TY - JOUR TI - Simultaneous oligonucleotide probe hybridization and immunostaining for in situ detection of Gordona species in activated sludge T2 - FEMS Microbiology Ecology AB - Oligonucleotide probes targeting ribosomal RNA can be designed with high specificity to target microbial populations at different phylogenetic levels if the cellular abundance of ribosomal RNA is sufficiently high. In contrast, polyclonal antibody probes cannot be produced with the same specificity for various phylogenetic groups, but they have the potential to detect slow growing microorganisms, populations with low metabolic activities, or even non-viable cells. We combined a polyclonal antibody stain with a ribosomal RNA targeted oligonucleotide probe for the single cell detection of species of the genus Gordona. Gordona species typically require long generation times, often exhibit filamentous growth, and are commonly encountered in activated sludge foams. Our results suggest that the ribosomal RNA content of individual cells of Gordona in activated sludge is highly variable. Therefore, the combined use of an immunostain and an oligonucleotide probe targeting ribosomal RNA can determine the identity of single cells and provide an approximation of their activity. This approach should result in improved detection limits while maintaining high specificity. DA - 1999/// PY - 1999/// DO - 10.1111/J.1574-6941.1999.TB00604.X UR - https://publons.com/wos-op/publon/7119270/ ER - TY - JOUR TI - Atrazine removal by preloaded GAG AU - Knappe, D.R.U. AU - Snoeyink, V.L. AU - Röche, P. AU - Prados, M.J. AU - Bourbigot, M.-M. T2 - Journal / American Water Works Association DA - 1999/// PY - 1999/// VL - 91 IS - 10 SP - 97-109 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0032620092&partnerID=MN8TOARS ER - TY - CONF TI - Determining Design Criteria for New WTP Solids Handling Facility AU - Ducoste, J.J. AU - Malmrose, P. AU - Weil, G. AU - Beacham, T. T2 - American Water Works Association / Water Environment Federation (AWWA/WEF) Residuals and Biosolids conference C2 - 1999/// CY - Charlotte, NC DA - 1999/// PY - 1999/// ER - TY - CONF TI - Implementation of the Integrated Disinfection Design Framework AU - Carlson, K.H. AU - Bellamy, W. AU - Pier, D. AU - Ducoste, J. AU - Carlson, M. T2 - American Water Works Association National Conference C2 - 1999/// C3 - Proceedings American Water Works Association National Conference CY - Chicago, IL DA - 1999/// PY - 1999/// ER - TY - CONF TI - Computational Fluid Dynamics Model of WTP Clearwell: Evaluation of Critical Parameters Influencing Model Performance AU - Ducoste, J.J. AU - Brauer, R. T2 - American Society of Civil Engineering-Canadian Society for Civil Engineering (ASCE-CSCE) Environmental Engineering Conference C2 - 1999/// C3 - Environmental engineering, 1999 : proceedings of ASCE-CSCE National Conference on Environmental Engineering CY - Norfolk, VA DA - 1999/// PY - 1999/// PB - American Society of Civil Engineers ER - TY - CONF TI - Enhancement of Computational Fluid dynamics (CFD) Modeling of Clearwell Performance AU - Peplinski, D. AU - Ducoste, J.J. T2 - North Carolina American Water Works Association / Water Environment Association (NC AWWA/WEA) Conference C2 - 1999/// C3 - Proceedings CY - Asheville, NC DA - 1999/// PY - 1999/// ER - TY - CONF TI - Evaluation of Stacked Secondary Clarifier Design using Computational Fluid Dynamics AU - Ducoste, J.J. AU - Daigger, G.T. AU - Smith, R. T2 - Water Environment Federation Technology Conference C2 - 1999/// C3 - Proceedings Water Environment Federation Technology Conference CY - New Orleans, LA DA - 1999/// PY - 1999/// ER - TY - CONF TI - A Systematic Approach to Reactor Hydraulic Characterization: Part 1 of the Integrated Disinfection Design Framework Protocol AU - Ducoste, J.J. AU - Carlson, K. AU - Bellamy, W, AU - Carlson, M. T2 - American Water Works Association (AWWA )Water Quality and Technology Conference C2 - 1999/// C3 - Proceedings AWWA Water Quality and Technology Conference CY - Tampa, FL DA - 1999/// PY - 1999/// ER - TY - CONF TI - Development of Alternative Solid Waste Management Options Using a Life-Cycle Approach " AU - Barlaz, M.A. T2 - WasteTech99, Environmental Industries Association C2 - 1999/// CY - New Orleans, LA DA - 1999/// PY - 1999/2/1/ ER - TY - SOUND TI - The Effects of Aging and Sorbent Decomposition on the Bioavailability of Toluene and o-Xylene in Solid Waste AU - Barlaz, M.A. AU - Knappe, D.R.U. DA - 1999/// PY - 1999/// ER - TY - CONF TI - A Model to Assess Biofilm Exopolymer Effects on Methane Oxidation in Landfill Cover Soil AU - Hilger, H.A. AU - Liehr, S.K. AU - Barlaz, M.A. T2 - 7th International Waste Management and Landfill Symposium C2 - 1999/// CY - Cagliari, Italy DA - 1999/// PY - 1999/10/4/ ER - TY - RPRT TI - Life Cycle Inventory of a Modern Municipal Solid Waste Landfill AU - Camobreco, V. AU - Repa, E. AU - Ham, R.K. AU - Barlaz, M.A. AU - Felker, M. AU - Rousseau, C. AU - Clark-Balbo, M. AU - Rathle, J. AU - Thorneloe, S. A3 - Environmental Research and Education Foundation DA - 1999/6// PY - 1999/6// PB - Environmental Research and Education Foundation ER - TY - CONF TI - Development of Alternative Solid Waste Management Options with Economic and Environmental Considerations: A Mathematical Modeling Approach AU - Barlaz, M.A. AU - Ranjithan, S.R. AU - Brill, E.D. AU - Dumas, R.D. AU - Harrison, K.W. AU - Solano, E. T2 - 7th International Waste Management and Landfill Symposium C2 - 1999/// CY - Cagliari, Italy DA - 1999/// PY - 1999/10/4/ ER - TY - CONF TI - A Life-Cycle Inventory of a Solid Waste Landfill AU - Barlaz, M.A. AU - Camobreco, V. AU - Coulon, R. AU - Felker, M. AU - Ham, R.K. AU - Rathle, J. AU - Repa, E. AU - Rousseau, C. T2 - 7th International Waste Management and Landfill Symposium C2 - 1999/10/4/ CY - Cagliari, Italy DA - 1999/10/4/ PY - 1999/10/4/ ER - TY - CONF TI - Biological and Chemical Transformations of Hazardous Organic Chemicals During Refuse Decomposition AU - Barlaz, M.A. AU - Sanin, F.D. AU - Knappe, D.R.U. T2 - 7th International Waste Management and Landfill Symposium C2 - 1999/// CY - Cagliari, Italy DA - 1999/// PY - 1999/10/4/ ER - TY - CONF TI - The Fate of Toluene and Dichloroethane in a Superfund Landfill AU - Barlaz, M.A. AU - Sanin, F.D. AU - Knappe, D.R.U. T2 - In Situ and On-Site Bioremediation 5th International Symposium C2 - 1999/// CY - San Diego, CA DA - 1999/// PY - 1999/4/19/ ER - TY - JOUR TI - Transfer and Development Lengths of Carbon Fiber Reinforced Polymer Prestressing Reinforcement AU - Mahmoud, Z. AU - Rizkalla, S. AU - Zaghloul, E. T2 - ACI Structural Journal DA - 1999/7// PY - 1999/7// VL - 96 IS - 4 SP - 594–602 ER - TY - JOUR TI - FRP Extends Service Life of Rehabilitated Infrastructure AU - Rizkalla, S. AU - Labossiére, P. T2 - Canadian Civil Engineer DA - 1999/9// PY - 1999/9// SP - 8–12 ER - TY - JOUR TI - Structural Engineering with FRP-In Canada AU - Rizkalla, S. AU - Labossiére, P. T2 - Concrete International DA - 1999/10// PY - 1999/10// VL - 21 IS - 10 SP - 25–28 ER - TY - JOUR TI - Shear Strengthening of AASHTO Bridge Girders Using CFRP Sheets AU - Hutchinson, R. AU - Rizkalla, S. T2 - ACI Special Publications DA - 1999/11// PY - 1999/11// VL - SP-188 SP - 945–958 ER - TY - JOUR TI - FRP for Shear Reinforcement of Concrete Structures AU - Shehata, E. AU - Morphy, R. AU - Rizkalla, S. T2 - ACI Special Publications DA - 1999/11// PY - 1999/11// VL - SP-188 SP - 157–167 ER - TY - JOUR TI - Design Recommendations for Bridge Deck Slabs Reinforced by FRP AU - Hassan, T. AU - Rizkalla, S. AU - Abdelrahman, A. AU - Tadros, G. T2 - ACI Special Publications DA - 1999/11// PY - 1999/11// VL - SP-188 SP - 313–323 ER - TY - JOUR TI - Identification and Analysis of Coastal Erosion Hazard Areas: Dare and Brunswick Counties, North Carolina AU - Overton, M.F. AU - Grenier, R.R., Jr. AU - Judge, E.K. AU - Fisher, J.S. T2 - Journal of Coastal Research DA - 1999/// PY - 1999/// VL - 28 SP - 69–84 ER - TY - CONF TI - Chance-Constrained Genetic Algorithms AU - Loughlin, D.H. AU - Ranjithan, S. T2 - Genetic and Evolutionary Computation Conference A2 - Banzhaf, W A2 - Daida, J A2 - Eiben, AE A2 - Garzon, MH A2 - Honavar, V C2 - 1999/7/13/ C3 - GECCO-99: Proceedings of the Genetic and Evolutionary Computation Conference CY - Orlando, Florida USA DA - 1999/7/13/ PY - 1999/7/13/ VL - 1 SP - 369–376 PB - Morgan Kaufmann ER - TY - CONF TI - Evaluation of Alternative Penalty Function Implementations in a Watershed Management Design Problem AU - Harrell, L.J. AU - Ranjithan, S. T2 - Genetic and Evolutionary Computation Conference A2 - Banzhaf, W A2 - Daida, J A2 - Eiben, AE A2 - Garzon, M A2 - Honavar, V C2 - 1999/7/13/ C3 - GECCO-99: Proceedings of the Genetic and Evolutionary Computation Conference CY - Orlando, Florida USA DA - 1999/7/13/ PY - 1999/7/13/ VL - 2 SP - 1551–1558 PB - Morgan Kaufmann SN - 978-1-55860-611-1 ER - TY - CONF TI - On the Validation of a Watershed Model AU - Vogel, R.M. AU - Sankarasubramanian, A. T2 - International Union of Geodesy and Geophysics C2 - 1999/8// CY - University of Buckingham, Buckingham, United Kingdom DA - 1999/8// PY - 1999/8// ER - TY - JOUR TI - Linseed Oil-Based Concrete Surface Treatment for Building and Highway Structures in Hong Kong AU - Xie, Y P AU - Kwan, A K H AU - Chan, H C AU - Rizkalla, S H T2 - HKIE Transactions AB - This experimental program investigated the effectiveness of concrete surface treatment using four Canadian linseed oil-based sealants on concrete specimens made from G30/20 and G45/20 concretes, which are typically used for building and highway structures in Hang Kong. The tests were conducted at the University of Hong Kong and the University of Manitoba independently, using samples cost from the same mixes in Hong Kong. A total of more than 500 specimens were tested in each university for salt spray resistance, carbonation, bond strength, dripping and ultra-violet weathering. The results show that the four sealants were capable of penetrating