An optimal gas-fired heating system

Utilizing a prescribed system configuration, this paper discusses the mathematical models of the system components used and formulates a method for controlling a domestic heating system in accordance to a prescribed criterion. The optimal problem treated is one of reducing the room temperature deviation from a prescribed reference value to zero, while at the same time minimizing the value of some predetermined performance or cost functional J. The development proceeds in essentially five steps.

1. (a) The development of the mathematical models for each of the elements of the heating system;

2. (b) Combining the mathematical models into a form which is suitable for the application of optimization techniques;

3. (c) Defining an optimization criterion which incorporates the main objective for minimizing room temperature variations with respect to a prescribed reference temperature;

4. (d) Choosing the optimization technique best suited for the problem;

5. (e) Constructing an optimal control system employing the optimization technique developed.

A numerical example compares the performance of the optimal system with a system of the conventional type which can be found in many American homes.     

An analysis of research topics in software engineering – 2006

This paper is the first in a new annual series whose goal is to answer the following question: what are the active research focuses within the field of software engineering? We considered 7 top journals and 7 top international conferences in software engineering and examined all the 691 papers published in these journals or presented at these conferences in 2006. Consequently, we have a number of findings.

(1) Seventy-three percent of journal papers focus on 20% of subject indexes in software engineering, including Testing and Debugging (D.2.5), Management (D.2.9), and Software/Program Verification (D.2.4).

(2) Eighty-nine percent of conference papers focus on 20% of subject indexes in software engineering, including Software/Program Verification (D.2.4), Testing and Debugging (D.2.5), and Design Tools and Techniques (D.2.2).

(3) Seventy-seven percent of journal/conference papers focus on 20% of subject indexes in software engineering, including Testing and Debugging (D.2.5), Software/Program Verification (D.2.4), and Management (D.2.9).

(4) The average number of references cited by a journal paper is about 33, whereas this number becomes around 24 for a conference paper.

Fuzzy multiple attributes and multiple hierarchical decision making

A procedure is proposed to solve the multiple attributes and multiple hierarchical system under fuzzy environment. The approach is based on:

1. (1) fuzzy representation;

2. (2) hierarchical performance evaluation structure,

3. (3) gradient eigenvector method for rating the fuzzy criteria weighting, and

4. (4) using the max-min paired elimination method for aggregation.

To illustrate the approach, an example on the evaluation of teaching performance in higher education is solved.     

Impact of personality and intelligence on job satisfaction of assembly line and bench work - an industrial study

A study of the impact of machine-paced (M/P) and self-paced (S/P) work on job satisfaction of 28 female industrial assembly workers was evaluated in which M/P work was confounded with simplified work and the S/P job was confounded with enriched tasks. Results indicated the following:

1. 1. Over three-quarters of workers were more satisfied in S/P jobs, while only less than one-quarter were more satisfied in M/P jobs.

2. 2. The 16PF personality test effectively predicts (0·88 multiple correlation) the satisfaction ratios of M/P to S/P jobs.

Applications of power series in computational geometry

A number of algorithms are presented for obtaining power series expansions of curves and surfaces at a point. Some results on the radius of convergence are given. Two applications of series are given:

1. • for curve tracing algorithms, where a truncated series is used to approximate the curve of intersection of two surfaces

2. • to define nth degree geometric continuity, for arbitrary

Investigations on the Dual Calculus

The Dual Calculus, proposed recently by Wadler, is the outcome of two distinct lines of research in theoretical computer science:

(A) Efforts to extend the Curry–Howard isomorphism, established between the simply-typed lambda calculus and intuitionistic logic, to classical logic.

(B) Efforts to establish the tacit conjecture that call-by-value (CBV) reduction in lambda calculus is dual to call-by-name (CBN) reduction.

This paper initially investigates relations of the Dual Calculus to other calculi, namely the simply-typed lambda calculus and the Symmetric lambda calculus. Moreover, Church–Rosser and Strong Normalization properties are proven for the calculus’ CBV reduction relation. Finally, extensions of the calculus to second-order types are briefly introduced.

Finite element programs based on general programming systems

This article describes the advantages and inconveniences with a finite element programming system, i.e. blocks of routines already thoroughly tested, which has to be built together by a programmer to a finite element program. This program may be a tailor-made program to fit a special problem or a general purpose finite element program.

The programming system used as an example in this article consists of

1. *NORSAM—finite element programming system

2. *DASA — pre- and postprocessors

3. *ELLIB—element library

Together they form a complete set of subroutines from datageneration through the necessary routines for matrix manipulation to presentation of results, including the multilevel superelement technique.

Reference to finite element programs applying the programming system concept, is given at the end of the article. Among others, programs for buckling, elasto-plastic analysis of 3-dimensional membranes and solids, nonlinear pipeline problems, acoustic field problems and transient heat conduction in solids are developed. The multilevel superelement technique has been applied in several of these application programs.

