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Simulation of electromagnetic radiation and scattering using a finite difference-time domain technique

computer Applications in Engineering Education 1992年第1期1卷 45-45页

作者： Li, K. Tassoudji, M.A. Shin, R.T. Kong, J.A. Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge Massachusetts 02139 Kevin Li:received his BS and SM degrees (1990) in Electrical Engineering and EE (Electrical Engineer's) degree (1991) from the Massachusetts Institute of Technology where he is currently pursuing his PhD in Electrical Engineering. Since 1990 he has been the recipient of a United States Air Force Laboratory Graduate Fellowship. His main research interests include electromagnetic scattering radar cross section prediction and numerical techniques. Mr. Li is a member of Tau Beta Pi and a student member of IEEE. M. Ali Tassoudji:received his BS (1987) and MS (1989) degrees in Electrical Engineering from the University of Michigan Ann Arbor. Since 1989 he has been a research assistant at the Massachusetts Institute of Technology where he is currently working towards his PhD in Electrical Engineering. His research interests include electromagnetic scattering and propagation modeling of microwave circuits and numerical techniques. Mr. Tassoudji is a member of IEEE and Eta Kappa Nu. Robert T. Shin:received his SB (1977) SM (1980) and PhD (1984) in Electrical Engineering from the Massachusetts Institute of Technology. Since 1984 he has been a member of the Air Defense Techniques Group at MIT Lincoln Laboratory as a Research Staff member and as a Senior Staff member from 1989. His research interests are in the areas of electromagnetic wave scattering and propagation theoretical model development and data interpretation for microwave remote sensing. He is the coauthor ofTheory of Microwave Remote Sensing(Wiley 1985). Dr. Shin is a member of The Electromagnetics Academy IEEE American Geophysical Union Tau Beta Pi Eta Kappa Nu and Commission F of the International Union of Radio Science. Since 1987 he has served on the Editorial Board of theJournal of Electromagnetic Waves and Applications(JEWA). Jin Au Kong:is Professor of Electrical Enginee

The finite difference-time domain (FD-TD) technique is applied to the solution of Maxwell's equations. A computer program, which can be used to simulate and study numerous electromagnetic phenomena, is developed and implemented on an IBM 386 compatible personal computer. The FD-TD technique is a useful tool for students in electromagnetics. The technique is flexible and can be applied to many basic EM scattering and radiation problems. Because field solutions are found as a function of time, visualization of the propagation of the EM fields is possible. The FD-TD technique is implemented for a two-dimensional rectangular grid in conjunction with a second-order absorbing boundary condition. Both E- and H-field polarizations are analyzed. Finite objects consisting of dielectric, magnetic and conducting materials, and perfectly conducting infinite ground planes are modeled. Plane wave and line current sources are implemented. In addition to the capability of animating the propagation of the EM fields, radiation and scattering patterns can be generated.

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COMPARISON OF DOWNHOLE AND SURFACE SAMPLING FOR THE DETERMINATION OF VOLATILE ORGANIC-COMPOUNDS (VOCS) IN GROUND-WATER

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GROUND WATER MONITORING AND REMEDIATION 1992年第1期12卷 126-133页

作者： ROSEN, ME PANKOW, JF GIBS, J IMBRIGIOTTA, TE Michael E. Rosen received his B.A. in chemistry from the State University of New York at Binghamton in 1981 and a Ph.D. in environmental science and engineering from the Oregon Graduate Institute in 1988. His research interests include trace environmental analysis of organic compounds. He is now manager of the Voluntary Cleanup Section of the Oregon Department of Environmental Quality (Environmental Cleanup Division 811 S.W. 6th Ave. Portland OR 97204) where he is working to develop streamlined procedures and processes for the investigation and cleanup of hazardous substance sites. James F. Pankow is professor and chairman of the Department of Environmental Science and Engineering at the Oregon Graduate Institute (Oregon Graduate Institute of Science and Technology Department of Environmental Science and Engineering 19600 N.W. von Neumann Dr. Beaverton OR 97006–1999). He received his B.A. in chemistry in 1973 from the State University of New York in Binghamton and his Ph.D. in environmental engineering science from the California Institute of Technology in Pasadena California in 1979. His group is involved in the study of the physical and chemical processes affecting the behavior of organic and inorganic chemicals in the environment. This work includes the development and application of sensitive analytical methods for the determination of trace organic contaminants in ground water systems. Jacob Gibs is an environmental engineer with the U.S. Geological Survey Water Resources Division (810 Bear Tavern Rd. Ste. 207 West Trenton NJ 08628). He received a B.S. in mechanical engineering in 1968 an M.S. in environmental engineering in 1975 and a Ph.D. in environmental engineering in 1983 all from Drexel University Philadelphia Pennsylvania. He is currently project chief of a study on representative sampling of ground water for trace levels of organic compounds. His research interests include evaluating ground water sampling techniques and devices for purgeable organic compounds design of sampling

