一种免维护反冲洗过滤器及其控制系统

本文介绍了一种能实现反向冲洗的过滤器，对其结构及冲洗原理作了说明。装置利用一台可编程序控制器实行全自动控制，文中给出了控制系统的工作原理图及部分软件控制图。     

基于S7-300的层流过滤器反冲洗控制系统

本文介绍了一种由西门子S7-300的PLC作为主控制器,对6台高速层流过滤器进行循环反冲洗的控制系统,详细论述了其电控系统的软硬件结构,为工业水处理系统的层流过滤器提供了一种新的控制方法。     

聚合物采油用自动控制反冲洗过滤罐的研究

为了解决油田采油过程中存在的过滤罐滤料污染后反洗效果差致使过滤后水质参数越来越差的问题。本文介绍了一种新型聚合物采油用自动控制反冲洗过滤罐系统，该系统能够提高反洗效果，使过滤后的水质参数有了大幅度的提高。     

基于PLC控制的反冲洗过滤系统

为了解决工业企业中废水处理及回收再利用的难题,介绍一种基于PLC控制的反冲洗过滤系统。     

气水反冲洗滤池自控系统设计

在气水反冲洗V 型滤池设置适当的在线检测仪表,采用先进的PLC 自动控制系统,通过调节清水阀的开度保 证恒水位过滤过程。滤池反冲洗时,采用合适的冲洗方法(单水或气、水反冲)和冲洗强度,既能有效地冲去积泥,又能保存滤 料表面一定的生物膜,以保证后期过滤效果。     

油田联合站反冲洗系统实时监测与控制

文章介绍了油田联合站反冲洗系统实时监测与控制,包括系统的 结构和功能。     

PLC在水厂滤池自动反冲洗改造中的应用

本文主要讲述西门子S7-200、S7-300系列PLC在珠海市西区水厂滤池恒水位自动反冲洗系统控制改造实例中的应用。本案例,我们在水厂不改变水厂现有构筑物的前期下,结合水厂现有设备的实际运行情况因地制宜地设置了PLC控制程序,实现是对老水厂滤池反冲洗自动化控制改造较为成功的案例。     

变频调速技术在水厂滤池气水反冲洗系统运行中的应用

针对自来水厂滤池反冲洗系统中鼓风机、水泵运行存在的实际问题,提出了应用交流变频调速技术加以解决的方案.本文对该方案的实施及调试过程中遇到的一些问题进行了分析与探讨,并提出了相应的解决办法.     

基于PLC的层流过滤器控制系统

本文介绍了采用西门子S7-300的PLC对6台高速层流过滤器进行循环反冲洗的控制系统,给出了其系统配置、电控系统的软硬件结构。运行表明,该控制系统大大提高了工业水处理系统的稳定性、经济性,收到了满意的控制效果。     

多语言编程在高炉喷煤PLC控制系统中的应用

为了解决用梯形图语言编写顺序控制设备时所存在的编程复杂、理解困难等问题,引入PLC的顺序功能图来编程是一种非常有效的方法,该方法具有编程简单而且直观等特点。本文以某高炉喷煤系统单罐循环的控制为例,采用顺序功能图与梯形图、功能块图相结合的方法编写控制程序,与以往常用的梯形图、功能块图编程方法相比具有简单、直观、逻辑性强等特点,大大提高了编程的效率。     

C语言程序关键词序列表示法

提出C语言程序关键词序列表示法,以消除由于个性化编程所造成的代码的不同,以证明程序是相同的.     

A Generate-Test-Aggregate parallel programming library for systematic parallel programming

The Generate-Test-Aggregate (GTA for short) algorithm is modeled following a simple and straightforward programming pattern, for combinatorial problems. First, generate all candidates; second, test and filter out invalid ones; finally, aggregate valid ones to make the final result. These three processing steps can be specified by three building blocks namely, generator, tester, and aggregator. Despite the simplicity of algorithm design, implementing the GTA algorithm naively following the three processing steps, i.e., brute-force, will result in an exponential-cost computation, and thus it is impractical for processing large data. The theory of GTA illustrates that if the definitions of generator, tester, and aggregator satisfy certain conditions, an efficient (usually near-linear cost) MapReduce program can be automatically derived from the GTA algorithm.     