through vertical, upward horizontal and downward horizontal concrete surfaces up to depths of 2.5 mm. All the four sealants significantly enhanced the resistance of G30/20 concrete against salt spray attack and carbonation. The resistance of G45/20 concrete to salt spray was also increased. Up to a duration limit of 500 hours of quick ultra-violet weathering, the treated specimens still demonstrated higher resistance against salt spray attack and carbonation than the untreated ones. However, no conclusion can be made regarding the effect on carbonation resistance of G45/20 concrete, since both the treated and untreated specimens showed no signs of carbonation after the test. DA - 1999/1// PY - 1999/1// DO - 10.1080/1023697x.1999.10667790 VL - 6 IS - 1 SP - 36-41 J2 - HKIE Transactions LA - en OP - SN - 1023-697X 2326-3733 UR - http://dx.doi.org/10.1080/1023697x.1999.10667790 DB - Crossref ER - TY - JOUR TI - Deflection Control of Concrete Beams Pretensioned by CFRP Reinforcements AU - Abdelrahman, Amr A. AU - Rizkalla, Sami H. T2 - Journal of Composites for Construction AB - Use of carbon fiber reinforced polymers (CFRP) reinforcement for prestressing concrete structures introduces a promising solution for deterioration of concrete structures due to corrosion of steel reinforcements. Due to the low elastic modulus and limited strain at failure of CFRP reinforcement, partial prestressing could be the most appropriate approach to enhance deformability and reduce the cost in comparison to fully prestressed concrete structures. For members reinforced or prestressed with fiber reinforced polymers reinforcements, serviceability requirements may be the governing criteria for the design; therefore, deflection under service loading conditions should be well defined. This paper introduces simplified methods to calculate the deflection of beams prestressed by CFRP reinforcement under short-term and repeated loading. It also examines the applicability of current approaches available to calculate the deflection. Based on an experimental program undertaken at the University of Manitoba, bond factors are introduced to account for tension stiffening of concrete beams prestressed by CFRP. A procedure to determine the location of the centroidal axis of cracked prestressed sections is also proposed. The proposed methods for deflection calculation are calibrated using the results obtained from different experimental programs. Design guidelines are proposed to predict the deflection of beams partially prestressed by CFRP reinforcement. DA - 1999/5// PY - 1999/5// DO - 10.1061/(asce)1090-0268(1999)3:2(55) VL - 3 IS - 2 SP - 55-62 J2 - Journal of Composites for Construction LA - en OP - SN - 1090-0268 1943-5614 UR - http://dx.doi.org/10.1061/(asce)1090-0268(1999)3:2(55) DB - Crossref ER - TY - CONF TI - Comparisons of Climate Elasticity of Streamflow in the United States AU - Vogel, Richard M. AU - Sankarasubramanian, A. AU - Limbrunner, James F. AU - Wilson, Ian T2 - 29th Annual Water Resources Planning and Management Conference AB - The sensitivity of streamflow to climate is investigated by calculating precipitation and potential evapotranspiration elasticity of streamflow for 1,447 watersheds in the United States. A unique dataset of streamflow and climate time-series is constructed which accounts for the complex spatial variations in climate across the U.S. Average annual values of streamflow, precipitation, temperature, and potential evapotransiration are used to estimate climate elasticity of the long-term mean streamflow using a nonparametric (databased) approach, a regional regression approach and a water balance modeling approach. Comparisons are provided with nine previous climate change studies based on monthly water balance models and soil moisture accounting models Our results suggest that streamflow is more sensitive to changes in precipitation than to changes in potential evapotranspiration. Streamflow is particularly sensitive to both precipitation and potential evapotranspiration in the midwestern regions of the U.S. Difficulties with both the concept of elasticity and with its estimation are discussed and ongoing research is summarized. Climate elasticities derived from detailed monthly simulation experiments agree nicely with the simpler annual approaches outlined in this study. C2 - 1999/6/3/ C3 - WRPMD'99 DA - 1999/6/3/ DO - 10.1061/40430(1999)251 PB - American Society of Civil Engineers SN - 9780784404300 UR - http://dx.doi.org/10.1061/40430(1999)251 DB - Crossref ER - TY - JOUR TI - Investigation and comparison of sampling properties of L-moments and conventional moments AU - Sankarasubramanian, A. AU - Srinivasan, K. T2 - Journal of Hydrology AB - The first part of this article deals with fitting of regression equations for the sampling properties, variance of L-standard deviation (l2), and bias and variance of L-skewness (t3), based on Monte-Carlo simulation results, for generalised Normal (Lognormal-3) and Pearson-3 distributions. These fitted equations will be useful in formulating goodness-of-fit test statistics in regional frequency analysis. The second part presents a comparison of the sampling properties between L-moments and conventional product moments for generalised Normal, generalised Extreme Value, generalised Pareto and Pearson-3 distributions, in a relative form. The comparison reveals that the bias in L-skewness is found to be insignificant up to a skewness of about 1.0, even for small samples. In case of higher skewness, for a reasonable sample size of 30, L-skewness is found to be nearly unbiased. However, the conventional skewness is found to be significantly biased, even for a low skewness of 0.5 and a reasonable sample size of 30. The overall performance evaluation in terms of “Relative-RMSE in third moment ratio” reveals that conventional moments are preferable at lower skewness, particularly for smaller samples, while L-moments are preferable at higher skewness, for all sample sizes. This point is illustrated through an application that seeks to obtain an appropriate regional flood frequency distribution for the 98 catchment areas located in the central region of India, spread over six hydrometeorologic subzones. DA - 1999/5// PY - 1999/5// DO - 10.1016/s0022-1694(99)00018-9 VL - 218 IS - 1-2 SP - 13-34 J2 - Journal of Hydrology LA - en OP - SN - 0022-1694 UR - http://dx.doi.org/10.1016/s0022-1694(99)00018-9 DB - Crossref KW - sampling methods KW - generalised normal KW - Pearson distributions KW - L-moments KW - L-skewness ER - TY - JOUR TI - Intelligent Sensing for Innovative Bridges AU - Shehata, Emile AU - Rizkalla, Sami T2 - Journal of Intelligent Material Systems and Structures AB - This paper discusses two types of fiber optic sensors used for monitoring highway bridges in Manitoba, Canada. The first, the Taylor Bridge, is the longest smart bridge built in North America and was completed in 1997. Four girders, large portions of the deck slab and the barrier wall are reinforced with carbon and glass fiber reinforced polymer (FRP) materials. The bridge is remotely monitored using fiber optic sensors embedded in the girders, the deck slab and the barrier wall to provide continuous information on the health and structural performance of the bridge. Signals obtained from the optical sensors are transmitted through a telephone line, thereby allowing an office-based engineer to monitor the stresses and strains via a computer anywhere in the world. The paper discusses the expert system program used to reduce the data collected from the bridge into engineering information which can be used to assess the performance of the FRP material and the behavior of the bridge. The second, the Norwood Bridge, is another innovative bridge also built in Winnipeg, Manitoba. The bridge is a complex precast reinforced concrete structure including an innovative mechanical connection at the supports to provide continuity. Monitoring of the bridge was requested by the owner, the City of Winnipeg, to verify structural behavior during different stages of construction and operation. A different type of fiber optic system was used in this bridge. Both the Taylor and the Norwood Bridge projects were undertaken by the Network of Centres of Excellence on Intelligent Sensing for Innovative Structures (ISIS Canada) which was able to provide the valuable link between the emerging new technology in structural remote monitoring and the construction industry. DA - 1999/4// PY - 1999/4// DO - 10.1177/1045389x9901000406 VL - 10 IS - 4 SP - 304-313 J2 - Journal of Intelligent Material Systems and Structures LA - en OP - SN - 1045-389X 1530-8138 UR - http://dx.doi.org/10.1177/1045389x9901000406 DB - Crossref ER - TY - JOUR TI - Performance of Bridge Timber Ties Under Static and Fatigue Loading AU - Soudki, Khaled A. AU - Rizkalla, Sami H. AU - Uppal, A. Shakoor T2 - Journal of Bridge Engineering AB - This study is in response to the dramatic increase in railway car axle loads that has occurred over the last 50 years. The paper presents the results of an experimental program undertaken to evaluate the structural performance of treated timber bridge ties under different railway car load levels. A portion of a prototype bridge deck, consisting of eight prototype timber bridge ties, was tested under various loading and support configurations to determine the axle load distribution. The serviceability of the treated bridge timber ties was evaluated based on the fatigue strength of eight prototype timber ties under different load levels. A theoretical model, based on energy principles, was developed to predict the axle load distribution to the ties for different span configurations. The model compares well with the measured test results and it complies with the American Railway Engineering Association requirements. DA - 1999/11// PY - 1999/11// DO - 10.1061/(asce)1084-0702(1999)4:4(263) VL - 4 IS - 4 SP - 263-268 J2 - Journal of Bridge Engineering LA - en OP - SN - 1084-0702 1943-5592 UR - http://dx.doi.org/10.1061/(asce)1084-0702(1999)4:4(263) DB - Crossref ER - TY - JOUR TI - Life Cycle Management of Municipal Solid Waste AU - Weitz, Keith AU - Barlaz, Morton AU - Ranjithan, Ranji AU - Brill, Downey AU - Thorneloe, Susan AU - Ham, Robert T2 - The International Journal of Life Cycle Assessment DA - 1999/7// PY - 1999/7// DO - 10.1007/bf02979496 VL - 4 IS - 4 SP - 195-201 J2 - Int. J. LCA LA - en OP - SN - 0948-3349 1614-7502 UR - http://dx.doi.org/10.1007/bf02979496 DB - Crossref ER - TY - JOUR TI - Representation of Compacted Clay Minifabric Using Random Networks AU - Atuahene, Frank AU - Chen, J. AU - Gabr, M. A. AU - Reddi, Lakshmi N. AU - Thangavadivelu, S. T2 - Journal of Geotechnical and Geoenvironmental Engineering DA - 1999/4// PY - 1999/4// DO - 10.1061/(asce)1090-0241(1999)125:4(335.2) VL - 125 IS - 4 SP - 335-337 ER - TY - JOUR TI - Methods for characterizing variability and uncertainty: Comparison of bootstrap simulation and likelihood-based approaches AU - Frey, H.C. AU - Burmaster, D.E. T2 - Risk Analysis DA - 1999/// PY - 1999/// DO - 10.1023/A:1006962412150 VL - 19 IS - 1 SP - 109-130 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0032940312&partnerID=MN8TOARS KW - variability KW - uncertainty KW - maximum likelihood KW - bootstrap simulation KW - Monte Carlo simulation ER - TY - JOUR TI - Simultaneous oligonucleotide probe hybridization and immunostaining for in situ detection of Gordona species in activated sludge AU - Oerther, DB AU - Reyes, FL AU - Hernandez, M AU - Raskin, L T2 - FEMS Microbiology Ecology AB - Oligonucleotide probes targeting ribosomal RNA can be designed with high specificity to target microbial populations at different phylogenetic levels if the cellular abundance of ribosomal RNA is sufficiently high. In contrast, polyclonal antibody probes cannot be produced with the same specificity for various phylogenetic groups, but they have the potential to detect slow growing microorganisms, populations with low metabolic activities, or even non-viable cells. We combined a polyclonal antibody stain with a ribosomal RNA targeted oligonucleotide probe for the single cell detection of species of the genus Gordona. Gordona species typically require long generation times, often exhibit filamentous growth, and are commonly encountered in activated sludge foams. Our results suggest that the ribosomal RNA content of individual cells of Gordona in activated sludge is highly variable. Therefore, the combined use of an immunostain and an oligonucleotide probe targeting ribosomal RNA can determine the identity of single cells and provide an approximation of their activity. This approach should result in improved detection limits while maintaining high specificity. DA - 1999/// PY - 1999/// DO - 10.1016/S0168-6496(99)00005-7 VL - 29 IS - 2 SP - 129-136 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0032776672&partnerID=MN8TOARS ER - TY - JOUR TI - Simultaneous oligonucleotide probe hybridization and immunostaining for in situ detection of Gordona species in activated sludge AU - Oerther, DB AU - Reyes, FL AU - Hernandez, M AU - Raskin, L T2 - Fems Microbiology Ecology DA - 1999/// PY - 1999/// VL - 29 IS - 2 SP - 129-136 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000081005100002&KeyUID=WOS:000081005100002 ER - TY - JOUR TI - Interfacing phylogenetic oligonucleotide probe hybridizations with representations of microbial populations and specific growth rates in mathematical models of activated sludge processes AU - Oerther, DB AU - Reyes, FL AU - Raskin, L T2 - Water Science and Technology AB - Accurate estimates of microbial population concentrations and the direct, in situ determination of kinetic parameters could improve the calibration and validation of existing mechanistic mathematical models of biological nutrient removal activated sludge systems. Oligonucleotide probe hybridizations show promise for measuring concentrations and in situ specific growth rates of microbial populations. The most common targets for oligonucleotide probes are the phylogenetically conserved ribosomal RNA molecules. Recent advances in hybridization techniques have improved the quantitative nature of ribosomal RNA based assays. However, correlations between concentrations of “theoretical” microbial populations predicted by mechanistic models and quantitative information obtained with oligonucleotide probe hybridizations are not yet developed. Future work should develop such correlations, while addressing the limitations of the molecular assays. DA - 1999/// PY - 1999/// DO - 10.1016/S0273-1223(98)00771-9 VL - 39 IS - 1 SP - 11-20 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000078379000003&KeyUID=WOS:000078379000003 KW - activated sludge KW - biological nutrient removal KW - mechanistic mathematical models KW - oligonucleotide probes KW - ribosomal RNA ER - TY - JOUR TI - Formal specification of concurrent systems T2 - Advances in Engineering Software DA - 1999/// PY - 1999/// VL - 30 IS - 3 SP - 211-224 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0033098338&partnerID=MN8TOARS ER - TY - CONF TI - Flushing of ethylbenzene?contaminated clay using Tergitol AU - Gabr, M. A. AU - Sabodish, M. C2 - 1999/// C3 - Environmental engineering, 1999 :proceedings of ASCE-CSCE National Conference on Environmental Engineering : July 25-28, 1999, Norfolk, Virginia DA - 1999/// PB - Reston, Va. : American Society of Civil Engineers SN - 9780784404355 ER - TY - JOUR TI - Characteristics of urethane-grouted sand for in situ seepage control AU - Gabr, M. A. T2 - ASCE Geotechnical Special Publication DA - 1999/// PY - 1999/// VL - 90 ER - TY - CONF TI - Well injection depth extraction (WIDE) for subsurface mixed waste flushing AU - Quaranta, J. AU - Gabr, M. A. AU - Sabodish, M. AU - Gates, K. AU - Ganz, J. C2 - 1999/// C3 - Proceedings of the environmental industry partnerships conferences DA - 1999/// PB - Morgantown, WV: National Energy Technology Laboratory ER - TY - JOUR TI - Mixture design and accelerated laboratory performance evaluation of unmodified and crumb rubber modified mixtures AU - Natu, G. AU - Tayebali, A. A T2 - Journal of the Association of Asphalt Paving Technologists DA - 1999/// PY - 1999/// VL - 68 SP - 192-221 ER - TY - RPRT TI - The Conceptual Universe database schema: Design issues and decisions AU - Rasdorf, W. A3 - Raleigh, N.C.: North Carolina Department of Transportation DA - 1999/// PY - 1999/// PB - Raleigh, N.C.: North Carolina Department of Transportation ER - TY - RPRT TI - A spatial and attribute database schema design for traffic survey data AU - Rasdorf, W. A3 - Raleigh, N.C.: North Carolina Department of Transportation DA - 1999/// PY - 1999/// PB - Raleigh, N.C.: North Carolina Department of Transportation ER - TY - CHAP TI - Quality of service for interrupted flow facilities in highway capacity manual 2000 AU - Milazzo, J. S. AU - Rouphail, N. AU - Hummer, J. AU - Allen, P. T2 - Highway capacity, quality of service, and traffic flow and characteristics CN - TE7 .H5 no. 1678 PY - 1999/// SP - 25-31 PB - Washington, D.C.: National Academy Press SN - 0309071046 ER - TY - JOUR TI - Design of break away walls under wave action AU - Yeh, S. C. AU - Rogers, S. M. AU - Tung, C. C. AU - Kasal, B T2 - Journal of Structural Engineering (New York, N.Y.) DA - 1999/// PY - 1999/// VL - 25 IS - 10 SP - 1162-1169 ER - TY - JOUR TI - Comparison of strength and construction tolerances in concrete AU - Cutshall, B. E. AU - Leming, M. L. AU - Johnston, David 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 - 1999/// PY - 1999/// DO - 10.14359/685 VL - 96 IS - 4 SP - 491–494 ER - TY - JOUR TI - Model for lightweight concrete columns confined by either single hoops or interlocking double spirals AU - Khaloo, A. R. AU - El-Dash, K. M. AU - Ahmad, S. H. T2 - ACI Structural Journal DA - 1999/// PY - 1999/// VL - 96 IS - 6 SP - 883-890 ER - TY - CONF TI - Analysis of the morphology of Oregon Inlet, NC since the construction of the terminal groin AU - Joyner, B. P. AU - Overton, M. F. AU - Fisher, J. S. C2 - 1999/// C3 - Coastal engineering 1998: Conference proceedings, June 22-26 1998, Falconer Hotel, Copenhagen, Denmark CN - TC203.5 .C6184 1999 DA - 1999/// PB - Reston, Va.: American Society of Civil Engineers ER - TY - CHAP TI - Evaluation of superpave repeated shear at constant height test to predict rutting potential of mixes: Performance of three pavement sections in North Carolina AU - Tayebali, A. A. AU - Khosla, N. P. AU - Waller, H. F. T2 - Hot-mix asphalt mixtures AB - The repeated shear at constant height (RSCH) test to predict the rutting potential of asphalt aggregate mixes based on field performance of pavement sections in North Carolina has been evaluated. Three pavement sections in Buncombe, McDowell, and Montgomery counties were selected based on the degree of rutting severity experienced after several years in service. The pavement section in Buncombe County showed no rutting, whereas those in McDowell and Montgomery counties showed light and severe rutting distress, respectively. Results of this study indicated that the RSCH test can clearly identify the well-performing versus poorly performing mixes (i.e., Buncombe versus Montgomery counties). Although previous studies in which the French pavement rutting tester and the Georgia loaded-wheel tester were used indicated early rutting of the pavement in Buncombe County, the RSCH test indicated that the mix was not susceptible to excessive rutting—in line with field experience of no significant pavement distress observed in this pavement. For Montgomery County, the RSCH test clearly showed that the mix was susceptible to excessive rutting with the wheelpath cores distinctly showing potential for tertiary flow—in agreement with experience of significant rutting distress observed in this pavement. CN - TE7 .H5 no. 1681 PY - 1999/// DO - 10.3141/1681-12 SP - 97 PB - Washington, DC: National Academy Press SN - 0309071070 ER - TY - JOUR TI - Flow pattern analysis of constructed wetlands