J-TEXTװ���������ϵͳ�������ʵ��

J-TEXT装置由许多相关子系统组成,其中央控制系统的主要功能和作用是统一调度和协调各个子系统,控制装置的运行状态。J-TEXT中央控制系统是基于Windows和QNX操作系统平台,并采用工业控制计算机结合PCI工业控制卡来实现的。该系统已经完成了相关测试并获得满意结果。在首轮的J-TEXT放电调试中,该系统运行稳定可靠,控制效果良好。     

Theoretical Strength of Face-Centred-Cubic Single Crystal Copper Based on a Continuum Model

The constitutive relation of single crystal copper based on atomistic potential is implemented to capture the nonlinear inter-atomic interactions. Uniaxial loading tests of single crystal copper with inter-atomic potential finite-element model are carried out to determine the corresponding ideal strength using the modified Born stability criteria. Dependence of the ideal strength on the crystallographic orientation is studied, and tension- compression asymmetry in ideal strength is also investigated. The results suggest that asymmetry for yielding strength of nano-materials may result from anisotropic character of crystal instability. Moreover, the results also reveal that the critical resolved shear stress in the direction of slip is not an accurate criterion for the ideal strength since it could not capture the dependence on the loading conditions and hydrostatic stress components for the ideal strength.     

Dynamics of Förster Energy Transfer in Pyridium Salt-Doped Thin Films

Properties of photoluminescence and Förster energy transfer dynamics based on an organic pyridium salt trans-4-[p-(N-Hydroxyethyl-N-methylamino)Styryl]-N-methylpyridinium iodide (ASPI) and organic small molecule Alq3 in PMMA polymeric thin films are investigated by steady-state and time-resolved fluorescent spectra as well as theoretical calculation. The observation of reduced emission intensity and the fluorescent lifetime of Alq3 is demonstrated, while the ASPI emission gradually increases and is finally dominant in the PL spectra with increasing ASPI doping concentration. Such results show that there exists an efficient Förster energy transfer (FET) from Alq3 to ASPI due to the large spectral overlap between ASPI absorption and Alq3 emission. The difference between the theoretical FET efficiency and the experimental data is caused by the lower mobility of the Alq3 exciton in the MMA matrix.     

Effects of Interfacial Polarization on Voltage Tunability of Pb(Fe1/2Nb1/2)1-xTixO3 Single Crystals

The voltage tunability of Pb(Fe_1/2Nb_1/2)_1-xTi_xO₃ single crystals is investigated at a low electric field (<130 V/cm) in a low frequency range (<1 MHz). The results show that the capacitance is strongly suppressed by the applied dc biases for both the rhombohedral sample and the tetragonal sample. A negative voltage tunability is only detected in the tetragonal sample. The origin of the giant tunability and the negative tunability is discussed based on the multipolarization-mechanism model and the equivalent circuit model, respectively. It is ascribed to the interfacial polarization at the interface of electrode/sample.     

Complex object 3D measurement based on phase-shifting and a neural network

An accurate phase-height mapping algorithm based on phase-shifting and a neural network is proposed to improve the performance of the structured light system with digital fringe projection. As phase-height mapping is nonlinear, it is difficult to find the best camera model for the system. In order to achieve high accuracy, a trained three-layer back propagation neural network is employed to obtain the complicated transformation. The phase error caused by the non-sinusoidal attribute of the fringe image is analyzed. During the phase calculation process, a pre-calibrated phase error look-up-table is used to reduce the phase error. The detailed procedures of the sample data collection are described. By training the network, the relationship between the image coordinates and the 3D coordinates of the object can be obtained. Experimental results demonstrate that the proposed method is not sensitive to the non-sinusoidal attribute of the fringe image and it can recover complex free-form objects with high accuracy.     

Scheme for Cloning an Unknown Entangled State with Assistance via Non-maximally Entangled Cluster States

We propose a scheme for cloning unknown two-particle entangled state and its orthogonal complement state with assistance from a state preparer. Two stages were included in this scheme. The first stage requires usual teleportation by using a one-dimensional non-maximally four-particle cluster state as quantum channel, after Alice’s (the state sender) Bell measurement, Bob (the state receiver) can get the original state with certain probability. In the second stage, after having received Victor’s (the state preparer) classical message, the perfect copies and complement copies of an unknown state can be produced in Alice’s place, the probability of Alice to get the original state or its orthogonal complement state are calculated. Assisted cloning of an arbitrary unknown two-particle entangled state is discussed in the latter scheme.     

固体热解塞曼原子吸收光谱法在毛发痕量汞分析中的应用

建立了一种采用固体热解塞曼原子吸收光谱快速测定毛发中痕量汞的方法,样品不需要经过消解即可直接测定。在优化的实验条件下．方法的相对标准偏差为3．9％(峰面积)和7．2％(峰高),检出限为26ng／g(3σ),回收率为94％～103％。使用标准参考物质进行对照分析和通过与ICP—MS分析结果进行比较,结果令人满意。应用本法通过对实验动物样本的检测表明,动物毛发中汞的含量与其体内受汞毒害程度存在一定的相关性。     

基于正交小波包的茶叶近红外光谱特性分析

针对茶叶近红外光谱数据中存在着高度的共线性和高维数,根据小波包变换具有的去相关能力。通过引入保留能量和置零系数来定量描述茶叶近红外光谱小波包变换后的特性;分析与实验表明,正交小波包对近红外光谱具有较强的压缩能力,压缩后保留的能量为99．98％,而置零系数百分比高达95．87％;这一结果对近红外光谱图的存储、检索及快速处理都有着十分重要的意义。     

CsI/MCP X射线阴极及其在低强度X射线影像仪中的应用

报道了X射线阴极的光电发射原理,给出CsI／MCPX射线阴极的制作方法。分析了反射式和透射式X射线阴极的量子效率和噪声特点,提出了改进工艺,给出CsI／MCP的输出特性和扫描电镜正面和剖面照片,且指出Lixiscope的发展以及在生物医学中的应用前景。     

脱氧核糖核酸在硬脂酸铝离子膜上固定杂交及BAR基因片段检测

将石墨粉、固体石蜡和硬脂酸按一定比例混合制得表面富含羧基的碳糊电极,然后在电极表面组装荷正电的铝离子膜。在硬脂酸铝离子膜上进行DNA探针的固定和与目标基因的杂交。以亚甲蓝为杂交指示剂,用循环伏安法优化了DNA的固定和杂交条件。应用该电化学生物传感器以微分脉冲伏安法对转基因玉米外源BAR基因片段进行了检测,结果令人满意。