Resonance Absorption of Metallic Plate with Subwavelength Hole Array

The optical reflectance by a metallic plate arranged with array consisting of subwavelength periodic square hole is investigated by using the three-dimensional finite-difference time-domain method （3D-FDTD）. There are dips in the reflectivity spectra, which indicate the absorption peaks. The absorption peaks behave differently according to the ratio of hole width and the period of the hole array. Combined with the near fields of the absorption peaks, it is found that the surface plasmon （SP） resonance on the surface of plate and localized SP in the hole play a major role for the two absorptions.     

浅谈军校大学物理分层教学法

本文针对士官学员基础较差、层次参差不齐等特点,在其大学物理的教学中实施了分层教学法.分层教学法主要包括教学对象分层、教学目标分层、教学过程分层和考核评价分层四个环节.教学实践表明,该种教学方法能够激发学员的学习热情和潜能,同时有利于提高学员的综合素质.     

基于网络环境的大学物理实验教学改革研究与实践

本文结合我校大学物理实验课程改革的具体实际, 介绍了课程教学的设计理念和课程教学的组织模 式, 通过课程改革的运行, 总结出大学物理实验课程改革对人才培养发挥的作用, 指出了课程改革存在的问题, 以 及解决问题的方法     

Cu在Zr掺杂CeO_2(111)表面吸附特性的第一性原理研究北大核心CSCD

采用第一原理计算方法,计算并分析了Cu在Zr掺杂的CeO2(111)表面吸附的吸附能及所形成的Cu/Ce0.75Zr0.25O2(111)界面体系的吸附结构和电子结构.结果表明:1)Cu在Ce0.75Zr0.25O2(111)表面上邻近Zr原子的次层O的顶位吸附最强;2)Zr的掺杂增强了Cu与CeO2衬底的作用;3)Cu的吸附在Ce0.75Zr0.25O2(111)表面的O2p-Ce4f态之间引入了新的间隙态,这些间隙态主要来自于Cu3d与衬底O2p的杂化作用,这是Cu与Ce0.75Zr0.25O2有较强作用的主要原因;4)吸附的Cu被Ce0.75Zr0.25O2氧化为Cuδ+,并伴随着表面Ce4+→Ce3+的转化,该反应可以总结为:Cu/Ce4+→Cuδ+/Ce3+.     

激光陀螺捷联惯导系统参数稳定性与外场自标定

惯导系统参数稳定性是决定系统精度的重要因素。基于激光陀螺捷联惯导系统参数稳定性统计分析,建立了适合激光陀螺捷联惯导系统外场自标定的加速度计组件误差参数模型。以惯性组合转动后重新调平的水平姿态修正量以及静态下重力测量误差为观测量,不依赖外界方向姿态转角等基准信息,实现了加速度计组件主要误差参数在外场条件下的自标定,并给出了标定参数的修正方法。实验表明,常温下加速度计组件的标定参数发生明显变化,采用外场标定方法可对其进行修正,相应的水平姿态最大误差由65″减小到10″。该方法标定精度好,标定时间短,操作简便,且对基座不稳造成的瞬时姿态小扰动影响有抑制能力。     

Absorption and dispersion control in a five-level M-type atomic system

We investigate the steady optical response of a coherently driven five-level M-type atomic system in three different situations.When all three coupling fields have the same zero detuning,we just find one deep transparency window accompanied by a steep normal dispersion in the probe absorption and dispersion spectra.When two coupling fields are detuned from the relevant transitions to the same extent,however,a second deep transparency window may be observed in the presence of a narrow absorption line of linewidth ～50 kHz.In this case,two single-photon far-detuned transitions can be replaced by a two-photon resonant transition,so the five-level M system in fact reduces into a four-level quasi-Λ system.Finally,we note that no deep transparency windows and no narrow absorption lines can be found when all three coupling fields have unequal detunings.     

冷铷原子样品中高效静态光信号的生成与调制

为了提高光信息处理元件的性能,实现高效率光信号的静止与存储,本文建立了由双向耦合场耦合的冷铷（87Rb）原子的四能级双Λ型能级机制,并对此机制在生成静态光信号时要求的高效性、持续时间,控制耦合场所需的操作条件以及对信号场强度的相位调制等进行了研究。首先,选取四能级双Λ型87Rb冷原子精细能级,用一对反向传播的行波激光场对能级进行近共振耦合,并沿耦合场方向输入一个正向弱光信号进行探测。接着,通过适当的绝热开启、关闭耦合场,存储光信号和生成高保真度静态光信号。然后,通过选取87Rb原子的不同精细能级结构,得出实现静态光所需满足的必要条件。最后,采用相位调制法对光信号进行处理。结果表明：生成的静态光信号具有高效性,过程持续时间约为80μs;相位调制法可以周期调节静态光脉冲的强度。在此机制下生成的静态光信号满足高效性、易于全光调节和长时效性等要求。     

考虑通孔横向热传输效应的三维集成电路热分析

考虑横向热传输效应,构造一种包含通孔结构的叠层芯片三维热传输模型.在具体的工艺参数下验证叠层芯片层数、通孔密度、通孔直径和后端线互连层厚度对三维集成电路热传输的影响.结果显示,采用该模型仿真得到的各层芯片温升要低于不考虑横向热传输时所得到的温升,差异最大可达10%以上,并且集成度要求越高,其横向热传输效应的影响越明显.该模型更符合实际情况,能够更准确地分析三维集成电路的各层芯片温度.     

Low-frequency vibrational modes of glutamine

High-resolution terahertz absorption and Raman spectra of glutamine in the frequency region 0.2 THz-2.8 THz are obtained by using THz time domain spectroscopy and low-frequency Raman spectroscopy. Based on the experimental and the computational results, the vibration modes corresponding to the terahertz absorption and Raman scatting peaks are assigned and further verified by the theoretical calculations. Spectral investigation of the periodic structure of glutamine based on the sophisticated hybrid density functional B3LYP indicates that the vibrational modes come mainly from the inter-molecular hydrogen bond in this frequency region.     

Transition of Magnetoresistance in Co/Alq3 Granular Film on Silicon Substrate

A Coo.3s （Alq3）o.62 granular film is prepared using a co-evaporating technique on a silicon substrate with a native oxide layer. A crossover of magnetoresistance （MR） from positive to negative is observed. The positive MR ratio reaches 17.5% at room temperature （H = 50kOe）, and the negative MR ratio reaches -1.35% at 1514 （H = 10 kOe）. Furthermore, a metal-insulator transition is also observed. The transition of resistance and MR results from the channel switching of electron transport between the upper Co-AIq3 granular film and the inversion layer underneath. The negative MR originates from the tunneling magnetoresistance effect due to the tunneling conducting between adjacent Co granules, and the positive MR may be attributed to the transport of high mobility carriers in the SiO2/Si inversion layer.