细晶粒钢筋拉伸试验测量不确定度评定

介绍了细晶粒钢筋拉伸试验中测量结果的不确定度评定方法,分析了拉伸试验中屈服强度ReL、抗拉强度Rm、断后伸长率A的影响因素,计算出了各种因素的标准不确定度,得出拉伸试验结果(ReL、Rm、A)的扩展不确定度,并给出最终测量结果的表达式.     

基于最大熵原理的测量不确定度商概率建模及计算

测量数学模型建立后,测量不确定度评定需考虑输入量的不确定度及分布的传递性.若测量模型为幂指数积模型,通常先将输入量线性化,再采用合成方差的方法计算被测量的不确定度,方法计算简便,但未揭示不确定度随分布传递这一现象.针对问题,首先运用最大熵原理,计算测量仪器分辨力已知时,输入量的概率密度函数,其结果显示输入量服从矩形分布;其次重点推导了输入量与被测量之间为商概率模型时,被测量的概率密度函数、估计值和测量不确定度,并给出不确定度评定的具体步骤;最后利用恒流源测量高精密小电阻实例的对比分析,说明了该不确定度评定模型的可行性和有效性.     

区间数伴语言变量的混合多属性决策

针对属性值既有区间数又有定性语言变量的混合多属性决策问题,基于集对分析中的联系数理论,通过语言变量的等级赋值,再把赋值看成区间数,继而把区间数转换成二元联系数,利用二元联系数中的确定性分量作出初决策,再利用二元联系数的不确定性分量作不确定分析,得到终决策。实例应用表明,该方法原理简单,方法简明,决策结果可靠。     

测量不确定度信息约束下的最大熵分布研究

不确定度报告广泛存在于计量工作中,在不确定度报告的有效周期内,如何利用已有的不确定度信息为后续的测量不确定度评定服务是一个重要的问题.文章以被测量已有的不确定度信息为约束条件,提出了一种结合最大信息熵原理和Heaviside阶梯函数的最大熵分布确定方法,实现被测量分布的推导.同时给出遗传算法计算拉格朗日乘子.通过实例分析发现,当被测量为对称性分布时,基于不确定度信息的最大熵分布与理论分布拟合地较好,而当被测量为非对称性分布时,拟合存在一定的偏差.但在仅有测量不确定度信息的情况下,最大熵分布是对被测量真实分布较好的近似,因而可将此分布用于后续的不确定度评定.     

基于联系数的定性定量混合多属性区间数决策

针对多属性区间数决策中既有用定量属性又有用自然语言表示的定性属性的这类复杂问题,基于集对分析的联系数理论,把定性属性值先用区间数赋值,再把各属性值区间数转换成二元联系数,建立基于二元联系数的决策模型,利用模型中的确定性联系分量作出初决策,再利用模型中的不确定量作不确定分析,得到终决策.方法简称为"确定性计算+不确定性分析-两步决策法".把以上方法用于电力黑启动决策实例计算和分析,表明方法原理清晰,方法简明,结论可靠,有应用推广价值.     

基于联系数伴随函数的区间数多属性决策

针对把集对分析联系数用于区间数多属性决策时会遇到联系数中i取值不确定问题,给出了一种合理规避i取值的区间数多属性决策新方法,先利用联系数的态势函数确定决策方案的态势排序,态势级别相同时利用联系数的势函数确定方案的优劣排序;势函数相同时再利用联系数的二阶全偏联系数确定方案的优劣排序;实例应用表明:该方法不仅合理规避了i取值难题,计算简便,而且同时兼顾了决策方案的当前状态评价和发展趋势评价,使决策更具合理性和可操作性。     

梯形模糊有序加权几何算子及其在决策中的应用

针对梯形模糊数据信息的集成问题,给出了梯形模糊数两两比较的可能度公式和梯形模糊有序加权几何(TFOWG)算子.基于可能度公式和TFOWG算子,提出了一种准则权重信息完全未知且准则值以梯形模糊数形式给出的不确定多准则决策方法.最后,实例分析表明了该方法的可行性和有效性.     

