TY - BOOK TI - Geosynthetics in Reinforcement and Hydraulic Applications AB - Proceedings of Geo-Denver 2007, New Peaks in Geotechnics, held in Denver, Colorado, February 18-21, 2007. Sponsored by the Geo-Institute of ASCE. This Geotechnical Special Publication contains 17 papers on the use of geosynthetics in earth structures by the construction industry. These papers present aspects related to recent advances in field and laboratory performance of geosynthetics as reinforcement and drainage materials. Topics include the characterization of geotextile voids; the interaction of geosynthetics with the surrounding soils; and construction aspects related to slopes, walls, and embankments on soft soils. Innovative approaches to design for efficient utilization of reinforcement capacity are presented. DA - 2007/10/14/ PY - 2007/10/14/ DO - 10.1061/9780784409091 PB - American Society of Civil Engineers SN - 9780784409091 UR - http://dx.doi.org/10.1061/9780784409091 ER - TY - CONF TI - MTBE adsorption kinetics on alternative adsorbents and packed bed adsorber performance AU - Rossner, A. AU - Knappe, D.R.U. C2 - 2007/// C3 - ACS National Meeting Book of Abstracts DA - 2007/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-37349024315&partnerID=MN8TOARS ER - TY - CONF TI - Simulating electricity spot prices in Brazil using neural network and design of experiments AU - Queiroz, A.R. AU - Oliveira, F.A. AU - Marangon Lima, J.W. AU - Balestrassi, P.P. AB - The electricity price has been one of the most important variables since the introduction of deregulation on the electricity sector. On this way, efficient forecasting methods of spot prices have become crucial to maximize the agent benefits. In Brazil the electricity price is based on the marginal cost provided by an optimization software (NEWAVE). Forecasting the operational marginal cost (OMC) and its volatility has been one big problem in the Brazilian market because of the computational time taken by this software. This work presents a fast and efficient model to simulate the OMC using DOE (design of experiments) and ANN (artificial neural networks) techniques. The paper proved that the combined techniques provided a promising result and may be applied to risk management and investment analysis. C2 - 2007/// C3 - 2007 IEEE Lausanne POWERTECH, Proceedings DA - 2007/// DO - 10.1109/PCT.2007.4538630 SP - 2029-2034 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-50849140143&partnerID=MN8TOARS ER - TY - JOUR TI - Determination of Time-domain Viscoelastic Functions using Optimized Interconversion Techniques AU - Mun, Sungho AU - Chehab, Ghassan R. AU - Kim, Y. Richard T2 - Road Materials and Pavement Design AB - ABSTRACT Several viscoelastic response functions are available to characterize the LVE behavior of asphalt concrete, some in time domain such as relaxation modulus E(t) and creep compliance D(t) and other such as complex modulus E* in frequency domain. The use of the complex modulus test has risen sharply after it has been incorporated in the M-E Pavement Design Guide and in the Superpave Simple Performance Test. With the availability of E* data it becomes advantageous to use mathematical interconversion techniques to obtain time-domain functions E(t) and D(t) which are typically used for constitutive modeling and other applications. This paper addresses the steps involved in conducting the interconversion between frequency-domain and time-domain functions. Issues considered include: a) presmoothing of raw data, b) refinement of phase angle data, c) Prony series representation of the fitted data including determination and sign-control of the Prony series coefficients, and d) interconversion techniques: approximate vs. exact. Finally, interconversion methods are evaluated by comparing D(t) data converted from E* to that measured in the lab. DA - 2007/1// PY - 2007/1// DO - 10.1080/14680629.2007.9690078 VL - 8 IS - 2 SP - 351-365 J2 - Road Materials and Pavement Design LA - en OP - SN - 1468-0629 2164-7402 UR - http://dx.doi.org/10.1080/14680629.2007.9690078 DB - Crossref ER - TY - CONF TI - The Use of Computational Fluid Dynamics (CFD) to Model UV-Initiated Advanced Oxidation Processes AU - Alpert, S. AU - Knappe, D. AU - Ducoste, J. T2 - International Ozone Association-International Ultraviolet Association World Congress C2 - 2007/// CY - Los Angeles, CA DA - 2007/// PY - 2007/8/27/ ER - TY - CONF TI - New Approaches in Determining the Spatial and Metabolic Interactions of Nitrogen-Transforming Bacteria in Microbial Flocs AU - de los Reyes, F.L. AU - Ducoste, J. AU - Hyman, M. AU - Mota, C. AU - Aslett, D. AU - Hong, H. T2 - National Science Foundation (NSF) Microbial Observatories(MO)/Microbial Interactions and Processes (MIP) Meeting C2 - 2007/// CY - Washington, DC DA - 2007/// PY - 2007/3/1/ ER - TY - CONF TI - Experimental and Numerical Analysis of Grease Interceptor Performance AU - Aziz, T. AU - Holt, L. AU - Keener, K. AU - Ducoste, J. T2 - North Carolina American Water Works Association (AWWA) & Water Environment Association (WEA) Conference C2 - 2007/// CY - Greensboro, NC DA - 2007/// PY - 2007/12/3/ ER - TY - CONF TI - Field Observations of Grease Interceptor Performance AU - Aziz, T. AU - Holt, L. AU - Keener, K. AU - Ducoste, J. T2 - Water Environment Federation Workshop C2 - 2007/// CY - Raleigh, NC DA - 2007/// PY - 2007/// ER - TY - RPRT TI - UV Disinfection for Large Water Treatment Plants AU - Hulsey, R. AU - Linden, K.G. AU - Ducoste, J.J. A3 - American Water Works Association Research Foundation DA - 2007/// PY - 2007/// PB - American Water Works Association Research Foundation ER - TY - JOUR TI - Money from Old Rope? Tracking the Carbon in Landfill Management AU - Barlaz, M.A. AU - Banister, A. AU - Hater, G. AU - Chanton, J. AU - Green, R. T2 - Waste Management World DA - 2007/// PY - 2007/// VL - 8 IS - 4 SP - 127 – 31 ER - TY - JOUR TI - Greenhouse Gas Inventories for the Waste Industry: The Importance of Measuring Landfill Gas Total Emissions AU - Hater, G. AU - Green, R. AU - Goldsmith, D. AU - Barlaz, M. AU - Abichou, T. AU - Chanton, J. T2 - MSW Management DA - 2007/// PY - 2007/// VL - 17 SP - 4 ER - TY - CONF TI - Evaluation of Special Wastes for Supplemental Liquid Addition in Bioreactor Landfills AU - Barlaz, M.A. AU - Sadri, A. AU - Staley, B.F. AU - Hater, G.R. T2 - 11th International Waste Management and Landfill Symposium C2 - 2007/// CY - Cagliari, Italy DA - 2007/// PY - 2007/10/1/ ER - TY - CONF TI - Simulation And Modeling of The Fate And Transport of Chemical Warfare Agents in Laboratory-Scale Landfills AU - Barlaz, M.A. AU - Saquing, J. AU - Mezzari, I. AU - Knappe, D.R.U. T2 - 11th International Waste Management and Landfill Symposium C2 - 2007/// CY - Cagliari, Italy DA - 2007/// PY - 2007/10/1/ ER - TY - CONF TI - Biotransformation of FTOH-Based Materials in Lab-Scale Landfill Simulation Vessels and Mixed Bacterial Cultures Under Methanogenic Conditions AU - Wang, N. AU - Szostek, B. AU - Barlaz, M.A. AU - Buck, R. AU - Folsom, P. AU - Wolstenholme, B. AU - Sulecki, L. AU - Panciroli, P. AU - Berti, W. AU - Gannon, J. T2 - Society of Environmental Toxicology and Chemistry (SETAC) C2 - 2007/// CY - Milwaukee, WI DA - 2007/// PY - 2007/11/12/ ER - TY - CONF TI - A Review of Five Bioreactor Landfill Operations: Leachate Production and Waste Settlement AU - Barlaz, M.A. AU - Benson, C.H. T2 - 2007 Solid Waste Association of North America (SWANA) Landfill Symposium C2 - 2007/// CY - San Diego, CA DA - 2007/// PY - 2007/6/25/ ER - TY - CONF TI - A Review of Five Bioreactor Landfill Operations: Leachate Quality and Gas Production AU - Barlaz, M.A. AU - Benson, C.H. T2 - 2007 Solid Waste Association of North America (SWANA) Landfill Symposium C2 - 2007/// CY - San Diego, CA DA - 2007/// PY - 2007/6/25/ ER - TY - CONF TI - Estimation of Carbon Sequestration in Landfills AU - Barlaz, M.A. T2 - Waste Tech Landfill Technology Conference C2 - 2007/// CY - Miami Beach, FL DA - 2007/// PY - 2007/3/12/ ER - TY - SOUND TI - Long-Term Management of Landfills: Is Functional Stability a Reasonable Approach? AU - Barlaz, M.A. DA - 2007/// PY - 2007/// ER - TY - SOUND TI - Leachate Quality and Gas Generation at Bioreactor Landfills AU - Barlaz, M.A. DA - 2007/// PY - 2007/// M3 - Invited lecture ER - TY - SOUND TI - The Application of Life-Cycle Analysis to Integrated Solid Waste Management Planning for the State of Delaware AU - Barlaz, M.A. DA - 2007/// PY - 2007/// ER - TY - SOUND TI - Physical Containment and Survival in Landfills AU - Barlaz, M.A. DA - 2007/// PY - 2007/// M3 - Invited lecture ER - TY - JOUR TI - Behavior of Three-Dimensionally Woven Glass Fiber Reinforced Polymeric Bridge Deck AU - Johnson, C. AU - Mohamed, T. AU - Rizkalla, S. T2 - Composites Research Journal DA - 2007/// PY - 2007/// VL - 1 IS - 2 SP - 27–42 ER - TY - JOUR TI - Flexural Design of High Strength Concrete Members AU - Mertol, H.C. AU - Rizkalla, S. AU - Zia, P. AU - Mirmiran, A. T2 - ACI Structural Journal DA - 2007/4// PY - 2007/4// VL - 104 IS - 4 ER - TY - JOUR TI - Durability of Concrete Beams Prestressed with CFRP Tendons AU - Mertol, H. AU - Rizkalla, S. AU - Scott, P. AU - Lees, J. AU - El-Hacha, R. T2 - ACI Special Publication, Case Histories and Use of FRP for Prestressing Applications DA - 2007/10// PY - 2007/10// VL - S245 SP - 1–20 ER - TY - JOUR TI - CFRP Materials for Reinforced Concrete Structures AU - Dawood, M. AU - Rizkalla, S. AU - Gleich, H. T2 - PCI Journal DA - 2007/9// PY - 2007/9// VL - 52 IS - 5 SP - 27–29 ER - TY - RPRT TI - Alternative Adsorbents for the Removal of Polar Organic Contaminants AU - Knappe, D.R.U. AU - Rossner, A. AU - Snyder, S.A. AU - Strickland, C. A3 - American Water Works Association Research Foundation DA - 2007/// PY - 2007/// M1 - Project #2905 M3 - Executive Summary PB - American Water Works Association Research Foundation SN - Project #2905 ER - TY - CONF TI - Agent-Based Modeling to Simulate Contamination Events and to Analyze Threat Management Strategies in Water Distribution Systems AU - Zechman, Emily M. T2 - World Environmental and Water Resources Congress 2007 AB - In the event of contamination of a water distribution system, decisions must be made to mitigate the impact of the contamination to protect public health. Making threat management decisions while the contaminant is spreading through the network is a difficult process due to uncertainty and lack of monitoring data. This is further complicated by the response actions taken by the utility managers and water consumption choices made by the consumers as they all will affect the hydraulics, thus the spread of the contaminant plume, in the network. A modeling framework that allows the simulation of a contamination event under the effects of actions taken by utility managers and consumers will be a useful tool for the analysis of alternative threat mitigation and management strategies. The complex interactions between the managers' network operation decisions and consumers' water consumption choices, and the response of the hydraulics and contaminant transport in the water distribution system will be simulated using an agent-based modeling approach. Agent-based models are simulated individuals that are formulated as interacting autonomous entities. Each agent selects actions based on a set of rules that represent an individual's autonomy, goal-based desires, and reaction to the environment and the actions of other agents. This paper presents a multi-agent modeling framework that will combine agent-based, mechanistic, and dynamic methods. As actions taken by agents affect demands and flows in the system, dynamic approaches will update the mechanistic model and the identification of the contaminant source to supply the "utility manager" agents with the latest information as it becomes available. The framework will be designed to consider the typical issues involved in water distribution threat management and will provide valuable analysis of threat containment strategies for water distribution system contamination events. C2 - 2007/5/11/ C3 - World Environmental and Water Resources Congress 2007 DA - 2007/5/11/ DO - 10.1061/40927(243)525 PB - American Society of Civil Engineers SN - 9780784409275 UR - http://dx.doi.org/10.1061/40927(243)525 DB - Crossref ER - TY - BOOK TI - Transforming sustainability strategy into action: The chemical industry AU - Johnson, Jeremiah AU - Beloff, B. AU - Lines, M. AU - Tanzil, D. AB - Key parameters of OECD biodegradation screening tests were analyzed for impact on the assessment of biodegradation potential of selected fragrance compounds.Comparison of official Japanese OECD 301C test results for 48 predominantly readily biodegradable chemicals with recent OECD 301F screening data demonstrated a significantly higher occurrence of false negatives potentially attributable to inoculum limitations for the former, while for the latter, restriction to 28 days was frequently limiting.Influence of test concentration was studied for two groups of quaternary carbon-containing compounds under high (OECD 301F) and low (OECD 301D) concentrations and extended incubations. Ionones were generally ultimately biodegradable within 28 days or readily biodegradable, whereas damascones reached ultimate biodegradation in OECD 301D tests only and required extended incubations.Predictions from Biowin and Catalogic models were analyzed for ionones, damascones and other selected structural groups of fragrance compounds. Comparison with previously published experimental data revealed significant differences in results between OECD screening tests, thus illustrating the shortcomings of currently available data collections and the potential risk of training prediction models with false negative results, particularly if used for models that are primarily based on data from one specific test. In addition, the analysis revealed specific limitations for prediction models that cannot take into account positioning of fragments within a structure. As a result, it appears that the presence of more than one unfavorable fragment usually does not allow reaching currently accepted threshold scores that would identify a given compound as biodegradable.The outcome of the analyses of this study underlines the need to take into account results from OECD screening tests that are best adapted to physico-chemical properties of fragrances (hydrophobicity, volatility and inhibition potential at high test concentration) and conducted at reduced stringency compared to OECD guidelines (extended incubation owing to reduced bioavailability). Negative MITI database results should be critically reviewed, particularly for quaternary carbon-containing compounds. For future efforts aimed at designing more environmentally benign chemicals, the apparent underestimations will have to be overcome by providing more realistic experimental data that should subsequently be used to improve current biodegradation prediction models for better guidance. DA - 2007/2// PY - 2007/2// DO - 10.1016/j.ecolecon.2006.03.023 VL - 61 PB - Elsevier BV SE - 194–195 UR - http://dx.doi.org/10.1016/j.ecolecon.2006.03.023 ER - TY - SOUND TI - Climate Informed Water Management AU - Arumugam, S. DA - 2007/7// PY - 2007/7// ER - TY - CONF TI - Improved Management of Falls Lake Reservoir during the Summer Season using Climate Information based Monthly Streamflow Forecasts: Role of Restrictions in Water supply and Water quality management AU - Golembesky, K. AU - Arumugam, S. AU - Devineni, N. T2 - North Carolina Water Resources Research Institute Annual Conference C2 - 2007/3// CY - Raleigh, NC DA - 2007/3// PY - 2007/3// ER - TY - CONF TI - Multi-model Ensembling of Probabilistic Streamflow Forecasts: Role of Predictor State Space in Skill Evaluation AU - Devineni, N. AU - Arumugam, S. AU - Ghosh, S. T2 - North Carolina Water Resources Research Institute Annual Conference C2 - 2007/3// CY - Raleigh, NC DA - 2007/3// PY - 2007/3// ER - TY - CONF TI - Multimodel Ensembles of Streamflow Forecasts: Role ofPredictor State in Developing Optimal Combinations AU - Devineni, N. AU - Arumugam, S. T2 - American Geophysical Union Fall Meeting C2 - 2007/12/10/ CY - San Francisco, CA DA - 2007/12/10/ PY - 2007/12/10/ ER - TY - CONF TI - Predictability of U.S. Winter Precipitation: Role of ENSO state in Developing Multimodel Combinations AU - Arumugam, S. AU - Devineni, N. T2 - American Geophysical Union Fall Meeting C2 - 2007/12/10/ CY - San Francisco, CA DA - 2007/12/10/ PY - 2007/12/10/ ER - TY - JOUR TI - Observation and Analysis of Popular Root Control Methods in Pilot Scale Sanitary Sewer AU - Wood, Justin AU - Aziz, Tarek AU - Groninger, John AU - Holt, Leon AU - Keener, Kevin AU - Ducoste, Joel T2 - Proceedings of the Water Environment Federation AB - Observation and Analysis of Popular Root Control Methods in Pilot Scale Sanitary SewerRoot intrusion in sanitary sewers is a significant contributor to the alarming rate of sanitary sewer overflows occurring in the US. A better understanding of popular root control methods is required for the development of an optimal root removal protocol. This research focuses on experiment design and data collection for the comparison of popular root control methods in a pilot scale sewer...Author(s)Justin WoodTarek AzizJohn GroningerLeon HoltKevin KeenerJoel DucosteSourceProceedings of the Water Environment FederationSubjectSession 86: Operation and MaintenanceDocument typeConference PaperPublisherWater Environment FederationPrint publication date Oct, 2007ISSN1938-6478SICI1938-6478(20071001)2007:11L.6842;1-DOI10.2175/193864707787223565Volume / Issue2007 / 11Content sourceWEFTECFirst / last page(s)6842 - 6864Copyright2007Word count105Subject keywordsSANITARY SEWER OVERFLOWTREE ROOT CONTROLDICHLOBENIL (ROOTX)DIQUAT (RAZOROOTER II) DA - 2007/10/1/ PY - 2007/10/1/ DO - 10.2175/193864707787223565 VL - 2007 IS - 11 SP - 6842-6864 J2 - proc water environ fed LA - en OP - SN - 1938-6478 UR - http://dx.doi.org/10.2175/193864707787223565 DB - Crossref ER - TY - CHAP TI - Anaerobic Decomposition of Refuse in Landfills and Methane Oxidation in Landfill Covers AU - Hilger, H.H. AU - Barlaz, M.A. T2 - Manual of Environmental Microbiology A2 - Hurst, Christon A2 - Crawford, Ronald A2 - Garland, Jay A2 - Lipson, David A2 - Mills, Aaron A2 - Stetzenbach, Linda AB - This chapter discusses techniques for the study of anaerobic biological reactions and microorganisms involved in refuse decomposition as it occurs in a landfill as well as the aerobic biological reactions that occur in the landfill cover. The chapter begins with a brief description of the major components of a sanitary landfill followed by a discussion of municipal solid waste (MSW) composition. Next, the manner in which cellulosic substrates are converted to CH 4 and CO 2 is described, followed by a discussion of CH 4 oxidation in landfill cover soils. Factors that influence both anaerobic decomposition rates in landfills and aerobic CH 4 oxidation in landfill covers are discussed. This is followed by a section on systems that can be used to simulate refuse decomposition and techniques that can be used to measure refuse biodegradation and microbial activity in landfills. Cellulose and hemicellulose are the principal biodegradable components of MSW. Carboxylic acids and H 2 will accumulate and the pH of the system will fall, thus inhibiting methanogenesis. After placement of refuse in a landfill, several months or longer is necessary for the proper growth conditions and the required microbiological system to become established for biological decomposition. The presence of anaerobic protozoa in refuse excavated from landfills has been documented, and many of the protozoa contained symbiotic methanogenic bacteria that utilize H 2 released by the host's hydrogenosomes. Common contaminants in older landfills and leachate plumes include alkylbenzenes, ketones, and chlorinated aliphatic hydrocarbons. PY - 2007/// DO - 10.1128/9781555815882.ch67 ET - 3rd PB - American Society of Microbiology ER - TY - CONF TI - Non-thermal dental ablation using ultra-short pulsed near infrared laser AU - Fahey, M.E. AU - Jaunich, M.K. AU - Dutta, A. AU - Tata, D.B. AU - Waynant, R.W. AU - Mason, H.L. AU - Mitra, K. C2 - 2007/// C3 - Proceedings of the ASME Summer Bioengineering Conference 2007, SBC 2007 DA - 2007/// SP - 81-82 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-40449103708&partnerID=MN8TOARS ER - TY - JOUR TI - Experimental verification and application of a practical corrosion model for uniformly depassivated steel in concrete AU - Ghods, Pouria AU - Isgor, O. Burkan AU - Pour-Ghaz, Mohammad T2 - Materials and Structures DA - 2007/10/24/ PY - 2007/10/24/ DO - 10.1617/s11527-007-9320-3 VL - 41 IS - 7 SP - 1211-1223 J2 - Mater Struct LA - en OP - SN - 1359-5997 1871-6873 UR - http://dx.doi.org/10.1617/s11527-007-9320-3 DB - Crossref ER - TY - CONF TI - Virtual Experiments to Investigate Steel Corrosion in Concrete AU - Pour-Ghaz, M. AU - Isgor, O. Burkan AU - Ghods, P. T2 - International Workshop on Computing in Civil Engineering 2007 AB - Virtual experiments are one of the integral parts of the advanced civil engineering practice since they eliminate time-consuming and expensive laboratory studies, and they are useful for educational and training purposes. In the present work, a number of