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排序方式: 共有141条查询结果,搜索用时 15 毫秒
51.
We study the mixing time of the Glauber dynamics for general spin systems on the regular tree, including the Ising model, the hard‐core model (independent sets), and the antiferromagnetic Potts model at zero temperature (colorings). We generalize a framework, developed in our recent paper (Martinelli, Sinclair, and Weitz, Tech. Report UCB//CSD‐03‐1256, Dept. of EECS, UC Berkeley, July 2003) in the context of the Ising model, for establishing mixing time O(nlog n), which ties this property closely to phase transitions in the underlying model. We use this framework to obtain rapid mixing results for several models over a significantly wider range of parameter values than previously known, including situations in which the mixing time is strongly dependent on the boundary condition. We also discuss applications of our framework to reconstruction problems on trees. © 2006 Wiley Periodicals, Inc. Random Struct. Alg., 2007 相似文献
52.
Moshe Dror Gilbert Laporte Francois V. Louveaux 《Mathematical Methods of Operations Research》1993,37(3):273-283
This paper considers a class of stochastic vehicle routing problems (SVRPs) with random demands, in which the number of potential failures per route is restricted either by the data or the problem constraints. These are realistic cases as it makes little sense to plan vehicle routes that systematically fail a large number of times. First, a chance constrained version of the problem is considered which can be solved to optimality by algorithms similar to those developed for the deterministic vehicle routing problem (VRP). Three classes of SVRP with recourse are then analyzed. In all cases, route failures can only occur at one of the lastk customers of the planned route. Since in general, SVRPs are considerably more intractable than the deterministic VRPs, it is interesting to note that these realistic stochastic problems can be solved as a sequence of deterministic traveling salesman problems (TSPs). In particular, whenk=1 the SVRP with recourse reduces to a single TSP. 相似文献
53.
Vehicle routing with split deliveries 总被引:6,自引:0,他引:6
This paper considers a relaxation of the classical vehicle routing problem (VRP), in which split deliveries are allowed. As the classical VRP, this problem is NP-hard, but nonetheless it seems more difficult to solve exactly. It is first formulated as an integer linear program. Several new classes of valid constraints are derived, and a hierarchy between these is established. A constraint relaxation branch and bound algorithm for the problem is then described. Computational results indicate that by using an appropriate combination of constraints, the gap between the lower and upper bounds at the root of the search tree can be reduced considerably. These results also confirm the quality of a previously published heuristic for this problem. 相似文献
54.
In this paper we consider an investment problem by an insurance firm. As in the classical model of collective risk, it is assumed that premium payments are received deterministically from policyholders at a constant rate, while the claim process is determined by a compound Poisson process. We introduce a conversion mechanism of funds from cash into investments and vice versa. Contrary to the conventional collective risk model we do not assume a ruin barrier. Instead we introduce conversion costs to account for the problems implicit in reaching the zero boundary. The objective of the firm is to maximize its net profit by selecting an appropriate investment strategy. A diffusion approximation is suggested in order to obtain tractable results for a general claim size distribution. 相似文献
55.
56.
Naum Parkansky Boris A. Alterkop Raymond L. Boxman Hadas Mamane Dror Avisar 《Plasma Chemistry and Plasma Processing》2008,28(5):583-592
Low voltage, low energy submerged pulsed arcs were used to break-down Sulfadimethoxine (SDM) contamination in aqueous solutions.
The SDM concentration decreased exponentially with rate constants of 0.13–1.9 min−1 during processing by pulsed arcs with a pulse repetition rate of 100 Hz, energies of 2.6–192 mJ and durations of 20, 50 and
100 μs. The electrical energy consumption was minimized with short duration pulses––1.5 kW-hr/m3 with 7.5 mJ, 20 μs pulses for 90% SDM removal. 相似文献
57.
Neelam Dror Shamir Ariela Burg Subramanian Palaniappan 《Journal of Coordination Chemistry》2016,69(23):3449-3457
Electron exchange columns were developed by utilizing the redox properties of polyoxometalates (POMs) entrapped in silica matrices via the sol–gel route. The properties of the columns strongly depend on the composition of the precursors used to prepare the matrices. The columns exhibit good reversibility and are the first ‘reducing’ electron exchange columns ever prepared. They are also the first columns where both the matrix and the entrapped redox agent are inorganic compounds. This increases their stability. However, the redox properties of the entrapped POMs in the matrices are affected by the composition of the matrices. 相似文献
58.
In this paper, we present a new approach providing super resolved images exceeding the geometrical limitation given by the detector pixel size of the imaging camera. The concept involves the projection of periodic patterns on top of the sample, which are then investigated under a microscope. Combining spatial scanning together with proper digital post-processing algorithm yields the improved geometrical resolution enhancement. This new method is especially interesting for microscopic imaging when the resolution of the detector is lower than the resolution due to diffraction. 相似文献
59.
We prove a conjecture stated by Melvin and Morton (and elucidated further by Rozansky) saying that the Alexander–Conway polynomial
of a knot can be read from some of the coefficients of the Jones polynomials of cables of that knot (i.e., coefficients of
the “colored” Jones polynomial). We first reduce the problem to the level of weight systems using a general principle, which
may be of some independent interest, and which sometimes allows to deduce equality of Vassiliev invariants from the equality
of their weight systems. We then prove the conjecture combinatorially on the level of weight systems. Finally, we prove a
generalization of the Melvin–Morton–Rozansky (MMR) conjecture to knot invariants coming from arbitrary semi-simple Lie algebras.
As side benefits we discuss a relation between the Conway polynomial and immanants and a curious formula for the weight system
of the colored Jones polynomial.
Oblatum 28-VII-1994 & 5-XI-1995 & 22-XI-1995 相似文献
60.
We examine cooperative games in supply-chain management termed Inventory Games. Supply-chain management has non-cooperative and cooperative interactions between the participating players. We provide a concise survey of cooperative inventory games in the form of extensions on two basic problems. For deterministic games, Economic Order Quantity-like policies with joint replenishment are of primary interest. For stochastic games we examine Newsvendor-like centralization games and their extensions. We conclude with a short summary of a dynamic Newsvendor realization game and directions for further research. 相似文献