end-use model and a stochastic model. The model is developed using residential customer billing records from two water utilities. The historical water billing records are fitted to a gamma distribution based on the Akaike Information Criterion (AIC) values compared to exponential, extreme value, and log-normal distribution. Consumers are categorized into different groups from the distribution of water billing records and aggregated demand is estimated for the water system. To validate the modeled customer categories, housing survey data is collected and analyzed. Integration of mechanistic and stochastic modeling along with linkage of multiple data sources through this methodology can provide a powerful tool for efficient and sustainable water resources management. C2 - 2013/5/28/ C3 - World Environmental and Water Resources Congress 2013 CY - Cincinnati, Ohio DA - 2013/5/28/ PY - 2013/5/19/ DO - 10.1061/9780784412947.224 PB - American Society of Civil Engineers SN - 9780784412947 UR - http://dx.doi.org/10.1061/9780784412947.224 ER - TY - CONF TI - Integrating Genetic Programming and Agent-based Modeling to Identify Sensor-based Rules for Flushing Contaminated Water from a Pipe Network AU - Shafiee, M. Ehsan AU - Zechman, Emily M. T2 - World Environmental and Water Resources Congress 2013 AB - A utility manager may become aware of a threat of contamination to a water distribution network through water quality sensor information, which may indicate that a biological pathogen or chemical contaminant was introduced to the network. In response, a utility manager can select a set of hydrants to flush contaminant from the network. As an event unfolds, a decision maker may not be able to ascertain source characteristics, creating additional difficulties in determining the set of hydrants that should be opened. The research presented here develops a Genetic Programming (GP)-based approach to identify a set of response actions that are based on sensor information, instead of source characteristics, for guiding selection of hydrants. GP is a method within the class of evolutionary computation, and a solution is represented as a combination of values and symbols to represent a computer program for executing computations, such as a mathematical equation. GP is developed in this research to program a list of rules for opening and closing hydrants that will effectively protect public health for an ensemble of contamination events. An ensemble of contamination events is developed based on a set of similar activated sensors. As the public health effects of a contamination event are influenced by a set of complex interactions among consumers, utility operators, and the pipe network, an agent-based modeling framework is used to predict the dynamic location of a contaminant plume during a contamination event and the number of exposed consumers. To identify optimal hydrant strategies to flush a contaminant while considering the complexity of interactions in the system, a simulation-optimization model couples agent-based modeling with GP. Multiple contamination scenarios are modeled to evaluate potential solutions, and the simulation-optimization framework is demonstrated for a virtual mid-sized municipality, Mesopolis. C2 - 2013/5/28/ C3 - World Environmental and Water Resources Congress 2013 CY - Cincinnati, Ohio DA - 2013/5/28/ PY - 2013/5/19/ DO - 10.1061/9780784412947.075 PB - American Society of Civil Engineers SN - 9780784412947 UR - http://dx.doi.org/10.1061/9780784412947.075 ER - TY - JOUR TI - In situ X-ray microdiffraction studies inside individual VO2 microcrystals AU - Budai, J.D. AU - Tselev, A. AU - Tischler, J.Z. AU - Strelcov, E. AU - Kolmakov, A. AU - Liu, W.J. AU - Gupta, A. AU - Narayan, J. T2 - Acta Materialia AB - Synchrotron X-ray microdiffraction provides quantitative structural measurements with submicron spatial resolution, and hence enables investigations of how local microstructural inhomogeneities affect materials’ properties. A combination of polychromatic and monochromatic X-ray microdiffraction was used to investigate domain formation, interface orientations and strain distributions inside individual vanadium dioxide (VO2) microcrystals. Using in situ measurements near the VO2 metal–insulator phase transition, it was found that the observed phase evolution is critically dependent on external strain. Substrate-induced strains or inhomogeneous sample heating can directly alter phase stability and affect the local domain orientations. In different clamped or freely suspended single-crystal samples, all the predicted twin laws for the M2 phase in VO2 were observed, except one. When the rutile and M2 phases coexist, it was found that different interphase boundary orientations can be stabilized by sample size and by interfacial elastic strain. The large variations in phase sequences and domain orientations observed in relatively simple, small single crystals provide insight into the mechanisms responsible for the broad structural and electronic transitions observed in epitaxial VO2 films. DA - 2013/5// PY - 2013/5// DO - 10.1016/j.actamat.2012.09.074 VL - 61 IS - 8 SP - 2751-2762 J2 - Acta Materialia LA - en OP - SN - 1359-6454 UR - http://dx.doi.org/10.1016/j.actamat.2012.09.074 DB - Crossref KW - Synchrotron microdiffraction KW - Phase transition KW - Interfaces KW - Twinning ER - TY - CONF TI - Evolution of Organic Matter and Organic Nitrogen in Leachates with Landfilling Age: A Size Distribution and Hydrophobicity Study AU - Gupta, Abhinav T2 - World Environmental and Water Resources Congress 2013 AB - Landfill leachates are frequently discharged to publically owned treatment works (POTWs). The presence of UV quenching substances in leachate interferes with UV disinfection at the POTWs. Also, the biorefractory organic nitrogen contained in the leachate contributes to the plant's effluent nitrogen making it difficult to meet the tightening total nitrogen effluent regulations in some regions of the country. To study the changes in organic carbon and nitrogen with landfill age, leachate samples with landfilling ages ranging from two to 30 years from a large landfill in Kentucky were collected and fractionated on the basis of their particle size (molecular weight cut off) and hydrophobicity into humic acids (HA), fulvic acids (FA), and a hydrophilic (Hpi) fraction. The results identified the hydrophilic component, which was mostly < 1 kDa as the major source of the total organic carbon and organic nitrogen. This component tends to persist even in the older stabilized leachates whereas the HA fraction gets degraded or converted into FA fraction. The effectiveness of biological treatment for leachates at different ages was examined to develop an understanding that might help design on-site treatment methods. It was observed that on-site biological treatment was able to degrade organic matter measured as total organic carbon (TOC) but was not effective for removal of UV quenching substances, especially for the older leachates. This pointed to the possibility that the microorganisms with the capability to degrade the UV absorbing substances need a detention time of around 10-20 years, which cannot be provided by on-site biological treatment. It was also observed that one-third of the organic nitrogen was from proteins that were mainly concentrated in the Hpi fraction. C2 - 2013/5/28/ C3 - World Environmental and Water Resources Congress 2013 DA - 2013/5/28/ DO - 10.1061/9780784412947.249 PB - American Society of Civil Engineers SN - 9780784412947 UR - http://dx.doi.org/10.1061/9780784412947.249 DB - Crossref ER - TY - SOUND TI - Climate-informed Uncertainty Analyses for Water and Energy Management AU - Arumugam, S. DA - 2013/2/20/ PY - 2013/2/20/ ER - TY - SOUND TI - Climate, Water and Energy Management in the Greater Horn of Africa AU - Arumugam, S. DA - 2013/3/23/ PY - 2013/3/23/ ER - TY - CONF TI - Near-term Climate Change and Water Management over the Sunbelt AU - Arumugam, S. T2 - Water Sustainability and Climate (WSC) PI meeting C2 - 2013/3/11/ CY - National Science Foundation DA - 2013/3/11/ PY - 2013/3/11/ ER - TY - CONF TI - Multivariate Downscaling of Decadal Climate Change Projections over the Sunbelt AU - Bhowmik, R. AU - Arumugam, S. AU - Patskoski, J. T2 - American Geophysical Union Chapman Conference, Seasonal to Interannual Hydroclimatic Forecasts and Water Management C2 - 2013/7/28/ CY - Portland, OR DA - 2013/7/28/ PY - 2013/7/28/ ER - TY - CONF TI - Near-term Climate Change Impacts on Surface water and groundwater interactions over the Sunbelt AU - Seo, S.B AU - Sinha, T. AU - Mahinthakumar, G. AU - Arumugam, S. T2 - American Geophysical Union Chapman Conference, Seasonal to Interannual Hydroclimatic Forecasts and Water Management C2 - 2013/7/28/ CY - Portland, OR DA - 2013/7/28/ PY - 2013/7/28/ ER - TY - CONF TI - Decomposition of Sources of Errors in developing Seasonal Streamflow Forecasts over the Sunbelt AU - Mazoorei, A. AU - Sinha, T. AU - Arumugam, S. T2 - American Geophysical Union Chapman Conference, Seasonal to Interannual Hydroclimatic Forecasts and Water Management C2 - 2013/7/28/ CY - Portland, OR DA - 2013/7/28/ PY - 2013/7/28/ ER - TY - CONF TI - Experimental Inflow and Storage Forecasts for the State of NC AU - Sinha, T. AU - Mazoorei, A. AU - Arumugam, S. AU - Boyles, R. T2 - American Geophysical Union Chapman Conference, Seasonal to Interannual Hydroclimatic Forecasts and Water Management C2 - 2013/7// CY - Portland, OR DA - 2013/7// PY - 2013/7/28/ ER - TY - CONF TI - A Quantitative Framework for Assessing the Effects of Climate and Land-use Change on Streamflow AU - Ranjithan, R.S. AU - Touma, D. AU - Brill, E.D. AU - Sankarasubramanian, A. T2 - World Environmental & Water Resources (EWRI) Conference C2 - 2013/5/19/ CY - Cincinnati, Ohio DA - 2013/5/19/ PY - 2013/5/19/ ER - TY - RPRT TI - Uncertainty in Surface Water Availability over North Carolina under climate and land use changes AU - Sankarasubramanian, A. AU - Sinha, T. A3 - NC Water Resources Research Institute DA - 2013/3// PY - 2013/3// M3 - Technical Report PB - NC Water Resources Research Institute ER - TY - RPRT TI - Improved Water Resources Sustainability utilizing Multi Time-scale Streamflow Forecasts AU - Sankarasubramanian, A. AU - Ranjithan, R.S. A3 - National Science Foundation DA - 2013/5// PY - 2013/5// M3 - Technical Report PB - National Science Foundation ER - TY - JOUR TI - Determining the limits of anaerobic co-digestion of thickened waste activated sludge with grease interceptor waste AU - Wang, Ling AU - Aziz, Tarek N AU - Francis, L T2 - Water research DA - 2013/// PY - 2013/// VL - 47 IS - 11 SP - 3835-3844 ER - TY - CHAP TI - Impacts of Climate Change and Variability on Water Resources in the Southeastern USA AU - Sun, G. AU - Caldwell, P.V. AU - Georgakakos, Aris P. AU - Cruise, James AU - McNider, Richard T. AU - Terando, Adam AU - Conrads, Paul A. AU - Feldt, John AU - Misra, Vasu AU - Romolo, Luigi AU - Rasmussen, Todd C. AU - McNulty, Steven G. AU - Marion, Daniel A. AU - Arumugam, Sankar AU - Covich, Alan T2 - Climate of the southeast United States : variability, change, impacts, and vulnerability A2 - Ingram, Keith A2 - Dow, Kristin A2 - Carter, Lynne A2 - Anderson, Julie A2 - Sommer, Eleanor K. T3 - NCA Regional Input Reports PY - 2013/// PB - Island Press ER - TY - JOUR TI - The use of broken power-laws to describe the distributions of daily flow above the mean annual flow across the conterminous U.S. AU - Segura, Catalina AU - Lazzati, Davide AU - Sankarasubramanian, Arumugam T2 - Journal of Hydrology AB - A recent study employed a broken power-law (BPL) distribution for understanding the scaling frequency of bankfull discharge in snowmelt-dominated basins. This study, grounded from those findings, investigated the ability of a BPL function to describe the distribution of daily flows above the mean annual flow in 1217 sites across the conterminous U.S. (CONUS). The hydrologic regime in all the sites is unregulated and spans a wide range in drainage areas (2–120,000 km2) and elevation (0–3000 m). Available daily flow records in all sites varied between 15 and 108 years. Comparing the performance of BPL distribution and the traditionally used lognormal distribution, we found that BPL provides stronger fit in ∼80% of the sites. Thus the BPL function provides a suitable tool to model daily flows in most areas of the CONUS. The potential for developing a model for predicting the frequency distribution of daily flows in ungauged sites was analyzed. We found that such model is possible using drainage area, mean basin elevation, and mean annual precipitation as predicting variables for any site located above 600 m across the CONUS. We also found strong continental-wide correlations between 3 of the 4 parameters that describe the BPL and basin characteristics. Our results indicate that the BPL function provides a robust alternative to traditional functions such as the lognormal to model the statistical variation of daily flows above the mean annual in most basins of the CONUS. DA - 2013/11// PY - 2013/11// DO - 10.1016/j.jhydrol.2013.09.016 VL - 505 SP - 35-46 J2 - Journal of Hydrology LA - en OP - SN - 0022-1694 UR - http://dx.doi.org/10.1016/j.jhydrol.2013.09.016 DB - Crossref KW - Stream flow distribution KW - Ungauged basins KW - Broken power law KW - Daily flows KW - Statistical description of flow distribution ER - TY - JOUR TI - Correction to Spatial and Temporal Trends in Lake Erie Hypoxia, 1987–2007 AU - Zhou, Yuntao AU - Obenour, Daniel R. AU - Scavia, Donald AU - Johengen, Thomas H. AU - Michalak, Anna M. T2 - Environmental Science & Technology AB - ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to Spatial and Temporal Trends in Lake Erie Hypoxia, 1987–2007Yuntao Zhou*†‡, Daniel R. Obenour‡§, Donald Scavia‡§∥, Thomas H. Johengen⊥, and Anna M. Michalak†View Author Information† Department of Global Ecology, Carnegie Institution for Science, Stanford, California 94305, United States ‡ Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States § School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan 48109, United States ∥ Graham Sustainability Institute, University of Michigan, Ann Arbor, Michigan 48103, United States ⊥ Cooperative Institute for Limnology and Ecosystems Research, School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan 48109, United States *E-mail: [email protected]; phone: (734) 709-3253; fax: (650) 462-5968.Cite this: Environ. Sci. Technol. 2013, 47, 9, 4958Publication Date (Web):April 23, 2013Publication History Published online23 April 2013Published inissue 7 May 2013https://doi.org/10.1021/es401561cCopyright © 2013 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views390Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (246 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts DA - 2013/4/23/ PY - 2013/4/23/ DO - 10.1021/ES401561C VL - 47 IS - 9 SP - 4958-4958 J2 - Environ. Sci. Technol. LA - en OP - SN - 0013-936X 1520-5851 UR - http://dx.doi.org/10.1021/ES401561C DB - Crossref ER - TY - JOUR TI - Mean and turbulent velocity fields near rigid and flexible plants and the implications for deposition AU - Ortiz, Alejandra C. AU - Ashton, Andrew AU - Nepf, Heidi T2 - Journal of Geophysical Research: Earth Surface AB - [1] The transport of fine sediment and organic matter plays an important role in the nutrient dynamics of shallow aquatic systems, and the fate of these particles is closely linked to vegetation. We describe the mean and turbulent flow near circular patches of synthetic vegetation and examine how the spatial distribution of flow is connected to the spatial distribution of suspended sediment deposition. Patches of rigid, emergent, and flexible, submerged vegetation were considered, with two different stem densities. For the rigid emergent vegetation, flow adjustment was primarily two-dimensional, with flow deflected in the horizontal plane. Horizontal shear layers produced a von Karman vortex street. Flow through the patch shifted the vortex street downstream, resulting in a region directly downstream of the patch in which both the mean and turbulent velocities were diminished. Net deposition was enhanced within this region. In contrast, for the flexible, submerged vegetation, flow adjustment was three-dimensional, with shear layers formed in the vertical and horizontal planes. Because of strong vertical circulation, turbulent kinetic energy was elevated directly downstream of the patch. Consistent with this, deposition was not enhanced at any point in the wake. This comparison suggests that morphological feedbacks differ between submerged and emergent vegetation. Further, enhanced deposition occurred only in regions where both turbulent and mean velocities were reduced, relative to the open channel. Reduced deposition (indicating enhanced resuspension) occurred in regions of high turbulence kinetic energy, regardless of local mean velocity. These observations highlight the importance of turbulence in controlling deposition. DA - 2013/12// PY - 2013/12// DO - 10.1002/2013JF002858 VL - 118 IS - 4 SP - 2585-2599 J2 - J. Geophys. Res. Earth Surf. LA - en OP - SN - 2169-9003 UR - http://dx.doi.org/10.1002/2013JF002858 DB - Crossref KW - sedimentation KW - vegetation KW - ecogeomorphology KW - velocity KW - turbulence ER - TY - CONF TI - A Complex Adaptive System Approach Assessing the Dynamics of Population Growth, Land Use, and Climate Change for Urban Water Resources Management AU - Lord, Benjamin AU - Zechman, Emily AU - Arumugam, Sankar T2 - World Environmental and Water Resources Congress 2013 AB - Urban water resources management requires careful planning to balance water supply and demand. Under increasing population growth and land use change through urbanization, water shortages may become increasingly frequent, and climate change can alter the availability and timing of water from expected levels. While long-term water supply planning is conventionally based on projections of population growth, demands, and system capacity under a stationary climate, the sustainability of water resources depends on the dynamic interactions among the environmental, technological, and social characteristics of the water system and local population. The response of consumers to water use regulations will affect future water availability, and to address the challenges of water resources management and provide insight to system dynamics a new modeling approach is needed that goes beyond simple assumptions about water availability, population growth, and demand increases, to explicitly incorporate the feedbacks among these systems and their impacts on water availability. A dynamic modeling approach is developed to provide insight about the supply-demand dynamics and feedbacks arising from urban growth dynamics, consumer behaviors, and potential changes in climate and land use. This research couples engineering and hydro-climatology models with complex adaptive system modeling techniques to assess the influence of social dynamics on water resources availability. Land use change is simulated using cellular automata modeling. Consumer adaptations of water demands and policy decisions about water restrictions are simulated using agent-based modeling. Watershed and reservoir simulation are implemented using the Soil Water Assessment Tool (SWAT) and integrated within a complex adaptive system simulation framework. This framework is developed for the Falls Lake Reservoir near Raleigh, North Carolina, to simulate the performance of alternative water shortage response plan and supply-side management scenarios under increased population and climate change scenarios. C2 - 2013/5/28/ C3 - World Environmental and Water Resources Congress 2013 CY - Cincinnati, Ohio DA - 2013/5/28/ PY - 2013/5/19/ DO - 10.1061/9780784412947.281 PB - American Society of Civil Engineers SN - 9780784412947 UR - http://dx.doi.org/10.1061/9780784412947.281 DB - Crossref ER - TY - CHAP TI - Improving the Convergence of Schwarz Methods for Helmholtz Equation AU - Guddati, Murthy N AU - Thirunavukkarasu, Senganal T2 - Lecture Notes in Computational Science and Engineering AB - Various domain decompositionmethods have been proposed for the Helmholtz equation, with the Optimized Schwarz Method (OSM) being one of them (see e.g. [7] for a review of various domain decomposition methods, and [3] for the details of OSM). In this paper, we focus on OSM, which is based on the idea of using approximated half-space Dirichlet-to-Neumann (DtN) maps to improve the convergence of the Schwarz methods; current version of the OSM is based on polynomial approximation of the half-space DtN map. See [8] for a review of various approaches to approximating the half-space DtN map (more commonly referred to as Absorbing Boundary Conditions (ABCs)). PY - 2013/// DO - 10.1007/978-3-642-35275-1_22 SP - 199-206 OP - PB - Springer Berlin Heidelberg SN - 9783642352744 9783642352751 UR - http://dx.doi.org/10.1007/978-3-642-35275-1_22 DB - Crossref ER - TY - JOUR TI - Evaluation of Life Cycle Assessment Recycling Allocation Methods AU - Johnson, Jeremiah X. AU - McMillan, Colin A. AU - Keoleian, Gregory A. T2 - Journal of Industrial Ecology AB - Summary Life cycle assessment practitioners struggle to accurately allocate environmental burdens of metals recycling, including the temporal dimension of environmental impacts. We analyze four approaches for calculating aluminum greenhouse gas emissions: the recycled content (RC) or cut‐off approach, which assumes that demand for recycled content displaces primary production; end‐of‐life recycling (EOLR), which assumes that postuse recycling displaces primary production; market‐based (MB) approaches, which estimate changes in supply and demand using price elasticities; and value‐corrected substitution (VCS), which allocates impact based on price differences between primary and recycled material. Our analysis suggests that applications of the VCS approach do not adequately account for the changing scrap to virgin material price ratio over time, whereas MB approaches do not address stock accumulation and depletion. The EOLR and RC approaches were analyzed using two case studies: U.S. aluminum beverage cans and vehicle engine blocks. These approaches produced similar results for beverage cans, which have a closed material loop system and a short product life. With longer product lifetimes, as noted with the engine blocks, the magnitude and timing of the emissions differs greatly between the RC and EOLR approaches. The EOLR approach indicates increased impacts at the time of production, offset by negative impacts in future years, whereas the RC approach assumes benefits to increased recycled content at the time of production. For vehicle engine blocks, emissions using EOLR are 140% higher than with RC. Results are highly sensitive to recycled content and future recycling rates, and the choice of allocation methods can have significant implications for life cycle studies. DA - 2013/9// PY - 2013/9// DO - 10.1111/jiec.12050 SP - n/a-n/a J2 - Journal of Industrial Ecology LA - en OP - SN - 1088-1980 UR - http://dx.doi.org/10.1111/jiec.12050 DB - Crossref KW - automobile KW - beverage cans KW - consequential LCA KW - industrial ecology KW - life cycle assessment (LCA) KW - metals ER - TY - JOUR TI - Improving startup performance with carbon mesh anodes in separator electrode assembly microbial fuel cells AU - Zhang, Fang AU - Xia, Xue AU - Luo, Yong AU - Sun, Dan AU - Call, Douglas F. AU - Logan, Bruce E. T2 - Bioresource Technology AB - In a separator electrode assembly microbial fuel cell, oxygen crossover from the cathode inhibits current generation by exoelectrogenic bacteria, resulting in poor reactor startup and performance. To determine the best approach for improving startup performance, the effect of acclimation to a low set potential (−0.2 V, versus standard hydrogen electrode) was compared to startup at a higher potential (+0.2 V) or no set potential, and inoculation with wastewater or pre-acclimated cultures. Anodes acclimated to −0.2 V produced the highest power of 1330 ± 60 mW m−2 for these different anode conditions, but unacclimated wastewater inocula produced inconsistent results despite the use of this set potential. By inoculating reactors with transferred cell suspensions, however, startup time was reduced and high power was consistently produced. These results show that pre-acclimation at −0.2 V consistently improves power production compared to use of a more positive potential or the lack of a set potential. DA - 2013/4// PY - 2013/4// DO - 10.1016/j.biortech.2013.01.036 VL - 133 SP - 74-81 J2 - Bioresource Technology LA - en OP - SN - 0960-8524 UR - http://dx.doi.org/10.1016/j.biortech.2013.01.036 DB - Crossref KW - Microbial fuel cell KW - Separator electrode assembly KW - Startup KW - Set anode potential KW - Inoculum ER - TY - CONF TI - Investigation of Cold-Formed Steel Wall Reinforcement Systems to Resist Progressive Collapse AU - Mohamed, Ismail AU - Rahman, Nabil A. AU - Seracino, R. T2 - Structures Congress 2013 AB - Building construction with cold-formed steel stud load-bearing walls has shown cost and construction time competiveness in military barracks projects compared to other construction material. The UFC 4-023-03 (2010) requires all new and existing military facilities of three stories or higher to be designed to avoid progressive collapse. The UFC 4-023-03 (2010) offers two general approaches: direct and indirect design. The direct design approach includes the Alternate Path method, which is based on flexural performance of the floor slab and the wall panel, as the building must bridge across removed vertical supporting elements. The indirect design approach includes the Tie Forces method. Applying progressive collapse design to steel stud bearing wall systems may necessitate an increase in the size and thickness of wall and floor framing members. Three framing components may be utilized to enhance the resistance to progressive collapse in case of wall section removal from the structure; the wall lateral bracing, the wall studs, and added tension straps. A nonlinear 3D static analysis was performed on cold formed steel stud bearing wall system to investigate the effectiveness of these framing components. It was observed that the collapse was mainly due to the global buckling of the studs adjacent to the removed wall section. However, the addition of tension straps redistributed the load of the lost wall section to the system and hence improved the resistance to progressive collapse. Adding double studs at each wall panel end delayed the global buckling of some studs. Improving the compression stiffness of the wall lateral bracing also contributed to increasing the resistance to progressive collapse. The study recommends finding a way to delay the global buckling failure mode of the studs to achieve the desired wall system resistance. C2 - 2013/4/30/ C3 - Structures Congress 2013 DA - 2013/4/30/ DO - 10.1061/9780784412848.085 PB - American Society of Civil Engineers SN - 9780784412848 UR - http://dx.doi.org/10.1061/9780784412848.085 DB - Crossref ER - TY - CONF TI - Leak Detection in Water Distribution Systems Using the Dividing Rectangles (DIRECT) Search AU - Jasper, Micah N. AU - Mahinthakumar, Gnanamanikam (Kumar) AU - Ranjithan, Sanmugavadivel (Ranji) AU - Brill, Earl Downey T2 - World Environmental and Water Resources Congress 2013 AB - Leak detection and management is an important problem in water distribution systems because it has been documented that up to 40% of the water may be lost to leaks in many aging systems. Small gradual leaks, which represent more than half of all leaks, are difficult to locate. Routinely measured pressure, flow, and water quality data in combination with a simulation-optimization inverse modeling approach could be used to characterize leakage. In this approach, the leak locations are found by minimizing the difference between real and simulated measurements for a known sensor configuration. Simulation-optimization approaches are computationally demanding because millions of simulations of a network simulator (e.g., EPANET) may be required to achieve a satisfactory solution. This problem is alleviated using a high-performance computing (HPC) framework that enables many parallel simulations of the water system using EPANET. This research is modifying an existing global search algorithm, called the Dividing Rectangles (DIRECT) Search that is traditionally used for continuous functions to enable parallel simulations and a mix of discrete variables (for leak locations) and continuous variables (for leak magnitudes). The modified algorithm is being tested with traditional continuous test functions, discrete test functions, and test water distribution networks. C2 - 2013/5/28/ C3 - World Environmental and Water Resources Congress 2013 DA - 2013/5/28/ DO - 10.1061/9780784412947.078 PB - American Society of Civil Engineers SN - 9780784412947 UR - http://dx.doi.org/10.1061/9780784412947.078 DB - Crossref ER - TY - CONF TI - A Sensitivity Analysis of Data Measurement Types for Leak Detection in Water Distribution Systems AU - Jasper, Micah N. AU - Mahinthakumar, Gnanamanikam (Kumar) AU - Ranjithan, Sanmugavadivel (Ranji) AU - Brill, Earl Downey T2 - World Environmental and Water Resources Congress 2013 AB - It is estimated that 15-40% of water is unaccounted for in urban water systems. This is mostly caused by small leaks, which are difficult to locate. Routinely measured pressure, flow, and water quality data can be used to locate leaks in the water network using an inverse modeling approach. For a known sensor configuration, the leak locations can be found by minimizing the difference between real and simulated measurements. However, when comparing measurement types (pressure, flow, or quality), some may be more sensitive to leak location than others. Furthermore, some measurement types may be more or less sensitive depending on the leak magnitude or the proximity of the leak to the sensors. The measurements types that are more sensitive to location will have a stronger signature and would need to be weighted more in an inverse modeling approach, especially in the presence of noise. Preliminary research suggests that water quality measurements are more sensitive to leak location when a leak is small, and that flow measurements are more sensitive when a leak is large. In this research, a series of sensitivity analyses are conducted on different networks to investigate the sensitivity of these measurements with respect to leak location, magnitude, and proximity of sensors to the leak location. C2 - 2013/5/28/ C3 - World Environmental and Water Resources Congress 2013 DA - 2013/5/28/ DO - 10.1061/9780784412947.059 PB - American Society of Civil Engineers SN - 9780784412947 UR - http://dx.doi.org/10.1061/9780784412947.059 DB - Crossref ER - TY - JOUR TI - Improved method of considering air void and asphalt content changes on long-term performance of asphalt concrete pavements AU - Zeiada, W.A. AU - Kaloush, K.E. AU - Underwood, B.S. AU - Mamlouk, M.E. T2 - International Journal of Pavement Engineering AB - Mixture properties (aggregate gradation and volumetric quantities), rate of loading and environmental conditions are the most important factors that affect the |E*| values. The main objective of this study was to develop a rational