关于真空中的位移电流、Maxwell方程组、电磁场的源及Jefimenko公式的几点注记

通过分析指出：电磁场是一个不可分割的整体，Maxwell方程组是电磁场的运动方程，电磁场的源是电荷与电流的分布，Jefimenko公式是真空中Maxwell方程组的解。     

各向异性场对三明治膜巨磁阻抗效应的影响

根据具有巨磁阻抗(GMI)效应的实际三明治样品的状况，提出三明治结构作为理论计算的模型，考虑了磁性层的各向异性场，利用一定边界条件下的Maxwell方程和Landau-Lifshitz方程对模型进行了理论计算，得到了阻抗与频率、各向异性场等因素间的函数关系.在此基础上，着重讨论了各向异性场H_k的作用.H_k的大小、方向均会对GMI效应造成影响，最佳的H_k应在400A/m左右，位于面内并与电流垂直.还证实了三明治结构中磁性层的磁致伸缩只会减弱G 关键词： 巨磁阻抗(GMI)效应 三明治膜 Maxwell方程 Landau-Lifshitz方程     

从运动镜面的反射谈起

用运动界面的边值关系推导运动镜面的反射定律，引出电磁波边值关系的协变性，对积分形式的Maxwell方程的协定性进行了讨论。     

微波谐振腔中电子与微波作用的非稳态过程研究

 在微波腔中微波场影响电子的运动，同时电子束作为电流源也产生辐射，影响微波场，这种相互作用包含线性和非线性过程。根据Maxwell理论，微波腔中的实际微波场可以按微波腔的模式展开，而且不同模式与电子束之间的相互作用不同。将电子束作为激励源，根据Maxwell方程和电子受到的洛伦兹力，建立不同模式在电子束作用下的激励方程和电子束电子在不同模式作用下的运动方程（即微波谐振腔中电子束与微波场相互作用的自洽方程组），并由此进一步分析一维情况下单间隙微波腔中微波建场、辐射场呈指数增长和饱和等非稳态作用过程，该过程涉及到电子束与微波作用的线性和非线性过程。     

浅析一维Bragg堆的色散特性

基于Maxwell方程和周期结构的Bloch定理，求解Bragg堆中的电磁场边值问题，得到Bragg堆的色散关系，同时讨论了Bragg堆的电磁带隙特征．     

三明治结构与同轴电缆结构磁性材料巨磁阻抗效应的理论研究

根据两种具有巨磁阻抗（GMI）效应的磁性材料实验样品，提出了两种理论模型（同轴电缆结构——Cu丝外覆软磁材料的圆柱形；三明治结构——Cu或Ag为中间层外包软磁层的三明治膜），利用Maxwell方程和Landau_Lifshitz方程对其GMI效应的机理进行了理论研究.证明了两种模型的差别仅仅是形状因子的不同，从而由理论上证实了两种结构GMI效应增强的内在一致性.证实了在同种磁性材料情况下，双层结构具有结构方面的优越性.并对照实验数据讨论了参数的影响，得到与实验定性相符的结果. 关键词： 巨磁阻抗效应 三明治膜 Maxwell方程 Landau_Lifshit     

利用场耦合理论研究开放微波谐振腔

在高功率微波(HPM)和驻波加速器的研究中，开放微波腔模式(微波场分布、频率和Q值)一直是大家所关心的问题，微波腔通常是具有复杂形状的圆柱腔；多年来，关于微波腔模式的研究一直在进行。从电磁理论(Maxwell方程)和有关的数学方法出发，建立开放微波腔模式同封闭微波腔模式之间的场耦合方程，由此确定开放微波腔模式。     

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根据狭义相对性原理,应用Lorentz变换法则,从相对运动媒质静止参考系中的有关结论,获取了实验室参考系中所需结果。通过证明平面波相位是Lorentz不变量,指出实验室参考系中平面波解的存在性。由Lorentz变换导出了实验室参考系中平面波色散关系表示式,据此给出运动媒质的波动方程。由Lorentz变换导出运动媒质中平面波Maxwell方程。基于这些结果,应用Lorentz变换获得了平面波从自由空间垂直入射到各向同性运动等离子体半空间时反射波与透射波的有关特性。     

守恒无伪解麦克斯韦方程间断元研究:(Ⅰ)一维和二维情况

考察了电、磁场分量分别基于不同近似函数空间展开的一维和二维Maxwell方程间断元求解方法。结合中心数值通量和电、磁场分量近似函数空间的不同组合,构造了各种间断元算子。通过用这些算子在规则和不规则网格上编码分析一维和二维金属腔的谐振模式,详细考察了算子的收敛和伪解支持性,并据此对基函数进行了优选。算子在时域和频域对谐振模式的计算结果彼此符合良好。优选的Maxwell方程间断元算子不仅同时具备能量守恒和免于伪解的特性,且无需引入辅助变量,为设计高品质Maxwell方程间断元算法和研发相关电磁场模拟软件提供了支撑。     

约束,变换方程和Hamilton函数

受理想、完整约束并且主动力全为保守力的力学 系统，如果所选的广义坐标使变换方程中不显含时间， 则相应的Ｈａｍｉｌｔｏｎ函数是系统的总机械能；如果所选 的广义坐标使变换方程中显合时间，则相应的 Ｈａｍｉｌｔｏｎ 函数是系统的广义能量．系统所受到的约束是否稳定，不能作为Ｈａｍｉｌｔｏｎ函数是否总机械能的判据．     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.