Explanation of Anomalous Diffractive Behavior with New Model in Doped KNSBN Crystals

ＥｘｐｌａｎａｔｉｏｎｏｆＡｎｏｍａｌｏｕｓＤｉｆｆｒａｃｔｉｖｅＢｅｈａｖｉｏｒｗｉｔｈＮｅｗＭｏｄｅｌｉｎＤｏｐｅｄＫＮＳＢＮＣｒｙｓｔａｌｓ￥ＬＩＹａｎｑｉｕ；ＨＯＵＦａｎｇｌｉｎ；ＺＨＯＵＧｅｎｇｆｕ；ＸＵＫｅｂｉｎ；ＨＯＮＧＪｉｎｇ（Ｄｅｐ...     

Tunable Solid-State Laser Using Organic Dye DCM Doped ORMOSIL

ＴｕｎａｂｌｅＳｏｌｉｄ－ＳｔａｔｅＬａｓｅｒＵｓｉｎｇＯｒｇａｎｉｃＤｙｅＤＣＭＤｏｐｅｄＯＲＭＯＳＩＬ￥ＹＥＨｕｉ；ＨＵＷｅｎｔａｏ；ＪＩＡＮＧＺｈｏｎｇｈｏｎｇ（ＳｈａｎｇｈａｉＩｎｓｔｉｔｕｔｅｏｆＯｐｔｉｃｓａｎｄＦｉｎｅＭｅｃｈａｎｉｃｓ...     

3-methyl-4-metroxy-4'-nitrostilbene (MMONS) Crystal Growth and Studies of It

３－ｍｅｔｈｙｌ－４－ｍｅｔｒｏｘｙ－４＇－ｎｉｔｒｏｓｔｉｌｂｅｎｅ（ＭＭＯＮＳ）ＣｒｙｓｔａｌＧｒｏｗｔｈａｎｄＳｔｕｄｉｅｓｏｆＩｔｓＳｅｃｏｎｄＮｏｎｌｉｎｅａｒＯｐｔｉｃａｌＰｒｏｐｅｒｔｉｅｓ￥ＣＡＯＹａｎｇ；ＺＨＵＺｈｉｄｏｎｇ；ＨＵＡ...     

Laser Cooling and Trapping of Sodium Atoms in Magneto-optical Trap

ＬａｓｅｒＣｏｏｌｉｎｇａｎｄＴｒａｐｐｉｎｇｏｆＳｏｄｉｕｍＡｔｏｍｓｉｎＭａｇｎｅｔｏ－ｏｐｔｉｃａｌＴｒａｐ￥ＬＩＵＸｕｎｍｉｎｇ；ＬＩＮＹｕｅｍｉｎｇ；ＺＨＯＵＳｈａｎｙｕ；ＨＵＯＹｕｎｓｈｅｎｇ；ＷＡＮＧＹｕｚｈｕ（Ｌａｂｏｒａｔｏｒｙｆｏ...     

A Quenched Dye Laser Pumped by a KrF Excimer Laser

ＡＱｕｅｎｃｈｅｄＤｙｅＬａｓｅｒＰｕｍｐｅｄｂｙａＫｒＦＥｘｃｉｍｅｒＬａｓｅｒ￥ＸＵＥＳｈａｏｌｉｎ；ＬＯＵＱｉｈｏｎｇ；ＨＵＡＮＧＨｕｉｊｉｅ；ＤＵＬｏｎｇｌｏｎｇ（ＳｈａｎｇｈａｉＩｎｓｔｉｔｕｔｅｏｆＯｐｔｉｃｓａｎｄＦｉｎｅＭｅｃｈａｎｉ...     

HMO in nonlinear optics

ＨＭＯｉｎｎｏｎｌｉｎｅａｒｏｐｔｉｃｓＧＵＯＨｏｎｇ；ＬＩＮＴａｏ；ＷＡＮＧＧａｎｇ；ＤＥＮＧＸｉｍｉｎｇ（ＮａｔｉｏｎａｌＬａｂｏｒａｔｏｒｙｏｎＨｉｇｈＰｏｗｅｒＡｕｓｅｒａｎｄＰｈｙｓｉｃｓ，ＳｈａｎｇｈａｉＩｎｓｔｉｔｕｔｅｏｆＯｐｔｉｃｓ...     

Diode-Pumped Monolithic Nd:LMA Laser

Ｄｉｏｄｅ－ＰｕｍｐｅｄＭｏｎｏｌｉｔｈｉｃＮｄ：ＬＭＡＬａｓｅｒ￥ＬＵＪｉａｎｇ；ＨＵＡＮＧＺｈａｏｍｉｎｇ；ＪＩＮＺｈｅｎｈｏｎｇ；ＷＡＮＧＹａｎｇｊｕｎ（ＯｐｔｉｃａｌＦｉｂｅｒＩｎｓｔｉｔｕｔｅ，，ＳｈａｎｇｈａｉＵｎｉｖｅｒｓｉｔｙｏｆＳｃ...     

