Effect of TiB2 and Boron Additions on the Stability of Wurtzite-Type Boron Nitride at High Temperatures and Pressures

Shock-synthesized wurtzite-type BN(w-BN) and mixtures of w-BN–TiB₂ and w-BN–ß were treated at high temperatures and pressures. The effect of TiB₂ and boron additions on the transformation of w-BN to zinc blende-type BN(z-BN) was studied at 1000° to 2200°C and 55 to 68 kbars. The formation region of z-BN was shifted toward higher temperatures by TiB₂ additions and toward lower temperatures by boron additions.     

FeOT-CaO-SiO2-Al2O3渣系中铅及其氯化物蒸汽压测定

利用Knudsen喷射法测试FeOT?CaO?SiO2?Al2O3渣系中铅及其氯化物的蒸汽压。结果显示该复杂体系中铅及其氯化物的蒸汽压随温度升高而升高。对于不含氯元素的渣系,铅的挥发气体种类为PbO 和金属Pb。二者蒸汽压的对数(lnp)与温度的倒数(1/T)之间呈良好的线性关系。金属 Pb 蒸汽形成比例越高,总的蒸汽压越高。铅的蒸汽压随FeOT?CaO?SiO2?Al2O3渣系碱度的升高、随FeO含量及w(Fe2+)/w(Fe3+)比例的升高而升高。对于含有Cl元素的渣系,铅的挥发气体种类为PbCl2和PbCl,二者总的蒸汽压随渣碱度及FeO含量的降低而升高。     

Switched-capacitor discrete Fourier analyser with window function circuit

An analogue window function circuit is realized by using switched-capacitor techniques. In order to verify the effect of this window, a novel switched-capacitor analogue discrete Fourier analyser is proposed. The window function circuit is included in this analyser as the ratios of capacitances. This switched-capacitor discrete Fourier analyser is very simple in construction, namely, only two elemental circuits based on the integral feedback capacitance circuit are connected in series. Agreement between the experimental and the theoretical values is confirmed.     

Influence of sub-micrometer notches on the fracture of single crystal silicon thin films

The influence of notches on the fracture of single crystal silicon thin films was investigated. The tests were conducted on notched and smooth tensile specimens micromachined on a silicon wafer. The specimen geometry was 100 μm long, 50 μm wide and 5 μm thick. For the notched specimen, a V‐shaped sub‐micrometer notch was introduced on one edge of it by using a focused ion beam (FIB) process. The notch lengths ranged from 0.07 to 1.3 μm. Four types of specimens with different surfaces and tensile orientations were tested. The smooth specimens showed scattered fracture strengths and ‘collapsed’ fractures. For the restrictive‐shaped notches, the critical length was 0.5 μm. The short‐notched (<0.5 μm) specimens also showed ‘collapsed’ fractures, and the stress concentrations on notch tips decreased their fracture strengths. For the long‐notched (>0.5 μm) specimens, the notch was equivalent to a crack in the Griffith model and the crack mainly propagated on {111} cleaved planes.     

Fast method of interpolation for frequency estimation of sinusoidal and spindle data

Estimating the frequency of one or more sinusoidal waves is a problem belonging to the field of signal analysis. The frequency characteristics of sinusoidal waves can be measured by peaks or troughs of the waves. Because of (he limit of the sampling frequency, the peaks or troughs of sinusoidal and EEG waves in the sampling usually deviate from their original ones in the time domain. Starting from a sinusoidal wave analysis, we present a correction formula with which the deviation time t_d can be calculated so as to detect the position of the real peak or trough of the data as fast and as accurately as possible on the time axis. The wave of the sleep spindle in the EEG can be considered as an asymmetrical sinusoid. Then after the waves have been filtered, the formula can also be applied to analyse the spindle of EEG waves and it is shown to be useful in the measurement of the frequency of the spindle wave. Error analysis and practical examples are presented.     

