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 ...
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Visualization and animation tools may become extremely important aids in the understanding, verification, and performance tuning of parallel computations. Presently, however, the use of visualization has had only a li...
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Visualization and animation tools may become extremely important aids in the understanding, verification, and performance tuning of parallel computations. Presently, however, the use of visualization has had only a limited use for enhancing parallel computation. We hypothesize that one of the primary reasons for the limited use of visualization tools in parallel program development is the difficulty of acquiring the information necessary to drive the visual display. Our approach to this impediment focuses on integrating visualization support directly into a distributed computing system. Central to this integration is the addition of a logical clock that prevents the timestamps of events from violating causality. The implementation requires the "piggybacking" of a negligible amount of extra header information on system messages and the impact on performance is minimal. This results in a system that produces useful visualizations with no extra effort required by the applications programmer. Also integrated into the distributed system is support which simplifies the creation of programmer-defined, application-specific visualizations, unique to each new parallel program developed.
Particle-based flow visualization techniques are used for the investigation of huge, complex data sets from computational fluid dynamics (CFD). Particle tracing requires the interpolation of local velocity inside a di...
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Particle-based flow visualization techniques are used for the investigation of huge, complex data sets from computational fluid dynamics (CFD). Particle tracing requires the interpolation of local velocity inside a discretized data set and the numerical integration, to find succeeding spatial positions of the moving particles. More and more often, CFD-data is computed on unstructured Finite Element grids, which makes interpolation and integration difficult. One strategy is to resample the unstructured volume data to a regular one. In contrast to this, this article describes how particle tracing can be performed directly inside unstructured grids, thereby preserving the quality and size of the original data for visualization: The basic idea is to perform the integration in the computational space of the individual cells of the grid. This leads to a faster computation of the particle's new position and an easier determination of the corresponding new cell into which the particle has moved. The proposed algorithms allow an interactive investigation with real-time computation of particle trajectories of huge data sets that are organized on unstructured grids.
Current user interface builders provide only low-level assistance, because they have knowledge of neither the application, nor the principles by which interface elements are combined effectively. We have developed a f...
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ISBN:
(纸本)9051991339
Current user interface builders provide only low-level assistance, because they have knowledge of neither the application, nor the principles by which interface elements are combined effectively. We have developed a framework that unites the knowledge components essential for effective user interface presentation design. The framework consists of an application model (both a data model and a control model), a design process model that supports top-down iterative development, and graphic design knowledge that is used both to place dialog box elements such that their application dependent logical relationships are visually reinforced and to control design symmetry and balance. To demonstrate the framework's viability, we have constructed a tool based on encapsulated design knowledge that establishes high-level style preferences and provides expert assistance for the dialog box presentation design and menu structuring.
As technology advances and our dependency on software increases, the requirement to develop the correct means to improve quality in both the deveiopment phase and the maintenance phase of software life cycle support b...
As technology advances and our dependency on software increases, the requirement to develop the correct means to improve quality in both the deveiopment phase and the maintenance phase of software life cycle support becomes increasingly significant. The focus of this paper is on the dilemma facing software engineering in maintaining quality within the constraints of the maintenance phase. The paper further proposes that the software maintenance process can also be analvzed and improved using statistical process control (SPC) techniques. The methods discussed in this paper have been proposed for use in the Software Maintenance project at NUWC Detachment Norfolk. Upon successful testing at NUWC Detachment Norfolk, they will be forwarded to the AN/SQQ-89(V) (interagencv) Software Quality Evaluation Committee for use by other agencies which are developing and maintaining AN/SQQ-89(V) software.
Traditional models of input work on the assumption that inputs delivered to a system are fairly certain to have occurred as they are reported. However, a number of new input modalities, such as pen-based inputs, hand ...
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ISBN:
(纸本)0897915496
Traditional models of input work on the assumption that inputs delivered to a system are fairly certain to have occurred as they are reported. However, a number of new input modalities, such as pen-based inputs, hand and body gesture inputs, and voice input, do not share this property. Inputs under these techniques are normally acquired by a process of recognition. As a result, each of these techniques makes mistakes and provides inputs which are approximate or uncertain. This paper considers some preliminry techniques for dialog management in the presence of this uncertainty. These techniques—including a new input model and a set of extended state machine abstractions—will explicitly model uncertainty and handle it as a normal and expected part of the input process.
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