virtual experiments for investigating the corrosion of reinforcement in concrete are designed, and the effect of different parameters on the corrosion process is examined. The design of the experiments is based on non-linear solution of Laplace's equation with polarized surface boundary conditions by the finite element method, for which an under-relaxation technique is implemented. Using the results of the virtual experiments, a closed-form solution for the considered domain is obtained. By using this solution, the effect of a number of factors that affect the corrosion process can be investigated; an example of this investigation is presented. These experiments can also be effectively used for service life design and structural health and integration monitoring purposes; these two approaches are discussed in detail. C2 - 2007/7/23/ C3 - Computing in Civil Engineering (2007) DA - 2007/7/23/ DO - 10.1061/40937(261)64 PB - American Society of Civil Engineers SN - 9780784409374 UR - http://dx.doi.org/10.1061/40937(261)64 DB - Crossref ER - TY - CONF TI - Sediment and Shoaling Processes: Bolivar Ferry Terminal, Galveston, Texas AU - Kite, II, R. D. AU - Edge, B. L. AU - Mears, W. D. T2 - 11th Triennial International Conference on Ports AB - The Bolivar Ferry Terminal Sediment and Shoaling Study aimed at understanding the cause of the ongoing shoaling and sedimentation within two existing ferry landings and determine the effects of adding a third landing with a reconfigured breakwater system. Compounding the shoaling effects was the proximity of the dredge material placement area located less than 1,000 feet south of the terminal. Already under construction (2005–2007) shoaling was an ongoing concern highlighted by the planned reconfiguration of the ferry terminal. The Galveston-Bolivar Ferry service, located in Galveston County Texas, provides transportation between Galveston Island and Bolivar Peninsula for local residents and tourists using up to six ferries. The Bolivar Ferry Terminal is sited within the throat of the Galveston Inlet where tidal velocities are at a maximum, increasing deposition within the supporting structures of the ferry landings. Determining the complex forces in and around the ferry terminal, for longshore transport, a hydrodynamic model was utilized to analyze and provide solutions for several short term and long term circulation issues. The placement of future dredge material and the resolve of the appropriate reconfiguration to reduce or eliminate the shoaling within the terminal were two of the primary issues. C2 - 2007/3/22/ C3 - Ports 2007 DA - 2007/3/22/ DO - 10.1061/40834(238)51 PB - American Society of Civil Engineers SN - 9780784408346 UR - http://dx.doi.org/10.1061/40834(238)51 DB - Crossref ER - TY - JOUR TI - Investigation of unrestrained cylinders rolling in steady uniform flows AU - Davis, Jack E. AU - Edge, Billy L. AU - Chen, Hamn-Ching T2 - Ocean Engineering AB - The goal of this study is to understand the movement of unexploded ordnance that may become unburied and forced by currents. Symmetrical, smooth, finite-length, unrestrained cylinders were studied in steady, uniform flows over a range of Reynolds numbers in a smooth-bottomed, horizontal flume. The study uses PIV tracking methods in the laboratory to identify the movement of ordnance simulated by unrestrained cylinders. The PIV is supported with a numerical analysis using a RANS flow solver. The simulations showed that at low Reynolds numbers the cylinders should roll at speeds near 70% of the free-stream flow. DA - 2007/7// PY - 2007/7// DO - 10.1016/j.oceaneng.2006.10.002 VL - 34 IS - 10 SP - 1431-1448 J2 - Ocean Engineering LA - en OP - SN - 0029-8018 UR - http://dx.doi.org/10.1016/j.oceaneng.2006.10.002 DB - Crossref KW - UXO KW - physical modeling KW - numerical models KW - hydrodynamics KW - RANS solver KW - PIV ER - TY - JOUR TI - A generic design approach for EB and NSM longitudinally plated RC beams AU - Oehlers, Deric John AU - Liu, Irene AU - Seracino, Rudolf T2 - Construction and Building Materials AB - There has been much good research on adhesive bonding plates to existing reinforced concrete structures which is now readily available in the form of published books or guidelines. Most of the fundamental and unique failure modes of plated structures have now been identified and quantified and research has reached the stage where it can be applied as design in practice and with confidence. This paper brings together this research and shows that the fundamental behaviour of plated structures can be described in generic terms for all forms of plating, which will eventually enable generic design rules to be developed for all types of adhesive plating. A generic design procedure is presented for adhesive bonding longitudinal plates to reinforced concrete (RC) beams and slabs: that applies to both externally bonded (EB) plates and near surface mounted (NSM) plates; that can be applied to prestressed and unprestressed beams; that covers all plate materials, plate configurations and plate adhesion to any surface; covers all four major debonding mechanisms at serviceability or ultimate limit states; and quantifies the flexural and shear strengths as well as the ductility associated with moment redistribution. DA - 2007/4// PY - 2007/4// DO - 10.1016/j.conbuildmat.2006.06.018 VL - 21 IS - 4 SP - 697-708 J2 - Construction and Building Materials LA - en OP - SN - 0950-0618 UR - http://dx.doi.org/10.1016/j.conbuildmat.2006.06.018 DB - Crossref KW - externally bonded KW - near surface mounted KW - retrofitting KW - reinforced concrete ER - TY - JOUR TI - AU - Seracino, R. AU - Chen, J.F. AU - Hollaway, L. T2 - Construction and Building Materials DA - 2007/4// PY - 2007/4// DO - 10.1016/j.conbuildmat.2006.06.005 VL - 21 IS - 4 SP - 695-696 J2 - Construction and Building Materials LA - en OP - SN - 0950-0618 UR - http://dx.doi.org/10.1016/j.conbuildmat.2006.06.005 DB - Crossref ER - TY - CONF TI - Experimental Study of Overwash AU - Edge, Billy L. AU - Park, Young Hyun AU - Overton, Margery T2 - Sixth International Symposium on Coastal Engineering and Science of Coastal Sediment Process AB - Overwash induced by storm conditions is one mechanism causing coastline change with cross-shore erosion and deposition. Many field studies have been conducted but laboratory experiments are few. This experimental study was conducted for estimation of eroded sand volume by overwash. The experiments were conducted at two different wave heights and four different wave periods in two different slopes of beach face for regular and irregular waves. The experiments were done in a 2D wave tank on mid-scale at Texas A&M University. The measured data from 32 different tests were used to analyze the characteristics of overwash. C2 - 2007/5/11/ C3 - Coastal Sediments '07 DA - 2007/5/11/ DO - 10.1061/40926(239)163 PB - American Society of Civil Engineers SN - 9780784409268 UR - http://dx.doi.org/10.1061/40926(239)163 DB - Crossref ER - TY - JOUR TI - A practical method for calculating the corrosion rate of uniformly depassivated reinforcing bars in concrete AU - Ghods, P. AU - Isgor, O.B. AU - Pour-Ghaz, M. T2 - Materials and Corrosion AB - Abstract The quantification of active corrosion rate of steel in concrete structures through nondestructive methods is a crucial task for scheduling maintenance/repair operations and for achieving accurate service life predictions. Measuring the polarization resistance of corroding systems and using the Stern‐Geary equation to calculate the corrosion current density of active steel is a widely‐used method for this purpose. However, these measurements are greatly influenced by environmental factors; therefore, accurate monitoring of corrosion requires integrating the instantaneous corrosion rates over time. Although advanced numerical models are helpful in research settings, they remain to be computationally expensive and complex to be adopted by general engineering community. In this paper, a practical numerical model for predicting corrosion rate of uniformly depassivated steel in concrete is developed. The model is built on Stern's earlier work that an optimum anode‐to‐cathode ratio exists for which the corrosion current on the metal surface reaches a maximum value. The developed model, which represents the corrosion rate as a function of concrete resistivity and oxygen concentration, is validated using experimental data obtained from the literature. DA - 2007/4// PY - 2007/4// DO - 10.1002/maco.200604010 VL - 58 IS - 4 SP - 265-272 J2 - Materials and Corrosion LA - en OP - SN - 0947-5117 1521-4176 UR - http://dx.doi.org/10.1002/maco.200604010 DB - Crossref ER - TY - JOUR TI - Dining at the Periodic Table:  Metals Concentrations as They Relate to Recycling AU - Johnson, Jeremiah AU - Harper, E. M. AU - Lifset, Reid AU - Graedel, T. E. T2 - Environmental Science & Technology AB - A correlation between the prices of a variety of substances and their dilutions in their initial matrices was shown in 1959 by T.K. Sherwood. The research presented here shows that the relationship holds for engineering metals today, which we termed the metals-specific Sherwood plot. The concentrations of metals in products (e.g., printed wiring boards and automobiles) and waste streams (e.g., municipal solid waste, and construction and demolition debris) were plotted with this correlation. In addition, for the products and waste streams that undergo disassembly at end-of-life, the metals concentrations of the disassembled components were also plotted. It was found that most of the metals that are currently targeted for recycling have post-disassembly concentrations that lie above the metals-specific Sherwood plot (i.e., have concentrations that are more enriched than minimum profitable ore grades). This suggests that material concentration plays a role in the viability of recycling at end-of-life. As products grow in complexity and the variety of materials used, analyses such as this one provide insight for policymakers and those interested in material sustainability into macro-level trends of material use and future recycling practices. DA - 2007/3// PY - 2007/3// DO - 10.1021/es060736h VL - 41 IS - 5 SP - 1759-1765 J2 - Environ. Sci. Technol. LA - en OP - SN - 0013-936X 1520-5851 UR - http://dx.doi.org/10.1021/es060736h DB - Crossref ER - TY - JOUR TI - Tubular Membrane Cathodes for Scalable Power Generation in Microbial Fuel Cells AU - Zuo, Yi AU - Cheng, Shaoan AU - Call, Doug AU - Logan, Bruce E. T2 - Environmental Science & Technology AB - One of the greatest challenges for using microbial fuel cells (MFCs) for wastewater treatment is creating a scalable architecture that provides large surface areas for oxygen reduction at the cathode and bacteria growth on the anode. We demonstrate here a scalable cathode concept by showing that a tubular ultrafiltration membrane with a conductive graphite coating and a nonprecious metal catalyst (CoTMPP) can be used to produce power in an MFC. Using a carbon paper anode (surface area Aan = 7 cm2, surface area per reactor volume Aan,s = 25 m2/m3), an MFC with two 3-cm tube cathodes (Acat = 27 cm2, Acat,s = 84 m2/m3) generated up to 8.8 W/m3 (403 mW/m2) using glucose [0.8 g/L in a 50 mM phosphate buffer solution (PBS)], which was only slightly less than that produced using a carbon paper cathode with a Pt catalyst (9.9 W/m3, 394 mW/m2; Acat= 7 cm2, Acat,s= 25 m2/m3). Coulombic efficiencies (CEs) with carbon paper anodes were 25-40% with tube cathodes (CoTMPP), compared to 7-19% with a carbon paper cathode. When a high-surface-area graphite brush anode was used (Aan = 2235 cm2, Aan,s = 7700 m2/m3) with two tube cathodes placed inside the reactor (Acat = 27 cm2, Acas, = 93 m2/m3), the MFC produced 17.7 W/m3 with a CE = 70-74% (200 mM PBS). Further increases in the surface area of the tube cathodes to 54 cm2 (120 m2/m3) increased the total power output (from 0.51 to 0.83 mW), but the increase in volume resulted in a constant volumetric power density (approximately 18 W/m3). These results demonstrate that an MFC design using tubular cathodes coated with nonprecious metal catalysts, and brush anodes, is a promising architecture that is intrinsically scalable for creating larger systems. Further increases in power output will be possible through the development of cathodes with lower internal resistances. DA - 2007/5// PY - 2007/5// DO - 10.1021/es0627601 VL - 41 IS - 9 SP - 3347-3353 J2 - Environ. Sci. Technol. LA - en OP - SN - 0013-936X 1520-5851 UR - http://dx.doi.org/10.1021/es0627601 DB - Crossref ER - TY - JOUR TI - Rethinking Organic Aerosols: Semivolatile Emissions and Photochemical Aging AU - Robinson, A. L. AU - Donahue, N. M. AU - Shrivastava, M. K. AU - Weitkamp, E. A. AU - Sage, A. M. AU - Grieshop, A. P. AU - Lane, T. E. AU - Pierce, J. R. AU - Pandis, S. N. T2 - Science AB - Most primary organic-particulate emissions are semivolatile; thus, they partially evaporate with atmospheric dilution, creating substantial amounts of low-volatility gas-phase material. Laboratory experiments show that photo-oxidation of diesel emissions rapidly generates organic aerosol, greatly exceeding the contribution from known secondary organic-aerosol precursors. We attribute this unexplained secondary organic-aerosol production to the oxidation of low-volatility gas-phase species. Accounting for partitioning and photochemical processing of primary emissions creates a more regionally distributed aerosol and brings model predictions into better agreement with observations. Controlling organic particulate-matter concentrations will require substantial changes in the approaches that are currently used to measure and regulate emissions. DA - 2007/3/2/ PY - 2007/3/2/ DO - 10.1126/science.1133061 VL - 315 IS - 5816 SP - 1259-1262 J2 - Science LA - en OP - SN - 0036-8075 1095-9203 UR - http://dx.doi.org/10.1126/science.1133061 DB - Crossref ER - TY - JOUR TI - Is the gas-particle partitioning in alpha-pinene secondary organic aerosol reversible? AU - Grieshop, Andrew P. AU - Donahue, Neil M. AU - Robinson, Allen L. T2 - Geophysical Research Letters AB - This paper discusses the reversibility of gas‐particle partitioning in secondary organic aerosol (SOA) formed from α ‐pinene ozonolysis in a smog chamber. Previously, phase partitioning has been studied quantitatively via SOA production experiments and qualitatively by perturbing temperature and observing particle evaporation. In this work, two methods were used to isothermally dilute the SOA: an external dilution sampler and an in‐chamber technique. Dilution caused some evaporation of SOA, but repartitioning took place on a time scale of tens of minutes to hours–consistent with an uptake coefficient on the order of 0.001–0.01. However, given sufficient time, α ‐pinene SOA repartitions reversibly based on comparisons with data from conventional SOA yield experiments. Further, aerosol mass spectrometer (AMS) data indicate that the composition of SOA varies with partitioning. These results suggest that oligomerization observed in high‐concentration laboratory experiments may be a reversible process and underscore the complexity of the kinetics of formation and evaporation of SOA. DA - 2007/7/25/ PY - 2007/7/25/ DO - 10.1029/2007GL029987 VL - 34 IS - 14 SP - 11053 J2 - Geophys. Res. Lett. LA - en OP - SN - 0094-8276 UR - http://dx.doi.org/10.1029/2007GL029987 DB - Crossref ER - TY - CHAP TI - Cyberinfrastructure for Contamination Source Characterization in Water Distribution Systems AU - Sreepathi, Sarat AU - Mahinthakumar, Kumar AU - Zechman, Emily AU - Ranjithan, Ranji AU - Brill, Downey AU - Ma, Xiaosong AU - von Laszewski, Gregor T2 - Computational Science – ICCS 2007 A2 - Shi, Y. A2 - van Albada, G.D. A2 - Dongarra, J. A2 - Sloot, P.M.A. T3 - Lecture Notes in Computer Science AB - This paper describes a preliminary cyberinfrastructure for contaminant characterization in water distribution systems and its deployment on the grid. The cyberinfrastructure consists of the application, middleware and hardware resources. The application core consists of various optimization modules and a simulation module. This paper focuses on the development of specific middleware components of the cyberinfrastructure that enables efficient seamless execution of the application core in a grid environment. The components developed in this research include: (i) a coarse-grained parallel wrapper for the simulation module that includes additional features for persistent execution, (ii) a seamless job submission interface, and (iii) a graphical real time application monitoring tool. The performance of the cyberinfrastructure is evaluated on a local cluster and the TeraGrid. PY - 2007/// DO - 10.1007/978-3-540-72584-8_139 SP - 1058-1065 OP - PB - Springer Berlin Heidelberg SN - 9783540725831 9783540725848 SV - 4487 UR - http://dx.doi.org/10.1007/978-3-540-72584-8_139 DB - Crossref ER - TY - CONF TI - Monitoring Sensor Network Design for Water Distribution Source Inversion Problems AU - Tryby, M. E. AU - Propato, M. AU - Ranjithan, R. T2 - World Environmental and Water Resources Congress 2007 AB - Monitoring network design for the detection of contaminants in water distribution systems is currently an active area of research. Much of the effort has been directed at the contamination detection sub-problem and the expression of public health protection objectives. Monitoring networks, once they are in place, however, are likely to be used to gather monitoring data for source inversion as well. Thus, the design of these networks with the unique objectives associated with source inversion in mind is a necessity. Source inversion problems in water distribution systems are inherently under-determined and exhibit solution non-uniqueness. Judicious monitoring design is one approach for addressing these difficulties. Herein, discrete linear inverse theory is applied to the monitoring sensor network design problem; in particular, a quantitative description of solution existence, uniqueness, stability, and resolution is developed using singular value decomposition. C2 - 2007/5/11/ C3 - World Environmental and Water Resources Congress 2007 DA - 2007/5/11/ DO - 10.1061/40927(243)521 PB - American Society of Civil Engineers SN - 9780784409275 UR - http://dx.doi.org/10.1061/40927(243)521 DB - Crossref ER - TY - CONF TI - Evaluation of Non-Uniqueness in Contaminant Source Characterization Based on Sensors with Event Detection Methods AU - Kumar, Jitendra AU - Zechman, E. M. AU - Brill, E. D. AU - Mahinthakumar, G. AU - Ranjithan, S. AU - Uber, J. T2 - World Environmental and Water Resources Congress 2007 AB - Due to the present state of sensor technology, during a water distribution contamination event, sensors may be able to detect only the presence of a contaminant and not necessarily the complete concentration profile. Some sensors trigger a detection based on a specified threshold concentration of observation, yielding a binary detection/no-detection signal. Event detection can also be based on observed concentrations of water quality parameters, such as pH and chlorine, which are routinely measured. These concentration observations are then processed through event detection algorithms to yield a detection/no-detection signal. These event detection techniques filter the measured concentrations at sensors to produce a discrete signal. When using this filtered information to characterize the contamination source, the certainty of identifying a unique solution is likely reduced, i.e., a set of widely different source characteristics may provide a match for the sensor observations. The authors previously presented an evolutionary algorithm-based procedure for source characterization and for assessing non-uniqueness by generating a set of maximally different alternatives. The procedure is extended here to characterize a contaminant source and any non-uniqueness arising by using sensor information processed through different event detection methods. C2 - 2007/5/11/ C3 - World Environmental and Water Resources Congress 2007 DA - 2007/5/11/ DO - 10.1061/40927(243)513 PB - American Society of Civil Engineers SN - 9780784409275 UR - http://dx.doi.org/10.1061/40927(243)513 DB - Crossref ER - TY - CONF TI - Considering Demand Variability and Measurement Uncertainties in Adaptive Source Characterization in Water Distribution Networks AU - Liu, Li AU - Brill, Jr., E. Downey AU - Mahinthakumar, G. AU - Uber, James AU - Zechman, Emily M. AU - Ranjithan, S. T2 - World Environmental and Water Resources Congress 2007 AB - Characterizing the sources of contamination in water distribution networks continues to be a challenging problem. Several methods have been reported to address this problem. The authors previously presented and continue to investigate an adaptive search procedure that attempts to solve this problem under dynamic conditions. Since demand variability and measurement errors contribute significantly to the quality of the solutions obtained as well as the time to solve the problem, we investigate these effects on the adaptive dynamic optimization procedure. First, the effects of these variabilities and uncertainties on the solutions obtained under deterministic conditions are evaluated. Second, we incorporate them such that the search for the source characterization is