approach to investigate and model the effect of air voids and asphalt content on the |E*| master curves and consequently predict pavement performance. In this study, |E*| tests were conducted on three asphalt concrete mixtures with the same aggregate gradation, but different binder grades. For each of these mixtures, the air void and asphalt contents were varied at three levels. It is found that the developed method provides a more accurate estimate of the effects of volumetric changes in hot mix asphalt. The application of the proposed approach would be most beneficial for quality control/quality assurance purposes, performance-related specifications and for estimating contractors' incentives and penalties, where |E*| is utilised to predict the pavement performance. DA - 2013/11/20/ PY - 2013/11/20/ DO - 10.1080/10298436.2013.857775 VL - 15 IS - 8 SP - 718-730 J2 - International Journal of Pavement Engineering LA - en OP - SN - 1029-8436 1477-268X UR - http://dx.doi.org/10.1080/10298436.2013.857775 DB - Crossref KW - dynamic modulus (|E*|) KW - air voids KW - asphalt content KW - pavement KW - performance ER - TY - JOUR TI - A Discontinuous Galerkin Coupled Wave Propagation/Circulation Model AU - Meixner, Jessica AU - Dietrich, J. Casey AU - Dawson, Clint AU - Zijlema, Marcel AU - Holthuijsen, Leo H. T2 - Journal of Scientific Computing DA - 2013/8/8/ PY - 2013/8/8/ DO - 10.1007/s10915-013-9761-5 VL - 59 IS - 2 SP - 334-370 J2 - J Sci Comput LA - en OP - SN - 0885-7474 1573-7691 UR - http://dx.doi.org/10.1007/s10915-013-9761-5 DB - Crossref KW - Discontinuous Galerkin methods KW - Shallow water equations KW - Action balance equation KW - Coupled model KW - A priori error estimate ER - TY - JOUR TI - Risk, Regulation, and Rhetorical Boundaries: Claims and Challenges Surrounding a Purported Nuclear Renaissance AU - Kinsella, William J. AU - Kelly, Ashley R. AU - Kittle Autry, Meagan T2 - Communication Monographs AB - This study examines the efforts of individuals and advocacy groups seeking to influence a state utilities commission's decisions regarding a large corporate merger and a nuclear power construction project. Such local engagements have wider significance as the nuclear industry attempts to expand its role in the global energy economy. Utilizing participatory field work and analysis of public documents, we extend the concept of rhetorical boundary work by examining two challenges faced by opponents of the merger and the nuclear project. First, the utilities commission's regulatory mandate is limited to economic risks rather than environmental, health, and safety risks. Second, expert authority is consistently privileged over local, vernacular arguments. We explore the rhetorical negotiation of these boundaries and the effects produced. DA - 2013/9// PY - 2013/9// DO - 10.1080/03637751.2013.788253 VL - 80 IS - 3 SP - 278-301 J2 - Communication Monographs LA - en OP - SN - 0363-7751 1479-5787 UR - http://dx.doi.org/10.1080/03637751.2013.788253 DB - Crossref KW - Rhetorical Boundary Work KW - Risk Communication KW - Nuclear Renaissance KW - Regulatory Discourse KW - Regulation KW - Public Expertise ER - TY - JOUR TI - Mechanisms of post-supply contamination of drinking water in Bagamoyo, Tanzania AU - Harris, Angela R. AU - Davis, Jennifer AU - Boehm, Alexandria B. T2 - Journal of Water and Health AB - Access to household water connections remains low in sub-Saharan Africa, representing a public health concern. Previous studies have shown water stored in the home to be more contaminated than water at the source; however, the mechanisms of post-supply contamination remain unclear. Using water quality measurements and structured observations of households in Bagamoyo, Tanzania, this study elucidates the causal mechanisms of the microbial contamination of drinking water after collection from a communal water source. The study identifies statistically significant loadings of fecal indicator bacteria (FIB) occurring immediately after filling the storage container at the source and after extraction of the water from the container in the home. Statistically significant loadings of FIB also occur with various water extraction methods, including decanting from the container and use of a cup or ladle. Additionally, pathogenic genes of Escherichia coli were detected in stored drinking water but not in the source from which it was collected, highlighting the potential health risks of post-supply contamination. The results of the study confirm that storage containers and extraction utensils introduce microbial contamination into stored drinking water, and suggest that further research is needed to identify methods of water extraction that prevent microbial contamination of drinking water. DA - 2013/6/7/ PY - 2013/6/7/ DO - 10.2166/wh.2013.023 VL - 11 IS - 3 SP - 543-554 LA - en OP - SN - 1477-8920 1996-7829 UR - http://dx.doi.org/10.2166/wh.2013.023 DB - Crossref KW - diarrheal pathogens KW - drinking water quality KW - fecal bacteria KW - recontamination KW - Tanzania KW - waterborne disease ER - TY - SOUND TI - TED Talk: Sanitation is a Basic Human Right AU - Reyes, F.L., III DA - 2013/// PY - 2013/// UR - https://www.ted.com/talks/francis_de_los_reyes_sanitation_is_a_basic_human_right N1 - TED Talk at RN - TED Talk at ER - TY - CONF TI - Developing Resilient Anaerobic Co-digesting Microbial Communities AU - Wang, L. AU - Hossen, E.H. AU - Aziz, T.N. AU - Ducoste, J. AU - Bullard, M. AU - De Los Reyes, F.L. C2 - 2013/// C3 - 86th Annual Water Environment Federation Technical Exhibition and Conference, WEFTEC 2013 DA - 2013/// VL - 2 SP - 764-770 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85070513853&partnerID=MN8TOARS ER - TY - CONF TI - A numerical method to simulate and assess the formation of Fats, Oils & Grease (FOG) deposits in a sewer collection system AU - Yousefelahiyeh, R. AU - Dominic, C.C.S. AU - Ducoste, J. C2 - 2013/// C3 - 86th Annual Water Environment Federation Technical Exhibition and Conference, WEFTEC 2013 DA - 2013/// VL - 8 SP - 5063-5068 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84938671555&partnerID=MN8TOARS ER - TY - JOUR TI - An Insertion Rate Model for Pile Installation in Sand by Jetting AU - Gabr, M. A. AU - Borden, Roy H. AU - Denton, R. L. AU - Smith, Alex W. T2 - Geotechnical Testing Journal AB - The use of jetting is an approach to aid the installation of piles, especially in areas that have hard but relatively shallow subsurface soil layers. Jetting piles for a portion of their installation depth minimize their exposure to excessive driving stress and provide energy savings and noise reduction. However, the literature offers little information regarding the appropriate selection of jetting parameters, such as flow rate and jet velocity, which are needed to produce the desired installation times as a function of soil strength. This paper presents a model for estimating pile jetting parameters based on the results from laboratory and field testing. The model is based on an idealization of the applied shear stress that is produced by the jet as well as the soil resistance to pile insertion. The model is applied to 19 field installations where the jetted depths of the piles range from 10–34 ft. The field data yield ratios of 6–20 for the jet flow rate (Qw) to the rate of the pile volume insertion in terms of time (Qp), with the lower ratios associated with higher jet velocities. The proposed model yields an estimated Qw/Qp that is within +/− 20 % of the measured values. DA - 2013/10/29/ PY - 2013/10/29/ DO - 10.1520/gtj20120191 VL - 37 IS - 1 SP - 20120191 J2 - Geotech. Test. J. LA - en OP - SN - 0149-6115 UR - http://dx.doi.org/10.1520/GTJ20120191 DB - Crossref KW - construction KW - criteria KW - installation KW - jetting KW - piles KW - sand KW - strength KW - stiffness ER - TY - JOUR TI - Effects of metered entry volume on an oversaturated network with dynamic signal timing AU - Medina, J.C. AU - Hajbabaie, A. AU - Benekohal, R.F. T2 - Transportation Research Record AB - This paper analyzes the effects of different traffic metering levels at the entry points of a simulated signalized network to maintain efficient vehicle processing. Metering signals were placed along the network perimeter in advance of the bordering intersections to reduce the vehicle arrival rate and prevent oversaturation. In the simulation environment, traffic signals were externally controlled by independent agents using a learning algorithm based on approximate dynamic programming. Agents operated the signals in a cycle-free mode, reacting in real time to current demands and occupancy estimated from detectors placed at the entry and exit points of all links. The metering strategies were analyzed for delay, throughput, network congestion, and queue management. Results indicate that metering have a significant effect on network performance. Metering to levels just below the maximum throughput capacity of an intersection resulted in increased network throughput (up to 5%); reduced delay (up to 10.9%), including vehicles inside and those metered outside of the network; and queue lengths inside the network that allowed efficient use of green time. However, metering to points well below or above the capacity of an intersection did not always provide network improvements. This finding suggests that an optimal congestion level exists inside the network that can be achieved by a metering strategy. An analysis of the metering effects is presented in a case study, and field implementations and scenarios in which metering can be applied are discussed. DA - 2013/// PY - 2013/// DO - 10.3141/2356-07 VL - 2356 IS - 1 SP - 53-60 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84886571705&partnerID=MN8TOARS ER - TY - JOUR TI - Improving uncertainty estimation in urban hydrological modeling by statistically describing bias AU - Del Giudice, D. AU - Honti, M. AU - Scheidegger, A. AU - Albert, C. AU - Reichert, P. AU - Rieckermann, J. T2 - Hydrology and Earth System Sciences AB - Abstract. Hydrodynamic models are useful tools for urban water management. Unfortunately, it is still challenging to obtain accurate results and plausible uncertainty estimates when using these models. In particular, with the currently applied statistical techniques, flow predictions are usually overconfident and biased. In this study, we present a flexible and relatively efficient methodology (i) to obtain more reliable hydrological simulations in terms of coverage of validation data by the uncertainty bands and (ii) to separate prediction uncertainty into its components. Our approach acknowledges that urban drainage predictions are biased. This is mostly due to input errors and structural deficits of the model. We address this issue by describing model bias in a Bayesian framework. The bias becomes an autoregressive term additional to white measurement noise, the only error type accounted for in traditional uncertainty analysis. To allow for bigger discrepancies during wet weather, we make the variance of bias dependent on the input (rainfall) or/and output (runoff) of the system. Specifically, we present a structured approach to select, among five variants, the optimal bias description for a given urban or natural case study. We tested the methodology in a small monitored stormwater system described with a parsimonious model. Our results clearly show that flow simulations are much more reliable when bias is accounted for than when it is neglected. Furthermore, our probabilistic predictions can discriminate between three uncertainty contributions: parametric uncertainty, bias, and measurement errors. In our case study, the best performing bias description is the output-dependent bias using a log-sinh transformation of data and model results. The limitations of the framework presented are some ambiguity due to the subjective choice of priors for bias parameters and its inability to address the causes of model discrepancies. Further research should focus on quantifying and reducing the causes of bias by improving the model structure and propagating input uncertainty. DA - 2013/// PY - 2013/// DO - 10.5194/hess-17-4209-2013 VL - 17 IS - 10 SP - 4209-4225 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84887060034&partnerID=MN8TOARS ER - TY - JOUR TI - Dynamic time warping improves sewer flow monitoring AU - Dürrenmatt, D.J. AU - Del Giudice, D. AU - Rieckermann, J. T2 - Water Research AB - Successful management and control of wastewater and storm water systems requires accurate sewer flow measurements. Unfortunately, the harsh sewer environment and insufficient flow meter calibration often lead to inaccurate and biased data. In this paper, we improve sewer flow monitoring by creating redundant information on sewer velocity from natural wastewater tracers. Continuous water quality measurements upstream and downstream of a sewer section are used to estimate the travel time based on i) cross-correlation (XCORR) and ii) dynamic time warping (DTW). DTW is a modern data mining technique that warps two measured time series non-linearly in the time domain so that the dissimilarity between the two is minimized. It has not been applied in this context before. From numerical experiments we can show that DTW outperforms XCORR, because it provides more accurate velocity estimates, with an error of about 7% under typical conditions, at a higher temporal resolution. In addition, we can show that pre-processing of the data is important and that tracer reaction in the sewer reach is critical. As dispersion is generally small, the distance between the sensors is less influential if it is known precisely. Considering these findings, we tested the methods on a real-world sewer to check the performance of two different sewer flow meters based on temperature measurements. Here, we were able to detect that one of two flow meters was not performing satisfactorily under a variety of flow conditions. Although theoretical analyses show that XCORR and DTW velocity estimates contain systematic errors due to dispersion and reaction processes, these are usually small and do not limit the applicability of the approach. DA - 2013/// PY - 2013/// DO - 10.1016/j.watres.2013.03.051 VL - 47 IS - 11 SP - 3803-3816 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84878500847&partnerID=MN8TOARS KW - Dynamic time warping KW - Sensor diagnosis KW - Sewer flow monitoring KW - Signal processing ER - TY - JOUR TI - Development of Deduct Value Curves for the Pavement Condition Index of Asphalt Airfield Pavement AB - PURPOSES: This study is to develop the deduct value curves for the calculation of pavement condition index of asphalt airfield pavement. METHODS: To develop the deduct value curves of asphalt airfield pavement, panel rating was conducted to decide the pavement condition based on pavement distress type, severity, and density. RESULTS: Results show that standard deviation of deduct values by panel rating is increased at higher severity level and as damage density increases. The deduct value of alligator cracking show the highest. CONCLUSIONS: The deduct value curves based on panel rating could be used without existing problems which were occurred in Shahin's method. DA - 2013/6/17/ PY - 2013/6/17/ DO - 10.7855/ijhe.2013.15.3.037 UR - http://dx.doi.org/10.7855/ijhe.2013.15.3.037 ER - TY - CHAP TI - Development and Evaluation of an Air Quality Model for Predicting the Impacts of Prescribed Burns AU - Odman, M. Talat AU - Yano, Aika AU - Garcia-Menendez, Fernando AU - Hu, Yongtao AU - Goodrick, Scott L. AU - Liu, Yongqiang AU - Achtemeier, Gary L. T2 - Air Pollution Modeling and its Application XXII PY - 2013/5/7/ DO - 10.1007/978-94-007-5577-2_87 SP - 517-521 OP - PB - Springer Netherlands SN - 9789400755765 9789400755772 UR - http://dx.doi.org/10.1007/978-94-007-5577-2_87 DB - Crossref KW - Burns KW - PM 2.5 KW - WRF ER - TY - JOUR TI - U.S. IOOS coastal and ocean modeling testbed: Evaluation of tide, wave, and hurricane surge response sensitivities to mesh resolution and friction in the Gulf of Mexico AU - Kerr, P. C. AU - Martyr, R. C. AU - Donahue, A. S. AU - Hope, M. E. AU - Westerink, J. J. AU - Luettich, R. A., Jr. AU - Kennedy, A. B. AU - Dietrich, J. C. AU - Dawson, C. AU - Westerink, H. J. T2 - Journal of Geophysical Research: Oceans AB - This paper investigates model response sensitivities to mesh resolution, topographical details, bottom friction formulations, the interaction of wind waves and circulation, and nonlinear advection on tidal and hurricane surge and wave processes at the basin, shelf, wetland, and coastal channel scales within the Gulf of Mexico. Tides in the Gulf of Mexico are modestly energetic processes, whereas hurricane surge and waves are highly energetic. The unstructured‐mesh, coupled wind‐wave and circulation modeling system, SWAN+ADCIRC, is implemented to generate modeled tidal harmonic constituents and hurricane waves and surge for a Hurricane Ike (2008) hindcast. In the open ocean, mesh resolution requirements are less stringent in achieving accurate tidal signals or matching hurricane surge and wave responses; however, coarser resolution or the absence of intertidal zones decreases accuracy along protected nearshore and inland coastal areas due to improper conveyance and/or lateral attenuation. Bottom friction formulations are shown to have little impact on tidal signal accuracy, but hurricane surge is much more sensitive, especially in shelf waters, where development of a strong shore‐parallel current is essential to the development of Ike's geostrophic setup. The spatial and temporal contributions of wave radiation stress gradients and nonlinear advection were charted for Ike. Nonlinear advection improves model performance by capturing an additional 10–20 cm of geostrophic setup and increasing resonant cross‐shelf waves by 30–40 cm. Wave radiation stress gradients improve performance at coastal stations by adding an extra 20–40 cm to water levels. DA - 2013/9// PY - 2013/9// DO - 10.1002/jgrc.20305 VL - 118 IS - 9 SP - 4633-4661 J2 - J. Geophys. Res. Oceans LA - en OP - SN - 2169-9275 UR - http://dx.doi.org/10.1002/jgrc.20305 DB - Crossref KW - bottom friction KW - grid resolution KW - tides KW - storm surge KW - waves KW - advection ER - TY - JOUR TI - The surge standard for "events of Katrina magnitude" AU - Kennedy, Andrew Brian AU - Dietrich, Joel Casey AU - Westerink, Joannes J. T2 - Proceedings of the National Academy of Sciences of the United States of America AB - Hurricane Katrina was historic in magnitude. From ref. 1: “The large size of Katrina throughout its history, combined with the extreme waves generated during its most intense phase, enabled this storm to produce the largest storm surges (reliable observations up to 28 ft) that have ever been observed within the Gulf of Mexico, as determined from analyses of historical records.” The analysis by Grinsted et al. (2) of the effects of rising temperatures on the frequency of Atlantic hurricane surge invokes “events of Katrina magnitude” as a standard by which other events are judged. However, we believe the Katrina benchmark, as used, is seriously flawed, in large part because the tide gauge spatial resolution used was so coarse that none of the locations forming the index ever experienced a true surge event of Katrina magnitude. This casts doubt on the claim that Katrina-level surge events may occur many times per decade by the late 21st century. DA - 2013/// PY - 2013/// DO - 10.1073/pnas.1305960110 VL - 110 IS - 29 SP - E2665-E2666 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000322086100003&KeyUID=WOS:000322086100003 ER - TY - JOUR TI - Surge Generation Mechanisms in the Lower Mississippi River and Discharge Dependency AU - Kerr, P. C. AU - Westerink, J. J. AU - Dietrich, J. C. AU - Martyr, R. C. AU - Tanaka, S. AU - Resio, D. T. AU - Smith, J. M. AU - Westerink, H. J. AU - Westerink, L. G. AU - Wamsley, T. AU - van Ledden, M. AU - de Jong, W. T2 - Journal of Waterway, Port, Coastal, and Ocean Engineering AB - The Lower Mississippi River protrudes into the Gulf of Mexico, and manmade levees line only the west bank for 55 km of the Lower Plaquemines section. Historically, sustained easterly winds from hurricanes have directed surge across Breton Sound, into the Mississippi River and against its west bank levee, allowing for surge to build and then propagate efficiently upriver and thus increase water levels past New Orleans. This case study applies a new and extensively validated basin- to channel-scale, high-resolution, unstructured-mesh ADvanced CIRCulation model to simulate a suite of historical and hypothetical storms under low to high river discharges. The results show that during hurricanes, (1) total water levels in the lower river south of Pointe à La Hache are only weakly dependent on river flow, and easterly wind-driven storm surge is generated on top of existing ambient strongly flow-dependent river stages, so the surge that propagates upriver reduces with increasing river flow; (2) natural levees and adjacent wetlands on the east and west banks in the Lower Plaquemines capture storm surge in the river, although not as effectively as the manmade levees on the west bank; and (3) the lowering of manmade levees along this Lower Plaquemines river section to their natural state, to allow storm surge to partially pass across the Mississippi River, will decrease storm surge upriver by 1 to 2 m between Pointe à La Hache and New Orleans, independent of river flow. DA - 2013/7// PY - 2013/7// DO - 10.1061/(ASCE)WW.1943-5460.0000185 VL - 139 IS - 4 SP - 326-335 J2 - J. Waterway, Port, Coastal, Ocean Eng. LA - en OP - SN - 0733-950X 1943-5460 UR - http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000185 DB - Crossref KW - Levees and dikes KW - Storm surges KW - Floods KW - Louisiana KW - Mississippi River KW - Hurricanes KW - Water discharge KW - Levee design KW - Storm surge KW - River stage KW - Flooding KW - Southeastern Louisiana KW - Mississippi River KW - ADCIRC KW - Surge propagation KW - Surge attenuation KW - Hurricane Katrina ER - TY - JOUR TI - Simulating Hurricane Storm Surge in the Lower Mississippi River under Varying Flow Conditions AU - Martyr, R. C. AU - Dietrich, J. C. AU - Westerink, J. J. AU - Kerr, P. C. AU - Dawson, C. AU - Smith, J. M. AU - Pourtaheri, H. AU - Powell, N. AU - Van Ledden, M. AU - Tanaka, S. AU - Roberts, H. J. AU - Westerink, H. J. AU - Westerink, L. G. T2 - Journal of Hydraulic Engineering AB - Hurricanes in southeastern Louisiana develop significant surges within the lower Mississippi River. Storms with strong sustained easterly winds push water into shallow Breton Sound, overtop the river’s east bank south of Pointe à la Hache, Louisiana, penetrate into the river, and are confined by levees on the west bank. The main channel’s width and depth allow surge to propagate rapidly and efficiently up river. This work refines the high-resolution, unstructured mesh, wave current Simulating Waves Nearshore + Advanced Circulation (SWAN+ADCIRC) SL16 model to simulate river flow and hurricane-driven surge within the Mississippi River. A river velocity regime–based variation in bottom friction and a temporally variable riverine flow-driven radiation boundary condition are essential to accurately model these processes for high and/or time-varying flows. The coupled modeling system is validated for riverine flow stage relationships, flow distributions within the distributary systems, tides, and Hurricane Gustav (2008) riverine surges. DA - 2013/5// PY - 2013/5// DO - 10.1061/(asce)hy.1943-7900.0000699 VL - 139 IS - 5 SP - 492-501 J2 - J. Hydraul. Eng. LA - en OP - SN - 0733-9429 1943-7900 UR - http://dx.doi.org/10.1061/(ASCE)HY.1943-7900.0000699 DB - Crossref KW - Storm surge KW - Mississippi River KW - Hurricanes KW - Rivers KW - Hydrodynamics KW - Numerical models KW - Storm surge generation KW - Propagation and attenuation ER - TY - CHAP TI - Real-Time Forecasting and Visualization of Hurricane Waves and Storm Surge Using SWAN+ADCIRC and FigureGen AU - Dietrich, J. C. AU - Dawson, C. N. AU - Proft, J. M. AU - Howard, M. T. AU - Wells, G. AU - Fleming, J. G. AU - Luettich, R. A. AU - Westerink, J. J. AU - Cobell, Z. AU - Vitse, M. AU - Lander, H. AU - Blanton, B. O. AU - Szpilka, C. M. AU - Atkinson, J. H. AU - Dawson, C AU - Gerritsen, M T2 - Computational Challenges in the Geosciences AB - Storm surge due to hurricanes and tropical storms can result in significant loss of life, property damage, and long-term damage to coastal ecosystems and landscapes. Computer modeling of storm surge is useful for two primary purposes: forecasting of storm impacts for response planning, particularly the evacuation of vulnerable coastal populations; and hindcasting of storms for determining risk, development of mitigation strategies, coastal restoration, and sustainability. Model results must be communicated quickly and effectively, to provide context about the magnitudes and locations of the maximum waves and surges in time for meaningful actions to be taken in the impact region before a storm strikes.In this paper, we present an overview of the SWAN + ADCIRC modeling system for coastal waves and circulation. We also describe FigureGen, a graphics program adapted to visualize hurricane waves and storm surge as computed by these models. The system was applied recently to forecast Hurricane Isaac (2012) as it made landfall in southern Louisiana. Model results are shown to be an accurate warning of the impacts of waves and circulation along the northern Gulf coastline, especially when communicated to emergency managers as geo-referenced images. PY - 2013/// DO - 10.1007/978-1-4614-7434-0_3 VL - 156 SP - 49-70 OP - PB - Springer New York SN - 9781461474333 9781461474340 UR - http://dx.doi.org/10.1007/978-1-4614-7434-0_3 DB - Crossref KW - Hurricane waves KW - Storm surge KW - Hurricane Isaac (2012) KW - ASGS KW - SWAN KW - ADCIRC KW - FigureGen ER - TY - JOUR TI - Limiters for spectral propagation velocities in SWAN AU - Dietrich, J.C. AU - Zijlema, M. AU - Allier, P.-E. AU - Holthuijsen, L.H. AU - Booij, N. AU - Meixner, J.D. AU - Proft, J.K. AU - Dawson, C.N. AU - Bender, C.J. AU - Naimaster, A. AU - Smith, J.M. AU - Westerink, J.J. T2 - Ocean Modelling AB - As phase-averaged spectral wave models continue to grow in sophistication, they are applied more frequently throughout the ocean, from the generation of waves in deep water to their dissipation in the nearshore. Mesh spacings are varied within the computational domain, either through the use of nested, structured meshes or a single, unstructured mesh. This approach is economical, but it can cause accuracy errors in regions where the input parameters are under-resolved. For instance, in regions with a coarse representation of bathymetry, refraction can focus excessive wave energy at a single mesh vertex, causing the computed solution to become non-physical. Limiters based on the Courant–Friedrichs–Lewy (CFL) criteria are proposed for the spectral propagation (refraction and frequency shifting) velocities in SWAN. These limiters are not required for model stability, but they improve accuracy by reducing local errors that would otherwise spread throughout the computational domain. As demonstrated on test cases in deep and shallow water, these limiters prevent the excessive directional turning and frequency shifting of wave energy and control the largest errors in under-resolved regions. DA - 2013/10// PY - 2013/10// DO - 10.1016/j.ocemod.2012.11.005 VL - 70 SP - 85-102 J2 - Ocean Modelling LA - en OP - SN - 1463-5003 UR - http://dx.doi.org/10.1016/j.ocemod.2012.11.005 DB - Crossref KW - Wave-current interaction KW - Refraction KW - SWAN KW - Numerical accuracy ER - TY - JOUR TI - Hindcast and validation of Hurricane Ike (2008) waves, forerunner, and storm surge AU - Hope, M. E. AU - Westerink, J. J. AU - Kennedy, A. B. AU - Kerr, P. C. AU - Dietrich, J. C. AU - Dawson, C. AU - Bender, C. J. AU - Smith, J. M. AU - Jensen, R. E. AU - Zijlema, M. AU - Holthuijsen, L. H. AU - Luettich, R. A., Jr. AU - Powell, M. D. AU - Cardone, V. J. AU - Cox, A. T. AU - Pourtaheri, H. AU - Roberts, H. J. AU - Atkinson, J. H. AU - Tanaka, S. AU - Westerink, H. J. AU - Westerink, L. G. T2 - Journal of Geophysical Research: Oceans AB - Hurricane Ike (2008) made landfall near Galveston, Texas, as a moderate intensity storm. Its large wind field in conjunction with the Louisiana‐Texas coastline's broad shelf and large scale concave geometry generated waves and surge that impacted over 1000 km of coastline. Ike's complex and varied wave and surge response physics included: the capture of surge by the protruding Mississippi River Delta; the strong influence of wave radiation stress gradients on the Delta adjacent to the shelf break; the development of strong wind driven shore‐parallel currents and the associated geostrophic setup; the forced early rise of water in coastal bays and lakes facilitating inland surge penetration; the propagation of a free wave along the southern Texas shelf; shore‐normal peak wind‐driven surge; and resonant and reflected long waves across a wide continental shelf. Preexisting and rapidly deployed instrumentation provided the most comprehensive hurricane response data of any previous hurricane. More than 94 wave parameter time histories, 523 water level time histories, and 206 high water marks were collected throughout the Gulf in deep water, along the nearshore, and up to 65 km inland. Ike's highly varied physics were simulated using SWAN + ADCIRC, a tightly coupled wave and circulation model, on SL18TX33, a new unstructured mesh of the Gulf of Mexico, Caribbean Sea, and western Atlantic Ocean with high resolution of the Gulf's coastal floodplain from Alabama to the Texas‐Mexico border. A comprehensive validation was made of the model's ability to capture the varied physics in the system. DA - 2013/9// PY - 2013/9// DO - 10.1002/jgrc.20314 VL - 118 IS - 9 SP - 4424-4460 J2 - J. Geophys. Res. Oceans LA - en OP - SN - 2169-9275 UR - http://dx.doi.org/10.1002/jgrc.20314 DB - Crossref KW - Hurricane Ike KW - Louisiana-Texas shelf KW - storm surge KW - waves KW - hurricane forerunner KW - SWAN plus ADCIRC ER - TY - JOUR TI - Air Quality and Climate Impacts Due to CNG Conversion of Motor Vehicles in Dhaka, Bangladesh AU - Wadud, Zia AU - Khan, Tanzila T2 - Environmental Science & Technology AB - Dhaka had recently experienced rapid conversion of its motor vehicle fleet to run on compressed natural gas (CNG). This paper quantifies ex-post the air quality and climate benefits of the CNG conversion policy, including monetary valuations, through an impact pathway approach. Around 2045 (1665) avoided premature deaths in greater Dhaka (City Corporation) can be attributed to air quality improvements from the CNG conversion policy in 2010, resulting in a saving of around USD 400 million. Majority of these health benefits resulted from the conversion of high-emitting diesel vehicles. CNG conversion was clearly detrimental from climate change perspective using the changes in CO2 and CH4 only (CH4 emissions increased); however, after considering other global pollutants (especially black carbon), the climate impact was ambiguous. Uncertainty assessment using input distributions and Monte Carlo simulation along with a sensitivity analysis show that large uncertainties remain for climate impacts. For our most