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501.
Keon Hee Baek Su Bin Choi Hee Rok Hong Nak Tak Jeong Hyeong Uk Moon Eun Seong Lee Hyung Min Kim Sung Uk Choi Myung Won Suh 《International Journal of Automotive Technology》2018,19(5):859-868
Ever since vehicle noise, vibration, and harshness (NVH) reduction technology made dramatic improvements, vehicle interior noises represented by Squeak and Rattle (S/R) becomes an ever more important factor to improve the emotional quality of vehicles. Generally, people detect S/R noises on automotive interior parts, brake system, suspension, Body in White (BIW), etc. Among them, the rear-glass joint is a major source for vehicle interior noise, and can cause S/R noises under a variety of environmental and driving conditions. This study uses, two approaches, experimental and numerical approaches, to define the cause of S/R noise at the rear-glass section. Based on these two approaches, this study confirms that S/R noises generate through the contact between bottom side of molding and BIW. The sealant penetration length, panelmolding distance, and sealant width are the parameters affecting noise generation. In addition, this study created an optimal design with Design of Experiments (DOE) of the rear-glass joint. The design maximized the sealant penetration length, which is a parameter that majorly affects noise. The optimal design comprises of two steps: sealant injections shape optimization and rear-glass joint parameter optimization. Each step is carried out with FEA and validated by sealant penetration experiments. Through these optimizations, this study obtained an optimum combination of design parameters and fignificantly reduced the noise generated by rear-glass section. 相似文献
502.
Dongmei Wu Haitao Ding Changqing Du 《International Journal of Automotive Technology》2018,19(1):135-146
Compared with internal combustion engine (ICE) vehicles, four-wheel-independently-drive electric vehicles (FWID EV) have significant advantages, such as more controlled degree of freedom (DOF), higher energy efficiency and faster torque response of an electric motor. The influence of these advantages and other characteristics on vehicle dynamics control need to be evaluated in detail. This paper firstly analyzed the dynamics characteristics of FWID EV, including the feasible region of vehicle global force, the improvement of powertrain energy efficiency and the time-delays of electric motor torque in the direct yaw moment feedback control system. In this way, the influence of electric motor output power limit, road friction coefficient and the wheel torque response on the stability control, as well as the impact of motor idle loss on the torque distribution method were illustrated clearly. Then a vehicle dynamics control method based on the vehicle stability state was proposed. In normal driving condition, the powertrain energy efficiency can be improved by torque distribution between front and rear wheels. In extreme driving condition, the electric motors combined with the electro-hydraulic braking system were employed as actuators for direct yaw moment control. Simulation results show that dynamics control which take full advantages of the more controlled freedom and the motor torque response characteristics improve the vehicle stability better than the control based on the hydraulic braking system of conventional vehicle. Furthermore, some road tests in a real vehicle were conducted to evaluate the performance of proposed control method. 相似文献
503.
Both sea battles and testing of ship in underwater explosions reveal unacceptably poor anti-shock performance of important shipboard equipment. Anti-shock performance of shipboard equipment is a significant factor determining fighting strength and survivability. The anti-shock performance of a shipboard gear case based on BV043/85 was investigated using numerical simulation. A geometric model of the gear case was built using MDT software and meshed in HyperMesh software, and then the finite element model of the gear case was formed. Using ABAQUS software, the anti-shock performance of the gear case was simulated. First, shock response of typical regions of gear case was determined. Next, some generalizations were made about the anti-shock performance of the gear case by analyzing the Mises stress of typical regions varied with shock inputs. Third, weak regions were determined from simulation results. The threshold values of shock resistance of the gear case at different impulse widths were obtained through interpolating the numerical simulation results selected from the most dangerous spot. This research provides a basis for further optimization of the design of gear cases. 相似文献
504.
Traffic forecasting provides the estimation of future traffic state to help traffic control,travel guide,etc. This paper compared several widely used traffic forecasting methods,and analyzed each one's performance in detail to make conclusions,which could redound to researchers choosing an appropriate traffic forecasting method in their own works. Compared with conventional works,this paper creatively assessed the performance of traffic forecasting methods based on travel time index (TTI) data prediction,wh... 相似文献
505.