Polarization Spectral Hole-Burning in Organic Materials

ＰｏｌａｒｉｚａｔｉｏｎＳｐｅｃｔｒａｌＨｏｌｅ－ＢｕｒｎｉｎｇｉｎＯｒｇａｎｉｃＭａｔｅｒｉａｌｓ￥ＹＩＮＹｕ；ＺＨＡＯＹｏｕｙｕａｎ；ＬＵＯＸｉａｏ；ＣＨＥＮＬｉｎｇｂｉｎｇ；ＬＩＦｕｍｉｎｇ（ＯｐｅｎｉｎｇＬｏｂｏｒａｔｏｒｙｆｏｒＭａｔｅｒｉ...     

Nonlinear Evolution of Driven Electron Plasma Oscillations in Inhomogeneous Plasmas

ＮｏｎｌｉｎｅａｒＥｖｏｌｕｔｉｏｎｏｆＤｒｉｖｅｎＥｌｅｃｔｒｏｎＰｌａｓｍａＯｓｃｉｌｌａｔｉｏｎｓｉｎＩｎｈｏｍｏｇｅｎｅｏｕｓＰｌａｓｍａｓ￥ＳＨＥＮＧＺｈｅｎｇｍｉｎｇ；ＸＵＺｈｉｚｈａｎ；ＹＵＷｅｉ；ＭＡＪｉｎｘｉｕ（ＳｈａｎｇｈａｉＩｎ...     

Design of Metal-clad Ti: LiNbO_3 Polarizer

ＤｅｓｉｇｎｏｆＭｅｔａｌ－ｃｌａｄＴｉ：ＬｉＮｂＯ＿３ＰｏｌａｒｉｚｅｒＨＵＨ．Ｚ．，ＣＨＥＮＧＧ．（ＤｅｐａｒｔｍｅｎｔｏｆａｐｐｌｉｅｄＰｙｓｉｃｓ，ＴｉａｎｊｉｎＵｎｉｖｅｒｓｉｔｙ，Ｔｉａｎｊｉｎ３０００７２，Ｃｈｉｎａ）ＧＥＮＦ；ＳＯＮＧ...     

The identification of weld defects by ultrasonic methods

In ultrasonic weld testing no satisfactory method has yet been evolved for the reliable identification of defects. The author of this article suggests an ultrasonic code for weld defects: the physical quantities that are measured in an ultrasonic test are analysed and then the values of these quantities are estimated for the major weld defects. Those defects which give the same responses are grouped together to form the code. The code is theoretical and there is an urgent need for an experimental programme to establish the correlation between weld defects and their ultrasonic responses. The article is based on a memorandum presented at the Select Conference on Ultrasonic Weld Inspection organized by the Institute of Welding in May 1963.     

不同焊接位置对5A90铝锂合金激光焊接质量的影响(英)

针对铝锂合金激光焊接产生的成形不良和气孔缺陷,探究不同焊接位置对焊缝成形及气孔的影响,并对比分析不同焊接位置熔池受力状态、熔融金属流动和小孔动态行为,解释缺陷形成及其抑制机理。研究发现:不同焊接位置熔池受力状态和熔融金属流动决定焊缝成形。平焊时焊缝成形差、下榻严重;横焊时背面焊缝不连续,有飞溅;立向上焊时背面焊缝内凹严重;立向下焊可得到最优焊缝成形和最优的气孔缺陷。焊缝气孔受小孔动态行为影响,不同焊接位置气孔随热输入的变化规律一致,气孔先增后减,在仅熔池透状态下有气孔最大值。立上焊时小孔不稳定,焊缝气孔多且分布杂乱;立向下焊时小孔稳定性高,气孔最少,主要分布在焊缝中心线上。     

Ultrasonic reflection properties of planar defects within austenitic welds

Reflection of ultrasonic beams from the faces of planar weld defects is affected by the anisotropic nature of the weld material. The simple laws of geometrical reflection no longer hold and energy may be strongly reflected into unexpected directions. This has important consequences for ultrasonic inspection techniques relying on specular signals for defect detection. In this Paper a ray tracing approach is used to study, theoretically, the expected patterns of defect reflection behaviour for several weld types and several defect locations and orientations. In general we find that when the ultrasonic beam is generated in the austenitic weld material without first passing through the base metal then the strongly reflected specular signal travels in very unexpected directions. If, however, the ultrasonic beam travels into the weld metal via the base metal then reflected signals usually occur close to the expected directions, except for vertically polarized shear waves. Furthermore, for a given weld type it is obviously useful to minimize ultrasonic ray paths within the weld material, to minimize both attenuation and curvature of ray paths.     

B型套筒角焊缝缺陷相控阵超声检测定量方法

B型套筒修复作为油气管道修复的主要方式之一,在其修复的焊接过程中,该结构的环形角焊缝内部常常出现以气孔、夹渣为代表的孔型缺陷。这类缺陷由于角焊缝特殊的结构,在利用相控阵超声无损检测技术对其检测时,难以对其进行定量分析。通过数值模拟和实验,发现通过相控阵超声扇扫得到缺陷回波信号峰值与孔型缺陷直径呈正相关,为孔型缺陷的定量分析提供了一种可靠的手段。     

各向异性焊缝缺陷超声阵列全聚焦成像方法

针对奥氏体不锈钢焊接构件安全评价需要,对各向异性结构中超声波传播特性进行了研究,利用射线追踪法确定了各向异性介质中声波传播路径。在传统全聚焦成像基础上,发展了一种用于各向异性焊缝中缺陷检测的超声阵列全聚焦成像方法。通过数值仿真和实验,研究了介质材质对超声阵列成像的影响,结果表明,发展的全聚焦成像方法可以很好实现各向异性焊缝中缺陷检测,缺陷定位更准确。项目研究工作为奥氏体不锈钢焊缝检测提供了可行的技术方案.     

