基于(s,S)库存策略的分销系统最优分配问题

分销系统的运营成本不仅与所采取的库存控制策略有关,也与配送中心在货源不足时的分配策略有关。该文讨论单品种、单配送中心多销售点、周期观察、随机需求的两级分销系统。配送中心及各销售点都采用(s,S)库存控制策略,顾客对销售点的需求过程服从Po isson过程。在给定配送中心向销售点分配策略的情况下,系统的状态转移形成一个离散时间的M arkov链,因此系统的最优分配策略问题是一个M arkov决策问题。采用策略迭代或值迭代的办法,可以求解系统的最优库存分配策略。数值算例表明,采用最优库存分配策略能显著降低系统的成本。     

海洋酸化与升温对浮游植物种群的影响研究综述

浮游植物是海洋生态系统物质和能量的基础,浮游植物的光合作用及群落结构决定了海洋生态系统的生产力及其服务功能.大气CO2浓度升高导致的海洋酸化和全球变暖等复杂的环境变化同时作用于海洋浮游植物,对其生长、代谢以及种群演替将产生深远影响.本文主要综述海洋酸化和升温单一以及耦合作用下对浮游植物的生长、光合作用和群落结构的影响,...     

从诉讼模式看我国刑事审判方式改革

我国现行庭审制度还存在若干问题，需借鉴现代刑事诉讼模式及其发展趋势进行改革，刑事审判方式改革的方向和路径应当是以职权主义为主、当事入主义为辅的审判模式——混合审。     

液固两相流体冲刷腐蚀的协同作用

金属材料在液固两相流中受到冲刷、腐蚀的协同作用,会加速材料流失,引发安全事故。本文对冲刷、腐蚀协同作用现状、机理、影响因素等进行分析。结果表明:冲刷作用物理的剥离腐蚀产物膜,致使金属暴露于腐蚀介质中,加速腐蚀;而腐蚀的产生会使金属表面松动,有利于冲刷剥落过程,两者互相促进,共同作用于金属表面,造成结构的腐蚀失效。     

Analysis of a New Type of Production System

Previous work studied a production system including multiple stations (or workshops) consisting of an entry station, a set of workstations, an exit station, and a central station, which could be arranged in any configuration. The central station was introduced into the production system to relax the environment. In this paper, the central station is eliminated. The entry station and all workstations have limited local buffers. A workstation can choose either a buffer or a kanban mechanism to control its work-in-process (WIP). The production system was modeled as a queueing network with blocking in a general configuration. A symmetrical decomposition approach was developed to analyze the production system. The simulation result shows that the decomposition approach works well. Comparison of the new production systems with modified production systems having a common buffer shows that the key for implementing just-in-time production systems is to reduce the uncertainty.