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33rd Aerospace sciences Meeting and Exhibit, 1995

作者： Ehtesham Hayder, M. Jayasimha, D.N. Pillay, Sasi Kumar Institute for Computational Mechanics in Propulsion Ohio Aerospace Institute NASA Lewis Research Center ClevelandOH United States Department of Computer Science The Ohio State University ColumbusOH United States Chief Computer Graphics Branch Computer Services Division NASA Lewis Research Center ClevelandOH United States

We study a high order finite difference scheme to solve the time accurate flow field of a jet using the compressible Navier-Stokes equations. As part of OUT ongoing efforts, we have implemented our numerical model on three parallel computing platforms to study the computational, communication, and scalability characteristics. The platforms chosen for this study are a cluster of workstations connected through h t networks (the LACE experimental testbed at NASA Lewis), a shared memory multiprocessor (the Cray YMP), and a distributed memory multiprocessor (the IBM SP1). Our focus in this study is on the LACE testbed. We present some results for the Cray YMP and the IBM SP1 mainly for comparison purposes. On the LACE testbed, we study: (a) the communication characteristics of Ethernet, FDDI and the ALLNODE networks and (b) the overheads. © 1995 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Testbeds

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The virtual tricorder: a uniform interface for virtual reality 95

The virtual tricorder: a uniform interface for virtual reali...

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Proceedings of the 8th annual ACM symposium on User interface and software technology

作者： Matthias M. Wloka Eliot Greenfield Science and Technology Center for Computer Graphics and Scientific Visualization Brown University Site Department of Computer Science Box 1910 Providence RI

No abstract available.

ISBN: (纸本)9780897917094

No abstract available.

关键词： user-interface metaphor 3D user interface tactile feedback immersive virtual reality

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SUPERVISED INTERPRETATION OF ECHOCARDIOGRAMS WITH A PSYCHOLOGICAL MODEL OF EXPERT SUPERVISION

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computerIZED MEDICAL IMAGING AND graphics 1995年第1期19卷 47-59页

作者： REVANKAR, S SHER, D CHEUNG, C SHALIN, VL RAMAMURTHY, M ROSENTHAL, S Department of Computer Science State University of New York at Buffalo 226 Bell Hall Buffalo NY 14260 U.S.A. Department of Industrial Engineering State University of New York at Buffalo 342 Bell Hall Buffalo NY 14260 U.S.A. Echocardiography-Graphics Laboratory University of Alabama Hospital Birmingham AL 35213 U.S.A.

We have developed a collaborative scheme that facilitates active human supervision of the binary segmentation of an echocardiogram. The scheme complements the reliability of a human expert with the precision of segmentation algorithms. In the developed system, an expert user compares the computer generated segmentation with the original image in a user friendly graphics environment, and interactively indicates the incorrectly classified regions either by pointing or by circling. The precise boundaries of the indicated regions are computed by studying original image properties at that region, and a human visual attention distribution map obtained from the published psychological and psychophysical research. We use the developed system to extract contours of heart chambers from a sequence of two dimensional echocardiograms. We are currently extending this method to incorporate a richer set of inputs from the human supervisor, to facilitate multi-classification of image regions depending on their functionality. We are integrating into our system the knowledge related constraints that cardiologists use, to improve the capabilities of our existing system. This extension involves developing a psychological model of expert reasoning, functional and relational models of typical views in echocardiograms, and corresponding interface modifications to map the suggested actions to image processing algorithms.

关键词： ECHOCARDIOGRAPHY IMAGE SEMANTICS INTERACTIVE IMAGE ANALYSIS MEDICAL IMAGE ANALYSIS PERCEPTUAL AND COGNITIVE ORGANIZATION ULTRASOUND VISUAL ATTENTION

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Visual navigation of large environments using textured clusters 95

Visual navigation of large environments using textured clust...

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Proceedings of the 1995 symposium on Interactive 3D graphics

作者： Paulo W. C. Maciel Peter Shirley Department of Computer Science Lindley Hall Indiana University Bloomington Indiana Program of Computer Graphics Cornell University Ithaca New York

ISBN: (纸本)9780897917360

A visual navigation system is described which uses texture mapped primitives to represent clusters of objects to maintain high and approximately constant frame rates. In cases where there are more unoccluded primitives inside the viewing frustum than can be drawn in real-time on the workstation, this system ensures that each visible object, or a cluster that includes it, is drawn in each frame. The system supports the use of traditional “level-of-detail” representations for individual objects, and supports the automatic generation of a certain type of level-of-detail for objects and clusters of objects. The concept of choosing a representation from among those associated with an object that accounts for the direction from which the object is viewed is also supported. The level-of-detail concept is extended to the whole model and the entire scene is stored as a hierarchy of levels-of-detail that is traversed top-down to find a good representation for a given viewpoint. This system does not assume that visibility information can be extracted from the model and is thus especially suited for outdoor environments.

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High Dimensional Brushing for Interactive Exploration of Multivariate Data 95

High Dimensional Brushing for Interactive Exploration of Mul...