焊接薄板中S0兰姆波对槽型缺陷响应特性的数值研究*

采用数值仿真方法,就焊接薄板中S_0兰姆波对槽型缺陷的响应特性以及焊缝对S_0兰姆波槽型缺陷检测灵敏度的影响开展了数值研究。数值仿真结果表明,S_0_R信号(经槽型缺陷反射的S_0兰姆波回波信号)的反射比率随槽型缺陷深度的增大而单调增加;S_0_R信号的反射比率随槽型缺陷宽度的变化呈非单调变化关系,可将S_0_R信号的反射比率及其持续时间一并加以考虑,以评价槽型缺陷宽度的变化。随着焊缝余高的增加,S_0兰姆波对槽型缺陷的检测灵敏度将降低;随着焊缝宽度的增加,S_0兰姆波对槽型缺陷检测灵敏度的影响并不明显;相比之下,焊缝余高是影响S_0兰姆波槽型缺陷检测灵敏度的主要因素。研究结果表明,将S_0兰姆波用于检测隐藏于焊缝背后的槽型缺陷,是具有可行性的。所得结果对于发展焊接薄板的超声兰姆波无损检测技术,具有一定的理论指导意义和实际参考价值。     

基于卷积神经网络的焊缝缺陷图像分类研究

为有效地对焊缝缺陷进行分类,从而判断焊接质量的等级,对传统卷积神经网络进行改进,提出一种多尺度压缩激励网络模型（SINet）。将4组两两串联的3×3卷积模块与Inception模块、压缩激励模块（SE block）相结合。通过多尺度压缩激励模块（SI module）将卷积层中的特征进行多尺度融合和特征重标定以提高分类准确率,并用全局平均池化层代替全连接层减少模型参数。此外考虑到焊接缺陷数量不平衡对准确率的影响,采用深度卷积对抗生成网络（DCGAN）进行数据集的平衡处理,并在该数据集上验证模型的有效性。与传统卷积神经网络相比,该模型具有良好的性能,在测试集上准确率达到96.77%,同时模型的参数个数也明显减少。结果表明该方法对焊缝缺陷图像能进行有效地分类。     

Parametric optimisation and microstructural analysis on high power Yb-fibre laser welding of Ti–6Al–4V

In this work thin sheets of Ti–6Al–4V were full penetration welded using a 5 kW fibre laser in order to evaluate the effectiveness of high power fibre laser as a welding processing tool for welding Ti–6Al–4V with the requirements of the aircraft industry and to determine the effect of welding parameters including laser power, welding speed and beam focal position on the weld microstructure, bead profile and weld quality. It involved establishing an understanding of the influence of welding parameters on microstructural change, welding defects, and the characteristics of heat affected zone (HAZ) and weld metal (WM) of fibre laser welded joints. The optimum range of welding parameters which produced welds without cracking and porosity were identified. The influence of the welding parameters on the weld joint heterogeneity was characterised by conducting detailed microstructural analysis.     

Analysis of a fibre laser welding case study, utilising a matrix flow chart

For fibre laser welding of an eccentric corner joint, the quality of the resulting weld cross section was studied with respect to the dependence on process parameters like lateral laser beam alignment, beam inclination, focal plane position or welding speed. The complex load situation of the support beamer was simplified to bending of one corner. Due to fatigue load, the weld properties causing the peak stress are essential, in particular the top and root shape of the weld cross section. For the parameters varied, the resulting shapes were categorized into different top and root classes, determined by certain key dimensions, considering also welding defects like undercuts. The shapes are boundary conditions for Finite Element Analysis of the joint under load for quantitative comparative analysis of the maximum stress. As two high strength steel grades were joined, the hardness transition across the weld was of interest, too. High speed imaging of the weld pool surface shape provided additional information on the relation between the parameter input and quality output. The different trends identified were discussed and guidelines were derived. As the systematic documentation of results is unsatisfactory in welding, a new method was developed and applied for the first time, called the Matrix Flow Chart. It enables an illustrative view on the resulting welding trends in a combined manner and is extendable by other researchers.     

焊缝超声相控阵检测数据深度学习降噪方法

超声相控阵检测技术在焊缝检测中具有广泛的应用.超声相控阵检测技术检测信号中常混入噪声导致检测成像时难以分辨真实的缺陷特征.这些噪声主要为无关的反射信号和局部相关的结构噪声,传统的超声图像降噪方法难以有效滤除这些噪声,且存在计算效率低、参数优化复杂等问题.该文提出了一种基于深度学习的焊缝超声相控阵检测技术检测S扫图像的降...