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排序方式: 共有685条查询结果,搜索用时 968 毫秒
631.
This paper presents a new controller design method based on a data-mining polynomial algorithm. We show application of a polynomial
data-mining algorithm, where an input-state linearized polynomial vehicle model is developed for very low speed operation
and, without introducing any processes with fudge factors, control inputs of a nonlinear system are obtained in the original
coordinates. We verify the developed modeling method and controller design method through numerical experiments. 相似文献
632.
Y. Shi I.- T. Lee A. Md. Afsar J.- I. Song 《International Journal of Automotive Technology》2009,10(4):481-488
As the number of disabled people grows, independence and mobility become a priority for those individuals. To achieve this
goal, a ‘Turny-type power seat’ was developed in this study to assist a disabled person rise from a vehicle without trouble.
The design and modeling of the power seat were performed using AutoCAD and CATIA software. The major motions of the power
seat system are swiveling, sliding, and extending, which are accomplished primarily by DC motors, chains, and gears. Most
of the power seat parts were made from mild steel. Welding technology was used throughout the frame fabrication. To ensure
the safety and stability of the power seat, various tests were performed, and the results analyzed. The static analysis of
the power seat was carried out by ANSYS 11.0. The results showed that the power seat conformed to the Americans with Disabilities
Act (ADA) standards. The durability test was performed by repeatedly rotating and sliding the power seat under loading conditions.
Dynamic crash simulation was carried out using the LS-DYNA software. The durability test ensured a longer life of the power
seat, while the crash analysis showed a small rotational distortion that was not harmful to passengers. However, the front
seat had a slightly larger forward displacement, which was not comfortable for passengers. Therefore, further modifications
of the power seat should be done to improve the performance, with attention given to the reduction of the forward displacement
in the event of a crash. 相似文献
633.
Domestic automobile insurance claims were investigated to correlate the driver neck injury risk with the safety rating of
the head restraint, the severity of vehicle damage, and other human factors. The results of our statistical analysis reveal
that the risk of neck injury for the driver is significantly different for vehicle size, use, driver gender, driver age, impact
direction, accident location, and safety rating of head restraint, depending on vehicle the damage level which is assumed
to imply impact severity during a rear-end crash accident. One of the unique findings from domestic insurance claims from
low-speed rear-end crash accidents is the frequent reports of lower back injury together with whiplash. Thus, the risk of
lower back discomfort is also included in this statistical analysis. 相似文献
634.
U. B. Azimov K. S. Kim D. S. Jeong Y. G. Lee 《International Journal of Automotive Technology》2009,10(3):265-276
The concept of Low Temperature Combustion (LTC) has been advancing rapidly because it may reduce emissions of NOx and soot
simultaneously. Various LTC regimes that yield specific emissions have been investigated by a great number of experiments.
To accelerate the evaluation of the spray combustion characteristics of LTC, to identify the soot formation threshold in LTC,
and to implement the LTC concept in real diesel engines, LTC is modeled and simulated. However, since the physics of LTC is
rather complex, it has been a challenge to precisely compute LTC regimes by applying the available diesel combustion models
and considering all spatial and temporal characteristics as well as local properties of LTC. In this paper, LTC regimes in
a constant-volume chamber with n-Heptane fuel were simulated using the ECFM3Z model implemented in a commercial STAR-CD code.
The simulations were performed for different ambient gas O2 concentrations, ambient gas temperatures and injection pressures. The simulation results showed very good agreement with
available experimental data, including similar trends in autoignition and flame evolution. In the selected range of ambient
temperatures and O2 concentrations, soot and NOx emissions were simultaneously reduced. 相似文献
635.
FMECA (Failure Modes, Effects and Criticality Analysis) is a procedure used to identify potential failure modes, determine
causes and effects of failure modes and mitigate or remove its effects on system functional performance. For the last several
decades, FMECA has been widely used in industry, and specialized versions of FMEA have been developed for several industrial
sectors. For instance, MIL-1629a, SAE-J1739 and IEC-60812 have been mainly used in the military, automotive and electronics
industries, respectively. However, there is no specialized FMECA method for the railroad industry yet, despite a need for
highly reliable systems. Thus, in this study three specifications, MIL-1629a, SAE-J1739 and IEC-60812, were analyzed and compared
with one another, and characteristics and requirements of railroad systems were summarized. Then a specialized FMECA procedure
for railroad systems was proposed based on the processes documented in the specifications, characteristics and requirements
of railroad systems. Finally, the procedure was applied to a railroad system in order to validate its applicability. 相似文献
636.
