It is quite necessary that an organization’s information network should be equipped with a proper security system based on its scale and importance. One of the effective methods is to use the simulation model for dec...
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Orthogonal frequency division multiplexing (OFDM) transmitter diversity techniques have been shown to be efficient means of achieving near optimal diversity gain in frequency selective fading channels. For these syste...
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Orthogonal frequency division multiplexing (OFDM) transmitter diversity techniques have been shown to be efficient means of achieving near optimal diversity gain in frequency selective fading channels. For these systems, knowledge of the channel parameters is required at the receiver for diversity combining and decoding. We propose a pilot-symbol assisted channel estimator using DFT-based and linear interpolation for OFDM based systems with two antenna transmitter diversity. We then consider four transmit antenna systems and propose new channel estimation techniques, which allow estimation and separation of the channel state information of the different transmit antennas without changing the preamble structure of the system.
The present study describes a Virtual Environment (VE) designed to train individuals to perform the role of a military checkpoint guard. Participants stood guard at a fictitious base in which simulated drivers in vehi...
The present study describes a Virtual Environment (VE) designed to train individuals to perform the role of a military checkpoint guard. Participants stood guard at a fictitious base in which simulated drivers in vehicles would approach seeking entrance. Participants were asked to inspect each vehicle, interact with the drivers, verify their identification, and make a decision to allow the driver to enter the base, to detain the vehicle, or to ask the driver to turn around and leave. The experiment was conducted in a CAVE™ with stereoscopic visual and auditory displays, participant tracking, and voice recognition. The results showed that participants were able to learn quite effectively in the VE with the biggest performance improvements seen in the areas of proper protocol and social influence. These findings suggest that VE technology holds promise for activities that are more like experience-based training and which place a greater emphasis on social interaction skills.
We investigate and compare a few parallel preconditioning techniques in the iterative solution of large sparse linear systems arising from solid Earth simulation with and without using contact information in the domai...
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The last decade has introduced various affordable computing platforms to the parallel computing community. Distributed shared-memory systems and clusters built with commercial-off-the-shelf (COTS) parts and interconne...
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The last decade has introduced various affordable computing platforms to the parallel computing community. Distributed shared-memory systems and clusters built with commercial-off-the-shelf (COTS) parts and interconnected with high-performance networks have proven to be serious alternatives to expensive supercomputers in terms of both performance and cost. HP's new AlphaServer ES80 is an example of distributed shared-memory systems, while SCI and Myrinet are the two most widely used high-performance interconnects in building parallel-computing clusters. In this study, we experimentally compare the performance of these parallel computer systems. The emphasis is pointing out the strengths and weakness of the HPs AlphaServer ES80 in comparison with high-performance SCI and Myrinet clusters. We evaluated the systems in terms of sustainable memory bandwidth, interprocess communication and overall parallel computation performance using various widely-accepted benchmarks such as STREAM, PALLAS PMB-MP1, and NAS2.3 parallel suite. It was observed that the HPs AlphaServer ES80, executing Linux, provides remarkable computing power while its communication subsystem cannot handle heavy loads of small messages as effectively.
This paper compares and evaluates the multicast performance of two of the most widely deployed system-area networks (SANs), Dolphin's scalable coherent interface (SCI) and Myricom's Myrinet. Both networks deli...
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This paper compares and evaluates the multicast performance of two of the most widely deployed system-area networks (SANs), Dolphin's scalable coherent interface (SCI) and Myricom's Myrinet. Both networks deliver low latency and high bandwidth to applications, but do not support multicast in hardware. We compared SCI and Myrinet in terms of their user-level performance using various software-based multicast algorithms under various networking and multicasting scenarios. The strengths and weaknesses of each network are comparatively presented in terms of numerous metrics, such as multicast completion latency, CPU utilization, link concentration and concurrency.
We discuss our recent work on simulational studies of impulse propagation and backscattering for the detection and imaging of shallow buried objects in close packed granular beds.
We discuss our recent work on simulational studies of impulse propagation and backscattering for the detection and imaging of shallow buried objects in close packed granular beds.
Scalability of a low-cost, Intel Xeon-based, multi-Teraflop Linux cluster is tested for two high-end scientific applications: Classical atomistic simulation based on the molecular dynamics method and quantum mechanica...
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It is well known that Ge(100) surface shows reconstructed structure like Si (100) surface. This surface formed structure which has asymmetric dimers in the topmost layer at low temperature, and the order-disorder phas...
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It is well known that Ge(100) surface shows reconstructed structure like Si (100) surface. This surface formed structure which has asymmetric dimers in the topmost layer at low temperature, and the order-disorder phase transition occurs at ∼200 K, the structure change to structure. For Ge(100) surface X-ray diffraction measurements and the structure analysis are performed by R. Rossmann, et al. However, they use the isotropic Debye-Waller factor. In actuality, Ge dimers makes flip-flop motion at particular direction. We try to perform the structure analysis of Ge (100) surface using the results of the first-principles calculation and the anisotropic Debye-Waller factor. Obtained results show improvement compared with previous analysis.
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