likely estimate, there were some climate costs, valued at USD 17.7 million, which is an order of magnitude smaller than the air quality benefits. This indicates that such policies can and should be undertaken on the grounds of improving local air pollution alone and that precautions should be taken to reduce the potentially unintended increases in GHG emissions or other unintended effects. DA - 2013/// PY - 2013/// DO - 10.1021/es402338b VL - 47 IS - 24 SP - 13907-13916 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84890672548&partnerID=MN8TOARS ER - TY - JOUR TI - Effects of Powdered Kenaf Supplementation on the Performance of Lab-Scale Activated Sludge Reactors AU - Hurley, Forrest James AU - Reyes, Francis L. T2 - proc water environ fed AB - Effects of Powdered Kenaf Supplementation on the Performance of Lab-Scale Activated Sludge ReactorsA porous powder of dried kenaf (plant), when added to mixed liquor (ML), might provide submerged surface area for biofilm development within suspended growth WWTPs, which could improve plant performance without costly modifications. The performance of bench-top sequencing batch reactors, fed municipal wastewater and carrying out enhanced biological nutrient removal was compared. Kenaf powder was...Author(s)Forrest James HurleyFrancis L. de los ReyesSourceProceedings of the Water Environment FederationDocument typeConference PaperPublisherWater Environment FederationPrint publication date Oct, 2013ISSN1938-6478DOI10.2175/193864713813692667Volume / Issue2013 / 10Content sourceWEFTECCopyright2013Word count162 DA - 2013/1/1/ PY - 2013/1/1/ DO - 10.2175/193864713813692667 VL - 2013 IS - 10 SP - 5125-5131 ER - TY - JOUR TI - Developing Resilient Anaerobic Co-digesting Microbial Communities AU - Wang, Ling AU - Hossen, Elvin H. AU - Aziz, Tarek N. AU - Ducoste, Joel AU - Bullard, Michael AU - Reyes, Francis L. T2 - proc water environ fed AB - Developing Resilient Anaerobic Co-digesting Microbial CommunitiesAnaerobic co-digestion of thickened waste activated sludge (TWAS) with grease interceptor waste (GIW) was conducted in two 8L lab scale semi-continuous digesters. GIW contains the entire contents of a grease interceptor (GI) including fat, oil, and grease (FOG), food residuals, and associated wastewater. The treated digester was spiked with periodic perturbations of GIW contributing to 60% (w/w)...Author(s)Ling WangElvin H. HossenTarek N. AzizJoel DucosteMichael BullardFrancis L. de los ReyesSourceProceedings of the Water Environment FederationDocument typeConference PaperPublisherWater Environment FederationPrint publication date Oct, 2013ISSN1938-6478DOI10.2175/193864713813667953Volume / Issue2013 / 18Content sourceWEFTECCopyright2013Word count143 DA - 2013/1/1/ PY - 2013/1/1/ DO - 10.2175/193864713813667953 VL - 2013 IS - 18 SP - 771-777 ER - TY - JOUR TI - Spatial and Temporal Trends in Lake Erie Hypoxia, 1987–2007 AU - Zhou, Yuntao AU - Obenour, Daniel R. AU - Scavia, Donald AU - Johengen, Thomas H. AU - Michalak, Anna M. T2 - Environmental Science & Technology AB - Hypoxic conditions, defined as dissolved oxygen (DO) concentrations below 2 mg/L, are a regular summertime occurrence in Lake Erie, but the spatial extent has been poorly understood due to sparse sampling. We use geostatistical kriging and conditional realizations to provide quantitative estimates of the extent of hypoxia in the central basin of Lake Erie for August and September of 1987 to 2007, along with their associated uncertainties. The applied geostatistical approach combines the limited in situ DO measurements with auxiliary data selected using the Bayesian Information Criterion. Bathymetry and longitude are found to be highly significant in explaining the spatial distribution of DO, while satellite observations of sea surface temperature and satellite chlorophyll are not. The hypoxic extent was generally lowest in the mid-1990s, with the late 1980s (1987, 1988) and the 2000s (2003, 2005) experiencing the largest hypoxic zones. A simple exponential relationship based on the squared average measured bottom DO explains 97% of the estimated variability in the hypoxic extent. The change in the observed maximum extent between August and September is found to be sensitive to the corresponding variability in the hypolimnion thickness. DA - 2013/1/3/ PY - 2013/1/3/ DO - 10.1021/es303401b VL - 47 IS - 2 SP - 899-905 J2 - Environ. Sci. Technol. LA - en OP - SN - 0013-936X 1520-5851 UR - http://dx.doi.org/10.1021/es303401b DB - Crossref ER - TY - JOUR TI - Retrospective Analysis of Midsummer Hypoxic Area and Volume in the Northern Gulf of Mexico, 1985–2011 AU - Obenour, Daniel R. AU - Scavia, Donald AU - Rabalais, Nancy N. AU - Turner, R. Eugene AU - Michalak, Anna M. T2 - Environmental Science & Technology AB - Robust estimates of hypoxic extent (both area and volume) are important for assessing the impacts of low dissolved oxygen on aquatic ecosystems at large spatial scales. Such estimates are also important for calibrating models linking hypoxia to causal factors, such as nutrient loading and stratification, and for informing management decisions. In this study, we develop a rigorous geostatistical modeling framework to estimate the hypoxic extent in the northern Gulf of Mexico from data collected during midsummer, quasi-synoptic monitoring cruises (1985-2011). Instead of a traditional interpolation-based approach, we use a simulation-based approach that yields more robust extent estimates and quantified uncertainty. The modeling framework also makes use of covariate information (i.e., trend variables such as depth and spatial position), to reduce estimation uncertainty. Furthermore, adjustments are made to account for observational bias resulting from the use of different sampling instruments in different years. Our results suggest an increasing trend in hypoxic layer thickness (p = 0.05) from 1985 to 2011, but less than significant increases in volume (p = 0.12) and area (p = 0.42). The uncertainties in the extent estimates vary with sampling network coverage and instrument type, and generally decrease over the study period. DA - 2013/8/14/ PY - 2013/8/14/ DO - 10.1021/ES400983G VL - 47 IS - 17 SP - 9808-9815 J2 - Environ. Sci. Technol. LA - en OP - SN - 0013-936X 1520-5851 UR - http://dx.doi.org/10.1021/ES400983G DB - Crossref ER - TY - JOUR TI - A Scenario and Forecast Model for Gulf of Mexico Hypoxic Area and Volume AU - Scavia, Donald AU - Evans, Mary Anne AU - Obenour, Daniel R. T2 - Environmental Science & Technology AB - For almost three decades, the relative size of the hypoxic region on the Louisiana-Texas continental shelf has drawn scientific and policy attention. During that time, both simple and complex models have been used to explore hypoxia dynamics and to provide management guidance relating the size of the hypoxic zone to key drivers. Throughout much of that development, analyses had to accommodate an apparent change in hypoxic sensitivity to loads and often cull observations due to anomalous meteorological conditions. Here, we describe an adaptation of our earlier, simple biophysical model, calibrated to revised hypoxic area estimates and new hypoxic volume estimates through Bayesian estimation. This application eliminates the need to cull observations and provides revised hypoxic extent estimates with uncertainties corresponding to different nutrient loading reduction scenarios. We compare guidance from this model application, suggesting an approximately 62% nutrient loading reduction is required to reduce Gulf hypoxia to the Action Plan goal of 5000 km2, to that of previous applications. In addition, we describe for the first time, the corresponding response of hypoxic volume. We also analyze model results to test for increasing system sensitivity to hypoxia formation, but find no strong evidence of such change. DA - 2013/9/17/ PY - 2013/9/17/ DO - 10.1021/ES4025035 VL - 47 IS - 18 SP - 10423-10428 J2 - Environ. Sci. Technol. LA - en OP - SN - 0013-936X 1520-5851 UR - http://dx.doi.org/10.1021/ES4025035 DB - Crossref ER - TY - CONF TI - Use of pavement models to evaluate impacts of RAP in pavement construction AU - Underwood, B.S. C2 - 2013/// C3 - 2013 Airfield and Highway Pavements Conference DA - 2013/// ER - TY - CONF TI - Sustainable construction practices AU - Underwood, B.S. AU - El Asmar, M. C2 - 2013/// C3 - 2013 Arizona Pavements/Materials Conference DA - 2013/// ER - TY - CONF TI - Nonlinear viscoelastic behavior of asphalt concrete and its implication on fatigue modeling AU - Underwood, B.S. AU - Kim, Y.R. C2 - 2013/// C3 - 92nd Annual Meeting of the Transportation Research Record DA - 2013/// ER - TY - JOUR TI - Microstructural association model for upscaling prediction of asphalt concrete dynamic modulus AU - Underwood, B.S. AU - Krim, Y.R. T2 - Journal of Materials in Civil Engineering DA - 2013/// PY - 2013/// IS - 9 SP - 1153-1161 ER - TY - CONF TI - Micromechanical modeling of particle concentration effect in asphalt mastic to consider physico-chemical interaction AU - Underwood, B.S. AU - Kim, Y.R. C2 - 2013/// C3 - 2013 Petersen Asphalt Research Conference DA - 2013/// ER - TY - CONF TI - Mechanistic behaviors of fine aggregate matrix and its relation to asphalt mixture behaviors AU - Underwood, B.S. AU - Kim, Y.R. C2 - 2013/// C3 - 2013 Airfield and Highway Pavements Conference DA - 2013/// ER - TY - CONF TI - Evaluation of in-situ RAP binder interaction in asphalt cement composites AU - Underwood, B.S. AU - Gundla, A. C2 - 2013/// C3 - 4th International Conference on Asphalt Materials DA - 2013/// ER - TY - CONF TI - Emerging methods of asphalt concrete mixture and pavement analysis AU - Underwood, B.S. C2 - 2013/// C3 - 2013 Roads and Streets Conference DA - 2013/// ER - TY - CONF TI - Effect of air voids and asphalt content on fatigue damage using the viscoelastic continuum damage analysis AU - Zeiada, W.A. AU - Kaloush, K.E. AU - Underwood, B.S. AU - Mamlouk, M.S. AB - In this study, a laboratory experimental program was conducted to investigate the effect of asphalt content and air voids on the material properties and fatigue performance characteristics of asphalt concrete mixtures. Two levels of asphalt content (4.2 and 5.2%) and air voids (4.5 and 9.5%) were considered to produce four asphalt concrete mixture combinations. The advanced material characterization tests included dynamic (complex) modulus for stiffness evaluation and the uniaxial tension-compression for fatigue assessment. The fatigue analysis was performed for each mixture using the simplified viscoelastic continuum damage (S-VECD) approach. The damage characteristic (C-S) curves were established for each of the four mixtures. To have more useful information about the fatigue resistance of the four mixtures, the C-S curves were used to obtain the fatigue relationships by performing simulated predictions of the fatigue life at specific conditions. It is found that the S-VECD simulations are able to reflect the observed material trends. Simulations performed with this model also suggest that the impact of air void and asphalt content changes differ between stress-controlled and strain-controlled loading. The quantification of these differences may have implications in both pavement and material analysis and design. C2 - 2013/// C3 - Proceedings 2013 Airfield and Highway Pavements Conference DA - 2013/// DO - 10.1061/9780784413005.094 ER - TY - JOUR TI - Fires and air AU - Odman, M. T. AU - Hu, Y. AU - Garcia-Menendez, F. AU - Davis, A. Y. AU - Chang, M. E. AU - Russell, A. G. T2 - EM, The Magazine for Environmental Managers DA - 2013/// PY - 2013/// VL - November SP - 12-21 ER - TY - JOUR TI - Microfluidically switched frequency-reconfigurable slot antennas AU - King, A. J. AU - Patrick, J. F. AU - Sottos, N. R. AU - White, S. R. AU - Huff, G. H. AU - Bernhard, J. T. T2 - IEEE Antennas and Wireless Propagation Letters AB - This letter proposes a concept for frequency-reconfigurable slot antennas enabled by pressure-driven capacitive microfluidic switches. The switches are operated by pneumatically displacing a plug of eutectic gallium indium alloy (EGaIn) within an air-filled microchannel that traverses the slot orthogonally. Frequency reconfigurability is achieved by altering the displacement of conductive fluid within the channel, which reactively loads the slot. A transmission-line model is developed to capture the physical behavior of the fluid channel, and measurements are provided that show good agreement with the behavior of the model. DA - 2013/// PY - 2013/// DO - 10.1109/lawp.2013.2270940 VL - 12 SP - 828-831 ER - TY - JOUR TI - Simulating smoke transport from wildland fires with a regional-scale air quality model: Sensitivity to uncertain wind fields AU - Garcia-Menendez, Fernando AU - Hu, Yongtao AU - Odman, Mehmet Talat T2 - Journal of Geophysical Research: Atmospheres AB - Abstract Uncertainties associated with meteorological inputs which are propagated through atmospheric chemical transport models may constrain their ability to replicate the effects of wildland fires on air quality. Here, we investigate the sensitivity of predicted fine particulate matter (PM 2.5 ) levels to uncertain wind fields by simulating the air quality impacts of two fires on an urban area with the Community Multiscale Air Quality modeling system (CMAQ). Brute‐force sensitivity analyses show that modeled concentrations at receptors downwind from the fires are highly sensitive to variations in wind speed and direction. Additionally, uncertainty in wind fields produced with the Weather Research and Forecasting model was assessed by evaluating meteorological predictions against surface and upper air observations. Significant differences between predicted and observed wind fields were identified. Simulated PM 2.5 concentrations at urban sites displayed large sensitivities to wind perturbations within the error range of meteorological inputs. The analyses demonstrate that normalized errors in CMAQ predictions attempting to model the regional impacts of fires on PM 2.5 levels could be as high as 100% due to inaccuracies in wind data. Meteorological drivers may largely account for the considerable discrepancies between monitoring site observations and predicted concentrations. The results of this study demonstrate that limitations in fire‐related air quality simulations cannot be overcome by solely improving emission rates. DA - 2013/6/21/ PY - 2013/6/21/ DO - 10.1002/jgrd.50524 VL - 118 IS - 12 SP - 6493-6504 J2 - J. Geophys. Res. Atmos. LA - en OP - SN - 2169-897X UR - http://dx.doi.org/10.1002/jgrd.50524 DB - Crossref KW - CMAQ KW - WRF KW - fire emissions KW - PM2 KW - 5 KW - wind ER - TY - JOUR TI - Safety risk management for electrical transmission and distribution line construction AU - Albert, Alex AU - Hallowell, Matthew R. T2 - SAFETY SCIENCE AB - Prior research has established that electrical contractors involved in the construction and maintenance of electrical transmission and distribution (T&D) lines are at extremely high risk of electrocution. The result of inadvertent contact with T&D lines often is death or severe injury that involves damage to internal organs, musculoskeletal disorders, neurological damages and severe burns. The Electrical Safety Foundation International has demonstrated that contact with overhead power lines has been the single largest cause of electrical fatalities over the last decade. To reduce this disproportionate injury rate, electrical contractors implement many strategies such as the use of rubber insulating equipment, and locking devices. Unfortunately, these strategies are often cost-prohibitive in certain construction and maintenance scenarios. Therefore, electrical contractors are faced with complex decisions that involve comparing the cost of injury prevention with the expected safety benefit. This paper presents research that objectively evaluated the risk associated with common T&D construction tasks and the effectiveness of specific injury prevention techniques. The research team then developed a decision support framework that provides electrical contractors with objective safety and cost feedback given specific project characteristics. The results indicate that many of the effective strategies implemented to reduce T&D electrical injuries are very costly (e.g., de-energizing lines). Consequently, under most conditions, the costs of injury prevention far outweigh the cost savings associated with the reduction of injury rates. The implication of these findings is that T&D electrical contractors must highly value the non-monetary benefits of injury prevention in order to improve safety in their sector. DA - 2013/1// PY - 2013/1// DO - 10.1016/j.ssci.2012.06.011 VL - 51 IS - 1 SP - 118-126 SN - 1879-1042 KW - Occupational safety KW - Risk management KW - Injury prevention KW - Electrical transmission and distribution ER - TY - JOUR TI - Revamping Occupational Safety and Health Training: Integrating Andragogical Principles for the Adult Learner AU - Albert, Alex AU - Hallowel, Matthew R. T2 - CONSTRUCTION ECONOMICS AND BUILDING AB - Despite attempts to improve safety performance, the construction industry continues to account for a disproportionate rate of injuries. A large proportion of these injuries occur because workers are unable to recognize and respond to hazards in dynamic and unpredictable environments. Unrecognized hazards expose workers to unanticipated risks and can lead to catastrophic accidents. In order to enhance hazard recognition skills, employers often put new and experienced workers through formal hazard recognition training programs. Unfortunately, current training programs primarily rely on instructor-centric pedagogical approaches, which are insensitive to the adult learning process. In order to ensure effective adult learning, training programs must integrate learner-centric andragogical principles to improve engagement and retention in adult trainees. This paper aims to discuss training program elements that can potentially accelerate the adult learning process while improving safety knowledge retention. To this end, the researchers reviewed relevant literature on the cognitive processes of adult learning, essential components of effectual training programs and developed a reliable framework for the training and transfer of safety knowledge. A case example of successfully using the framework is also presented. The results of the study will provide safety trainers and construction professionals with valuable information on developing effective hazard recognition and receptor training programs, with the goal of improving construction safety performance. DA - 2013/// PY - 2013/// DO - 10.5130/ajceb.v13i3.3178 VL - 13 IS - 3 SP - 128-140 SN - 1837-9133 KW - Hazard recognition training KW - Adult education KW - Construction Safety KW - Human resources development KW - Training framework ER - TY - JOUR TI - Enhancing construction hazard recognition and communication with energy-based cognitive mnemonics and safety meeting maturity model: Multiple baseline study AU - Albert, A. AU - Hallowell, M. AU - Kleiner, B. T2 - Journal of Construction Engineering and Management AB - Nearly every safety management activity is designed around the fundamental and implicit assumption that the workforce is capable of identifying hazards before exposure. Unfortunately, research shows preliminary evidence that construction crews perform relatively poorly with respect to hazard recognition. This may be attributable, in part, to the diverse and dynamic nature of construction work. Consequently, many hazards remain unidentified, uncontrolled, and unmanaged until they are encountered by workers. To advance theory and practice in the area of construction hazard recognition and communication, a large-scale, multiphase research project was conducted with the following objectives: (1) devise a new hazard recognition method based upon the principles of cognitive mnemonics and that promotes hazard recognition skill; (2) build a maturity model to improve hazard recognition performance and encourage hazard communication; and (3) experimentally measure improvement in hazard recognition and communication resulting from the new program. The first two objectives were achieved by using the nominal group technique driven by input from an expert panel of 14 industry professionals from organizations with world-class safety records and an average of 26 years of safety management experience. A new method for measuring the quality of prejob safety meetings was devised in a series of eight face-to-face meetings and teleconferences among the experts over a 1-year period. The null hypothesis that the strategy does not improve the proportion of hazards identified and communicated before the start of construction was experimentally tested with six crews using the multiple baseline testing approach. This is a series of concurrent longitudinal A-B designs that are time-lagged among independent treatment groups. The obtained observations were analyzed using interrupted time series regression models. The results showed that workers were able to identify and communicate an average of 38% of hazards before the intervention was applied and that the new strategy caused a weighted overall level-change improvement in hazard recognition skill of 31% (p<0.01). This is the first known quasi-experimental test of a hazard recognition strategy in any industry and one of the first large-scale studies to employ multiple baseline testing with appropriate controls that optimize validity and statistical rigor. DA - 2013/// PY - 2013/// DO - 10.1061/(asce)co.1943-7862.0000790 VL - 140 IS - 2 ER - TY - CONF TI - Teaching construction hazard recognition through high fidelity augmented reality AU - Tixier, A. AU - Albert, A. AU - Hallowell, M. C2 - 2013/// C3 - Proceedings of the 2013 120th ASEE Annual Conference and Exposition DA - 2013/// ER - TY - CONF TI - Modeling the role of social networks in situational awareness and hazard communication AU - Albert, A AU - Hallowell, M.R C2 - 2013/// C3 - Proceedings of the 2012 Construction Research Congress Annual Conference DA - 2013/// ER - TY - CONF TI - Measuring the effectiveness of pedagogical innovations using multiple baseline testing AU - Albert, A. AU - Hallowell, M. C2 - 2013/// C3 - Proceedings of the 2013 120th ASEE Annual Conference and Exposition DA - 2013/// ER - TY - JOUR TI - SUMMARY VISUALIZATIONS FOR COASTAL SPATIAL-TEMPORAL DYNAMICS AU - Thakur, Sidharth AU - Tateosian, Laura AU - Mitasova, Helena AU - Hardin, Eric AU - Overton, Margery T2 - INTERNATIONAL JOURNAL FOR UNCERTAINTY QUANTIFICATION AB - Digital scans of dynamic terrains such as coastal regions are now being gathered at high spatial and temporal resolution. Although standard tools based on geographic information systems (GIS) are indispensable for analyzing geospatial data, they have limited support to display time-dependent changes in data and information such as statistical distributions and uncertainty in data. We present a set of techniques for visually summarizing the dynamics of coastal dunes. We visualize summary statistics of important data attributes and risk or vulnerability indices as functions of both spatial and temporal dimensions in our data and represent uncertainty in the data set. We apply standard techniques, the space time cube and clustering, in novel ways to the domain of geomorphology. We combine surface-mapping and imagery with summary visualizations to retain important geographical context in the visualizations and reduce clutter due to direct plotting of statistical data in displays of geospatial information. We also address some issues pertaining to visualization of summary statistics for geographical regions at varying scales. We demonstrate visualization tools on time series of elevation models from the Outer Banks of North Carolina and observe temporal-spatial trends therein. DA - 2013/// PY - 2013/// DO - 10.1615/int.j.uncertaintyquantification.2012003969 VL - 3 IS - 3 SP - 241-253 SN - 2152-5099 KW - uncertainty KW - visualization KW - geovisualization KW - glyph-based visualization KW - spatial-temporal analysis KW - space-time cube KW - coastal terrain KW - geomorphology KW - GRASS GIS KW - Outer Banks ER - TY - JOUR TI - Synthesizing Route Travel Time Distributions from Segment Travel Time Distributions AU - Isukapati, Isaac Kumar AU - List, George F. AU - Williams, Billy M. AU - Karr, Alan F. T2 - TRANSPORTATION RESEARCH RECORD AB - This paper examines a way to synthesize route travel time probability density functions (PDFs) on the basis of segment-level PDFs. Real-world data from I-5 in Sacramento, California, are employed. The first finding is that careful filtering is required to extract useful travel times from the raw data because trip times, not travel times, are observed (i.e., the movement of vehicles between locations). The second finding is that significant correlations exist between individual vehicle travel times for adjacent segments. Two analyses are done in this regard: one predicts downstream travel times on the basis of upstream travel times, and the second checks for correlations in travel times between upstream and downstream segments. The results of these analyses suggest that strong positive correlations exist. The third finding is that comonotonicity, or perfect positive dependence, can be assumed when route travel time PDFs are generated from segment PDFs. Kolmogorov–Smirnov tests show that travel times synthesized from the segment-specific data are statistically different only under highly congested conditions, and even then, the percentage differences in the distributions of the synthesized and actual travel times are small. The fourth finding, somewhat tangential, is that there is little variation in individual driver travel times under given operating conditions. This is an important finding, because such an assumption serves as the basis for all traffic simulation models. DA - 2013/// PY - 2013/// DO - 10.3141/2396-09 IS - 2396 SP - 71-81 SN - 2169-4052 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84897082752&partnerID=MN8TOARS ER - TY - JOUR TI - Deterministic framework and methodology for evaluating travel time reliability on freeway facilities AU - Schroeder, B. J. AU - Rouphail, N. M. AU - Aghdashi, S. T2 - Transportation Research Record DA - 2013/// PY - 2013/// IS - 2396 SP - 61-70 ER - TY - CONF TI - Understanding mechanisms leading to asphalt binder fatigue in the dynamic shear rheometer (DSR) AU - Hintz, C. AU - Bahia, H. C2 - 2013/// C3 - Asphalt paving technology 2013, vol 82 DA - 2013/// VL - 82 SP - 465-501 ER - TY - JOUR TI - Nonlinear Viscoelastic Behavior of Asphalt Concrete and Its Implication for Fatigue Modeling AU - Underwood, B. Shane AU - Kim, Y. Richard T2 - Transportation Research Record: Journal of the Transportation Research Board AB - Mechanistic models for asphalt concrete (AC) can consider many different physical mechanisms. However, as more mechanisms are considered, the complexity increases, and it becomes important to balance accuracy and complexity to create a model that can be used by the engineering community. In some cases, the material response is dominated by the effects of only some key processes, and smearing the effects of the minor ones is acceptable. In other cases, many processes are important and need to be considered. In this paper, the importance of modeling the nonlinear viscoelasticity (NLVE) of AC for fatigue response prediction is assessed. Two mechanistic hypotheses are considered for describing this phenomenon: linear viscoelastic with damage and NLVE with damage. The importance of explicitly considering NLVE effects under fatigue loading is evaluated with laboratory tests, the simplified viscoelastic continuum damage (S-VECD) model, and an NLVE form of the S-VECD model. These two models are characterized and used to simulate and compare AC fatigue response under constant and random controlled stress and strain conditions. It is found that while the NLVE-based formulation better represents the material response in random loading and suggests less overall damage accumulation during fatigue, the two models predict similar amounts of modulus reduction. The primary conclusion from this study is that because the goal for fatigue assessment is to find the change in modulus over a long period of time, fatigue response modeling of AC does not need to explicitly consider NLVE. DA - 2013/1// PY - 2013/1// DO - 10.3141/2373-11 VL - 2373 IS - 1 SP - 100-108 J2 - Transportation Research Record LA - en OP - SN - 0361-1981 2169-4052 UR - http://dx.doi.org/10.3141/2373-11 DB - Crossref ER - TY - JOUR TI - Locating Traffic Sensors on a Highway Network Models and Algorithms AU - Sayyady, Fatemeh AU - Fathi, Yahya AU - List, George F. AU - Stone, John R. T2 - TRANSPORTATION RESEARCH RECORD AB - This paper considers the problem of finding optimal sensor locations on a traffic network with the goal of characterizing system use overall. The problem is studied for two practical scenarios. In the first scenario, it is assumed that there is a given number of sensors (p) to be located on the highway network. In this context, the problem is to find a collection of p locations among a given collection of candidate locations. In the second scenario, it is assumed that there is a cost (c i ) associated with installing a sensor at each candidate location i and a total budget b. In this context, the problem is to find a collection of locations that provide the best possible characterization given the budget constraint. A metric is proposed for evaluating a potential solution, and then appropriate mathematical models are proposed for solving the problem for each scenario. It is shown that the budget-constrained problem is an extension of the well-known p-median problem. A new Lagrangian heuristic algorithm is presented for solving large instances of this problem when a budget constraint is imposed. A comprehensive computational experiment is used to demonstrate that the Lagrangian heuristic algorithm provides solutions for large-scale networks within reasonable execution times. Examples are based on locating weigh-in-motion sensors on a large-scale highway network. DA - 2013/// PY - 2013/// DO - 10.3141/2339-04 IS - 2339 SP - 30-38 SN - 2169-4052 ER - TY - JOUR TI - Investigation into Top-Down Cracking of Asphalt Pavements in North Carolina AU - Park, Hong Joon AU - Kim, Y. Richard T2 - TRANSPORTATION RESEARCH RECORD AB - Top-down cracking has become a commonly reported cracking mechanism in asphalt pavements worldwide. In top-down cracking, a crack initiates at the surface of an asphalt concrete pavement and propagates to the bottom of the asphalt pavement layer. Because the location and governing state of stress for top-down cracking are different from those for bottom-up cracking, analysis of pavement cracking performance must be robust enough to account for the complex mechanisms that are involved in top-down cracking. This study applies the viscoelastic continuum damage finite element model to the evaluation of two pavement sections in North Carolina where top-down cracking has been identified. Small specimen geometries are used to perform simplified viscoelastic continuum damage testing on individual asphalt layers obtained from field cores. This testing model and the Fourier finite element program are used