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61.
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. 相似文献
62.
A model for assessing the effects of dynamic travel time information via variable message signs 总被引:2,自引:0,他引:2
In view of the serious traffic congestion during peak hours in most metropolitan areas around the world and recent improvement
of information technology, there is a growing aspiration to alleviate road congestion by applications of electronic information
and communication technology. Providing drivers with dynamic travel time information such as estimated journey times on major
routes should help drivers to select better routes and guide them to utilise existing expressway network. This can be regarded
as one possible strategy for effective traffic management. This paper aims to investigate the effects and benefits of providing
dynamic travel time information to drivers via variable message signs at the expressway network. In order to assess the effects
of the dynamic driver information system with making use of the variable message signs, a time-dependent traffic assignment
model is proposed. A numerical example is used to illustrate the effects of the dynamic travel time information via variable
message signs.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
63.
There is a growing interest in traveller behaviour research to explore alternative information processing strategies (often
referred to as heuristics or rules) adopted by individuals when assessing packages of attributes describing alternatives in
a choice set, and making a choice. One popular attribute processing rule relates to attributes not being considered (i.e.,
being ignored), for all manner of reasons, referred to in the small but growing literature as attribute non-attendance or
non-preservation. Researchers have used a mixture of methods to study the role of attribute non-attendance, including supplementary
questions on whether each attribute is ignored or not, and methods in which the functional form of the utility expressions
defining an alternative can recognise the possibility, up to a probability, of an attribute being ignored. Although supplementary
questions are worthy of further consideration, despite the controversy as to the reliability of the response, recent interest
has focused on ways to establish the incidence of attribute non-attendance without recourse to such evidence. In this paper
we use an existing data set of choice amongst four attributes describing alternative car non-commuting trips, to illustrate
the proposed method, and to compare values of travel time savings under each possible combination of non-attendance attributes
relative to a model in which all attributes are assumed to be fully attended to. The paper reveals a major concern with the
way that attribute levels and ranges are selected in the design of choice experiments, which can induce non-attendance situations
where willingness to pay estimates cannot be obtained. 相似文献
64.
This paper proposes an analytical model for investigating transit technology selection problem from a perspective of transit authority. Given a transit technology alternative (e.g., metro, light rail transit, or bus rapid transit), the proposed model aims to maximize the social welfare of the transit system by determining the optimal combination of transit line length, number of stations, station location (or spacing), headway, and fare. In the proposed model, the effects of passenger demand elasticity and capacity constraint are explicitly considered. The properties of the model are examined analytically, and a heuristic solution procedure for determining the model solution is presented. By comparing the optimized social welfare for different transit technology alternatives, the optimal transit technology solution can be obtained together with critical population density. On the basis of a simple population growth rate formula, optimal investment timing of a new transit technology can be estimated. The proposed methodology is illustrated in several Chinese cities. Insightful findings are reported on the interrelation among transit technology selection, population density, transit investment cost, and transit line parameter design as well as the comparison between social welfare maximization and profit maximization regimes. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
65.
William B. Rourke 《先进运输杂志》1998,32(1):45-55
Costly and complicated airports have just three basic functions: (1) service, dispatch and recover airplanes; (2) service, process and embark/debark passengers and material; (3) generate operating cost recovery for owner, operator, sponsor. The first function is ground servicing. The second is embarking and loading, with and subsequent recovery of airplanes, unloading and disembarkation. None of the first function require a terminal of any kind. The second function does, and the third function does nothing for air travel. Use major shopping centers for PRT movement, direct to the jetway. No terminal. Place eleven square buildings between the parallel runways, diamond oriented point-to-point, with four parking spaces -the module sides. Airplanes taxi in and away on one center line, 100 feet from the module centered between in-the-ground service connections. PRT connects two story modules, 200 feet on a side. Jetways at each corner also move vertically up and down to load and unload twice as fast, DOWN the jetway, with baggage on conveyors. PRT from neighborhood centers allows passengers to get tickets from local travel agents, and security check from local police. Travel is secure. Parking and the sales tax take is distributed. 相似文献
66.
William C. Jordan Lawrence D. Burns 《Transportation Research Part B: Methodological》1984,18(6):487-503
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. 相似文献
67.
The motions of an infinitely long, two-dimensional runway subjected to the dynamic moving load imposed by an airplane taking
off are investigated. The runway is assumed to be floating in an inviscid fluid and is initially at equilibrium before the
plane takes off. The deformation of the runway resulting from the take-off is wave-like and moves in the same direction as
the plane. The maximum drag occurs when the plane catches up with the first wave. Three different runway configurations were
considered: a baseline and ones which were ten and one hundred times more flexible than the baseline. For these runways, the
added drag to the aircraft was very small, ranging from 1% for the stiffest to 10% for the most flexible runway. 相似文献
68.
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. 相似文献
69.
Anouck R. Girard Daniel M. Empey William C. Webster J. Karl Hedrick 《Journal of Marine Science and Technology》2003,7(3):109-118
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) 相似文献
70.
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. 相似文献