The study of system dynamics starts from model construction and simulation to understand and solve dynamical complicated problems. Traditionally approaches of modeling process depend on an expert¡¦s experiences and the trial & error procedure. Chen¡¦s research proposes a transformation method that could map a System Dynamics Model (SDM) to a specially designed Partial Recurrent Network (PRN). Thus he could use the neural network training algorithm to assist model construction and policy design. In this paper, we will introduce a Genetic Algorithm (GA) in the model building process, which encodes a PRN into a string and uses an evolution process to select a best solution. The algorithm not only improves the PRN training, but also generates more candidate models for consideration. Thus, it enhances the SDM-PRN transformation¡¦s usability.

Providing care services across several departments and care givers creates the complexity of the patient pathways, as it deals with different departments, policies, professionals, regulations and many more. One example of complex patient pathways (CPP) is one that exists in integrated care, which most literature relates to health and social care integration. The world population and demand for care services have increased. Therefore, necessary actions need to be taken in order to improve the services given to patients in maintaining their quality of life. As the complexity arises due to different needs of stakeholders, it creates many problems especially when it involves complex patient pathways (CPP). To reduce the problems, many researchers tried using several decision tools such as Discrete Event Simulation (DES), System Dynamic (SD), Markov Model and Tree Diagram. This also includes Direct Experimentation, one of techniques in Lean Thinking/Techniques, in their efforts to help simplify the system complexity and provide decision support tools. However, the CPP models were developed using a single tools which makes the models have some limitations and not capable in covering the entire needs and features of the CPP system. For example, lack of individual analysis, feedback loop as well as lack of experimentation prior to the real implementation. As a result, ineffective and inefficient decision making was made. The researcher also argues that by combining the DES and SD techniques, named the hybrid simulation, the CPP model would be enhanced and in turn will help to provide decision support tools and consequently, will reduce the problems in CPP to the minimum level. As there is no standard framework, a framework of a hybrid simulation for modelling the CPP system is proposed in this research. The researcher is much concerned with the framework development rather than the CPP model itself, as there is no standard model that can represent any type of CPP since it is different in term of its regulations, policies, governance and many more. The framework is developed based on several literatures, selected among developed framework/models that have used combinations of DES and SD techniques simultaneously, applied in a large system or in healthcare sectors. This is due to the condition of the CPP system which is a large healthcare system. The proposed framework is divided into three phases, which are Conceptual, Modelling and Models Communication Phase, and each phase is decomposed into several steps. To validate the suitability of the proposed framework that provides guidance in developing CPP models using hybrid simulation, the inductive research methodology will be used with the help of case studies as a research strategy. Two approaches are used to test the suitability of the framework – practical and theoretical. The practical approach involves developing a CPP model (within health and social care settings) assisted by the SD and DES simulation software which was based on several case studies in health and social care systems that used single modelling techniques. The theoretical approach involves applying several case studies within different care settings without developing the model. Four case studies with different areas and care settings have been selected and applied towards the framework. Based on suitability tests, the framework will be modified accordingly. As this framework provides guidance on how to develop CPP models using hybrid simulation, it is argued that it will be a benchmark to researchers and academicians, as well as decision and policy makers to develop a CPP model using hybrid simulation.

The aim of this thesis is to explore the diversification of a major oil company into the. petrochemical business and then through thorough analysis to recommend the appropriate corporate strategies to be followed by the petrochemical subsidiary of such a company in the 1980's and the 1990's. The petrochemical industry has undergone great changes during the last decade. In the early 1970's it entered a new era of maturity, however due to the misplannings of the late 1960's extending to the early 1970's the industry was suddenly faced with significant overcapacity which has persisted to the present date and is expected to last well into the 1980's. The 1974 oil crisis caused a further decline in the growth of demand, hence exacerbating the situation. During the seventies the industry has had to operate under increasing material prices, unlike the past, which when coupled with the problem of overcapacity and the resulting deterioration of prices, has caused considerable decline in the financial ability of the companies to finance their capital expenditure programmes through internal cash generation (which was the case in the industry's 'golden era'). This situation is threatening the long term viability and survival of the petrochemical businesses. A System Dynamics model for a hypothetical petrochemical subsidiary of a major oil company has been constructed which embodies all the policies inherent in such a system. The dynamic behaviour of the model closely resembles that expected from the real system such as the declining financial ability, which is mostly due to the inflationary conditions. Through thorough analysis, the impact of varying inflation level on the performance of the system was explored, and the need for adopting suitable accounting policies which would take account of the replacement costs of assets, during periods of high inflation, was proposed. The adoption of a number of policies led to a certain degree of improvement in the financial performance of the system, and these are recommended concerning the corporate strategy of the company for the next two decades. Finally it was discovered that due to the low level of growth of demand (compared to the past), the large economic sizes of the petrochemical plants and the market share consensus, the companies will have to go into joint ventures in the future.

