Urban Systems最新文献

System analysis techniques can be used to study models such as the nonlinear dynamic feedback World Dynamics Model developed by Jay W. Forrester. Through application of sensitivity analysis it was discovered that the capital-investment parameters of the Forrester model exert the greatest influence on model behavior. Due to high sensitivity of these variables, careful inspection of their function and continual updating of their interrelations with other parameters must be performed to insure model accuracy. In many cases perturbation of a multiplier produces the same relative effect as an equal percentage change in one of the parameters designed as control variables. A change in the relation of the multiplier and its dependent variable offers an alternative to the direct control policies suggested by Forrester.

With recent developments in disaggregated demand models and advances in low cost computer graphic systems, it is now reasonable to contemplate integrating these innovations together in an interactive graphic transit route design system.

The authors outline the goals for such a system and propose a means for implementing those goals. The result is an analytical system which is more effective and economically efficient for transit planners to use than previous interactive systems while also having the capability to solve problems of a larger size, for cities up to one million population.

Finally, the authors have developed an operational example of such a system to demonstrate the feasibility of the proposed approach.

This paper presents a methodology for developing air pollution control strategies through emission-density zoning. The emission potential of each parcel of land is considered to be a function of the type of land use and the level of intensity of the use. Based on this relationship, allowable emission-density limits corresponding to each category of land use are established by a linear programming model. Emissions could then be controlled through zoningordinances in order to maintain acceptable regional air quality standards.

A numerical example is presented which demonstrates the concepts and methodology of the emission-density zoning technique. Potential practical applications of the proposed methodology include long-range air resourced management, regulation and control of air pollution, the evaluation of the capacity of an existing control system to handle increased emissions from future development, and the channelling of future developments to locations of minimum regional pollution effects.

Criminal justice planners at the local level can identify issues and problems involved in processing criminal cases by “tracking” individual arrestees through the justice system. In Joliet, Illinois (U.S.A.), this was done via a manual data collection, manipulation, and reporting system. Issues and problems discussed in the first two reports generated are elaborated upon in this article. Insights into the charging decisions made by police and prosecutor, misdemeanor case handling, and plea negotiations are discussed. Numerous factors influence how these functions are performed and how they can interrelate.

This paper describes the development, validation, testing, and utilization of a systems dynamics model of the stagnating economy of the St. Louis Metropolitan Area. The model focuses on the operation of the area's labor market and uses an age-specific regimen for predicting changes in population, and the concept that the area's unemployment level is inversely related to its exports. The validity of the model is tested by setting its initial conditions to the 1960 values of its variables and running the model forward to 1970. Testing and utilization has involved a series of policy action simulations designed to determine what set of conditions might lead to improvement in the regional economy during the period 1975–2000. Extensive test results from application of the model are presented, and the implications of the various policy actions are discussed.

Simulation models have come to represent the epitome of analytic input to the rational decision maker. Simulation has become a highly sophisticated tool available within an information system which supports decision making in an organization, public or private. The classic use of simulation is to study complex systems whose behavior and features are representable by straightforward analytic relationships. A simple question arises: What is the performance of simulation models as decision aids? This paper contends that a simulation model qua model is less of an aid to decision making than is the process of implementing the model. This thesis is based on (1) the literature where it is not organized and stated explicitly as such. and (2) an 18 month study of the utilization of three computer simulation models in the Philadelphia Emergency Medical Services System. Based on our study, a user-responsive information system to support decision making would provide information in a staged manner according to the level of sophistication needed. The level of sophistication is determined by a complex mosaic of problem area, decision-maker information utilization characteristics, decision-making situation, and decision-making process. This suggests programmatic approaches to information system design which yield effective, efficient aids to decision making.

When choosing housing, individuals are often confronted with a fait accompli. Take what is offered, or leave it. Design is often based on past buying habits, but these do not necessarily represent design options that the consumer would prefer. In this study, a methodology to analyze the stated needs and preferences of residents of new rental housing is presented. The methodology based on data collected from extensive home interviews incorporates: (1) descriptions and definitions of underlying dimensions utilized in housing choice, (2) the determination of the similarity of existing and proposed offerings, and (3) the identification of homogeneous user groups and social characteristics of these groups to aid in the development of a model to help estimate user response to design innovations. The model makes use of multidimensional scaling techniques to assist in the analysis of detailed questions on housing attributes and overall rankings of the housing choices themselves. For the group studied, major dimensions of choice were determined to be size, value and luxury. Interior space attributes were considered more important than location and accessibility to activities. The study concludes with a discussion of the application of these measurements to the development of design criteria.

The extensive use of computer technology is often proposed as one tool to alleviate the fiscal problems facing many urban local governments. Employing data from a nationwide study of computer use in more than 500 larger city and county governments, this paper assesses the current and near-future financial impacts of computer technology on local government operations. There have been a variety of financial benefits from computer use, although few are dramatic. Of all local government functions, computer technology has been applied most extensively in the finance-oriented functional areas. Most current automated applications are unsophisticated: but those applications most commonly under development concentrate on exploiting the technology more fully in order to enhance financial control and to improve the capabilities for revenue generation. Computer technology seems one of the most feasible techniques available for short-term relief from the symptoms of the urban fiscal crisis.