The residential building environment accounts to a large extent for the emission of greenhouse gases. In Switzerland, 27% of the carbon dioxide emissions are generated by heating houses and providing warm water and electricity. The employment of existing state of the art energy efficient technologies can reduce these emissions significantly. Why are the technologies not applied on a regular basis? In this paper, we focus on the decisions the individual building owner has to make during the house planning process. The papers contribution is multifold: systematization of important decisions during the planning process, development of a static theory of decision making based on psychological action theories, enrichment of the static theory by empirical research, and development of a dynamic theory. From a superior content point of view, the paper sheds light on the decisions during the building planning process. From a methodological perspective, the paper adds to more traceability during the model conceptualization phase. In other words, the art of modeling is partially substituted by a rigorous, scientific research process. This paper is still under development; especially the formulation of the system dynamics model and the subsequent discussion will be developed further in following versions of the paper.
The residential building environment and the belonging values creation network consisting of several in-terdependent actors has not obtained much attention from the field of science. Even though much litera-ture exists about the diffusion of innovations (e.g., Rogers 1995), the diffusion process of innovations in the residential building system is not fully understood. Hence, the enormous potential to reduce CO2-emmsions can not be utilized. In Switzerland, a research project tries to elaborate the different processes in the building environment in order to provide policy interventions based on a system dynamics model. Based on this research project, we present the interconnections between the different actors in the system. Thereby, we want to depict the inner life of each important actor group via a details simulation model. In the current version of the paper, only some details about the individual building owners can be provided. For the other actors, empirical survey research is in the process of being executed, after the completion of which dedicated models can be presented, different policies tested and implications discussed.
The paper deals with one of the oldest and still most pressing issue in system dynamics: when to map and when to model. We propose a heuristic to be used in system dynamics projects to give an indication whether one should aim at quantitative modeling (i.e., the classical system dynamics approach) or whether qualitative treatment will be sufficient: (1) If the problem definition phrase starts with the word why, often causal explanations for the development of variables should be the result of the project; in this case, the exploration of dynamic behaviour needs the application of quantitative simulation models because of the difficulties people have with inferring dynamics from complex models; (2) If the problem definition phrase starts with the word how, the structure of a system is asked for; then, the result of the project is usually a graphical representation of the shared understanding of team members about the structure of a system, which can be achieved by using qualitative modelling techniques like causal-loop diagrams, hexagons, or policy structure diagrams.
The paper presents and discusses the distinction between inductive and deductive System Dynamics modeling. Findings are that the distinction between inductive and deductive modeling is helpful in appropriately setting up, conducting, and evaluating System Dynamics projects. The discussion is based on a literature review, conceptual considerations, and the insights gained from case studies, both within business and academia. Implications are different processes, different potential outcomes, and different possibilities for implementation for the two modeling approaches. The value of the paper lies in a new perspective on the most relevant question, why some System Dynamics projects thrive while others fail.
The Critical Infrastructure Protection Decision Support System (CIPDSS) project has developed a risk-informed decision support system that provides insights for making critical infrastructure protection decisions by considering many critical infrastructures and their interdependencies. Since program inception the project has demonstrated how the CIPDSS can assist decision makers in making informed choices by functionally representing key critical infrastructures with their interdependencies, and computing human health & safety and economic impacts. The method of delivery to date has involved the conduct of analysis by the project developers and delivery of the results in the form of reports, often supplemented with face to face interactions with sponsors and decisions makers. This approach benefits from having the analysis conducted by the developers who best understand the underlying models and their limitations. However, this mode of delivery can be said to live more distant from those who might best benefit from being exposed to the analysis and the inherent trade-offs therein. This paper describes the development of a desktop simulation designed to help bridge this gap between the CIPDSS analysis and decisions makers. To illustrate the utility of this approach, an application focused on controlling infectious disease outbreaks, such as Pandemic Influenza, has been implemented.
While nonprofit organizations and their brands are growing in importance and stature, these organizations display surprisingly limited brand management activities. This is partly due to the fact that no explicit brand equity models exist specifically for nonprofit organizations. The aim of this research is to build a formal model of brand equity for international nonprofit organizations engaged in development, advocacy and relief work, using a combination of a system dynamics approach and grounded theory development. In doing so, we hope to contribute to the system dynamics literature by illustrating the step-by-step process of building a model from actual case studies rather than the traditional approach of literature review. Based on in-depth field work in three organizations (Care, Oxfam, and World Vision), two waves of focus groups with 18 brand managers led to the derivation and validation of a formal brand equity model. At the heart of this model are four core variables (Consistency, Focus, Trust, and Partnerships) and their associated causal loops. As such, this research constitutes a significant attempt to advance our understanding of brand equity in nonprofits through modeling, and to demonstrate the effective use of system dynamics in areas of marketing that have traditionally not considered this methodological approach.
A nonlinear approach to game theory has been designed to resolve two of its major problems: The
arbitrariness of valuing cooperation greater than competition in determining social welfare; and the
lack of interdependent uncertainty. The approach is to develop quantum or bistable agents and
relationships. The quantum approach means that agents in relationships are more likely to be found in
bistable states that correspond to their observation-action or energy-time levels; e.g., the more
complex, competitive, or conflictual the state, the greater the energy required but also the less time
available to enact an action. In our view, games are initialized, evolved to a state that solves a target
problem, then measured, consequently creating a measurement problem. In past research, we have
resolved the measurement problem. The measurement problem led to the development of metrics that
have been applied to organizations in the field (we briefly illustrate an application to military Medical
Department Research Centers). In this paper, we focus on modeling control in bistable close and market
relationships to produce evolvable systems.
In Avalanche a rod is lowered to the ground, team members staying in contact throughout. Normally the task is easy. However, with larger group sizes counter-intuitive behaviours appear, including the objects ascending.
A formal theory for the geometric element and other human behaviour effects gives insight into the behaviours. Each player has two balancing loops, one involved in lowering the object, the other ensuring contact. For more players these loops interact and these can allow intermittent dominance by reinforcing loops, causing the system to chase upwards towards an ever increasing goal.
Analysis indicates that there is only a narrow region in which the system is able to move downwards. An analogy is drawn between the co-operative behaviour required in this system and Prisoners Dilemma situations. Sensitivity analysis gives further insight into the systems modes and their causes. Reflections on the benefits of formal theory building close the paper.
Managing endangered species populations is a complex task demanding integration of knowledge across many disciplines, spatial and temporal scales, and ranges of human impacts. Computer simulation models can be useful in these efforts. We describe an ecosystem-level model for simulating population dynamics of the Rio Grande Silvery Minnow (RGSM; Hybognathus amarus) in the Rio Grande of central New Mexico. The model includes numerous variables which can be set by the user for different and in many cases uncertain minnow life history traits, impacts on mortality, and environmental conditions. Sensitivity analyses were conducted on the models output as a way of testing the robustness of the model, gaining insights into RGSM population dynamics, and identifying important data gaps. The model returned biologically reasonable results consistent with currently limited understanding of RGSM population dynamics. Some results were completely predictable (e.g., good fertility and mortality data are the most important variables for understanding population dynamics), and some offered useful insights (e.g., current captive release programs may have little impact on long term population dynamics, but may prevent short term extinction).
