published_or_final_version / abstract / Transport Policy and Planning / Master / Master of Arts in Transport Policy and Planning

This thesis deals with the problem of locating emergency vehicles in an urban area. An optimization model is formulated that extends previous work by allowing stochastic travel times, unequal vehicle utilizations, and backup service. The heart of the model is a procedure similar to the Hypercube approximation model. Ten pair-wise interchange heuristics are developed and tested on 240 test problems. Demand and service time components of the test data have been generated using characteristics of the Tucson Emergency Medical System. Geographical components of the test data have been generated using actual city shapes as models. It is believed that these test problems are more indicative of actual emergency vehicle location problems than those previously presented in the literature.

Zugl.: Dresden, Techn. Univ., Diss., 2007

Thesis (Ph. D.)--New Jersey Institute of Technology, 2005. / Includes bibliographical references (p. 136-140). Also available online via the New Jersey Institute of Technology library website (http://www.library.njit.edu/etd/).

Nowadays, MPLS VPN has become a widely used solution on the issue of QoS guarantees against unexpected changes of network environments. This thesis investigates the system performance of the BGP-based MPLS VPN, which supports per class differentiated services. The results are compared with those without VPN. In this study, the target network is simulated through the OPNET simulator. Through adjusting the network parameters and creating different scenarios, such as network congestion and disconnection, we make statistical analyses based on the simulation results. It is observed that in addition to increasing the labels contained in each packet, MPLS VPN require PE routers be capable of supporting more protocols, such as searching for IP tables, and transferring various tables for the use of routing. Therefore, introducing VPN may increase processing load and overhead for data transmission. On the other hand, MPLS VPN may take longer convergence time in establishing entire routing messages than Non-VPN. However, when network disconnection occurs, the former has better throughput than the latter due to the shorter convergence time in the search of new routes. Also, if the networks become congested, the transmission delay of EF traffic in MPLS VPN is smaller since the alternative LSP for it is pre-established. For the same disconnected LSP route, MPLS VPN network also achieves better throughput, because the guaranteed EF traffic can be rerouted via different LSP routes. According to our simulation results, the background traffic has the largest throughput decrease, while the EF Traffic has the least.

Thesis (M. Econ.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 20-22).

Thesis (M.A.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 82-85).

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