一种基于小波的网络流量发生器设计

网络流量发生器在网络性能分析和协议实现中具有重要的作用。文章基于多分形小波模型，设计了一种自相似网络流量发生器。其中对随机数的生成、序列的截断、自相似序列的生成以及自相似流量的生成等主要设计部分进行了论述。与常用的基于分形布朗运动的模型的流量发生器相比，该发生器生成的流量具有更准确的自相似流量特性。     

自相似业务流复用特性分析

现有研究将复用的自相似业务流Hurst参数值确定为各个业务流中最大的H参数值，与业务流的其他性质无关，这一结论用于网络设备的设计不利于网络资源的有效利用。本文采用简单近似估算，并用分形布朗运动模型生成自相似业务流，彩用小波分析方法估计Hurst参数值。实验结果表明，由于复用合成业务流的渐近自相似的本质，在可以观测的时间尺度范围内业务流的Hurst参数比这理论预测值小；在一定的序列长度下，复用流的Hurst参数的不仅和最大Hurst参数业务流有关，还受到其它业务流，特别是业务流的方差系数所表现出的短时突发性影响，因此对合成业务流的自相似参数具有重要的影响。     

分形天线的IFS实现与特性分析

分形最基本的特征就是自相似特性与分数维，可以很好的用于设计天线。文章讲述了用IFS(迭代函数系统)实现分形天线的过程。并对一些典型的分形天线及分形天线阵列的特性进行了分析。     

基于近距自相似模型的分形图像图像编码方法

为了克服分形图像编码方法速度低的弱点，提出了根据图像模型研究相应算法的思想。基于ρ＾│ｒ│图像模型，导出了与之相应的近距自相似模型，提供了一种适合于该模型的分形图像编码方法。实验结果表明，这种方法大大提高了编码速度，而且能有效地压缩图像数据。     

大模场面积光子晶体光纤全正色散自相似锁模激光器

通过数值模拟和实验研究了一种基于大模场面积光子晶体光纤的高功率全正色散自相似锁模激光器。激光器采用长为1.9 m的掺镱双包层大模场面积光子晶体光纤作为增益介质,腔内没有引入色散图,整个激光器工作在全正色散域。激光器采用环形腔结构,利用非线性偏振旋转锁模和一个窄带高斯滤波器实现了稳定的自相似锁模运转。实验最终获得了直接输出平均功率为5 W,重复频率为72 MHz,单脉冲能量超过69 n J,脉冲宽度为1.699 ps的自相似锁模脉冲输出,经过腔外1200 line/mm的透射光栅对压缩后脉宽为84 fs。激光器可以实现自启动锁模,光束质量因子M2为1.41。     

基于近距自相似模型的分形图像编码方法

为了克服分形图像编码方法速度低的弱点，提出了根据图像模型研究相应算法的思想。基于ρ｜ｒ｜图像模型，导出了与之相应的近距自相似模型，提供了一种适合于该模型的分形图像编码方法。实验结果表明，这种方法大大提高了编码速度，而且能有效地压缩图像数据     

分形图形中的随机动态方向准则

提出了一个新的生成自相似几何分形学的方法－随机动态方向准则。随机方法运用概率论的有关知识，继承了传统的方式和新的符号移位法特点，并将两种方式有机地结合在本的准则之下，增加了生成分形图形的种类。     

基于FBNDP自相似业务源建模

基于分形二项噪音驱动泊松过程（FBNDP）动态原理,我们构建了其仿真模型并进行多次仿真实验,提示了FBNDP模型采样数据轨迹的表面现象,并用R/S法和时间方差法对其自相似强度进行分析计算;另外,自相似过程的非退化自相关结构特性得到图形化验证.     

自相似业务流的快速生成方法及其性能研究

网络中业务流的自相似性正日益受到重视，因为它对网络性能有着很大的影响。在缺乏对自相似模型进行数学分析的情况下，计算机仿真成为当前最有效的研究手段。ＦＧＮ（ＦｒａｃｔａｌＧａｕｓｓｉａｎＮｏｉｓｅ）是目前使用最为广泛的一种自相似模型，本文提出了一种基于其定义的快速生成算法，具有良好的运算速度和精度。     

互补分形图像的光学傅里叶变换

从理论上推导了SC分形图像的衍射强度表达式，并用光学方法进行了SC分形互补屏的傅里叶变换，在频谱面上除中心处，分形互补屏给出了相同的衍射图样，而且也具有对称性和自相似嵌套结构。实验结果与理论上推导出的表达式相吻合。同时，验证了巴俾涅原理。     

A rigorous analytical solution to abrupt dielectric waveguidediscontinuities

A simple analytical method is proposed for analyzing transmitted, reflected, and radiated fields in abrupt discontinuities of dielectric waveguides, such as step discontinuities and sharp bends. Approximate transmitted fields, both guided mode fields and radiated fields, are first calculated by assuming the incident field to be the source field on the discontinuity interface. Next, the approximate reflected fields are calculated by assuming the difference field of the incident and approximate transmitted fields to be the source field on the discontinuity interface. Then, the improvements for these approximate transmitted fields and approximated reflected fields are calculated successively. Only a few successive steps are suffice for obtaining rigorous solutions. Numerical examples are presented for step discontinuities and sharp bends of dielectric slab waveguides     

色散对半球型固体浸没透镜系统透射场的影响

在考虑了半球型固体浸没透镜(h-SIL)内部的反射,应用矢量衍射理论分析了色散对h-SIL的透射场特性的影响.对应不同波长的照明光,h-S1L的材料色散作用将对其透射场特性产生影响.h-SIL的分辨率、焦深和聚焦强度对照明光的波长变化非常敏感,都随着波长的变化成周期性的振荡.     

