A Case Study in Community Care Using Systems Thinking

This paper uses a recent application of System Dynamics in community care to contribute to a clarification of the role of System Dynamics as a framework for strategic debate. A revised framework for System Dynamics within a philosophy of ‘modelling as learning’ is summarized. This framework is now referred to as Systems Thinking and combines knowledge acquisition and both qualitative and quantitative modelling, supported by microworlds and archetypes to aid dissemination of insights. The emphasis of the paper is on using qualitative models interactively with different groups of participants in the problem domain. The purpose is to assist the development of a shared understanding of how culture, power and politics combine to affect the behaviour of a process, when subjected to externally superimposed changes in responsibility.     

System dynamics in project management: assessing the impacts of client behaviour on project performance

The influence of client behaviour on a project is complex, including schedule restrictions on milestones, high demand on progress reports, delays in approving documents, and changes to workscope throughout the life-cycle. Quantifying these effects is important to project managers, in particular for effective communication with the client. Traditional planning and control tools have proved ineffective at providing quick and reliable information. Their tendency to incorporate more detail has increased their complexity, inhibiting practical strategic analyses. System Dynamics provides an alternative view in which these major influences are considered and quantified explicitly. This approach dispenses with much of the detail required by the traditional tools, but enables modelling of the systemic effects which traditional tools cannot model. The authors have developed a conceptual framework in which System Dynamics models are combined with traditional tools providing complementary support, and validated it in a large software project. This paper describes the use of this framework to assess and quantify the impacts of client behaviour. A practical example is discussed.     

Software Reviews

Sky Travel Commodore Business Machines 1200 Wilson Drive MasterType's Figure + Formulas The Scarborough System Enzyme Investigations Arrow Dynamics: The Programming Game Fraction Fuel-Up DLM Teaching Resources     

The relevance of system dynamics to engineering systems design

With the recent advent of new technology using micro computers for the centralised monitoring of information, the scope for totally automatic, real time control of large engineering systems has been advanced. We are entering a period which, retrospectively, may well be seen as the era of control; where for the first time it is both feasible and necessary to design system in terms of the way in which they will be operated, as well as in the traditional terms of their capacity requirements. However, before such comprehensive design can be undertaken compatible advances are required in information usage technology.The purpose of this paper is to demonstrate how the subject of System Dynamics can be used to assist with this problem, though its capacity to model information feedback and hence to model and test alternative system control rules based on the information retrieved. This type of application in the hard system area of engineering provides a strong contrast to the more usual applications of System Dynamics in softer socio-economic systems.The problem described is taken from the coal mining industry and related to the design of large scale underground conveyor belt systems used for the clearance of coal from mines. The demonstration presented, therefore, concerns research in this field, but has considerable scope for application in the general area of large scale bulk handling system.Of particular importance in the results is an indication of the potential savings in physical capacity which can stem from the careful design and implementation of control in such systems.     

A Model of the Dynamics of the Third World War — An Exercise in Technology Transfer

The paper discusses two scenarios for a Third World War in Europe, and argues that it is often convenient to supplement a scenario by a formal model. The problems of creating such a model are examined, and a model is formulated for land, air, and sea combat in Europe and the Atlantic, using the System Dynamics approach, which has not hitherto been widely employed for military analysis.The model confirms the results of the two scenarios, and its use for the analysis of alternative force configurations is illustrated. Some implications in the interpretation of Soviet military literature are discussed, and the paper ends with speculations on the role and value of such models.     

Das Elmikon,ein elektromechanischer Bildverstärker und Bildwandler

Summary Proceeding from some basic ideas of the known Eidophor System, the conception of the Elmicon, a new type of image amplified and converter, is derived. A picture signal influencesan electric field by its action on a photoconductor. The electric field itself produces deformations of a jellylike substance and controls in this way the light flux of a Schlieren system. Following a general discussion of the underlying ideas, the practical results hitherto obtained are reported.     

Using system dynamics models with litigation audiences

A litigation process involves many different parties. If models are used to support litigation, then there is a variety of audiences to which the model may be exposed. For example lawyers, members from the plaintiff's and defendant's organisations, expert modellers, arbitrators and judges. This paper discusses the experience of using System Dynamics models to support claims for compensation for time and cost overruns on large and complex projects. In this situation, it is argued that it is vital that the modeller understands how the different audiences will react to the models, otherwise the audience may dismiss the use of the model to support a claim for compensation. This paper discusses the nature of reactions to System Dynamics models by litigation audiences. These reactions highlight issues that the modeller faces when constructing a model. These issues need to be addressed so that the modeller can ensure that the model provides the support required to enable the client to optimise their chances of gaining compensation.     

The dynamics of the UK chemical plant investment cycle

Orders for new chemical plant (sanctions) and investment in chemical plant both show marked business cycle like variations. Amongst the effects of the UK cycle on the Chemical Industry are variations in: new plant additions, requirements for capital expenditure finance and capital utilization. As far as the UK Process Plant Contractors and Process Plant Manufacturers are concerned, the cycle is reflected in a varying work-load arising from the UK Chemical Industry together with varying manpower requirements and profitability.The project described in this paper involved the construction of both System Dynamics and Control Systems models of the Investment Cycle as a guide to strategic planning for the industries affected by it.The implications of the results from both types of model for corporate and strategic planning in the industries concerned are discussed.     