The concept of the programming system gives undoubtedly a large saving of time and resources and has proved to be more reliable than conventional methods when developing finite element programs.     

Database considerations in manufacturing systems integration

This paper deals with ideas that could form a basis for manufacturing integration. In recent times more attention is being paid to the idea of applying artificial intelligence (AI) techniques to manufacturing. However, very little attention is being paid to the proper use of these techniques. This research work explores three basic ideas:

1. 1. Applications of the entity-relationship approach to knowledge representation.

2. 2. The basic philosophy of expert database systems and

3. 3. Integration of manufacturing systems from the above two concepts.

The approaches for 1 and 2 are explained with actual implementation experiences, while a framework for integration is proposed from a more philosophical perspective.     

基于GA的模糊控制器在弯辊控制中的应用

UC轧机中间辊弯辊控制回路的数学模型具有很强的时变性和不确定性,为实现其精确控制,设计了一种基于遗传算法的模糊控制器并将其应用于该控制回路中。系统利用遗传算法来优化模糊控制器的隶属函数及量化因子和比例因子的初值,并且根据模糊控制查询表的输出来在线调整量化因子和比例因子。仿真结果表明,用该方法设计的模糊控制器具有一定的自适应能力,将该控制器应用于UC轧机中间辊弯辊控制回路可以使二次型板形缺陷得到快速有效的控制,具有良好的控制性能。     

A survey of simple transfer-function derivations from high-order state-variable models

The problem of the derivation of simple transfer function models from high order state variable models is reviewed. Methods of reduction are classified according to whether they involve

1. (a) the computation of the time or frequency responses

2. (b) the derivation, as an intermediate step, of a transfer function which is the ratio of two polynomials, the denominator being of the same order as the state variable model, or

3. (c) a set of characterising functions.

Particular reduction methods considered are those based on fitting the step or frequency responses, on determining the intermediate, high order transfer function and reducing it by continued fraction expansion and on fitting the moments of the impulse response. An example illustrating these methods is given. The form of the simple model, the criteria of goodness of fit and the practical difficulties involved in the use of these methods are discussed.     

提高AGC厚度控制精度及其百分比的研究

为进一步提高带坯全长厚度控制精度,需提高本体头部命中率,以便绝对AGC投入。介绍了采用动态设定DSU、Taper Head、TaperTail控制算法以维持轧制力恒定来保证板形。为了能够在热轧生产线上应用,通过对造成轧制力偏差原因的分析,依据实际现场数据对不同轧制规程进行计算,给出了DSU穿带的约束条件,避免了穿带自适应误动作。在本体厚度控制中,提出了基于相位补偿的轧辊偏心控制方案,分析其特点及基于相位补偿控制的优越性,并给出实际的F3机架轧制力滤波效果。实际应用结果表明,该控制算法是有效的。     

Verification in loosely synchronous queue-connected discrete timed automata

We look at a model of a queue system that consists of the following components:

1. Two discrete timed automata W (the “writer”) and R (“the reader”).

2. One unrestricted queue that can be used to send messages from W to R. There is no bound on the length of the queue.

W and R do not share a global clock and operate in a loosely synchronous way. That is, the absolute value of the difference between the local time of W and the local time of R is always bounded by a positive constant. We show that the binary reachability for these systems is effectively computable, and this result is generalized to the case when there are two queues (one from W to R and the other from R to W) that operate in half-duplex. We then present some properties (e.g., safety, invariance, etc.) that can be verified for loosely synchronous queue-connected discrete timed automata and give an example of a system composed of a sensor and a controller that is verifiable using our results.     

Discrete warehouse problem

A discrete warehouse is a collection of two-dimensional unit-square objects (robot and obstacles), which are allowed to move horizontally and vertically along grid lines. In this paper, we consider motion planning problems in a discrete warehouse with movable obstacles. In such a setup one is allowed to move some of the obstacles in order to:

1. (1) navigate the robot between an initial and a final position of the warehouse, and

2. (2) construct a clearing (path) between two specified points.

The final positions of the obstacles are unimportant for our problems.

We consider two forms of obstacle manipulations:

1. (a) remote, when the obstacles are moved by a remote mechanism, and

2. (b) contact, when the obstacles are moved only by direct contact of the robot.

We present necessary and sufficient conditions for the existence of a motion in both cases, and propose efficient algorithms for constructing feasible motions.     

Use of simulation in the analysis of shop floor operations

The use of computers in actual system applications is increasing with the availability of intelligent terminals on the shop floor. These terminals can be used by management as tools in the decision making process of planning shop floor operation. This paper discusses a pilot simulation study in the use of conventional Fortran-based simulation programs by shop floor management to:

1. 1. Participate in the evaluation of proposed FMS systems,

2. 2. Assess the impact of FMS acquisition on existing facilities,

3. 3. Assist in the identification of operational alternatives in “bottle neck” situations.

