Solving the Problem of Forbidden States in Discrete Event Systems: A Novel Systematic Method for Reducing the Number of Control Places

This paper deals with the problem of forbidden states in Discrete Event Systems modelled by non‐safe Petri Nets. To avoid these states, some Generalized Mutual Exclusion Constraints can be assigned to them. These constraints limit the weight sum of tokens in some places and can be enforced on the system using control places. When the number of these constraints is large, a large number of control places should be added to the system. In this paper, a method is presented to assign the small number of constraints to forbidden states using some states which cover the forbidden states. So, a small number of control places are added to the system leading to obtaining a maximally permissive controller.     

长输管线变电所备用电源自动投入系统的改造

根据管道储运公司下属的各变电所目前的运行方式以及备用电源自动投入系统(以下简称“备自投”)的运行情况，指出了备自投使用中的不足之处，并通过增加对应断路器的辅助触点来完善备自投，使变电所运行更加可靠。     

改进的ESMD用于公共场所异常声音特征提取

由于公共场所异常声音的特殊性及背景噪声的复杂性,极点对称模态分解(ESMD)用于异常声音分解时,存在一些理论和技术上的缺陷。经分析认为公共场所异常声音为非线性、非平稳信号,背景噪声服从T分布。为此,提出改进的ESMD用于公共场所异常声音分解,得到有利于识别的特征。所提出方法的特点是将T分布噪声序列添加到具有背景噪声的异常声音信号中,以减小背景噪声对特征提取的影响;将模态分量的排列熵作为判定异常声音与背景噪声的准则,自适应筛选有效的模态分量;用对称中点插值法替代极值中点奇偶插值法,以缓解ESMD插值端点不明确带来的模态失真。在公共场所异常声音数据库上进行了相关实验。实验结果表明,所提出的方法与目前典型的时频信号处理方法相比,在提高公共场所异常声音分类识别率的同时,缩短异常声音的分解时间,是一种有效的公共场所异常声音特征提取方法。     

Petri网位置不变量的几何意义

引入了Ｐｅｔｒｉ网路增益及位置不变量并运算的概念，建立了路增益与位置不变量之间的联系以及路、基本圈与它们对应的位置不变量的关系，给出了Ｐｅｔｒｉ网图形运算与位置不变量运算之间的关系，证明了加权状态机位置不变量存在的充要条件，揭示了Ｐｅｔｒｉ网位置不变量的几何意义。     

一种复杂条件下的水电站厂房网架屋盖安装

水电站厂房屋盖网架施工,在周围无安装场地条件下,网架屋盖安装选择合理有效的高空散装法和网架移动法相结合的方案,克服工期紧迫,现场空间狭小,土建和机电安装多工种交叉作业的纷乱繁杂环境条件等诸多空间条件限制,采用合理的移动操作平台吊装和网架滑移拼装的方法,成功实施了网架及屋盖安装,为实现水电站扩建工程机组投产发电目标发挥了...     

Light aversion in mice depends on nonimage-forming irradiance detection.

Detection of light in the eye underlies image-forming vision, but also regulates adaptive responses in physiology and behavior. Typically these adaptive responses do not involve image-forming vision, but depend on a relatively absolute measure of brightness (nonimage-forming irradiance detection). The goal of this study was to further understand how image-forming vision and nonimage-forming irradiance detection contribute to the effects of light on behavior. Three light dependent behaviors were assessed in wild-type, Rpe65-/- and rd1 mice. In Rpe65-/- mice, nonimage-forming irradiance detection is severely attenuated, but rod based visual acuity is relatively preserved. In rd1 mice visual acuity is nonrecordable, but nonimage-forming responses are less severely attenuated than Rpe65-/-. Positive masking, an image-forming vision dependent increase in wheel running, was absent in rd1 and restricted to higher irradiances in Rpe65-/-. Negative masking, a suppression of wheel running sensitivity with nonimage-forming irradiance detection input, was increased in rd1, but reduced in Rpe65-/- mice. By contrast, light aversion, an avoidance of brightly lit areas, was abolished in both Rpe65-/- and rd1. This shows that image-forming vision is not sufficient for light aversion, suggesting nonimage-forming irradiance detection motivates this behavior. Further, the differing effects of disease suggest that negative masking and light aversion are distinct responses with specialized nonimage-forming irradiance detection pathways. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

带式输送机水平转弯装置在综掘工作面生产中的应用

阐述了DZ-B800×90型带式输送机转弯装置的结构组成及工作原理,介绍了其在综掘工作面生产中的应用情况,并分析了在生产中使用该装置后取得的效果。     

福州台江步行街人性化设计的调研与评价

通过福州台江步行街一期工程建设的实例分析,指出目前步行街人性化设计中存在的主要问题。并在“以人为本”思想的指导下,提出解决现存问题的设计要点,以期创造出公众真正需要的人性空间。     

北京日报报业集团新闻采编中心项目设计探讨

结合北京日报报业集团新闻采编中心所处地理位置及自身功能,针对该项目的设计难点,围绕净化与协调,极简与高效,人文化的公共空间三个设计原则进行了具体阐述,介绍了对该项目的整体设计构思,对类似项目设计具有一定指导意义。     

城市生态的自然回归——波特兰雨园

本文以波特兰雨园为案例,就城市景观作为城市环境不可或缺的重要部分,如何在迎合城市发展的过程中,真正化身为城市生态系统的一个有益环节,协调优化城市与自然的关系,营造丰富并具有深度的体验场所的问题展开分析。