Synthesis of control implementation for discrete manufacturing systems

The paper presents the concepts and steps required to synthesize a correct control implementation for discrete manufacturing systems, starting from Grafcet specifications. A formal framework implementing the synthesis steps is also presented and illustrated with an example of a drilling system.     

基于UML OCL、支持团队开发的企业组织元模型

组织模型不仅要支持传统的纵向的组织结构,而且还要支持以团队方式工作的横向组织结构。本文提出了包含组织纵向和横向结构的组织元模型,并采用UML对象约束语言(OCL)描述了元模型中实体与实体之间的联系和约束关系。除用OCL描述组织结构外,还显式地给出了组织规则的OCL表示方法。这样,便可将组织规则与组织结构相分离,从而在组织结构不变的情况下,通过修改组织规则,以达到提供企业敏捷性的目的。     

A synthesis approach to distributed supervisory control design for manufacturing systems with Grafcet implementation

In supervisory control, computational complexity and implementation flexibility represent major challenges when a large number of local components compose a target system. To overcome these difficulties, we propose a formal approach to distributed control synthesis and implementation for automated manufacturing systems (AMS). We assume that the system is modelled with automata in a local modular fashion. Local control specifications are defined for each local subsystem by means of logical equations to construct local controllers (LCs). Then, global control specifications, stated as logical implications, are applied to the LCs, which allows synchronisation and cooperative interaction among the subsystems. This paper makes two contributions. First, it outlines a formal method for constructing minimally restrictive and deadlock-free distributed controllers (DCs). Second, it proposes a method for the interpretation of these DCs into Grafcet, which is a graphical modelling formalism widely used to design the controller’s dynamic behaviour for AMS. An experimental manufacturing system illustrates the approach.     

A bottleneck-based beam search for job scheduling in a flexible manufacturing system

In this paper, we study job-scheduling methods for flexible manufacturing systems (FMSs). Routeing flexibility is a feature that distinguishes FMS scheduling from a classic general jobshop problem. We formalize the problem as a flexible jobshop problem and introduce a flexibility index to measure the extent of routeing flexibility. Based on a procedure to identify a potential bottleneck machine, we develop a beam search method for approximately solving the problem. The proposed method yields a significantly shorter makespan than that of the commonly used shortest processing-time dispatching rule, and it properly exploits the added flexibility in routeing. The computational effort required also is small enough to enable practical implementation.     

Monitoring the deviation of coaxiality of nominally cylindrical surfaces of a component

A recommendation is proposed for improving monitoring of deviations from coaxiality of nominally cylindrical surfaces of components that makes it possible to exclude ambiguity for the results of monitoring operations and also to formalize these operations. __________ Translated from Izmeritel’naya Tekhnika, No. 12, pp. 17–20, December, 2007.     

On the Multihead Weigher Machine Setup Problem

A multihead weigher machine (MWM) is a computer‐controlled machine used to fill a package with small products or parts with a given target weight. MWMs are widespread in the food and non‐food industries because of their high performance in terms of variety of products to be packed, high throughput and quality of the packaged items. Despite the popularity of these machines, no studies to date have addressed how to set up the operating parameters of these machines. In industrial practice, operators currently use ad hoc rules to setup an MWM, but the initial settings can have a dramatic effect on the machine performance. The aim of this paper is to formalize the setup problem and its main variables. Then an optimization technique is proposed to solve the problem. Copyright © 2016 John Wiley & Sons, Ltd.     

A simulation-based optimization approach to size manufacturing systems

The problem of sizing the resources of a production system is widely encountered both in the literature and in practice. Simulation is a very useful method to identify the necessary number of resources. However, if there are numerous resources, it can become impossible to make a sound ‘trial-and-error’ analysis with simulation models, so that strategies using simulation optimization appear as an attractive approach. Unfortunately, it is necessary to specify a cost function, and, in practice, it is often very difficult to formalize such a function which is used to determine the number of resources that will minimize this cost. In this article, we propose a different modelling approach, which aims at sizing the resources so as to meet the design specifications. In this respect, we search for the minimum number of resources of each type, while satisfying the performance requirements specified in the design project. As a result, the problem is formulated as a stochastic multi-objective optimization problem with constraints. The approach used here is based on simulation, used in conjunction with a bootstrap approach which accounts for the stochastic aspect of the model, and with regression metamodelling in order to derive an analytical formulation of the constraints together. Different multi-objective optimization methods can then be used to solve the problem. An illustrative example is given.     

The interpolation function of a general serendipity rectangular element

The shape functions of serendipity rectangular elements had originally to be found by inspection. More recently an algorithm has been developed to formalize the construction of these shape functions. Here a simple expression is found for the interpolation function of the most general serendipity element. The shape functions can be derived immediately.     