Necrotic enteritis (NE) caused by Clostridium perfringens type A is an important bacterial enteric disease of global broiler production. However, the dynamic interactions of NE and its predisposing factors are not fully presented by current studies. By using the System Dynamics (SD) Model, the epidemiological changes in susceptible-infected-removed models of NE and avian coccidiosis and their interactions in one or multiple grow-out cycles was established; meanwhile, the growth performance was measured by the average weights of infected and non-infected populations at harvest were estimated. The SD model provided direct and persuasive outcomes of the epidemiology and ecology of NE compared with models using statistical methodology. With interventions on certain predisposing factors of management practices and medication, effects which decreased disease incidence and growth performance were observed; moreover, the leverage points obtained from interventions on certain management practices provided quantitative results which were applicable and useful for improving the broiler production.

The aim of this thesis is to explore the diversification of a major oil company into the. petrochemical business and then through thorough analysis to recommend the appropriate corporate strategies to be followed by the petrochemical subsidiary of such a company in the 1980's and the 1990's. The petrochemical industry has undergone great changes during the last decade. In the early 1970's it entered a new era of maturity, however due to the misplannings of the late 1960's extending to the early 1970's the industry was suddenly faced with significant overcapacity which has persisted to the present date and is expected to last well into the 1980's. The 1974 oil crisis caused a further decline in the growth of demand, hence exacerbating the situation. During the seventies the industry has had to operate under increasing material prices, unlike the past, which when coupled with the problem of overcapacity and the resulting deterioration of prices, has caused considerable decline in the financial ability of the companies to finance their capital expenditure programmes through internal cash generation (which was the case in the industry's 'golden era'). This situation is threatening the long term viability and survival of the petrochemical businesses. A System Dynamics model for a hypothetical petrochemical subsidiary of a major oil company has been constructed which embodies all the policies inherent in such a system. The dynamic behaviour of the model closely resembles that expected from the real system such as the declining financial ability, which is mostly due to the inflationary conditions. Through thorough analysis, the impact of varying inflation level on the performance of the system was explored, and the need for adopting suitable accounting policies which would take account of the replacement costs of assets, during periods of high inflation, was proposed. The adoption of a number of policies led to a certain degree of improvement in the financial performance of the system, and these are recommended concerning the corporate strategy of the company for the next two decades. Finally it was discovered that due to the low level of growth of demand (compared to the past), the large economic sizes of the petrochemical plants and the market share consensus, the companies will have to go into joint ventures in the future.

This study is based on Porter¡¦s five forces model of competition. It combines system dynamics theory to make Porter¡¦s five forces model be simulated by dynamic system model and then the strategy can be simulated by computer. With this strategic experiment, the industry analysis or industry strategy can be simulated and experimented just like in the laboratory and make the forecast in the future be achievable. The conclusions of this study are presented as follows: 1.The five forces in Porter¡¦s five forces model can be expressed and quantified by combination of each two forces. 2.The Porter¡¦s five forces model is not strong enough to cope with the dynamic, twinkling and changeful environment. But it can be compensated by system dynamics theory. 3.Combining the system dynamics theory and Porter¡¦s five forces model, the relationship between every two forces can be transformed into cause-and-effect chain. The total forces among five forces can be expressed by system feedback circle. 4.After combination of the system dynamic theory and Porter¡¦s five forces model, we can use the iThink software to simulate the combination. It makes the unquantifiable force change be able to be simulated and forecasted. The conclusions above are significant to the study in the following aspects. 1.The ten forces relationship of Porter¡¦s five forces model can be expressed by cause-and-effect chain in system dynamics theory. 2.The pull-and-push relationship of the ten forces combination in Porter¡¦s five forces model can be expressed by system feedback circle. 3.The mutual and active forces in the system dynamics can be quantified, simulated and forecasted.

The concept of the circular economy has been introduced to China and encouraged to be implemented in manufacturing industries by the government in recent years. The implementation of a circular economy in the mobile phone product system can potentially serve as a solution to reducing a significant amount of waste mobile phones. However, the development of a circular economy in China is still at the beginning phase. To help with the promotion of a circular economy, this thesis was proposed. The aim is to explore the possibility to promote a circular economy in the mobile phone product system in China and the main target group is mobile phone producers. The main methodology of this thesis was system dynamics modeling. A system dynamic model was developed to analyze the potential sustainability profits and economic profits. A questionnaire and a literature review were conducted to collect relevant data for the model. The study proposed three strategies (old-for-new, eco-design, and product service system) for producers to promote a circular economy. The profitability of the three scenarios was evaluated and then a sensitivity analysis of the parameters in the model was conducted. According to the model results, the old-for-new strategy was the most profitable and the strategy of the product- service system could not bring additional profit to producers if only economic profits were considered. The general suggestion for producers on maximizing the profitability was propagandizing the significance of mobile phone collection and recycling to increase consumers’ awareness.

