Performance evaluation of Fast Ethernet, ATM and Myrinet under PVM

Congestion in network switches can limit the communication traffic between Parallel Virtual Machine (PVM) nodes in a parallel computation. The research introduces a new benchmark to evaluate the performance of PVM in various networking environments. The benchmark is used to achieve a better understanding of performance limitations in parallel computing that are imposed by the choice of the network. The networks considered here are Fast Ethernet, Asynchronous Transfer Mode (ATM) OC-3c (155Mb/s) and Myrinet. Together, they represent an interesting range of alternatives for parallel cluster computing. A characterization of network delays and throughput and a comparison of the expected costs of the three environments are developed to provide a basis for an informed decision on the networking methods and topology for a parallel database that is being considered for FBI\u27s National DNA Indexing System (NDIS)[17]. This network is used for communications among the nodes of the parallel machine; thus the security requirements defined for the FBI\u27s Criminal Justice Information Services Division Wide Area Network (CJIS-WAN) [12] are not a concern

Large-Scale Multi-Agent Simulations for Transportation Applications

In many transportation simulation applications including intelligent transportation systems (ITS), behavioral responses of individual travelers are important. This implies that simulating individual travelers directly may be useful. Such a microscopic simulation, consisting of many intelligent particles (= agents), is an example of a multi-agent simulation. For ITS applications, it would be useful to simulate large metropolitan areas, with ten million travelers or more. Indeed, when using parallel computing and efficient implementations, multi-agent simulations of transportation systems of that size are feasible, with computational speeds of up to 300 times faster than real time. It is also possible to efficiently implement the simulation of day-to-day agent-based learning, and it is possible to make this implementation modular and essentially “plug-and-play.” Unfortunately, these techniques are not immediately applicable for within-day replanning, which would be paramount for ITS. Alternative techniques, which allow within-day replanning also for large scenarios, are discussed

An efficient parallelization of a real scientific application

Bibliography: leaves 137-145.In the past decade the cost of computing has come down considerably making high-powered computing more easily affordable. As a result many institutions and organisations now have networks of high-powered workstations. Such networks provide a large, generally untapped, source of computing power which can be used for running large scientific applications which previously could only be run on supercomputers. This dissertation shows that a substantial improvement in performance can be achieved by the parallelization of a real scientific application for a heterogeneous network of Sun and Silicon Graphics workstations connected by an Ethernet network, but that this is affected by a number of factors. These factors include communication delays, load balancing, and the number of slaves used. This dissertation shows that performance can be improved by sending more, shorter messages, and by overlapping communication with computation. Part of this thesis concerns the difficulties involved in the evaluation of parallel performance on a heterogeneous network. This dissertation shows that conventional methods such as speedup and efficiency are not appropriate for evaluating the performance of a heterogeneous system, and that linear speed gives a much more representative indication of the actual performance achieved. We also proposed new concepts of perfect linear speed and linear efficiency, which help to evaluate the improvement in parallel performance on a heterogeneous system

Interface for the integration of DynaMIT with the Traffic Management Center

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001.Includes bibliographical references (p. 117-121).by Manish Mehta.S.M

Analysis of volatile aroma-active compounds from a headspace of a novel whiskey glass

In the literature part of this thesis the human olfactory sense is explored. Also, individual differences in the sense of smell are studied. Since the study focuses on whiskey the anesthetic effects of ethanol on the olfactory system are explored. The different drinking vessels commonly used with whiskey are introduced and reviewed. A novel whiskey glass was studied for its aroma enhancing effects. The glass was designed to lessen the effect of ethanol anesthesia while nosing a whiskey from the glass. A method for headspace solid-phase microextraction (HS-SPME) was developed which adsorbed volatile compounds from the whiskey glass. The HS-SPME method developed was used to analyze whiskey volatile aroma-active compounds. The compounds were identified and quantitated using gas chromatography-flame-ionization detector (GC-FID). For comparison a whiskey sample is quantitated by direct injection and analyzed using gas chromatography-mass spectrometry (GC-MS). Ethanol evaporation experiments were conducted to verify the working principle of the novel whiskey glass. Gas chromatography-olfactometry (GC-O) was used to recognize that the aroma-active compounds of whiskey extracted from the novel glass can be perceived. The HS-SPME method from the whiskey glass was developed to simulate the natural whiskey nosing conditions to ensure relevant results. Several matters regarding the HS-SPME method were considered. These included duration, timing, closed or open headspace and temperature. With the developed method whiskey odorants known to be in the whiskey sample could be identified. Quantitation of these odorants was more challenging and subsequent analyses showed variation in quantities. GC-O also did not perfectly correlate with quantitation’s indicating that some odor-active compounds were under the detection limit

The effect of time delays on the stability of load balancing algorithms for parallel computations

A deterministic dynamic nonlinear time-delay system is developed to model load balancing in a cluster of computer nodes used for parallel computations. The model is shown to be self consistent in that the queue lengths cannot go negative and the total number of tasks in all the queues and the network are conserved (i.e., load balancing can neither create nor lose tasks). Further, it is shown that using the proposed load balancing algorithms, the system is stable in the sense of Lyapunov. Experimental results are presented and compared with the predicted results from the analytical model. In particular, simulations of the models are compared with an experimental implementation of the load balancing algorithm on a distributed computing network