The relative precision and accuracy of sampling and analysis methods for the determination of trace concentrations of volatile organic compounds (VOCs) in ground water were compared. Samples were collected from a well containing nanogram-per-liter (ng/L) to microgram-per-liter (mu-g/L) levels of VOCs. A Keck helical rotor submersible pump was used to collect samples at the surface for analysis by purge and trap (P&T) and for analysis by adsorption/thermal desorption (ATD). Downhole samples were collected by passing water through an ATD cartridge. Although slight spontaneous bubble outgassing occurred when the water was brought to the surface, the relative precisions and comparabilities of the surface and downhole methods were generally found to be equivalent from a statistical point of view. A main conclusion of this study is that bringing sample water to the surface for placement in VOC vials (and subsequent analysis by P&T) can be done reliably under many circumstances. However, care must still be taken to prevent adsorption losses and cross contamination. Samples subject to strong bubble outgassing will need to be handled in a special fashion (e.g., by downhole ATD) to minimize volatilization losses. Additionally, the higher sensitivity of the ATD method allows lower detection limits than are possible with P&T. For example, several compounds present at the ng/L level could be determined with confidence by ATD, but not by P&T.

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AN AI-BASED DECISION SUPPORT SYSTEM FOR NAVAL SHIP DESIGN

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NAVAL ENGINEERS JOURNAL 1992年第3期104卷 156-165页

作者： CHOU, YC BENJAMIN, CO Yu-Chao Chou:has served as an engineering officer in the Republic of China Navy for 20 years. He graduated from the Chung Chen Institute of Technology in 1972 with a bachelor of science degree in naval architecture. He received a master of engineering degree in naval architecture and marine engineering from the University of Michigan in 1977. He obtained his Ph.D. in engineering management at the University of Missouri-Rolla in 1991. His current research interests include artificial intelligence project management and concurrent engineering. He is a member of the American Society of Naval Engineers and the Institute of Industrial Engineers. Colin O. Benjamin:is an associate professor of engineering management at the University of Missouri-Rolla and has had several years of international teaching industrial and consulting experience. He received a Ph.D. in industrial engineering from the University of the West Indies an MBA from the Cranfield Institute of Technology U.K. and an M.Sc. in engineering production and management from the University of Birmingham U.K. His current research interests include artificial intelligence (AI) multi-criteria decision making (MCDM) facilities planning and computer integrated manufacturing (CIM). He is a Senior Member of the Institute of Industrial Engineers and the Society of Manufacturing Engineers.

Naval ship design is a complex, iterative decision-making process that requires not only qualitative reasoning and quantitative computations, but also effective handling of massive amounts of information. The development of a systematic procedure in the form of an interactive Decision Support System (DSS) incorporating artificial intelligence (AI) techniques can assist in improving the design process. The DSS reported in this paper integrates conventional naval ship design application software with an expert system. Modeling techniques such as a spreadsheet, a database management system, and graphic display capability are incorporated as well. This DSS facilitates "what-if" analysis of design problems and assessment of the trade-offs between performance and cost. The DSS will aid rapid generation of design alternatives and facilitate their evaluation. A final recommendation is made based on multiattribute decision analysis using the straightforward points allocation method and the analytic hierarchy process. During a typical consultation process, the user is prompted for inputs to the naval ship design process and is provided with a wide range of reports in graphical and numerical form. During a structured system evaluation, the DSS displayed considerable accuracy, flexibility, speed, user-friendliness, and cost-effectiveness. The reliability and validity of the system were also confirmed. These evaluation procedures provide a replicable methodology for verification and validation of this type of AI-based decision support system.

