Nuclear Halo-Like Phenomena and Short-Range Nuclear Correlation

Based on Glauber Multiple Scattering Theory, high-energy proton elastic scattering on halo-like nucleus ^13C is studied in a single nucleon wave function with low angular momentum configurations. A great agreement with experimental data is obtained and the theoretical prediction clearly shows that 13U has a neutron halo-like structure.Then, the origin and nature of nuclear halo phenomena are explained in terms of nuclear short-range correlations. Our conclnsion shows ttiat the origin of nuclear halo-like phenomena originates from short range nuclear correlation.     

基于特征点匹配的电子稳像技术

为获得高质量视频输出序列,电子稳像技术常被用来去除成像设备所摄取的图像序列中的随机抖动。本文首先介绍了电子稳像的国内外发展现状。然后,从电子稳像技术中的运动估计模块出发,描述了国内外近年来出现的直接求取运动估计算法以及各种基于特征点匹配的运动估计方法,并对运动校正和运动补偿模块的算法进行了评述。最后综合分析了稳像算法的难点以及未来发展趋势,提出基于特征匹配的电子稳像技术的发展方向。     

径向极化压电陶瓷长圆管复合超声换能器的径向振动

提出了一种圆管式径向复合压电陶瓷换能器,并对其径向振动特性进行了分析。该换能器由径向极化的压电陶瓷圆管以及金属外圆管组成。利用解析法得出了金属圆管以及具有任意壁厚的径向极化压电陶瓷圆管径向振动的机电等效电路。基于金属圆管与压电圆管的机械边界条件,得出了换能器的六端机电等效电路。在此基础上得出了换能器共振及反共振频率方程的解析表达式,给出了换能器的共振及反共振频率与其几何尺寸之间的依赖关系。利用数值方法对换能器的径向振动特性进行了模拟及仿真,并与解析结果进行了比较。最后,设计并加工了一些径向复合管式压电陶瓷换能器,利用精密阻抗分析仪对其共振及反共振频率进行了实验测试。研究结果表明,利用解析理论得出的换能器共振及反共振频率与数值模拟结果以及实验测试结果符合很好。     

氩-氮混合气电感耦合等离子体在元素和同位素分析中的应用进展

在传统Ar等离子体中引入其他活性气体(如氮气等)已经成为拓展其分析性能的一种重要手段。本文较系统的阐述了Ar-N₂混合气体电感耦合等离子体的基本物理化学性质,从N₂气引入引起传统Ar-ICP基本物理化学参数变化的层面出发探讨了Ar-N₂混合气等离子体特殊性质产生的机制,回顾了Ar-N₂混合气电感耦合等离子体在质谱分析中近40年的应用成果,并且展望了该技术在未来元素和同位素分析领域的应用前景。     

Monte Carlo simulation of GEM-based for 14 MeV neutron detector

A new concept of neutron detector based on Gas Electron Multiplier(GEM) technology is presented in this paper,in which a novel multi-layer high density polyethylene(HDPE) as neutron-to-proton converter is proposed and studied with Geant4 toolkit for fast 14 MeV neutron.Our preliminary results show that the detection efficiency of the detector with 400 converter units is higher than 2.3% and reconstruction accuracy of the incident neutron position is higher than 2.6%.     

利用视频分析软件Tracker研究皮球的弹跳

利用视频分析软件Tracker分析皮球在下落弹跳过程中位移和速度的变化情况,并依据分析的实验数据测量重力加速度以及皮球与地面碰撞时的恢复系数.     

Precise absolute positioning for a single-frequency user

A new strategy to realize precise absolute positioning for a single-frequency user is presented. In the presented strategy, the receiver clock and ambiguities are removed using the satelliteand epoch-differenced (SDED) algorithm. As a further development of the SDED algorithm, a regional augmentation network is used to generate the SDED atmospheric delays at the user. The weakened mathematic property due to the epoch-differenced operation is improved by adding the generated atmospheric delays and applying the robust estimation. To test the new approach, the 24-h data at 5 Continuous Operation Reference Station (CORS) stations in Shanghai is processed. The results show a more than 96% success rate, defined as the case where three directions achieve the desired positioning accuracy of 10 cm, when the observation is longer than 20 min. The 20-min static results show that the new method can reach an accuracy of 3.42, 4.76 and 9.26 cm in the North, East and Up directions, respectively. An experiment was carried out to assess the kinematic positioning. The results show that the kinematic positioning accuracy is 4.11, 5.31 and 4.05 cm in the north-south, east-west and height directions,respectively.     

基于动平台多源数据的运动目标测量方法研究

根据运动目标性能试验需求及试验平台的特点,建立一个影像数据测量系统,实现目标的运动视频记录和外部参数测量。采用基于OpenCV的棋盘格内参数标定结合基于平台上固定标识点、线为基准的外场标定的摄像机标定方法,采用高速影像数据、中线视频数据和GPS数据相结合的方法实现目标运动的轨迹、姿态等参数的测量。通过测量精度分析及多次试验结果证明,测量精度达到水平方向优于10 cm,高程方向优于5 cm,姿态精度优于05。     

压电波形对喷墨打印电极的调控规律

压电喷墨打印是制备印刷电子器件的主要手段之一,其墨滴喷射状态直接受压电波形的影响,因而压电波形对于器件打印具有重要意义。本文主要研究了压电波形对薄膜晶体管(TFT)电极打印效果的影响,实验通过改变压电波形的加压速率和脉冲持续时间,打印得到了一系列的电极样品,并对其图形效果及表面粗糙度进行了测量。实验表明,随着加压速率和脉冲持续时间的增大,墨滴喷出动能增大,最终打印的图形效果先改善后恶化,表面粗糙度则随之增大。在加压速率取值为0.08~1.65 V/μs、脉冲持续时间取值为1.216~2.688μs的区间内得到了失真程度较小的电极图形,在加压速率及脉冲持续时间分别为0.25 V/μs、2.688μs及0.65 V/μs、1.600μs时,电极图形化效果较好,表面粗糙度分别为59.04 nm和59.27 nm。通过对压电波形参数的合理设置,能够实现对打印图形效果的优化。     

Bi~(3+)或Sm~(3+)掺杂对NaGd(WO_4)_2∶Eu~(3+)荧光粉结构和发光性质的影响

采用水热法制备了白光LED用NaGd_(0.95-x)(WO_4)_2∶0.05Eu~(3+),x Bi~(3+)(x=0,0.02,0.04,0.06,0.08)和NaGd_(0.95-y)(WO_4)_2∶0.05Eu~(3+),y Sm~(3+)(y=0,0.01,0.02,0.03,0.04)系列红色荧光粉,通过X射线衍射仪、扫描电子显微镜及荧光分光光度计等表征手段分析了样品的物相结构、颗粒形貌以及发光性质。结果表明:少量离子掺杂对NaGd(WO_4)_2的晶体结构影响较小,样品均为四方晶系、白钨矿结构的纯相;颗粒形貌呈四方盘状,且粒度均匀,分散性良好,Bi~(3+)或Sm~(3+)的引入使颗粒尺寸由原来的4μm分别增加至5μm和6μm。该系列荧光粉均可被近紫外光(394 nm)有效激发,其最强发射峰位于614 nm处,归属于Eu~(3+)的5D0→7F2电偶极跃迁。掺杂适量的Bi~(3+)或Sm~(3+)可有效提高NaGd_(0.95)(WO_4)_2∶0.05Eu~(3+)荧光粉的发光强度和红光的色纯度,其中Sm~(3+)的引入对其影响更为明显。