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采用化学成分分析、金相检测、宏观与微观断口形貌分析等方法,对柴油机QT600-3球墨铸铁曲轴的早期断裂机制进行了分析研究.结果表明,轴颈圆角处的表面氧化皮及显微裂纹是引起疲劳开裂的主要原因,淬火组织缺陷诱发裂纹源的形成,对曲轴早期断裂也有一定的影响,断裂机制为解理与准解理断裂,具有典型的脆性断裂特征。 相似文献
154.
黎云 《冶金标准化与质量》2005,43(3):73-75
针对我公司高线厂粗轧机开式机架,连接装置存在的问题,在结构分析、强度分析的基础上对此装置进行了改造,取得了很好效果。对于同类轧机开式机架连接具有一定的借鉴和参考价值。 相似文献
155.
The relationship between treatment outcome and the extent to which participants completed homework assignments was evaluated among 60 cocaine-dependent individuals assigned to cognitive-behavioral therapy (CBT). Homework was assigned in 72% of all sessions and initiated by participants in 48% of the sessions in which it was assigned. Completion of homework was unrelated to participants' baseline characteristics and several indicators of treatment compliance. Participants who completed more homework assignments demonstrated significantly greater increases in the quantity and quality of their coping skills and used significantly less cocaine during treatment and through a 1-year follow-up. These data suggest that the extent to which participants are willing to complete extrasession assignments may be an important mediator of response to CBT. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
156.
Burle Borís; Allain Sonia; Vidal Franck; Hasbroucq Thierry 《Canadian Metallurgical Quarterly》2005,31(4):831
Although it is widely accepted that control mechanisms are necessary for human behavior to be adapted, very little is known about how such mechanisms are recruited. A suggestion to fill the gap was put forward by M. M. Botvinick, T. S. Braver, C. S. Carter, D. M. Barch, and J. D. Cohen (2001), who proposed the conflict-loop theory. This theory has been successful in accounting for the reduction of compatibility effects after an incompatible trial: The level of conflict being, on average, higher during an incompatible trial, more control occurs after such a trial. The authors have tested this prediction by sorting the trials on the basis of amount of conflict (quantified by the electromyographic activity) they presented. A reduction of the compatibility effect was observed after incompatible trials, but it was independent of the level of conflict on previous trials, suggesting that the conflict does not trigger changes in executive control. Consequences for the conflict monitoring model are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Y. Deshayes L. Bechou F. Verdier Y. Danto 《Quality and Reliability Engineering International》2005,21(6):571-594
Numerous papers have already reported various results on electrical and optical performances of GaAs‐based materials for optoelectronic applications. Other papers have proposed some methodologies for a classical estimation of reliability of GaAs compounds using life testing methods on a few thousand samples over 10 000 hours of testing. In contrast, fewer papers have studied the complete relation between degradation laws in relation to failure mechanisms and the estimation of lifetime distribution using accelerated ageing tests considering a short test duration, low acceleration factor and analytical extrapolation. In this paper, we report the results for commercial InGaAs/GaAs 935 nm packaged light emitting diodes (LEDs) using electrical and optical measurements versus ageing time. Cumulative failure distributions are calculated using degradation laws and process distribution data of optical power. A complete methodology is described proposing an accurate reliability model from experimental determination of the failure mechanisms (defect diffusion) for this technology. Electrical and optical characterizations are used with temperature dependence, short‐duration accelerated tests (less than 1500 h) with an increase in bias current (up to 50%), a small number of samples (less than 20) and weak acceleration factors (up to 240). Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
159.
简述了计算运动学的发展过程,论述了计算运动学的基础理论,并利用两个实例展现了计算运动学在机构运动分析中的作用。最后以转向机构综合为例,对比传统综合方法和现代计算运动学方法的特点。结果表明:计算运动学方法在寻找所有解,精度和系统性等方面具有较大的优势。 相似文献
160.
Gönül Turhan-SayanAuthor Vitae 《Pattern recognition》2003,36(7):1449-1466
This paper presents a model-based electromagnetic feature extraction technique that makes use of time-frequency analysis to extract natural resonance-related target features from scattered signals. In this technique, the discrete auto-Wigner distribution of a given signal is processed to obtain a partitioned energy density vector with a significantly reduced sensitivity to aspect angle. Each partition of this vector contains, in the approximate sense, spectral distribution of the signal energy confined to a particular subinterval of time. Selection of sufficiently late-time partitions provides target features with a markedly increased target discrimination capacity. The potential of the suggested technique and the practical issues in its implementation are demonstrated by applying it to realistic target classification problems with very encouraging results. 相似文献