聚乙烯管道电熔接头缺陷超声相控阵成像模拟和实验研究

为了快速获得电熔接头超声成像图以便研究聚乙烯管道电熔接头无损评估算法研究,运用了多物理场耦合有限元分析软件COMSOL Multiphysics对聚乙烯管道电熔接头金属电热丝的超声响应特性进行了有限元分析,并对聚乙烯管材内壁钻孔缺陷及含孔洞缺陷聚乙烯管道电熔接头进行了超声相控阵检测成像实验,验证了超声相控阵检测成像有限元模拟分析结果的正确性。采用Richardson-Lucy反卷积算法对聚乙烯管材内壁钻孔缺陷超声相控阵成像图进行了图像复原处理。实验结果表明:基于超声傅里叶成像的相控阵成像仿真方法具有可行性,有限元模型为聚乙烯管道电熔接头缺陷超声相控阵成像提供了数值模型。     

复合材料缺陷的脉冲热成像有限元模拟研究

针对脉冲红外热成像对复合材料的无损检测能力问题,利用有限元数值分析法模拟了脉冲加热红外成像无损检测过程。建立了"在复合材料上表面施加不同的热流边界条件",而在其下表面施加自然对流换热边界条件的有限元模型,研究了不同复合材料内部缺陷对材料表面温度分布产生的差别,具体研究了脉冲形状、脉冲加热时间、缺陷类型等因素对含有平底孔缺陷复合材料表面温差变化和对比度变化的影响。研究结果表明,缺陷深度越浅且越大,表面温差和对比度会越大;而热流量越大,表面温差越大,但对比度不变。该有限元模拟为研究脉冲加热红外热成像的复合材料缺陷检测提供了数值模型。     

基于热成像的埋地热力管道缺陷检测试验研究

为了研究埋地热力管道缺陷检测、泄漏定位问题,根据相似性原理搭建埋地热力管道泄漏试验平台,利用红外热像仪对3种不同工况的埋地管道上方地表进行探测,分析热力管道上方地表红外热像、最大差值辐射温度和差值温度分布变化特征。结果表明,埋地管道泄漏时,红外热像上漏点周围会呈现椭圆形高温区、温度梯度区与自然温度区,高温区内温度最大点往往对应漏点的位置,温度梯度区代表泄漏的影响范围。管道泄漏时最大差值辐射温度升温速率最快,分别是管道保温层破损和管道无破损的2倍和4倍,其差值温度分布直方图由正态分布演变为偏态分布。所提出的根据热像图的像素计算埋地管道泄漏影响区域的实际面积以及根据最大温度点的坐标确定泄漏点位置的方法,可实现管道泄漏影响评估和漏点准确定位。     

一种多功能运行工况检测装置的研究

利用红外热成像仪对机器设备、管道内部等情况进行故障检查是现有技术中比较常见的方法,但常规的红外热成像探测器一般只具有一个红外热成像的探头,只能根据温度来对机器设备、管道内部的故障进行位置大致检查,无法深入的检测故障的具体发生位置和情况,而且现有技术中的红外热成像探测器基本是单一的仪器,检测范围具有一定的局限性,使用灵活性也相对较差。本文结合河源供电局运维人员最新职工技术创新成果,研究多功能型的设备检测方式。     

含缺陷城镇燃气聚乙烯管道内压承载能力研究

聚乙烯管道在城镇燃气行业中有广泛的应用,但是目前国内外对在用聚乙烯管道的安全性能评价的研究相对较少,导致在检验检测过程中无法对发现的缺陷开展合于使用评价,从而无法准确判断含缺陷聚乙烯管道的安全状况。选取两种典型的聚乙烯管道材料PE80和PE100,在拉伸性能测试的基础之上,建立起了材料的本构模型,采用有限元模拟的方法,对选取的9种缺陷模型开展极限承载能力的分析与研究,初步确定了缺陷尺寸与承载能力的关系,为后续开展含缺陷聚乙烯管道的合于使用评价工程应用提供参考。     

基于有限元方法的钢板焊缝缺陷红外无损检测

应用有限元方法于红外无损检测中，利用大型有限元分析软件ANSYS，构建不同尺寸、深度的缺陷，施加单面局部热流，计算被测物体表面的温度分布，借助图像处理得到表面温度分布云图，根据热像特征和表面温升，从定性和定量上得到对缺陷更为可信的判定。工作重点在于研究缺陷尺寸、位置与表面温度间的关系，旨在使红外无损检测从定性检测向定量检测接近，为制定焊缝缺陷准确可靠的检测标准提供依据。     

红外热成像技术在石化企业的应用研究

现代科学采用特殊的光电红外探测器对各种波长的红外线进行收集处理,进而转化为电信号,再利用现代热成像技术,将物体表面的温度分布情况以图像的形式呈现出来,这种图像就是红外热像图。本文简述了红外热成像技术的工作原理,通过具体实列介绍了红外热像仪在石化企业的应用,为石化企业设备管理提供了帮助。     

固体火箭包覆层脱粘调制红外热波检测法的数值模拟

调制红外热波无损检测是一种可以检测材料内部缺陷的先进技术,在固体火箭发动机包覆层脱粘的诊断中有一定的应用前景.以有限元法对固体火箭发动机包覆层脱粘的调制红外热波检测法进行数值模拟,研究加热条件和结构对可检测性的影响.得出可检信息参数(表面过余温度幅值、相位和相位差)随热波激励条件(调制频率、热流强度)和结构参数(材料、...     

红外图像处理技术在金属表面缺陷检测中的应用

红外热成像技术用于金属材料产品表面缺陷检测时,具有图像对比度低、噪声较大、缺陷目标小等特点,因此图像处理是进行红外热成像无损检测的重要基础.本文在含缺陷钢制试件红外热像检测实验的基础上,利用直方图均衡化、高频强调滤波、区域生长等多种图像处理技术,实现了裂纹、圆孔等不同类型缺陷时缺陷几何特征信息的提取与识别,并考虑了腐蚀因素的影响.论文的研究为最终开发出基于红外热成像技术的缺陷自动检测和识别系统奠定了基础,对于应用红外热成像技术进行产品质量控制和结构健康监测具有良好的参考价值.     

基于红外锁相法的热波检测技术及缺陷深度测量-1

红外锁相法热波检测技术（Lock-in Thermography）是一种基于热波处理的主动式红外热成像检测技术,适用于复合材料及复杂结构构件的无损检测,已广泛应用于航天航空、汽车、机械、电力等领域。本文着重介绍了阐述了红外锁相法热波检测技术的原理、缺陷深度测量及在蜂窝夹层结构及焊接构件检测中的应用。采用有限差分法计算了强度按正弦规律变化热流引起试件表面温度变化历程,并采用锁相法提取了有缺陷与无缺陷处的稳态温度变化和计算二者相位差,与试验结果接近。建立了热波在试件中传导的热—电等效模型,利用该模型对红外锁相法热波检测技术进行了仿真研究,得到了缺陷深度和反射热波与入射热波相位差之间的关系,该模型计算结果与试验结果基本一致。采用红外锁相法热波检测技术对模拟缺陷的蜂窝夹层结构试件和实际的焊接构件进行了无损检测试验研究,结果表明,采用红外锁相法热波检测技术能够快速、准确的获得缺陷大小、位置等,该技术对具有复杂曲面结构的构件也十分优越。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.