Surface oxidation of vanadium dioxide films prepared by radio frequency magnetron sputtering

This paper reports that the thermochromic vanadium dioxide films were deposited on various transparent substrates by radio frequency magnetron sputtering, and then aged under circumstance for years. Samples were characterized with several different techniques such as x-ray diffraction, x-ray photoelectron spectroscopy, and Raman, when they were fresh from sputter chamber and aged after years, respectively, in order to determine their structure and composition. It finds that a small amount of sodium occurred on the surface of vanadium dioxide films, which was probably due to sodium ion diffusion from soda-lime glass when sputtering was performed at high substrate temperature. It also finds that aging for years significantly affected the nonstoichiometry of vanadium dioxide films, thus inducing much change in Raman modes.     

关于具有二阶细焦点的二次系统

研究了具有二阶细焦点的二次系统的极限环存在性的某些问题.首先,简化了一个极限环存在性定理的证明,然后证明了若L满足不等式ψ1(-1 (L+1))>ψ2(-1 (L+1)),则二次系统(E2)在原点O外围至多存在一个极限环的定理,并猜测当L0相似文献   

JPEG2000 DWT变换器和EBCOT编码器的VLSI结构设计

为了进行符合新一代静止图像压缩标准 JPEG2 0 0 0的图像编码 IP核设计 ,提出了基于 JPEG2 0 0 0标准的离散小波变换器 (DWT)和优化截断的嵌入式分块编码器 (E-BCOT)的 VL SI结构。DWT采用的空间组合推举体制算法(SCL A)将基于 9/ 7滤波器的标准推举 (lifting)算法体制快速的运算量降低了 5 / 12。EBCOT采用的并行运算和动态内存控制 (DMC)结构 ,在保证编码速度的前提下 ,最大限度减小了片内小波系数缓存量和访问频率。这 2项设计均可以作为单独的 IP核应用在其他需要高速图像处理的领域 ,如远程监控、数码相机等。     

Structural and optical properties of tungsten-doped vanadium dioxide films

Thin films of tungsten(W)-doped thermochromic vanadium dioxide(VO2) were deposited onto soda-lime glass and fused silica by radio frequency magnetron sputtering.The doped VO2 films were characterized by X-ray diffraction,optical transmittance measurement,and near field optical microscopy with Raman spectroscopy.X-ray diffraction patterns show that the(011) peak of W-doped thermochromic VO2 film shifts to a lower diffraction angle with the increase of W concentration.The optical measurements indicated that the transmittance change(△T) at wavelength of 2500 nm drops from 65%(T at 35℃ and 80℃ for undoped VO2 film) to 38%(T at 30℃ and 42℃ for the doped VO2 film).At the same time,phase transition temperature drops from 65℃ to room temperature or lower with the increase of W concentration.Near field optical microscopy image shows that the surface of W-doped VO2 film is smooth.Raman results show that the main Raman modes of W-doped VO2 are centered at 614 cm1,the same as that of undoped VO2,suggesting no Raman mode changes for lightly W-doped VO2 at room temperature,due to no phase transition appearing under this condition.     

钒氧化物薄膜的拉曼散射

用射频磁控溅射以纯金属钒做靶材在氩氧混合气体中制备了钒氧化物 (VO2 (B)、V6O1 3、V2 O5)薄膜。报导了钒氧化物薄膜的拉曼光谱 ,结合这些钒氧化物不同的结构特点 ,对它们的拉曼光谱进行了分类讨论     

猪有病人也不能幸免

研究结果显示:国内一些养猪场滥用抗生素,有的为了让猪卖相好,给猪喂食有机砷制剂,以致养猪场成为耐药细菌的选拔场。这些耐药细菌通过猪粪便流入外界环境,对人类健康造成危害。     

In-situ characterization of electrochromism based on ITO/PEDOT:PSS towards preparation of high performance device

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) is usually sandwiched between indium tin oxide(ITO) and a functional polymer in order to improve the performance of the device. However, because of the strong acidic nature of PEDOT:PSS, the instability of the ITO/PEDOT:PSS interface is also observed. The mechanism of degradation of the device remains is unclear and needs to be further studied. In this article, we investigate the in-situ electrochromism of PEDOT:PSS to disclose the cause of the degradation. X-ray photoelectron spectroscopy(XPS) was used to characterize the PEDOT:PSS films, as well as the PEDOT:PSS plus polyethylene glycol(PEG) films with and without indium ions. The electrochromic devices(ECD) based on PEDOT:PSS and PEG with and without indium ions are carried out by in-situ micro-Raman and laser reflective measurement(LRM). For comparison, ECD based on PEDOT:PSS and PEG films with LiCl, KCl, NaCl or InCl_3 are also investigated by LRM. The results show that PEDOT:PSS is further reduced when negatively biased, and oxidized when positively biased. This could identify that PEDOT:PSS with indium ions from PEDOT:PSS etching ITO will lose dopants when negatively biased. The LRM shows that the device with indium ions has a stronger effect on the reduction property of PEDOT:PSS-PEG film than the device without indium ions. The contrast of the former device is 44%, that of the latter device is about 3%. The LRM also shows that the contrasts of the device based on PEDOT:PSS+PEG with LiCl, KCl, NaCl, InCl_3 are 30%, 27%, 15%, and 18%, respectively.     

Electrochromic & magnetic properties of electrode materials for lithium ion batteries

Progress in electrochromic lithium ion batteries(LIBs) is reviewed, highlighting advances and possible research directions. Methods for using the LIB electrode materials' magnetic properties are also described, using several examples.Li_4Ti_5O_(12)(LTO) film is discussed as an electrochromic material and insertion compound. The opto-electrical properties of the LTO film have been characterized by electrical measurements and UV–Vis spectra. A prototype bi-functional electrochromic LIB, incorporating LTO as both electrochromic layer and anode, has also been characterized by charge–discharge measurements and UV–Vis transmittance. The results show that the bi-functional electrochromic LIB prototype works well. Magnetic measurement has proven to be a powerful tool to evaluate the quality of electrode materials. We introduce briefly the magnetism of solids in general, and then discuss the magnetic characteristics of layered oxides, spinel oxides, olivine phosphate Li Fe PO_4, and Nasicon-type Li_3Fe_2(PO_4)_3. We also discuss what kind of impurities can be detected, which will guide us to fabricate high quality films and high performance devices.     

Structures and Dynamics of Two-Dimensional Dust Lattices with and without Coulomb Molecules in Plasmas

Structures and dynamics of two-dimensional dust lattices with and without Coulomb molecules in plasmas are investigated. The experimental results show that the lattices have the crystal-like hexagonal structures, i.e. most particles have six nearest-neighboring particles. However, the lattice points can be occupied by the individual particles or by a pair of particles called Coulomb molecules. The pair correlation function is used to compare the structures between the lattices with or without the Coulomb molecules. In the experiments, the Coulomb molecules can also decompose and recombine with another individual particle to form a new molecule.     

基于LS-SVM的导弹费用估测研究

导弹系统的费用估算对于采办费用的控制、方案的优化设计具有十分重要的意义和作用,目前对导弹系统费用估算方法存在估算精度不高、泛化能力差、计算过程烦杂等问题,作者提出了基于最小二乘支持向量机的导弹系统费用估算方法,并采用了密度因子法来对样本集中的孤立样本点进行剔除.研究表明,最小二乘支持向量机能够较好地适用于导弹系统的费用的估算,并具有较高的估算精度.