太阳过渡区紫外光谱的观测与诊断

太阳过渡区是太阳色球层顶到日冕底部的大气薄层。厚度仅几百千米,但其间太阳等离子体参数变化剧烈。过渡区的辐射多为光学薄的远紫外、极紫外发射谱线和背景连续谱线。由于地球大气的吸收,过渡区紫外光谱需通过天基观测才能实现。近几十年来,星载仪器的成功发射为太阳过渡区的研究打开了新纪元。工作回顾了太阳过渡区紫外光谱的观测历史和各类星载仪器,特别介绍了近十几年几种重要的光谱仪器。详细阐述了过渡区紫外光谱的发生率、电子密度和电子温度的诊断原理。讨论了过渡区紫外谱线的形状,并以SOHO/SUMER光谱仪为例介绍了表征谱线的几种重要参量及其物理意义。     

Effect of post heat treatment on microstructure and photocatalytic activities of TiO2 nanoribbons

Low-dimensional TiO₂ nanoribbons were synthesized by a simple one-step hydrothermal method. The TiO₂ nanoribbons were calcined over the temperature range 200-800 °C in order to enhance their photocatalytic properties by altering their crystal phase and increasing crystallization. Effects of hydrothermal temperature, calcinated temperature and calcination time on the formation of nanostructures have been observed and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The (BET) specific surface area of the samples which with different post treatments were determined by N₂ absorption-desorption experiment. In addition, photocatalytic activities of the nanoribbons were evaluated by photodegradation of organic dyes methyl orange under the radiation of UV light. The results reveal that the post-treatments have great effects on the microstructures and the photocatalytic activities of TiO₂ nanoribbons.     

Spin-glass behavior and magnetocaloric effect in melt-spun TbCuAl alloys

Magnetic properties and magnetocaloric effects of amorphous and crystalline TbCuAl ribbons are investigated by measuring their ac susceptibilities including a nonlinear term and dc magnetizations. The in-phase third harmonic ac susceptibility is found to be negative. It can be well fitted by the expression at high temperatures, indicating a spin-glass behavior in amorphous TbCuAl alloy. ΔT_f(ω)/[T_f(ω)Δlog₁₀ω], a possible distinguishing criterion to judge the presence of a spin-glass behavior is ∼0.011. The frequency-dependent data can be well fitted by the conventional critical slowing down law and the spin-glass transition temperature is obtained to be 20.1 K. The maximum of magnetic entropy change reaches 4.5 J kg⁻¹ K⁻¹ for a field change of 0-50 000 Oe, while the crystalline TbCuAl compound experiences a simple ferromagnetic-to-paramagnetic phase transition. The peak value of magnetic entropy change is obtained at the Curie temperature and reaches 14.4 J kg⁻¹ K⁻¹ for the same field change, which is much larger than that of amorphous TbCuAl alloy.     

Infrared small moving target detection method based on graph matching

We apply graph matching method to detect infrared small moving targets using image sequences. Candidates （interest points） detected in the first frame form one graph and the same candidates in the last frame form another one. The real moving targets are extracted by matching these two graphs. Experimental results demonstrate that the proposed method is robust and efficient to the translation and rotation of the background.     

Effects of enhanced electronic correlation on magnetic properties of light non-metallic element (B,C, N,and O)-doped CuCl: A first-principles study

Based on density functional calculations within both standard generalized gradient approximation and plus on-site Coulomb interactions approaches, we have investigated the electronic structure and magnetic properties of the first-row element-doped CuCl semiconductors. The electronic correlations in both 2p and 3d orbitals are enhanced by adding the on-site Coulomb repulsion (Hubbard U and Hund exchange J). After a comparative study, we find that, for both standard and beyond approaches, B-doped CuCl is a half-metallic magnet with majority-spin impurity bands touching the Fermi level, C-doped CuCl is a magnetic semiconductor, and N-doped CuCl is a half-metallic magnet with minority-spin impurity bands crossing the Fermi level. Nevertheless, for O-doped CuCl, it transforms from a nonmagnetic semiconductor to a half-metallic magnet with metallic up-spins by considering the correlation effects. The calculation shows that the enhanced electronic correlation not only corrects the error of band-gap, but also influences the magnetic ground state and the distribution of local magnetic moments. The location of impurity bands with different dopants was understood based on the elements' electronegativity and interaction between dopant and host atoms. Strong hybridization between the dopant's 2p states and the filled 3d orbitals of adjacent Cu yields the main contribution to magnetization.     