A reconfigurable flexible poles die was developed. The die can be used to implement the process of “the multi-point pressing
and forming sheet”. Sheet metal is restricted by the elastic pressing forces putting on the upper and lower surfaces of sheet
in stamping process. The method is an effective way to enhance the buckling critical stresses and reduce wrinkling of sheet.
The results of tests indicate that the die can achieve “one die brings multi-purpose” and suppress the wrinkle of sheet. The
process of the multi-point pressing and forming sheet provides a practical and effective way for the curved sheet metal forming. 相似文献
506.
应用广义相关时间延迟估计方法,经由诱发电位潜伏期变化的测定,分析研究了撞击加速度和缺窒息实验条件下中枢时间系统的损伤问题。计算机模拟和诱发电位信号分析表明,当神经系统发生损伤时,诱发电位的潜伏期会出现显的变化,这种化可以由广义相关时间延迟估计方法而有效测定。 相似文献
507.
This study focuses on the user-interface of the route guidance system with an electronic map display. The ultimate goal of
the study is to aid in designing electronic map displays that can deliver information to the user most efficiently and expeditiously
with minimum confusion. To evaluate the efficiency and understandability of a map display, laboratory experiments were designed
and conducted in this study. In the experiments the subjects were presented with electronic map displays of different attributes
and performed a set of tasks. Their understanding of the information contents was measured based on the outcomes of the tasks,
and subjective ratings of the ease of using the maps were obtained. Using the experimental data obtained, a structural equations
model system is developed to explain the understandability of a map display in terms of the subject’s attributes and the characteristics
of the map display. The experimental procedure and the modeling results are presented in this paper. 相似文献
508.
Naoya Umeda Hirotada Hashimoto Shohei Minegaki Akihiko Matsuda 《Journal of Marine Science and Technology》2008,13(1):16-23
The parametric rolling of modern containerships is emerging as a serious problem, to the extent that its effects warrant a
study into its prevention. In light of this, two methods for reduction of parametric rolling are proposed and examined by
physical model experiments. The first is a sponson attached to the side of a ship, the purpose being to decrease the rate
of change of the rollrestoring moment. The second is an antirolling tank to increase roll damping. By conducting free-running
model experiments for a 6600-TEU post-Panamax container ship with sponsons under typical parametric rolling conditions, it
was found that the sponsons could decrease the magnitude of parametric rolling. The antirolling tank could prevent parametric
rolling completely in certain conditions, even in severe head seas. Using the damping coefficients from experimentally derived
data of a model ship with an antiroll tank, a numerical simulation was established. The numerical model was then compared
with the free-running model experiments. The results indicated that the numerical model could qualitatively verify the experimental
results. Finally, an attempt to optimise the size of an antirolling tank for preventing parametric rolling for the subject
post-Panamax container ship in the North Pacific Ocean is presented. 相似文献
509.
Yusuke Tahara Daniele Peri Emilio Fortunato Campana Frederick Stern 《Journal of Marine Science and Technology》2008,13(2):95-116
The main objective of this article is to describe the development of two advanced multiobjective optimization methods based
on derivative-free techniques and complex computational fluid dynamics (CFD) analysis. Alternatives for the geometry and mesh
manipulation techniques are also described. Emphasis is on advanced strategies for the use of computer resource-intensive
CFD solvers in the optimization process: indeed, two up-to-date free surface-fitting Reynolds-averaged Navier-Stokes equation
solvers are used as analysis tools for the evaluation of the objective function and functional constraints. The two optimization
methods are realized and demonstrated on a real design problem: the optimization of the entire hull form of a surface combatant,
the David Taylor Model Basin—Model 5415. Realistic functional and geometrical constraints for preventing unfeasible results
and to get a final meaningful design are enforced and discussed. Finally, a recently proposed verification and validation
methodology is applied to assess uncertainties and errors in simulation-based optimization, based on the differences between
the numerically predicted improvement of the objective function and the actual improvement measured in a dedicated experimental
campaign. The optimized model demonstrates improved characteristics beyond the numerical and experimental uncertainty, confirming
the validity of the simulation-based design frameworks. 相似文献
510.
网络信息技术的迅速发展,对图书馆情报工作提出了新的变革要求.本文分析了网络环境下图书馆情报工作面临的新情况和新问题,对图书馆情报工作的改革必要性以及大体的变革方向进行了分析. 相似文献