Amelia C. Regan

Broadcasting safety information in vehicular networks: issues and approaches

A primary goal of intelligent transportation systems is to improve road safety. The ability of vehicles to communicate is a promising way to alleviate traffic accidents by reducing the response time associated with human reaction to nearby drivers. Vehicle mobility patterns caused by varying traffic dynamics and travel behavior lead to considerable complexity in the efficiency and reliability of vehicular communication networks. This causes two major routing issues: the broadcast storm problem and the network disconnection problem. In this article we review broadcast communication in vehicular communication networks and mechanisms to alleviate the broadcast storm problem. Moreover, we introduce vehicular safety applications, discuss network design considerations, and characterize broadcast protocols in vehicular networks.

Trucking industry adoption of information technology: a multivariate discrete choice model

The objective of this research is to understand the demand for information technology among trucking companies. A multivariate discrete choice model is estimated on data from a large-scale survey of the trucking industry in California. This model is designed to identify the influences of each of twenty operational characteristics on the propensity to adopt each of seven different information technologies, while simultaneously allowing the seven error terms to be freely correlated. Results showed that the distinction between for-hire and private fleets is paramount, as is size of the fleet and the provision of intermodal maritime and air services.

Evaluation of Dynamic Fleet Management Systems: Simulation Framework

The problem of dynamic fleet management for truckload carrier fleet operations is introduced, and the principal elements of a simulation framework for the evaluation of dynamic fleet management systems are described. The application of the simulated framework to the investigation of the performance of a family of real-time fleet operational strategies, which include load acceptance, assignment, and reassignment strategies, also is described. The simulation framework described is an example of a first-generation tool for the evaluation of dynamic fleet management systems. Selected experimental results are highlighted. These are intended to illustrate some of the issues encountered in real-time fleet management and the role of the simulation modeling environment in investigating them.

COMBINATORIAL AUCTIONS FOR TRANSPORTATION SERVICE PROCUREMENT: THE CARRIER PERSPECTIVE

The procurement of transportation services is an important task for shippers because of the need to control costs while providing high service levels. When shippers need to transport goods and materials, they seek transportation services from outside companies and typically issue a request for quotes from a group of carriers. The shippers then assign contracts on the basis of negotiated service charges. This process is similar to a simple sealed-bid auction in which each bidder submits a sealed bid for a single item. In the past, when shippers needed to procure transportation services for a set of distinctive delivery routes (called lanes), they would obtain quotes for each lane individually and repeat the simple auction process for each lane. Alternatively, they might negotiate for bundles of lanes with a single carrier at a time. However, in the last several years, software has been developed to enable shippers to make all lanes available for bidding simultaneously and to enable carriers to simultaneously bid on combinations of individual lanes. This method of awarding contracts, conventionally called a combinatorial auction, has resulted in significant cost savings for shippers. This research examines the benefits of combinatorial auctions primarily from the carriers perspective. On the basis of a simple simulation model, preliminary findings suggest that carrier benefits can also be significant.

Location-Based Crowdsourcing for Vehicular Communication in Hybrid Networks

It is a challenge to design efficient routing protocols for vehicular ad hoc networks (VANETs) because of their highly dynamic properties. We address the vehicular communication problem in urban hybrid networks and present a hybrid routing scheme for data dissemination in VANETs. Location-based crowdsourcing of nearby roadside units (RSUs) has been applied to the infrastructural support of inter-vehicle, vehicle-to-roadside, and inter-roadside communications in hybrid VANETs. The combination of RSU resources and ad hoc networks involves an online probabilistic RSU retrieval algorithm that uses coarse- and fine-grained localization to estimate the number and location of available RSUs; a network coding based multicast routing for dense VANETs using maximum distance separation (MDS) code and local topology information from the forwarding set to achieve robust communication and max-flow min-cut data dissemination; an application of opportunistic routing, using a carry-and-forward scheme to solve the forwarding disconnection problem in sparse VANETs; and a routing switch mechanism to guarantee quality of service (QoS) under various network connectivity and deployment configurations. The performance of our hybrid routing scheme is evaluated using both simulations and real testbed experiments.

