封套材料透湿率影响因素分析

对封套材料透湿率影响因素进行了分析，提出了设计封套材料的见解。     

纸基全息印品图文质量的影响因素分析

介绍了纸基全息印品的生产工艺流程,分析了全息涂料的单体组成对涂膜性能的影响,讨论了激光全息图文质量的光学特性指标--衍射效率和信噪比,着重阐述了模压温度、纸张表面光泽度和背景颜色对衍射效率的影响.     

Classification: Methods for the Exploratory Analythi of Multivariate Data

A fuzzy clustering strategy is used to identify subsets of influential observations in regression. As part of the fuzzy clustering strategy, the analyst can explore the uniqueness of selected subsets and the degree of belonging of observations to selected subsets. This is accomplished by either varying a fuzzy parameter or the number of clusters. Once the observations or subsets have been identified, the analyst can then compute regression diagnostics to confirm their degree of influence in regression. Bootstrapping and high-breakdown procedures were used to confirm the influence of the previously identified subsets. This fuzzy clustering strategy is applied to the modified data on wood-specific gravity and an augmented production dataset. Both datasets have been previously presented in the literature.     

CDF sensitivity analysis technique for ranking influential parameters in the performance assessment of the proposed high-level waste repository at Yucca Mountain, Nevada, USA

A cumulative distribution function (CDF)-based method has been used to perform sensitivity analysis on a computer model that conducts total system performance assessment of the proposed high-level nuclear waste repository at Yucca Mountain, and to identify the most influential input parameters affecting the output of the model. The performance assessment computer model referred to as the TPA code, was recently developed by the US nuclear regulatory commission (NRC) and the center for nuclear waste regulatory analyses (CNWRA), to evaluate the performance assessments conducted by the US department of energy (DOE) in support of their license application. The model uses a probabilistic framework implemented through Monte Carlo or Latin hypercube sampling (LHS) to permit the propagation of uncertainties associated with model parameters, conceptual models, and future system states. The problem involves more than 246 uncertain parameters (also referred to as random variables) of which the ones that have significant influence on the response or the uncertainty of the response must be identified and ranked. The CDF-based approach identifies and ranks important parameters based on the sensitivity of the response CDF to the input parameter distributions. Based on a reliability sensitivity concept [AIAA Journal 32 (1994) 1717], the response CDF is defined as the integral of the joint probability-density-function of the input parameters, with a domain of integration that is defined by a subset of the samples. The sensitivity analysis does not require explicit knowledge of any specific relationship between the response and the input parameters, and the sensitivity is dependent upon the magnitude of the response. The method allows for calculating sensitivity over a wide range of the response and is not limited to the mean value.     

基于线性化Nataf变换的一次可靠度方法

首先引入等概率边缘变换的基本原理,证明了常用的Rackwitz-Fiessler变换是等概率边缘变换的一次近似形式,将当量正态化原理和线性变换相结合,提出了扩展的Rackwitz-Fiessler变换,并指出其存在的缺点。然后针对Nataf变换的非线性特征,提出了线性化Nataf变换,并将该变换与改进的HLRF算法相结合,给出了基于线性化Nataf变换和iHLRF算法的一次可靠度方法。将Nataf变换、线性化Nataf变换和扩展的Rackwitz-Fiessler变换通过算例进行了对比分析,结果表明:采用线性化Nataf变换的结构可靠度分析结果收敛于采用Nataf变换的计算结果,而采用扩展的Rackwitz-Fiessler变换的计算结果则有较大的误差。     

Calculation of crack tip phase transformation zones with the weight function method

Stabilized Zirconia ceramics can undergo a stress-induced tetragonal-to-monoclinic phase transformation. This way, a transformation zone with compressive stresses develops around crack tips, leading to an increase in fracture toughness. The increase in fracture toughness depends on the size of the transformation zone. Therefore, the ability to compute the phase transformation zone at a crack tip is crucial to determine the transformation toughening due to phase transformation. In the case of subcritical phase transformation, the crack tip phase transformation zone has been calculated using the finite element method. In some Zirconia ceramics, such as ceria-stabilized TZP Zirconia ceramics, an autocatalytic phase transformation takes place, leading to large, elongated transformation zones. As this supercritical phase transformation cannot be computed with finite elements, several methods for investigating supercritical phase transformation have been developed. In this paper, a method based on the weight function method will be described.     