一种基于区间型联系数的多指标决策方法

首先定义了区间数贴近度,并讨论了相应的性质;然后在联系数的基础上定义了区间型联系数及运算法则,并给出了区间型决策矩阵的规范化公式,提出了一种基于区间型联系数相对贴近度的决策方案排序方法.运用该方法进行多指标决策和评价,概念清楚、涵义明确,决策和评价结果准确、可信、不具有主观随意性.最后通过实例分析验证了该方法的有效性和...     

基于累积效应的区间粗糙数距离

区间粗糙数是一种新的用来描述不确定问题的不确定数,合理定义两个区间粗糙数之间的距离成为解决属性值为区间粗糙数的多属性决策问题的重要组成部分。本文基于集合的思想建立区间粗糙数与区间数之间的联系,进而基于累积效应构建新的区间粗糙数之间的距离,证明新定义满足距离的三个公理化条件,并示例说明新定义的距离相较于原有距离的优越性。最后将新定义的距离与基于贴近度的理想解法相结合应用到属性值为区间粗糙数的多属性决策问题中,并以数值实验验证其可行性。     

基于非线性相位恢复的X射线相位衬度断层成像算法

对全息测量下的X射线相位衬度断层成像问题提出了一种新的重建算法．该算法的主要想法是利用牛顿迭代法求解非线性的相位恢复问题．我们证明了牛顿方向满足的线性方程是非适定的,并利用共轭梯度法得到方程的正则化解．最后利用模拟数据进行了数值实验,数值结果验证了算法的合理性以及对噪声数据的数值稳定性,同时通过与线性化相位恢复算法的数值结果比较说明了新算法对探测数据不要求限制在Fresnel区域的近场,适用范围更广．     

基于联系数的预先危险性分析技术与应用

工程施工中的预先危险性分析受到随机、模糊、不确知等多种不确定性的干扰 ,采用集对分析联系数对客观存在的不确定性作系统描述 ,形成一种计及不确定性的预先危险性分析新技术 ,为工程施工预防安全事故、安全检查与评估提供了一种新的科学分析方法 .     

Reliability and covariance estimation of weighted k-out-of-n multi-state systems

In the literature of reliability engineering, reliability of the weighted k-out-of-n system can be calculated using component reliability based on the structure function. The calculation usually assumes that the true component reliability is completely known. However, this is not the case in practical applications. Instead, component reliability has to be estimated using empirical sample data. Uncertainty arises during this estimation process and propagates to the system level. This paper studies the propagation mechanism of estimation uncertainty through the universal generating function method. Equations of the complete solution including the unbiased system reliability estimator and the corresponding unbiased covariance estimator are derived. This is a unified approach. It can be applied to weighted k-out-of-n systems with multi-state components, to weighted k-out-of-n systems with binary components, and to simple series and parallel systems. It may also serve as building blocks to derive estimators of system reliability and uncertainty measures for more complicated systems.     

Uncertainty relations for sets of self adjoint operators

Uncertainty relations quantify the joint localisation in time respectively space domain and Fourier domain. For that reason they are an important tool in the design of wavelets. Uncertainty relations in higher dimension are most often realized as the tensor product of one dimensional uncertainty relations, whence these uncertainty relations are not invariant under rotations. The property of invariance with respect to rotation is however very desirable for image processing. We will give a new uncertainty relation for sets of self-adjoint operators that yields the desired invariance in many examples. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Behavior of CFRP-confined concrete cylinders with a compressive steel reinforcement

The paper presents results of an experimental investigations carried out to estimate the cooperation between a steel bar reinforcement and round concrete cylinders confined by a carbon-epoxy composite, concerning the increase in the concrete compression strength due the composite wrapping. The steel bar reinforcement with its yield stress considerably increases the bearing capacity of concrete. This also happens above the unconfined concrete strength of specimens. The onset of reinforcement yielding roughly coincides with reaching of the unconfined concrete strength at a compressive strain of ≈0.20%, and therefore it does not produce a change in the tangent modulus of the stress-strain relationships above the limit of linearity. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 43, No. 3, pp. 293–308, May–June, 2007.     

