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1.
结合布局问题的具体特点,采用序列对来间接描述布局问题的解结构,并且在模拟退火算法的基础上对布局问题的优化算法进行了研究,综合构成了一种有效求解布局问题的模拟退火算法。还将传统模拟退火算法和加回火策略的模拟退火算法的测试结果进行了比较。通过测试模块验证,传统算法取得了很优的结果,加回火策略的算法略微优于传统优化算法但却大大增加了时间复杂度。  相似文献   

2.
在传统模拟退火算法的基础上,对布局问题的优化算法进行了研究,采用回火策略,改进一般模拟退火算法寻优的效果;结合布局问题的具体特点,采用Sequence Pair来描述布局问题的解结构,综合构成了一种新的求解布局问题的模拟退火算法.通过算例验证,该算法优于传统优化算法和普通启发式搜索算法,并且对增量布局也能够取得较好的效果.  相似文献   

3.
一种混合全局寻优算法及其在布局中的应用   总被引:2,自引:2,他引:0  
布局问题是NP完全问题,传统的优化算法很难求得全局最优欠解,遗传算法和模拟退火算法等的随机搜索算法的求解精度和效率不能令人满意,文中将启发式随机搜索策略的局部优化算法相结合,构造混合全局寻优算法,以旋转卫星舱布局问题的简化模型为背景,建立了多目标优化的数学模型,通过一已在最优解的布局算例与遗传算法和乘子法的计算结果比较,该算法求解的质量和效率更优,表明此算法在布局优化中具有应用潜力。  相似文献   

4.
在分析中小学的排课问题并研究相关算法的基础上,提出了把动态规划算法和模拟退火算法相结合的一种新的排课算法.动态规划算法求出满足约束条件的一个解,作为模拟退火算法的初始解,用模拟退火算法对初始解优化,得到一个优化后的课表.  相似文献   

5.
针对化学反应优化对反馈信息利用不足导致后期求解效率低的问题,提出化学反应蚁群优化算法.该算法利用化学反应优化生成较优解,通过信息素转换策略将较优解转换为蚁群算法的初始信息素,最后由蚁群算法累积更新信息素得到最优解.以TSP为例进行仿真,结果表明,与化学反应优化、蚁群算法、模拟退火算法相比,所提算法具有更高的寻优能力、收敛效率和计算效率.  相似文献   

6.
解布局问题的四元组数据结构及其模拟退火算法   总被引:2,自引:0,他引:2  
本文提出解布局问题的四元组数据结构,并根据该结构给出求解的模拟退火算法的基本程序。该结构和算法可直接用于求解复杂的布局问题,具有直接的实用价值和重要的理论意义。  相似文献   

7.
由于设备布局问题是NP完全问题,它在有限合理的时间内难以求得最优解,因此问题的求解只能依赖于各种启发式方法。文章针对传统的模拟退火算法经常出现迂回搜索,导致搜索效率低,解的质量差这一现象,通过在传统模拟退火算法搜索过程中增加记忆功能,来避免迂回搜索,将改进的模拟退火算法应用于设备布局的研究中,通过实例证明改进的模拟退火算法解的质量有了很大提高。  相似文献   

8.
岳琪  曹军 《计算机应用研究》2005,22(10):226-228,244
讨论了如何利用改进的模拟退火算法即单调升温的模拟退火算法求解板式家具生产中的优化下料问题。在对问题进行数学描述的基础上,给出了算法求解的关键步骤和方法;讨论了单调升温模拟退火算法中如何跳出局部最优解,以及升温幅值的确定方法。实例表明该算法优化速度快,效率高,能有效解决大规模矩形件优化下料问题。  相似文献   

9.
针对芯片堆叠的热布局优化问题,使用热叠加模型,结合热传导公式,以所有芯片温度的最高值作为评价指标,确定出三维芯片堆叠热布局优化的适应度函数;然后采用模拟退火离散粒子群算法对芯片热布局进行优化。得到优化后的芯片堆叠布局方案,并用Icepak软件对优化后的布局进行仿真验证。仿真结果表明:采用模拟退火离散粒子群算法对三维芯片堆叠进行热布局优化可以使温度分布更加均匀,最高温度明显降低。  相似文献   

10.
基于遗传算法和模拟退火算法的布局问题研究   总被引:8,自引:0,他引:8  
文章在介绍遗传算法和模拟退火算法的基本理论及主要特点的基础上,提出了一个基于遗传算法和模拟退火算法的求解布局问题(矩形件排样优化)算法,并通过算例验证了该算法的有效性。  相似文献   

