诱发性耳声发射阈同行为反应阈及听觉脑干反应阈间的相关性

本工作以疏波短声作为刺激声在３５位受试者（５８耳）分别测出诱发性耳声发射（ＥＯＡＥ）、行为反应（ＢＲ）及听觉脑干反应（ＡＢＲ）的阈值．闭值的主要分布范围：ＥＯＡＥ为１０－４５ｄＢ（ｎＨＬ），占总数的８６％；为１０－２５ｄＢ，占８８％；ＡＢＲ为１０－３５ｄＢ，亦占８８％．所有受试耳的三种阈值的相关系数ｒ：ＥＯＡＥ－ＢＲ为０．４１５（ｐ＜０．００２）．ＥＯＡＥ－ＡＢＲ为０．５０１（ｐ＜０．００１），ＡＢＲ－ＢＲ为０．７０２（ｐ＜０．００１），均呈显著相关．若仅取ＢＲ、ＡＢＲ或ＥＯＡＥ阈值≥２５ｄＢ的耳作统计，则ＥＯＡＥ－ＢＲ间的ｒ只有０．１７６及０．２９２；ＥＯＡＥ－ＡＢＲ的ｒ只有０．３１０及０．３００，无相关（ｐ＞０．０５），而ＡＢＲ－ＢＲ间的ｒ仍有０．５３３及０．７２０，（ｐ＜０．０５），这些结果表明ＥＯＡＥ与听阈之间只有在后者正常或稍升高时才有一定的相关，当听阈上升较多时相关即不存在．ＥＯＡＥ可以作为听力学检查的一种辅助方法，但不能用它推算听阈．     

超高能宇宙线广延大气簇射（EAS）观测阵列事例重建的研究

通过认真分析影响ＥＡＳ事例重建精度与速度的种种精细因素，采用适当的算法，设计，编制了具有一定的通用性的ＥＡＳ阵列事件重建程度ＥＡＳＦＩＴ。北京怀柔ＥＡＳ阵列采用ＥＡＳＦＩＴ后，改善了阵列综合测量精度与参数离线重建速度，并得到了该ＥＡＳ阵的一些重要的物理结果。     

书评

书评ＡＩＰＨＡＮＤＢＯＯＫＯＦＣＯＮＤＥＮＳＥＲＭＩＣＲＯＰＨＯＮＥＳＴｈｅｏｒｘＣａｌｉｂｒａｔｉｏｎａｎｄＭｅａｓｕｒｅｍｅｎｔｓＧｅｅｒｇｅＳ．Ｋ．Ｗｏｎｇ，ＴＯｎｙＦ．Ｗ．Ｅｍｂｌｅｔｏｎ主编３２１＋ＸＶｌｌ页（ＡｍｅｒｉｃａｎＩｎｓｔｉｔｕ...     

霍尔效应检测钢丝绳断丝

本文介绍了霍尔效应在钢丝绳断丝检测中的应用．     

DEUTERIUM INFLUX PROFILE ALONG THE APEX OF THE UPPER X-POINT TILES IN JET

ＤＥＵＴＥＲＩＵＭＩＮＦＬＵＸＰＲＯＦＩＬＥＡＬＯＮＧＴＨＥＡＰＥＸＯＦＴＨＥＵＰＰＥＲＸ－ＰＯＩＮＴＴＩＬＥＳＩＮＪＥＴ￥Ｙ．Ｋ．Ｚｈｕ（ＳｏｕｔｈｗｅｓｔｅｒｎＩｎｓｔｉｔｕｔｅｏｆＰｈｙｓｉｃｓ，Ｐ．Ｏ．Ｂｏｘ４３２，Ｃｈｅｎｇｄｕ６１００４１...     

PUSHING THE ENVELOPE IN RAMAN SPECTROSCOPY

ＰＵＳＨＩＮＧＴＨＥＥＮＶＥＬＯＰＥＩＮＲＡＭＡＮＳＰＥＣＴＲＯＳＣＯＰＹＧ．Ｄ．Ｐｉｔｔ（ＵｎｉｖｅｒｓｉｔｙｏｆＬｅｅｄｓａｎｄＲｅｎｉｓｈａｗｐｌｃＵ．Ｋ）ＮｅｗｔｅｃｈｎｉｑｕｅｓｈａｖｅｂｅｅｎｄｅｖｅｌｏｐｅｄｆｏｒＵＶＲａｍａｎｍｉｃｒ...     

