This letter introduces a parallel and distributed computation method for dynamical economic dispatch over a cyber-physical system. To achieve a faster economic dispatch operation, accelerated consensus approach is pro...
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This letter introduces a parallel and distributed computation method for dynamical economic dispatch over a cyber-physical system. To achieve a faster economic dispatch operation, accelerated consensus approach is proposed. The simulation illustrates the better performance of accelerated consensus algorithm.
In this paper we describe methods for mitigating the degradation in performance caused by high latencies in parallel and distributed networks. For example, given any "dataflow" type of algorithm that runs in...
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In this paper we describe methods for mitigating the degradation in performance caused by high latencies in parallel and distributed networks. For example, given any "dataflow" type of algorithm that runs in T steps on an n-node ring with unit link delays, we show how to run the algorithm in O(T) steps on any n-node bounded-degree connected network with average link delay O(1). This is a significant improvement over prior approaches to latency hiding, which require slowdowns proportional to the maximum link delay. In the case when the network has average link delay d(ave), our simulation runs in O(root d(ave)T) steps using n/root d(ave) processors, thereby preserving efficiency. We also show how to efficiently simulate an n x n array with unit link delays using slowdown (O) over tilde(d(ave)(2/3)) on a two-dimensional array with average link delay d(ave). Last, we present results for the case in which large local databases are involved in the computation.
This paper, the second one in a three-paper sequence, presents the nesC model of a Hopfield neural network configured for a static optimization problem, the maximum independent set, in fully parallel and distributed m...
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This paper, the second one in a three-paper sequence, presents the nesC model of a Hopfield neural network configured for a static optimization problem, the maximum independent set, in fully parallel and distributed mode for TinyOS-based wireless sensor networks. Actual nesC code that implements the required neural computing functionality is presented. The graph representation of the maximum independent set problem is used as the basis for the topology of the Hopfield network as well as the wireless sensor network since each mote is conceived to house one neuron in order to facilitate fully parallel and distributed computation. The nesC implementation of a multitude of phases of computation is detailed including initialization of the neural network, relaxation, convergence detection, and solution detection all while the neural computations are performed on the wireless sensor network. Simulation of the presented nesC-TinyOS model is deferred to the third paper in the sequence. (C) 2011 Published by Elsevier B.V.
This paper, the second one in a three-paper sequence, presents the nesC model of a Hopfield neural network configured for a static optimization problem, the maximum independent set, in fully parallel and distributed m...
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This paper, the second one in a three-paper sequence, presents the nesC model of a Hopfield neural network configured for a static optimization problem, the maximum independent set, in fully parallel and distributed mode for TinyOS-based wireless sensor networks. Actual nesC code that implements the required neural computing functionality is presented. The graph representation of the maximum independent set problem is used as the basis for the topology of the Hopfield network as well as the wireless sensor network since each mote is conceived to house one neuron in order to facilitate fully parallel and distributed computation. The nesC implementation of a multitude of phases of computation is detailed including initialization of the neural network, relaxation, convergence detection, and solution detection all while the neural computations are performed on the wireless sensor network. Simulation of the presented nesC-TinyOS model is deferred to the third paper in the sequence.
We propose a new and low per-iteration complexity first-order primal-dual optimization framework for a convex optimization template with broad applications. Our analysis relies on a novel combination of three classic ...
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We propose a new and low per-iteration complexity first-order primal-dual optimization framework for a convex optimization template with broad applications. Our analysis relies on a novel combination of three classic ideas applied to the primal-dual gap function: smoothing, acceleration, and homotopy. The algorithms due to the new approach achieve the best-known convergence rate results, in particular when the template consists of only nonsmooth functions. We also outline a restart strategy for the acceleration to significantly enhance the practical performance. We demonstrate relations with the augmented Lagrangian method and show how to exploit the strongly convex objectives with rigorous convergence rate guarantees. We provide representative examples to illustrate that the new methods can outperform the state of the art, including Chambolle Pock, and the alternating direction method-of-multipliers algorithms. We also compare our algorithms with the well-known Nesterov smoothing method.
This paper presents a neural network approach with successful implementation for the robot task-sequencing problem. The problem addresses the sequencing of tasks comprising loading and unloading of parts into and from...
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This paper presents a neural network approach with successful implementation for the robot task-sequencing problem. The problem addresses the sequencing of tasks comprising loading and unloading of parts into and from the machines by a material-handling robot. The performance criterion is to minimize a weighted objective of the total robot travel time for a set of tasks and the tardiness of the tasks being sequenced. A three-phased parallel implementation of the neural network algorithm on Thinking Machine's CM-5 parallel computer is also presented which resulted in a dramatic increase in the speed of finding solutions. To evaluate the: performance of the neural network approach, a branch-and-bound method and a heuristic procedure have been developed for the problem. The neural network method is shown to give good results and is especially useful for solving large problems on a parallel-computing platform. (C) 2000 Elsevier Science Ltd. All rights reserved.