On the transformation textures influenced by deformation in electrical steels,high manganese steels and pure titanium sheets

Transformation texture is normally different to deformation and recrystallization textures, thus influencing materials properties differently. As deformation and recrystallization are often inseparable to transformation in materials which shows a variety in types such as diffusional or non-diffusional transformations, different phenomena or rules of strengthening transformation textures occur. This paper summarizes the complicated phenomena and rules by comparison of a lot of authors’ published and unpublished data collected from mainly electrical steels, high manganese steels and pure titanium sheets. Three kinds of influencing deformation are identified, namely the dynamic transformation with concurrent deformation and transformation, the transformation preceded by deformation and recrystallization and the surface effect induced transformation, and the textures related with them develop in different mechanisms. It is stressed that surface effect induced transformation is particularly effective to enhance transformation texture. It is also shown that the materials properties are also improved by controlled transformation textures, in particular in electrical steels. It is hoped that these phenomena and processing techniques are beneficial to the establishment of transformation texture theory and property improvement in practice.     

结构可靠度分析中变量相关时三种变换方法的比较

介绍了Orthogonal变换、Rosenblatt变换和Nataf变换三种变换方法的基本原理,并比较了三种变换方法的优缺点及其适用范围.采用算例详细地比较了三种变换方法对可靠度结果的影响.结果表明,Nataf变换和Orthogonal变换的根本区别在于Nataf变换考虑了相关变量变换到相关标准正态空间后相关系数的变化...     

V-Ti钢热变形奥氏体的连续冷却转变行为

为研究V—Ti微合金钢热变形奥氏体的连续冷却转变行为，在对V—Ti徽合金钷进行Gleeble3800热模拟后，建立了连续冷却转变曲线（CCT图），探讨了变形量和高温停留对CCT曲线和相变组织的影响．研究表明：变形量的增大，促进了先共析铁素体和珠光体转变，使其孕育期缩短，一定程度上也促进了高冷速下的贝氏体转变，但使低冷速下的贝氏体转变受阻；马氏体转变温度的降低说明变形量的增大在一定程度上使马氏体相变受阻；变形后若高温停留，组织发生静态回复，对扩散型相变的先共析铁素体和珠光体转变以及半扩散型相变的贝氏体转变均不利，使先共析铁素体转变量和珠光体转变量都有相对减少，而对马氏体转变影响不大．     

Bainitic transformation kinetics and stress assisted transformation

Abstract

With reference to experimental data, the effects of stress, chemical composition, and transformation temperature on bainitic transformation kinetics are analysed. A decrease of transformation temperature or an increase of carbon equivalent results in a slow rate of bainitic transformation and reduces the promotive effect of stress induced transformation. Moreover, the relative effect of unit stress on kinetic parameter b in the Avrami equation for bainitic transformation is found to be in the 10^-3 order of magnitude, and n (Avrami index) tends to increase with decrease of transformation temperature. A comprehensive model to depict bainitic transformation kinetics dependent on stress and chemical composition as well as transformation temperature is established.     

Top-hat selection transformation for infrared dim small target enhancement

Abstract

To improve the performance of top-hat transformation for infrared dim small target enhancement, a top-hat selection transformation is proposed in this paper. First, the top-hat selection transformation is defined and analysed based on analysing and improving of classical top-hat transformation. Then, the top-hat selection transformation is used to enhance infrared dim small targets. The calculation of parameters used in top-hat selection transformation for infrared dim small target enhancement is discussed in detail. Various experiments verified that top-hat selection transformation was effective for infrared dim small target enhancement.     

Calculation of Autocatalytic Phase Transformation Zones in Cracked and Uncracked Zirconia Ceramics

Stabilized zirconia ceramics can undergo a stress-induced tetragonal-to-monoclinic phase transformation. A transformation zone with compressive stresses develops at crack tips, leading to an increased fracture toughness which depends on the size and geometry of the transformation zone. In this paper, transformation zones in cracked and uncracked bodies for the case of autocatalytic phase transformation are computed using the weight function method and Eshelby's method. The results are compared with experimentally observed transformation zones.     

