The negligent upkeep of many abandoned industrial sites (brownfields) throughout the twentieth century has had grave impacts on the urban landscape of American and European cities. In recent years, brownfield redevelopment has come to be viewed as a strategy for sustainable land use and urban revitalization. This study assesses the feasibility of the construction of a dynamic simulation model of urban brownfield redevelopment. Literature surrounding brownfield redevelopment is reviewed and used to construct a dynamic hypothesis of brownfield redevelopment as it relates to site liability, economic viability, and availability of redevelopment funding. Finally, an initial system dynamics model of the brownfield redevelopment process is constructed. This quantitative analysis is performed using the 2003 US Conference of Mayors brownfield survey, which serves as a dataset on brownfield distribution and average site size. We conclude with suggestions for the extension of the model to capture spatial feedback in order to assess redevelopment effects on the surrounding matrix of urban land-uses.
Recently, an invasive Asian beetle known as the Emerald Ash Borer (EAB) (Agrilus planipennis Coleoptera: Buprestidae) has emerged as a threat to Ash trees in the Midwestern United States and Canada (McCullough and Katovich 2004). Significant infestations in Michigan and nearby areas have all but doomed nearly one billion native ash trees. This paper presents an argument for the establishment of a widely accessible knowledgebase of information on the EABs spread capabilities. We argue that spatial dynamic modeling stands as a flexible and powerful decision support system platform. We present initial simulations of EAB spread scenarios constructed using tree information and land use data collected for DuPage County, IL, an uninfected suburban county in the Chicago metropolitan area. These simulations test policies focused on impeding the costly spread of the beetle. This analysis also presents a framework for further studies assessing the economic impacts on municipalities and counties due to tree removal costs and aesthetic damage. Our work points to human driven movement as the major vector for EAB spread throughout our study area. Here, the focus falls on the ability of state and county implemented firewood quarantines to act as effective policies for slowing EAB spread.
Project-based professional service organisations supply their services as tailored or one-off projects for specific clients. The particular form of their organisation, the character of their relationships with their clients necessary to deliver highly customised projects and the non-routine, creative nature of the work come together in a way which makes the management of these service firms particularly demanding. A common challenge is fluctuation in the workload. While this is partly influenced by changes in demand, the external environment does not provide a comprehensive explanation and the interaction between business processes and project processes needs to be examined. In providing a generic explanation of the causes of workload fluctuation as well as an assessment of different bidding strategies based on a system dynamics model, this paper aims to help to advance the theoretical understanding of the project-based professional service organisation and ultimately to help to provide tools for its managers.
The importance of management flight simulators for learning has been already tested and documented. Single player simulation games are usually utilised, but a multiplayer simulation game adds direct competition to the existing problems (delays, nonlinearities and feedbacks). An asymmetric game also introduces bounded rationality and the dynamics of the information flow within the team. A network team game finally allows for the analysis of cooperation dynamics (by letting the users play against each other: against an unpredictable competitor, with no pre-defined strategy). This paper presents an asymmetric multiplayer network game that is considered to be easy to play and understand. The main advantage of the ILE here introduced is the facilitation of the analysis of: learning and decision making processes, cooperation and competition dynamics.
Our objective is to conduct simulations with economic environmental model. We list the important and causal relationships among the levels and trace the feedback loop structures. In describing an economic and environmental model we focus on the relations among income, consumption, emission, and damage. This paper yields insight into maximization of welfare. Next, we present the simulation runs of the model, conducted with the help of existing system dynamics modeling tools.
System Dynamics (SD) is a special type of simulation modeling where
output validity refers to validating the patterns of dynamic behaviors, such
as oscillations, growth or decline. The developers and users of these
models (the decision makers and people affected by decisions based on
such models) are all rightly concerned with whether a model and its
results are valid. Structural model validity and validation have long been
recognized as one of the main issues in system dynamics. This concern
is addressed through pattern recognition and testing in this paper.
Another issue in dynamic simulation methodology is parameter
calibration; assuming that the structure of simulation model constructed
by the user is valid. Parameter calibration is the minimization of an error
function which is a measure of the correspondence between numerically
calculated output patterns and the respective real behavior patterns. We
offer a software that does automated parameter calibration with respect to
a given (desired) dynamic pattern. This particular feature can also be
used in policy improvement design.
Natural gas for automotive purposes is an appealing alternative: curbing local and global pollution and dependence on foreign oil are among the most remarkable advantages. The other side of the coin implies building and maintaining an on purpose network entailing financial requirements. The final aim of this work is to compare its advantages with economic rationale.
A system dynamics model is built and taken as reference for all quantitative assertions. It contains data referring to two scenarios: business as usual versus expansion. The model treats separately global and local emissions and infrastructure needs. Quantitative results are the basis for the final assessment, that is grounded on the externalities theory. By analyzing the scenarios gap numerous remarks follow.
Regarding global emissions, beneficial effects seem modest. Local emissions would either decrease or not vary depending on the pollutant. Avoided externalities estimates exceed infrastructure financial requirements. Natural gas is a suitable answer in tackling some issues related to the road transport industry.
The Norwegian Armed Forces used to have a unitary personnel policy. All officers were recruited with prospects of life-long employment. The long time constants in such a system meant that a transformation into a younger corps was almost impossible to achieve. The model-supported intervention significantly reduced the probable risk of failure in policy design and implementation. A number of achievements must be attributed to the model intervention per se. First, the models base case projected a 100% surplus of senior officers. This was an eye-opener. Moreover, the lack of suitable options within the current policy regime became obvious. Finally, the suitability of the new policy was convincingly presented and its implementation success virtually secured. The success of the model intervention is discussed. Though the most aggregated model sufficed analytically, the existence of a more detailed model that reflected the production system, crucially enhanced the analysis face validity, especially as a cost analysis was called for. However, more critical than the models transparency was that the results fell within the comfort zone of most key stakeholders. The results challenged intuitions enough so that the model was considered invaluable, but not so much so as to question the approach.
The Military Roundtable is the arena for sharing ideas and experiences
on the application of System Dynamics to military problems. The list of
topics includes, for example: strategy development; force-on-force
analysis; war-gaming; military decision making; training of military
decision makers; including command-post exercises; preparedness studies;
human resource management; development and management of military
capability; management of materiel acquisition; military logistics
modelling; in-service management. We suggest the following main topic
for this year's meeting: "SDM as a tool to support training and
exercise". Opportunities exist for participants to provide update on
recent research and consulting activities, to discuss opportunities for
the future and challenges that confront those working in or having an
interest in system dynamics modelling (SDM) in military context. We will
continue the work on assembling a compendium of models and readings on
SDM in defence.
In this poster, authors explain a System Dynamics model developed for measuring efficiency of the Small Aircraft Transportation System (SATS) that NASA has been developing to enhance intercity travelers' mobility in the country. The model is comprehensive in the sense that it includes multi-modes such as automobile, commercial airlines and rail. It also considers different types of decision makers such as travelers, airlines, Federal Aviation Administration (FAA) and Federal Rail Administration (FRA) that dynamically interact with each other based on its own interest. The model allows users to change several critical but uncertain parameters such as the price for SATS trip, airports for SATS operations, etc. This feature enables users to do "what-if" type of study. Technically, the model is developed as a stand-alone tool with a Graphical User Interface that encloses all computational procedures written in MALTALB. Socio-economic data and computational results are represented at a county level using the Geographical Information System (GIS).