Gal(1-x)Mn(1-x)Sb Grown on GaSb with Mass-Analyzed Low-Energy Dual Ion Beam Deposition

The Ga1-xMnxSb samples were fabricated by the implantation of Mn ions into GaSb (1 0 0) substrate with mass-analyzed low-energy dual ion beam deposition system, and post-annealing. Auger electron spectroscopy depth profile of the Ga1-xMnxSb samples showed

Thermal mismatch stress in SiC whisker reinforced aluminium composite: new measurement method by X-ray diffraction

A new X-ray diffraction method for characterising thermal mismatch stress (TMS) in SiC_w–Al composite has been developed. The TMS and thermal mismatch strain (TMSN) in SiC whiskers are considered to be axis symmetrical, and can be calculated by measuring the lattice distortion of the whiskers. Not only the average TMS in whiskers and matrix can be obtained, but the TMS components along longitudinal and radial directions in the SiC whiskers can also be deduced. Experimental results indicate that the TMS in SiC whiskers is compressive, and tensile in the aluminium matrix. The TMS and TMSN components along the longitudinal direction in the SiC whiskers are greater than those along the radial direction for a SiC_w–Al composite quenched at 500°C.

Nd65Al10Fe25-xCox (x=0,5,10) bulk metallic glasses with wide supercooled liquid regions

Bulk metallic glasses of Nd65Al10Fe25-xCox (x=0,5,10) have been prepared in the form of 3 mm diam rods. Results of differential scanning calrimetry, dynamic mechanical thermal analysis (DMTA), and x-ray diffraction are presented for these alloys. It is shown that the glass transition and crystallization have been observed by DMTA. The reduced glass transition temperature of these glasses, defined as the ratio between the glass transition temperature T-g and the melting temperature T-l is in the range from 0.55 to 0.62. All these glasses have a large supercooled liquid region (SLR), ranging from 80 to 130 K. The high value of reduced glass transition temperature and wide SLR agree with their good glass formation ability.

条形药包泥面爆炸爆坑发展过程的X光摄影研究

用Ｘ光摄影技术研究了导爆索在泥面爆炸时爆坑的发展过程，得到的各瞬时爆坑轮廓线可用椭圆方程描述，瞬时最大爆坑深度约为７０～８０倍药芯半径，瞬时最大爆坑宽度约为２００倍药芯半径，爆坑深度随时间成对数关系增长，未见临空面对其有明显影响，临空面对爆坑的影响出现在爆坑宽度为６０～８０倍药芯半径之后，爆坑有回缩现象。

X-Ray Observation on Flow and Failure of Saturated

介绍脉冲X光机和医用X光机的特性,应用这两种设备进行一系列饱和砂土的冲击加载实验。利用医用X光机拍摄到了饱和砂土在冲击载荷作用下产生的横断裂缝、纵向排水通道以及密实沉降的照片,得到了横断裂缝和纵向排水通道的出现规律,从而为研究饱和砂土冲击液化后结构破坏与密实沉降的机理提供了一种实验观测手段。

Molecular Dynamics And Density Functional Studies Of A Body-Centered-Tetragonal Polymorph Of Zno

We report a previously unknown body-centered-tetragonal structure for ZnO. This structure results from a phase transformation from wurtzite in [0001]-oriented nanorods during uniaxial tensile loading and is the most stable phase for ZnO when stress is above 7 GPa. The stress-induced phase transformation has important implications for the electronic, piezoelectric, mechanical, and thermal responses of ZnO. The discovery of this polymorph brings about a more complete understanding of the extent and nature of polymorphism in ZnO. A crystalline structure-load triaxiality map is developed to summarize the relationship between structure and loading.

Structural, Electrical, And Optical Properties Of Inasxsb1-X Epitaxial Films Grown By Liquid-Phase Epitaxy

The InAsxSb1-x films were grown on (100) GaSb substrates by liquid-phase epitaxy, and their structural, electrical, and optical properties were investigated. The high-resolution x-ray diffraction results reveal that the single crystalline InAsxSb1-x films with a midrange composition are epitaxially grown on the GaSb substrates. Temperature dependence of the Hall mobility was theoretically modeled by considering several predominant scattering mechanisms. The results indicate that ionized impurity and dislocation scatterings dominate at low temperatures, while polar optical phonon scattering is important at room temperature (RT). Furthermore, the InAsxSb1-x films with the higher As composition exhibit the better crystalline quality and the higher mobility. The InAs0.35Sb0.65 film exhibits a Hall mobility of 4.62x10(4) cm(2) V-1 s(-1). The cutoff wavelength of photoresponse is extended to about 12 mu m with a maximum responsivity of 0.21 V/W at RT, showing great potential for RT long-wavelength infrared detection. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2989116]

