分形维数与城市规模分布评析

本在分形概念的基础上，指出城市规模分布是基于统计意义上的一种分形分布，并计算了安徽省1978～1998年城市规模分布的分维值，评析了安徽省城市规模分布变化的特征。     

关于居住小区若干问题探讨

通过对我国居住小区的模式、规模、结构、布局等现存问题的分析,提出了一些针对性的建议。     

结构可靠性设计中尺寸变差系数的确定方法

提出了在结构可靠性设计中,根据现有加工条件和设计要求确定几何尺寸变差系数的思想,并给出了当已知精度等级时,直接加工尺寸和组合尺寸变差系数的计算方法和程序。采用该方法使可靠性设计更切合实际。     

Pb-Sn-Bi三元系α相固溶体的点阵参数

应用X射线衍射法测定了Pb-Sn-Bi三元系Pb基α相固溶体的点阵参数,发现点阵间距与成分呈线性变化,对两批实验数据分别进行回归分析,得到点阵参数-浓度关系的统一解析式: α=0.49495X_(Pb)+0.47813X_(Sn)+0.50629X_(Bi)。其F检验置信度大于99.9％,残余标准差σ=6.4×10~(-5) nm,分析点阵畸变的影响因素表明尺寸效应是控制固溶体点阵行为的主要因素。     

Particle Size Analysis by Transmission Fluctuation Spectrometry: Experimental Results Obtained with a Gaussian Beam and Analog Signal Processing

Transmission fluctuation spectrometry (TFS) is a method for the analysis of particle size distributions based on the statistical fluctuations of a transmission signal. Complete information on the PSD and particle concentration can be retrieved by a special transformation of the transmission signal, whereby the expectancy of the transmission square (ETS) is determined after the signal has been subjected to a procedure of spatial and temporal averaging. By varying the averaging parameters over a wide range, a spectrum of ETSs is obtained and introduced into a linear equation system, which yields the PSD. In the experimental realization presented here, variable temporal averaging is realized in the frequency domain with a series of low pass filters at different cutoff frequencies while spatial averaging inevitably occurs as the particles pass through a focused Gaussian beam of finite cross section. Experimental results on spherical particles (glass beads) and non‐spherical particles (SiC) are presented. The PSDs are resolved in 30 intervals within a particle size range from 1–1000 μm, employing a modified Chahine inversion algorithm. So far, the measurements are limited to moderate particle concentrations. Some influences affecting the measurements, especially for higher particle concentrations, are discussed in detail.     

步进电机细分技术在经济型数控机床中的应用

本文叙述了步进电机细分原理及微机控制系统，并将其应用于经济型数控铣床的横向进给伺服系统，有效提高了开环数控系统的定位精度。     

Size dependence of self-diffusion in the hard-square lattice gas

A striking size dependence of the mean-square displacement of diffusing particles in the two-dimensional lattice gas of hard squares has been observed by Monte Carlo simulation. It is shown that the size effect is due to the formation of a stable cage structure in small lattices when the particle concentration is high. The formation of cages is governed by a new type of percolation problem related to bootstrap percolation.     

经编针织运动服装的织物性能研究

从人体穿着舒适性能考虑,织物的热湿舒适性越来越成为人们重视的服用性能.本文针对功能性的针织运动服的原料选用和织物组织结构,分析其导湿性.     

Full-Wave Analyses for a Multi-Layered Microstrip Patch Antenna

This paper describes numerical modelling of a dual band multi-layered microstrip patch antenna operating at 35GHz on an in-house semi-insulating GaAs substrate. The simulated and measured resonant frequencies at both lower and upper resonant frequencies will be compared to check the accuracy of the different numerical modelling techniques.