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Potentials, IEEE

Issue 4 • Date Oct/Nov 1996

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Displaying Results 1 - 8 of 8
  • SIMD processors-expanding its horizons by emulating others

    Page(s): 26 - 28
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1300 KB)  

    Parallel processing has established itself as the key enabling technology for the future of high performance computing. A parallel machine can be abstracted as a collection of processing elements (PEs) connected using some form of communication network. Parallel machines have been built along two major architectural formats: multiple-instruction streams multiple-data streams (MIMD) machines and single-instruction stream multiple-data streams (SIMD) machines. The hardware differences and general programming models for SIMD and MIMD processors have led many to believe each can solve only limited types of problems. SIMD machines, for instance, are often used in applications such as image processing. In that application, the same set of operations are performed on many different pieces of data. MIMD machines are commonly used when the control flow needs vary in correspondence with differences in data, such as parallel simulation View full abstract»

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  • The power of networking-pooling resources to keep our electricity on requires control

    Page(s): 38 - 42
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    One of life's mysteries is how electric power companies provide our homes and industries with electric service so reliably and, despite oft-heard complaints, so economically. This article will attempt to shed light on the basic principles on which electric power systems operate. The author discusses the electric power grid, power system organisation, frequency control, clock time, power interchange control, area control error, economic load dispatch, spinning reserve, load flow, system security, and voltage stability View full abstract»

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  • Cleanroom software engineering-plan your work and work your plan in small increments

    Page(s): 29 - 32
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    In the semiconductor industry, silicon chips are built in contaminant-free environments called cleanrooms. This helps prevent the injection of defects during the production process. Similarly, defect prevention is the primary concern of software-developers using cleanroom software engineering. The motivation is the same in both cases: defect prevention is much less expensive than defect removal. The traditional software development pattern relies heavily on testing and debugging after development to find and repair errors. With cleanroom, the goal is to construct software with no defects during development. Given high quality code, testers on a cleanroom project can focus on determining the reliability of the code. They can then improve it, if necessary, rather than spend time finding and fixing an indeterminate number of defects keeping fingers crossed that reliability will be satisfactory in production. These may sound like unattainable goals, however, numerous cleanroom teams have used cleanroom successfully. They have built a total of nearly two million lines of extremely high quality software during the past decade, while maintaining high productivity rates. Cleanroom software engineering is a managerial and technical process for developing ultra-high quality software with certified reliability. Cleanroom provides a complete disciplined structure within which software development teams can plan, specify, design, verify, code, test, and certify software View full abstract»

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  • Mobile computing-a promising future that still requires much work

    Page(s): 13 - 15
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    Mobile computing is a paradigm shift in computing and telecommunications caused by the people's lifestyles. This area is still in its infancy as there are many unresolved research issues. The research issues include design of system specifications and protocols for mobile system; a plethora of issues in providing transparent virtual networking of computers, database and information management issues, security and compression techniques and resource discovery and design of agents. A typical mobile computer system consists of the following components: a static communication backbone using wired means; a set of static hosts; sets of mobile hosts (MHs) that can communicate with a predetermined static host; and mobile subnets/wireless cells. The static communication backbone connects all the static hosts sometimes called mobile support stations (MSSs). As the name suggests, the static communication backbone and the static hosts are not mobile. Each MSS can communicate with a set of mobile hosts. The mobile hosts can move within a limited geographical area referred to as a wireless cell or a mobile subnet View full abstract»

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  • Simulating winds and floods-regional weather-river prediction and regional climate research

