同兴垃圾发电厂DCS控制系统

重庆同兴垃圾发电厂采用的是德国马丁公司(原法国阿尔斯通公司)的逆推式炉排焚烧技术。本文叙述了焚烧技术的工艺流程、DCS控制系统的硬件构成及功能。以全厂集中操作与各工段分散控制相结合的系统运行模式,实现了垃圾焚烧发电厂整体生产过程的监控和低成本运行,提高了垃圾焚烧发电机组的自动化和管理水平。     

基于ADAM5510的新型失重秤设计

通过对老式失重秤工作原理的介绍,分析了老式失重秤在流量测量过程中的误差来源,提出一种基于ADAM5510为控制器的新型失重秤的方法。并阐述了其工作原理及控制方案。实践证明,对于提高失重秤的称重精度和计量精度效果明显。     

Liquid-Gas Two-Phase Flow Simulation in Mold Filling Process with Level Set Method

Air entrapped in liquid metal during the mold filling process seriously affects the casting quality, thus it is important to track its behavior in the mold cavity. A liquid-gas two-phase flow model is developed to describe the mold filling process and predict the air entrapment defect. The model is based on the combination of SOLA and Level Set Method. The pressure and velocity fields are calculated by SOLA,and the interface movement is simulated by Level Set method as the most common interface tracking met...     

面向对象的空中交通流量管理系统建模与仿真

针对我国空中交通流量日益增长的空中交通管理的现状,研究建立空中交通流量管理系统,通过监视一定范围的空中交通状况,进行交通流量的预测和控制。面向对象理论已成为复杂系统设计和分析中一种必不可缺的工具,这种技术为交通流量管理系统的研究提供了重要的平台。利用抽象、分类、封装、继承、关联、消息通讯等概念建立的交通流量管理系统的模型结构清晰,更好的反映了系统的工作流程和各模块间的交互关系。     

膏体推进剂变截面管道流动的数值仿真

应用Ostwald幂律本构关系.分析了膏体推进剂在收缩管道内的稳态流动特性,获得了管内的流速、压力的分布.以收缩角θ(半锥角)为对象.研究了收缩角对流场的影响,得到了单位长度管道压力差与收缩角的关系.根据仿真结果发现,收缩角对压力分布影响较大,在管道渐变处,收缩角越大,压力分布越复杂.而收缩角对流场速度分布影响不大.收缩角对输送能量损耗影响很小,在设计膏体推进剂输送功率时可以忽略这一参数,将收缩过渡段当成细管道计算,处理是安全的.为了避免膏体推进剂流动时产生"死区",应该采用小收缩角管道.     

基于二进小波变换的主动轮廓模型

针对传统的主动轮廓模型对噪声敏感的缺陷,在推广梯度矢量流的基础上,提出了基于二进小波变换的改进外力场的计算方法.通过综合利用图像小波分解的高频信息,迭代计算获得其外力场,使蛇在图像的多尺度空间中搜索目标轮廓.针对蛇模型对初始轮廓的依赖性问题,给出了在一维最大熵阈值分割后的图像上获取初始轮廓点的方法,减少了人工的干预,加快了蛇的收敛速度和效果.实验结果表明该模型能有效地排除噪声的干扰,搜索凹陷轮廓,而且对脆弱轮廓有很好的逼近能力.     

HiTM：一种高速流量采集方法

针对目前高速流量采集存在的问题,对被采样的数据使用Hash算法压缩流ID长度,并在本文提出了一种高速流量采集方法HiTM。HiTM多级过滤器前增加一个高速缓存,减少流ID处理时的访存次数和多级过滤器的报文处理数目,提高处理的效率。理论和实验表明,HiTM与目前的经典算法相比具有错误率低、访存次数少、统计速度快的特点,可以应 应用于高速网络流量采集。同时,算法的内存需求可以预先给定,在网络规模扩大时,算法的精度也可以得到很好的控制。     

Network flow and 2-satisfiability

We present two algorithms for network flow on networks with infinite capacities and finite integer supplies and demands. The first algorithm runs inO(mK) time on networks withm edges, whereK=O(m²/log⁴ m) is the value of the optimal flow, and can also be applied to the capacitated case by lettingK be the sum of thefinite capacities alone. The second algorithm runs inO(wm logK) time for arbitraryK, where w is a new parameter, thewidth of the network. These algorithms as well as other uses of the notion of width lead to results for several questions on the 2-satisfiability problem: minimizing the weight of a solution, finding the transitive closure, recognizing partial solutions, enumerating all solutions. The results have applications to stable matching, wherew corresponds to the number of people andm to the instance size (usuallym w²).     

Algorithms and complexity analysis for some flow problems

Several network-flow problems with additional constraints are considered. They are all special cases of the linear-programming problem and are shown to be -complete. It is shown that the existence of a strongly polynomial-time algorithm for any of these problems implies the existence of such an algorithm for the general linear-programming problem. On the positive side, strongly polynomial algorithms for some parametric flow problems are given, when the number of parameters is fixed. These algorithms are applicable to constrained flow problems when the number of additional constraints is fixed.Work on the paper was done while at Stanford University and IBM Almaden Research Center. This research was partially supported by NSF PYI Grant CCR-8858097.     

Recent development and applications of an optical method for measurements of thermophysical properties

The experimental determination of thermophysical properties has been greatly improved by the introduction of laser technology. The laser beam is used for sensing and also for heating (or exciting) the specimen. The advantage of using a laser beam is most strongly felt in the measurement of the thermal conductivity or the thermal diffusivity, which are some of the most difficult properties to measure. Interesting features of new techniques for investigating various aspects of thermal conductivity in fluids and solids are reviewed. An optical method, the so-called forced Rayleigh scattering method, or the laser-induced optical-grating method, has been developed and used extensively by the present author's group. The method is a high-speed remote-sensing method which can also quantitatively detect anisotropy, namely, direction dependence of heat conduction in the material. It was used for determination of the thermal diffusivity and its anisotropic behavior for high-temperature materials such as molten salts, liquid crystals, extended polymer samples, and flowing polymer melts under shear. Interesting applications of the method were demonstrated also for thermal diffusivity mapping and microscale measurement.Invited paper presented at the Twelfth symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.