This paper describes how the Threshold21 Model developed for the Government of Mali has been used to support the preparation of the five-year strategic plan for the country. The model proven useful at different levels in the planning process: (1) it enabled testing the coherence of data collected; (2) provided insights into the future development of current issues and the emergence of new challenges in the Business-As-Usual scenario; (3) supported the discussion of alternative policies and development paths; and (4) provided a basis for monitoring and evaluation of implemented policies. This paper reports of the use of the model at levels (2) and (3), describing how it enabled an open discussion on the critical assumptions for economic growth to be used in the strategic plan, and on the delays involved in the countrys growth process. Results from the model have been eventually incorporated in the national strategic plan.
The service industry has grown considerably in the last century and investments in operational improvements have increased. Operational investments decisions have a huge impact on the profitability of the organization not only at present but also in the future affecting the sustainability of the organization. The service-profit chain is a framework that brings together several components in the service delivery process. Evaluations of service operations based on the service-profit chain and others have taken a static approach without any consideration to the feedback structure. We develop a system dynamics model to evaluate the impact of number of courses offered on profitability of training services. This is accomplished by incorporating an optimization structure using the hill-climbing algorithm. The results from the simulation are then discussed along with validation of the model.
This paper offers a computational model of profit-driven communication, when information-processing capacity of recipients is limited. Even though the model was inspired by the present situation in the direct online marketing industry, it has a wide applicability. In the model, profit-seeking communication firms exploit freely-available attention of recipients, while recipients allocate their limited cognitive capacity between competing tasks. We run numerical experiments to test various technical, market and regulatory proposals that aim at improving the social outcome. The paper makes a theoretical contribution to the economic literature and it also elucidates the current public policy debate about direct online marketing industry.
The UK health and social care systems are continuously changing over time. Other authors have previously put a strong case for usage of system dynamics (SD) in this area largely because SD address issues of system complexity and identification of feedback loops, resulting in a greater insight into this problem situation.
This paper presents research carried out in two areas of SD, firstly the conceptualizing of a problem and secondly the building of a SD model related to the dynamic problem of bed blocking in the UK health and social care domain. A case study approach has been applied to a hospital discharge department and elderly wards in a main UK hospital.
This paper provides a useful insight into issues that have occurred when conceptualizing and formulating a health and social care SD model. System behavior has been discussed as has the use of causal loop diagrams and stock and flow diagrams. Causal loop diagrams and stocks and flows have shown to play a useful part in overcoming SD difficulties. SD has proved to be a useful method in helping to gain an insight into the dynamics of a health and social care system. This is a preliminary paper, future papers will expand on this to look at policy experiments and sensitivity tests.
Delays are one specific factor contributing to misperceptions of dynamics. An experimental study was conducted to investigate how different representations of delays in the decision making interfaces (DMIs) may affect peoples ability to manage and understand a dynamic system. A simple production-inventory management game was developed with four distinct DMIs, each featuring the production delay in a different way. Subjects were assigned randomly to use one of the four DMIs and a single-subject, think-aloud experimental protocol was deployed to gather data on the decision making process. No vivid impact of the different representations of the delay in the DMI was observed. However, data gathered through the single subject experimental protocol suggest that the subjects do not follow the anchoring and adjustment rule proposed earlier (see Sterman 1989). Rather, they develop a simplified decision rule that is not robust to changes in the task settings but that is successful in the context of the particular experimental task.
This paper presents a System Dynamics approach to analyzing the violence and widespread death and displacement in Darfur, Sudan, as observed since 2003. We lay a foundation for using simulation to investigate the underlying structure and effects of violence; model analysis indicates that presently the dynamics may be driven by the population at risk more so than aggressor intent. This model can aid in future policy analysis and establishes a foundation for using System Dynamics to understand the structure and pattern of genocide. We present several challenges to analyzing the Darfur crisis including observability, information delays, and the choice of metrics. Finally we discuss modeling results and options for intervention and propose several policy questions and areas for future research.
This paper proposes several alternative methods to improve system dynamics models used in the literature for generation expansion planning in liberalised electricity markets. Concretely, these methods provide a better representation of oligopoly structures and market power. These improvements focus on market price and productions calculations, future markets modelling and companies differentiation when deciding new investments. The methods presented in the paper are based on equilibrium approaches and credit risk theory.
System dynamics has been successfully applied to the study of projects for many years. While this modeling has clearly defined the structures which create project dynamics, it has been less helpful in providing explicit policy advice to managers. To address this gap, we examine the effectiveness of three common project controls available to project managers to address deviations in project performance; (1) exerting pressure on project staff to work faster, (2) having staff work overtime, and/or (3) hiring additional staff. While the three project controls can have short-term benefits for project performance, their long-term impacts can be detrimental. The current work presents preliminary results of the research, focusing on the impacts of the three project controls on project rework and schedule performance. The work describes the development of project control feedback structures, the initial testing and use of a formal system dynamics model of the system, and preliminary results. The work concludes with a description of future project research efforts.
Crowd Control is a function generally associated with the police more than the military. However, the Canadian Forces are occasionally asked to intervene in riot situations either in Canada, in support to Federal, Provincial and Municipal Governments, or overseas, during Coalition operations. Thus, there is a need to understand crowd behaviour and to determine optimal intervention strategies for crowd control. The Canadian Forces have skills and resources that might be called upon if a situation gets out of control and must be prepared to deploy on short notice. A model has been developed that can be used to understand these events in the time dimension both inside the event and from event to event. The model has been developed theoretically and face validated using data from two case studies. The model is required to evaluate appropriate tactics such as the employment of non-lethal weapons, and as a training simulator for strategic and tactical commanders.
Goodwins A Growth Cycle [1967] represents a milestone in the non-linear modeling of economic dynamics. In terms of the two variables wage share and employment rate and on the basis of few simple assumptions, the Goodwin Model (GM) is formulated exactly as the well-known Lotka-Volterra system, with all the limits of such system, in particular the lacking of structural stability. A number of extensions have been proposed with the aim to make the model more robust. We propose a new extension that: a) removes the limiting hypothesis of Harrod-neutral technical progress: b) on the line of Lotka-Volterra models with adaptation, introduces the concept of memory, which certainly plays a relevant role in the dynamics of economic systems. As a consequence an additional equation appears, the validity of the model is substantially extended and a rich phenomenology is obtained, in particular transition to chaotic behavior via period-doubling bifurcations.
System dynamics models are often constructed to improve system performance by identifying and modifying feedback mechanisms that drive system behavior. Once identified, these feedback mechanisms can be used to design and test policies for system performance improvement. A preliminary step in developing policies is the identification of high leverage parameters and structures, the influential model sections that drive system behavior. The current work clarifies and extends the use of statistical screening (Ford and Flynn, 2005) as a model analysis tool with a six step process that identifies specific model sections for further analysis and development. The work also presents a method that clarifies the results of model analysis with statistical screening to practicing managers Statistical screening offers system dynamicists a user-friendly tool that can be used to help explain how model structure drives system behavior.
