全文获取类型
收费全文 | 441篇 |
免费 | 5篇 |
专业分类
公路运输 | 287篇 |
综合类 | 6篇 |
水路运输 | 89篇 |
铁路运输 | 3篇 |
综合运输 | 61篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 6篇 |
2019年 | 1篇 |
2018年 | 37篇 |
2017年 | 25篇 |
2016年 | 32篇 |
2015年 | 10篇 |
2014年 | 32篇 |
2013年 | 48篇 |
2012年 | 38篇 |
2011年 | 47篇 |
2010年 | 39篇 |
2009年 | 43篇 |
2008年 | 40篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有446条查询结果,搜索用时 62 毫秒
411.
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
412.
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
413.
Partial range scaling method based washout algorithm for a vehicle driving simulator and its evaluation 总被引:2,自引:0,他引:2
M. S. Kim Y. G. Moon G. D. Kim M. C. Lee 《International Journal of Automotive Technology》2010,11(2):269-275
Unlike an actual vehicle, a vehicle driving simulator (VDS) has limited kinematics, workspace, and bounded dynamic characteristics
making it very difficult to simulate dynamic motions of an actual vehicle. To solve these problems, a washout algorithm was
developed. The developed algorithm restricts the workspace of the VDS to within the kinematic limit and makes the person driving
the VDS perceive movement of an actual vehicle. However, the classic washout algorithm contains several problems, such as
time delay and the generation of a wrong motion signal caused by characteristics of the filters. So the driver feels “simulator
sickness,” such as fatigue, nausea, headache and so on because of differences between the sense of movement of the VDS and
that of a real vehicle. In this paper, a partial range scaling method based washout algorithm, including a tilt coordination
system, is developed to enhance the perception of motion and reduce simulator sickness. It is verified by a simulation, a
survey, and a bio signal analysis using an electrocardiogram (ECG). 相似文献
414.
The vibrational characteristics of automotives during idling were studied experimentally by considering the axial forces of
the drive shaft and the spider positions in a constant-velocity joint. The generated forces, such as PF (plunging force) and
GAF (generated axial force) in the assembly of the drive-shaft module, were measured directly by an experimental apparatus.
Measurements of the GAF and PF did not show the same trends as the joint angles. They depended instead on the types of CV
joints. In addition, the relationship between the offset values of the shaft and the spider positions in the tulip of the
constant-velocity joint were studied. As a result, the idle vibration characteristics were affected by the variation of the
spider positions and the vibrational characteristics in the axial direction of the shaft, including the amplitude and the
harmonic periods. 相似文献
415.
S. I. Kim G. H. Lee J. J. Lee J. P. Hong 《International Journal of Automotive Technology》2010,11(2):277-282
In this paper, a simple design method for improving the performance of an interior permanent magnet synchronous motor (IPMSM),
for driving the air-conditioning compressor used in hybrid electric vehicles, is presented. There are many design methods
that optimize the IPMSM. Each method deals with a variety of design factors, such as slot opening, pole arc, and rotor shape.
However, as the number of design variables increases, a lot of modeling and analysis time is needed in order to improve the
characteristics of an IPMSM. This paper demonstrates that the optimization of a double-layer IPMSM, satisfying the given design
conditions, is possible with only a flux barrier shape design. Then, response surface methodology is applied as the optimization
method, and the validity of the design approach is verified by comparison with test results. 相似文献
416.
提出了用低成本的单个数字信号处理器(DSP)控制多个单相功率因数补偿(PFC)模块的新方案.该方案允许不同电流额定值的多个模块并联工作,并通过单个DsP控制.基于DSP的控制,易于分流,设备小巧.文章叙述了每个PFC模块电流的测量技术和多个模块工作的输出电压和输入电流闭环控制方法.在该设计例子中,开关频率设定为120kHz,2级连续导通模式的PFC并联工作,并由单个TMS320LF2407DSP控制.实验结果表明,现代开关电源可采用该方案. 相似文献
417.
Hyuk Kim Graduate student Yong-San Yoon Professor Ph.D 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1995,24(10):759-780
The objective of this study is to develop a control law for a semi-active suspension for the purpose of ride quality improvement. The semi-active control law is determined by reproducing the control force of an optimally controlled active suspension while suppressing its damping coefficient variation. The performance index of the optimal control for the active suspension is modified to include frequency-shaping by use of Parseval's theorem, which allows us to de-emphasize the effects of particular variables over specific frequency bands.
Through the numerical simulations, it was found that the semi-active suspension may reduce the vertical acceleration of the driver's seat and the sprung mass motions significantly. The road-holding and tire deflections were not affected much. 相似文献
Through the numerical simulations, it was found that the semi-active suspension may reduce the vertical acceleration of the driver's seat and the sprung mass motions significantly. The road-holding and tire deflections were not affected much. 相似文献
418.
419.
This paper describes a design of a real-time conversion system of wheel linear accelerations into tire lateral forces. Though the tire lateral forces are important elements for analyzing vehicle dynamic control performances, they cannot be easily measured in real-time owing to the non-linearities of tire dynamics, friction, and slippage on road. In this paper, we propose a practical direct method using wheel linear accelerations in order to estimate tire lateral forces transmitted into the vehicle in real-time. A simplified vehicle model based on force-acceleration analysis is proposed to assure the real-time performance. The acceleration values are obtained using three-axis accelerometers attached on each wheel location. For conditioning and rectifying the acceleration signals, a signal transducer is designed using a digital filter. And in order to investigate the feasibility and real-time performance, a prototype of signal transducer is fabricated using a digital signal processor. The experimental results and performance are validated with the road test results using six-component wheel force transducers. 相似文献
420.
Due to environmental concerns and safety regulations in the automotive industry, the development of strong and lightweight cars has been a hot issue in the last decade. One solution for this purpose would be to use high-strength steel (HSS) and advanced high-strength steel (AHSS). These materials can make the car lighter while maintaining the crash resistance of the vehicle. HSS and AHSS have more resistance force in the die structure compared with conventional steel due to their higher yield and tensile strength and thus, these materials have a greater effect on die deformation during the sheet metal forming process. As a result, die deformation can affect the blank sheet’s drawn pattern, strain, and stress as well as springback. This study presents a sheet metal forming simulation that considers die deformation. The simulation process was compared with conventional simulation methods. Our results indicate that the sheet metal forming simulation with die deformation consideration provides useful information on the die structure as well as formability and springback. 相似文献