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921.
Virtualization is attracting significant interest in the automotive industry because it enables a highly secure and reliable
computing environment. More importantly, virtualization maintains the same operating environment for legacy automotive software
while exploiting the benefits of widely adopted multicore platforms. To exploit the virtualization technology in an automotive
system, it is important to predict the WCET of an automotive application running on a virtual machine monitor (VMM). Unfortunately,
the task is challenging because of difficulties in analyzing complicated interactions between a VMM and a guest OS. There
are no known attempts to predict the WCET of an application in such an environment. In this paper, we propose a hierarchical
and parametric WCET prediction framework. We divide the problem into two subproblems. First, we model the WCET of an application
as a function of WCETs of system calls provided by a guest OS. Second, we model WCETs of a system call as a function of WCETs
of VMM services. To establish this framework, we clearly identify the places and times of VMM services invoked during the
execution of an application. At the time of deployment, the WCET of an application is instantiated by composing the WCET models
altogether. We have performed experiments with the proposed framework by predicting the WCETs of sample programs on various
virtual and real machine platforms. These experimental results effectively demonstrate the viability of the proposed framework. 相似文献
922.
C. -H. Park H. -J. Shim D. -H. Choi J. -K. Kim S. -M. Lee 《International Journal of Automotive Technology》2012,13(1):61-75
Rubber isolators are mounted between a cooling module and a carrier to isolate the car body from vibration due to the rotation
of the cooling fan. The isolators should be durable against fatigue loads originating from fan rotation and road disturbance.
Thus, the design of rubber isolators is required to maximize both vibration isolation and fatigue life. In this study, the
shapes of the rubber isolators are optimally designed using a process integration and design optimization (PIDO) tool that
integrates the various computer-aided engineering (CAE) tools necessary for vibration and fatigue analyses, automates the
analysis procedure and optimizes the design solution. In this study, we use CAE models correlated to the experimental results.
A regression-based sequential approximate optimizer incorporating Process Integration, Automation and Optimization (PIAnO),
a commercial PIDO tool, is employed to handle numerically noisy responses with respect to the variation in design variables.
Using the analysis and design procedure established in this study, we successfully obtained the optimal shapes of the rubber
isolators in two different cooling modules; these shapes clearly have better vibration isolation capability and fatigue lives
than those of the baseline designs used in industry. 相似文献
923.
Smooth motion control of the adaptive cruise control system by a virtual lead vehicle 总被引:1,自引:0,他引:1
The adaptive cruise control system maintains the appropriate distance to the lead vehicle when the lead vehicle exists and
maintains the desired speed when no lead vehicle is detected. A virtual lead vehicle scheme is introduced to make the switching
between the speed control algorithm and the distance control algorithm unnecessary and simplify the structure of the control
system. The speed and the position of the virtual vehicle can be decided by the control system according to the current situation.
Smoother responses are achieved by the virtual lead vehicle scheme compared to the conventional mode switching scheme. This
method is also shown to provide a good reaction for when a lead vehicle cuts in or out. A linear quadratic controller with
variable weights is suggested to control the virtual lead vehicle. This scheme shows improved performance in terms of passenger
comfort and fuel efficiency of the host vehicle. 相似文献
924.
J. Choi S. S. Kim S. S. Rhim J. H. Choi 《International Journal of Automotive Technology》2012,13(2):255-261
This study uses an elastohydrodynamic lubrication model coupled with multi-flexible-body dynamics (MFBD) to analyze dynamic
bearing lubrication characteristics, such as pressure distribution and oil film thickness. To solve the coupled fluid-structure
interaction system, this study uses an MFBD solver and an elastohydrodynamics module. The elastohydrodynamics module passes
its force and torque data to the MFBD solver, which can solve general dynamic systems that include rigid and flexible bodies,
joints, forces, and contact elements. The MFBD solver analyzes the positions, velocities, and accelerations of the multi-flexible-body
system while incorporating the pressure distribution results of the elastohydrodynamics module. The MFBD solver then passes
the position and velocity information back to the elastohydrodynamics solver, which reanalyzes the force, torque, and pressure
distribution. This iteration is continued throughout the analysis time period. Other functions, such as mesh grid control
and oil hole and groove effects, are also implemented. Numerical examples for bearing lubrication systems are demonstrated. 相似文献
925.