Designing checkers for programs that run in parallel

Program correctness for parallel programs is an even more problematic issue than for serial programs. We extend the theory of program result checking to parallel programs, and find general techniques for designing such result checkers that work for many basic problems in parallel computation. These result checkers are simple to program and are more efficient than the actual computation of the result. For example, sorting, multiplication, parity, the all-pairs shortest-path problem and majority all have constant depth result checkers, and the result checkers for all but the last problem use a linear number of processors. We show that there are P-complete problems (evaluating straight-line programs, linear programming) that have very fast, even constant depth, result checkers.This research was done while at the Computer Science Division, University of California, Berkeley, and the International Computer Science Institute, Berkeley, California. Supported in part by an IBM Graduate Fellowship and NSF Grant No. CCR 88-13632.     

并联有源电力滤波器控制方式研究

针对无损耗电阻器的并联有源电力滤波器，采用一种控制算法，可实时计算出开关阵列的导通时间，实现更精确的控制。仿真结果表明，该滤波器及控制算法具有良好的谐波补偿效果。     

Hurwitz testing sets for parallel polytopes of polynomials

In considering robustness of linear systems with uncertain paramenters, one is lead to consider simultaneous stability of families of polynomials. Efficient Hurwitz stability tests for polytopes of polynomials have earlier been developed using evaluations on the imaginary axis. This paper gives a stability criterion for parallel polytopes in terms of Hurwitz stability of a number of corners and edges. The ‘testing set’ of edges and corners depends entirely on the edge directions of the polytope, hence the results are particularly applicable in simultaneous analysis of several polytopes with equal edge directions.It follows as a consequence, that Kharitonov's four polynomial test for independent coefficient uncertainties is replaced by a test of 2q polynomials, when the stability region is a sector Ω = { e^iv | > 0, rπ/q < | v | ≤ π } and r/q is a rational number.     

An introduction to compilation issues for parallel machines

The exploitation of today's high-performance computer systems requires the effective use of parallelism in many forms and at numerous levels. This survey article discusses program analysis and restructuring techniques that target parallel architectures. We first describe various categories of architectures that are oriented toward parallel computation models: vector architectures, shared-memory multiprocessors, massively parallel machines, message-passing architectures, VLIWs, and multithreaded architectures. We then describe a variety of optimization techniques that can be applied to sequential programs to effectively utilize the vector and parallel processing units. After an overview of basic dependence analysis, we present restructuring transformations on DO loops targeted both to vectorization and to concurrent execution, interprocedural and pointer analysis, task scheduling, instruction-level parallelization, and compiler-assisted data placement. We conclude that although tremendous advances have been made in dependence theory and in the development of a toolkit of transformations, parallel systems are used most effectively when the programmer interacts in the optimization process.     

Eliminating recursion from combinatoric procedures

The problem of eliminating linear and binary recursion has received quite a deal of attention. Less has been given to the elimination of the more general form of recursion that arises in combinatorics. In this paper we extend earlier work and produce two pairs of equivalent schemata. The correspondences between these schemata and the classical combinatoral problems are given and two applied examples: topological sorting and the set covering problem, are discussed in detail.     

On the suboptimality of a parallel Kalman filter

A filtering scheme has been proposed in the literature that attempts to achieve a certain amount of parallelism in a discrete-time Kalman filter by forcing the measurement- and time-update levels of the filter to decouple whereby the two levels may be run in parallel. The authors use an error covariance analysis to prove that the proposed filter is suboptimal and is not, in fact, a Kalman filter     

Finding r-dominating sets and p-centers of trees in parallel

Let T=(V, E) be an edge-weighted tree with |V|=n vertices embedded in the Euclidean plane. Let IE denote the set of all points on the edges of T. Let X and Y be two subsets of IE and let r be a positive real number. A subset D/spl sube/X is an X/Y/r-dominating set if every point in Y is within distance r of a point in D. The X/Y/r-dominating set problem is to find an X/Y/r-dominating set D* with minimum cardinality. Let p/spl ges/1 be an integer. The X/Y/p-center problem is to find a subset C*/spl sube/X of p points such that the maximum distance of any point in Y from C* is minimized. Let X and Y be either V or IE. In this paper, efficient parallel algorithms on the EREW PRAM are first presented for the X/Y/r-dominating set problem. The presented algorithms require O(log/sup 2/n) time for all cases of X and Y. Parallel algorithms on the EREW PRAM are then developed for the X/Y/p-center problem. The presented algorithms require O(log/sup 3/n) time for all cases of X and Y. Previously, sequential algorithms for these two problems had been extensively studied in the literature. However, parallel solutions with polylogarithmic time existed only for their special cases. The algorithms presented in this paper are obtained by using an interesting approach which we call the dependency-tree approach. Our results are examples of parallelizing sequential dynamic-programming algorithms by using the approach.