Experimetal study on the FRP-concrete bond behavior under repeated loadings

In this study, the effects of repeated loads on the FRP-concrete bond strength were investigated experimentally by direct pull out tests according to CSA S806-02. A conventional reinforcing steel bar and two types of glass-fiber-reinforced plastic (GFRP) bars were embedded in concrete and tested under four different loading patterns. The bond strength–slip curves of the bars were obtained and analyzed. The results showed that the maximum bond strengths under the repeated loads differed from those obtained under monotonic ones. In addition, noticeable differences in degradation of the bond strength with respect to the magnitude of slip were observed between the different bar types tested. On the basis of an image analysis of failure surfaces, they were attributed to the different bond failure mechanisms associated with the steel and GFRP bars.     

Tensile testing of high-strength unidirectional composites

Conclusions 1. In order to obtain stable values of the tensile strength of high-strength unidirectional composites it is necessary to use bar specimens with pressboard end reinforcement 90–110 mm in length.2. In determining the strength on specimens without end reinforcement it is necessary to select their size and shape with allowance for the transverse compressive strength, the shear strength and the taper of the grip jaws.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. All-Union Scientific-Research Institute of Aviation Materials, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 717–723, July–August, 1978.     

Comparison of the Bayesian and Randomised Decision Tree Ensembles within an Uncertainty Envelope Technique

Multiple Classifier Systems (MCSs) allow evaluation of the uncertainty of classification outcomes that is of crucial importance for safety critical applications. The uncertainty of classification is determined by a trade-off between the amount of data available for training, the classifier diversity and the required performance. The interpretability of MCSs can also give useful information for experts responsible for making reliable classifications. For this reason Decision Trees (DTs) seem to be attractive classification models for experts. The required diversity of MCSs exploiting such classification models can be achieved by using two techniques, the Bayesian model averaging and the randomised DT ensemble. Both techniques have revealed promising results when applied to real-world problems. In this paper we experimentally compare the classification uncertainty of the Bayesian model averaging with a restarting strategy and the randomised DT ensemble on a synthetic dataset and some domain problems commonly used in the machine learning community. To make the Bayesian DT averaging feasible, we use a Markov Chain Monte Carlo technique. The classification uncertainty is evaluated within an Uncertainty Envelope technique dealing with the class posterior distribution and a given confidence probability. Exploring a full posterior distribution, this technique produces realistic estimates which can be easily interpreted in statistical terms. In our experiments we found out that the Bayesian DTs are superior to the randomised DT ensembles within the Uncertainty Envelope technique.     

基于区间数确定性与不确定性相互作用点的多属性决策

区间数多属性决策中的区间数是确定性与不确定性的对立统一体,存在着相互依赖、相互作用的关系,利用集对分析的联系数理论可以计算出一个区间数的确定性与不确定性的"相互作用点",以此反映一个区间数确定性与不确定性相互作用的大小,该点同时可以作为该区间数的"代表点"参与决策,从而使区间数多属性决策过程简明,快捷.     

基于集对分析联系数的区间数型多属性决策投影模型及其在基坑支护方案评价中的应用

多属性决策时因掌握的信息有限,加之问题本身的复杂性、不确定性以及人类思维的模糊性,其属性的精确值往往难以获取,常用区间数形式表示针对多属性决策中各指标区间数不能直接进行大小比较的问题,提出一种基于集对分析联系数的区间数型多属性决策投影模型.模型用备择方案在理想方案上的投影进行集结,根据区间数的误差分布形式,沟通区间数与联系数的关系,根据a+bi型联系数大小比较法则,综合评价方案优劣.以某大厦基坑支护拟用的4种方案优化选择为例,说明方法的应用与模糊优化理论模型和灰色物元分析优化模型进行了对比,得到的结果一致.