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691.
692.
This study uses probabilistic choice models to predict potential demand for electric cars. Survey data are employed to estimate separate utility functions for each of 51 subjects. This provides a sample distribution of consumer preferences for vehicle attributes including price, operating cost and range. The results indicate great diversity in individual trade-offs among attributes, with range and top speed generally being highly valued. The sample of utility functions is then used to predict potential market shares for various kinds of electric vehicles as second cars. Demand is quite limited, except when (a) electric cars are considerably more advanced than anything likely to be available in the near future, and (b) consumers fear massive gasoline shortages. The latter effect derives from an observed “bias” in favor of electric autos, which is plausibly interpreted as a hedge against disruptions in the gasoline market.  相似文献   
693.
This paper traces the evolution of Canadian liner shipping policy from its beginnings, at the time of the initial formation of shipping conferences, in the late nineteenth century, to its current form, as provided by the 1987 Shipping Conference Exemption Act. It is shown that evolution has been associated with a shift in policy orientation from an initial British-based position to a contemporary form that is distincly American in nature. The reasons for this shift are analysed and the similarities and differences between curent Canadian and U.S.A. legislation are identified. The paper shows that the adoption by Canada of an American-style policy became inevitable once the container revolution had physically integrated the transport systems of both nations.  相似文献   
694.
The conservation of thermal energy equation applied to the mixed layer of the ocean, has been used to predict the sea surface temperature anomalies (SSTA) and the month-to-month changes in the Gulf of Mexico. The model includes the horizontal transport of heat by mean ocean currents and by turbulent eddies, as well as the heating by short and long wave radiation, evaporation and sensible heat given off to the atmosphere. A comparative study is carried out on the relative importance of the heating and transport terms. An objective verification of the skill of the predictions is presented for each season and for the whole period from March 1986 to February 1987. The predictions using only the heating terms have some skill over the control predictions (persistence and return to normal). The skill is substantially increased when the horizontal transport of heat by turbulent mixing is included in the model. The incorporation in the model of the Ekman wind drift current anomalies computed from the anomalous surface geostrophic wind improves appreciably the skill of the predictions in winter and fall.The mixed layer depth computed using the Kraus and Turner theory with dissipation, shows that the depths in summer and fall are shallower than in spring and winter. The effect of the shallow mixed layer depth in the model becomes apparent in summer and fall, improving the skill of the predictions in these seasons, with respect to the skill obtained using a constant mixed layer depth of 60 m.The incorporation in the model of the cooling in the mixed layer by turbulent entrainment of colder water from the thermocline, does not improve in an appreciable way the average skill of the predictions.  相似文献   
695.
The cruise ship industry is currently undergoing a period of rapid expansion. New cruise capacity threatens to produce overtonnaging, with future berths exceeding demand. Despite this development, cruise operators are confident that a growing North American market will be able to satisfy the equilibrium condition sought by vessel operators. This research explores where the new tonnage might be deployed and its eventual impact on the cruise industry. Geographic concepts are utilized to test and support the premise that geography contributes positively to the cruise port selection process. Itineraries, influenced by 'site' and 'situation,' are presently still the most important factor affecting cruise port selection.  相似文献   
696.
This paper provides a broad review of the developments that have taken place within the past thirty years in the field now known as Advanced Vehicle Control Systems (AVCS). This long time horizon was chosen to ensure that significant findings from earlier generations of work are not overlooked today. Following a history of the international development of AVCS, several methods of classifying AVCS are introduced. The main body of the paper reviews the relevant literature in lateral, longitudinal and integrated control of road vehicles and summarizes the most significant findings from this work.  相似文献   
697.
Recent research on autonomous highway vehicles has begun to focus on lateral control strategies. The initial work has focused on vehicle control during low-g maneuvers at constant vehicle speed, typical of lane merging and normal highway driving. In this paper, and its companion paper, to follow, the lateral control of vehicles during high-g emergency maneuvers is addressed. Models of the vehicle dynamics are developed, showing the accuracy of the different models under low and high-g conditions. Specifically, body roll, tire and drive-train dynamics, tire force saturation, and tire side force lag are shown to be important effects to include in models for emergency maneuvers. Current controllers, designed for low-g maneuvers only, neglect these effects. The follow on paper demonstrates the performance of lateral controllers during high-g lateral emergency maneuvers using these vehicle models.  相似文献   
698.
699.
The purpose of this paper is to present the results of a survival analysis for the duration of particular trip-making activities based on sex. Specifically, this study investigates the duration of those activities related to household and family support shopping, personal business, and free time and how these durations vary between men and women. It was found that there were no significant differences in the survival curves (i.e., durations) of free-time or personal business activities; this suggests that men and women spend approximately similar amounts of time on these activities, although it is not known if the activities themselves are similar (for example, banking versus getting gas). Alternatively, sex was found to be a very significant indicator of the duration of household and family support shopping activities. In the model specification, assuming all variables except sex are the same, it was found that women were 1.32 times more likely than men to spend a longer period of time in a household and family support shopping activity. Additionally, it was found that women are 1.33 times more likely than men to have a longer household and family support activity duration if the activity is nested in the journey to work trip.  相似文献   
700.
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