The Kerr electro-optic field mapping technique has been used to study space charge effects in high voltage pulsed propylene carbonate (C/sub 4/H/sub 6/O/sub 3/) using aluminum blade-plane and point-plane electrode geo...
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The Kerr electro-optic field mapping technique has been used to study space charge effects in high voltage pulsed propylene carbonate (C/sub 4/H/sub 6/O/sub 3/) using aluminum blade-plane and point-plane electrode geometries. Measurements presented here were taken using a circular polariscope with aligned polarizers at slightly elevated room temperature (T/spl sim/27/spl deg/C) with calculated space charge free peak electric field strengths of /spl sim/210 kV/cm at the blade electrode tip and /spl sim/240 kV/cm at the point electrode tip and for times ranging from 10 /spl mu/s to 400 /spl mu/s. The light intensity was recorded on Polaroid film for the blade- and point-plane electrodes and also with a CCD camera for the point-plane electrodes. A CCD camera was used for the point-plane electrodes to more accurately resolve the gray-scale light intensity distribution because of the short optical path length. These high voltage Kerr electro-optic measurements show significant space charge effects in propylene carbonate as the light intensity maxima and minima significantly differ from the calculated patterns from numerical solutions to Laplace's equation under space-charge free conditions.
We present the tracking properties of the Normalized LMS and affine projection class of algorithms for a randomly time-varying system under certain simplifying assumptions on the data. An expression is given for the s...
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We present the tracking properties of the Normalized LMS and affine projection class of algorithms for a randomly time-varying system under certain simplifying assumptions on the data. An expression is given for the steady-state mean-squared error. The dependence of the steady-state error and of the tracking properties on three user-selectable parameters, namely step size, number of vectors used for adaptation, and delay used to choose input vectors used for adaptation, is discussed. While the lag error depends on all of the above parameters, the fluctuation error depends only on step size. Increasing delay results in a linear increase in the lag error and hence the total steady-state mean-squared error. There is an optimum choice for stepsize and number of input vectors that minimizes the total mean-squared error. Simulation results are provided to corroborate the theoretical conclusions.
Massive Multi-player Online Games (MMOGs) are rapidly gaining in popularity, as the access to high bandwidth connectivity becomes a commodity in the consumer market. With player subscriptions for popular games reachin...
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ISBN:
(纸本)0769518575
Massive Multi-player Online Games (MMOGs) are rapidly gaining in popularity, as the access to high bandwidth connectivity becomes a commodity in the consumer market. With player subscriptions for popular games reaching seven digit numbers and concurrent player participation in the hundreds of thousands, new high-performance adaptive frameworks, which aid system programmers, are required. Primary research challenges that have to be addressed are compensating network latency and jitter, keeping system-wide data consistent, enabling fair resource sharing and interaction between game players, and expanding the scale of the system as the number of players increases. A global timestamp based approach is presented and describes issues and implementation approaches based on a high-level object-oriented real-time programming methodology called the time-triggered message-triggered object (TMO) programming scheme.
In this paper, we address the impact of resource limitations on the operation and performance of the broadcasting and multicasting schemes developed for infrastructureless wireless networks in our earlier studies. The...
In this paper, we address the impact of resource limitations on the operation and performance of the broadcasting and multicasting schemes developed for infrastructureless wireless networks in our earlier studies. These schemes, which provide energy-efficient operation for source-initiated session traffic, were previously studied without fully accounting for such limitations. We discuss the “node-based” nature of the all-wireless medium, and demonstrate that improved performance can be obtained when such properties are exploited by networking algorithms. Our broadcast and multicast algorithms involve the joint choice of transmitter power and tree construction, and thus depart from the conventional approach that makes design choices at each layer separately. We indicate how the impact of limited frequency resources can be addressed. Alternative schemes are developed for frequency assignment, and their performance is compared under different levels of traffic load, while also incorporating the impact of limited transceiver resources. The performance results include the comparison of our algorithms to alternative “link-based” algorithms for broadcasting and multicasting.
Multiple description coding (MDC) schemes have become popular as robustness tools in packet switched networks where multiple paths with varying packet loss rates are available. The descriptions are designed so that th...
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Multiple description coding (MDC) schemes have become popular as robustness tools in packet switched networks where multiple paths with varying packet loss rates are available. The descriptions are designed so that the quality of the reconstructed image depends on the number of descriptions received and not on which descriptions are actually received. We propose a new MDC framework for the EBCOT algorithm used in the current JPEG 2000 standard for still image compression. The inherent block coding in EBCOT allows for more flexibility in the formation of basic groups that are then combined in different ways to form descriptions. The bit allocation problem (between the different groups in a description) is formulated and optimized for good rate-distortion performance. Optimization of the bit allocation between the primary and secondary positions in each description is obtained using the generalized BFOS algorithm. Experiments using the Kakadu software (for JPEG 2000) show that the performance of the proposed framework degrades gracefully with increase in the number of descriptions lost.
