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12th Computational Fluid Dynamics Conference, 1995

作者： Fiterman, A. Turkel, E. Vatsa, V. Department of Environmental Sciences and Energy Research Weizmann Insittute Rechovot Israel Institute for Computer Applications in Science and Engineering School of Mathematical Sciences Tel-Aviv University Ramat-Aviv Tel-Aviv Israel NASA Langley Research Center HamptonVA United States

We consider the steady state equations for a compressible fluid. Since we wish to solve for a range of speeds we must consider the equations in conservation form. For transonic speeds these equations are of mixed type. Hence, the usual approach is to add time derivatives to the steady state equations and then march these equations in time. One then adds a time derivative of the density to the continuity equation, a derivative of the momentum to the momentum equation and a derivative of the total energy to the energy equation. This choice is dictated by the time consistent equations. However, since we are only interested in the steady state this is not necessary. Thus we shall consider the possibility of adding a time derivative of the pressure to the continuity equation and similar modifications for the energy equation. This can then be generalized to adding combinations of time derivatives to each equation since these vanish in the steady state. When using acceleration techniques such as residual smoothing, multigrid, etc. these are applied to the pressure rather than the density. Hence, the code duplicates the behavior of the incompressible equations for low speeds. © 1995 by the American institute of Aeronautics and Astronautics, Inc.

关键词： Equations of state

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Mapping of backpropagation learning onto distributed memory multiprocessors

Mapping of backpropagation learning onto distributed memory ...

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IEEE International Conference on Algorithms and Architectures for Parallel Processing (ICAP)

作者： S. Mahapatra R.N. Mahapatra Department of Electronics & Electrical Communication Engineering Indian Institute of Technology Kharagpur India Department of Computer Science Engineering & Applications Regional Engineering College Orissa India

This paper presents a mapping scheme for parallel pipelined execution of the Backpropagation Learning Algorithm on distributed memory multiprocessors (DMMs). The proposed implementation exhibits training set parallelism that involves batch updating. Simple algorithms have been presented, which allow the data transfer involved in both forward and backward executions phases of the backpropagation algorithm to be carried out with a small communication overhead. The effectiveness of our mapping has been illustrated, by estimating the speedup of a proposed implementation on an array of T-805 transputers.< >

关键词： Multi-layer neural network Parallel processing Backpropagation algorithms Neural networks Neurons Performance analysis Parallel architectures Visualization computer science Application software

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Interactive shape metamorphosis 95

Interactive shape metamorphosis

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Proceedings of the 1995 symposium on Interactive 3D graphics

作者： David T. Chen Andrei State David Banks Department of Computer Science University of North Carolina at Chapel Hill Institute for Computer Applications in Science and Engineering Mail Stop 132C NASA Langley Research Center Hampton Virginia

ISBN: (纸本)9780897917360

Image metamorphoses (morphing) is a powerful and easy-to-use tool for generating new 2D images from existing 2D images. In recent years morphing has become popular as an artistic tool and is used extensively in the entertainment industry. In this paper we describe a new technique for controlled, feature-based metamorphosis of certain types of surfaces in 3-space; it applies well-understood 2D methods to produce shape metamorphosis between 3D models in a 2D parametric space. We also describe an interactive implementation on a parallel graphics multicomputer, which allows the user to define, modify and examine the 3D morphing process in real time.

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Runtime support for data parallel tasks

Runtime support for data parallel tasks

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Frontiers of Massively Parallel Computation

作者： M. Haines B. Hess P. Mehrotra J. Van Rosendale H. Zima Institute for Computer Applications in Science and Engineering NASA-Langley Research Center Hampton VA USA Institute for Software Technology and Parallel Systems University of Technology Vienna Vienna Austria

We have recently introduced Opus, a set of Fortran language extensions that provide shared data abstractions (SDAs) as a mechanism for communication and synchronization among coarse-grain data parallel tasks. In this paper, we discuss the design and implementation issues of the runtime system necessary to support SDAs, and outline the underlying requirements for such a runtime system. We explore the feasibility of this approach by implementing a prototype of the runtime system. We give preliminary results of the prototype on the Intel Paragon, outline the current status of the project, and discuss future plans.< >

关键词： Runtime Aircraft propulsion NASA Prototypes Data structures Parallel languages Parallel processing Design optimization Aerospace control computer applications

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The widest practicable dissemination: The NASA technical report server 10th

The widest practicable dissemination: The NASA technical rep...