together for pavement cracking performance simulations, and the joint model uses the structure and layer material properties obtained from the two study pavements. The simulation results clearly support the propensity of these pavements to exhibit top-down cracking. In addition to laboratory testing and analysis, the deflection-based method suggested by Uhlmeyer et al. is applied to the data obtained from pavement sections with known crack initiation locations, and that method's validity is investigated. The Uhlmeyer method uses the AREA parameter, which is determined from falling weight deflectometer deflections, and pavement thicknesses. The analysis results show a clear difference in the AREA versus pavement thickness relationship between the pavement sections with top-down cracking and those with full-depth cracking. DA - 2013/// PY - 2013/// DO - 10.3141/2368-05 IS - 2368 SP - 45-55 SN - 2169-4052 ER - TY - JOUR TI - Event-based modeling of driver yielding behavior to pedestrians at two-lane roundabout approaches AU - Salamati, K. AU - Schroeder, B. J. AU - Geruschat, D. R. AU - Rouphail, N. M. T2 - Transportation Research Record DA - 2013/// PY - 2013/// IS - 2389 SP - 1-11 ER - TY - JOUR TI - Estimation of incident propensity for reliability analysis in the Highway Capacity Manual AU - Aghdashi, Seyedbehzad AU - Rouphail, Nagui M AU - Hajbabaie, Ali T2 - Transportation Research Record AB - This paper presents the method used to generate the incident probabilities required by the freeway scenario generator for travel time reliability analysis in the Highway Capacity Manual. The freeway scenario generator requires the estimation of monthly probabilities of different levels of incident severity during specified study periods. Incident probability in this context is the fraction of time that an incident of a specific level of severity is active somewhere on the freeway facility during the study period for the month considered. The proposed method is designed to recognize and deal with the varying levels of incident and facility data availability at the implementing agencies. A queuing model is proposed for the conversion of incident frequencies into incident probabilities when agencies have access only to frequencies instead of probabilities. DA - 2013/// PY - 2013/// DO - 10.3141/2395-14 VL - 2395 IS - 1 SP - 123-131 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84897037320&partnerID=MN8TOARS ER - TY - JOUR TI - Enhancements to the freeway facilities method in the highway capacity manual to enable reliability analysis AU - Sajjadi, S. AU - Schroeder, B. AU - Rouphail, N. M. T2 - Transportation Research Record DA - 2013/// PY - 2013/// IS - 2395 SP - 21-30 ER - TY - JOUR TI - Emissions estimation at multilane roundabouts effects of movement and approach lane AU - Salamati, K. AU - Coelho, M. C. AU - Fernandes, P. J. AU - Rouphail, N. M. AU - Frey, H. C. AU - Bandeira, J. T2 - Transportation Research Record DA - 2013/// PY - 2013/// IS - 2389 SP - 12-21 ER - TY - JOUR TI - Development of an oversaturated speed-flow model based on the highway capacity manual AU - Xu, Y. L. AU - Williams, B. M. AU - Rouphail, N. M. AU - Chase, R. T. T2 - Transportation Research Record DA - 2013/// PY - 2013/// IS - 2395 SP - 41-48 ER - TY - CONF TI - Development of a failure criterion for asphalt mixtures under fatigue loading AU - Zhang, J. AU - Sabouri, M. AU - Guddati, M. N. AU - Kim, Y. R. C2 - 2013/// C3 - Asphalt paving technology 2013, vol 82 DA - 2013/// VL - 82 SP - 1-22 ER - TY - JOUR TI - Development of Calibration Testing Protocol for Permanent Deformation Model of Asphalt Concrete AU - Choi, Yeong-Tae AU - Kim, Y. Richard T2 - TRANSPORTATION RESEARCH RECORD AB - Recent permanent deformation modeling research at North Carolina State University has resulted in the shift model, which is capable of expressing the permanent strain growth of asphalt concrete as a function of deviatoric stress, load time, and temperature on the basis of the time–temperature superposition and time–stress superposition principles. This paper presents an efficient calibration test protocol for the shift model as well as verification of the model. The proposed test protocol is comprised of triaxial stress sweep (TSS) tests and a reference test. The TSS test is suggested to reduce the number of tests required by applying three deviatoric stresses within one test. Each TSS test was performed at three temperatures: high (T H ), intermediate (T I ), and low (T L ). The reference test was a triaxial repeated load permanent deformation test conducted at T H only. The shift model was calibrated for the polymer-modified dense-graded NY9.5B mix, and the calibrated model was applied successfully to predict strain growth for the composite tests at the three study temperatures and for random load tests at T H . The calibration testing procedure was optimized for the asphalt mixture performance tester. The TSS tests take approximately 2.9 h at T H and 1.5 h at T I and T L . Thus, about a day was required to complete one set of calibration tests under the proposed test protocol. Within 2 to 3 days of testing, depending on the number of replicates, the calibrated shift model is capable of predicting permanent strain growth for different temperatures, load times, and deviatoric stresses. DA - 2013/// PY - 2013/// DO - 10.3141/2373-04 IS - 2373 SP - 34-42 SN - 2169-4052 ER - TY - CONF TI - A mechanistic permanent deformation model for asphalt concrete in compression AU - Choi, Y. T. AU - Kim, Y. R. C2 - 2013/// C3 - Asphalt paving technology 2013, vol 82 DA - 2013/// VL - 82 SP - 617-649 ER - TY - JOUR TI - Understanding the spatial formation and accumulation of fats, oils and grease deposits in the sewer collection system AU - Dominic, Christopher Cyril Sandeep AU - Szakasits, Megan AU - Dean, Lisa O. AU - Ducoste, Joel J. T2 - WATER SCIENCE AND TECHNOLOGY AB - Sanitary sewer overflows are caused by the accumulation of insoluble calcium salts of fatty acids, which are formed by the reaction between fats, oils and grease (FOG) and calcium found in wastewaters. Different sewer structural configurations (i.e., manholes, pipes, wet wells), which vary spatially, along with other obstructions (roots intrusion) and pipe deformations (pipe sags), may influence the detrimental buildup of FOG deposits. The purpose of this study was to quantify the spatial variation in FOG deposit formation and accumulation in a pilot-scale sewer collection system. The pilot system contained straight pipes, manholes, roots intrusion, and a pipe sag. Calcium and oil were injected into the system and operated at alkaline (pH = 10) and neutral (pH = 7) pH conditions. Results showed that solid accumulations were slightly higher at neutral pH. Fourier transform infrared (FTIR) analysis on the solids samples confirmed that the solids were indeed calcium-based fatty acid salts. However, the fatty acid profiles of the solids deviated from the profile found from FOG deposits in sewer systems, which were primarily saturated fatty acids. These results confirm the work done previously by researchers and suggest an alternative fate of unsaturated fatty acids that does not lead to their incorporation in FOG deposits in full-scale sewer systems. DA - 2013/// PY - 2013/// DO - 10.2166/wst.2013.428 VL - 68 IS - 8 SP - 1830-1836 SN - 1996-9732 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84888247504&partnerID=MN8TOARS KW - FOG KW - hydraulic configurations KW - pilot-scale sewer collection system KW - sanitary sewer overflows ER - TY - JOUR TI - Numerical Simulation of MSE Wall Behavior Induced by Surface-Water Infiltration AU - Kim, Wan Soo AU - Borden, Roy H. T2 - JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING AB - A series of numerical simulations, including transient seepage analyses and stress deformation analyses, was performed to predict the behavior of a mechanically stabilized earth (MSE) wall subjected to surface-water infiltration. In this research, two mechanisms to cause the deformation because of wetting were considered: (1) the deformation induced by shear strength decreases and (2) the volumetric deformation (swell or collapse) because of wetting. The effects of low as-compacted water content and a low-quality compaction zone behind the wall face on the wall behavior were investigated. As result of the simulations, the wall deformations (face deflections and reinforced-soil settlements) and reinforcement tensions (maximum tensions) are presented at the end of construction and after periods of surface-water infiltration. DA - 2013/12/1/ PY - 2013/12/1/ DO - 10.1061/(asce)gt.1943-5606.0000927 VL - 139 IS - 12 SP - 2110-2124 SN - 1943-5606 KW - MSE wall KW - Unsaturated soil mechanics KW - Compaction KW - Water infiltration KW - Numerical analysis ER - TY - JOUR TI - Innovative Technologies Used to Investigate Segments of the Inca Road AU - Jaselskis, Edward J. AU - Schexnayder, Clifford J. AU - Fiori, Christine AU - Becker, Timothy C. AU - Hung, Wu-Chueh AU - Beckman, Christine AU - Kaewmoracharoen, Manop AU - Recavarren, Gerardo Chang AU - Celaya, Manuel AU - Alarcon, Daniela T2 - JOURNAL OF PROFESSIONAL ISSUES IN ENGINEERING EDUCATION AND PRACTICE AB - Supported by a National Science Foundation, Pan-American Advanced Studies Institute (PASI) grant and the Smithsonian Institute, two expeditions were made by teams of multidisciplinary researchers to the Andes Mountains of Peru to study the design and construction methods used to build the great Inca Road. The objectives of the study were to identify sustainable engineering practices used by the Inca, determine which practices can apply to modern design and construction, and share findings with visitors at the National Museum of the American Indian and others throughout the world through live interactive satellite broadcasts. This paper focuses on the technologies that were used to accomplish the broadcasts and used to support the engineering and construction analysis of the Inca Road. Each technology used on these expeditions provided a unique opportunity to learn about the road and disseminate findings with others. The technologies utilized included communication equipment (e.g., satellite router and dish, Wi-Fi, and mobile portable video equipment), location and mapping technologies [e.g., geographic information system (GIS) and global positioning system (GPS)], photogrammetric techniques for three-dimensional modeling, laser range finding for precision measurement of the road features, and ground-penetrating radar (GPR) for use in nondestructive testing and evaluation of subsurface conditions. The technologies are explained in this paper along with the challenges of implementing them in such harsh and extreme conditions. In addition, some of the more salient engineering and construction discoveries are included. This information can be useful for others who are interested in implementing a similar approach for studying ancient civil infrastructure in other remote locations. DA - 2013/7/1/ PY - 2013/7/1/ DO - 10.1061/(asce)ei.1943-5541.0000145 VL - 139 IS - 3 SP - 187-195 SN - 1943-5541 KW - Inca road KW - Tele-engineering KW - Information technology ER - TY - JOUR TI - A Performance-Based Evaluation of Superpave Design Gyrations for High Traffic Surface Mixes AU - Khosla, N. Paul AU - Ayyala, Dinesh T2 - 2ND CONFERENCE OF TRANSPORTATION RESEARCH GROUP OF INDIA (2ND CTRG) AB - The number of design gyrations (Ndes) is an extremely important parameter in the asphalt concrete mix design procedure using the Superpave method. The choice of Ndes is a function of total traffic during the pavement service life, expressed in ESALs. Asphalt concrete mixes for higher traffic levels are compacted to a higher Ndes as a denser mix resists rutting more effectively. However, this leads to a lower design asphalt content, which decreases fatigue performance of the mix. Therefore, a performance-oriented approach to determine Ndes was developed that optimizes mix performance with respect to both rutting and fatigue cracking. In this paper, the research methodology adopted to compare the relative performance of surface mixes with 12.5 mm nominal maximum aggregate size is presented, along with recommended Ndes values for C and D-level mixes, designed to handle traffic levels of 3-30 Million and greater than 30 Million ESALs, respectively. Asphalt concrete mixes were designed at Ndes levels of 50, 75, 100 and 125 gyrations to determine asphalt content using Superpave design method. Dynamic modulus (E*) was measured at design asphalt content for different gyration levels using the Asphalt Mixture Performance Tester device. The E* data and corresponding binder properties were used as input in the AASHTO Darwin-ME software to predict rutting and fatigue performance of the mixes by assuming a model pavement section and appropriate traffic levels. Relative performance indicators were developed for both rutting and fatigue, and plotted against the asphalt content to determine optimum Ndes. For both surface mixes, the optimum Ndes value was determined to be 85 gyrations. DA - 2013/// PY - 2013/// DO - 10.1016/j.sbspro.2013.11.103 VL - 104 SP - 109-118 SN - 1877-0428 KW - Design gyrations KW - Fatigue cracking KW - Rutting KW - Relative performance KW - Dynamic modulus ER - TY - JOUR TI - Healing of biologically induced cemented sands AU - Montoya, B. M. AU - Dejong, J. T. T2 - GEOTECHNIQUE LETTERS AB - Microbial-induced calcite precipitation (MICP) is a novel bio-mediated ground improvement method that can be used to increase the shear strength and stiffness of sand. One of the benefits of the MICP treatment process is the ability to heal degraded calcite bonds post-shearing. The healed bonds can then improve the sand properties (small strain stiffness and peak strength) compared with those of the pre-shearing condition. The MICP healing process was evaluated using monotonic undrained shearing and dynamic centrifuge tests, and comparing the sand behaviour before and after the healing process. Similar or improved behaviour was observed after the healing process. This healing ability implies that degraded MICP-treated sands can be healed after loading (e.g. in an earthquake) to their original level of treatment to prevent additional settlements or damage from subsequent loading (e.g. aftershocks). DA - 2013/// PY - 2013/// DO - 10.1680/geolett.13.00044 VL - 3 SP - 147-151 SN - 2045-2543 KW - deformation KW - ground improvement KW - sands KW - shear strength KW - stiffness ER - TY - JOUR TI - Fire performance curves for unprotected HSS steel columns AU - Alam, M. Shahria AU - Billah, A. H. M. Muntasir AU - Quayyum, Shahriar AU - Ashraf, Mahmud AU - Rafi, A. N. M. AU - Rteil, Ahmad T2 - STEEL AND COMPOSITE STRUCTURES AB - The behaviour of steel column at elevated temperature is significantly different than that at ambient temperature due to its changes in the mechanical properties with temperature. Reported literature suggests that steel column may become vulnerable when exposed to fire condition, since its strength and capacity decrease rapidly with temperature. The present study aims at investigating the lateral load resistance of non-insulated steel columns under fire exposure through finite element analysis. The studied parameters include moment-rotation behaviour, lateral load-deflection behaviour, stiffness and ductility of columns at different axial load levels. It was observed that when the temperature of the column was increased, there was a significant reduction in the lateral load and moment capacity of the non-insulated steel columns. Moreover, it was noted that the stiffness and ductility of steel columns decreased sharply with the increase in temperature, especially for temperatures above $400^{\circ}C$. In addition, the lateral load capacity and the moment capacity of columns were plotted against fire exposure time, which revealed that in fire conditions, the non-insulated steel columns experience substantial reduction in lateral load resistance within 15 minutes of fire exposure. DA - 2013/12// PY - 2013/12// DO - 10.12989/scs.2013.15.6.705 VL - 15 IS - 6 SP - 705-724 SN - 1598-6233 KW - HSS steel column KW - elevated temperature KW - moment-rotation KW - lateral load-deflection KW - axial capacity ER - TY - JOUR TI - Effect of volumetric factors on the mechanical behavior of asphalt fine aggregate matrix and the relationship to asphalt mixture properties AU - Underwood, B. Shane AU - Kim, Y. Richard T2 - Construction and Building Materials AB - The multiscale study of asphalt concrete using fine aggregate matrix (FAM) has become widespread in recent years. Different laboratory fabrication procedures have been proposed, and since FAM’s sensitivity to compositional effects is unknown this literature cannot be coherently interpreted. In this paper, the mechanical responses of FAM at different volumetric compositions are systematically studied. The viscoelastic and tensile properties are found to be sensitive to volumetric composition. It is concluded that the use of FAM for modeling purposes requires accurate replication of FAM as it exists in the mixture. However, such strict requirements are not necessary for simpler, comparative evaluations. DA - 2013/12// PY - 2013/12// DO - 10.1016/j.conbuildmat.2013.08.045 VL - 49 SP - 672-681 J2 - Construction and Building Materials LA - en OP - SN - 0950-0618 UR - http://dx.doi.org/10.1016/j.conbuildmat.2013.08.045 DB - Crossref KW - Asphalt concrete KW - Fine aggregate matrix KW - Multiscale evaluation KW - Linear viscoelastic KW - Fatigue ER - TY - JOUR TI - Comparing exposure metrics for the effects of fine particulate matter on emergency hospital admissions AU - Mannshardt, Elizabeth AU - Sucic, Katarina AU - Jiao, Wan AU - Dominici, Francesca AU - Frey, H. Christopher AU - Reich, Brian AU - Fuentes, Montserrat T2 - JOURNAL OF EXPOSURE SCIENCE AND ENVIRONMENTAL EPIDEMIOLOGY AB - A crucial step in an epidemiological study of the effects of air pollution is to accurately quantify exposure of the population. In this paper, we investigate the sensitivity of the health effects estimates associated with short-term exposure to fine particulate matter with respect to three potential metrics for daily exposure: ambient monitor data, estimated values from a deterministic atmospheric chemistry model, and stochastic daily average human exposure simulation output. Each of these metrics has strengths and weaknesses when estimating the association between daily changes in ambient exposure to fine particulate matter and daily emergency hospital admissions. Monitor data is readily available, but is incomplete over space and time. The atmospheric chemistry model output is spatially and temporally complete but may be less accurate than monitor data. The stochastic human exposure estimates account for human activity patterns and variability in pollutant concentration across microenvironments, but requires extensive input information and computation time. To compare these metrics, we consider a case study of the association between fine particulate matter and emergency hospital admissions for respiratory cases for the Medicare population across three counties in New York. Of particular interest is to quantify the impact and/or benefit to using the stochastic human exposure output to measure ambient exposure to fine particulate matter. Results indicate that the stochastic human exposure simulation output indicates approximately the same increase in the relative risk associated with emergency admissions as using a chemistry model or monitoring data as exposure metrics. However, the stochastic human exposure simulation output and the atmospheric chemistry model both bring additional information, which helps to reduce the uncertainly in our estimated risk. DA - 2013/// PY - 2013/// DO - 10.1038/jes.2013.39 VL - 23 IS - 6 SP - 627-636 SN - 1559-064X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84886725530&partnerID=MN8TOARS KW - ambient monitoring data KW - CMAQ KW - SHEDS KW - PM2.5 ER - TY - JOUR TI - A generalized multistage optimization modeling framework for life cycle assessment-based integrated solid waste management AU - Levis, James W. AU - Barlaz, Morton A. AU - DeCarolis, Joseph F. AU - Ranjithan, S. Ranji T2 - Environmental Modelling & Software AB - Solid waste management (SWM) is an integral component of civil infrastructure and the global economy, and is a growing concern due to increases in population, urbanization, and economic development. In 2011, 1.3 billion metric tons of municipal solid waste (MSW) were generated, and this is expected to grow to 2.2 billion metric tons by 2025. In the U.S., MSW systems processed approximately 250 million tons of waste and produced 118 Tg of CO2e emissions, which represents over 8% of non-energy related greenhouse gas (GHG) emissions, and 2% of total net GHG emissions. While previous research has applied environmental life cycle assessment (LCA) to SWM using formal search techniques, existing models are either not readily generalizable and scalable, or optimize only a single time period and do not consider changes likely to affect SWM over time, such as new policy and technology innovation. This paper presents the first life cycle-based framework to optimize—over multiple time stages—the collection and treatment of all waste materials from curb to final disposal by minimizing cost or environmental impacts while considering user-defined emissions and waste diversion constraints. In addition, the framework is designed to be responsive to future changes in energy and GHG prices. This framework considers the use of existing SWM infrastructure as well as the deployment and utilization of new infrastructure. Several scenarios, considering cost, diversion, and GHG emissions, are analyzed in a 3-stage test system. The results show the utility of the multi-stage framework and the insights that can be gained from using such a framework. The framework was also used to solve a larger SWM system; the results show that the framework solves in reasonable time using typical hardware and readily available mathematical programming solvers. The framework is intended to inform SWM by considering costs, environmental impacts, and policy constraints. DA - 2013/12// PY - 2013/12// DO - 10.1016/j.envsoft.2013.08.007 VL - 50 SP - 51-65 J2 - Environmental Modelling & Software LA - en OP - SN - 1364-8152 UR - http://dx.doi.org/10.1016/j.envsoft.2013.08.007 DB - Crossref KW - Solid waste KW - Optimization KW - Multi-stage KW - Life cycle assessment KW - Decision support ER - TY - JOUR TI - Use of Cyclic Direct Tension Tests and Digital Imaging Analysis to Evaluate Moisture Susceptibility of Warm-Mix Asphalt Concrete AU - Lee, Jong-Sub AU - Lee, Jae-Jun AU - Kwon, Soo-Ahn AU - Kim, Y. Richard T2 - TRANSPORTATION RESEARCH RECORD AB - This paper presents a simplified viscoelastic continuum damage material model for the evaluation of moisture susceptibility of asphalt concrete. The model is based on cyclic direct tension testing and layered viscoelastic analysis. The visual stripping inspection afforded by digital imaging analysis is also proposed as an intuitive and straightforward method for moisture susceptibility evaluation. These methods were applied to a Superpave ® 19-mm hot-mix asphalt mixture and corresponding warm-mix asphalt mixtures modified by a polyethylene wax-type additive with and without an antistripping agent. The fatigue life predicted by the simplified viscoelastic continuum damage and layered viscoelastic analysis models had a strong correlation with the percentage of stripping determined from specimen surfaces that were fractured during cyclic direct tension testing of the hot-mix and warm-mix asphalt mixtures with various asphalt contents. In addition, a polyethylene wax-type additive combined with an antistripping agent was found to provide a longer fatigue life and less stripping than a pure polyethylene wax-type additive. The findings from this paper should provide guidance to agencies and material engineers in developing asphalt binder modifiers that lengthen the fatigue life of pavements and reduce moisture susceptibility. DA - 2013/// PY - 2013/// DO - 10.3141/2372-08 IS - 2372 SP - 61-71 SN - 2169-4052 ER - TY - JOUR TI - Special Issue on the Role of Systems Analysis in Watershed Management AU - Cai, Ximing AU - Vogel, Richard AU - Ranjithan, Ranji T2 - JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT DA - 2013/9// PY - 2013/9// DO - 10.1061/(asce)wr.1943-5452.0000341 VL - 139 IS - 5 SP - 461-463 SN - 1943-5452 ER - TY - JOUR TI - Simplification of Linear Amplitude Sweep Test and Specification Parameter AU - Hintz, Cassie AU - Bahia, Hussain T2 - TRANSPORTATION RESEARCH RECORD AB - The linear amplitude sweep (LAS) test has recently been approved by AASHTO as a provisional standard and is currently being considered for specification of asphalt binder fatigue resistance. The LAS test is a cyclic torsion test conducted in the dynamic shear rheometer (DSR) that uses increasing loading amplitudes to accelerate damage. The LAS test has been proposed as a surrogate to the time sweep (TS) test, which is a conventional fatigue test consisting of repeated cyclic loading at constant amplitude. The TS test is considered unsuitable for specification because of the uncertainty in the test duration required to induce and quantify fatigue. Recent ruggedness testing efforts have shown that the LAS test cannot be conducted by all DSRs. This study evaluates a simpler amplitude ramping procedure that resolved the difficulties encountered with some rheometers. Additionally, a simple specification parameter is introduced to offer a practical approach to define damage tolerance. The definition of failure is based on a more recent study to explain the mechanisms of fatigue damage under TS testing in the DSR. On the basis of a comparison between TS and LAS test results, this paper demonstrates that the damage evolution in the two tests differs, thus indicating that the LAS test is very complex and is better referred to as a damage tolerance test rather than a true fatigue test. With the simplified analysis approach for the modified LAS procedure, a critical cracking length signifying the start of rapid crack growth is proposed for specification of binder damage tolerance at intermediate temperature. DA - 2013/// PY - 2013/// DO - 10.3141/2370-02 IS - 2370 SP - 10-16 SN - 2169-4052 ER - TY - JOUR TI - Establishment of a universal healing evaluation index for asphalt binder AU - Shan, Liyan AU - Tan, Yiqiu AU - Kim, Y. Richard T2 - CONSTRUCTION AND BUILDING MATERIALS AB - The healing performance of asphalt binder is important to the overall performance of asphalt pavement. A suitable healing evaluation index is critical in order to compare the healing performance of different asphalt binders and choose the binder with the best healing properties. However, current studies focus primarily on the healing performance of asphalt binder and seem to ignore the importance of the healing evaluation index. In this paper, the healing performance of four different asphalt binders is analyzed. By comparing the healing curve to the initial curve, a ratio that is based on the areas created by the curves is found to reflect the healing performance of asphalt binders. Once the healing evaluation indices are established, they are also used to evaluate the mastics, and the applicability of the indices is analyzed. Also, a healing function for asphalt binder is established. The results show that the HIm-c index (based on the curve of the normalized modulus versus load cycles), the HIem-c index (based on the curve of the elastic modulus versus load cycles) and the HIvm-c index (based on the curve of the viscous modulus versus load cycles) suggest the same rankings for the healing of the studied binders. The healing ranking of the binders is also the same as that of the corresponding mastics evaluated by the HIm-c index. Based on the established healing function, it is found that the effect of terminal cases on the healing performance of asphalt binder is greater than the effect of rest periods. DA - 2013/11// PY - 2013/11// DO - 10.1016/j.conbuildmat.2013.06.039 VL - 48 SP - 74-79 SN - 1879-0526 KW - Asphalt binder KW - Healing evaluation index KW - Healing function KW - Modulus ER - TY - JOUR TI - Complex Adaptive Systems Approach to Simulate the Sustainability of Water Resources and Urbanization AU - Giacomoni, M. H. AU - Kanta, L. AU - Zechman, E. M. T2 - Journal of Water Resources Planning and Management AB - Urban water resources should be managed to meet conflicting demands for environmental health, economic prosperity, and social equity for present and future generations. While the sustainability of water resources can depend on dynamic interactions among natural, social, and infrastructure systems, typical water resource planning and management approaches are based on methodologies that ignore feedbacks and adaptations among these systems. This research develops and demonstrates a new complex adaptive systems approach to model the dynamic interactions among population growth, land-use change, the hydrologic cycle, residential water use, and interbasin transfers. Agent-based and cellular automaton models, representing consumers and policymakers who make land- and water-use decisions, are coupled with hydrologic models. The framework is applied for an illustrative case study to simulate urbanization and the water supply system over a long-term planning horizon. Results indicate that interactions among the decentralized decisions of individual residents can significantly influence system-wide sustainability. Adaptive management policies are included to restrict the water use and land use of consumers as the availability of water decreases. These strategies are simulated and assessed based on their abilities to increase the sustainability of the water supply system under the stresses of population growth, land-use change, and drought. DA - 2013/9// PY - 2013/9// DO - 10.1061/(asce)wr.1943-5452.0000302 VL - 139 IS - 5 SP - 554-564 J2 - J. Water Resour. Plann. Manage. LA - en OP - SN - 0733-9496 1943-5452 UR - http://dx.doi.org/10.1061/(asce)wr.1943-5452.0000302 DB - Crossref KW - Complex adaptive systems KW - Water resources sustainability KW - Adaptive management KW - Urbanization KW - Sociotechnical system KW - Multiscale modeling ER - TY - JOUR TI - Traffic Signal Timing Optimization Choosing the Objective Function AU - Hajbabaie, Ali AU - Benekohal, Rahim F. T2 - TRANSPORTATION RESEARCH RECORD AB - Choosing an appropriate objective function in optimizing traffic signals in urban transportation networks is not a simple and straightforward task because the choice likely will affect the set of constraints, modeling variables, obtained outputs, and necessary computer and human resources. A methodology for selection of an appropriate objective function for the problem of signal timing optimization was developed. The methodology was applied to a realistic case study network under four demand patterns (symmetric, asymmetric, undersaturated, oversaturated). Selection is made from a pool of five candidates: minimizing the delay, minimizing the travel time, maximizing the throughput-minus-queue, maximizing the number of completed trips (or trip maximization), and maximizing the weighted number of completed trips (or