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121.
今年是我国伟大的航海家郑和下西洋600周年.郑和下西洋这一世界航海史上的伟大壮举,是中华民族优秀的文化遗产和宝贵的精神财富.长期以来,在郑和航海和郑和宝船的学术研究方面存有不同的声音.只有认识历史真相,才能古为今用.为了求得真知和丰富学术内涵,作者针对郑和航海和郑和宝船研究发表一些个人见解,以同业界商讨. 相似文献
122.
桥梁基桩屈曲机理及其分析方法 总被引:2,自引:0,他引:2
讨论了基桩屈曲分析的现有方法,进而在分析基桩屈曲机理的基础上,将桩身视为考虑几何非线性的空间梁单元,利用更新的拉格朗日坐标体系建立有限元方程,并采用弧长控制法求解有限元非线性方程组,对基桩屈曲的几何非线性有限元分析进行了探讨。利用Matlab语言编制了相应的计算程序,以现场木桩压屈试验作为计算实例进行比较,计算表明,程序的计算结果吻合较好,可用于基桩屈曲的几何非线性分析。此外计算表明,地基系数对屈曲荷载的影响明显,随着地基系数的增大,基桩的屈曲荷载也随之增大。 相似文献
123.
通过对安全气囊结构的了解,针对其在实际使用中存在的问题,提出关于安全气囊改进措施,使得安全气囊得以充分发挥安全保护性能,在实际应用中得到广泛推广。 相似文献
124.
J. M. Pi Y. S. Bak Y. K. You D. H. Park H. S. Kim 《International Journal of Automotive Technology》2016,17(6):1101-1111
A route information based driving control algorithm was developed for an RE-EV which consists of two motorgenerators, MG1 and MG2. A threshold power which controls the engine on/off to charge the battery was obtained by an optimization process using route information, such as the vehicle velocity and altitude. The threshold power allows the vehicle to travel to the final destination while making the final battery SOC close to SOC low. Using the threshold power, route based control (RBC) was proposed by considering the driver’s characteristics and traffic conditions using the driving data base. In addition, a relationship between the threshold power and various initial battery SOC was obtained by off-line optimization. The performance of the RBC was evaluated by simulation and human-in-the-loop simulation (HILS) for city driving. It was found from the simulation and HILS results that the RBC achieved approximately 4 % to 12 % reduction in fuel consumption compared to the existing charge depleting/charge sustaining (CD/CS) driving control. 相似文献
125.
为了深入的分析同步发电机调压系统,本文建立了带H∞状态反馈控制器的交流无刷励磁同步发电机调压系统的数学模型,通过这个模型对调压系统的动态特性进行了研究.应用鲁棒H∞控制理论和MATLAB的μ综合工具箱完成权函数的优化,直接解决鲁棒控制设计问题.并利用MATLAB软件进行了突加、突减静负荷以及起动大功率异步电动机的仿真分析.仿真结果表明建立的数学模型是正确的. 相似文献
126.
This study develops a new performance evaluation model, called the meta dynamic network slack‐based measure (MDN‐SBM). This model incorporates the concept of meta‐frontiers to facilitate comparisons of performance of decision making units, while at the same time it generalizes the slack‐based measure (SBM), network SBM, and dynamic SBM. This MDN‐SBM model is capable of dealing with two important special features of the transportation industry: unfavorable accidents and non‐storable goods, i.e. available seat‐kilometers that are wasting assets that lose value completely if unsold before departure. Hence, this generalized model contains higher differentiable capability than all its SBM‐related submodels in the literature. To demonstrate, 35 international airlines with two divisions (production and consumption) in three terms (one‐year time periods from 2007 to 2009) have been analyzed using meta‐performance efficiency measures (ME) for all decision making units and have also been compared by geographical area (Asia‐Pacific, N. America/Europe). The numerical example and comparison validate the proposed MDN‐SBM model and suggest the airlines should put more focus on input resources reduction for productivity improvement. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
127.
J. -S. Jo S. -H. You J. Y. Joeng K. I. Lee K. Yi 《International Journal of Automotive Technology》2008,9(5):571-576
The Vehicle stability control system is an active safety system designed to prevent accidents from occurring and to stabilize
dynamic maneuvers of a vehicle by generating an artificial yaw moment using differential brakes. In this paper, in order to
enhance vehicle steerability, lateral stability, and roll stability, each reference yaw rate is designed and combined into
a target yaw rate depending on the driving situation. A yaw rate controller is designed to track the target yaw rate based
on sliding mode control theory. To generate the total yaw moment required from the proposed yaw rate controller, each brake
pressure is properly distributed with effective control wheel decision. Estimators are developed to identify the roll angle
and body sideslip angle of a vehicle based on the simplified roll dynamics model and parameter adaptation approach. The performance
of the proposed vehicle stability control system and estimation algorithms is verified with simulation results and experimental
results. 相似文献
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应用无网格局部Petrov-Galerkin法对船舶平直板结构进行了研究。运用最小二乘法和加权余量法来求解结构位移场量的逼近函数,给出了问题的控制方程和刚度方程。通过算例与有限元法计算结果进行了比较分析,验证了文章提出方法的正确性。文章研究对于分析船舶结构变形和应力具有良好的适用性。 相似文献