Connecting parameters optimization on unsymmetrical twin-tower structure linked by sky-bridge

Based on a simplified 3-DOF model of twin-tower structure linked by a sky-bridge, the frequency response functions, the displacement power spectral density （PSD） functions, and the time-averaged total vibration energy were derived, by assuming the white noise as the earthquake excitation. The effects of connecting parameters, such as linking stiffness ratio and linking damping ratio, on the structural vibration responses were then studied, and the optimal connecting parameters were obtained to minimize the vibration energy of either the independent monomer tower or the integral structure. The influences of sky-bridge elevation position on the optimal connecting parameters were also discussed. Finally, the distribution characteristics of the top displacement PSD and the structural responses, excited by El Centro, Taft and artificial waves, were compared in both frequency and time domain. It is found that the connecting parameters at either end of connection interactively affect the responses of the towers. The optimal connecting parameters can greatly improve the damping connections on their seismic reduction effectiveness, but are unable to reduce the seismic responses of the towers to the best extent simultaneously. It is also indicated that the optimal connecting parameters derived from the simplified 3-DOF model are applicable for two multi-story structures linked by a sky-bridge with dampers. The seismic reduction effectiveness obtained varies from 0.3 to 1.0 with different sky-bridge mass ratio. The displacement responses of the example structures are reduced by approximately 22% with sky-bridge connections.     

质子辐射环境下PNP输入双极运算放大器辐照效应与退火特性

对不同偏置下的PNP输入双极运算放大器在3、10 MeV两种质子能量下的辐照效应进行了研究,并将质子辐射损伤效应与0.5Gy(Si)/s剂量率60 Coγ射线辐射损伤效应进行了比较,以探究质子和γ射线产生的辐射损伤之间的对应关系。结果表明,运放LM837对γ射线的敏感程度较10 MeV质子和3 MeV质子的小,然而其室温退火后的后损伤效应却更严重;相同等效总剂量条件下,10 MeV质子造成的损伤较3 MeV质子的高;质子辐射中器件的偏置条件对损伤影响不大。     

几款电脑Hi-Fi的解码器

大家之所以这么认为只是一般电脑声卡在数模转换的模拟部分水准比Hi-Fi差太多.但这只要外接好的解码器就行了.用同轴输出的解码器接声卡或带USB接口的解码器(多用于笔记本,解码器其实就是一个高级的声卡),使电脑(包括PC,MAC系统)Hi-Fi渐渐流行起来.通过解码器驳接到功放,这是PC Hi-Fi最佳音源效果.     

相邻结构减震体系参数随机性影响分析

根据黏滞阻尼器连接相邻结构减震体系的2-DOF模型,以平稳白噪声为地震激励,建立了结构振动能量表达式,分别以单体塔楼和整体结构的振动能量最小为控制目标,建立了优化连接阻尼参数理论表达式.分析了结构频率比和质量比的随机性对优化连接阻尼、结构减震效果的影响以及连接阻尼参数随机性对减震效果的影响.最后对某工程算例进行了位移反应分析,对比了减震效果.结果表明,依据简化模型得到的优化连接参数可以适用于多自由度体系,两结构频率比的随机性对优化连接参数及减震效果有一定影响,质量比的随机性对二者影响较小,而优化连接阻尼随机性对减震效果的影响则可以忽略不计.     

基于光强变化场景的目标检测与跟踪新方法

为在光强变化场景下实现目标的检测与跟踪,研究了一种新方法。该方法综合集成了Vibe算法与粒子滤波算法的优点,通过在改进Vibe算法中引入光照补偿模型、重构粒子滤波模型,解决了2种方法对光强变化的自适应性难题;在局部三值模式(LTP)中建立了一种自适应阈值方法,并采用线性回归分类方法,实现了目标跟踪。通过开发相应程序并将所提新方法的结果与标准结果进行对比验证,验证结果表明：新方法的偏差小于文中其他3个对照方法的相应偏差,该方法对光强变化场景下的目标检测与跟踪研究有一定帮助。