weighted trip maximization). Findings indicate that for all demand patterns, weighted trip maximization improved network performance compared with the other objective functions. Weighted trip maximization reduced system total delay by 0.1% to 5.2% in symmetric undersaturated demand, by 1.0% to 2.4% in asymmetric undersaturated demand, by 1.2% to 16.6% in symmetric oversaturated demand, and by 11.7% to 27.4% in asymmetric partially oversaturated demand. These figures indicate that the weighted trip maximization objective function is the most suitable of the candidates in oversaturated conditions, especially when demand is not symmetric. Throughput-minus-queue and trip maximization were the second most suitable objective functions for oversaturated conditions, and trip maximization was slightly more suitable when demand was asymmetric. DA - 2013/// PY - 2013/// DO - 10.3141/2355-02 VL - 2355 IS - 2355 SP - 10-19 SN - 2169-4052 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84886558107&partnerID=MN8TOARS ER - TY - JOUR TI - The Role of Multimodel Climate Forecasts in Improving Water and Energy Management over the Tana River Basin, Kenya AU - Oludhe, C. AU - Sankarasubramanian, A. AU - Sinha, Tushar AU - Devineni, Naresh AU - Lall, Upmanu T2 - JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY AB - Abstract The Masinga Reservoir located in the upper Tana River basin, Kenya, is extremely important in supplying the country's hydropower and protecting downstream ecology. The dam serves as the primary storage reservoir, controlling streamflow through a series of downstream hydroelectric reservoirs. The Masinga dam's operation is crucial in meeting power demands and thus contributing significantly to the country's economy. La Niña–related prolonged droughts of 1999–2001 resulted in severe power shortages in Kenya. Therefore, seasonal streamflow forecasts contingent on climate information are essential to estimate preseason water allocation. Here, the authors utilize reservoir inflow forecasts downscaled from monthly updated precipitation forecasts from ECHAM4.5 forced with constructed analog SSTs and multimodel precipitation forecasts developed from the Ensemble-Based Predictions of Climate Changes and their Impacts (ENSEMBLES) project to improve water allocation during the April–June and October–December seasons for the Masinga Reservoir. Three-month-ahead inflow forecasts developed from ECHAM4.5, multiple GCMs, and climatological ensembles are used in a reservoir model to allocate water for power generation by ensuring climatological probability of meeting the end-of-season target storage required to meet seasonal water demands. Retrospective reservoir analysis shows that inflow forecasts developed from single GCM and multiple GCMs perform better than use of climatological values by reducing the spill and increasing the allocation for hydropower during above-normal inflow years. Similarly, during below-normal inflow years, both of these forecasts could be effectively utilized to meet the end-of-season target storage by restricting releases for power generation. The multimodel forecasts preserve the end-of-season target storage better than the single-model inflow forecasts by reducing uncertainty and the overconfidence of individual model forecasts. DA - 2013/11// PY - 2013/11// DO - 10.1175/jamc-d-12-0300.1 VL - 52 IS - 11 SP - 2460-2475 SN - 1558-8432 KW - Forecast verification KW - skill KW - Seasonal forecasting KW - Statistical forecasting KW - Planning ER - TY - JOUR TI - Temporal stability of generation choice models AU - Huntsinger, L. F. AU - Rouphail, N. M. T2 - Transportation Research Record DA - 2013/// PY - 2013/// IS - 2344 SP - 79-87 ER - TY - JOUR TI - Public Opinions of Roadway Assets Roadway Review as a New Survey Method AU - Cunningham, Christopher M. AU - Chang, Jeffrey C. AU - Findley, Daniel J. AU - Vaughan, Christopher L. AU - Martin, James AU - Hekele, Aaron AU - Tatham, Chris T2 - TRANSPORTATION RESEARCH RECORD AB - In October 2011, the North Carolina Department of Transportation conducted a roadway review with a randomly recruited sample of North Carolina residents and community leaders. More than 300 people from 61 communities participated in the surveys, which were held in six locations: Asheville, Burlington, Charlotte, Jonesville, Rocky Mount, and Wilmington. The purpose of the roadway review was twofold: to determine the expectations for the condition of North Carolina highways and to identify the features that North Carolinians believe are most important on different types of highways. Surveys were completed during both daytime and nighttime hours and covered many roadway maintenance aspects, such as pavement, landscaping and mowing practices, signage, retroreflectivity, and shoulders. Regression equations are also provided to predict the overall satisfaction of condition, safety, and appearance by each individual roadway type. DA - 2013/// PY - 2013/// DO - 10.3141/2361-04 IS - 2361 SP - 25-34 SN - 2169-4052 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000327920200005&KeyUID=WOS:000327920200005 ER - TY - JOUR TI - Modeling for insight using Tools for Energy Model Optimization and Analysis (Temoa) AU - Hunter, Kevin AU - Sreepathi, Sarat AU - DeCarolis, Joseph F. T2 - ENERGY ECONOMICS AB - This paper introduces Tools for Energy Model Optimization and Analysis (Temoa), an open source framework for conducting energy system analysis. The core component of Temoa is an energy economy optimization (EEO) model, which minimizes the system-wide cost of energy supply by optimizing the deployment and utilization of energy technologies over a user-specified time horizon. The design of Temoa is intended to fill a unique niche within the energy modeling landscape by addressing two critical shortcomings associated with existing models: an inability to perform third party verification of published model results and the difficulty of conducting uncertainty analysis with large, complex models. Temoa leverages a modern revision control system to publicly archive model source code and data, which ensures repeatability of all published modeling work. From its initial conceptualization, Temoa was also designed for operation within a high performance computing environment to enable rigorous uncertainty analysis. We present the algebraic formulation of Temoa and conduct a verification exercise by implementing a simple test system in both Temoa and MARKAL, a widely used commercial model of the same type. In addition, a stochastic optimization of the test system is presented as a proof-of-concept application of uncertainty analysis using the Temoa framework. DA - 2013/11// PY - 2013/11// DO - 10.1016/j.eneco.2013.07.014 VL - 40 SP - 339-349 SN - 1873-6181 KW - Energy economy KW - Open source KW - Repeatability KW - Uncertainty analysis KW - Stochastic optimization ER - TY - JOUR TI - Methods for Fog Seal Field Test with Polymer-Modified Emulsions Development and Performance Evaluation AU - Im, Jeong Hyuk AU - Kim, Y. Richard T2 - TRANSPORTATION RESEARCH RECORD AB - Findings from a laboratory evaluation of fog seal emulsions are presented. Curing time and adhesive behavior of polymer-modified emulsions (PMEs) were compared with those of unmodified emulsions as fog seal materials. The study showed that polymer modification could improve certain properties of emulsions, such as an increase in adhesion. The evaporation test and the pneumatic adhesion tension testing instrument were used to investigate emulsion curing and adhesive behavior. Also, the rolling ball test and the damping test were developed as in situ test methods to determine an appropriate traffic opening time for roadways treated with fog seals. Finally, the third-scale Model Mobile Load Simulator was employed to compare the performance properties of the fog seal emulsions. The following main findings are presented: use of PMEs improved the emulsion bond strength and lessened the time a road was closed to traffic; PMEs showed more effective emulsion curing rates than did unmodified emulsions; strong relationships existed between the bond strength and both the measured rolling distance (from the rolling ball test) and the measured percentage of stained area (from the damping test); field test methods could be used to help determine whether emulsions were fully cured; and PMEs exhibited better aggregate retention and bleeding performance properties than did unmodified emulsions as a fog seal. DA - 2013/// PY - 2013/// DO - 10.3141/2361-11 IS - 2361 SP - 88-97 SN - 2169-4052 ER - TY - JOUR TI - Effects of metered entry volume on an oversaturated network with dynamic signal timing AU - Medina, J. C. AU - Hajbabaie, A. AU - Benekohal, R. F. T2 - Transportation Research Record DA - 2013/// PY - 2013/// IS - 2356 SP - 53-60 ER - TY - JOUR TI - Decomposition of forest products buried in landfills AU - Wang, Xiaoming AU - Padgett, Jennifer M. AU - Powell, John S. AU - Barlaz, Morton A. T2 - WASTE MANAGEMENT AB - The objective of this study was to investigate the decomposition of selected wood and paper products in landfills. The decomposition of these products under anaerobic landfill conditions results in the generation of biogenic carbon dioxide and methane, while the un-decomposed portion represents a biogenic carbon sink. Information on the decomposition of these municipal waste components is used to estimate national methane emissions inventories, for attribution of carbon storage credits, and to assess the life-cycle greenhouse gas impacts of wood and paper products. Hardwood (HW), softwood (SW), plywood (PW), oriented strand board (OSB), particleboard (PB), medium-density fiberboard (MDF), newsprint (NP), corrugated container (CC) and copy paper (CP) were buried in landfills operated with leachate recirculation, and were excavated after approximately 1.5 and 2.5 yr. Samples were analyzed for cellulose (C), hemicellulose (H), lignin (L), volatile solids (VS), and organic carbon (OC). A holocellulose decomposition index (HOD) and carbon storage factor (CSF) were calculated to evaluate the extent of solids decomposition and carbon storage. Samples of OSB made from HW exhibited cellulose plus hemicellulose (C + H) loss of up to 38%, while loss for the other wood types was 0–10% in most samples. The C + H loss was up to 81%, 95% and 96% for NP, CP and CC, respectively. The CSFs for wood and paper samples ranged from 0.34 to 0.47 and 0.02 to 0.27 g OC g−1 dry material, respectively. These results, in general, correlated well with an earlier laboratory-scale study, though NP and CC decomposition measured in this study were higher than previously reported. DA - 2013/11// PY - 2013/11// DO - 10.1016/j.wasman.2013.07.009 VL - 33 IS - 11 SP - 2267-2276 SN - 0956-053X KW - Landfills KW - Municipal solid waste KW - Forest products KW - Anaerobic decomposition KW - Biogenic carbon storage ER - TY - JOUR TI - Understanding Mechanisms Leading to Asphalt Binder Fatigue in the Dynamic Shear Rheometer (DSR) AU - Hintz, Cassie AU - Bahia, Hussain T2 - ASPHALT PAVING TECHNOLOGY 2013, VOL 82 AB - Asphalt binder fatigue resistance is important in determining overall pavement fatigue performance. One procedure commonly used to characterise asphalt binder fatigue resistance is the time sweep test, which consists of repeated cyclic loading in the dynamic shear rheometer (DSR). Generally, apparent changes in complex modulus and phase angle with respect to number of loading cycles are used to define fatigue performance. Although results from DSR testing have been shown to correlate well with asphalt mixture fatigue performance, the mechanisms responsible for changes in binder properties in the DSR were previously not well understood. Results in this study demonstrate that fracture can explain the changes in loading resistance during fatigue testing in the DSR. Under cyclic torsional loading of cylindrical specimens, fracture manifests as a circumferential crack that starts at the periphery of a sample and propagates inward, reducing the effective sample radius. Digital visualisation of binder specimens following testing allows for determination of the fractured and intact sample radius. Predictions of fracture propagation based on measurements of loading resistance and fracture mechanics concepts agreed favourably with direct measurements based on visualisation. Furthermore, it is shown in this study that fracture morphology and progression of crack growth of asphalt binders under time sweep testing match those observed for other materials under similar loading conditions. Based on these findings, fracture mechanics concepts are used to present an analysis framework that allows for predicting binder fatigue life at any loading amplitude using the results of a single time sweep test. DA - 2013/// PY - 2013/// DO - 10.1080/14680629.2013.818818 VL - 82 SP - 465-501 SN - 0270-2932 KW - asphalt binder KW - fatigue KW - fracture KW - failure mechanism ER - TY - JOUR TI - The Outer Loop bioreactor: A case study of settlement monitoring and solids decomposition AU - Abichou, Tarek AU - Barlaz, Morton A. AU - Green, Roger AU - Hater, Gary T2 - WASTE MANAGEMENT AB - The Outer Loop landfill bioreactor (OLLB) located in Louisville, KY, USA has been in operation since 2000 and represents an opportunity to evaluate long-term bioreactor monitoring data at a full-scale operational landfill. Three types of landfill units were studied including a Control cell, a new landfill area that had a piping network installed as waste was being placed to support leachate recirculation (As-Built cell), and a conventional landfill that was modified to allow for liquid recirculation (Retrofit cell). The objective of this study is to summarize the results of settlement data and assess how these data relate to solids decomposition monitoring at the OLLB. The Retrofit cells started to settle as soon as liquids were introduced. The cumulative settlement during the 8 years of monitoring varied from 60 to 100 cm. These results suggest that liquid recirculation in the Retrofit cells caused a 5–8% reduction in the thickness of the waste column. The average long-term settlement in the As-Built and Control Cells was about 37% and 19%, respectively. The modified compression index (Cα′) was 0.17 for the Control cells and 0.2–0.48 for the As-Built cells. While the As-Built cells exhibited greater settlement than the Control cells, the data do not support biodegradation as the only explanation. The increased settlement in the As-Built bioreactor cell appeared to be associated with liquid movement and not with biodegradation because both chemical (biochemical methane potential) and physical (moisture content) indicators of decomposition were similar in the Control and As-Built cells. The solids data are consistent with the concept that bioreactor operations accelerate the rate of decomposition, but not necessarily the cumulative loss of anaerobically degradable solids. DA - 2013/10// PY - 2013/10// DO - 10.1016/j.wasman.2013.02.005 VL - 33 IS - 10 SP - 2035-2047 SN - 0956-053X KW - Bioreactor landfill KW - Settlement KW - Solid decomposition KW - Leachate recirculation ER - TY - JOUR TI - Sustainable Infrastructure Materials: Challenges and Opportunities AU - Pour-Ghaz, Mohammad T2 - INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY AB - The recent quest for developing new low carbon footprint construction materials to lower the environmental emissions and implications of infrastructure has imposed many challenges and has created many opportunities for research and development in academia and industrial sectors. The present paper, discusses and summaries these challenges and opportunities and provides a synopsis of the ideas presented in the I nfrastructure sessions of the F ourth I nternational C ongress on C eramics ( ICC 4). This paper also discusses recent advances in the development of sustainable infrastructure materials. DA - 2013/7// PY - 2013/7// DO - 10.1111/ijac.12083 VL - 10 IS - 4 SP - 584-592 SN - 1546-542X ER - TY - JOUR TI - Microstructural investigation of asphalt concrete for performing multiscale experimental studies AU - Underwood, B. Shane AU - Kim, Y. Richard T2 - International Journal of Pavement Engineering AB - Abstract In this paper, a microstructural hypothesis for asphalt concrete (AC) is developed in order to provide a basis for a multiscale experimental investigation. The hypothesis is consistent with the belief that AC can be considered as a four-scale assemblage of components with different characteristic length scale, binder, mastic, fine aggregate matrix (FAM) and finally AC. The hypothesis is supported with a series of direct microstructural experiments including morphological observations with digital and scanning electron microscopy as well as quantitative evaluation using a novel meso-gravimetric test method developed specifically for this research. Morphological evaluation shows that asphalt mastic effectively exists as a basic building block for AC. Meso-gravimetric analysis finds that the volumetric composition of this mastic is equal to that found when assuming that mastic contains all of the effective asphalt binder and the filler-sized particles. Other key volumetric properties including FAM gradation and mastic concentration within the FAM and mixture are presented as well. Keywords: asphaltmasticfine aggregate matrixmultiscale modellingscanning electron microscopy DA - 2013/7// PY - 2013/7// DO - 10.1080/10298436.2012.746689 VL - 14 IS - 5 SP - 498-516 J2 - International Journal of Pavement Engineering LA - en OP - SN - 1029-8436 1477-268X UR - http://dx.doi.org/10.1080/10298436.2012.746689 DB - Crossref KW - asphalt KW - mastic KW - fine aggregate matrix KW - multiscale modelling KW - scanning electron microscopy ER - TY - JOUR TI - Method for Measuring the Ratio of In-Vehicle to Near-Vehicle Exposure Concentrations of Airborne Fine Particles AU - Jiao, Wan AU - Frey, H. Christopher T2 - TRANSPORTATION RESEARCH RECORD AB - Human exposure to fine particulate matter of less than 2.5 microns in aerodynamic diameter is causally linked to cardiovascular and pulmonary diseases. In-vehicle exposure may account for 10% to 20% of daily average exposure. However, exposure models are typically based on areawide air quality data that poorly predict in-vehicle concentration. A practical method is demonstrated for conducting field measurements to quantify the ratio of in-vehicle to outside vehicle concentration (I/O) for a wide range of conditions that affect intravehicle variability in exposure concentration. A field data collection study design is developed on the basis of sources of intravehicle variability in I/O that include ventilation air source, window status, fan setting, air-conditioning (AC) use, vehicle speed, road type, travel direction, and time of day. Three replicates of measurements were made for 16 combinations of these factors on 110 mi of roads comprising eight one-way routes between typical commuter origin–destination pairs. Two portable particle monitors recorded in-vehicle and near-vehicle ambient concentrations on 1-min averages for four particle size ranges. The comparability of the monitors was quantified. Near-vehicle concentrations varied with road type, time of day, and traffic conditions. The I/O ratio was approximately independent of near-vehicle concentration and varied with window status, source of ventilation air (fresh or recirculated), and for cases with recirculation and closed windows, fan setting, and AC use. The study design can be extended to additional vehicles to account for potential sources of inter-vehicle variability. Data collected here can be used to improve exposure simulation models. DA - 2013/// PY - 2013/// DO - 10.3141/2341-04 IS - 2341 SP - 34-42 SN - 2169-4052 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84887641213&partnerID=MN8TOARS ER - TY - JOUR TI - Measurement of carbon storage in landfills from the biogenic carbon content of excavated waste samples AU - Cruz, Florentino B. AU - Chanton, Jeffrey P. AU - Barlaz, Morton A. T2 - WASTE MANAGEMENT AB - Landfills are an anaerobic ecosystem and represent the major disposal alternative for municipal solid waste (MSW) in the U.S. While some fraction of the biogenic carbon, primarily cellulose (Cel) and hemicellulose (H), is converted to carbon dioxide and methane, lignin (L) is essentially recalcitrant. The biogenic carbon that is not mineralized is stored within the landfill. This carbon storage represents a significant component of a landfill carbon balance. The fraction of biogenic carbon that is not reactive in the landfill environment and therefore stored was derived for samples of excavated waste by measurement of the total organic carbon, its biogenic fraction, and the remaining methane potential. The average biogenic carbon content of the excavated samples was 64.6 ± 18.0% (average ± standard deviation), while the average carbon storage factor was 0.09 ± 0.06 g biogenic-C stored per g dry sample or 0.66 ± 0.16 g biogenic-C stored per g biogenic C. DA - 2013/10// PY - 2013/10// DO - 10.1016/j.wasman.2012.12.012 VL - 33 IS - 10 SP - 2001-2005 SN - 0956-053X KW - Landfill KW - Carbon storage KW - Municipal solid waste ER - TY - JOUR TI - Liquid balance monitoring inside conventional, Retrofit, and bio-reactor landfill cells AU - Abichou, Tarek AU - Barlaz, Morton A. AU - Green, Roger AU - Hater, Gary T2 - WASTE MANAGEMENT AB - The Outer Loop landfill bioreactor (OLLB) in Louisville, KY, USA has been the site of a study to evaluate long-term bioreactor performance at a full-scale operational landfill. Three types of landfill units were studied including a conventional landfill (Control cell), a new landfill area that had an air addition and recirculation piping network installed as waste was being placed (As-Built cell), and a conventional landfill that was modified to allow for liquids recirculation (Retrofit cell). During the monitoring period, the Retrofit, Control, and As-Built cells received 48, 14, and 213LMg(-1) (liters of liquids per metric ton of waste), respectively. The leachate collection system yielded 60, 57 and 198LMg(-1) from the Retrofit, Control, and As-Built cells, respectively. The head on liner in all cells was below regulatory limits. In the Control and As-Built cells, leachate head on liner decreased once waste placement stopped. The measured moisture content of the waste samples was consistent with that calculated from the estimate of accumulated liquid by the liquid balance. Additionally, measurements on excavated solid waste samples revealed large spatial variability in waste moisture content. The degree of saturation in the Control cells decreased from 85% to 75%. The degree of saturation increased from 82% to 83% due to liquids addition in the Retrofit cells and decreased back to 80% once liquid addition stopped. In the As-Built cells, the degree of saturation increased from 87% to 97% during filling activities and then started to decrease soon after filling activities stopped to reach 92% at the end of the monitoring period. The measured leachate generation rates were used to estimate an in-place saturated hydraulic conductivity of the MSW in the range of 10(-8) to 10(-7)ms(-1) which is lower than previous reports. In the Control and Retrofit cells, the net loss in liquids, 43 and 12LMg(-1), respectively, was similar to the measured settlement of 15% and 5-8% strain, respectively (Abichou et al., 2013). The increase in net liquid volume in the As-Built cells indicates that the 37% (average) measured settlement strain in these cells cannot be due to consolidation as the waste mass did not lose any moisture but rather suggests that settlement was attributable to lubrication of waste particle contacts, softening of flexible porous materials, and additional biological degradation. DA - 2013/10// PY - 2013/10// DO - 10.1016/j.wasman.2013.05.023 VL - 33 IS - 10 SP - 2006-2014 SN - 1879-2456 KW - Landfill KW - Bioreactor KW - Leachate KW - Recirculation KW - Liquid balance ER - TY - JOUR TI - Gradation effects on the mechanical response of crushed stone aggregate AU - Cunningham, Charles N. AU - Evans, T. Matthew AU - Tayebali, Akhtar A. T2 - INTERNATIONAL JOURNAL OF PAVEMENT ENGINEERING AB - A study was conducted to evaluate the effects of varying the gradation of aggregate base course (ABC) on material performance. Five different gradations consistent with a range of common ABC were selected. Experimental trials were performed to classify the materials and assess the performance differences between the five gradations. The gradation was found to affect the behaviour of the aggregate in that coarser gradations gave better strength and resilience values under conditions most similar to those found in the field. From research and experience during the laboratory testing, it was concluded that the coarsest blends became too difficult to realistically work with and they also lacked the stability of the well-graded combinations. It was also observed that as the amount of fines in the specimens exceeded 8–12% by mass, the fines governed the behaviour of the material. Results are interpreted using previously published work on specific surface, ‘ideal’ gradations and micromechanical models for the response of granular materials. DA - 2013/4/1/ PY - 2013/4/1/ DO - 10.1080/10298436.2012.690518 VL - 14 IS - 3 SP - 231-241 SN - 1477-268X KW - base course KW - gradation KW - triaxial testing KW - Atterberg limits KW - resilient modulus KW - shear strength ER - TY - JOUR TI - Effects of higher percentage of recycled asphalt pavement on pavement performance AU - Visintine, Beth AU - Khosla, N. Paul AU - Tayebali, Akhtar T2 - ROAD MATERIALS AND PAVEMENT DESIGN AB - The recycling of asphalt pavements has become a very routine procedure throughout the country. Research has shown that the recycled asphalt pavement (RAP) recovered from construction sites still contains usable materials, both in the recycled aggregates and recycled binder. The fatigue life and rut resistance of mixtures containing various amounts of recycled asphalt pavement (RAP) were compared with a virgin mixture. The fatigue life and rut resistance of the mixtures were calculated from laboratory testing using Frequency Sweep Testing using Superpave Simple Shear Tester (SST) and Repeated Simple Shear Tests using (SST) device. The SHRP A-003A surrogate models and the Asphalt Institute models were both be used in order to predict pavement performance using the results from the Frequency Sweep Testing and the Repeated Simple Shear Test. DA - 2013/6/1/ PY - 2013/6/1/ DO - 10.1080/14680629.2013.779310 VL - 14 IS - 2 SP - 432-437 SN - 1468-0629 KW - RAP KW - fatigue life KW - rut resistance KW - pavement performance ER - TY - JOUR TI - Effect of Load History on Performance Limit States of Circular Bridge Columns AU - Goodnight, Jason C. AU - Kowalsky, Mervyn J. AU - Nau, James M. T2 - JOURNAL OF BRIDGE ENGINEERING AB - In this paper, the importance of displacement history and its effects on performance limit states, the relationship between strain and displacement, and the spread of plasticity in RC structures is explored. An experimental study is underway to assess the performance of 30 circular, well-confined, bridge columns with varying lateral displacement history, transverse reinforcement detailing, axial load, aspect ratio, and longitudinal steel content. Eight of these columns, with similar geometry and detailing, were subjected to various unidirectional displacement histories including standardized laboratory reversed cyclic loading and re-creations of the displacement responses obtained from a nonlinear time-history analysis of multiple earthquakes with distinct characteristics. Longitudinal reinforcing bars were instrumented to obtain strain hysteresis, vertical strain profiles, cross section curvatures, curvature distributions, and fixed-end rotations attributable to strain penetration. Results have shown that the limit state of reinforcement bar buckling was influenced by load history, but the relationship between strain and displacement along the envelope curve was not. The main impact of load history on bar buckling is its influence on accumulated strains within the longitudinal reinforcement and transverse steel. DA - 2013/12/1/ PY - 2013/12/1/ DO - 10.1061/(asce)be.1943-5592.0000495 VL - 18 IS - 12 SP - 1383-1396 SN - 1943-5592 KW - Load history KW - Limit states KW - Buckling KW - Bridges KW - Columns KW - Load history KW - Performance limit states KW - Bar buckling KW - Bridge columns ER - TY - JOUR TI - Development of a failure criterion for asphalt mixtures under fatigue loading AU - Zhang, Jun AU - Sabouri, Mohammadreza AU - Guddati, Murthy N. AU - Kim, Y. Richard T2 - ROAD MATERIALS AND PAVEMENT DESIGN AB - Abstract The failure criterion defines the applicable region associated with the continuum damage model and is important in characterising the service life of asphalt mixtures. A proper failure criterion should consistently predict the failure of the material that reaches macro-fracture. A previously developed criterion that uses the viscoelastic continuum damage (VECD) model exhibits high variability and is considered to be inefficient because it requires calibration tests at different temperatures. In this paper, a new concept that involves released pseudo strain energy is introduced. This released pseudo strain energy concept focuses on the dissipated energy that is related to stiffness reduction only and is fully compatible and predictable using the VECD model. A characteristic relationship is found between the stable rate of pseudo energy release during testing and the final fatigue life of the same mixture, independent of strain amplitude and temperature. Based on these observations, a new failure criterion is proposed. The proposed failure criterion combines the advantages of the VECD model and this characteristic relationship, which both originate from fundamental mixture properties, and is able to predict the fatigue life of asphalt concrete mixtures across different temperatures and strain amplitudes. Keywords: failure criterionfatigueasphaltpseudo energyviscoelasticdamage Acknowledgements This research was funded by Texas A&M University as part of the Asphalt Research Consortium project and by the University of New Hampshire as part of the New England RAP project. The authors gratefully acknowledge their support. DA - 2013/8/1/ PY - 2013/8/1/ DO - 10.1080/14680629.2013.812843 VL - 14 SP - 1-15 SN - 2164-7402 KW - failure criterion KW - fatigue KW - asphalt KW - pseudo energy KW - viscoelastic KW - damage ER - TY - JOUR TI - Determining the limits of anaerobic co-digestion of thickened waste activated sludge with grease interceptor waste AU - Wang, Ling AU - Aziz, Tarek N. AU - Reyes, Francis L., III T2 - WATER RESEARCH AB - Anaerobic co-digestion of thickened waste activated sludge (TWAS) with grease interceptor waste (GIW) from a food service establishment was conducted in lab scale semi-continuous digesters. GIW included the entire contents of the grease interceptor (GI) including fat, oil, and grease (FOG), food residuals, and associated wastewater. GIW was added in step increases to identify the maximum methane production and the corresponding threshold input of GIW that led to inhibition of methanogenesis. The experiment was performed at mesophilic conditions (37 °C) with a solids retention time (SRT) of 20 days. The highest GIW addition rate achieved without digester failure was 20% (v/v), or 65.5% (w/w) of volatile solids (VS) added, enhancing the methane yield from 0.180 to 0.752 mCH43/kgVSadded, biogas production from 2.2 × 10−3 to 1.4 × 10−2 m3/d, and methane content from 60.2% to 70.1%. The methane yield of 0.752 mCH43/kgVSadded is the highest value reported to date for co-digestion of GIW. Stepwise increases in co-substrate addition led to better microbial acclimation and reduced the GIW inhibitory effect. The limit for GIW addition leading to an inhibited digestion process was identified to be between 20 and 40% (v/v) or 65.5 and 83.5% (w/w) of VS added. The results show the significant benefits of anaerobic co-digestion of GIW and the positive impacts of gradual addition of GIW. DA - 2013/7/1/ PY - 2013/7/1/ DO - 10.1016/j.watres.2013.04.003 VL - 47 IS - 11 SP - 3835-3844 SN - 0043-1354 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84878477665&partnerID=MN8TOARS KW - Anaerobic co-digestion KW - FOG KW - Grease interceptor KW - Grease trap ER - TY - JOUR TI - Comparison of Locomotive Emissions Measured During Dynamometer Versus Rail Yard Engine Load Tests AU - Graver, Brandon M. AU - Frey, H. Christopher T2 - TRANSPORTATION RESEARCH RECORD AB - For environmental emissions certification, locomotive prime mover engines undergo rigorous measurements with the use of federal reference methods (FRMs). However, there are nonregulatory reasons for engine emissions measurement, such as to compare relative differences in fuel use and emissions as a result of engine rebuild or between engines in a fleet. Portable emissions measurement systems (PEMSs) are widely used for highway vehicle and nonroad construction equipment but have had limited locomotive applications. The objectives are to (a) demonstrate an approach for quantifying locomotive emission rates with a PEMS during dynamometer and rail yard engine load tests, (b) compare the emissions measured in dynamometer versus rail yard load tests, and (c) assess the relative change in fuel use and emissions from engine rebuild. Measurements were conducted on 3,000-hp prime movers, including an EMD 16-645 for a GP40 and two EMD 12-710s for F59PHs. Fuel use and PEMS-based emission rates for nitric oxide, carbon monoxide, hydrocarbons, and particulate matter were compared between dynamometer and rail yard load tests and with data from previous literature. Fuel use and oxides of nitrogen (NO x ) emission rates after engine rebuild were lower for the GP40 prime mover, and the fuel use and NO x emission rates for the F59PH rebuilt engines were lower than those of the rebuilt GP40 engine. PEMS is not a substitute for locomotive FRMs if compliance certification is needed but provides useful data for comparative assessment. DA - 2013/// PY - 2013/// DO - 10.3141/2341-03 IS - 2341 SP - 23-33 SN - 2169-4052 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84887758744&partnerID=MN8TOARS ER - TY - JOUR TI - Bond Behavior between Basalt Fiber-Reinforced Polymer Sheet and Concrete Substrate under the Coupled Effects of Freeze-Thaw Cycling and Sustained Load AU - Shi, Jiawei AU - Zhu, Hong AU - Wu, Zhishen AU - Seracino, Rudolf AU - Wu, Gang T2 - JOURNAL OF COMPOSITES FOR CONSTRUCTION AB - This paper presents an experimental investigation on the bond behavior between basalt fiber–reinforced polymer (BFRP) sheet and concrete substrate under the coupled effects of freeze-thaw cycling and sustained load. Test variables were freeze-thaw cycles, level of sustained load, and adhesive type. Double-lap shear specimens were used in the tests, and a specially designed reaction-loading system was used to apply the sustained load during freeze-thaw cycles. Specimens with or without sustained load were exposed to up to 300 freeze-thaw cycles. A modified epoxy resin, made by adding a toughening agent to the original epoxy resin, was used in the test to study the effect of adhesive type on the durability of the BFRP–concrete interface. Coupon tests were also conducted to determine the freeze-thaw resistance of the constituent materials of the BFRP–concrete interface. After exposure, double-lap shear tests were carried out to investigate the residual bond capacity of the BFRP–concrete interface. Digital image correlation measurement was applied to capture the full-field deformation of the FRP sheet and the concrete block during the double-lap shear tests. A nonlinear bond-slip relationship of the BFRP–concrete interface was determined based on the analysis of displacement data. Test results show that (1) the bond capacity of the BFRP–concrete interface decreases with increasing freeze-thaw cycles, (2) the failure mode changes from debonding in the concrete layer to debonding in the adhesive layer, (3) extra degradation of the bond-slip relationship could be caused by the coupled effects, and (4) the durability improvement of the adhesive may result in a better durability of the BFRP–concrete bond capacity in a freeze-thaw environment. Finally, the coupled effects and evaluation of freeze-thaw procedures on the bond degradation of FRP–concrete interface are discussed. DA - 2013/8/1/ PY - 2013/8/1/ DO - 10.1061/(asce)cc.1943-5614.0000349 VL - 17 IS - 4 SP - 530-542 SN - 1090-0268 KW - Coupled effects KW - Freeze-thaw cycling KW - Sustained load KW - Basalt fiber-reinforced polymer KW - Bond KW - Durability ER - TY - JOUR TI - A Two-Dimensional Laminar Flow Model for Thermodenuders Applied to Vapor Pressure Measurements AU - Park, Sung Hoon AU - Rogak, Steven N. AU - Grieshop, Andrew P. T2 - AEROSOL SCIENCE AND TECHNOLOGY AB - Thermodenuders (TD) have been used to quantify the volatility of aerosol species, frequently with the aid of modeling. Here we present a two-dimensional model of flow, heat transfer, and aerosol dynamics that is fast, yet includes spatial resolution of the complete aerosol size distribution. We first demonstrate the utility of the model by interpreting nonequilibrium TD measurement data previously reported in the literature. It is shown that the thermogram (temperature vs. mass fraction remaining) curve is remarkably insensitive to radial variations in temperature and vapor concentration under typical conditions. Therefore, the discrepancies among vapor pressure estimates determined in TD studies are unlikely to be due to oversimplified flow models, but are instead likely due to faulty assumptions concerning evaporation kinetics. We then show that the best-fit range for the parameters that dictate equilibrium partitioning (saturation vapor pressure at a reference temperature and enthalpy of vaporization) can also be obtained by fitting nonequilibrium TD data using a three-parameter model that accounts for mass transfer limitations (by also fitting the evaporation coefficient). The degree of agreement between experiments and model simulations are examined for two dicarboxylic acids using the model developed in this study. The best-fit parameters were within the uncertainty range previously found using an “equilibrated” TD approach for butanedioic acid, whereas significantly better model-experiment agreement was obtained for a much lower value of enthalpy of vaporization than previously reported for hexanedioic acid. DA - 2013/3/1/ PY - 2013/3/1/ DO - 10.1080/02786826.2012.750711 VL - 47 IS - 3 SP - 283-293 SN - 1521-7388 ER - TY - JOUR TI - A Mechanistic Permanent Deformation Model for Asphalt Concrete in Compression AU - Choi, Yeong-Tae AU - Kim, Y. Richard T2 - ASPHALT PAVING TECHNOLOGY 2013, VOL 82 AB - Abstract Permanent deformation modelling research at North Carolina State University has produced the so-called incremental model that fits the primary and secondary regions in permanent strain growth. Triaxial repeated load permanent deformation tests are conducted on Federal Highway Administration-Accelerated Loading Facility and NY9.5B mixtures to evaluate the effects of temperature, stress, and load time on permanent deformation and, therefore, to determine the form of the incremental model to account for these effects. The test results suggest that the slope in the log(ϵvp)−log(N) plot is constant regardless of these three major factors. This observation provides the basis for two modelling approaches: the functionalised model and the shift model. The functionalised model is formulated by expressing the coefficients of the incremental model in terms of the reduced load time and deviatoric stress. The shift model, based on the time-temperature–stress superposition principle, utilises the strain mastercurve and reduced load time and deviatoric stress shift functions. A composite loading test that is composed of varying load times and deviatoric stresses is proposed as the model calibration test. It is found that the permanent strain growth under the complex loading histories predicted by the calibrated models is in good agreement with the measured permanent strain growth. Keywords: permanent deformationruttingincremental modelfunctionalised modelshift modeltime-stress superposition Acknowledgements This research is sponsored by the Federal Highway Administration under project No. DTFH61-08-H-00005, Hot Mix Asphalt Performance-Related Specifications Based on Viscoelastoplastic Continuum Damage Models. The authors gratefully acknowledge the FHWA's support. DA - 2013/// PY - 2013/// DO - 10.1080/14680629.2013.812847 VL - 82 SP - 617-649 SN - 0270-2932 KW - permanent deformation KW - rutting KW - incremental model KW - functionalized model KW - shift model KW - time-stress superposition ER - TY - JOUR TI - Seismic fragility evaluation of piping system installed in critical structures AU - Ju, B. S. AU - Jung, W. Y. AU - Ryu, Y. H. T2 - Structural Engineering and Mechanics DA - 2013/// PY - 2013/// VL - 46 IS - 3 SP - 337-352 ER - TY - JOUR TI - Parametric study using finite element simulation for low cycle fatigue behavior of end plate moment connection AU - Lim, C. M. AU - Choi, W. C. AU - Sumner, E. A. T2 - Steel and Composite Structures DA - 2013/// PY - 2013/// VL - 14 IS - 1 SP - 57-71 ER - TY - JOUR TI - Modeling Effect of Geocomposite Drainage Layers on Moisture Distribution and Plastic Deformation of Road Sections AU - Bahador, M. AU - Evans, T. M. AU - Gabr, M. A. T2 - JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING AB - The effect of geosynthetic layers on moisture distribution and plastic deformation of paved and unpaved road sections is studied using numerical simulations. The geosynthetic layers consisted of, from top to bottom, a transport layer, a geonet, and a nonwoven geotextile (referred to as a geocomposite capillary barrier drain by previous researchers). Two geotextile types were modeled as the transport layer: woven fiberglass and nonwoven polypropylene. The numerical models were verified against published results obtained from a soil-geotextile column. Inclusion of the geosynthetic layers at the interface of the aggregate base course (ABC) and subgrade increased suction in the subgrade and decreased it in the ABC during a simulated rainfall event. The woven fiberglass geotextile led to higher suctions in the ABC compared with the nonwoven polypropylene geotextile. The geosynthetic layers decreased the plastic deformation in both paved and unpaved road sections through combined mechanistic and hydraulic actions. Increasing the thickness of the asphalt and ABC layers decreased the reinforcement effect of the geotextile while increasing its beneficial hydraulic effect in term of the suction level. In sections with a thinner asphalt layer, the woven fiberglass, functioning as a transport layer, decreased the plastic deformation of the profile by up to 20% compared with the profile with the nonwoven polypropylene geotextile. Increasing the thickness of the asphalt layer, however, reduced this difference to approximately 4%. In unpaved sections, the inclusion of the woven fiberglass layer decreased the plastic deformation by approximately 24% more than the profile with nonwoven polypropylene geotextrile, regardless of the aggregate base course thickness used in the analysis. DA - 2013/9// PY - 2013/9// DO - 10.1061/(asce)gt.1943-5606.0000877 VL - 139 IS - 9 SP - 1407-1418 SN - 1943-5606 KW - Deformation KW - Geocomposite KW - Moisture KW - Pavement KW - Reinforcement KW - Subgrade KW - Suction ER - TY - JOUR TI - Assessment of Scour on Bridge Foundations by Means of In Situ Erosion Evaluation Probe AU - Kayser, Mohammad AU - Gabr, Mohammed A. T2 - TRANSPORTATION RESEARCH RECORD AB - The work in this paper presents the use of an in situ erosion evaluation probe (ISEEP) to assess scour depth at bridge piers. Numerical modeling and deployment of the device at a North Carolina Outer Banks site damaged by Hurricane Irene in 2011 demonstrates the applicability of the proposed concept. Computational fluid dynamics software, FLOW-3D, was used to assess the scour depth at a bridge pier, and the results were compared with values based on ISEEP-estimated parameters by using an excess-stream power model. The scour depth was also calculated from empirical equations that assumed the same conditions as those used in the numerical analysis. Parametric analysis using FLOW-3D indicated that of the parameters for defining the scour depth, the entrainment coefficient had the largest effect, whereas the drag coefficient had the smallest effect on the scour magnitude within the range of values included in this analysis. The estimated scour depths that were based on ISEEP data agreed relatively well with the scour magnitudes obtained from the numerical analysis, as the ISEEP data reflected the changes in the properties of the sand layer with depth. In contrast, the scour magnitude calculated from the empirical equations underestimated the scour depth, mainly because these equations had no provision for a layered-soil profile. Further validation of both the field-testing procedure and the data reduction approach, including the assessment of the applicability in soils that contain an appreciable percentage of fines, is recommended. DA - 2013/// PY - 2013/// DO - 10.3141/2335-08 VL - 2335 IS - 2335 SP - 72-78 SN - 2169-4052 ER - TY - JOUR TI - Preliminary Engineering Cost Estimation Model for Bridge Projects AU - Hollar, Donna A. AU - Rasdorf, William AU - Liu, Min AU - Hummer, Joseph E. AU - Arocho, Ingrid AU - Hsiang, Simon M. T2 - Journal of Construction Engineering and Management AB - This paper addresses one of the costs of new bridges, i.e., the cost of doing the preliminary engineering (PE). This particular aspect of cost has largely been neglected because of the difficulty in obtaining appropriate data. Typically, PE costs are determined as a percentage of construction costs, disregarding other project-specific parameters. Bridge projects let by the North Carolina (NC) DOT between 2001 and 2009 were reviewed. From an analysis of these 461 projects, the writers developed statistical models linking variation in PE costs with distinctive project parameters. The primary contribution this paper makes to the body of knowledge is the finding that PE cost estimates for bridge projects are commonly and significantly underestimated. The writers found that bridge projects exhibited a mean PE cost ratio of 28%. This result is significantly greater than the percentage used in practice. An investigation of data sources related to bridge projects, a description of regression techniques applied to predict the PE cost of such projects, and an assessment of the predictive performance of models are addressed in this paper. New knowledge contributions include identification of key factors affecting the PE costs of bridges, illustration of how those key factors enabled us to predict PE costs of future projects, and discussion of the data collection problems that hindered model development. The writers’ PE cost analyses and predictive modeling effort relate to infrastructure funding issues. All of the parties involved in infrastructure construction, from legislators to contractors, must understand costs and have confidence in the cost estimates developed to ensure efficient and effective funding of infrastructure projects. This paper on bridge PE costs addresses one component of infrastructure funding. DA - 2013/9// PY - 2013/9// DO - 10.1061/(asce)co.1943-7862.0000668 VL - 139 IS - 9 SP - 1259-1267 J2 - J. Constr. Eng. Manage. LA - en OP - SN - 0733-9364 1943-7862 UR - http://dx.doi.org/10.1061/(asce)co.1943-7862.0000668 DB - Crossref KW - Construction management KW - Infrastructure KW - Bridges KW - Construction costs KW - Budgets KW - Preliminary engineering KW - Preconstruction KW - Infrastructure KW - Bridges KW - Cost estimation KW - Regression KW - Planning KW - Design KW - Budget control KW - Project planning and design ER - TY - JOUR TI - Microstructural Association Model for Upscaling Prediction of Asphalt Concrete Dynamic Modulus AU - Underwood, B. Shane AU - Kim, Y. Richard T2 - Journal of Materials in Civil Engineering AB - Multiscale modeling is becoming an increasingly useful method of evaluating the behaviors of asphalt concrete. Reasons for this increased interest include the fact that many of the critical behaviors of this material are affected by localized behaviors that cannot be completely captured using more traditional continuum approaches. Computational methods are popular for this type of evaluation because in principle they can directly account for many of the localized mechanisms. However, computational expense can be excessive, particularly if all of these localized mechanisms are accounted for rigorously. An alternative method of multiscale modeling relying on analytical models is developed and presented in this paper. The model is referred to as the microstructure association model because it accounts for the ways that the multiple scales within asphalt concrete associate together to yield the gross behaviors of the finished composite, asphalt concrete. This model is formed from the hypothesis that asphaltic composites at different length scales evolve along a continuum, which is related to the degree of internal structuralization that exists within the composite. In this way asphalt mixture may behave in a quantitatively similar way as asphalt mastic if the concentration of particles within the mastic produces the same degree of internal structuralization as that which exists in the asphalt mixture. Through this modeling effort two separate, but possibly related, mechanisms are identified: (1) interaction of particles separated by some distance, but still influenced by an adsorbed and nonadsorbed asphalt binding medium; and (2) close-proximity contacts of aggregate particles that lead to a significant increase in stiffness with relatively small changes in volumetric concentration. Each of these mechanisms is modeled separately within the microstructural association model and combined using a rational mechanical analog approach. The model is characterized using only experiments on asphalt mastic at different concentrations, but is verified with its ability to upscale to the modulus of asphalt concrete. In the final section of this paper the ability of the model to perform useful engineering tasks is shown when it is used to assess the impact of asphalt content and air void content changes on the modulus of two different materials. DA - 2013/9// PY - 2013/9// DO - 10.1061/(asce)mt.1943-5533.0000657 VL - 25 IS - 9 SP - 1153-1161 J2 - J. Mater. Civ. Eng. LA - en OP - SN - 0899-1561 1943-5533 UR - http://dx.doi.org/10.1061/(ASCE)MT.1943-5533.0000657 DB - Crossref KW - Multiscale model KW - Asphalt mixture KW - Linear viscoelastic KW - Mastic KW - Upscale KW - Adsorbed asphalt ER - TY - JOUR TI - Mechanisms of Fat, Oil and Grease (FOG) deposit formation in sewer lines AU - He, Xia AU - Reyes, Francis L., III AU - Leming, Michael L. AU - Dean, Lisa O. AU - Lappi, Simon E. AU - Ducoste, Joel J. T2 - WATER RESEARCH AB - FOG deposits in sewer systems have recently been shown to be metallic salts of fatty acids. However, the fate and transport of FOG deposit reactant constituents and the complex interactions during the FOG deposit formation process are still largely unknown. In this study, batch tests were performed to elucidate the mechanisms of FOG deposit formation that lead to sanitary sewer overflows (SSOs). We report the first formation of FOG deposits on a concrete surface under laboratory conditions that mimic the formation of deposits in sewer systems. Results showed that calcium, the dominant metal in FOG deposits, can be released from concrete surfaces under low pH conditions and contribute to the formation process. Small amounts of additional oil to grease interceptor effluent substantially facilitated the air/water or pipe surface/water interfacial reaction between free fatty acids and calcium to produce surface FOG deposits. Tests of different fatty acids revealed that more viscous FOG deposit solids were formed on concrete surfaces, and concrete corrosion was accelerated, in the presence of unsaturated FFAs versus saturated FFAs. Based on all the data, a comprehensive model was proposed for the mechanisms of FOG deposit formation in sewer systems. DA - 2013/9/1/ PY - 2013/9/1/ DO - 10.1016/j.watres.2013.05.002 VL - 47 IS - 13 SP - 4451-4459 SN - 0043-1354 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84879016648&partnerID=MN8TOARS KW - Sanitary sewer overflows (SSOs) KW - Fat, Oil and Grease (FOG) deposits KW - Free fatty acids (FFAs) KW - Calcium KW - FOG deposit formation KW - Sewer lines ER - TY - JOUR TI - Integrating evolution strategies and genetic algorithms with agent-based modeling for flushing a contaminated water distribution system AU - Zechman, Emily M. T2 - Journal of Hydroinformatics AB - Water utilities can prepare for water distribution hazards, such as the presence of contaminants in the pipe network and failure of physical components. In contamination events, the complex interactions among managers' operational decisions, consumers' water consumption choices, and the hydraulics and contaminant transport in the water distribution system may influence the contaminant plume so that a typical engineering model may not properly predict public health consequences. A complex adaptive system (CAS) approach couples engineering models of a water distribution system with agent-based models of consumers and public officials. Development of threat management strategies, which prescribe a set of actions to mitigate public health consequences, is enabled through a simulation–optimization framework that couples evolutionary algorithms with the CAS model. Evolution strategies and genetic algorithm-based approaches are developed and compared for an illustrative case study to identify a flushing strategy for opening hydrants to minimize the number of exposed consumers and maintain acceptable levels of service in the network. DA - 2013/7// PY - 2013/7// DO - 10.2166/hydro.2013.102 VL - 15 IS - 3 SP - 798-812 J2 - J Hydroinform LA - en OP - SN - 1464-7141 1465-1734 UR - http://dx.doi.org/10.2166/hydro.2013.102 DB - Crossref KW - agent-based model KW - evolutionary algorithms KW - sociotechnical systems KW - water distribution system security ER - TY - JOUR TI - Effects of production practices on camber of prestressed concrete bridge girders Response AU - Storm, T. K. AU - Rizkalla, S. H. AU - Zia, P. Z. T2 - PCI Journal DA - 2013/// PY - 2013/// SP - 143-144 ER - TY - JOUR TI - Effects of errors on vehicle emission rates from portable emissions measurement systems AU - Sandhu, G. AU - Frey, H. T2 - Transportation Research Record AB - Portable emissions measurement systems (PEMS) are useful for quantification of real-world vehicle activity, energy use, and emissions. However, there is no standard methodology for processing PEMS data; this can lead to errors in reported results. PEMS typically include tailpipe exhaust gas and particle analyzers, Global Positioning System (GPS) receivers, engine sensors, and electronic control unit (ECU) data loggers. The sensitivity of estimated emission rates to random errors in measurements is quantified. Methods are evaluated for identification and correction of improper synchronization of PEMS, ECU, and GPS data streams and for road grade estimation. Estimated fuel use and emission rates for light- and heavy-duty vehicles are sensitive to errors in intake manifold absolute pressure and engine revolutions per minute values and in indicators of air-to-fuel ratio including carbon dioxide and oxygen concentrations. Synchronization can be aided by maximizing the Pearson correlation coefficient between two indicator variables and confirming the result by matching concurrent increases in indicator variables. The effect of improper synchronization on estimated modal emission rates is quantified. Modal average emission rates based on vehicle-specific power (VSP) are more sensitive to improperly synchronized engine versus GPS data. Improperly synchronized data streams result in decreased variability between the lowest and highest modal average emission rates. Estimation of road grade from a linear least squares slope of elevation over a specified distance is demonstrated. VSP-based modal fuel use and pollutant emission rates are less sensitive to differences in road grade than to errors in synchronization. DA - 2013/// PY - 2013/// DO - 10.3141/2340-02 IS - 2340 SP - 10-19 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84883041079&partnerID=MN8TOARS ER - TY - JOUR TI - Effects of License Plate Attributes on Automatic License Plate Recognition AU - Findley, Daniel J. AU - Cunningham, Christopher M. AU - Chang, Jeffrey C. AU - Hovey, Kyle A. AU - Corwin, Michael A. T2 - TRANSPORTATION RESEARCH RECORD AB - This paper describes an experiment designed to develop a comprehensive and thorough understanding of the readability of North Carolina's license plates with an automatic license plate recognition system. This research focused on law enforcement applications and used two infrared camera systems for data collection in a controlled environment involving more than 900 license plates. The field test was conducted in a controlled environment under the following settings and conditions: a test vehicle traveling at 25 mph, nighttime evaluation, closed test track, 40 ft of spacing of license plates, 9 ft of lateral offset between the license plates and camera, standard issue and specialty plate types, standard syntax and personalized plates, and various license plate ages and conditions. The key finding of this research project is that the current, standard issue license plate with characters in blue ink has the highest capture and read rates among the plates tested in this study. Factors that decreased the capture and read rates were personalized syntax, specialty license plates, and the presence of stacked characters on a specialty license plate. DA - 2013/// PY - 2013/// DO - 10.3141/2327-05 IS - 2327 SP - 34-44 SN - 0361-1981 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000323141900006&KeyUID=WOS:000323141900006 ER - TY - JOUR TI - Development of a simultaneous search-based pilot point method for subsurface characterization AU - Jung, Yong AU - Mahinthakumar, G. AU - Ranjithan, Ranji T2 - STOCHASTIC ENVIRONMENTAL RESEARCH AND RISK ASSESSMENT DA - 2013/12// PY - 2013/12// DO - 10.1007/s00477-013-0734-x VL - 27 IS - 8 SP - 2003-2013 SN - 1436-3259 KW - Hydraulic conductivity KW - SSBM KW - DBM KW - Global optimization ER - TY - JOUR TI - Application of Time Buffers to Construction Project Task Durations AU - Russell, Marion M. AU - Howell, Gregory AU - Hsiang, Simon M. AU - Liu, Min T2 - Journal of Construction Engineering and Management AB - For this research, a time buffer is defined as the extra time added during planning to individual task durations to compensate for uncertainty and protect against workflow variation to assure a predictable hand-off to subsequent crews. Although previous research has acknowledged this addition of time buffers, their use in practice has not been studied. This paper reports on what causes people to add and size time buffers. A nationwide survey was administered to project managers, superintendents, and foremen to identify the most frequent and severe reasons for adding time buffers to construction task durations. Forty-seven buffer factors were grouped into nine categories: project characteristics, prerequisite work, detailed design/working method, labor force, tools and equipment, material and components, work/jobsite conditions, management/supervision/information flow, and weather. Contributions to the body of knowledge include (1) identifying the 12 most frequent and severe causes of time buffer; (2) analyzing (understanding) how buffers are viewed differently by foremen, superintendents, and project managers, between trades and between general contractors and subcontractors, and the perception among different levels of experience; and (3) investigating how companies that do not regularly use the Last Planner System and those that do view those factors differently. Additionally, the research quantitatively developed risk profiles of the buffer factors through an integrated risk assessment approach. Understanding the application of time buffers and their associated frequency and severity will help construction managers address potential problem areas and inefficiencies in a prioritized manner. DA - 2013/10// PY - 2013/10// DO - 10.1061/(asce)co.1943-7862.0000735 VL - 139 IS - 10 SP - 04013008 J2 - J. Constr. Eng. Manage. LA - en OP - SN - 0733-9364 1943-7862 UR - http://dx.doi.org/10.1061/(asce)co.1943-7862.0000735 DB - Crossref KW - Construction KW - Time KW - Buffer KW - Uncertainty KW - Labor and personnel issues ER - TY - JOUR TI - An agent-based modeling framework for sociotechnical simulation of water distribution contamination events AU - Shafiee, M. Ehsan AU - Zechman, Emily M. T2 - Journal of Hydroinformatics AB - In the event that a contaminant is introduced to a water distribution network, a large population of consumers may risk exposure. Selecting mitigation actions to protect public health may be difficult, as contamination is a poorly predictable dynamic event. Consumers who become aware of an event may select protective actions to change their water demands from typical demand patterns, and new hydraulic conditions can arise that differ from conditions that would be predicted when demands are considered as exogenous inputs. Consequently, the movement of the contaminant plume in the pipe network may shift from its expected trajectory. A sociotechnical model is developed here to integrate agent-based models of consumers with an engineering water distribution system model and capture the dynamics between consumer behaviors and the water distribution system for predicting contaminant transport and public exposure. Consumers are simulated as agents with behaviors, including movement, water consumption, exposure, reduction in demands, and communication with other agents. As consumers decrease their water use, the location of the contaminant plume is updated and the amount of contaminant consumed by each agent is calculated. The framework is tested through simulating realistic contamination scenarios for a virtual city and water distribution system. DA - 2013/7// PY - 2013/7// DO - 10.2166/hydro.2013.158 VL - 15 IS - 3 SP - 862-880 J2 - J