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PARALLEL ANd dISTRIBUTEd TLM COMPUTATION WITH SIGNAL-PROCESSING FOR ELECTROMAGNETIC-FIELd MOdELING

INTERNATIONAL JOURNAL OF NUMERICAL MOdELLING-ELECTRONIC NETWORKS dEVICES ANd FIELdS 1995年第3-4期8卷 169-185页

作者： SO, PPM ESWARAPPA, C HOEFER, WJR NSERC/MPR Teltech Research Chair in RF Engineering Department of Electrical and Computer Engineering University of Victoria Victoria British Columbia V8W 3P6 Canada Poman So received his B.Sc. degree in computer science and physics from the University of Toronto Toronto Onatario Canada in 1985. He obtained his B.A. Sc. and M.A.Sc. degrees in electrical engineering (summa cum laude) from the University of Ottawa Ottawa Ontario Canada in 1987 and 1989 respectively. Mr So was a research engineer in the University of Ottawa from January 1989 to October 1991 his research interests included CAD techniques of microwave circuits and numerical methods for electromagnetic wave modelling. He specialized in the development of electromagnetic engineering CAD software and successfully implemented a number of electromagnetic wave simulators based on the two-dimensional and three-dimensional transmission-line matrix methods. From August 1990 to February 1991 he accompanied Professor W. J. R. Hoefer to Rome Italy and Sophia Antiopolas France. During that time he implemented a parallel version of the 3D-TLM simulator for the CM-2 Connection Machine using C-Star and X Windows Library. He is a research engineer and a Ph.D. student at the University of Victoria Victoria British Columbia Canada. He ported the 2D- and 3D-TLM simulators to DECmpp 1200 massively parallel computer using MPL C and C++. He also combined OSA90/hope a commercially available microwave CAD program with a 2D-TLM simulation module for geometry optimization using the Datapipe technique of OSA90/hope. Recently he has developed a distributed client-server computing technique for the TLM method this technique could accelerate the TLM simulation by more than an order of magnitude. Channabasappa Eswarappa received the M.Tech. degree in electrical engineering from the Indian Institute of Technology Kanpur India in 1983 and Ph. D. degree from the University of Ottawa Canada in 1990. He worked as an Assistant Executive Engineer and later as

This paper describes the implementation of transmission-line matrix (TLM) method algorithms on a massively parallel computer (dECmpp 12000), the technique of distributed computing in the UNIX environment, and the combination of TLM analysis with Prony's method as well as with autoregressive moving average (ARMA) digital signal processing for electromagnetic field modelling. By combining these advanced computation techniques, typical electromagnetic field modelling of microwave structures by TLM analysis can be accelerated by a few orders of magnitude.

关键词： Mathematical models

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FIELd TRAPPING OF SUBSURFACE VAPOR-phASE PETROLEUM-HYdROCARBONS

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GROUNd WATER MONITORING ANd REMEdIATION 1994年第1期14卷 110-119页

作者： MOYER, EE OSTENdORF, dW KAMPBELL, dH XIE, YF Ellen E. Moyer (ENSR Consulting and Engineering 35 Nagog Park Acton MA 01720) is a senior environmental engineer at ENSR Consulting and Engineering in Acton Massachusetts. Her research interests include bioremediation air sparging soil venting and analytical modeling of subsurface contamination. Moyer is a registered Professional Engineer with an M.S. in environmental engineering and a Ph.D. in civil engineering from the University of Massachusetts at Amherst and a member of the National Ground Water Association and the American Society of Civil Engineers. David W. Ostendorf (Civil Engineering Department University of Massachusetts Amherst MA 01003) is an associate professor in the environmental engineering program of the Civil Engineering Department of the University of Massachusetts at Amherst. His research interests include unconfined aquifer contamination hazardous waste site remediation and analytical modeling of problems in environmental fluid mechanics. Ostendorf is a registered Professional Engineer and a member of the American Geophysical Union American Society of Civil Engineers Soil Science Society of America Water Pollution Control Federation and Association of Environmental Engineering Professors as well as the National Ground Water Association. Don H. Kampbell (Robert S. Kerr Environmental Research Laboratory Ada OK 74820) is a research chemist at the U.S. EPA Robert S. Kerr Environmental Research Laboratory in Ada Oklahoma. His research interests include gas chromatog- raphy GC/mass spectrometry industrial waste processes soil bioreactor systems aquifer biorestoration and soil gas measurements. Kampbell is a certified Professional Soil Scientist and a registered Professional Engineer as well as a member of the Soil Science Society of America and the American Chemical Society. Yuefeng Xie (Civil Engineering Department University of Massachusetts Amherst MA 01003) is a postdoctoral research associate in the environmental engineering program of the Civil Engineering Depart

