三层固体材料的光声效应理论与实验

Ｒｏｓｅｎｃｗａｉｇ－Ｇｅｒｓｈｏ的光声效应理论推广应用于三层固体材料的研究。给出了在固体和气体交界处的周期温度的一般表达式，数值计算并分析了三层材料中光、热参数和样品厚度变化对光声信号幅度，相位与频率变化关系的影响，并与实验结果进行了对照。     

单轴晶光轴干涉图成因的理论分析

借助于数学工具和一种简单的实验装置,用直观的方法,使理论分析和图形相结合,从理论上解释了单轴晶光轴干涉图的成因,并给出了在白光照射下的干涉花样。搭建了实验光路,结果表明:若用单色光照射,干涉图为明暗相间圆环;若用白光照射,则为一个套一个的环状等色曲线。愈向视域边缘,干涉色级数愈高,等色曲线的数目愈多,密度愈大,表示晶体的双折射率愈大。实验结果与理论分析相吻合。     

同轴双无衍射光的理论与实验

提出同轴双无衍射光的概念。如果两束汇聚角略有不同的同轴无衍射光同时存在，则它们相互之间叠加干涉后产生一种纵向呈周期变化的光场结构，这是一种新的光束空间分布，这种光束在横向仍是一种同心环光斑，可用于精密对准。而在不同纵向位置，这些同心环的强度分布是不同的，且是周期性变化的。同轴双无衍射光的轴向周期性可用于沿光束传播方向的定位。文中提出了双环缝法、分段圆锥透镜法、正弦相位环光栅法等实现同轴双无衍射光的理论与实验方法，分析了同轴双无衍射光的横向与纵向传播的衍射光斑特性，理论计算与实验测量的结果基本相符合。     

无衍射光的干涉实验与理论分析

分析了两束无衍射光的干涉场分布形式和干涉条纹轨迹。将一束单色光入射两小孔产生的两束相干光照射轴锥镜,在轴锥镜后将产生两束无衍射光。根据单束倾斜光入射轴锥镜的无衍射理论,分析出这两束无衍射光产生的干涉场为每束无衍射光的无衍射场的线性叠加。利用零阶贝塞尔函数的零点公式,推导出两束无衍射光的干涉条纹的轨迹为双曲线。计算结果表明,干涉场中两中心的间距与两孔实际的间距和干涉场距轴锥镜的距离成正比。实验结果与理论仿真相一致。     

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     

光轴平行晶体表面时的锥光干涉图

针对光轴平行晶体表面时的锥光干涉图,提出了计算干涉场中振幅和相位分布的方法,据此绘制完整的干涉图,方便地显示出晶体参数改变时锥光干涉图的变化规律．用CCD摄像机拍摄了铌酸锂晶体的锥光干涉图,结果与理论完全一致。     

新型高性能激光光声光谱球形光声池：理论和实验研究

从理论上讨论了球形光声池共振模式的声学特征，计算表明，与常用的圆柱形光声池比较，球形光声池具有更高的Ｑ值；利用球形光声池和钛宝石激光器的光声光谱仪，从实验上测量了球形光声池的共振模式，与理论计算结果一致；该球形光声池的声学Ｑ值达到５９０，明显高于圆柱形池的结果；利用该装置成功地记录了Ｃ２Ｈ２ １２７５０ｃｍ＾－１附近的一段弱谱带，与本实验室高灵敏的激光腔内吸收光谱仪（ＩＣＬＡＳ）得到的结果相比，具     

光耦合理论及其在通信元器件中的应用

运用矩阵光学中变换矩阵的理论,并以重叠面积积分的方法为基础,推导出了普遍适用于计算光在光通信元器件中光耦合效率的理论公式,可通过设置边界条件计算单模光纤、扩束光纤、半导体激光二极管以及光波导等不同光学元器件之间的耦合效率。导出了计算单模光纤之间和单模光纤与扩束光纤之间存在横向偏移、轴向偏移时的耦合效率理论通用公式。阐述了扩束光纤的制作方法及光在扩束光纤中的传播,并根据所推导耦合效率理论公式计算结果与单模光纤间和单模光纤与扩束光纤间的耦合实验数据进行了比较。     

光折变自适应光外差探测系统理论研究

首次对光折变自适当光外差探测系统的工作状态进行了较全面分析。给出了系统的最小可探测信号功率和可提供的参考光功率，指出了影响系统特性的关键参数。     

光泵磁共振实验探讨

本文讨论了在光泵磁共振实验中,地磁场垂直分量的抵消、样品泡所在处恒定磁场的确定和实验中的干扰信号等问题。阐明了地磁场垂直分量不被抵消情况下,对实验结果的影响;在实验中采用利用一种元素测量样品所在处磁场的方法,准确确定样品泡所在处的恒定磁场;最后对实验中的干扰信号进行了分析。     