treating landfill leachate AU - Rash, J. K. AU - Liehr, S. K. T2 - Water Science and Technology AB - Three series of tracer studies were performed on three constructed wetlands at the New Hanover County Landfill near Wilmington, North Carolina, USA. One vegetated free water surface wetland (FWS-R), one vegetated subsurface flow wetland (SSF-R), and one unvegetated control subsurface flow wetland (SSF-C) were studied. A conservative tracer, lithium chloride, was used to study the chemical reactor behavior of these wetlands under normal operating conditions. Results indicated that short-circuiting is quite common in SSF wetlands, while FWS wetlands are well-mixed and not as subject to short-circuiting. These results were obtained from and reinforced with tracer measurements at interior points in these wetlands, analysis of residence time distributions from two different formulations, and the construction of residence volume distributions. The short-circuiting in the SSF wetlands can be attributed to the following: (1) Vertical mixing is inhibited by a combination of physical barriers and density gradients caused by rainfall and runoff dilution of the upper layer; and (2) Leachate is drawn from the bottom of the wetland, causing it to further prefer a flow path along the bottom. DA - 1999/// PY - 1999/// DO - 10.1016/S0273-1223(99)00450-3 VL - 40 IS - 3 SP - 309-315 ER - TY - JOUR TI - Behavior of breakaway walls under wave action AU - Yeh, S. C. AU - Rogers, S. M. AU - Tung, C. C. AU - Kasal, B. T2 - Journal of Structural Engineering (New York, N.Y.) AB - In coastal areas residential houses are often built on piles. The space below the first floor and the ground is sometimes enclosed. The enclosure walls are constructed to break away under severe wave-induced forces so that the forces transmitted through the breakaway walls to the building's foundation are not unduly large. Successful design of a breakaway wall therefore depends critically on knowledge of the ultimate strength of nailed fasteners and wall material and of the behavior of breakaway wall under wave-induced forces. In this research, laboratory tests were performed to determine the ultimate strength of nailed connections. Behavior and failure modes of breakaway walls from water waves were studied analytically and in a series of laboratory wave channel tests. DA - 1999/// PY - 1999/// DO - 10.1061/(asce)0733-9445(1999)125:10(1162) VL - 125 IS - 10 SP - 1162-1169 ER - TY - JOUR TI - Water quality prediction and probability network models AU - Reckhow, KH T2 - CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES AB - It is a common strategy in surface water quality modeling to attempt to remedy predictive inadequacies by incorporating additional mechanistic detail into the model. This approach reflects the reasonable belief that enhanced scientific understanding of basic processes can be used to improve predictive modeling. However, nature is complex, and even the most detailed simulation model is extremely simple in comparison. At some point, additional detail exceeds our ability to simulate and predict with reasonable error levels. In those situations, an attractive alternative may be to express the complex behavior probabilistically, as in statistical mechanics, for example. This viewpoint is the basis for consideration of Bayesian probability networks for surface water quality assessment and prediction. To begin this examination of Bayes nets, some simple water quality examples are used for the illustration of basic ideas. This is followed by discussion of a set of proposed probability network models for the eutrophication of the Neuse River estuary in North Carolina. The presentation concludes with consideration of applications and opportunities for Bayes nets in predictive water quality modeling. DA - 1999/7// PY - 1999/7// DO - 10.1139/cjfas-56-7-1150 VL - 56 IS - 7 SP - 1150-1158 SN - 0706-652X ER - TY - JOUR TI - Reflection of oblique waves by currents: analytical solutions and their application to numerical computations AU - Shyu, J. H. AU - Tung, C. C. T2 - Journal of Fluid Mechanics DA - 1999/// PY - 1999/// VL - 396 IS - 1999 Oct. 10 SP - 143-182 ER - TY - JOUR TI - Exopolysaccharide control of methane oxidation in landfill cover soil AU - Hilger, H. A. AU - Liehr, S. K. AU - Barlaz, Morton T2 - Journal of Environmental Engineering (New York, N.Y.) AB - The study objective was to examine whether a relationship exists between the accumulation of exopolymeric substances (EPS) in landfill cover soil and the gradual decline in biotic methane oxidation observed in laboratory soil columns sparged with synthetic landfill gas. A mathematical model that combined multicomponent gas diffusion along the vertical axis of the columns with biotic methane oxidation was used to predict vertical gas gradients in the columns. An initial trial assumed methane oxidizers were embedded in a thin base layer of biofilm coating the soil, and the model predictions fit experimental data from soil columns early in their operating period. A second trial modeled the same system with a thick EPS layer coating the base biofilm and limiting diffusion of gases into and out of the cells. Predictions from the latter trials fit experimental data from soil columns later in their operating period when lower methane consumption rates were observed. The model results suggest that EPS accumulation may regulate methane oxidation rates in landfill covers. DA - 1999/// PY - 1999/// DO - 10.1061/(asce)0733-9372(1999)125:12(1113) VL - 125 IS - 12 SP - 1113–1123 ER - TY - JOUR TI - Techniques for automated extraction of roadway inventory features from high-resolution satellite imagery AU - Karimi, H. A. AU - Dai, X. L. AU - Khattak, A. J. AU - Khorram, S. AU - Hummer, J. E. T2 - Geocarto International AB - Abstract The emergence of high‐resolution satellite imagery is attracting new applications which can take advantage of remotely sensed data for mapping, inventory, and change detection. Automated collection of roadway inventory features is one such application. To this end, it is important to investigate the performance of conventional feature extraction techniques when applied to high‐resolution images and to develop new techniques for extraction of roadway features using one‐meter, or higher, resolution imagery. In this paper, classification‐ based and edge detection‐based techniques potential for automated extraction of roadway features from high‐resolution satellite imagery are described, tested, and evaluated. Of possible techniques, the applicability of conventional classification algorithms, the Thin and Robust Zero‐Crossing edge detector based on the Laplacian of Gaussian operator, and seeded region growing segmentation is investigated. The advantages and disadvantages of each technique for extracting roadway features are discussed. These techniques are applied to one‐meter resolution images (currently simulated using one‐meter aerial photos) and the experimental results are presented. DA - 1999/// PY - 1999/// DO - 10.1080/10106049908542099 VL - 14 IS - 2 SP - 5-16 ER - TY - JOUR TI - Roadway feature extraction and delineation fron high-resolution satellite imagery AU - Dai, X. L. AU - Karimi, H. A. AU - Khorram, S. AU - Khattak, A. J. AU - Hummer, J. E. T2 - EOM DA - 1999/// PY - 1999/// IS - 1999 May SP - 34-37 ER - TY - JOUR TI - Molecular structure-property relationships for electron-transfer rate attenuation in redox-active core dendrimers AU - Gorman, CB AU - Smith, JC AU - Hager, MW AU - Parkhurst, BL AU - Sierzputowska-Gracz, H AU - Haney, CA T2 - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY AB - Two series of redox-active, iron−sulfur core dendrimers of the general structure (nBu4N)2[Fe4S4(S-Dend)4] (Dend = dendrons of generations 1 through 4) were prepared. Heterogeneous electron-transfer rate constants indicated that the rigid series of dendrimers were more effective at attenuating the rate of electron transfer than were the flexible series of dendrimers. These results were rationalized using computationally derived models which indicated an offset and mobile iron−sulfur core in the flexible series of molecules and a more central and relatively immobile iron−sulfur core in the rigid series of molecules. Further consideration of these data indicated that, while the dendrimers containing rigid ligands had better encapsulated redox cores for a given molecular weight, these molecules had higher electron-transfer rates for a given molecular radius. DA - 1999/11/3/ PY - 1999/11/3/ DO - 10.1021/ja990875h VL - 121 IS - 43 SP - 9958-9966 SN - 1520-5126 ER - TY - JOUR TI - Methods for characterizing variability and uncertainty: Comparison of bootstrap simulation and likelihood-based approaches AU - Frey, H. Christopher AU - Burmaster, D. E. T2 - Risk Analysis AB - Variability arises due to differences in the value of a quantity among different members of a population. Uncertainty arises due to lack of knowledge regarding the true value of a quantity for a given member of a population. We describe and evaluate two methods for quantifying both variability and uncertainty. These methods, bootstrapsimulation and a likelihood‐based method, are applied to three datasets. The datasetsinclude a synthetic sample of 19 values from a Lognormal distribution, a sample of nine values obtained from measurements of the PCB concentration in leafy produce, and asample of five values for the partitioning of chromium in the flue gas desulfurization system of coal‐fired power plants. For each of these datasets, we employ the two methods to characterize uncertainty in the arithmetic mean and standard deviation, cumulative distribution functions based upon fitted parametric distributions, the 95th percentile of variability, and the 63rd percentile of uncertainty for the 81st percentile of variability. The latter is intended to show that it is possible to describe anypoint within the uncertain frequency distribution by specifying an uncertainty percentile