Climate change (CC) mitigation and adaptation are preeminent goals of the European Union (EU) because there is a need to produce and consume in harmony with the global ecosystem that sustains us. To achieve those goals, the EU has set a target of ten percent green house gas emissions reduction in the agricultural sector relative to 2005 levels by 2020. The development of optimal strategies to meet that goal is the responsibility of each individual country, which suggests that country-specific research on the topic is needed for policy makers. Spain presents a unique setting for the study of optimal CC strategies because its agricultural sector is diverse and highly threatened by CC. This paper develops a continuous dynamic model in order to elucidate the current and emergent relationships and behaviors between the agricultural sector and its direct natural resources, human capital and social capital. The final aim is to identify efficient CC mitigation and adaptation strategies for the short and long run that consider the relationships between economic, natural and social systems. The model structure is based on the Spanish AgroSAM (social accounting matrix), extended with natural resource, human capital and social capital satellite accounts, and converted into a general disequilibrium model.
Tourism is an important industry in many developing countries. In the past few decades, the issue of how to minimize the negative effects of tourism on natural and cultural environments and maximize its positive effects on economic development has been a major topic for tourism researchers and practitioners. Successful tourism-related policies not only can deliver economic benefits to communities, regions, and countries, but also can facilitate their sustainable economic, environmental, and cultural development. Within this context, it is important for policy-makers to incorporate sustainable initiatives into tourism-related policy making. The question of how policy-makers can incorporate sustainable initiatives into tourism-related policy making in a way that will allow them to develop implementable policies and achieve sustainable tourism is, however, not a simple question to answer. Since tourism practices are depicted as processes that reflect different competing interests and values, in order to incorporate sustainable initiatives into tourism-related policy making and achieve sustainable tourism, the first step should be understanding different competing interests and values and their possible contributions to sustainable tourism. This study is aimed at contributing to this area by investigating tourism stakeholder groups interests and values and their influences on tourism development through a system dynamics approach.
The sophistication of schools texts has been declining for more than 100 years in the U.S. Coincidentally, student capabilities and measured verbal achievement have been declining, certainly since the 1950s and probably since 1900. This investigation built a tiny model representing the famous sliding goals archetype tracing back to Forrester's Market Growth paper, and fit the model beautifully to the data. The fit is very dramatic and persuades everyone who sees it that the sophistication of texts and student SAT verbal scores are linked in a sadly sliding long-term pattern. But the fit, derived by robust and correct procedures, is fundamentally flawed, and the lovely fit to data is grossly misleading. This presentation will reveal the entire sad story, with implications for wise practice in the field.
Shareholder Value (SHV) and value-based management (VBM) are blamed for causing short-termism of investors and managerial myopia. Empirical evidence states decreased holding periods of stocks by investors, increased discount rates and widespread adoption of earnings management. While this supports the existence of short-termism and myopia, it does not clarify its causes. What is missing is: do shareholder value and value-based management cause short-termism in the behavior of investors and managers? The paper uses System Dynamics to model both concepts and to try to explain short-termism and myopia as endogenous outcome of these concepts. The main result is, that, given uncertainty of outcomes of managerial action managers will have incentives to engage in short-termism. Since SHV raises target hurdles which increases pressure on managers, short-termism is a direct consequence of SHV itself. The contribution to the debate on short-termism is to better understand the role of SHV and VBM in explaining short-termism and to direct future empirical research as well as advancing modeling of SHV and VBM.
The Veterans Administration faces growing dissatisfaction with the delivery of one of its key services, Compensation and Pension (C&P). This paper focuses on the system surrounding the administration of C&P exams, which determine the extent of a veterans service-related disability. Many VHA facilities nation-wide are experiencing increasing service delays, along with reductions in exam quality and patient satisfaction. A system dynamics model was developed to determine the relationships between operational policies, management decisions, and process outcomes, and calibrated with data from one New England-area VA hospital. Simulation of system performance under various demand scenarios reveal the extent of the implicit the trade-off between resource flexibility, clinic utilization rates and patient wait-times. These scenarios are used to develop strategic policies to improve resource allocation and increase timeliness under highly variable demand conditions. Furthermore, alternate staffing models were tested against historic demand patterns, providing quantitative evidence for system redesign.
This paper is about the shortage of water resources in the central part of Iran -Isfahan while the region faces rapidly growth of the population. The study utilizes the system dynamics approach. The model consists of the following three main parts: water consumption, water resources and population. We will account for the current policies and the current population growth rate in hope of preventing a catastrophic failure in less than two decades from now. So, emigration, birth control policies and major changes in the consumption style are evaluated.