Soil gas samples from intact soil cores were collected on adsorbents at a field site, then thermally desorbed and analyzed by laboratory gas chromatography (GC). Vertical concentration profiles of predominant vapor phase petroleum hydrocarbons under ambient conditions were obtained for the zone directly above the capillary fringe. Water and residual phase weathered aviation gasoline were present in this region of the profile. The sampling, trapping, and GC methodology was effective in most respects. Reproducibility, trapping, and desorption efficiency were generally satisfactory, and different sorbent tubes gave similar results. A minor shortcoming of the method occurred with the most volatile compound, 2,3-dimethylbutane, which was poorly retained during several weeks of storage time and was also poorly desorbed. Vapor phase concentrations of predominant hydrocarbon compounds all increased with depth at one sampling location. At a more highly contaminated location, concentrations of highly volatile compounds increased with depth while concentrations of less volatile compounds remained constant or decreased, possibly indicating distillation effects. Scatter in the data was attributed to heterogeneities in water and residual phase distribution.

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ENHANCEd dEGRAdATION OF dISSOLVEd BENZENE ANd TOLUENE USING A SOLId OXYGEN-RELEASING COMPOUNd

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GROUNd WATER MONITORING ANd REMEdIATION 1994年第1期14卷 120-128页

作者： BIANCHIMOSQUERA, GC ALLENKING, RM MACKAY, dM Gino Bianchi-Mosquera is principal geochemist at Stollar Bianchi (140 Ravenna Dr. Long Beach CA 90803). He received a B.A. degree in geochemistry from Occidental College in Los Angeles California an M.S. degree in geochemistry from The Pennsylvania State University and a D. Env. degree from the University of California Los Angeles in 1982 1986 and 1993 respectively. His research interests include the transport and fate of organic compounds in the subsurface and the design and evaluation of new aquifer cleanup techniques. Douglas Mackay is adjunct professor in the Centre for Groundwater Research at the University of Waterloo (Waterloo Ontario N2L 3G1) Canada and a visiting scientist at the UCLA Department of Civil Engineering. From 1986 to mid- 1990 he was a faculty member in the environmental science and engineering program of the UCLA School of Public Health. His research focuses on field studies of transport and fate of organic chemicals in ground water and ground water decontamination technologies. Mackay received a B.S. in engineering and M.S. and Ph.D. degrees in civil engineering from Stanford University in 1970 1973 and 1981 respectively.

A field test to evaluate the applicability of an oxygen-releasing compound (ORC) to the remediation of ground water contaminated with benzene and toluene was conducted in the Borden Aquifer in Ontario, Canada. Benzene and toluene were injected as organic substrates to represent BTEX compounds, bromide was used as a tracer, and nitrate was added to avoid nitrate-limited conditions. The fate of the solutes was monitored along four lines of monitoring points and wells. Two lines studied the behavior of the solutes upgradient and downgradient of two large-diameter well screens filled with briquets containing ORC and briquets without ORC. One line was used to study the solute behavior upgradient and downgradient of columns of ORC powder placed directly in the saturated zone. The remaining line was a control. The results indicate that ORC in both briquet and powder form can release significant amounts of oxygen to contaminated ground water passing by it. In the formulation used in this work, oxygen release persisted for at least 10 weeks. Furthermore, the study indicates that the enhancement of the available dissolved oxygen content of at least 4 mg/L each of the ground water by ORC can support biodegradation of benzene and toluene dissolved in ground water. Such concentrations are typical of those encountered at sites contaminated with petroleum hydrocarbons;therefore, these results suggest that there is promise for ORC to enhance in situ biodegradation of BTEX contaminants at such sites using passive (nonpumping) systems to contact the contaminated ground water with the oxygen source.

