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241.
Martín Gómez Ravetti Carlos Riveros Alexandre Mendes Mauricio G. C. Resende Panos M. Pardalos 《Annals of Operations Research》2012,199(1):269-284
This paper addresses the Permutation Flowshop Problem with minimization of makespan, which is denoted by Fm|prmu|C max. In the permutational scenario, the sequence of jobs has to remain the same in all machines. The Flowshop Problem (FSP) is known to be NP-hard when more than three machines are considered. Thus, for medium and large scale instances, high-quality heuristics are needed to find good solutions in reasonable time. We propose and analyse parallel hybrid search methods that fully use the computational power of current multi-core machines. The parallel methods combine a memetic algorithm (MA) and several iterated greedy algorithms (IG) running concurrently. Two test scenarios were included, with short and long CPU times. The tests were conducted on the set of benchmark instances introduced by Taillard (Eur. J. Oper. Res. 64:278?C285, 1993), commonly used to assess the performance of new methods. Results indicate that the use of the MA to manage a pool of solutions is highly effective, allowing the improvement of the best known upper bound for one of the instances. 相似文献
242.
Binwu Zhang Xiucui Guan Panos M. Pardalos Chunyuan He 《Journal of Optimization Theory and Applications》2018,178(2):538-559
Shortest path problems play important roles in computer science, communication networks, and transportation networks. In a shortest path improvement problem under unit Hamming distance, an edge-weighted graph with a set of source–terminal pairs is given. The objective is to modify the weights of the edges at a minimum cost under unit Hamming distance such that the modified distances of the shortest paths between some given sources and terminals are upper bounded by the given values. As the shortest path improvement problem is NP-hard, it is meaningful to analyze the complexity of the shortest path improvement problem defined on rooted trees with one common source. We first present a preprocessing algorithm to normalize the problem. We then present the proofs of some properties of the optimal solutions to the problem. A dynamic programming algorithm is proposed for the problem, and its time complexity is analyzed. A comparison of the computational experiments of the dynamic programming algorithm and MATLAB functions shows that the algorithm is efficient although its worst-case complexity is exponential time. 相似文献
243.
Jonas Hasselberg Panos M. Pardalos George Vairaktarakis 《Journal of Global Optimization》1993,3(4):463-482
In the last years many algorithms have been proposed for solving the maximum clique problem. Most of these algorithms have been tested on randomly generated graphs. In this paper we present different test problem generators that arise from a variety of practical applications, as well as graphs with known maximum cliques. In addition, we provide computational experience with two exact algorithms using the generated test problems. 相似文献
244.
245.
The High Dimensional Model Representation (HDMR) technique is a procedure for efficiently representing high-dimensional functions. A practical form of the technique, RS-HDMR, is based on randomly sampling the overall function and utilizing orthonormal polynomial expansions. The determination of expansion coefficients employs Monte Carlo integration, which controls the accuracy of RS-HDMR expansions. In this article, a correlation method is used to reduce the Monte Carlo integration error. The determination of the expansion coefficients becomes an iteration procedure, and the resultant RS-HDMR expansion has much better accuracy than that achieved by direct Monte Carlo integration. For an illustration in four dimensions a few hundred random samples are sufficient to construct an RS-HDMR expansion by the correlation method with an accuracy comparable to that obtained by direct Monte Carlo integration with thousands of samples. 相似文献
246.
247.
Recently, there are many papers published in the literature on study of dominating sets, connected dominating sets and their
variations motivated from various applications in wireless networks and social networks. In this article, we survey those
developments for wireless networking, dominating, and packing problems. 相似文献
248.
We approximate the objective function of the fixed charge network flow problem (FCNF) by a piecewise linear one, and construct
a concave piecewise linear network flow problem (CPLNF). A proper choice of parameters in the CPLNF problem guarantees the
equivalence between those two problems. We propose a heuristic algorithm for solving the FCNF problem, which requires solving
a sequence of CPLNF problems. The algorithm employs the dynamic cost updating procedure (DCUP) to find a solution to the CPLNF
problems. Preliminary numerical experiments show the effectiveness of the proposed algorithm. In particular, it provides a
better solution than the dynamic slope scaling procedure in less CPU time.
Research was partially supported by NSF and Air Force grants. 相似文献
249.
Panos Hatsis Gary Valaskovic Jing‐Tao Wu 《Rapid communications in mass spectrometry : RCM》2009,23(23):3736-3742
Nanoelectrospray ionization (nESI) coupled online with high‐field asymmetric waveform ion mobility spectrometry (FAIMS) for small molecule analysis in a discovery pharmaceutical setting was examined. A conventional capillary pump, autosampler and nESI source were used to introduce samples directly into the FAIMS device. The FAIMS device was used to separate gas‐phase ions on a timescale that was compatible with the mass spectrometer. The capability of the nESI‐FAIMS combination to efficiently remove metabolite interferences from the parent drug, and reduce ion suppression effects, was demonstrated. On average, 85% of the signal intensity obtained from a neat sample was preserved in the extracted plasma samples. Standard curves were prepared for several compounds. Linearity was obtained over approximately 3 to 4 orders of magnitude. Comparison of results from nESI‐FAIMS with those from conventional LC/MS for a mouse pharmacokinetic study yielded concentration values differing by no more than 30%. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
250.
Jamming communication networks under complete uncertainty 总被引:1,自引:0,他引:1
Clayton W. Commander Panos M. Pardalos Valeriy Ryabchenko Oleg Shylo Stan Uryasev Grigoriy Zrazhevsky 《Optimization Letters》2008,2(1):53-70
This paper describes a problem of interdicting/jamming wireless communication networks in uncertain environments. Jamming
communication networks is an important problem with many applications, but has received relatively little attention in the
literature. Most of the work on network interdiction is focused on preventing jamming and analyzing network vulnerabilities.
Here, we consider the case where there is no information about the network to be jammed. Thus, the problem is reduced to jamming
all points in the area of interest. The optimal solution will determine the locations of the minimum number of jamming devices
required to suppress the network. We consider a subproblem which places jamming devices on the nodes of a uniform grid over
the area of interest. The objective here is to determine the maximum grid step size. We derive upper and lower bounds for
this problem and provide a convergence result. Further, we prove that due to the cumulative effect of the jamming devices,
the proposed method produces better solutions than the classical technique of covering the region with uniform circles. 相似文献