Effect of structural period and ground motion parameters on the earthquake response of asymmetric buildings

The results of a parametric study of torsional coupling effects in the response of asymmetric buildings to a grouped selection of 45 strong motion earthquakes from Europe, North America, the Middle East and Southern Pacific are presented. The period dependency of the key response parameters is studied in relation to the site dependent criteria employed by certain earthquake-resistant design codes for specifying the lateral shear forces to be resisted by the structural frames and/or walls. Unlike lateral forces, the torsional response is relatively insensitive to the ration of peak ground accelaration to velocity, which has been used in previous studies as a measure of the effect on earthquake ground motions of site soil conditions and epicentral distance. The results show that the effect of torsional coupling on edge displacement response is more pronounced in stiff, short period structures. However, the dynamic shear and torque responses are relatively insensitive to variations in structural period. Codified design provisions for torsional effects specified in the United States, Canadian and European seismic building regulations are assessed, along with alternative proposals, in relation to the analytical results. It is concluded that in some cases special provisions are needed for short period asymmetric systems, a feature which has been neglected by the codes and inadequately accounted for in previous proposals.     

一种简便实用的视频特技切换器

本文介绍了一种用集成电路制作的特技切换器，具有成本低，线路简单，易于制作的特点。可以完成简单，基本的扫换，键控，特技效果和快切等功能。     

Influence of low-frequency electromagnetic fields on living organisms

Recent research reports appear to indicate a real possibility that the low-frequency electromagnetic field produced by the power transmission and distribution network presents a health problem. A critical assessment of the available information is presented here. The state of knowledge, available evidence and conflicting reports indicate a definite need for interim action by the power industry. New direction for analytical research, possible interim avoidance measures, proper advice to clients and the public are discussed. Detailed mathematical modeling for the linear and nonlinear dynamics of DNA and the chromosome as a whole is suggested.     

掺杂染料的向列相液晶微粒材料的非线性光学研究

对布满液晶微粒的聚合物(PDLC)进行了简并四波混频及光学双稳态的研究,并在文中对相关的PDLC中的分子重取向和热效应的非线性光学效应进行了讨论.     

Microstructural Effects of Ion Implantation on Molybdenum

The effects of ion implantation and subsequent annealing on the microstructure of molybdenum have been investigated by transmission electron microscopy. The ions investigated were carbon, nitrogen, and tellurium. The ion-induced damage was found to give rise to grain boundary migration phenomena both during implantation and during subsequent annealing. Precipitation or ordering was found to occur for each ion on annealing.     

自发参量下转换光场的实验研究进展综述

自发参量下转换(spontaneous parametric down-conversion,SPDC)光场是基于单色泵浦光子流和量子真空噪声对非线性晶体的综合作用而产生的,它固有的量子起源决定了在非经典光场研究中的重要地位和作用.对SPDC光场的相干特性和它在绝对测量光电探测器量子效率中的应用进行了深入而细致的研究和探讨.     

Effects of luminance,wavelength and purity on the color attributes: Brief review with new data and perspectives

A color stimulus may be characterized by three psychophysical dimensions (luminance, dominant wavelength, and purity), whose corresponding color attributes are lightness, hue, and chroma/colorfulness. The 3 × 3 matrix gives nine basic effects of the psychophysical dimensions on the color attributes (e.g. the effect of luminance on hue), but there are 49 possible combinations as more complex effects (e.g. the effect of luminance on hue and chroma, i.e. on chromaticity). Researching and quantifying such effects enables modelling of the underlying neural mechanisms and of color appearance. Using a simple nomenclature to identify the effects (e.g. Ph denotes the effect of Purity on hue), this paper briefly reviews and interrelates 15 of the commonest effects, giving new data or new graphical perspectives to clarify or fill gaps in the literature. Contrast and no‐contrast effects (stimuli viewed simultaneously or singly, respectively) are differentiated. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 208–222, 2007     

CDMA时变色散信道的两级盲辨识算法

本文通过对时变信道的扩展函数在时频域进行正则采样，得到了CDMA时变系统的离散正则模型。针对该模型提出了一种具有较低运算量的两级盲辨识算法。为避免两级算法产生的误差传播效应，文章将理想SIMO模型等效为加性噪声模型来处理。与基展开模型方法相比，该算法具有不需利用观测数据的高阶统计量估计展开基频率的优点。文章通过仿真验证了该算法是可行的。     

干扰抵消型多用户检测器性能分析

用模块化的方法描述了 ＳＩＣ、ＭＳＳＩＣ、ＰＩＣ和ＰＳＩＣ干扰抵消多用户检测算法，给出算法的实现结构图，并且在渐近有效性、抗远近效应、系统容量和实现复杂度诸方面进行了性能比较分析。分析表明需要进行功率排序的ＭＳＳＩＣ、ＰＳＩＣ和ＳＩＣ算法比ＰＩＣ算法具有更好的抗远近效应的性能，ＭＳＳＩＣ和 ＰＳＩＣ算法在渐近有效性和系统容量方面要显著强于ＳＩＣ和ＰＩＣ算法。     

非晶软磁合金的巨磁阻抗效应及应用

近来在ＦｅＣｏＳｉＢ等Ｃｏ基非晶体丝带中现了巨磁阻抗效应，由于在一小的直流纵向偏置场下该效应能使丝带两端的交流电压发生大而灵敏的变化，因而在磁记录头和传顺技术中具有巨大的应用科学潜能，受到各国学者的关注，本文简单介绍了巨磁阻抗效应的来源，并综述了近年来非晶体软磁合金材料的的巨磁阻抗效应及应用的研究进展，文章最后说明了尚待深入解决的问题。