C. L. Myung H. Lee K. Choi Y. J. Lee S. Park 《International Journal of Automotive Technology》2009,10(5):537-544
This study was focused on experimental comparisons of the effects of various vehicle certification modes on particle emission
characteristics of light-duty vehicles with gasoline, diesel, LPG, and low-carbon fuels such as bio-diesel, bioethanol, and
compressed natural gas, respectively. The particulate matter from various fueled vehicles was analyzed with the golden particle
measurement system recommended by the particle measurement programme, which consists of CVS, a particle number counter, and
particle number diluters. To verify particle number and size distribution characteristics, various vehicle emission certification
modes such as NEDC, FTP-75, and HWFET were compared to evaluate particle formation with both CPC and DMS500. The formation
of particles was highly dependent on vehicle speed and load conditions for each mode. In particular, the particle numbers
of conventional fuels and low-carbon fuels sharply increased during cold start, fast transient acceleration, and high-load
operation phases of the vehicle emission tests. A diesel vehicle fitted with a particulate filter showed substantial reduction
of particulate matter with a number concentration equivalent to gasoline and LPG fuel. Moreover, bio-fuels and natural gas
have the potential to reduce the particulate emissions with the help of clean combustion and low-carbon fuel quality compared
to non-DPF diesel-fueled vehicles. 相似文献
637.
B. Kim Y. Kim D. M. Chun S. H. Ahn J. D. Jang 《International Journal of Automotive Technology》2009,10(1):73-77
Improving the durability of an automotive V-belt pulley, which is commonly used in an automotive powertrain to transfer power
to other parts, is discussed. Fatigue life of the original V-belt pulley is predicted based on damage analysis by finite element
analysis (FEA). Stress history of the pulley during operation was found by performing consecutive static analyses on the pulley
as the pulley rotates. Assembly load (due to the tightening of the bolts) and operation load were considered to describe the
actual load conditions in a durability test. The contact condition from the belt was calculated and applied to the surface
of the pulley. Static analyses at 36 different positions of the pulley, every ten degrees of rotation, were performed to determine
the stress history of the pulley during operation. Using stress history data calculated from FE analysis, damage over one
rotation of the pulley was calculated and fatigue life, in number of rotations to failure, was estimated. An improvement to
the durability of the pulley was investigated by modifying the design of the pulley using FE analysis results. Durability
tests for the pulleys used in the analysis were carried out to verify the analytical results. Comparison between analysis
and experimental results showed that analytical results correlated with the experimental results closely. 相似文献
638.
大跨悬索桥箱形钢桁架梁的综合疲劳评定方法研究 总被引:1,自引:1,他引:0
根据大跨桥梁铜箱梁各类构件的受力特点建立了确定钢箱梁关键疲劳构件的评价模型,提出了基于结构有限元分析、应变监测信息、构件分级系统和桥梁结构人工检测等多方面信息综合评定关键疲劳构件的方法。以某大跨悬索桥钢箱梁结构为例,结合结构有限元数值计算和结构健康监测系统确定的关键钢箱梁截面,针对关键截面上的主要构件分布,利用应变传感器输出信息、结构有限元分析得到的应力分布信息、人工检测信息和桥梁主要构件的危险等级和易损等级信息,结合层次分析法和模糊综合评判理论确定了影响钢桥构件疲劳评定的各因素的权重,用综合隶属度评分法进行关键疲劳构件的等级评定。 相似文献
639.
Rollover mitigation for a heavy commercial vehicle 总被引:1,自引:0,他引:1
Y. I. Ryu D. O. Kang S. J. Heo J. H. In 《International Journal of Automotive Technology》2010,11(2):283-287
A heavy commercial vehicle has a high probability of rollover because it is usually loaded heavily and thus has a high center
of gravity. An anti-roll bar is efficient for rollover mitigation, but it can cause poor ride comfort when the roll stiffness
is excessively high. Therefore, active roll control (ARC) systems have been developed to optimally control the roll state
of a vehicle while maintaining ride comfort. Previously developed ARC systems have some disadvantages, such as cost, complexity,
power consumption, and weight. In this study, an ARC-based rear air suspension for a heavy commercial vehicle, which does
not require additional power for control, was designed and manufactured. The rollover index-based vehicle rollover mitigation
control scheme was used for the ARC system. Multi-body dynamic models of the suspension subsystem and the full vehicle were
used to design the rear air suspension and the ARC system. The reference rollover index was tuned through lab tests. Field
tests, such as steady state cornering tests and step steer tests, demonstrated that the roll response characteristics in the
steady state and transient state were improved. 相似文献
640.
The dynamic stability of a vehicle depends on various maneuvering features, such as traction, braking, and cornering. This
study presents nonlinear vehicle models for estimating the stability region and simulating the dynamic behavior of a vehicle.
Two types of vehicle models were found by considering the degrees of freedom and linearity. A simple model with nonlinear
tire dynamics is useful for determining the stability region, while a complex model (a multi-body dynamic model in MSC.ADAMS)
is appropriate for carrying out accurate simulations. Actual data for a mid-sized passenger car were used, and the models
were validated by comparison with test results. 相似文献