11.
The numerical solution of variational inequality problems in elastostatics is investigated by means of recently proposed equivalent nonlinear equations. Symmetric and nonsymmetric variational inequalities and linear or nonlinear, but monotone, complementarity problems can be solved this way without explicit use of nonsmooth (nondifferentiable) solvers. As a model application, two-dimentional unilateral contact problems with and without friction effects approximated by the boundary element method are formulated as nonsymmetric variational inequalities, or, for the two-dimensional case as linear complementarity problems, and are numerically solved. Performance comparisons using two standard, smooth, general purpose nonlinear equation solvers are included.  相似文献   

12.
Optimization problems with criterion functions and admissible sets symmetric with respect to some transformations are considered. Conditions are studied which guarantee that solutions of these problems exist on a set of points fixed with respect to the initial transformation for continuous problems and on a set of quasifixed points for integer problems.  相似文献   

13.
14.
Almost 2-SAT is fixed-parameter tractable   总被引:1,自引:0,他引:1  
We consider the following problem. Given a 2-cnf formula, is it possible to remove at most k clauses so that the resulting 2-cnf formula is satisfiable? This problem is known to different research communities in theoretical computer science under the names Almost 2-SAT, All-but-k 2-SAT, 2-cnf deletion, and 2-SAT deletion. The status of the fixed-parameter tractability of this problem is a long-standing open question in the area of parameterized complexity. We resolve this open question by proposing an algorithm that solves this problem in O(k15×k×m3) time showing that this problem is fixed-parameter tractable.  相似文献   

15.
Multicriteria/multiobjective path and tree models are useful in many applications. Particularly, in Internet routing problems they seem to lead to promising approaches. In the first part of this paper, we classify and present the main exact approaches dealing with several multicriteria path problems putting in evidence the shortest path problem. In the second part, we review exact algorithms dedicated to some multicriteria tree problems, namely the minimum spanning tree and the minimum cost/minimum label spanning tree problems. Finally, the application of these models is exemplified.  相似文献   

16.
Differential evolution is primarily designed and used to solve continuous optimization problems. Therefore, it has not been widely considered as applicable for real-world problems that are characterized by permutation-based combinatorial domains. Many algorithms for solving discrete problems using differential evolution have been proposed, some of which have achieved promising results. However, to enhance their performance, they require improvements in many aspects, such as their convergence speeds, computational times and capabilities to solve large discrete problems. In this paper, we present a new mapping method that may be used with differential evolution to solve combinatorial optimization problems. This paper focuses specifically on the mapping component and its effect on the performance of differential evolution. Our method maps continuous variables to discrete ones, while at the same time, it directs the discrete solutions produced towards optimality, by using the best solution in each generation as a guide. To judge its performance, its solutions for instances of well-known discrete problems, namely: 0/1 knapsack, traveling salesman and traveling thief problems, are compared with those obtained by 8 other state-of-the-art mapping techniques. To do this, all mapping techniques are used with the same differential evolution settings. The results demonstrated that our technique significantly outperforms the other mapping methods in terms of the average error from the best-known solution for the traveling salesman problems, and achieves promising results for both the 0/1 knapsack and the traveling thief problems.  相似文献   

17.
The Semiring Constraint Satisfaction Problem (SCSP) framework is a popular approach for the representation of partial constraint satisfaction problems. In this framework preferences can be associated with tuples of values of the variable domains. Bistarelli et al. [S. Bistarelli, U. Montanari, F. Rossi, Semiring-based constraint solving and optimization, Journal of the ACM 44 (2) (1997) 201-236] defines a maximal solution to a SCSP as the best set of solution tuples for the variables in the problem. Sometimes this maximal solution may not be good enough, and in this case we want to change the constraints so that we solve a problem that is slightly different from the original problem but has an acceptable solution. We propose a relaxation of a SCSP, and use a semiring to give a measure of the difference between the original SCSP and the relaxed SCSP. We introduce a relaxation scheme but do not address the computational aspects.  相似文献   

18.
19.
基于演化算法的一类时间表问题的自动求解   总被引:6,自引:3,他引:3  
本文给出了一种有效的基于演化算法的求解大学的时间表总理2(编排课程和考试)即在很强的资源约束条件下将一些事件(课程或考试)安排到时间段和空间位置的总理2的方法,此方法有杉直接的时间表编码表示和启发式深化算子,并通过惩罚函数保证对约束条件的满足,计算实验表明方法在求解大学考试时间表问题中是有效的。  相似文献   

20.
Phase change problems are of practical importance and can be found in a wide range of engineering applications. In the present paper, two proposed numerical algorithms are developed; the first one is general for phase change problems, while the second one is for ablation problems. The boundary elements method is used as a mathematical tool in conjunction with the proposed algorithms. Two test examples were solved and the results agree with the physics of the problems.  相似文献   

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