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DEPTH AND SHAPE FROM SHADING USING THE PHOTOMETRIC STEREO METHOD

CVGIP-IMAGE UNDERSTANDING

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CVGIP-IMAGE UNDERSTANDING 1991年第3期54卷 416-427页

作者： KIM, B BURGER, P Computer Vision and Graphics Group Department of Computing Imperial College of Science Technology and Medicine University of London 180 Queen's Gate London SW7 2BZ England

The independent calculation of local position and orientation of the Lambertian surface of an opaque object is proposed using the photometric stereo method. A number of shaded video images are taken using different positions of an ideal point light source which is placed close to the object. Normally, three images are required for a uniform and four for a textured Lambertian surface. By restricting three light sources to lie in a straight line, the depth calculations for an arbitrary surface with textured Lambertian reflection characteristics can be also determined; however, in this case the orientation of the surface cannot be calculated independently. It is shown that for both uniform and textured Lambertian surfaces the equations which are functions of three independent variables, namely, depth ( D ) and surface normal direction vector (n = [ p , q , − 1]), can be reduced to a single nonlinear equation of depth, i.e., the distance between the camera and the point on the surface. Both convergence and a unique solution are ensured because of the simple behavior of the nonlinear equation within a practical range of depth and gradient values. The robustness of the algorithm is demonstrated by synthetic as well as experimental data. The calculation of the approximate positions and orientations of discontinuous surfaces is demonstrated when random noise is added to the synthetically calculated image intensities. Two parallel planes with a gap, two sloped planes, and a spherical surface are used to demonstrate that the algorithms work well. An important feature of calculating both depth and orientation independently is that for smooth surfaces they must obey the partial differential expressions p = δ D δ x and q = δ D δ y . If we are certain that the experimental errors are within a known limit then the numerical approximation to these partial derivative expressions can be used to determine discontinuities within the image. On the other hand, if we know that the surface

关键词： Image Processing

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Mechanical Properties of Microsensor Materials: How to Deal with the Process Dependences?

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MRS Online Proceedings Library 1991年第1期239卷 3-11页

作者： Senturia, Stephen D. Barton L. Weiler Professor of Electrical Engineering Microsystems Technology Laboratories Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge

Microsensors are measurement devices fabricated using planar integrated circuit technology together with enhancements generically called “micromachining”. It is well known that the thin-film materials used in microelectronics can have properties which differ from their bulk counterparts. In addition, thin-film materials exhibit residual stress, which is known to be strongly process dependent. The sensor designer must understand how the detailed process used to fabricate a particular device impacts the specific mechanical properties, hence, the expected mechanical device performance. This paper illustrates the problem of process-dependent material properties using examples of residual stress of several materials, and then presents an object-oriented material-property database which is being developed as part of a CAD system for microelectromechan-ical systems (MEMCAD).

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STRESSES IN CONCRETE PANELS EXPOSED TO THE SUN ON THE MOON

STRESSES IN CONCRETE PANELS EXPOSED TO THE SUN ON THE MOON

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1ST TECHNICAL SYMP ON LUNAR CONCRETE

作者： LIN, TD AHMED, G HILL, G ROBINSON, S LIN, T LINDBERGH, C OGALLAGHER, J (1) Principal Research Engineer Construction Technology Laboratories Inc. Chairman ACI125.(2) Post Doctor Researcher Construction Technology Laboratories.(3) Former Cadets of Civil Engineering and Computer Science Department respectively The Citadel.(4) Graduate Student Ceramic Engineering Department University of Missouri - Rolla(5) Head of Civil Engineering Department The Citadel College(6) Professor Physics Department University of Chicago

ISBN: (纸本)9780870316234

The recently established Lunar/Mars Program Office at Johnson Space Center is studying options that include construction of lunar outposts in the early 21st Century, and subsequent structures for industrial operations. Major industrialization on the Moon cannot occur without an assess to lunar resources. Construction of structures such as large pressurized habitats, launching facilities, lunar surface transportation systems, and liquefied oxygen storage tanks requires enormous volumes of materials. Experiments sponsored by the National Aeronautics and Space Administration (NASA) and carried out at Construction technology Laboratories show that (1) cements can be made from lunar anorthite and basalt, (2) concrete made with lunar soils as aggregate has strength exceeding 10,000 psi, and (3) a dry mixture of of cement and aggregate wetted by injected steam will simplify concreting procedures and minimize needs for water and heavy equipment. In addition, a preliminary analysis of a prestressed precast concrete structure measuring 120 ft. in diameter and 72 ft. high, shows that a properly designed concrete structure can confine a one atmospheric internal pressure. This project further investigates the effect of lunar temperature extremes on the behavior of precast concrete panels during the construction period. The major work involves calculations of heat flow in concrete panels exposed to the sun on the lunar surface, thermal stresses in the panels caused by the transient heat flow. computer programs were written for the computations, and results are presented in figures 2 to 5. © 1991 American Concrete Institute. All rights reserved.

