LRB曲线桥震致碰撞效应的非线性分析方法

发展了一种适用于体元模拟联间轴向正面碰撞效应的束缚面型碰撞单元（Constraint-sur-face Impact Element,CIE）;基于柔度法给出了不同以往文献中碰撞单元刚度的计算取值,该取值不仅理论合理且在物理角度可解释其合理性。将该方法应用于广州潮汕机场航站楼高架桥的震致碰撞分析。箱梁采用壳单元模拟,伸缩缝位置设有CIE,桥墩与箱梁间设置隔震单元模拟铅芯橡胶隔振支座（Lead-rubber Bearing,LRB）,采用通过试验得到的双线性刚度模型模拟其物理行为。采用非线性直接积分法进行时程分析,主要考察联间的碰撞力、LRB滞回耗能、LRB位移量、基底弯矩、剪力以及碰撞力分别对这些因素的影响。     

蒲石河抽水蓄能电站下库蓄水对下游的影响

为了确保蒲石河抽水蓄能电站工程按期投产发电,保证水库及电站初期蓄水和发电运行安全,就不同蓄水方案对下游各业用水部门的影响进行了分析。下游各行业用水的调查分析,为尽可能减轻水库初期蓄水影响,制定切实可行的电站初期下闸蓄水方案提供了技术支撑。     

Highly accurate SNR measurement using the covariance of two SEM images with the identical view

Quality of an SEM image is strongly influenced by the extent of noise. As a well-known method in the field of SEM, the covariance is applied to measure the signal-to-noise ratio (SNR). This method has potential ability for highly accurate measurement of the SNR, which is hardly known until now. If the precautions discussed in this article are adopted, that method can demonstrate its real ability. These precautions are strongly related to "proper acquisition of two images with the identical view," "alignment of an aperture diaphragm," "reduction of charging phenomena," "elimination of particular noises," and "accurate focusing," As necessary, characteristics in SEM signal and noise are investigated from a few standpoints. When using the maximum performance of this measurement, SNR of many SEM images obtained in a variety of the SEM operating conditions and specimens can be measured accurately.     

高速信号采集存储及传输系统的设计与实现

为解决高速数据采集系统中的数据缓存和传输速度瓶颈,设计并实现了一种基于光纤通道协议和DDR2 SODIMM存储的高速数据传输、存储系统。利用Stratix Ⅳ GX系列FPGA和QuartusⅡ中自带的DDR2 IP核以及高速收发器IP核,实现了PCI9056的本地接口、DDR2控制器、光纤通道协议和高速串行数据的转换发送,最终实现了数据的高速存储和传输。     

一种嵌入式操作系统休眠唤醒后程序自动运行的方法

针对目前采用休眠方式来实现嵌入式系统快速启动后,一些动态进程或进程的执行过程不能正常恢复而导致进程不能按照原来的方式正常运行的情况,运用一种新的方法 ,实现了基于休眠的嵌入式操作系统启动后,自动运行任何形式的目标脚本和应用程序。     

Drivers and effects of enterprise resource planning post-implementation learning

The use of enterprise resource planning (ERP) systems has grown enormously since 1990, but the failure to completely learn how to use them continues to produce disappointing results. Today's rapidly changing business environment and the integrative applications of ERP systems force users to continuously learn new skills after ERP implementation. This study explores the effects of post-implementation learning on ERP usage and ERP impact and identifies the factors that can impact post-implementation learning, such as social capital and post-training self-efficacy. This study employs a survey method to examine the perceptions of ERP users. The theoretical model is tested by using structural equation modelling on a dataset of 812 users. This study finds that post-implementation learning has a significant positive effect on ERP usage and ERP impact, and that social capital and post-training self-efficacy are important antecedent factors of post-implementation learning. Post-training self-efficacy also significantly affects ERP usage and ERP impact. The implications for research, practice and future research directions are discussed.     

45号钢在往复冲击载荷作用下的塑性变形

摘要：采用钢球冲击45号钢盘,观测了在不同接触条件、冲击次数及载荷条件下钢盘表面的塑性变形情况．发现在低冲击次数条件下,使用低黏度油的凹坑深度与干接触相近,但在高次数冲击条件下,冲击深度与干接触条件下相比大幅度变浅．而高黏度油条件下的凹坑深度一直最浅．在其他条件相同时,冲击深度随载荷的增加而增加．冲击时,由于凹坑中心产生的热量不断向边缘传递,使凹坑边缘形成凸起即形成所谓彩虹环．彩虹环随润滑油黏度的增加及载荷的增加而高度增加．润滑油的使用可以降低材料表面的塑性变形和磨损．对于干接触条件,凹坑内部发生微细颗粒碎化．而油润滑时凹坑内部出现微裂纹．微细颗粒碎化及微裂纹的程度均随冲击次数和载荷的增加而增加．     

基于时频分析的混沌谐波线性混合信号提取算法

混沌信号与谐波信号的分离问题是混沌信号处理中的重点问题,时频分析理论的日趋成熟为该问题带来了新的解决方案。针对不同噪声情况下混沌背景下谐波信号的提取进行分析,将小波变换与EMD方法进行比较,经仿真实验总结出一种新的谐波信号提取的融合算法,仿真实验验证了该算法的有效性。     

MIMO空间相关信道下格规约辅助的信号检测

针对多输入多输出空间相关信道环境,提出了一种基于格规约理论的最小均方误差检测算法.该算法考虑了空间相关性的影响,利用复数Lenstra-Lenstra-Lovász格规约算法克服了传统的线性最小均方误差检测器分集阶数随相关系数增加而减小的缺点,使检测到的信号在高信噪比下可以达到比传统算法低几个数量级的误码率.理论分析与仿真结果表明,在信道为Kronecker相关平坦衰落模型下,接收端采用最小均方误差信道估计,发射端采用QPSK调制未使用信道编码,当比特信噪比大于18dB时,基于格规约理论的最小均方误差检测器的误码率低于传统最小均方误差检测器的误码率;发射端采用(2,1,3)卷积码、接收端采用硬判决Viterbi译码,当信噪比大于16dB时,基于格规约理论的最小均方误差检测器的误码率低于传统最小均方误差检测器的误码率,且基于格规约理论的最小均方误差检测器的分集阶数不受相关系数的影响,等于接收天线数N.     

枯草芽孢杆菌谷氨酰胺转氨酶的异源表达

以野生型枯草芽孢杆菌基因组DNA为模板,PCR扩增获得带有sD序列及谷氨酸棒状杆菌信号肽AS0949的BTG基因。将其与大肠杆菌-谷氨酸棒状杆菌穿梭表达载体pXMJ19连接,构建重组质粒pXMJ19-Sbtf转化谷氨酸棒状杆菌ATCC13032。经IPTG诱导后该重组茵发酵液具有交联酪蛋白的能力,表明该重组茵能够实现分泌表达。