and a Variability percentile. Using the bootstrap method, we compare results based upon use of the method of matching moments and the method of maximum likelihood for fitting distributions to data. Our results indicate that with only 5‐19 data pointsas in the datasets we have evaluated, there is substantial uncertainty based upon random sampling error. Both the boostrap and likelihood‐based approaches yield comparable uncertainty estimates in most cases. DA - 1999/// PY - 1999/// DO - 10.1111/j.1539-6924.1999.tb00393.x VL - 19 IS - 1 SP - 109–130 ER - TY - JOUR TI - 7th International Symposium on Current Issues Related to Nuclear Power Plant Structures, Equipment and Piping - Raleigh, North Carolina, USA 1-4 December 1998 - Preface AU - Tung, C. C. D. T2 - Nuclear Engineering and Design DA - 1999/// PY - 1999/// VL - 192 IS - 2-3 SP - v ER - TY - JOUR TI - A comparison of physical properties of synthetic sludge with activated sludge AU - Sanin, FD AU - Vesilind, PA T2 - WATER ENVIRONMENT RESEARCH AB - Conducting physical and chemical tests with activated sludge is difficult because of its constantly changing properties. To overcome this difficulty a synthetic sludge that physically and chemically resembles activated sludge was created. In this study, the physical properties of synthetic sludge were examined and compared to those of activated sludge, including particle size, filterability by specific resistance to filtration and capillary suction time, conditioning with two polyelectrolytes, floc strength, rheological properties, and residual turbidity after settling. Results of this study show striking similarities between activated sludge and synthetic sludge. Filterabilities of both sludges are almost identical. A medium‐molecular‐weight, medium‐charge‐density, cationic polymer is effective in conditioning both sludges at approximately the same dose. Activated sludge is found to have stronger flocs than synthetic sludge. However, both sludges seem to have flocs stronger than some loose and weak flocs reported in the literature. Rheological behavior in terms of apparent viscosity of the two sludges is similar. The average particle size of activated sludge is found to be slightly larger than that of synthetic sludge. Also, synthetic sludge has a higher residual turbidity than activated sludge. These differences are explained by the fact that the synthetic sludge is lacking filamentous microorganisms that form the backbone of a floc structure in activated sludge. Even though there are some differences in properties, because its overall behavior is close to that of activated sludge, synthetic sludge can be used as a surrogate material for activated sludge when reproducibility in testing is necessary. DA - 1999/// PY - 1999/// DO - 10.2175/106143098X121897 VL - 71 IS - 2 SP - 191-196 SN - 1061-4303 KW - synthetic sludge KW - filterability KW - floc strength KW - particle size KW - rheology KW - turbidity ER - TY - JOUR TI - Variability of seismic response of soils using stochastic finite element method AU - Rahman, MS AU - Yeh, CH T2 - SOIL DYNAMICS AND EARTHQUAKE ENGINEERING AB - The evaluation of seismic response of soil sites constitutes an important problem with respect to groundmotion amplification and soil instability because of liquefaction. The base motion generated during earthquake is a random process. In addition, the soil sites are usually homogenous with randomly varying characteristics. The uncertainties associated with the input motion and site characteristics may lead to a wide range of variability of the site response. In this paper, a Monte-Carlo based stochastic finite element method is used to study the variability of seismic response. DA - 1999/4// PY - 1999/4// DO - 10.1016/S0267-7261(98)00031-1 VL - 18 IS - 3 SP - 229-245 SN - 0267-7261 KW - seismic response KW - Monte-Carlo ER - TY - CHAP TI - The bases of effective coordination in decentralized multi-agent systems AU - Rustogi, S. K. AU - Singh, M. P. T2 - Intelligents Agents V: Agent theories, architectures, and languages AB - Coordination isa recurring theme in multiagent systems design.We consider the problem of achieving coordination in a system where the agents make autonomous decisions based solely on local knowledge.An open theoretical issue is what goes into achieving effective coordination? There is some folklore about the importance of the knowledge held by the different agents,but the rest of the rich agent landscape has not been explored in depth.The present paper seeks to delineate the different components of an abstract architecture for agents that influence the effectiveness of coordination.Specifically,it proposes that the extent of the choices available to the agents as well as the extent of the knowledge shared by them are both important for understanding coordination in general.These lead to a richer view of coordination that supports a more intuitive set of claims.This paper supports its conceptual conclusions with experimental results based on simulation. CN - [Electronic resource] PY - 1999/// DO - 10.1007/3-540-49057-4_10 VL - 1555 SP - 149-161 PB - Berlin; New York: Springer SN - 3540657134 ER - TY - JOUR TI - Production of non-methane organic compounds during refuse decomposition in a laboratory-scale landfill AU - Thomas, C. L. AU - Barlaz, Morton T2 - Waste Management & Research AB - The presence of non-methane organic compounds (NMOCs) in landfill gas is well documented. However, there is little understanding of the degree to which the production of NMOCs should be attributed to the volatilization of household hazardous waste as opposed to intermediates of the anaerobic decomposition of the major cellulosic components of municipal solid waste. The objectives of this study were: (1) to compare the NMOC yields for decomposed refuse, fresh residential refuse, and a synthetic refuse; and (2) to evaluate the source of NMOCs emitted during refuse decomposition. Replicate 2-1 reactors were filled with shredded residential refuse expected to contain household hazardous waste, synthetic refuse containing no hazardous constituents, and control reactors with decomposed refuse only. Anaerobic decomposition of each refuse was initiated with a seed of decomposed refuse, and the reported methane and NMOC yields were corrected for that attributable to the seed. The NMOC yields from the seed, synthetic refuse, and residential refuse were comparable (0.62 to 1.01 X 10 -4 g NMOC (dry g) -1 , suggesting that the volatilization of hazardous organic compounds is not the sole source of NMOCs in landfill gas and that anaerobic biodegradation intermediates also contribute to NMOCs. DA - 1999/// PY - 1999/// DO - 10.1177/0734242X9901700306 VL - 17 IS - 3 SP - 205–211 ER - TY - JOUR TI - Life-cycle inventory of a modern municipal solid waste landfill AU - Camobreco, V AU - Ham, R AU - Barlaz, M AU - Repa, E AU - Felker, M AU - Rousseau, C AU - Rathle, J T2 - WASTE MANAGEMENT & RESEARCH AB - The Environmental Research and Education Foundation (EREF), in conjunction with Ecobalance and researchers from the University of Wisconsin and North Carolina State, is nearing completion of a comprehensive 2-year project on the life-cycle inventory (LCI) of a modern municipal solid waste (MSW) landfill. Data for the model came from both primary (over 100 landfills world-wide) and secondary data sources. Partners in the project included waste management companies from North America and Europe (including Waste Management Inc., SITA and CREED). In addition to the landfill LCI model, the project also includes the development of a software tool. The final report will provide a sound basis for assessing, on a life-cycle basis, the emissions and resource consumption associated with a modern MSW landfill. The model and report can be used to assess the importance of: (1) the various stages in the life-cycle system; (2) the time horizon selected; and (3) the air and water management techniques selected. DA - 1999/12// PY - 1999/12// DO - 10.1034/j.1399-3070.1999.00079.x VL - 17 IS - 6 SP - 394-408 SN - 0734-242X KW - landfill KW - life-cycle inventory (LCI) KW - waste management, municipal solid waste ER - TY - JOUR TI - Interconversion between relaxation modulus and creep compliance for viscoelastic solids AU - Park, S. W. AU - Kim, Y. R. T2 - Journal of Materials in Civil Engineering AB - Methods of interconversion between relaxation modulus and creep compliance for linear viscoelastic materials are discussed and illustrated using data from asphalt concrete. Existing methods of approximate interconversion are reviewed and compared for their approximating schemes. A new approximate interconversion scheme that uses the local log-log slope of the source function is introduced. The new scheme is based on the concept of equivalent time determined by rescaling the physical time. The rescaling factor, which can be interpreted as a shift factor on a logarithmic time axis, is dictated by the local slope of the source function on log-log scales. The unknown target function at a given time is obtained by taking the reciprocal of the source function evaluated at an equivalent time. Although the method is developed using a mathematical relationship based on the power-law representations of relaxation modulus and creep compliance, the method is not limited to material functions characterized by power-laws but can be applied to general, non-power-law material functions as long as the relevant material behaviors are broadband and smooth on logarithmic scales. The new method renders good results especially when the log-log slope of the source function varies smoothly with logarithmic time. DA - 1999/// PY - 1999/// DO - 10.1061/(ASCE)0899-1561(1999)11:1(76) VL - 11 IS - 1 SP - 76-82 ER - TY - JOUR TI - Ultimate capacity of nailed connections for design of breakaway walls AU - Yeh, S. C. AU - Kasal, B. AU - Tung, C. C. AU - Rogers, S. M. T2 - Forest Products Journal DA - 1999/// PY - 1999/// VL - 49 IS - 10 SP - 76-81 ER - TY - JOUR TI - Discrete