轮胎试验台六分力解算、标定与优化分析

轮胎试验台的力与力矩测试精度直接影响到轮胎数据的准确性,应用多体动力学理论对所研发的平板式六自由度低速轮胎试验台进行研究,分析了该试验台姿态控制的机理,推导出试验台轮胎六分力解算公式,并用abaqus有限元软件验证其准确性。然后对设计加工出的试验台进行标定,结果表明:3个方向的力吻合较好,但是力矩并不特别理想。经合理分析假设,试验台6个电缸铰支的硬点实际安装中存在空间的偏差,对其进行辨识优化分析,结果表明:优化后三方向的力及力矩与标定值吻合的精度符合要求,力的精度高于0.75%,力矩精度可达1%左右,证明了铰支安装偏差的假设是合理的,也体现出该轮胎试验台在测试精度上的优势。     

珠江口两岸耕地变化驱动机制分析

利用1988—2004年耕地及相关的统计和普查数据,应用主成分分析法诊断影响耕地动态变化的主要驱动因子,揭示了耕地变化的人文驱动机制。在此基础上,应用多元回归分析法分析耕地与驱动因子之间的综合定量规律。分析耕地的驱动机制,对今后合理利用耕地资源、控制耕地进一步减少、保持耕地动态平衡具有重要意义。     

Assessment of dairy cow locomotion in a commercial farm setting: The effects of walking speed on ground reaction forces and temporal and linear stride characteristics

Objectives of this study were to determine the effects of walking speed on ground reaction force (GRF) parameters and to explore inter- and intra-individual variability with unsupervised data collection in a commercial farm setting.We used eight high producing loose-housed Holstein Friesian cows consistently scored sound, with no veterinary treatment during the collection period. Cows walked freely (0.52-1.37 m/s) over a five force platform array, twice daily, following milking. GRF data were split into speed categories and temporal and kinetic gait parameters extracted. A general linear model was carried out to determine effects of speed.Variation in parameters between cows is inconsistent, while between speed categories (containing data from multiple cows) the parameters which vary are consistent. Stance and stride time were reduced with increasing speed but no change in peak vertical GRF or duty factor was found. This ability to track parameters within an individual over time aids detection of subtle changes associated with lameness.     

我国现代先进生产力发展的层次性、阶段性与党的"三个代表"作用

代表中国先进生产力的发展要求是"三个代表"的基础。我国现代先进生产力的发展具有多层次性和多阶段性。我国现代先进生产力的这一特点与中国共产党作为先进生产力主体力量先进部队的阶级特性,决定了党必然代表中国先进生产力的发展要求。面向新世纪,我们党坚定地站到先进生产力的前沿,大力推进理论创新与科技创新,从而进一步解决好了党在新世纪"如何代表"的问题。     

后疫情背景下安徽省农业企业行业环境分析

通过采用PESTEL分析和波特五力模型的方法，分析安徽省农业企业在发展过程中的内部和外部因素的影响，得出企业要长久的发展，需要增强企业的核心竞争力、组织员工学习专业技能、创新发展、完善企业的制度。