基于模态振型和L1正则化的结构损伤识别

考虑到基于2范数的正则化算法存在对结构识别结果过度光滑的效果,提出了基于模态振与L1正则化的损伤识别方法。以—2D简支梁有限元模型为数值算例,比较了使用不同振型数不同损伤程度对损伤识别效果的影响。数值模拟结果表明,对于多损伤工况,当损伤结构的振型数和无损结构的振型数乘积数大于6时,能较好地进行损伤定位,并能对损伤程度给出定性的描述。     

基于信息融合技术的结构损伤诊断方法

为提高结构损伤识别的准确率,将多源信息融合技术引入到结构损伤诊断中．在介绍多源信息融合技术的基本理论、功能模型、级别分类和数学方法的基础上,将2种或多种结构损伤识别方法提取的损伤特征向量进行特征级融合,建立了基于信息融合的结构损伤诊断方法．在钢筋混凝土板损伤试验中测试其模态信息,利用基于信息融合的结构损伤诊断方法进行裂缝位置识别,并与单独使用模态应变能法和柔度法进行损伤识别的结果进行对比．结果显示基于特征级信息融合的结构损伤诊断方法能够准确识别单一损伤识别方法无法识别的结构损伤,对于多位置损伤识别亦有效果．基于信息融合的结构损伤诊断方法具有良好的损伤敏感性．不同的信息融合算法有不同的适用范围,在实际结构健康监测中,要通过详细分析选择合适的多源信息融合算法．     

Statistical algorithm for damage detection of concrete beams based on piezoelectric smart aggregate

The functional piezoelectric ceramic smart aggregate(SA) sensors and actuators,based on piezoelectric ceramic materials such as lead zirconium titanate(PZT),were embedded into the reinforced concrete beams with three-point bending under static loading for purposes of damage detection.The SA actuators generated the desired sine sweep excitation signals online and the SA sensors received and detected real-time signals before and after damage.The wavelet analysis and statistical characteristics about damage signals were used as a signal processing and analysis tool to extract the optimal damage information and establish a statistical damage detection algorithm.The damage index-based wavelet analysis and damage probability-based probability and statistics were proposed by PZT wavebased theory and active health monitoring technology.The results showed that the existence of cracks inside largely attenuated the amplitude of active monitoring signal after the damage of beam and the attenuation was related to the severity degree of damage.The innovative statistical algorithm of damage pattern detection based PZT-SA can effectively determine damage probability and damage degree,and provide a prediction for the critical damage location of reinforced concrete structures.The developed method can be utilized for the structural health comprehensive monitoring and damage detection on line of various large-scale concrete structures.     

基于支持向量机的结构损伤识别

支持向量机是一种基于统计学习理论和结构风险最小化原则的新型机器学习算法。介绍了支持向量机分类概率估计和回归估计,构造基于模态频率的损伤指标标识量,根据分类概率估计与回归算法计算结构损伤位置及程度。通过简支梁仿真算例,验证了该方法的有效性。     

法海寺大雄宝殿结构解析与缺陷检测分析

北京法海寺因其国宝级壁画而闻名,壁画所在的大雄宝殿在经历了580年历史巨变后其结构状况不容乐观。对大雄宝殿的结构进行解析,指出其主要结构外观缺陷,对木构架变形检测结果进行分析,提出加固保护的建议,对大殿未来的科学修缮加固具有重要参考价值。     

Automatic damage detection of engineering ceramics ground surface based on texture analysis

Ground textures seriously interfere with the exact identification of grinding damage. The common nondestructive testing techniques for engineering ceramics are limited by their difficulty and cost. Therefore, this paper proposes a global image reconstruction scheme in ground texture surface using Fourier transform (FT). The lines associated with high-energy frequency components in the spectrum that represent ground texture information can be detected by Hough transform (HT), and the corresponding high-energy frequency components are set to zero. Then the spectrum image is back-transformed into the spatial domain image with inverse Fourier transform (IFT). In the reconstructed image, the main ground texture information has been removed, whereas the surface defects information is preserved. Finally, Canny edge detection is used to extract damage image in the reconstructed image. The experimental results of damage detection for the ground texture surfaces of engineering ceramics have shown that the proposed method is effective.     

一种利用时间序列分析的特征提取与损伤预警方法

针对结构健康监测中如何基于在线监测数据实现损伤诊断的问题,提出了一种利用时间序列分析ARMA模型的特征提取和损伤预警方法.首先对所有监测数据样本建立ARMA模型,以模型中AR部分参数的主成分矩阵构建Mahalanobis距离判别函数,提出了一种新的结构损伤敏感指标DDSF.然后,采用t-检验考察该指标在损伤前后是否存在显著性变化,从而可以有效地实现结构损伤预警.三跨连续梁数值算例表明,提出的结构损伤特征指标对结构的微小损伤具有敏感性,具备结构在线实时损伤预警的应用价值.     

基于小波包分析的大跨桥梁结构损伤预警的理论研究

基于小波包分析推导了结构动力系统在不同分析尺度上的状态方程和观测方程,在此基础上研究了结构动力响应在不同分析尺度上的时-频特性.理论分析证明,采用小波包分解结构的动力响应得到小波包能量谱,将可以表征结构损伤的发生.在此基础上进行了小波包能量谱关于结构损伤和观测噪声的敏感性研究,分析了结构系统矩阵和测量噪声在各个分析尺度上的递推性.结果表明,采用结构动力响应的小波包能量谱进行结构损伤预警具有较好的损伤敏感性和噪声鲁棒性.     

