圆环面螺旋线的计算机绘图

本文论讨了圆环面螺旋线的形成及其四个要素．推导了该螺旋线的参数方程．并给出了计算机绘图方法．     

采用"结式法"的圆环面和球面求交算法

提出了一种不需跟踪的求交算法.通过坐标变换使圆环中心轴与球心共处在XOZ平面内,然后讨论该平面内圆环面小圆和球面截圆的位置关系,给出了圆环面和球面不相交、交线为一个或两个圆、有孤立交点的几何条件以及交线的区间.最后,将圆环面和球面求交转化为平行于XOY面的平面内的两圆交点的问题并利用"结式法"解得交点.     

AutoCAD中圆环螺旋面的形成与绘图

根据圆柱螺旋线理论,分析了形成圆环螺旋线的要素,并运用解析几何方法建立了圆环螺旋线的参数方程.基于圆柱螺旋面和圆环螺旋线的形成原理,构建了圆环直纹螺旋面的数学模型,讨论了圆环直纹螺旋面的两种表示方法.在AutoCAD环境下,用VisualLisp语言编程,绘制了圆环螺旋线的投影图和三维立体图,并给出了圆环正螺旋面和斜螺旋面的三维CAD造型方法.     

Nanoporous gallium nitride square microtubes

Porous gallium nitride microtubes were self-fabricated from gallium nitride submicron irregular structures. The microtubes were of square cross-section. Electron diffractions indicated that the microtubes were composed of zincblende gallium nitride. Electron energy-loss spectrum and photoluminescence spectrum of the microtubes were collected and compared with that of single crystals.     

Demagnetizing factors for square bars

Using a finite-element method, we have calculated fluxmetric and magnetometric demagnetizing factors N/sub f/ and N/sub m/ for square cross-section bars as functions of susceptibility /spl chi/ and length-to-width ratio c/a over the range /spl chi/=-1 to /spl infin/ and c/a=0.01 to 100. We present the results in figures and tables and compare them with those for cylinders. We give an approximate conjugate relation for N/sub m/(/spl chi/) of a cube.     

Vortex States of a Three-Dimensional Mesoscopic Superconducting Torus in an External Magnetic Field

The time-dependent Ginzburg–Landau equations have been solved numerically by the finite-element method for a three-dimensional mesoscopic superconducting torus. We obtain the different vortex patterns as a function of the applied field perpendicular to its surface. And we find that multivortex states are ground state in a three-dimensional mesoscopic torus. These results show that our approach is effective and useful to interpret experimental data on vortex states in mesoscopic superconductors.     

圆环钎焊蜂窝结构超声C扫描检测及其系统研制

利用直接数字成像和程控采样扫描技术，研制成了圆环蜂窝构件超声Ｃ扫描检测系统，精确地将蜂窝构件检测结果分析处理后直接显示在微机终端屏幕。     

移动最小二乘支持向量机

基于移动最小二乘逐点逼近思想,移动权被引入到最小二乘支持向量机的误差变量中,得到新算法的模型.此外,证明了用移动最小二乘支持向量机作函数估计与在特征空间中用移动最小二乘法得到的解是一致的,揭示了移动最小二乘支持向量机所选择的核函数相当于移动最小二乘法所选择基函数组.数值试验与实例进一步验证所提出方法的优越性.     

Dynamic axial crushing of square tubes

Eighty-four dynamic tests on thin-walled square steel tubes having two different cross-sections with c/h = 30.25 and c/h = 32.18 and various lengths were crushed axially on a drop hammer rig. Approximate theoretical predictions were developed for the axial progressive crushing of square box columns using a kinematically admissible method of analysis. This theoretical study predicts four deformation modes which govern the behaviour for different ranges of the parameter c/h. New asymmetric deformation modes were predicted theoretically and confirmed in the experimental tests. These asymmetric modes cause an inclination of a column which could lead to collapse in the sense of Euler even for relatively short columns. The effective crushing distance is considered in the approximate theoretical analysis together with the influence of material strain rate sensitivity, which is important for steel even when the loadings are quasi-static. The simple equations presented herein for the design of axially crushed spuare box columns give reasonable agreement with the corresponding experimental results.     

方块电阻测试仪的智能化方案

提出对便携式方块电阻测试仪的内部功能进行智能化的必要性和实验方案,包括:电源的动态监测;探针通路的检测;防止探针击穿样品;智能A/D转换;自动量程转换;数字通讯等.由硬件和软件配合达到智能化的目的.     

An approach to improve conventional square ferrocement jacket for strengthening application of short square RC column

The confinement effect over the cross-section of a square column is non-uniform compared to the same of a circular column. Concentration of stresses and subsequent cracking in the confining external jacket occurs at the corners of a square column; and thus the effectiveness of external jacket in such column is reduced significantly. The conventional square ferrocement jacket consists of rich mix cement mortar with single or multiple layers of wire mesh. This type of external jacket also experience similar problems in confining core columns. This study aims to develop efficient techniques to overcome the drawbacks of conventional square ferrocement jackets in strengthening of short square-shaped RC columns. Three techniques and variations in those techniques are proposed to address the problem. Experimental studies of selected variation from each technique affirm the effectiveness of the proposed techniques in addressing the problem associated with conventional square ferrocement jackets. The experimental investigation reveals that all the retrofitted square ferrocement-jacketed short columns exhibit higher load carrying and deflection capacities before failure compared with non-jacketed as well as conventional square ferrocement-jacketed columns. The findings indicated that the proposed techniques are efficacious to address the problem of conventional square ferrocement jacket.     

Ronchi test with a square grid

We use a square grid in the Ronchi test. This grid allows processing of both the X and the Y directions when calculating optical path difference. We use trapezoidal integration to analyze the new patterns, since it does not have the smoothing drawback at the edges of the wave front.     

Performance of submillimeter square hollow waveguides

Propagation losses are determined for 100 microm x 100 microm square, hollow waveguides constructed from glass capillaries. The small size makes it possible to observe optical effects not easily seen with larger waveguides. The depletion of higher-order even modes creates a large, nonlinear loss. Over a distance of a meter the loss approaches the smaller, linear value expected for the fundamental mode. Additionally, the lowest two even modes beat to produce an oscillatory loss with a period of approximately 2 cm. Making the focal radius 0.35 the waveguide width minimizes these two effects. In a related study, 50-microm waveguides embossed in polydimethylsiloxane are shown to have losses similar to glass capillaries.     

Subsurface resistivity measurements using square waveforms

This work analyzes the effect of inductive and capacitive coupling between the injecting circuit and the detecting circuit in resistive field surveys. Theoretical and experimental results demonstrate that if a square waveform is injected into the soil, and synchronous sampling is used to sample at the flat zone of the detected voltage, then the effect of the interference is greatly reduced. Furthermore, square waveforms are easier to generate than sinusoidal waveforms, so they offer a new approach to subsurface resistivity measurements     

Self-tuned programmable active-R square wave generator

Self-tuning of a digitally programmable active-R square wave generator is investigated. A single-chip-mode microprocessor is used as a microcontroller. The microcontroller continuously monitors and automatically corrects the shift in the output frequency that may be caused by temperature drift, component mismatch, aging, and/or any other environmental changes