Tracking of a third-order maneuvering target under an arbitrary topology

We explore the tracking problem of a maneuvering target. Tracking agents with third-order kinematics can communicate with each other via wireless network. The communication network topology is arbitrary rather than switches among several fixed topologies. The information sharing and interaction among agents are position, velocity, and acceleration. Some sufficient conditions of tracking strategy have been proposed. Finally, a numerical example is employed to demonstrate the effectiveness of proposed tracking strategy.     

利用光纤法布里-珀罗谐振器干涉透射波长同时测量混合溶液中多溶质浓度

为了同时探测混合溶液中多种溶质的浓度,提出一种用光纤法布里-珀罗谐振器作为传感器测量混合溶液中多溶质浓度的测量系统.从理论上分析了光纤法布里-珀罗谐振器干涉透射波长与混合溶液浓度之间的关系,采用光纤法布里-珀罗谐振器干涉透射波长实现了高准确度同时测量混合溶液中多溶质浓度的原理和可行性.构建了由InGaAs发光二极管光源、光纤耦合器、FFPR传感器、光电信号转换和放大器、光谱分析仪等组成的测量系统.对乙醇和甘油的9组标准混合溶液进行测量实验,并用测量结果标定了混合溶液中各溶质浓度与光纤法布里-珀罗谐振器传感器干涉透射波长之间的数学解析关系式.根据数学关系式用Action Script 2.0脚本语言编写程序,计算机实时监控了混合溶液中各溶质浓度的变化过程.     

An Application of the Renormalization Group Method to Stable Limit Laws

Let \((X_n)_{n=1}^{\infty }\) be a sequence of independent identically distributed random variables. We study the normalized partial sums and the corresponding renormalization group flow in the space of probability densities. We prove the convergence to stable limit laws under suitable assumptions on the initial density.     

近红外、中红外和拉曼光谱法测定商品农药制剂中溴氰菊酯的含量

利用近红外、中红外和拉曼光谱法定量分析了商品农药制剂中有效成分溴氰菊酯的含量,采用偏最小二乘法(partial least squares,PLS)建立溴氰菊酯的定量模型并进行了优化,用独立检验集对模型适应性进行评价。近红外和中红外法溴氰菊酯定量模型的相关系数和定标标准差分别是0.9999,0.022和0.9996,0.056,两种方法的定量效果接近;拉曼法溴氰菊酯定量模型的相关系数是0.9967,定标标准差是0.172,预测精度不如近红外和中红外高。MIR-ATR,NIR和Raman方法均能满足现场检测农药质量的需要,对生产企业的连续在线检测、监督部门进行农药质量控制和农产品安全具有重要意义。     

基片温度对SiNx薄膜结晶状态及机械性能的影响

利用微波电子回旋共振增强磁控反应溅射法在不同基片温度下制备无氢SiNx薄膜.通过傅里叶变换红外光谱、透射电子显微镜、台阶仪、纳米硬度仪等表征技术,研究了基片温度对SiNx薄膜结晶状态、晶粒尺寸、晶体取向等结晶性能以及薄膜的生长速率、硬度等机械性能的影响,并探讨了薄膜结晶性能与机械性能之间的关系.研究结果表明,在基片温度低于300℃时制备的SiNx薄膜以非晶状态存在,硬度值仅为18 GPa左右;基片温度在320-620℃范围内,SiNx薄膜中出现纳米晶粒,且晶粒尺寸随沉积温度的增加而增加,在沉积温度为620℃时达到最大,为20±1.5 nm;当沉积温度为700℃时,SiN<,x>薄膜的晶粒尺寸突然减小,但由于此时晶粒密度为最大,因此薄膜硬度达到最大值(36.7 GPa).