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NUMERICAL-METHOd FOR CALCULATING SURFACE CURRENT-dENSITY ON 3-dIMENSIONAL SMOOTH SCATTERERS

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ELECTRONICS ANd COMMUNICATIONS IN JAPAN PART II-ELECTRONICS 1994年第2期77卷 1-11页

作者： IKUNO, H GONdO, M NISHIMOTO, M Faculty of Engineering Kumamoto University Kumamoto Japan 860 Himyoshi Ikmo received his B.E. M.E. and Ph.D. from Kyushu University in 1962 1964 and 1979 respectively. From 1967 to 1970 he was a Research Associate in Computer Science and Communication Engineering at Kyushu University. He joined the Department of Electrical Engineering and Computer Science of Kumamoto University in 1970 and is currently a Professor there. During 1983 to 1984 he was a Visiting Professor at the Polytechnic University Brooklyn NY. His research interests are in the areas of scattering diffraction and wave propagation in the theory of electromagnetics. Dr. Ikuno is a member of IEEE and IEE of Japan. Michim Gondo graduated from National Defense Academy Yokosuka in 1985 and received his M.E. from Kumamoto University in 1990. He is currently in the doctoral program at Kumamoto University. His research interest is in three-dimensional electromagnetic scattering. Masahiko Nkhimoto received his B.S. in Electronic Engineering from Kumamoto University in 1982 and an M.S. and Ph.D. from Kyushu University in 1984 and 1987 respectively. Since 1987 he has been a Research Associate in the Department of Electrical Engineering and Computer Science Kurnamoto University. His research interests are in the areas of scattering and diffraction of electromagnetic waves.

This paper shows that the surface current density can be calculated by using approximate total tangent magnetic vector fields which are expressed by finite number of linear combination of tangent vectors of spherical wave functions. Sampling points are determined by considering the property of associated Legendre functions and trigonometrical functions. By setting a number of sampling points to twice the largest mode number, a computer-aided algorithm is obtained. The accuracy of the solutions is checked and the polarization dependence of the surface current densities is clarified.

关键词： YASUURA METHOd 3-dIMENSIONAL PROBLEM BOdY OF REVOLUTION LEAST-SQUARES PROBLEM

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ACQUISITION REFORM ANd BEST PROdUCT PROCUREMENT - AN engineering VIEW

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NAVAL ENGINEERS JOURNAL 1994年第6期106卷 41-57页

作者： FISHER, dA SKOLNICK, A He has been involved with several weapon system developments. Among these were the Trident II fire control and navigation systems the BSY-I Anti-Submarine Warfare System and the Navy standard computers (UYK44 and EMSP). He served as manager of the Digital Circuits Engineering Branch and was then appointed as manager of the Automatic Test Equipment (ATE) Technology Division. As manager of the ATE Technology Division he was responsible for the SP-23 Fire Control System Support Project the SP-24 Navigation Project and the Fleet Progressive Maintenance Program (2M/ATE). This Division was responsible for selection and application of electronic product technology and for developing fleet test and repair techniques. He holds a B.S. in Electrical Engineering from the University of Evansville and is currently pursuing a Masters of Public Administration at Indiana University-Purdue University Indianapolis. Dr. Alfred Skolnick:retired from the Navy in 1983 with the rank of captain. He is president of System Science Consultants (SSC) specializing in strategic planning technical program definition technology assessment and engineering analyses on selected matters of national interest. Dr. Skolnick taught mathematics and management sciences at University of Virginia and Marymount University. He is adjunct faculty at Northern Virginia Community College. From 1985 to 1989 he was president of the American Society of Naval Engineers. In the Navy he served at Applied Physics Laboratory/The Johns Hopkins University then aboard USSBoston(CAG-1) and played leading roles in several weapon system developments inertial navigation (Polaris) deep submergence (DSRV) and advanced ship designs (SES). He later was director Combat System Integration Naval Sea Systems Command and head Combat Projects Naval Ship Engineering Center. In 1975 he became a major project manager and led the Navy's High Energy Lasers Program in 1981 he was assigned all Navy Directed Energy Weapons development efforts. He was vice president advanced tech