关键词： computer PROGRAMS CONCRETE PANELS HEAT TRANSFER LUNAR BASES PRECAST CONCRETE PRESTRESSED CONCRETE SUN THERMAL STRESSES

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ADAPTING AVAILABLE FINITE-ELEMENT STRUCTURAL PROGRAMS TO SOLVE 3-DIMENSIONAL HIGH-FREQUENCY ELECTROMAGNETIC PROBLEMS

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INTERNATIONAL JOURNAL OF MICROWAVE AND MILLIMETER-WAVE computer-AIDED ENGINEERING 1991年第4期1卷 386-394页

作者： NAVARRO, EA FEMENIA, JM SUCH, V Departamento de Fisica Aplicada Universitat de València C Doctor Moliner 50.46100 Burjassot (València) Spain Enrique A. Navarro was born in Sueca (Valéncia) Spain on January 18 1965. He received the Licenciado degree in Physics from the Universitat de Valéncia Spain in 1988. After working on Systems Simulation at GMV S.A. Madrid. Spain. he returned to the Universitat de Valéncia in 1980 where he began to study for the PhD degree in the Department de Fésica Aplicada. Universitat de Valéncia Spain. He is currently Assistant Professor in the Department of Applied Physics. His rescarch interests are in the area of microwave engineering and numerical method for solving electromagnetic wave propagation problems. Jose M. Femenia was born in Segorbe (Castellón) Spain in 1962. He obtained in Physics from the the Licenciado degree in Physics from the Universitat de Valéncia Spain in 1987 Universitat. After working in Laser and Optical Technology in the Department d'Optica di la Universitat de Valéncia he received a grant to work in numerical techniques for electromagnetics in the Departnment de Fisica Aplicada. He currently works in Computer Science and Communications in the Servei d'lnformàtica de la Universitat de Valéncia. Vicente Such was born in Valéncia Spain on August 10 1943. He received the Licenciado degree in Physics in 1967 and the PhD degree in 1971 both from the Universitat de Valéncia Spain. From 1967 to 1974 he was Assistant Professor with the Department of Electricity and Magnetism Universitat de Valéncia and with the Universitat Politécnica de Valkncia. From1974 to 1981 he was Professor of Electricity and Magnetism at the Universitat de Extremadura Universitat de Valéncia and Universidad de Palma de Mallorca Spain. He is now a Professor in the Department of Applied Physics at Universitat de Valéncia. His current research interests deal with microstrip antennas arrays Microwave passsive circuits and computer methods in electromagnetics.

The adaptation of available structural mechanics software to solve microwave problems is possible by the analogy between the differential equations. A brief review of the analogy between transverse or shear waves in elasticity and electromagnetic waves is presented, followed by a more detailed discussion of the adaptation of a program to obtain the resonant frequencies of a rectangular resonant cavity, doing a three-dimensional analysis. The geometry of the electric field is also obtained for the resonant modes.

关键词： Microwaves

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FULL-WAVE SOLUTION OF DIELECTRIC LOADED WAVE-GUIDES AND SHIELDED MICROSTRIPS UTILIZING FINITE-DIFFERENCE AND THE CONJUGATE-GRADIENT METHOD

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INTERNATIONAL JOURNAL OF MICROWAVE AND MILLIMETER-WAVE computer-AIDED ENGINEERING 1991年第4期1卷 346-357页

