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带有模糊参数的农业生产计划模型   总被引:3,自引:1,他引:2  
在现实的生产系统中, 由于材料价格, 产品价格, 市场需求以及劳动者能力等不确定因素的影响, 生产计划问题常常是一个不确定规划问题. 因此, 带有常系数的生产计划模型不能准确有效的描述生产决策环境. 基于可信性理论, 本文将提出一类新的带有模糊参数的生产计划模型. 然后, 我们讨论了可信性函数的逼近并且设计一个基于逼近方法、神经网络和遗传算法的启发式算法来求解这个模糊生产计划问题. 最后, 给出了一个数值例子来表明所设计算法的可行性和有效性.  相似文献
2.
This work deals with the continuous time lot-sizing inventory problem when demand and costs are time-dependent. We adapt a cost balancing technique developed for the periodic-review version of our problem to the continuous-review framework. We prove that the solution obtained costs at most twice the cost of an optimal solution. We study the numerical complexity of the algorithm and generalize the policy to several important extensions while preserving its performance guarantee of two. Finally, we propose a modified version of our algorithm for the lot-sizing model with some restricted settings that improves the worst-case bound.  相似文献
3.
The approximate sampling theorem with its associated aliasing error is due to J.L. Brown (1957). This theorem includes the classical Whittaker–Kotel’nikov–Shannon theorem as a special case. The converse is established in the present paper, that is, the classical sampling theorem for , 1p<∞, w>0, implies the approximate sampling theorem. Consequently, both sampling theorems are fully equivalent in the uniform norm.Turning now to -space, it is shown that the classical sampling theorem for , 1<p<∞ (here p=1 must be excluded), implies the -approximate sampling theorem with convergence in the -norm, provided that f is locally Riemann integrable and belongs to a certain class Λp. Basic in the proof is an intricate result on the representation of the integral as the limit of an infinite Riemann sum of |f|p for a general family of partitions of ; it is related to results of O. Shisha et al. (1973–1978) on simply integrable functions and functions of bounded coarse variation on . These theorems give the missing link between two groups of major equivalent theorems; this will lead to the solution of a conjecture raised a dozen years ago.  相似文献
4.
ALTERNATIONTHEORYINAPPROXIMATIONBYPOLYNOMIALSHAVINGBOUNDEDCOEFFICIENTSXUSHUSHENG(许树声)(JiangnanUniversity,Wuxi214063,China)Abs...  相似文献
5.
This paper presents an analytical approach for scheduling crackdowns on street-corner drug markets. The crackdown scheduling problem is shown to be NP-complete. We then provide efficient optimal algorithms for several special cases and approximation algorithms for the general case. These results show that the optimal strategy is to give priority to markets that take longer to bring down and which require low levels of post-crackdown maintenance. The results are then extended to incorporate dealer displacement between drug markets.  相似文献
6.
用线性正算子的逼近理论飞速发展,但正性是一个较强的限制,孙永生,王仁宏等研究过减弱正性限制,作者研究用线性弱正算子逼近,推广Korovkin定理和Grundmann定理等等.  相似文献
7.
Given an undirected, edge-weighted connected graph, the k-cut problem is to partition the vertex set into k non-empty connected components so as to minimize the total weight of edges whose end points are in different components.  相似文献
8.
It has been evident that the theory and methods of dynamic derivatives are playing an increasingly important rle in hybrid modeling and computations.Being constructed on various kinds of hybrid grids,that is,time scales,dynamic derivatives offer superior accuracy and flexibility in approximating mathematically important nat- ural processes with hard-to-predict singularities,such as the epidemic growth with un- predictable jump sizes and option market changes with high uncertainties,as com- pared with conventional derivatives.In this article,we shall review the novel new concepts,explore delicate relations between the most frequently used second-order dy- namic derivatives and conventional derivatives.We shall investigate necessary condi- tions for guaranteeing the consistency between the two derivatives.We will show that such a consistency may never exist in general.This implies that the dynamic derivatives provide entirely different new tools for sensitive modeling and approximations on hy- brid grids.Rigorous error analysis will be given via asymptotic expansions for further modeling and computational applications.Numerical experiments will also be given.  相似文献
9.
Let H be a Hilbert space, AL(H), y ∈ , and yR(A). We study the behavior of the distance square between y and A(B τ), defined as a functional F(τ), as the radius τ of the ball B τ of H tends to ∞. This problem is important in estimating the approximation error in learning theory. Our main result is to estimate the asymptotic behavior of F(τ) without the compactness assumption on the operator A. We also consider the Peetre K-functional and its convergence rates.   相似文献
10.
The article deals with the existence and the approximation of nontrivial solutions to a general hemivariational inequality where the potential corresponding to the nonlinear term admits a superquadratic growth. Finally, convergence results for Galerkin type approximation are established. Since the usual techniques based on coerciveness assumptions fail in this case, one makes use of nonsmooth variational arguments. Our approach allows to cover in a unifying way the superlinear and sublinear situations. Improvements and completions of previous results are obtained.  相似文献
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