非对称荷载下疲劳强度临界值的统一公式

本文对非对称荷载下的疲劳强度临界值预测公式和疲劳寿命预测公式进行了系统深 入的研究,分析了著名的Ｇｏｏｄｍａｎ公式,Ｓｏｄｅｒｂｅｒｇ公式和Ｇｅｒｂｅｒ公式的适用条件,建立了 一种新的疲劳强度临界值预测公式和疲劳寿命预测公式。新公式的最大优点是,对实际破坏 面的形状不做任何限制,并可使用任意疲劳寿命实验数据进行拟合。     

船用核反应堆提棒外推临界优化研究

因稳定时间受限，传统的倍增公式导出的外推临界公式计算结果大于实测值，偏危险；文中根据新的中子倍增公式导出了外推临界计算的新公式，实例计算表明，该公式比传统的外推临界公式精确且偏安全．     

Performance of a color-difference formula based on OSA-UCS space using small-medium color differences

An investigation of the color metrics and the complexity of the CIEDE2000 formula shows that CIELAB space is inadequate to represent small-medium color differences. The OSA-UCS (Uniform Color Space) Committee has shown that no space with uniform scale for large color differences exists. Therefore the practical way for color-difference specification is a color-difference formula in a nonuniform space. First, the BFD (Bradford University) ellipses are considered in the OSA-UCS space, and their very high regularity suggests a new and very simple color-difference formula at constant luminance. Then the COM (combined) data set used for the development of the CIEDE2000 formula is considered in the OSA-UCS space, and the color-difference formula is extended to sample pairs with a different luminance factor. The value of the performance factor PF/3 for the proposed OSA-UCS-based formula shows that the formula performs like the more complex CIEDE2000 formula for small-medium color differences.     

Analysis of methods for determining electromechanical couplingcoefficients of piezoelectric elements

An important characteristic of piezoelectric elements as energy converters is the energy conversion efficiency. The electromechanical coupling coefficient (EMCC) is commonly used as a measure of a piezoelectric elements' efficiency. The latest Standard on Piezoelectric recommends that EMCC be determined by the use of the Berlincourt et al. formula for a uniform electroelastic state, and the dynamic formula by Mason for near resonance frequencies. This paper is devoted to the analysis of these two formulas along with a third formula. The EMCC of commonly seen piezoelectric elements are formulated and analyzed. The comparison of the numerical results leads us to the following conclusions: 1. The formula of Berlincourt et al. is valid only for a uniform electroelastic state, 2. The dynamic formula of Mason gives the EMCC at a frequency equal to the arithmetic mean of resonance and the corresponding antiresonance frequencies, 3. The third formula for the EMCC is valid for both the static and dynamic electroelastic state of a piezoelement, and its results are in good agreement with those found by using Berlincourt's formula and the dynamic formula of Mason     

钢筋混凝土剪扭构件承载力可靠度分析

对GB50010-2002《混凝土结构设计规范》(以下简称“规范”)剪扭构件承载力计算公式以及黄靓建议的公式进行了可靠度对比分析。结果表明,对于安全等级为二级的剪扭构件,当发生脆性的剪型破坏时,规范公式的受剪可靠指标和受扭可靠指标均值分别为3.23 和3.25,不能满足GB50068-2001《建筑结构可靠度设计统一标准》(以下简称《统一标准》)3.7 的要求;当发生延性的扭型破坏时,规范公式的受剪可靠指标和受扭可靠指标分别为4.02 和2.88,亦不能满足3.2 的可靠指标要求;随着扭剪比的变化,规范公式的可靠指标变化幅度较大,受扭和受剪可靠指标之间相差较大,出现不平衡现象。黄靓建议的公式的可靠指标比规范公式高,对于两种破坏类型,可靠指标都在3.6 附近,并克服了规范公式可靠指标不平衡的缺点,但对于剪型破坏亦不满足《统一标准》3.7 的可靠指标要求。对此,该文把黄靓等人的直线模型再次缩进,提出钢筋混凝土剪扭构件修正公式并作了可靠度分析,结果表明该文修正公式的可靠指标均值在3.75 附近,能满足《统一标准》的要求。     

爆破飞石飞散距离计算公式浅析

爆破飞石是造成大量工程事故的五大爆破危害之一,其飞散距离的估算存在较大难度,主要是因为确定爆破飞石飞散距离的因素很多。本文查阅了大量相关资料,总结得出了计算爆破飞石飞散距离的经验公式、统计规律公式、弹道公式和其他公式。从使用情况来看,几何相似公式的使用次数最多,但是该公式的系数K1的选取存在较大差异,取值范围大多为1~2;而该系数对计算结果有直接影响,需要广大爆破工作者进行相应的试验来细化K1的取值。     

Comparative Analysis of Different Air Density Equations

In general mass measurements are carried out in air and that’s why air buoyancy correction plays a major role in mass measurements and it is totally dependent on density of air of the laboratory during the measurement. The density of air is calculated from temperature, relative humidity, air pressure, concentration of CO₂ monitored (for CIPM formula only) in the laboratory rather direct determination and for calculation of density of air, CIPM-2007 formula is recognized as most accurate formula. Since CIPM formula is very complicated formula and it is not required for less accurate measurements, different National Metrology Institutes have derived simple equations to calculate air density and those are known as approximation formulas. We had gone through a comparative analysis among different formulas of density of air to evaluate which approximation formula is most accurate compare to CIPM-2007 formula.     