The pilot study employs a batch-oriented MRP system to provide daily updates of outstanding production center loadings on a monthly planning horizon. Two intelligent terminals are used to access a mini computer facility that executes the simulation models. The terminals have AT-compatible capabilities and are also used as data acquisition devices that support the numerically controlled operations within each work center.

The simulation models represent the 13 work centers of the firm and provide information about the average utilization of each work center, the number of parts in each queue and the average delay of parts in the queues. Future extensions of the models are planned to utilize the terminals' graphic animation capabilities to display the flow of production orders through the manufacturing facility.     

Performance assessment of control systems in rolling mills – application to strip thickness and flatness control

This contribution takes the control performance monitoring (CPM) technology into a new industrial area, the metal processing, where not much work has been done before. It is shown how to explore not yet discovered opportunities for controller performance improvement in this industrially interesting field, where special aspects have to be considered. This includes online vs. batch-wise performance evaluation, time-based vs. length-based assessment, and oscillation diagnosis. The paper presents two industrial case studies of the performance evaluation of control systems in a tandem cold rolling mill: (1) a feedforward/feedback strip thickness controller; and (2) an internal model control of the strip flatness. Routine operating data are analysed to obtain the performance monitoring metrics in terms of minimum variance index, oscillation index, and to suggest improvement measures. A monitoring tool for calculating and displaying the performance indices has been developed, and tailored to the applications in this field. The results indicate that tuning the feedback thickness controller is suggested to better handle entry thickness disturbances for specific coils. The performance of the flatness controller is found to be satisfactory, thus no actions are needed.     

基于分散鲁棒控制策略的冷连轧板形板厚多变量系统研究

在冷连轧生产中,通过弯辊来控制板形质量时,在一定程度上会对出口板厚造成影响;而通过调节辊缝来达到控制板厚质量时又会影响板形,这是一个耦合的双入双出过程.针对板形板厚多变量耦合系统,提出一种分散鲁棒控制策略,充分发挥鲁棒控制器的抗干扰性能,将耦合通道人为看作扰动后,针对独立通道分别设计鲁棒控制器,从而在保证各控制通道鲁棒性的同时实现了解耦.仿真实验结果表明了该设计的有效性.     

The monadic second-order logic of graphs X: Linear orderings

Graphs are finite and handled as relational structures. We give some answers to the following general questions:

1. (1) For which classes of graphs is it possible to specify a linear ordering of the set of vertices of each graph of by fixed monadic second-order formulas?

2. (2) For which classes of graphs does there exist an extension of monadic second-order logic such that a subclass L of is recognizable if and only if it is the class of graphs in that satisfy a formula of ? (In this paper, recognizability is understood in an algebraic sense, relative to a finite set of graph operations and basic graphs that generate all graphs of .)

3. (3) For which classes of graphs is it possible to construct, in every graph of the class, and by fixed formulas of a suitable extension of monadic second-order logic, its hierarchichal structure, i.e., a finite term written with the operations and basic graphs of (2), that defines the considered graph?

Applications concern dependency graphs of partially commutative words, partial k-paths, cographs, and graphs, the modular decomposition of which uses prime graphs of bounded size.     

A global parametrization of asymptotically stable linear systems

In this paper we construct a homeomorphism from the set of p × m transfer functions of McMillan degree n onto the open subspace of asymptotically stable linear systems. This homeomorphism yields a one-to-one correspondence between

1. (i) canonical forms for state space equivalence of minimal systems and

2. (ii) canonical forms for state space equivalence of asymptotically stable minimal systems.

Implications for the topology of various sets of asymptotically stable systems are given.     

轧机主传动系统自抗扰控制器设计与应用

轧钢过程中的负荷扰动容易激起机电振动,这严重影响板带材的产量和质量.为了抑制机电振动,针对轧机主传动系统存在不确定外部扰动和未建模动态的特点,首先建立了轧机主传动系统的模型,将不确定性外扰和未建模动态视为一个综合扰动项,然后利用扩张状态观测器对综合扰动项进行观测和补偿,设计了一种不依赖于对象模型的轧机主传动系统鲁棒控制器.仿真结果证明:该控制器比外扰负荷观测器控制系统具有更好的抗扰动能力,同时对系统内部参数如负载转动惯量、转矩常数等的摄动也具有较强的鲁棒性,有效抑制了由于轧制负荷周期性变化和轧制负荷突变引起的机电振动.首次将扩张状态观测器和自抗扰控制技术应用到轧机主传动系统机电振动控制中,并通过实验证明了该方法的有效性和优越性.