This thesis is focused on dynamics of soft factors influencing workers during projects. These factors include motivation, workplace atmosphere, team synergy of workers and their emotions, and attribute of project manager who manages the project. Identification of soft factors and their relationships was achieved by examination of scientific literature in psychology and system dynamics. Description of managing project matters was achieved by examination of scientific literature dealing with project management. The main objective of this thesis is to create a dynamic model which simulates behavior of these soft factors influencing the project staff. The primary metric of the model is efficiency of workers participating on the project based on input parameters. Validation of the model was achieved by verification of historic behavior of key elements. Results of validation experiments correspond with historic behavior with roughly 95 % accuracy. At the end of this thesis is presented an ICT project case study. Based on the results of simulation experiments is performed a scenario analysis which tries to bring possible suggestions for project management.

This diploma thesis is focused on the application of a system approach, which was configured by the author. Configured approach was used to analyze project of implementation of data warehouse tool. Dynamics of the project delivery system was shown by causal loop diagram and then by system dynamics model. Thesis defined and used terms like system, system complexity, system approach, system approach configuration, causal loop diagram, system dynamics model, system archetype of shifting the burden, data warehouse and its definition against a database definition, project, project organizational structures, methods and their necessity in implementation of information systems projects, feasibility of the information system projects and problems with measurement of project performance. Time-proportional simulation of system dynamics model quantified effects of factors and also quantified different results of project implementation approaches. Based on the analyzed project was provided a brief general recommendations for information systems projects.

<p>The aging water infrastructure system in the United States has posed considerable hindrance to policy-makers as they seek to provide safe, reliable, and clean drinking water for communities. The deterioration of the physical water infrastructure negatively affects the economics of water utilities and can lead to increases in water rates for consumers, so that utilities can recover the financial losses. However, the dynamics emerging from the interactions among changes in water service reliability, water-rates, consumer behavior (with respect to water consumption and willingness to support water-rate changes in response to changes in water rates, and water utility economics, are still unknown factors in the management of water infrastructure systems. </p> <p>The overarching objective of this dissertation is the creation and demonstration of the dynamics of coupled human and water infrastructure systems under conditions of water main breaks and water-rate increases. First, using water-main break data for a 21-year period from two U.S. cities in the Great Lakes region, the dissertation demonstrates a methodology to estimate the system-wide monthly frequency of water main breaks as a function of a number of explanatory variables. Using a random-parameters negative-binomial approach, the statistical estimations show that pipe diameters, average pipe age, distribution of pipe age, pipe material, time of year, and mean monthly temperature all have a significant impact on monthly water main break frequencies. The results can assist asset managers in quantifying the effect of factors may have on the likelihood of water main breaks, as well as in making cost-effective decisions regarding pipe renewal.</p> <p>Next, by incorporating qualitative survey data and using quantitative econometric methods, consumer behaviors in responses to the water-rate increases, and based on perceptions of water service reliability and quality in a Midwestern U.S. city was evaluated. Using a multivariate binary probit approach, the results provide insights as to how individuals are likely to respond to water-rate increases based on the reliability of current water services and the quality of the supplied water. The outputs of the econometric enable utility managers to better understand the behavior of consumers under different rate conditions and help water utilities in their long-term and short-term financial analyses.</p> <p>Finally, the aforementioned two components are integrated into the interdependency analysis to evaluate the interactive effects of features of the physical water infrastructure (pipeline characteristics, water and associated energy losses, and the revenue loss for water utilities) and the behavior of stakeholders (water utilities and consumers). The developed hybrid system dynamics and agent-based model examines interdependencies between the physical water infrastructure, the water utility, and the water consumers to explore possible emergent behavior patterns of water users during water rate increases over time. The model is demonstrated over the 2001–2010 period on a case study city with a large water distribution system that includes 4,000 miles of pipeline and nine water treatment plants serving a population of 863,000. This model was then verified and validated throughout the development of simulation models and included the following steps: 1) data validity, 2) conceptual model validity, 3) computerized model validity, and 4) operational validity. The results suggest the simulated behavior of the model was reasonable and the output of the simulation model regrading water main break frequency, amount of water and associated energy losses, generated revenue, and payoff periods for implementing proactive maintenance strategies had the accuracy required for the model’s intended purpose. </p> <p>The framework developed in this doctoral study can be applied to different size classifications of cities, as well as different classifications of utility companies (such as electricity and gas) by updating the parameters in the model to reflect the characteristics of the infrastructure system components. The distinctive methodological approach in this doctoral work could capture the emergent behaviors of human-water infrastructure interactions such as the impact of increasing water-rates on residential consumers, the impact of water price elasticity cascading into the water utility revenue, and the impact of residential consumers’ water consumption on water utility revenues. In conclusion, the results of this doctoral research can assist asset managers in understanding their systems, identify pathways for growing revenue through reducing non-revenue water and increasing water-rates, and implementing a proactive pipeline asset management program towards the provision for safe, reliable, and clean drinking water.</p>