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71.
Abstract The Lancaster Sound Regional Study serves as a pilot project for regional planning in the Arctic. Probably the most biologically productive area of all arctic regions, Lancaster Sound represents a unique Canadian heritage. And since it occupies the strategic eastern entrance to the Northwest Passage, the Sound has long been a summer shipping route. Now, proposals are under review that would permit year‐round shipping of oil and gas from the Beaufort Sea by means of ice‐breaking tankers. Also proposed are the exploration and development of possible hydrocarbon reservoirs within the Sound. Actual decisions for the area's use must respect the interests of the native Inuit who have lived there for centuries as well as the preservation of the environment. This paper describes the preliminary phase of the regional planning for the region: the preparation of a public discussion paper to elicit informed comment and opinion on future uses of the Sound. It is a first step toward recommending suitable management and use options for the region. 相似文献
72.
Julián Pando Andres Araujo Francisco Javier Maqueda 《Maritime Policy and Management》2013,40(2):67-87
Recent technological developments in maritime transport, particularly in container shipping and larger vessels, are having major repercussions at ports the world over. The latest wave of innovations has increased the level of competition in maritime transport, in particular in port activities. Shippers have many more alternatives available, something that tends to increase the hinterland of each port, precisely by reducing captive hinterlands. Ports are now generally moving towards formulas in which private initiative has a bigger role to play. Increases in competition combined with growth in private initiatives highlight the usefulness of marketing tools in two ways. Externally, because they help to achieve throughputs from remote points of origin and destination, and internally, by aiding the proper coordination of business and organizational activity at a commercial port. The present paper is a transversal study of the current situation of marketing and quality tools at major ports, including the opinions of a range of port commercial and marketing managers. We have also tried to describe the differentiated groups to be found at ports, as a useful methodology for identifying the nearest competition or ports with similar characteristics. 相似文献
73.
Juan M. Barragán Muñoz 《Coastal management》2013,41(3):137-156
The article is divided into three clearly defined sections. The first outlines the Brazilian National Coastal Zone Management Plan. The second offers a critical assessment of its introduction. To conclude, some general considerations are made. In this way, the author aims to achieve two objectives: to disseminate the aforementioned plan and offer a critical opinion of it. 相似文献
74.
Transit textbooks and engineering manuals indicate that the capacity of Bus Rapid Transit –BRT – systems does not exceed 20,000 passengers per hour per direction. The implementation of the TransMilenio BRT System, in Bogotá, Colombia, showed that the systematic combination of multiple platforms at stations, overtaking lanes, level boarding, prepayment, large buses with multiple doors, express and local services, and traffic engineering measures at intersections, allow for very large passenger throughput. Measurements indicate actual throughput of 43,000 passengers per hour per direction with average bus occupancy of 150 passengers per articulated bus, and a commercial speed of 22–24 km/h. According to special formulas developed for the analysis of high capacity BRT corridors, the critical section of TransMilenio has a practical capacity of 48,000 passengers per hour per direction with its existing infrastructure and 150 passengers per bus – 35,000 passengers per hour per direction with 110 passengers per bus. Changes in existing infrastructure, such as additional platforms, higher capacity vehicles, non-grade facilities at critical intersections, among other improvements, may increase the capacity, speed, reliability and quality of service of the system. 相似文献
75.
José Manuel Vassallo Pablo Pérez De Villar Ramón Muñoz‐Raskin Tomás Serebrisky 《运输评论》2013,33(2):261-278
Abstract Public transport policy in the Madrid Metropolitan Area is often deemed as a success. In 1985, an important reform was carried out in order to create a new administrative authority to coordinate all public transport modes and establish a single fare for all of them. This reform prompted a huge growth in public transport usage, even though it reduced the funding coverage ratio of the transport system. Since then, Madrid’s public transport system has been undergoing an increasing level of subsidization, which might jeopardize the financial viability of the city public transport system in the future. In this paper, we present a detailed analysis of the evolution of the public transport funding policy in Madrid in recent years. We found that the increasing level of subsidy can hardly be explained on the basis of equity issues. Moreover, we claim that there is still room for a funding policy that makes the efficiency of the system compatible with its financial sustainability. 相似文献
76.
