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There is hardly a science that is without the notion of "system". We have systems in mathematics, formal systems in logic, systems in physics, electrical and mechanical engineering, architectural-, operating-, infonnation-, programming systems in computer science, management-and PJoduction systems in industrial applications, economical-, ecological-, biological systems, and many more. In many of these disciplines formal tools for system specification, construction, verification, have been developed as well as mathematical concepts for system modeling and system simulation. Thus it is quite natural to expect that systems theory as an interdisciplinary and well established science offering general concepts and methods for a wide variety of applications is a subject in its own right in academic education. However, as can be seen from the literature and from the curricula of university studies -at least in Central Europe-, it is subordinated and either seen as part of mathematics with the risk that mathematicians, who may not be familiar with applications, define it in their own way, or it is treated separately within each application field focusing on only those aspects which are thought to be needed in the particular application. This often results in uneconomical re-inventing and re-naming of concepts and methods within one field, while the same concepts and methods are already well introduced and practiced in other fields. The fundamentals on general systems theory were developed several decades ago. We note the pioneering work of M. A. Arbib, R. E. Kalman, G. 1. Klir, M. D.



Abstractly modelling complex systems

Systems theory means different things to different people. Here, we mean the mathematical study of abstract representations of systems, keeping in mind the problems that seem most important for real systems and the aspects of the theory which seem most amenable to mathematical development.
Charles Rattray

Formal Specification

We identify both the mathematical structures and the logic that underpin the main approaches to the formal specification of systems. Our aim is to present a theoretical framework for system specification that is built on precise mathematical foundations. Being faced with the syntactic details of particular specification languages can be confusing for someone who lacks mathematical experience. For this reason we prefer to present the important theoretical concepts that underlie system construction in the familiar notation of logic and mathematics. Once an understanding of these concepts is achieved, the notations that are currently in use can be mastered without difficulty. We see an analogy with the need to understand the fundamental principles of programming before becoming too involved with the fussy, and often confusing, syntactic details of concrete mechanical codes. Understanding is best achieved when an abstract programming language is used.
Gillian Hill

On mathematical systems theory

Intuitively, systems are, frequently hierarchical, aggregations of physical or mental objects, composed either by nature or composed by us for a certain purpose or for logical reasons according observable and distinguishable “properties”. Properties can be physical or logical qualities and quantities, location in physical space, behavior in physical time, physical or logical relationships between objects.
Rudolf F. Albrecht

An Introduction to Discrete Event Modeling Formalisms

Modeling formalisms offer several advantages over non formal methods in the representation of simulation models. These advantages include a compact and rigorous notation. Models specified in a modeling formalism are also independent of any simulation language.
Fernando J. Barros, Bernard P. Zeigler

Design of Microsystems: Systems-theoretical Aspects

Advances in Microelectronic technology, especially sensor- and actuator technology, have resulted in the development of integrated circuits which, in addition to microelectronics and transducers, contain mechanical and optical components. Consequently it has become possible to develop complex systems by coupling these new components with conventional microelectronic components and systems. The construction of these systems necessitates changes in the design and manufacturing process. This paper concentrates on the changes necessary, especially in the design process, to meet the challenges of this new field of microsystems (i.e., microelectromechanical systems, micromechatronics).
Franz Pichler

A formal representation of DSS generator

It is usual that an MIS (management information system) is categorized by the three levels, TPS (transaction processing system), MIS in a narrow sense and DSS (decision support system). A TPS of the first level constitutes the infra-structure of an MIS, which handles transaction process of a business, and maintains a corporate DB (data base). This DB supplies basic information for the MIS.
Yasuhiko Takahara, Xiaohong Chen

Structure and Functions of Operating Systems

The operation of a modern computer cannot be imagined without the employment of an operating system. Even in small real-time computers dedicated to a single task some general parts independent of the specific application can be identified. These auxiliary parts assist in bridging the gap between the mostly rather uncomfortable hardware level and the needs of higher levels induced by the application environments. Furthermore, in many systems there exists the necessity for an additional task. Modern computers perform very fast, much faster than is needed for most applications especially for those with interactive controlling. In order to efficiently use the computer’s power we have to organize the concurrent execution of many more or less independent courses of events. Hence, a number of objectives arises for which solutions have to be offered by the operating system. Some of the major topics can be identified as follows:
  • Accepting sets of self-contained units capable of concurrent execution
  • Organizing a multiplexed usage of processors
  • Supplying facilities for interaction between execution units
  • Organizing the competition for system resources
  • Organizing access to remote recources (this hints at distributed systems)
Horst D. Wettstein

