手写体字符识别方法的探讨

手写体字符识别的一项重要应用是在邮政自动化系统中自动识别邮区编码.本文扼要介绍了应用于我国邮电部信函自动分拣系统中的手写体数字识别机,并对于识别顺序逻辑的设计方法问题进行分析.试图利用有限状态文法推断的一些结果来设计识别顺序逻辑,并考虑用不分明集(模糊集)的一些概念来进行信息压缩.     

应用静压桩技术补强加固沉管灌注桩的工程实践

介绍了某商住楼桩基工程中应用静压桩技术补强加固沉管灌注桩的设计原理和施工要点 ,以及补强加固的效果     

Application of wilsonés equation to determination of vapor-liquid equilibrium data and heats of mixing for non-ideal solutions

A calculation technique, starting from total pressure data of binary systems and utilizing Wilsonés equation was developed, leading to isothermal vapor liquid equilibrium data for binary and ternary systems. Heats of mixing for ternary systems were also calculated from binary data.     

The effect of pre-stress cycles on fatigue crack growth—an analysis of crack growth mechanism

Cyclic pre-stress increases subsequent fatigue crack growth rate in 2024-T351 aluminum alloy. This increase in growth rate, caused by the pre-stress, and the increased rate, caused by temper embrittlement as observed by Ritchie and Knott, cannot be explained by the crack tip blunting model alone. Each fatigue crack increment consists of two components, a brittle and a ductile component. They are respectively controlled by the ductility of the material and its cyclic yield strength.     

Cylindrical ground-clutter shield

A theoretical investigation of the influence of metal shields on antenna radiation patterns is performed. This study allows us to determine the proper dimensions of a circular cylindrical finite perfectly conducting shield placed on the ground around infinitesimal sources located at its axis, in order to reduce the ground-side lobe. Two different methods are applied in this study: 1) integral equation method (IE) and 2) geometrical theory of diffraction (GTD). When the dimensions of the cylindrical shield become very large compared to the wavelength, the first method involves a very large matrix that is impractical for the present computers to handle. Under these circumstances, GTD may be shown to be a very useful approach. For the range of dimensions where both methods are applicable, a comparison between them is made.     

Radiation from sources in the presence of a flat earth

The authors call attention to the equivalence between Sommerfeld's formulation for an oscillating dipole and the result based on the dyadic Green function technique. The complication resulting from the use of the set of the longitudinal vector wave functions in formulating electromagnetic problems is also pointed out     

Some properties of the gain of uniform and nonuniform arrays

Some characteristics of the directivity function of uniformly spaced and nonuniformly spaced arrays are presented. In particular, the lower bound of the directivity function and the asymptotic expansion for the directivity of some composite arrays are examined.     

Ultrasonic Blood Flow Spectral Analysis Using Coherent Optics

It has been shown that ultrasonic Doppler signals can be obtained easily and transcutaneously from many blood vessels in both normal and atherosclerotic subjects. The Doppler spectrum changes with time, giving rise toa distnbution of frequencies whose envelope has a waveform that is characteristic of the vessel site and closely folows the events of the cardiac cycle. This makes it very useful in diagnosing lesions of the arterial system. The paper presents a coherent optical technique for displaying and analyzing a blood-flow-generated ultrasonic Doppler spectrum. The system is highly cost-effective and produces spectrograms on-line. Other advantages include a large, continuously variable bandwidth, an instantaneous display of velocity profile, and simultaneous display of temporal spectra. The system makes use of the Fourier transformation property of converging lens and its use of processing time signals. The spectrum obtained from the brachial artery of a normal subject compares favorably with the spectrograms obtained using electronic spectrum analyzers.