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61.
研究了用单活性中心催化剂合成的新型乙烯-辛烯-1共聚物在不同条件下的结晶行为,表征了其支链分布。与普通支化聚乙烯相比,其支链分布均匀,不存在过长无支化链段,但并非单一分布,在小范围内有一定可变性,本工作进一步澄清了支链是否参予结晶这一有争议的问题。 相似文献
62.
A branch and bound method for stochastic global optimization 总被引:9,自引:0,他引:9
Vladimir I. Norkin Georg Ch. Pflug Andrzej Ruszczyński 《Mathematical Programming》1998,83(1-3):425-450
A stochastic branch and bound method for solving stochastic global optimization problems is proposed. As in the deterministic
case, the feasible set is partitioned into compact subsets. To guide the partitioning process the method uses stochastic upper
and lower estimates of the optimal value of the objective function in each subset. Convergence of the method is proved and
random accuracy estimates derived. Methods for constructing stochastic upper and lower bounds are discussed. The theoretical
considerations are illustrated with an example of a facility location problem. 相似文献
63.
Woonghee Tim Huh Ganesh JanakiramanPeter L. Jackson Nidhi Sawhney 《Operations Research Letters》2003,31(5):366-374
This paper studies minimizing the flow time of a cyclic schedule for repeated identical jobs, where one job is started/completed in each cycle, subject to the schedule achieving maximum throughput. We propose a branch and bound method for a single machine problem, and use this method to derive an improved lower bound for the multiple machine problem. 相似文献
64.
J. R. WillemsA. V. Cabot 《Mathematical and Computer Modelling》1995,21(12):75-84
In this paper, we present a branch and bound algorithm for solving the constrained entropy mathematical programming problem. Unlike other methods for solving this problem, our method solves more general problems with inequality constraints. The advantage of the proposed technique is that the relaxed problem solved at each node is a singly constrained network problem. The disadvantage is that the relaxed problem has twice as many variables as the original problem. An application to regional planning is given, and an example problem is solved. 相似文献
65.
In this paper, a branch and bound approach is proposed for global optimization problem (P) of the sum of generalized polynomial
fractional functions under generalized polynomial constraints, which arises in various practical problems. Due to its intrinsic
difficulty, less work has been devoted to globally solving this problem. By utilizing an equivalent problem and some linear
underestimating approximations, a linear relaxation programming problem of the equivalent form is obtained. Consequently,
the initial non-convex nonlinear problem (P) is reduced to a sequence of linear programming problems through successively
refining the feasible region of linear relaxation problem. The proposed algorithm is convergent to the global minimum of the
primal problem by means of the solutions to a series of linear programming problems. Numerical results show that the proposed
algorithm is feasible and can successfully be used to solve the present problem (P). 相似文献
66.
In this paper, we consider set covering problems with a coefficient matrix almost having the consecutive ones property, i.e., in most rows of the coefficient matrix, the ones appear consecutively and only a few blocks of consecutive ones appear in the remaining rows. If this property holds for all rows it is well known that the set covering problem can be solved efficiently. For our case of almost consecutive ones we present a reformulation exploiting the consecutive ones structure to develop bounds and a branching scheme. Our approach has been tested on real-world data as well as on theoretical problem instances. 相似文献
67.
Chenggen Shi Jie Lu Guangquan Zhang Hong Zhou 《Applied mathematics and computation》2006,180(2):529-537
For linear bilevel programming, the branch and bound algorithm is the most successful algorithm to deal with the complementary constraints arising from Kuhn–Tucker conditions. However, one principle challenge is that it could not well handle a linear bilevel programming problem when the constraint functions at the upper-level are of arbitrary linear form. This paper proposes an extended branch and bound algorithm to solve this problem. The results have demonstrated that the extended branch and bound algorithm can solve a wider class of linear bilevel problems can than current capabilities permit. 相似文献
68.
C. De Simone M. Diehl M. Jünger P. Mutzel G. Reinelt G. Rinaldi 《Journal of statistical physics》1996,84(5-6):1363-1371
In this paper we study the problem of finding an exact ground state of a two-dimensional ±J Ising spin glass on a square lattice with nearest neighbor interactions and periodic boundary conditions when there is a concentrationp of negative bonds, withp ranging between 0.1 and 0.9. With our exact algorithm we can determine ground states of grids of sizes up to 50×50 in a moderate amount of computation time (up to 1 hr each) for several values ofp. For the ground-state energy of an infinite spin-glass system withp=0.5 we estimateE
0.5
=–1.4015±0.0008. We report on extensive computational tests based on more than 22,000 experiments. 相似文献
69.
Indranirekha Saikia Moushumi Hazarika Najrul Hussian Manash R. Das Chandan Tamuly 《Tetrahedron letters》2017,58(45):4255-4259
Here, biogenic synthesis of Fe2O3@SiO2 nanoparticles using fruit extract of Zanthoxylum rhetsa is reported. The SiO2 nanoparticles was synthesized using paddy straw which is a byproduct obtained in cultivation of rice. The composite was characterised by spectroscopic method like XRD, SEM, TEM and EDX analysis. The ipso-hydroxylation reactions were carried out with excellent yield within a moderate time period with mild reaction condition in all cases. Therefore, this approach may be considered as simple, easy, cheap and greener, environment friendly protocol for ipso-hydroxylation of arylboronic acids at 50 °C temperature. 相似文献
70.
Class-based storage implementation decisions have significant impact on the required storage space and the material handling cost in a warehouse. In this paper, a nonlinear integer programming model is proposed to capture the above. Effects of storage area reduction on order picking and storage space cost are incorporated. A branch and bound algorithm is developed to solve the model. Computational experience with randomly generated data sets and an industrial case shows that branch and bound algorithm is computationally more efficient than a baseline dynamic programming algorithm. It is further observed that the class based policy results in lower total cost of order picking and storage space than the dedicated policy. 相似文献