Evaluation of the role of waste in a truck manufacturing line using simulation

In their never-ending search to improve manufacturing performance, companies try to eliminate all sources of waste. In this paper, we describe how the effects of the elimination of waste on performance measures such as lead time and overtime costs can be estimated using logistical simulation. This is illustrated using a real-life case study that was conducted in the repair department of a truck cabin factory. In this department, cabs are controlled and if necessary repaired. The first part of the paper describes how bottlenecks were determined for both the present layout and for a proposed layout change. This turned out to be difficult, as several product flows intertwine. Modelling was made complex by these interactions, as they caused deadlock phenomena. The second part of the paper represents a sensitivity analysis, which evaluates the effects of different types of waste, such as machine breakdowns, inadequate buffer size and production time variance.     

Pathways to childhood depressive symptoms: The role of social, cognitive, and genetic risk factors.

Childhood depressive conditions have been explored from multiple theoretical approaches but with few empirical attempts to address the interrelationships among these different domains and their combined effects. In the present study, the authors examined different pathways through which social, cognitive, and genetic risk factors may be expressed to influence depressive symptoms in 300 pairs of child twins from a longitudinal study. Path analysis supported several indirect routes. First, risks associated with living in a step- or single-parent family and punitive parenting did not directly influence depressive outcome but were instead mediated through maternal depressive symptoms and child negative attributional style. Second, the effects of negative attributional style on depressive outcome were greatly exacerbated in the presence of precipitating negative life events. Third, independent of these social and cognitive risk mechanisms, modest genetic effects were also implicated in symptoms, with some indication that these risks are expressed through exposure to negative stressors. Together, these routes accounted for approximately 13% of total phenotypic variance in depressive symptoms. Theoretical and analytical implications of these results are discussed in the context of several design-related caveats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

网管日记

今天老板让我把网吧里的CS全删除了,我忙活了一晚上.至于为什么要删除CS呢?其实起因是这样的.今天公安局的临时检查,之前已经得到过风声,一连几天我都当了清道夫,把18岁以下的任何生物统统赶出了网吧.所以远远的看着警察叔叔们来时,我和老板都没什么紧张的.     

Extension and partial optimization of a modified Smith predictor and controller for unstable processes with time delay

Extension and partial parameter optimization are applied to a modified Smith predictor and controller, designed by de Paor( 1985) for a class of unstable processes having transfer functions of the form k₁A exp(—sT)/B, where A is a monic, Hurwitz polynomial of degree (n — l) and the nth degree monic polynomial B has a single right half-plane root at s=λ It is found that for l = 1,2,3 asymptotic stability can be achieved for λ T> 1, which more than doubles the best result obtained earlier. For a specific process, responses are compared with those obtained using the optimum stability PI controller of de Paor and O'Malley (1989). The advantages of the optimized, modified predictor in terms of tightness of control and faster settling time are highlighted     

基于MPLS的IPTV QoS研究

MPLS(Multi-Protocol Label Switch)和服务质量(QoS)是与下一代网络相关的重要技术.作者首先介绍了QoS的两种模型:综合服务(IntServ)和区分服务(DiffServ)模型,然后描述了基于MPLS网络的DiffServ模型的实现.文中介绍了网络电视(IPTV)系统的组成和存在的问题,并提出了一个基于MPLS的QoS区分服务模型改进方案.     

纺织专家系统中知识与知识库的应用

专家系统是人工智能的一个分支，是一种模拟专家决策能力的计算机系统，知识库是系统的重要组成部分，是系统的核心。本文结合纺织工艺设计及管理专家系统介绍了基于知识的专家系统的概念和结构，对系统中知识的获取、存储方式予以说明．并对其知识的表示方法加以阐述。     

Continuous mobile robot localization by using structured light and a geometric map

A mobile robot needs to know its position and orientation with accuracy in order to decide the control actions that permit it to finish the entrusted tasks successfully. To obtain this information, dead-reckoning-based systems have been used, and more recently inertial navigation systems. However, these systems have some errors that grow bigger as time goes by, therefore a moment comes when the information provided is useless. Because of this, there should be a periodic process that updates the robot position and orientation of the vehicle. The process to determine the robot position and orientation by using information originated from the external sensors is defined as the mobile robot relocalization. It is obvious that the greater the frequency of this process, the better the knowledge of its position the robot will have, and therefore its movements will be better directed to the point it must reach. The algorithm to achieve this can be classified in two large groups: relocalization through an a priori map of the environment and relocalization through the detection of landmarks present in that environment. The algorithm presented in the paper belongs to the first case. The sensor used is a combination of a laser diode and a CCD camera. The sensorial information is modelled as straight lines that will be matched with an a priori map of the environment. With this, the position of the mobile robot is estimated. The matching process is accomplished within an extended Kalman filter. The algorithm is able to work in real time, and it actualizes the position of the robot in a continuous way.     

APPLICATION OF A PERTURBATION THEORY FOR EVALUATION ALGORITHMS FOR IDENTIFICATION OF A CONTINUOUS PLANT FROM DISCRETE DATA

Abstract

A perturbation theory for evaluation algorithms of arithmetic expressions is applied to the generalized least-squares identification of the continuous parameters by using nonperiodic discrete data. The sampling instants are distributed in such a way that a sequence of the elemental arithmetic expressions of the identification algorithm are suboptimized according to bang-bang rules on the extrema of appropriate variation intervals. The weighting scalars in the generalized least-squares method are updated with the same purpose.