Development of surface reconstruction algorithms for optical interferometric measurement

Optical interferometry is a powerful tool for measuring and characterizing areal surface topography in precision manufacturing. A variety of instruments based on optical interferometry have been developed to meet the measurement needs in various applications, but the existing techniques are simply not enough to meet the ever-increasing requirements in terms of accuracy, speed, robustness, and dynamic range, especially in on-line or on-machine conditions. This paper provides an in-depth perspective of surface topography reconstruction for optical interferometric measurements. Principles, configurations, and applications of typical optical interferometers with different capabilities and limitations are presented. Theoretical background and recent advances of fringe analysis algorithms, including coherence peak sensing and phase-shifting algorithm, are summarized. The new developments in measurement accuracy and repeatability, noise resistance, self-calibration ability, and computational efficiency are discussed. This paper also presents the new challenges that optical interferometry techniques are facing in surface topography measurement. To address these challenges, advanced techniques in image stitching, on-machine measurement, intelligent sampling, parallel computing, and deep learning are explored to improve the functional performance of optical interferometry in future manufacturing metrology.     

Lamin-Related Congenital Muscular Dystrophy Alters Mechanical Signaling and Skeletal Muscle Growth

Laminopathies are a clinically heterogeneous group of disorders caused by mutations in the LMNA gene, which encodes the nuclear envelope proteins lamins A and C. The most frequent diseases associated with LMNA mutations are characterized by skeletal and cardiac involvement, and include autosomal dominant Emery–Dreifuss muscular dystrophy (EDMD), limb-girdle muscular dystrophy type 1B, and LMNA-related congenital muscular dystrophy (LMNA-CMD). Although the exact pathophysiological mechanisms responsible for LMNA-CMD are not yet understood, severe contracture and muscle atrophy suggest that mutations may impair skeletal muscle growth. Using human muscle stem cells (MuSCs) carrying LMNA-CMD mutations, we observe impaired myogenic fusion with disorganized cadherin/β catenin adhesion complexes. We show that skeletal muscle from Lmna-CMD mice is unable to hypertrophy in response to functional overload, due to defective fusion of activated MuSCs, defective protein synthesis and defective remodeling of the neuromuscular junction. Moreover, stretched myotubes and overloaded muscle fibers with LMNA-CMD mutations display aberrant mechanical regulation of the yes-associated protein (YAP). We also observe defects in MuSC activation and YAP signaling in muscle biopsies from LMNA-CMD patients. These phenotypes are not recapitulated in closely related but less severe EDMD models. In conclusion, combining studies in vitro, in vivo, and patient samples, we find that LMNA-CMD mutations interfere with mechanosignaling pathways in skeletal muscle, implicating A-type lamins in the regulation of skeletal muscle growth.     

Cell-envelope proteinases from lactic acid bacteria: Biochemical features and biotechnological applications

Proteins displayed on the cell surface of lactic acid bacteria (LAB) perform diverse and important biochemical roles. Among these, the cell-envelope proteinases (CEPs) are one of the most widely studied and most exploited for biotechnological applications. CEPs are important players in the proteolytic system of LAB, because they are required by LAB to degrade proteins in the growth media into peptides and/or amino acids required for the nitrogen nutrition of LAB. The most important area of application of CEPs is therefore in protein hydrolysis, especially in dairy products. Also, the physical location of CEPs (i.e., being cell-envelope anchored) allows for relatively easy downstream processing (e.g., extraction) of CEPs. This review describes the biochemical features and organization of CEPs and how this fits them for the purpose of protein hydrolysis. It begins with a focus on the genetic organization and expression of CEPs. The catalytic behavior and cleavage specificities of CEPs from various LAB are also discussed. Following this, the extraction and purification of most CEPs reported to date is described. The industrial applications of CEPs in food technology, health promotion, as well as in the growing area of water purification are discussed. Techniques for improving the production and catalytic efficiency of CEPs are also given an important place in this review.     

基于振动信号的深沟球轴承滚动体故障诊断研究

目前针对滚动轴承内、外圈故障的诊断方法较为有效,但难以诊断滚动体故障。针对这种情况,利用时域统计参数(有效值、峭度、脉冲因数、裕度因数)与Hilbert包络谱两种方法,对不同转速、负荷和故障程度情况下滚动体故障与正常状况的振动加速度数据进行比较分析,得出了滚动体故障难以诊断的原因,并给出了解决方法。     

控制吸力的非饱和土真三轴试验研究

基于西安理工大学的新型真三轴仪,在压力室底座与试样顶盖上分别安装高进气值陶土板与多孔板,从而增加孔隙气压力与孔隙水压力独立控制和量测装置,进而利用轴平移技术对基质吸力进行控制,并且新增水气控制面板和气动二联件对可控制吸力的真三轴仪进行了进一步完善。在此基础上初次尝试对重塑黄土进行了同时控制吸力(s=100 kPa)与净平均应力(p=300 kPa)为常数的真三轴固结排水剪切试验,分析了不同中主应力参数(b=0,0.25,0.5,0.75,1)条件下,各主应变(e_1,e_2,e_3)随偏应力(q)的变化情况;给出了重塑黄土在同时控制吸力与净平均应力路径下p平面上的破坏轨迹,并与Lade–Duncan强度破坏准则和Mohr–Coulomb强度破坏准则的预测破坏线进行了比较。     

建筑围护结构中热桥稳态传热计算研究

在实验室进行了稳态传热条件下热桥表面温度和热流强度的测试实验,将实验结果分别与二维稳态传热模拟软件PTDA的模拟计算结果及我国现行标准中规定的一维简化方法的计算结果进行了对比。结果表明,PTDA的模拟结果较精确,而现行标准中的简化方法的误差较大,应及时修订。     

双曲面网架轻钢屋盖围护结构设计简化计算方法的应用

针对南部沿海地区大跨度双曲面网架屋面抗台风的结构设计,择定风压、荷载、体型系数的计算取值,提出相应的简化计算方法。代表工程交验后,经多年实用及复测证明效果良好,荣获二等设计奖励,具有应用价值和推广意义。     

围护结构传热系数动态分析

分析了围护结构内表面热流的动态特性，得出了反映室外气候与围护结构热惰性共同作用的室外加权温度，并以此为基础讨论了夏季现场测量围护结构传热系数的有效性。     

城市住宅节能技术的优化探讨

根据国务院部署大力发展节能省地型建筑,建设节约型社会的要求,全面实施建筑节能50%设计标准,进而推动城市节能65%标准的实施。目前,我国大部分城市正在制订或者已经执行居住建筑节能65%的标准。如何将建筑的性能化节能指标转化为围护结构的热工性能指标,需要对节能50%设计标准的住宅热工性能现状进行分析总结,才有可能在技术上找到合理地提高住宅节能水平的设计方法。结合近年来西安市住宅围护结构的构造做法和热工性能,其节能指标与节能50%、节能65%标准的比较,找出目前住宅的热工性能指标与新标准的差距。据此提出应优先采用高效节能保温窗;墙体保温材料的选择要综合考虑保温层的特点、造价等因素;同时,对于因抗震设计而产生的热桥影响应引起高度重视,以寻求新的构造方式加强热桥部位的保温。