Hydroinform LA - en OP - SN - 1464-7141 1465-1734 UR - http://dx.doi.org/10.2166/hydro.2013.158 DB - Crossref KW - agent-based modeling KW - sociotechnical system KW - threat management KW - water distribution system ER - TY - JOUR TI - Access, accommodation, and science: Knowledge in an "open" world AU - Kelly, Ashley Rose AU - Kittle-Autry, Meagan T2 - First Monday AB - The rising popularity of open access (OA) publishing in scholarly communities is purportedly leading to increased public knowledge. At least, that’s a key piece of the OA moral argument. This is especially true for discussions of scientific research. We argue, however, that while there have been significant moves to provide better material/technological access to research, OA advocates must still tackle the issue of making original scientific research conceptually accessible. Despite being freely available on the Internet, articles are not also by default linguistically, conceptually, or ideologically accessible to the global public(s) they are intended to reach. In this article, we examine how OA coupled with innovative scientific communication practices can help align the ideals of OA with the realities of complex, specialized genres of writing to provide better, more “open,” access to research. We look to PLOS ONE and the PLOS Blog Network to discuss how the innovative material access of PLOS ONE coupled with the communication strategies of PLOS Bloggers can work together toward more openly accessible original scientific research articles. DA - 2013/// PY - 2013/// DO - 10.5210/fm.v18i6.4341 VL - 18 IS - 6 ER - TY - JOUR TI - Viscoelastoplastic modeling of the behavior of hot mix asphalt in compression AU - Yun, Taeyoung AU - Kim, Y. Richard T2 - KSCE JOURNAL OF CIVIL ENGINEERING DA - 2013/9// PY - 2013/9// DO - 10.1007/s12205-013-0352-7 VL - 17 IS - 6 SP - 1323-1332 SN - 1976-3808 KW - rutting KW - compression KW - viscoelasticity KW - viscoplasticity KW - microcracking KW - aggregate interlocking KW - VEPCD ER - TY - JOUR TI - Trip Generation Models Using Cumulative Logistic Regression AU - Huntsinger, Leta F. AU - Rouphail, Nagui M. AU - Bloomfield, Peter T2 - JOURNAL OF URBAN PLANNING AND DEVELOPMENT AB - This paper evaluates the usefulness of the cumulative logistic regression model for estimating trip generation. The cumulative logistic regression model is a type of discrete choice model that estimates relationships between an ordered dependent variable, for example, person trip generation, and a set of independent variables, for example, household size, income, and workers. In addition to testing the model form, life cycle, area type, and accessibility variables are evaluated along with a set of widely used explanatory variables. A secondary focus of this paper is on the issue of temporal stability. Temporal stability is concerned with how models developed during one period of time transfer to a future period. The evaluation includes models based on widely used explanatory variables in addition to models supplemented with life cycle, area type, and accessibility variables to evaluate whether these variables result in improved stability. Analysis includes models estimated using 1995 survey data, applied using 2006 socioeconomic data, and evaluated against 2006 observed data. The results of this analysis show that cumulative logistic regression models are good candidate models for estimating trip generation and for improving the temporal stability of the model results. With respect to life cycle, area type, and accessibility, this research shows that there is benefit in including these variables to help explain trip making and to improve temporal stability. DA - 2013/9/1/ PY - 2013/9/1/ DO - 10.1061/(asce)up.1943-5444.0000151 VL - 139 IS - 3 SP - 176-184 SN - 0733-9488 KW - Transportation models KW - Travel demand KW - Forecasting KW - Logistics KW - Transportation models KW - Trip generation KW - Travel demand KW - Trip forecasting KW - Data analysis KW - Planning ER - TY - JOUR TI - On Event Detection and Localization in Acyclic Flow Networks AU - Suresh, Mahima Agumbe AU - Stoleru, Radu AU - Zechman, Emily M. AU - Shihada, Basem T2 - IEEE Transactions on Systems, Man, and Cybernetics: Systems AB - Acyclic flow networks, present in many infrastructures of national importance (e.g., oil and gas and water distribution systems), have been attracting immense research interest. Existing solutions for detecting and locating attacks against these infrastructures have been proven costly and imprecise, particularly when dealing with large-scale distribution systems. In this article, to the best of our knowledge, for the first time, we investigate how mobile sensor networks can be used for optimal event detection and localization in acyclic flow networks. We propose the idea of using sensors that move along the edges of the network and detect events (i.e., attacks). To localize the events, sensors detect proximity to beacons, which are devices with known placement in the network. We formulate the problem of minimizing the cost of monitoring infrastructure (i.e., minimizing the number of sensors and beacons deployed) in a predetermined zone of interest, while ensuring a degree of coverage by sensors and a required accuracy in locating events using beacons. We propose algorithms for solving the aforementioned problem and demonstrate their effectiveness with results obtained from a realistic flow network simulator. DA - 2013/5// PY - 2013/5// DO - 10.1109/tsmca.2012.2210411 VL - 43 IS - 3 SP - 708-723 J2 - IEEE Trans. Syst. Man Cybern, Syst. OP - SN - 2168-2216 2168-2232 UR - http://dx.doi.org/10.1109/tsmca.2012.2210411 DB - Crossref KW - Computer simulation KW - event detection KW - heuristic algorithms KW - optimization KW - wireless sensor networks ER - TY - JOUR TI - Role of climate forecasts and initial conditions in developing streamflow and soil moisture forecasts in a rainfall-runoff regime AU - Sinha, T. AU - Arumugam, S. T2 - Hydrology and Earth System Sciences DA - 2013/// PY - 2013/// VL - 17 SP - 721-733 ER - TY - JOUR TI - Experimental Optimization of Microbial-Induced Carbonate Precipitation for Soil Improvement AU - Martinez, B. C. AU - DeJong, J. T. AU - Ginn, T. R. AU - Montoya, B. M. AU - Barkouki, T. H. AU - Hunt, C. AU - Tanyu, B. AU - Major, D. T2 - JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING AB - Implementation of laboratory-tested biomediated soil improvement techniques in the field depends on upscaling the primary processes and controlling their rates. Microbial-induced carbonate precipitation (MICP) holds the potential for increasing the shear stiffness and reducing the hydraulic conductivity by harnessing a natural microbiological process that precipitates calcium carbonate. The study presented herein focuses on controlling MICP treatment of one-dimensional flow, half-meter-scale column experiments. Treatment was optimized by varying procedural parameters in five pairs of experiments including flow rates, flow direction, and formulations of biological and chemical amendments. Monitoring of column experiments included spatial and temporal measurements of the physical, chemical, and biological properties essential to the performance of MICP, including shear wave velocity, permeability, calcium carbonate content, aqueous calcium, aqueous ammonium, aqueous urea, and bacterial density. Relatively uniform improvement of a half-meter one-dimensional flow sand column experiment resulted in a change from a shear wave velocity of 140 m/s to an average of 600 m/s. Examination of data sets provides insight into which parameters have a first-order effect of MICP treatment uniformity and efficiency and how these parameters can be monitored and controlled. DA - 2013/4// PY - 2013/4// DO - 10.1061/(asce)gt.1943-5606.0000787 VL - 139 IS - 4 SP - 587-598 SN - 1943-5606 KW - Biomediated soil improvement KW - Microbially induced calcite precipitation KW - Ground improvement KW - Biosoils KW - Ureolytic KW - Ureolysis KW - Geophysics ER - TY - JOUR TI - Using observed data to improve estimated methane collection from select US landfills AU - Wang, X. M. AU - Nagpure, A. S. AU - DeCarolis, J. F. AU - Barlaz, Morton T2 - Environmental Science & Technology AB - The anaerobic decomposition of solid waste in a landfill produces methane, a potent greenhouse gas, and if recovered, a valuable energy commodity. Methane generation from U.S. landfills is usually estimated using the U.S. EPA's Landfill Gas Emissions Model (LandGEM). Default values for the two key parameters within LandGEM, the first-order decay rate (k) and the methane production potential (L0) are based on data collected in the 1990s. In this study, observed methane collection data from 11 U.S. landfills and estimates of gas collection efficiencies developed from site-specific gas well installation data were included in a reformulated LandGEM equation. Formal search techniques were employed to optimize k for each landfill to find the minimum sum of squared errors (SSE) between the LandGEM prediction and the observed collection data. Across nearly all landfills, the optimal k was found to be higher than the default AP-42 of 0.04 yr(-1) and the weighted average decay for the 11 landfills was 0.09 - 0.12 yr(-1). The results suggest that the default k value assumed in LandGEM is likely too low, which implies that more methane is produced in the early years following waste burial when gas collection efficiencies tend to be lower. DA - 2013/// PY - 2013/// DO - 10.1021/es304565m VL - 47 IS - 7 SP - 3251–3257 ER - TY - JOUR TI - Simulation-Optimization Approach to Design Low Impact Development for Managing Peak Flow Alterations in Urbanizing Watersheds AU - Damodaram, Chandana AU - Zechman, Emily M. T2 - Journal of Water Resources Planning and Management AB - The process of urbanization transforms natural landscape into impervious land cover, affecting the ecosystem health of receiving water bodies and downstream communities by changing the timing and volumes of the natural flow regime. Best management practices (BMP) and low impact development (LID) are a set of mitigating measures that can be considered for watershed management to mitigate the hydrologic consequences of urbanization. This research develops a methodology to select sites for placing LID technologies, namely rainwater harvesting and permeable pavements, to reduce hydrologic impacts, measured as alterations to the peak flow while meeting a prespecified budget. A simulation-optimization methodology couples a genetic algorithm with a hydrologic model, a hydraulic model, and curve number-based models of LID technologies. The trade-off between costs and peak flow alteration is explored by optimizing LID placement under varying budget constraints. Strategies that combine a detention pond and LID are explored and optimized for a spectrum of design storms, including 2-, 10-, and 100-year events. Trade-offs among management strategies that are designed to control storms of different sizes are analyzed. The simulation-optimization framework and methodology is applied for a small watershed on the Texas A&M University campus. DA - 2013/5// PY - 2013/5// DO - 10.1061/(asce)wr.1943-5452.0000251 VL - 139 IS - 3 SP - 290-298 J2 - J. Water Resour. Plann. Manage. LA - en OP - SN - 0733-9496 1943-5452 UR - http://dx.doi.org/10.1061/(asce)wr.1943-5452.0000251 DB - Crossref KW - Watershed management KW - Best management practices KW - Low impact development KW - Peak flow KW - Hydrologic modeling KW - Genetic algorithm ER - TY - JOUR TI - Seismic fragility evaluation of multi-branch piping systems installed in critical low-rise buildings AU - Ju, B. AU - Jung, W. T2 - Disaster Advances DA - 2013/// PY - 2013/// VL - 6 IS - 4 SP - 59-65 ER - TY - JOUR TI - Monolignol Pathway 4-Coumaric Acid: Coenzyme A Ligases in Populus trichocarpa: Novel Specificity, Metabolic Regulation, and Simulation of Coenzyme A Ligation Fluxes AU - Chen, Hsi-Chuan AU - Song, Jina AU - Williams, Cranos M. AU - Shuford, Christopher M. AU - Liu, Jie AU - Wang, Jack P. AU - Li, Quanzi AU - Shi, Rui AU - Gokce, Emine AU - Ducoste, Joel AU - Muddiman, David C. AU - Sederoff, Ronald R. AU - Chiang, Vincent L. T2 - PLANT PHYSIOLOGY AB - 4-Coumaric acid:coenzyme A ligase (4CL) is involved in monolignol biosynthesis for lignification in plant cell walls. It ligates coenzyme A (CoA) with hydroxycinnamic acids, such as 4-coumaric and caffeic acids, into hydroxycinnamoyl-CoA thioesters. The ligation ensures the activated state of the acid for reduction into monolignols. In Populus spp., it has long been thought that one monolignol-specific 4CL is involved. Here, we present evidence of two monolignol 4CLs, Ptr4CL3 and Ptr4CL5, in Populus trichocarpa. Ptr4CL3 is the ortholog of the monolignol 4CL reported for many other species. Ptr4CL5 is novel. The two Ptr4CLs exhibited distinct Michaelis-Menten kinetic properties. Inhibition kinetics demonstrated that hydroxycinnamic acid substrates are also inhibitors of 4CL and suggested that Ptr4CL5 is an allosteric enzyme. Experimentally validated flux simulation, incorporating reaction/inhibition kinetics, suggested two CoA ligation paths in vivo: one through 4-coumaric acid and the other through caffeic acid. We previously showed that a membrane protein complex mediated the 3-hydroxylation of 4-coumaric acid to caffeic acid. The demonstration here of two ligation paths requiring these acids supports this 3-hydroxylation function. Ptr4CL3 regulates both CoA ligation paths with similar efficiencies, whereas Ptr4CL5 regulates primarily the caffeic acid path. Both paths can be inhibited by caffeic acid. The Ptr4CL5-catalyzed caffeic acid metabolism, therefore, may also act to mitigate the inhibition by caffeic acid to maintain a proper ligation flux. A high level of caffeic acid was detected in stem-differentiating xylem of P. trichocarpa. Our results suggest that Ptr4CL5 and caffeic acid coordinately modulate the CoA ligation flux for monolignol biosynthesis. DA - 2013/3// PY - 2013/3// DO - 10.1104/pp.112.210971 VL - 161 IS - 3 SP - 1501-1516 SN - 0032-0889 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84874626790&partnerID=MN8TOARS ER - TY - JOUR TI - Lane Choice Model for Signalized Intersections with an Auxiliary Through Lane AU - Bugg, Zachary AU - Rouphail, Nagui M. AU - Schroeder, Bastian T2 - JOURNAL OF TRANSPORTATION ENGINEERING AB - An auxiliary through lane (ATL) is a commonly used congestion relief measure at signalized intersections in which fiscal and right-of-way constraints do not allow for full widening between intersections. Previously developed models have predicted the flow in the ATL as a function of macroscopic elements, such as through-movement demand and the ratio of average green time to cycle length. However, these models explain neither driver behavior nor motivation to use the ATL, nor can such an approach be used in microscopic simulation models. This paper presents empirically developed models for driver lane choice at signalized intersection approaches with one ATL and one continuous through lane (CTL). These models were developed from a calibration data set that covers eight ATL approaches in three U.S. states, for a total of 12 h of observation. The results suggest that the utility of the ATL is a function of each through-movement driver’s arrival time (during either the effective red or green phase), and the queue lengths in either lane at the time of arrival. After calibration, the models were evaluated by applying them to data from a validation site from outside the calibration data set. The paper concludes with a discussion of how the models should be implemented within the lane-change algorithms of microsimulation systems. DA - 2013/4// PY - 2013/4// DO - 10.1061/(asce)te.1943-5436.0000513 VL - 139 IS - 4 SP - 371-378 SN - 1943-5436 KW - Auxiliary through lane KW - Operations KW - Intersection design KW - Discrete choice model KW - Microsimulation KW - Lane choice algorithm ER - TY - JOUR TI - Finding All-Pairs Shortest Path for a Large-Scale Transportation Network Using Parallel Floyd-Warshall and Parallel Dijkstra Algorithms AU - Pradhan, Anu AU - Mahinthakumar, G. T2 - JOURNAL OF COMPUTING IN CIVIL ENGINEERING AB - Parallel computing has become a powerful approach for solving real-time decisions about large-scale, computing-intensive transportation problems. A frequently encountered transportation problem is the “shortest path problem;” that is, finding the shortest path between any two nodes in a transportation network. For the large transportation networks encountered in major metropolitan areas, this problem can be computationally demanding, especially if shortest paths between all the nodes in the network need to be dynamically updated (e.g., evolving traffic conditions). In such a situation, one may wish to harness parallel computing to solve this problem. However, the parallel implementations of commonly used shortest-path algorithms are computationally demanding because of the inherent sequential nature of the search process used by the algorithms. This paper describes parallel implementations and includes performance analyses of two prominent graph algorithms (i.e., Floyd-Warshall and Dijkstra) used for finding the all-pairs shortest path for a large-scale transportation network. The results indicate that a multilevel parallel implementation that combines message passing interface (MPI) with shared memory threads [e.g., Open Multiprocessing (OpenMP) or POSIX Threads (pthreads)] is effective for solving these problems on a moderate number of symmetric multiprocessor (SMP) nodes. This paper also includes the derivation of the computational time for the different parallel implementations of these two graph algorithms. DA - 2013/// PY - 2013/// DO - 10.1061/(asce)cp.1943-5487.0000220 VL - 27 IS - 3 SP - 263-273 SN - 1943-5487 KW - Parallel computing KW - Graph algorithm KW - Transportation KW - Computing ER - TY - JOUR TI - Equine Viral Respiratory Pathogen Surveillance at Horse Shows and Sales AU - Carlson, Jennifer K. AU - Traub-Dargatz, Josie L. AU - Lunn, D. Paul AU - Morley, Paul S. AU - Kohler, Andi AU - Kasper, Katheryne AU - Landolt, Gabriele A. AU - Barnett, D. Craig AU - Lunn, Katharine F. T2 - JOURNAL OF EQUINE VETERINARY SCIENCE AB - Equine respiratory viral infections cause significant worldwide disease and economic loss. Common causes include equine influenza virus (EIV) and equine herpesviruses-1 and -4 (EHV-1 and -4), and risk of exposure to these agents may be highest in young horses commingling at sales and competitive events. A surveillance study was conducted at two horse shows and two Thoroughbred sales to determine whether horses shed EHV-1, EHV-4, or EIV on arrival, or 2-4 days later, and whether shedding was associated with identifiable risk factors. Real-time polymerase chain reaction assays were used to detect EHV-1, EHV-4, and EIV nucleic acid in nasal swabs obtained from 369 horses at the four events. In response to evidence of clinical disease, 82 additional horses were sampled at two farms providing horses for one of the sales. On arrival at the events, shedding of EHV-1 was detected in 3.3%, EHV-4 in 1.1%, and EIV in 0.8% of horses. EHV-1 was detected at low levels, and EHV-1 and EHV-4 detection was not associated with clinical disease. EIV was detected only in horses at a Thoroughbred sale, in association with an outbreak of respiratory disease traced back to regional farms. On arrival at events, horses younger than 2 years had a significantly greater risk of shedding EHV-1 compared with older horses; no other significant risk factors associated with viral shedding were identified. Thus, there is a risk of exposure to EIV, EHV-1, and EHV-4 at equine events, and horses and events should be managed to mitigate this risk. DA - 2013/4// PY - 2013/4// DO - 10.1016/j.jevs.2012.06.006 VL - 33 IS - 4 SP - 229-237 SN - 0737-0806 KW - Horse respiratory viruses KW - Equine herpesvirus-1 KW - Equine herpesvirus-4 KW - Equine influenza virus ER - TY - JOUR TI - Driver distraction and performance effects of highway logo sign design AU - Zhang, Yu AU - Harris, Elizabeth AU - Rogers, Meghan AU - Kaber, David AU - Hummer, Joseph AU - Rasdorf, William AU - Hu, Jia T2 - APPLIED ERGONOMICS AB - Driver distraction and safety concerns have been identified for new highway logo sign configurations. This study assessed driver perception of logo signs and distraction under nine-panel, overflow-combination, or standard six-panel formats. A nine-panel sign has nine business panels within a single sign; a six-panel sign has six panels within a sign; an overflow-combination consists of a standard six-panel sign and a six-panel sign displaying two different services (e.g., food and gas). In this study, twenty-four participants searched for target food business logos while driving in a high-fidelity driving simulation under each signage condition. Gas and lodging signs were also displayed along the road in conventional six-panel formats. Dependent variables included signal detection, visual attention allocation, and vehicle control measures. Experiment results showed nine-panel signs drew greater visual attention and produced lower average speed than overflow-combination signs, and produced a lower speeding percentage compared to six-panel signs. However, there was no evidence the new configurations (nine-panel and overflow) caused substantive performance changes with safety implications. This study suggested the use of nine-panel and overflow-combination logo signs may be suitable for interchanges where there are more than six qualifying businesses in a category in terms of driver performance and safety. DA - 2013/5// PY - 2013/5// DO - 10.1016/j.apergo.2012.10.009 VL - 44 IS - 3 SP - 472-479 SN - 1872-9126 KW - Roadway logo signs KW - Driving simulation KW - Driver performance KW - Driver distraction KW - Highway safety ER - TY - JOUR TI - Collecting Horizontal Curve Data: Mobile Asset Vehicles and Other Techniques AU - Findley, Daniel J. AU - Hummer, Joseph E. AU - Rasdorf, William AU - Laton, Brian T. T2 - JOURNAL OF INFRASTRUCTURE SYSTEMS AB - Mobile asset data collection vehicles can provide transportation agencies with inventories of various roadway and roadside elements containing location information, element type, and condition data. Horizontal curves are of interest to agencies because they have been shown to be hazardous roadway components and have potential for mobile data collection concurrently with other roadway elements. The cost of manually acquiring horizontal curvature data to develop an inventory can be prohibitive for many agencies, so understanding the applicability of a mobile asset data collection effort for curves is important. The objective of this work was to study the ability of multiple commercial roadway inventory vehicles and to compare them to other methods for determining the geometric characteristics of horizontal curves. The comparison is based on data from three commercial vendors of roadway asset inventory data on a 38.8-km (24.1-mi) course in central North Carolina. Among the 16 curves studied, at least one vendor was within 10% of the radius value found with the manual chord method for six of the curves and within 25% for 13 of the curves. Only three curves had a larger radius variant. For the length measurements of the 16 curves, at least one vendor was within 10% of the length from the chord method for eleven of the curves and within 25% for fifteen of the curves. Only one curve had a larger length variant. The mobile vehicle vendors provided more accurate and consistent curve length measurements than radius measurements. Agencies that consider using mobile data collection vehicles for horizontal alignments should understand the limitations of each horizontal curve estimating technique and the changes that can occur in the radius within the curve. Collaborating with vendors to define the changes in roadway alignment that constitute a curve, the associated beginning and ending of the curve, and geometric characteristics can provide agencies the most appropriate data to meet their needs. DA - 2013/3// PY - 2013/3// DO - 10.1061/(asce)is.1943-555x.0000107 VL - 19 IS - 1 SP - 74-84 SN - 1076-0342 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000316563500008&KeyUID=WOS:000316563500008 KW - Transportation engineering KW - Highways and roads KW - Curvature KW - Alignment KW - Infrastructure KW - Geographic information systems KW - Data collection KW - Civil engineering KW - Transportation engineering KW - Road curvature KW - Alignment KW - Infrastructure KW - Geographic information systems KW - Inventories KW - Length KW - Horizontal curve KW - Radius ER - TY - JOUR TI - Assessment of In Situ Scour Profile in Sand Using a Jet Probe AU - Gabr, Mo AU - Caruso, Cary AU - Key, Austin AU - Kayser, Mohammad T2 - Geotechnical Testing Journal AB - Abstract Work in this paper presents a device and a process for in situ assessment of erosion potential with depth. The proposed device is termed “in situ erosion evaluation probe” (ISEEP), and the process is developed based upon advancing a rod fitted with a truncated cone jet nozzle into the soil. As water exits the nozzle with controllable velocity and flow rate (induced by an external pump) the probe advances into the subsurface profile and the rate of advancement is measured. The jet flow velocity and the advancement rate of the probe are correlated with a stream power value, and used to estimate soil erodibility parameters. Results from laboratory testing show the feasibility of the concept. An approach for the estimation of a critical stream power and a detachment rate coefficient is presented. Numerical modeling and deployment of the device at a North Carolina barrier island site after hurricane Irene are used to demonstrate the applicability of the proposed concept. Correlations between scour magnitudes, estimated by ISEEP parameters, and those estimated through modeling and field observation are presented and illustrate the viability of ISEEP’s soil erosion parameters as defined by a critical stream power and a detachment rate coefficient. DA - 2013/1// PY - 2013/1// DO - 10.1520/gtj20120046 VL - 36 IS - 2 SP - 20120046 J2 - Geotech. Test. J. LA - en OP - SN - 0149-6115 UR - http://dx.doi.org/10.1520/GTJ20120046 DB - Crossref KW - sand KW - erosion KW - shear stress ER - TY - JOUR TI - Removal of highly polar micropollutants from wastewater by powdered activated carbon AU - Kovalova, Lubomira AU - Knappe, Detlef R. U. AU - Lehnberg, Kai AU - Kazner, Christian AU - Hollender, Juliane T2 - ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH AB - Due to concerns about ecotoxicological effects of pharmaceuticals and other micropollutants released from wastewater treatment plants, activated carbon adsorption is one of the few processes to effectively reduce the concentrations of micropollutants in wastewater. Although aimed mainly at apolar compounds, polar compounds are also simultaneously removed to a certain extent, which has rarely been studied before. In this study, adsorption isotherm and batch kinetic data were collected with two powdered activated carbons (PACs) to assess the removal of the polar pharmaceuticals 5-fluorouracil (5-Fu) and cytarabine (CytR) from ultrapure water and wastewater treatment plant effluent. At pH 7.8, single-solute adsorption isotherm data for the weak acid 5-Fu and the weak base CytR showed that their adsorption capacities were about 1 order of magnitude lower than those of the less polar endocrine disrupting chemicals bisphenol A (BPA) and 17-α-ethinylestradiol (EE2). To remove 90 % of the adsorbate from a single-solute solution 14, 18, 70, and 87 mg L−1 of HOK Super is required for EE2, BPA, CytR, and 5-Fu, respectively. Effects of solution pH, ionic strength, temperature, and effluent organic matter (EfOM) on 5-Fu and CytR adsorption were evaluated for one PAC. Among the studied factors, the presence of EfOM had the highest effect, due to a strong competition on 5-Fu and CytR adsorption. Adsorption isotherm and kinetic data and their modeling with a homogeneous surface diffusion model showed that removal percentage in the presence of EfOM was independent on the initial concentration of the ionizable compounds 5-Fu and CytR. These results are similar to neutral organic compounds in the presence of natural organic matter. Overall, results showed that PAC doses sufficient to remove >90 % of apolar adsorbates were able to remove no more than 50 % of the polar adsorbates 5-Fu and CytR and that the contact time is a critical parameter. DA - 2013/6// PY - 2013/6// DO - 10.1007/s11356-012-1432-9 VL - 20 IS - 6 SP - 3607-3615 SN - 0944-1344 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84878111191&partnerID=MN8TOARS KW - Adsorption KW - Powdered activated carbon KW - Wastewater treatment KW - Polar compound KW - Trace organic compound KW - Micropollutant KW - Pharmaceuticals KW - Cytostatic ER - TY - JOUR TI - Preliminary Engineering Cost-Estimation Strategy Assessment for Roadway Projects AU - Liu, Min AU - Rasdorf, William AU - Hummer, Joseph E. AU - Hollar, Donna A. AU - Parikh, Shalin C. T2 - Journal of Management in Engineering AB - Preliminary engineering (PE) for a roadway project encompasses two efforts: planning to minimize the physical, social, and human environmental impacts of projects and engineering design to deliver the best alternative. State transportation agencies strive to manage these efforts efficiently, seeking to maximize the utilization of limited funding and workforce productivity. Managers need a feasible PE budget, considering both cost and time, early in project development. The results reported herein will provide engineers and managers with a comparative investigation evaluating different strategies for establishing a PE budget during the preconstruction phase of roadway project development. Cost data were obtained for 188 North Carolina roadway projects built between 1999 and 2009. An analysis of the North Carolina DOT data yielded an overall mean ratio of PE cost to estimated construction cost (the PE cost ratio) of 11.7%. The multiple linear regression model was used to develop prediction models to forecast the PE cost ratio of future roadway projects. It was found that while differing regression strategies could reduce prediction error, the improvement was small. In terms of simplicity, using the historical means applicable for widening projects (13.3%), rehabilitation/resurfacing projects (7.7%), and new location/interchange projects (16.5%) proved advantageous over regression modeling because a project manager would not have to estimate any project-specific values at the earliest stages of project development. The lowest of these historical means was significantly different than the two higher means (7.7% versus 13.3% and 16.5%); however, the difference between the two higher means (13.3% versus 16.5%) was not statistically significant. The study analyses also found a significant correlation between a project’s PE cost ratio and its PE duration, suggesting that further investigation into PE duration of transportation projects is warranted. DA - 2013/4// PY - 2013/4// DO - 10.1061/(asce)me.1943-5479.0000137 VL - 29 IS - 2 SP - 150-157 J2 - J. Manage. Eng. LA - en OP - SN - 0742-597X 1943-5479 UR - http://dx.doi.org/10.1061/(asce)me.1943-5479.0000137 