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31.
The sonochemical activity and the radial dynamics of a harmonically excited spherical bubble are investigated numerically. A detailed model is employed capable to calculate the chemical production inside the bubble placed in water that is saturated with oxygen. Parameter studies are performed with the control parameters of the pressure amplitude, the forcing frequency and the bubble size. Three different definitions of collapse strengths (extracted from the radius vs. time curves) are examined and compared with the chemical output of various species. A mathematical formula is established to estimate the chemical output as a function of the collapse strength; thus, the chemical activity can be predicted without taking into account the chemical kinetics into the bubble model. The calculations are carried out by an in-house code exploiting the high processing power of professional graphics cards (GPUs).The results shown that chemical activity can be approximated qualitatively from the values of relative expansion. This could be helpful in order to optimise chemical output of sonochemical reactors either from measurement data or simulations as well. 相似文献
32.
33.
Scenario Reduction Algorithms in Stochastic Programming 总被引:4,自引:0,他引:4
We consider convex stochastic programs with an (approximate) initial probability distribution P having finite support supp P, i.e., finitely many scenarios. The behaviour of such stochastic programs is stable with respect to perturbations of P measured in terms of a Fortet-Mourier probability metric. The problem of optimal scenario reduction consists in determining a probability measure that is supported by a subset of supp P of prescribed cardinality and is closest to P in terms of such a probability metric. Two new versions of forward and backward type algorithms are presented for computing such optimally reduced probability measures approximately. Compared to earlier versions, the computational performance (accuracy, running time) of the new algorithms has been improved considerably. Numerical experience is reported for different instances of scenario trees with computable optimal lower bounds. The test examples also include a ternary scenario tree representing the weekly electrical load process in a power management model. 相似文献
34.
随机交通均衡配流模型及其等价的变分不等式问题 总被引:7,自引:0,他引:7
本文讨论了交通网络系统的随机用户均衡原理的数学表述问题.在路段出行成本是流量的单调函数的较弱条件下,对具有固定需求和弹性需求的模式,首次证明了随机均衡配流模型可表示为一个变分不等式问题,同时也说明了该变分不等式问题与相应的互补问题以及一个凸规划问题之间的等价关系. 相似文献
35.
汽配件颜色喷涂顺序问题通常以生产线上相邻汽配件颜色切换次数少为最优目标,以进一步降低生产成本.该类问题具有所有汽配件都必须喷涂一次且只喷涂一次的特点,为此提出了TSP转化与建模的方法.将待喷涂汽配件定义为TSP顶点,任意两个待喷涂汽配件的颜色切换定义为顶点的距离,仿照TSP问题构建0-1规划模型;类似于顶点距离,将某些... 相似文献
36.
37.
In this paper, we study optimal retirement in a two-dimensional incomplete market caused by borrowing constraints and forced unemployment risk. We show that the two aspects jointly affect an individual’s optimal consumption, investment, and retirement strategies. In contrast to the complete market case, the endogenously determined wealth threshold for retirement is significantly affected by the two-dimensional market incompleteness, resulting in a lower wealth threshold. We also discuss a possible unemployment insurance scheme for the borrowing-constrained individual to respond to the shocks of forced unemployment. 相似文献
38.
In this paper, we study inverse optimization for linearly constrained convex separable programming problems that have wide applications in industrial and managerial areas. For a given feasible point of a convex separable program, the inverse optimization is to determine whether the feasible point can be made optimal by adjusting the parameter values in the problem, and when the answer is positive, find the parameter values that have the smallest adjustments. A sufficient and necessary condition is given for a feasible point to be able to become optimal by adjusting parameter values. Inverse optimization formulations are presented with ℓ1 and ℓ2 norms. These inverse optimization problems are either linear programming when ℓ1 norm is used in the formulation, or convex quadratic separable programming when ℓ2 norm is used. 相似文献
39.
Discrete optimization in public rail transport 总被引:5,自引:0,他引:5
Many problems arising in traffic planning can be modelled and solved using discrete optimization. We will focus on recent
developments which were applied to large scale real world instances.
Most railroad companies apply a hierarchically structured planning process. Starting with the definition of the underlying
network used for transport one has to decide which infrastructural improvements are necessary. Usually, the rail system is
periodically scheduled. A fundamental base of the schedule are the lines connecting several stations with a fixed frequency.
Possible objectives for the construction of the line plan may be the minimization of the total cost or the maximization of
the passengers’s comfort satisfying certain regulations. After the lines of the system are fixed, the train schedule can be
determined. A criterion for the quality of a schedule is the total transit time of the passengers including the waiting time
which should be minimized satisfying some operational constraints. For each trip of the schedule a train consisting of a locomotive
and some carriages is needed for service. The assignment of rolling stock to schedule trips has to satisfy operational requirements.
A comprehensible objective is to minimize the total cost. After all strategic and tactical planning the schedule has to be
realized. Several external influences, for example delayed trains, force the dispatcher to recompute parts of the schedule
on-line.
A Web page with examples quoted in this survey can be found at http://www.math.tu-bs.de/mo/ismp.html. 相似文献
40.
M. Schechter 《Journal of Optimization Theory and Applications》1977,23(3):389-400
A symmetric duality theory for programming problems with homogeneous objective functions was published in 1961 by Eisenberg and has been used by a number of authors since in establishing duality theorems for specific problems. In this paper, we study a generalization of Eisenberg's problem from the viewpoint of Rockafellar's very general perturbation theory of duality. The extension of Eisenberg's sufficient conditions appears as a special case of a much more general criterion for the existence of optimal vectors and lack of a duality gap. We give examples where Eisenberg's sufficient condition is not satisfied, yet optimal vectors exist, and primal and dual problems have the same value. 相似文献