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851.
在上海腹地经济飞速发展的背景下,上海港要建成国际航运中心和腹地型集装箱枢纽港,将面临前所未有的大好机遇,也面临着国内港口以及东亚等港口之间的激烈竞争。本文就如何合理布局上海港集装箱运输结构;如何构建上海港各集装箱码头之间的沟通桥梁;如何整合上海港现有集装箱码头的综合竞争力,充分发挥上海港整体的优势等上述问题作初步探讨。 相似文献
852.
Data on hydrography, phyto- and zooplankton, obtained on a transect along the 0° meridian during the Winter Weddell Gyre Study, June 1992, revealed peculiarities of the early winter situation in the eastern Weddell Gyre. The vertical distribution and developmental stage composition of Rhincalanus gigas, Calanoides acutus, Calanus propinquus and krill, Euphausia superba larvae, were a good index for a general assessment of the seasonal condition of the plankton communities. There were five zones differing in seasonal situation: (1) The Polar Front and the southern ACC (not studied in detail), (2) The Weddell Front, (3) The Weddell Gyre interior, (4) The Maud Rise area, and (5) The Coastal Current zone. In the Weddell Front, the planktonic community resembled an autumnal situation with moderate phytoplankton biomass; the overwintering stock of copepods was not completely formed and the occurrence of calyptopes larvae of E. superba indicated that krill continued to reproduce until May. In the Weddell Gyre interior, a typical winter plankton community was found even before sea ice had formed. The specific hydrographic regime of the Maud Rise (governed by the mesoscale circulation over the seamount) support the late autumn conditions similar to the Weddell Front (but without early krill larvae). The plankton of the Coastal Current was a winter community. We conclude that in the eastern part of the Weddell Front (compared to the western part) seasonal development of both phytoplankton and herbivorous zooplankton is delayed in spring but prolonged in late autumn. Furthermore, it appears that the Weddell Sea ecosystem exhibits a much higher degree of spatial and temporal variability than thought before. This may have an impact on seasonal pattern of organic carbon transport from the pelagic realm to deeper water layers and to the sediment. 相似文献
853.
A.H. Wickens 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1996,25(6):389-412
The general form of the equations of motion of a symmetric railway vehicle with two unsymmetric two-axle bogies is derived. The equations include a generic elastic stiffness matrix that describes the nature and configuration of the structural connections between the various components of the vehicle. This matrix satisfies the condition for perfect steering (without generating creep forces) on uniform curves and the necessary condition for dynamic stability derived in previous work. The paper shows the application of these basic conditions to a class of generic unsymmetric bogies. The analysis has as its objective the derivation of the simplest rather than the most general configuration that meets the conditions imposed. The results are related to past and current practice. It is shown that perfect steering, with stability at low speeds, can be achieved by means of passive suspension elements not employing linkages, and that it is possible to simplify existing steering arrangements. 相似文献
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855.
Kenneth A. Small 《Transportation Research Part A: Policy and Practice》2012,46(6):874-889
This paper assesses the costs and effectiveness of several energy policies for light-duty motor vehicles in the United States, using a version of the National Energy Modeling System. The policies addressed are higher fuel taxes, tighter vehicle efficiency standards, and financial subsidies and penalties for the purchase of high- and low-efficiency vehicles (feebates). I find that tightening fuel-efficiency standards beyond those currently mandated through 2016, or imposing feebates designed to accomplish similar changes, can achieve by 2030 reductions in energy use by all light-duty passenger vehicles of 7.1–8.4%. A stronger feebate policy has somewhat greater effects, but at a significantly higher unit cost. High fuel taxes, on the order of $2.00 per gallon (2007$), have somewhat greater effects, arguably more favorable cost-effectiveness ratios, and produce their effects much more quickly because they affect the usage rate of both new and used vehicles. Policy costs vary greatly with assumptions about the reason for the apparent myopia commonly observed in consumer demand for fuel efficiency, and with the inclusion or exclusion of ancillary costs of congestion, local air pollution, and accidents. 相似文献
856.
Due to globalization trends and the increasing competition between ports, the maritime policy for container shipments has witnessed a change in operations that resulted in less reliance on direct freight flows and higher transshipment operations. Motivated to investigate a soft intelligent decision-making approach using game theory in the context of servicing vessels during unloading operations in transshipment, we propose an epsilon bargaining approach between the carrier and the container terminal operator (CTO). The objective of the game is to maximize the carrier service level while minimizing operation costs for the CTO. The players' utilities, which depend on the service level and the fees for the carrier, as well as the revenues generated and the cost incurred for the CTO, are uniquely formulated and evaluated in a bargaining scenario using an ordinal ranking approach. The negotiation process is further improved between the two players based on our proposed Epsilon Bargaining Equilibrium, which to the best of our knowledge has not been used in maritime transportation problems. Results from a risk aversion case illustrate the value of the soft computing mathematical model that we formulated and motivate follow-up research. 相似文献
857.
Neville A. Parker 《运输规划与技术》2013,36(4):247-256
The selection of a rural highway corridor between designated termini is approached as the simultaneous selection of line and grade of a particular alignment in the corridor. The selection is facilitated by the successive application of linear programming and shortest path techniques. A model is presented in which the inputs are terrain elevations, design constraints on overall grade, terminal grades and elevations, and restricted areas of passage. The output consists of a user‐specified number of alternative corridors, selected on the basis of minimum sum of the deviations of their representative profiles from the original ground. The model is applicable to situations where route selection is dominated by construction considerations. A hypothetical example and an actual application demonstrate the utility of the methodology. 相似文献
858.
Athanasios A. Pallis 《Maritime Policy and Management》2013,40(4):369-393
This study reveals the profiles, motivations, and expectations of students pursuing undergraduate maritime programmes. Although a number of tertiary institutions offer maritime programmes, the characteristics and structures of the demands for such programmes remain under-researched. This paper illustrates and discusses the results of a survey completed by students pursuing undergraduate programmes in maritime business and management at three universities in Asia and Europe, and compares them with the findings of a database examining similar issues towards postgraduate students within the same institutions. Research highlights include the tendency of undergraduate students to combine studies and work, considering real-world experiences as a vital contributor to career prospects. Shipping (notably tankers, dry bulks and containers) stands out as the ideal professional paths within the maritime industries. Another key finding is that the current marketing strategies of the institutions are rather irrelevant. This paper provides a solid foundation for understanding the profile students pursuing maritime programmes and contributes to the effective planning and management of maritime programmes, thus to the overall professional quality of the maritime industries. 相似文献
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