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161.
Vehicle detection is a crucial issue for driver assistance system as well as for autonomous vehicle guidance function and
it has to be performed with high reliability to avoid any potential collision. The vision-based vehicle detection systems
are regarded promising for this purpose because they require little infrastructure on a highway. However, the feasibility
of these systems in passenger car requires accurate and robust sensing performance. In this paper, a vehicle detection system
using stereo vision sensors is developed. This system utilizes feature extraction, epipoplar constraint and feature matching
in order to robustly detect the initial corresponding pairs. The proposed system can detect a leading vehicle in front and
can estimate its position parameters such as the distance and heading angle. After the initial detection, the system executes
the tracking algorithm for the vehicles in the lane. The proposed vehicle detection system is implemented on a passenger car
and its performances are verified experimentally. 相似文献
162.
Analysis of a regenerative braking system for Hybrid Electric Vehicles using an Electro-Mechanical Brake 总被引:3,自引:0,他引:3
J. K. Ahn K. H. Jung D. H. Kim H. B. Jin H. S. Kim S. H. Hwang 《International Journal of Automotive Technology》2009,10(2):229-234
The regenerative braking system of the Hybrid Electric Vehicle (HEV) is a key technology that can improve fuel efficiency
by 20∼50%, depending on motor size. In the regenerative braking system, the electronically controlled brake subsystem that
directs the braking forces into four wheels independently is indispensable. This technology is currently found in the Electronic
Stability Program (ESP) and in Vehicle Dynamic Control (VDC). As braking technologies progress toward brake-by-wire systems,
the development of Electro-Mechanical Brake (EMB) systems will be very important in the improvement of both fuel consumption
and vehicle safety. This paper investigates the modeling and simulation of EMB systems for HEVs. The HEV powertrain was modeled
to include the internal combustion engine, electric motor, battery and transmission. The performance simulation for the regenerative
braking system of the HEV was performed using MATLAB/Simulink. The control performance of the EMB system was evaluated via
the simulation of the regenerative braking of the HEV during various driving conditions. 相似文献
163.
K. O. Lee S. K. Hong Y. K. Kang H. J. Yoon S. S. Kang 《International Journal of Automotive Technology》2009,10(6):697-702
A double-quenching (D/Q) process is proposed for heat-treating high carbon-chromium bearing steels to improve the fatigue
properties through refinement of the microstructure. The new heat treatment method has two steps: The first step is a nitrocarburizing
process that results in high surface hardness and lowers the transformation temperature. The second step is the same as in
the conventional quenching process but can be conducted at a considerably lower temperature than in conventional quenching.
The microstructure in the material that is caused by the D/Q heat treatment is much finer than in the conventional Q/T (quenching
and tempering) process. In order to quantify the performance of the proposed heat-treatment process, various mechanical property
tests are carried out. The rolling contact fatigue life of double-quenched bearing steels was eight times higher than in bearing
steels that were treated by conventional Q/T. 相似文献
164.
THAMANAM Srinivasa Rao NAGARAJA Potti NAIK B Balaji MANJUNATHACHARI K 《上海交通大学学报(英文版)》2021,(4):488-493
Data security plays a vital role in the current scenario due to the advanced and sophisticated data access techniques.Present development in data access is alwa... 相似文献
165.
ABSTRACT This paper studies incentive-based subsidy to transit systems to improve performance. It derives a formula for optimal effort that equalizes marginal cost and marginal benefit and derives some principles from it among which is that the larger the value of a transit system’s performance criterion the larger the effort it will exert to improve it. Next, using a constrained cost minimization approach it derives a nonlinear cost function that includes optimal effort and estimates it using an unbalanced panel data of single mode U.S. bus transit systems. The results show that optimal effort is the equivalent of seven full-time employees (15,243 labor hours) per year and in real terms it results in 0.6% cost saving (US$198,331) and US$836,796 in incentive subsidy per observation. The implications of these findings are examined. 相似文献
166.
Transportation - Freight generation (FG) models are important to transportation authorities and planning agencies as they can be used to forecast local/regional/state/national freight movements for... 相似文献
167.
Douglas K. Fleming 《Maritime Policy and Management》1989,16(2):93-107
More than a century ago far-sighted railroad builders and steamship operators were seeking the shortest intermodal itineraries between the eastern United States and the Orient. A combination of locational fact and the factual outcomes of 19th century railroad building left Chicago roughly equidistant in railway mileage from what became the four great US West-Coast port complexes in the Los Angeles, San Francisco, Portland and Seattle regions. Their nearly equivalent rail access to Chicago and points east has renewed significance in the container era.
This paper concerns the efforts of US Pacific seaboard ports to stay 'on the beaten track' with respect to container shipments between Asia and the eastern United States. The West-Coast ports are transit points dividing the transcontinental and transoceanic segments of long intercontinental journeys. From origins to destinations there are, in fact, many possibly feasible itineraries, including all-water routes.
The West-Coast ports have considerable control over their own site improvements. On the other hand, with respect to transiting container traffic, the ports may influence, but are unlikely to control, their own situations. Since the major container port facilities are very often on long-term lease to large intermodal carriers, the latter are making the important shipping and routeing decisions. The carriers tend in fact to set the tone and level of port competition.
What is the nature of the competition between container ports? Is it a figment of the publicist's imagination and perpetuated by irrelevant statistical boasting? Is it perhaps something forced on the ports by carriers eager to play one port off against another in a 'lowest bid' game? At what geographical scale might port competition be most useful or, maybe, least wasteful? 相似文献
This paper concerns the efforts of US Pacific seaboard ports to stay 'on the beaten track' with respect to container shipments between Asia and the eastern United States. The West-Coast ports are transit points dividing the transcontinental and transoceanic segments of long intercontinental journeys. From origins to destinations there are, in fact, many possibly feasible itineraries, including all-water routes.
The West-Coast ports have considerable control over their own site improvements. On the other hand, with respect to transiting container traffic, the ports may influence, but are unlikely to control, their own situations. Since the major container port facilities are very often on long-term lease to large intermodal carriers, the latter are making the important shipping and routeing decisions. The carriers tend in fact to set the tone and level of port competition.
What is the nature of the competition between container ports? Is it a figment of the publicist's imagination and perpetuated by irrelevant statistical boasting? Is it perhaps something forced on the ports by carriers eager to play one port off against another in a 'lowest bid' game? At what geographical scale might port competition be most useful or, maybe, least wasteful? 相似文献
168.
169.
This paper is an attempt to develop a generic simulation‐based approach to assess transit service reliability, taking into account interaction between network performance and passengers' route choice behaviour. Three types of reliability, say, system wide travel time reliability, schedule reliability and direct boarding waiting‐time reliability are defined from perspectives of the community or transit administration, the operator and passengers. A Monte Carlo simulation approach with a stochastic user equilibrium transit assignment model embedded is proposed to quantify these three reliability measures of transit service. A simple transit network with a bus rapid transit (BRT) corridor is analysed as a case study where the impacts of BRT components on transit service reliability are evaluated preliminarily. 相似文献
170.
Wayne K. Talley 《Transportation》1986,13(3):201-210
Two contrasting methodologies have appeared in the literature for selecting indicators to evaluate the performance of public transit firms. One methodology specifies the criteria that the selected performance indicators must satisfy. The other methodology requires the specification of operating objectives by the transit firm for the purpose of then selecting performance indicators. This paper compares the two methodologies and discusses the attributes of one methodology versus those of the other methodology. Also, a major difference in the premises of the two methodologies is demonstrated. 相似文献