element modeling of shock compression of hexagonal boron nitride powder with and without copper addition AU - Horie, Y AU - Yano, K T2 - JOURNAL OF MATERIALS PROCESSING TECHNOLOGY AB - A multi-physics, discrete element computer code called DM2 was used to model shock compression of hexagonal boron nitride (hBN) powder at the particle level. Included in this analysis are an anisotropic property of powder grains and heat conduction between hBN and copper particles. Results confirm the earlier observations that the effects of copper are to increase shock pressure and to act as a heat sink to cool BN grains. But, the simulation also reveals that the shock processing at the particle level is far more complex than those suggested in the literature and that the interpretation of process parameters based on macroscopic conditions requires caution. DA - 1999/1/1/ PY - 1999/1/1/ DO - 10.1016/S0924-0136(98)00272-6 VL - 85 IS - 1-3 SP - 109-114 SN - 0924-0136 KW - shock processing KW - hBN KW - discrete element modeling ER - TY - JOUR TI - Atrazine removal by preloaded GAC AU - Knappe, DRU AU - Snoeyink, VL AU - Roche, P AU - Prados, MJ AU - Bourbigot, MM T2 - JOURNAL AMERICAN WATER WORKS ASSOCIATION AB - Utilities can use predictions of remaining GAC life to develop a GAC regeneration or replacement schedule. The effect of granular activated carbon (GAC) service time on the remaining life of GAC adsorbers that are exposed to periodic pollutant episodes was evaluated. Equilibrium and kinetic parameters describing the adsorption of atrazine were determined for GAC that had been preloaded with background organic matter (BOM) for as long as 25 months. Furthermore, atrazine removal was measured in pilot tests employing GAC that had been preloaded for five and 20 months. Isotherm data showed that (1) preloaded BOM sharply reduced the remaining adsorption capacity of GAC for atrazine, (2) competitive adsorption was not important on the tested preloaded GAC samples, and (3) use of pulverized preloaded GAC led to an overestimate of remaining adsorption capacity. Preloading had the greatest effect on GAC capacity; adsorption kinetics were not affected as severely. The homogeneous surface diffusion model was used to predict atrazine removal in pilot tests and to predict remaining GAC life. For the given adsorbent and background water, remaining life predictions for atrazine removal are presented for scenarios that may be typical for utilities in the midwestern United States and in western Europe. DA - 1999/10// PY - 1999/10// DO - 10.1002/j.1551-8833.1999.tb08719.x VL - 91 IS - 10 SP - 97-109 SN - 0003-150X ER - TY - JOUR TI - A neural network model for liquefaction-induced horizontal ground displacement AU - Wang, J AU - Rahman, MS T2 - SOIL DYNAMICS AND EARTHQUAKE ENGINEERING AB - The horizontal ground displacement generated by seismically induced liquefaction is known to produce significant damage to engineered structures. A backpropagation neural network model is developed to predict the horizontal ground displacements. A large database containing the case histories of lateral spreads observed in eight major earthquakes is used. The results of this study indicate that the neural network model serves as a reliable and simple predictive tool for the amount of horizontal ground displacement. As more data become available, the model itself can be improved to make more accurate displacement prediction for a wider range of earthquake and site conditions. DA - 1999/12// PY - 1999/12// DO - 10.1016/S0267-7261(99)00027-5 VL - 18 IS - 8 SP - 555-568 SN - 0267-7261 KW - neural network KW - multiple linear regression KW - models KW - displacement KW - free face KW - ground slope KW - free face ratio KW - liquefaction ER - TY - JOUR TI - Slurry infiltrated mat concrete (SIMCON)-based shear retrofit of reinforced concrete members AU - Krstulovic-Opara, N. AU - Al-Shannag, M. J. T2 - ACI Structural Journal DA - 1999/// PY - 1999/// VL - 96 IS - 1 SP - 105-114 ER - TY - JOUR TI - Shear and flexural behavior of lightweight concrete bridge columns in seismic regions AU - Kowalsky, M. J. AU - Priestley, M. J. N. AU - Seible, F. 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 - 1999/// PY - 1999/// DO - 10.14359/605 VL - 96 IS - 1 SP - 136-148 ER - TY - JOUR TI - Automatic image analysis in evaluation of aggregate shape AU - Brzezicki, J. M. AU - Kasperkiewicz, J. T2 - Journal of Computing in Civil Engineering AB - The presented method of image analysis is aimed at the evaluation of aggregate grain shape for concrete mixes and other civil engineering purposes. Standard procedure of the aggregate shape evaluation (ASTM) involves manual, troublesome measurements and produces parameters that only roughly characterize the shape of aggregates. The present procedure enables automatic and accurate measurement of three main dimensions of each grain in a sample of aggregate grains, and makes possible evaluation of their flakiness and elongation indexes, as well as of the corresponding statistics. A new, more accurate method of the shape characterization of the samples of aggregates along with its graphical presentation is proposed. Examples of the application of the method to sets of aggregate grains of different origin demonstrate the effectiveness of the method and of the new shape characteristics. DA - 1999/// PY - 1999/// DO - 10.1061/(ASCE)0887-3801(1999)13:2(123) VL - 13 IS - 2 SP - 123-128 ER - TY - JOUR TI - Case study of the physics component of an integrated curriculum AU - Beichner, R AU - Bernold, L AU - Burniston, E AU - Dail, P AU - Felder, R AU - Gastineau, J AU - Gjertsen, M AU - Risley, J T2 - AMERICAN JOURNAL OF PHYSICS AB - Over a four-year time span, several departments at North Carolina State University offered experimental sections of courses taken by freshman engineering students. The acronym IMPEC (Integrated Math, Physics, Engineering, and Chemistry curriculum) describes which classes were involved. This paper discusses the physics component of the curriculum and describes the impact of the highly collaborative, technology-rich, activity-based learning environment on a variety of conceptual and problem-solving assessments and attitude measures. Qualitative and quantitative research results indicate that students in the experimental courses outperformed their cohorts in demographically matched traditional classes, often by a wide margin. Student satisfaction and confidence rates were remarkably high. We also noted substantial increases in retention and success rates for groups underrepresented in science, math, and engineering. Placing students in the same teams across multiple courses appears to have been the most beneficial aspect of the learning environment. DA - 1999/7// PY - 1999/7// DO - 10.1119/1.19075 VL - 67 IS - 7 SP - S16-S24 SN - 0002-9505 ER - TY - JOUR TI - Binding of lipophilic nutrients to beta-lactoglobulin prepared by bioselective adsorption AU - Wang, QW AU - Allen, JC AU - Swaisgood, HE T2 - JOURNAL OF DAIRY SCIENCE AB - The binding of the lipophilic nutrients, retinal, vitamin D2, and retinyl palmitate by beta-lactoglobulin was measured by analysis of changes in the fluorescence of the tryptophanyl residue of beta-lactoglobulin or the retinyl moiety. The fluorescence intensity of the tryptophanyl residue was quenched by retinoid or vitamin D binding but was enhanced by palmitate binding. The analysis of competitive binding experiments with palmitate indicated that retinal and palmitate did not compete for the same site; however, vitamin D2, which binds with a stoichiometry of 2, appeared to displace palmitate at higher concentrations. Also, the retinoids and vitamin D2 were bound more tightly than was palmitate. The results are consistent with the model in which the retinoids and vitamin D2 bind in the calyx formed by the beta-barrel; palmitate and a second molecule of vitamin D2 bind in a surface pocket near the dimer contact region. Retinyl palmitate, which has both moieties, appeared to bind at both sites. DA - 1999/2// PY - 1999/2// DO - 10.3168/jds.S0022-0302(99)75231-8 VL - 82 IS - 2 SP - 257-264 SN - 0022-0302 KW - binding lipophilic nutrients KW - beta-lactoglobulin KW - bioselective adsorption ER - TY - JOUR TI - Turbulence in flocculators: Comparison of measurements and CFD simulations AU - Ducoste, JJ AU - Clark, MM T2 - AICHE JOURNAL AB - AIChE JournalVolume 45, Issue 2 p. 432-436 R&D Note Turbulence in flocculators: Comparison of measurements and CFD simulations Joel J. Ducoste, Corresponding Author Joel J. Ducoste Dept. of Civil Engineering, North Carolina State University, Raleigh, NC 27695Dept. of Civil Engineering, North Carolina State University, Raleigh, NC 27695Search for more papers by this authorMark M. Clark, Mark M. Clark Dept. of Civil and Environmental Engineering, University of Illinois Urbana-Champaign, Urbana, ILSearch for more papers by this author Joel J. Ducoste, Corresponding Author Joel J. Ducoste Dept. of Civil Engineering, North Carolina State University, Raleigh, NC 27695Dept. of Civil Engineering, North Carolina State University, Raleigh, NC 27695Search for more papers by this authorMark M. Clark, Mark M. Clark Dept. of Civil and Environmental Engineering, University of Illinois Urbana-Champaign, Urbana, ILSearch for more papers by this author First published: 16 April 2004 https://doi.org/10.1002/aic.690450222Citations: 12AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Literature Cited Armenante, P. M., and C. C. Chou, “Velocity Profiles in a Baffled Vessel with Single or Double Pitched-Blade Turbines,” AIChE J., 42, 1 (1996). Ducoste, J. J., M. M. Clark, and R. J. Weetman, “Turbulence in Flocculators, The Effects of Tank Size and Impeller Type,” AIChE J., 43(2), 328 (1997). Ducoste, J. J., and M. M. Clark, “The Influence of Tank Size and Impeller Geometry on Turbulent Flocculation: I. Experimental,” Environ. Eng. Sci. J., 15(3), 215 (1998a). Ducoste, J. J., and M. M. Clark, “The Influence of Tank Size and Impeller Geometry on Turbulent