The Brazilian program for sugarcane ethanol has been greatly successful since its inception about 40 years ago. But the road has been bumpy and today there are still major problems with price, supply and demand stability. This paper describes a research with the objective to propose policies by the government to stabilise and foster the Ethanol market in Brazil. The policies are tested by simulation. For that purpose a system dynamics model was built and calibrated to mimic the industry. Once the model is considered robust, it is used to test several proposed policies under different macroeconomic scenario forecasts. Historical evidence and the simulations suggest that the dynamics in the system are highly important in defining prices and other important variables. As one example, periods of high growth tend to negatively influence productivity after five to six years via a decreased investment in crops renovation which may create long term cycles. The effects of long term dynamics are mixed with several short and long term cycles typical of commodities markets and the combination increases complexity exponentially. Simulation can be a crucial tool for understanding causality and planning sound policies for the medium to long terms.
One of the excellence enablers is KM . In order to evaluate the KM processes, a comprehensive model is required, which should be able to capture all aspects of KM. One of such models is KMAT . This research exploits system dynamics in order to measure the effects of KM on business excellence with a combination of KMAT and EFQM .Relationships between KM and EFQM are analyzed and demonstrated by means of the literature reviews, expert interviews and system dynamics .The results of this study could be useful for knowledge management planners and managers in organizations.
The aim of this paper is to illustrate the biofuel model BioPOL and its new developments, to describe a set of scenarios, in which BioPOL was applied and to discuss the results of the scenarios.
Successful corporate action requires a comprehensive recognition of the relevant cause-effect relationships. In combination with the mental models of decision-makers, and as a complement to static instruments for business management, system dynamics simulation models provide valuable support. However, due to the usually experienced big effort and the demand of specific modelling knowledge the use of such models is not yet widespread within management. In order to give medium-sized companies in particular access to such simulation models, a practice-oriented concept was developed, enabling the design and implementation of system dynamics models as to support decision-making within strategic management. Within the framework of an empirical case-study, simulation models were developed for and implemented in four production companies. In order to make the modelling process as simple, efficient, effective and relevant as possible, a practical procedure was derived out of the case studies. This procedure describes the entire modelling process encompassing the initial process of structuring the mental models, the development of quantitative simulation models, as well as the analysis of various scenarios. The concept is based on generic model components, assembled to form a fundamental model structure (backbone) in order to facilitate and to accelerate the modelling process.
This paper presents a dynamic simulation model for the study of the residential heat market in Germany with regard to the European energy targets for the year 2020. It describes the model properties and specifies the dynamic structures of the demand side based on housing units and of the supply side which is formed by heating systems. An initial model validation indicates the appropriateness of the model assumptions. Five policy scenarios are introduced which take into account different measures for the promotion of renewable and innovative heat generation technologies and obligations for energy-efficient renovation of buildings. The discussion of the scenarios shows that with the given set of policies, the EU targets for heat demand reduction and CO2 emission mitigation in the residential sector would not be met, while the envisaged share of renewable and innovative technologies seems to be achievable.
In this paper we model the impacts of competition between cities when considering demand management strategies on both the optimal tolls and business and residential location choices. The work builds on earlier work which studied competition in a small network using a static equilibrium approach. That work showed that while both cities have an incentive to charge alone, once they begin, they are likely to fall into a Nash trap or prisoners dilemma where both cities are worse off. Our research extends this by setting up a system dynamics model which includes all modes and longer term location responses. The model is used first to study an isolated city and a simplified welfare function is used to determine the optimal toll around the central area and its impacts on location decisions and other transport indicators. A twin city is then added. Traffic from the neighbouring city may be charged and the revenue retained - a form of tax exporting behaviour which should increase the welfare of the city. We study the impact on the optimal tolls set by the cities and how the game develops between cities of equal size and amenity. The impact on location decisions and other transport indicators are presented along-side the implications for regulation and the development of cities within regional partnerships.
GEPSUS, decision support system for handling hazardous air pollutant releases was developed based on a Gaussian simulation model of air pollution dispersion using MATLAB. For the Gaussian model the following assumptions apply: a) the smokestack emission is constant and continuous, b) flat homogeneous terrain, and c) the wind speed is constant. It is assumed that in the main wind direction, x, advection dominates over diffusion and dispersion. A detailed outline of the system integration is provided, which includes aspects of hydro-meteorological data, eco-toxicological data, Geographical Information Systems (GIS), user input, and system output including a description of threat zones and evacuation plans using a geo-browser. The Gaussian air-pollution dispersion simulation model is linked to the GIS by generating the output in KML file format. Several simulation scenarios were considered using meteorological data sets of wind speed, wind direction and ambient temperature. The developed simulation model and decision support system is intended to facilitate rapid emergency response for both deliberate and accidental air pollution releases. System dynamics model is developed to address the crisis mitigation issues.
