Reference values of respiratory and peripheral muscle function in rats

Skeletal muscle dysfunction is a common systemic manifestation in several prevalent diseases. Predictive values are useful tools for the diagnosis and prognosis of diseases. In experimental animals, no reference values of muscle function evaluation have been so far reported. The objective was to obtain predictive values of maximal inspiratory pressure (MIP) and grip strength measurements in healthy rats. In 70 healthy rats, MIP and grip strength were measured in vivo weekly for five consecutive weeks using non‐invasive methodologies. Three ranges of rat body weights (250–299, 300–349 and 350–399 g) and lengths (37.0–41.0, 41.1–42.0 and 42.1–44.0 cm) were established. MIP and grip strength measurements falling within the ranges of weight 350–399 and 300–349 g and length 42.1–44.0 cm were significantly greater than values falling within 250–299 g and 37.0–41.0 cm ranges respectively. Specific weight‐ and length‐percentile distributions for MIP and grip strength measurements were calculated. As significant direct correlations were observed between rat weights and lengths and either MIP or grip strength measurements, regression equations relating all these variables were also determined. Skeletal muscle dysfunction is frequently associated with highly prevalent conditions. The significant predictive equations described for both MIP and grip strength measurements will enable scientists to better estimate the respiratory and peripheral muscle dysfunctions of laboratory animals, especially when conducting follow‐up and/or intervention investigations.     

基于人机界面优化目的的森林灭火手泵操作力研究

为了优化森林灭火手泵的人机操作界面,提高操作的舒适性和效率,该文通过最大操作力的测量,研究了森林灭火手泵的握持直径、握持长度和握持姿势对操作者操作力的影响。结果表明:①手泵握持直径、握持长度以及握持姿势对操作力的影响都很显著。② 手泵合理握持长度为450～800 mm,握持直径为32～35 mm,内筒直径取144 mm,握持姿势以采用出水方向偏离水平面向上为宜。      

基于复合滑移理论的轮胎抓地状态建模与验证

为了精确地估计轮胎抓地状态,该文针对影响汽车行驶稳定性和安全性的轮胎和地面之间的相互作用模型进行了深入研究。采用轮胎刷子模型,同时考虑纵向滑移和侧向滑移情况,提出了改进的复合滑移轮胎刷子模型。利用抓地力和最大滚动摩擦系数确定轮胎抓地状态。通过定义复合滑移系数建立了一个关于抓地状态的一元三次方程式,讨论模型中参数对抓地状态的影响,为了提高模型适应性,同时考虑了速度与最大滚动摩擦系数的变化关系。选用225/60R18轮胎的某车型进行3次重复双移线试验,结果显示:在转向时间段内(1.8~2,3.2~3.4,4.4~4.6 s)抓地状态分别为0.54、0.79和0.39,与估计值极限误差分别为4%、5.4%和5.2%,而在直线行驶时测量值与估计值误差小于2%,说明此解析模型可为预测轮胎滑移状态提供一种新的方法。该文对汽车操纵稳定性的研究具有一定的指导意义。     

油锯动静态特性对操作者手臂肌肉疲劳的综合效应(I)──重量、手把直径和手臂姿势对掌长肌收缩的影响

该文通过表面肌电图研究了油锯重量、手把直径和手臂姿势对掌长肌收缩强度的影响．结果表明，重量和手把直径对掌长肌收缩强度的影响很显著，而手臂姿势的影响不显著．通过回归分析求出了３个方程：①握持重量与掌长肌收缩功率的回归方程；②握持力与掌长肌收缩功率的回归方程；③握持重量与所需握持力的回归方程．中国人生理上的合理油锯手把直径和油锯重量分别为３０ｍｍ左右和４～６ｋｇ     

油锯橡胶把套的隔振实验研究

本文对油锯橡胶把套的振动特性进行了实验研究。结果表明,橡胶把套对于高频振动(100～200Hz)有较明显的隔振作用。橡胶把套的使用性能除硬度以HA45±5为宜外,还应包括扯断强度、冲击弹性、耐油性等物理机械性能指标。     

Finite Element Analysis of Mechanical Behavior of High Strength Bolt Friction Grip Long Joint

In order to study the mechanical behavior and stress state of the high strength bolt friction grip long joint, fourteen different bolted connections are studied with the three-dimensional finite element analysis which is based on the general FE software ANSYS. The force-delivering ratio of each bolt, the stress concentration at the edge of the bolt hole, the stress state of the high strength bolt and the force-delivering coefficient before the bolt hole are specially studied. Also, the ranges of these parameters’ value are presented clearly. The results presented would be useful as references to these type joint's design and computation.