We describe a mechanically checked proof of a property of a small system of Java programs involving an unbounded number of threads and synchronization, via monitors. We adopt the output of the javac compiler as the se...
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We describe a mechanically checked proof of a property of a small system of Java programs involving an unbounded number of threads and synchronization, via monitors. We adopt the output of the javac compiler as the semantics and verify the system at the bytecode level under an operational semantics for the JVM. We assume a sequentially consistent memory model and atomicity at the bytecode level. Our operational semantics is expressed in ACL2, a Lisp-based logic of recursive functions. Our proofs are checked with the ACL2 theorem prover. The proof involves reasoning about arithmetic;infinite loops;the creation and modification of instance objects in the heap, including threads;the inheritance of fields from superclasses;pointer chasing and smashing;the invocation of instance methods (and the concomitant dynamic method resolution);use of the start method on thread objects;the use of monitors to attain synchronization between threads;and consideration of all possible interleavings (at the bytecode level) over an unbounded number of threads. Readers familiar with monitor-based proofs of mutual exclusion will recognize our proof as fairly classical. The novelty here comes from (i) the complexity of the individual operations on the abstract machine;(ii) the dependencies between Java threads, heap objects, and synchronization;(iii) the bytecode-level interleaving;(iv) the unbounded number of threads;(v) the presence in the heap of incompletely initialized threads and other objects;and (vi) the proof engineering permitting automatic mechanical verification of code-level theorems. We discuss these issues. The problem posed here is also put forth as a benchmark against which to measure other approaches to formally proving properties of multithreaded Java programs.
By using projections by a block of vectors in place of a single vector it is possible to parallelize the outer loop of iterative methods for solving sparse linear systems. We analyze such a scheme proposed by Coppersm...
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By using projections by a block of vectors in place of a single vector it is possible to parallelize the outer loop of iterative methods for solving sparse linear systems. We analyze such a scheme proposed by Coppersmith for Wiedemann's coordinate recurrence algorithm, which is based in part on the Krylov subspace approach. We prove that by use of certain randomizations on the input system the parallel speed up is roughly by the number of vectors in the blocks when using as many processors. Our analysis is valid for fields of entries that have sufficiently large cardinality. Our analysis also deals with an arising subproblem of solving a singular block Toeplitz system by use of the theory of Toeplitz-like matrices.
A distributed estimation algorithm for sensor networks is proposed. A noisy time-varying signal is jointly tracked by a network of sensor nodes, in which each node computes its estimate as a weighted sum of its own an...
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A distributed estimation algorithm for sensor networks is proposed. A noisy time-varying signal is jointly tracked by a network of sensor nodes, in which each node computes its estimate as a weighted sum of its own and its neighbors' measurements and estimates. The weights are adaptively updated to minimize the variance of the estimation error. Both estimation and the parameter optimization is distributed;no central coordination of the nodes is required. An upper bound of the error variance in each node is derived. This bound decreases with the number of neighboring nodes. The estimation properties of the algorithm are illustrated via computer simulations, which are intended to compare our estimator performance with distributed schemes that were proposed previously in the literature. The results of the paper allow to trading-off communication constraints, computing efforts and estimation quality for a class of distributed filtering problems.
In this paper we deal with the problem of designing virtual path layouts in ATM networks when the hop-count is given and the load has to be minimized. We first prove a lower bound for networks with arbitrary topology ...
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In this paper we deal with the problem of designing virtual path layouts in ATM networks when the hop-count is given and the load has to be minimized. We first prove a lower bound for networks with arbitrary topology and arbitrary set of connection requests. This result is then applied to derive lower bounds for the following settings: (i) one-to-all (one node has to be connected to all other nodes of the network) in arbitrary networks;(ii) all-to-all (each node has to be connected to all other nodes in the network) in several classes of networks, including planar and k-separable networks and networks of bounded genus. We finally study the all-to-all setting on two-dimensional meshes and we design a virtual path layout for this problem. When the hop-count and the network degree are bounded by constants, our results show that the upper bounds proposed in this paper for the one-to-all problem in arbitrary networks and for the all-to-all problem in two-dimensional mesh networks are asymptotically optimal. Moreover, the general lower bound shows that the algorithm proposed in Gerstel (Ph.D. Thesis, Technion-Haifa, Israel, 1995) for the all-to-all problem in k-separable networks is also asymptotically optimal. The upper bound for mesh networks also shows that the lower bound presented in this paper for the all-to-all problem in planar networks is asymptotically tight. (C) 2002 Elsevier Science B.V. All rights reserved.
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