磁粉制动器的滑差功率研究

首先用理论方法对经过结构优化的磁粉制动器的滑差功率进行了计算，然后在自行设计、安装的实验台上对其进行了温升实验，所得理论计算值和实测值的一致性较好，在此基础上确定了它的额定滑差功率线图。     

广义线性系统的输出反馈和极点配置

研究了广义线性系统的输出反馈和极点配置问题。引入“正常化”概念,从而推导出类似于正常线性系统有关输出反馈和极点配置问题的一些重要结论。     

自然伽玛曲线上的“海侵针”及其地质意义

自然伽玛曲线上的尖锥状～针状特高异常—“海侵针”,常可指示海侵作用与海相层的存在:“阵发式”海退与“振荡式”海退则是含煤岩系形成过程中两类常见的利于聚煤的海退类型.     

Internal interactions within the human circadian system: the masking effect

Summary In the realm of human circadian rhythms, the masking effect is defined as the change in the course of deep body temperature induced by changes in the degree of physical activity, or by the alteration between sleep and wake. This effect is particularly obvious during internal desynchronization where the rhythms of deep body temperature, and the sleep-wake sleep-wake sleep cycle — i.e. one of the masking factors — run with different periods.Every sleep onset is accompanied by a rapid drop, and wake onset by a rapid rise in deep body temperature, each one with an overshoot of about 50% of the steady state variations. When rhythms are calculated, with the dominant temperature period as the screening period, exclusively from data obtained during sleep episodes, on the one hand, and from those obtained exclusively during wake, on the other, two average cycles emerge: the sleep temperature curve and the wake temperature curve. Both run in parallel but are separated by the masking effcct. As derived from many experiments, the mean masking effect amounts to 0.28±0.06°C. The masking effect also depends to some extent on the phase of the temperature rhtthm; it is larger than average around the temperature maximum and during the descending phase of the temperature cycle, where the alertness commonly is highest and the probability to sleep, in general, and the REM sleep propensity, in particular, are smaller than average. This also can be interpreted to indicate that the sleep temperature curve is phase advanced relative to the wake temperature curve; this, on the average, by 0.9±0.3 h.If the individually determined amount of masking is added to the temperature data obtained during sleep, or substracted from the temperature data obtained during wake, a temperature curve emerges that can be though of as being purified of the masking effect. Analyses of this artificial curve allow estimation of that part of the internal interactions uninfluenced by the masking effect. On the average, about half of the amount of interaction between the rhythm of sleep-wake and that of deep body temperature is explained by the masking effect, whereas the other half is oscillatory interaction. Both types of interaction are inherent and inseparable parts of the circadian clock mechanism, as can be deduced from model considerations.     

区间删失数据下基于OLLGG分布的多参数回归模型的参数估计

该文基于Ⅱ型区间删失数据,在OLLGG分布下提出多参数回归模型,通过线性回归刻画分布参数与协变量之间的关系,并通过极大似然方法给出了模型的参数估计,数值模拟验证了模型参数的估计有良好的性质,将提出的模型应用到血友病患者HIV感染的数据中,发现提出的模型对数据有灵活的拟合效果.     

考虑应力集中的吊车梁多轴疲劳寿命预测

钢结构吊车梁在工业建筑中被广泛应用,应力集中的存在导致几何不连续位置在复杂应力下服役.借助有限元法分析吊车梁应力-应变状态,确定危险点位置,并提取应力、应变分量;以应变能密度作为损伤参量并以最大平面为临界面,基于能量准则建立临界面位置数值计算方法,结合有限元结果给出吊车梁临界面位置;考虑吊车梁在非对称载荷下服役,借助Goodman方程进行平均应力修正,并结合Q355D钢近似S-N曲线计算疲劳寿命.该方法考虑了应力集中处多轴应力对疲劳损伤的影响,可以为复杂应力下几何不连续钢构件的疲劳寿命评估提供新方法.     

满旗流形Sp(3)/T的不变爱因斯坦度量

研究了迷向表示分为9个不可约子空间的满旗流形Sp(3)/T上的不变爱因斯坦度量,计算Sp(3)/T非零结构常数的值,根据其爱因斯坦方程,利用Maple软件得到64个不变爱因斯坦度量(差常数倍的情况下),在等距的意义下,其中有1个凯莱爱因斯坦度量和3个非凯莱爱因斯坦度量.     

扩展裂纹缺陷评定方法的优化研究

裂纹扩展的缺陷评定方法,越益受到了人们的重视,美国ＥＰＲＩ提出的“裂纹 推力图”方法,虽然准确合理,但方法偏于繁复,尚难于向工程界推广。清华大学力学 研究所曾先后提出几种评定方法,以期使评定过程得以简化。在此基础上,文章提出 “相容应力增量”法作为优化方法,它将使全部评定过程大为简化,从而为扩展裂纹的 缺陷评定方法向工程界推广创造便利条件。     

正规BCI-代数的“拟-广结并”构造

本文进一步讨论BCI—代数的拟结合部分的特征性质,引入正规BCI—代数的概念。同时给出一种构造正规BCI—代数的“拟—广结合并”方法。     

砂土中螺旋桩在斜拉荷载作用下的承载性能

为研究斜拉荷载倾斜角度和叶片埋深对螺旋桩极限承载力的影响,基于ABAQUS软件构建了砂土中螺旋桩的有限元模型,通过螺旋桩水平承载机理砂箱试验与竖向拉拔试验数据,对模型的准确性和可行性进行验证。设置4组不同叶片埋深的螺旋桩模型,分别施加不同角度的斜拉荷载,探讨了砂土地基中螺旋桩的承载性能与斜拉角度、叶片埋深的相关性。结果表明:砂土中螺旋桩的极限承载力随着斜拉角度的增大不断减小;当斜拉角度小于30°时,螺旋桩极限承载力与斜拉角度的关系曲线近似呈线性;螺旋桩极限承载力存在一个临界埋深比,当埋深比大于等于4时,承载力不随埋深比的增大而变化。推导了深埋状态下螺旋桩受斜拉荷载作用的极限承载力公式,经验证该公式能较好反映螺旋桩极限承载力随斜拉角度增大而逐渐下降的规律。