This paper tackles on instabilities and chaos which can occur in production systems whose organisation is based on the just-in-time philosophy. This could be a Kanban system which controls the production flows. In this case, cards or other manual and visual devices, accompanied by parts containers, signalise transfer and/or manufacturing operations thus acting as production orders. For instance, a worker, from an assembly line, needing more components, attaches a transportation Kanban to an empty parts container, that is moved to the previous work centre (according to routing procedure) where it is replenished (with new manufactured parts) and moved back to the assembly line.
As environmental considerations have to be incorporated into national energy planning, development countries must cope not only with reducing pollution, but also with solving more pressing issues which play a crucial role in their economic development processes: the alleviation of poverty; the control of population growth; the provision of adequate employment opportunities; the acquisition of food supplies; the satisfaction of energy requirements and other basic needs; and, the improvement of the quality of their human resource. Developing nations are faced with a major question: with those more basic and pressing problems, how will the developing countries cope with the emerging environmental problems? In particular, what are the implications of various energy strategy options to the general economic welfare and development of developing countries?
Managing a project and understanding the many system dynamics and feedback loops associated with a project is a formidable task. Creating schedules and tracking progress are two important activities for mangers. These activities become exponentially more complex and difficult for larger projects. Good managers possess an intuitive talent understanding how a system will behave when modifications are performed and make decisions using these skills and experience. However, when wrong decisions are made and implemented into a project, disastrous results could occur, reducing the probability of success. The larger the project, the more the feedback loops, the greater the dynamics, and the reduced probability of accurately predicting an outcome from modifications. Changing only one variable could effect the dynamics of a project with an unpredictable outcome. This is particularly true when considering all the system feedback loops associated with a project.
The sustainability of a Watershed (DAS) ecology depends on numerous factors, especially land and water availability. Transformations occurring on a DAS be seen from the forest opening in the upstream to the conversions of rice fields into settlements and industrial area in the downstream. These transformations determine the water cycle of a DAS, such as soil absorbency, thereby affecting the eiver's waterflow and quality. Mismanagement in the upstream area, in addition. may affect the downstream area. This paper is aimed to observe and understand the occurring transformation on DAS in Java Island- Indonesia, thus provide the basic considerations for well-managed DAS in order to minimize any possible negative impacts. System Dynamics program is applied to support the analysis.
Most community development work viewed as planning social change often involves or leads to conflict. The basic premise of conflicts is usually distribution of benefits in society, with one group seeking to maximize its potential. Social conflict is a behaviour threat by one party directed at the territory- rights, interests, or privilege- of another party. If conflict is seen as functional social process, one is likely to be committed to as a useful tool to achieve the change desired. This paper applies system dynamics as a tool for explaining social behaviour over time and integrating experimental learning in community development for social science students and community development practitioners. The lectures incorporate experimentation in computer-based learning for understanding theories and information relationships existing in social changes, social conflicts and development. The dynamics simulation model developed in this paper aims to study the community conflict in terms of territoriality, which helps in understanding what the problem is and who is causing it. Robinson's conflict cycle is applied as feedback system interacting with the actors-dominator, manipulator, mediator, compromiser, and avoider- in terms of participant's behaviour styles in the conflict situation. Students were evaluated to be energetic in discussion among themselves the strategies regarding conflict for approaching to community development, preventing it or managing and resolving it while learning and doing assignments.
The term ecosystem structure has been variously defined in the ecological literature. I prefer to use the definition proposed by Margalef (1963) Ecosystems have a structure, in the sense that they are composed of different parts or elements, and these are arranged in a definite pattern. For the purpose of this study, I define ecosystem structure as including the elements of the system (Odum 1962), the structure of their interactions (network design- Hill and Wiegert 1980), and the particular form of interactions (instantaneous flow rates- Hill and Wiegert's form). The structure of an ecosystem determines its behavior and functional attributes, including both nutrient recycling and ecosystem maturity, I hypothesized that certain ecosystem characteristics tend to co-occur based in similar casual factors in the underlying ecosystem structure. The purpose of this study was to test the hypothesis that tightening of the phosphorus and carbon cycles increases the stability of pelagic ecosystems to nutrients perturbation.
Many trends in computing- distributing processing, telecoms, reliance on computing for key business processes- combine to increase greatly the risks and vulnerability of firms to computer attack. The form of attack is also is also diversifying- mischief-making by "hackers" or virus writers, sabotage by disgruntled employees, fraudulent activity, or simple random hardware or software failure. The threats and potential costs to firms of breakdowns in security can be very large, involving the need to replace or re-engineering systems, to recover or reconstruct key information and data, and maybe even to try to re-establish goodwill with customers who may have been affected. The literature reflects that while the general issues here are appreciated, few firms understand fully the potential threats to their business, nor have explicit policies and procedures to guard against them.
Learning curves have been identified in a wide variety of industries (Dutton and Thomas, 1984) and the extensive theoretical literature has explored their strategic implications A learning curve creates a positive feedback loop by which a small initial market share advantage leads to greater production experience, lower unit costs, lower prices and still greater market share advantage. In general, the literature suggest that in the presence of learning curves - and when learning is privately appropriable-firms should pursue an aggressive strategy in which they seek to preempt their rivals, expand output and reduce price below the short-run profit maximizing level (Spence, 1981: Fudenberg and Tirol, 1983, 1986; Tirole, 1990). Intuitively, such aggressive strategies are superior because they increase both industry demand and the aggressive firm's share of that demand, boosting cumulative volume, reducing future cost and building sustained competitive advantage until the firm dominates the market. The desirability of aggressive strategies in industries with learning curves have diffused widely with business education, the popular business literature management texts, and public policy debates. (Rothschild 1990, Hax and Majluf, 1984; Oster, 1990; Porter, 1980; Krugman, 1990) and learning curve strategies appear to have led to sustained advantages in industires such as synthetic fibers, bulk chemicals, and disposable diapers (Shaw and Shaw 1984; Ghemawat 1984, Porter 1984), However in many industries including televisions, VCRS, semiconductor, toys and games, lighting equipment, vacuum cleaners, aggressive pricing and capacity expansion have led to substantial overcapacity and price wars that have destroyed industry profitability (Beinhocker, 1991; Salter, 1969: Porter 1980; Saporito. 1992; The Economist, 1991; Business Week, 1992).
Why are quality so successful in some firms but not in others? Some point to difficulties in implementation or leadership. The problem is more fundamental, however. Quality programs are tightly coupled with other functions, routines, and structures. Product development, marketing, accounting, systems, human resource policies, employee morale, pricing policies, and financial results are all affected by and in turn influence quality initiatives. We hypothesize that the productivity gains from successful quality programs can interact unfavorably with existing routines and structures. Under certain conditions these interactions may lead -or force-a firm to take actions that ultimately cause the demise of an otherwise successful program. Field study and formal models are used to test these hypotheses.
We apply a dynamic time-series method called Vector-autoregression (VAR) to studying the dynamic linkage between unemployment and crime rates in Virginia. The promise of the VAR methodology lies in its ability to provide information on the dynamic and the feedback properties in systems of variables.