Prediction of Fatigue Characteristics of Metals at Different Loading Frequences

The procedure for predicting fatigue characteristics by high-frequency test results over lifetime ranges up to 10¹⁰ cycles is proposed. The procedure is based on the fatigue fracture model accounting for the loading frequency and stress ratio. The potentials of the method are exemplified by the tests of smooth specimens and specimens with a stress concentrator from different materials (nickel-, aluminum-, and titanium-base alloys). The prediction results for different loading frequencies (35–10,000 Hz) and stress ratios (from -1 to 0.5) are shown to vary by about 10% from experimentally obtained data.     

Variations of stress intensity factor of a semi-elliptical surface crack subjected to mixed mode loading

Maximum stress intensity factors of a surface crack usually appear at the deepest point of the crack, or a certain point along crack front near the free surface depending on the aspect ratio of the crack. However, generally it has been difficult to obtain smooth distributions of stress intensity factors along the crack front accurately due to the effect of corner point singularity. It is known that the stress singularity at a corner point where the front of 3 D cracks intersect free surface is depend on Poisson's ratio and different from the one of ordinary crack. In this paper, a singular integral equation method is applied to calculate the stress intensity factor along crack front of a 3-D semi-elliptical surface crack in a semi-infinite body under mixed mode loading. The body force method is used to formulate the problem as a system of singular integral equations with singularities of the form r ⁻³ using the stress field induced by a force doublet in a semi-infinite body as fundamental solution. In the numerical calculation, unknown body force densities are approximated by using fundamental density functions and polynomials. The results show that the present method yields smooth variations of mixed modes stress intensity factors along the crack front accurately. Distributions of stress intensity factors are indicated in tables and figures with varying the elliptical shape and Poisson's ratio.     

Mixed numerical-analytical approach for dynamic one-point-bend test modelling

Specimen deformation during a one-point-bend impact test is modelled within 2D linear elasticity framework. Using modal superposition technique, the closed-form solutions for the striker force and dynamic stress intensity factor (DSIF) variation with time are derived. Parameters used in these solutions have been determined using plane stress finite element model of the specimen and approximated polynomially for a wide range of the specimen geometry parameters. The efficiency of the method proposed has been verified by comparison of the analytical results with the experimental data available in the literature and with the results of finite element analysis.     

An Investigation of Passivatior of Cerium for Red Copper

The paperis studied and probed into the cerium application in the passivators of red copper. Through the experimentation of single factor we knoew that ithas remarkable quality influence among red copper passivators by Ce3 , determined that there is obvious function in its small content. And we educed a best technology through the orthogonal test. Research shows: there are obvious changes in the molecular structure of the passivating films after adding the Ce compounds and anticorrosive performance is improved.     

有限元辐射度方法综述

在计算机真实感图形生成中,景物之间的光能传递可以归结为一个积分方程--辐射度积分方程.文章阐述了求解辐射度积分方程的一种技术--有限元方法.传统的辐射度方法实际上是取分片常值函数为基函数的有限元方法;为了提高辐射度计算的精度和效率,通常采用分片线性函数、分片二次函数和高阶函数为基函数的有限元方法;还可以同时采用上述各阶基函数,即采用高阶层次基函数的有限元方法.结果表明,利用有限元辐射度方法可以有效地模拟光在场景中景物面片之间的传递,获得高度真实感的图形.     

提高电网功率因数节能效果分析

由于感性负荷的比例大，造成供电电网的功率因数低，损耗大。本分析和计算了加装无功补偿装置后的高压供电线路和主变压器的节能效果。     

氧化膜铝带绕组起重电磁铁的改造

对氧化膜铝带绕组起重电磁铁改为铜绕组需注意的几个要点进行了阐述和分析，在此基础上结合改造实例介绍了改造过程中一些参数的计算方法。     

Structured Latent Curve Models for the Study of Change in Multivariate Repeated Measures.

This article considers a structured latent curve model for multiple repeated measures. In a structured latent curve model, a smooth nonlinear function characterizes the mean response. A first-order Taylor polynomial taken with regard to the mean function defines elements of a restricted factor matrix that may include parameters that enter nonlinearly. Similar to factor scores, random coefficients are combined with the factor matrix to produce individual latent curves that need not follow the same form as the mean curve. Here the associations between change characteristics in multiple repeated measures are studied. A factor analysis model for covariates is included as a means of relating latent covariates to the factors characterizing change in different repeated measures. An example is provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Structure of Anxiety and Depression in Urban Youth: An Examination of the Tripartite Model.

In this study, the authors examined the validity of the tripartite model of anxiety and depression (L. A. Clark & D. Watson, 1991) in a community epidemiological sample of 467 urban African American youth. Participants completed the Baltimore How I Feel (N. S. Ialongo, S. G. Kellam, & J. Poduska, 1999), a measure of anxiety and depressive symptoms, in Grades 6 and 9. Confirmatory factor analyses indicated that a 3-factor model representing the tripartite model fit the data well and better than competing models. Longitudinal confirmatory factor analysis revealed configural invariance of the tripartite factor structure. However, a predicted divergence among dimensions over time was not evidenced. High correlations among the tripartite dimensions suggest that anxiety and mood symptoms may not differentiate in urban youth. Results are discussed in terms of the ethnicity and urban context of this community sample. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Confirmatory Factor Analysis of the Psychopathy Checklist: Screening Version in Offenders With Axis I Disorders.

One hundred forty-nine inpatients within a maximum security psychiatric facility were assessed with the Psychopathy Checklist: Screening Version (PCL:SV; S. D. Hart, D. N. Cox, & R. D. Hare, 1995). Within the total sample, 68% had a psychotic disorder and 30% met criteria for psychopathy. Using confirmatory factor analysis, the authors tested the 2-factor PCL:SV model of psychopathy and recent 3- and 4-factor models. Results indicated good fit for each model, with the 4-factor model showing best overall fit. Structural equation modeling was used to determine which psychopathy factors predicted 6-month follow-up of inpatient aggression. The 2-, 3-, and 4-factor models, respectively, accounted for 16%.27%. and 3l% of the variance in aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)