Hydrogen, an energy vector, displays remarkable versatility with regards to the ways it can be produced. State-of-the-art technologies allow almost every energy source to be converted into hydrogen. What is more challenging, however, is the feasibility of building a new infrastructure to overlap with and, possibly, substitute existing one. This investigation aims to assess what it would entail to add 5% of hydrogen fuel to road transport energy consumption through 2050. The comparison spans five technologies: steam methane reforming, coal gasification, and water electrolysis where power is generated from wind, solar, and nuclear sources. The simulation provides two sets of estimates: calculations on physical infrastructure requirements and its related variable and fixed costs. With regards to facility requirements, the considered technologies show different degrees of feasibility. Coal and nuclear power are not as land-intensive as solar and wind power, but bear problems with pollution and waste disposal, respectively. Economically, coal is least expensive, followed by wind. Natural gas loses competitiveness because of high hydrocarbon prices. The sheer economic rank of preferable energy sources for generating hydrogen should be put into question when internalizing environmental impact of the considered options.
The total dialysis dose, expressed as Kt/V, has been widely recognized to be a major determinant of morbidity and mortality in hemodialyzed patients. Many different factors influence the correct determination of Kt/V, such as urea sequestration in different body compartments, access and cardiopulmonary recirculation. These factors are responsible for urea rebound after the end of the hemodialysis session, causing poor Kt/ V estimation. In this work, system dynamics model was combined with a neural network (NN) method for early prediction of the Kt/V dose. Two different portions of the urea concentration-time profile provided by the system dynamics (on-line urea monitor) were analyzed: the entire curve A and the first half B, using an NN to predict the Kt/V and compare this with that provided by the system dynamics model. The NN was able to predict Kt/V is the middle of the 4h session (B data) without a significant increase in the percentage error (B data: 6.65%±2.51%; A data: 5.62%±8.65%) compared with the system dynamics Kt/ V.
Human resource crises by collective retirement of hospital physicians are a critical issue in Japanese health care systems. System Dynamics modeling is a feasible way to understand these phenomena. Japanese health care system is confronted with not only exogenous environments but also endogenous feedbacks to build up the situation. Increasing busyness by physicians and risk of medical lawsuits and decreasing average productivity and quality of physician by hiring new physicians reinforce retirements of physicians and the retirements change the situation for the worse. To keep sustain level of physician we could find essential policies by simulation. First strategy is changing desired number of physicians with increasing of number of patients per physician. Second way is decreasing delay between retirement and hiring. This was accomplished by early recognition of physicians busyness by hospital managers and abundant of physicians in a health care system.
Hemodialysis-induced hypotension is still a severe complication in spite of all the progress in hemodialysis treatment. Because of its multifactor causes, hemodialysis-induced hypotension cannot be reliably prevented by conventional ultrafiltration and sodium profiling in open-loop systems, as they are unable to adapt themselves to actual decreases in blood pressure. Therefore, it is the ultimate goal to provide automatic control in hemodialysis. Furthermore, the treatment should improve patient comfort and be carried out without use of additional body sensors and without additional medication. Automatic control of hemodialysis has the potential to provide a better treatment to the ever increasing number of ESDR patients who present with more complicated co-morbid conditions
The real-world problem the research aims to address is the continuing highly seasonal, exponential electricity demand growth in the Greek islands that are unconnected to the national electricity grid over the past decades. This paper presents only part of the on-going research. It specifically tests an early draft of the sub-model concerned with the interplay of an islands tourism volume & attractiveness, local technological learning-by-using effects and the dynamics of demand-side equipment diffusion. The general assumption is that a tourist chooses a basket of services received at the place visited, one of which is cooling comfort. Cooling-comfort eventually translates to installed cooling capacity and in effect electricity consumption. This paper examines the sub-model which, based on a figure of cooling comfort per person, constructs an indicator of competitiveness to similar destinations and relates the flow of tourists to it. Similarly, a cost comparison incorporating a learning curve between a conventional and an efficient variant of cooling equipment drives the installation stocks at any time and effectively alters the efficiency of the overall service across the island. The sub-model is run for a number of structural and behavioural tests and also assessed for its potential use in policy making.
Abstract: The scientific community has had increasing concerns for strategic understanding and implementation of food security policies in developing countries, especially since the food crisis in the 70s. The process of decision-making in the public sector is becoming increasingly complex due to the interaction of multiple dimensions related to food security. Policy makers normally use models to support their decisions. This research explores the food security process from a national approach for developing countries through the study of its three main components: The availability of food, the access to food resources and the stability of food security. It bases its study on a systemic perspective through the use of systems dynamics as means of understanding the complexity of this phenomenon as well as the (interrelation) linkage and interdependency of its factors. The study will empower the planners of local regions in the decision making process, to foresee future treats, to alleviate partly the scarcity of food and handle the mismanagement of food resources.
To better understand the performance of hospital operations in response to IT-enabled improvement, we report the results of a system dynamics model designed to improve core medical processes. Utilizing system dynamics modeling and emerging HIS data, we demonstrate how current behavior within the hospital leads to a stove-pipe effect, in which each functional group employs policies that are rational at the group level, but that lead to inefficiencies at the hospital level. We recommend management improvements in both materials and staff utilization to address the stove-pipe effect, and estimate the resultant cost-saving. We believe that the major gains in health information systems use will accompany new information gathering capabilities, as these capabilities result in collections of data that can be used to greatly improve patient safety, hospital operations, and medical decision support.
A business model is a set of assumptions about how an organization will perform by creating value for all the players on whom it depends, not just its customers. This paper discusses a multi-method approach to consistently analyzing the structure, the behaviour and the dynamics of business models in order to identify possible optimizations. The method utilizes object-oriented analysis for analyzing structural and behavioral aspects and system dynamics to analyze value creation dynamics.
Multi-tier, multi-channel supply chains are now common in many industries including aviation. Such supply chains provide high-value aviation parts to the Government, and many have been plagued recently by shortages. A system dynamics model has been developed of an aviation supply chain producing a major sub-assembly composed of eight components, each component coming from a three tier supply chain. These components are used in new production as well as overhaul of damaged parts. It was found that in the face of varying demands substantial bullwhip was produced and that it became especially pronounced at the lower levels of the supply chain. Moreover, it was shown that the government ordering process is extremely sensitive to common data errors such as the production lead-time and that production constraints, not included in the ordering algorithms, created deep and prolonged shortages. On going research is developing improvements to the formulation of the ordering process and developing optimum inventory strategies for creating push-pull boundaries in the manufacturing process.
Supply chains providing high-value parts to the Government have been plagued by both shortages and excess inventory. In many of these supply chains, a computerized government process calculates recommended orders for both new and overhaul parts. A research effort was undertaken to understand the mathematics of this process and its impact on supply chain performance. A system dynamics model of the supply chain was developed that incorporates the equations of the requirements determination process. The model revealed that the process worked appropriately for constant demand and responded well to a ramp-up in demand. It was found, however, that in the face of varying demands substantial bullwhip was produced in the supply chain. Moreover, it was shown that the ordering process is extremely sensitive to common data errors such as the production lead-time and that production constraints, not included in the ordering algorithms, created deep and prolonged shortages. On going research is developing improvements to the formulation of the ordering process and developing supply chain strategies for the next five years under differing demand scenarios.