Rebate, returns and price protection policies in channel coordination

We study channel coordination policies for products subject to midlife price declines during their short product life cycles. Using a two-period supply chain model consisting of one supplier and one retailer, we identify policies and/or conditions under which the supply chain can be coordinated and a win-win situation can be guaranteed. We also provide algorithms to determine the win-win policy parameters. We show that if there are two purchase opportunities, then under linear or decreasing (the more you buy, the lower price you pay) pricing strategies, there may not exist a win-win policy. Our analysis shows that several findings in the single-period models prevalent in the supply chain research literature to date do not extend to the two-period model with two purchase opportunities. For example, returns policies and revenue sharing contracts are no longer equivalent. Also, quantity discounts may never lead to a win-win situation. In fact, the supplier may need to charge more for large orders in order to achieve a win-win outcome. Finally, the analytical framework of this paper can be applied to situations in which the price is constant but production costs change over time.

Current Challenges for Intermodal Freight Transport and Logistics in Europe and the United States

The current issues and challenges related to the large-scale implementation of intermodal freight transportation systems in the United States and Europe are addressed, and open research issues and challenges are identified. As congestion and environmental impacts continue to worsen, intermodal transportation will continue to increase in importance. Therefore, it is necessary to establish a research agenda for an in-depth study of intermodal freight and logistics issues in the European Union and the United States.

Geographic load balancing routing in hybrid Vehicular Ad Hoc Networks

To improve the quality of wireless communication and extend the range of networking applications in Vehicular Ad Hoc Networks (VANET), a hybrid VANET structure is proposed by the combination of the Wireless Mesh Network (WMN) and the Ad Hoc Network. Making use of location information, congestion monitoring and routing switch, we design a geographic load balancing routing in hybrid VANETs, namely GLRV. The mesh routers are deployed to provide backbone supports. Data packet are transmitted in the form of forwarding set to provide multiple forwarding candidates. Three routing switch strategies are designed to ensure the Quality of Service (QoS) under various network connectivity and load scenarios, which are mesh routing when the mesh router is available, geographic greedy routing when the network connectivity is good, and opportunistic routing when the network connectivity is poor. Simulation results show that GLRV can reduce the transmission latency and increase network delivery ratio in hybrid VANET architecture.

Multi-Hop Broadcasting in Vehicular Ad Hoc Networks with Shockwave Traffic

A primary goal of intelligent transportation systems (ITS) is to improve road safety. The ability for vehicles to communicate is a promising way to alleviate traffic accidents by reducing the response time associated with human reaction to nearby drivers. In addition the limitations of standard driving can be overcome by providing drivers with instantaneous information about complications up ahead. Shockwaves, induced by vehicle speed differentials, are a typical mobility pattern that occurs with the formation and propagation of vehicle queues. These induce sudden braking and increase the occurrence of traffic incidents. In this paper, we investigate safety applications in highways with shockwave mobility and different lane configurations in vehicular ad hoc networks (VANET). We evaluate the performance of multi-hop broadcast communication using the ns-2 simulator with vehicles following a shockwave mobility pattern in fully-connected traffic streams. We propose mechanism to improve broadcast reliability using dynamic transmission range that leverages our understanding of fundamental traffic flow relationships.

Resource Location and Relocation Models with Rolling Horizon Forecasting for Wildland Fire Planning

Abstract A location and relocation model are proposed for air tanker initial attack basing in California for regional wildland fires that require multiple air tankers that may be co-located at the same air base. The Burning Index from the National Fire Danger Rating System is modeled as a discrete mean-reverting process and estimated from 2001–2006 data for select weather stations at each of 12 California Department of Forestrys units being studied. The standard p-median formulation is changed into a k-server p-median problem to assign multiple servers to a node. Furthermore, this static problem is extended into the time dimension to obtain a chance-constrained dynamic relocation problem. Both problems are solved using branch and bound in the numerical example. The relocation model is shown to perform better than the static location model by as much as 20–30% when using fire weather data to forecast short term future demand for severe fires, whereas relocating without rolling horizon forecasting can be less cost-effective than a static location model. The results suggest that state fire agencies should identify the threshold beyond which it would be more cost-effective to adopt a regional relocation model with forecasting from fire weather data, especially in a global warming environment.