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Computer

Issue 7 • Date July 1993

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Displaying Results 1 - 6 of 6
  • A framework for controlling cooperative agents

    Page(s): 8 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (980 KB)  

    Presents an overview of the ITX (Interacting Transaction) system, which supports complex interactions among cooperating agents in the presence of user interventions that change application objectives and system failures. The system's components and its unique fixed-point criterion for feedback control of iterative interactions are described. An example of a simplified multimedia teleconferencing application is discussed to illustrate the features of the ITX system.<> View full abstract»

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  • An investigation of the Therac-25 accidents

    Page(s): 18 - 41
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1759 KB)  

    Between June 1985 and January 1987, the Therac-25 medical electron accelerator was involved in six massive radiation overdoses. As a result, several people died and others were seriously injured. A detailed investigation of the factors involved in the software-related overdoses and attempts by users, manufacturers, and government agencies to deal with the accidents is presented. The authors demonstrate the complex nature of accidents and the need to investigate all aspects of system development and operation in order to prevent future accidents. The authors also present some lessons learned in terms of system engineering, software engineering, and government regulation of safety-critical systems containing software components.<> View full abstract»

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  • Scaling parallel programs for multiprocessors: methodology and examples

    Page(s): 42 - 50
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (984 KB)  

    Models for the constraints under which an application should be scaled, including constant problem-size scaling, memory-constrained scaling, and time-constrained scaling, are reviewed. A realistic method is described that scales all relevant parameters under considerations imposed by the application domain. This method leads to different conclusions about the effectiveness and design of large multiprocessors than the naive practice of scaling only the data set size. The primary example application is a simulation of galaxies using the Barnes-Hut hierarchical N-body method.<> View full abstract»

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  • Volume graphics

    Page(s): 51 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1073 KB)  

    Volume graphics, which employs a volume buffer of voxels for 3D scene representation, is discussed. Volume graphics offers advantages over surface graphics: it is viewpoint independent, insensitive to scene and object complexity, and suitable for the representation of sampled and simulated data sets. Moreover, geometric objects can be mixed with these data sets. Volume graphics supports the visualization of internal structures and lends itself to the realization of block operations, constructive solid geometry modeling, irregular voxel sizes, and hierarchical representation. The problems associated with the volume buffer representation (such as discreteness, memory size, processing time, and loss of geometric representation) are discussed.<> View full abstract»

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  • Hot topics-eye-gaze computer interfaces: what you look at is what you get

    Page(s): 65 - 66
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (302 KB)  

    As computers are becoming more powerful, the critical bottleneck in their use is often in the user interface, not in the computer processing. Research in human-computer interaction that seeks to increase the communication bandwidth between the user and the machine by using input from the user's eye movement is discussed. The speed potential, processing stages, interaction techniques, and problems associated with these eye-gaze interfaces are described.<> View full abstract»

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Computer, the flagship publication of the IEEE Computer Society, publishes highly acclaimed peer-reviewed articles written for and by professionals representing the full spectrum of computing technology from hardware to software and from current research to new applications.

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Editor-in-Chief
Ron Vetter
University of North Carolina
Wilmington