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应用BP神经网络识别内层表面细小缺陷的研究 被引量:1
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作者 朱鸿茂 饶云华 《应用声学》 CSCD 北大核心 2001年第5期12-15,共4页
内层表面细小凹坑的识别是扭声无损评估的一个难点.本文利用人工神经网络对于信号的分类功能,建构和训练了一个BP神经网络,并用它对尺寸为1mm的圆锥形和半球形两种凹坑成功地进行了识别.研究表明,应用凹坑回波的DCT 谱作... 内层表面细小凹坑的识别是扭声无损评估的一个难点.本文利用人工神经网络对于信号的分类功能,建构和训练了一个BP神经网络,并用它对尺寸为1mm的圆锥形和半球形两种凹坑成功地进行了识别.研究表明,应用凹坑回波的DCT 谱作为缺陷特征输入,可使BP神经网络的训练和缺陷识别既快捷又有效. 展开更多
关键词 BP神经网络 缺陷识别 DCT变换 内层表面 圆锥形凹坑 超声无损评估 半球形凹坑
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半金属摩阻制品中钢纤维取向状态对其摩擦性能影响的研究
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作者 吴培熙 瞿雄伟 《河北工业大学学报》 CAS 1990年第2期15-21,共7页
研究了钢纤维取向状态下半金属摩阻材料的摩阻性能,与铜纤维无规排布的相比,大多数取向状态均有明显的改性效果,在七种试样中摩擦系数以α=45°的最高.用扫描电镜及 x—射线能谱仪对α=45°的试样进行了摩擦表面层结构的表征,... 研究了钢纤维取向状态下半金属摩阻材料的摩阻性能,与铜纤维无规排布的相比,大多数取向状态均有明显的改性效果,在七种试样中摩擦系数以α=45°的最高.用扫描电镜及 x—射线能谱仪对α=45°的试样进行了摩擦表面层结构的表征,得到的物理模型为四层结构,即表面膜外层、表面膜内层、热分解层、热影响层. 展开更多
关键词 半金属摩阻材料 钢纤维 复合材料 酚醛塑料 表面膜外 表面内层
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THRUST NAPPE STRUTRUE IN THE JINGGANG MOUNTAIN: CHARACTERISTICS AND SIGNIFICANCE FOR PROSPECTION OF ORE DEPOSITS
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作者 CUI Xuejun, XIA Bin and ZHOU Jibin(Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry & South ChinaSea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, GD 510640, China Jiangxi Institute of Geological Survey, Nanchang, JX 330201, China) 《Geotectonica et Metallogenia》 2003年第1期1-10,共10页
Nappe structure, as was first discovered by the authors during the regional geological survey at the scale of 1:50,000 in The Jinggang Mountain, is mainly comprised of a series of NNE-NE-striking thrust fault zones an... Nappe structure, as was first discovered by the authors during the regional geological survey at the scale of 1:50,000 in The Jinggang Mountain, is mainly comprised of a series of NNE-NE-striking thrust fault zones and thrust sheets among them. Sinian, Cambrian, Ordovician, Devonian, Carboniferous,Triassic, Jurassic and Cretaceous strata are involved in the thrust nappe system. The nappe structure is of the type of duplex structures formed as a result of the earlier stage migration from SE to NW and late stage migration from E to W of sedimentary cover or basement strata. Formation of the nappe structure in the studied area involves two main epochs: Early Yanshanian and Late Yanshanian to Early Himalayan. The mineral deposits and the buried coalfields in the area, especially the latter, are extensively controlled by the nappe structure. 展开更多
关键词 thrust nappe structure Mesozoic inland deformation the Jinggang Mountain.
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Gas Absorption by Wavy Falling Liquid Film Formed on Inner Surface of Vertical lubes
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作者 Akio Miyara Tomoki Yamamoto +1 位作者 Toru Iemura Takashi Shimada 《Journal of Thermal Science》 SCIE EI CAS CSCD 2003年第1期57-61,共5页
An experimental study on gas absorption into falling liquid film formed on inner surface of vertical tubes has been carried out in order to clarify fundamental characteristics of the gas absorption and enhancement by ... An experimental study on gas absorption into falling liquid film formed on inner surface of vertical tubes has been carried out in order to clarify fundamental characteristics of the gas absorption and enhancement by surface waves. The water supplied into the test tubes is periodically disturbed by fluctuating a silicon tube before the test section with a speaker and the wavy films absorb the oxygen filled in the tubes. Imposing the periodic disturbance enhances the gas absorption and the enhancement has a maximum at around 20-30 Hz, where the gas absorption is 20-30% higher. Mass transfer coefficients obtained with five tubes agree well with those obtained with single tube. Two-dimensional numerical simulations have also been conducted for gas absorption by wavy film and the enhancement mechanism of the gas absorption is discussed. 展开更多
关键词 falling liquid film gas absorption surface wave vertical tube mass transfer enhancement.
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Influence of thickness and permeability of endothelial surface layer on transmission of shear stress in capillaries
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作者 ZHANG SongPeng ZHANG XiangJun +2 位作者 TIAN Yu MENG YongGang LIPOWSKY Herbert 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2015年第7期90-98,共9页
The molecular coating on the surface of microvascular endothelium has been identified as a barrier to transvascular exchange of solutes. With a thickness of hundreds of nanometers, this endothelial surface layer (ESL... The molecular coating on the surface of microvascular endothelium has been identified as a barrier to transvascular exchange of solutes. With a thickness of hundreds of nanometers, this endothelial surface layer (ESL) has been treated as a porous do- main within which fluid shear stresses are dissipated and transmitted to the solid matrix to initiate mechanotransduction events. The present study aims to examine the effects of the ESL thickness and permeability on the transmission of shear stress throughout the ESL. Our results indicate that fluid shear stresses rapidly decrease to insignificant levels within a thin transition layer near the outer boundary of the ESL with a thickness on the order of ten nanometers. The thickness of the transition zone between free fluid and the porous layer was found to be proportional to the square root of the Darcy permeability. As the per- meability is reduced ten-fold, the interfacial fluid and solid matrix shear stress gradients increase exponentially two-fold. While the interracial fluid shear stress is positively related to the ESL thickness, the transmitted matrix stress is reduced by about 50% as the ESL thickness is decreased from 500 to 100 nm, which may occur under pathological conditions. Thus, thickness and permeability of the ESL are two main factors that determine flow features and the apportionment of shear stress- es between the fluid and solid phases of the ESL. These results may shed light on the mechanisms of force transmission through the ESL and the pathological events caused by alterations in thickness and permeability of the ESL. 展开更多
关键词 endothelial surface layer transition layer Brinkman equation shear stress transmission glycocalyx thickness perme-ability
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