Nonlinear input/output modelling

This paper gives a highly abbreviated overview of some of the key issues in empirical nonlinear modelling for chemical process applications. This task is complicated by the inherent nature of nonlinearity: the term describes a class of systems by the one feature they lack. In fact, this division — linear vs. nonlinear — suggests a ‘unity’ or ‘homogeneity’ of the class of nonlinear systems that does not exist. Consequently, this review will focus on specific sub-classes of nonlinear models that have analytically useful structural characteristics, and comparisons will be made both between these classes and with the more familiar linear models. Length limitations restrict these discussions somewhat, but it is hoped that the range of examples will be great enough to demonstrate how nonlinear model identification is both similar to and different from linear model indentification. The general conclusion of this paper is that nonlinear input/output modelling is a vitally important practical art with many unresolved issues; the principal objective of this paper is to elucidate some of these issues.     

Decentralized adaptive output feedback control via input/output inversion

A decentralized adaptive output feedback control design method is presented for control of large-scale interconnected systems. It is assumed that all the controllers share prior information about the subsystem reference models. Based on that information, a linear dynamic output feedback compensator and linearly parameterized neural network (NN) are introduced for each subsystem to partially cancel the effect of the interconnections on the tracking performance. Boundedness of error signals is shown through Lyapunov's direct method.     

Multi-stability in monotone input/output systems

This paper studies the emergence of multi-stability and hysteresis in those systems that arise, under positive feedback, starting from monotone systems with well-defined steady-state responses. Such feedback configurations appear routinely in several fields of application, and especially in biology. Characterizations of global stability behavior are stated in terms of easily checkable graphical conditions.     

Generation and sensitivity of input/output DC plots

A computer program operating in an interactive mode enables input/output DC plots of nonlinear systems to be generated and sensitivity properties to be studied. The computational method is based on the piecewise-linear approach. The technique is applied to simulate transistor curve tracers and to carry out worst-case analysis of transfer characteristics in digital circuits.     

Voice input/output in inspection data entry

Today's voice technology can provide voice input/output systems that can be used effectively in the factory. This will happen only if the proper technology is connected to suitable applications. Discrete word-dependent speaker recognition in inspection data entry is one such combination.     

The input/output complexity of transitive closure

Suppose a directed graph has its arcs stored in secondary memory, and we wish to compute its transitive closure, also storing the result in secondary memory. We assume that an amount of main memory capable of holdings values is available, and thats lies betweenn, the number of nodes of the graph, ande, the number of arcs. The cost measure we use for algorithms is theI/O complexity of Kung and Hong, where we count 1 every time a value is moved into main memory from secondary memory, or vice versa.In the dense case, wheree is close ton ², we show that I/O equal toO(n ³/s) is sufficient to compute the transitive closure of ann-node graph, using main memory of sizes. Moreover, it is necessary for any algorithm that is standard, in a sense to be defined precisely in the paper. Roughly, standard means that paths are constructed only by concatenating arcs and previously discovered paths. For the sparse case, we show that I/O equal toO(n ²e/s) is sufficient, although the algorithm we propose meets our definition of standard only if the underlying graph is acyclic. We also show that(n ²e/s) is necessary for any standard algorithm in the sparse case. That settles the I/O complexity of the sparse/acyclic case, for standard algorithms. It is unknown whether this complexity can be achieved in the sparse, cyclic case, by a standard algorithm, and it is unknown whether the bound can be beaten by nonstandard algorithms.We then consider a special kind of standard algorithm, in which paths are constructed only by concatenating arcs and old paths, never by concatenating two old paths. This restriction seems essential if we are to take advantage of sparseness. Unfortunately, we show that almost another factor ofn I/O is necessary. That is, there is an algorithm in this class using I/OO(n ³e/s) for arbitrary sparse graphs, including cyclic ones. Moreover, every algorithm in the restricted class must use(n ³e/s/log³ n) I/O, on some cyclic graphs.The work of this author was partially supported by NSF grant IRI-87-22886, IBM contract 476816, Air Force grant AFOSR-88-0266 and a Guggenheim fellowship.     

Optimal input/output reduction in production processes

While conventional Data Envelopment Analysis (DEA) models set targets for each operational unit, this paper considers the problem of input/output reduction in a centralized decision making environment. The purpose of this paper is to develop an approach to input/output reduction problem that typically occurs in organizations with a centralized decision-making environment. This paper shows that DEA can make an important contribution to this problem and discusses how DEA-based model can be used to determine an optimal input/output reduction plan. An application in banking sector with limitation in IT investment shows the usefulness of the proposed method.     

