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351.
Using the recent anthropometry of the North American population, human body models were developed for seat comfort simulation.
The external geometry of the models was acquired from the three-dimensional whole body laser scan of recruited volunteers
in a driving position. The selection criteria for volunteers with standard size and shape were derived from a statistical
factor analysis of the Size USA database. As a practical application of the model in a design process, comfortable driving
postures were constructed by adopting the cascade prediction model (CPM), which takes into account both interior package layout
and the driver’s anthropometry. The detail modeling process of finite element modeling and its validation results against
volunteer measurements are introduced. 相似文献
352.
In this paper, we present a method for estimating the natural frequencies of various engine valve springs such as constant
pitch, two-step variable pitch, three-step variable pitch, and progressive springs. Since a valve spring’s surging amplitude
is magnified when the spring’s natural frequency coincides with the frequency of the cam profile harmonic components, estimating
the natural frequency of the spring is the first step in predicting valve spring surging phenomena. A new method for calculating
the valve spring’s natural frequency is proposed in this paper that considers the end coil effect. This method predicts not
only the natural frequency of a helical spring at a fixed number of active turns, but also the change in the natural frequency
as the spring is compressed. The experimental results demonstrate that nonlinear characteristics of engine valve springs can
be predicted from the given initial pitch curves. 相似文献
353.
B. K. Han M. K. Cho C. Kim C. H. Lim J. J. Kim 《International Journal of Automotive Technology》2009,10(4):469-474
An efficient multibody dynamic model was developed to predict the vibrating transmitted gear forces of loaded and unloaded
pairs of helical gears simultaneously at all speeds. The model can also calculate the bearing forces of a manual transmission
that, in turn, may be converted to rattling noises. The bending of meshing gear teeth and torsional flexibility of transmission
shafts were considered and embodied effectively in the multibody dynamic model by calculating the tooth bending stiffness
and adding a torsion spring on a shaft section between two gears, respectively. The reactive forces on teeth and bearings
were calculated and compared using three different models that were developed for this study — an equivalent model, a rigid-body
model, and a frequency-based model. The equivalent model took only 58% computation time, compared to the frequency-based method,
even though the two showed very similar results. 相似文献
354.
T. J. Kim H. Y. Kim B. C. Hwang H. J. Kang C. Kim 《International Journal of Automotive Technology》2009,10(5):611-618
There are three sub-processes associated with the assembly of an automobile transmission: heat fitting, shrink fitting, and
combination fitting. In the heat fitting stage, the gear is heated to a specified temperature and then squeezed towards the
outer diameter of the shaft. The stress of the heat-fitted gear depends on the yield strength of the gear. In the shrink fitting
process, the gear is typically squeezed towards the shaft at room temperature using a press. An alternate method, known as
warm shrink fitting, heats the already warm gear and safely squeezes it toward the shaft. The warm shrink fitting process
for automobile transmission parts is becoming more commonplace, but the additional heating can cause the dimensions of the
assembled parts (shaft/gear) to change with respect to both the outer diameter and the profile of the gear. As a result, there
may be additional noise and vibration between gears. To address these problems, we analyzed the warm shrink fitting process
using the contact pressure caused by fitting interference between the outer diameter of the shaft and the inner diameter of
the gear, fitting temperature, and the profile tolerance of the gear as design parameters. In this study, a closed form equation
for predicting the contact pressure and fitting load is proposed. This equation is used to develop an optimization technique
for the warm shrink fitting process. The reliability of the model was verified using experimental results measured in the
field, and FEM with thermal-structural coupled field analysis. Actual loads measured in the field showed good agreement with
the results obtained by theoretical and finite element analysis, and expansion of the outer diameters of the gears agreed
well with the results. 相似文献
355.
J. Kim N. Kim S. Hwang Y. Hori H. Kim 《International Journal of Automotive Technology》2009,10(6):733-742
A motor control strategy for an input-split hybrid electric vehicle (HEV) is proposed. From a power characteristic analysis,
it is found that the powertrain efficiency decreases for speed ratios at which power circulation occurs. Using dynamic models
of an input-split HEV powertrain, a motor-generator control algorithm for obtaining high system efficiency is designed by
inversion-based control. The performance of the control algorithm is evaluated by the simulator which is developed based on
PSAT, and simulation results are compared with the test results. It is found that, even if the engine thermal efficiency is
sacrificed by moving the engine operation point from the OOL for the control strategy, improved overall powertrain system
efficiency can be achieved by the engine operation that gives a relatively high efficiency from the viewpoint of the overall
powertrain efficiency. The control algorithm developed can be used in design of future electric vehicles. 相似文献
356.
