Production planning in semiconductor wafer fab considering variable cycle times

Recent research in the semiconductor manufacturing area has addressed some industrial engineering and operations research applications to solve the challenging production planning and scheduling problems. Relative to the other industries, the number of practical production management techniques and supporting software in the semiconductor industry is limited. The conventional models proposed use fixed or averaged cycle time and yield to get the results. However, in the actual wafer fabs, cycle time is spread widely and skewed due to the large variations in the operations. Therefore, the use of averaged cycle time and yield makes significant differences between the plan and the actual shop performance. Thus, we focus on the production planning problem in the wafer fabrication (“fab”), introducing a planning methodology that explicitly considers the variable cycle time and the shop status. We also evaluate some different types of input policies.     

高原低气压环境对人体热舒适性影响的研究初探

模拟了高原低气压环境,以问卷调查的方式进行了低气压环境下人体热舒适的实验研究,为低气压地区舒适性空调的设计提供了参考.     

指数反余弦函数变换灰色预测模型

将指数反余弦函数变换aarccosx(a≥e)应用到粮食产量数据的实证分析中,可变参数a取值可以提高GM(1,1)模型的预测精度.     

NEURAL NETWORK-BASED PREDICTIVE CONTROL FOR MULTIVARIABLE PROCESSES

In this paper, the systematic derivations of setting up a nonlinear model predictive control based on the neural network are presented. This extends our previous work (Chen, 1998) into a multivariable system to explore the characteristics of the design. There are two stages for the development of nonlinear neural network predictive control: a neural network model and a control design. In the neural network model design, a parallel multiple-input, single-output neural network autoregressive with a model of exogenous inputs (NNARX) is proposed for multistep ahead predictions. In control design, the controller with extended control horizon is developed. The Levenberg-Marquardt algorithm is applied to training the NNARX model. Also, the sequential quadratic programming is used to search for the optimal manipulated inputs. The gradient of the objective function and constraints that require computation of Jacobian matrices are completely derived for optimization calculation. To demonstrate the control ability of MIMO cases, the proposed method is applied through two nonlinear simulation problems.     

海洋放线菌发酵产物的乙酰胆碱酯酶抑制活性研究

利用海洋高氏一号培养基对36株海洋放线菌进行培养。发酵处理4 d天后发酵液用乙酸乙酯进行提取。用Ellman法检测发酵产物的乙酰胆碱酯酶抑制活性。21株海洋放线菌的发酵产物对乙酰胆碱酯酶具有显著的抑制活性,其中,放线菌LYG22对乙酰胆碱酯酶的抑制活性最好,对AChE的抑制率达到48.58%。     

李祯祥的"厚道外交"——访本刊2001年十大新闻人物李祯祥

北京金隅嘉业房地产开发公司:年开发规模近100万平方米,竣工30多万平方米,开发住宅小区17个,还有腾达大厦、金隅大厦等现代化的写字楼;年销售收入进入全国500强房地产企业前50位,主营收入名列北京市房地产企业前10名. 建材圈里人无不羡慕:北京金隅的房地产真是越做越大了,位居北京,地皮又多,天时地利啊! 房地产界人士惊叹:一家搞建材的企业居然能在众多的房地产公司中脱颖而出,坐稳前几名,真是不可思议!     

硕果累累催人奋进任重道远再展宏图——全国墙体材料革新成就展览会暨第一届中国国际新型墙体材料及设备展览会巡礼

秋风送爽，景色宜人。9月24-27日．由国家发改委、国土资源部、建设部、农业部、北京市政府支持．各省、自治区、直辖市墙改办协办，中国建材联合会、国家建材展贸中心联合主办的“全国墙体材料革新成就展览会暨第一届中国国际新型墙体材料及设备展览会”在北京国际展览中心隆重举行。[第一段]     

三峡溢流坝段几个温度应力问题的计算与分析

本文对三峡溢流坝段通仓浇筑与不同分缝分块、孔口、溢流面的温度应力进行了全面分析,并在此基础上提出了三峡溢流坝段施工设计中需要考虑的问题。这些问题具有代表性,也可作三峡其它坝段以及类似工程进行施工方案、温控设计时参考。     

2000年我国正丁醇产需分析

综述了正丁醇的国内外生产和消费现状,分析２０００年正丁醇的生产和消费能力,表明正丁醇在我国市场前景看好。