Quantum Nonlocality and Entanglement of Pair Cat States with Phase Decoherence

We investigate the entanglement of pair cat states in the phase damping channel by adopting the log-negativity and then study the possible violations of Bell＇s inequalities for the pair cat states in terms of the Wigner representation in phase space based upon parity measurement and displacement operation.     

Determination of Orientations in Deformed U--U Collisions at 0.52GeV/u

The ART model is applied to study the deformed UU collision at HIRFL-CSR energy area corresponding to the high baryon density region in the QCD phase diagram. The time evolution of central baryon (energy) densities in central collisions at E_b =0.52GeV/u shows that different orientation collisions will lead to different lifetimes of high density, especially tip--tip UU collisions which have an extend lifetime for the high density phase by almost a factor of 2 compared to the body--body orientation collisions. In order to pick out the interesting tip--tip like events from a mass of random orientation collisions, we study the relation between stopping power R and impact parameter b in different orientation collisions and find that it can enhance the purity of tip--tip like events when R increases. Therefore, the high density and long lifetime events can be effectively distinguished by R selection.     

Multi-Slit Diffraction of Evanescent Electromagnetic Waves

The well-known Fraunhofer multi-slit diffraction is described as the multi-slit interference modulated by the singleslit diffraction, namely the multiplication between the single-slit diffraction factor and the multi-slit interference factor. By considering the simplified argument we show that the multi-slit diffraction of evanescent waves which are in the near-field region also has the interference and diffraction effects, and that this two-fold effect can be expressed as the convolution of the diffraction factor and the interference factor. Our conclusion could be helpful to understand the contribution of evanescent waves to the optical responses of sub-wavelength structures such as slits and grooves.     

基于毛竹叶片理化参数的刚竹毒蛾危害检测研究

虫害检测算法研究是开展虫害快速、准确监测,制定精准森防检疫措施的重要基础。以毛竹叶片为研究尺度,基于刚竹毒蛾危害下的寄主外部形态与内部生理现象总结,选择并实测叶损量LL、相对叶绿素含量RCC、相对含水量RWC、原始光谱的733.66~898.56 nm值(ρ_{733.66~898.56})、一阶微分光谱的562.95~585.25 nm值(ρ′_{562.95~585.25})与706.18~725.41 nm值(ρ′_{706.18~725.41})等理化参数,随机划分实验组(63组)和验证组(37组)并设计5次重复实验;分别运用Fisher判别分析、BP神经网络、随机森林等三种方法建立刚竹毒蛾危害等级的检测模型,从检测精度、Kappa系数及R2等指标对模型的检测效果予以分析和比较。结果显示,Fisher判别分析、BP神经网络、随机森林的检测精度分别为69.19%,65.41%,83.78%,Kappa系数分别为0.576 9,0.532 4和0.778 8,R2分别为0.722 2,0.582 6和0.870 9,总体而言,三种方法均具备刚竹毒蛾危害的检测能力,随机森林的检测效果最优,Fisher判别分析次之,再次为BP神经网络;从分等级来看,随机森林的检测精度亦优于Fisher判别分析与BP神经网络,但3种方法对中度危害等级的检测精度均有所不足。该成果可为刚竹毒蛾危害及其他病虫害检测算法的选择提供参考,并为进一步建立冠层、遥感影像像元等尺度的虫害检测模型奠定基础。     

网络化雷达现状及技术发展趋势

随着新的作战对象和作战样式的出现,以及作战环境更加复杂,仅依靠单个雷达节点的能力已经越来越难以满足新的作战需求。文中针对网络化雷达这一新体制雷达开展研究,通过分析国外网络化雷达系统发展现状、趋势及关键技术,总结对我国网络化雷达技术发展的经验启示,为我国网络化雷达系统发展提供技术参考。     

通过超宽139La固体核磁共振波谱研究层状La(OH)2NO3

层状稀土氢氧化物是一类新型的稀土功能材料,本文采用固体核磁共振（SSNMR）方法研究了同时具备离子交换能力和非线性光学特性的层状La（OH）₂NO₃化合物,探讨了通过四极核CPMG（QCPMG）脉冲序列和变频谱图采集获取超宽¹³⁹La SSNMR谱图的方法,并描述了适用于此类实验的滤波方程和谱图重建方法.重建谱图同时包含四极核中心跃迁和卫星跃迁信息,本文使用QUEST软件对超宽¹³⁹La NMR谱图进行了模拟,获取的四极耦合常数C_Q和非对称因子η_Q均与CASTEP密度泛函理论计算值高度吻合.SSNMR实验结果证实层状La（OH）₂NO₃化合物属于非中心对称结构（P2₁）,解决了对其结构长期以来存在的争论.     

Facile Synthesis of Bi2MoO6 Nanosheets@Nitrogen and Sulfur Codoped Graphene Composites for Sodium-ion Batteries

Recently,sodium-ion batteries gradually become the promising alternative to lithium-ion batteries because of cost considerations.In this work,a kind of Bi2MoO6 nanosheets@N,S codoped graphene composite is designed and fabricated for sodium storage applications.Detailed characterizations are employed to investigate its morphology,structure and chemical compositions.When evaluated as an anode material for sodium-ion batteries,the as-prepared composite is able to display a specific capacity of 254 mA·h/g after 50 cycles at a current density of 0.2 A/g,and 186 mA·h/g at 1.6 A/g during the rate capability test.As a result,the further morphology and structure optimization is still required for high performance sodium-ion batteries.     

浅谈P4的生长

P_4(白磷的分子式)及其衍生物的结构是化学竞赛的热点之一。本文简介了P_4的生长,对近年与本知识相关的几道竞赛题进行了解析,并提出了几点教学建议。     

基于B样条的TERS形貌成像背景扣除方法

在针尖增强拉曼光谱(TERS)形貌成像过程中,由于针尖与扫描台无法绝对平行、样品电子密度骤变处针尖快速升降以及扫描控制系统响应时间特性差等综合原因的影响,往往使形貌图中带有倾斜或边界面卷曲的成像背景。成像背景对样品形貌的识别和分析带来十分不利的影响,而背景扣除就是解决该问题的重要手段,也是形貌成像预处理的重要组成部分。背景扣除的原理一般是通过拟合背景的方法来扣除成像中的背景。传统的背景扣除方法是利用多项式拟合的方法对成像进行逐行的基线校正,但是该方法在处理形貌成像时常常会由于过拟合而造成样品形貌的失真,同时容易在图片上留下明显的线条纹理。针对传统方法的缺点,本文提出采用B样条曲面拟合方法,直接对样品形貌图进行曲面背景拟合,发挥B样条低阶光滑的优点,能够有效克服传统方法的缺陷。在实验中,同时利用传统方法和该方法对金单晶和合成金片的形貌图进行背景扣除,实验结果表明,两种方法都能够扣除样品形貌图中的成像背景,但与传统方法相比,所提出的方法不会造成样品形貌的失真,且不会留下线条纹理,获得了更加良好的背景扣除效果,为进一步分析样品形貌特征提供了更准确可靠的信息,是一种更加有效的TERS形貌成像背景扣除算法。