The military services are being moved in the direction of performance-based specifications and standards. They are being steered against dictating ''how to'' produce an item since such action forecloses on the ability to gain access to components or technology that may have a commercial equivalent. Why should the engineering community embrace the new approach? Aside from the obvious weight of it being approved policy, therefore currently mandated, it warrants examination because it is the correct approach at this time when applied to appropriate products. Military specifications and standards are to be displaced then, by acceptable alternative contractor design solutions. Industry bidders will be allowed to propose the particular design details, permitting procurement flexibility by contractually citing only system level or interface requirements, both physical and functional. Hopefully, this can broaden the industrial base and increase competition with reduced costs to follow. Conceptually, the approach appears both performance-sensible and cost-attractive (there are, of course, consequent risks) but how does implementation proceed? Is it possible to pursue the goals envisioned along paths that are not in themselves experimental? Can the American postulate, minimal loss of life and limb to U.S. military people, continue to be honored? Experience and track record elsewhere imply encouraging possibilities in select situations-useful prospects are identified and discussed in practical terms.

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PERFORMANCE OF A PRIORITIZEd ON-BOARd BASEBANd SWITCH FOR A MULTISERVICE MULTIBEAM SATELLITE

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INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS 1994年第3期12卷 283-297页

作者： BOHM, S ELHAKEEM, AK HACHICHA, M Department of Electrical and Computer Engineering Concordia University 1455 De Maisonneuve Blvd. West Montreal H3A 1M8 Canada Was born in Montreal Canada on 14 September 1966. He received the B. Eng. degree in electrical engineering from Concordia University Montreal Canada in 1989. He is at present completing the M.A.Sc. degree in electrical engineering at Concordia University. (S'75–S'79–M'79–SM'86) received the Ph.D. degree from Southern Methodist University Dallas TX in 1979. He spent the next two years working as a Visiting Professor in Egypt after which he moved to Ottawa Canada in 1982. He assumed teaching and research positions in Carleton and Manitoba Univerities and later moved to Concordia University Montreal Canada in 1983 where he is now a Professor in the Electrical and Computer Engineering Department. He has published numerous papers in IEEE and international journals in the areas of spread spectrum and networking. He is a well-known expert in these areas and serves as a consultant to many companies. His current research interests include wide-band metropolitan networks switching architectures and performance of on-board multibeam satellites acquisitionless CDMA networks code distribution and orthogonalization of CDMA signals responsive congestion control for ATM-based networks ARQ techniques and investigation of the novel SUGAR CDMA systems in fading channels. Dr. Elhakeem is a Senior Member of the Canadian Electrical Engineering Society and Armed Forces Association. He has chaired numerous technical sessions in IEEE Conferences was the Technical Program Chairman for IEEE Montech 1986 Montreal Canada. Dr. Elhakeem is the key guest editor of theIEEE Journal of Selected Areas in Communicationsfor the May June issues 1993 covering CDMA networks. Advanced Technology & Networks VISTAR Telecommunications Inc. Ottawa Ontario K1G 3J4 Canada An Associate Director of Advanced Technology & Networks Group VISTAR Telecommunications Inc. Ottawa Canada. He is also an Adjunct Pr

In this paper, we study the performance of a prioritized on-board baseband switch in conjunction with a multibeam satellite handling integrated services. The services considered for the analysis include voice, video, file transfer and interactive data. The prioritized switch uses both input and output buffering, switch speed-up as well as a two-phase head-of-line resolution algorithm, in order to reduce the buffer loss while maintaining acceptable user delays. The minimum required buffer capacity and switch speed-up for each service in a prioritized environment are found under uniform traffic conditions. It is shown that under uniform traffic conditions, only minimal buffering and switch speed-up are needed even for the lowest priority users. The performance dependence on the switch size is also substantially reduced with head of line resolution and buffering even in a prioritized environment.