H. G. Jung Y. H. Lee H. J. Kang J. Kim 《International Journal of Automotive Technology》2009,10(2):219-228
This paper discusses the market trends and advantages of a safety system integrating LKS (Lane Keeping System) and ACC (Adaptive
Cruise Control), referred to as the LKS+ACC system, and proposes a method utilizing the range data from ACC for the sake of
lane detection. The overall structure of lane detection is the same as the conventional method using monocular vision: EDF
(Edge Distribution Function)-based initialization, sub-ROI (Region Of Interest) for left/right and distance-based layers,
steerable filter-based feature extraction, and model fitting in each sub-ROI. The proposed method adds only the system for
confining lane detection ROI to free space that is established by range data. Experimental results indicate that such a simple
adaptive ROI can overcome occlusion of lane markings and disturbance of neighboring vehicles. 相似文献
357.
S. Y. Kim H. C. Choi W. J. Won S. Y. Oh 《International Journal of Automotive Technology》2009,10(1):103-113
Because the overall driving environment consists of a complex combination of the traffic Environment, Vehicle, and Driver
(EVD), Advanced Driver Assistance Systems (ADAS) must consider not only events from each component of the EVD but also the
interactions between them. Although previous researchers focused on the fusion of the states from the EVD (EVD states), they
estimated and fused the simple EVD states for a single function system such as the lane change intent analysis. To overcome
the current limitations, first, this paper defines the EVD states as driver’s gazing region, time to lane crossing, and time
to collision. These states are estimated by enhanced detection and tracking methods from in- and out-of-vehicle vision systems.
Second, it proposes a long-term prediction method of the EVD states using a time delayed neural network to fuse these states
and a fuzzy inference system to assess the driving situation. When tested with real driving data, our system reduced false
environment assessments and provided accurate lane departure, vehicle collision, and visual inattention warning signals. 相似文献
358.
Hwa-Joong KimYoung-Tae Chang Kwang-Tae KimHyo-Jeong Kim 《Transportation Research Part D: Transport and Environment》2012,17(2):97-103
This paper provides an algorithm to minimize the fixed ordering, purchase, and inventory-carrying costs associated with bunker fuel together with ship time costs; and environmental costs associated with greenhouse gas emissions. It determines the optimum ship speed, bunkering ports, and amounts of bunker fuel for a given ship’s route. To solve the problem, we use an epsilon-optimal algorithm by deriving a property. The algorithm is illustrated by applying it to typical sample data obtained and the effects of bunker prices, carbon taxes, and ship time costs on the ship speed are analyzed. The results indicate that the ship speed and CO2 emissions are highly sensitive to the factors considered. 相似文献
359.
This paper studies the springing response of a flexible floating barge under an oblique wave. A time domain Rankine panel
method was used to represent fluid motion surrounding a flexible seagoing vessel, and a finite element method was used for
structural response. For accurate prediction of the structural response under an oblique wave, special attention was given
to the structural model, such as the effect of warping distortion and bending-torsion coupling. The Vlasov assumption was
followed for a deformable beam element to take into account the effect of warping distortion so that the cross section of
the beam deforms out of its original plane without changing its cross-section contour. The coupled equation for both the fluid
and structural domain was solved by using the implicit iterative method. A fixed point iteration with a relaxation scheme
was employed in this study with the aid of the Aitken δ2 process seeking acceleration of solution convergence. Accuracy of a developed computer program was verified through the comparison
with experimental work done by Remy et al. (Experimental and numerical study of the wave response of a flexible barge, Hydroelasticity in Marine Technology, Wuxi, 2006) resulting in good correspondence between the two results. 相似文献
360.
Computational predictions of ship-speed performance 总被引:1,自引:0,他引:1
Jung-Eun Choi Jung-Hun Kim Hong-Gi Lee Bong-Jun Choi Dong-Hyun Lee 《Journal of Marine Science and Technology》2009,14(3):322-333
This paper examines ship-speed performance based on acomputational method. The computations are carried out under identical
model conditions, i.e., resistance and self-propulsion tests, to predict the speed-power relationship. The self-propulsion
point is obtained from the self-propulsive computational results of two propeller rotative speeds. The speed-power relationship
in full scale is obtained through analyzing the computational results in model scale according to the model-ship performance
analysis method of ITTC’78. The object ship is a VLCC. The limiting streamlines and the distribution of the pressure coefficient
on the hull, the wake characteristics on the propeller plane, and the wave characteristics around a model ship are also investigated.
After completing the computations, a series of model tests are conducted to evaluate the accuracy of the predictions by comparing
the computational results with the experimental results. 相似文献