This paper reports how systems perspective and simulation modeling method can help healthcare administrators and practitioners broaden their boundary perception and create shared understanding of their system. The case used in this study involves a community mental healthcare program in New York State where Systems Thinking and System Dynamics are used to uncover misalignment in the system boundary perceived by the different levels of healthcare administrators. The difference in the perceived system boundary can have a critical impact on the success of a healthcare program if the perception drives planning and assessment of the program implementation. More specifically, this study looks at how the perceived system boundary influences assessment of workload and capacity issues in the program. The study finds that without a systems perspective, unintended consequences of disparate boundary perception can persist without being recognized at the system level, as the local effortsor solutions that are not necessarily globally optimalare arranged to alleviate the unwanted pressures in the system.
The airline industry is characterized by strong dynamic developments. Concentrating on the smallest possible market for an airline company to develop, in this paper we want to demonstrate the effects of entry and exit on city pairs, i.e. the routes between two airports, by presenting a System Dynamics model to simulate and analyze strategic movements on airline markets. By varying the preconditions, e.g. distinct business models and initial entry setups and calibrated with the data of German Antitrust law suit between Lufthansa and Germania, we will show the various consequences of different market scenarios, comparing the results with hypotheses from a literature review. Additionally, we will show the effectiveness of a policy of predatory pricing against market entry under different conditions.
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.
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.
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.
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.
In this paper we address the role of reflective skills in the development and training of new System Dynamics modellers at the tertiary education level. Over the last two years students at the Delft University of Technology have written a reflective essay on their experiences with the conceptualisation, formulation, validation and use of a System Dynamics model in addressing the fictitous, but realistic, problems of a public policy maker. The degree to which they apply the cursory reflective training that they receive and the effect of this intentional reflection on their acquisition and application of modelling skills is evaluated. While some students do attempt to address the added value of a modelling approach to their client and their role in actualising this, the majority of students focus their attention on the strengths and weaknesses of their model and the dilemmas they face in executing the modelling cycle. By presenting the metaphor used in teaching these reflective skills and analyzing the questionnaires completed by the students, we are able to gain further insights regarding the views held by the aspirant modellers of the choices they face in building and using their models. This then feeds back to improve our teaching.
Organic farming represents strategic action for many European countries. Although the subsidies to organic farming sector are present there is no desired level of conversion from conventional to organic farming. System approach was applied in order to analyze the problem state. In order to provide proper strategy to achieve desired level of conversion the simulation model was build. By analysis of different simulation scenarios several propositions for strategic actions are proposed. Further model development guidelines are proposed.
The Special Interest Group on Model Analysis (SIG-MA) focuses on the development, use and advancement of formal model analysis methods in System Dynamics. These methods currently include: Pathway Participation Metric, Fords Behavioural Analysis and Eigenstructure-based methods, amongst others. The focus of this group is not so much on the validity of model equations as, given the equations, how can they best be analyzed and interpreted back to reality.
A system dynamics model of insurgencies is built using the US. Army and Marine Counterinsurgency Manual (FM 3-24) as a basis. It must, however, be supplemented by additional theory from outside sources to enable calibration to a historical data set. Parameter and policy analyses are conducted. These highlight the criticality of some features of insurgencies described by FM 3-24 such as the importance of obtaining and maintaining popular support and employing sufficient counterinsurgency forces to gather intelligence. Other features, not highlighted by FM 3-24, also are shown to be important such as how quickly does violence escalate during the insurgency and how easily can detained/eliminated insurgents be replaced. Finally, contraindicating the expectations of FM 3-24 and other conventional wisdom, results from optimization simulations suggest that the level of force used in a counterinsurgency should increase only once a preparatory period of intelligence gathering by those same forces has been completed.
This paper describes a laboratory experiment to study the effect of variable capacity utilization over the behavior of an electricity market. Capacity utilization is an important factor in order to explain the multiple cycle periods observed in many industries. Investors make investment and capacity utilization decisions in an expanded Cobweb market of the power generation sector. The experiment has four year investment lag, power generation capacity with a sixteen year lifetime and it does not assume full capacity utilization. Cyclical behavior results in three out six markets. Tests show that one market presents well-defined and pronounced cyclical behavior, while other two markets present minor oscillations. Results suggest that varying capacity utilization favors stability, rather than a cyclical behavior.
Commodity prices cycles have a negative effect in developing countries. This paper applies system dynamics to study the long term cyclical behavior of coffee price. The model is based in Meadows (1970) and Deaton and Laroque (1996, 2003). The model includes the price dynamics, investments, capacity, and demand. Our model is the first stages and not fully calibrated. Nevertheless, the model provides a better understanding of the commodity cycles, focusing on the internal structure of the system. The model replicates the reference mode, thus, coffee price exhibits cyclical behavior in the long term. In particular, we have founded very difficult the estimation of investment functions; therefore, future work will be focus on validation and use of laboratory experiments to estimate investment function with coffee farmers.
This paper is a review of research on the application of laboratory methods to System Dynamics (SD). Although laboratory methods have been used in psychology for many years, our review focuses on the laboratory experiments developed from the experimental economics field and on their contributions to SD and the management sciences. In particular, we examine the use of experimental methods for estimating the decisions used by SD models, and the intersection of SD and laboratory experiments in theory testing and theory building.
This paper uses hybrid simulation to evaluate the impact of a whiteboard on the workflow of an A&E department. Hybrid simulation in this context is defined as the integrated use of discrete event simulation and system dynamics; we illustrate how discrete event simulation and system dynamics, by themselves, are incapable of meeting the objective. "Parsimonious" and "divide and conquer" principles for model-building have been followed. We also highlight how a slight modification to the "divide and conquer" approach can assist multi-method users. This paper has deployed novel approach of hybrid simulation in the context of healthcare. It attempts to link value proposition of information system (whiteboard/ electronic patient tracking system) to workflow of A&E department. Due to technical limitation with respect to automatic exchange of information between system dynamics and discrete event simulation, potential of hybrid simulation could not be deployed to maximum level.
This work is an attempt to go ahead on a suitable system dynamics model for goal dynamics in organizations proposed by Barlas & Yasarcan (2008). Even if the proposed model doesnât have any pretension to be exhaustive, the main objective of this paper is to propose a model of goal dynamics in which Goal Setting, Management by Objectives and Training are viewed as human resources practices able to enhance workersâ goal commitment, and therefore, organizational performance. In the first part of this paper, an analysis of Goal Setting Theory and the role of goal setting practice in enhancing workerâs performance are remarked. In the second part, the case-study, the causal loop and a quantitative model of goal dynamics in organizations are described. In the third part, behaviour reproduction test, optimization analysis for parameter estimation and scenario analysis are presented. Limits of this research and conclusion are finally discussed.