TE-scattering and reception by a parallel-plate waveguide array

TE-wave scattering and reception by a parallel plate waveguide array is Investigated. A Fourier-transform technique is used to express the scattered field in the spectral domain. The boundary conditions are enforced on the conducting surface and the array apertures to obtain simultaneous equations for the transmitted field inside the waveguide. The simultaneous equations are solved to obtain the transmitted field in a series representation whose first term is the Kirchoff solution. The behavior of the far-zone scattered field and the transmission coefficient are studied in terms of the scattering angle, array size, and frequency     

Mode field diameter measurement conditions for fibers by transmitted field pattern methods

The transmitted near- and far-field pattern methods, measuring the mode field diameter of the fundamental LP01mode in a single-mode fiber are studied. On the basis of measurement error evaluation, the optimum measurement conditions for typical single-mode fibers are determined. Actual measured values for nearly ideal step-index fibers are in good agreement with the theoretical predictions (within 0.2 μm with a standard deviation of 0.05 μm). The mode field diameter measurement by the transmitted field pattern methods is useful for the study of the structural optimization of the single-mode fibers.     

Interaction of Electromagnetic Transient Radiation with Biological Materials

The transmission characteristics of transient electromagnetic pulses in biological material are studied using a plane wave pulse incident normally on a semi-infinite layer model. With the dispersion properties of complex tissue dielectric constants taken into account, the steady state transfer function was examined as a function of frequency. Integral solutions for the transmitted field of a Gaussian pulse were obtained through Fourier transformation. The transmitted waveforms inside muscle were determined numerically for various depths pertinent to biological situations. The results suggest that incident pulse experiences severe reflection at the airtissue interface and, shorter pulses are transmitted more readily than longer ones. For an incident pulse of 50 kV/m and 1 us in pulsewidth, the transmitted amplitude is 221 V/m.     

未知原子态经纠缠腔场信道的隐形传态

为了有效地进行原子态的量子隐形传输,提出了一个使用纠缠腔场的原子量子比特态的量子隐形传输新方案,利用位于高品质光腔中的三能级原子与腔场进行大失谐的相互作用来实现,并讨论了光腔的耗散对量子隐形传输的影响。结果表明,该方案不需要辅助原子就能将一个原子态直接传输到另一个原子上,并且在不考虑光腔损耗的情况下传输效率达到100%;对于小的衰减,对任意态的传输,其保真度都接近1.0。该研究对量子通讯的发展是有帮助的。     

均匀非磁化等离子体与雷达波的相互作用

采用平板几何金属衬底模型对雷达波在均匀等离子体中传播所发生的吸收、反射和衰减进行了数值分析研究,结果表明:等离子体对电磁波的吸收衰减取决于等离子体密度和碰撞频率的共同作用;通过适当选择等离子体密度和等离子体碰撞频率,可以使均匀等离子体对某一雷达波段的吸收达到90%以上,隐身效果显著。     

High frequency fields in the presence of a curved dielectric interface

A high-frequency line source in a dielectric medium that is separated by a concave cylindrical boundary from an exterior medium with lower dielectric constant generates a variety of wave phenomena which have been explored extensively. This problem is reexamined here with a view toward clarifying relevant reflection and transmission characteristics within the framework of ray optics, with emphasis on the more complicated transmitted field. The exterior domain is divided into illuminated and shadow regions separated by the transmitted tangent ray launched by a ray incident at the critical angle. Conventional ray optics is valid far from the tangent ray shadow boundary on the illuminated side. The shadow boundary is surrounded by transition regions wherein Fock type integrals and Weber functions yielding local lateral waves provide alternative representations. On the shadow side, not too far from the shadow boundary, the field can be interpreted via "tunneling" and subsequent radiation along a ray from a virtual caustic to the observer. The tunneling is associated with the initial evanescent decay of the transmitted field excited by a totally reflected incident ray. However, deeper inside the shadow, this mechanism is inapplicable, and the field is expressed either in terms of the Fock integrals or a creeping wave-type residue series. The results are presented in a format that permits insertion into a geometrical theory of diffraction (GTD) user's manual.     

基于结构张量方向引导的改进的Image Quilting图像风格迁移算法

传统的Image Quilting算法在进行块拼接时没有考虑到目标图像的方向场特征的变化,所以传输的纹理不具备方向性特征。针对传统算法的不足,本文提出了一种基于目标图像结构张量方向引导的改进的Image Quilting图像风格迁移算法,从而使得图像风格迁移时不仅保证了颜色及纹理特征能准确传输到目标图像中,同时通过方向场引导,确保了方向信息也能合理传输到目标图像中,同时本文运用图像内容融合技术确保目标图像的形状,边缘,内容等信息较好的留存于渲染图像中。实验表明,改进后的算法能够取得更好的图像风格迁移效果。     

Nonclassical states in optical communication to a remote receiver (Corresp.)

The relation between the density operators of the aperture fields of a single-mode optical transmitter and a single-mode receiver is simply expressed in terms of their quasiprobability distributions. This formulation indicates that when the receiver is so far away that it picks up only a small fraction of the transmitted energy, the state induced in its aperture field by a nonclassical transmitted state differs only slightly from what it would be were a certain equivalent classical state transmitted instead. The implications for remote communications are discussed.