重动句的结构和语义分析

本文对重动句的结构和语义进行分析 :重动句由VP1和VP2两个结构一前一后的结合而成 ,VP1和VP2的句法地位基本相等 ,都可出现时体标记 ,都可受状语修饰 ;重动句是双语义焦点句 ,VP1和VP2在语义上有多种关系 ,两者互相依存 ,缺一不可     

有限元法在基础不均匀沉降引起的结构受损分析中的应用

建筑基础的变形以及由于基础不均匀沉降引起的上部结构受损情况很难用常规手段进行预测。文章结合现场实测数据,运用有限元分析方法,对某机车室基础不均匀沉降导致的结构受损情况进行建模和分析,查明了引起结构受损变形的主要原因,并对其分析结果进行了验证。     

长厚壁螺线管中的等效自感电动势和自感系数

分别用三种方法求出了长厚壁螺线管的自感系数.特别是第三种方法,先求等效自感电动势,再求自感系数,和传统的求解思路大不一样.可作为求解宽导体回路自感系数的一种新方法.     

叶片数控砂带磨床的磨削工艺分析及结构设计

针对汽轮机叶片的结构特点,结合砂带磨削的工艺特性,进行了叶片砂带磨削的工艺分析。在对叶片磨削运动分析的基础上,进行了叶片数控砂带磨床的总体结构设计,并对砂带磨床的关键结构件进行了力学性能有限元分析。     

A Systematic Evaluation and Comparison Between Exploratory Structural Equation Modeling and Bayesian Structural Equation Modeling

In this study, we contrast two competing approaches, not previously compared, that balance the rigor of CFA/SEM with the flexibility to fit realistically complex data. Exploratory SEM (ESEM) is claimed to provide an optimal compromise between EFA and CFA/SEM. Alternatively, a family of three Bayesian SEMs (BSEMs) replace fixed-zero estimates with informative, small-variance priors for different subsets of parameters: cross-loadings (CL), residual covariances (RC), or CLs and RCs (CLRC). In Study 1, using three simulation studies, results showed that (1) BSEM-CL performed more closely to ESEM; (2) BSEM-CLRC did not provide more accurate model estimation compared with BSEM-CL; (3) BSEM-RC provided unstable estimation; and (4) different specifications of targeted values in ESEM and informative priors in BSEM have significant impacts on model estimation. The real data analysis (Study 2) showed that the differences in estimation between different models were largely consistent with those in Study1 but somewhat smaller.     

Inclusive education and best practice for children with autism spectrum disorder: an integrated approach

Many parents of children with autism spectrum disorder (ASD) have reported general discontent with the services offered by the education system and have advocated for increased ASD‐specific services to better meet their children’s educational needs. The elements of best practice offer an ideal model for educational support. There are, however, limitations to advocating ASD‐specific services. This paper describes how best practice for ASD as an educational model fits within what is described as authentic inclusion. Further, it is suggested that the ASD community align with the greater inclusive education reform movement. With the use of this unified model of education, all children will receive the educational support they require.     

反例在数学教学中的作用与构造分析

举反例是数学中一种重要思维方式,反例在数学中有很多作用,一个数学真命题的确定往往需要严密的证明,而对假命题的判定如用反例来说明则显得容易理解。文章通过具体的例子阐述了反例在数学教学中作用的体现,构造分析简单例子,总结归纳出反例构造的方法,为数学解题以及实际数学教学提供参考价值。     

体育专业学生篮球运动损伤调查及其病理学分析

调查并分析体育专业学生篮球运动损伤的基本状况、损伤时段、以及损伤类型和损伤原因等方面,揭示体育专业学生篮球运动损伤发生的一般病理学规律和处理损伤的原则,最后提出若干建议。     

我国区域差距的结构性特征与发展趋势

本文认为 ,我国东、中、西三大区域之间和各省区之间不仅在经济总体发展水平上存在巨大的差距 ,更为严重的是在产业结构、企业规模等方面的经济质量上存在差距 ,若再考虑到技术水平、创新能力以及人力资源等因素 ,这种质量上的差距就更为突出。如果说经济总体发展水平上的差距可以通过加大投入来缩小的话 ,那么由结构、技术和人才决定的质量差距 ,就很难在短时期内消除。所以 ,我国区域经济发展的非均衡特征将会长期存在。     

直接采用二维多截面时步法有限元的斜槽异步电机模型

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高层剪力墙结构计算结果分析与判断

本文结合具体实例说明了在高层建筑结构设计中对计算结果进行分析、判断的必要性，并介绍了分析、判断的内容及应采取的相应措施，通过对计算结果进行分析，判断出其正确与否，确定是否需要对设计方案或输入数据进行修改以及应从哪些方面进行修改，使下一步的设计更加有针对性，从而避免设计工作中的盲目性，提高工作效率和设计的准确性。     

朔南矿区麻家梁井田构造特征及成因分析

在分析井田区域构造基础上,总结了井田主要褶曲形态、断层产状及变化规律,并分析了该区的构造形成机制及断裂构造对该区矿井开采的影响.