工业CT技术在卫星产品检测中的应用

卫星产品许多都采用了焊接结构。为了保证其使用的安全可靠性,必须对焊缝进行l00％的无损检测。然而对于一些形状复杂的精密电子束焊件,由于产品尺寸小,加之焊缝周围结构的遮挡,使常规方法的应用受到了限制。工业CT技术具有不受试件材料种类、形状结构及表面状况限制的特点,能给出与试件材料密度及尺寸特性相对应的断层扫描图象,分辨率高,在检测复杂构件方面显示出了优势。本文介绍了卫星产品精密复杂焊接件对无损检测技术的具体要求,研究了卫星产品电子束焊缝的工业CT检测方法,包括设备、对比试样、检测工艺、评定方法等,并通过电磁阀、喷注器、自锁阀、减压器、加注/排放阀、单向阀、气滤、过滤器等具体产品检测实例,描述了工业CT技术在卫星产品检测中的应用。实际应用表明：工业CT是检测航天卫星产品精密复杂结构件焊缝缺陷的理想手段,其成象直观,缺陷的定位、定性和定量结果可靠,完全能满足产品的质量控制要求。目前,累计用工业CT检测卫星产品数批若干件,检测焊缝上千条。剔出有超标缺陷的产品40件,避免了隐患。经过工业CT检测的产品,己在"返回式卫星"、"风云二号"、"东方红三号"、"资源一号"、"中星-22号"等型号卫星中取得了成功应用。     

工业CT在复合材料孔隙率分析中的应用

目的：研究应用高分辨率工业CT系统对陶瓷基复合材料的孔隙率进行分析的方法，材料和方法：采用俄罗斯INDINTRO公司的BT－50高分辨工业CT系统对陶瓷基复合材料试样进行CT扫描，用自行编制的后处理软件对得到的CT图像进行分析，得出材料的孔隙率，结果：通过此方法得出的结果与超声检测结果相符，说明用高分辨率工业CT系统测定复合材料的孔隙率是可行的，同时对材料进行缺陷检测，密度分析等。     

导线线圈的射线层析检测

本文选用不同的方法对两个导线线圈进行了射线检测,主要采用透射式工业CT检测和康普顿背散射成像检测两种射线层析检测方法,有效检测了导线线圈内部的缺陷隋况,并指出射线层析检测作为一项新技术和新手段,可充分应用在航天产品的无损检测中。     

碳纤维复合材料气瓶的CT检测实验研究

目前国内碳纤维复合材料气瓶的定期检验对于内部缺陷还没有成熟的无损检测方法,射线检测可以对内部缺陷进行定性检测,CT检测技术可实现缺陷的精确定位和定量。针对某型号呼吸器用碳纤维复合材料气瓶的结构特点,依据有关定期检验标准,制作各种缺陷,开展CT检测实验研究。结果表明该技术对表面缺陷和纤维层内部缺陷都有很好的检出效果。以厚度2姗的铝内胆为基础,对缺陷的位置和深度进行了估算。     

工业CT在电磁线圈缺陷检测中的应用

通过工业CT（ICT）对电磁线圈进行内部结构分析,可以避免电磁线圈解剖的困难。ICT能有效地检测出电磁线圈中的漆包线断开、零部件安装不到位、漆包线熔断、绕组变形、包封层中气孔、多余杂线以及金属杂质等缺陷,并且能够精确地确定出缺陷的位置和几何形状。工业CT分析对提高电磁线圈产品的质量,改进生产工艺有指导意义。      

大型工业CT在机车关键部件无损检测中的应用

摇枕、侧架作为列车转向架的重要组成部分,对列车行驶安全起到至关重要的作用,各生产厂家亟须具有高穿透力的检测设备对其进行大批量的检测.本文介绍了应用于铁路机车关键部件无损检测的大型工业CT系统,论述了系统设计和扫描工作流程,并通过实例展示大型工业CT在摇枕、侧架等无损检测的应用情况.实际应用说明大型工业CT系统可对摇枕、侧架等关键部件的内部结构及内部的气孔、砂眼、夹杂物、缩孔、疏松、冷隔、裂纹等铸造缺陷进行快速有效检测,能够很好地满足该行业的需求.     