关键词： SWITCH ON-BOARd BASEBANd MULTIBEAM PRIORITIZEd HEAd-OF-LINE UNIFORM LOAd SPEEd-UP

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THE CALLING(SM) NETWORK - A GLOBAL WIRELESS COMMUNICATION-SYSTEM

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INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS 1994年第1期12卷 45-61页

作者： TUCK, EF PATTERSON, dP STUART, JR LAWRENCE, MH Calling Communications Corporation. 1900 West Garvey Ave South. Suite 200 West Covina CA 91790 USA. Chairman of Calling Communications Corporation. He is also the Managing Director of Kinship Venture Management Inc. the general partner of Kinship Partners 11 and a General Partner of Boundary the general partner of The Boundary Fund. As a venture capitalist he has founded or participated in founding several telecommunications companies including Calling Communications Corporation Magellan Systems Corporation manufactures of Global Positioning System receivers Applied Digital Access manufacturer of DS-3 test access and network performance monitoring equipment Endgate Technology Corporation specialists in satellite phased array antennas and Poynting Systems Corporation. now a division of Reliance Corporation manufacturers of fibre optic transport equipment. He was a founder of Kebby Microwave Corporation where he invented the first solid-state. frequency-modulated commercial microwave link system. The company was acquired by ITT Corporation where he rose to the position of V.P. and Technical Director of ITT North America Telecommunications Inc. Subsequently he was V.P. of Marketing and Engineering at American Telecommunications Inc. (ATC). He was founding Director of American Telecom Inc. a joint venture between ATC and Fujitsu and has served on more than 20 boards of directors including those of three public companies. He has authored articles on microwave engineering and telephone signalling and was a contributor to Reference Data For Radio Engineers. He is a graduate of the University of Missouri at Rolla where he was later awarded an honorary Professional degree and serves on its Academy of Electrical Engineering. Mr Tuck is a Senior Member of the IEEE a Fellow of the Institution of Engineers (Australia) a Professional Member of the AIAA and a registered professional engineer in three states. More than 25 years of experience in the telecommunications industry where he has been responsibl

There is a very large demand for basic telephone service in developing nations, and remote parts of industrialized nations, which cannot be met by conventional wireline and cellular systems. This is the world's largest unserved market. We describe a system which uses recent advances in active phased arrays, fast-packet switching technology, adaptive routeing, and light spacecraft technology, in part based on the work of the Jet Propulsion Laboratory and on recently-declassified work done on the Strategic defense Initiative, to make it possible to address this market with a global telephone network based on a large low-Earth-orbit constellation of identical satellites. A telephone utility can use such a network to provide the same modern basic and enhanced telephone services offered by telephone utilities in the urban centres of fully-industrialized nations. Economies of scale permit capital and operating costs per subscriber low enough to provide a service to all subscribers, regardless of location, at prices comparable to the same services in urban areas of industrialized nations, while generating operating profits great enough to attract the capital needed for its construction. The bandwidth needed to support the capacity needed to gain these economies of scale requires that the system use K(alpha)-band frequencies. This choice of frequencies places unusual constraints on the network design, and in particular forces the use of a large number of satellites. Global demand for basic and enhanced telephone service is great enough to support at least three networks of the size described herein. The volume of advanced components, and services such as launch services, required to construct and replace these networks is sufficient to propel certain industries to market leadership positions in the early 21st Century.

