Evaluation of a supplementary auditory display in a dual axis compensatory tracking task.

Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics. Thesis. 1971. M.S.Microfiche copy available in Barker.Bibliography: leaves 79-80.M.S

Locations of Medians on Stochastic Networks

The definition of network medians is extended to the case where travel times on network links are random variables with known discrete probability distributions. Under a particular set of assumptions, it is shown that the well-known theorems of HAKIMI and of LEVY can be extended to such stochastic networks. The concepts are further extended to the case of stochastic oriented networks. A particular set of applications as well as formulations of the problem for solution using mathematical programming techniques are also discussed briefly

New logistical issues in using electric vehicle fleets with battery exchange infrastructure

AbstractThere is much reason to believe that fleets of service vehicles of many organizations will transform their vehicles that utilize alternative fuels that are more sustainable. The electric vehicle (EV) is a good candidate for this transformation, especially which “refuels” by exchanging its spent batteries with charged ones. This paper discusses some new logistical issues that must be addressed by such EV fleets, principally the issues related to the limited driving range of each EV's set of charged batteries and the possible detouring for battery exchanges. In particular, the paper addresses (1) the routing and scheduling of the fleet, (2) the locations of battery-exchange stations, and (3) the sizing of each facility. An overview of the literature on the topic is provided and some initial results are presented

Approach to Modeling Demand and Supply for a Short-Notice Evacuation

As part of disaster mitigation and evacuation planning, planners must be able to develop effective tactical and operational strategies to manage traffic and transportation needs during an evacuation. One aspect of evacuation planning is the estimation of how many people must be evacuated to provide strategies that are responsive to the number and location of these people. When such estimates are available, it may be possible to implement tactical and operational strategies that closely match the likely demand on the road network during the evacuation. With short notice for an evacuation, people may need to be evacuated directly from current locations. In addition, for some disasters, the spatial extent of the evacuated area may change over time. This problem may be exacerbated by congestion around the evacuated area. An estimation process is proposed for a short-notice evacuation. The method uses on-hand data typically generated through existing travel demand models at many metropolitan planning organizations. It estimates demand using convenient models for trip generation, trip distribution, and travel time generation for these trips, considering a staged evacuation. These demand estimates feed a dynamic simulation model, DynusT, that is used to model the supply characteristics of the roadway network during the evacuation. Such models can be applied using a case study based on a short-notice flooding scenario for Phoenix, Arizona

Locating Sensors on Traffic Networks: Models, Challenges and Research Opportunities

The problem of optimally locating sensors on a traffic network to measure flows has been object of growing interest in the past few years, due to its relevance in transportation systems. Different locations of sensors on the network can allow, indeed, the collection of data whose usage can be useful for traffic management and control purposes. Many different models have been proposed in the literature as well as corresponding solution approaches. The proposed existing models differ according to different criteria: (i) sensor types to be located on the network (e.g., counting sensors, image sensors, Automatic Vehicle Identification (AVI) readers), (ii) available a-priori information, (iii) flows of interest (e.g., OD flows, route flows, link flows). The purpose of this paper is to review the existing contributions and to give a unifying picture of these models by categorizing them into two main problems: the Sensor Location Flow- Observability Problem and the Sensor Location Flow-Estimation Problem. For both the problems, we will describe the corresponding computational complexity and the existing results. After describing various models and identifying their advantages and limitations, we conclude with several promising directions for future research and discuss other classes of location problems that address different objectives than the ones reviewed in the pape

Survey of models to locate sensors to estimate traffic flows

With the advent of Intelligent Transportation Systems, transportation networks are substantially detectorized and large amounts of streaming data is available to manage and plan a multimodal network and provide real-time traffic information to travelers. The related problem of optimally locating sensors on the network to estimate flows has been object of growing interest in the past few years. Available sensors use various technologies and measures different aspects of traffic flows. In this paper we classify the sensor location problems in the literature into two main problems: the Sensor Location Flow- Observability Problem and the Sensor Location Flow-Estimation Problem. We review the existing contributions for the latter of the two problem types and present a unifying bilevel optimization framework, where the upper level addresses the location decisions and the lower level the estimation variables. Several directions for future research are discussed