The human immune system can be seen as a complex network structure that is able to respond to an almost unlimited multitude of foreign invaders such as viruses and bacteria. Hence, this parallel and distributed adapti...
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The human immune system can be seen as a complex network structure that is able to respond to an almost unlimited multitude of foreign invaders such as viruses and bacteria. Hence, this parallel and distributed adaptive system promises tremendous potential in many intelligent computing applications, including Web mining. Some of these immunity-based techniques involve the development and analysis of algorithms that can identify patterns in observed data in order to make predictions about unseen data. In this paper, we introduce several new enhancements to deal with some of the weaknesses of previous artificial immune system models. In particular, we address the uncertainty and fuzziness inherent in the matching process that takes place between antibodies and antigens. This problem is handled by introducing a fuzzy artificial immune system. A fuzzy artificial immune system mimicking the body's adaptive learning and defense mechanism in the face of invading biological agents is used as a monitoring and learning system for a Web site in the face of all incoming Web requests.
作者：
S. SomasundaramR. ChandramouliMultimedia Systems
Networking and Communications (MSyNC) Laboratory Department of Electrical and Computer Engineering Stevens Institute of Technology Hoboken NJ USA
Presents a common ground between information theoretic and perceptually based approaches to watermarking. A perceptually based iterative waterfilling algorithm that achieves information theoretic watermarking capacity...
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Presents a common ground between information theoretic and perceptually based approaches to watermarking. A perceptually based iterative waterfilling algorithm that achieves information theoretic watermarking capacity within perceptual distortion constraints is proposed. Image watermarking is considered for experimental analysis. Experimental results are presented to explain how the proposed algorithm achieves a trade-off between information theoretic capacity, robustness and perceptual distortion. Some general observations about the visual quality of an image and its information theoretic capacity are also made.
We present a proactive resource allocation algorithm, called BEA, for fault-tolerant asynchronous real-time distributed systems. BEA considers an application model where transnode application timeliness requirements a...
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We present a proactive resource allocation algorithm, called BEA, for fault-tolerant asynchronous real-time distributed systems. BEA considers an application model where transnode application timeliness requirements are expressed using benefit functions, and anticipated workload during future time intervals are expressed using adaptation functions. Furthermore, BEA considers an adaptation model where subtasks of application tasks are replicated at run-time for tolerating failures as well as for sharing workload increases. Given such models, the objective of the algorithm is to maximize the aggregate real-time benefit and the ability to tolerate host failures during the time window of adaptation functions. Since determining the optimal solution is computationally intractable, BEA heuristically computes near-optimal resource allocations in polynomial-time. We show that BEA can achieve almost the same fault-tolerance ability as full replication, and accrue most of real-time benefit that full replication can accrue. In the meanwhile, BEA requires much fewer replicas than full replication, and hence is cost effective.
Presents the design and preliminary evaluation of hierarchical partitioning and load-balancing techniques for distributed structured adaptive mesh refinement (SAMR) applications. The overall goal of these techniques i...
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Presents the design and preliminary evaluation of hierarchical partitioning and load-balancing techniques for distributed structured adaptive mesh refinement (SAMR) applications. The overall goal of these techniques is to enable the load distribution to reflect the state of the adaptive grid hierarchy and exploit it to reduce synchronization requirements, improve load-balance, and enable concurrent communications and incremental redistribution. The hierarchical partitioning algorithm (HPA) partitions the computational domain into subdomains and assigns them to hierarchical processor groups. Two variants of HPA are presented. The static hierarchical partitioning algorithm (SHRA) assigns portions of overall load to processor groups. In SHRA, the group size and the number of processors in each group is setup during initialization and remains unchanged during application execution. It is experimentally shown that SHRA reduces communication costs as compared to the Non-HPA scheme, and reduces overall application execution time by up to 41%. The adaptive hierarchical partitioning algorithm (AHRA) dynamically partitions the processor pool into hierarchical groups that match the structure of the adaptive grid hierarchy.
Summary form only given. Permanent magnet machines are being considered for use in electric ships as pumps and drives. The exterior fields of these machines are of concern. These fields decay at a rate that depends on...
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Summary form only given. Permanent magnet machines are being considered for use in electric ships as pumps and drives. The exterior fields of these machines are of concern. These fields decay at a rate that depends on the number of poles, fields from higher number of poles decaying more rapidly. If there is an imbalance in the set of poles, the lower order decay of the unbalanced poles dominate in the far field and the advantage of using a high number of poles could be lost.
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