Ravi Palaniappan

FDTD speedups obtained in distributed computing on a Linux workstation cluster

The project investigated various aspects of parallel FDTD implementation on a workstation cluster. The computation grid was divided among nodes. For a fixed size problem, as the number of processor increases, the speedup saturates. This happens because each processor spends less time computing but essentially the same time communicating with its neighbors. To take advantage of the parallel algorithm, the problem size must be sufficiently large compared with the number of processors. For very large problems, we can efficiently employ a large number of processors to obtain a linear speedup. In this work, the message passing interface (MPI) parallel implementation was integrated with POSIX threads using the pthreads library. This was required because each node in the cluster was equipped with two processors. On each node, each process contained two threads that executed in parallel. As expected, for sufficiently large problems the speedup was increased by almost a factor of two when using threads.

Target detection and tracking using a UWB sensor web

This paper describes the experimental and simulation studies that were conducted to locate and track a target inside a UWB sensor web system. The sensor web was designed using second generation UWB prototype devices and the simulation software was developed using MATLAB and C language. Return scans from the UWB devices were analyzed to determine the noise floor and the signal strength. Using the noise floor level, a threshold level is set above which the alarm is triggered to indicate the presence of a target. The probability of false alarm (PFA) is also determined using the signal-to-noise ratio and the threshold. The PFA was varied to minimize the false alarm level. The noise statistics of the sensor web system was also analyzed using the Kolmogorov-Smirnov (KS) test.

Outdoor propagation analysis of ultra wide band signals

An ultra wide band (UWB) signal is defined as any radiation in which the 3-dB bandwidth is greater than 25% of the center frequency. UWB signals are characterized by extreme low powers and large bandwidths, which can be used for data, voice and video communication. Since UWB waveforms have very short time duration, they possess unique properties. For example in radar applications, these same pulses can provide very fine range resolution and precision distance and/or positioning measurement capabilities. These short duration waveforms are relatively immune to multi-path cancellation effects. In this paper we test the performance of a simulation to model the propagation of an UWB signal in outdoor forested environment. The simulation uses a combination of finite difference time domain and ray tracing methods to simulate UWB wave propagation. The model takes into consideration the dielectric constants of the materials of the trees and measures the signal strength for vertical and horizontal polarizations of the UWB antennas placed at various heights and distances from each other. The results of the simulation are compared to measurements obtained from tests conducted at a wooded area in Seneca Creek State Park, Gaithersburg, Maryland. It was observed that up to 150 ft distance between the transmitter and receiver, the horizontally polarized antenna system gave better signal-to-noise ratio, but at greater distances the vertically polarized antenna system gave a better signal-to-noise ratio performance. Three dimensional plots of the signal strengths and the signal-to-noise ratio for various transmitter and receiver distances are plotted for the system. These are compared with experimental results and it was observed that the simulation closely matched the experimental data. The results of the simulation and measurements will be used for further developing a UWB location and tracking system in outdoor environments.

Study of ultra-wide band signal propagation in urban environments

INTRODUCTION Ultra-wide bandwidth (UWB) spread spectrum techniques have recently attracted great scientific as well as commercial interest [l]. Recent results indicate UWB radios are a viable candidate for the short-range communication in dense multkpath environments. Performance predictions of such communication systems require appropriate channel modeling and simulation techniques. In this paper ultra-wide band signal propagation in an urban environment is measured and studied. Data collected from an UWB propagation experiment performed inside an office building is compared to computer simulations done using ray tracing and the finite difference time domain (FDTD) methods.

