Development of a generalised equivalent estimation approach for multi-axle vehicle handling dynamics

This paper devotes analytical effort in developing the 2M equivalent approach to analyse both the effect of vehicle body roll and n-axle handling on vehicle dynamics. The 1M equivalent vehicle 2DOF equation including an equivalent roll effect was derived from the conventional two-axle 3DOF vehicle model. And the 1M equivalent dynamics concepts were calculated to evaluate the steady-state steering, frequency characteristics, and root locus of the two-axle vehicle with only the effect of body roll. This 1M equivalent approach is extended to a three-axle 3DOF model to derive similar 1M equivalent mathematical identities including an equivalent roll effect. The 1M equivalent wheelbases and stability factor with the effect of the third axle or body roll, and 2M equivalent wheelbase and stability factor including both the effect of body roll and the third-axle handling were derived to evaluate the steady-state steering, frequency characteristics, and root locus of the three-axle vehicle. By using the recursive method, the generalised 1M equivalent wheelbase and stability factor with the effect of n-axle handling and 2M equivalent generalised wheelbase and stability factor including both the effect of body roll and n-axle handling were derived to evaluate the steady-state steering, frequency characteristics, and root locus of the n-axle vehicle. The 2M equivalent approach and developed generalised mathematical handling concepts were validated to be useful and could serve as an important tool for estimating both the effect of vehicle body roll and n-axle handling on multi-axle vehicle dynamics.     

基于复合建模方法的轴系扭转振动特性及仿真

为了提高主机轴系计算准确度,本文提出了一种新型的主机轴系建模方法,该方法将主机轴系分为连续子系统和离散子系统。推进轴段如螺旋桨轴、中间轴、螺旋桨及法兰划分为连续子系统,柴油机曲轴端划分为离散子系统。分别应用波分析法和多自由度动力特性分析,得到连续子系统和离散子系统的控制方程,同时通过边界条件将两个子系统动态刚度矩阵连接,推导出全局控制方程。对某型主机轴系扭转振动计算进行了仿真分析,并与传统建模方法比较。从计算结果可知,在高阶模态上,新型建模方法计算更精确,更接近真实振动状态,同时在保证相同计算精度的情况下,新型建模计算方法计算时间和计算资源占用较少,相对更为简便。同时,新型建模方法克服了当模态节点集中于轴段时,传统建模方法由于将轴系等效为一至两个质量单元而引起的节点偏移所带来的误差,这在实际主机轴系计算特别是长推进轴和刚度较低的轴系中具有重要意义。     

Towards the Incorporation of Environmental Impacts into Pavement Management Systems

Environmental nuisances (such as greenhouse gases and noise) may be generated during the use phase of the pavement life cycle, with these known to significantly affect the environment. However, no attempt has yet been made to gather information concerning the processes involved in the generation of environmental impacts, and to evaluate them. To address this issue, this paper reviews the knowledge base and relevant methods relating to environmental impact assessment and pavement management. It then presents a conceptual model, integrating impact pathway approach and life cycle cost analysis principles and providing a comprehensive framework for quantification and incorporation of environmental impacts into pavement management. This study shows that pavement management influences environmental impacts occurring during the use phase of the pavement life cycle. It establishes causal links between pavement management and nuisance generation, between nuisances and their impact on receptors, and finally between these impacts and their costs. This study also suggests that incorporating environmental impacts into pavement management systems is feasible and describes how existing and future methodologies and tools may be integrated to support this incorporation. Finally, this study underlines that the inaccuracy of current knowledge and data limits the scope of this conceptual model to network-level decisions.     

二维平行放位装车问题的布局约束启发式算法

在分析二给平行入位货物装车问题的基础上，对货物装车问题设定了布局约束，构造了布局约束启发式算法。实验结果表明，此算法可以有效求得问题的优化或近似优化解，是求解此类问题的一个较好的方案。     

重型钢引桥提升机的设计

详细地分析了钢引桥在提升过程中的技术要求,并在此基础上提出了此类提升机的设计计算依据和一个应用实例。     

轴对称弹塑性大变形有限元法在断裂局部方法中的应用

研究了断裂局部方法中测定材料的临界解理应力σ_u和威布尔指数m的方法。进行了16Mn钢的光滑试件和缺口试件的低温拉伸试验。测定了材料的应力-应变曲线和缺口试样的断裂载荷,编制了轴对称弹塑性大变形有限元分析程序。程序中大变形的分析采用了完全的拉格朗日方法,非线性方程组的求解采用了修正的牛顿法。计算了缺口试件的应力-应变场,编制了根据缺口试件的断裂载荷和有限元计算中得到的应力、应变场,计算m和σ_u的程序,测定了16Mn钢的临界解理应力σ_u和威布尔指数m。     

从契约经济学角度认识保价运输

通过阐述保价运输的产生与发展,提出了保价运输的演进过程,在高风险低运费的不变规律下,产生了承运人限额赔偿制度和保价运输制度。根据不完全契约理论,阐明运输活动的特点决定运输契约是典型的不完全契约,以及产生运输契约的不完全性因素,即交易费用的存在是运输契约不完全的根本原因,有限理性与机会主义的存在,非对称信息的存在。在此基础上,提出保价运输制度是修正运输契约不完全性的有效途径。     

Development of evolutionary cone type LSD for SUV/RV utilizing the axiomatic approach and the ultrasonic nano crystal surface modification technology

Surface topology, cone angle and the forces acting on the cone of the clutch type limited slip differential (LSD) are major design parameters for the bias ratio and the noise condition. Therefore much research has been dedicated to these developments but the results have been used to submit patents. A new cone type limited slip differential for sport utility vehicles and recreational vehicles, which has a very simple structure and easy compliance with the vehicle performance, has been developed by the axiomatic approach and the ultrasonic nano crystal surface modification (UNSM) technology. The design criteria and optimal value of the design parameters are determined by the axiomatic approach utilizing CAE tools. Test methodologies in a test rig and in a vehicle were also developed. Test results showed good performance of bias ratio and noise level but durability is still under testing. This study is an extension of F2006P266, FISITA 2006.     

坚持以人为本是做好新时期思想政治工作的关键

以人为本不仅是社会主义和谐社会基本特征的集中体现,也是加强和改进思想政治工作的重要突破口,新时期思想政治工作必须坚持以人为本的原则,注重人性化的工作方法,充分尊重人的个性化,关注解决人的实际生活问题,切实保障思想政治工作的实效性。     

沥青混合料破坏阶段的黏弹性行为

采用基于连续破坏力学和功势原理的模型对沥青混合料破坏阶段的黏弹性行为进行研究.该模型中利用虚应变来描述沥青混合料的时间依赖性,利用破坏参数和虚劲度模量的关系描述沥青混合料的破坏特性.通过不同条件下的复数模量试验确定了沥青混合料的线黏弹性力学参数,进行了不同条件下的恒应变率压缩试验来确定沥青混合料的破坏特性.确定了破坏参数、应力的勒贝格范数和虚劲度模量之间的关系,进而用线性分段法计算了沥青混合料的黏弹性应变.利用该模型对不同条件下的恒应变率压缩试验结果进行了分析.结果表明:预测值和实测值吻合良好.