In this article we have developed a simple dynamic model to portray a cyclic producing mechanism in land market and in the following we have probed the effect of land market oscillation on house market price, which has not been addressed before. In this model, in the beginning two cyclic producing mechanisms in land market are introduced and their effect on house market is elaborated in detail. As we combine the land market model with house market model, to develop an integrated model that offers better understandings of house market trends. The model showed that, in contrast to common perception which presumes house market fluctuations(in supply sector)to be totally intrinsic,they are mainly due to cyclic producing mechanism in land market. Our work uncovers the rich dynamic complexity of the real estate system and can serve as a good example of applying systems thinking principles to complex real world problems. Moreover, we have taken advantage of classic mass-spring systems, to model the house and land market and thus a simple powerful tool is introduced to predict the effect of various mechanisms affecting the house market (e.g. capital market)and it can be a great help to understand the complex house market system, in more depth.
In this paper, we have developed a simple system dynamics model to put forward a perspective for explaining the consumer behavior in energy sector and addressing the obstacles facing the development of new energy systems and their sustainability in rural areas of Iran. In our model, we have presented a mechanism, by which cognitive personal concerns of consumers transforms into behavioral outcomes in rustic society, which was not discussed before this paper. Typically, it is presumed that increasing traditional alternative energy prices and influencing social mind by advertisement and publicity leads to peoples inclination to renewable energies. We observed that in Iran, as the alternative prices are low due to presence of subsidy, the two aforementioned policies shall be implemented collectively and the more effective factor here is price. Furthermore, we have tested the effects of investment on individuals expertise by education and the results are portrayed. A conventional opinion suggests improvement by revenue from surplus production for consumers; however, we have proven it fallacious. Although we have done our utmost to cover the major elements while trying to save simplicity for developing our model, further research might be necessary to make any ambiguities clear.
Traditionally, production and consumption of steel are indicators of the development process in a society. In the world village, domestic and world indexes and prices highly affect each other. Differences between the supply and current demand are the main factors determining the steel price. In this paper, by an Artificial Neural Network we specify indispensable variable to identify the supply and demand for steel. Time of Contract, Expected Price, Volume of supply, Prior contract volume, Global Steel Price, Time between contract and transfer, Previous Price, Volume of Demand, Different Between Supply & Demand, Exchange Rate are specified as the main variables. Then, by a System Dynamics approach we analyze intricate system functioning against changing economic parameters in Iran.
Antibiotic resistance is a major clinical and public health issue causing difficulties in treating infectious diseases and increased risk for complications that lead to fatal outcome. The epidemiology of resistance is a function of the innate characteristics of the bacteria, transmission rates and the consumption of antibiotics. While there are cases where prudent usage of antibiotics leads to decrease in resistant frequency, there are examples where reduction does not lead to reversibility. The dynamics of this complex relationship can be profitably explored by system dynamics simulations. In this paper a generic model describing the transmission of commensal bacteria within a community exposed to different levels of antibiotics is simulated and analytical expressions describing the conditions for reversibility are derived. It is shown that cutting back the volume of antibiotics is necessary but not sufficient to reduce resistance frequency. The biological cost for sustaining resistant traits (fitness cost) and the lateral transmission of genetic material plays a critical role.
This paper is made up of two parts: the first part presents the general structure and technical aspects of the IQuaL (Individual Quality of Life) model. IQuaL is a system dynamic model, built within the capability approach tradition to study the impact of alternative patterns of public expenditure on the well-being of a heterogeneous population. The overlapping-generations structure of the model gives it an intertemporal, long-term dimension, thereby allowing a sustainable development perspective. It focuses on three main functionings (health, education and environment) and studies the various stages leading from public expenditure to functionings and to well-being. The second part focuses on the results of the simulations carried out by the model. The paper shows the key variables that affect the impact on well-being of changes in public expenditure, and explores, with reference to Italy, their crucial role and inter-dependencies. Finally, the implemented analyses provide useful and tangible advices for policy makers who have to implement policies of sustainable human development.
This paper describes our Going Green Globally effort to bring first-year MBA students and business clients together to create sustainable yet profitable practices. The intensive student experience uses systems thinking to frame strategic decisions with a holistic perspective. Students obtain self-assessments on environmental citizenry, study with environmental scientists and engineers, and collaborate with industry experts to craft green practices for actual clients. This cornerstone integrative experience addresses the recognized need to apply knowledge and successfully innovate in complex situations as well as develop sound green business models for their future.
An SD model of biophysical and socioeconomic processes represents the aggregate community goat flock and a processing and marketing cooperative in highland communities near Xalapa, Mexico. Developed through a group model building process with researchers from Mexicos Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, the model is used to assess strategies to increase net income from caprine production through cooperative processing of aged cheeses. Our analyses indicate that manufacture of goat milk products by the cooperative could increase community net income from caprine activities under a variety of environmental and market conditions, including significant demand shocksif these shocks occur after the cooperative is fully operational. These analyses also indicate potential risks and factors that could limit cooperative success: market size and reliability, cooperative management policies, production costs, and flock composition and productivity.
Problem definition, as system dynamicists believe, is the most important phase of the system dynamics modeling process. However, its literature is not rich enough so as to match its importance. In this paper, by reviewing the literature, we introduce the idea that the problem definition itself has an iterative and evolutionary nature. Here, we propose an approach to develop and enrich problem definition based on continuous and conscious effort to elicit the hidden ambiguities of the dynamic hypothesis and transform these ambiguities into questions whose answers would precise the definition of the problem and improve the dynamic hypothesis. We show how this approach on one hand can help us build models much more suited to dynamic real world problem and on the other hand help us much more effectively use models to understand and solve these problems. Finally, we propose some guidelines for revealing the ambiguities as basis to the problem definition and dynamic hypothesis in an iterative process.
Cat Ba Archipelago in Viet Nam has been recognized as a world biosphere reserve. This biosphere is identified as the highest biodiversity in the country and a priority for global conservation. Cat Ba, the largest Island in the archipelago, features diverse topography, remarkable historical heritage and archaeological value. Because of these unique features, the Island has become a popular tourist destination. Cat Ba is experiencing a strong growth in tourism. However, a number of challenges pose threats to sustainable tourism development in Cat Ba including environmental degradation, high poverty level, overuse of underground water, lack of fresh water and electricity, lack of skilled labours, and poor infrastructure and recreational facilities. This paper seeks to explain how a complex and dynamic tourism systems model can be developed and used as framework for decision making and capacity development for local government and private stakeholders who share the responsibility of sustaining the system. The causal loop diagrams and stock and flow models have been developed with participation of diverse stakeholders. Alternative scenarios will be analysed to explain how tourism in the biosphere may change in the next 10-20 years as a result of both multiple investment strategies and changes in the external environments.