Experimental investigation of the transformation zone of tetragonal zirconia polycrystalline ceramics

Stress-induced martensitic transformation plastic zones of ceria-stabilized tetragonal zirconia polycrystalline ceramics, under some typical loading conditions, were studied by Moiré interferometry. The full-field fringe patterns, including u-fields and v-fields, were acquired. According to these patterns, the transformation zone shape and transformation plasticity distributions of the specimens were obtained. The experimental results show that the stress-induced transformation at room temperature is concentrated in some narrow bands and the transformation plasticity is not uniform within the transformation zone. Experiments also reveal that the transformation zone with a characteristic elongated shape ahead of the notch, in a single-edge notch bending specimen, is obviously different from that resulting from some constitutive relation of transformation. This work provides a significant experimental foundation for establishing the theoretical models of transformation toughening.     

Transformation criterion of phase transformation toughening ceramics with misoriented microcracks

Phase transformation criterion is the key to investigating the toughness of phase transformation ceramics. In this paper, the modified equivalent inclusion theory by the authors is employed to study the interaction between microcracking and transformation in ceramics. The transformation criterion is derived. The influence of microcracks and transformation particles on the critical transformation load is discussed. This revised version was published online in November 2006 with corrections to the Cover Date.     

The distance sinh transformation for the numerical evaluation of nearly singular integrals over curved surface elements

This paper presents a new transformation termed as the distance sinh transformation for the numerical evaluation of nearly singular integrals arising in 3D BEM. The new transformation is an improvement of the previous sinh transformation. The original sinh transformation is only limited to planar elements. Moreover, when the nearly singular point is located outside the element, results obtained by the original sinh transformation combined with conventional subdivision method are not quite accurate. In the presented work, the sinh transformation combined with the distance function is proposed to overcome the drawbacks of the original sinh transformation. With the improved transformation, nearly singular integrals on the curved surface elements can be accurately calculated. Furthermore, an alternative subdivision method is proposed using an approximate nearly singular point, which is quite simple for programming and accurate results can be obtained. Numerical examples for both curved triangular and quadrangular elements are given to verify the accuracy and efficiency of the presented method.     

Ti-49.6Ni合金在拉压对称循环载荷下的电阻-温度曲线

用电阻法测量了固溶后Ti-49.6Ni形状记忆合金的相变行为,马氏体逆相变具有明显的相变温度点;在降温过程中没有发生R相变。在该热处理制度下材料疲劳后,在升温过程中没有明显的逆相变温度点;在降温过程中出现R相变。电阻-温度曲线特征发生明显规律性变化,提出一种解释这一现象的微观机制。     

Effect of pro-eutectoid ferrite on subsequent bainite transformation kinetics simulation

The kinetics of multiphase transformation is more complicated than single phase transformation due to the effects of prior phase transformation on the subsequent transformations. The authors have previously proposed a new method to estimate the parameters related to the isothermal kinetics of single phase transformation. This current paper investigates the application of the authors’ method to the bainite transformation process of multiphase steel G18CrMo2-6. The mathematical relationship between Pro-eutectoid ferrite (Pro-EF) fractions and the kinetics related parameters of the subsequent bainite transformation during heat treatment processes in the G18CrMo2-6 multiphase steel has been investigated. The results show the significant effect of Pro-EF fractions on the start and finish temperatures and the isothermal phase transformation parameters ‘b’ of subsequent bainite transformation.     

Modeling the effects of digital transformation in Indian manufacturing industry

Digital transformation has become the new norm and is perceived as an important component to transform the firms’ businesses. It has revolutionized the way in which firms conduct their businesses. However, the literature has not widely examined the holistic impact of key antecedents of digital transformation on manufacturing firm performance. The study aims to identify the antecedents of digital transformation and demonstrates the mediating role of digital transformation on firm performance. Using PLS-SEM modeling reveals that there is a considerable impact of competitive pressure, organizational mindfulness, IT readiness, and strategic alignment on digital transformation. Also, digital transformation mediates the effects of the antecedents on the performance of the firm. The practitioners and firms would be motivated to seize the digital transformation advantages as an opportunity to improve firm performance.     

A Feedback Transformation of the Planning Problems

This paper proposes a problem transformation method, called feedback transformation method, for solving the planning problems. Some basic notions from the theory of problem transformation are introduced. Two measures of problem complexity are defined. Algebraic properties of the feedback transformation are investigated. Finally, a partial relationship between the problem transformation and decomposition methods is established. Received: January 21, 1994; revised version: May 25, 1998