    Page(s): 17 - 19
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    The authors at the University of California Lawrence Livermore National Laboratory (UC-LLNL) developed a coupled modeling system. The system simulates regional-scale weather, land-surface processes, and river flow using large-scale atmospheric data and land surface terrain information as input. This Coupled Atmosphere River Flow Simulation (CARS) system consists of the mesoscale atmospheric simulation (MAS) model coupled with a soil-plant-snow (SPS) model, our Automated Land Analysis System (ALAS) and a physically-based fully distributed surface hydrology and river flow model, TOPMODEL. The MAS model is a primitive-equation, limited-area model. It includes a third order accurate advection scheme and physical processes for: (1) precipitation and thermal forcing due to deep convective clouds and stratiform clouds; (2) solar and terrestrial radiative transfer within the atmosphere, and (3) turbulent transfer at the Earth's surface and within the atmosphere. Interactions between the atmosphere and land-surface are computed using the SPS model. It is interactively coupled to the MAS. The SPS keeps track of hydrologic variables such as water stored in the snowpack that is crucial for assessing the available water resources. The ALAS provides topographic properties, such as river networks and watershed areas, at specified resolutions, using digital elevation model data View full abstract»

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  • Maglev vehicles-raising transportation advances of the ground

    Page(s): 7 - 12
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    Maglev as a practical concept was first proposed by the authors in 1966. The concept was based on using lightweight, very high current superconducting loops suitably positioned on a streamlined vehicle. As the vehicle moves along a guideway containing loops of ordinary aluminum wire at ambient temperature, the superconducting loops induce small electric currents in the guideway loops that are directly underneath them. The magnetic interaction of the permanent currents in the superconducting loops with the induced currents in the guideway loops automatically levitates the vehicle. The levitation is inherently stable about its normal equilibrium suspension point. If an external force (e.g. a wind gust, curve, or change in grade) acts on the vehicle, a magnetic force automatically and immediately develops to oppose the external force. The magnetic force pushes the vehicle back toward its normal equilibrium suspension point. Since Maglev vehicles do not contact the guideway, their speed is not constrained by mechanical stresses, friction, or wear. The speed is limited only by aerodynamic drag or straightness of route. The authors describe how the first generation of Maglev vehicles probably will travel in air; however, as tunneling technology develops and becomes cheaper, long distance, ultra-speed Maglev vehicles that travel in low pressure tunnels will emerge as the second generation. Passengers will then be able to travel between New York and Los Angeles, for example, in a little over an hour, with virtually no energy required View full abstract»

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  • Feature interaction-how it works in telecommunication software

    Page(s): 35 - 37
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    The results from feature interaction can be seen as a problem from different perspectives. The two primary perspectives are from the end user's view and the application developer's view. This article pursues solutions that originate from the applications designer's view. Even within this view, there are different ways to approach the feature interaction problem. These solutions, in turn, have the potential to introduce new problems. Each of these views lead to different solutions to our problem. The solution to the feature interaction has three parts. First, avoid undesirable interactions whenever possible. Second, detect interactions when they occur. Finally, resolve the interactions as quickly as possible. Preferably, this final step should be automated. Feature interactions will occur in real-time, and must be handled on-the-fly for our communication networks to perform as expected by the end user View full abstract»

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  • Detecting stress and fatigue cracks

    Page(s): 20 - 24
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    Discoveries in using open ended rectangular waveguides for microwave surface crack detection and sizing have generated interest. The foundation, potential, advantages and disadvantages of this methodology, developed at the Applied Microwave Nondestructive Testing Laboratory in the Electrical Engineering Department at Colorado State University, are discussed. Microwave techniques in general and this particular approach offer certain unique advantages that can advance the state of the art of fatigue/surface crack detection. The basic features and capabilities of this technique have been theoretically and experimentally investigated these past few years. However, more developmental work is needed to bring this technique from the laboratory to the real testing environment. The microwave method described has proven to be very effective in detecting and characterizing surface cracks in metals. It is inexpensive and can readily be applied in various environments. This approach applies to exposed, empty, filled and covered cracks. Cracks may also be detected remotely (i.e. the use on a liftoff in between the waveguide aperture and the surface under examination) View full abstract»

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IEEE Potentials is the magazine dedicated to undergraduate and graduate students and young professionals.

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Editor-in-Chief
David Tian
Carnegie Mellon University
david.tian@ieee.org