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951.
Until recently, passenger cars have primarily interested in pedestrian protection performance. Nowadays, however, it is important
for a sport-utility vehicle (SUV) to meet the bumper system standards for pedestrian safety. For a SUV bumper system, there
are some difficulties in attaining a high level of pedestrian performance for the lower legform. An SUV has a high bumper
position from the ground level, and the bumper approach angle must also be secured, which has an effect on car insurance fees.
Due to these reasons, it is difficult to meet the pedestrian performance of the lower legform for an SUV. In this paper, a
comparative study was performed on various SUV bumper systems, and a concept model for a SUV bumper system was developed,
which is expected to meet the pedestrian performance by using the Pugh method. The design control factors were defined to
affect the bumper pedestrian performance through the experiences of tests and analyses. For the noise factor to affect the
pedestrian performance, the deviation of the impactor position was selected at the moment of impact. The design control factors
were optimized by using the Taguchi optimization technique. For the Taguchi method, an L18 orthogonal array table of design
control factors was used in the optimization process. Particularly, for the optimization of the bumper corner region, an optimization
analysis was performed three times to meet pedestrian performance. Based on the results of the Taguchi optimization method,
the sensitivity of the bumper design parameters was studied, and a new SUV bumper system is proposed that satisfies the pedestrian
performance of the lower legform. The optimized bumper system should obtain a full Euro-NCAP score of 6 points for the bumper
test. The pedestrian performance of the optimized bumper system is validated by using a CAE (Computer Aided Engineering) analysis,
which has been proven to be in accurate. A comparison between the test and analysis results is shown for the validation of
accuracy. By using the optimized bumper system, the tests and development costs of a bumper can be reduced. 相似文献
952.
Modeling of network traffic is a fundamental building block of computer science. Measurements of network traffic demonstrate that self-similarity is one of the basic properties of the network traffic possess at large time-scale. This paper investigates the change of non-stationary self-similarity of network traffic over time,and proposes a method of combining the discrete wavelet transform (DWT) and Schwarz information criterion (SIC) to detect change points of self-similarity in network traffic. The traffi... 相似文献
953.
In H.264,the computational complexity and memory access of deblocking filter are variable and depend on the video contents. In this paper,a pipelined VLSI architecture of deblocking filter with adaptive dynamic power is proposed. It avoids redundant computations and memory access by precluding the blocks which can be skipped. And the vertical and horizontal edges are simultaneously processed in an advanced scan order to speed up the decoder. As a result,the dynamic power of the proposed architecture can be ... 相似文献
954.
It is still controversial whether or not to resurface patella during primary total knee arthroplasty (TKA). One of the reasons
may be insensitive measurement tools. We conducted a randomized controlled study to compare kinematic and kinetic parameters
of resurfacing and nonresurfacing patella with the Vicon gait analysis system. The results show that patient post-operative
gait of the two groups improved compared to pre-operative gait. Part of gait parameters, knee flexion at heel-strike, double
limb support time and maximum adduction angle appeared to be statistically difference in 3 months, but 12 months later, the
gait parameters of the two groups had no significant difference. Therefore, it seems that the final function of knee after
TKA is not related whether or not to resurface patella. 相似文献
955.
The static softening behavior of aluminum alloy A6082 was investigated by interrupted hot tests conducted on Gleeble-1500
simulator at deformation temperatures from 573 to 773 K and strain rates from 0.1 to 10 s−1, with a pre-strain from 0.3 to 0.7 and variable inter-pass delay times. The offset method was applied to convert the changes
in flow stress between two passes to static softening fraction. The microstructural changes were characterized by the quantitative
metallography of quenched specimens. The results showed both static softening and static recrystallization curves exhibited
a simple sigmoidal shape; the static softening is related to the static recrystallization in a nonlinear manner with 50% static
recrystallized volume fraction corresponding to 80% static softening fraction; an increase in temperature, strain rate or
pre-strain yields a decrease in the time for 50% static recrysallized volume fraction, on which the temperature has the most
remarkable influence; Si and Mn additions accelerate the process of static recrystallization. Finally, the equations of static
recrystallization kinetics of this alloy were developed with a good agreement between the predicted and experimental results. 相似文献
956.
A four-degree-of-freedom mathematical model was established to investigate the course stability of an air cushion vehicle (ACV). The forces of aerodynamic,propeller and rudder were obtained by wind tunnel experiments. A series of constrained model experiments with horizontal-planar-motion-mechanism (HPMM) were conducted to determine the hydrodynamics. The ACV's course stability was analyzed by using Hurwitz deter-mination method with differential equation of perturbation,and the four-degree-of-freedom cours... 相似文献
957.
It is very difficult,for the component-type ship mathematical model,to estimate the interaction force coefficients among the hull,propeller and rudder. Some coefficients such as wake fraction and flow straightening coefficient were studied from the model tests in diffierent loading conditions and the normal force of rudder was tested in captive model tests to obtain the coefficients. From these results of the tests,the flow straightening coefficients increase with the increase of trims or drafts. Similarly,... 相似文献
958.
This paper presents a new improved collaborative optimization (CO) model that provides solution capabilities for multiobjective multidisciplinary optimization problems. Reasons that cause computational difficulties in CO algorithm are firstly analyzed. Then a new system level objective function is advised to minimize relative value between the collaborative objective function and single disciplinary objective function. And it eliminates the effect of dimensions and magnitude orders among objectives. A new s... 相似文献
959.
AbstractTo study an entity the entire jack-up performs as a total system with close interdependency and high level of integration of a myriad of subsystems supporting each individual function.All subsystems should be arranged in regular geometric space with clear regional division according to their respective functions.The "building block"such as arrangement makes it feasible to apply modular design method while the integration and conflicts among subsystems offer an arena for game theoretic analysis.All the contradictions between subsystems should be resolved bye the designer.Here we present a game theoretic analysis methodology,which based on the basic principles of game theory,through the establishment of matrix-mode game models to describe and analyze engineering design tasks.By using this method the optimization process in various fields of expertise can be effectively coordinated and controlled,and the parallel design patterns can be achieved to some extent.Taking account of the impact of commercial or technical activities in platform’s life cycle,time line is considered in the early stage of design process which provides more convenience for effcient upgrade and reconfiguration.Some second-hand three-legged jack-up upgrade design process is used as an example to illustrate the utility of the method. 相似文献
960.
Grinding is known as the most complicated material removal process and the method for monitoring the grinding wheel wear has
its own characteristics comparing with the approaches for detecting the wear on regular cutting tools. Research efforts were
made to develop the wheel wear monitoring system due to its significance in grinding process. This paper presents a novel
method for identification of grinding wheel wear signature by combination of wavelet packet decomposition (WPD) based energies.
The distinctive feature of the method is that it takes advantage of the combinational information of the decomposed frequency
components based on the WPD so the extracted features can be customized according to the specific monitored object to get
better diagnosis effects. Experiments are researched on monitoring of grinding wheel wear states under different machining
conditions. The results show that the energy ratio extracted from the measured vibration signals is consistent with the grinding
wheel wear condition evaluated by experiment and the further extracted feature ratio can be used in prediction of wheel wear
condition. 相似文献