向量相似度测度方法

判断两个向量的相似程度,一般采用计算相似度的方法。首先对相似度测度法中的几种成熟的计算方法和应用优缺点进行了综合分析和对比。然后,根据实际的应用需要,结合两种成熟的距离测度法的方法,提出了一种改进的距离测度,即相对误差距离;又从放大较大相对误差作用的思路出发,提出一个相似性函数,即最大相异系数。这两种方法都充分考虑了相对变化量,具有针对性,适用于未知的待比较向量与确知的标准向量进行测度的情况。     

镜片测度表示值误差的测量不确定度评定

本文介绍了镜片测度表的用途与原理,运用测量不确定度评定与表示方法,对镜片测度表示值误差的测量值的不确定度进行了评定,详细分析了测量过程中的各分量对示值误差的影响,最后得出测量值的扩展不确定度。     

复合材料结构损伤的属性理论综合评估

为获得一种实时判别复合材料结构损伤的方法研究了属性测度及其识别.用材料结构的应力变化和表面短裂纹群作为特征矢量对结构的状态进行离散化处理,将属性测度识别方法应用于各离散状态的识别,从而对材料结构的损伤程度进行评估.实验表明这种方法的综合识别效率优于径向基函数神经网络,为研究复合材料结构的损伤在线识别提供了一种研究方法.     

基于极小准则的完备正交判别局部保持算法

以无监督判别投影算法为理论基础,提出了一种基于极小准则的完备正交判别局部保持投影算法.算法首先根据同类样本的空间信息重新定义了类内局部保持散度矩阵与类问局部保持散度矩阵,然后借鉴无监督判别投影算法的目标函数,推导出一个基于极小准则的目标函数,该目标函数通过投影到总体散度矩阵的非零空间中有效地解决小样本问题,最后给出了该...     

关于多输出布尔函数的第二类非线性度

本文对多输出布尔函数的第二类非线性度进行研究,该定义是衡量抵抗最佳多输出仿射逼近攻击性能的一项重要准则.利用多输出布尔函数的Walsh变换,我们给出第二类非线性度的一种表达式,并在此基础上得到第二类非线性度的一个上界.进一步地,我们给出了当第一类非线性度达到最优时,其第二类非线性度的一个界.此外,本文还给出任意多输出布尔函数与所有多输出线性函数之间距离的均值.     

一类具离散时变时滞和分布时滞神经网络的指数稳定性(英文)

本文讨论一类具离散时变时滞和分布时滞神经网络的指数稳定性。利用非线性测度,本文得到一个与时滞无关的充分条件,它保证了平衡点的存在性、唯一性和指数稳定性。既然新稳定准则不要求激活函数的有界性、单调性及可微性和随时间改变的传递延迟函数的可微性,那么它是某些已有结果的推广。此外,本文的方法的另一个优点是给出了解的指数收敛速度。最后,给出的例子说明我们的方法是有效的。     

未确知测度模型在爆破振动安全预评价中的应用

根据当前土岩爆破振动危害效应的影响因素众多,而且各影响因素之间的综合作用不确定的特点,通过引入未确知测度模型,建立了土岩爆破振动的安全预评价模型,并结合工程实例,对某土石方开挖工程爆破振动的危害效应进行了基于未确知测度理论的安全预评价.实例分析表明:基于未确知测度的爆破振动安全预评价模型在各评价指标权重和识别准则的确定上,分别采用了信息熵和置信度识别准则,使评价结果更具客观性,将影响爆破振动安全的各影响因素的未确知程度定量化,使评价结果更具客观性,为合理有效地控制爆破振动的危害效应提供了决策依据,也为土岩爆破振动的安全预评价提供了一种新方法.     

冻结砂土爆破作用区域内损伤模型分析

为了分析冻结砂土爆后的破坏程度,在探究冻结砂土爆破机理的过程中,将冻结砂土爆破作用的区域划分为空腔、挤压区、破碎区、裂纹区和弹性振动区,依据动力学原理,分析冻结砂土的爆破过程,推导出爆破后空腔及各破坏区域近似半径,并用损伤理论分区分析。结果是,在挤压区,采用Bui等建立的突然损伤模型,则爆炸载荷作用前D=0,冻土瞬间损伤断裂条件后D=1;在破碎区,动态抗压强度准则采用引入应变率效应的莫尔-库仑准则,损伤模型取修正的Lemaitre损伤模型;在裂纹区,采用准脆性材料的微裂纹扩展条件为冻土损伤准则,损伤模型采用弹塑性损伤模型。根据各爆破作用区域损伤特点,采用不同的损伤模型分析,细化了冻结砂土爆破破坏形式,为冻结砂土工程爆破实践提供理论参考。     

Sierpinski垫片的Hausdorff测度

Sierpinski垫片是具有严格的自相似性的经典分形集之一 ,它的 Hausdorff测度的估计和计算在理论上具有更重要的意义。本文通过在 Sierpinski垫片上定义某种质量分布 ,导出了相应的分形插值函数 ,通过对该分形插值函数性质的分析 ,并用质量分布原理 ,给出了 Sierpinski垫片的 Hausdorff测度的一个下界     

未确知测度理论在爆破飞石安全评价中的应用

根据土岩爆破中爆破飞石危害效应影响众多且难准确测定的特点,通过引入未确知测度方法,建立了爆破飞石的安全评价模型,并结合工程实例,对某土岩爆破工程中飞石的危害效应进行了基于未确知测度理论的安全评价。评价分析表明:基于未确知测度的爆破飞石安全评价模型,采用信息熵确定评价指标权重,在识别准则的确定上采用置信度识别准则,将各因素对爆破飞石危害效应的影响程度定量化,使评价结果更具客观性,为合理有效地控制爆破飞石的危害效应提供了决策依据。     

