现代操作系统中的多进程技术实及其应用

进程作为资源的拥有者和操作系统中被调度的基本单元,是现代操作系统的重要概念;掌握多进程编程并应用于实际,可以加深对操作系统的认识,是每个优秀程序员必备的素质。本文通过基于RPC的Client/Server进程应用程序的编写,讲述了实现进程并发的分布式计算。     

Application of a neural network to improve an automated thermoplastic tow-placement process

This study demonstrates the use of an on-line neural network to calculate process set points for PID controllers in a manufacturing process such as the automated thermoplastic tow-placement (ATP) technique. The set points are computed by the neural network so that the throughput is near maximum and a desired minimum quality is maintained. A novel neural network predictive scheme is developed to enable performance over a wide range of processing inputs. Process history can greatly affect the final part quality and, therefore, is an integral part of the method for determining the set points. The system is first trained and tested in simulation and then validated for the highly non-linear ATP process resulting in significantly improved process operation. The developed approach is applicable to many other manufacturing processes where process simulations exist and conventional control techniques are lacking.     

Dynamic process fault monitoring based on neural network and PCA

A newly developed method, NNPCA, integrates two data driven techniques, neural network (NN) and principal component analysis (PCA), for process monitoring. NN is used to summarize the operating process information into a nonlinear dynamic mathematical model. Chemical dynamic processes are so complex that they are presently ahead of theoretical methods from a fundamental physical standpoint. NN functions as the nonlinear dynamic operator to remove processes' nonlinear and dynamic characteristics. PCA is employed to generate simple monitoring charts based on the multivariable residuals derived from the difference between the process measurements and the neural network prediction. It can evaluate the current performance of the process. Examples from the recent monitoring practice in the industry and the large-scale system in the Tennessee Eastman process problem are presented to help the reader delve into the matter.     

The average-case identifiability and controllability of large scale systems

Needs for increased product quality, reduced pollution, and reduced energy and material consumption are driving enhanced process integration. This increases the number of manipulated and measured variables required by the control system to achieve its objectives. This paper addresses the question of whether processes tend to become increasingly more difficult to identify and control as the process dimension increases. Tools and results of multivariable statistics are used to show that, under a variety of assumed distributions on the elements, square processes of higher dimension tend to be more difficult to identify and control, whereas the expected controllability and identifiability of nonsquare processes depends on the relative numbers of measured and manipulated variables. These results suggest that the procedure of simplifying the control problem so that only a square process is considered is a poor practice for large scale systems.     

Design of a nonlinear distributed parameter observer for a pressure swing adsorption plant

As an integral part of an advanced process monitoring and control scheme, the reconstruction of the spatial concentration, temperature, and pressure profiles of an oxygen production plant is studied by the design of a nonlinear observer with distributed parameters. The considered pressure swing adsorption process consists of two adsorbers and each adsorber of two layers. The design of the nonlinear observer with distributed parameters is illustrated for a single adsorption layer, which is described by six quasilinear partial differential equations and related boundary conditions. Thereby, a late lumping approach is used in order to design the injected correction functions in the observer equations and to introduce tuning parameters with a physical meaning. The observer is extended to the entire adsorption process and its simulation shows an excellent convergence behavior.     

基于集成产品与过程建模的设计进程管理

本文研究虚拟原与设计过程模型的集成问题以及基于该集成模型的设计进程管理,首先提出基于虚拟原型的设计过程模型生成,然后讨论基于虚拟原型和设计过程集成建模的、面向并行工程的设计过程管理、最后重点讨论通过初步设计信息交换加快设计进程的问题。     

隐含约束的识别与规整方法

提出了隐含约束的识别与规整方法,并利用图来描述图形实体的相互约束。用动态迭代法来处理动边变动对已有约束的影响。系统记录各咬合点,全局遍历结构约束图中的咬合点,局部规整各动边。用户可根据不同图形,设置适当的规整优先级及全局误差,增加了灵活性。     

数字仿真技术在继电保护中的应用及其展望

叙述用于测试继电保护装置的SＪ和DSF双侧电源数字静模仿真器，分析仿 真的电力系统模型、算法和软硬件的实现，展望数字仿真技术应用前景。     

活性二氧化锰的研制与分析

本文对制备活性二氧化锰的工艺条件进行了探索,并使用DTA、X-衍射等方法分析讨论了不同制备工艺对AMD结构的影响。     

二氧化锰活化工艺探索

本文以“EMD电解液+少量NaClO_3和含铝聚氯化物”为介质的活化体系为基础,试验并确定活化MnO_2的工艺条件。