CV主动轮廓模型在管道焊缝缺陷检测中的应用

焊接是钢结构生产的主要方法。射线检测方法是检查焊接缺陷的几种主要方法之一。射线检测结果的评定方法有两种：人工评定和计算机辅助评定。人工评定检测结果时,评定人员工作量大,评定结果易受评定人员主观因素影响。采用计算机对X射线检测结果进行分析和识别,可以大大提高工作效率。分析识别的基础是图像的分割。本文分析Mumford—Shah模型和主动轮廓的CV模型,并将其首次应用到焊缝缺陷的分割之中。目前多数文献选择单个初始圆为曲线演化的初始轮廓,本文将初始轮廓选择为多个初始圆,此方法极大加快了曲线演化的速度。     

人工智能辅助规培医师对不同大小肺实性结节检出效能的初步研究

目的:探讨人工智能（AI）辅助检测软件对低年资规培医生提高肺实性结节检出效能的临床应用价值。方法:收集200例经CT证实有肺实性结节的CT影像,由2名8年影像诊断工作的主治医师结合AI （SCHOLAR,infervision）共同阅片确定肺实性结节数量,分歧时由第3名从事影像诊断15年以上主任医师会诊,最终确定“金标准”。先由低年资规培医师对上述CT图像独立进行肺结节检测（方法A）,2周洗脱期后在AI软件辅助下再进行上述CT图像肺结节检测（方法B）。将方法A和方法B标注结果分别与“金标准”比较,记录真阳结节数、假阳结节数,采用SPSS 20.0数据统计软件比较两组间检测灵敏度、假阳性率差异,P<0.05为差异有统计学意义。结果:与方法A相比,方法B灵敏度明显增加,总的实性结节灵敏度提高65%,而假阳性率降低25%,差异有统计学意义（P<0.05）;应用AI辅助软件对检测4组不同大小（D≤4 mm、4 mm 8 mm）肺实性结节的灵敏度均有提高,分别为78%、38%、27%和13.8%。方法A的FROC曲线上面积（AAC）为0.176,方法B为0.085 2,差异有统计学意义（P<0.05）;方法A和方法B平均每例CT阅片时间分别为411.9 s和319.7 s。结论:AI辅助检测软件可明显提高低年资规培医师对CT上不同大小肺实性结节的检出效能,尤其对直径≤4 mm肺结节的检出更具优势。      

高能射线工业CT最新进展

本文主要介绍了清华大学在高能射线工业CT研究及产业化方面的新进展,介绍了其中的多项成果:小体积、大功率的直线加速器,低噪声、高效率的阵列固体探测器,旋转极坐标反投影快速图像重建算法等.高能工业CT技术的研制成功及产业化,使我国高能工业CT技术达到国际先进水平,结束了我国无自主研制大型工业CT检测系统的历史,解决了我国大型工件无损检测难题,对提高我国高能无损检测技术水平具有重大意义.     

工业计算机断层扫描仪(工业CT)研制报告

工业CT(ICT)是用于工业产品进行无损检测和探伤的先进仪器。ICT技术能紧密、准确地再现物体内部的三维立体结构,能够定量地提供物体内部的物理、力学等特性,如缺陷的位置及尺寸、密度的变化及水平,异型结构的形状及精确尺寸,物体内部的杂质及分布等。ICT的功能和特性在许多方面越过X光和超声检测,为航空、航天、兵器等工业领域的精密零部件的无损检测提供了新的手段。该技术研制成功并荣获1994年度亚洲CT技术十大科技进展成果奖。有关专家认为该技术居国内先进水平,与国际水平相当。我们研制开发的工业CT机已经为中国航空材料研究所、中国运载火箭技术研究院、兵器工业总公司等多家科研、生产单位进行了各种零件的测试。     

石英丝弹性元件的研究与制作

本文介绍了烧焊熔凝石英的实验设备,拉制及焊接石英丝、石英弹簧等元件的技术。同时,还简要介绍了熔凝石英的物理、化学特性和应用情况。     

图像处理在X射线胶片缺陷识别中的应用

本文针对油气管道焊缝射线检测胶片的实际情况,提出一种用于气孔缺陷检测的方法,应用数字图像处理技术对气孔缺陷进行量化分析,并实现计算机辅助评片.     