Object-oriented system development — concepts and tools —

Modern computing devices and their patterns of usage continue to change dramatically at an unprecedented rate and technological capabilities as well as our expectations are very different from what they were in the past. Personal workstations and networks have largely replaced the expensive mainframe computers of the sixties and seventies and users are increasingly unwilling to tolerate tools and interfaces that are arcane and cryptic. Instead they expect technology to adapt to its users and support languages and habits which take account of their users’ strengths and weaknesses. While this is a very positive and desirable development it greatly increases the resource requirements and complexity of computer software. Fortunately computers continue to become faster, smaller and cheaper, so that the difficulty of developing effective and reliable programs rather than traditional concerns with hardware efficiencies has increasingly come to dominate the cost of applications development. The term software crisis is often used in this context and the question of how to structure and control the “growth” of large programs has become a mayor focus of software research.
Wolfgang Kreutzer

Model-based software engineering for interactive systems

Software solutions for many target domains (e.g. business, financial, CAD, scientific visualization, Internet) are typically organized as interactive systems. This article discusses the design of interactive software systems in general and presents a model-based environment for computer-aided design of such systems, the Application Modeling Environment (AME).
Christian Märtin

Modeling fault-tolerant system behavior

Aerospace and railroad control systems need to ensure the safety of passengers. To prevent financial losses, banking and telecommunication systems must offer high availability. Such safety- and mission-critical systems require high assurance. To this end, several formal methods for specifying and verifying non-functional system properties like timeliness, safety and liveness have been developed (Leveson et al. 1994, Leeb and Lynch 1996, Kirner and Davis 1996, Bruel et al. 1996, Mok et al. 1996). These methods are intended to give system developers and customers greater confidence that the systems satisfy their requirements. A number of these verification methods are based on finite-state representations and have achieved considerable success in practical applications.
Mario Dal Cin

Applications of artificial neural networks

In this article we consider some theoretical aspects of neural networks and some of their varied applications. The theoretical aspects are presented from the point of view of a system, basically input/state/output. For the applications, we consider large systems: from production systems, through biological and chemical systems and on to environmental systems.
David William Pearson, Gérard Dray

The method of equivalence in robotics

A manipulation robot is a technical system capable of affecting its environment purposefully, in a way resembling the human manipulation. The function of manipulation is executed by a mechanical device called a manipulator. The robotic manipulator consists of a certain number of rigid bodies called links, connected to each other by joints. Links form a chain that begins at a fixed base of the manipulator, and terminate at its end. Relative motions of consecutive links, accomplished at the joints, have usually one degree of freedom and can be described either as rotations or as translations. Accordingly, the joints are referred to as revolute or prismatic. In typical manipulator designs the joints are driven by independent actuators. Forces or torques exerted by actuators play the role of control inputs. From anthropomorphic perspective the manipulator acts as a substitute of the human arm, while the end-effector, often topped with a gripper, replaces the human hand.
Krzysztof Tchoń

Manufacturing Algebra: a new mathematical tool for discrete-event modelling of manufacturing systems

The Manufacturing Algebra was developed during several years of research and more recently within the ESPRIT Basic Research HIMAC-8141 (Hierarchical Management and Control of Manufacturing Systems). For a comprehensive list of publications see the enclosed References. The Manufacturing Algebra is a methodology specifically conceived for investigating and modelling discrete manufacturing systems at various degrees of accuracy. Such an endeavour was motivated by the apparent limitations of the current approaches-first of all Queueing Theory and Petri Nets-whenever applied to the field of engineering here considered. In fact they were adapted to manufacturing problems, but not originally tailored to meet their requirements, whereas that is an essential feature of the Manufacturing Algebra.
Enrico Canuto, Francesco Donati, Maurizio Vallauri


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