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381.
环境,是人们生存和发展的外部条件,人在社会中不能孤立存在,而要受到环境潜移默化的影响。大学生处于性格成长的重要阶段,对外界环境充满兴趣又极为敏感。高校教育者可以利用环境对大学生的作用激发他们在思维方式、行为方式方面的良好意识,培养出大学生积极的情感取向、性格特点、价值观念和生活态度,引导他们成长成才。 相似文献
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383.
闫吉 《西安航空技术高等专科学校学报》2009,27(4)
"流行书风"的形成与当时书法艺术家主体的完全独立、书法理论界的思想解放、创作主体对创作的个性化与原创性追求,以及以国家级的展览为代表的展厅文化的推波助澜息惠相关.只要其"根植传统、张扬个性"的宗旨不变,在当前乃至今后一个较长的时期,它将一如既往地继续"流行". 相似文献
384.
The application of computational fluid dynamics/computational solid method (CFD/CSM) on solving the aero-thermo-elastic problem of spinning rocket is introduced. Firstly, the aerodynamic coefficients of a rocket are calculated, and the results are compared with the available experimental data, which verified the accuracy of the CFD output. Then, analysis is carried using ANSYS Workbench multi-physics coupling platform, which includes fluid, thermal, and structural solvers. The results show that spinning causes a significant effect on the de formations and stresses. Furthermore, thermal stresses due to high temperature at the rocket warhead and tail edges have a dominated effect, even more than those produced by aerodynamic forces. Consequently, this important outcome should be taken into consideration during the rocket design stages. 相似文献
385.
The main purpose of the paper is to obtain the experimental yield loci of TRIP590 advanced high strength steel,and to compare it with the theoretical loci in order to obtain the best yield criterion for this material. First,the biaxial loading tests under different loading paths in the method of load control are carried out. Then,the experimental yield loci of different deformation stages are obtained. Finally,the experimental yield loci are compared with the theoretical loci of Mises criterion and Hill48 criterion,the parameters of which are calculated based on the r-value and the yield stress method,respectively. The results show that the accuracy of the theoretical yield loci of Hill48 based on the yield stress is higher than that of Mises criterion and Hill 48 criterion based on r-value method. 相似文献
386.
387.
Robotic belt grinding has emerged as a finishing process in recent years for machining components with high surface finish and flexibility.The surface machining consistency, however,is difficult to be guaranteed in such a process.To overcome this problem, a method of hybrid force-position control combined with PI/PD control is proposed to be applied in robotic abrasive belt grinding of complex geometries.Voltage signals are firstly obtained and transformed to force information with signal conditioning methods.Secondly, zero drift and gravity compensation algorithms are presented to calibrate the F/T transducer which is installed on the robot end-effector.Next, a force control strategy combining hybrid force-position control with PI/PD control is introduced to be employed in robotic abrasive belt grinding operations where the force control law is applied to the Z direction of the tool frame and the positon control law is used in the X direction of the tool frame.Then, the accuracy of the F/T transducer and the robotic force control system is analyzed to ensure the stability and reliability of force control in the robotic grinding process.Finally, two typical cases on robotic belt grinding of a test workpiece and an aero-engine blade are conducted to validate the practicality and effectiveness of the force control technology proposed. 相似文献
388.
信息产业在过去的二十年里发生了巨大的变化,新一代软件技术服务和面向服务的软件体系结构(SOA)随之而生以应对变化性和复杂性与日俱增的业务需求。本文以继承的观点对服务进行分析,对服务的元素、属性以及它们之间关系给出了合理的解释,并根据不同的目标将服务属性分成了两组,并在每组中分别解释了服务如何在封装的基础上实现复用目标,以及如何基于统一描述实现交互目标的。此外,本文还给出新的服务和SOA概念,分析了它们的属性。同时还详细地讨论了SOA及其相关技术(分布式系统和服务),以及SOA系统如何通过服务实现分布式目标。 相似文献
389.
在计算流体力学(CFD)方法中,限制技术是影响计算精度和计算稳定性的重要因素,目前应用较广的经典二阶总变差衰减(TVD)限制器虽能较好地满足计算要求,但性能差异大且分辨率和耗散的性能间并未得到良好权衡。对一种新型的三阶TVD插值限制器(T-3限制器)进行了研究并将其与3种经典限制器进行对比。首先通过一维黎曼问题,得出T-3限制器兼顾较高间断分辨率和良好稳定性的特点;接着通过高超声速双锥绕流和X-33外形飞行器的数值实验,得到T-3限制器具有刻画复杂流动的能力以及较优的气动热计算性能。 相似文献