便携式林业机械(油锯)及其作业中的人类工效学

该文论述了油锯作业的安全问题及其与人体疲劳的关系．从人体生理学和人类工效学的角度概述了人体疲劳的研究情况．高强度的工作负荷是油锯作业人体疲劳的主要原因．文章最后提出对油锯及其作业进行合理的人类工效学设计是降低油锯工作负荷，减轻作业疲劳的有效方法．     

甘蔗收割机刀盘轴的疲劳分析和优化设计

通过实测甘蔗收割机作业工况的载荷信号,利用nCode Glphyworks进行信号处理,得到了能反映实际工作载荷的载荷谱。通过UG建立刀盘轴的三维实体模型,将三维实体模型导入ANSYS Workbench中进行网格划分和静力分析,得到刀盘在静力作用下的应力结果。根据载荷谱、有限元分析结果和材料的S-N曲线,利用nCode Designlife对刀盘轴进行了疲劳寿命预测,再根据静力分析和疲劳的结果,利用ANSYS Workbench对刀盘轴进行优化,最后验证优化后的刀盘轴是否满足实际使用的需求。     

用于某种电动客车的铝合金榫卯节点疲劳性能研究

针对铝合金电动中巴客车行驶环境中榫卯结构的疲劳强度问题,以铝合金榫卯节点为研究对象开展三点弯曲疲劳试验,研究铝合金榫卯节点疲劳性能。研究结果表明,榫卯节点裂纹萌生寿命位于总寿命的10%~20%区间。根据寿命曲线预估,每降低一个载荷等级,榫卯节点疲劳寿命约是前一载荷等级的2倍。疲劳破坏先是卯梁上翼缘受到挤压开始萌生裂纹,接着节点周围焊缝处产生新的裂纹,随着变形量增大,样件最后断裂失稳。     

轨道车辆焊接结构疲劳评估方法研究与实现

以城市轨道车辆为整体,运用HyperMesh建立整车有限元模型,在ANSYS环境中进行强度分析。采用子模型技术,切割车下焊接结构危险部位,提取关键工况边界条件,基于DVS1608标准实现了车下焊接结构的疲劳强度评估。结果表明,安装座的疲劳强度满足设计要求。     

钢板弹簧疲劳寿命可靠性计算

在讨论钢板弹簧疲劳寿命概率分布的基础上，研究了可靠度和置信度问题，给出了利用三参数Weibull分布计算疲劳寿命和可靠度的公式，计算实例表明，该法可方便地对所要求的任意可靠度和置信度进行寿命计算。     

Fracture Analysis of Tense Bolt

In this methods of fracture mechanics and reliability are used toanalyse the causes for failure of a flange bolt connecting an inclinded rope to the natural gas pipelinebridge spaning the Changjiang(the Yangtze River)loeated at Chongqing and the proper safetymeasures that should be required are propozed.     

A RESEARCH OF THE INFLUNCE OF RARE-EARTH ELEMENT ON THE THERMAL FATIGUE BEHAVIOR OF CAST IRON

It is known that cylinder heads, exhaust manifoids, ingot molds, etc. are often failed resulting from thermal fatigue. For this reason, the influence of RE on the thermal fatigue behavior of cast iron was studied by measn of a thermal fatigue test unit with completely constrained strain developed by ourselves. The test results shown that RE can improve the thermal fatigue resistance of cast iron greatly when residual RE contents surpass a critical value. This value is 0.04-0.045% for light Rare-Earth, and 0.045-0.05%; for heavy Rare-Earth. Further more, the relationship between RE and the thermophysical and mechanical properties of cast iron which have influence on thermal fatigue resisteance was also discussed.     

脱落酸预处理对低温胁迫下萝卜幼苗的缓解效应

以‘阳春早秀’萝卜幼苗为试材,通过叶面喷施不同质量浓度的脱落酸(ABA)(0,5,10,15,20 mg.L-1),在找出适宜质量浓度的基础上,进一步探讨了外源ABA对低温胁迫下萝卜幼苗的缓解效应.结果表明,ABA预处理能不同程度地提高萝卜幼苗叶片可溶性糖和脯氨酸(Pro)含量,降低其电解质渗漏率,以15 mg.L-1效果最明显.同一质量浓度ABA(15 mg.L-1)预处理幼苗后,随低温时间延长,可溶性糖和脯氨酸含量逐渐升高,抗氧化酶活性也显著高于同期对照,而丙二醛(MDA)含量显著低于同期对照.以上结果表明,适当质量浓度的外源ABA可通过增加渗透调节物质含量和提高抗氧化酶活性来提高萝卜幼苗对低温胁迫的抗性.     

Impact on Brain Wave Rhythm and Learning Efficiency by Color Temperature of Artificial Light Sources

This experiment tests the change rate of students α & β brain waves under different illuminance levels combining with three color temperatures (CCTs) to indicate the influence of light spectrum on human physiological rhythm.The result shows that the brain electrical activities have significant differences under various CCTs and illuminance levels.The excitement and sensitivity of brain are roughly proportional to the light CCTs and illuminance. Brain electrical activities are more sensible to high CCT illuminations. Keeping mental work in the same time period with the same study intensities, brain fatigue comes earlier and stronger in excitable state at high illuminace and high CCT illumination than in peacful state at low illuminance and low CCT illumination.This situation leads to the learning efficiency of students decreased sharply.An interesting phenomena is that when working in low illuminance and low CCT environment, learning efficiency of students rises with time passing by.That indicates this kind of lighting environment may lead to awake effect of brain. In some environments which have the same illuminance levels with different CCTs that bring about the similar brain activities, learning efficient change rates are different because of the diversity of light spectrum which may induce the different stimulus intensity.Further research work is needed to explain this phenomenon.This experiment points out that the long-term mental workload character during the process of study and comprehensive effect of time accumulationmust be seriously considered in classroom lighting design.