The underlying structure of system dynamics models is that of a proportional feedback controller. We propose a broader framework for system dynamics models, where systems are modeled using a combined feedback-feedforward structure. While the traditional structure for system dynamics models only uses proportional feedback of error for control, the proposed structure for information feedback employs the use of proportional, integral and derivative (PID) error. Hence, existing system dynamics models only use a small subset of the proposed structure for modeling systems. We argue that the proposed structure provides a more flexible framework for modeling and designing systems.
Decisions made in the air transport industry are defined by perceptions. Airlines order aircraft when they believe the conditions to upgrade their fleet are appropriate in terms of profitability and market opportunities. However, the financial performance of an airline can be easily affected by several variables.
Many entrepreneurial successes are attributed to the strong personalities of the new venture leaders, who offer vision, inspire loyalty, and display tenacity in solving problems to achieve their goals. Successful start-up ventures may bias perceptions of the anecdotal benefits of personality-driven leadership in firms too young to have established processes, operationally and organizationally. Those ventures destroyed by the personalities of early leaders, because they no longer exist, offer few anecdotes with which to compare and counter legendary successes such as Apple and its visionary leader Steve Jobs or Amazon and its creative founder Jeff Bezos. This paper advances our thinking about the risks and rewards of personality-driven leadership in start-ups by exploring the dynamics that can arise from heroic leadership gone awry. Building on a case study of a key manager in a medical-device start-up, we identify causal relations and essential dynamics that may bring success to the leader but at the expense of the new ventureâs viability. We discuss insights from the causal loops as they relate to the literature on leadership and outline next steps to advance the research.
This is about the water purification system which named eco-machine system. Based on the Model built by STELLA software, the system is used to simulate the wastewater treatment process of Constructed Wetland. This system can increase the amount of dissolved oxygen and absorb nitrogen and phosphorus. Through analyzing the elements influencing dissolved oxygen, we designed the experiment which is divided into 4 parts of circulation: Aquarium which contains ornamental fish; physical treatment which contains oxygen increasing pump; emerged plant absorbing nitrogen and phosphorus; submerged plant increasing oxygen. The power of pump indicates the speed of circulation of water. The amount of oxygen successfully increases with the help of our water purification system in the lab. We assume that the dissolved oxygen is the dominant indicator of the effluvium, so we consider the increase of the dissolved oxygen as the decrease of the effluvium. Meanwhile, all the cost we need is the electrical energy for operating water pump, some aquatic creatures and water plants. In another words, our eco-machine system is an efficient way to improve the water quality.
At its genesis, system dynamics (SD) modeling was developed to examine the temporal behavior of interrelated systems. This ability has made SD modeling and analysis the choice for decision and policy makers to do scenario testing and risk analysis. In addition to the conceptual advantages of SD modeling in this realm, are the many SD modeling platforms that have been developed that greatly simplify model creation and more importantly, provide an environment for visualizing the output. However, when making decisions that involve urban planning, electrical and/or water infrastructure, and the like, or for examining impacts of resource development on the environment, the spatial aspects of the decision becomes just as important as the temporal dynamics. To properly support these decisions, simultaneous visualization of the temporal and spatial dynamics is needed. This paper presents a methodology for utilizing vbscript from within the SD development platform Powersim to dynamically link Powersim simulations with Google Earth to visualize, in real time, spatial data that change over time. The presentation will describe the logic behind the approach, its capabilities and limitations, and areas for improvement that should be addressed.
This paper presents a preliminary System Dynamics model developed to analyze sustainability of a natural reserve in Mexico: the Tamiahua wetlands. Wetlands are often referred to as natureâs kidney because they filter contaminants from water. In spite of their importance, wetlands are endangered areas around the world. The preliminary model presented in this paper suggests that fishing activity in the Tamiahua wetlands, together with contaminants from human activity, have the potential to damage the diversity of species in the ecosystem, endangering the sustainability of the system. Continued work on the model is intended to explore appropriate ways of preserving Tamiahua, providing inhabitants with economic activities that promote the sustainability of the region.
It is hard to study problems where boundedly rational stakeholders determine important decisions in the system. This is because the dynamics of boundedly rational social cognition and social influence are complex and because data about stakeholder mental models and social networks are difficult to elicit, organize, and test. The proposed method to study these kinds of problems combines data elicitation techniques from stakeholder management, theories of boundedly rational social cognition and social influence, and a system dynamics simulation model. This method takes rough qualitative stakeholder data, organizes it into stakeholder diagrams, and uses it to parametrically populate existing system dynamics structure. This allows the researcher to quantitatively simulate complex stakeholder-centric problems where data quality is poor.
There are numerous discussions on possible leverage points in improving software quality and they have been placed in various context--from technical approach, improving user education to economic approach. One of central points of the discussions is on the best policy to handle vulnerability discoveries. Various approaches have been developed: from secret reporting, full-disclosure, responsible disclosure to a market approach. The dominant aspect of the latter is about the Vulnerability Black Market (VBM), which emerged due to the latter development, as an alternative for malicious hackers to sell exploits and malware that take advantage of the flaws in the software. The model in this paper draws on empirical observation on black markets and market-based approach for vulnerability discovery to generate a simple model of VBM. The model results suggest that efficient legal markets may attract malicious hackers to enter the legal markets and may reduce their likelihood to be involved in vulnerability black markets. However, better patching management may mitigate the abuse of software vulnerabilities.
This paper presents a brief discourse on chaotic behaviour and provides an implementation of a classical example from existing chaos theory; the Lorenz strange attractor. The implementation is carried out using standard System Dynamics software and techniques. The paper then goes on to describe a classical buffered feedback system; the Ktesibios clock. The implementation of this feedback system is again carried out using standard System Dynamics software and techniques. Both systems are then amalgamated to unite the butterfly effect of the Lorenz attractor with the buffered nature of the water clock. It is postulated that the resultant taming of the chaotic behaviour generated by the Lorenz attractor through the feedback buffer of the Ktesibios machine is common to many systems; brief examples are given. It is concluded that, in some cases at least, it is the overwhelming of the buffer that leads to a tipping point returning the whole system to a state of chaotic behaviour. Implementing a model of a natural buffered system with chaotic input is identified as an area for further work.
In the UK, formal tertiary education comes at monetary cost to those who choose to participate. Currently 43% of young people enter universities in the belief that they will recoup the initial expense in higher salaries, later in life. Whilst this is a historically true model for the majority of graduates, many analysts believe that the Government's push for a 50% participation rate, coupled with rising costs to attend university, could affect the profitability of higher education and lead to a situation where ignorance is not only bliss but also an economically sound decision.
