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991.
In this study, a 3-D CFD simulation and laser diagnostics were developed to understand the characteristics of soot generation
in a diesel diffusion flame. The recently developed RANS (Reynolds-averaged Navier-Stokes equations) hybrid combustion model
(Extended Coherent Flame Model — 3 Zones, ECFM-3Z model) was used. This industrial, state-ofthe-art model of the diffusion
flame is commonly used in diesel combustion models as well as for propagating (premixed) flame combustion. The simulation
results were validated with measurements from a constant volume combustion chamber. The experiment revealed that soot accumulated
in the chamber where the temperature decreased. Where the temperature increased rapidly, only a little soot accumulated. The
temperature and soot distribution were independently examined using both the two-color method and a 3-D CFD simulation for
a turbulent diesel diffusion flame. 相似文献
992.
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
993.
D. M. Chun J. C. Lee J. C. Yeo S. H. Ahn S. S. Hong J. D. Jang 《International Journal of Automotive Technology》2011,12(2):273-280
In new slim torque converters, lock-up clutches are used to provide high fuel efficiency at low speed. However, the slimness
of the converters causes difficulty in heat dissipation, which may damage the friction material and shorten its life span.
A cooling hole in the lock-up piston reduces the heat but also reduces the torque because oil flows through the hole due to
the pressure difference between the two faces of the piston. In the early stages of the development of this type of torque
converter, designers must consider the minimum flow rate required to cool the friction material and the minimum torque capacity
required to transmit the engine torque. This research explored two methods of estimating these parameters. In the first method,
an estimation equation was derived by combining the response surface method with physical properties such as the centrifugal
force, a sudden expansion, a sudden contraction, and the steady flow energy equation. The second method involved the use of
an artificial neural network. The feasibility of the estimates based on statistics and on the artificial neural network were
confirmed in the design stage by comparing experimental and estimated data. An estimation program was created using the C#.Net
language and has been used for actual torque converter designs by the Korea Powertrain Company. 相似文献
994.
D. H. Lee S. N. Bai D. Y. Kwak J. I. Jung 《International Journal of Automotive Technology》2011,12(2):251-264
Vehicle-based applications were recently introduced to improve traffic safety and efficiency. These applications are classified
into either safety-oriented or non-safety-oriented applications. Safety-oriented applications are typically provided by means
of vehicle-to-vehicle (V2V) communications to support reliable and fast alert message propagation to all surrounding vehicles
when an emergency occurs on the road. In vehicular ad-hoc network (VANET) broadcast-based packet forwarding is typically preferred
for the propagation of urgent traffic-related information to all reachable nodes within a specified dangerous region. However,
this approach may cause broadcast storm problems, which can lead to serious contention between transmissions from adjacent
nodes. In this paper, we propose an alert message propagation scheme that is based on selective forwarding and aims to i)
minimize the number of rebroadcasting nodes and ii) guarantee reliable and fast alert message delivery to all reachable nodes.
Our scheme was evaluated using two different highway scenarios. The simulation results demonstrated that the performance of
the proposed scheme was better than that of existing broadcast schemes in terms of the message delivery latency, the message
delivery ratio, and the message rebroadcasting ratio. 相似文献
995.
Recently, to reduce environmental pollution and the waste of limited energy resources, there is an increasing requirement
for higher engine efficiency and lower levels of harmful emissions. A premixed charge compression ignition (PCCI) engine,
which uses a 2-stage type injection, has drawn attention because this combustion system can simultaneously reduce the amount
of NOx and PM exhausted from diesel engines. It is well known that the fuel injection timing and the spray angle in a PCCI
engine affect the mixture formation and the combustion. To acquire two optimal injection timings, the combustion and emission
characteristics of the PCCI engine were analyzed with various injection conditions. The flame visualization was performed
to validate the result obtained from the engine test. This study reveals that the optimum injection timings are BTDC 60° for
the first injection and ATDC 5° for the second injection. In addition, the injection ratio of 3 to 7 showed the best NOx and
PM emission results. 相似文献
996.
Sliding-mode-based parameter identification with application to tire pressure and tire-road friction
This paper presents a method of simultaneous estimation of tire pressure and tire-road friction. A sliding-mode scheme is
designed to identify the system state and the parameter variation of a torsional tire system, which greatly depend on the
change in tire pressure. Then, the recursive least-squares method with a forgetting facto is used to estimate the parameter
variations of the tire system and the tire-road friction force without a friction model using the information retrieved from
the equivalent input for sliding motion. A simulation study is performed to illustrate the effectiveness of the proposed method. 相似文献
997.
B. Assadsangabi F. Daneshmand N. Vahdati M. Eghtesad Y. Bazargan-Lari 《International Journal of Automotive Technology》2011,12(6):921-932
In this paper, first a new design for a disk-type magneto-rheological (MR) brake for automotive applications is proposed and
then, a finite element analysis is performed to analyze the resulting magnetic field intensity distribution within the MR
brake configuration. This finite element model of the brake is then utilized in a optimization process which incorporates
Genetic Algorithm (GA) to obtain optimal design parameters. The optimization process goal is to increase the braking torque
capacity of the brake while keeping the weight of the brake as low as possible. Although, the braking torque of the present
design is larger compared to the previous designs, the braking toque capacity of the present design is still smaller than
the required braking torque for automobiles. 相似文献
998.
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
999.
S. -J. Kim W. -J. Jeon J. -J. Park B. -S. Moon Y. -J. Cho Y. -I. Seo N. -K. Park K. Son 《International Journal of Automotive Technology》2011,12(6):951-958
A perturbation mark is occasionally produced on the velocity indicator of the cluster panel of a vehicle during a vehicle
collision. This mark can be used to estimate the velocity of the vehicle at the moment of the vehicle’s impact. In this study,
the effect of the impact velocity and the deceleration of the vehicle on the perturbation mark were investigated, and an analysis
of the driver’s injury was also conducted through a numerical pulse representation and computer simulations. Sled and pendulum
tests were used to replicate the conditions that produce a perturbation mark on the velocity indicator of a cluster panel.
It was verified that a higher peak acceleration is more likely than the impact velocity to cause a perturbation mark. According
to the computer simulation results, a driver’s injury could be more severe at higher peak accelerations with a constant impact
velocity. If a perturbation mark, which can be used to estimate the impact velocity, is found while investigating a vehicle
accident, this mark reveals that the acceleration was higher than that listed in the related crash report. Therefore, the
injuries of the occupants could be more serious than those expected at the reported impact velocity. 相似文献
1000.
杨娥 《广州航海高等专科学校学报》2014,(2):52-55
根据CDIO工程教育理念,结合应用型路桥专业人才培养的特点,探讨了基于CDIO理念的应用型本科路桥专业课程体系和目标体系,并将该理念贯穿在课程内容教学的全过程。运用CDIO教育模式对路桥专业课程的内容、设计进行探讨和实践,在教学中以问题为导向,引导学生主动学习,主动探寻学科知识,促使学生理论与实践的结合能力、创新能力和团队合作能力等有所提高。 相似文献