Thesis (Ph.D)--Industrial and Systems Engineering, Georgia Institute of Technology, 2009. / Committee Co-Chair: Erera, Alan L.; Committee Co-Chair: Savelsbergh, Martin W. P.; Committee Member: Ergun, Ozlem; Committee Member: Ferguson, Mark; Committee Member: Kleywegt, Anton J.. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis: M. Arch. A.S., Massachusetts Institute of Technology, Department of Architecture, 1976 / Includes bibliographical references (leaves 268-274). / M. Arch. A.S. / M. Arch. A.S. Massachusetts Institute of Technology, Department of Architecture

It is observed that transit riders are responding to service changes while transit planning is responding to ridership changes, or that transit patronage and service supply are highly interrelated. It is also noticed that transit riders transfer from route to route, the introduction of new service may draw some riders from the existing routes, which implies transit patronage on a route is also affected by other parallel and intersecting routes. An analytic tool is needed to examine these complex relationships in the transit system. This study has developed a quantitative model by incorporating these interactions into a simultaneous system. The simultaneity of transit demand, supply and the interrelationship of inter-route effects are addressed in a three-equation simultaneous model: a demand equation, a supply equation and an equation for competing routes. These equations are estimated simultaneously using the three-stage-least-squares estimation method. The model is estimated at the route-segment level by the time of a day, and by the inbound and outbound directions. Data from Portland, Oregon metropolitan area are used as an extended case study. The socioeconomic and demographic data are allocated to an one-quarter-mile distance service area around a transit route by utilizing the technique of Geographic Information Systems (GIS). The data allocation significantly reduces the measurement error. Inter-route relationships are also identified using GIS. The estimation results show that a service change on a route increases the transit patronage on that route, but it also decreases the ridership on its competing routes, so the net effect of that service improvement is smaller than the ridership increase on the subject route. A conventional single equation model under-estimates the ridership responses on the subject route, and over-estimates the net patronage response. This study is the first research to discuss the net effects of a service change at the route level. The model can be implemented for system-level policy analysis and route-level service and land use planning. It is especially useful for "what-if" scenario analysis at the route level to simulate the ridership impacts of service and land use changes.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 342-356. / by Ilan Salomon. / Ph.D.

The major objectives of this study are to: (i) improve the understanding of what is meant by economic diversification and economic diversity, (ii) provide a comprehensive conceptual framework for region-specific analysis of the relationship between changing economic structure and economic performance measured in terms of the growth, stability, and distribution of income and employment, and (iii) construct an operational model of a regional economy that can be used to assess the impacts of alternative development strategies. This study attempts to sort out the overlaps, contradictions, and gaps among the different economic and finance theories, and the different definitions and measures of economic diversification and diversity. The subject of economic diversification or diversity is addressed in the context of the question: "What is the relationship between a region’s changing economic structure and performance?" A structural model of a regional economy, an extended input-output model based on a social accounting matrix (SAM), serves as the foundation of the conceptual framework and operational model. The SAM-based input- output model explicitly depicts the functional relationship between economic structure and performance. The region’s demand, production technologies, and trade flows are included as part of economic structure. Economic performance is measured as the growth, stability, and distribution of regional income and employment, by occupation group. The structural model is used to analyze the relationship between economic structure and performance for a given time period, and to analyze changes over time. Growth, stability, and distributional impacts are considered simultaneously. By doing this, potential tradeoffs can be explicitly addressed. To identify the structural sources of growth and stability, the SAM-based input-output model is decomposed at different points in time. By decomposing a SAM-based model it is possible to analyze structural sources of growth and stability in terms of both supply and demand factors. Alternative development strategies can be modelled using this conceptual framework. The operational model quantifies the relationship between: (i) the anticipated growth and stability of exogenous final demands, and (ii) the anticipated growth, stability, and distribution of endogenous income and employment, by occupation group. The operational model focuses attention on the distributional impacts of changing economic structure and performance. The relationship between a region’s social welfare, and the aggregation scheme and accounting stance used in the analysis of economic impacts are explicitly addressed. As such, there are explicit social welfare criteria for comparing and ranking alternative development strategies. The operational model presented in this study is well-suited to many popular input-output application packages. / Ph. D.

