The importance of social structures in analyzing a diffusion of ideas and innovations is widely acknowledged. This paper presents the first step in the construction of a system dynamics model to study social diffusion phenomena using network marketing as the specific structure through which products and services are spread. Network marketing organizations are direct-selling channels that recruit new distributors and form a particular type of social network which is shaped through time and based on preferential attachment. The paper presents a way to generate the topology of such a network so as to have the basis for analyzing the diffusion of products and services through such channels; a variant is introduced to an existing model developed with systems dynamics for generating scale-free networks with preferential attachment. We found that the resulting model generates an adequate network topology for analyzing essential characteristics of the way network marketing organizations are formed. This structure is the base for exploring the diffusion of products through such a business model; exploration of these processes constitutes the next step for this project.
The criminal justice apparatus is an example of a complex system; it can be conceived as a purposeful arrangement of heterogeneous and loosely interrelated actors whose missions are to enforce the law and to prosecute and rehabilitate offenders. This article explores the problem of the growing congestion of criminal cases in a recently implemented reform introduced by the Colombian government; in particular the focus is the criminal process as stipulated by the new accusatory system formally implemented in 2005. A simulation model of this new criminal process system was developed for the Corporation for Excellence in Justice (Corporación Excelencia en la Justicia). The paper depicts the main aspects of the model. It also offers selected analyses focused on the way that criminal cases are accumulated and evacuated through the main stages of the new accusatory system. The model shows that this system is largely driven by accumulations which provide a pervasive inertia. But what is more important is that such distinctive characteristic seems to be unnoticed for decision making processes. The paper underlines the importance of understanding the significant dynamics associated with accumulations and how this learning can be promoted through simulation.
The aim of this study is to 1) apply system dynamics approach in 7th grade middle school students in science and technology course, 2) determine the problems in field application, 3) improve the students attitude against course and some skills such as problem solving, understanding the causal relationship and graphing with analyzing the relationship, 4) provide an effective learning and teaching tools for students and teachers. Another aim of this study is to investigate how system dynamics approach help constructivism. The experimental design with pre-post test with control group is applied in this research. The study was applied with 81 students in middle schools in Istanbul / Turkey. Five assessment tools are used: "Science and Technology Course Attitude Scale", "Scientific Success Test", "Cause-Effect Relationship Scale", "Graphing and Analyzing Skills Scale", "Problem Solving Skills Inventory". Improvements due to system dynamics are observed in the tests that measure: scientific success, perceived problem solving skill, ability of undestanding graphics, ability of understanding causality relationships. However in the boundaries of the research, no improvements were observed in the following attitudes: perceived understanding of causality relationships, perceived graphics drawing and reading ability, perceived interest into science and technology course.
The system dynamics technique is one of the object oriented approach that studies and manages complex feedback systems. Its merits include the friendly and easily development and improvement of model. Its also used as a decision tool for engineering problems.In this paper, the system dynamics technique was used to simulate the performance of a drainage system in unsteady state condition. The model is capable to predict many hydrological parameters such as water table fluctuation, drainage discharge, upward flux, evapotranspiration, deep percolation, infiltration, runoff, soil moister content and unsaturated hydraulic conductivity on the basis of variation of soil moister content. All above parameters were investigated theoretically and their trends were found to be legible. The model was validated using observed experimental field data collected from amirkabir unit in sugar beet development plan located at khozestan, Iran. The observed data were water table level and drainage discharge. The standard error index was calculated to determine the agreement between the observed and simulated values of water table and drainage discharge. The results indicated that S.E. for water table and drainage discharge were 10.2 and 0.13 centimeter per day respectively.
Telecommunication industry is not comparable with many industries in view of rapid market and technological change. In this industry, Mobile Communications is one of the most attractive segments. The new and novel trends can be seen in Telecommunication industry from time to time which suggesting various dynamics and relationships in this industry development. In this article, we will examine and analyze existing trends in mobile operators services to find out the position of Value Added Service (VAS). Then, existing dynamics in delivering Mobile VAS will be deduced through VAS value chain analysis and its market characteristics. We will simulate and execute the proposed dynamic model and get acquainted with the behavior of model elements and analyze them. Finally, two policies will be suggested and with the analysis of results of these two policies, some recommendations will be made for mobile network operators to maximize their revenues out of VAS.
Recent movements towards a 'knowledge-based' view of firm have emphasized the importance of knowledge in enabling the firm to gain competitive advantage. Different dimensions of knowledge are explicated in the knowledge management literature such as explicit vs. tacit knowledge, internal vs. external knowledge, etc. Based on SECI model, firms create knowledge through social interaction between tacit and explicit knowledge. It is important for them to acquire external knowledge and combine it with internal knowledge to create new knowledge as well. Acquiring external knowledge is a very complex process and several scholars have considered this process from different perspectives. In this paper, we try to integrate these perspectives and propose a System Dynamics (SD) model for knowledge transfer and creation dynamics within an industry. Using this model, we can test the impact of knowledge strategy adopted by a firm on its success in different knowledge situations.
Although large developed System dynamics model can be applied on different ecological system in this paper it is applied on Kastela region in Croatia. The Computer Simulation Sub model of The Ecological Regional Subsystem of the "KASTELA BAY" is an extra relevant submodel of The System Dynamics Computer Simulation Model of the KASTELA BAY which has been developed with the help of System Dynamics. It is, in its essence, a continuous model because it is presented as a system of non-linear differential equations. At the same time, it is a discrete model, because it is presented as a system of linear differential equations (System Dynamics DYNAMO - software package). Its DT (length of intervening time = computation interval) is chopped in full accordance with the Sampling Theorem (Shannon and Koteljnikov). The System Dynamics Computer Simulation Model of the "Kastela Bay" also employs certain experience gathered by experts who had worked on the preparation of projects: "Blue Plan" and "The Methodological Basis for the Scenario of the Management of Natural Resources of the "Kastela Bay"" (1991).
We propose an Integrated Systemic Theory of Catastrophes (ISTC) using System Dynamics to model and to understand common systemic structures and behaviours of catastrophes. Current catastrophe research concentrates on a specific field and does not capture complex multi-field catastrophe scenarios that cannot be reduced to a single scientific field. For example, when looking at famines the elements of the relevant feedback loops belong to different fields of science (climate, precipitation, soil conditions, population density etc.) and no single of these sciences alone can identify the systemic structure generating famines. In this paper we introduce the concept of catastrophe archetypes that function as a central element of the ISTC. Catastrophe archetypes describe systemic structures responsible for catastrophes to occur and make underlying catastrophe dynamics visible that are normally not directly seen. Within the ISTC the catastrophe archetypes will be used as diagnostic-, planning- and theory building tools to explore catastrophes systemically.
The absorption kinetics of subcutaneously injected soluble insulin is unusual in that clinical experiments show that a slow initial absorption after a couple of hours is replaced by a significantly faster absorption. Moreover, experiments with different injection volumes and insulin concentrations demonstrate that there is both a volume and a concentration effect. The slow initial phase disappears if either the injected volume or the concentration of the injected insulin is reduced. On the other hand, in the limits of very low concentrations or small volumes, a tail develops on the absorption curve, representing a new type of slow process. A System Dynamics model of this absorption scenario was original developed in collaboration with the Steno Memorial Hospital. In spite of the fact that the insulin concentrations have increased by an order of magnitude, the model continues to correctly predict the absorption curves, and we are presently using variants of the model to explain the absorption curves for other insulin forms, some of which are bound to protein as they are injected or bind to protein as they enter the blood vessels while yet others are injected in crystalline form or precipitate immediately after the injection.