Spreadsheet Implementable Inventory Control for a Distribution Center

This paper develops and tests a simple procedure for establishing stocking rules for a multi-component distribution center that supplies spare parts for an equipment maintenance operation. Our basic formulation seeks to minimize inventory investment subject to constraints on average service level and replenishment frequency. We simplify this formulation by classifying parts according to a new ABC methodology and applying heuristics to the classical (Q,r) model that lead to closed-form expressions for the stocking parameters. Our numerical results show that: (1) the proposed ABC scheme does not introduce large errors provided that it is done in a manner that reflects the key parameters in the model, and (2) any of a number of simple reorder point heuristics can provide the basis for an effective spreadsheet implementable system for controlling inventory in a complex multi-component environment as long as the service level is checked against the exact formula.     

A note on the gradient of heat semigroup

A new representation for the gradient of heat semigroup on Riemannian manifold is given by using the integration by parts formula on Wiener space, which reflects in some sense the asymptotic property of Brownian motion.     

SF6气体间隙开关激光触发延迟的数值模拟

 建立了激光触发SF₆气体间隙开关的0维数值模型，数值计算结果与国内外实验进行了比较，计算的延迟时间与实验结果符合较好。在充气压力一定时，延迟时间随激光能量、工作电压比的增加而减小，并且延迟时间-工作电压比的曲线斜率也是随激光能量和工作电压比的增加而减小的。当激光能量一定时，延迟时间随充气压力的减小和电压的增加而减小, 并且不同充气压力的延迟时间随电压变化的曲线斜率是随电压的增加而减小的。但是，等电压压力比值情况下,延迟时间是随充气压力的增加而减小的。     

光学零件超精密加工机理及新技术

本文较全面阐述了光学零件超精密加工机理及新技术,反映了国外最新技术进展与水平。     

一种模拟转发器标校方法的研究

概述了卫星导航系统的时间同步问题和卫星导航的设备零值及其标校问题。阐述了模拟转发器标校的工作原理,在此基础上对模拟转发器标校的关键设计技术进行了分析,并针对卫星导航系统提出了基于模拟转发器标校技术的设备零值标校平台,该平台能适应多种卫星导航设备的零值标校。基于模拟转发器标校技术的标校平台能实现发射和接收设备零值的完全分离,并可方便地实现标校自动化。通过与绝对标校和基准差分法标校的比较,该标校平台用于卫星导航系统的设备零值标校具有独特优势。     

甚低频固态发射机功率器件分析

甚低频发射机用来给潜艇发信,功率达数百千瓦至数千千瓦,如今可以采用MOSFET和IGBT等固态器件作为大功率开关放大器,但选择MOSFET还是IGBT,设计人员需要做出选择。分析了这两类器件的开关特性及导通特性,比较了它们的工作特点,介绍了一种典型的大功率开关放大器应用电路,讨论了甚低频发射机在选择大功率放大器器件时应考虑的一些条件,如频率、电压、开关时间等。     

离子注入机中高压电源主电路工作频率的确定

离子注入机中高压直流稳压电源的主电路采用了脉宽调制式变换电路。本文从控制主要元器件的功耗入手，讨论如何选择变换器的工作频率和设计主要器件的参数，以确保电源的低功耗和高效率。     

Investigation of SOA-assisted Sagnac recirculating shift register switching characteristics

The switching characteristics of a Semiconductor Optical Amplifier (SOA)-assisted Sagnac recirculating shift register with an inverter are investigated by undertaking a numerical analysis that describes the dynamic gain response of the SOA to high speed and strong feedback optical pulses. The key performance parameters are identified and their role in the formation of the switching window is analyzed. The optimum values of these parameters are not unique and must be adapted to the specific all-optical shift register network application. For this reason, they must be properly selected and combined so as to ensure the satisfaction of the desired operating conditions. The technical restrictions that the derived values may impose on the state-of-the-art photonics technology are also discussed and efficient ways of overcoming them are proposed.     

分组交换中分组流的概率特性与输出排队

本文分析快速分组交换中分组流的概率特性与输出排队。在输入分组流为复合泊松流的假设之下，论证了复合泊松流在分组交换过程中的叠加性、分解性、泊松性、马尔柯夫性、输出与输入的不变性等。然后，将输出分组流转换为连续时间的马尔柯夫链，分析了输出分组流的概率特性，并得到了输出排队长分布和充满缓冲器的概率。     

高速大功率半导体开关RSD的di/dt耐量极限值

文章由等离子体双极漂移方程和临界预充电荷条件出发,得出高速大功率半导体开关RSD的di/dt耐量表达式。从外电路和器件结构本身两方面分析了RSD的di/dt耐量的影响因素,并提出了改善di/dt耐量的措施,测试结果证明了理论分析的正确性。