The Dutch Soft Drugs policy will soon be under review. Regarding Dutch Soft Drugs policy, the Dutch population and political arena could be divided into three groups: those who do not really care, those strongly in favor of legalizing cultivation and use of soft drugs, and those strongly in favor of banning soft drugs. The points of view of the two latter groups are analyzed in this paper
Understanding how interactions between apparently race-neutral institutions and policies can produce racial disparities is essential to a Civil Rights Movement in the United States in the 21st Century. Moving from a discourse that focuses on intent as the determining factor in whether racism exists to a discourse that focuses on the existence of racial disparities and the structures that reproduce them requires a new language and vocabulary. Conceptualizing and operationalizing effective interventions that will reduce these disparities requires a new methodology. System dynamics can play a key role in providing both a language and a methodology to better understand the continuing presence of racial disparities across nearly every indicator of wellbeing. Most attempts to reduce racial disparities have met with considerable policy resistance, and modeling work must focus on identifying key leverage points. In this mostly qualitative work, causal-loop diagrams are pulled from relevant research and key reference modes are examined for insights into the structures perpetuating racial hierarchy. A dynamic hypothesis is proposed that the stock of African-Americans living in areas of concentrated poverty is one of the key drivers of racial disparities. Suggestions and opportunities for further modeling and next steps are also outlined.
The number of incidents provoked by a domestic terrorist organization shows an oscillatory though irregular behaviour over time. There are periods of time where the organization carries out many incidents whereas during other periods, the activity diminishes or even is null. This paper attempts to explain the reasons of that behaviour considering a causal structure that picks up the interrelations between the actions of the organization and the government of the country where the organization focus mainly its activities. While the terrorist organization controls positive feedback loops, the governmental policies implemented to fight against it are led by negative feedback loops fraught with uncertainty. The dynamic emerging from the interrelations between the positive and the negative feedback loops would explain the evolution of the number of attacks carried by the organization. In order to check the strength of the causal structure a simulation exercise is proposed to characterize the number of incidents of a specific organization during a concrete temporal horizon. The aim is to check the degree of fit between the real data and those obtained by simulation, which includes specific features of the organization to study.
This paper reports on an experiment comparing the relative effectiveness of standard group facilitation techniques with system dynamics facilitation techniques in a real world stakeholder participation process. The experiment tested the hypothesis that the system dynamics approach would lead to: (1) better decisions; (2) greater participant focus on relevant materials; and (3) higher procedural satisfaction. The system dynamics approach yielded better decisions but lower procedural satisfaction among participants.
The aim of this paper is to extend a recent "war of attrition" model for counterinsurgency (Kress & Szechtman, 2008) to include the impact on war of the use of influence operations for popular support and defections from the insurgency. The model has the following five sectors: (1) Competitive Contagion for Popular Support; (2) Recruitment and Defections; (3) Quality of Intelligence; (4) War of Attrition; and (5) Collateral Damage. Two messaging policies were compared, but the results of such comparisons will depend heavily on model parameterization and the formulation of effect functions. Still, a model such as this one can be used in principle to inform policy development by making assumptions transparent and by clarifying causal links. For instance, popular support messaging can reduce the effectiveness of insurgent fighters and their ability to recruit. Alternatively, defection messaging can help to recruit defectors and glean intelligence for targeting that could limit civilian casualties and reduce insurgent recruitment, thus bringing the war to an earlier close. This effort was completed, in part, for the U.S. Air Force Research Laboratory at Wright-Patterson Air Force Base (Contract No. FA8650-04-D-6405 TO 25 and TO 33).
Sustained competitive advantage is a major issue in the field of management research. A growing number of scholars utilize the Dynamic Capabilities View as a reason for over average performance and adaptability of a firm, especially to radical innovations that threaten a firmâs survival. Due to the abstract character of the concept, the nature and impact of dynamic capabilities is still vague and empirical evidence is rare. This paper presents a formal simulation model that builds on previous work on the accumulation of dynamic capabilities to explore the micro foundations of the concept. To generate pseudo empirical data, a mixed agent based and system dynamics modeling approach is devel-oped. Judging preliminary results further development of the method promises to be fruitful to understand of the micro foundations of dynamic capabilities.
The healthy exchange of ideas within an organization leads to faster problem solving, mitigates short and long term risk, and opens the possibility for disruptive technological change. We introduce a new tool (GYRUS) for the simulation and optimization of idea propagation within an organization. This tool treats the organizational topology, internal processes, and implements an individual knowledge model to examine idea propagation. The topology represents both the formal and informal networks of idea movement within an organization. The processes include all activities resulting in the exchange or introduction of ideas to the organization. The knowledge model concerns how individuals store and propagate ideas. We apply this tool to a simple organizational topology to understand the propagation characteristics of ideas and the coupling of ideas between entities in the structure.
In this study we develop a system dynamics model of teachers adoption of e-learning system. We identify that environment variables and teachers individual characteristics are the two main factors affecting teachers adoption. Consequently we integrate well-known technology acceptance model into our dynamic model. This study also proposes three policies to enhance teachers adoption. Each policy will be analyzed individually, and policy comparison will also be performed.
Organizational accidents are increasingly being studied using system dynamics (SD) tools. However, as compared to qualitative research of organizational accidents, most of the SD studies conducted so far lack grounding in actual data. Ironically, organizational accidents usually have available data in the form of inquiry reports and other public reports. This study reviews SD studies of organizational accidents and proposes ways to improve the rigor of SD analysis of organizational accidents. Eight relevant papers were identified and classified into two broad types: (1) practice-to-theorizing and (2) theorizing-to-practice. Practice-to-theorizing refers to deriving theories from analysis of actual organizational accidents, while theorizing-to-practice refers to use of pre-conceived theoretical model for research. The study found that both approaches can be improved through textual analysis techniques. The paper proposed data analysis procedures to improve robustness of SD analysis of organizational accidents.
Knowledge and expertise are the most precious assets of a call canter, which enables the staff to serve the customers on high quality. As call centers have a tense working condition, staff are likely to leave this job to a better position in the company or outside, so a real challenge for the managers of these centers is first to moderate the working condition , and then to cope with the high rate of turnovers. This article aims to the last, by modeling the cycle of training a new staff and building experiences, which helps him to serve the customers. By entering the risk of leaving job, this model is objected to find scenarios to reduce the costs of turnover.
Accommodation support for people with Intellectual Disability is a major component of public expenditure in the Australian welfare setting and over the past three decades there have been major shifts in the philosophy of care which have had impact upon funding policies and the allocation of resources. The signing of the UN Convention on the Rights of Persons with Disabilities has prompted a review of current programs and more comprehensive planning for improvements. A community prevalence of approximately 0.6% was established, with a baseline of approximately 0.1% of the population requiring formal accommodation support. Modeling of changes in level of intellectual impairment and levels of dependency in four age groups over the next forty years predicts a rise in the numbers of middle aged and older adults with Intellectual Disability needing accommodation support. Changes in the three forms of adult accommodation (private, state-funded disability accommodation and commonwealth-funded aged care accommodation) were also predicted by the model. There will be a substantial rise in the intensity and demand for state funded disability accommodation, as the clients themselves and their parents age. Changes in the levels of demand in each form of accommodation were estimated by what-if experimentation with changes in eligibility criteria.