作者： NARAYANAN, V MANELA, M LADE, RK SARKAR, TK Department of Electrical and Computer Engineering Syracuse University Syracuse New York 13244-1240 Viswanathan Narayanan was born in Bangalore India on December 14 1965. He received the BE degree in Electronics and Communications from B.M.S. College of Engineering Bangalore in 1988. He joined the Department of Electrical Engineering at Syracuse University for his graduate studies in 1989 where he is currently a research assistant. His research interests are in microwave measurements numerical electromagnetics and signal processing. Biographies and photos are not available for M. Manela and R. K. Lade. Tapan K. Sarkar (Sf69-M'76-SM'X1) was born in Calcutta. India on August 2 1948. He received the BTech degree from the Indian Institute of Technology Kharagpur India in 1969 the MScE degree from the University of New Brunswick Fredericton Canada in 1971. and the MS and PhD degrees from Syracuse University. Syracuse NY in 1975. From 1975-1976 he was with the TACO Division of the General Instruments Corporation. He was with the Rochester Institute of Technology (Rochester NY) from 1976-1985. He was a Research Fellow at the Gordon Mckay Laboratory Harvard University Cambridge MA from 1977 to 1978. He is now a Professor in the Department of Electrical and Computer Engineering Syracuse University. His current research interests deal with numerical solutions of operator equations arising in electromagnetics and signal processing with application to system design. He obtained one of the “ best solution” awards in May 1977 at the Rome Air Development Center (RADC) Spectral Estimation Workshop. He has authored or coauthored more than 154 journal articles and conference papers and has written chapters in eight books. Dr. Sarkar is a registered professional engineer in the state of New York. He received the Best Paper Award of the IEEE Transactions on Electromagnetic Compatibility in 1979. He was an Associate Editor for feature articles of the lEEE Antennas arid Propagation Sociefy Newsletter and was

Dynamic analysis of waveguide structures containing dielectric and metal strips is presented. The analysis utilizes a finite difference frequency domain procedure to reduce the problem to a symmetric matrix eigenvalue problem. Since the matrix is also sparse, the eigenvalue problem can be solved quickly and efficiently using the conjugate gradient method resulting in considerable savings in computer storage and time. Comparison is made with the analytical solution for the loaded dielectric waveguide case. For the microstrip case, we get both waveguide modes and quasi-TEM modes. The quasi-TEM modes in the limit of zero frequency are checked with the static analysis which also uses finite difference. Some of the quasi-TEM modes are spurious. This article describes their origin and discusses how to eliminate them. Numerical results are presented to illustrate the principles.

关键词： Waveguides

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Realtime spline curves from interactively sketched data 90

Realtime spline curves from interactively sketched data

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1990 Symposium on Interactive 3D graphics, I3D 1990

作者： Banks, Michael J. Cohen, Elaine Computer Science University of Utah Salt Lake CityUT84112 United States Hewlett-Parkard Company Graphics Technology Division Fort CollinsCO80525 United States

ISBN: (纸本)0897913515

Hand-sketching is a particularly attractive solution to providing an intuitive design interface for modeling. The goal is to reduce the data collected from the input strokes and to construct a curve that faithfully represents the sketched data. This paper presents a new approach to interactive realtime handsketching in two or three dimensions and isbased on the new approach to general spline datafitting presented in [10,8,9]. The goal of our approach is to obtain approximating curves with reasonable accuracy at real-time interactive speeds, and at the same time significantly reduce in the number of coefficients for the curve representation over the original data representation. The approach taken here to obtain realtime interaction is to reduce the data incrementally using new local algorithms while the data is still being sketched. © 1990 ACM.

关键词： Interactive computer graphics

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Real-time robot motion planning using rasterizing computer graphics hardware 90

Real-time robot motion planning using rasterizing computer g...

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Proceedings of the 17th annual conference on computer graphics and interactive techniques

作者： Jed Lengyel Mark Reichert Bruce R. Donald Donald P. Greenberg Graduate Student Program of Computer Graphics Cornell University Ithaca N.Y. Assistant Professor and Director Computer Science Robotics Laboratory Department of Computer Science 4130 Upson HalI Cornell University Ithaca N.Y. Director Program of Computer Graphics Jacob Gould Shurman Professor of Computer Graphics Cornell University Ithaca N.Y.

ISBN: (纸本)9780897913447

We present a real-time robot motion planner that is fast and complete to a resolution. The technique is guaranteed to find a path if one exists at the resolution, and all paths returned are safe. The planner can handle any polyhedral geometry of robot and obstacles, including disjoint and highly concave unions of *** planner uses standard graphics hardware to rasterize configuration space obstacles into a series of bitmap slices, and then uses dynamic programming to create a navigation function (a discrete vector-valued function) and to calculate paths in this rasterized space. The motion paths which the planner produces are minimal with respect to an L1 (Manhattan) distance metric that includes rotation as well as *** examples are shown illustrating the competence of the planner at generating planar rotational and translational plans for complex two and three dimensional robots. Dynamic motion sequences, including complicated and non-obvious backtracking solutions, can be executed in real time.

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