焊接残余应力对铁路钢桥焊缝区域危险点列车振动动应力影响的研究

本文研究了焊接残余应力对铁路钢桥焊缝区域危险点列车振动动应力的影响.文中,以铜九线鄱阳湖铁路钢桁架桥梁为研究背景,采用符合电弧焊的双椭球热源模型,模拟出桥梁焊缝区域的焊接残余应力分布情况;旧时叠加上铜九线鄱阳湖铁路钢桁架桥与焊缝节点连接的构件在列车过桥时的实测动应力,并将其施加在桥梁节点精确有限元模型上,分析得出在不同...     

基于改进模态参数灵敏度法的结构损伤识别研究

推导了模态参数对于损伤构件的一阶和二阶灵敏度矩阵,并对在推导一阶和二阶振型灵敏度的过程中产生的模态截尾误差进行了改进。根据泰勒级数展开的原理分别建立了一阶和二阶的灵敏度方程。考虑到一阶灵敏度方程求解速度快和二阶灵敏度方程求解精度高的特点,本文提出了一种用于结构损伤识别的混合迭代算法,该算法用二阶非线性的解析解作为算法的第一次迭代值,用一阶灵敏度方程的求解值对该算法的第一次迭代值进行关于泰勒级数截尾误差的修正。研究表明,本文提出的混合迭代算法由于采用了精确度较高的二阶非线性解析解作为迭代修正的初值,因此,迭代修正精度更高,收敛性更好。     

基于地质统计理论的储集层潜在伤害钻前预测方法

储集层潜在伤害预测研究是各项作业方案设计的依据.应用地质统计的区域化变量理论和其估计、模拟处理方法,针对钻前情况,在储集层潜在伤害空间特性分析的基础上,建立了储集层潜在伤害钻前预测方法,并以胜利某油田区块Es₂地层水敏伤害结果为例进行了钻前预测.结果表明,该方法在钻前情况下给出了该区块的水敏指数分布,且预测分布结果与该区块实际水敏指数分布情况相符,提出的储集层潜在伤害钻前预测方法切实可行.     

Seismic rehabilitation performance of steel side plate moment connections

Moment connections in an existing steel building located in Kaohsiung, Taiwan were rehabilitated to satisfy seismic requirements based on the 2005 AISC seismic provisions. Construction of the building was ceased in 1996 due to financial difficulties and was recommenced in 2007 with enhanced connection performance. Steel moment connections in the existing building were constructed by groove welding the beam flanges and bolting the beam web to the column. Four moment connections, two from the existing steel building, were cyclically tested. A non‐rehabilitated moment connection with bolted web‐welded flanges was tested as a benchmark. Three moment connections rehabilitated by welding full‐depth side plates between the column face and beam flange inner side were tested to validate the rehabilitation performance. Test results revealed that (1) the non‐rehabilitated existing moment connection made by in situ welding process prior to 1996 had similar deformation capacity as contemporary connection specimens made by laboratory welding process, (2) all rehabilitated moment connections exhibited excellent performance, exceeding a 4% drift without fractures of beam flange groove‐welded joints, and (3) presence of the full‐depth side plates effectively reduced beam flange tensile strain near the column face by almost half compared with the non‐rehabilitated moment connection. The connection specimens were also modeled using the non‐linear finite element computer program ABAQUS to further confirm the effectiveness of the side plate in transferring beam moments to the column and to investigate potential sources of connection failure. A design procedure was made based on experimental and analytical studies. Copyright © 2009 John Wiley & Sons, Ltd.     