Recently there has been a dramatic increase in worldwide attention to environmental issues based on climate change and global warming. This effort has resulted in advances toward a new paradigm, 'sustainable development'. Especially, Green Growth has risen as a new alternative to earlier problems. Korea has focused on the Green Growth, and several plans have been presented by the current administrations. The main purpose of this study is to find what steps are included in the agenda setting process of the Green Growth in Korea, using both time series analysis and system thinking approach. To conduct a time series analysis, the paper examines articles of newspaper and government reports. And, to build a causal map, the speech of current president of Korea is analyzed. The study concludes that the political consideration has played a major role in the policy agenda-setting process of Green Growth in Korea. In addition, it is identified that causal map analysis, as a qualitative approach, can complement the existing method for analyzing the policy agenda setting process.
This research explores the effects of implementing a lean production system in a government facility that is formally governed by accounting practices which delay recognition of production savings but which informally promotes its lean efforts through attention-getting, off-the-books, innovative accounting. We state three propositions relating to customers effects of the lean improvements and the financial approaches. We then state four hypotheses relating to unintended effects of these measures as a facilitys workload varies, and test the hypotheses employing a system dynamics simulation. We identify minor effects upon customer behavior and labor rates oscillation, thereby filling gaps in the literature relating to government productivity improvements, and expanding knowledge relating to lean labor savings, work demand, and employment effects.
As Highly Pathogenic Avian Influenza (HPAI) had become an issue in Korea, Korean Government has decided to make a complete defense system of HPAI using system dynamics and agent based modeling techniques after a preliminary research. This paper summarizes the simulation part of the Korean Government efforts on HPAI.
This paper presents a Bioenergy Systems Sustainability Assessment and Management (BIOSSAM) model. BIOSSAM model was developed as an assessment tool to provide insights on the implications of developing biofuel production programs in South Africa, which is critical for sustainable energy development. As a case study, BIOSSAM model was applied to simulate biodiesel production proposals in the Eastern Cape Province of South Africa. Development of biodiesel production in the Eastern Cape is associated with the promotion of socio-economic development such as job-creation, which in turn influences the economic growth of the Province. Biodiesel production development is influenced by a number of factors such as producer/supplier profitability, which is influenced by several factors such as: land availability to supply raw materials, feedstock prices, government regulations/incentives. To explore the extent of achieving the socio-economic goals from biodiesel production development, BIOSSAM model provides a framework for understanding the causal-loop/feedback structure and dynamics of this emerging industry.
This paper considers the problem of managing process improvement when resources are constrained. The paper constructs a system dynamics model that formalizes the critical interaction between using resources to produce primary output and investing resources in process improvement as means to increase throughput. The model incorporates learning so that the productivity of doing improvement activities grows as workers accumulate experience with new methods. The model enables a rigorous examination into how the feedback structure of process improvement presents challenges to people in a system facing the dual pressure to produce output and to build capability. Simulation analysis highlights the dynamics of the tradeoff between production and improvement and demonstrates the existence of a tipping point that distinguishes enduring high levels of production from modest or no improvement. Results show the superior performance of counter-intuitive policy orientations that favor learning.
In this presentation I develop a small system dynamics model of the fishing industry to explore sustainability and limits to growth. I then use the same model as a metaphor to think about limits to global growth and industrialisation and to appreciate the structure and dynamics of more complex models of industrial society. Since my aim is also to communicate about dynamic complexity, the paper and accompanying talk illustrate basic concepts of stock accumulation, feedback structure and dynamics.
Most business organisations attach great importance on intellectual property and knowledge today, because the property and knowledge are considered as source of competitiveness. In order to protect them, businesses have tried to control the source of intellectual property and knowledge, to say engineers and knowledge workers. This has been working well to enable the businesses to be competitive especially in manufacturing companies and IT companies in early days. The environment around businesses especially in information communication technology and service industries is now changed. Since needs of customers, government regulations and market environments are changing rapidly, knowledge and skills of engineers and knowledge workers need to be quickly updated. Falling behind competitors can lead to withdraw from the market. Nevertheless, businesses seem to continue their protective control on their personnel in old style. This can eventually cause not only lowering workers condition but also aggravated result of businesses because of obsoleteness of knowledge and loss of competitiveness. In order to examine this possibility, this paper shows simulation model based on existing research concerning employment and knowledge management. The result of simulation suggests overprotective policy would reduce businesses competitiveness and protecting knowledge workers job choice supports their companies development.
According to the Global Terrorism Database, Asia was the continent that suffers the highest number of terrorist attacks and the highest number of casualties during the period 1998-2007. One of the numerous terrorist organizations operating on its territory is Lashkar e Taiba (LeT) that was created in 1999. From its inception to 2007, it has staged ninety attacks generating 1,945 casualties. This paper presents a system dynamics model to try to reproduce the number of monthly incidents of that organization. The construction is carried out adapting to the organization those feedback processes that explain the survival over time of a terrorist organization. Comparing the data series and the data obtained by simulation, the paper examines the degree in which the model reproduces the incidents of the organization. After checking the usefulness of the model, different counter terrorist measures are tested in order to assess their effectiveness.
Evidence shows that the paths of growth followed by different countries are diverse. While some countries present a fast growth, other countries show a moderate or even, a slight growth. The first behavior could be justified by means of positive feedback loops that provoke strong accumulations while the second one could be explained through interrelationships of positive and negative feedback loops. To generate process of growth, this paper constructs a system dynamics model considering a causal structure that gathers decisions of consumers, firms and a government in an economy. A simulation exercise obtains different paths of growth taking into account both different governmental strategies and boom and bust cycles. Due to the possibilities that the model offers different political aspects tied to governmental strategies, such as distribution of wealth, degree of corruption or level of education, are examined.
This paper studies the effect of R&D consortia policy and the consequences of the policy implementation process on technology spillover through Foreign Direct Investment (FDI) in Thailand using a system dynamics method. The results show that the R&D consortia policy increases the level of technology spillover and improves the economy of Thailand by boosting the productivity and GDP per capita of Thailand. The R&D consortia policy also amplifies the level of FDI which adds up to the productivity growth. When considering the policy implementation process, shortening the implementation time significantly increases the benefits in the short run but in the long run the additional benefits from shortening the implementation duration diminished. The FDI signaling effect reduces the benefits of the policy. However, when accounting for the signaling effect, Thailand is still better off if the R&D consortia policy is implemented.
This paper presents a study on the penetration of Distributed Generation (DG) under the consideration of a proposal for trading, environmental, and technical incentives, in the Colombian power system. To quantify the technical incentives, we simulated a part of the Colombian grid presents some busbars, low levels of voltage. We connect the busbars "problem", distributed generation and we found an increase in voltage that in a controlled manner can to help to better quality and continuity of electricity supply. Environmental and trade incentives were quantified using international experiences. In addition, we built a system dynamics model to evaluation the complete proposal. We found that the current incentives presented in the Colombian regulation such as tax breaks are insufficient to cover the total costs. Moreover, environmental incentives can be an efficient way to promote renewable energy use in Colombia, in order to achieve, more generating capacity with less pollution indices; and technical incentives in conjunction with environmental incentives can improve further the growth of DG in Colombia. Thus, the DG diffusion become an additional tool for the operator of the interconnected system to make voltage control, improve the quality, and security of electrical power systems.
