Seismic signal processing is computationally intensive and sequential algorithms in use do not exploit the concurrency inherent in data migration techniques. In this paper we study seismic migration algorithms with an...
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Seismic signal processing is computationally intensive and sequential algorithms in use do not exploit the concurrency inherent in data migration techniques. In this paper we study seismic migration algorithms with an objective to present a general framework for analyzing such algorithms and propose some medium-grained paradigms for computation on parallel computers. We introduce parallel models for computation and discuss techniques to optimize their performance on distributed concurrently executing processors. The computational and communication requirements of the algorithms are discussed and diverse optimization techniques are proposed. The memory limitation, I/O bottleneck, and computational tradeoffs on hypercube multiprocessors are analyzed.
Channel assignment is among the most challenging issues for multiradio wireless mesh networks, given the variety of objectives that can be pursued and the computational complexity of the resulting problems. The channe...
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Channel assignment is among the most challenging issues for multiradio wireless mesh networks, given the variety of objectives that can be pursued and the computational complexity of the resulting problems. The channel assignment problem has been also shown to be interdependent with the routing problem, i.e., the problem to determine the amount of traffic flow to be routed on every link. Such a relationship raises the need to recompute the channel assignment every time the traffic pattern changes. However, channel assignment algorithms designed to assign channels from scratch will likely return a completely different configuration of radios, which would disrupt the network operation for the time required to switch to using the links established on the new channels. As shown by the experiments that we conducted, such a time may not be negligible, due to the resistance of routing protocols designed for wireless ad hoc and mesh networks to rapidly flagging a link as established/lost. Such a consideration, along with the observation that channel assignment algorithms may be suboptimal, led us to the design of a channel reassignment algorithm that takes the current channel assignment into account and attempts to cope with the new traffic pattern in the best manner possible while modifying the channel on a limited number of radios. In this paper, we illustrate such a channel reassignment algorithm and evaluate its performance by means of both simulations and experiments with real hardware.
This paper presents an algorithm for minimizing an objective function subject to conventional inequality constraints as well as to inequality constraints of the functional type: \max_{\omega \in \Omega} \phi(z,\omega)...
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This paper presents an algorithm for minimizing an objective function subject to conventional inequality constraints as well as to inequality constraints of the functional type: \max_{\omega \in \Omega} \phi(z,\omega) \leq 0 , where Ω is a closed interval in R , and z \in R^{n} is the parameter vector to be optimized. The algorithm is motivated by a standard earthquake engineering problem and the problem of designing linear multivariable systems. The stability condition (Nyquist criterion) and disturbance suppression condition for such systems are easily expressed as a functional inequality constraint.
This paper analyzes the performance of two different types of service control point (SCP) overload control algorithms, table-driven controls and an adaptive control. As performance measures, we use aggregate transacti...
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This paper analyzes the performance of two different types of service control point (SCP) overload control algorithms, table-driven controls and an adaptive control. As performance measures, we use aggregate transaction throughput and fairness (whether the control algorithm allocates SCP capacity to individual traffic sources as desired), We find that, even when parameters are well-matched to source characteristics, table-driven controls do not perform as well as the adaptive control. In addition, the adaptive control is more robust to traffic patterns and SCP internal operation than the table-driven controls.
New design flows require reducing work at the gate level and perfoming most activities before the synthesis step, including evaluatation of testability of circuits. We propose a suite of RT-level benchmarks that help ...
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New design flows require reducing work at the gate level and perfoming most activities before the synthesis step, including evaluatation of testability of circuits. We propose a suite of RT-level benchmarks that help improve research in high-level ATPG tools. First results on the benchmarks obtained with our prototype tool show the feasibility of the approach.
To address difficulties with contact analysis in mechanical design-namely in planar mechanical systems with complex part shapes, tight fits, and contact changes-the authors have developed a general contact-analysis me...
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To address difficulties with contact analysis in mechanical design-namely in planar mechanical systems with complex part shapes, tight fits, and contact changes-the authors have developed a general contact-analysis method based on configuration space computation.
A general procedure for the transformation of networks containing mutual inductive couplings into equivalent circuit systems with no mutual couplings for which the ordinary resolution methods apply is illustrated. The...
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A general procedure for the transformation of networks containing mutual inductive couplings into equivalent circuit systems with no mutual couplings for which the ordinary resolution methods apply is illustrated. The proposals are made a) to provide a procedure for the prompt resolution of any problems-no matter how complex-concerning networks which include inductive couplings, b) to render the treatise accessible to a large number of readers; thus, in the analytical developments, only simple algorithms are used, c) to provide the means to apply the results of the procedure without difficulty and without the need for knowledge of the demonstration, and d) to draw the specialists' attention to subjects that offer grounds for further studies and research.
Beginning with the announcement of General Instrument Corp.'s DigiCipher all-digital system, US engineers have propelled high-definition television (HDTV) into the digital era. Federal Communications Commission (...
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Beginning with the announcement of General Instrument Corp.'s DigiCipher all-digital system, US engineers have propelled high-definition television (HDTV) into the digital era. Federal Communications Commission (FCC) chairman Al Sikes is encouraging new technological developments in the terrestrial broadcast arena. Digital HDTV offers certain advantages over analog and hybrid systems, including pictures that are free of atmospheric noise and other interference. However, HDTV also presents some problems, including a tendency to degrade abruptly. Such challenges notwithstanding, all the system proponents plan to have their digital systems ready for testing in accordance with an FCC schedule. The proposed systems share many features, such as the use of so-called taboo VHF or UHF channels. HDTV signals require much wider bandwidths than do conventional broadcast signals, prompting development of a variety of techniques to compress them.
Bernoulli and first-order Markov processes are used to approximate the output process of a class of slotted multiuser random-access communication networks. The output process is defined as the process of the successfu...
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Bernoulli and first-order Markov processes are used to approximate the output process of a class of slotted multiuser random-access communication networks. The output process is defined as the process of the successfully transmitted packets within the network. The parameters of the approximating processes are analytically calculated for a network operating under a specific random access algorithm. The applied methods are general and can be used to calculate these parameters in the case of any random access algorithm within a class. To evaluate the accuracy of the approximations, a star topology of interconnected multiuser random-access communication networks is considered. The mean time that a packet spends in the central node of the star topology is calculated under the proposed approximations of the output processes of the interconnected networks. The results are compared to simulation results of the actual system. It turns out that the memoryless approximation gives satisfactory results up to a certain per network traffic load. Beyond that per network traffic load, the first-order Markov process performs better.< >
The multidelay parallel (MDP) technique is a multidelay logic simulation algorithm that uses no timing wheel, or any other event-sorting mechanism, Instead, wide bit-fields containing net-values for several different ...
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The multidelay parallel (MDP) technique is a multidelay logic simulation algorithm that uses no timing wheel, or any other event-sorting mechanism, Instead, wide bit-fields containing net-values for several different times are used to resolve out-of-order events, Bit-parallel operations are performed to simulate;gates at the required times, The MDP technique was originally designed to be implemented in hardware, but the current software version of the algorithm has proven to be competitive with conventional event-driven multidelay simulation, Two versions of the MDP technique are presented in this paper, fixed alignment and variable alignment, The fixed alignment algorithm provides bit-fields that are wide enough to capture any event that could occur during the simulation of an input vector, while the variable alignment algorithm uses a minimum-width bit field which is just wide enough to capture those events that could occur at an individual step in the simulation, A prototype hardware design is discussed briefly.
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