The formation of the EU is the one of the biggest politicaleconomic events of the last 50 years. EU development process is still incomplete, with still evolving EU economic foundations and financial system. The aim of study is to develop EU economy functioning SD model, taking into account main economic indicator changes of EU countries since EU enlargement. Study result author divides countries into several groups, based on their economic specifics. For these groups in the paper the first attempt to develop EU economy system dynamic model is undertaken. General scheme of EU economy SD model is shown, new EU member economic integration model is developed. Model is tested only for one EU country, Latvia. Results of paper show failure of mechanism of EU operations. The available mechanism contradicts EU principles; it doesn't promote the cohesion in EU, but quite opposite- leads to solving problems of well-developed EU countries at the expense of developing countries. In the given conditions the example of Latvia shows that there is no possibility to overcome the system crisis. These circumstances specify necessity of changes in EU internal migratory policy, in principles of developing countries support, in distribution of means, taking into account internal migration.
World Class Manufacturing (WCM) has attracted the attention of many manufacturing industries and operation strategists. Lack of clarification of relationships among widely spreading elements of manufacturing process and poor attention to non-linearity and time delays, all are the main reasons that some companies may be far away from developing a comprehensive and advantageous model in a WCM system. The purpose of this paper is designing and analysis a dynamic Model of WCM system to develop a proper strategy which changing the current situation into a WCM situation would be possible in the future By the Dynamic Balanced scorecard (DBSC) methodology as well as clarifying deficiencies of classical balanced scorecard, a systematic model of WCM has been presented through causal loop and stock & flow diagrams. This research has been carried out as a case study in the Iran Khodro Co.(IKCO), We've used Vensim software for designing and analyzing our model after entering related data, parameters, and equations. Some strategies have been presented through analyzing the scenario and running the simulation model.
In the last decades in several mature democracies the problem of debt emerged as a violation of intergenerational equal treatment due to high expenditures concentration and dilution of costs by mean of debt creation. So far this issue has been analyzed from a statistical and a socio-economic perspective, which identified the high political interference as the main dysfunction of country debt management. There are no studies which frame the issue by focusing on State institutions as performance-oriented organizations, according to this perspective such organizations have to respect dynamically trade-off between development and the debt reduction through a mix of levers such as: funds acquisition/reduction, interest rate and financial leverage. System dynamics can be successfully used as an instrument to support Government in keeping control over the key variables affecting debt changes and implementing a sustainable policy. In the paper three kinds of policies are recommended: the reduction of expenses and increase of receipts in the short term to drastically reduce the debt amount; the opportunity to exploit the financial leverage in the long term. Such approach implies a change of perspective, looking at Italy as a performance-oriented organization in which a proper financial management serves economic development and not vice versa.
The main aim of this paper is to study the impact on birth rate of specific public policies: subsidies to chilbearing and public consumption. The analysis is framed in an developed economy in which fertility choices and economic decisions are interconnected. In particular, the study relies on overlapping generations, habit formation in consumption and endogenous fertility rate. This last factor is directly explained by the preference for children, the economic capacity of young people and the stylized fact of unemployment. The outcome is a versatile system dynamics model that is adapted for the Portuguese economy from 2000 to 2011. Two counterfactual exercises differentiated from the employment distribution but with identical alternatives of public spending are implemented in the simulation model. The results show two divergent aspects: the births do not vary if the public consumption increases but, the births increase when the costs of childrearing are subsidized even if the public consumption is high. These results also indicate that the subsidies are not sufficient to curb the decreasing trend of births. In addition to them, it is required a sustainable economic growth.
Adaptation of SD mainly focuses on management and environment aspects, and successes to get enormous reputations from results. However, adaptation of SD is not limited on these areas, but disseminating to psychology and military science recently. Author believes such adaptation should be wider to other fields too. Continuous of such adaptation, this paper tries to build SD model for study literature with quantitative explanation and understanding. William Shakespeares Tragedy of Romeo and Juliet is one of best works in his early age. Similar story also looked in other literatures in other countries including works of Chikamatsu Monzaemon in Japan and opera Tristan and Isère. Added more, Romeo and Juliet was adapted to other forms of arts and literatures including Broadway musical West Side Story.
By using an integrated dynamic model we are able to reconstruct the supply and gold price of the past (1920-2010) and this is used to predict the future supply of gold to the market and to make a forecast of the gold price 2010-2100. The model was validated against field data for the period 1920-2010 and it performs well. The simulation results show that the market is fundamentally driven by supply and demand, but that derivates trade and speculations have affected the market significantly to create large short term variations in price. In the long term, the model predicts a shift from high-grade ores to low-grade deposits as the main supply source in the next 50 years, but that recycling will become the most important source of gold to the market. The authors predict a significant tightening of the gold market, with rising prices and a decreased derivates trade as compared to trade in the physical commodity. The model shows clearly that foreward and derivates trade create less stability and increase price fluctuations, but that they cannot prevent the long term trend from basic fundamental factors to set the long term levels.
