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451.
“Today, the idea of allowing aircraft pilots to operate as they see fit, without any control from the land, is unthinkable. Will the same things apply to ships in twenty to thirty years’ time?”Current maritime pilotage regimes are clearly seen in some quarters as too restrictive and old fashioned. Change is “in the air” and VTS, pilotage, and the relationship between them cannot be immune to it. Subject to the attainment of the appropriate standards by both ships and their crews there is no practical reason why more flexible Vessel Traffic Management cannot be introduced. The required technology is largely available and, with the introduction of AIS, the required dynamic data can be available. Technical problems foreseen are believed capable of solution. The more significant obstacles to implementation are, therefore, largely political, commercial, organisational, and cultural. These issues are discussed in this paper taking into account the viewpoints of major stakeholders. 相似文献
452.
Andrew M. Malecki 《Transportation》1978,7(4):403-415
The perception that drivers have of car operating costs is an important factor in determining modal split characteristics. Theoretical figures derived from discriminant analysis models suggest that drivers perceive only petrol costs, but this has not been cor roborated by detailed surveys. This report examines in detail perceived and actual journey to work petrol costs of a sample of London commuters. The perception is also examined of related factors, such as petrol consumption and distance, in an attempt to throw some light on the perception mechanism itself. 相似文献
453.
M. J. H. Mogridge 《Transportation》1978,7(1):45-67
Since the oil crisis of 1973, a number of studies have been made in various countries of the effects of the rise in petrol prices on the level of traffic flow, but rather fewer have attempted to delineate the complex chain of reactions within the car market set off by this impulse. We attempt to do this, using data from the UK.Since 1966 during the prediction stage of the first London Transportation Study it became obvious that low income and high income households had different rates of growth of car ownership, mainly because low income households bought cheap, old cars which vary in quantity and price differently from expensive, new cars. The Greater London Council therefore sponsored a study of car prices by age and size, starting from 1957 annually, and since the oil crisis, evaluated monthly. This has enabled us to examine the strong change in trend that had occurred, with large cars depreciating 15% per annum more than the smallest. The quantities of cars of each size registered each month are available from national statistics and this enables us to say that the previous 1% per annum increase in car size was arrested, with new cars becoming substantially smaller.A model of the car market has been developed which relates on the one hand the price distribution of cars by age, and on the other hand the price. distribution of the stock of cars owned at each household income level. Via the expenditure on car purchase at each household income level and the distribution of the length of time between purchase and resale of cars, a fully dynamic model has been developed to relate expenditure flow and stock. This enables us to test the effect of different trends on the dynamic equilibrium in the car market.The implications of the two trends noted above on the prediction of future car ownership growth are discussed, with the standstill since the oil crisis attributed to petrol prices via the split in household expenditure between purchase and use. 相似文献
454.
C. E. M. Pearce 《Transportation Research Part B: Methodological》1981,15(6):427-435
An analytical study is made of the determination of the travel intensity at an arbitrary point of a city with a straight line barrier. For a given origin and destination a trip is made by the shortest path not crossing the barrier or the city perimeter. The joint trip end distribution is arbitrary except for a continuity assumption. 相似文献
455.
房志宇 《西安交通大学学报(英文版)》1995,(2)
INVITROGLYCATIONOFHEMOGLOBIN(HB):CHOOSINGTHEAPPROPRIATEMODELFangZhiyu;R.R.Little,H.M.Wiedmeyer,D.E.Goldstein(DepartmentofChil... 相似文献
456.
Mohamed M. ELMADANY 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1988,17(4):193-210
Stochastic optimal control and estimation theories are used to design an active suspension system for a cab ride in a tractor-semitrailer vehicle. A discrete-continuous vehicle model with eleven degrees of freedom is augmented by a stochastic road excitation model and a human perception of vibration shape filter. Both perfect measurement and estimated state cases are considered. The impact of the measurement noise on the design of the optimal controller is demonstrated. The performance of the optimally controlled system is compared with an optimal passive system. It is shown that significant improvements in ride comfort can be achieved through the use of actively controlled cab suspensions. 相似文献
457.
F. M. Everard 《Maritime Policy and Management》1995,22(3):197-199
The paper, first of all, examines what a 'rogue ship' is and then moves on to the various practical solutions as to how to deal with the problem. There is no one single answer but the author believes that it is in the interest of society in general to get rid of these ships. 相似文献
458.
459.
C. C. Macadam M. W. Sayers J. D. Pointer M. Gleason 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1990,19(4):201-236
Results of vehicle crosswind research involving both full-scale driver-vehicle tests and associated analyses are presented. The paper focuses on experimental crosswind testing of several different vehicle configurations and a group of seven drivers. A test procedure, which utilized wind-generating fans arranged in alternating directions to provide a crosswind “gauntlet”, is introduced and described. Driver preferences for certain basic chassis and aerodynamic properties are demonstrated and linked to elementary system responses measured during the crosswind gauntlet tests. Based on these experimental findings and confirming analytical results, a two-stage vehicle design process is then recommended for predicting and analyzing the crosswind sensitivity of a particular vehicle or new design. 相似文献
460.
Stanley B. Gershwin David M. Orlicki 《Transportation Research Part B: Methodological》1984,18(6):441-458
A new assignment principle for traveler behavior in an urban network is described which is based on empirical findings in the theory of travel budgets. It characterizes the distribution of travelers, demand, and modal split. It treats all travel decisions (whether to travel, where to go, how to get there) and the important costs (time and money) in a single, unified way. A numerical technique is proposed and it is applied to several examples to illustrate qualitative features. 相似文献