Optimal approximation of high-order systems subject to polynomial inputs

In this paper the optimal approximation of a high-order system, subject to polynomial inputs, is investigated.

It is shown that the constraints on the asymptotic behaviour are easily taken into account as structure constraints. Thus the problem is reduced to a minimization without constraint. Expressions for the gradient of the criterion are then given in the case of a unit step response.

An extension to the case of unstable systems is also proposed.     

Radiation-Induced Defects and Structure of Barium Silicate Glasses

The effect of increasing BaO on the intensity and position of absorption bands induced in barium silicate glasses was studied. Many of these glasses showed a two-step process in the growth and thermal bleaching curves. This process was attributed to two types of defects in the glass, induced and intrinsic. Infrared absorption, molar volume, and X-ray diffraction studies predicted structural changes at compositions containing about 22.5 and 27.5 mole % BaO. The results of gamma-induced absorption were in Une with these predictions, supporting the view that color center studies can be used to detect changes in structure, especially when high radiation doses are applied.     

基于类别分布差异和特征熵的维吾尔语文本特征选择

文本特征选择是在文本自动分类中最重要的一个环节。为了更好地解决维吾尔文文本分类中特征空间的高维性和文档表示向量的稀疏性问题, 提出一种基于特征的类别分布差异和信息熵的维吾尔文文本特征选择方法。该方法不仅要考虑特征在类别间的分布情况, 而且也要考虑特征在类别内的分布情况。采用本方法对维吾尔文文本语料进行了分类实验, 并与一些传统的特征选择方法进行了比较。从结果来看, 本方法在所选特征数更少的情况下, 达到了比其他方法更高的分类MacroF1值853%, 比传统的IG和CHI等方法在MacroF1值上分别高出了43%和61%。     

“突厥语大词典”电子词典的设计与实现

介绍了11世纪中国突厥语言学著作"突厥语大词典"的电子词典软件的设计与实现。突厥语大辞典的电子版是突厥语大辞典的维、土、汉、英版本的基础上研究了多语种(维吾尔语、土耳其语、汉语、英语)突厥语大辞典电子版的构建技术。实现了具有通过原词或原词在以上四种不同语言中的词义来快速查找的功能。详细介绍了本词典的总体结构、功能、数据库设计、查找算法、系统运行机制。最后提出了进一步增强、改进系统的一些设想。     

Polymorphic Behavior of Thin Evaporated Films of Zirconium and Hafnium Oxides

Polymorphism in thin evaporated films of zirconium and hafnium oxides was investigated from 100° to 1500°C by electron diffraction and transmission electron microscopy. The films have metastable cubic structures at room temperature and at moderate temperatures. Zirconium oxide, depending on temperature, exists in cubic, tetragonal, and monoclinic forms, whereas hafnium oxide transforms directly from the cubic to the monoclinic structure. The transformation temperatures depend on the oxygen partial pressure. Air annealing of thin films of ZrO₂ and HfO₂ lowered the temperature of transformation of the tetragonal and the cubic structure into the monoclinic structure by about 150° and 100°C, respectively. The cubic/tetragonal transformation of ZrO₂ is monotropic, whereas the tetragonal monoclinic transformation occurs by the typical nucleation and growth mechanism. Determination of grain size in ZrO₂ at the tetragonal/monoclinic transformation temperature showed that the transformation occurs when a constant grain size of about 800 Å is reached. The oxygen partial pressure, grain size, and temperatures at which the metastable phases exist were correlated. The rate of grain growth is enhanced by increase in oxygen partial pressure. The accelerated transformation in air is attributed to rapid attainment of the critical size; grain boundary energy is an important controlling factor in transformation.     

Some general experimental studies on charge-coupled device circuits†

The first part, of the paper includes the derivation of a lump model for the basic CCD unit. This model consists of two capacitors, a current generator and a switch. Experimental results are given for the justification of this model.

In the second part of the paper a report is given on the successful operation of silicon gate CCD shift registers, two-phase and three-phase.

The last part presents photosensitivity results of CCD silicon gate shift registers operated as imaging arrays. The noise equivalent power (NEP) was 2 × 10^?8 W/cm² at a wavelength of 0·7 μm. Relative output as a function of integration time is also given.     

Pr1-xSrxMnO3体系中O2P空穴参与的 O1s近边吸收谱

对于Pr1-xSrxMnO3体系x=0和0．3以及MnO2在0K边进行了X射线吸收谱实验研究。在X=0的PrMnO3端点化合物进行空穴掺杂使x=0．3,当体系成为Pr0.7Sr0．3MnO3时,实验结果显示其在Mn3d轨道上的电子数目并不随空穴掺杂减少,反而有增加的趋势。对该结果基于O2p与Mn3d轨道的杂化和共价键特性进行了探讨。     

Bit-level pipelined digit-serial multiplier

A new cell architecture for high performance digit-serial computation is presented. The design of this cell is based on the feed forward of the carry digit, which allows a high level of pipelining to increase the throughput rate with minimum latency. This will give designers greater flexibility in finding the best trade-off between hardware cost and throughput rate. A twin-pipe architecture to double the throughput rate of digit-serial/parallel multipliers is also presented. The effects of the number of pipelining levels and the twin architecture on the throughput rate and hardware cost are presented. A two's complement digit-serial/parallel multiplier which can operate on both negative and positive numbers is also presented.     

A two-dimensional problem for a fibre-reinforced anisotropic thermoelastic half-space with energy dissipation

The theory of thermoelasticity with energy dissipation is employed to study plane waves in a fibre-reinforced anisotropic thermoelastic half-space. We apply a thermal shock on the surface of the half-space which is taken to be traction free. The problem is solved numerically using a finite element method. Moreover, the numerical solutions of the non-dimensional governing partial differential equations of the problem are shown graphically. Comparisons are made with the results predicted by Green–Naghdi theory of the two types (GNII without energy dissipation) and (GNIII with energy dissipation). We found that the reinforcement has great effect on the distribution of field quantities. Results carried out in this paper can be used to design various fibre-reinforced anisotropic thermoelastic elements under thermal load to meet special engineering requirements.