AlGaN薄膜的微区Raman散射光谱研究

利用微区Ｒａｍａｎ散射技术,对低压ＭＯＣＶＤ生长的不同Ａｌ组分的ＡｌｘＧａ１－ｘＮ薄膜（ｘ＝０,０．０７,０．１５）进行了背散射Ｚ（Ｘ,Ｘ）Ｚ－几何配制下的测量．Ａ１（ＬＯ）模式的声子频移随Ａｌ组分的变化关系为：ω（ＡｌｘＧａ１－ｘＮ）＝（１＋０．２２０ｘ）ω（ＧａＮ）．观察到了Ａ１（ＬＯ）模式由于空间相关效应引起的展宽．Ｅ２模式随Ａｌ组分的的增大产生的移动很微小,但趋于展宽．这被认为是Ｅ２模式的声子频移随Ａｌ组分的增加而增大与其受到的张应力导致的声子频移随Ａｌ组分的增加而减小共同作用的结果．在多种配置下,观察到了Ａｌ０．０７Ｇａ０．９３Ｎ薄膜的Ａ１（ＴＯ）模式、Ａ１（ＬＯ）模式、Ｅ１（ＴＯ）模式和Ｅ２模式．验证了ＡｌｘＧａ１－ｘＮ薄膜的Ｒａｍａｎ选择定则．表明ＡｌｘＧａ１－ｘＮ薄膜具有单模行为．     

测定癌胚抗原的化学发光免疫分析新方法

使用自制的双吖啶发光示标识别１０,１０′－二甲基－３,３′－二磺酸基－９,９′－双吖啶（简称ＤＭＤＳＢＡ）标识抗癌胚抗原（ＣＥＡ）抗体,标识率达１．１５－１．３２。研究了标识反应、双抗夹心免疫反应和化学发光反应的条件,建立了一种测定ＣＥＡ的双抗夹心免疫分析新方法,测定ＣＥＡ的线性范围为１．０－１５０．０ｎｇ．ｍＬ＾－１,最小检测浓度为０．５３ｎｇ．ｍＬ＾－１。应用于人血清中ＣＥＡ含量的测定,结果与放射免疫法相关性良好。     

EXAFS研究负载型Ni／SiO2的区域结构

实验结果表明改进的实验室ＥＸＡＦＳ谱仪测试Ｎｉ箔的Ｋ吸收得到的ＥＸＡＦＳ谱与同步辐射上测量Ｎｉ箔得到的ＥＸＡＦＳ谱相近，利用实验室ＥＸＡＦＳ方法也可开展较好的结果测量研究，在ＳｉＯ２粉末载体上Ｎｉ负载量变化的ＥＸＡＦＳ结果表明，随着Ｎｉ负载量的降低，Ｎｉ的径向结构函数主配位峰的位置Ｒ＝０．２２０ｎｍ保持不变，但振幅强度逐渐降低。负载量从Ｎｉ箔到２．５％Ｎｉ／ＳｉＯ２，无序度因子σ由０．００６８ｎｍ     

TX100胶束中光解蒽醌的TRESR研究

用时间分辨电子自旋共振（ＴＲＥＳＲ） 波谱仪研究了光解蒽醌自由基的化学诱导动态电子极化（ＣＩＤＥＰ） ．实验测量表明,在蒽醌／ 乙二醇／ＴＸ－ １００ 体系中,蒽半醌自由基ＡＱＨ·有很强极化ＥＳＲ 信号,在激光激发后～０ ．８μｓ,检测到蒽醌负离子基ＡＱ·－ 的信号,表明ＡＱＨ·自由基部分地离解为负离子基ＡＱ·－ ．     

桥梁拉索损伤声发射监测研究进展

大量索承体系桥梁即将达到20–30年的拉索寿命期,开展有效的拉索损伤监测方法研究有利于保障大桥结构安全。本文简要论述了现有桥梁拉索损伤检测及监测方法的适用性,重点综述了近40年来声发射技术应用于桥梁拉索监测的研究进展,以及在腐蚀、疲劳、断丝等损伤监测方面所取得的研究成果。结合实测数据在采集、数据处理过程中的难点及参数分析盲点,探讨了现有研究成果应用于特大桥梁拉索损伤监测仍需解决的问题,并针对性地提出了研究思路。     

