Truck backhauling on two terminal networks

Truck backhauling reduces empty truck-miles by having drivers haul loads on trips back to their home terminal. This paper 1) examines the impact on backhauling opportunities of terminal locations and directional imbalances in the flow of freight from the terminals, and 2) develops a method for determining which truckloads should be backhauled. Backhauling is studied for two terminals sending full truckloads to many customers under steady-state conditions. This research develops two backhauling models. The first is a continuous model that makes simplifying assumptions about customer locations and travel distances. It results in formulae showing that 1) savings from backhauling increase at a decreasing rate as the directional flow of freight between two terminals becomes more balanced and 2) backhauling is an important, but often ignored, factor in terminal (e.g. trucking terminal, warehouse, or plant) location and supplier selection decisions. The second model is a more general discrete model that determines which loads should be backhauled to minimize empty truck-miles.     

High-speed rail service: Issues for the Detroit-Chicago corridor

Several issues concerning the implementation and operation of high-speed rail service in the Detroit-Chicago corridor are identified and discussed in this paper. The primary concern is whether such a service is likely to be attractive enough to induce the private sector to provide it. While the outlook for private operation appears pessimistic, consideration of a broader range of potential benefits (e.g., direct and indirect employment) may justify public involvement and investment.     

A network equilibrium approach for modelling activity-travel pattern scheduling problems in multi-modal transit networks with uncertainty

An understanding of the interaction between individuals’ activities and travel choice behaviour plays an important role in long-term transit service planning. In this paper, an activity-based network equilibrium model for scheduling daily activity-travel patterns (DATPs) in multi-modal transit networks under uncertainty is presented. In the proposed model, the DATP choice problem is transformed into a static traffic assignment problem by constructing a new super-network platform. With the use of the new super-network platform, individuals’ activity and travel choices such as time and space coordination, activity location, activity sequence and duration, and route/mode choices, can be simultaneously considered. In order to capture the stochastic characteristics of different activities, activity utilities are assumed in this study to be time-dependent and stochastic in relation to the activity types. A concept of DATP budget utility is proposed for modelling the uncertainty of activity utility. An efficient solution algorithm without prior enumeration of DATPs is developed for solving the DATP scheduling problem in multi-modal transit networks. Numerical examples are used to illustrate the application of the proposed model and the solution algorithm.     

Approaches and Techniques for Modelling CO2 Emissions from Road Transport

Abstract

Transport accounts for around a quarter of CO₂ emissions globally. Transport modelling provides a useful means to explore the dynamics, scale and magnitude of transport-related emissions. This paper explores the modelling tools available for analysing the emissions of CO₂ from transport. Covering a range of techniques from transport microsimulation to global techno-economic models, this review provides insights into the various advantages and shortcomings of these tools. The paper also examines the value of having a broad range of perspectives for analysing emissions from transport. The paper concludes by suggesting that the broad range of models creates a rich environment for exploring a spectrum of policy questions around the emissions from transport, and the potential for combining modelling approaches further enhances the understanding that can be attained.     

U.S. import/export container flow modeling and disruption analysis

International containerized freight movement is a vital part of the supply chain for many companies, and a critical element of moving consumer goods to points of retail sale within the U.S. Containerized imports also present a clear security concern (e.g., terrorists attempting to ship “dirty bombs,” chemical, biological or even nuclear weapons, into the U.S. in a shipping container). The goal of the research presented here is to create a modeling tool for analyzing flows of U.S. imports and exports of containerized freight, and the potential changes in those flows under a variety of conditions (e.g., port disruptions, extensive security-related delays, etc.). Our focus is on movements through maritime container ports, and not overland movements between the U.S. and Canada or Mexico.The network model, referred to as the System for Import/Export Routing and Recovery Analysis (SIERRA), represents container movements between the U.S. and 46 other countries that account for the vast majority of U.S. imports and exports. The SIERRA model is a network equilibrium model that predicts flows between foreign countries and North American ports, the total volumes handled (import and export) by each port, the modal volumes (truck and rail) moving domestically into and out of each port, and volumes between each port and a set of transportation analysis zones within the U.S.     

