副车架疲劳载荷分析方法

结合LMSTWR软件,详细介绍了基于混合路面的轮心位移反求法求取副车架载荷谱的方法。通过在某MPV上布置合适传感器,在试验场测得道路载荷谱信号。根据实测的数据,建立整车多体动力学模型。基于处理后的道路载荷谱与多体动力学模型进行虚拟迭代,并进行副车架载荷分解。结果表明,迭代仿真得到的信号与试验值吻合度较好。     

工业大麻割晒机的三维仿真设计

针对当前我国工业大麻割晒机研究现状与发展需求,运用三维软件UG设计了一款工业大麻割晒机,包括夹持输送机构、切割机构、传动机构、机架等。首先对星轮式拨禾机构、往复式切割器等零部件进行三维建模,然后根据各零部件之间的准确约束进行整机装配,并对样机各运转部件进行了干涉检查,仿真结果表明所设计的工业大麻割晒机符合农艺要求,并为后续的虚拟样机运动仿真、割台的结构优化奠定了良好的基础,提高了样机的研发速度。     

基于多源数据的上海城市公园使用满意度关键影响因素

以上海市综合公园--人民公园和复兴公园为研究样本,采用问卷调查、实地监测和网络点评数据3种调查方法对影响城市公园使用满意度的5类17个影响因素进行分析.研究结果表明,城市公园的游憩环境、活动与设施水平对公园整体满意度影响显著;不同年龄段的公园使用者对城市公园满意度的关注点各不相同,老年人关注公园的服务环境,中年人对公园管理有着较高的要求,青年人更关注公园特色.基于多源数据分析的公园满意度具有一致性,可以交叉验证,置信度更高.在此基础上,总结了影响城市居民公园使用满意度的主导因素,并提出公园空间品质提升的优化策略.     

Spatio-temporal dynamics of technical efficiency in China’s specialized markets: A stochastic frontier analysis approach

China’s specialized markets as a special form of bottom-up capital agglomeration have played a key role in fostering regional development. It once exhibited positive externalities with high efficiencies. However, given the rapid proliferation of specialized markets and the penetration of E-commerce, their advantages may have shifted and the understanding of this shift is limited. The paper explores the spatio-temporal dynamics of China’s specialized markets in terms of technical efficiency. Based on turnover data from Statistical Yearbooks of China Commodity Exchange Market from 2000 to 2016, technical efficiencies in specialized markets are measured by a Stochastic Frontier Analysis (SFA) approach using panel data. The results show that (a) the technical efficiencies in China’s specialized markets are significantly divergent in space over time; (b) labor input has notable effect on efficiency increase, while capital input has no significant effect; (c) informatization level, cluster size, and degree of market openness are identified to have a positive effect on specialized market’s technical efficiency. This paper argues that specialized markets should be taken seriously in the cluster evolution research. The role of proximity and the bounded links between specialized markets and their local clusters is the key to understanding their changing forms, performances, and trajectories.     

Effects of dietary vitamin C on growth,antioxidant activity,and immunity in ricefield eel (Monopterus albus)

A 10-week feeding trial aimed to investigate the effects of dietary vitamin C (l -ascorbic acid) on growth, antioxidant activity, and immunity in ricefield eel, Monopterus albus. Six diets were formulated with different levels of vitamin C supplementation (0.1, 17.5, 34.8, 68.6, 139.7, and 278.5 mg/kg). The results indicated that the weight gain (WG) of the M. albus fed the diets with vitamin C was remarkably higher than that of the M. albus fed the control diet (p < .05), and the quadratic analysis showed an optimal vitamin C level of 80.66 mg/kg. Compared with the control group, serum lysozyme activities, the complement pathway, red blood cell counts, white blood cell counts, immunoglobulin M, and phagocytosis percentage were significantly increased (p < .05) in the treatment groups, and superoxide dismutase activity, serum glucose, and malondialdehyde content were significantly decreased (p < .05) in the treatment groups. The challenge trial with Aeromonas hydrophila showed that the M. albus fed the diets with vitamin C had remarkably reduced cumulative mortality compared with those fed the control diet (p < .05), and mortality in the 68.60 mg/kg diet group was the lowest. Based on WG, the optimal vitamin C supplementation level for M. albus was estimated to be 80.66 mg/kg.