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Computing in Science & Engineering

Issue 4 • Date July-Aug. 1999

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Displaying Results 1 - 10 of 10
  • Massive Data Visualization

    Page(s): 16 - 17
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  • Tex to Web-fast and easy

    Page(s): 63 - 65
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    The Web has become a repository for a wide range of easily accessed information-from lecture notes to articles to recipes-all on hand for a large, varied audience. However, the ease of publishing (or posting) your information should match the ease of retrieval (download times notwithstanding). The author discusses software that converts documents created with Tex or LaTex into HTML files with minimal effort, and a plug-in that lets Web browsers view Tex and LaTex files View full abstract»

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  • Hysteresis, avalanches, and noise

    Page(s): 73 - 81
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    In our studies of hysteresis and avalanches in the zero-temperature random-field Ising model, a simple model of magnetism, we often have had to do very large simulations. Previous simulations were usually limited to relatively small systems (up to 9002 and 1283), although there have been exceptions. In our simulations, we have found that larger systems (up to a billion spins) are crucial to extracting accurate values of the critical exponents and understanding important qualitative features of the physics. We show three algorithms for simulating these large systems. The first uses the brute-force method, which is the standard method for avalanche-propagation problems. This algorithm is simple but inefficient. We have developed two efficient and relatively straightforward algorithms that provide better results. The sorted-list algorithm decreases execution time, but requires considerable storage. The bits algorithm has an execution time that is similar to that of the sorted-list algorithm, but it requires far less storage View full abstract»

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  • Using multivariate clustering to characterize ecoregion borders

    Page(s): 18 - 25
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    The authors present a geographic clustering technique which unambiguously locates, characterizes, and visualizes ecoregions and their borders. When coded with similarity colors, it can produce planar map views with sharpness contours that are visually rich in ecological information and represent integrated visualizations of complex and massive environmental data sets View full abstract»

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  • How templates enable high-performance scientific computing in C++

    Page(s): 66 - 72
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    The C++ programming language has a powerful template facility that enables the development of flexible software without incurring a large abstraction penalty. Templates let programmers tell the compiler how to create classes and functions parametrized in terms of other types and constants. Programmers often use templates to implement type-safe generic containers that hold elements of a particular type, or generic functions that can, for example, sort the elements in an arbitrary generic container. Templates are one of the most complex C++ language features. For this reason, they were deliberately left out of the Java programming language. Nevertheless, templates are the fundamental enabling technology that supports construction of maintainable, highly abstract, high performance scientific codes in C++. To support our thesis, we use examples from the Pooma framework. Pooma supports high performance scientific computing by providing high level math and physics abstractions such as multidimensional arrays, fields, particles, and transforms. It encapsulates the details associated with parallelism, enabling scientists to develop software on serial platforms and then transition quickly to parallel execution View full abstract»

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  • Data sonification and sound visualization

    Page(s): 48 - 58
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    Sound can help us explore and analyze complex data sets in scientific computing. The authors describe a digital instrument for additive sound synthesis (Diass) and a program to visualize sounds in a virtual reality environment (M4Cave). Both are part of a comprehensive music composition environment that includes additional software for computer-assisted composition and automatic music notation View full abstract»

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  • 3D knee modeling and biomechanical simulation

    Page(s): 82 - 87
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    Knee osteotomy is a kind of orthopedic surgery to realign the lower limb by opening or cutting a bone wedge from the leg. It is a better alternative than other types of knee-replacement surgeries, especially for young people. However, knee osteotomy requires understanding the imbalance of stresses at the knee joint, analyzing an abnormal gait cycle, and cutting the bone wedge precisely. Therefore, it is difficult and can cause further damage even though it is simply a bone cut. While some computer based surgical simulation systems have been developed to help surgeons perform knee surgeries, the knee models used either are not patient-specific or lack kinematic and kinetic information. We discuss how we use computer graphics, physics based modeling, and interactive visualization to assist knee-surgery study and osteotomies. Our patient-specific 3D knee surface model helps us calculate the contact stresses at the knee joint, perform virtual surgery, and record data from surgery simulation View full abstract»

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  • Diving deep: data-management and visualization strategies for adaptive mesh refinement simulations

    Page(s): 36 - 47
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    The authors' cosmological applications illustrate problems and solutions in storing, handling, visualizing, virtually navigating, and remote serving data produced by large scale adaptive mesh refinement simulations. The authors describe their cosmological AMR algorithm and how they applied it to star, galaxy, and galaxy cluster formation. Basically, the algorithm allows them to place very high resolution grids precisely where they are needed-where stars and galaxies condense out of diffuse gas. In these applications, AMR allows the authors to achieve a local mesh refinement, relative to the global coarse grid, of more than a factor of 106. Such resolution would be totally impossible to achieve with a global, uniform fine grid. Thus, AMR allows them to simulate multiscale phenomena that are out of reach with fixed grid methods View full abstract»

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  • Pay me now or pay me later [computer programming techniques]

    Page(s): 59 - 62
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    A colleague of the authors recently asked for a way to sample from a Poisson distribution to simulate the way metallic flakes cluster in paint. The flakes aren't distributed uniformly at random throughout the paint binder but form clusters around center points. The number of flakes around a center is distributed like the Poisson distribution. The article presents three ways to sample from the Poisson distribution. We describe the usual method, a faster method that uses some preprocessing, and an even faster method with more preprocessing. The last two methods work with any discrete probability distribution. Depending on how often we need to generate samples, paying extra for a deluxe model of sample generation might be worth it View full abstract»

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  • Visualizing text data sets

    Page(s): 26 - 35
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    The authors present a visualization methodology which provides users with a way to alter perspectives and interpret visualization so that they can quickly identify trends, outliers, and possible clusters while tuning for a particular context. The technology developed for text mining is called Trust, or Text Representation Using Subspace Transformation. Trust provides an analysis environment that can supply meaningful representations of text documents; it also supports the functional ability to visually present a collection of documents in a meaningful context that allows for user insight and textual content. Contrary to other similar technologies, Trust applies a novel analysis ability that allows different subspaces to generate views, providing content information for the basis of the visualization and allowing an analyst to specify subspaces for it based on content View full abstract»

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Aims & Scope

Computing in Science & Engineering presents scientific and computational contributions in a clear and accessible format.

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Meet Our Editors

Editor-in-Chief
George K. Thiruvathukal
Loyola University