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IEEE Conference on Visualization

作者： A.R. Martin M.O. Ward Advanced Graphics Division Silicon Graphics Inc. Mountain View CA USA Computer Science Department Worcester Polytechnic Institute Worcester MA USA

ISBN: (纸本)9780818671876

Brushing is an operation found in many data visualization systems. It is a mechanism for interactively selecting subsets of the data so that they may be highlighted, deleted, or masked. Traditionally, brushes have been defined in screen space via methods such as painting and rubberband rectangles. In this paper we describe the design of N-dimensional brushes which are defined in data space rather than screen space, and show how they have been integrated into XmdvTool, a visualization package for displaying multivariate data. Depending on the data display technique in use, brushes may be specified and manipulated via direct or indirect methods, and the specification may be demand-driven or data-driven. Various brush operations such as highlighting, linking, masking, moving average, and quantitative display have been developed to apply to the selected data. In addition, we have explored several new brush concepts, such as non-discrete brush boundaries, simultaneous display of multiple brushes, and creating composite brushes via logical operators. Preliminary experimental evaluation with test subjects supports the usefulness of N-dimensional brushes in data exploration tasks.

关键词： Brushes Displays Data visualization graphics Scattering Silicon Painting Packaging Joining processes Testing

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Experience with an interactive attribute-based user information environment

Experience with an interactive attribute-based user informat...

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International Phoenix Conference on computers and Communications (IPCCC)

作者： C.E. Wills D. Giampaolo M.S. Mackovitch Computer Science Department Worcester Polytechnic Institute Worcester MA USA Silicon Graphics Inc. CA USA

This paper explores an attribute-based approach to storing information in the context of a file system that supports extended attributes about files and a mechanism to manipulate files based on logical queries and comparisons of attributes. The novel aspects of our system are that it is sophisticated enough to operate as a user's primary method of interaction with the operating system and that it supports derived attributes whose values are derived at look-up time. Organizational mechanisms are explored to aid in the navigation of the system. We implemented our system as a user-level NFS server that supports attribute-based naming of files and other objects. We discuss its details, our experiences with it and performance comparisons between it and a traditional hierarchical file system. Overall the work is successful by demonstrating the feasibility of an attribute-based environment that can be a user's interface to the underlying system.< >

关键词： Hierarchical systems computer science File systems File servers Tail User interfaces Silicon computer graphics Information management Tree data structures

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Partitioning for synchronous parallel simulation

Partitioning for synchronous parallel simulation

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Workshop on Principles of Advanced and Distributed Simulation (PADS)

作者： P. Konas Pen-Chung Yew Silicon Graphics Inc. Mountain View CA USA Department of Computer Science University of Minnesota Minneapolis MN USA

A new partitioning method for synchronous PDES simulations is proposed. The method exploits characteristics of both the simulation method and of the application domain to arrive at efficient partitionings. A performance study shows that the method outperforms existing partitioning methods in terms of four different performance metrics.< >

关键词： Computational modeling Partitioning algorithms Iterative algorithms Predictive models Silicon graphics Parallel machines NASA computer science computer simulation

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A model and tools for supporting parallel real-time applications in Unix environments

A model and tools for supporting parallel real-time applicat...

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Real-Time Technology and Applications Symposium

作者： R.W. Wisniewski L.F. Stevens Department of Computer Science University of Rochester Rochester NY USA Silicon Graphics Inc. Mountain View CA USA

As real-time applications become more complex, it becomes increasingly important to provide both a clean model for their development and the ability to verify that their execution matches the development model. In addition to becoming more complex, soft real-time programs are becoming more mainstream, and as such are being run on platforms running some variant of Unix. It is even more important in these environments to be able to monitor a program and understand its behavior. We describe a frame scheduler that provides a simple model to the real-time programmer while maintaining considerable flexibility. We motivate and describe the implementation of FrameView, a set of tools closely coupled with the frame scheduler. Since FrameView and the frame scheduler were developed in conjunction with each other and are tightly coupled, they provide a powerful and efficient means for programmers to implement, analyze and modify soft parallel real-time applications. The frame scheduler is fully implemented in IRIX 5.3, and FrameView is in beta release. In this paper, we describe our experiences building and using the frame scheduler and FrameView.

关键词： Programming profession Kernel Application software Processor scheduling Timing Monitoring High performance computing computer science Silicon computer graphics

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Processor self-scheduling in parallel discrete event simulation

Processor self-scheduling in parallel discrete event simulat...

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Simulation Winter Conference

作者： P. Konas Pen-Chung Yew Silicon Graphics Inc. Mountain View CA USA Department of Computer Science University of Minnesota Minneapolis MN USA

This paper describes a novel data structure and an algorithm for processor self-scheduling in parallel discrete event simulation. The presented data structure allows the efficient scheduling of future computations, it facilitates the inexpensive use of processor affinity information, it reduces the contention on the scheduling queue, and it integrates load balancing and locality management methods into a single mechanism. We use the behavioral simulation of a multiprocessor system to characterize the behavior of the proposed data structure and the associated scheduling algorithm. The results of our study show that it is important to maintain as detailed affinity information as possible and exploit this information at run time.

关键词： Discrete event simulation Computational modeling Processor scheduling Load management Data structures Multiprocessing systems Optimization methods Predictive models Concurrent computing Distributed computing

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Practical methods for approximating shortest paths on a convex polytope in R3 95

Practical methods for approximating shortest paths on a conv...

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Proceedings of the sixth annual ACM-SIAM symposium on Discrete algorithms

作者： John Hershberger Subhash Suri Mentor Graphics 1001 Ridder Park Drive San Jose CA Department of Computer Science Washington University St. Louis MO

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