DB - Crossref KW - Preliminary engineering KW - Preconstruction costs KW - Cost estimation KW - Regression KW - Roadway cost KW - Duration ER - TY - JOUR TI - Integration of Climate and Weather Information for Improving 15-Day-Ahead Accumulated Precipitation Forecasts AU - Wang, Hui AU - Sankarasubramanian, A. AU - Ranjithan, Ranji S. T2 - JOURNAL OF HYDROMETEOROLOGY AB - Abstract Skillful medium-range weather forecasts are critical for water resources planning and management. This study aims to improve 15-day-ahead accumulated precipitation forecasts by combining biweekly weather and disaggregated climate forecasts. A combination scheme is developed to combine reforecasts from a numerical weather model and disaggregated climate forecasts from ECHAM4.5 for developing 15-day-ahead precipitation forecasts. Evaluation of the skill of the weather–climate information (WCI)-based biweekly forecasts under leave-five-out cross validation shows that WCI-based forecasts perform better than reforecasts in many grid points over the continental United States. Correlation between rank probability skill score (RPSS) and disaggregated ECHAM4.5 forecast errors reveals that the lower the error in the disaggregated forecasts, the better the performance of WCI forecasts. Weights analysis from the combination scheme also shows that the biweekly WCI forecasts perform better by assigning higher weights to the better-performing candidate forecasts (reforecasts or disaggregated ECHAM4.5 forecasts). Particularly, WCI forecasts perform better during the summer months during which reforecasts have limited skill. Even though the disaggregated climate forecasts do not perform well over many grid points, the primary reason WCI-based forecasts perform better than the reforecasts is due to the reduction in the overconfidence of the reforecasts. Since the disaggregated climate forecasts are better dispersed than the reforecasts, combining them with reforecasts results in reduced uncertainty in predicting the 15-day-ahead accumulated precipitation. DA - 2013/2// PY - 2013/2// DO - 10.1175/jhm-d-11-0128.1 VL - 14 IS - 1 SP - 186-202 SN - 1525-7541 ER - TY - JOUR TI - Engine and Duty Cycle Variability in Diesel Construction Equipment Emissions AU - Abolhasani, Saeed AU - Frey, H. Christopher T2 - JOURNAL OF ENVIRONMENTAL ENGINEERING AB - This paper explores methods for analyzing onboard mass emissions data and developing modal models on the basis of case study examples for nine selected nonroad construction vehicles. Data for these vehicles were obtained from the U.S. Environmental Protection Agency (EPA). Several modeling methods were explored, including stratification of the data into operating modes and supplementing the modal models with ordinary least-squares regression and multiple least-squares regression. The modal approach offers the advantages as conceptually the simplest, reducing the influence of autocorrelation in the model and providing substantial explanatory power. The normalized relationship between predicted mode-specific average emissions and exhaust flow is stable, similar, and consistent for all vehicles. For a given engine, the average emission rate can vary by more than a factor of two when comparing highest to lowest rates among different duty cycles. Some engines are common to different types of equipment, such as bulldozers and front-end loaders. For a given type of equipment, such as bulldozers, average NOx and CO2 mass emission rates can vary by more than 50% depending on the duty cycle. Vehicle category-specific modal models are recommended on the basis of onboard second-by-second in-use activity and emissions data and for use in new modeling tools to estimate emissions produced by nonroad construction vehicles. DA - 2013/2// PY - 2013/2// DO - 10.1061/(asce)ee.1943-7870.0000548 VL - 139 IS - 2 SP - 261-268 SN - 1943-7870 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84873375511&partnerID=MN8TOARS KW - Diesel engines KW - Air pollution KW - Emissions KW - Construction equipment KW - Pollutants KW - Fuel use KW - Greenhouse gas ER - TY - JOUR TI - Dynamic response of liquefiable sand improved by microbial-induced calcite precipitation AU - Montoya, B. M. AU - Dejong, J. T. AU - Boulanger, R. W. T2 - GEOTECHNIQUE AB - Microbial-induced calcite precipitation (MICP), a novel bio-mediated ground improvement method, was explored to mitigate liquefaction-prone soils. Geotechnical centrifuge tests were used to evaluate cementation integrity and the response of MICP cemented sands to dynamic loading. The cementation integrity testing reveals a change in behaviour from ‘soil like' to ‘rock like', with an increase in treatment level. Results from dynamic testing demonstrate a clear increase in resistance to liquefaction of MICP-treated sands compared to untreated loose sand. The MICP sands were treated to varying levels of cementation (light, moderate and heavy cementation levels) and assessed using non-destructive shear wave velocity measurements. The centrifuge models were all subjected to ground motions consisting of sine waves with increasing amplitudes. Accelerations, pore pressures and settlements were measured in the soil during shaking, and the changes in soil behaviour and post-shaking shear wave velocity for soils prepared to different cementation levels are discussed. Increased resistance to liquefaction was demonstrated with a decrease in excess pore pressure ratios in the MICP-treated models, as well as in reduced post-shaking settlements; however, surface accelerations were amplified at heavy levels of cementation. A tradeoff between improving liquefaction resistance and minimising undesirable higher surface accelerations needs to be considered when designing the soil improvement level. DA - 2013/3// PY - 2013/3// DO - 10.1680/geot.sip13.p.019 VL - 63 IS - 4 SP - 302-312 SN - 1751-7656 KW - centrifuge modelling KW - dynamics KW - ground improvement KW - liquefaction KW - sands ER - TY - JOUR TI - Cost-Benefit Analysis of Construction Information Management System Implementation: Case Study AU - Vaughan, Joshua L. AU - Leming, Michael L. AU - Liu, Min AU - Jaselskis, Edward T2 - Journal of Construction Engineering and Management AB - In construction projects, construction managers spend a significant portion of their time gathering project data, assessing production rates, communicating with project participants, and tracking project quality. Executing those tasks manually reduces efficiency and can result in less effective project management operations. In order to improve efficiency of information process flow, various types of construction information management systems (CIMSs) have been introduced to construction projects. However, due to the difficulty of tracking fragmental and illusive data, measuring the cost and benefit of the implementation and evaluating the trade-off remain a challenge for construction practitioners. This paper’s contributions to the body of knowledge include (1) proposing a framework to assess tangible and semitangible or intangible costs and benefits of innovative construction technology application, (2) determining costs and benefits of the use of CIMSs by conducting a product-specific case study, and (3) summarizing lessons learned through the application of a CIMS from the first-hand users so that construction managers can avoid pitfalls in other projects. This study provides data collected during real-time immersion in the project as part of the project team over a 6 month period. The study found that the use of CIMSs, coupled with mobile technologies, increased efficiency and decreased clerical time of operations-level construction personnel, and thereby increased value to the project through improved allocation of managerial time. The internal observation and analysis provide a useful guidance to project managers who are interested in implementing CIMS in construction projects. DA - 2013/4// PY - 2013/4// DO - 10.1061/(asce)co.1943-7862.0000611 VL - 139 IS - 4 SP - 445-455 J2 - J. Constr. Eng. Manage. LA - en OP - SN - 0733-9364 1943-7862 UR - http://dx.doi.org/10.1061/(asce)co.1943-7862.0000611 DB - Crossref KW - Technology KW - Information management KW - Construction management KW - Computer software KW - Planning KW - Case studies KW - Benefit cost ratios ER - TY - JOUR TI - Comparative evaluation of a viscoplastic power-law and rate-independent crystal plasticity in channel die compression AU - Havner, Kerry S. T2 - MECHANICS OF MATERIALS AB - General equations in (1 1 0) channel die compression are derived for a viscoplastic power-law, and comparative evaluations made with rate-independent theory and experiment. The latter theory has been shown in a series of papers (2007–2012) to predict well the finite-deformation experimental behavior (1966–2007) of fcc crystals in this family of orientations, and to give a rational basis for the elastoplastic transition that precedes the onset of finite multiple-slip. It is established analytically that, during this elastoplastic transition, the power-law equations in the limit of unbounded exponent n are identical with the rate-independent equations for lateral stress-rate and (very small) lattice rotation-rate. Moreover, results for aluminum and copper agree very closely for large n in four initial orientations investigated numerically. At the onset of finite deformation (in general when four or more systems are equally stressed) the respective results for stress-rate differ sharply, with the exception of the experimentally stable Brass orientation. When lattice elasticity is included in the power-law in this orientation (with an n of 100 or greater), it predicts results essentially indistinguishable from rate-independent theory for both aluminum and copper, in good agreement with experiment. In two orientations near the ends of the range, the power-law lattice rotation-rates at the onset of finite deformation for large n also agree closely with the rate-independent results. However, in the specific orientation from which there is large lattice rotation, the power-law significantly under-predicts rate-independent and experimental results after large strains, whatever the value of exponent n. DA - 2013/4// PY - 2013/4// DO - 10.1016/j.mechmat.2012.09.004 VL - 59 SP - 126-141 SN - 0167-6636 KW - Channel die compression KW - Elastoplastic fcc crystals KW - Rate-independent theory KW - Viscoplastic power-law KW - Finite deformation ER - TY - JOUR TI - Biogeochemical processes and geotechnical applications: progress, opportunities and challenges AU - Dejong, J. T. AU - Soga, K. AU - Kavazanjian, E. AU - Burns, S. E. AU - Van Paassen, L. A. AU - Al Qabany, A. AU - Aydilek, A. AU - Bang, S. S. AU - Burbank, M. AU - Caslake, L. F. AU - Chen, C. Y. AU - Cheng, X. AU - Chu, J. AU - Ciurli, S. AU - Esnault-Filet, A. AU - Fauriel, S. AU - Hamdan, N. AU - Hata, T. AU - Inagaki, Y. AU - Jefferis, S. AU - Kuo, M. AU - Laloui, L. AU - Larrahondo, J. AU - Manning, D. A. C. AU - Martinez, B. AU - Montoya, B. M. AU - Nelson, D. C. AU - Palomino, A. AU - Renforth, P. AU - Santamarina, J. C. AU - Seagren, E. A. AU - Tanyu, B. AU - Tsesarsky, M. AU - Weaver, T. T2 - GEOTECHNIQUE AB - Consideration of soil as a living ecosystem offers the potential for innovative and sustainable solutions to geotechnical problems. This is a new paradigm for many in geotechnical engineering. Realising the potential of this paradigm requires a multidisciplinary approach that embraces biology and geochemistry to develop techniques for beneficial ground modification. This paper assesses the progress, opportunities, and challenges in this emerging field. Biomediated geochemical processes, which consist of a geochemical reaction regulated by subsurface microbiology, currently being explored include mineral precipitation, gas generation, biofilm formation and biopolymer generation. For each of these processes, subsurface microbial processes are employed to create an environment conducive to the desired geochemical reactions among the minerals, organic matter, pore fluids, and gases that constitute soil. Geotechnical applications currently being explored include cementation of sands to enhance bearing capacity and liquefaction resistance, sequestration of carbon, soil erosion control, groundwater flow control, and remediation of soil and groundwater impacted by metals and radionuclides. Challenges in biomediated ground modification include upscaling processes from the laboratory to the field, in situ monitoring of reactions, reaction products and properties, developing integrated biogeochemical and geotechnical models, management of treatment by-products, establishing the durability and longevity/reversibility of the process, and education of engineers and researchers. DA - 2013/3// PY - 2013/3// DO - 10.1680/geot.sip13.p.017 VL - 63 IS - 4 SP - 287-301 SN - 1751-7656 KW - chemical properties KW - environmental engineering KW - ground improvement KW - remediation KW - soil stabilisation ER - TY - JOUR TI - Application of artificial neural networks to predict the bond strength of FRP-to-concrete joints AU - Mashrei, Mohammed A. AU - Seracino, R. AU - Rahman, M. S. T2 - CONSTRUCTION AND BUILDING MATERIALS AB - A Back-Propagation Neural Network (BPNN) model for predicting the bond strength of FRP-to-concrete joints is proposed. Published single-lap shear test specimens were used to predict the bond strength of externally bonded FRP systems adhered to concrete prisms. A database of one hundred and fifty experimental data points from several sources was used for training and testing the BPNN. The data used in the BPNN are arranged in a format of six input parameters including: width of concrete prism; concrete cylinder compressive strength; FRP thickness; bond length; bond width (i.e. FRP width); and FRP modulus of elasticity. The one corresponding output parameter is the bond strength. A parametric study was carried out using BPNN to study the influence of each parameter on the bond strength and to compare results with common existing analytical models. The results of this study indicate that the BPNN provides an efficient alternative method for predicting the bond strength of FRP-to-concrete joints when compared to experimental results and those from existing analytical models. DA - 2013/3// PY - 2013/3// DO - 10.1016/j.conbuildmat.2012.11.109 VL - 40 SP - 812-821 SN - 1879-0526 KW - BPNN KW - FRP KW - Bond strength KW - Concrete ER - TY - JOUR TI - An evolutionary algorithm approach to generate distinct sets of non-dominated solutions for wicked problems AU - Zechman, Emily M. AU - Giacomoni, Marcio H. AU - Shafiee, M. Ehsan T2 - Engineering Applications of Artificial Intelligence AB - Many engineering design problems must optimize multiple objectives. While many objectives are explicit and can be mathematically modeled, some goals are subjective and cannot be included in a mathematical model of the optimization problem. A set of alternative non-dominated fronts that represent multiple optima for problem solution can be identified to provide insight about the decision space and to provide options and alternatives for decision-making. This paper presents a new algorithm, the Multi-objective Niching Co-evolutionary Algorithm (MNCA) that identifies distinct sets of non-dominated solutions which are maximally different in their decision vectors and are located in the same non-inferior regions of a Pareto front. MNCA is demonstrated to identify a set of non-dominated fronts with maximum difference in decision vectors for a set of real-valued problems. DA - 2013/5// PY - 2013/5// DO - 10.1016/j.engappai.2013.03.004 VL - 26 IS - 5-6 SP - 1442-1457 J2 - Engineering Applications of Artificial Intelligence LA - en OP - SN - 0952-1976 UR - http://dx.doi.org/10.1016/j.engappai.2013.03.004 DB - Crossref KW - Evolutionary computation KW - Engineering design KW - Multi-objective optimization KW - Niching KW - Alternative generation ER - TY - JOUR TI - A viscoplastic model for rate-dependent hardening for asphalt concrete in compression AU - Subramanian, Vijay AU - Guddati, Murthy N. AU - Kim, Y. Richard T2 - MECHANICS OF MATERIALS AB - This paper presents a new type of viscoplastic model based on viscoelastic convolution integrals for explaining the behavior of asphalt concrete in compression under repeated loading. Triaxial compression cyclic tests carried out for long rest periods, with different loading times and two different pulse shapes, square and haversine, were used in developing and validating the model. These tests demonstrate that the evolution of permanent deformation depends on load history. This history-dependent behavior is not captured accurately by some of the existing Perzyna-type viscoplastic models in which permanent deformation evolution depends on the current values of stress and viscoplastic strain. Therefore, in this study, viscoelastic-like convolution integrals were used in the model to capture the effect of history. The proposed model is applicable to compressive creep and recovery experiments at 54 °C with (1) several hundreds of cycles of loading including the secondary creep region, (2) haversine loading shapes at three different peak deviatoric stress levels, 620 kPa, 827 kPa, and 1034 kPa, and square loading shapes at 827 kPa peak deviatoric stress, and (3) long rest periods that allow complete viscoelastic recovery. DA - 2013/4// PY - 2013/4// DO - 10.1016/j.mechmat.2012.10.003 VL - 59 SP - 142-159 SN - 1872-7743 KW - Asphalt concrete KW - Viscoplasticity KW - Creep and recovery KW - Viscoelasticity KW - Permanent deformation KW - Compression behavior ER - TY - JOUR TI - Simulation-Based Evaluation of Traffic Sign Retroreflectivity Maintenance Practices AU - Hummer, Joseph E. AU - Harris, Elizabeth A. AU - Rasdorf, William T2 - JOURNAL OF TRANSPORTATION ENGINEERING-ASCE AB - A new highway sign minimum retroreflectivity standard issued by the Federal Highway Administration (FHWA) is compelling agencies to evaluate how to comply while remaining within their budgets. This paper presents the results from a unique microscopic sign system simulation developed to quantitatively evaluate the effectiveness of various sign management practices. The analysis focused on three management methods—nighttime visual inspection, blanket replacement, and expected sign life—and two key sign maintenance functions, sign damage and replacement. The analysis found that sign managers should make prompt replacement of damaged signs a priority. The blanket replacement method was less cost-effective than the nighttime visual inspection method. The expected sign life method was competitive on costs with the visual inspection method while maintaining similar sign conditions. Training inspectors to be more accurate can realize further savings. Skipping inspection or replacement one year, or having an insufficient sign budget, can lead to degraded sign condition levels. The authors offer five best practices that agencies can consider when making sign management decisions. DA - 2013/6// PY - 2013/6// DO - 10.1061/(asce)te.1943-5436.0000526 VL - 139 IS - 6 SP - 556-564 SN - 0733-947X KW - Simulation KW - Traffic signs KW - Retroreflectivity KW - Asset management ER - TY - JOUR TI - Road Grade Measurement Using In-Vehicle, Stand-Alone GPS with Barometric Altimeter AU - Boroujeni, Behdad Yazdani AU - Frey, H. Christopher AU - Sandhu, Gurdas Singh T2 - JOURNAL OF TRANSPORTATION ENGINEERING-ASCE AB - Real-world vehicle fuel use and emission rates are sensitive to road grade. There is a need for a practical method for measuring road grade in combination with on-board measurement of vehicle activity, energy use, and emissions using portable emissions measurement systems (PEMS). This paper focuses on quantification of the accuracy and precision of a low-cost method using a stand-alone global positioning system (GPS) receiver with an in-built barometric altimeter. Approximately 100 one-way runs were made on each of several study routes. The sensitivity of average grade estimates to the averaging distance over which grade is estimated is quantified. The repeatability of vehicle location and distance traveled is quantified. The run-to-run variability and confidence intervals for average estimates of grade are quantified. The accuracy of the grade estimates is evaluated in comparison to LIDAR-based estimates. The low-cost method is shown to be accurate, but imprecision in the measurements leads to a need for typically at least 10 or more repeated runs, depending on the desired precision of the average estimate of grade. DA - 2013/6// PY - 2013/6// DO - 10.1061/(asce)te.1943-5436.0000545 VL - 139 IS - 6 SP - 605-611 SN - 0733-947X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84881240089&partnerID=MN8TOARS KW - Vehicle KW - Emissions KW - Highway KW - Road grade KW - Engine load KW - Speed KW - Acceleration KW - Vertical curvature KW - Distance KW - Global positioning system (GPS) ER - TY - JOUR TI - Performance-Cost Analysis of Stabilized Undercut Subgrades AU - Cote, Benjamin AU - Robinson, Brent AU - Gabr, M. A. AU - Borden, Roy H. T2 - JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT-ASCE AB - An approach for comparatively evaluating the performance cost of undercut subgrade stabilization measures is presented. The performance-cost analysis coupled results from laboratory cyclic load testing with material prices and estimated cost factors for stabilization alternatives. The study utilized data from 22 simulated undercut sections with different stabilization configurations over a soft subgrade with a California bearing ratio of approximately 2.0%. The computed cost factors are normalized with respect to the rut-depth magnitude and subgrade strength. Sections with lime-stabilized subgrade were the most economical with respect to initial and postrut repair cycles. Unreinforced aggregate based course (ABC) sections between 356 and 508 mm (14 and 20 in.) in thickness were economical during initial cycles. Sections with geosynthetic reinforcement showed that once enough rut depth is induced to mobilize the strength of the reinforcement, economical performance was comparable with other stabilization measures excluding lime-stabilized subgrade. When the ABC layer was thicker [between 457 and 508 mm (18 and 20 in.)], differences in the reinforcement type were less significant. Tests with 914 mm (36 in.) select fill overlaid by 76 mm (3 in.) ABC stabilization exhibited a high unit cost but were moderately economical. This study shows the advantage of including performance aspects, such as rut depth and subgrade strength, when considering the overall cost of stabilization. DA - 2013/2// PY - 2013/2// DO - 10.1061/(asce)co.1943-7862.0000572 VL - 139 IS - 2 SP - 121-127 SN - 0733-9364 KW - Construction KW - Cost KW - Cyclic KW - Geosynthetics KW - Lime KW - Rutting KW - Soil KW - Stabilization KW - Strength KW - Subgrade ER - TY - JOUR TI - Nanoscale mechanical properties of concrete containing blast furnace slag and fly ash before and after thermal damage AU - Zadeh, V. Z. AU - Bobko, C. P. T2 - Cement & Concrete Composites AB - Portland cement blended with waste products such as blast furnace slag and fly ash are frequently used to create more sustainable concrete, but their nanoscale mechanical behavior, particularly after thermal damage, has not been well-studied. Here, nanoindentation experiments confirm that concrete produced with blended cements contains hydration products with nearly identical nanoscale mechanical properties to the hydration products found in concretes produced with ordinary Portland cement. The volume fractions of the hydration products, particularly calcium-silicate-hydrate (C-S-H) phases, are formed in different proportions with the addition of fly ash and blast furnace slag. After exposure to fire damage, the nanoscale behavior of concretes produced with fly ash and slag also matches the nanoscale behavior of conventional concretes. This suggests that any macroscopic differences between fire damage behavior of blended cement concrete and ordinary Portland cement concrete must have origins in a larger length scale. DA - 2013/// PY - 2013/// DO - 10.1016/j.cemconcomp.2012.09.003 VL - 37 SP - 215-221 ER - TY - JOUR TI - Multiphase Extraction of Light Non-aqueous Phase Liquid (LNAPL) Using Prefabricated Vertical Wells AU - Gabr, M. AU - Sharmin, N. AU - Quaranta, J. T2 - GEOTECHNICAL AND GEOLOGICAL ENGINEERING DA - 2013/2// PY - 2013/2// DO - 10.1007/s10706-012-9567-5 VL - 31 IS - 1 SP - 103-118 SN - 1573-1529 KW - Groundwater KW - Light non-aqueous phase KW - liquid (LNAPL) KW - Multiphase contaminant transport KW - Low permeability KW - Model KW - Remediation technique KW - Soil ER - TY - JOUR TI - Drift, strain limits and ductility demands for RC moment frames designed with displacement-based and force-based design methods AU - Vidot-Vega, Aidcer L. AU - Kowalsky, Mervyn J. T2 - ENGINEERING STRUCTURES AB - This paper presents the results of the non-linear time history analysis of six different reinforced concrete moment frames. The frames were designed using direct displacement-based design (DDBD) and traditional force-based design methods. Frames of 4–12 storeys tall and with two and three bays were studied. The interstorey drifts, displacements, and material strains obtained from the analyses of the frames designed using both design methods are compared. The implications of code implied ductility and allowable drifts were also studied. Target steel tensile strains and interstorey drifts for the frames designed using DDBD correlated well with the values obtained from the analyses. DA - 2013/6// PY - 2013/6// DO - 10.1016/j.engstruct.2013.01.004 VL - 51 SP - 128-140 SN - 0141-0296 KW - Displacement-based design KW - Drifts KW - Reinforced concrete frames KW - Force-based design KW - Material strains KW - Ductility ER - TY - JOUR TI - Displacement-Based Seismic Design of Bridges AU - Calvi, Gian Michele AU - Priestley, Michael John Nigel AU - Kowalsky, Mervyn J. T2 - STRUCTURAL ENGINEERING INTERNATIONAL AB - This paper provides a summary of the displacement-based seismic design method as applied to bridge structures. A brief introduction is devoted to the shortcomings of traditional force-based design methods, followed by a discussion of the seismic input for displacement-based design and by the fundamentals of the method.The essential objective of the approach is to provide a design methodology that engineers can employ to accomplish the goals of performance-based earthquake engineering (PBEE), the primary objective of which is to design a structure in order to achieve predictable levels of performance under defined levels of seismic input, within definable levels of reliability, as stated by SEAC in 1999.It is thus essential that the design procedures used are capable of controlling structural performance. Such a requirement is the primary limitation of traditional force-based methods. Structural performance can be characterized by various parameters such as strains, curvature, rotations, displacement, drift, or ductility which are of course all deformation quantities. This is of obvious importance since structures are designed to respond inelastically under even moderate earthquakes. Forces, however, are poor indicators of damage potential and any attempt to control inelastic structural behavior by controlling forces is likely to fail. DA - 2013/5// PY - 2013/5// DO - 10.2749/101686613x13439149157399 VL - 23 IS - 2 SP - 112-121 SN - 1016-8664 KW - design KW - earthquake KW - displacement KW - bridge KW - strength ER - TY - JOUR TI - Criteria for the initiation of modes of response of a caisson subjected to a breaking wave force AU - Lin, J. G. AU - Tung, C. C. D. T2 - Journal of Marine Science and Technology DA - 2013/// PY - 2013/// VL - 21 IS - 1 SP - 87-93 ER - TY - JOUR TI - An evaluation of microwave land surface emissivities over the continental United States to benefit GPM-era precipitation algorithms AU - Ferraro, R. R. AU - Peters-Lidard, C. D. AU - Hernandez, C. AU - Turk, F. J. AU - Aires, F. AU - Prigent, C. AU - Lin, X. AU - Boukabara, S. A. AU - Furuzawa, F. A. AU - Gopalan, K. AU - Harrison, K. W. AU - Karbou, F. AU - Li, L. AU - Liu, C. T. AU - Masunaga, H. AU - Moy, L. AU - Ringerud, S. AU - Tian, Y. D. T2 - IEEE Transactions on Geoscience and Remote Sensing DA - 2013/// PY - 2013/// VL - 51 IS - 1 SP - 378-398 ER - TY - JOUR TI - The effect of aging on the bioavailability of toluene sorbed to municipal solid waste components AU - Chen, Ye AU - Knappe, Detlef R. U. AU - Barlaz, Morton A. T2 - CHEMOSPHERE AB - Past practice of co-disposing priority pollutants with municipal solid waste (MSW) has led to the placement of more than 150 MSW landfills in the US on the National Priorities List of Superfund. Interactions between organic contaminants and MSW constituents and the effects of these interactions on contaminant fate are poorly understood. The objective of this study was to evaluate the effects of sorbate–sorbent aging time and sorbent decomposition on toluene bioavailability and fate. The bioavailability of 14C-toluene sorbed to individual MSW constituents [office paper, newsprint, model food and yard waste, high density polyethylene (HDPE), and poly(vinyl chloride) (PVC)] was evaluated after aging times of 1, 30, and 180 d. Biodegradable sorbents were tested in both fresh and anaerobically degraded forms to evaluate the effect of sorbent decomposition. At the termination of bioavailability tests, the distribution of 14C that was not converted to 14CO2 was measured by sequential lipophilic solvent and base extractions of sorbents followed by combustion of extracted sorbents. Increasing the toluene-sorbent aging time reduced the rate of toluene biodegradation for all MSW components except for HDPE. 14C remaining in sorbents at the completion of bioavailability tests was physically sequestered within and/or covalently bound to sorbent organic matter, and this fraction increased with increasing aging time. Up to 18.6% of 14C was associated with humic matter (humic and fulvic acids, humin) at the completion of bioavailability tests. DA - 2013/1// PY - 2013/1// DO - 10.1016/j.chemosphere.2012.06.062 VL - 90 IS - 2 SP - 251-259 SN - 1879-1298 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84869886366&partnerID=MN8TOARS KW - Bioavailability KW - Landfill KW - Municipal solid waste KW - Sorption KW - Desorption ER - TY - JOUR TI - Deformation-induced omega phase in nanocrystalline Mo AU - Cheng, G. M. AU - Yuan, H. AU - Jian, W. W. AU - Xu, W. Z. AU - Millett, P. C. AU - Zhu, Y. T. T2 - SCRIPTA MATERIALIA AB - A deformation-induced hexagonal ω phase was first observed in pure nanocrystalline body-centered cubic (bcc) Mo using high-resolution transmission electron microscopy. As the grains were refined into nanometer sizes by deformation using high-pressure torsion under a pressure of ∼4 GPa at room temperature, the ω phase formed at the grain boundaries of bcc Mo with a crystallographic relationship close to the {1 1 2}〈1 1 1〉 twin orientation. Its formation was mainly attributed to the shear deformation on {1 1 2} planes in bcc Mo. DA - 2013/1// PY - 2013/1// DO - 10.1016/j.scriptamat.2012.09.033 VL - 68 IS - 2 SP - 130-133 SN - 1359-6462 KW - Phase transformation KW - Nanocrystalline KW - Body-centered cubic KW - Deformation mechanism KW - High-pressure torsion ER -