Inventory model for an inventory system with time-varying demand rate

The standard inventory problems of the multi-period have been modeled under different situations. Specifically we have considered the demand subjects of a continuous distribution and a discrete distribution, and whether the demand of each period is unchanged or not. A method to get an economic order quantity in inventory systems with discrete and unchanged demand was presented in a previous paper, and this method has been generalized to an inventory model with varying continuous demand. However, it was not achieved due to there being many classified cases in the general situations. In this article the above method is discussed in the case discrete demand to determine whether it increases or decreases from period to period. A theoretical method is presented by using previous results and some examples are given which suggest how the concept can handle on inventory system. In order to make the decision, an algorithm is also presented under some conditions, and examples are shown by using the computer software program, Mathematica, which helps to explain the findings. In general cases, we view the optimal policy in the inventory problems in only a few periods.     

A world trade model based on comparative advantage with m regions,n goods,and k factors

This paper describes the World Trade Model, a linear program that determines world prices, scarcity rents, and international trade flows based on comparative advantage in a world economy with m regions, n goods, and k factors. The new model generalizes the World Model of Leontief et al. (1977) in ways that make it particularly useful for analyzing scenarios about sustainable development. Major properties of the model are demonstrated, and sources of the gains from trade are identified for the world as a whole and for individual regions. Illustrative results are reported for a 10-region, 8-good, 3-factor model of the world economy.     

考虑批量订货的易腐农产品配送中心选址方法

为提高物流管理绩效、降低物流运作成本,考虑到配送中心的批量订货和作业能力限制,建立了易腐农产品配送中心选址问题的0-1整数非线性规划模型,并利用Lingo 9.0软件进行了模型求解.利用该模型可以确定配送中心的位置和各配送中心与零售店之间的配送关系,并可得到配送中心的订货周期和订货批量.最后,通过算例验证了模型的有效性.     

建设城市物流园区战略探析——以毕节市七星关区为例

在分析以物流园区为核心的物流发展趋势及其功能的基础上,结合实证分析,对城市物流园区发展规划展开战略研究.从功能设计、投资经营模式、主体培育发展、建立物流信息平台等方面展开分析,对毕节市七星关区物流园区的建设进行战略探析.     

数控加工中宏程序的应用

手工编程中应用宏程序不仅可以减少程序量也能编制复杂零件程序,可以起到事半功倍的效果.用户宏功能是用户提高数控机床性能的一种特珠功能,在相类似工件的加工中巧用宏程序将起到事半功倍的效果.     

基于网络单纯形法的冷链物流运输优化研究

冷链物流运输的特殊性使得从事冷链物流运输的企业支付了高额的成本,针对目前的现实情况,从降低冷链物流运输过程中成本的角度,对冷链物流运输问题进行优化,使用线性规划的方法,对冷链物流运输过程中空箱的进出、中转构建模型,结合所构建的模型,给出相关的算例,根据给定的数据计算出结果验证了所构建模型的合理性,使冷链物流运输货物成本最低问题的研究又多了一种新的定量分析的方法。     

供应链中数学模型及其算法研究

通过对供应链研究现状的分析,进而对供应链中数学模型进行了深入的探讨。论文采用双层规划模型描述了提出的问题,其中上层规划模型是从生产商的角度出发,使得生产成本最小化;而下层规划模型则是从供应商的角度出发,使得收益最大化。文中对双层规划模型设计了相应的模拟退火算法进行求解。算例结果表明,模型和算法都是有效的,从而为供应链中角色决策提供支持。     

数字通信遥视系统数据实时传输技术研究

文章讨论了基于数据实时传输技术的数字通信遥视系统(DigitalRemoteSystem)传输模块的具体实现,并从整体嵌入式系统设计的方法着手,论述了嵌入式系统设计的软硬件设计流程和数字遥视系统的传输模块的软硬件详细设计,另外还提出了以Motorola的微通信控制器MPC850为核心的硬件设计,以及以RTOSNucle-usPlus为基础的实时应用软件设计的方案。     

Weekly scheduling models for traveling therapists

This paper presents a series of models that can be used to find weekly schedules for therapists who provide ongoing treatment to patients throughout a geographical region. In all cases, patient-appointment times and visit days are known prior to the beginning of the planning horizon. Variations in the models include single vs. multiple home bases, homogeneous vs. heterogeneous therapists, lunch break requirements, and a nonlinear cost structure for mileage reimbursement and overtime. The single home base and homogeneous therapist cases proved to be easy to solve and so were not thoroughly investigated. This left two cases of interest: the first included only lunch breaks while the second added nonlinear overtime and mileage reimbursement costs. For the first case, 40 data sets were solved, each consisting of either 15 or 20 therapists and between roughly 300 and 540 patient visits over five days. For each instance, we were able to obtain the minimum cost of providing residential healthcare services using a commercial solver. The results showed that CPU time increases more rapidly than total cost as the total number of visits grows. For the second case, which was much more difficult, it was necessary to develop heuristics to find good solutions quickly. Results for 5- through 20-therapist instances are presented and compared to the linear programming relaxation lower bounds. In the first of two parametric analyses, the tradeoff between the number of therapists on staff and the cost of providing service was examined. In the second, a similar tradeoff was explored between cost can the number of home bases used by the therapists.     

关于节水型园林设计规划的思路构架和分析

随着我国社会主义现代化建设和城市化建设进程不断加快,人们对自然资源的过渡开发与利用,带来了诸多环境问题。为提高我国园林生态水平,相关部门应认识到我国园林用水的现状,并积极开发和设计节水型园林,大力推广节水灌溉,优化各类植物配置,加强园林人力资源管理,提高人们的节水意识,从而为建设节水型园林奠定坚实的基础。