Auxiliary Graph for Attribute Graph Clustering

Attribute graph clustering algorithms that include topological structural information into node characteristics for building robust representations have proven to have promising efficacy in a variety of applications. However, the presented topological structure emphasizes local links between linked nodes but fails to convey relationships between nodes that are not directly linked, limiting the potential for future clustering performance improvement. To solve this issue, we offer the Auxiliary Graph for Attribute Graph Clustering technique (AGAGC). Specifically, we construct an additional graph as a supervisor based on the node attribute. The additional graph can serve as an auxiliary supervisor that aids the present one. To generate a trustworthy auxiliary graph, we offer a noise-filtering approach. Under the supervision of both the pre-defined graph and an auxiliary graph, a more effective clustering model is trained. Additionally, the embeddings of multiple layers are merged to improve the discriminative power of representations. We offer a clustering module for a self-supervisor to make the learned representation more clustering-aware. Finally, our model is trained using a triplet loss. Experiments are done on four available benchmark datasets, and the findings demonstrate that the proposed model outperforms or is comparable to state-of-the-art graph clustering models.     

Graph kernels,hierarchical clustering,and network community structure: experiments and comparative analysis

There has been a quickly growing interest in properties of complex networks, such as the small world property, power-law degree distribution, network transitivity, and community structure, which seem to be common to many real world networks. In this study, we consider the community property which is also found in many real networks. Based on the diffusion kernels of networks, a hierarchical clustering approach is proposed to uncover the community structure of different extent of complex networks. We test the method on some networks with known community structures and find that it can detect significant community structure in these networks. Comparison with related methods shows the effectiveness of the method.     

Graph reconstruction and quantum statistical mechanics

We study how far it is possible to reconstruct a graph from various Banach algebras associated to its universal covering, and extensions thereof to quantum statistical mechanical systems. It turns out that most the boundary operator algebras reconstruct only topological information, but the statistical mechanical point of view allows for complete reconstruction of multigraphs with minimal degree three.     

Graph theory,SO(n) current algebra and the Virasoro master equation

We announce an isomorphism between a set of generically irrational affine-Virasoro constructions onSO(n) and the unlabelled graphs of ordern. On the one hand, the conformal constructions are classified by the graphs, while, conversely, a group-theoretic and conformal field-theoretic identification is obtained for every graph of graph theory. High-level expansion provides a strong argument that each construction is unitary down to some finite critical level.This work was supported in part by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Division of High Energy Physics of the U.S. Department of Energy under Contract DE-AC03-76SF00098 and in part by the National Science Foundation under grant PHY85-15857     

Spectra of Semi-Infinite Quantum Graph Tubes

The spectrum of a semi-infinite quantum graph tube with square period cells is analyzed. The structure is obtained by rolling up a doubly periodic quantum graph into a tube along a period vector and then retaining only a semi-infinite half of the tube. The eigenfunctions associated to the spectrum of the half-tube involve all Floquet modes of the full tube. This requires solving the complex dispersion relation \({D(\lambda,k_1,k_2)=0}\) with \({(k_1,k_2)\in(\mathbb{C}/2\pi\mathbb{Z})^2}\) subject to the constraint \({a k_1 + bk_2 \equiv 0}\) (mod \({2\pi}\)), where a and b are integers. The number of Floquet modes for a given \({\lambda\in\mathbb{R}}\)  is  \({2\max\left\{ a, b \right\}}\). Rightward and leftward modes are determined according to an indefinite energy flux form. The spectrum may contain eigenvalues that depend on the boundary conditions, and some eigenvalues may be embedded in the continuous spectrum.     

物理图像应用的八大要义

图像是描述物理规律的重要手段，特别是一些用文字、公式很难表达清楚的物理规律，可以用图像直观、简明的表达出来．图像可以包含有关物理现象的许多信息，反映丰富的物理内涵；利用图像分析物理问题的方法有着广泛的应用．在近年物理高考中，图像题有较大的比重，且题型多样，有关图像试题的设计意图，明显由“注重对状态的分析”转化为“注重对过程的理解和处理”．     

Graph partitioning induced phase transitions

We study the percolation properties of graph partitioning on random regular graphs with N vertices of degree k. Optimal graph partitioning is directly related to optimal attack and immunization of complex networks. We find that for any partitioning process (even if nonoptimal) that partitions the graph into essentially equal sized connected components (clusters), the system undergoes a percolation phase transition at f = fc = 1-2/k where f is the fraction of edges removed to partition the graph. For optimal partitioning, at the percolation threshold, we find S approximately N 0.4 where S is the size of the clusters and l approximately N 0.25 where l is their diameter. Also, we find that S undergoes multiple nonpercolation transitions for f相似文献   

Test spaces,dacey spaces,and completeness of inner product spaces

We show that a test space consisting of the unit sphere of a real or complex inner product spaceS and of the set all maximal orthonormal systems inS, is algebraic iffS is Dacey or, equivalently, iffS is complete. In addition, we present another completeness criterion.This research is supported by the grant G-368 of the Slovak Academy of Sciences, Slovakia.