The TETRA-model has been built to predict the modern occurrence of ancient Athenian tetradrachm silver coins in quantitative terms, based on their original minting volumes an antiquity and the processes of their loss and destruction, as well as the process of finding them in modern times. The conceptual model was developed as causal loop diagrams and flow charts, based on Athenian siver mining dynamics, the minting process, the circulation in trade and finance in ancient Athens, rates of wear and loss of coinage, corrosion of coins in the buried state, modern retrieval rates and dynamic turnover in the numismatic market, as well as deposits into collections and museums. A systems dynamics model was programmed in the STELLA modeling environment and implemented for 500 years of Athenian coin production (526 BC to 42 AD) and preservation and retrieval until the present (526 BC to 2010 AD). The TETRA model was tested against independent estimates of past and present coin volumes, treasure finds, museum stocks. The model seems to work well in tests against independent estimates. The approximate number of coins surviving until today for the different types such as archaic owls, classical owls, transitional owls, heterogeneous owls and new style owls were predicted well within the estimates derived through other means and museum inventories (r2=0.82).
Methods of systems analysis were applied to the illness multiple sclerosis (MS). By mapping causality among the many causes affecting multiple sclerosis, we have been able to show that it is a systemic illness, with multiple interacting causes and mechanisms. By using causal-loop diagrams we synthesized a systemic picture of MS in which the role of allergies, pathogens, molecular mimicry, venous vascular dynamics, membrane stability, immune system, and oxidants-antioxidant dynamics were integrated. There are important components that make up MS:
A water cycle analysis System Dynamics model for designing an optimal reclaimed water production scheduling is proposed. A water cycle has various types of water flow and storage, so System Dynamics is suitable for modeling and simulating it. In addition, by using System Dynamics modeling software, various types of models for water cycle analysis can be modeled comparatively easily and used to design an optimal scheduling. The model must be able to analyze water quality and energies for water distribution and treatment as well as water flow and storage in order to schedule optimal production. It therefore consists of three components: water flow, water quality, and energy models. We constructed a water flow model that can handle various types of water flow. The Energy model computes the energy consumption of the pumps and blowers used in water distribution and water treatment systems, and the water quality model computes the water quality of treated wastewater and reclaimed water. Our constructed model was used to schedule water reclamation production to reduce the energy consumed during the water reclamation process and to ensure high quality of the reclaimed water. Simulation results showed that the proposed model is effective for designing an optimal scheduling.
Human resource requirements planning for nursing capacity has traditionally focused on expected utilization or demand and largely ignored the complex workplace policies. The approach taken in this research emphasizes the interaction of policies affecting compensation, work intensity, task satisfaction and career progression on hiring and retention the flows that determine the stock of nurses. Based on research conducted with Singapore Ministry of Health, we describe how policy changes influence employment levels at care venues over a strategic time horizon. To answer three research questions posed by experienced planners and managers, we employ a System Dynamics model to test and explain the implications of alternative policy choices.
Presented here are strategic planning tools used at a State University, College of Business. Four distinct tools are presented: The Strategic Initiative Scoring Model, which communicates how the college strategic planning execution projects fit the strategic priorities of the Universitys mission statement & strategic plan; the college Strategic Risk Planning Matrix, which describes both risk assessments and risk management plans; the college Strategic Planning (SD) Model, which is used by administrators to assess impacts from proposed or mandated changes in budgets, admissions, Student-Faculty Ratio targets, and faculty hiring/attrition; and the Strategic Performance Indicator matrix, used to monitor performance and drive the creation of new projects to be assessed in the Strategic Initiative Scoring Model.
Inter-firm trust is an essential element in supplier relationship that shapes the collaboration and coordination between suppliers and buyers. In this paper, we use system dynamics as an approach and perspective to analyze the evolutionary process of supply chain collaboration. Use a valve manufacturing firm as an illustrative case, this paper illustrates how a buyer firm in a networked supply chain unexpectedly harmed the inter-firm trust between the buyer and its suppliers that further resulted in the collapse of the relationships among them. Based on the quantitative system dynamics model developed, this paper argues and shows that supply chain relationships may be more complex than the consideration of transaction costs. Path dependency of the make or buy decision may exist and drive a supply chain to evolve over time. Buyers and suppliers rational decisions to reduce their own risks and to optimize efficiency may not only interfere with the benefits of the other side but also entrap a long existed supply chain to collapse. From the economic perspective, how to balance the time required for capacity expansion and the time for suppliers to develop new customers is of the essence in such a vulnerable supply chain setting.