J. Enrique Fernández L. Joaquín de Cea Ch G. Germán Valverde 《Transportation Research Part A: Policy and Practice》2009,43(5):481-499
The effect of the application of advanced transport information system (ATIS) and road pricing is studied in a transportation system under non-recurrent congestion. A stochastic network deterministic user equilibrium model (SNDUE) with elastic demand is formulated and used to evaluate the welfare and private impacts of different market penetrations of ATIS, together with road pricing for a simple network. Both marginal first-best road pricing and a second-best fixed road pricing are considered. The incentives of private users to use ATIS are analyzed and the characteristics of optimum tolls as a function of ATIS market penetration are shown. We conclude that ATIS is an efficient and necessary tool to reduce the effects of non-recurrent incidents in a transportation network, especially when non-recurrent congestion causes a significant deterioration of operational conditions of the network. If the impact of non-recurrent incidents on free flow costs is small or is reduced only to congestion effects, the use of road pricing would be more efficient. Social benefits obtained when jointly implementing ATIS and road pricing are practically the same whether first-best or second-best road pricing is used. Considering the private costs perceived by the network users, and the benefits experienced by equipped users, the maximum level of market penetration achieved could be limited because private benefits disappear after certain market penetration is obtained. 相似文献
77.
Ana Laverón-Simavilla Victoria Lapuerta Sebastián Franchini Angel Sanz 《Journal of Marine Science and Technology》2008,13(3):190-206
A study of a boat's motion is carried out in order to analyze the aerodynamic properties of the optimal sail for obtaining
the maximum velocity when sailing to windward. The mechanics study shows the optimal C
L and C
D for a given sail and how the shape of the aerodynamic polar of the sail should be. A parametrical analysis of the aerodynamics
of a sail is then carried out varying the maximum camber, position of the maximum camber in the chord direction and position
of the maximum camber in the mast direction. The parametric analysis is done numerically with a vortex lattice method (VLM)
and experimentally in a wind tunnel. The results show that the influence of the relevant parameters studied can be reduced
to the variation of two parameters, A and B, defining the polar of the sail, C
D = B + A
2
C
L
2; and the influence of parameters A and B on the maximum VMG obtainable are calculated. 相似文献
78.
79.
Nonlinear Dynamics of Vehicle Traction 总被引:3,自引:0,他引:3
B. J. Olson S. W. Shaw G. St p n 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2003,40(6):377-399
Summary The purpose of this study is to understand the nonlinear dynamics of longitudinal ground vehicle traction. Specifically, single-wheel models of rubber-tired automobiles under straight-ahead braking and acceleration conditions are investigated in detail. Customarily, the forward vehicle speed and the rotational rate of the tire/wheel are taken as dynamic states. This paper motivates an alternative formulation in which wheel slip, a dimensionless measure of the difference between the vehicle speed and the circumferential speed of the tire relative to the wheel center, replaces the angular velocity of the tire/wheel as a dynamic state. This formulation offers new insight into the dynamic behavior of vehicle traction. The unique features of the modeling approach allow one to capture the full range of dynamic responses of the single-wheel traction models in a relatively simple geometric manner. The models developed here may also be useful for developing and implementing anti-lock brake and traction control control schemes. 相似文献
80.
A Versatile Flat Track Tire Testing Machine 总被引:1,自引:0,他引:1
J. A. Cabrera A. Ortí z A. Sim n F. Garcí a A. P rez La Blanca 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2003,40(4):271-284
Summary A flat track tire testing machine developed by the IMMa group is described. It permits the simulation and study of the dynamic behavior of a great variety of tires under controllable and repetitive highly dynamic realistic working conditions in the laboratory for a diversity of vehicles, from motorcycles to light trucks. The machine incorporates: - a hydraulically operated tire support and loading system with wide operating ranges; - a computer controlled brake system to simulate braking maneuvers with ABS systems; - a complete sensorial system; - a data acquisition and control system continually monitoring and acting on the experimental variables, i.e., tire and belt speed, longitudinal slip, slip and camber angles, tire pressure, tire normal force, etc. As an application example, results are presented that adjust the parameter of the magic formula for a standard 175/70 R14 passenger vehicle tire. Accurate mathematical tire models are recognized as essential for the prediction of vehicle dynamic performances using simulation tools. 相似文献