Call number: LD2668 .T4 1985 D66 / Master of Regional and Community Planning

This research focuses on fleet management in freight transportation systems. Effective management requires effective planning and control decisions. Plans are often generated using estimates of how the system will evolve in the future; during execution, control decisions need to be made to account for differences between actual realizations and estimates. The benefits of minimum cost plans can be negated by performing costly adjustments during the operational phase. A planning approach that permits effective control during execution is proposed in this dissertation. This approach is inspired by recent work in robust optimization, and is applied to (i) dynamic asset management and (ii) vehicle routing problems. In practice, the fleet management planning is usually decomposed in two parts; the problem of repositioning empty, and the problem of allocating units to customer demands. An alternative integrated dynamic model for asset management problems is proposed. A computational study provides evidence that operating costs and fleet sizes may be significantly reduced with the integrated approach. However, results also illustrate that not considering inherent demand uncertainty generates fragile plans with potential costly control decisions. A planning approach for the empty repositioning problem is proposed that incorporates demand and supply uncertainty using interval around nominal forecasted parameters. The intervals define the uncertainty space for which buffers need to be built into the plan in order to make it a robust plan. Computational evidence suggests that this approach is tractable. The traditional approach to address the Vehicle Routing Problem with Stochastic Demands (VRPSD) is through cost expectation minimization. Although this approach is useful for building routes with low expected cost, it does not directly consider the maximum potential cost that a vehicle might incur when traversing the tour. Our approach aims at minimizing the maximum cost. Computational experiments show that our robust optimization approach generates solutions with expected costs that compare favorably to those obtained with the traditional approach, but also that perform better in worst-case scenarios. We also show how the techniques developed for this problem can be used to address the VRPSD with duration constraints.

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Thesis (MBA)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Auto Carrier Transport (ACT) is the motor ferrying division of Grindrod South Africa (Pty) Ltd and is contracted to transport the product of 15 different vehicle manufacturers. The division is responsible for ensuring that the combined annual volumes of each contract, totalling over 300 000 vehicles per year, are delivered to the right place, at the right time, and in the right condition. ACT's operating mandate thus focuses on the outbound logistics of new vehicles, which implies moving cars from either the local manufacturing plants, or from the import facilities at the ports, to the respective dealer networks all across Southern Africa. One of the key operational processes regarding the transportation of vehicles is the allocation of cars to carrier loads, also known as load building. Once cars have been allocated to a load, a carrier is then used to transport the load. The existing load building operation is completely manual, with operators simply assigning cars to loads as best they see fit. No support systems exist. Thus, given the complexity of the load building problem, and the manual processes used, existing load building practices result in suboptimal payload performances. A Linear Programming Model was developed to improve the manner in which vehicles are categorised, and then assigned to loads. When compared against the results of load building operators, it was found that the model could potentially improve the company's contribution margin by 5.8 percent. / AFRIKAANSE OPSOMMING: Auto Carrier Transport (ACT) is die motorvoertuig vervoerafdeling van Grindrod Suid Afrika (Edms) Bpk en word gekontrakteer vir die vervoer van die produkte van 15 verskillende motorvervaardigers. Die afdeling is verantwoorde1ik om te verseker dat die jaarlikse volume van elke kontrak (met 'n gekombineerde volume van meer as 300 000 motorvoertuie per jaar) betyds afgelewer word, op die regte plek en in die regte toestand. ACT se operasionele mandaat fokus dus op die uitgaande logistiek van nuwe motorvoertuie met die implikasie dat motorvoertuie vanaf die plaaslike vervaardingsaanleg, of die invoer fasiliteit by die hawens, na die ooreenstemende handelaarsnetwerke in Suider Afrika vervoer word. Een van die kern operasionele prosesse rakende die vervoer van motorvoertuie, wat bekendstaan as vragtoekening, is die toedeling van motorvoertuie tot vragmotor vragte. Sodra 'n motorvoertuig aan 'n vrag toegeken is, word dit deur middel van 'n vragmotor vervoer. Die bestaande vragtoekeningsproses word per hand uitgevoer deur operateurs wat eenvoudig motorvoertuie aan vragte toedeel soos hulle goeddink sonder die gebruik van enige besluitnemingsondersteuningstelsels. Aangesien vragtoekening 'n baie komplekse probleem is wat per hand uitgevoer word, is die resultate suboptimaal. 'n Lineêre programeeringsmodel is ontwikkel om die klassifikasie van motorvoertuie te verbeter waarna die motorvoertuie aan vragte toegeken word. In 'n vergelyking tussen die model se resultate en die van die operateurs is daar bevind dat die model die maatskappy se wins per eenheid met 5.8 persent kan verbeter.

by Lau Tze Yiu, Peter. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (p. 352-365). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.