Synthesis of PANI/rGO composite as a cathode material for rechargeable lithium-polymer cells

Graphene oxide (GO) was synthesized by an improved Hummers method and then reduced with NaBH₄; GO became rGO with regular layered structure. Polyaniline (PANI)/rGO composite was prepared by a adsorption double oxidant method with rGO as a template. Some physical characterization methods (Fourier transform infrared spectroscopy analysis, X-ray diffraction, scanning electron microscope, and transmission electron microscope) were used to analyze the morphology and crystallinity of the composite. The electrochemical properties were characterized by cyclic voltammetry, impedance spectroscopy, galvanostatic charge/discharge, and rate capability. The first discharge specific capacity of the rPANI/rGO and PANI/rGO was 181.2 and 147.8 mAh/g. After 100 cycles, the capacity retention rate was still 90.2 and 88.9% separately, and the coulombic efficiency of batteries is close to 100%. These results demonstrate the composite has exciting potentials for the cathode material of lithium-ion battery.     

退火处理对磁控溅射制备LaCoO_3薄膜性能的影响

采用磁控溅射法在硅衬底上制备了LaCoO_3(LCO)薄膜,研究了退火温度对LCO薄膜组织结构、表面形貌及热电特性的影响,并利用X射线衍射仪、原子力显微镜(AFM)、激光导热仪等对LCO薄膜的晶体结构、表面形貌、热扩散系数等进行测量与表征.结果表明:退火温度对LCO薄膜的结晶度、晶粒尺寸和薄膜表面形貌都有较大影响;退火前后LCO薄膜的热扩散系数都随温度的升高而减小,且变化速率逐渐减缓; LCO薄膜的热扩散系数随退化温度的升高先增大后减小.LCO薄膜经过700℃退火后得到最佳的综合性能,其薄膜表面致密、平整,结晶质量最好,热扩散系数最小,热电性能最好.     

冷原子系综内单集体激发态的相干操纵

原子系综内部分原子发生相干态转移后所处量子态被称为集体激发态.如果激发数目在单原子量级则被称为单激发态.在量子存储过程中,单光子以单激发态的形式在原子系综内进行存储.因此,研究单激发态的制备、演化、转化、干涉等过程是量子存储及其应用研究的关键.本文总结了近年来作者所在研究团队针对冷原子系综体系在此研究方向取得的若干成果.主要包括采用动量模式调控、三维光晶格等手段抑制单激发态的退相干,采用环形腔增强原子至光子的转化效率,发展基于拉曼光的单激发态相干转移技术,利用单量子态不同模式间干涉制备光与原子纠缠,利用里德伯阻塞机制提升纠缠制备效率等.此外,简要回顾了基于多个单激发态的量子中继及量子网络实验.     

Study on a new green phosphor Ca12Al14O32Cl2: Tb3+ derived from Tb-doped Ca-Al layered double hydroxide

A new green phosphor Ca₁₂Al₁₄O₃₂Cl₂: Tb³⁺ derived from Tb-doped Ca-Al layered double hydroxide (Tb-doped CaAl-LDH) was prepared through phase transition route. The X-ray diffraction measurement results revealed that the Tb-doped CaAl-LDH transformed into Ca₁₂Al₁₄O₃₂Cl₂:Tb³⁺ phase at 600 °C. With temperature varying from 600, 800–1000 °C, the crystallinity of the Ca₁₂Al₁₄O₃₂Cl₂:Tb³⁺ phase gradually improved. Compositional analyses suggested the chemical formula of the Ca₁₂Al₁₄O₃₂Cl₂:Tb³⁺ phase estimated to be Ca₁₂Al_13.52Tb_0.48O₃₂Cl₂. The Ca₁₂Al_13.52Tb_0.48O₃₂Cl₂ phase can be efficiently excited by near ultraviolet light and show strong green emissions attributed to ⁵D₄→⁷F_J (J = 5, 6) transition of Tb³⁺. The present Ca₁₂Al_13.52Tb_0.48O₃₂Cl₂ may be a promising candidate for green phosphor applied in LED.     

A possible explanation of the knee of cosmic light component spectrum from 100 TeV to 3 PeV

A mixed hydrogen and helium(H + He) spectrum with a clear steepening at ~700 TeV has been detected by the ARGO-YBJ experiments. In this paper, we demonstrate that the observed H + He spectrum can be reproduced well with a model of cosmic rays escaping from the supernova remnants(SNRs) in our Galaxy. In this model, particles are accelerated in a SNR through a non-linear diffusive shock acceleration mechanism. Three components of high energy light nuclei escaped from the SNR are considered. It should be noted that the proton spectrum observed by KASCADE can be also explained by this model given a higher acceleration efficiency.     