PLC输入输出端的硬件保护

可编程控制器作为新一代的工业控制装置 ,通常其本身具有较完善的保护功能 ,但如果现场环境过于恶劣 ,如供电不稳、灰尘大等 ,很容易造成输入输出点的损坏 ,或者因输出端驱动的负载而产生干扰 ,影响PLC控制系统的正常工作。为此 ,在PLC输入输出端采取硬件保护措施是十分必要的。(1)输入端的保护PLC输入端最有效的保护方法是外加一级光电耦合器 ,一旦有高压电压等侵入回路时 ,使其击穿保护级光耦 ,然后像更换熔断器一样方便地更换损坏了的光耦 ,及时排除故障。增加的保护级光耦可选用 4N2 5型。对于开关频率高的场合 ,可选用TIL110型。…     

Canonical forms for bilinear input/output maps

In an earlier paper [1], necessary and sufficient conditions were obtained for a state-space realization of a bilinear inout/output map to be quasi-reachable and observable, and procedures were introduced for reducing any realization not of this type to one which is. In rids paper, it is shown that any two such quasi-reachable and observable (or canonical) realizations are isomorphic, and using this result, it is possible to generate canonical forms for these realizations by means of complete sets of independent invariants.     

Efficient timestamp input and output

In this paper we provide efficient algorithms for converting between timestamp values that signify some number of seconds from an arbitrary origin, and character strings specifying Gregorian dates, such as ‘January 1, 1993’. We give several algorithms that explore a range of time and space trade-offs. Unlike previous algorithms, those discussed here have a constant time cost over a greatly extended range of timestamp values. These algorithms are especially useful in operating systems and in database management systems.     

A new technique for WFTA input/output reordering

The Winograd Fourier transform algorithm (WFTA) is receiving intensive study. The advantage of this class of transform is its potential high throughput due to reduced multiplication count. However, both input and output reorderings have to be performed when the algorithm is implemented. In this work, a technique for the WFTA input/output reorderings is developed. This technique is flexible to the choice of the base numbers of WFTA and capable of operating at high speed in digital hardware. This technique requires no extra memory for reordering when implementing the WFTA in the residue number system if the moduli set of RNS is carefully chosen to contain the base numbers of WFTA.This work was supported in part under AFOSR Grant F49620-79-C-0066 and Lockheed Independent Research Funds.     

基于输入输出关系的综合黑盒测试方法

主要针对黑盒测试存在的问题,提出一种测试用例设计方法:根据系统规格说明和系统输入输出之间的关系等附加信息,来确定输入参数之间的覆盖和约束关系,并对参数输入域进行约减;接着对各组合进行处理;仅对各个组合中的输入变量进行两两组合覆盖;对各相关组的结果进行水平拼接组合.实践结果表明,该方法在不影响测试检错能力的情况下有效地提高了测试用例的选择效果.     

Learning to classify parallel input/output access patterns

Input/output performance on current parallel file systems is sensitive to a good match of application access patterns to file system capabilities. Automatic input/output access pattern classification can determine application access patterns at execution time, guiding adaptive file system policies. In this paper, we examine and compare two novel input/output access pattern classification methods based on learning algorithms. The first approach uses a feedforward neural network previously trained on access pattern benchmarks to generate qualitative classifications. The second approach uses hidden Markov models trained on access patterns from previous executions to create a probabilistic model of input/output accesses. In a parallel application, access patterns can be recognized at the level of each local thread or as the global interleaving of all application threads. Classification of patterns at both levels is important for parallel file system performance; we propose a method for forming global classifications from local classifications. We present results from parallel and sequential benchmarks and applications that demonstrate the viability of this approach.     

Expressibility of output equals input

We examine the common and seemingly simple specification that the output stream equals the input stream. We show that this is not in full generality expressible in first-order or temporal logic by an infinite set of sentences or a recursive specification, but requires certain extra assumptions, such as the existence of a clock or discrete input values.The main negative results are stated for first-order expressibility and have direct corollaries for inexpressibility in first-order temporal logic: output equals input with arbitrary delay is not expressible by a (perhaps infinite) theory (Theorems 2 and 3), even with a timestamp (Theorem 8), and is not expressible for an timeline by a sentence, even with a timestamp (Theorem 10). Output equals input with constant delay cannot be expressed for timeline by a sentence with extra unary predicates over the timeline.As an example of the positive results, we show output equals input can be expressed by a sentence in the language with a (weak) clock if the base model contains either an extra function (Theorem 14), or arithmetic (Theorem 15).Supported by Aerospace Sponsored Research     

A note on linear input/output maps of bounded-type

This note studies a class of constant, linear, continuous-time input/output maps, which is called input/output maps of bounded-type. An algebraic condition for an input/output map to be of bounded-type is given. Its application to realization theory (especially for delay-differential systems) is considered. An example is given to illustrate how it gives rise to a concrete realization procedure.