High-Temperature Failure of an Alumina-Silicon Carbide Composite under Cyclic loads: Mechanisms of Fatigue Crack-Tip Damage

Experimental results are presented on the mechanisms of tensile cyclic fatigue crack growth in an A1₂0₃-33-vol%-SiC-whisker composite at 1400°C. The ceramic composite exhibits subcritical fatigue crack propagation at stress-intensity-fator values far below the fracture toughness. The fatigue characterized by the stressintensity-factor range, ΔK, and crack propagation rates are found to be strongly sensitive to the mean stress (load ratio) and the frequency of the fatigue cycle. Detailed transmission electron microscopy of the fatigue crack-tip region, in conjunction with optical microscopy, reveals that the principal mechanism of permanent damage ahead of the advancing crack is the nucleation and growth of interfacial flaws. The oxidation of Sic whiskers in the crack-tip region leads to the formation of a silica-glass phase in the 1400°C air environment. The viscous flow of glass causes debonding of the whisker-matrix interface; the nucleation, growth, and coalescence of interfacial cavities aids in developing a diffuse microcrack zone at the fatigue crack tip. The shielding effect and periodic crack branching promoted by the microcracks result in an apparently benefcial fatigue crack-growth resistance in the A1₂0₃—SiC composite, as compared with the unreinforced alumina with a comparable grain size. A comparison of static and cyclic load crack velocities is provided to gain insight into the mechanisms of elevated temperature fatigue in ceramic composites.     

Lane-changing behavior on urban streets: a focus group-based study

As lane-changing behavior has received increasing attention during the recent years, various algorithms have been developed. However, most of these models were derived and validated using data such as vehicle trajectories, with no consideration of driver characteristics. In this research, focus group studies were conducted to obtain driver-related information so that the driver characteristics can be incorporated into lane-changing models. Different urban lane-changing scenarios were examined and discussed in the focus group meetings. The likelihood for initiating lane changes under each scenario was obtained. The participating drivers were categorized according to their background information and verbal responses, so that the lane-changing behavior can be related to driver characteristics for each group. Two types of information, quantitative and qualitative responses from participants, were used to establish this relationship. The paper concludes by providing recommendations related to the implementation of study findings into micro-simulators to better replicate driver behavior in urban street networks.     

Dow Launches First Sustainability Report in China

<正> The Dow Chemical Company announced itslaunch of the inaugural issue of the "2009Dow Greater China Sustainability Report"on April 1st.The first launched "2009 Dow Greater ChinaSustainability Report" aims to introduceDow's sustainability strategies as well as the     

The social shaping of educational technologies in Saudi Arabia: An examination of how the social fabric shapes the construction and use of technologies

This article is organised around the research question: To what extent has the social fabric shaped the way in which educational technologies are constructed at the institutional level in a specific social context? This question is addressed through a naturalistic study of a state university in the Eastern Province of Saudi Arabia. Guided by the grounded theory approach, the data analysis demonstrated that Saudi society was committed to many established relationships, structures and identities, a commitment that has resulted in the social shaping of educational technologies.     

Dissociative states in eating disorders: An empirical Rorschach study.

The study explores the DSM-IV-TR classification of eating disorders that is constituted of four subtypes, two of them defined as anorexia (restricting and binge eating/purging) and two as bulimia (purging and non-purging). This classification is based on body weight as the distinguishing criterion. However, psychoanalytic thinking substantially distinguishes between restricting anorexia and the other three subtypes, all of them involving binge eating. Accordingly, binge eating patients are assumed to present different personality characteristics and different dynamics including dissociation proneness as a core component of the disturbance. The dissociative component of binge eating is examined by using the Rorschach Reality-Fantasy Scale (RFS; Tibon, Handelzalts, & Weinberger, 2005) and other Rorschach measures in a sample of 61 female adolescent inpatients diagnosed with eating disorders. This sample was divided into two groups by using the criterion of whether or not the symptoms involve binge eating behavior. The results support the view that dissociation between reality and fantasy is an important facet of binge eating disorders. A case study that demonstrates the utility of the RFS is presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On line and under veil: Technology-facilitated communication and Saudi female experience within academia

The Saudi female population, which is characterised as sheltered, hard-to-reach and conservative, is arousing good interest globally (and nationally). Therefore, a review of literature on emerging issues surrounding Saudi female experience is timely. This article, in the form of a literature review, provides a background to and justification for a forthcoming study, which will examine how technology-facilitated communication has shaped the social–cultural pattern of Saudi female experience within academia.     

SIMS quantification of As and In in Hg1−xCdxTe materials of different x values

This paper presents a study of Secondary Ion Mass Spectrometry (SIMS) quantification of As and In in Hg_1–xCd_xTe materials. The SIMS results show that for Hg_1-xCd_xTe with x from 0.2 to 0.8, As and In quantification is independent of the x-values (0.2–0.8). The relative sensitivity factors (RSF) for In and As derived from the standard of one x value can be used to accurately quantify unknown samples of different x value(s). We also determined the dependence of sputtering rate vs. x values under oxygen beam bombardment.