Flocculation: II. Model,” Environ. Eng. Sci. J., 15(3), 225 (1998b). FIDAP 7.0 Theory Manual, Fluid Dynamic International, Evanston, IL (1995). Kresta, S. M., and P. E. Wood, “Prediction of the Three-Dimensional Turbulent Flow in Stirred Tanks,” AIChE J., 37, 3 (1991). Luo, J. Y., A. D. Gosman, R. I. Issa, J. C. Middleton, and M. K. Fitzgerald, “Full Flow Field Computation of Mixing in Baffled Stirred Vessels,” Chem. Eng. Res. Des., 71, 342 (1993). Middleton, J. C., F. Pierce, and P. M. Lynch, “Computations of Flow Fields and Complex Reaction Yield in Turbulent Stirred Reactors, and Comparison with Experimental Data,” Chem. Eng. Res. Des., 64, 18 (1986). Oldshue, J. Y., and O. B. Mady, “Flocculation Performance of Mixing Impellers,” Chem. Eng. Prog., 74, 103 (1978). Oldshue, J. Y., Fluid Mixing Technology, McGraw-Hill, New York (1983). Ranade, V. V., and J. B. Joshi, “Flow Generated by a Disc Turbine: II. Mathematical Modeling and Comparison with Experimental Data,” Chem. Eng. Res. Des., 68, 34 (1990). Rodi, W., “ Turbulence Models and Their Applications in Hydraulics,” International Association for Hydraulic Research, Rotterdamseweg, Netherlands (1984). Taylor, G. I., “The Spectrum of Turbulence,” Proc. Royal Society, A164, 476 (1938). Van der Molen, K., and H. R. E. Van Maanen, “Laser Doppler Measurements of Turbulent Flow in Stirred Vessels to Establish Scaling Rules,” Chem. Eng. Sci., 33, 1161 (1978). Weetman, R. J., and J. Y. Oldshue, “Power, Flow and Shear Characteristics of Mixing Impellers,” 6th Eur. Conf. on Mixing, Pavia, Italy (1988). Citing Literature Volume45, Issue2February 1999Pages 432-436 ReferencesRelatedInformation DA - 1999/2// PY - 1999/2// DO - 10.1002/aic.690450222 VL - 45 IS - 2 SP - 432-436 SN - 0001-1541 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0033083186&partnerID=MN8TOARS ER - TY - JOUR TI - Formal specification of concurrent systems AU - Chadha, HS AU - Baugh, JW AU - Wing, JM T2 - ADVANCES IN ENGINEERING SOFTWARE AB - This paper presents a formal methodology for developing concurrent systems. We extend the Larch family of specification languages and tools with the CCS process algebra to support the specification and verification of concurrent systems. We present and follow a refinement strategy that relates an implementation in a programming language to a formal specification of such a system. We illustrate our methodology on an example that uses the preconditioned conjugate gradient method for solving a linear system of equations. DA - 1999/3// PY - 1999/3// DO - 10.1016/S0965-9978(98)00058-1 VL - 30 IS - 3 SP - 211-224 SN - 0965-9978 KW - larch KW - CCS KW - equational specifications KW - process algebra KW - conjugate gradient method KW - distributed systems KW - concurrent systems KW - programming languages KW - formal methods ER - TY - JOUR TI - Influence of protozoan grazing on contaminant biodegradation AU - Kota, S. AU - Borden, R. C. AU - Barlaz, Morton T2 - FEMS Microbiology Ecology AB - The influence of protozoan grazing on biodegradation rates in samples from contaminated aquifer sediment was evaluated under aerobic and anaerobic conditions. Predator–prey biomass ratios suggested that protozoan grazing might be influencing bacterial populations. Experiments under aerobic conditions were conducted with a sediment extract fed with BTEX and treated with protozoan inhibitors (cycloheximide, neutral red, amphotericin-B). After 10 days, BTEX losses were enhanced in the presence of protozoan inhibitors, suggesting that reduced protozoan grazing enhanced the rate of BTEX biodegradation. In tests conducted in macrocosms under anaerobic conditions, treatments included benzaldehyde (carbon substrate), benzaldehyde+cycloheximide, a live control (no carbon), and an abiotic control. In both the benzaldehyde-only and benzaldehyde+cycloheximide treatments, repeated benzaldehyde additions resulted in an increase in the total fermenter population from 103 to 105 cells (g sediment)−1 and in the Fe-reducing population from 101 to 105 cells g−1. However, the protozoan population remained at about 20 cells g−1 in the sediment with no cycloheximide, and there was no difference in benzaldehyde biodegradation in the presence and absence of cycloheximide, suggesting that predation was not a significant control on anaerobic benzaldehyde biotransformation. DA - 1999/// PY - 1999/// DO - 10.1111/j.1574-6941.1999.tb00609.x VL - 29 IS - 2 SP - 179–189 ER - TY - JOUR TI - BTEX Extraction from Clay Soil Using Prefabricated Vertical Drains AU - Gabr, M. A. AU - Sabodish, Mike AU - Williamson, Alan AU - Bowders, John J. T2 - Journal of Geotechnical and Geoenvironmental Engineering AB - A pilot scale field test was conducted to demonstrate the feasibility of using prefabricated vertical drains (PVDs) for in-situ point extraction of benzene, toluene, ethylbenzene, and xylene (BTEX) under vacuum. Results indicated the achievement of an average flow rate of 16.7 mL/s for the five PVD systems. Grab samples from the effluent indicated an increase in retrieved BTEX concentration with time. Maximum retrieved concentrations in a 2-day period were ∼0.4 mg/L for benzene, 0.27 mg/L for toluene, 0.19 mg/L for ethylbenzene, and 0.025 mg/L for xylene. Based on the limited results of the pilot scale test, a full-scale remediation of the site using the PVDs system is deemed feasible. DA - 1999/7// PY - 1999/7// DO - 10.1061/(ASCE)1090-0241(1999)125:7(615) VL - 125 IS - 7 SP - 615-618 ER - TY - JOUR TI - Probabilities of low-strength events in concrete AU - Leming, M. L. 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 - 1999/// PY - 1999/// DO - 10.14359/670 VL - 96 IS - 3 SP - 369-376 ER - TY - JOUR TI - Seismic response of unanchored bodies AU - Shao, Y. AU - Tung, C. C. T2 - Earthquake Spectra AB - This paper is concerned with the response of a rigid body subjected to base excitation. Using analytical and numerical methods of investigation, the results are presented in a series of graphs giving (1) the criteria for initiation of various modes (rest, slide, rock and slide-rock) of response and, using an ensemble of 75 real earthquake acceleration records, (2) the mean plus standard deviation of the distance of sliding relative to the base and (3) the probability of overturning during rocking. Based on the results in (3), two tables are prepared which give, corresponding to probability of overturning equal to 0.16 and 0.5, allowable peak base acceleration. DA - 1999/// PY - 1999/// DO - 10.1193/1.1586056 VL - 15 IS - 3 SP - 523-536 ER - TY - JOUR TI - Ritz vector approach for evaluating incabinet response spectra AU - Gupta, A AU - Rustogi, SK AU - Gupta, AK T2 - NUCLEAR ENGINEERING AND DESIGN AB - A new method is proposed for evaluating accurate incabinet response spectra for seismic qualification of electrical instruments. Finite element analysis of several typical cabinets shows that only few (often one) modes contribute significantly to the spectral accelerations at critical instrument locations inside the cabinet. In most cases the significant mode is a local mode of the cabinet component like door or back wall on which the instrument is mounted. In some cases it can also be a global cabinet mode or a superposition of the global cabinet and local component modes. Dynamic properties of the significant modes can be calculated using Rayleigh–Ritz method. The engineering effort and computational time taken by the new method is a minute fraction of that by the finite element method. DA - 1999/6// PY - 1999/6// DO - 10.1016/S0029-5493(99)00076-X VL - 190 IS - 3 SP - 255-272 SN - 0029-5493 ER - TY - JOUR TI - Fracture toughness for microcracking in a viscoelastic particulate composite AU - Park, S. W. AU - Kim, Y. R. AU - Lee, H. J. T2 - Journal of Engineering Mechanics AB - Fracture toughness for microcracking in a viscoelastic particulate composite is derived theoretically from the relationship between a continuum damage model and a micromechanical model. The continuum model presented by Park et al. and the micromechanical model presented by Schapery, which account for viscoelasticity and growing damage, are reviewed and compared in this paper. The condition for local microcrack growth is linked to the evolution law for damage growth in the homogenized continuum. Local microcrack growth is governed by an energy-based fracture criterion. Damage growth in the continuum is described by a phenomenological evolution law determined from an experiment. The resulting fracture toughness for asphalt concrete decreases rapidly with loading duration. DA - 1999/// PY - 1999/// DO - 10.1061/(ASCE)0733-9399(1999)125:6(722) VL - 125 IS - 6 SP - 722-725 ER - TY - JOUR TI - Flood retrofit of coastal residential structures: Outer Banks, North Carolina AU - Work, P. A. AU - Rogers, S. M. AU - Osborne, R. T2 - Journal of Water Resources Planning and Management AB - After Hurricane Emily struck the Outer Banks of North Carolina in August 1993, approximately 50 homeowners in the towns of Avon, Buxton, Frisco, and Hatteras, N.C., elected to superelevate their houses to reduce the future risk of flooding. Insurance payments served as at least a partial source of funds in most cases. A survey of 30 homeowners from this group was performed in 1995 to determine the motivations, methods, and benefits of the floodproofing retrofits. Half of the homeowners had been flooded at least twice prior to taking action. Homeowners typically made decisions based on memory of prior flood events or advice from others, rather than predictions of flood elevations. Retrofit costs were typically $10,000–$14,000 (in 1993 dollars), representing roughly 15% of the mean assessed house value for the survey. Results question the adequacy of the Flood Insurance Rate Maps for the area and reveal costs and motivations for flood retrofits of existing residential structures in a coastal barrier island setting. DA - 1999/// PY - 1999/// DO - 10.1061/(ASCE)0733-9496(1999)125:2(88) VL - 125 IS - 2 SP - 88-93 ER - TY - JOUR TI - Discrete-element modeling of shock compression of polycrystalline copper AU - Yano, K AU - Horie, Y T2 - PHYSICAL REVIEW B AB - Shock compression of polycrystalline copper was numerically investigated by use of a discrete-element model to highlight underlying heterogeneous and nonequilibrium processes at the grain level. The average diameter of model grains was 12 \ensuremath{\mu}m. Results show highly transient vortical flow fields and strong particle velocity dispersion that are consistent with the experimental results of Mescheryakov and his associates. Characteristic times for these phenomena were on the order of acoustic propagation times across the grains. The number of vortices increased with shock strength, but their size decreased almost inversely. Ejection of copper particles from the back free surface of the specimen was also observed. The cause of ejection is grain boundary cracking. DA - 1999/6/1/ PY - 1999/6/1/ DO - 10.1103/physrevb.59.13672 VL - 59 IS - 21 SP - 13672-13680 SN - 2469-9969 ER - TY - JOUR TI - Compressive behavior of slurry infiltrated mat concrete AU - Krstulovic-Opara, N. AU - Al-Shannag, M. J. T2 - ACI Materials Journal DA - 1999/// PY - 1999/// VL - 96 IS - 3 SP - 367-377 ER - TY - JOUR TI - B-2 stress index for elbow analysis AU - Yu, LX AU - Matzen, VC T2 - NUCLEAR ENGINEERING AND DESIGN AB - The purpose of this study is to evaluate the effect of end constraint, geometric dimension and internal pressure on the B2 stress indices, and thus to determine the conservativeness of the code equation for B2 stress indices. For a series of stainless steel elbow-straight pipe connections of different sizes and schedules, with flanges attached at different locations and with different levels of applied internal pressure, nonlinear finite element analyses were performed considering both material and geometrical nonlinearities. Load-deflection curves were obtained, and from these curves, collapse limit loads were determined. B2 stress indices were computed using the equation B2=Sy/(Mcl/Z). The B2 stress indices of elbows with flanges attached at different locations were compared. Also compared were B2 stress indices of elbows with different levels of internal pressure. Finally the B2 stress indices from the finite element analysis are compared with the B2 stress indices computed from code equation. Regression analysis is used to determine revised numerical values for the code equation for B2. A new, less conservative equation is proposed to be used to compute B2 stress indices for elbow component. DA - 1999/9// PY - 1999/9// DO - 10.1016/S0029-5493(99)00112-0 VL - 192 IS - 2-3 SP - 261-270 SN - 0029-5493 ER - TY - JOUR TI - Assessing denitrification rate limiting factors in a constructed wetland receiving landfill leachate AU - Kozub, DD AU - Liehr, SK T2 - WATER SCIENCE AND TECHNOLOGY AB - The focus of this research was to investigate denitrification in constructed wetlands to improve the nitrogen treatment capabilities of these systems. A free water surface flow constructed wetland located at the New Hanover County Solid Waste Management Facility, near Wilmington, North Carolina, USA, was used for this research. Field water sampling in conjunction with a laboratory acetylene block method was used to quantify nitrogen removals in the wetland. Background denitrification rates as well as potential denitrification rates using sodium acetate and sodium phosphate were measured in the laboratory. According to field measurements, average nitrate nitrogen loading and removal rates in the constructed wetland during 1997 were 11.1 ± 3.4 g N/m3/d and 4.5 ± 2.2 g N/m3/d, respectively. Denitrification rates measured in the laboratory with the addition of sodium acetate were higher than background denitrification rates while the addition of sodium phosphate had no effect on the denitrification rates. Results suggested denitrification in the wetland was limited by the availability of easily degradable sources of organic carbon. Background denitrification rates measured using the laboratory method were comparable to the nitrate nitrogen removal rates measured by field water sampling. DA - 1999/// PY - 1999/// DO - 10.1016/S0273-1223(99)00459-X VL - 40 IS - 3 SP - 75-82 SN - 0273-1223 KW - acetylene block method KW - constructed wetlands KW - denitrification KW - landfill leachate KW - nitrate nitrogen ER - TY - JOUR TI - Viscoelastic constitutive modeling of asphalt concrete with growing damage AU - Lee, HJ AU - Kim, YR AU - Kim, SH T2 - STRUCTURAL ENGINEERING AND MECHANICS AB - This paper presents a mechanistic approach to uniaxial viscoelastic constitutive modeling of asphalt concrete that accounts for damage evolution under cyclic loading conditions. An elasticviscoelastic correspondence principle in terms of pseudo variables is applied to separately evaluate viscoelasticity and time-dependent damage growth in asphalt concrete. The time-dependent damage growth in asphalt concrete is modeled by using a damage parameter based on a generalization of microcrack growth law. Internal state variables that describe the hysteretic behavior of asphalt concrete are determined. A constitutive equation in terms of stress and pseudo strain is first established for controlled-strain mode and then transformed to a controlled-stress constitutive equation by simply replacing physical stress and pseudo strain with pseudo stress and physical strain. Tensile uniaxial fatigue tests are performed under the controlled-strain mode to determine model parameters. The constitutive equations in terms of pseudo strain and pseudo stress satisfactorily predict the constitutive behavior of asphalt concrete all the way up to failure under controlled-strain and -stress modes, respectively. DA - 1999/2// PY - 1999/2// DO - 10.12989/sem.1999.7.2.225 VL - 7 IS - 2 SP - 225-240 SN - 1225-4568 KW - asphalt concrete KW - correspondence principle KW - constitutive model KW - cyclic test KW - damage KW - fatigue KW - viscoelasticity ER - TY - JOUR TI - Saving lives and money with robotic trenching and pipe installation AU - Lee, J. AU - Lorenc, S. J. AU - Bernold, L. E. T2 - Journal of Aerospace Engineering AB - Excavation, and in particular trenching and pipe laying, represent a hazardous working environment for humans. Many hazards exist, including trench walls that can collapse, heavy objects that can be accidentally dropped into the opening, and buried utilities (e.g., power lines) that are damaged during the operation. Workplace safety has become a major concern in the construction industry over the past few decades. The main accident prevention efforts used for trench excavation and pipe installation today are the use of the trench box, appropriate sloping of trench walls, and the training of site personnel. The Construction Automation and Robotics Laboratory at North Carolina State University has developed an alternative that is using advanced technology, the prototype robotic excavation and pipe installation system. The major mechanical components are a backhoe excavator and a pipe manipulator attachment. Joystick control of hydraulic actuators, data acquisition/processing, CAD interface, and automatic as-built generation represent the main software/hardware components. The integration of an excavator with a pipe manipulator attachment, video cameras, beam-laser, spatial-positioning system, and CAD represents an innovative approach to reduce the number of terrible accidents and fatalities in this industry. The success of transferring this technology into the industry, however, will depend on how much a contractor can benefit economically. One key item is the cost associated with the efforts that are required by the Occupational Safety and Health Administration (OSHA) to protect workers in an open trench. Because workers do not need to enter the trench, OSHA regulations do not have to be followed; thus a major cost factor is eliminated. This paper will not only discuss the developed hardware and software, it will also present the potential economic benefits of robotic excavation and pipe installation. DA - 1999/// PY - 1999/// DO - 10.1061/(ASCE)0893-1321(1999)12:2(43) VL - 12 IS - 2 SP - 43-49 ER - TY - JOUR TI - Discussion of “Representation of Compacted Clay Minifabric Using Random Networks” by J. Chen and M. A. Gabr AU - Chen, J. AU - Gabr, M. A. T2 - Journal of Geotechnical and Geoenvironmental Engineering DA - 1999/4// PY - 1999/4// DO - 10.1061/(asce)1090-0241(1999)125:4(336) VL - 125 IS - 4 SP - 336-337 ER - TY - JOUR TI - BMP test on chemically pretreated sludge AU - Lin, JG AU - Ma, YS AU - Chao, AC AU - Huang, CL T2 - BIORESOURCE TECHNOLOGY AB - Municipal waste activated sludge (WAS) was treated with NaOH to solubilize the particulate organic matter in order to improve its digestibility when the sludge was stabilized in an anaerobic digestion process. For the WAS of 1% TS treated with 20 and 40 meq/l NaOH at ambient temperature for 24 h, the SCOD/TCOD values increased from 3.5 to 39 and 55%, respectively. Results of the BMP (biochemical methane potential) test showed that recoveries of carbon and nitrogen reached 94–105% and the methane produced was 349 ml (at 1 atm and 35°C) for 1 g of COD removed. The improvement in VS removal for sludge treated with 40 meq/l of NaOH was as high as 41% over the control sludge sample, with COD removal and gas production improved by 30 and 34%, respectively, over the control. Results of the cumulative COD removal appeared to follow first-order reaction kinetics. Parameters of the first-order model such as ultimate biodegradable COD (Lu), reaction rate coefficient (k) and ultimate biodegradability (μ), were calculated using the Thomas method. The BMP test can be used as a valuable tool to study the kinetics and efficiency of anaerobic digestion processes. DA - 1999/5// PY - 1999/5// DO - 10.1016/S0960-8524(98)00126-6 VL - 68 IS - 2 SP - 187-192 SN - 0960-8524 KW - anaerobic digestion KW - biochemical methane potential KW - chemical pretreatment KW - hydrolysis ER -