Practical aspects of algorithmic solutions to gas pulsation problems of pipeline systems

Experiences gained in the field of program development for acoustic pressure and velocity pulsation calculation of reciprocating compressor pipeline systems are discussed. An interactive personal computer program package based on the acoustic plane wave model has been elaborated. Using graph and matrix interpretation of the system, tree-structure pipeline networks are handled by generalized algorithms which make it possible to realize pulsation calculations on two levels, with general logical operations of structure recognition being separated from structure dependent numerical calculations. Economical time and memory usage, as well as program structure and data flow design are detailed.     

A knowledge-based simulation environment for hierarchical flexiblemanufacturing

This article presents an approach to embedding expert systems within an object oriented simulation environment. The basic idea is to create classes of expert system models that can be interfaced with other model classes. An expert system shell is developed within a knowledge-based design and simulation environment which combines artificial intelligence and systems modeling concepts. In the given framework, interruptible and distributed expert systems can be defined as components of simulations models. This facilitates simulation modeling of knowledge-based controls for flexible manufacturing and many other autonomous intelligent systems. Moreover, the structure of a system can be specified using a recursive system entity structure (SES) and unfolded to generate a family of hierarchical structures using an extension of SES pruning called recursive pruning. This recursive generation of hierarchical structures is especially appropriate for design of multilevel flexible factories. The article illustrates the utility of the proposed framework within the flexible manufacturing context     

Roles for knowledge-based computer systems: Case studies in maternity care

The design of medical knowledge-based computer systems requires effective interdisciplinary communication for the development of a community sharing common goals and a common language for design. Over the past 9 years the Perinatal Research Group, an interdisciplinary team of computer scientists, engineers and clinicians, have developed a prototype knowledge-based computer system to aid clinicians in the care of women in labour. The group were uncertain which approach to adopt to progress this system from a prototype to a useful clinical tool to support decision making. A case study and activity theory analysis, of an existing clinical knowledge-based computer system in routine use, helped to resolve a number of communication and methodological issues that the design team encountered. Sharing of backgrounds and perspectives caused the design team to question previous assumptions and to explore alternative functions and roles for knowledge-based computer systems in maternity care. We are now undertaking a longitudinal case study and activity theory analysis of obstetric teams and women in labour to analyse the relationships between clinicians, patients and technology. This work will inform the development of our knowledge-based computer system to place the patient at the centre of the decision-making process.     

Application of AI in software and information engineering

Methodologies already exist for information systems analysis and design (e.g. SSADM, JSP, Merise, etc.) and supporting tools, namely, CASE (Computer Aided Software Engineering) and RDBMS (Relational Database Management System) and/or 4GL tools. All of these tools contain a data dictionary at the core of certain facilities.

In the underlying research and in this paper, the following questions need to be addressed:

• —How can the capability of a recently available data dictionary be enhanced with some knowledge-based modules?

• —What would be the architecture of such a system, based on the data dictionary of some CASE tools?

• —How can the informal and formal modelling approach information system design be combined?

• —What sort of knowledge-representation techniques would be suitable for the different tasks during the analysis and the design of the system?

The system outlined here would work as an intelligent assistant and workbench supporting the developer, but not as an automatic programming environment.     

Logic of design actions

The way in which knowledge about design can be incorporated into knowledge-based design systems is discussed and demonstrated within the framework of an overall logical/linguistic model of the design process. The technique of hierarchical planning is discussed. within this framework. The domain under consideration is that of spatial layout in buildings.     

Structural design language for coupled knowledge-based systems

A Structal Design Language (SDL) has been developed in INTERLISP environment for building coupled knowledge-based expert systems for integrated design of a class of structures. The integrated design includes the preliminary design, structural analysis, design of members, design of connections, and computer-aided drafting of the final design. The complex body of knowledge needed for detailed design of a structure is fractionated into smaller and more manageable knowledge sources which are organized into a hierarchy of cooperating conceptual specialists. SDL provides a multiwindow graphics interface capable of displaying both the orthographic and isometric views of the frame structure and beam-column connections. A three-dimensional face frame representation sentation is used for the graphic display of the beam-column connections. SDL has been used to develop a prototype knowledge-based system for integrated design of steel building structures consisting of moment-resisting frames.     

