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101.
In the evaluation of accurate weight functions for the coefficients of first few terms of the linear elastic crack tip fields and the crack opening displacement (COD) using the finite element method (FEM), singularities at the crack tip and the loading point need to be properly considered. The crack tip singularity can be well captured by a hybrid crack element (HCE), which directly predicts accurate coefficients of first few terms of the linear elastic crack tip fields. A penalty function technique is introduced to handle the point load. With the use of these methods numerical results of a typical wedge splitting (WS) specimen subjected to wedge forces at arbitrary locations on the crack faces are obtained. With the help of appropriate interpolation techniques, these results can be used as weight functions. The range of validity of the so-called Paris equation, which is widely used in the evaluation of the COD from the stress intensity factors (SIFs), is established. 相似文献
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Roberts Brent W.; O'Donnell Megan; Robins Richard W. 《Canadian Metallurgical Quarterly》2004,87(4):541
The present research examined continuity and change in the importance of major life goals and the relation between change in goals and change in personality traits over the course of college (N = 298). Participants rated the importance of their life goals 6 times over a 4-year period and completed a measure of the Big Five personality traits at the beginning and end of college. Like personality traits, life goals demonstrated high levels of rank-order stability. Unlike personality traits assessed during the same period and in the same sample, the mean importance of most life goals decreased over time. Moreover, each goal domain was marked by significant individual differences in change, and these individual differences were related to changes in personality traits. These findings provide insights into the relatively unstudied question of how life goals change during emerging adulthood. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
104.
The incompact long afterglow pigment SrAl2O4: Eu, Dy was synthesized by ceramics technology.The agglomerated starting raw material had little effect on the synthesis of SrA12O4 matrix through solid-state reaction method,but the shrinkage and densification was retarded greatly by the agglomerated powder by the formation of large and extensive pore network.The sintering mechanism is surface diffusion ( without flux B2O3 ) and grain boundary diffusion (with B2O3 as flux)respectively, and the as-prepared long afterglow pigment glows in the dark for over 4000 min. 相似文献
105.
目前我国在运核电厂和其他所有堆型(CPR1000、EPR和AP1000)的在建核电厂均缺少一套统一的放射性固体废物管理系统,缺乏对放射性固体废物从产生到最终处置的全周期跟踪管理。根据核电厂的放射性废物管理需求,研制了一套适合于各核电机型的核电厂放射性固体废物管理系统,对废物源项、处理、暂存、运输、处置全过程进行跟踪,使放射性废物管理安全、可控;研发了废物管理跟踪单和数据库,分析了废物管理工艺流程的逻辑关系,根据废树脂、浓缩液、废滤芯、检修废物等处理工艺分别设计了核素计算模型,可推算指定时刻的放射性水平,实现放射性废物数据的深度分析、应用以及对放射性废物安全管理的全过程追踪。研究成果已经在国内部分核电厂使用,有助于提高核电厂的放射性废物管理水平,具有较大的安全和社会意义。同时,该系统记录的数据有助于核电厂实现辐射防护优化设计和放射性废物最小化管理。 相似文献
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108.
Guo-Qing Zhang Shuai Wang Hai-Qing Zhang Xing-Wang Zhu Chao Peng Jun Cai Zhao-Zhong He Kun Chen 《核技术(英文版)》2017,28(3)
The release of fission products from coated particle fuel to primary coolant,as well as the activation of coolant and impurities,were analysed for a fluoride salt-cooled high-temperature reactor (FHR) system,and the activity of radionuclides accumulated in the coolant during normal operation was calculated.The release rate (release fraction per unit time) of fission products was calculated with STACY code,which is modelled mainly based on the Fick's law,while the activation of coolant and impurities was calculated with SCALE code.The accumulation of radionuclides in the coolant has been calculated with a simplified model,which is generally a time integration considering the generation and decay of radionuclides.The results show that activation products are the dominant gamma source in the primary coolant system during normal operation of the FHR while fission products become the dominant source after shutdown.In operation condition,health-impacts related nuclides such as 3H,and 14C originate from the activation of lithium and coolant impurities including carbon,nitrogen,and oxygen.According to the calculated effective cross sections of neutron activation,6Li and 14N are the dominant 3H production source and 14C production source,respectively.Considering the high production rate,3H and 14C should be treated before being released to the environment. 相似文献
109.
随着北斗三号卫星导航系统完成全球组网并正式开通,中国已成为世界上第3个独立拥有全球卫星导航系统的国家.目前BDS-3卫星可播发5个频点的观测信号,研究BDS-3多频组合对于实现模糊度快速固定、提高定位精度具有重要意义.针对中长基线解算,本文充分利用BDS-3四频中存在电离层延迟极小且具有整数特性的组合,同时考虑对流层延迟的影响,建立了基于弱电离层组合的中长基线解算模型.实验结果表明,相比于传统双频无电离层模型,该模型的模糊度固定速度提高10%以上,N、E、U 3个方向定位精度相比最优双频无电离层组合分别提高了7.7%、7.9%、8.2%. 相似文献
110.