An approach to the implementation and verification of abstract data

Abstract

The concept of abstraction can be used to simplify and formalize the design of software. However, most of the existing techniques based on abstraction only consider the control structure but not the data structures in the software. The transformation of a data abstraction, i.e., an abstract data type, to a physical data structure is a complicated process. It is composed of three major parts: a specification technique for describing a data abstraction; a deriving process for deriving the representation of the abstraction based on the specification; and a verification method for verifying the correctness of the specification and the representation of the abstraction. In this paper, we will concentrate on the last two problems, and it is assumed that the algebraic specification technique is used for describing abstract data types. Also, we will use examples to illustrate the use of the proposed approach.     

Improving word coverage using unsupervised morphological analyser

Powerful computers are needed for processing tasks related to human languages these days. Human languages, also called natural languages, are highly versatile systems of encoding information and can capture information of various domains. To enable a computer to process information in human languages, the language needs to be appropriately ‘described’ to the computer, i.e. the language needs to be ‘modelled’. In this work, we present an approach for acquisition of morphology of inflectional language like Hindi. It is an unsupervised learning approach, suitable for languages with a rich concatenative morphology. Broadly, our work is carried out in three steps: 1. Acquire the morphology of Hindi from a raw (un annotated) Central Institute of Indian Languages (CIIL), Mysore text corpus, 2. prepare clusters and prepare stem bag and suffix bag, 3. use the morphological knowledge to decompose given word as stems and suffixes according to their morphological behaviour and add new words. A prime motivation behind this work is to eventually develop an unsupervised morphological analyser which is language-independent (used for Hindi). Second motivation is to develop a Morphological segmentation which is language-independent as it is shown that study of morphology would benefit to a range of NLP tasks such as speech recognition, speech synthesis, machine translation and information retrieval. Though Hindi is an important and a national language in India, little computational work has been done so far in this direction. Our work is one of the first efforts in this regard and can be considered pioneering. There are many such languages for which it is very important to have a suitable but inexpensive computational acquisition process. Languages receive very little attention of computational linguistic research both in terms of availability of funds and number of researchers. We however do not claim that our approach is a solution for all such languages. Different languages have characteristics that require individual research attention.     

Design-based studies: an action-based ‘form of knowledge’ for thinking,reasoning and operating

Some points of significance in the Royal College of Art report Design in general education have, to a certain extent, been insufficiently exploited by ‘doers and makers’. This paper re-acknowledges the contribution made by the identification of ‘modelling’ and ‘design awareness’ to the acceptability of action-based problem-solving. Simultaneously, the paper relates the RCA report to longer-term trends in thinking about traditional conceptions of knowledge divisions and boundaries. The RCA report is seen as an inevitable point on a continuum, but unfortunately it stopped short of suggesting action-based modes of knowing and thought as constituents of a ‘new’ discrete form of knowledge. This concept, outlined by Hirst, functions alongside the structures associated with verbal/mathematical and other language ‘tools’ used generally to organize aspects of reality in distinctive and characteristic ways and to generate new thought within the language mode and associated knowledge domain of ‘doing and making’.The paper goes on to propose a model which relates the imagery and structure of action-based knowledge with the principle theories on the thought-verbal language relationship and some other prominent observations on the nature of thought and language. As a follow-up to this it is necessary to outline the crucial importance of internalization of action-based experience so that both action-based imagery and structure are assimilated into the thinking, awareness and character of the individual.Finally the paper examines some of the implications this might have for the way design-based studies are to be viewed in the future.     

Recognition and interpretation of interacting and non-interacting features using spatial decomposition and Hamiltonian path search

Since it is a complex task to formalize the feature recognition problem explicitly, a large variety of systems has been developed. One of the problems these systems have to overcome is the recognition and interpretation of interacting features. A fair success has been achieved in surface based methods to recognize certain classes of interacting features. However the problem remains for general cases of interacting features. Recently much effort has been focused on the volumetric approach. We present here the current state of a volumetric feature recognition method. The system considers interacting features in prismoidal parts and it operates in two stages: (1) recognition of regions of interest: a spatial decomposition of the space bounded by a predefined circumscribing volume is performed. A ‘cell evaluated and directed adjacency graph’ is then established. This graph is traversed to identify cavity volumes. (2) interpretation: cavity volumes made up of more than one cell can be produced by different machining operations. A graph-based decomposition method and Hamiltonian path search are combined to generate interpretations which correspond to optimal machining. The system CEDAG developed in this work uses a cell-face directed graph and contrasts the face-edge and edge-vertex graphs encountered in most conventional graph-based recognition methods.     