基于改进的加速鲁棒特征的目标识别

为了提高加速鲁棒特征(SURF)算法的实时性和准确性,本文提出了一种结合AGAST角点检测和改进的SURF特征描绘算法。首先利用AGAST角点检测模板检测特征点,再使用增加对角信息的哈尔小波响应来生成特征点的描述子,之后利用特征袋对产生的描述子进行编码并生成新的特征向量,最后利用支持向量机(SVM)对特征向量进行分类,完成识别。本文以SIFT和SURF算法为对照,分别进行不同视角、光照和尺度的识别实验。实验结果表明,本文算法的平均识别率为98.0%、96.9%、97.1%,平均时间分别为66.1 ms、79.3 ms、41.0 ms,在识别率上较优于SURF算法,所耗时间约是SURF算法的1/3。     

跟踪微分器在陀螺信号去噪方面的应用

为了提高航空光电稳定平台的视轴稳定精度,采用跟踪微分器作为滤波器,对输入信号进行滤波,改善随机噪声对控制精度带来的负面影响。跟踪微分器会产生相位延迟,根据它得到的滤波信号及其微分信号,采用预报方法对滤波后的信号进行补偿。算法不依赖对象模型,计算量较小,易于实现。本文阐述了该算法的离散数学表达式,给出数值仿真分析,并在某型航空光电稳定平台上进行实验验证。结果表明:相较于巴特沃斯滤波器,跟踪微分器提高了阶跃响应的性能,最大超调量减少10.5%,上升时间缩短了4.5 ms,调整时间缩短50 ms。基本满足控制系统的实时性、快速性、稳定可靠、精度高、抗干扰能力强等要求。研究表明跟踪微分器对于航空光电稳定平台的精度提高,有比较好的实用价值。     

RDX/HMX颗粒炸药落锤撞击点火-燃烧机理

对单质炸药受低速撞击的力学和化学响应研究,是进行炸药敏感性评价的基础。利用配备了光学观测的落锤撞击装置,实现了频率为1.5×105 s-1的实时观测,不但可以区分样品的“爆”或“不爆”,而且可以获取RDX和HMX颗粒炸药受落锤低速撞击变形、破碎、溅射、点火和燃烧随时间演化的特征。结果表明:RDX颗粒是在液相中点火,而HMX颗粒在固相中点火; 燃烧反应前常常发生剧烈的溅射现象,溅射是由气相反应产物释放能量推动破碎的颗粒所致。对比了单个和单层颗粒炸药响应的特点,多个颗粒由于热点密集和破碎后相互作用,其燃烧反应比单个颗粒燃烧反应更剧烈。根据图像处理估算燃烧波传播速度,很好地表征了样品宏观燃烧反应的剧烈程度。     

聚苯乙烯非均相催化加氢吸附动力学及反应动力学研究

采用以表面具有贯穿大孔的二氧化硅空心微球为载体制备的负载型钯催化剂（Pd/SHMs）,对聚苯乙烯（PS）在非均相加氢催化剂上的吸附及加氢反应行为进行了系统研究,得到了吸附和反应动力学模型,并对部分加氢产物进行了详细分析.结果表明随着温度的升高,PS吸附量逐渐增加,且达到饱和吸附时间也随之增长,确定了PS非均相加氢为1级反应,活化能为58.3 kJ·mol^-1.将不同加氢度的样品进行分离提纯分析,结果显示PS的部分加氢产物都是由较高加氢转化率（85%左右）和较低加氢转化率（25%左右）的PS组成,证明PS非均相加氢存在二次吸附和竞争吸附加氢的现象,即服从“Blocky”机理.此工作为PS催化加氢吸附及反应过程的研究奠定基础,也为理解其他聚合物在非均相催化剂上的吸附及反应行为提供帮助.     

膦酸酯离子液体在合成多元醇酯过程中的双重作用:从催化剂到合成酯的减摩抗磨添加剂

合成了两种膦酸酯类离子液体,用作三羟甲基丙烷(TMP)与油酸(OA)的酯化催化剂合成三羟甲基丙烷三油酸酯(TMPTO).结果表明:这两种离子液体均具有一定的催化活性和较高的产物(二酯和三酯)选择性.反应结束后,离子液体催化剂可完全溶于产物TMPTO中,在微动摩擦磨损试验机SRV-IV上评价其作为钢/钢摩擦副润滑油减摩抗磨添加剂的高温摩擦学性能;结果表明所合成的磷酸酯离子液体具有优异的减摩抗磨性能.采用扫描电子显微镜(SEM)及X射线光电子能谱仪(XPS)对磨斑表面进行了分析,结果表明所合成的膦酸酯类离子液体在高温下均表现出优异的摩擦学性能,源于膦酸酯类离子液体与金属基底发生了摩擦化学反应并形成了摩擦化学反应膜从而使该离子液体表现出优异的摩擦学性能.