conducted under noisy conditions. This paper reports the results from these investigations based on an investigation conducted for an illustrative water distribution network. C2 - 2007/5/11/ C3 - World Environmental and Water Resources Congress 2007 DA - 2007/5/11/ DO - 10.1061/40927(243)502 PB - American Society of Civil Engineers SN - 9780784409275 UR - http://dx.doi.org/10.1061/40927(243)502 DB - Crossref ER - TY - CONF TI - Evolutionary Algorithms-Based Grid Computational Framework for Solving Groundwater Characterization Problems AU - Mirghani, Baha AU - Tryby, Michael AU - Ranjithan, Ranji AU - Mahinthakumar, Kumar T2 - World Environmental and Water Resources Congress 2007 AB - This paper investigates groundwater system characterization problem, in this inverse problem the contaminant signals at monitoring wells are recorded to recreate the pollution profiles. In this study, simulation-optimization approach is a technique utilized to solve inverse problems by formulating them as an optimization model, where evolutionary algorithms are used to perform the search. In this approach, the PDE groundwater transport simulation model (simulation model) is solved iteratively during the evolutionary search, which in general can be computationally expensive. To overcome this limitation, high performance computing and grid computing are used to improve the simulation model efficiency. The parallel PDE groundwater transport simulation model is then coupled with an evolutionary computation search procedure to solve two instances of groundwater inverse problems. The results demonstrate the performance of the grid-enabled simulation-optimization approach in terms of solution quality and computational performance. C2 - 2007/5/11/ C3 - World Environmental and Water Resources Congress 2007 DA - 2007/5/11/ DO - 10.1061/40927(243)160 PB - American Society of Civil Engineers SN - 9780784409275 UR - http://dx.doi.org/10.1061/40927(243)160 DB - Crossref ER - TY - CONF TI - Modeling organics degradation with the UV/H2O2 advanced oxidation process using computational fluid dynamics AU - Alpert, S.M. AU - Ducoste, J.J. C2 - 2007/// C3 - American Water Works Association - Water Quality Technology Conference and Exposition 2007: Fast Tracks to Water Quality DA - 2007/// SP - 3077-3093 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84871548365&partnerID=MN8TOARS ER - TY - CONF TI - Incorporation of micromixing models within CFD simulations describing UV-initiated advanced oxidation processes AU - Alpert, S.M. AU - Knappe, D. AU - Ducoste, J. C2 - 2007/// C3 - American Water Works Association - AWWA Annual Conference and Exposition, ACE 2007 DA - 2007/// SP - 388-401 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84871662252&partnerID=MN8TOARS ER - TY - CONF TI - Evaluating sequential disinfection in continuous flow water treatment systems AU - Richards, B.H. AU - Ducoste, J.J. C2 - 2007/// C3 - American Water Works Association - Water Quality Technology Conference and Exposition 2007: Fast Tracks to Water Quality DA - 2007/// SP - 2074-2081 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84871574021&partnerID=MN8TOARS ER - TY - CONF TI - Spatial and temporal analysis of real-world empirical fuel use and emissions AU - Frey, H.C. AU - Zhang, K. C2 - 2007/// C3 - 100th Annual Conference and Exhibition of the Air and Waste Management Association 2007, ACE 2007 DA - 2007/// VL - 3 SP - 2097-2102 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-44649198655&partnerID=MN8TOARS ER - TY - JOUR TI - Potential best practices for reducing greenhouse gas (GHG) emissions in freight transportation AU - Frey, H.C. AU - Kuo, P.-Y. T2 - Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA DA - 2007/// PY - 2007/// VL - 5 SP - 3099-3103 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-44649095696&partnerID=MN8TOARS ER - TY - JOUR TI - Methodology for activity, fuel use, and emissions data collection and analysis for nonroad construction equipment AU - Frey, H.C. AU - Rasdorf, W. AU - Pang, S.-H. AU - Kim, K. AU - Abolhasani, S. AU - Lewis, P. T2 - Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA DA - 2007/// PY - 2007/// VL - 5 SP - 3124-3128 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-44649103903&partnerID=MN8TOARS ER - TY - JOUR TI - Fuel consumption and emissions comparisons between ethanol 85 and gasoline fuels for flexible fuel vehicles AU - Zhai, H. AU - Frey, H.C. AU - Rouphail, N.M. AU - Gonçalves, G.A. AU - Farias, T.L. T2 - Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA DA - 2007/// PY - 2007/// VL - 5 SP - 3104-3108 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-44649111256&partnerID=MN8TOARS ER - TY - JOUR TI - Development of quantitative real-time PCR assays for detection and quantification of surrogate biological warfare agents in building debris and leachate. AU - Saikaly, P. E. AU - Barlaz, M. A. AU - Los Reyes, F. L. T2 - Appl Environ Microbiol DA - 2007/// PY - 2007/// DO - AEM.00779-07 [pii] 10.1128/AEM.00779-07 VL - 73 IS - 20 SP - 6557-65 ER - TY - CONF TI - Moment transfer in bearing supported Bridges AU - Vidot?Vega, A. L. AU - Possiel, B. AU - Robinson, B. AU - Kowalsky, M. AU - Gabr, M. A. C2 - 2007/// C3 - 2007 PCI-FHWA National Bridge Conference, AZ, October 2007 DA - 2007/// ER - TY - CONF TI - Limit Equilibrium and Deformation Analyses of a Geogrid-Reinforced Embankment AU - Park, Young Jin AU - Gabr, Mohammed A. AU - Borden, Roy H. AU - Kim, Kyung Jun AU - Kreider, Christopher A. AB - Limit equilibrium analyses and 2-dimensional numerical simulations are performed to estimate the performance of a geosynthetic-reinforced embankment supporting a bridge abutment. Geogrid reinforcement was evaluated as a means of improving the stability of the embankment slope and reducing deformation under design loads. Results indicated a reduction in total and differential deformation due to the inclusion of reinforcement. The deformation of the embankment slope was correlated to the global factor of safety. Vertical and lateral movements for the reinforced case were computed to be 65% and 78%, respectively, of those of the unreinforced embankment case. The load carrying capacity of the reinforced embankment was estimated to be 5 times larger than the unreinforced case while providing the same limit equilibrium factor of safety. C2 - 2007/10// C3 - Geosynthetics in Reinforcement and Hydraulic Applications DA - 2007/10// DO - 10.1061/40909(228)17 VL - 165 PB - American Society of Civil Engineers (ASCE) ER - TY - CONF TI - Laboratory Characterization of Jetting-Induced Disturbance Zones AU - Gabr, Mohammed A. AU - Borden, Roy H. AU - Smith, Alex W. AU - Denton, Raymond L. AB - A laboratory study is performed to develop a model for evaluating the extent of the disturbance zone created by the pile jetting process. The physical phenomenon of jetting was observed in three different sands. Observations indicated that installation of piles by jetting is from the simultaneous erosion of sand beneath the pile tip and transport of soil particles through an annulus created around the circumference of the pile up to the ground surface. The pile advances only after a sufficient area has been eroded beneath the tip to cause a bearing capacity failure, as side friction is reduced due to the return water and liquefaction of sand within the annulus. Given equal jetting parameters, the extent of the debris zone from the pile center was approximately 100% further for sand with smaller average particle sizes (D50 = 0.15 mm) than for sand with larger average particle size (D50 = 0.5 mm). An empirical model to provide dimensional characteristics of the disturbance zone is proposed based on data from the laboratory study. Further research into the effect of jetting and water currents on disturbance zone is warranted including monitoring of field installations to verify the proposed model. C2 - 2007/10// C3 - Soil Improvement DA - 2007/10// DO - 10.1061/40916(235)15 VL - 172 PB - American Society of Civil Engineers (ASCE) ER - TY - CONF TI - A Point of Fixity Model for Pile and Shaft Bents AU - Robinson, Brent AU - Suarez, Vinicio AU - Robalino, Pablo AU - Kowalsky, Mervyn AU - Gabr, Mohammed T2 - Geo-Denver 2007 AB - Pile bents are often used in bridge foundation systems. These sub-structural elements are constructed by installing a row of piles and connecting them with a concrete cap. A common design practice is to use a point of fixity approach which idealizes the soil-pile system as a cantilever of a particular length, forming a single column in an elastic frame. In this paper, current design practices are reviewed, and a new method for calculating point of fixity is developed for engineers who must consider separate single pile lateral analyses and elastic frame analyses. The proposed approach better matches the maximum moments and displacements obtained from non-linear analysis for a pile in the foundation system that is subjected to the lateral loading applied to the bridge. An example that compares a pile bent designed as an equivalent elastic frame with a nonlinear analysis is presented. Comparative results show the elastic frame model with two equivalent lengths (based on transverse and longitudinal loading conditions) satisfactorily matches results from nonlinear analysis, while a frame with a single point of fixity, based on deepest equivalent length, provides a conservative approximation of the nonlinear model. C2 - 2007/10/14/ C3 - Contemporary Issues In Deep Foundations DA - 2007/10/14/ DO - 10.1061/40902(221)16 VL - 158 PB - American Society of Civil Engineers SN - 9780784409022 UR - http://dx.doi.org/10.1061/40902(221)16 DB - Crossref ER - TY - BOOK TI - Displacement-based seismic design of structures AU - M.J.N. Priestley, G.M. Calvi AU - Kowalsky, M.J. AB - As stated in the front piece, ‘This book is primarily directed to practicing structural designers…. The information provided in this book will be of value, not just to designers using displacement-based principles, but also to those using more conventional force-based design, who wish to understand the seismic response of structures in more detail, and to apply this understanding to design’. The book starts with a consideration in Chapter 1 as to why it is necessary to move from force-based to displacement-based seismic design. This is largely related to the guesses of initial stiffness necessary in force-based design, and the inadvisability of using these initial stiffness values to distribute seismic lateral force through the structure. Chapter 2 provides a state-of-the-science input for displacement-based design, particularly related to characteristics of elastic and inelastic displacement spectra. The fundamental concepts behind ‘direct displacement-based seismic design’—so-called because no iteration is required in the design process—are developed in Chapter 3. Analytical tools especially relevant to displacement-based design are discussed in Chapter 4. The principles of displacement-based design are then applied to different structural systems (frames, wells, dual wall/frames, masonry, timber buildings, bridges, structures with seismic isolation and added damping, and wharves) in the following chapters and are subsequently adapted to seismic assessment in Chapter 13. Finally, the principles are presented in Chapter 14 in a code format to provide a possible basis for future codification. The text is illustrated by design examples throughout. Chapter titles are as follows: \documentclass{article} \footskip=0pc \pagestyle{empty} \begin{document} \begin{tabular}{ll} Chapter 1: & Introduction: The Need for Displacement-Based Seismic Design\\ Chapter 2: & Seismic Input for Displacement-Based Design\\ Chapter 3: & Direct Displacement-Based Design: Fundamental Considerations\\ Chapter 4: & Analysis Tools for Direct Displacement-Based Design\\ Chapter 5: & Frame Buildings\\ Chapter 6: & Structural Wall Buildings\\ Chapter 7: & Dual Wall--Frame Buildings\\ Chapter 8: & Masonry Buildings\\ Chapter 9: & Timber Structures\\ Chapter 10: & Bridges\\ Chapter 11: & Structures with Isolation and Added Damping\\ Chapter 12: & Wharves and Piers\\ Chapter 13: & Displacement-Based Seismic Assessment\\ Chapter 14: & Draft Displacement-Based Code for Seismic Design of Buildings \end{tabular} \end{document} DA - 2007/// PY - 2007/// DO - 10.1002/eqe.807 PB - Pavia, Italy: IUSS Press: Distributed by Fondazione EUCENTRE ER - TY - RPRT TI - Life cycle inventory and impact analysis framework for nonroad construction vehicles and equipment based upon in-use measurements AU - Frey, H. C. AU - Rasdorf, W. AU - Kim, K. AU - Pang, S.-H. AU - Lewis, P. AU - Abolhassani, S. A3 - Raleigh, N.C.: National Science Foundation DA - 2007/// PY - 2007/// PB - Raleigh, N.C.: National Science Foundation ER - TY - JOUR TI - Early warning system to identify poor time management habits AU - Bernold, L. E. T2 - International Journal of Engineering Education DA - 2007/// PY - 2007/// VL - 23 IS - 6 SP - 1182-1191 ER - TY - JOUR TI - STATISTICAL VALIDATION OF THE EFFECT OF LATERAL LINE LOCATION ON PAVEMENT MARKING RETROREFLECTIVITY DEGRADATION AU - Craig, W. Neil, III AU - Sitzabee, William E. AU - Rasdorf, William J. AU - Hummer, Joseph E. T2 - PUBLIC WORKS MANAGEMENT & POLICY AB - This article examines the effect of lateral location on the degradation of retroreflectivity in thermoplastic pavement-marking systems. The authors examined data collected on North Carolina roads over a 5-year period and conducted a statistical analysis to determine if there was a significant difference in the rates of retroreflectivity degradation between edge lines and center lines. The study concluded that there was statistical evidence that lateral line location does have an effect on retroreflectivity degradation and that center lines degrade faster than edge lines. Understanding retroreflectivity performance over time facilitates the development and implementation of guidelines and tools that can be used for holistic asset management. Based on their findings, the authors recommend changes in pavement-marking maintenance strategies. DA - 2007/10// PY - 2007/10// DO - 10.1177/1087724x07308773 VL - 12 IS - 2 SP - 431-450 SN - 1552-7549 KW - pavement markings KW - retroreflectivity KW - degradation rates KW - management ER - TY - JOUR TI - FIELD INVESTIGATION OF HIGHWAY SIGN DAMAGE RATES AND INSPECTOR ACCURACY AU - Immaneni, Venkata Pavan K. AU - Rasdorf, William J. AU - Hummer, Joseph E. AU - Yeom, Chunho T2 - PUBLIC WORKS MANAGEMENT & POLICY AB - This study sought to create a simulation model to provide the North Carolina Department of Transportation (NCDOT) with recommendations to improve its sign inspection and replacement procedures. This research focuses on two key factors built into the model: (a) the rate at which signs are damaged beyond usefulness based on natural or man-made causes and (b) the accuracy rate of visual sign inspections based on retroreflectivity. The research team conducted nighttime rides with sign inspectors in 5 of 14 NCDOT divisions. During subsequent daytime rides, the team measured sign retroreflectivity to allow estimation of sign deterioration and inspector accuracy rates. Data were collected for white, yellow, red, and green signs and for sheeting Types I and III. About 2.3% of inspected signs (per year) were damaged to the point of needing replacement, and inspectors did not reject a large percentage of signs that had retroreflectivity values below the proposed minimum Federal Highway Administration standard. DA - 2007/4// PY - 2007/4// DO - 10.1177/1087724x07299882 VL - 11 IS - 4 SP - 266-278 SN - 1552-7549 KW - sign KW - retrorefiectivity KW - inspect KW - damage KW - vandalism KW - inspector performance ER - TY - JOUR TI - Approach to determine extent and depth of highway flooding AU - Cai, H. AU - Rasdorf, W. AU - Tilley, C. T2 - Journal of Infrastructure Systems AB - Flooding and flash flooding pose serious infrastructure hazards to human populations in many parts of the world. During a flood, it is critical to identify road segments that are flooded so that rescue and response routes can be determined and rescue personnel and supplies can be distributed promptly. Presently there is not an information system that, given a specific flood level, can accurately predict flooded road segments and their depth and provide this information for rescue activities. This paper reports on a study to develop a prediction prototype to identify flooded road segments during a flood. It includes two tasks: determining flood extent and depth and identifying road segments that are flooded. Unlike a traditional approach, which determines flood extent and depth by comparing a water surface and a terrain surface, this study determines flood extent and depth using light detection and ranging data in a geographic information system. This flood extent and depth information is integrated with 3D road centerline data created in a related study. It is believed that the proposed prediction model and algorithms in this study can provide a practical and efficient approach to identify road segments that are flooded in a timely manner to help determine rescue routes. These models show promise. Additional research is required to fully validate the models. DA - 2007/// PY - 2007/// DO - 10.1061/(asce)1076-0342(2007)13:2(157) VL - 13 IS - 2 SP - 157-167 ER - TY - CONF TI - Methods for measurement and analysis of in-use emissions of nonroad construction equipment AU - Frey, H. C. AU - Rasdorf, W. AU - Pang, S. AU - Kim, K. AU - Lewis, P. C2 - 2007/// C3 - Proceedings of the EPA Emissions Inventory Conference DA - 2007/// PB - Raleigh, NC: EPA ER - TY - CONF TI - Methodology for activity, fuel use, and emissions data collection and analysis for nonroad construction equipment AU - Frey, H. C. AU - Rasdorf, W. AU - Pang, S. H. AU - Kim, K. AU - Abolhasani, S. AU - Lewis, P. C2 - 2007/// C3 - Proceedings of the Air and Waste Management Association Annual Conference DA - 2007/// PB - Pittsburgh, PA: AWMA ER - TY - CONF TI - IT infrastructure problems for asset management AU - Rasdorf, W. AU - Hummer, J. AU - Harris, E. A2 - L. Soibelman, B. Akinci A2 - Shon, H. AB - Transportation infrastructure asset management efforts normally focus on collecting data on items with low volumes and higher capital costs, such as bridges. Road signs and pavement markings, on the other hand, are high volume, low capital cost items but are critical elements of the transportation infrastructure. These high volume assets serve a critical function, safety, and thus they are receiving attention. In particular, the Federal Highway Administration (FHWA) has been working to establish minimum retroreflectivity standards for signs and pavement markings. This paper seeks to address information technology (IT) problems that emerge when developing an overall asset management system for high volume assets and to identify their unique characteristics. These IT problems include asset identification, asset location, data availability, data fragmentation, automated data collection, software selection, and system size and resources. A discussion of the issues related to these problems is presented herein to facilitate the development of more comprehensive systems to manage the automation of infrastructure asset management systems (AMS). C2 - 2007/// C3 - Computing in civil engineering: Proceedings of the 2007 ASCE International Workshop on Computing in Civil Engineering, July 24-27, 2007, Pittsburgh, Pennsylvania DA - 2007/// DO - 10.1061/40937(261)10 PB - Reston, VA: American Society of Civil Engineers SN - 0784409374 ER - TY - JOUR TI - Normal modes of a rectangular tank with corrugated bottom AU - Howard, Louis N. AU - Yu, Jie T2 - JOURNAL OF FLUID MECHANICS AB - We study some effects of regular bottom corrugations on water waves in a long rectangular tank with vertical endwalls and open top. In particular, we consider motions which are normal modes of oscillation in such a tank. Attention is focused on the modes whose internodal spacing, in the absence of corrugations, would be near the wavelength of the corrugations. In these cases, the perturbation of the eigenfunctions (though not of their frequencies) can be significant, e.g. the amplitude of the eigenfunction can be greater by a factor of ten or more near one end of the tank than at the other end. This is due to a cooperative effect of the corrugations, called Bragg resonance. We first study these effects using an asymptotic theory, which assumes that the bottom corrugations are of small amplitude and that the motions are slowly varying everywhere. We then present an exact theory, utilizing continued fractions. This allows us to deal with the rapidly varying components of the flow. The exact theory confirms the essential correctness of the asymptotic results for the slowly varying aspects of the motions. The rapidly varying parts (evanescent waves) are, however, needed to satisfy accurately the true boundary conditions, hence of importance to the flow near the endwalls. DA - 2007/12/25/ PY - 2007/12/25/ DO - 10.1017/S0022112007008695 VL - 593 SP - 209-234 SN - 0022-1120 ER - TY - JOUR TI - Adoption patterns of advanced information technologies in the construction industries of the United States and Korea AU - Williams, T. AU - Bernold, L. AU - Lu, H. Q. T2 - Journal of Construction Engineering and Management AB - The results of a survey conducted by the ASCE Wireless Construction Committee are presented. The goal of the effort is to better understand how much construction contractors have advanced in adopting information technologies in general and wireless communications in particular. Responses were collected from 152 U.S. and 31 Korean firms. It was found that, overall, the strongest interest among the responding contractors is in document and content management applications. Differences between Korean and U.S. contractors are discussed. The data indicate that the use of information technology by contractors is generally higher in Korea than in the United States. Both practitioners and scientists will be able to use the presented study because the data reveal the managers’ perceptions of the most promising opportunities for and highest barriers to implementation of advanced communication systems in construction. With the information provided, interested readers of this journal will be able to focus their attention on pursuing specific opportunities and removing barriers to future adoptions. