In this study, by using system dynamics approach we aim to investigate the profitability of a company if it is engaged in remanufacturing, which is the most advanced form of product recovery. Our motivation is to find out whether investing in remanufacturing is advantageous for a company/sector in terms of long term profitability and, what should be the quality and price levels of the remanufactured and newly manufactured products. The model shows that a company involved both in new and remanufactured versions of the same product, endogenously generates interesting customer-base dynamics. Different from the studies in the literature that deal with micro level models, we analyze the effects of being involved in remanufacturing of electronic products on the profitability of the firm at macro level, by taking into account the government incentives for the firms that perform product recovery.
Service operations depend intensively on human resources because of their interaction with customers and suppliers and thus, training becomes a must in order to ensure higher performance. Knowledge Management (KM) may be looked as a framework for training programs since it addresses knowledge conversion from explicit and tacit knowledge. This paper proposes that dynamic simulation might be used as a tool to analyze training programs effectiveness from a KM perspective. Thus, a SD model was built using data from a customer support service of a software-house in Brazil. Three scenarios were considered, relying on the number of trainings per month. The main contribution of this work lies on shedding light over the intangible effects of tacit and explicit knowledge that support the effectiveness of training programs over organizational performance.
This paper addresses the challenge of identifying adequate theoretical starting points for problem oriented simulation studies of socio-technical transitions towards near fossil free energy services e.g. for housing and transportation. The identification of adequate starting points for simulation studies is becoming increasingly important for the generalization of simulation results as well as for theory refinement. We found that the Multi-Level Perspective (MLP) offers a helpful language for a modelling experiment based in a feedback perspective. This allows scientific conceptualization of a socio-technical transition challenge departing from an inter-subjective and hence scientific starting point. In addition feedback modelling appears to be a promising mathematical analysis approach that helps to substantiate the MLP. We have seen that the insights of the simulation experiment corroborate basics assumptions of the MLP concerning multi-level alignment processes but also discriminates the decisive determinants and governance mechanism that explain radical innovation and subsequently the creation of path dependency.
Over the past few decades, many studies of corruption have been carried out. These studies have mainly focused on specific characteristics such as: economic issues, legal issues, and social propositions. In this article we have described the concept of modeling corruption in Pakistan using a Causal Loop Diagram (CLD). Corruption represents a very dangerous social phenomenon observed in many parts of the world. However, its manifestation in a developing country is an especially destructive agent against human development. The System Dynamics (SD) approach has been extended in the past several years through its application to new problems such as modeling state instability, supply chain management, and analysis of different nation building policies. The main objective of this study is to develop a theoretical framework which can be used to study corruption dynamics by means of SD. The methodology employed is a case study. Semi structured interviews with key stakeholders such as: government ministries, donor agencies, judiciary, police departments, non-governmental organizations and the general public are done. On the basis of literature and social theory we have developed three preliminary CLD models of corruption. The data for the qualitative system dynamics analysis comes from 30 interviews conducted in (Islamabad) Pakistan.
This paper explores the Agile software development methodology to discover the essence that has enabled it to prosper and grow since the declaration of the Manifesto for Agile Software Development in 2001. Examined is the role of feedback in the Agile methodology and its relationship to single and double loop learning.
The desire to better understand the transmission of infectious disease in the real world has motivated the representation of epidemic diffusion in the context of quantitative simulation. In recent decades, both individual-based models and aggregate models (such as System Dynamics) are widely used in epidemiological modeling. This paper com-pares the difference between aggregate models and individual-based models in the context of Tuberculosis (TB) transmission, considering smoking as a risk factor. The merits and impact of capturing individual heterogeneity is examined via representing Bacillus Calmette-Gurin vaccination and reactivation in both models. The simulation results of the two models exhibit distinct discrepancies in TB incidence rate and prevalence. Results also suggest that, at the level of practical application, individual-based models offer significantly greater accuracy and easier extension, especially when representing a decreasing reactivation rate, waning of immunity and heterogeneous individual at- tributes. Another experiment sought to evaluate the impact of network structure on TB diffusion. Simulations are conducted under three widely used network topologies, namely random, scale-free and small world. The results reveal large differences between results of individual-based models and aggregate models, which further give insights into the difference between these two model types in the context of practical decision-making.
Over the next several decades, population trends sweeping across the world will challenge cultural traditions, health systems capacity, and social infrastructure. As average age of populations increase, health care needs change from acute to chronic. Of all the causes of age-related dependency, dementia presents a particular problem: the elderly with dementia have extensive care demands and, as their dementia progresses from mild and moderate to severe, institutionalization becomes more likely. Our research applies system dynamics methodology to estimate future population-level severity of dementia and the challenges of age-related dementia to family and community infrastructure.
Indonesia, through a state-owned aircraft industry named PT. Dirgantara Indonesia (PTDI), is trying to develop its national capacity in aerospace industrial technology. The strategy being thought to realize this objective is to build the aerospace supply chain industries through which the Small & Medium Enterprises (SMEs) can take a role in the global aerospace supply chain industries in the near future. As a main focus for this purpose, the Quality Management Systems (QMS) like AS 9100 has to be internalized in the SMEs; because, in reality, the Indonesian SMEs have not yet been experiencing with the quality requirement. Therefore, it is important to simulate the QMS learning process in the SMEs through an outsourcing collaboration between PTDI and SMEs. To simulate the learning process, a system dynamics model of knowledge development is constructed based on the inter-organizational learning dynamic model developed by Otto and Richardson (2004). A modification of the original model is made to accommodate an assistance mechanism for SMEs learning process in order that the QMS knowledge and experience of SMEs is adequate enough prior to the outsourcing partnership with PTDI. This study shows that the assistance is very important for SMEs those have not adequate prior knowledge and experience in QMS to increase their knowledge level.
This paper presents a soft landing model and a related control heuristic. The aim of this modeling effort is to represent the process of landing a spacecraft on the surface of a celestial body. This problem is known as the soft landing problem because crashing the spacecraft to the surface should be avoided. At the same time, long landing period necessitates extensive use of fuel, which should also be avoided. Consequently, the main goal in soft landing problem is to land the spacecraft as gently and as fast as possible. We adapted a control heuristic from the mass-spring damper model. According to the initial simulation runs, the adapted heuristic is successful in landing the spacecraft.
This paper introduces system dynamics approach to the domain of psychiatric research. We have tried to develop a computer simulation model based on theoretical findings and facts known to clinicians and looked for an answer to the problem of different cortisol reactivity between major depression and PTSD patients with respect to trauma severity, length and proposed genetically based differences in hippocampal volume. Modeling PTSD and depression in one structure is to our knowledge the first attempt to grasp these widely spread disorders with substantial societal and clinical burden. Even though the current model structure is simplified, proposed approach has a powerful predicting potential in clinical practice and social policy. Model structure and model equations are in Appendices 1 and 2.