钢管截面形状分析及其圆度测量方法初探

介绍了钢管圆度精密测量使用的仪器和通过四种测量方法测量的准确数据,提出测量棱圆横截面的方 法。     

Numerical analysis of the acoustic signature of a surface-breaking crack

The boundary element method is used to calculate the acoustic signature, produced by a line focus scanning acoustic microscope, of an elastic object containing a surface-breaking crack. The acoustic signature has a vertical (z) and horizontal (x) dependence. A model of the microscope developed earlier is used and extended to take account of the crack. The mathematical formulation of the scattering problem for the cracked object leads to hypersingular integral equations. A suitable technique is employed to solve such equations by the boundary element method. An electromechanical reciprocity identity is used to relate the received voltage to the acoustic wavefields collected by the lens. The acoustic wavefield scattered from the cracked object is investigated, and curves are presented that display the acoustic signature, as functions of (x ,z), for cracks of various depths and orientations. A method to measure the depth of a surface-breaking crack using the acoustic signature is suggested.     

Measures of component importance in repairable multistate systems—a numerical study

Dynamic and stationary measures of importance of a component in a repairable multistate system are an important part of reliability. For multistate systems little has been published until now on such measures even in the nonrepairable case. According to the Barlow-Proschan type measures a component is important if there is a high probability that a change in the component state causes a change in whether or not the system state is above a given state. On the other hand, the Natvig type measures focus on how a change in the component state affects the expected system uptime and downtime relative to the given system state. In the present paper we first review these measures which can be estimated using advanced simulation methods. Extending earlier work from the binary to the multistate case, a numerical study of these measures is then given for two three component systems, a bridge system and also applied to an offshore oil and gas production system. In the multistate case the importance of a component is calculated separately for each component state. Thus it may happen that a component is very important at one state, and less important, or even irrelevant at another. Unified measures combining the importances for all component states can be obtained by adding up the importance measures for each individual state. According to these unified measures a component can be important relative to a given system state but not to another. It can be seen that if the distributions of the total component times spent in the non-complete failure states for the multistate system and the component lifetimes for the binary system are identical, the Barlow-Proschan measure to the lowest system state simply reduces to the binary version of the measure. The extended Natvig measure, however, does not have this property. This indicates that the latter measure captures more information about the system.     

Construction of a Structural-Parametric Diagnostic Model from the Results of Processing Measurement Information

A justification is given of an approach in which it is proposed to use diagnostic information concerning the structural characteristics of an object, in the form of a structural-parametric mathematical model, together with data concerning the results of measurements of its important parameters in order to determine the technical state of the diagnosed object.     

Colour Reproduction as a Function of Tone Scale in Negative-Positive and Reversal Systems

The object of this study is to provide o method for simulating the whole process of colour reproduction in a mathematical way, so that at any moment well-chosen changes can be introduced into the different steps of this process. This approach provides certain possiblities, when testing the quality of colour reproduction by colour material, which are not yet afforded with the required accuracy by empirical means.     

Mathematical simulation of the temperature state of an inhomogeneous body

A mathematical model is treated, which contains alternative functionals and describes the temperature state of an inhomogeneous body. This model enables one to obtain quantitative information about the temperature state of an inhomogeneous body and, owing to the dual variational formulation of the problem being solved, to estimate the error of the results of computer simulation. An example is given of utilizing the mathematical model.     

Theoretical analysis and reduction of the quantization noise effects in the SA‐DCT

We present a detailed mathematical analysis of two important problems in object‐based video coders that use shape‐adaptive discrete cosine transform (SA‐DCT). One is the annoying mean distortion effect caused by the quantization process and the other is the quantization noise dependence on the object shape (and not only on the quantizer characteristics). A general expression for the cross‐correlation matrix of the image error magnitude is presented, as well as one for the particular case of white quantization noise. In the latter case, four different implementation options are examined. We propose new strategies to minimize (or even eliminate) the two problems considered in our mathematical formulation. The results of our experiments show that the proposed scheme outperforms those obtained with other strategies described in the literature. © 2005 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 14, 238–245, 2004; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/ima.20030     

On the feasibility of high spatial resolution superconducting X-ray detectors

We discuss a class of superconducting particle/radiation detectors in which the readout is by magnetic means. Even a small energy deposition can change the state of a superconductor, leading to a drastic change of its electromagnetic properties. To increase the detector sensitivity, a highly granulated superconducting medium is used. Millions of physically separated sensors are read out in parallel by only a few channels of very sensitive D.C.-SQUID based electronics. We present the mathematical formulation of the problem and discuss how the excellent signal-to-noise ratio obtained using SQUIDs permits us to determine particle/photon localization.     

大直径数显测量装置系统的研究

大型零件直径尺寸的测量是当今国内外尚未得到很好解决的技术关键。本文主要介绍作者设计研制的大直径数显测量装置系统,并提出了新的测量原理和方法,经鉴定验证,该装置的测量精度可以满足大直径零件ＩＴ６精度等级的加工要求,保证了产品质量．     

Construction of Infrared Images of Objects in the Sea Taking into Account Radiation Reflected from an Undulating Sea Surface

A mathematical model of the process by which infrared images of objects in the sea are generated that takes into account radiation reflected from a disturbed sea surface is described. The contribution of the reflected component to the total radiant flux from the object in the sea is estimated as a function of the state of the atmosphere, the degree of undulation of the sea, and the angle of sight to the object.