结合灵敏度修正的遗传算法的结构损伤诊断

提出了1种结合灵敏度修正的遗传算法进行结构损伤诊断。在遗传算法计算过程中加入灵敏度修正操作,使遗传过程得以快速收敛并增加了识别准确性。利用4层平面框架进行数值模拟,识别结果表明,本文所提出的结构损伤识别方法比常规遗传算法有效。     

Inversion of dynamic production data for permeability: fast streamline-based computation of sensitivity coefficients of fractional flow rate

Generation of permeability field in a reservoir model that matchs historical dynamic production data requires an inverse calculation. A gradient method is typically used to solve the inverse minimization problem and requires sensitivity coefficients of reservoir responses, e.g. fractional flow rate or pressure, with respect to the change in the permeability. This paper presents a novel semi-analytical streamline-based method for computing such sensitivity coefficients under the framework of two-phase (oil-water) flow conditions. This method is shown to be significantly faster and generate permeability fields with lower objective function than the traditional perturbation method. The method decomposes the multiple-dimensional full flow problem into multiple 1D problems along streamlines. The sensitivity of fractional flow rate at the production well is directly related to the sensitivity of time-of-flight (TOF) along each individual streamline and the sensitivity of pressure at grid cells along the streamline. The sensitivity of TOF of a streamline can be obtained analytically. The sensitivity of pressure is obtained as part of a fast single phase flow simulation. The proposed method is implemented in a geostatistically based inverse technique, called the sequential self-calibration (SSC) method. Results for fractional flow rate sensitivities are presented and compared with the traditional perturbation method. This new method can be easily extended to compute sensitivity coefficients of saturation (concentration) data.     

Ranking welding intensity in pyroclastic deposits

Welding of pyroclastic deposits involves flattening of glassy pyroclasts under a compactional load at temperatures above the glass transition temperature. Progressive welding is recorded by changes in the petrographic (e.g., fabric) and physical (e.g., density) properties of the deposits. Mapping the intensity of welding can be integral to studies of pyroclastic deposits, but making systematic comparisons between deposits can be problematical. Here we develop a scheme for ranking welding intensity in pyroclastic deposits on the basis of petrographic textural observations (e.g., oblateness of pumice lapilli and micro-fabric orientation) and measurements of physical properties, including density, porosity, point load strength and uniaxial compressive strength. Our dataset comprises measurements on 100 samples collected from a single cooling unit of the Bandelier Tuff and parallel measurements on 8 samples of more densely welded deposits. The proposed classification comprises six ranks of welding intensity ranging from unconsolidated (Rank I) to obsidian-like vitrophyre (Rank VI) and should allow for reproducible mapping of subtle variations in welding intensity between different deposits. The application of the ranking scheme is demonstrated by using published physical property data on welded pyroclastic deposits to map the total accumulated strain and to reconstruct their pre-welding thicknesses.Editorial Responsibility: T. Druitt     

Miocene rhyolitic welded tuff infilling a funnel-shaped eruption conduit Shiotani, southeast of Matsue, SW Japan

 At Shiotani, SW Japan, rhyolitic welded tuff forms a steep-sided funnel-shaped body, confined by Paleogene granitic rocks to an elliptical area 1–1.5 km across. The Shiotani welded tuff is pervasively welded and foliated concordantly with the contact that dips inward at angles of 70–90°. In contrast, nearby contemporary volcaniclastic deposits are non-welded and gently inclined. Near the contact with the granite, the tuff is plastically deformed and shows lineations that plunge inward at angles of 40–65°. Lithic and crystal clasts in the rheomorphic outer part are rotated in a plane normal to the foliations and parallel to the lineations indicating downward flow of the welded tuff. The geometry and internal structures suggest that the Shiotani welded tuff was emplaced and welded in a funnel-shaped eruption conduit. Upon collapse of a plinian or phreatoplinian eruption column, the majority of the conduit-filling pyroclasts probably fell back en masse into the conduit. Heat and steam from underlying magma and diffusion of interstitial volatiles into the glass perhaps reduced the viscosity of juvenile pyroclasts and facilitated welding in the conduit, especially at deep levels. The hot welded pyroclasts then flowed down the conduit wall during welding compaction and retreat of the magma. These processes resulted in increased welding toward the contacts and welding foliations concordant with the steep wall. Emplacement of nearby correlative volcaniclastic mass-flow deposits in a shelf to upper bathyal environment suggests a possibility that, when active, the Shiotani conduit was under the sea. Welding compaction would occur even under the sea provided that the steam generated in the upper part of the conduit fill prevented water access. Received: 28 February 1996 / Accepted: 5 May 1997