鲍列斯柯夫公式在深孔爆破中的应用

分析了常用深孔爆破底盘抵抗线计算公式.对鲍列斯柯夫条形装药药量计算公式进行了合理的调整变形.建立了计算深孔爆破底盘抵抗线的公式,并在工程实践中进行检验,证明该公式准确明了,便于实际运用.另外,还叙述了鲍氏公式在校核深孔爆破飞石安全方面的运用.     

Precise recursive formula for calculating spot size in optical waveguides and accurate evaluation of splice loss

The spot size of a single-mode waveguide was defined from the viewpoint of a least-squares fit of the field profile to a Gaussian profile. The field profile was expanded in terms of Hermite-Gaussian functions, and a new precise recursive formula for calculating the spot size was derived. It was shown that our formula is equivalent to the best fitting of the offset coupling loss to that of a Gaussian profile and keeps its form against the Fourier transform that corresponds to the diffraction in the same manner as the Gaussian profile. The accuracy of conventional formulas and our new spot-size formula was compared with the exact value defined from the viewpoint of a least-squares fit to a Gaussian profile, and it was shown that our recursive formula is the most accurate of the approximate formulas. Next we proposed a new formula for calculating the splice loss between two waveguides and showed that our formula is more accurate than the conventional one, which involves only the spot size.     

线图法预测疲劳寿命的改进

线图法预测工程的疲劳寿命简单，方便。在已有预测公式的基础上，提出了预测低应力高周疲劳寿命的新公式，并进行了严密的公式推导，对一实例进行了计算并进行了验证，给出了新旧公式的预测结果，并进行了比较。     

谐振弦式传感器理论公式修正方法及应用

在简要导出谐振弦式传感器理论公式的基础上，阐述了修正理由，给出了修正公式，实例计算表明，修正公式能显著提高计算精度，最后，利用修正公式对所研制的５０ＭＰａ谐振弦式压力传感器的标定数据进行了处理，给出了相对计算误差。     

平面多边形Newell公式的运用与推广

Newell公式在计算机图形学中常被用于计算多边形面积和平面法向量。论文主要讨论了Newell公式的运用与推广。首先将其推广三维空间中用于计算多面体体积的公式。其次讨论了在异面多边形的情况下,Newell公式的几何意义。最后,从数值计算的角度分析了Newell公式的计算方法。     

混凝土初始损伤对爆炸压碎区尺寸影响分析

在已有经验公式的分析基础上,考虑钻孔或侵彻对炮孔产生损伤的影响,引入一个无量纲的参数,提出预估混凝土介质中爆炸压碎区半径的经验公式,通过文献实验对经验公式参数进行拟合,并由文献提供的全尺寸实验对提出的公式进行验证。分析比较表明,本文提出的公式预估与实验符合较好。     

传统压痕法识别陶瓷材料断裂韧性的有效性研究

基于虚拟裂纹闭合法对传统压痕法测试陶瓷材料断裂韧性的数值模型进行计算,以此为基础,分析比较传统压痕法的几种典型公式识别陶瓷材料断裂韧性的测试误差和所测材料的适用范围。结果表明:传统压痕法的Anstis公式较Evans公式,Lawn公式,JISR公式和Niihara公式,在材料比功0.3≤We/Wt≤0.45时所测断裂韧性值与理论计算值较为接近,其最大误差为12.9%,测试结果相对准确;当0.45We/Wt≤0.7时,传统压痕法对陶瓷材料断裂韧性的测试误差随比功增加迅速增大,特别是当We/Wt=0.7时,Anstis公式,Evans公式,Lawn公式,JISR公式和Niihara公式所测断裂韧性值与理论计算值的最大误差分别为70%,148.5%,48.8%,98.7%和166.6%,在此材料比功范围内传统压痕法所测断裂韧性值误差较大。     

混凝土初始损伤对爆炸压碎区尺寸影响分析

在已有经验公式的分析基础上,考虑钻孔或侵彻对炮孔产生损伤的影响,引入一个无量纲的参数,提出预估混凝土介质中爆炸压碎区半径的经验公式,通过文献实验对经验公式参数进行拟合,并由文献提供的全尺寸实验对提出的公式进行验证。分析比较表明,本文提出的公式预估与实验符合较好。     

爆破飞石飞散距离计算公式浅析

爆破飞石是造成大量工程事故的五大爆破危害之一,其飞散距离的估算存在较大难度,主要是因为确定爆破飞石飞散距离的因素很多。本文查阅了大量相关资料,总结得出了计算爆破飞石飞散距离的经验公式、统计规律公式、弹道公式和其他公式。从使用情况来看,几何相似公式的使用次数最多,但是该公式的系数K1的选取存在较大差异,取值范围大多为1²;而该系数对计算结果有直接影响,需要广大爆破工作者进行相应的试验来细化K1的取值。     

空气间隔装药预裂爆破空气比经验公式分析

鉴于空气间隔装药预裂爆破合理空气比理论公式的复杂性,不便于推广应用,在分析现有预裂爆破线装药密度的经验公式基础上,完善并修正了线装药密度经验公式,并结合面装药密度的概念,得出了空气间隔装药预裂爆破合理空气比的半理论半经验公式,为爆破施工提供参考依据。     

基于奇数沟千分尺的丝锥中径单针测量方法探讨

采用奇数沟千分尺可以使用单针法测量丝锥中径,日本三丰公司生产的奇数沟千分尺,在其产品说明书中给出了单针法测量丝锥中径的分步式计算公式。但是国产奇数沟千分尺如果采用上述分步式计算将会导致错误的结果。该文依据奇数沟千分尺的原理和丝锥中径的单针法测量原理,推导出了丝锥中径的综合计算公式。最后提供上述两种丝锥中径计算方法的实验对比结果,证明了分步式计算公式中系数准确计算的重要性。