Making public policy through citizen committees: Case histories from the Islands

Abstract

Citizen committees properly designed can strongly influence public policy. Examples are taken from the results of reports on marine affairs that citizen committees wrote in Hawaii, the U.S. Virgin Islands and Puerto Rico. Community acceptance and use of each report came about because (1) many members of the committees were in positions to act on the recommendations, (2) the recommendations were specific and called for actions other than studies, and (3) the governor of each area had asked that a report be drawn. To ensure attention to the reports, each governor had agreed that they would be uncensored, widely publicized, and released concurrently to the public and the government.     

An experimental testbed for mobile offshore base control concepts

 The concept of a mobile offshore base (MOB) reflects the need to stage and support military and humanitarian operations anywhere in the world. A MOB is a self-propelled, modular, floating platform that can be assembled into lengths of up to 2 km, as required, to provide logistic support to US military operations where fixed bases are not available or adequate. It accommodates the take-off and landing of C17 aircraft, and can be used for storage, as well as to send resources quickly to shore. In most concepts, the structure is made of three to five modules, which have to perform long-term station-keeping in the presence of winds, waves, and currents. This is usually referred to as dynamic positioning (DP). In the MOB, the alignment is maintained through the use of thrusters, connectors, or a combination of both. In this paper, we consider the real-time control of scaled models of a MOB. The modules are built at the 1 : 150 scale, and are kept aligned by rotating thrusters under a hierarchical hybrid control scheme. This paper describes a physical testbed developed at the University of California, Berkeley, under a grant from the US Office of Naval Research, for the purpose of evaluating competing MOB control concepts. Received: June 4, 2002 / Accepted: October 30, 2002 Acknowledgments. This material is based on work supported by the MOB Program of the US Office of Naval Research under grant N00014-98-1-0744. The authors would like to thank the Link Foundation for its support. Many thanks go to Stephen Spry for his experimental work. The photographs are courtesy of Bill Stone, Gerald Stone, and Jay Sullivan of the PATH Publications staff. Address correspondence to: A.R. Girard (e-mail: anouck@eecs.berkeley.edu)     

Green-Naghdi theory, part A: Green-Naghdi (GN) equations for shallow water waves

In this work,Green-Naghdi (GN) equations with general weight functions were derived in a simple way. A wave-absorbing beach was also considered in the general GN equations. A numerical solution for a level higher than 4 was not feasible in the past with the original GN equations. The GN equations for shallow water waves were simplified here, which make the application of high level (higher than 4) equations feasible. The linear dispersion relationships of the first seven levels were presented. The accuracy of dispersion relationships increased as the level increased. Level 7 GN equations are capable of simulating waves out to wave number times depth . Numerical simulation of nonlinear water waves was performed by use of Level 5 and 7 GN equations, which will be presented in the next paper.     

系统识别法在双自由度涡激振动试验研究中应用

采用系统识别的方法对双自由度圆柱体的涡激振动特性进行了分析研究.试验是在美国麻省理工大学开展,在得到的圆柱体涡激振动轨迹中,由于受到试验条件的影响,如自由液面和水池池底,得到的轨迹并非对称的8字形.因此首先对原始试验结果进行了分解,得到其傅里叶级数展开形式,然后采用了系统识别的方法对其进行分解,分别得到对称和非对称的试验结果,并认为对称的结果为理想或深海条件下圆柱体的涡激振动轨迹,而在自由液面和水池池底等其他因数的干扰下,产生了非对称的试验结果.     

The Organization of Nautical Training and Executive Leadership

The aim of this paper is to indicate some of the distinctive problems of executive leadership which surround the control of authority in merchant navy training schools in the United Satates, Great Britain, and Spain. On the basis of extensive field interviews with the staff and directors of two American, three British, and two Spanish, schools, our purpose is to suggest the conditions which give rise to the need for particular kinds of leadership styles, depending upon the manner by which nautical education is organized [1]. More specfi-cally, our thesis is that their organizationl chartering arrangements (defined as contractual and quasi-contractual linkages with variious third parties to nautical education) mandate specific kinds of internal structural patterns within nautical schools which, in turn, produce the need for different styles of executive leadership.