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1.
考虑由一个分销中心和一个零售商组成的单一产品两级动态经济批量问题,其中零售商在每一进货期的进货量都具有数量限制.目的是确定分销中心和零售商分别在什么时期进货以及进多少单位的货物,从而使分销中心和零售商的运输费用和库存费用总和最小.分析了最优解的性质,并且利用动态规划和最短路问题在O(n5)时间内解决了此问题.最后给出了此算法的一个算例,表明此算法是可行有效的.  相似文献   

2.
李珍萍  焦鹏博 《科学技术与工程》2021,21(26):11362-11367
基于供应商管理库存(VMI)模式制定科学的产品配送决策,可以合理优化库存水平、有效提高物流运输效率。本文针对VMI模式下的配送路径优化问题开展研究,考虑客户的产品消耗率和服务时间窗等因素,以总配送成本最小为目标,建立混合整数规划模型,并设计了贪婪算法;首先利用Gurobi求解器对小规模算例进行求解,分析VMI模式的优越性,结果表明,基于VMI模式的配送路径规划方案可以有效减少库存水平,降低总配送成本;然后利用中等规模算例分析贪婪算法的求解效果,结果显示,对于40个点的中等规模算例,求解器在240分钟内无法得到最优解,而贪婪算法可以在0.2秒之内得到近似最优解。  相似文献   

3.
考虑路段充电和时间窗的电动车取送货问题,以最小化车辆总旅行距离为目标,结合车辆容量约束、时间窗约束和电量约束等限制,决策一组最优的车辆线路。该问题公式化为一个混合整数线性规划模型,提出一种变邻域搜索算法求解该问题。数值算例用于验证模型的性质和算法的性能。结果表明:在小规模算例中,提出的算法只比商业求解器CPLEX差0.08%;但在大规模算例中,算法能求出高质量的可行解而CPLEX在规定时间内无法得到可行解。  相似文献   

4.
摘要:
在供应链协同库存背景下研究了基于集合覆盖的有时间和容量限制的配送中心选址问题,目标是系统的成本最小以及决策配送中心向需求点提供最优配送量.根据建模的假设条件,建立了基于集合覆盖的有容量和时间限制的选址 分配系统的非线性规划模型,按照模型决策空间所具有的特殊结构,设计了基于遗传和粒子群算法(GA PSO)的启发式算法.用大量的数据作为算例对模型进行了数值演算.结果表明,模型实用、算法有效.
关键词:
协同库存;选址 分配系统; 时间容量限制; 启发式算法
中图分类号: F 27
文献标志码: A  相似文献   

5.
借助于Duhois和Prade所定义的LR模糊数的近似乘法算子,运用广义逆矩阵A-l,A+,讨论了广义完全模糊线性系统(A)(⊕)(x)=(b)的解.首先,扩充了LR模糊数的定义;然后对广义完全模糊线性系统,讨论了其最小二乘解、最小二乘解的通解和极小最小二乘解;最后给出了具体算例.  相似文献   

6.
求解运输问题的一种新算法   总被引:1,自引:0,他引:1  
货物从生产商到销售商的分配问题称为运输问题(Transportation Problem),它是一类典型的线性规划问题,在现实中具有极其广泛的应用.如:选址问题、分派问题、生产计划与库存管理等.本文在传统的表上作业法的基础上引申得到了一种新算法.其主要思想是将最小元素法与指派问题的匈牙利解法巧妙地结合起来,通过对分配数以及0元素的讨论,一次性的得到最优解,从而避开了先确定初始解,再通过检验来确定最优解的复杂过程.该算法的优点在于计算过程容易掌握、计算量相对于原来算法比较简单.最后给出应用算例.  相似文献   

7.
针对遗传算法易早熟收敛和易产生大量不可行解的问题,提出了一种基于改进的克隆遗传算法(CGA)的配电网重构方法.该方法对克隆遗传算法进行了3点改进:通过简化网络结构,缩短了算法中染色体的长度;采用基于环路的编码方式,避免了产生大量不可行解;改进克隆遗传算法的选择算子、基因移位和突变操作,克服了早熟收敛的问题,提高了算法的收敛速度.本文以网损最小为优化目标对算例进行了重构,同时与基于遗传算法及粒子群算法的配电网重构进行了比较,算例结果表明:改进的CGA具有较高的寻优性能,应用于配电网中可以起到减小网损的作用.  相似文献   

8.
提出了一种基于贪心启发式的计算方法,可以在多项式时间复杂度内获得DUDC问题的近似最优解.首先生成了可替代二维平面的离散单元格,在每一单元格中心建立能够覆盖一定数量目标点的替代集,使用贪心算法确定替代集的最小组合方式,实现了对目标点的全覆盖.基于每个子集内所包含的点的具体位置,计算了其最小覆盖圆.最小覆盖圆的中心视为选址位置.基于具体案例证明了算法的有效性.讨论了该算法的影响因素,分析了时间复杂度以及近似度比率.  相似文献   

9.
基于免疫克隆选择优化算法的地下矿山配矿   总被引:2,自引:0,他引:2  
建立了基于免疫克隆选择算法地下矿山配矿的数学模型.以国内某地下锌矿实际生产为背景,使用Java编制相应的免疫克隆选择算法优化软件进行优化解算,将解算结果与该矿的生产计划指标和模糊优化算法解算结果进行对比验证.结果表明免疫克隆选择优化算法在地下矿山优化配矿领域的应用是可行的.  相似文献   

10.
硬件增强角速率圆锥优化算法的姿态解算精度分析及改进   总被引:1,自引:0,他引:1  
在分析传统硬件增强角速率圆锥优化算法姿态解算精度的基础上,提出了一种改进的算法,对传统算法中的周期分量进行了二次优化.首先通过分析传统算法的各轴分量相对于旋转矢量变化量的真值以及理想值的误差来确定算法的姿态解算精度,然后根据经典圆锥运动建立二次优化的误差准则并推导了相应的二次优化系数,最后在不同的经典圆锥运动环境下对传统算法以及改进算法的姿态解算精度进行仿真对比.结果表明,对传统算法的姿态解算精度的分析是正确合理的,而且只需采用改进的三子样算法就可以获得与根据理想值得到的结果几乎完全一致的姿态解算精度.  相似文献   

11.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

12.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

13.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

14.
Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with  相似文献   

15.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

16.
17.
The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.  相似文献   

18.
R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).  相似文献   

19.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

20.
The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.  相似文献   

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