The controller area network (CAN) protocol is widely used for in-vehicle network (IVN) systems, and many automotive companies
also use the CAN in chassis network systems. However, the increasing number of electronic control units (ECUs) dictated by
the need for more intelligent and fuel-efficient functions requires an IVN system with a greater transmission capacity and
less network delay. Automotive companies have tried several approaches such as segmenting CAN systems and developing time-triggered
protocols. This paper presents a practical method for increasing the transmission capacity and reducing the network delay
in CAN systems using dual communication channels with a traffic-balancing algorithm based on Kalman prediction to forecast
the traffic on each channel and allocate frames to the one that is most appropriate. An experimental testbed using commercial
microcontrollers with two or more CAN protocol controllers was used to demonstrate the feasibility of the Kalman traffic-balancing
algorithm. Experimental results show that the traffic-balancing CAN system with Kalman prediction reduced the transmission
delay of all priority messages compared to that of a simple method, such as a channel-switching CAN, without sacrificing the
performance for high-priority messages. 相似文献
926.
S. Kim K. Park H. J. Song Y. K. Hwang S. J. Moon H. S. Ahn M. Tomizuka 《International Journal of Automotive Technology》2012,13(1):87-95
Developed in this research is a control logic for the ARC (Active Roll Control) system that uses rotary-type hydraulic stabilizer
actuators at the front and rear axles. The hydraulic components of the system were modeled in detail using AMESim, and a driving
logic for the hydraulic circuit was constructed based upon the model. The performance of the driving logic was evaluated on
a test bench, and it demonstrated good pressure tracking capability. The control logic was then designed with the target of
reducing the roll motion of the vehicle during cornering. The control logic consists of two parts: a feedforward controller
that generates anti-roll moments in response to the centrifugal force, and a feedback controller that generates anti-roll
moments in order to make the roll angle to follow its target value. The developed ARC logic was evaluated on a test vehicle
under various driving conditions including a slowly accelerated circular motion and a sinusoidal steering. Through the test,
the ARC system demonstrated successful reduction of the roll motion under all conditions, and any discomfort due to the control
delay was not observed even at a fast steering maneuver. 相似文献
927.
S. H. Jeong J. E. Lee S. U. Choi J. N. Oh K. H. Lee 《International Journal of Automotive Technology》2012,13(7):1133-1140
Recently, the advanced driver assistance system (ADAS), which helps mitigate car accidents, has been developed using environmental detection sensors, such as long and short range radar, lidar, wide dynamic range cameras, ultrasonic sensors and laser scanners. Among these detection sensors, radars can quickly provide drivers with reliable information about the velocity, distance and direction of a target obstacle, as well as information about the vehicle in changing weather conditions. In the adaptive cruise control system (ACCS), three radar sensors are usually needed because two short range radars are used to detect objects in the adjacent lane and one long range radar is used to detect objects in-path. In this paper, low-cost radar based on a single sensor, which can detect objects in both the adjacent lane and in-path, is proposed for use in the ACCS. Before designing the proposed radar, we analyzed the world-wide radar technology and market trends for ACCS. Based on this analysis, we designed a novel radar sensor for the ACCS using radar components, such as an antenna, transceiver module, transceiver control module and signal processing algorithm. Finally, target detection experiments were conducted. In the experimental results, the proposed single radar can successfully complete the detection required for the ACCS. In the conclusion, the perspective and issues in the future development of the ACCS radar are described. 相似文献
928.
A.B. Chelani S. Devotta 《Transportation Research Part D: Transport and Environment》2007,12(8):596-600
This study evaluates the potential of nonlinear time series analysis based methods in predicting the carbon monoxide concentration in an urban area. To establish the functional relationship between current and future observations, two models based on local approximations and neural network approximations are used. To compare the performance of the models, an autoregressive integrated moving average model is also applied. The multi-step forecasting capabilities of the models are evaluated. 相似文献
929.
930.
Kamlesh S.?VaryaniEmail author Appapillai?Thavalingam Parmeswarn?Krishnankutty 《Journal of Marine Science and Technology》2004,9(1):24-31
To improve the formulation of ship–ship interaction forces and moments in a mathematical model of a ship maneuvring simulator, we developed a new generic mathematical model for the overtaking maneuver. This process involves using the numerical results, which provide a potentially complete set of data from which (within the constraints of the numerical modelling) everything necessary can be acquired. We found that the new generic mathematical model is as accurate as the numerical model. It is also more accessible to a navigator, master, or pilot, who could use it on a palmtop computer by keying in a few numberical estimates of the size, position, and speed of the neighboring ship and receive almost instant aneous results, giving time for a refined strategy to be validated if necessary. These results can also readily be used by simulation program developers to simulate the worst possible scenarios. 相似文献