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)0733-9364(2007)133:10(780) VL - 133 IS - 10 SP - 780-790 ER - TY - JOUR TI - A novel optimization approach for minimum cost design of trusses AU - Kripakaran, Prakash AU - Gupta, Abhinav AU - Baugh, John W., Jr. T2 - COMPUTERS & STRUCTURES AB - This paper describes new optimization strategies that offer significant improvements in performance over existing methods for bridge-truss design. In this study, a real-world cost function that consists of costs on the weight of the truss and the number of products in the design is considered. We propose a new sizing approach that involves two algorithms applied in sequence – (1) a novel approach to generate a “good” initial solution and (2) a local search that attempts to generate the optimal solution by starting with the final solution from the previous algorithm. A clustering technique, which identifies members that are likely to have the same product type, is used with cost functions that consider a cost on the number of products. The proposed approach gives solutions that are much lower in cost compared to those generated in a comprehensive study of the same problem using genetic algorithms (GA). Also, the number of evaluations needed to arrive at the optimal solution is an order of magnitude lower than that needed in GAs. Since existing optimization techniques use cost functions like those of minimum-weight truss problems to illustrate their performance, the proposed approach is also applied to the same examples in order to compare its relative performance. The proposed approach is shown to generate solutions of not only better quality but also much more efficiently. To highlight the use of this sizing approach in a broader optimization framework, a simple geometry optimization algorithm that uses the sizing approach is presented. This algorithm is also shown to provide solutions better than the existing results in literature. DA - 2007/12// PY - 2007/12// DO - 10.1016/j.compstruc.2007.04.006 VL - 85 IS - 23-24 SP - 1782-1794 SN - 1879-2243 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-36049020582&partnerID=MN8TOARS KW - truss design KW - structural optimization KW - hybrid search KW - genetic algorithms KW - member grouping KW - discrete sizing optimization KW - cost minimization ER - TY - JOUR TI - Parallel Performance Modeling using a Genetic Programming-based Error Correction Procedure AU - Raghavachar, Kavitha AU - Mahinthakumar, G. AU - Worley, Patrick AU - Zechman, Emily AU - Ranjithan, Ranji T2 - SIMULATION AB - Performance models of high performance computing (HPC) applications are important for several reasons. First, they provide insight to designers of HPC systems on the role of subsystems such as the processor or the network in determining application performance. Second, they allow HPC centers more accurately to target procurements to resource requirements. Third, they can be used to identify application performance bottlenecks and to provide insights about scalability issues. The suitability of a performance model, however, for a particular performance investigation is a function of both the accuracy and the cost of the model. A semi-empirical model previously published by the authors for an astrophysics application was shown to be inaccurate when predicting communication cost for large numbers of processors. It is hypothesized that this deficiency is due to the inability of the model adequately to capture communication contention (threshold effects) as well as other unmodeled components such as noise and I/O contention. In this paper we present a new approach to capture these unknown features to improve the predictive capabilities of the model. This approach uses a systematic model error-correction procedure that uses evolutionary algorithms to find an error correction term to augment the eXisting model. Four variations of this procedure were investigated and all were shown to produce better results than the original model. Successful cross-platform application of this approach showed that it adequately captures machine dependent characteristics. This approach was then successfully demonstrated for a second application, further showing its versatility. DA - 2007/7// PY - 2007/7// DO - 10.1177/0037549707084691 VL - 83 IS - 7 SP - 515-527 J2 - SIMULATION LA - en OP - SN - 0037-5497 1741-3133 UR - http://dx.doi.org/10.1177/0037549707084691 DB - Crossref KW - error correction procedure KW - genetic programming KW - performance modeling ER - TY - JOUR TI - Field P-y curves in weathered rock AU - Cho, Kook Hwan AU - Gabr, Mohammed A. AU - Clark, Shane AU - Borden, Roy H. T2 - CANADIAN GEOTECHNICAL JOURNAL AB - In weathered and decomposed rock profiles, the lack of an acceptable analysis procedure for estimating lateral load–displacement response of drilled shafts is compounded by the unavailability of weathered material properties, including the material's lateral subgrade reaction modulus. Such deficiency often leads to the overdesign of the drilled shaft foundation. Six field tests were conducted on drilled shafts to investigate the shape and magnitude of P–y curves in weathered rock material at three locations in North Carolina. The tested shafts were instrumented using dial gages, strain gages, and continuous vertical inclinometers. The measured load versus deflection data are used to study the stiffness response of weathered rock. Measured lateral responses are compared with the results estimated based on a "weak rock" model and a stiff clay model. The comparison shows that Reese's weak rock model overestimated the resistances of the tested shafts while the stiff clay model consistently underestimated the measured shaft resistances. The measured and computed results are analyzed and discussed.Key words: drilled shaft, weathered rock P–y curve, subgrade modulus, ultimate resistances in weathered rock, verification tests. DA - 2007/7// PY - 2007/7// DO - 10.1139/t07-026 VL - 44 IS - 7 SP - 753-764 SN - 0008-3674 KW - drilled shaft KW - weathered rock P-y curve KW - subgrade modulus KW - ultimate resistances in weathered rock KW - verification tests ER - TY - JOUR TI - Closure to "optimal design of redundant water distribution networks using a cluster of workstations" by Sujay V. Kumar, Troy A. Doby, John W. Baugh Jr., E. Downey Brill, and S. Ranji Ranjithan AU - Kumar, S. V. AU - Doby, T. A. AU - Baugh, J. W. AU - Brill, E. D. AU - Ranjithan, S. R. T2 - Journal of Water Resources Planning and Management DA - 2007/// PY - 2007/// DO - 10.1061/(asce)0733-9496(2007)133:6(580) VL - 133 IS - 6 SP - 580-581 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-36349011269&partnerID=MN8TOARS ER - TY - JOUR TI - A numerical view into direct shear specimen size effects AU - Jacobson, D. E. AU - Valdes, J. R. AU - Evans, T. M. T2 - Geotechnical Testing Journal DA - 2007/// PY - 2007/// VL - 30 IS - 6 SP - 512-516 ER - TY - JOUR TI - Quantitative assessment of backhoe operator skill AU - Bernold, L. E. T2 - Journal of Construction Engineering and Management AB - The safe and efficient operation of large equipment depends heavily on the skill of the operator. However, very little is known about how to evaluate what makes an operator safe and productive. This paper presents a quantitative approach for assessing the performance of backhoe operators. The approach takes advantage of electronic sensors that are built into a backhoe simulator providing data from both the operator controls and the backhoe arm itself. After a brief review of principles related to learning motor skills the paper describes a newly established backhoe simulator facility and reports about a series of experiments conducted to investigate the efficacy of measuring and comparing the performance of a backhoe operators. Several trained operators with differing work experiences participated in the study. The relevance of this work is in that the collected and analyzed data backs the well-documented correlations linking work experience with skill. It is believed that the utilization of quantitative skill metrics will lead to drastic improvements in the safety and productivity of large equipment. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)0733-9364(2007)133:11(889) VL - 133 IS - 11 SP - 889-899 ER - TY - JOUR TI - Predicting the resilient modulus of asphalt concrete from the dynamic modulus AU - Lacroix, Andrew AU - Khandan, A. Ardalan Mosavi AU - Kim, Y. Richard T2 - TRANSPORTATION RESEARCH RECORD AB - The NCHRP 1-37A Guide for Mechanistic-Empirical Design of New and Rehabilitated Design Structures introduces the dynamic modulus as the material property to characterize asphalt concrete. This is a significant change from the resilient modulus used in the previous AASHTO pavement design guide. This paper presents an analytical method of calculating the resilient modulus from the dynamic modulus. It involves the application of multiaxial linear viscoelastic theory to linear elastic solutions for the indirect tension test developed by Hondros. The prediction method is verified by using three 12.5-mm surface course mixtures with different aggregate shapes and binder types and one 25.0-mm base mixture. Results show that the predicted and measured resilient modulus values are in close agreement. The results provide a forward model for the potential back-calculation of the dynamic modulus from resilient modulus databases already available in highway agencies, such as the Long-Term Pavement Performance Materials Database. DA - 2007/// PY - 2007/// DO - 10.3141/2001-15 IS - 2001 SP - 132-140 SN - 0361-1981 ER - TY - JOUR TI - Manual traffic allocation for small-town networks AU - Han, Y. AU - Stone, J. R. AU - Huntsinger, L. F. T2 - Transportation Research Record DA - 2007/// PY - 2007/// IS - 1997 SP - 24-34 ER - TY - JOUR TI - Laboratory simulation of impact loading on laminated glass for ice hockey arenas AU - Fam, A. AU - Rizkalla, S. T2 - EXPERIMENTAL TECHNIQUES DA - 2007/// PY - 2007/// DO - 10.1111/j.1747-1567.2007.00181.x VL - 31 IS - 5 SP - 46-52 SN - 0732-8818 ER - TY - JOUR TI - Global-local assessment of low-velocity impact damage in woven composites AU - Pearson, J. D. AU - Zikry, M. A. AU - Prabhugoud, M. AU - Peters, K. T2 - JOURNAL OF COMPOSITE MATERIALS AB - Global measurements from low-velocity impact experiments and local strain measurements from embedded and surface mounted optical fiber Bragg grating (FBG) sensors were used to obtain failure maps for two- and three dimensional woven composites. These maps delineated five distinct regimes spanning behavior from initial impact to complete penetration. Sensor and host damage were separated by signal intensity and the evolution of Bragg peaks due to repeated impact loads. The results indicate that a local-global framework can be used to monitor damage progression in different host materials, and hence it can be potentially used to mitigate damage. DA - 2007/12// PY - 2007/12// DO - 10.1177/0021998307078734 VL - 41 IS - 23 SP - 2759-2783 SN - 1530-793X KW - woven composite KW - low-velocity impact KW - FBG KW - local strains ER - TY - PCOMM TI - Galvanic corrosion rare with proper detailing AU - Dawood, M. AU - Rizkalla, S. AU - Gleich, H. DA - 2007/// PY - 2007/// SP - 27-29 ER - TY - JOUR TI - Fatigue and overloading Behavior of steel-concrete composite flexural members strengthened with high modulus CFRP materials AU - Dawood, M. AU - Rizkalla, S. AU - Sumner, E. T2 - Journal of Composites for Construction AB - Due to corrosion and the continuous demand to increase traffic loads, there is a need for an effective system which can be used to repair and/or strengthen steel bridges and structures. This paper describes an experimental program, recently completed, to investigate the fundamental behavior of steel–concrete composite scaled bridge beams strengthened with new high modulus carbon fiber-reinforced polymer (HM CFRP) materials. The behavior of the beams under overloading conditions and fatigue loading conditions was studied as well as the possible presence of shear lag at the interface of the steel surface and the CFRP strengthening material. The test results are compared to an analytical model based on the fundamental principles of equilibrium and compatibility, to predict the behavior of the strengthened steel–concrete composite beams. Based on the findings of this research work, combined with other work in the literature, a design guideline is proposed for the use of HM CFRP for strengthening the steel flexural members typically used for bridges and structures. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)1090-0268(2007)11:6(659) VL - 11 IS - 6 SP - 659-669 ER - TY - JOUR TI - Development of quantitative real-time PCR assays for detection and quantification of surrogate biological warfare agents in building debris and leachate AU - Saikaly, Pascal E. AU - Barlaz, Morton A. AU - Reyes, Francis L., III T2 - APPLIED AND ENVIRONMENTAL MICROBIOLOGY AB - ABSTRACT Evaluation of the fate and transport of biological warfare (BW) agents in landfills requires the development of specific and sensitive detection assays. The objective of the current study was to develop and validate SYBR green quantitative real-time PCR (Q-PCR) assays for the specific detection and quantification of surrogate BW agents in synthetic building debris (SBD) and leachate. Bacillus atrophaeus (vegetative cells and spores) and Serratia marcescens were used as surrogates for Bacillus anthracis (anthrax) and Yersinia pestis (plague), respectively. The targets for SYBR green Q-PCR assays were the 16S-23S rRNA intergenic transcribed spacer (ITS) region and recA gene for B. atrophaeus and the gyrB , wzm , and recA genes for S. marcescens . All assays showed high specificity when tested against 5 ng of closely related Bacillus and Serratia nontarget DNA from 21 organisms. Several spore lysis methods that include a combination of one or more of freeze-thaw cycles, chemical lysis, hot detergent treatment, bead beat homogenization, and sonication were evaluated. All methods tested showed similar threshold cycle values. The limit of detection of the developed Q-PCR assays was determined using DNA extracted from a pure bacterial culture and DNA extracted from sterile water, leachate, and SBD samples spiked with increasing quantities of surrogates. The limit of detection for B. atrophaeus genomic DNA using the ITS and B. atrophaeus recA Q-PCR assays was 7.5 fg per PCR. The limits of detection of S. marcescens genomic DNA using the gyrB , wzm , and S. marcescens recA Q-PCR assays were 7.5 fg, 75 fg, and 7.5 fg per PCR, respectively. Quantification of B. atrophaeus vegetative cells and spores was linear ( R 2 > 0.98) over a 7-log-unit dynamic range down to 10 1 B. atrophaeus cells or spores. Quantification of S. marcescens ( R 2 > 0.98) was linear over a 6-log-unit dynamic range down to 10 2 S. marcescens cells. The developed Q-PCR assays are highly specific and sensitive and can be used for monitoring the fate and transport of the BW surrogates B. atrophaeus and S. marcescens in building debris and leachate. DA - 2007/10// PY - 2007/10// DO - 10.1128/AEM.00779-07 VL - 73 IS - 20 SP - 6557-6565 SN - 1098-5336 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-35448953535&partnerID=MN8TOARS ER - TY - JOUR TI - Behaviour of intrinsic polymer optical fibre sensor for large-strain applications AU - Kiesel, Sharon AU - Peters, Kara AU - Hassan, Tasnim AU - Kowalsky, Mervyn T2 - MEASUREMENT SCIENCE AND TECHNOLOGY AB - This paper derives the phase response of a single-mode polymer optical fibre for large-strain applications. The role of the finite deformation of the optical fibre and nonlinear strain optic effects are derived using a second order strain assumption and shown to be important at strain magnitudes as small as 1%. In addition, the role of the core radius change on the propagation constant is derived, but it is shown to be negligible as compared to the previous effects. It is shown that four mechanical and six opto-mechanical parameters must be calibrated to apply the sensor under arbitrary axial and transverse loading. The mechanical nonlinearity of a typical single-mode polymer optical fibre is experimentally measured in axial tension and is shown to be more significant than that of their silica counterpart. The mechanical parameters of the single-mode polymer optical fibre are also measured for a variety of strain rates, from which it is demonstrated that the strain rate has a strong influence on yield stress and strain. The calibrated constants themselves are less affected by strain rate. DA - 2007/10// PY - 2007/10// DO - 10.1088/0957-0233/18/10/S16 VL - 18 IS - 10 SP - 3144-3154 SN - 1361-6501 KW - large strain KW - polymer optical fibre KW - optical fibre sensor ER - TY - JOUR TI - Behavior of a Caisson subjected to a horizontal breaking wave force AU - Tung, C. C. T2 - Journal of Engineering Mechanics AB - In coastal waters, caissons are used as breakwaters. Under the action of breaking waves, some caissons are initiated into motion. This study is concerned with the following questions: For a caisson subjected to a breaking wave force, what are (1) the possible modes of response and (2) the conditions under which a caisson would be initiated into these modes? These questions have not been studied before. The actual response of a caisson that takes place in each mode is not addressed in this study. A caisson is modeled as a free-standing rigid body placed on a frictional base subjected to a concentrated horizontal force of short duration applied on the seaward side face of the caisson. The conditions for initiation of each mode of motion are derived using the three equations of motion of a plane rigid body. The results are given in explicit analytical forms and presented graphically. For simplicity, the effects of water surrounding the caisson are not included. Knowing the magnitude and location of the force, coefficient of friction, and aspect ratio of the body, the modes of motion of the body may be identified easily from the graphs. It is shown that under the action of a force, a body may undergo various types of motion and its behavior is quite different, depending on whether the line of action of the force is applied above or below the center of mass of the body. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)0733-9399(2007)133:12(1302) VL - 133 IS - 12 SP - 1302-1310 ER - TY - JOUR TI - Applications of the wavelet transform in the generation and analysis of spectrum-compatible records AU - Suarez, Luis E. AU - Montejo, Luis A. T2 - STRUCTURAL ENGINEERING AND MECHANICS AB - A wavelet-based procedure to generate artificial accelerograms compatible with a prescribed seismic design spectrum is described. A procedure to perform a baseline correction of the compatible accelerograms is also described. To examine how the frequency content of the modified records evolves with time, they are analyzed in the time and frequency using the wavelet transform. The changes in the strong motion duration and input energy spectrum are also investigated. An alternative way to match the design spectrum, termed the "two-band matching procedure", is proposed with the objective of preserving the non-stationary characteristics of the original record in the modified accelerogram. DA - 2007/9/30/ PY - 2007/9/30/ DO - 10.12989/sem.2007.27.2.173 VL - 27 IS - 2 SP - 173-197 SN - 1598-6217 KW - spectrum compatible accelerograms KW - wavelet transform KW - baseline correction KW - input energy spectrum KW - strong motion duration ER - TY - JOUR TI - Analysis of traffic sign asset management scenarios AU - Harris, Elizabeth Allison AU - Rasdorf, William AU - Hummer, Joseph E. AU - Yeom, Chunho T2 - TRANSPORTATION RESEARCH RECORD AB - Minimum traffic sign retroreflectivity standards proposed for the Manual on Uniform Traffic Control Devices by the FHWA will present numerous management challenges to state and local departments of transportation (DOTs) responsible for traffic sign assets. These DOTs are looking at how to comply with the standard while minimizing sign maintenance costs. This paper presents an analysis of several traffic sign retroreflectivity maintenance methods using a sign asset management simulation based on inspection and sign data gathered in the field. The simulation evaluated 30 sign asset management scenarios in terms of annual maintenance cost per sign and percentage of traffic signs not compliant with the proposed FHWA standard. The simulation results found that, generally, higher costs for sign maintenance resulted in a lower percentage of noncompliant signs. However, for some scenarios using the visual nighttime inspection method, lower percentages of noncompliant signs were found even with relatively low maintenance costs per sign. Increasing the maintenance cost per sign by 10% resulted in an approximately 10% or more reduction in the number of noncompliant signs. It is recommended that DOTs implement a 100% Type III sign replacement policy because Type I signs have a greater life-cycle cost than do Type III signs. DOTs need to allocate an adequate annual budget for sign replacement and should establish their own minimum retroreflectivity standards. The sign asset management simulation developed as part of this study could be modified so that its use could be extended to other DOTs. DA - 2007/// PY - 2007/// DO - 10.3141/1993-02 IS - 1993 SP - 9-15 SN - 0361-1981 ER - TY - JOUR TI - A neural network model for prediction of pile setup AU - Jeon, Jongkoo AU - Rahman, M. Shamimur T2 - TRANSPORTATION RESEARCH RECORD AB - The time-dependent increase in pile capacity after its driving may be significant. A reliable prediction of this increase (setup) may lead to a significant saving in pile design. A neural network model to predict pile setup was developed. A database derived from field tests reported in the literature showing setup of driven piles was compiled, with six variables selected as input parameters: soil type, pile type, pile diameter, pile length, time after pile installation, and initial effective stress at tip. Ultimate pile capacity at beginning of restrike (Q BOR ) is the sum of pile capacity (Q EOD ) at end of drive and increased in capacity (ΔQ BOR ) caused by setup, which in this study is predicted by a backpropagation neural network. The results demonstrate that the neural network model provides a better prediction than predictions by the available empirical methods. A neural network model can serve as a reliable tool for the prediction of pile setup, and further training with additional data will lead to additional improvement in the quality of prediction. DA - 2007/// PY - 2007/// DO - 10.3141/2004-02 IS - 2004 SP - 12-19 SN - 2169-4052 ER - TY - JOUR TI - Understanding our students: A longitudinal-study of success and failure in engineering with implications for increased retention AU - Bernold, Leonhard E. AU - Spurlin, Joni E. AU - Anson, Chris M. T2 - JOURNAL OF ENGINEERING EDUCATION AB - Abstract In spite of considerable research about the poor retention rate of undergraduate engineering students, we still have an inadequate understanding of the factors that affect students' decisions to remain in engineering programs and their ability to perform well enough to be retained. Although continued study is needed of external factors such as curricular requirements, admissions criteria, and test scores, we also need to know much more about the relationships between curricular experiences and students' learning styles, habits, and attitudes. The work presented in this paper was designed to enhance educators' understanding of the factors that underlie the concern about student retention in engineering. By observing 1,000 engineering students during their first three years in college, the research team generated a large database on the students' academic and non‐academic characteristics as well as their successes and failures. The traits discovered not only support many findings from previous studies but also reveal some new relationships that could prove essential to designing an educational environment that will prepare engineers for success in the future. DA - 2007/7// PY - 2007/7// DO - 10.1002/j.2168-9830.2007.tb00935.x VL - 96 IS - 3 SP - 263-274 SN - 2168-9830 KW - retention KW - gender KW - underrepresented minorities ER - TY - JOUR TI - Natural treatment and onsite processes AU - Liehr, S. K. AU - Kruzic, A. T2 - Water Environment Research DA - 2007/// PY - 2007/// VL - 79 IS - 10 SP - 1451-1473 ER - TY - JOUR TI - GRID-enabled solution of groundwater inverse problems on the TeraGrid network AU - Sayeed, Mohamed AU - Mahinthakumar, Kumar AU - Karonis, Nicholas T. T2 - SIMULATION-TRANSACTIONS OF THE SOCIETY FOR MODELING AND SIMULATION INTERNATIONAL AB - Grid-computing environments are becoming increasingly popular for scientific computing due to the significant increase in capacity that they represent when compared to a single computational resource (e.g., a single cluster), their ubiquitous availability and advances in grid middleware components. Several such specialized grid environments are now available for users in the commercial and research sectors. One such effort for research is the TeraGrid, consisting of a collection of geographically distributed heterogeneous supercomputer resources including data storage resources. Parallel implementations for these environments are inherently multilevel and obtaining efficient mapping of work to processors can be eXtremely challenging. This paper eXtends an eXisting MPI application to the grid via the use of grid-enabled MPI libraries. The application uses a simulation-optimization framework involving coarse-grained parallelism in the optimizer and fine-grained parallelism in the finite-element-based simulator. Using parallelism at both these levels is essential for problems involving computationally intensive simulation steps. A hierarchical grid architecture consisting of a collection of supercomputers is ideally suited for these types of problems as a good application-to-architecture mapping can be obtained with a proper implementation. This paper presents the performance results of our implementation on the TeraGrid network consisting of three geographically distributed supercomputers. DA - 2007/6// PY - 2007/6// DO - 10.1177/0037549707084936 VL - 83 IS - 6 SP - 437-448 SN - 0037-5497 KW - high performance computing KW - grid computing KW - inverse problems KW - optimization KW - ground-water KW - genetic algorithms KW - finite element methods KW - TeraGrid ER - TY - JOUR TI - Effective distribution of emulsified edible oil for enhanced anaerobic bioremediation AU - Borden, R. C. T2 - Journal of Contaminant Hydrology DA - 2007/// PY - 2007/// DO - 10.1016/jjconhyd.2007.06.001 VL - 94 IS - 1-2 SP - 1-12 ER - TY - JOUR TI - Concurrent bioremediation of perchlorate and 1,1,1-trichloroethane in an emulsified oil barrier AU - Borden, Robert C. T2 - JOURNAL OF CONTAMINANT HYDROLOGY AB - A detailed field pilot test was conducted to evaluate the use of edible oil emulsions for enhanced in situ biodegradation of perchlorate and chlorinated solvents in groundwater. Edible oil substrate (EOS®) was injected into a line of ten direct push injection wells over a 2-day period to form a 15-m-long biologically active permeable reactive barrier (bio-barrier). Field monitoring results over a 2.5-year period indicate the oil injection generated strongly reducing conditions in the oil-treated zone with depletion of dissolved oxygen, nitrate, and sulfate, and increases in dissolved iron, manganese and methane. Perchlorate was degraded from 3100 to 20,000 μg/L to below detection (< 4 μg/L) in the injection and nearby monitor wells within 5 days following the injection. Two years after the single emulsion injection, perchlorate was less than 6 μg/L in every downgradient well compared to an average upgradient concentration of 13,100 μg/L. Immediately after emulsion injection, there were large shifts in concentrations of chlorinated solvents and degradation products due to injection of clean water, sorption to the oil and adaptation of the in situ microbial community. Approximately 4 months after emulsion injection, concentrations of 1,1,1-trichloroethane (TCA), perchloroethene (PCE), trichloroethene (TCE) and their degradation products appeared to reach a quasi steady-state condition. During the period from 4 to 18 months, TCA was reduced from 30–70 μM to 0.2–4 μM during passage through the bio-barrier. However, 1–9 μM 1,1-dichloroethane (DCA) and 8–14 μM of chloroethane (CA) remained indicating significant amounts of incompletely degraded TCA were discharging from the oil-treated zone. During this same period, PCE and TCE were reduced with concurrent production of 1,2-cis-dichloroethene (cis-DCE). However, very little VC or ethene was produced indicating reductive dechlorination slowed or stopped at cis-DCE. The incomplete removal of TCA, PCE and TCE is likely associated with the short (5–20 days) hydraulic retention time of contaminants in the oil-treated zone. The permeability of the injection wells declined by 39–91% (average = 68%) presumably due to biomass growth and/or gas production. However, non-reactive tracer tests and detailed monitoring of the perchlorate plume demonstrated that the permeability loss did not result in excessive flow bypassing around the bio-barrier. Contaminant transport and degradation within the bio-barrier was simulated using an advection–dispersion–reaction model where biodegradation rate was assumed to be linearly proportional to the residual oil concentration (Soil) and the contaminant concentration. Using this approach, the calibrated model was able to closely match the observed contaminant distribution. The calibrated model was then used to design a full-scale barrier to treat both ClO4 and chlorinated solvents. DA - 2007/10/30/ PY - 2007/10/30/ DO - 10.1016/j.jconhyd.2007.06.002 VL - 94 IS - 1-2 SP - 13-33 SN - 0169-7722 KW - anaerobic KW - bioremediation KW - edible oil KW - soybean oil KW - emulsion KW - perchlorate KW - trichloroethane ER - TY - JOUR TI - Air void models for the dynamic modulus, fatigue cracking, and rutting of asphalt concrete AU - Seo, Y. G. AU - El-Haggan, O. AU - King, M. AU - Lee, S. J. AU - Kim, Y. R. T2 - Journal of Materials in Civil Engineering AB - A laboratory study has been carried out to develop mechanical models for the dynamic modulus, fatigue life, and rutting performance of asphalt concrete as a function of air void content. The experimental program includes an axial compression complex modulus test, indirect tensile (IDT) fatigue test, and triaxial repeated load permanent deformation (TRLPD) test on the two most commonly used asphalt–aggregate mixtures in North Carolina. The dynamic moduli are determined using axial compression tests with and without confining pressure, and the results are compared to evaluate the effect of confining pressure on the dynamic modulus. The relationship between the dynamic moduli that are determined from the uniaxial compression test and the air void content is developed. The growth of the tensile strain and axial permanent strain is measured from the IDT fatigue test and TRLPD test, respectively, and is used to determine the fatigue life and rutting behavior of the mixtures. The fatigue and rutting models adopted in the new NCHRP 1-37A Mechanistic-Empirical Pavement Design Guide have been refined to represent the IDT and TRLPD test results more accurately and to incorporate the air void content as an input parameter. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)0899-1561(2007)19:10(874) VL - 19 IS - 10 SP - 874-883 ER - TY - JOUR TI - Displacement-based seismic design of drilled shaft bents with soil-structure interaction AU - Suarez, Vinicio AU - Kowalsky, Mervyn J. T2 - JOURNAL OF EARTHQUAKE ENGINEERING AB - The Direct Displacement-Based Design method is implemented for performance based seismic engineering of drilled shaft bents with consideration of soil-structure interaction effects. This was accomplished by defining an equivalent model that allows the prediction of yield displacement, displacement ductility and equivalent viscous damping for the in-plane and out-of-plane response of bents embedded in soft clay and sand. The utilization of the model is simple and requires the input of geometry, basic soil properties, target performance in terms of top displacement, ductility or strain limits and seismic demand in the form of displacement response spectra. Examples are presented to demonstrate the application of the procedure. DA - 2007/11// PY - 2007/11// DO - 10.1080/13632460701232683 VL - 11 IS - 6 SP - 1010-1030 SN - 1363-2469 KW - soil-structure interaction KW - ductility KW - equivalent damping KW - DDBD ER - TY - JOUR TI - Development of crash reduction factors for overhead flashing beacons at rural intersections in North Carolina AU - Murphy, B. G. AU - Hummer, J. E. T2 - Transportation Research Record DA - 2007/// PY - 2007/// IS - 2030 SP - 15-21 ER - TY - JOUR TI - Data collection time intervals for stochastic short-term traffic flow forecasting AU - Guo, Jianhua AU - Williams, Billy AU - Smith, Brian L. T2 - Transportation Research Record AB - The specification of time intervals for data collection is a fundamental determinant of the nature and utility of the resulting traffic condition data streams. In the context of short-term traffic flow forecasting, the establishment of the data collection time interval should play a key role in determining the corresponding appropriate forecasting approach. The data collection time interval provides the forecasting horizon for one-step-ahead forecasting. Nevertheless, the need for more rigorous understanding of the effects of data collection time interval specification within the context of short-term traffic flow forecasting is not well recognized. By contrast, it has been common practice in previous research to select the data collection time interval and forecasting approach without explicit consideration of time interval effects or systematic evaluation of available forecasting methods. A stochastic seasonal autoregressive integrated moving average plus generalized autoregressive conditional heteroscedasticity (SARIMA+GARCH) structure proposed in previous work holds promise in providing accurate point forecasts and reasonable forecasting confidence intervals. In this paper, a spectrum of data collection time intervals is tested with an online forecasting algorithm developed based on the SARIMA+GARCH structure to determine the applicable data collection time intervals for this structure. In this test, both the forecast accuracy and the validity of the forecasting confidence intervals are investigated. This work serves as an important step toward establishing a short-term traffic condition forecasting framework that identifies appropriate forecasting approaches for candidate data collection time intervals based on the functional requirements of specific applications. DA - 2007/// PY - 2007/// DO - 10.3141/2024-03 IS - 2024 SP - 18–26 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-40449106442&partnerID=MN8TOARS ER - TY - JOUR TI - Combination of modal responses: A closed-form formulation for rigid response coefficient AU - Saigal, Rakesh K. AU - Gupta, Abhinav T2 - NUCLEAR ENGINEERING AND DESIGN AB - Recent studies conducted by US Nuclear Regulatory Commission (USNRC) for combining modal responses in a response spectrum method of seismic analysis and design have emphasized that each modal response quantity should be separated into damped-periodic and rigid parts before combining the contributions from different modes. The damped-periodic parts of modal responses are combined using the double-sum equation whereas the rigid parts are combined algebraically. A particular modal response quantity is separated into damped-periodic and rigid parts using the “rigid response coefficient”. The USNRC sponsored study recommends the calculation of rigid response coefficient by either the Lindley–Yow approach or Gupta method. While Lindley–Yow's method has a heuristic basis and gives incorrect results in low frequency region, Gupta's method is based on numerical studies of free-field earthquake motions and works well in the frequency regions of interest for a free-field ground motion. A closed-form solution was developed by Hahn and Valenti in 1997 using a frequency domain approach. With appropriate simplifications, their work can be shown to result in an expression which is very similar to that given by Gupta. It must be noted that the earthquake input to the secondary systems such as piping and equipment is defined by a floor motion and not a free-field ground motion. The frequency characteristics of a floor motion are very different from those of a free-field ground motion. In this paper, we study the validity of existing formulations for the case of floor motions and develop a closed-form solution based on a time domain approach to explain the behavior of rigid response coefficient. The formulation is then used to explain the nature of variation in rigid response coefficient for ground as well as floor motions. It is shown that the proposed formulation and its simplified form gives results that are identical to those evaluated numerically in the complete frequency region of interest. DA - 2007/10// PY - 2007/10// DO - 10.1016/j.nucengdes.2007.04.003 VL - 237 IS - 19 SP - 2075-2082 SN - 0029-5493 ER - TY - JOUR TI - Adaptive seasonal time series models for forecasting short-term traffic flow AU - Shekhar, Shashank AU - Williams, Billy T2 - Transportation Research Record AB - Conventionally, most traffic forecasting models have been applied in a static framework in which new observations are not used to update model parameters automatically. The need to perform periodic parameter reestimation at each forecast location is a major disadvantage of such models. From a practical standpoint, the usefulness of any model depends not only on its accuracy but also on its ease of implementation and maintenance. This paper presents an adaptive parameter estimation methodology for univariate traffic condition forecasting through use of three well-known filtering techniques: the Kalman filter, recursive least squares, and least mean squares. Results show that forecasts obtained from recursive adaptive filtering methods are comparable with those from maximum likelihood estimated models. The adaptive methods deliver this performance at a significantly lower computational cost. As recursive, self-tuning predictors, the adaptive filters offer plug-and-play capability ideal for implementation in real-time management and control systems. The investigation presented in this paper also demonstrates the robustness and stability of the seasonal time series model underlying the adaptive filtering techniques. DA - 2007/// PY - 2007/// DO - 10.3141/2024-14 IS - 2024 SP - 116–125 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-40449101916&partnerID=MN8TOARS ER - TY - JOUR TI - Study of intermediate crack debonding in adhesively plated beams AU - Liu, I. S. T. AU - Oehlers, D. J. AU - Seracino, R. T2 - Journal of Composites for Construction AB - The main disadvantage of reinforced concrete beams retrofitted with steel or fiber reinforced polymer (FRP) plates adhesively bonded to the external surfaces is the premature debonding of the plates before reaching the desired strength or ductility. One of the main mechanisms of debonding failure is intermediate crack (IC) debonding, which is initiated by the formation of flexural cracks in the vicinity of the plates causing slip to occur at the plate/concrete interfaces. Much of the existing research focuses on the bond–slip relationship at the plate/concrete interface, with a lack of attention on the IC debonding behavior of flexural members. In this research, a model is described for IC debonding of plated RC beams that is based on partial interaction theory. To allow a better understanding of the IC debonding behavior of plated members, studies are carried out using the proposed model to study the effects of variations in crack spacings and rate of change of moment, and it is shown that both of these factors as well as the number of cracks in the beam can have large effects on the local behavior and the resultant strains in the plated member. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)1090-0268(2007)11:2(175) VL - 11 IS - 2 SP - 175-183 ER - TY - JOUR TI - Simulation of flocculation in stirred vessels - Lagrangian versus Eulerian AU - Prat, O. P. AU - Ducoste, J. J. T2 - CHEMICAL ENGINEERING RESEARCH & DESIGN AB - A study has been performed to evaluate Lagrangian and Eulerian approaches for simulating flocculation in stirred vessels. The prediction of the transient floc size evolution was performed using the quadrature method of moments (QMOM) while flow field characteristics within the turbulent stirred vessel were obtained using computational fluid dynamics (CFD). The Eulerian and Lagrangian CFD/QMOM models were applied to a 28 l square tank using either a Rushton turbine or a fluid foil impeller. Simulations were performed with an initial concentration of 100 mg L−1 of 1 μm nominal clay particles for several average characteristic velocity gradients (40-, 70-, 90-, 150-s−1). For the Lagrangian approach, the results showed that the average floc size transient evolution curve does not predict a peak followed by a lower steady-state size as observed for higher shear rates with the Eulerian approach. However, the overall good agreement between the Eulerian and Lagrangian CFD/QMOM models, indicates that a Lagrangian approach combined with a QMOM model would be an efficient method to quantify the impact of non-fluid flow experimental conditions on the flocculation process. In addition, the Lagrangian CFD/QMOM approach may be a useful tool to study the dynamics of flocculation and determine appropriate coalescence/breakup kernels when performing an inverse problem technique. DA - 2007/2// PY - 2007/2// DO - 10.1205/cherd05001 VL - 85 IS - A2 SP - 207-219 SN - 1744-3563 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33947272599&partnerID=MN8TOARS KW - Eulerian KW - Lagrangian KW - quadrature method of moment KW - computational fluid dynamics KW - turbulence KW - flocculation ER - TY - JOUR TI - Proposed design guidelines for strengthening of steel bridges with FRP materials AU - Schnerch, D. AU - Dawood, M. AU - Rizkalla, S. AU - Sumner, E. T2 - CONSTRUCTION AND BUILDING MATERIALS AB - This paper focuses on the use of externally bonded high modulus carbon fiber reinforced polymer (HM CFRP) materials to strengthen steel bridges and structures. Proper installation of the CFRP materials is necessary to prevent premature failure due to debonding. The paper proposes guidelines and installation techniques based on the best practice reported in the literature and the extensive practical experience in bonding of composite materials. The surface preparation of the materials, the application of the adhesive and the detailing of the strengthening are provided in detail. The design guidelines include the structural design criteria for the use of high modulus CFRP materials as flexural strengthening system of typical steel–concrete composite bridge girders. The flexural design procedure is based on a moment–curvature analysis and a specified increase of the live load carried by the bridge to satisfy specific serviceability requirements. A bond model is also described which can be used to calculate the shear and peel stresses within the adhesive thickness. To prevent a premature debonding failure of the strengthening system, the criteria specify a maximum principle stress in the adhesive which cannot be exceeded for a given characteristic strength of an adhesive. A worked example is presented to illustrate the proposed flexural design approach. The research findings conclude that high modulus CFRP materials provide a promising alternative for strengthening steel bridges that can be easily designed and installed to increase their strength and stiffness. DA - 2007/5// PY - 2007/5// DO - 10.1016/j.conbuildmat.2006.03.003 VL - 21 IS - 5 SP - 1001-1010 SN - 1879-0526 KW - high modulus carbon fiber reinforced polymers KW - steel structures KW - design guidelines ER - TY - JOUR TI - Numerical simulation of UV disinfection reactors: Evaluation of alternative turbulence models AU - Liu, D. AU - Wu, C. AU - Linden, K. AU - Ducoste, J. T2 - Applied Mathematical Modelling AB - Six turbulence models, including standard k–ε, k–ε RNG, k–ω (88), revised k–ω (98), Reynolds stress transport model (RSTM), and two-fluid model (TFM), were applied to the simulation of a closed conduit polychromatic UV reactor. Predicted flow field and turbulent kinetic energy were compared with the experimental data from a digital particle image velocimetry (DPIV). All of the predicted flow fields were combined with a multiple segment source summation (MSSS) fluence rate model and three different microbial response kinetic models to simulate the disinfection process at two UV lamp power conditions. Microbial transport was simulated using the Lagrangian particle tracking method. The results show that the fluence distributions and the effluent inactivation levels were sensitive to the turbulence model selection. The level of sensitivity was a function of the operating conditions and the UV response kinetics of the microorganisms. Simulations with operating conditions that produced higher log inactivation or utilized microorganisms with higher UV sensitivity showed greater sensitivity to the turbulence model selection. In addition, a broader fluence distribution was found with turbulence models that predicted a larger wake region behind the lamps. DA - 2007/// PY - 2007/// DO - 10.1016/j.apm.2006.06.004 VL - 31 IS - 9 SP - 1753–1769 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-34047229522&partnerID=MN8TOARS ER - TY - JOUR TI - Initiation of motion of a free-standing body to base excitation AU - Tung, C. C. T2 - EARTHQUAKE ENGINEERING & STRUCTURAL DYNAMICS AB - Abstract This study is concerned with the conditions for the initiation of various modes of response of a free‐standing rigid body, initially at rest, placed on a frictional horizontal base which undergoes earthquake‐like accelerations in both the horizontal and vertical directions. These conditions are derived using equations of motion appropriate for each mode of motion. The analysis shows that an equivalent horizontal base acceleration may be constructed by dividing the time history of horizontal base acceleration by the sum of gravitational acceleration and the time history of vertical base acceleration. The criteria governing each mode of response of a body of given aspect ratio are then presented graphically with the magnitude of the equivalent base acceleration as abscissa and the coefficient of friction between the body and the base as ordinate. The study shows that a body is more stable while the vertical base acceleration is upwards than when it is absent as expected. When the vertical base acceleration is downwards, although the body is very likely to be lifted off the base, it is nevertheless possible to rock, and slide and rock simultaneously provided the value of coefficient of friction is sufficiently high and the downward vertical base acceleration is not too different from gravitational acceleration. Copyright © 2007 John Wiley & Sons, Ltd. DA - 2007/8// PY - 2007/8// DO - 10.1002/eqe.703 VL - 36 IS - 10 SP - 1431-1439 SN - 0098-8847 KW - free standing KW - rigid body KW - base excitation ER - TY - JOUR TI - Evolutionary computation-based approach for model error correction and calibration AU - Zechman, Emily M. AU - Ranji Ranjithan, S. T2 - Advances in Water Resources AB - Calibration is typically used for improving the predictability of mechanistic simulation models by adjusting a set of model parameters and fitting model predictions to observations. Calibration does not, however, account for or correct potential misspecifications in the model structure, limiting the accuracy of modeled predictions. This paper presents a new approach that addresses both parameter error and model structural error to improve the predictive capabilities of a model. The new approach simultaneously conducts a numeric search for model parameter estimation and a symbolic (regression) search to determine a function to correct misspecifications in model equations. It is based on an evolutionary computation approach that integrates genetic algorithm and genetic programming operators. While this new approach is designed generically and can be applied to a broad array of mechanistic models, it is demonstrated for an illustrative case study involving water quality modeling and prediction. Results based on extensive testing and evaluation, show that the new procedure performs consistently well in fitting a set of training data as well as predicting a set of validation data, and outperforms a calibration procedure and an empirical model fitting procedure. DA - 2007/5// PY - 2007/5// DO - 10.1016/j.advwatres.2006.11.013 VL - 30 IS - 5 SP - 1360-1370 J2 - Advances in Water Resources LA - en OP - SN - 0309-1708 UR - http://dx.doi.org/10.1016/j.advwatres.2006.11.013 DB - Crossref KW - evolutionary computation KW - calibration KW - model error correction KW - genetic programming ER - TY - JOUR TI - Determination of time-domain viscoelastic functions using optimized interconversion techniques AU - Mun, Sungho AU - Chehab, Ghassan R. AU - Kim, Y. Richard T2 - ROAD MATERIALS AND PAVEMENT DESIGN DA - 2007/// PY - 2007/// DO - 10.3166/RMPD.8.351-365 VL - 8 IS - 2 SP - 351-365 SN - 2164-7402 KW - interconversion methods KW - prony series KW - complex modulus KW - relaxation modulus KW - creep compliance KW - linear viscoelastic KW - asphalt mixtures ER - TY - JOUR TI - Bond strength of near-surface mounted FRP strip-to-concrete joints AU - Seracino, R. AU - Jones, N. M. AU - Ali, S. M. AU - Page, M. W. AU - Oehlers, D. J. T2 - Journal of Composites for Construction AB - The retrofitting technique of near-surface mounting (NSM) fiber-reinforced polymer (FRP) bars/strips is receiving more attention recently due to a number of advantages over the externally bonded technique. However, there is insufficient data available in the existing literature to quantify the intermediate crack (IC) debonding mechanism of reinforced concrete members retrofitted with longitudinal NSM strips. As it is recognized that simple push–pull specimens simulate the IC debonding mechanism observed in retrofitted flexural members, this paper presents the results of a series of 36 push–pull tests using NSM strips to quantify the bond strength of such FRP-to-concrete joints. It is proposed that the confinement effect of the concrete surrounding the interface debonding crack improves the shear stress transfer mechanism resulting in higher debonding plate strains compared with externally bonded plates. A nonlinear statistical analysis of the experimental data was undertaken to develop a model to predict the maximum axial plate force for IC debonding, taken at a critical bonded length of 200mm. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)1090-0268(2007)11:4(401) VL - 11 IS - 4 SP - 401-409 ER - TY - PCOMM TI - Stirrups for torsion resistance prompt questions - Authors' response AU - Lucier, G. AU - Hassan, T. AU - Rizkalla, S. AU - Klein, G. AU - Zia, P. DA - 2007/// PY - 2007/// SP - 14-14 ER - TY - JOUR TI - Shear strength parameters of municipal solid waste with leachate recirculation AU - Gabr, Mohammed AU - Hossain, M. S. AU - Barlaz, Morton T2 - Journal of Geotechnical and Geoenvironmental Engineering AB - The objective of this study was to characterize relative changes in waste shear strength parameters during waste decomposition. Twelve direct shear tests (100mm diameter by 50mm thickness) were performed on waste specimens ranging from fresh to well-decomposed residential refuse. In addition, nine direct shear tests were performed on selected waste components including fresh paper, partially decomposed refuse, and plastics. Results indicate that the friction angle of refuse decreased with decomposition. As refuse decomposed, the plastic content increased, which contributed to a decrease in friction angle as the friction angle of plastics is 18–19∘ as compared to 33° for fresh shredded waste. The extent of refuse decomposition was characterized by the cellulose plus hemicellulose to lignin ratio [(C+H)∕L]. The measured friction angle decreased from 32 to 24° as (C+H)∕L decreased from 1.29 to 0.25. The shearing pattern for decomposed refuse showed a peak, followed by residual, which was then followed by a steady increase in shear stresses with displacement; the final rate of increase was similar to that observed in fresh paper specimens. Results from this work were comparable to data from previous reports, though it is important to characterize the extent of solids decomposition for a valid comparison with published studies. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)1090-0241(2007)133:4(478) VL - 133 IS - 4 SP - 478–484 ER - TY - JOUR TI - Oscillator interrogated time-of-flight optical fiber interferometer for global strain measurements AU - Jiang, Guoliang AU - Van Vickle, Patrick AU - Peters, Kara AU - Knight, Victor T2 - SENSORS AND ACTUATORS A-PHYSICAL AB - In this paper, we demonstrate an oscillator interrogated time-of-flight optical fiber interferometer that provides global strain information for large-scale structures. The sensing resolution of the interferometer is sufficient for many structural applications, while the system is relatively inexpensive and durable as compared to previous methods. The measurable displacement range is determined by the oscillator frequency and can therefore be designed to be significantly larger than that of current systems. An optical length change resolution of 9.5 mm and range of 1.39 m are demonstrated experimentally. To easily embed the interferometer in structures and effectively increase the fiber sensing length, a commercially available prefabricated fiber ribbon is used. Results from static loading tests of a FRP strengthened reinforced concrete beam with embedded fiber ribbons show the feasibility of this technique for monitoring infrastructure systems. DA - 2007/4/15/ PY - 2007/4/15/ DO - 10.1016/j.sna.2006.08.023 VL - 135 IS - 2 SP - 443-450 SN - 0924-4247 KW - time-of-flight interferometer KW - displacement measurements KW - structural monitoring ER - TY - JOUR TI - Erratum for “Shear Strength Parameters of Municipal Solid Waste with Leachate Recirculation” by M. A. Gabr, M. S. Hossain, and M. A. Barlaz AU - Gabr, Mohammed A. T2 - Journal of Geotechnical and Geoenvironmental Engineering DA - 2007/9// PY - 2007/9// DO - 10.1061/(asce)1090-0241(2007)133:9(1181) VL - 133 IS - 9 SP - 1181-1181 ER - TY - JOUR TI - Direct displacement-based seismic design of unbonddd post-tensioned masonry walls AU - Wight, G. D. AU - Kowalsky, M. J. AU - Ingham, J. M. T2 - ACI Structural Journal AB - First Name is required invalid characters Last Name is required invalid characters Email Address is required Invalid Email Address Invalid Email Address DA - 2007/// PY - 2007/// DO - 10.14359/18858 VL - 104 IS - 5 SP - 560-569 ER - TY - CONF TI - Shear banding and microstructure evolution in 2D numerical experiments AU - Evans, T. M. AU - Frost, J. D. AB - A limitation of using laboratory experiments to study the micromechanics of soils is that detailed information about the specimen microstructure is typically available at only one state in a test sequence due to the destructive nature of the forensic process. To study microstructure evolution, characterization of replicate specimens tested to various global axial strain levels has been undertaken, but this procedure presents some practical and theoretical problems. Accordingly, a numerical program was undertaken using the discrete element method to model the micromechanical deformation response of particulate assemblies in two dimensions. The simulated assemblies failed via regions of high localized strain. The microstructures of these assemblies were studied as a function of global axial strain to assess evolution of local and mesoscale void ratio distributions and mean free paths. Local void ratio distributions were modeled statistically and mesoscale measurements were used to assess microstructure inside and outside of the shear bands. C2 - 2007/// C3 - Proceedings of GeoDenver 2007: New peaks in geotechnics DA - 2007/// DO - 10.1061/40917(236)28 PB - Denver, CO: Geo-Institute of ASCE ER - TY - JOUR TI - Innovative process to characterize buried utilities using Ground Penetrating Radar AU - Lester, Jim AU - Bernold, Leonhard E. T2 - AUTOMATION IN CONSTRUCTION AB - Today's non-invasive technologies for locating buried utilities can be considered as ancient. However, Ground Penetrating Radar (GPR) has recently received significant attention from the scientific community since it showed great promise in detecting landmines. Yet, the complexities of the underground, especially in inhabited areas, makes “seeing-through-the-earth” to find buried utilities extremely difficult. This paper presents the results of a data processing method, called Translation Invariant Wavelet Packet Detection (TIWPD), applied to filtering GPR data collected on a university campus. It first provides a brief introduction into the working principles of scanning the ground with electromagnetic radar waves that are being refracted, scattered, and reflected by buried objects of all sizes and materials. In its main section, the paper presents the results of experimental deployment of the system during a construction project that involved the extensive excavation trenches to lay chilled water pipes. The significance of this paper lies in its use of real-world GPR data to demonstrate the performance characteristics of the filtering process and its validation with the actual condition found during excavation. The encouraging results of this work should provide the basis for developing a near-real time utility detection system that can be used by laborers in the field. DA - 2007/7// PY - 2007/7// DO - 10.1016/j.autcon.2006.09.004 VL - 16 IS - 4 SP - 546-555 SN - 1872-7891 KW - Ground Penetrating Radar KW - data filtering KW - buried utility protection KW - non-invasive utility detection KW - accident prevention KW - Translation Invariant Wavelet Packet Detection ER - TY - JOUR TI - Control schemes for tele-robotic pipe installation AU - Bernold, Leonhard E. T2 - AUTOMATION IN CONSTRUCTION AB - Tele‐robotic operation, which allows an operator to control a mechanical tool from a safe distance, provides a technical alternative to installing buried pipes within the confines of a hazardous trench. However, the handling as well as the jointing of the many different types can't be easily replaced by remotely controllable devices. While large concrete drainage pipes are heavy, plastic pipes for sewer and water systems require careful handling to guarantee that they are properly sealed by the O‐ring gasket inside the bell. This paper will discuss the differences in control schemes that have been developed to enable the necessary operations for the two most common pipes. The paper will not only describe the designs of the many innovative components but also discuss how the many field trials with construction personnel led to successful final functionality tests for each prototype. DA - 2007/7// PY - 2007/7// DO - 10.1016/j.autcon.2006.09.002 VL - 16 IS - 4 SP - 518-524 SN - 0926-5805 KW - tele-robotics KW - pipe manipulator KW - construction automation KW - safety KW - performance evaluation KW - technological innovation KW - remote control KW - mechanical design ER - TY - JOUR TI - Climate, stream flow prediction and water management in northeast Brazil: societal trends and forecast value AU - Broad, Kenneth AU - Pfaff, Alexander AU - Taddei, Renzo AU - Sankarasubramanian, A. AU - Lall, Upmanu AU - de Assis de Souza Filho, Franciso T2 - Climatic Change DA - 2007/5/30/ PY - 2007/5/30/ DO - 10.1007/s10584-007-9257-0 VL - 84 IS - 2 SP - 217-239 J2 - Climatic Change LA - en OP - SN - 0165-0009 1573-1480 UR - http://dx.doi.org/10.1007/s10584-007-9257-0 DB - Crossref ER - TY - JOUR TI - Simplified performance model of gas turbine combined cycle systems AU - Zhu, Y. AU - Frey, H. Christopher T2 - Journal of Energy Engineering AB - Conventional evaluation approaches for complex technologies, such as gas turbine systems, typically use process simulators for modeling, which are usually complicated and time-consuming. In order to facilitate policy analysis, a simplified desktop model for gas turbine systems based upon the air-standard Brayton cycle is developed in Microsoft EXCEL. The simplified model incorporates key process details and includes a comprehensive cost model. The model is calibrated based on a typical “Frame 7F” heavy duty gas turbine fired with natural gas and syngas. The model generally produces accurate and reasonable estimates for performance and cost comparable to reference data. The model responds appropriately to different syngas compositions, such as based on variation in moisture content and CO2 removal. Changes in syngas composition lead to different syngas heating values and thus affect gas turbine performance and cost. The effects of changes in inputs on key outputs are evaluated. Six key inputs are identified that are critical in order to obtain accurate estimates. The simplified model provides detailed technical information in a format that supports strategic planning and analysis. DA - 2007/// PY - 2007/// DO - 10.1061/(asce)0733-9402(2007)133:2(82) VL - 133 IS - 2 SP - 82-90 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-34248512929&partnerID=MN8TOARS ER - TY - JOUR TI - Preparedness of engineering freshman to inquiry-based learning AU - Bernold, L. E. T2 - Journal of Professional Issues in Engineering Education and Practice AB - Educational experts, past and present, urge engineering colleges nationwide to transform their pedagogical paradigm from a predominantly lecture- to an inquiry-based teaching approach. Written comments by two seniors, deploring having to read and write in a required course of an ABET accredited program, highlight a common expectation of today’s students. Presented are the disturbing results of a survey that assessed the level of learning skills exhibited by 1,020 engineering freshmen. Time management not only surfaced as needing drastic remediation but it also correlated with the level of students’ motivation to succeed in college. Problems with poor time management were listed by 25% of the freshman cohort at the end of the first semester. From monitoring the submittals of online homework it was learned that timeliness corresponded with the final grade achieved in a course. The work presented in this paper indicates that universities need not only to address the students’ learning preferences but also equip them with the skills necessary to engage actively in the knowledge-building process, a necessary sea-change in engineering education. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)1052-3928(2007)133:2(99) VL - 133 IS - 2 SP - 99-106 ER - TY - JOUR TI - Novel finite-element-based subsurface imaging algorithms AU - Heidari, A. H. AU - Guddati, M. N. T2 - FINITE ELEMENTS IN ANALYSIS AND DESIGN AB - Through an unconventional use of the finite-element method, we have developed a new class of wave equation-based subsurface imaging algorithms. These methods, which are based on the recently developed arbitrarily wide-angle wave equations (AWWE) [M.N. Guddati, Arbitrarily wide-angle wave equations for complex media, Comput. Methods Appl. Mech. Eng. 195(1–3), 63–93], employ the finite-element concepts not just to solve, but to derive the governing equations of the imaging problem. The authors have successfully applied the AWWE imaging algorithms to both acoustic and elastic media. These implementations of AWWE imaging algorithms are discussed here, and the role of finite elements in their derivation is depicted. The stability of the AWWE imaging methods is analytically studied, and their accuracy is shown through numerical impulse responses. Finally, the effectiveness of the methods is illustrated using various synthetic problems for both acoustic and elastic media. DA - 2007/3// PY - 2007/3// DO - 10.1016/j.finel.2006.11.007 VL - 43 IS - 5 SP - 411-422 SN - 1872-6925 KW - finite-element method KW - one-way wave equation KW - subsurface imaging KW - wavefield extrapolation KW - acoustic wave KW - elastic wave ER - TY - JOUR TI - Improving the professional engineering licensure process for construction engineers AU - Johnston, David AU - Ahluwalia, N. T. AU - Gwyn, M. B. T2 - Journal of Construction Engineering and Management AB - Professional engineering licensure is important in the career development of engineers who undertake work critical to protecting public health, safety, and welfare. The knowledge and experience of construction engineers has not previously been well represented in professional engineering licensure evaluation. The ASCE-CI Construction Engineering Education Committee identified recognition of construction engineering in the professional engineering licensure process as one of its missions when it was organized in 1995. With the support of the states and the receptiveness of the National Council of Examiners for Engineering and Surveying (NCEES), improvements were gradually achieved in recognition of construction engineering experience by changes in NCEES Model Rules. In 2003, the NCEES Board decided to evaluate modification of the Civil Engineering PE exam to include a Construction Engineering module. The evaluation included a Professional Activities and Knowledge Study (PAKS) of the skills appropriate for construction engineers. Following approval of the NCEES Board in 2005, exam development has been underway with implementation planned for April 2008. An additional benefit of the PAKS is the improved understanding of knowledge needed by construction engineers in completing their work activities. These results should be valuable to construction engineering education and industry in identifying critical subject matter for inclusion in courses, curriculums, and continuing education. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)0733-9364(2007)133:9(669) VL - 133 IS - 9 SP - 669–677 ER - TY - JOUR TI - Equivalent damping in support of direct displacement-based design AU - Dwairi, H. M. AU - Kowalsky, M. J. AU - Nau, J. M. T2 - JOURNAL OF EARTHQUAKE ENGINEERING AB - The concept of equivalent linearization of nonlinear system response as applied to direct displacement-based design is evaluated. Until now, Jacobsen's equivalent damping approach combined with the secant stiffness method has been adopted for the linearization process in direct displacement-based design. Four types of hysteretic models and a catalog of 100 ground motion records were considered. The evaluation process revealed significant errors in approximating maximum inelastic displacements due to overestimation of the equivalent damping values in the intermediate to long period range. Conversely, underestimation of the equivalent damping led to overestimation of displacements in the short period range, in particular for effective periods less than 0.4 seconds. The scatter in the results ranged between 20% and 40% as a function of ductility. New equivalent damping relations for four structural systems, based upon nonlinear system ductility and maximum displacement, are proposed. The accuracy of the new equivalent damping relations is assessed, yielding a significant reduction of the error in predicting inelastic displacements. Minimal improvement in the scatter of the results was achieved, however. While many significant studies have been conducted on equivalent damping over the last 40 years, this study has the following specific aims: (1) identify the scatter associated with Jacobsen's equivalent damping combined with the secant stiffness as utilized in Direct Displacement-Based Design; and (2) improve the accuracy of the Direct Displacement-Based Design approach by providing alternative equivalent damping expressions. DA - 2007/7// PY - 2007/7// DO - 10.1080/13632460601033884 VL - 11 IS - 4 SP - 512-530 SN - 1363-2469 KW - damping KW - hysteretic KW - seismic response KW - seismic analysis KW - equivalent linearization ER - TY - JOUR TI - "Channel die compression revisited: Application of a set of basic crystal hardening inequalities to (110) loading" (vol 39, pg 610, 2007) AU - Havner, Kerry S. T2 - MECHANICS OF MATERIALS AB - An error in the uniqueness proof of load-axis stability in the subject paper [Havner, K.S., 2007. Channel die compression revisited: application of a set of basic crystal hardening inequalities to (1 1 0) loading. Mech. Mater. (39), 610–622] is acknowledged and another argument for axis stability is given. DA - 2007/9// PY - 2007/9// DO - 10.1016/j.mechmat.2007.03.001 VL - 39 IS - 9 SP - 893-895 SN - 0167-6636 KW - Fcc crystals KW - channel die compression KW - slip-system hardening inequalities ER - TY - JOUR TI - Trraffic management center use of incident detection algorithms: Findings of a nationwide survey AU - Williams, Billy M. AU - Guin, Angshuman T2 - IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS AB - The focus of this paper is the context in which the decision makers for traffic management centers (TMCs) choose whether to include and/or use automatic incident detection (AID) algorithms. A survey was conducted of TMC professionals in positions to make, influence, or provide input to decisions regarding TMC operational policies as well as decisions regarding priorities for future system enhancements. Analysis of the survey results not only provides an understanding of the reasons behind the limited implementation of AID algorithms but also allows a direct comparison between the conventional incident detection methods and the AID technology on the basis of measured and/or perceived performance. It was observed that 90% of the survey respondents feel that the current methods of incident detection are insufficient either at present (70%) or will be so in the future (20%). This finding alone motivates a need to redouble research efforts aimed at developing robust and accurate automatic detection methods. In this regard, this paper presents promising directions to overcome past AID algorithm deficiencies DA - 2007/6// PY - 2007/6// DO - 10.1109/TITS.2007.894193 VL - 8 IS - 2 SP - 351-358 SN - 1524-9050 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-34249913940&partnerID=MN8TOARS KW - decision support systems KW - detectors KW - intelligent systems KW - transportation ER - TY - JOUR TI - Measurement of low velocity and quasi-static failure modes in PMMA AU - Pearson, J. D. AU - Zikry, M. A. AU - Prabhugoud, M. AU - Peters, K. T2 - POLYMER COMPOSITES AB - Abstract An investigation of the low velocity impact and quasi‐static failure of polymethylmethacrylate (PMMA) based on global and local strain measurements was conducted. Local strains were obtained from surface‐mounted fiber Bragg grating (FBG) sensors, and they were combined with global measurements from quasi‐static indentation and low‐velocity impact experiments to obtain detailed maps of how failure evolves. For both loading regimes, the interactions between the host PMMA specimens and the sensors played a crucial role in the evolution of residual strains. A mapping of the strains clearly shows that strains decrease radially, from high values near the point of impact to far‐field values. Sensors located in critical locations had the highest residual strains prior to PMMA fracture. Furthermore, it was determined that strain transfer to the sensor is strongly influenced by the bonding conditions at the specimen's surface. Because of the debonding of the sensor and the frictional effects associated with the bonding agent, compressive residual strains occurred on the rear‐surface. Hence, a detailed understanding of how strain evolves due to sensor–host interactions and catastrophic fracture can be obtained, which can potentially be used to mitigate damage in PMMA for a range of strain rates. POLYM. COMPOS., 28:381–391, 2007. © 2007 Society of Plastics Engineers DA - 2007/6// PY - 2007/6// DO - 10.1002/pc.20287 VL - 28 IS - 3 SP - 381-391 SN - 0272-8397 ER - TY - JOUR TI - Infrastructure management information system framework requirements for disasters AU - Pradhan, A. R. AU - Laefer, D. F. AU - Rasdorf, W. J. T2 - Journal of Computing in Civil Engineering AB - A three-tiered, enterprise, geographic information system architecture offers a robust, efficient, and secure platform to potentially revolutionize disaster management by enabling support of all of the phases of governmental activity that must occur before, during, and after a disaster. Presently, both publicly and privately initiated, computer-based systems designed for disaster management cannot meet the real-time data access and analysis needs at crucial stages, especially those occurring during an actual disaster. Impediments are reflective of the proprietary, stand alone, and segregated nature of current systems. This paper proposes an integrated, infrastructure management information system as a reliable and effective alternative. Issues related to sharing data, customizing applications, supporting multiple data formats, querying visually, facilitating ubiquitous computing, and upgrading are all addressed. Achieving maximum flexibility and capacity in a disaster management system relies upon recent advances in the following areas: (1) standardized data specifications; (2) middleware services; and (3) Web-enabled, distributed computing. Key resources in designing and implementing such an arrangement are prototyped in a system that was initially designed for addressing disaster management of urban explosions. The critical details of that system are presented herein. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)0887-3801(2007)21:2(90) VL - 21 IS - 2 SP - 90-101 ER - TY - JOUR TI - Generic debonding resistance of EB and NSM plate-to-concrete joints AU - Seracino, R. AU - Saifulnaz, M. R. R. AU - Oehlers, D. J. T2 - Journal of Composites for Construction AB - It is well established that adhesively bonding plates to the surfaces of reinforced concrete members is an efficient retrofitting approach. Specifically, two techniques have emerged: Using thin externally bonded (EB) sheets/plates and near-surface mounted (NSM) strips/bars. A good amount of research has been undertaken worldwide to understand the fundamental behavior describing such adhesively bonded plate-to-concrete joints. Unfortunately, until now, no generic model exists to determine the debonding resistance of both retrofitting techniques. In this paper, a generic analytical model is derived to determine the debonding resistance of any adhesively bonded plate-to-concrete joint using an idealized linear-softening local interface bond-slip relationship. The model is derived using a unique definition of the debonding failure plane and confinement ratio such that it is suitable for both the externally bonded and near-surface mounted techniques. The model is validated by comparison with existing push-pull data as well as 14 new push-pull tests with varying plate cross-section aspect ratios. Comparison with an existing well-known model demonstrates the suitability of the proposed generic model. The model can be used to predict the intermediate crack debonding resistance of strengthened reinforced concrete members. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)1090-0268(2007)11:1(62) VL - 11 IS - 1 SP - 62-70 ER - TY - JOUR TI - Decreased survival of C/EBP beta-deficient keratinocytes is due to aberrant regulation of p53 levels and function AU - Yoon, K. AU - Zhu, S. AU - Ewing, S. J. AU - Smart, R. C. T2 - ONCOGENE DA - 2007/1// PY - 2007/1// DO - 10.1038/sj.onc.1209797 VL - 26 IS - 3 SP - 360-367 SN - 1476-5594 KW - apoptosis KW - p53 KW - C/EBP beta KW - keratinocytes ER - TY - JOUR TI - Comparing real-world fuel consumption for diesel- and hydrogen-fueled transit buses and implication for emissions AU - Frey, H. Christopher AU - Rouphail, Nagui M. AU - Zhai, Haibo AU - Farias, Tiago L. AU - Goncalves, Goncalo A. T2 - TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT AB - This paper explores the influence of key factors such as speed, acceleration, and road grade on fuel consumption for diesel and hydrogen fuel cell buses under real-world operating conditions. A Vehicle Specific Power-based approach is used for modeling fuel consumption for both types of buses. To evaluate the robustness of the modeling approach, Vehicle Specific Power-based modal average fuel consumption rates are compared for diesel buses in the US and Portugal, and for the Portuguese diesel and hydrogen fuel cell buses that operate on the same route. For diesel buses there is similar intra-vehicle variability in fuel consumption using Vehicle Specific Power modes. For the fuel cell bus, the hydrogen fuel consumption rate was found to be less sensitive to Vehicle Specific Power variations and had smaller variability compared to diesel buses. Relative errors between trip fuel consumption estimates and actual fuel use, based upon predictions for a portion of real-world activity data that were not used to calibrate the models, were generally under 10% for all observations. The Vehicle Specific Power-based modeling approach is recommended for further applications as additional data become available. Emission changes based upon substituting hydrogen versus diesel buses are evaluated. DA - 2007/6// PY - 2007/6// DO - 10.1016/j.trd.2007.03.003 VL - 12 IS - 4 SP - 281-291 SN - 1361-9209 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-34247868934&partnerID=MN8TOARS KW - fuel consumption KW - diesel buses KW - hydrogen fuel cells KW - vehicle specific power ER - TY - JOUR TI - Teaching evaluations for construction engineering and management: Opportunity to move us forward AU - Bernold, L. E. T2 - Journal of Construction Engineering and Management AB - Engineering education is challenged to usher in new approaches to preparing its students for their professional careers. Many blue-ribbon committees call for systematic modifications in research universities to clear the path for cross-disciplinary learning communities. In this context, the paper investigates the effect of student ratings as a measure of teaching effectiveness. One survey found that engineering sophomores perceive active student-centered teaching methods as greatly ineffective, while a second survey highlighted that lecture-based teaching underpins student rating forms used at U.S. research universities. With the goal of aligning teaching objectives, learning outcomes, and the criteria for evaluating teaching, a student rating form is presented. The scales of the multidimensional construct are based on the most up-to-date understanding of effective pedagogy, the new American Accreditation Board for Engineering and Technology criteria, and a view of the future of our profession. The importance of this paper lies in its science-based proposal underlying a call for the establishment of a coalition to validate a constructive approach to further teaching performance in the field of construction engineering and management. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)0733-9364(2007)133:2(146) VL - 133 IS - 2 SP - 146-156 ER - TY - JOUR TI - Simulation and analysis of freeway lane reversal for coastal hurricane evacuation AU - Williams, Billy AU - Tagliaferri, A.P. AU - Meinhold, S.S. AU - Hummer, J.E. AU - Rouphail, N.M. T2 - Journal of Urban Planning and Development AB - Following the unprecedented multistate evacuation for Hurricane Floyd in 1999, the North Carolina Department of Transportation and the Department of Crime Control and Public Safety jointly developed a lane reversal plan for Interstate 40 to facilitate evacuation of residents and tourists in southeastern North Carolina. Prior to the 2003 hurricane season, the NCDOT sponsored a two-year research to address areas of operational concern. The first year research findings resulted in modifications to the original lane reversal plan. The second year’s findings showed the modified reversal plan to be effective in expediting evacuation from the coastal threat zone. However, modeling of the entire lane reversal plan revealed a potentially extensive queue formation at the contraflow termination point. This paper presents an overview of the project along with the principal research findings and resulting plan modifications. In addition, this paper highlights conclusions and recommendations applicable to the general emergency evacuation problem. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)0733-9488(2007)133:1(61) VL - 133 IS - 1 SP - 61-72 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33847207471&partnerID=MN8TOARS ER - TY - JOUR TI - Shake table testing of post-tensioned concrete masonry walls containing openings AU - Wight, G. D. AU - Kowalsky, M. J. AU - Ingham, J. M. T2 - Publication pending AB - The in-plane seismic response of posttensioned concrete masonry walls with openings is investigated by means of shake table testing. A test program was initiated to verify the seismic performance of a wall system for use in residential construction. Two single-story in-plane wall tests were conducted initially to study the effect of door and window openings. This led to the construction and testing of a simple square structure which investigated the influence of multiple door and window openings and wall corners. All walls were posttensioned using unbonded high-tensile steel bars which allowed the wall panels to rock at the wall-foundation interface. Wall damage consisted of masonry crushing in the lower wall corners and vertical cracking under the openings and in the lintels. Residual displacements were minimal, due to the restoring forces provided by the posttensioning tendons. A complete description of the test setup and results is provided, including discussion on wall structural response in terms of flexural strength, displacement capacity, deformed shape, and damage patterns. DA - 2007/// PY - 2007/// DO - 10.1061/(asce)0733-9445(2007)133:11(1551) VL - 133 IS - 11 SP - 1551-1559 ER - TY - JOUR TI - Comparison of pulse velocity and impact-echo findings to properties of thin disks from a fire damaged slab AU - Dilek, U. AU - Leming, M. L. T2 - Journal of Performance of Constructed Facilities AB - The engineering assessment of fire damage to a concrete slab provided the opportunity to compare the results of in situ, nondestructive evaluation (NDE) techniques and laboratory testing of specimens taken from cores extracted from the fire damaged slab. This paper discusses and compares results of in situ pulse velocity and impact-echo testing with dynamic elastic modulus and air permeability index test results of 25mm (1in.) thick disks sawed from concrete cores removed from selected areas of the damaged slab. Both the NDE techniques and the laboratory testing of thin disks identified the presence of damage as a result of the fire. Analysis of the relatively thin concrete specimens permitted assessment of the presence and degree of damage in thin layers, and provided important and useful data on concrete properties for engineering assessment which was not available from NDE alone. Compressive strength results were consistent with the results of other tests but largely inconclusive by themselves. Impact-echo testing was able to identify the presence of a severely deteriorated concrete layer but could not identify the extent or depth of damage or clearly identify less damaged areas. A distressed layer of concrete was found by subsequent laboratory testing to be limited to a near-surface zone in some areas as suggested by the pulse velocity evaluation, but pulse velocity based analysis resulted in an overestimate of