This paper aims to introduce System Dynamics (SD) in applying Drum Buffer Rope (DBR) methodology of Theory of Constraints (TOC) in a three-stage flow shop system that produces a single product. To the best of our knowledge, although there are a lot of TOC applications using discrete simulation in production scheduling with DBR methodology, there are not any TOC application of DBR methodology in production scheduling using System Dynamics.
This paper presents progress on the conceptualisation and implementation of an extended version of Ford's behavioural approach to feedback loop dominance analysis. The need for the extension of the original method is discussed, as are the methodological consequences of changing and implementing the method.
The Mexican auto-parts industry nowadays has a high dependency from the importation of raw materials and auto parts made in USA, China and Japan and some other countries from which it get supplied for the development of productive processes. Many of this importations can be substituted is the necessary mechanisms to produce in a national level get established, bringing an increase of the auto-parts industry and more competitiveness from Mexico in global scenarios.
Massively Multiplayer Online Games (MMOGs) are popular worldwide. Especially in Korea, there were about 19 million gamers in 2006. Some players have become seriously addicted to online games, causing a serious social problem. However, studies and/or trials to address game addiction problems have rarely been performed. In this paper, we discover the relationships among interested parties in the game industry and propose a base model to explain them. From the base model, we can expect that casual gamers increase until some time, but decline afterward. The growth rate of total revenue of online game decreases due to a reduced number of casual gamers over time and a negative image of online games. To resolve game addiction problems, we implemented a self regulation policy and a tax and rebate policy in the base model. After applying the policies, we found that a tax and rebate policy is preferable to a self regulation policy. The total revenues of online gaming increases contrary to the concern of game companies, the social image of online games is improved and the number of game addicts decreases.
The main concern of strategic management today is the controlling of the interactions between the organization and its environment as this constitutes a highly complex system of interrelated parts. The solution to this problem lies on understanding the underlying structure of the organizational-environmental system with all its possible observable manifestations in constructs and quantifiable variables as well as the steering possibilities or decision rules that this structure allows. This requires the drawing of the patterns of interaction of a large number of important variables. In this paper we argue that by combining the strengths of two prominent planning methodologies, which belong to different and to somewhat conflicting paradigms and modeling schools, we may indeed produce a single more effective planning framework. We proceed by outlining the strengths and limitations of the two approaches namely PIMS and System Dynamics and then drawing on the complementarities we integrate them into a single composite strategic planning framework. The PIMS/SD inter-paradigm composite planning model is finally evaluated across theoretical conditions and practical relevance criteria.
In system dynamics methodology, formal output analysis can create a basis for improving the structure, so it is important to determine the variables to which the model is sensitive, by using a formal experimental design method. Moreover, such a research can allow comparing different methods for parametric sensitivity analysis. The purpose of this study is to understand different reactions of real estate prices to changes in different input factors. The study is carried out on a system dynamics model previously developed by the authors on real estate prices in Istanbul. The sensitivity of period, amplitude and mean of price oscillations to the changes in some selected variables of the model are analyzed. Two experimental sensitivity analysis designs, namely fractional factorial design and Latin hypercube sampling are used to measure the sensitivity of the model. The study shows that the factors that turn out to be most significant in the two designs are not the same. But the factors and interactions found significant by both techniques can be safely assumed to be highly influential.
Conceptually, the level of funding of higher education activities is directly proportional to its strategic directions/implementations and hence quality. In developing countries, these dependencies are far from straightforward due to ad-hoc reactions to reduced funding. This paper contributes to the development of tools for this management challenge. We investigate the dynamics of higher education funding and ensuing impact on part-time teaching, staff to student ratios, staff development, research productivity, and ultimately the perceived quality, using a system dynamics simulation model. The model developed is based on higher education literature in the developing world in general and Uganda in particular. We use the resulting model to review policies on funding and quality in higher education, and ultimately envisage that the model can easily be adapted to higher education in other environments.
System Dynamics deals with modelling processes over time. In this paper we discuss two ways to model changes over time: finite vs. infinitesimal. This leads to two different concepts of time: discrete time as a succession of time points and time intervals vs. continuous time. Although the System Dynamics concept of distinguishing between stocks and flows suggests a discrete modelling of time, SD is considered mostly a modelling technique based on continuous time. In the paper we argue to see SD modelling compatible with both the continuous and the discrete concept of time. We will show that this hybrid potential makes SD a superior technique for modelling time, which combines the advantages of continuous and discrete time concepts.
Theory can inform us of the differences between principles and methods used to build System Dynamics and Agent Based Models. However, little is known about how the paradigms are applied in practice and the subsequent difficulties encountered. In order to assist the model developer in applying currently established methodologies, it is first necessary to examine what occurs in practice. This paper reports the conclusions of an assessment study of four different simulation projects, two of which used System Dynamics, and the other two Agent Based Modelling. Results highlight the methodological issues faced when building models with both paradigms. Furthermore, the results suggest that the more mature modelling paradigm of System Dynamics can assist in improving Agent Based Model building processes.
Reserves estimations in natural gas markets are fundamental for decision making of private and public agents. When markets are mature, market signals such as demand growth, costs, and price expectations activate exploration and new reserves are continually added to the proven reserves base. We can describe the process of discovering new reserves in a market with a simple dynamic hypothesis in which investment in exploration eventually leads to increase proven reserves while probable reserves decrease. The simple dynamic hypothesis, however, does not seem able to explain the large reserves additions occurring in immature markets. In immature markets it is frequent to discover large natural gas reservoirs independently of the degree of exploration activity. Instead of rejecting our simple dynamic hypothesis, we broaden it by including discoveries as a stochastic component, aiming to capture some of the major uncertainties observed in immature natural gas markets.