The emissions of greenhouse gases have become a great worldwide concern due to their effects on climate change. This led to determine, through the Kyoto Protocol, goals to decrease at least 5% of the GHGs by 2012, with respect to the 1990 levels. This agreement established three explicit mechanisms: joint implementation, clean development mechanism and emissions trading. In this context, the European Union created an Emissions Trading Scheme EU ETS (EU Emissions Trading Scheme) that committed 73% of the global carbon market in 2009. Given that the electricity sector is the main contributor of GHGs, it is important to assess the impact of the EU ETS on this sector. This article undertakes this task with the support of a system dynamics model, using the United Kingdom as a case study. Preliminary results indicate that even under a scenario of low prices for emission allowances this would induce significant changes in the installed capacity of the electricity sector, replacing fossil-based technologies by cleaner ones, such as wind and nuclear energy; and also significant reductions of CO2 emissions.
The Portuguese Energy Policy considers the development of a commercially viable and competitive market for energy performance contracting (EPC) as a main mechanism to achieve the objectives of energy efficiency improvement. This paper proposes a study to investigate how to achieve widespread adoption of energy performance contracting by means of system dynamics modelling and simulation. To explore and gather insights on this question, a system dynamics model representing the system of the Portuguese EPC market at industry level will be created. The simulation of that model will provide a helpful basis for analysing and explaining the development of key variables, and accel-erating learning on the managerial, organizational and political adaptation processes that foster the diffusion of EPC adoption. The first phase of this research project aims at identifying and analysing the key factors and critical cause-effect relations that drive the adoption of EPC. With this purpose, a qualitative content analysis on relevant documents was performed and a set of interviews was conducted. That data was ana-lysed to capture the critical variables and its interrelation to formulate a preliminary representation of the system structure as stock and flow diagrams.
Social science theories are developed to understand problematic behavior and describe the social structure believed to be the cause. Only occasionally used, system dynamics has long been considered an ideal testing ground for such theories.
The purpose of the paper is to test whether people make different decisions when a task requires either a fixed delay or a continuous delay conceptualisation. With the help of a structurally simple dynamic decision making task, we test two conditions in a controlled experiment: hiring when personnel stays in an organisation for exactly ten years (fixed delay condition) or when personnel stays on average for ten years (continuous delay condition). In this preliminary study, 71 participants were tested. Findings so far show no differences in performance between the groups, indicating that they most likely use the same cognitive representation of the task. Since participants answers are substantially closer to the fixed delay condition, we assume that people have the tendency to conceptualise lags in the form of discrete delays, at least in the context of personnel hiring. Research implications comprise the repetition of the experiment to achieve a higher number of participants and to allow for a more extreme differentiation between the two conditions. Practical implications regard the formulation of decision making tasks within organisations, for instance in human resource management. The value of this paper lies in its rigorous usage of a structurally simple dynamic task to shed light on a fundamental trait of human decision making.
To better understand the performance of hospital operations in response to IT-enabled improvement, we report the results of a system dynamics model designed to improve core medical processes. Utilizing system dynamics modeling and emerging Health Information Systems (HIS) data, we demonstrate how current behavior within the hospital leads to a stove-pipe effect, in which each functional group employs policies that are rational at the group level, but that lead to inefficiencies at the hospital level. We recommend management improvements in both materials and staff utilization to address the stove-pipe effect, estimate the resultant cost-saving, and report the results of a new experiment conducted in the hospital to validate our approach. We believe that the major gains in health information systems use will accompany new information gathering capabilities, as these capabilities result in collections of data that can be used to greatly improve patient safety, hospital operations, and medical decision support.
Prior exploration is an instructional strategy which has improved performance and knowledge acquisition in system-dynamics based learning environments, but only to a limited degree. This study investigates whether model transparency, showing users the internal structure of models, can extend the prior exploration strategy and improve learning even more. In an experimental study, participants in a web-based simulation learned about and managed a small developing nation. All participants were provided the prior exploration strategy but only half received prior exploration embedded in a structure-behavior diagram intended to make the underlying models structure more transparent. Participants provided with the more transparent strategy demonstrated better knowledge acquisition of the underlying model on an objective measure (multiple-choice posttest) but no difference on a subjective measure (open-ended verbal protocols based on short essay questions). Furthermore, their performance (managing the nation) was the equivalent to those in the less transparent condition. Combined with our previous studies, the results suggest that while prior exploration is a beneficial strategy for both performance and knowledge acquisition, making the model structure transparent in this way (with structure-behavior diagrams) is more limited in its effect and may depend on the participants level of expertise.
The objective of the study is to conduct an exploratory study of the causes that constitute to skilled labor shortage in Norway. Subsequently, we formulate policy to increase skilled labor supply. We apply system dynamics methodology to model the causal relationship between individuals motivation to tertiary education participation, from wages and job opportunity perspective. From the simulation, we find that if tertiary education participation persists as it is, skilled labor shortage will increase from 40,000 in 1994 to 190,000 skilled laborers in 2050, which accounts for 11% of the total skilled labor force. With the introduction of voluntary-based internship program into current tertiary curriculum, promotion of online tertiary education, and encouragement of more foreign tertiary students to study in the country, total university students in 2050 will be 1.30% higher, domestic skilled labor force will be lifted 2.5%, and skilled labor shortage will be reduced by 35%.
The Health Systems Design Laboratory applied progressively more complex concept models to help elicit expert knowledge from medical professionals leadership at a population health agency (PHA) as part of a study of medical professional capacity planning over a 20-year horizon. In this paper we document the knowledge elicitation process employed with PHA managers and medical professionals in two half-day sessions in which we introduced first principles of System Dynamics methodology and applied those in progressively more complex concept models. We observe that our working group, made up of persons with widely divergent levels of experience with complicated models and systems thinking consultations, quickly learned iconography and terminology of system dynamics and contributed to the development of dynamic hypotheses.
The use of DDT for Indoor Residual Spraying (IRS) in recent years has proven to be a cost effective way of combating malaria in sub Saharan Africa. A variety of alternatives to DDT for IRS exist. However, their costs and benefits are insufficiently understood. This is particularly true when it comes to evaluating vector control strategies in an integrated way, i.e., also in terms of their broader socio-economic development impacts. The Malaria Management Model project estimated the costs associated with the eradication of malaria for different combinations of vector control interventions and for different time horizons. For this purpose it developed a computer based simulation model that is based on an extensive database and calibrated for the aggregated sub Saharan African region. It studies long-term (1970-2050) trends of malaria diffusion and the implications for socio-economic development. Model simulations showed that for all policy-scenario combinations, the average yearly expenditures for malaria prevention were much lower than the possible average yearly gain in GDP from eradicating malaria. Model simulations also revealed that the additional costs of substituting DDT for IRS create a series of benefits as well as avoided risks that overall more than offset the costs.
The objective of this research is to identify the key factors that impact the system of product commercialization in the Bogota´s market to allow a better comprehension of the growth behavior of the convenience stores in this city.