钢包用滑板的热应力有限元分析

连铸钢包使用的滑动激光器是控制连铸生产过程的关键设备之一。为了确定501滑板使用中产生裂纹的原因，抑制裂纹形成，提高滑板使用寿命，本文应用有限元法进行了滑板热应力分析，并与生产中使用的滑板比较，有限元分析显示：在滑板材质一定的情况下，滑板形状以及滑板的预紧能力和固定方式是影响滑板使用寿命的基本因素。     

Shear Stress in Smooth Rectangular Open-Channel Flows

The average bed and sidewall shear stresses in smooth rectangular open-channel flows are determined after solving the continuity and momentum equations. The analysis shows that the shear stresses are function of three components: (1) gravitational; (2) secondary flows; and (3) interfacial shear stress. An analytical solution in terms of series expansion is obtained for the case of constant eddy viscosity without secondary currents. In comparison with laboratory measurements, it slightly overestimates the average bed shear stress measurements but underestimates the average sidewall shear stress by 17% when the width–depth ratio becomes large. A second approximation is formulated after introducing two empirical correction factors. The second approximation agrees very well (R2>0.99 and average relative error less than 6%) with experimental measurements over a wide range of width–depth ratios.     

Increased Vulnerability to Stress Following Opiate Exposures: Behavioral and Autonomic Correlates.

The authors used rats to study the impact of a history of opiate exposures on behavioral and autonomic responses to restraint stress. Brief restraint (30 min) provoked tachycardia and a pressor response, anxiety (as indexed by social interaction), grooming, and reduced exploration. The pressor response was reduced at 1 day, but not 7 days, after last opiate exposure; tachycardia was unaffected (Experiment 1). Stress-induced anxiety was potentiated 1 and 7 days after last opiate exposure (Experiment 2), and this potentiation was a function of dose (Experiment 3) and duration (Experiment 4) of opiate exposure. The results show that a history of opiate exposures alters vulnerability to stress and has implications for understanding coping, anxiety, and emotionality in former opiate users. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stress Generation, Avoidance Coping, and Depressive Symptoms: A 10-Year Model.

This study examined (a) the role of avoidance coping in prospectively generating both chronic and acute life stressors and (b) the stress-generating role of avoidance coping as a prospective link to future depressive symptoms. Participants were 1,211 late-middle-aged individuals (500 women and 711 men) assessed 3 times over a 10-year period. As predicted, baseline avoidance coping was prospectively associated with both more chronic and more acute life stressors 4 years later. Furthermore, as predicted, these intervening life stressors linked baseline avoidance coping and depressive symptoms 10 years later, controlling for the influence of initial depressive symptoms. These findings broaden knowledge about the stress-generation process and elucidate a key mechanism through which avoidance coping is linked to depressive symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

理论模型在高质量、无缺陷铸坯生产中的应用

尽管连续铸钢技术已经在全世界广泛、成功地应用，然而通过现存所选择的工艺和设计参数来生产高质量产品还有一些障碍。近年来，通过冶金工作者的不断努力，取得了一些突破性成就。     

Calibration of the Weibull stress scale parameter, σu, using the Master Curve

This work proposes that the Weibull stress scale parameter, σ_u, increases with temperature to reflect the increasing microscale toughness of ferritic steels caused by local events that include plastic shielding of microcracks, microcrack blunting, and microcrack arrest. The Weibull modulus, m, then characterizes the temperature invariant, random distribution of microcrack sizes in the material. Direct calibration of σ_u values at temperatures over the DBT region requires extensive sets of fracture toughness values. A more practical approach developed here utilizes the so-called Master Curve standardized in ASTM Test Method E1921-02 to provide the needed temperature vs. toughness dependence for a material using a minimum number of fracture tests conducted at one temperature. The calibration procedure then selects σ_u values that force the Weibull stress model to predict the Master Curve temperature dependence of K_Jc values for the material. At temperatures in mid-to-upper transition, the process becomes more complex as fracture test specimens undergo gradual constraint loss and the idealized conditions of high-constraint, small-scale yielding assumed in E1921-02 gradually degenerate. The paper develops the σ_u calibration process to incorporate these effects in addition to consideration of threshold toughness effects and the testing of fracture specimens with varying crack-front lengths. Initial illustrations of the calibration process for simpler conditions, i.e. 1T crack-front lengths, use the temperature dependent flow properties and a range of toughness levels for an A533B pressure vessel steel. Then using the extensive fracture toughness data sets for an A508 pressure vessel steel generated recently by Faleskog et al. [Engng. Fract. Mech., in press], the paper concludes with calibrations of both m and σ_u over the DBT region and assessments of the Master Curve calibration approach developed here.     

走向嵌入式因特网

简要介绍嵌入式系统,嵌入式因特网的概念,以及对嵌入式设备因特网接入的展望     

降温替代法在改线施工中的应用

在线路升高改造中，由于线路局部升高，将引起线长的变化，因此需计算导线和地线的应力来进行线长调整，否则可能导致该耐张段应力增加。为此提出了一种试算方法——降温替代法，并通过实例详细说明了该方法的计算过程。     

1Cr17Ni2 钢锻造工艺试验

通过对１Ｃｒ１７Ｎｉ２钢锻造工艺试验，掌握了锻件成形后的组织和力学性能，找出了锻件形成过程中使锻件各质点处于最佳应力状态的锻造工艺方法，避免锻造裂纹     

钢筋混凝土环形截面构件受弯时强度计算

空心圆形电柱在安装时可能受到弯曲作用，其强度计算，是在做了合理假定后推导力学方程式。求解方程式并非易事，即使使用计算机也只是试算求解，或采用图解法。本文给出求解联立方程组的计算方法。