A self-organizing hybrid sensor system with distributed data fusion for intruder tracking and surveillance

A wireless sensor network is a network of distributed sensor nodes each equipped with its own sensors, computational resources and transceivers. These sensors are designed to be able to sense specific phenomenon over a large geographic area and communicate this information to the user. In this work a novel approach to tracking dynamic targets in a sensor field is presented. Using a combination of static and mobile sensor nodes we can track a target through the sensor field. Unlike other tracking methods that are based on computationally complex methods, the strategy adopted in this work is based on a computationally simple but effective technique of dividing the coverage region into grids based on the target location. The algorithms developed are based on a number of reasonable assumptions that are easily verified in a densely distributed sensor networks and require simple computations that efficiently tracks the target in the sensor field. The performance analysis of the tracking system is done on an experimental test-bed and also through simulation and the improvement in accuracy over other methods demonstrated.

A Novel Sensor Web System for Tracking and Surveillance

Current sensor network technology for detection and tracking are focused solely in terms of static networks and suffers from device specific inadequacies such as lack of coverage, power and fault tolerance. Failing nodes result in coverage loss or breakage in connectivity and hence there is a pressing need for a robust system. In this work a unique sensor network is fielded that uses multiple frequencies and transmit powers to improve coverage. A novel approach to track a sensor node is also presented. Simulation data is compared to experimental results for validation.

High Performance Computing Benchmark Tool for Parallel Processing of Large Models

Benchmarks for parallel processing of large models is an urgent need for High Performance Computing (HPC) as today’s model size reaches millions of degrees of freedom. Explicit solvers as in the case of crash dynamics or fluid dynamics do not require matrix based equation solvers and inherently exhibit good scalability on lar ge numbers of processors. Where as analysis requiring implicit solvers in thermally driven structural response utilize large matrix equation solvers. The thermal radiation exchange problem matrices also may be dense and unsymmetric. Publicly available benchmarks such as Standard Performance Evaluation Corporation (SPEC) benchmarks do not address performance in areas of large matrix equation solvers for large number of nodes or for dense and unsymmetric matrix solvers. This study attempts to develop a benchmark tool that can be applied to dense and unsymmetrical matrix solvers for avionics heat transfer problems, thermally driven structural response problems and radiation exchange problems. In particular it addresses implicit solution algorithms with production models and benchmarks for indefinite matrices and configurations scaling for large dense matrix problems in distributed high performance system in shared, distributed and mixed memory conditions.

Responding to a bioterrorism attack-one scenario: part 2.

This article continues the discussions introduced in the earlier article submitted to The Health Care Manager that is titled Epidemic Simulation for Syndromic Surveillance, where a format for analysis of the incidence of a bioterrorist attack was presented. Part 2 of this series provides a discussion of the observed outcomes from the simulation techniques. This simulation was conducted as part of a federal grant award administered through the Center for Biological Defense at the University of South Florida. The disease entity simulated was an attack of anthrax introduced into the Central Florida region. The spread, effects, and eventual control of the disease entity are highlighted.

Outdoor propagation analysis of ultrawideband signals

An ultra wide band (UWB) signal is defined as any radiation in which the 3-dB bandwidth is greater than 25% of the center frequency. UWB signals are characterized by extreme low powers and large bandwidths, which can be used for data, voice and video communication. Since UWB waveforms have very short time duration, they are relatively immune to multi-path cancellation effects. In this paper we test the performance of a simulation to model the propagation of an UWB signal in outdoor forested environment. The simulation uses a combination of Finite Difference Time Domain and ray tracing methods to simulate the UWB wave propagation. The model takes into consideration the dielectric constants of the materials of the trees and measures the signal strength for vertical and horizontal polarizations of the UWB antennas placed at various heights and distances from each other. The results of the simulation are compared to measurements obtained from tests conducted at a wooded area in Seneca Creek State Park, Gaithersburg, Maryland. It was observed that upto 150 ft distance between the transmitter and receiver, the horizontally polarized antenna system gave better signal-to-noise ratio, but at greater distances the vertically polarized antenna system gave a better signal-to-noise ration performance. Three dimensional plots of the signal strengths and the signal-to-noise ratio for various transmitter and receiver distances are plotted for the system. These are compared with experimental results and the simulation closely matched the experimental data. The results of the simulation and measurements will be used for further developing an UWB location and tracking system for outdoor environments.