Acoustoelectric current through a quantum wire containing a point impurity

A dc electric current due to a flow of ultrasonic phonons through a quantum wire containing an isolated point impurity is analyzed theoretically. An explicit expression for the acoustoelectric (AE) current is obtained and its dependence on the chemical potential of the electron gas and the induction of the external magnetic field is investigated. It is shown that a point impurity may lead to a partial or complete destruction of the steplike structure of the AE current as a function of the chemical potential.     

Initiation of impact fracture in SiO2 ceramics

The results of high-speed recording of fractal luminescence (FL) and acoustic emission (AE) during the impact fracture of the surface of quartz ceramic are presented. FL results from the breakage of covalent bonds, and AE appears during the motion of microscopic and larger cracks. Measurements are performed on samples chosen after each stage of heat treatment, namely, drying at 100°C, sintering at 1190°C, and flame treatment of the sample surface. After each temperature cycle, the hardness of the material is measured and the connectivity of the silicate network of glass is estimated by IR reflection spectroscopy. The energy released during damage formation is determined from the FL and AE intensities. The energy distribution in the FL signals recorded after an impact in all samples is shown to obey the power law that is characteristic of the cooperative phenomena occurring in nonequilibrium processes. This finding indicates correlated fracture development at a nanostructure level. In AE signal series, a power energy distribution is detected only in sintered not glassy ceramic.     

Characterisation of a laser droplet formation process by acoustic emission

The aim of this article is to describe an application of acoustic emission to characterise a process of laser droplet formation from a metal wire. Laser droplet formation is a crucial process in new laser droplet welding technology, where parts are joined by means of the heat content of a liquid metal droplet deposited onto the parts to be joined. A laser beam is used for heating and melting the wire tip, and for detaching the molten pendant droplet. Depending on the process parameters, three different outcomes of the process can be observed: (1) no droplet formed; (2) a droplet formed but not detached; (3) a droplet formed and detached from the wire. It is shown that AE can be used to monitor the process and to indicate the different process outcomes.     

Mechanism of microweld formation and breakage during Cu-Cu wire bonding investigated by molecular dynamics simulation

Currently,wire bonding is the most popular first-level interconnection technology used between the die and package terminals,but even with its long-term and excessive usage,the mechanism of wire bonding has not been completely evaluated.Therefore,fundamental research is still needed.In this study,the mechanism of microweld formation and breakage during Cu-Cu wire bonding was investigated by using molecular dynamics simulation.The contact model for the nanoindentation process between the wire and substrate was developed to simulate the contact process of the Cu wire and Cu substrate.Elastic contact and plastic instability were investigated through the loading and unloading processes.Moreover,the evolution of the indentation morphology and distributions of the atomic stress were also investigated.It was shown that the loading and unloading curves do not coincide,and the unloading curve exhibited hysteresis.For the substrate,in the loading process,the main force changed from attractive to repulsive.The maximum von Mises stress increased and shifted from the center toward the edge of the contact area.During the unloading process,the main force changed from repulsive to attractive.The Mises stress reduced first and then increased.Stress concentration occurs around dislocations in the middle area of the Cu wire.     

Stabilization of monoatomic gold wires by carbon impurities

The influence of atomic and molecular carbon on the structural and electronic properties of a monoatomic gold wire has been studied by means of projector augmented-wave method (PAW) within density functional theory (DFT). Our calculations show that carbon is able to enhance the stability of linear gold chains with large interatomic separations. The Au-Au spacing at breakage can be as long as ∼4.5 and 6 Å for the wires incorporating atomic (Au-C) and molecular carbon (Au-C₂), respectively. The calculated band structure for nonmagnetic Au-C reveals the presence of one conduction channel for linear chains, but two channels for zigzag-like ones. A close similarity of this behaviour, to that known for a pure gold wire might indicate little influence of carbon on the conduction properties of gold nanowires.     