关键词： LOW EARTH ORBIT SATELLITE COMMUNICATIONS FAST PACKET SWITCHING EARTH FIXEd CELLS AdAPTIVE ROUTEING LIGHT SPACECRAFT K(A) BANd phASEd-ARRAY ANTENNAS

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HYdROCARBON VAPOR dIFFUSION IN INTACT CORE SLEEVES

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GROUNd WATER MONITORING ANd REMEdIATION 1993年第1期13卷 139-150页

作者： OSTENdORF, dW MOYER, EE XIE, YF RAJAN, RV David W. Ostendorf (Civil Engineering Department University of Massachusetts Amherst MA 01003) is an associate professor in the Environmental Engineering Program of the Civil Engineering Department of the University of Massachusetts at Amherst. His research interests include unconfined aquifer contamination hazardous waste site remediation and analytical modeling of problems in environmental fluid mechanics. Ostendorf is a Registered Professional Engineer in Massachusetts and a member of the American Geophysical Union American Society of Civil Engineers Soil Science Society of America Water Pollution Control Federation and Association of Environmental Engineering Professors as well as the National Ground Water Association. Ellen E. Moyer (Civil Engineering Department University of Massachusetts Amherst MA 01003) is a doctoral candidate in the Environmental Engineering Program of the Civil Engineering Department of the University of Massachusetts at Amherst with an M.S. degree in environmental engineering from that institution. Her research interests include subsurface investigation soil venting bioremediation and analytical modeling of subsurface contamination. She has six years of professional experience managing hazardous waste site investigation and cleanup projects and is a member of the National Ground Water Association and the American Society of Civil Engineers. Yuefeng Xie (Civil Engineering Department University of Massachusetts Amherst MA 01003) is a postdoctoral research associate in the Environmental Engineering Program of the Civil Engineering Department of the University of Massachusetts at Amherst. His research interests include environmental analyses drinking water treatment and the chemical characterization and removal of disinfection by-products. A graduate with a Ph.D. and an M.S. in environmental engineering and a B.S. in chemistry and chemical engineeering from Tsinghua University Beijing China Xie is a member of the American Water Works Association and the Water Poll

The diffusion of 2,2,4-trimethylpentane (TMP) and 2,2,5-trimethylhexane (TMH) vapors out of residually contaminated sandy soil from the U.S. Environmental Protection Agency (EPA) field research site at Traverse City, Michigan, was measured and modeled. The headspace of an intact core sleeve sample was swept with nitrogen gas to simulate the diffusive release of hydrocarbon vapors from residual aviation gasoline in and immediately above the capillary fringe to a soil-venting air flow in the unsaturated zone. The resulting steady-state profile was modeled using existing diffusivity and air porosity estimates in a balance of diffusive flux and a first order source term. The source strength, which was calibrated with the observed flux of 2,2,4-TMP leaving the sleeve, varied with the residual gasoline remaining in the core, but was independent of the headspace sweep flow rate. This finding suggested that lower soil-venting air flow rates were in principle as effective as higher air flow rates in venting LNAPL vapors from contaminated soils. The saturated vapor concentration ratio of 2,2,4-TMP to 2,2,5-TMH decreased from 6.6 to 3.5 over the duration of the experiments in an expression of distillation effects. The vertical profile model was tested against sample port data in four separate experiments for both species, yielding mean errors ranging from 0 to -24 percent in magnitude.

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VIRTUAL PROTOTYPING USING KNOWLEdGE - BASEd MOdELING ANd SIMULATION TECHNIQUES

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NAVAL ENGINEERS JOURNAL 1993年第3期105卷 201-212页

作者： SHEA, JG The Author:holds bachelor and master of engineering degrees in mechanical engineering a M.Eng. in engineering management and is currently fulfilling requirements for the M.S. and Ph.D. degrees in computer science at the University of Louisville. He is employed as program manager Phalanx Advanced Engineering Development at the Naval Ordnance Station Crane Div. NavSurfWarCen Louisville Ky. During his tenure with Phalanx Mr. Shea has contributed to system reliability improvement system performance upgrading and the development of the Phalanx HOL (RISC) Computer. Mr. Shea is a member of ASNE the Institute of Electrical and Electronics Engineers American Institute of Aeronautics and Astronautics Society for Computer Simulation International Test & Evaluation Association and the Military Operations Research Society.

