Hierarchical production control for a flow shop with dynamic setup changes and random machine breakdowns

In this paper, we study a manufacturing system consisting of two machines separated by two intermediate buffers, and capable of producing two different products. Each product requires a constant processing time on each of the machines. Each machine requires a constant non-negligible setup change time from one product to the other. The demand rate for each product is considered to be piecewise constant. Each machine undergoes failure and repair. The time-to-failure and time-to-repair are exponentially distributed random variables. The setup change and processing operations are resumable. We model our system as a continuous time, continuous flow process. An optimal control problem is formulated for the system to minimize the total expected discounted cost over an infinite horizon. To determine the optimal control policy structure, a discrete version of the problem is solved numerically using a dynamic programming formulation with a piecewise linear penalty function. A real-time control algorithm is then developed with the objective of maintaining low work-in-process inventory and keeping the production close to the demand. The algorithm uses a hierarchical control structure to generate the loading times for each product on each machine in real time and to respond to random disruptions in the system. The system is simulated using this algorithm to study its performance. The performance of the algorithm is also compared to alternative policies.     

换热网络数值模拟稳定性分析

换热网络的数值模拟在换热网络的定量分析中起着重要作用。但在模拟计算中,有时表现出数值稳定性差。提高数值稳定性的方法,目前多通过改善算法来实现。本文通过对换热网络数值模拟的误差分析,提出了误差放大因子的概念,并依此选择迭代变量。通过对迭代变量的选择,达到提高换热网络数值模拟稳定性的目的。     

New concept of surface modification to LiCoO2

As the continuance of our series study on LiCoO₂ surface modification, the complicated traditional surface coating method is replaced with simple addition of amorphous YPO₄ and Al₂O₃ in commercial LiCoO₂ or in commercial electrolyte based on our understanding to the improvement mechanism of surface modification. Comprehensive studies by X-ray photoelectron spectroscopy (XPS), gas chromatography and mass spectroscopy (GC–MS), inductively coupled plasma (ICP) and Fourier transformed infrared (FTIR) indicate that the products of spontaneous reaction between the additive and the LiPF₆ based electrolyte are responsible for the performance improvements.     

变异函数在进间砂体预测中的应用

应用变异函数探讨了砂体的定量预测问题。通过对北二东密井网试验区不同类型砂体，不同井网密和岩厚度的预测，检验了此方法的精度（为70％左右），在原方法的基础上，通过对预报精度的分析并结合精度地质研究进一步完善了该方法，提出二次建模法并应用于北二东西块聚驱井的砂岩厚度预测中，预测精度可提高5％以上，从而说明应用变异函数研究砂体的定量预测问题具有可借鉴性，可以为今后新井调整厚度的预测及砂体描述提供依据。     

微光CCD摄像器件综合特性的分析与比较

ＣＣＤ的优良特性使其在微光电视技术领域得到了广泛运用。本文对各种微光ＣＣＤ摄像器件的综合特性例如信噪比、探测率、动态范围与计数模式等进行了详细的研究与对比，并得出基本结论。     

液态烃球罐安全应用探讨

液态烃常温球罐储存技术相当成熟,但在实际应用方面仍然存在许多问题,影响安全储存。针对使用过程中所了解的一些具体做法进行了分析和探讨,对球罐的改造和设计提供了必要的参考。     

我国锦纶帘子布市场发展态势及对策

通过对我国当前帘布市场态势的分析和今后三年的需求预测，探讨了锦纶帘线的生产发展对策。认为“八五”期间，我国锦纶帘布市场将呈现供大于求的局面，在一段时期内，锦纶帘布仍将是主要的橡胶骨架材料，其占比例为７０％左右。预计１９９３～１９９５年，锦纶橡胶骨架材料的市场需求量分别为９．１６，１０．３７．１１．６９万ｔ。     

远洋山水居住区(西区)"九年一贯制"学校

远洋山水居住区（西区）的教育优势突出，在居住区的西南角规划设计了一所36班的“九年一贯制”示范学校。其中，小学部24班，初中部12班。该学校隶属于石景山教委，主要招生服务对象为远洋山水居住区（西区）和周边社区的居民。学校占地3.6ha，总建筑面积约23800m^2。