黏滞阻尼器的优化布置及其在高层钢结构加固中的应用

阻尼器优化布置是结构减震设计过程中的重要环节,通常需要通过多次动力响应计算来完成。为此,提出了一种通过结构静力分析确定阻尼器合理布置位置的方法,并能够快速计算出优化方案的附加阻尼比。将该方法应用于一栋位于日本东京都新宿区29层钢结构建筑的减震加固设计中,分析了该建筑的强震观测系统在日本“311地震”中采集到的部分楼层加速度时程数据,并基于分析结果验证了所建立的非线性数值分析模型的可靠性。采用所提方法对结构进行减震加固,得到双向共64个阻尼器的优化布置方案及其附加阻尼比,并通过动力方法对结果进行了验证。同时针对长周期及长持时特性的地震波,对减震结构进行动力弹塑性时程分析,评估其抗震性能。分析结果表明：减震优化方案的减震效果明显,结构整体地震反应和构件损伤较非减震方案都大大减小;减震优化方案有效改善了高层钢结构楼层变形不均匀的情况,层间位移角均满足小于1/100的性能要求;通过减震优化后大部分钢支撑和钢梁的塑性率都降低至小于1。     

IDENTIFICATION OF NON-PROPORTIONAL MODAL DAMPING MATRIX AND REAL NORMAL MODES

Equations of motion for non-proportionally damped structures cannot be decoupled by using the real normal modes. For such structures, the complex normal modes are in common use for this purpose, but for the validation of finite element mass and stiffness matrices where physical damping matrices are not available, the related experimental real normal modes must be known. In previous publications, an identification theory using the real normal modes and the non-diagonal modal damping matrix for the non-proportionally damped system and some applications with the computer code ISSPA were presented. However, the theory cannot assure the symmetry of the identified modal damping matrix, which must be theoretically symmetric. In this paper, a method for identifying the symmetric non-proportional modal damping matrix using undamped modal parameters obtained from ISSPA is presented and the validity of the method is demon-strated through both numerical and experimental examples.     

α-松油烯为原料的单萜衍生物合成及其构造解析

把α-松油烯与马来酸酐的分子间Diels-Alder环加成反应产物1-甲基-4-（1-甲基乙基）-双环[2．2．2]-5-辛烯-2,3-二酸酐（1）,在甲醇溶剂中,用Raney Ni为催化剂进行加氢,获得了加氢产物1-甲基-4-（1-甲基乙基）-双环[2．2．2]辛烷-2,3-二酸酐（2）,然后,对化合物1和2分别进行加水分解反应获得了二羧酸化合物1-甲基-4-（1-甲基乙基）-双环[2．2.2]-5-辛烯-2,3-二羧酸（3）和-个新化合物1-甲基-4-（1-甲基乙基）-双环[2．2．2]辛烷-2,3-二羧酸（4）。用^1HNMR（^1H-^1H Cosy）以及^13CNMR（DEPT,HMQC,HMBC,NNE,INADEQUATE）高分解能核磁共振测定手法对化合物1～4进行了详细的解析和化学位鹈的归属．     

Dietary Flavonoids as Potential Natural Biological Response Modifiers Affecting the Autoimmune System

In vitro anti-complement activity of 19 phenolic compounds was evaluated in the classical pathway. Two flavonoids, epigallocatechin gallate and myricetin, exhibited marked anti-complement activities with IC₅₀ values of 4.2 and 5.2 μg/mL (concentration causing 50% inhibition of complement activity), respectively. The two flavonoids appeared to interact with both antibody-sensitized erythrocytes and complement components to inhibit the cascade reactions in the classical pathway of the complement system. The flavonoids may function as natural biological response modifiers by multiple mechanisms including anticomplement effects. Dietary flavonoids may thus affect the body's autoimmune system.     

Recent collaborative researches between Japanese universities and steel industry on the iron ore agglomeration process

The properties of iron ores used in ironmaking process have been drastically changed in the past couple of decades.Especially,the change has become significant in the last few years because of the considerable increase in the world steel production.The property change of the iron ore is mainly caused by the depletion of the hard and high-grade lump hematite ores.It has led to the increasing use of ores containing a larger amount of goethite/limonite,i.e.,hydro-oxides of iron.Typically,the proportion of p...