BaWO_4晶体的拉曼光谱分析

BaWO4晶体是一种很有应用前景的喇曼激光晶体。本文根据对称性分类,用商群理论分析了Ba-WO4晶体的喇曼光谱。一个原胞中含有两个BaWO4分子,理论上有36个振动膜,和我们用群论计算得数目一致。其中有18支拉曼活性光学膜。我们测得了10支拉曼峰,并对测得的各个配置的拉曼峰进行了指认,其中X(ZZ)X配置921cm-1处的喇曼峰强度最强,线宽较窄,对于作为喇曼激光晶体来讲是很有益的。     

Design of Two-Dimensional Photonic Crystal Edge Emitting Laser for Photonic Integrated Circuits

An edge emitting laser based on two-dimensional photonic crystal slabs is proposed. The device consists of a square lattice microcavity, which is composed of two structures with the same period but different radius of air-holes, and a waveguide. In the cavity, laser resonance in the inner structure benefits from not only the anomalous dispersion characteristic of the first band-edge at the M point in the first Brillouin-zone but also zero photon states in the outer structure. A line defect waveguide is introduced in the outer structure for extracting photons from the inner cavity. Three-dimensional finite-difference time-domain simulations apparently show the in-plane laser output from the waveguide. The microcavity has an effective mode volume of about 3.2（λ/nslab）^3 for oscillation mode and the quality factor of the device including line defect waveguide is estimated to be as high as 1300.     

矩母函数:拟对称概率测度

本文用凸函数的方法研究了概率测度的矩母函数和由C.J.Stone提出的拟对称性,并刻画了Martin边界的法向量.拟对称性在随机游动的比例极限定理中是一个重要的概念.这些结果可应用于Levy过程的研究.     

Structural Characteristics of Liquid Sn

We investigate the structural properties of liquid Sn. With the help of the internal friction (tanФ) method, it is found that a peak appears in the tan Ф - T curve, suggesting that an anomalous discontinuous temperatureinduced structure change may take place in liquid Sn. From the experimental data of pair distribution functions, we calculate the viscosity η and the excess entropy S and it is found that there are a peak of viscosity in the η-T curve and a bend of excess entropy in the S - T curve, which give a positive support to the appearance of the internal-friction peak in the tan Ф- T curve.     

切割次序的优化

这是一个如何安排加工次序的组合优化问题,文章首先建立了一般问题的数学模型,在对其求解过程中我们采取了分枝限界法,保证了所得结果的最优性,且具有很高的时效性.其次针对某部门所采取的贪婪算法给以了评价,在评价中以其近似解与最优解的接近程度、得到最优解的概率为标准,利用计算机模拟对其进行评估,发现对于该问题贪婪算法并不能保证解的最优性,但近似程度较好。而后我们对调整刀具费用为0的情形进行了讨论,首先给出了一个引理,然后给出了一个简明的优化准则:当对各切割平面按其厚费比以不升序排列时,所得次序为最优加工次序,最后利用题中所给数据进行了验证,再次表明了所得结论的正确性。     

在玻璃转变温度及其以上温区聚苯乙烯/聚氧化乙烯共混物的动力学弛豫行为

用熔融共混法制备了不同组分的聚苯乙烯(PS)与聚氧化乙烯(PEO)共混物(PS/PEO).在玻璃转变温度T_g及其以上温区,利用相对能量耗散技术研究了该共混物的动力学行为.结果发现,在能量耗散-温度曲线上出现了两个弛豫型的耗散峰(α峰和α′峰).分析表明,α峰是与PS玻璃转变有关的特征耗散峰; α′峰则对应于一种“液-液转变”.两者的弛豫时间τ都不满足Arrhenius关系.此外,还研究了组分对这两个弛豫型耗散峰的影响,并给予了定性的解释. 关键词： 相对能量耗散 玻璃转变 力学弛豫     

栅耦合型静电泄放保护结构设计

提出了一种新型栅耦合型静电泄放(ESD)保护器件——压焊块电容栅耦合型保护管.该结构不仅解决了原有栅耦合型结构对特定ESD冲击不能及时响应的问题，而且节省了版图面积，提高了ESD失效电压.0.5 μm标准互补型金属氧化物半导体工艺流片测试结果表明，该结构人体模型ESD失效电压超过8 kV.给出了栅耦合型ESD保护结构中ESD检测结构的设计方法，能够精确计算检测结构中电容和电阻的取值. 关键词： 静电泄放 栅耦合 金属氧化物半导体场效应管 压焊块电容     

Kondo Resonance versus Fano Interference in Double Quantum Dots Coupled to a Two-Lead One-Ring System

We analyse the transport properties of a coupled double quantum dot （DQD） device with one of the dots （QD1） coupled to metallic leads and the other （QD2） embedded in an Aharonov-Bhom （A-B） ring by means of the slaveboson mean-field theory. It is found that in this system, the Kondo resonance and the Fano interference exist simultaneously, the enhancing Kondo effect and the increasing hopping of the QD2-Ring destroy the localized electron state in the QD2 for the QD1-leads, and accordingly, the Fano interference between the DQD-leads and the QD1-leads are suppressed. Under some conditions, the Fano interference can be quenched fully and the single Kondo resonance of the QD1-leads comes into being. Moreover, when the magnetic flux of the A-B ring is zero, the influence of the parity of the A-B ring on the transport properties is very weak, but this influence becomes more obvious with non-zero magnetic flux. Thus this model may be a candidate for future device applications.     

Phase Transition and EOS of Marmatite （Zn0.76Fe0.23S） up to 623K and 17 GPa

In situ energy dispersive x-ray diffraction for natural marmatite （Zn0.76Fe0.23S） is performed up to 17. 7 GPa and 623 K. It is fit, ted by the Birch-Murnaghan equation of state （EOS） that Ko and α0 for marmatite are 85（3）GPa and 0.79（16）＊10^-4 K^-1, respectively. Fe^2＋ isomorphic replacing to Zn^2＋ in natural crystal is responsible for high bulk modulus and thermal expansivity of marmatite. Temperature derivative of bulk modulus （OK/OT）p for marmatite is fitted to be -0.044（23） GPaK^-1. The unambiguous B3-B1 phase boundaries for marmatite are determined to be Pupper（GPa）= 15.50 - 0.016T（℃） and Plower （GPa）=9.94-0.012T（℃） at 300-623K.     

用于增强现实的头盔显示器的设计

穿透式双通道头盔显示器 (HMD)是增强现实系统中的关键部件。本文给出了一种新颖的穿透式双通道头盔显示器的设计方案 ,使得当在用于增强现实系统中时 ,能够获得更大的透过率 ,以获得清晰的外部世界与内部产生的场景信息。同时通过成功的光学设计 ,获得了大视场、高分辨率的光学系统