螺栓连接大变形梁非线性振动特性的实验研究

柔性机械臂、大型可展开天线等机械结构的动作精度受运动过程中大变形几何非线性和连接处接触非线性的影响十分显著。以含螺栓连接结构的大变形梁作为研究对象，针对动力学建模和振动特性开展了实验研究，通过数值计算验证了实验发现的非线性振动特性。搭建了含螺栓连接柔性大变形梁的实验台架，开展了敲击和正弦激振的实验测试。实验结果表明，螺栓连接的柔性梁较连续梁的（无螺栓连接）模态频率降低，阻尼增加，反映出随着激励能量增大，模态频率降低的非线性模态特征。改变螺栓连接位置会显著影响结构的模态频率，其变化规律可由求解线性矩阵特征值定性反映。     

青藏铁路含保温夹层路基厚度与地温关系的研究

通过对青藏铁路风火山段含有保温夹层的路基建立均匀介质分层纯导热模型并运用分层近似解法求出冻土表层的温度函数,结合Lachenbruch给出的冻土层的理论温度表达式,得到了路基填料层、保温层、地表年平均温度与正弦变化温度的振幅比三者之间的隐式方程,并应用该方程对三者之间的关系进行了分析.     

含砂雾封层在桥面铺装工程中的应用

结合含砂雾封层在国道205桥面铺装上的应用,深入分析了含砂雾封层的防水、防老化作用机理,本文系统总结了国道205桥面雾封层施工质量的控制要点,并对施工前后封层各项性能指标进行跟踪检测,分析结果表明采取含砂雾封层措施确实能对桥面早期微裂缝进行有效封水,延缓桥面病害的发生,延长沥青路面的使用寿命。     

大学生勤工助学体验性学习实践模式探索

以北京联合大学的大学生勤工助学体验性学习实践为例,通过课题研究,探讨了适用于高校大学生勤工助学体验性学习实践的模式。     

单快拍相干信号自适应波束形成方法

针对低快拍条件下相干信号波束形成问题,提出一种单快拍相干自适应波束形成方法。首先,构造Duvall特征消除器滤除阵列接收信号中的期望信号,再利用空间平滑方法解相关。然后,依据Hung Tuner算法对平滑后的协方差矩阵进行Gram Schmidt正交化,快速重构干扰信号子空间。最后,将静态权矢量在干扰子空间内的正交投影作为波束形成最优权矢量。该算法可有效避免协方差矩阵求逆和特征分解造成的复杂计算,且能降低由于期望信号泄露造成的子空间估计误差,在单快拍条件下性能良好。仿真分析验证了算法的优越性和理论分析的有效性。     

普通话在线游戏学习系统的研究与应用

针对希望进一步掌握普通话口语学习的外国学习者,该研究提出了一种普通话游戏学习系统.系统的学习模式结合了计算机技术和语言学研究成果,打破了传统的教学模式的限制,对学习者进行实时评测,提供学习报告与口语学习的最终评定结果.结果表明,该系统能够较为有效地辅助外国学习者的普通话口语学习.     

The expansion of GPCR transactivation-dependent signalling to include serine/threonine kinase receptors represents a new cell signalling frontier

G protein-coupled receptor (GPCR) signalling is mediated through transactivation-independent signalling pathways or the transactivation of protein tyrosine kinase receptors and the recently reported activation of the serine/threonine kinase receptors, most notably the transforming growth factor-β receptor family. Since the original observation of GPCR transactivation of protein tyrosine kinase receptors, there has been considerable work on the mechanism of transactivation and several pathways are prominent. These pathways include the “triple membrane bypass” pathway and the generation of reactive oxygen species. The recent recognition of GPCR transactivation of serine/threonine kinase receptors enormously broadens the GPCR signalling paradigm. It may be predicted that the transactivation of serine/threonine kinase receptors would have mechanistic similarities with transactivation of tyrosine kinase pathways; however, initial studies suggest that these two transactivation pathways are mechanistically distinct. Important questions are the relative importance of tyrosine and serine/threonine transactivation pathways, the contribution of transactivation to overall GPCR signalling, mechanisms of transactivation and the range of cell types in which this phenomenon occurs. The ultimate significance of transactivation-dependent signalling remains to be defined but it appears to be prominent and if so will represent a new cell signalling frontier.     

A Forward Selection Method on Customer Credit

In this paper, we discuss a selection and evaluation method of customer credit for the commercial bank loans operation, and put forth a forward selection model by optimization techniques. At last, we also give an example to analyze its application.