In Search of Alternatives to Higgs Fields

Field equations of the S² sigma model (“the A3 model”) with spontaneously broken Z(2) symmetry are presented for (D+1)-dimensional space–time. The A3 model is an extension of the sine-Gordon equation (SGE) and supports kink-like U(1) charged solitons which are a generalization of neutral solitons of the SGE. The natural question arises — is the A3 model completely integrable in (1+1)-dimensional space–time? The Lorentz-invariant scalar A3 field can be viewed as a promising alternative to the Higgs field.     

磁悬浮传输出系统平衡法控制器的设计

介绍了磁悬浮传输系统的组成及工作原理 ,通过线性方法建立了系统的数学模型 ,并基于此模型使用平衡法设计了闭环控制器 ,分析它的稳态性能及抗干扰能力 ,得出性能良好的控制方案并给出计算机仿真结果 .     

基于单端半导体光放大器的可调谐超短光脉冲源理论与实验研究

超短光脉冲源是光时分复用(OTDM)系统中的关键器件.提出了一种基于单端半导体光放大器(SOA)的注入型主动锁模光纤激光器产生超短光脉冲的方案，建立了该方案的理论模型.实验实现了高消光比稳定的重复频率10—40GHz皮秒级光脉冲的输出，输出波长在30nm范围内连续可调. 关键词： 超短光脉冲 单端半导体光放大器 主动锁模     

SD对壳模型: 偶偶Pt核低激发态性质

利用SD对壳模型讨论了偶偶Pt核低激发态的集体性质. 结果发现在该模型下, 利用一个仅含有3个参数的哈密顿量, 可以很好地再现偶偶Pt核低激发谱的集体性质.     

聚甲基丙烯酸甲酯掺杂Ce3+的飞秒激光三维信息存储

用飞秒激光(200 fs,1 kHz,800 nm)脉冲在掺杂稀土离子Ce3 的聚甲基丙烯酸甲酯(PMMA)膜中进行了光存储实验研究,包括对样品的吸收光谱、激光照射前后的电子旋转共振(Electron spin resonance,ESR)光谱的测量和讨论。结果表明掺杂稀土离子Ce3 的聚甲基丙烯酸甲酯膜具有较低的写入阈值,有利于高速、并行的三维光存储。实验结果采用传统光学显微镜并行读出。给出了四层存储结果(点间距和层间距分别是4μm和16μm),并讨论了脉冲能量的大小对空腔尺寸的影响,进行高密度存储时,在保证读出信号灰度值足够大的情况下,应选择尽量小的激光脉冲写入能量。实验结果表明这种材料可以应用于三维光信息存储。     

Differential Pulse Polarographic Determination of Nitrate in AUT Solution

A differential pulse polarographic method for the determination of nitrate ion has been developed. With 0.5 M CaCl₂ as supporting electrolyte, NO^?₃ is reduced to give a peak with E_1/2=–1.836 Volt vs. the Ag/AgCl electrode. The differential pulse polarographic peak height is proportional to the nitrate concentration from 20 to 60 ppm. The detection limit for nitrate is 2 ppm in pure aqueous solution. In the determination of 40 ppm nitrate a relative precision (relative standard deviation) of less than 2% was achieved. Nitrite interferes seriously and should be absent if accurate results are required. The method has been applied to the determination of nitrate in Ammonium Uranyl Tricarbonate (AUT) Solution, results obtained by this method are compared to those obtained by ion chromatography. The agreement between the two sets of results suggests that the DPP method can be used with a fair degree of confidence.     

脉冲离散效应对光纤中基于交叉相位调制的脉冲压缩的影响

通过数值模拟，分析了脉冲离散效应对单模光纤正群速色区基于暗孤子交叉不相位调制的脉冲压缩的影响，并提出了减轻这种影响的办法，作者发现，即使暗孤子与被压缩脉冲的中心波长相差很小，离散效应对脉冲压缩的影响也很大，离散效应不仅导致脉冲压缩比的减小和压缩后脉冲峰值功率的降低，而且还导致脉冲压缩所需最佳光纤长度的增加以及压缩后的脉冲呈现不对称性，还发现，若采取本文提出了的非同步耦合法，则可以明显地弥补离散效应     

单个波长到多个波长的变换实验

报道一种波长变换的新方法.采用此方法不需要任何泵浦光便能够直接将信号光变换成在特定谱宽内的任意多个任意波长的变换光,这对于将来的波分复用光网络提供了较大的方便.此波长变换的原理是利用色散位移光纤的非线性效应产生超连续光谱(SC)信号,由于这种SC信号携带有变换光信号,对这种连续谱进行滤波便能够得到所需要的任意频率的变换信号.此变换方式具有变换频带宽,偏振不敏感的优点。     

纳米Zn-Co铁氧体的固相合成及电磁损耗特性研究

采用NH₄HCO₃与FeCl₃·6H₂O，Zn(NO₃)₂·6H₂O，Co(NO₃)₂·6H₂O进行室温固相反应制得前驱物，经微波加热处理后，进而热分解分别制得复合氧化物ZnFe₂O₄、CoFe₂O₄和Co_0.5Zn_0.5Fe₂O₄。由激光粒度分析仪、XRD和SEM表征：获得了颗粒分布比较均一、平均粒度为65 nm左右、立方晶系尖晶石结构的纳米铁氧体粉体。经测试样品的相对介电常数和相对磁导率后，研究了它们的电磁损耗特性。结果表明：Co_0.5Zn_0.5Fe₂O₄在100～1 800 MHz内比另外两种铁氧体具有更好的电磁损耗特性。     

Anodic Stripping Voltammetry of Heavy Metals at Nanocrystalline Boron‐Doped Diamond Electrode

Boron‐doped Diamond (BDD) electrode has become one of the important tools for heavy metal detection. By studying some analytical parameters of DPASV method, like deposition time and potential in different electrolyte concentrations (acetate buffer), the conditions for detecting very low metal ion levels (Zn, Cd, Pb, and Cu) could be chosen. Diluted electrolyte (0.01 M buffer) was one of the factors favoring low detection and quantification limits, but its quantification range is short in comparison to more concentrated media. For ?1.7 V deposition potential, the detection of single metal at ppb levels was reached in 60 s deposition time. Understanding different metal‐metal interactions shows the limits to the simultaneous determination of heavy metals at BDD. Quantification was possible for the simultaneous determination of Zn, Cd and Pb despite the overlapping of Zn and Cd peaks. The performance of the BDD was compared with that of another C‐based solid electrode: the glassy carbon electrode (without mercury plating). A lower base line current, wider potential range, higher sensitivity (3 to 5 times higher than GC) and longevity of the material were noticed for the BDD.