Acoustic emission technique for monitoring the pyrolysis of composites for process control

Carbonization is the first step in the heat and pressure treatment (pyrolysis) of composites in preparing carbon-carbon parts. These find many uses, including aircraft brakes, rocket nozzles and medical implants. This paper describes the acoustic emissions (AE) from various stages of the manufacturing process of carbon-carbon composites. This process involves carbonization at a high temperature and this results in both thermal expansion and volume change (due to pyrolysis in which a sacrificial polymer matrix is converted to carbon). Importantly the resultant matrix is porous and has a network of small intra-lamina cracks. The formation of these microcracks produces AE and this paper describes how this observation can be used to monitor (and eventually control) the manufacturing process. The aim is to speed up manufacture, which is currently time-consuming. The first section of the paper describes the design of unimodal waveguides to enable the AE to propagate to a cool environment where a transducer can be located. The second part of the paper describes various experimental observations of AE under a range of process conditions. In particular, this paper presents a technique based on detecting acoustic emissions and (1) uses wire waveguides to monitor parts within the autoclave to 800 degrees C, (2) monitors microcracking during pyrolysis, (3) uses a four-level threshold to distinguish between low- and high-amplitude cracking events, (4) recognizes the occurrence of harmful delaminations, and (5) guides the control of the heating rate for optimum efficiency of the pyrolysis process. In addition, supporting data are presented of in situ measurements of porosity, weight loss, cross-ply shrinkage, and mass spectroscopy of gases emitted. The process evolution is illustrated by the use of interrupted manufacturing cycle micrographs obtained by optical, scanning acoustic (SAM) and scanning electron (SEM) microscopy. The technique promotes in-process monitoring and control but also contributes to current understanding of pyrolysis.     

Measurements and analysis of the acoustic signals produced by partial discharges in insulation oil

This paper focuses on the frequency analysis of acoustic signals produced by partial discharges (PDs) in insulation oil and the positioning of the PD occurrence for application in the diagnosis of oil-insulated transformers. Three types of electrode systems; the needle–plane, the plane–plane, and the wire–wire structures were assembled to simulate the partial discharge in insulation oil. A low-noise amplifier and a de-coupler were designed to detect the acoustic signal with high-sensitivity. The frequency ranges of the acoustic signal were 60–270 kHz in the needle–plane electrode system, 45–250 kHz in the plane–plane electrode system, and 50–180 kHz in the wire–wire electrode system. Their peak frequencies were 145 kHz, 118 kHz and 121 kHz, respectively.The position of the PD occurrence was calculated from the time difference of arrival (TOA) using three acoustic emission (AE) sensors. The position was found within a 1% error in the experimental set-up.     

钢轨裂纹伤损声发射源的建模仿真与特征分析

高速铁路的发展对钢轨的安全性提出了特殊要求,因此对钢轨内部裂纹的特征分析具有重要意义。为了研究钢轨内部裂纹声发射源特征,对钢轨中不同类型、深度和传导距离的裂纹声发射源进行了分析.采用有限元方法建立了钢轨模型并通过实验验证,然后结合小波方法和瑞利-兰姆方程分析了裂纹声发射源的特征。结果表明:钢轨中不同类型和不同频率特征的声发射源能够利用声发射模态之间的强度比率来识别;轨腰深度上的声发射源具有统一的模态特征,而轨头和轨底的声发射源则具有复杂的模态特征;同时,不同类型声发射源在钢轨中的传导特征差异明显。研究结果对利用声发射技术进行钢轨裂纹检测提供了指导,可作为实际应用的重要参考。      

Feature analysis of acoustic emission sources for rail crack detection by the finite element method

The safety of rail is very important for the development of high speed railway,and it is necessary to investigate the features of inner cracks in rail.In order to obtain the features of Acoustic Emission(AE)sources of inner cracks in rail,AE sources with different types,depths and propagation distances are examined for crack in rail.The finite element method is utilized to model the rail with cracks and the results of experiment demonstrate the effectiveness of this model.Wavelet transform and Rayleigh-Lamb equations are utilized to extract the features of crack AE sources.The results illustrate that the intensity ratio among AE modes can identify the AE source types and the AE sources with different frequencies in rail.There are uniform AE mode features existing in the AE signals from AE sources in rail web,however AE signals from AE sources in rail head and rail base have the complex and unstable AE modes.Different AE source types have the different propagation features in rail.It is helpful to understand the rail cracks and detect the rail cracks based on the AE technique.