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10th Computing in Aerospace Conference, 1995

作者： Nelson, Michael L. Gottlich, Gretchen L. Bianco, David J. Binkley, Robert L. Kellogg, Yvonne D. Paulson, Sharon S. Beaumont, Chris J. Schmunk, Robert B. Kurtz, Michael J. Accomazzi, Alberto NASA Langley Research Center HamptonVA United States Computer Sciences Corporation NASA Langley Research Center HamptonVA United States NASA Dryden Flight Research Center EdwardsCA United States Institute for Computer Applications in Science and Engineering HamptonVA United States Computer Sciences Corporation NASA Ames Research Center Moffett FieldCA United States NASA Goddard Institute of Space Studies National Research Council New YorkNY United States Smithsonian Astrophysical Observatory CambridgeMA United States

The National Aeronautics and Space Act of 1958 established NASA and charged it to "provide for the widest practicable and appropriate dissemination of information concerning […] its activities and the results thereof." The search for innovative methods to distribute NASA’s information lead a grass-roots team to create the NASA Technical Report Server (NTRS), which uses the World Wide Web and other popular Internet-based information systems as search engines. The NTRS is an inter-center effort which provides uniform access to various distributed publication servers residing on the Internet. Users have immediate desktop access to technical publications from NASA centers and institutes. The NTRS is comprised of several units, some constructed especially for inclusion in NTRS, and others that are existing NASA publication services that NTRS reuses. This paper presents the NTRS architecture, usage metrics, and the lessons learned while implementing and maintaining the services over the initial 6-month period. The NTRS is largely constructed with freely available software running on existing hardware. NTRS builds upon existing hardware and software, and the resulting additional exposure for the body of literature contained will allow NASA to ensure that its institutional knowledge base will continue to receive the widest practicable and appropriate dissemination. © 1995, American institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： NASA

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Tracking a turbulent spot in an immersive environment 95

Tracking a turbulent spot in an immersive environment

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Proceedings of the 1995 symposium on Interactive 3D graphics

作者： David C. Banks Michael Kelley Institute for Computer Applications in Science and Engineering ICASE Mail Stop 132C. NASA Langley Research Center Hampton Virginia Information Sciences Institute 4350 N. Fairfax Drive Suite 400 Arlington VA

ISBN: (纸本)9780897917360

We describe an interactive, immersive 3D system called Tracktur, which allows a viewer to track the development of a turbulent flow. Tracktur displays time-varying vortex structures extracted from a numerical flow simulation. The user navigates the space and probes the data within a windy 3D landscape. In order to sustain a constant frame rate, we enforce a fixed polygon budget on the geometry. In actual use by a fluid dynamicist, Tracktur has yielded new insights into the transition to turbulence of a laminar flow.

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Development and application of MCAL tools for marine radar instruction

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computer applications in engineering Education 1995年第4期3卷 259-259页

作者： Guirguis, S. Korany, E. Abdel-Bary, A. Institute of Graduate Studies and Research Alexandria University Alexandria Egypt Shawkat K. Guirguis:obtained the BSc and M.Sc. degrees in Computer Science and Automatic Control Faculty of Engineering Alexandria University in 1981 and 1984 respectively. In 1988 he obtained a PhD degree in Electronics and Communications Faculty of Engineering Cairo University co-supervised by the Imperial College of Science and Technology University of London where he spent two years as an academic visitor. His current research interests include software quality management multimedia automatic programming and decision support systems. He is currently a lecturer of Computer Science at the Institute of Graduate Studies & Research Alexandria University. Ezzat A. Korany:received the BS degree in Electrical Engineering (Electronics Section) from the University of Alexandria Egypt in 1971 the MS degree in Electrical Engineering (Computer Section) from Ain Shams University Cairo Egypt in 1977 and the PhD degree in Electrical Engineering (Digital Systems) from Florida Institute of Technology U.S.A. in 1982. He is currently an associate professor of Computer Science at the Institute of Graduate Studies & Research University of Alexandria. His research interests are in data communications and multimedia applications computer networks image processing and pattern recognition. Abdel-Latif A. Abdel-Bary:obtained the BEng degree in Electronics Technology from Arab Maritime Transport Academy in 1986. In 1995 he obtained the MSc degree in Information Technology from the Institute of Graduate Studies & Research Alexandria University. His current research interests include ICAL hypermedia and automatic programming.

In this article a multimedia computer-assisted learning (MCAL) system is presented. The major objective of this work was to investigate the potential of using such systems as tools for transferring instructional course information through various types of computer media as opposed to the classic CAL systems. The philosophy and techniques employed to design the system are investigated. Usage of the implemented system and its merits have been illustrated through its application to teach engineering students and technicians the theory and concepts of marine radar. System design, implementation, test, and revision phases are presented and discussed.