Lyapunov stability of a class of discrete event systems

Discrete event systems (DES) are dynamical systems which evolve in time by the occurrence of events at possibly irregular time intervals. “Logical” DES are a class of discrete time DES with equations of motion that are most often nonlinear and discontinuous with respect to event occurrences. Recently, there has been much interest in studying the stability properties of logical DES and several definitions for stability, and methods for stability analysis have been proposed. Here the authors introduce a logical DES model and define stability in the sense of Lyapunov and asymptotic stability for logical DES. Then the authors show that more conventional analysis of stability which employs appropriate Lyapunov functions can be used for logical DES. The authors provide a general characterization of the stability properties of automata-theoretic DES models, Petri nets, and finite state systems. Furthermore, the Lyapunov stability analysis approach is illustrated on a manufacturing system that processes batches of N different types of parts according to a priority scheme (to prove properties related to the machine's ability to reorient itself to achieve safe operation) and a load balancing problem in computer networks (to study the ability of the system to achieve a balanced load to minimize underutilization)     

Toward an engineering science of knowledge-based design

In this paper, we present a framework for organizing, evaluating, and developing knowledge-based models of the design process. We argue that evaluation of a design process model can be carried out from three usefully distinguished perspectives: the knowledge it embodies; the functionality of the design process, from a problem-solving viewpoint; and the implementation of the design process as an actual program. This paper focuses on the first two perspective. We systematically introduce a set of basic functional components, and show how existing approaches or systems can be viewed as configurations of these components, in which domain knowledge has been incorporated. As we lay out this framework, we illustrate it in a simple way by using it to describe knowledge-based house floorplanners. We then complete our presentation by analysing a more complex knowledge-based system (DONTE) that designs circuits.     

Decopan Design: a knowledge-based system for industrial controlgear panels design

A wide domain for expert systems application is that of design processes. Decopan Design is a knowledge-based system supporting the design of industrial controlgear panels. Such a design process requires declarative knowledge, heuristic knowledge and human experience and skill, which are excellent subjects in order to be incorporated in a knowledge-based expert system. Decopan Design has been created using an expert system shell and has been linked with a computer-aided drafting program for drawing purposes.     

Task structures as a basis for modeling knowledge-based systems

Recently, there has been an increasing interest in improving the reliability and quality of AI systems. As a result, a number of approaches to knowledge-based systems modeling have been proposed. However, these approaches are limited in formally verifying the intended functionality and behavior of a knowledge-based system. In this article, we proposed a formal treatment to task structures to formally specify and verify knowledge-based systems modeled using these structures. The specification of a knowledge-based system modeled using task structures has two components: a model specification that describes static properties of the system, and a process specification that characterizes dynamic properties of the system. The static properties of a system are described by two models: a model about domain objects (domain model), and a model about the problem-solving states (state model). The dynamic properties of the system are characterized by (1) using the notion of state transition to explicitly describe what the functionality of a task is, and (2) specifying the sequence of tasks and interactions between tasks (i.e., behavior of a system) using task state expressions (TSE). The task structure extended with the proposed formalism not only provides a basis for detailed functional decomposition with procedure abstraction embedded in, but also facilitates the verification of the intended functionality and behavior of a knowledge-based system. © 1997 John Wiley & Sons, Inc.     

Knowledge-based environment for investigating multicomputer architectures

Multicomputers for massively parallel processing will eventually employ billions of processing elements, each of which will be capable of communicating with every other processing element. A knowledge-based modelling and simulation environment (KBMSE) for investigating such multicomputer architecture at a discrete-event system level is described. The KBMSE implements the discrete-event system specification (DEVS) formalism in an object-oriented programming system of Scheme (a dialect), which supports building models in a hierarchical, modular manner, a systems-oriented approach not possible in conventional simulation languages. The paper presents a framework for knowledge-based modelling and simulation by exemplifying modelling a hypercube multicomputer architecture in the KBMSE. The KBMSE has been tested on a variety of domains characterized by complex, hierarchical structures such as advanced multicomputer architectures, local area computer networks, intelligent multi-robot organizations, and biologically based life-support systems.     