Knowledge-based modeling and simulation bridges the gap between ''conventional'' artificial intelligence implementations (such as expert systems) and more traditional computer-aided design techniques. We are currently developing software, whose primary function is to capture a user-input design specification and produce a ''virtual'' rapid prototvpe in the form of executable rule-based code. This code can then be exercised either as an interactive part of a hardware-in-the-loop testbed simulator or as a component of an object-oriented ''behavioral'' simulation environment. While the phalanx Testbed is the immediate beneficiary of this work, the techniques described have a wide range of application in the modeling of conceptual design and performance characteristics. This paper describes the system architecture and software tools that we are applying to generate virtual rapid prototypes for use in the phalanx Testbed. Particular attention is paid to defining the intelligent knowledge-capture mechanisms and model generation methodologies that we are using to translate design knowledge and performance requirements into rule-based simulations. The object-oriented programming approach to the merging of ''new'' data with previouslv-captured and stored data is discussed, and the issues of verifying and validating prototypes generated using such partiallv ''reengineered'' models are examined. An application currently in use as an investigative prototype for testbed development, a simple position controller servomechanism used to control the azimuth angle of a target-tracking sensor, is used to illustrate the process.

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APPLICATION OF ELECTROMAGNETIC LOGGING TO CONTAMINATION INVESTIGATIONS IN GLACIAL SANd-ANd-GRAVEL AQUIFERS

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GROUNd WATER MONITORING ANd REMEdIATION 1993年第3期13卷 129-138页

作者： WILLIAMS, JH LAphAM, WW BARRINGER, TH John H. Williams received an M.S. in geology from Penn State University in 1980 and has worked for the U.S. Geological Survey since that time. He currently is the ground water specialist for the New York District (P.O. Box 1669 Albany NY 12201) and the borehole geophysics specialist for the Northeastern Region. He is also an instructor for the National Ground Water Association course on aquifer test methods. His primary interest is the application of borehole geophysics to ground water studies. Wayne W. Lapham has been employed as a hydrologist with the U.S. Geological Survey since 1976. He currently works for USGS as a ground water specialist for the National Water-Quality Assessment Program (MS 413 Reston VA 22092). He received a B.S. degree in mechanical engineering from Northeastern University in 1969 an M.S. in geology from the University of Massachusetts in 1975 and a Ph.D. in hydrology from the University of Arizona in 1988. He has been involved with various aspects of ground water hydrology including resource appraisal and ground water modeling. Thomas H. Barringer is the statistical methods specialist for the New Jersey District of the U.S. Geological Survey (810 Bear Tavern Rd West Trenton NJ 08628). His interests include spatial statistics and the application of statistical methods to hydrological problems. He has a joint M.S. in regional planning and regional science and a PhD. in regional science from the University of Pennsylvania.

Electromagnetic (EM) logging provides an efficient method for high-resolution, vertical delineation of electrically conductive contamination in glacial sand-and-gravel aquifers. EM, gamma, and lithologic logs and specific conductance data from sand-and-gravel aquifers at five sites in the northeastern United States were analyzed to define the relation of EM conductivity to aquifer lithology and water quality. Municipal waste disposal, septic waste discharge, or highway deicing salt application at these sites has caused contaminant plumes in which the dissolved solids concentration and specific conductance of ground water exceed background levels by as much as 10 to 20 times. The major hydrogeologic factors that affected EM log response at the five sites were the dissolved solids concentration of the ground water and the silt and clay content in the aquifer. EM conductivity of sand and gravel with uncontaminated water ranged from less than 5 to about 10 millisiemens per meter (mS/m);that of silt and clay zones ranged from about 15 to 45 mS/m;and that of the more highly contaminated zones in sand and gravel ranged from about 10 to more than 80 mS/m. Specific conductance of water samples from screened intervals in sand and gravel at selected monitoring well installations was significantly correlated with EM conductivity. EM logging can be used in glacial sand-and-gravel aquifer investigations to (1) determine optimum depths for the placement of monitoring well screens;(2) provide a nearly continuous vertical profile of specific conductance to complement depth-specific water quality samples;and (3) identify temporal changes in water quality through sequential logging. detailed lithologic or gamma logs, preferably both, need to be collected along with the EM logs to define zones in which elevated EM conductivity is caused by the presence of silt and clay beds rather than contamination.

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