The role of aggregate in the fracture of concrete

The fracture of concrete is reviewed. Tests on notched and unnotched beams made from concretes containing aggregates of different sizes and types are described. A simple model is proposed to elucidate and formalize the role of the aggregate particles in a brittle matrix. It is concluded that aggregate particles cause cracks to form in a concrete matrix at a lower stress than that at which the matrix would crack if it contained no aggregate. It is also concluded that aggregate particles impede the extension of matrix cracks.     

规格说明语言ChiSL

ＣｈｉＳＬ是一种作用式可执行的功能规格说明语言，它是以数据抽象为核心的将代数规格说明和面向模型的规格说明两种技术有机地结合起来的模块化语言，具有良好的数据性质和可读性，能比较方便地书写大型规格说明?由于该语言是可执行的，因此ＣｈｉＳＬ规格说明可作为所要开发的软件系统的一个原型在该语言的支撑系统上执行。本文后面介绍了使用ＣｈｉＳＬ语言及其支撑系统开发软件原型的一些应用实例。     

Automated Arabic Text Classification Using Hyperparameter Tuned Hybrid Deep Learning Model

The text classification process has been extensively investigated in various languages, especially English. Text classification models are vital in several Natural Language Processing (NLP) applications. The Arabic language has a lot of significance. For instance, it is the fourth mostly-used language on the internet and the sixth official language of the United Nations. However, there are few studies on the text classification process in Arabic. A few text classification studies have been published earlier in the Arabic language. In general, researchers face two challenges in the Arabic text classification process: low accuracy and high dimensionality of the features. In this study, an Automated Arabic Text Classification using Hyperparameter Tuned Hybrid Deep Learning (AATC-HTHDL) model is proposed. The major goal of the proposed AATC-HTHDL method is to identify different class labels for the Arabic text. The first step in the proposed model is to pre-process the input data to transform it into a useful format. The Term Frequency-Inverse Document Frequency (TF-IDF) model is applied to extract the feature vectors. Next, the Convolutional Neural Network with Recurrent Neural Network (CRNN) model is utilized to classify the Arabic text. In the final stage, the Crow Search Algorithm (CSA) is applied to fine-tune the CRNN model’s hyperparameters, showing the work’s novelty. The proposed AATC-HTHDL model was experimentally validated under different parameters and the outcomes established the supremacy of the proposed AATC-HTHDL model over other approaches.     

Incorporating individual health-protective decisions into disease transmission models: a mathematical framework

It is anticipated that the next generation of computational epidemic models will simulate both infectious disease transmission and dynamic human behaviour change. Individual agents within a simulation will not only infect one another, but will also have situational awareness and a decision algorithm that enables them to modify their behaviour. This paper develops such a model of behavioural response, presenting a mathematical interpretation of a well-known psychological model of individual decision making, the health belief model, suitable for incorporation within an agent-based disease-transmission model. We formalize the health belief model and demonstrate its application in modelling the prevalence of facemask use observed over the course of the 2003 Hong Kong SARS epidemic, a well-documented example of behaviour change in response to a disease outbreak.     

AN EXAMINATION OF THE GROWTH MODELS FOR TiC WHISKERS MADE BY CVD

Whiskers of refractory compounds such as carbides, nitrides and oxides have been grown by many researchers by chemical vapor deposition. The growth of whiskers from the vapor phase has been suggested to occur by the vapor-solid (VS) and/or the vapor-liquid-solid (VLS) mechanisms. In the growth of TiC whiskers with nickel as the catalyst, the VLS mechanism is widely accepted as the primary initial growth mechanism in which a ternary eutectic of Ni, Ti and C is considered to provide the growth path for the whiskers. In this paper, we examine the published literature on the growth of TiC whiskers by several researchers and show that this view of the ternary eutectic may not explain the whisker growth at temperatures below the eutectic point of the Ti-Ni-C system. This paper attempts to formalize a VLS mechanism model based on a binary eutectic for the observed formation of whiskers at lower temperatures,     

Automating the analysis of results of a holographic experiment

This article examines an algorithm for the computer analysis of holographic interference fringes of cylindrical shells in a three-hologram, double-exposure experiment conducted to study displacements. The method, based on graphical input of the coordinates of reference points on lines of equal order and approximation of order surfaces on the basis of regression analysis, makes it possible to formalize selection of the type of nonlinear mathematical model and speed up subsequent calculations. The statistical characteristics of the model and the regression process improve with an increase in the number of points. An analysis is made of the accuracy of the analysis of holographic interference fringes by the proposed method using the example of results of tests of a cylindrical shell with a nonplanar end in uniaxial compression. Satisfactory agreement is seen between data obtained by the proposed method and the traditional method.Translated from Problemy Prochnosti, No. 5, pp. 78–85, May, 1994.