Damage analysis of tetragonal perovskite structure ceramics implicated by asymptotic field solutions and boundary conditions

Cracking of ceramics with tetragonal perovskite grain structure is known to appear at different sites and scale level. The multiscale character of damage depends on the combined effects of electromechanical coupling, prevailing physical parameters and boundary conditions. These detail features are exhibited by application of the energy density criterion with judicious use of the mode I asymptotic and full field solution in the range of r/a = 10(-4) to 10(-2) where r and a are, respectively, the distance to the crack tip and half crack length. Very close to the stationary crack tip, bifurcation is predicted resembling the dislocation emission behavior invoked in the molecular dynamics model. At the macroscopic scale, crack growth is predicted to occur straight ahead with two yield zones to the sides. A multiscale feature of crack tip damage is provided for the first time. Numerical values of the relative distances and bifurcation angles are reported for the PZT-4 ceramic subjected to different electric field to applied stress ratio and boundary conditions that consist of the specification of electric field/mechanical stress, electric displacement/mechanical strain, and mixed conditions. To be emphasized is that the multiscale character of damage in piezoceramics does not appear in general. It occurs only for specific combinations of the external and internal field parameters, elastic/piezoelectric/dielectric constants and specified boundary conditions. (C) 2002 Published by Elsevier Science Ltd.

Synchronization of modified Chua's circuit with x vertical bar x vertical bar function

This paper considers the chaos synchronization of the modified Chua's circuit with x vertical bar x vertical bar function. We firstly show that a couple of the modified Chua systems with different parameters and initial conditions can be synchronized using active control when the values of parameters both in drive system and response system are known aforehand. Furthermore, based on Lyapunov stability theory we propose an adaptive active control approach to make the states of two identical Chua systems with unknown constant parameters asymptotically synchronized. Moreover the designed controller is independent of those unknown parameters. Numerical simulations are given to validate the proposed synchronization approach.

超高速弹丸撞击靶板的脉冲X光照相实验研究

双层靶结构是一种有效的太空防护结构,对速度为5～7km/s的小颗粒弹丸具有极好的防护作用。为研究双层靶结构的防护作用,用二级轻气炮发射超高速弹丸撞击靶板,用脉冲X光摄影系统拍摄弹丸撞击靶板后形成的碎片粒子云团。对照见证靶被侵彻的形态,可以得到内涵十分深刻的实验数据。自动跟踪式脉冲X光摄影系统是一种新型的脉冲X光摄影系统。应用该系统成功地拍摄了高速弹丸撞击靶板后弹、靶形成碎片粒子云团的形态。文章披露了铝弹撞击铝靶,钢弹撞击铅靶后某一时刻的X光拍摄的图象,并对实验结果作了初步分析。

铝粉快速反应光谱中AlOB~2Σ~＋→X~2Σ~＋发射光谱的研究

在由光学多道分析仪收集的氢氧气体爆轰激励下铝粉快速反应光谱中，观察到ＡｌＯＢ２Σ＋→Ｘ２Σ＋跃迁Δｖ＝０带系的光谱特征与通常铝氧化反应的光谱特征不同。经分析是因为存在一个从４６７ｎｍ开始向长波方增强的连续辐射，它改变了该波长区ＡｌＯ分子的辐射特征。这一连续辐射可能是由铝与水蒸汽发生水合反应生成，而处于不同激发态的多原子分子ＨＡｌＯＨ产生

正激波后OH A~2∑~+──X~2∏瞬态光谱的测量

用光学多道分析仪（OMA光学系统）测量了氢氧燃烧驱动激波管中典型状态下正激波后高温空气不同时刻的瞬态光谱。光谱结果显示高温空气的光谱中有很强的OHA2∑＋─X2∏光谱。通过采用线线合成光谱的方法得到激波后不同时刻高温空气中OH分子的转动温度。

多台脉冲X光机出光时间间隔的量测

<正> 多台脉冲X光同步照相技术在爆炸力学等各个领域中得到了广泛的应用。数控脉冲X光同步机解决了多台同步运行时的同步精度,为精确地确定动态现象的照相时间,还必须测定每台脉冲X光机准确的出光时间。过去通常以脉冲X光机的放电电流或电压讯号代表出光时间讯号进行测量。由于脉冲X光的测试是在高压大电流脉冲放电的环境中进行,各

数控脉冲式X光同步机的研制和应用

本文介绍一种控制多台脉冲X光机同步运行的新型同步机。它具有抗干扰能力强,精度高,使用方便等特点。本文还对干扰机制和抗干扰措施以及仪器使用中如何保证可控精度的问题进行了探讨,并给出了应用结果——雷管爆炸、聚能射流等动态过程不同瞬态的X光照片。