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CONCURRENT LARGE-SIGNAL SIMULATION OF AN ACTIVE MICROSTRIP ANTENNA

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INTERNATIONAL JOURNAL OF NUMERICAL MODELLING-ELECTRONIC NETWORKS DEVICES AND FIELDS 1995年第1期8卷 3-12页

作者： MCDOWALL, DS FUSCO, VF High Frequency Electronics Laboratory. Department of Electrical and Electronic Engineering The Queen's University of Belfast Ashby Building Stranmillis Road Belfast BT9 5AH U.K. D. Stewart McDowall was born in Dublin Republic of Ireland in 1967. He received the M. Eng. degree in Electrical and Electronic Engineering from the Queen's University of Belfast in 1990. In the same year he was presented with a Distinction Award from the Departmnet of Education of Northern Ireland and he is currently pursuing his Ph.D. in the Microwave Research Group at Q.U.B. His principal research area is the electromagnetic field mapping of microwave systems using concurrent programming. He is an Associate Member of the Institute of Electrical Engineers. Vincent F. Fusco was educated at the Queens's University of Belfast where he obtained the degree of Ph.D. in 1982. He has worked as a research engineer on short-range radar and radio telemetry systems. Currently he is a reader in Microwave Communications in the School of Electrical engineering and Computer Science the Queen's University of Belfast. His current research interests include non-linear microwave circuit simulatino and concurrent programming techniques for electromagnetic field problems with particular emphasis on EMC applications. He has published numerous research papers in these areas. He is the author of the bookMicrowave Circuits Analysis and Computer Aided Design Prentice-Hall 1987. Dr Fusco is a Chartered Electrical Engineer and a Member of the Institute of Electrical Engineers.

This paper details the use of a circuit-based EM modelling technique combined with a harmonic balance simulator used to model the radiation from the microstrip bodies comprising an active antenna circuit. The modelling approach adopted for the planar bodies in the circuit will be shown to allow the use of concurrent algorithms in order to reduce overall computational time.

关键词： Microstrip antennas

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Undersea technologies in the former Soviet Union

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NAVAL ENGINEERS JOURNAL 1995年第6期107卷 85-92页

作者： DeHaemer, DJ Dr. Michael J. DeHaemer:is Director of the World Technology Evaluation Center and the Japanese Technology Evaluation Center at Loyola College in Baltimore. He has directed more than a dozen studies of technologies in foreign countries under the sponsorship of the National Science Foundation ARPA Departments of Energy and Commerce and other agencies. He has a continuing interest in assessing foreign technologies in comparison to the United States.—-On the faculty of the Sellinger School of Business at Loyola College Dr. DeHaemer is a former department chairman and an associate professor of information systems and decision sciences. He teaches the strategic use of information technology and human-computer interface design. His research includes user performance with automated speech recognition systems for computers and business applications of artificial intelligence. Dr. DeHaemer completed an earlier career as a submarine officer including command of a ballistic missile submarine. He holds a B.S. degree from the University of Notre Dame and a Master's degree in Operations Analysis from the Naval Postgraduate School. He has an M.B.A. an M.S. in Industrial Engineering and a Ph.D. in Management Information Systems from Rensselaer Polytechnic Institute.

A team of experts, assembled by the World Technology Evaluation Center, visited twenty-five locations in Russia and Ukraine to observe the state of undersea technologies. Academic sites, basic research institutes, industrial development laboratories, and oceanographic operating bases were visited. The report highlights specific technologies that support research submersibles;and critiques the strengths and weaknesses of the ocean technologies establishment. Russia and Ukraine were found to have a number of strengths, especially in test facilities, a large fleet of surface and submersible research vessels, and highly educated and qualified engineers and scientists. Although political and economic conditions need to be over-come, there is motivation for many cooperative commercial or research ventures with both government institutes and new private companies in Russia and Ukraine.

关键词： Ocean engineering

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AN ALTERNATIVE TO UNSTRUCTURED GRIDS FOR COMPUTING GAS-DYNAMIC FLOWS AROUND ARBITRARILY COMPLEX 2-DIMENSIONAL BODIES

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computerS & FLUIDS 1994年第1期23卷 125-142页

作者： QUIRK, JJ Institute for Computer Applications in Science and Engineering NASA Langley Research Center Hampton VA 23681 U.S.A.

Within the shock-capturing community, the need to simulate flows around geometrically complex bodies has resulted in an inexorable shift away from schemes which employ body-fitted grids to schemes which employ unstructured grids. Although unstructured grids are undeniably effective, in view of the increasing reliance placed on computational results, such a wholesale shift in mentality should give cause for concern. The concept of using several computer codes to cross-check numerical results becomes ill-founded if all codes follow the same methodology. In this paper we describe an alternative approach for dealing with arbitrarily complex two-dimensional geometries, the so-called Cartesian boundary method. Conceptually, the Cartesian boundary method is quite simple. Solid bodies blank out areas of a background, Cartesian mesh, and the resultant cut cells are singled out for special attention. However, there are several obstacles that must be overcome in order to achieve a practical scheme. We present a general strategy that overcomes these obstacles, together with details of our successful conversion of an adaptive mesh algorithm from a body-fitted code to a Cartesian boundary code.

关键词： Gas dynamics

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