A Hypermedia-based Delphi Tool for Knowledge Acquisition in Model Building

The traditional Delphi method has been used for many years as an approach for knowledge capture and consensus building in a variety of social and managerial areas, including model building. This paper describes research into the development and initial application of a computerized version of the Delphi method to assist model building in situations where the domain experts to be consulted are large in number and geographically dispersed. Specifically, it has been developed to assist System Dynamics model building, where the purpose of the modelling was to help with the design and assessment of computer-based information systems. The features of a Hypermedia-based Delphi system, which was developed for the Apple Macintosh are described and the results of its application to a modelling exercise are discussed, with particular emphasis on its ability to create consensus influence diagrams and graphical relationships.     

Dynamical Systems with Multiple Time-Varying Delays: Stability and Stabilizability

This paper deals with the class of uncertain systems with multiple time delays. The stability and stabilizability of this class of systems are considered. System robustness is also studied when the norm-bounded uncertainties are considered. LMI delay-dependent sufficient conditions for stability, stabilizability, and system robustness are established to check whether a system of this class is stable and/or stabilizable. Numerical examples are provided to show the usefulness of the proposed results.     

系统动力学模型结构分析中表函数的改进方法

分析了非线性系统动力学(SD)模型中表函数环节的传统表示方法,指出该方法对于进行SD模型的结构分析所造成的障碍,并提出了用牛顿插值的承袭性算法来改进表函数环节的表示方法的思路.接着分别介绍了用差商和差分牛顿插值法改进表函数的过程.最后,通过一个实例说明了表函数改进的方法,并展示了以此为基础进行结构分析的思路.     

Systems weakend by failures

The ideas of a dynamic approach to the analysis of multivariate life length distributions, introduced in Arjas (1981a) and Arjas and Norros (1984), are developed further. Basic definitions are given in terms of prediction processes. Properties of martingales jumping downwards at failure times are studied. Finally, the spaecial case of a general multivariate exponential distribution is considered.     

Studying transition dynamics via focusing on underlying feedback interactions

The emerging need for societal transitions raises the need for a better understanding of the dynamic nature of large scale societal systems, and therefore the development of an analytical approach for drawing dynamic conclusions based on system’s dynamic mechanisms, feedback relationships and interacting components. The objective of this study is to explore the degree to which System Dynamics as an approach enhances the process of understanding transition dynamics in socio-technical systems. In other words, it is aimed to reveal the type of insights that can be developed about such systems and their dynamic behaviour using the approach, as well as the shortcomings of the approach in this challenging task. In order to do so, a modeling study aiming to understand the underlying mechanisms of the waste management transition in the Netherlands is conducted. The quantitative model developed is based on the historical case of the waste management transition of the Netherlands, and it portrays issues as the dynamics of actors’ preferences, development of infrastructure and environmental consequences of dominant mode of functioning and provides an instance for demonstrating and evaluating the feedback-focused perspective discussed in this paper. Finally, the paper discusses a set of points regarding the utilized approach, System Dynamics, observed during this study both in general and in the specific context of transitions. In short, System Dynamics stands as a promising approach mainly due to its strength in explaining the source of complex dynamics based on interacting feedback loops, but it also has certain drawbacks in the context of transitions.

工科数学试题库应具备的品质──来自用户的建议

工科数学试题库应具备的品质──来自用户的建议刘江国（郑州工学院）１工科数学试题库的意义和现状随着计算机应用的日益广泛和深入，计算机辅助教学（ＣＡＩ：ＣｈｌｌｌｏｕｔｅｒＡｉｄｅｄＩｎｓｔｒｕｃｔｉｏｎ）领域也呈现出方兴未艾的势头。在工科数学ＣＡｆ方面...     

Structural Analysis in the Dynamical Modelling of Chemical Engineering Systems

The dynamical modelling of physical (bio-)chemical processes based on first principles considerations is analysed from a structural point of view. Based on a classification of the variables and equations that occur in such models, we propose a general framework that can help to organise the model in a transparent way and to analyse efficiently its solv- ability properties. We show that a well-known tool in the theory of nonlinear dynamical systems, the Zero Dynamics Algorithm, can be used in the analysis of higher index mod- els and also in index reduction. The symbolic computations involved in this algorithm are readily available in the form of nonlinear system analysis packages. The proposed methods are illustrated by a few simple concrete examples. Keywords : First principles modelling, differential-algebraic systems, index reduction.     

The Effects of Design Changes and Delays on Project Costs

This paper describes a study of a large design and manufacture engineering project, undertaken as part of a Delay and Disruption litigation. Design changes and delays in design approval would have caused delay to the project; in order to fulfil a tight time-constraint, management had to increase parallel development in the network logic, reducing delay but setting up feedback loops that markedly increased total project spend. Cognitive mapping was used to elicit the relationships, which suggested the use of System Dynamics to quantify the effects. Results are described that show the effect of levels of design changes and approval delays, and their compounding effect. The wider implications on modelling projects are also discussed.     

Evaluation of a system design model

In this report we summarize the ideas behind and the results of the research project RASUT. The study includes comparison between different models aiming at evaluating the System Design Model introduced by the Swedish Standardization Institute. It has also been treated within ISO TC97/SC7, Design and Documentation of Computer Based Systems, and the corresponding Swedish committee.Computer Based Systems, and the corresponding Swedish committee.