Dual-steering mode based on direct yaw moment control for multi-wheel hub motor driven vehicles:Theoretical design and experimental assessment

One of the main challenges for multi-wheel hub motor driven vehicles is the coordination of individual drivetrains to improve mobility and stability in the steering process.This paper proposes a dual-steering mode based on direct yaw moment control for enhancing vehicle steering ability in complex environ-ments.The control system is designed as a hierarchical structure,with a yaw moment decision layer and a driving force distribution layer.In the higher-level layer,the objective optimization function is con-structed to obtain the slip steering ratio,which represents the degree of vehicle slip steering in the dual-steering mode.A yaw moment controller using active disturbance rejection control theory is designed for continuous yaw rate control.When the actual yaw rate of the vehicle deviates from the reference yaw rate obtained by the vehicle reference model and the slip steering ratio,the yaw moment controller is actuated to determine the yaw moment demand for vehicle steering.In the lower-level layer,there is a torque distribution controller based on distribution rules,which meets the requirement of yaw moment demand without affecting the total longitudinal driving force of the vehicle.For verifying the validity and feasibility of the dual-steering mode,simulations were conducted on the hardware-in-loop real-time simulation platform.Additionally,corresponding real vehicle tests were carried out on an eight-wheel prototype vehicle.Test results were generally consistent with the simulation results,thereby demon-strating that the proposed dual-steering mode reduces steering radius and enhances the steering per-formance of the vehicle.     

Numerical investigation of the failure mechanism of cubic concrete specimens in SHPB tests

Cylindrical specimens are commonly used in Split Hopkinson pressure bar (SHPB) tests to study the uniaxial dynamic properties of concrete-like materials.In recent years,true tri-axial SHPB equipment has also been developed or is under development to investigate the material dynamic properties under tri-axial impact loads.For such tests,cubic specimens are needed.It is well understood that static material strength obtained from cylinder and cube specimens are different.Conversion factors are obtained and adopted in some guidelines to convert the material strength obtained from the two types of specimens.Previous uniaxial impact tests have also demonstrated that the failure mode and the strain rate effect of cubic specimens are very different from that of cylindrical ones.However,the mechanical background of these findings is unclear.As an extension of the previous laboratory study,this study performs numerical SHPB tests of cubic and cylindrical concrete specimens subjected to uniaxial impact load with the validated numerical model.The stress states of cubic specimens in relation to its failure mode under different strain rates is analyzed and compared with cylindrical specimens.The detailed analyses of the numerical simulation results show that the lateral inertial confinement of the cylindrical specimen is higher than that of the cubic specimen under the same strain rates.For cubic specimen,the corners are more severely damaged because of the lower lateral confinement and the occurrence of the tensile radial stress which is not observed in cylindrical specimens.These results explain why the dynamic material strengths obtained from the two types of specimens are different and are strain rate dependent.Based on the simulation results,an empirical formula of conversion factor as a function of strain rate is proposed,which supplements the traditional conversion factor for quasi-static material strength.It can be used for transforming the dynamic compressive strength from cylinders to cubes obtained from impact tests at different strain rates.     

论中国特色军事文化的理论渊源

中国特色军事文化以马克思主义军事文化为理论基础,特别是其中的实事求是思想、战争是政治的继续思想和人民战争思想,构成了中国特色军事文化的理论基石;中国特色军事文化形成于我党领导的军事文化实践中,科学文化教育实践和政治宣传工作实践是中国特色军事文化形成的坚实平台;人类优秀文化成果充实了中国特色军事文化的思想内涵,中国特色军事文化批判地吸收和继承了中国传统军事文化中的朴素军事辩证法、崇道尚义、以仁为本的军事伦理思想和知彼知己、百战不殆的战争认识论,融和、借鉴了西方优秀文化中的民主思想和科学思想.     

红军无线电通信技术在土地革命战争时期的历史作用

无线电通信技术作为当时的"高科技"技术,得到了中国共产党的高度重视。中国共产党为了掌握这一技术,花费了巨大的代价。历史证明了中国共产党这一高瞻远瞩的决定是正确的。这一技术在之后的中国革命战争中有力地保障红军作战的指挥与协同;保障苏区与中央、中央与共产国际之间的通信联络;侦听敌电、破译密码、获取敌情;抄收中外新闻、广播红色消息等等,发挥了特殊的作用。     

基于波束域MUSIC方法的高分辨方位估计

现代声纳系统普遍采用水听器基阵和一定的信号处理来提高对目标的检测和定位能力,而基阵的波束形成则在其中起着核心作用。文中研究了窄带波束域高分辨方位估计技术,分析了波束域MUSIC方位估计的构造过程和具体实现方法。仿真计算表明,基于波束域MUSIC的方位估计算法是一种分辨空间小角域内多个目标的有效方法。     

试论技术基础与国防科技工业自主创新

本文论述了技术基础工作在国防科技工业自主创新中的作用和地位,阐述了技术基础创新的内涵和提高技术基础创新能力的关键环节,并对“十一五”技术基础工作的发展提出了几点思考。     

基于信息化的国防资源共享机制研究

本文结合我国国防资源信息共享面临的新形势和新要求,对我国国防资源信息共享现状、影响因素及国防资源信息共享的必要性进行了分析,提出推进我国国防资源信息共享的若干措施。     

钛合金材料的等离子弧焊接技术

通过对钛合金管的等离子弧焊接工艺技术探索及分析、试验,掌握了钛合金材料的焊接要点,解决了钛合金在焊接时熔池和高温区的保护措施,改进了保护装置结构和喷嘴尺寸,在合理规范的参数下获得了满意的接头质量。     

认真做好"三大规范"编制工作提高企业标准化水平

本文阐述了"三大规范"编制工作的意义,并从"三大规范"编制工作的实践中,总结出了一些具体做法、写法及体会,以期对企业在这方面的工作有一些借鉴作用。     

基于RWG基函数的电场积分方程的奇异性处理

采用矩量法分析导体三维散射体时,基于RWG基函数的电场积分方程存在奇异性,如果直接使用数值积分,则准确性很低。为了得到准确的积分结果,将被积函数拆分为2部分,对于无奇异点的部分直接使用数值积分求解,而对于包含奇异点的部分通过积分变换简化被积函数,得到解析表达式,计算实例验证了这种方法的正确性。