the depth of the damage. The findings highlighted a shortcoming of using conventional strength testing alone on investigations involving relatively thin layers of damage and pointed out several key limitations in the use and interpretation of nondestructive evaluation and associated analysis in a field assessment project. DA - 2007/// PY - 2007/// DO - 10.1061/(ASCE)0887-3828(2007)21:1(13) VL - 21 IS - 1 SP - 13-21 ER - TY - JOUR TI - Subsurface imaging via fully coupled elastic wavefield extrapolation AU - Guddati, Murthy N. AU - Heidari, A. Homayoun T2 - INVERSE PROBLEMS AB - We develop a new space-domain wavefield extrapolation technique for subsurface imaging in heterogeneous elastic media. Unlike the existing space-domain techniques, which separately propagate pressure and shear waves, the proposed method simulates one-way propagation with strong coupling between the pressure and shear waves, thus resulting in more accurate images. This is achieved by combining downward continuation ideas with the concepts of the recently developed arbitrarily wide-angle wave equations (Guddati M N 2006 Comput. Methods Appl. Mech. Eng. 195 63–93). In this method, one-way propagation is modelled by attaching a virtual halfspace to each depth step, which is represented by special complex-length finite elements. The parameters of the method, namely the lengths of the special finite elements, are chosen such that the wavefield extrapolation is stable and accurate. The accuracy of the proposed method is illustrated by its impulse response, which accurately captures the pressure, shear and head wave fronts. Application to various synthetic imaging problems, in both homogeneous and heterogeneous domains, further confirms the effectiveness of the method. DA - 2007/2// PY - 2007/2// DO - 10.1088/0266-5611/23/1/004 VL - 23 IS - 1 SP - 73-98 SN - 1361-6420 ER - TY - JOUR TI - Second-order modeling of variability and uncertainty in microbial hazard characterization AU - Vicari, Andrea S. AU - Mokhtari, Amirhossein AU - Morales, Roberta A. AU - Jaykus, Lee-Ann AU - Frey, H. Christopher AU - Slenning, Barrett D. AU - Cowen, Peter T2 - JOURNAL OF FOOD PROTECTION AB - This study describes an analytical framework that permits quantitative consideration of variability and uncertainty in microbial hazard characterization. Second-order modeling that used two-dimensional Monte Carlo simulation and stratification into homogeneous population subgroups was applied to integrate uncertainty and variability. Specifically, the bootstrap method was used to simulate sampling error due to the limited sample size in microbial dose-response modeling. A data set from human feeding trials with Campylobacter jejuni was fitted to the log-logistic dose-response model, and results from the analysis of FoodNet surveillance data provided further information on variability and uncertainty in Campylobacter susceptibility due to the effect of age. Results of our analyses indicate that uncertainty associated with dose-response modeling has a dominating influence on the analytical outcome. In contrast, inclusion of the age factor has a limited impact. While the advocacy of more closely modeling variability in hazard characterization is warranted, the characterization of key sources of uncertainties and their consistent propagation throughout a microbial risk assessment actually appear of greater importance. DA - 2007/2// PY - 2007/2// DO - 10.4315/0362-028X-70.2.363 VL - 70 IS - 2 SP - 363-372 SN - 0362-028X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33847215129&partnerID=MN8TOARS ER - TY - JOUR TI - Modeling of L-shaped, precast, prestressed concrete spandrels AU - Hassan, Tarek AU - Lucier, Gregory AU - Rizkalla, Sarni AU - Zia, Paul T2 - PCI JOURNAL AB - This paper presents results of nonlinear finite element (FE) analyses conducted to model the behavior of L-shaped, precast, prestressed concrete spandrels built with open web reinforcement. The FE model was calibrated using experimental results from recent tests of slender, L-shaped, precast, prestressed concrete spandrels. Detailed correlative studies between analytical and experimental results are provided, demonstrating the capability of the FE program to describe the observed experimental behavior. The feasibility of using open web reinforcement in compact, L-shaped, precast, prestressed concrete spandrels to achieve a more construction-friendly reinforcement scheme is also examined. Five different web reinforcement configurations for the compact spandrels were studied in order to evaluate the contribution of closed stirrups to the spandrels' shear-torsion behavior. The behavior, ultimate load-carrying capacity, and mode of failure of both the slender and compact L-shaped precast, prestressed concrete spandrels are presented. For loading values near the ultimate, the out-of-plane bending behavior of compact, L-shaped, precast, prestressed concrete spandrels is strongly influenced by the web-reinforcement configuration. Results from the analysis show that for long-span, compact spandrels, open web reinforcement can be used effectively to resist torsional forces throughout the member. DA - 2007/// PY - 2007/// DO - 10.15554/pcij.03012007.78.92 VL - 52 IS - 2 SP - 78-92 SN - 0887-9672 ER - TY - JOUR TI - Generating Alternatives Using Evolutionary Algorithms for Water Resources and Environmental Management Problems AU - Zechman, Emily M. AU - Ranjithan, Ranji S. T2 - Journal of Water Resources Planning and Management AB - Contemporary heuristic search procedures [e.g., evolutionary algorithms (EAs)] continue to offer increased capabilities for systematic search for a range of water resources and environmental management problems. These problems are often riddled, however, with numerous unquantifiable issues that are important when making decisions, but escape being incorporated in the system model. The mathematically optimal solution to such an incompletely defined model may be found unrealistic or altogether incorrect for the real problem. Optimization procedures could still be made useful if they can be utilized effectively to generate, in addition to the optimal solution, a small number of different alternatives that are near optimal. Alternatives with maximal differences in the decision variable values are expected to perform differently with respect to the unmodeled issues, providing valuable choices when making decisions. Although successful alternative generation procedures have been reported for mathematical programming-based search procedures, they are yet to be explored fully for EAs. This paper describes an extensive investigation of a new EA-based alternatives generation procedure, the evolutionary algorithm to generate alternatives (EAGA). A previously published regional wastewater treatment optimization study is used as a basis for establishing and demonstrating the capabilities of EAGA, and the set of results from the previous study is used as a benchmark for comparing the performance of EAGA. Comparisons of results indicate that EAGA is effective in generating good alternative solutions that perform differently with respect to several unmodeled issues. EAGA is sufficiently flexible to be applied to a wide range of water resources and environmental management problems. Further, EAGA can be applied to any problem that is set up to be solved using an evolutionary algorithm. DA - 2007/3// PY - 2007/3// DO - 10.1061/(ASCE)0733-9496(2007)133:2(156) VL - 133 IS - 2 SP - 156-165 J2 - J. Water Resour. Plann. Manage. LA - en OP - SN - 0733-9496 1943-5452 UR - http://dx.doi.org/10.1061/(asce)0733-9496(2007)133:2(156) DB - Crossref ER - TY - JOUR TI - Deicer salt scaling resistance of concrete containing manufactured sands AU - Dilek, Ufuk AU - Leming, Michael L. T2 - JOURNAL OF TESTING AND EVALUATION AB - Manufactured sands are produced by crushing rock deposits to produce a fine aggregate which is generally more angular and has a rougher surface texture than naturally weathered sand particles. Manufactured sands can also contain significant quantities of rock dust. As natural sand deposits become depleted near some areas of metropolitan growth, the use of manufactured sands as a replacement fine aggregate in concrete is receiving attention. DA - 2007/3// PY - 2007/3// DO - 10.1520/JTE100475 VL - 35 IS - 2 SP - 134-142 SN - 1945-7553 KW - deicer salt scaling resistance KW - salt scaling KW - manufactured sand KW - pavements KW - manufactured fine aggregate KW - frost durability KW - angularity KW - fines content KW - rock dust KW - air content KW - mineral admixtures KW - blended sands ER - TY - JOUR TI - Channel die compression revisited: Application of a set of basic crystal hardening inequalities to (110) loading AU - Havner, Kerry S. T2 - MECHANICS OF MATERIALS AB - A rigorous analytical investigation of (1 1 0) compression of fcc crystals in a channel die is carried-out for all lattice orientations between lateral constraint directions (channel-wall normals) (001¯) and (11¯2¯). It is proved that a set of basic slip-system hardening inequalities, that are consistent with experiments on fcc crystals in high symmetry, multiple-slip orientations in tension [Havner, K.S., 2005. On lattice and material-frame rotations and crystal hardening in high-symmetry axial loading. Philos. Mag. 85 (25), 2861–2894.], uniquely predict load-axis stability in (1 1 0) channel die compression, with lattice rotation and finite shearing about the loading direction as found experimentally for this range of orientations. It also is established from the inequalities that the evolving lateral constraint stress will be less than that predicted by classic (isotropic) Taylor hardening. DA - 2007/6// PY - 2007/6// DO - 10.1016/j.mechmat.2006.09.004 VL - 39 IS - 6 SP - 610-622 SN - 0167-6636 KW - Fcc crystals KW - channel die compression KW - slip-system hardening inequalities ER - TY - JOUR TI - Strengthening of circular hollow steel tubular sections using high modulus CFRP sheets AU - Fawzia, S. AU - Al-Mahaidi, R. AU - Zhao, X. L. AU - Rizkalla, S. T2 - CONSTRUCTION AND BUILDING MATERIALS AB - This paper describes the behaviour of very high strength (VHS) circular steel tubes strengthened by carbon fibre reinforced polymer (CFRP) and subjected to axial tension. A series of tests were conducted with different bond lengths and number of layers. The distribution of strain through the thickness of CFRP layers and along the CFRP bond length was studied. The strain was found to generally decrease along the CFRP bond length far from the joint. The strain through the thickness of the CFRP layers was also found to decrease from the bottom to top layer. The effective bond length for high modulus CFRP was established. Finally empirical models were developed to estimate the maximum load for a given CFRP arrangement. DA - 2007/4// PY - 2007/4// DO - 10.1016/j.conbuildmat.2006.06.014 VL - 21 IS - 4 SP - 839-845 SN - 1879-0526 KW - carbon fiber reinforced polymer KW - strengthening steel tube KW - bond KW - adhesive KW - VHS (very high strength) steel tubes ER - TY - JOUR TI - Practice review of five bioreactor/recirculation landfills AU - Benson, C. H. AU - Barlaz, M. A. AU - Lane, D. T. AU - Rawe, J. M. T2 - WASTE MANAGEMENT AB - Five landfills were analyzed to provide a perspective of current practice and technical issues that differentiate bioreactor and recirculation landfills in North America from conventional landfills. The bioreactor and recirculation landfills were found to function in much the same manner as conventional landfills, with designs similar to established standards for waste containment facilities. Leachate generation rates, leachate depths and temperatures, and liner temperatures were similar for landfills operated in a bioreactor/recirculation or conventional mode. Gas production data indicate accelerated waste decomposition from leachate recirculation at one landfill. Ambiguities in gas production data precluded a definitive conclusion that leachate recirculation accelerated waste decomposition at the four other landfills. Analysis of leachate quality data showed that bioreactor and recirculation landfills generally produce stronger leachate than conventional landfills during the first two to three years of recirculation. Thereafter, leachate from conventional and bioreactor landfills is similar, at least in terms of conventional indicator variables (BOD, COD, pH). While the BOD and COD decreased, the pH remained around neutral and ammonia concentrations remained elevated. Settlement data collected from two of the landfills indicate that settlements are larger and occur much faster in landfills operated as bioreactors or with leachate recirculation. The analysis also indicated that more detailed data collection over longer time periods is needed to draw definitive conclusions regarding the effects of bioreactor and recirculation operations. For each of the sites in this study, some of the analyses were limited by sparseness or ambiguity in the data sets. DA - 2007/// PY - 2007/// DO - 10.1016/j.wasman.2006.04.005 VL - 27 IS - 1 SP - 13-29 SN - 1879-2456 ER - TY - JOUR TI - Flexural behavior of aged prestressed concrete girders strengthened with various FRP systems AU - Rosenboom, Owen AU - Hassan, Tare K. AU - Rizkalla, Sami T2 - Construction and Building Materials AB - Many prestressed concrete bridges are in need of upgrading in order to increase their posted capacities. Departments of transportation across the country have been faced with large financial burdens on the maintenance budget, negative psychological effects on highway users, long traffic delays during maintenance, potential safety hazards, and reduced service life as a result of the deficiencies. In response to considerable consultation with the North Carolina Department of Transportation (NCDOT), a research project with practical goals was initiated to evaluate the cost-effectiveness and value engineering of Carbon Fiber Reinforced Polymer (CFRP) repair and strengthening systems for prestressed concrete bridge girders. This paper presents the first phase of the research program, involving the testing under static loading conditions of eight prestressed concrete bridge girders, six strengthened with various CFRP systems. Results show that the ultimate capacity of prestressed concrete bridge girders can be increased by as much as 73% using CFRP without sacrificing the ductility of the original member. Transverse CFRP U-wrap reinforcements are recommended along the length of the girder to control debonding type failures. The second phase of the research will examine the fatigue behavior of the strengthened girders, and provide analysis under service loading conditions. DA - 2007/4// PY - 2007/4// DO - 10.1016/j.conbuildmat.2006.06.007 VL - 21 IS - 4 SP - 764-776 J2 - Construction and Building Materials LA - en OP - SN - 0950-0618 UR - http://dx.doi.org/10.1016/j.conbuildmat.2006.06.007 DB - Crossref KW - prestressed KW - strengthening KW - fiber reinforced polymers KW - bridge girder KW - near surface mounted KW - externally bonded KW - flexural behavior ER - TY - JOUR TI - Control of carbon and ammonium ratio for simultaneous nitrification and denitrification in a sequencing batch bioreactor AU - Chiu, Ying-Chih AU - Lee, Li-Ling AU - Chang, Cheng-Nan AU - Chao, Allen C. T2 - INTERNATIONAL BIODETERIORATION & BIODEGRADATION AB - This study shows how the carbon and nitrogen (C/N) ratio controls the simultaneous occurrence of nitrification and denitrification in a sequencing batch reactor (SBR). Data demonstrated that a low C/N ratio resulted in a rapid carbon deficit, causing an unbalanced simultaneous nitrification–denitrification (SND) process in SBR. When the initial COD/NH4+-N ratio was adjusted to 11.1, the SND-based SBR achieved complete removal of NH4-N and COD without leaving any NO2−-N in the effluent. The nitrogen removal efficiency decreases gradually with increasing ammonium-loading rate to the SND–SBR system. Altogether, data showed that appropriate controls of carbon and nitrogen input are required to achieve an efficient SND–SBR. An established SND technology can save operation time and energy, and might replace the traditional two-stage biological nitrification and denitrification process. DA - 2007/1// PY - 2007/1// DO - 10.1016/j.ibiod.2006.08.001 VL - 59 IS - 1 SP - 1-7 SN - 1879-0208 KW - carbon source KW - heterotrophic nitrilication KW - oxidation-reduction potential (ORP) KW - simultaneous nitrification and denitrification (SND) ER - TY - JOUR TI - A model for life cycle evaluation of highway investments AU - List, George T2 - STRUCTURE AND INFRASTRUCTURE ENGINEERING AB - Sustainable development has added a new dimension to the evaluation of highway capacity investments. It places an emphasis on analyzing the entire life of a facility, from an environmental as well as an economic perspective. This paper presents a way to analyze capacity investments that is consistent with the sustainable development perspective. It departs from the typical approach of focusing on a small set of peak use conditions, often in the design year. It couples economic concepts with a representation of the facility's lifetime use to perform a robust analysis. A freeway facility is used to illustrate the ideas. Principles of engineering economics and life cycle costing help determine what incremental capacity investments would be warranted given postulated or observed use patterns. It is then demonstrated that the findings from this analysis and the principles employed can be applied to a wide range of infrastructure investment decision making situations. DA - 2007/6// PY - 2007/6// DO - 10.1080/15732470600590903 VL - 3 IS - 2 SP - 95-101 SN - 1573-2479 KW - life cycle KW - infrastructure KW - economics ER - TY - JOUR TI - Precast Concrete, L-Shaped Spandrels Revisited: Full-Scale Tests AU - Lucier, Gregory AU - Rizkalla, Sami AU - Zia, Paul AU - Klein, Gary T2 - PCI Journal AB - This paper presents results from full-scale testing conducted on 4 precast, prestressed concrete L-shaped spandrels. The 4 L-shaped spandrels were each loaded through 12-ft-long, prestressed double tees that rested on the spandrel ledge at one end and on an independent support at the other. None of the beams were constructed with closed stirrups of mild-steel reinforcement. Rather, different arrangements of transverse L-shaped bars, welded-wire reinforcement, and longitudinal bars were provided to resist the shear and torsion induced in the spandrels. Shear and torsion forces were created by the double-tee reaction forces that were loaded eccentrically to the spandrels. The transverse and longitudinal reinforcement resisted the combined effects of vertical shear and out-of-plane bending of the web and satisfied minimum vertical hanger reinforcement requirements for ledge-to-web attachment. All beams sustained loads in excess of their factored design loads. Eliminating the need for closed reinforcement in slender spandrels would be of significant benefit to the precast concrete industry. This design approach would enhance constructability of slender members, which could increase plant productivity and reduce overall costs. Behavior of all 4 spandrels at various limit states is presented, including crack patterns and failure modes. Researchers used these test results to better understand the fundamental mechanism developed in the L-shaped spandrels to resist shear and torsion. DA - 2007/3/1/ PY - 2007/3/1/ DO - 10.15554/pcij.03012007.62.76 VL - 52 IS - 2 SP - 62-76 J2 - pcij OP - SN - 0887-9672 UR - http://dx.doi.org/10.15554/pcij.03012007.62.76 DB - Crossref ER - TY - BOOK TI - Construction methods and management (7th ed.) AU - Nunnally, S. W. CN - TH145 .N86 2007 DA - 2007/// PY - 2007/// PB - Upper Saddle River, NJ: Pearson Prentice Hall SN - 0131716859 ER - TY - CONF TI - Microwave pretreatment of switchgrass to enhance enzymatic hydrolysis AU - Keshwani, D. R. AU - Cheng, J. J. AU - Li, L. AU - Burns, J. C. AU - Chiang, V. AB - Switchgrass is a promising lignocellulosic biomass for fuel-ethanol production. However, pretreatment of lignocellulosic materials is necessary to improve its susceptibility to enzymatic hydrolysis. The objectives of this study were to examine the feasibility of microwave pretreatment to enhance enzymatic hydrolysis of switchgrass and to determine the optimal pretreatment conditions. Switchgrass samples immersed in water, dilute sulfuric acid and dilute sodium hydroxide solutions were exposed to microwave radiation at varying levels of radiation power and residence time. Pretreated solids were enzymatically hydrolyzed and reducing sugars in the hydrolysate were analyzed. Microwave radiation of switchgrass at lower power levels resulted in more efficient enzymatic hydrolysis. The application of microwave radiation for 10 minutes at 250 watts to switchgrass immersed in 3% sodium hydroxide solution (w/v) produced the highest yields of reducing sugar. Results were comparable to conventional 60 minute sodium hydroxide pretreatment of switchgrass. The findings suggest that combined microwave-alkali is a promising pretreatment method to enhance enzymatic hydrolysis of switchgrass. C2 - 2007/// C3 - Proceedings of the ASABE Annual International Meeting (Minneapolis, Minnesota) DA - 2007/// DO - 10.13031/2013.23472 VL - 077127 ER -