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521.
Structural optimization of a circumferential friction disk brake with consideration of thermoelastic instability 总被引:1,自引:0,他引:1
This research suggests a new disk brake design using circumferential friction on the disk of a front-wheel-drive passenger
car. The paper compares mechanical performance between the conventional and suggested disk brakes under dynamic braking conditions.
Thermoelastic instability is considered in simulation of the test condition. An optimization technique using a metamodel is
introduced to minimize the weight of the suggested disk brake. To achieve this goal, the response defined in the optimization
formulation is expressed in a mathematically explicit form with respect to the design variables by using a kriging surrogate
model, resulting in a simple optimization problem. Then, the simulated annealing algorithm is utilized to find the global
optimum. The design results obtained by the kriging method are compared with those obtained from ANSYS analysis. 相似文献
522.
Research on the electro-hydraulic variable valve actuation system based on a three-way proportional reducing valve 总被引:1,自引:0,他引:1
J. -R. Liu B. Jin Y. -J. Xie Y. Chen Z. -T. Weng 《International Journal of Automotive Technology》2009,10(1):27-36
As the internal combustion engine moves into the 21st century, fully flexible valve actuation systems are being proposed as
an enabling technology for advanced internal combustion engine concepts. Electro-hydraulic valve actuator systems are being
considered as a potential variable valve technology. Compared to the servo control system, the system using a proportional
valve has the advantages of low price, high anti-pollution ability and high reliability. Our research focuses on exploring
the dynamic characteristic of the electro-hydraulic variable valve system, which is based on three-way proportional reducing
valve. In this paper, the structure and working principles of the system are described. The dynamic mathematical model of
the system is derived. From the analysis of a linearized model and dynamic simulation, it is demonstrated that the system
will be stable only if the proportional reducing valve has a positive opening. Some structural factors that affect the system’s
dynamic characteristics, such as input signal, the stiffness of the return spring and the pre-tightening force of the return
spring, are studied using AMESim. The experimental results coincide with the theoretical and simulated analyses. Further study
shows that the dynamic response can be improved effectively by adopting closed-loop control of valve lift. 相似文献
523.
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
524.
计量模型在“十五”四川省 交通运输量预测中的应用 总被引:2,自引:0,他引:2
在阐述科学预测交通运输量的意义的基础上,利用计量经济模型对四川省的“十五”交通运输量进行了预测,并给出了一般性的模型检验流程. 相似文献
525.
526.
Various water wave problems involving an infinitely long horizontal cylinder floating on the surface water were investigated
in the literature of linearized theory of water waves employing a general multipole expansion for the wave potential. This
expansion involves a general combination of a regular wave, a wave source, a wave dipole and a regular wave-free part. The
wave-free part can be further expanded in terms of wave-free multipoles which are termed as wave-free potentials. These are
singular solutions of Laplace’s equation (for non-oblique waves in two dimensions) or two-dimensional Helmholz equation (for
oblique waves) satisfying the free surface condition and decaying rapidly away from the point of singularity. The method of
constructing these wave-free potentials is presented here in a systematic manner for a number of situations such as deep water
with a free surface, neglecting or taking into account the effect of surface tension, or with an ice-cover modelled as a thin
elastic plate floating on water. 相似文献
527.
Transportation - Although complete street policies are proliferating, little is known about how nearby residents perceive and act on their new active transportation opportunities. We survey the... 相似文献
528.
杨兵赵建森王胜正谢宗轩张学生 《中国舰船研究》2022,(6):209-215
[目的]为了解决水面无人艇(USV)路径规划中安全性和平滑性方面的问题,提出一种与障碍物距离可控的USV路径规划方法。[方法]首先,结合雷达图像生成栅格化环境信息,利用维诺场算法(VFA)为每个栅格添加危险势场并建立航行界限;其次,建立与航行界限关联的危险度函数对A^(*)算法的评价函数进行改进,利用改进的A^(*)算法进行路径规划;最后,针对航行路径转向角较大的问题,采用梯度下降法(GDM)进行航行路径的平滑处理,得到满足USV实际航行要求的连续平滑路径。[结果]仿真结果表明,所提路径规划方法通过设置不同的航行界限可以实现路径与障碍物之间距离的控制且平滑性符合航行要求。[结论]该方法在USV路径规划过程中具有一定的合理性和有效性,可为USV自主避障决策提供参考。 相似文献
529.
Cui Yu Makhija Ramandeep Singh Manjeet Singh Chen Roger B. He Qing Khani Alireza 《Transportation》2021,48(4):1809-1835
Transportation - Ridesharing is the sharing of trip segments from one place to another among multiple travelers, obviating others’ needs to drive themselves. By having more than one occupant... 相似文献
530.
M. H. Lee K. S. Lee H. G. Park Y. C. Cha D. J. Kim B. Kim S. Hong H. H. Chun 《International Journal of Automotive Technology》2012,13(5):801-807
This paper proposes a lateral control system for an unmanned vehicle that is designed to improve the responsiveness of the system with the use of a PD control. The vehicle heading error can be stabilized, and the transient response characteristics can be improved using the proposed controller. A mathematical model of the vehicle dynamics using two degrees of freedom was developed for the controller design. The waypoint tracking method for autonomous navigation was tested with incorporation of the Point-to-Point algorithm with position and heading measurements received from GPS receivers via Kalman filtering. The performance of the designed controller was verified through experiments with a real vehicle. 相似文献