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841.
842.
As urban systems increase in size and diversity, the factors which influence spatial change increase in number and their interactions become more complex. Increasing emphasis is thus being placed by some governments and agencies on regular reviews of policies and programs, to ensure that they are consistent with and facilitate the evolving urban form. Consequently, the monitoring of urban transport and activity systems is of increasing importance, to aid the review processes. This paper considers the progress which has been made in and use of procedures for monitoring urban, transport-related spatial changes. The specification, estimation and presentation of appropriate indicators is briefly discussed. Experience with the use of spatial monitoring procedures on data for two Australian cities has revealed several possible implications for transport investment practice and the development of monitoring and modelling procedures. These are discussed and the paper then indicates the approach which is currently being taken at ARRB towards developing a monitoring system. 相似文献
843.
Earlier work by the Transport Studies Group of the Polytechnic of Central London on minibus development in Britain for the Transport and Road Research Laboratory provided a financial analysis of intensive urban minibus operation. This is taken as the basis for the application of cost-benefit analysis. Unit operating cost savings and passenger benefits are taken into account, using typical demand elasticities derived from earlier work. Particular attention is paid to the problem of evaluating passenger benefits for which waiting time at the roadside is not necessarily an adequate proxy. A direct survey of passenger waiting times indicates that these do not necessarily decrease when a higher-frequency minibus service replaces a conventional bus service but the improved convenience produces an increase in ridership which may be assessed in terms of a demand curve shift to estimate benefits obtained. 相似文献
844.
R. Morris 《Maritime Policy and Management》1983,10(1):53-60
In this paper, the author focuses attentioon on the so-called Melbourne Dockers War of 1971-3. Having descrided its mains events, he goes on to analyse of the unprecedented level of violence in the milieuof trade union elections. He traces this in part to the influx of criminal elements into the Federated Ship-Painters and Dockers Union of Australia (FSPDU) during the Second World War, and to the more immediate disagreement between rival factors concerning the direction which union activities, legal or othewise, should follow. He then assesses the implications of the episode for Australian politics, law and public administration in general. 相似文献
845.
Rajendra G. Kulkarni Roger R. Stough Kingsley E. Haynes 《Transportation Research Part C: Emerging Technologies》1996,4(6):407-424
This paper models traffic congestion formation on highways and roads by recognizing the centrality of dynamical systems and using concepts from complexity theory as imbedded in the spin glasses analogue. Further, it explores the concept of how an increase in air pollution caused by vehicle exhaust emission can be traced to traffic congestion, specifically to the acceleration/deceleration of vehicles on the roads. First, spin glass is introduced and then by applying the two-dimensional x − y Ising model and defining a Hamiltonian (based on Edwards-Anderson and Mattis models of spin glass systems) for a system of vehicles on the road, derivations are made of the specific friction of congestion and the bulk modulus of congestion using the Gibbs-Boltzmann statistic. Similarly using the interactions of vehicles with each other and the resulting accelerations and decelerations of vehicles as the basis for exhaust emissions, derivations are made of a specificity of exhaust emissions. These are analogues to the entropy models of thermodynamics. This series of derivations serves as an analytical model for detecting incidents of congestion and increase in air pollution due to exhaust emissions in transportation systems. 相似文献
846.
The paper examines an international service sector (passenger sea ferry services between the U.K. and continental Europe) from the perspective of its competitive environment. Porter's five forces model forms the basis of the analysis of the market illustrated by recent develoments. Within this context the barriers to entry into and exit from the market are considered in detail. Recently, there have been many changes in market structure, and with increased competition, including that from the Channel Tunnel, it may be necessary to pool services. This will improve ferry competition with other forms of transport, but will require the brand awareness of ferries to shift from the ferry company to the ferry service offer. The service offer will need to be more clearly defined. 相似文献
847.
848.
R. S. Sharp C. J. Alstead 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1980,9(6):327-357
A new tyre model for studies of motorcycle lateral dynamics, and three new motorcycle models, each incorporating a different form of structural compliance, are developed. The tyre model is based on “taut string” ideas, and includes consideration of tread width and longitudinal tread rubber distortion and tread mass effects, and normal load variation. Parameter values appropriate to a typical motorcycle tyre are employed. The motorcycle models are for small lateral perturbations from straight running at constant speed, and include (a) lateral compliance of the front wheel in the front forks, (b) torsional compliance of the front forks, and (c) torsional compliance in the rear frame at the steering head about an axis perpendicular to the steering axis.
Results in the form of eigenvalues, indicating modal damping properties and natural frequencies are presented for each model. The properties of four large production machines for a range of forward speeds, and the practicable range of stiffnesses are calculated, and the implications are discussed.
It is concluded that typical levels of structural compliance in models (a) and (c) contribute significantly to the steering behaviour properties of large motorcycles, and their observed behaviour can be understood better in terms of the new results than of those existing previously. Some conclusions relating to optimal structural stiffness properties are also drawn. 相似文献
Results in the form of eigenvalues, indicating modal damping properties and natural frequencies are presented for each model. The properties of four large production machines for a range of forward speeds, and the practicable range of stiffnesses are calculated, and the implications are discussed.
It is concluded that typical levels of structural compliance in models (a) and (c) contribute significantly to the steering behaviour properties of large motorcycles, and their observed behaviour can be understood better in terms of the new results than of those existing previously. Some conclusions relating to optimal structural stiffness properties are also drawn. 相似文献
849.
Road Vehicle Suspension System Design - a review 总被引:8,自引:0,他引:8
R. S. Sharp D. A. Crolla 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1987,16(3):167-192
Based mainly on English language literature, information relating to the design of automobile suspension systems for ride comfort and control of wheel load variations for frequencies below body structure resonances is reviewed. The information is interpreted in the context of vehicles which travel through a wide speed range on roads of markedly differing quality, which do so carrying different loads and which are required to possess good handling qualities.
Sections are devoted to describing road surfaces, modelling vehicles and setting up performance criteria, and to passive, active, semi-active and slow-active system types. Methods for deriving active system control laws are outlined. Strengths and weaknesses of the various systems are identified and their relative performance capabilities and equipment requirements are discussed. Attention is given to adaptation of the suspension or control system parameters to changing conditions. Remaining research needs are considered. 相似文献
Sections are devoted to describing road surfaces, modelling vehicles and setting up performance criteria, and to passive, active, semi-active and slow-active system types. Methods for deriving active system control laws are outlined. Strengths and weaknesses of the various systems are identified and their relative performance capabilities and equipment requirements are discussed. Attention is given to adaptation of the suspension or control system parameters to changing conditions. Remaining research needs are considered. 相似文献
850.