Using knowledge-based technology to integrate CIM databases

The authors propose a framework for using knowledge-based systems to integrate the heterogeneous multidatabases of computer integrated manufacturing (CIM). For each database, a corresponding knowledge-based system is designed for directing knowledge-processing of shared information. This one-to-one method reduces the complexity of the problem. Specifically, the structure, features, and knowledge representation for a knowledge-based system are presented. Then, a prototype of an interface between manufacturing planning and computer-aided design is described. Due to the potential for rapid changes in the manufacturing environment, the linkages among CIM databases are designed to be dynamic, flexible, and adaptive to a wide variety of situations     

Information technology and computer-based decision support in diabetic management

This paper describes the application of computer-based techniques within an intelligent, knowledge-based framework to the management of diabetes. The objectives are to structure data collection and storage so that the relevant patient-specific data are collected and made accessible as needed, and to provide clinical decision support on either a day-by-day or longer timescale as appropriate; these objectives relating to both hospital clinic and general practice. For longer-term management, a prototype rule set (greater than 500 rules) has been developed (coded in Sigma PROLOG), validated and tested on patient data. The data collection programs (written in SCULPTOR) to feed the ruleset have been tested in the hospital clinic and compared with the resident data collection system for usability, and impact on the running of the clinic. Links between the data collection programs and the ruleset program have been written and tested. The computer system will also incorporate a module, combining knowledge-based advisory system and glucose/insulin model as patient simulator, that can be tested as a potential decision aid for adjusting insulin dosage on a daily basis.     

Structured logical design of information systems: A methodology,documentation and experience

A methodology for the logical design of Information Systems is presented. This methodology emphasizes structure design. It is based on a precise and extended concept of system logical design, which leads to consider management and organizational factors that have been ignored by most methods. A well-defined procedure for generating the “best” design and attaining a sound and complete system logical specification is the main practical contribution. The methodology has several years of successful testing by many people in practice. The use of computerized techniques in supporting the systems logical design process is also reported.     

From participatory design to participating problem solving: Enhancing system adaptability through user modelling

The issue on the role of users in knowledge-based systems can be investigated from two aspects: the design aspect and the functionality aspect. Participatory design is an important approach for the first aspect while system adaptability supported by user modelling is crucial to the second aspect. In the article, we discuss the second aspect. We view a knowledge-based computer system as the partner of users' problem-solving process, and we argue that the system functionality can be enhanced by adapting the behaviour of the system to fit the needs of users with different profiles. We emphasise that the notion of user modelling is crucial to realise such kind of flexibility. User modelling will be beneficial to the user, not only through adaptive interfaces, but also through the enhanced system adaptability. In a knowledge-based system, by incorporating user models, searching can be reduced to a smaller portion in the knowledge-base, thus enhancing system functionality. In other words, user modelling is incorporated to realise flexible inference control to achieve system adaptability. An example is provided, and a general conceptual model is sketched. We conclude this paper by emphasising that the design aspect and functionality aspect are complementary. Achieving enhanced functionality through joint efforts of computers and human users indicates a kind of participatory execution of computerised problem-solving or participatory problem-solving.     

Symbiotic, knowledge-based computer support systems

The full benefit of computers as tools of thought can come only when we learn to divide intelligence into a portion which is best suited to the human being and a portion which is best suited to the computer and then find a way to combine the process. The limiting resource in future human-computer systems will be the human (with respect to time, attention, complexity management) and not the computer. There is a need for symbiotic, knowledge-based computer support systems which will make communication with computers easier, more rewarding and turn the computer into a convivial tool. Theories, methodologies and tools are neded to make systems of this sort broadly available. In our research project INFORM we are designing, implementing and evaluating a knowledge-based information manipulation system (IMS) as a prototypical development.     

A framework for knowledge-based temporal abstraction

A new domain-independent knowledge-based inference structure is presented, specific to the task of abstracting higher-level concepts from time-stamped data. The framework includes a model of time, parameters, events and contexts. A formal specification of a domain's temporal abstraction knowledge supports acquisition, maintenance, reuse and sharing of that knowledge.

The knowledge-based temporal abstraction method decomposes the temporal abstraction task into five subtasks. These subtasks are solved by five domain-independent temporal abstraction mechanisms. The temporal abstraction mechanisms depend on four domain-specific knowledge types: structural, classification (functional), temporal semantic (logical) and temporal dynamic (probabilistic) knowledge. Domain values for all knowledge types are specified when a temporal abstraction system is developed.

The knowledge-based temporal abstraction method has been implemented in the RÉSUMÉ system and has been evaluated in several clinical domains (protocol-based care, monitoring of children's growth and therapy of diabetes) and in an engineering domain (monitoring of traffic control), with encouraging results.