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871.
872.
M. C. Ircha 《Maritime Policy and Management》1995,22(4):281-294
U.S. ports are facing competitive pressures similar to those being felt by ports elsewhere around the world. Despite the public enterprise nature of U.S. port authorities, they tend to function as 'business-like' organizations. This enterprise-like approach stems from their evolution from being primarily private railroad ports in the 19th century to public competitive port authorities in the 20th century. This paper provides an overview of the evolution of U.S. ports and the ongoing effect of earlier legislation, the varied resulting institutional structures, and current national and regional level issues. Although there is no national ports plan or strategy in the U.S.A. (the Constitution limits federal actions in the ports field) the federal government is involved in providing dredging services through the Army Corps of Engineers, navigation aids via the Coast Guard and other minor port-related services. U.S. ports typically come under the jurisdiction of state or local governments. Increasing competition coupled with other port issues (growing financial constraints, difficulties in obtaining dredging permits, environmental concerns and restricted landside access) is forcing some U.S. ports to enter into strategic alliances with others at a regional level. 相似文献
873.
874.
875.
M. C. Ircha 《Maritime Policy and Management》1993,20(1):51-66
Canada's federal government is responsible for ports. Despite this, an integrated national ports system has not been established. The Canadian system includes: the Canada Ports Corporation; Harbour Commissions; and Transport Canada's Public Harbours. These are historic divisions. Following a failed 1970s attempt to place all ports within Transport Canada, in 1983 parliament opted for a Crown corporation model in establishing the Canada Ports Corporation for Canada's major ports. This paper addresses the question of whether, in today's increasingly competitive environment, a more integrated and businesslike national system of ports is required. Alternative systems range from centralization to regionalization and enhanced 'commercialization' of local ports to privatization. A suggested alternative for Canada includes incorporating all commercial ports within the Canada Ports Corporation, using a regional system for planning, and augmenting local autonomy of financially self-sufficient ports by making them crown corporations. Eventual privatization of the expanded Canada Port Corporation is also considered. 相似文献
876.
C. W. Ronosulistyo P. F. Sweatman P. N. Joubert 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1976,5(4):239-264
The significance of the effects of steering compliance and aerodynamic life on high speed automobile's steering response was investigated on two vehicles, a Ford Falcon XW (1969) station-wagon and a GM-Holden Kingswood HQ (1974) sedan. An aerofoil was mounted above the front bumper bar of the Ford Falcon to enable the simulation of vehicles with very degraded aerodynamic characteristics. Mathematical analysis showed the importance of the inclusion of steering compliance effects in determining stability factor, and hence the vehicle's high speed yaw rate sensitivity. Both experiments and theory showed that the actual high speed yaw rate response is not significantly less than that predicted from a low speed skid pad test, however, slight errors were found which are likely to be due to steering system nonlinearity and the effects of aerodynamic lift. 相似文献
877.
Camille N. Kamga Kyriacos C. Mouskos Robert E. Paaswell 《Transportation Research Part C: Emerging Technologies》2011,19(6):1215-1224
This paper presents results from a research case study that examined the distribution of travel time of origin–destination (OD) pairs on a transportation network under incident conditions. Using a transportation simulation dynamic traffic assignment (DTA) model, incident on a transportation network is executed under normal conditions, incident conditions without traveler information availability, and incident conditions assuming that users had perfect knowledge of the incident conditions and could select paths to avoid the incident location. The results suggest that incidents have a different impact on different OD pairs. The results confirm that an effective traveler information system has the potential to ease the impacts of incident conditions network wide. Yet it is also important to note that the use of information may detriment some OD pairs while benefiting other OD pairs. The methodology demonstrated in this paper provides insights into the usefulness of embedding a fully calibrated DTA model into the analysis tools of a traffic management and information center. 相似文献
878.
Y. -G. Kim S. -W. Kim C. -K. Park T. -W. Park Y. -M. Kim 《International Journal of Automotive Technology》2011,12(1):51-58
It is necessary to guarantee the proper brake force to stop a train safely in a limited distance and o adjust its speed. Currently,
most trains are run by electrical power and have a combined electrical and mechanical (friction) braking system. The mechanical
brake force is determined by many parameters, such as the friction coefficient of the brake disc and pad, the pressure in
the brake cylinder, the brake cylinder’s cross sectional area and the brake linkage ratio. In general, the friction coefficient
data of the brake disc and pad have been taken through a dynamo-test in a laboratory, but these data might not be well matched
with real data under operating conditions because of the difference in data acquisition conditions. The present study examined
two methodologies that can measure the friction coefficient of the brake pad and disc based on a train’s real operating conditions.
The first method was the direct method, which measured the brake force and clamping force applied on the mechanical brake
by using strain gauges installed on the brake to calculate the friction coefficient. The second was an indirect method that
obtained the friction coefficient by using the weight of the train and the equivalent brake force. Those variables were calculated
from the longitudinal dynamic characteristics, such as resistance to motion, gradient resistance and curved resistance. These
two methodologies were used to obtain the disc-pad friction coefficient for the mechanical brakes of a Korean high-speed train
(HSR350x). 相似文献
879.
M. S. Kim S. B. Yu S. Y. Lee M. C. Lee 《International Journal of Automotive Technology》2011,12(5):755-762
For developing telematics devices, traditional development methods include the unit function test, compatibility test and
T-Car, which have some limitations. Telematics devices have various functions that require accounting for the interactions
among three major elements of automotive electronics: the vehicle, the device unit and driver. The KAAS (KATECH Advanced Automotive
Simulator) system is a virtual-reality-based test environment designed to test and analyze the three elements in one place.
One of the difficult functions when constructing such VR (Virtual Reality)-based telematics test environment is to develop
a test method for the LBS (Location-Based Service) function such as a car navigation demanding the GPS (Global Positioning
System) satellite signals because KAAS is in a fixed laboratory. To overcome these problems, a real-time GPS simulation system,
which can be integrated with KAAS, is needed because the location of the vehicle in virtual space is determined purely by
the driver’s personal intention while driving virtually. This paper presents new concepts needed to construct a VR-based telematics
test environment to generate a GPS RF signal, which reflects the continuously changing vehicle location during virtual driving
in real-time. To construct this system, the coordinate transform must be conducted from a rectangular coordinate system that
is compatible with a virtual 3D DB that is used to construct a 3D image for KAAS using a WGS84 and a longitude-latitude coordinate
system compatible with a GPS simulator. Moreover, the real-time HILS (Hardware In Loop Simulation) systems and the CDMA (Code
Division Multiple Access) simulation system are developed to evaluate telematics devices. Finally, we show its applications
and results. 相似文献
880.
Shipbuilding is the subject of public policies in a number of countries, as it is considered a strategic industry and has an impact on employment levels in many regions. Establishing performance targets can be a challenge to shipbuilding policy makers. This paper suggests an approach to this problem, based on the Data Envelopment Analysis (DEA) technique. This approach makes it feasible to estimate productivity and building time potential, taking into account the output pattern, technological level and quality of the industrial environment of the country or region. The methodology is applied to the analysis of the competitive potential of some Brazilian shipyard models. The benchmarking analysis was carried out for a sample of shipyards from the world's principal shipbuilding blocks. 相似文献