钨铜材料电镀镍层常见缺陷分析及解决方法

就钨铜材料表面电镀镍层常见的孔洞、油污、鼓泡和腐蚀等缺陷进行了研究;采用扫描电镜和金相显微镜对缺陷形貌进了观察,并通过能谱分析对缺陷处元素组成进行了研究.研究结果表明:电镀层的孔洞是由于钨铜基材中存在较大孔洞造成的;油污是由于基材表面的针孔里残留有电镀液而引起的;鼓泡是由于钨铜基材表面存在氧化铝;腐蚀是因为电镀工艺不恰当引起的.还对不同缺陷提出了相应的解决方法.     

Circumferential higher order guided wave modes for the detection and sizing of cracks and pinholes in pipe support regions

The non-dispersive propagation of ultrasonic guided wave higher order modes cluster (HOMC) traveling along the circumferential direction in a hollow cylinder and its interaction with defects in pipe support regions is reported. These circumferential guided waves were generated in mild steel (MS) pipe specimens containing artificially created axial notches (simulating axial cracks) and pinholes (simulating pinhole-like defects) of different sizes in order to simulate conditions such as cracking and corrosion under pipe supports. The characteristics of these guided waves were also studied as a function of parameters related to how they were generated; namely, using: (a) 2.25 MHz linear phased array transducer, (b) 2.25 MHz conventional circular transducer and (c) 1 MHz conventional circular transducer. These higher frequency modes were explored for their ability to detect and size defects. Because of access limitations to the pipe support region in actual field testing, the transducer was always placed at a fixed circumferential position and moved axially along the length of the pipe. The defect position along the circumference was ascertained from the time of flight while the defect size was estimated using the amplitude data. The signals obtained for all three transducer configurations are compared for their ability to locate, detect and size the above-mentioned defects. It was shown that at these relatively higher frequencies, the guided wave modes exhibit small dispersion and have the ability to provide improved imaging of small size defects throughout the cross-section of the pipe.     

A novel technique for visualizing ultrasonic waves in general solid media by pulsed laser scan

This study proposes a novel technique to visualize ultrasonic waves propagated in a general solid medium. A specimen was scanned by a pulsed laser for generation of ultrasound, and the propagated waves were received by a fixed transducer. This technique then provided a snapshot of traveling waves based on the reversibility for the wave propagation, which is confirmed in this paper. We experimentally and numerically investigated and visualized the wave propagation in a steel plate with a slit. Furthermore, we demonstrated inspection of an elbow pipe with an artificial defect, as an application of the proposed technique to a structural component. Non-contact laser scanning for ultrasound excitation enabled us to inspect a wide area of an arbitrarily shaped object. The distinguishing advantages of this technique were determined to be well-suited to the quick and easy wide-range inspection of real structures.     

光纤缺陷的超声信号小波阈值去噪改进算法

光纤熔接缺陷的超声检测中,由于受噪声干扰,一些弱结合缺陷很难被正确检测出来。在多分辨分析小波阈值去噪方法基础上,提出了一种改进的闽值函数,并将其应用于缺陷信号的去噪。实际缺陷信号去噪结果表明,该算法与传统方法相比,具有重建信号均方误差小,信噪比高的优点,具有很好的去噪效果。     

济阳坳陷及鲁西隆起区中、新生代伸展与断裂活动特征

济阳坳陷与鲁西隆起具有相同类型的结晶基底.选取这两个地区近年来3条有代表性的大跨度深层反射地震剖面,重建盆地沉积岩层埋藏史,通过反复拟合盆地内部构造形态,定量计算各主要构造演化阶段的构造运动学参数,详细解析了基底伸展变形过程.结果表明济阳坳陷与鲁西隆起区基底伸展及断裂活动在时空上很不均衡,两个地区古近纪伸展变形强度均显著大于中生代;古近纪济阳坳陷南北向地壳伸展率和伸展速率均为东西向的两倍以上.     

Hundredhands

Directed by Sunitha Kondur and Bijoy Ramachandran, Hundredhands is a multidisciplinary design studio whose work draws on a keen sense of the urban. In their projects, often represented in patiently executed analytical drawings, the architects have redirected their focus on the urban context by returning to questions of scale, character, spatial and visual impact, and remaking the public domain, all of which is so vital to the tempestuous urbanism of Indian cities. Copyright © 2007 John Wiley & Sons, Ltd.     

管线断裂失效概率模型及计算

以相关管道档案、检验报告作为原始资料, 配合现场调查及观测, 采用“ 在役压力管道失效风险分析系统(SAPP)” , 对管线断裂失效风险进行分析。将管线中各缺陷安全状况与失效风险有机地结合起来, 在当前检测缺陷数据基础上, 通过适当选取概率模型, 计算管线的失效风险概率。对于准确了解管线的安全状态, 制定具有针对性的检修计划, 加强管线维护, 保障装置的安全稳定运行有重要的现实意义。     

THE DETERMINATION OF THE RESIDUAL STRESS DURING THE FATIGUE CRACK EXTENDSION

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The causes and costs of defects in construction: A study of seven building projects

To perform rational defect prevention, it is necessary to have knowledge about defects, their causes and associated costs. The purpose of the study presented here is to stimulate improvements by indicating where preventive measures are most effective as well as how to perform them. A study of defects in construction was performed during the period 1986–1990. A new and deeper study has been performed by the same research group during 1994–1996. Seven building projects have each been monitored during a 6 month-period. Observers spent 8 h a day at the site analysing and describing defects occurring. A total of 2879 defects have been collected and fully described, including their root causes. Formal interviews with 92 key persons have been made.     

吐哈盆地HYS反转构造及其平衡演化

吐哈盆地HYS构造从晚中生代至新生代经历了拉张伸展期、挤压抬升期、伸展拗陷期和强烈挤压褶皱期等演化阶段。拉张伸展期盆地引张伸展,断层为正断层,形成半地堑式构造单元;挤压抬升期,盆地受挤压抬升,断层活化为逆断层,伴随产生弱压缩褶皱;伸展拗陷期盆地再次引张伸展,断层转化为正断层,盆地呈拗陷沉降;强烈挤压褶皱期,受挤压应力场的作用,断层又活化为逆断层,并伴随断层产生相关的褶皱,形成了正反转构造和复杂的地层构造关系。后期的强烈挤压褶皱反转虽然形成了油气的聚集场所,但同时又破坏了构造圈闭的完整性及其保存条件,不利于构造油气藏的形成。