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排序方式: 共有2346条查询结果,搜索用时 15 毫秒
121.
Raffaele Cerulli Paola Festa Giancarlo Raiconi 《Computational Optimization and Applications》2003,26(2):191-208
In this paper, the problem of finding a shortest path tree rooted at a given source node on a directed graph (SPT) is considered. A new efficient algorithm based on a primal-dual approach is presented, which improves both the convergence and the complexity of the best known auction-like algorithm. It uses the virtual source (VS) concept based on the following consideration: when a node i is visited for the first time by any algorithm which preserves verified the dual admissibility conditions, then the shortest path (SP) from the source node to i is found. Therefore, the SP from the source to the remaining nodes may be computed by considering i as a virtual source.We propose a very efficient implementation of an auction-like algorithm that uses this concept and enables us to obtain a computational cost of O(n
2), where n is the number of nodes.Numerical experimentsare reported showing that the new method outdoes previously proposed auction-like algorithms and is highly competitive with other state-of-art SP approaches. 相似文献
122.
Minimizing risk models in stochastic shortest path problems 总被引:1,自引:0,他引:1
Yoshio Ohtsubo 《Mathematical Methods of Operations Research》2003,57(1):79-88
123.
Let P
k be a path on k vertices. In an earlier paper we have proved that each polyhedral map G on any compact 2-manifold
with Euler characteristic
contains a path P
k such that each vertex of this path has, in G, degree
. Moreover, this bound is attained for k = 1 or k 2, k even. In this paper we prove that for each odd
, this bound is the best possible on infinitely many compact 2-manifolds, but on infinitely many other compact 2-manifolds the upper bound can be lowered to
. 相似文献
124.
Simulation optimization of buffer allocations in production lines with unreliable machines 总被引:3,自引:0,他引:3
Gül Gürkan 《Annals of Operations Research》2000,93(1-4):177-216
We use a recent simulationbased optimization method, sample path optimization, to find optimal buffer allocations in tandem production lines where machines are subject to random breakdowns and repairs, and the product is fluidtype. We explore some of the functional properties of throughput of such systems and exploit these properties to prove the almost sure convergence of our optimization technique, under a regularity condition on the steady state. Utilizing a generalized semiMarkov process (GSMP) representation of the system, we derive recursive expressions to compute onesided directional derivatives of throughput, from a single simulation run. Finally, we give computational results for lines with up to 50 machines. We also compare results for smaller lines with the results from a more conventional method, stochastic approximation, whenever applicable. In these numerical studies, our method performed quite well on problems that are considered difficult by current computational standards. 相似文献
125.
将竞争机理引入网络的自动波产生与传播过程中,提出自动波竞争神经网络(ACNN)模型,并成功地应用于求解单源最短路问题,给出了基于ACNN的最短路求解算法. 与其他神经网络最短路算法相比,基于ACNN的最短路算法具有网络所需的神经元数目少、神经元及网络的结构简单、易于软硬件的实现、以及全并行方式计算等特点,可用于求解非对称赋权图的最短路径树问题,且其计算时间(迭代次数)仅正比于最短路径上的跃点数,与赋权图的复杂度、路径总长、边长的精度、通路总数等因素无关. 计算机仿真结果表明该算法的有效性和快速求解能力.
关键词:
单源最短路问题
自动波竞争神经网络
脉冲耦合神经网络 相似文献
126.
M. Faber A. N. Ivanov N. I. Troitskaya 《International Journal of Theoretical Physics》2007,46(1):143-148
We evaluate the evolution operator Z
Reg(R
2,R
1) introduced by Diakonov and Petrov for the definition of the Wilson loop in terms of a path integral over gauge degrees of
freedom. We use the procedure suggested by Diakonov and Petrov (Physics Letters B
224 (1989) 131) and show that the evolution operator vanishes.
PACS numbers: 11.10.-z; 11.15.-q; 12.38.-t; 12.38.Aw; 12.90.+b. 相似文献
127.
128.
Liu Hui-jun 《Frontiers of Physics in China》2007,2(2):171-177
We review our density functional study of oxygen adsorption on the outer surface of 4 ? single-wall carbon nanotubes, which
have been recently synthesized using a templating method. The stability of these 4 ? tubes under ambient conditions is investigated
by the nudged elastic band technique and further confirmed by the experimentally measured Raman spectra. Different adsorption
pictures of singlet O2 could be used to select a single chirality from a mixture of these ultra-small radius tubes.
相似文献
129.
This study proposes a common path interference optical system for the measurement of refractive indices and thickness of uniaxial crystal material. The measurement system comprises an accurate Mach–Zehnder laser interferometer, a single-axis rotary stepping motor, and a computer. The laser interferometer is composed of a single-frequency He–Ne laser, two-beam splitters and two reflectors. The Mach–Zehnder laser interferometer measures the optical length difference by using its linear measurement accuracy. The proposed solution procedure enables both the refractive indices and the thickness of the optical waveplate to be obtained. The proposed design differs from conventional designs in that it does not use a heterodyne modulator with a lock-in technique. It is shown that the refractive indices and thickness of the tested optical elements can be measured rapidly and accurately. 相似文献
130.
The identification of tyre induced vehicle interior noise 总被引:2,自引:0,他引:2
Sound transmission into a vehicle is classified as either airborne or structure borne sound. From the point view of noise control, the reduction of noise transferred by different paths requires different solutions. Coherence function analysis is often used to identify transmission paths. However it can be difficult to separate the airborne from structure borne components. The principle of acoustic reciprocity offers a convenient method for overcoming this difficulty. The principal states that the transfer function between an acoustic volume velocity source and an acoustic receiver is independent of a reversal of the position of source and receiver. The work done on this study involves exciting a stationary tyre and measuring the surface velocity of the tyre at a number of discrete points. The acoustic transfer functions between each point on the tyre and a receiver point are measured reciprocally. Two sets of measurements are then combined to yield a measure of the sound pressure due to a point force on the tyre via the acoustic transmission path only. This technique also provides information on the relative contributions of various regions of the tyre wall to the resultant noise. Also the sound radiation characteristics, the horn effect, and resonance at the wheel housing are identified through the reciprocal measurement. 相似文献