Design of photonic crystal fibers for dispersion-related applications

A general procedure for design of photonic crystal fibers (PCFs) with desirable dispersion properties is presented. The design model is based on the combination of a rigorous vector mode solver and a scaling transformation for the dispersion properties of the PCFs. In comparison with the conventional design method, the new design procedure is more efficient and can be readily automated for the purpose of design optimization. Several applications of the design procedure, e.g., the design optimization for dispersion shifted fibers, dispersion flattened fibers, and dispersion compensation fibers, are demonstrated and discussed.     

Hankel transform-domain analysis of scattered fields in multilayer planar waveguides and lasers with circular gratings

Radiation patterns of scattered fields with arbitrary azimuthal orders in multilayer planar waveguides and laser cavities with circularly symmetric gratings are formulated based on the volume current method. Full-wave Green's function analysis based on the integral transform method lies at the heart of this approach. Unlike the conventional approach, the dyadic Green's function relates some auxiliary fields to some auxiliary sources in the spectral domain. These auxiliary functions are defined to facilitate the spectral domain formulation in the cylindrical coordinate system and the use of transfer matrix method for obtaining a closed-form solution of the spectral Green's function in multilayer planar structures. More importantly, it is shown that the far-field pattern of the scattered field can be expressed directly in terms of the auxiliary fields in the Hankel transform domain.     

基于混合CatfishPSO-LSSVM 特征选择的入侵检测

入侵检测系统面临的主要问题是计算量大,特征选择被引入解决这一问题。针对现有方法的缺点,利用改进的粒子群算法来搜索最优特征子集,提出了一种基于混合CatfishPSO和最小二乘支持向量机的特征选择方法,利用混合的CatfishBPSO和CatfishPSO选择特征子集并同步对LSSVM的参数进行优化,最后建立了一个基于该特征选择方法的入侵检测模型。在KDD Cup 99数据集上进行的实验结果表明该模型的检测性能较高。     

自调整模糊控制器的控制参数和控制规则

1 引言模糊控制是智能控制研究的方向之一。与传统控制截然不同的是,模糊控制不需要被控对象的精确数学模型。自从E.H.Mamdani1974年在实验室将模糊控制应用于锅炉和     

一种新型高速低功耗BiCMOS分频器

本文设计了一种基于BiCMOS技术的分频器,结合了双极（Bipolar）和CMOS技术的优点。作为分频器的基本单元,锁存器的工作速度直接影响了分频器的性能。通过分离跟踪差分对与交叉耦合对,并减小后者的偏置电流可以提高锁存器的工作速度。同时,合并两个锁存器的跟踪差分对可以减小分频器的功耗。采用0．8μm BiCMOS模型在Cadence SPECTRE中仿真,可以得到这种新型高速低功耗分频器的工作频率上限可以达到2．4GHz,功耗为-1．61dBm。     

用四叉树算法建立自主系统环境模型

对环境建模是自主系统路径规划的基础,针对传统方法中存在的种种缺陷,该文在阐述自主系统中利用激光测距成像雷达的坐标变换法所获取的距离图实时检测障碍物的基础上,利用二值图像的四叉树表示是基于数据区域的一致性判别准则和空间递归分解原理建立起来的一种分层的树形数据结构,将一幅二值图像分为大小相同的四个分区,着重研究了利用模式四叉树建立部分已知或完全未知的环境模型的方法,结果显示其节省了四叉树占用的存储空间,在相同的存储空间情况下,提高了环境分辨率,加快了系统的运行速度,并给出了环境信息的优化策略。     

Resolving Deep Sub-Wavelength Scattering of Nanoscale Sidewalls Using Parametric Microscopy

The quantitative optical measurement of deep sub-wavelength features with sub-nanometer sensitivity addresses the measurement challenge in the semiconductor fabrication process. Optical scatterings from the sidewalls of patterned devices reveal abundant structural and material information. We demonstrated a parametric indirect microscopic imaging (PIMI) technique that enables recovery of the profile of wavelength-scale objects with deep sub-wavelength resolution, based on measuring and filtering the variations of far-field scattering intensities when the illumination was modulated. The finite-difference time-domain (FDTD) numerical simulation was performed, and the experimental results were compared with atomic force microscopic (AFM) images to verify the resolution improvement achieved with PIMI. This work may provide a new approach to exploring the detailed structure and material properties of sidewalls and edges in semiconductor-patterned devices with enhanced contrast and resolution, compared with using the conventional optical microscopy, while retaining its advantage of a wide field of view and relatively low cost.     

iAES:面向网络安全博客的IOC自动抽取方法

网络威胁指标(IOC)作为网络威胁的行为特征,可以按照标准组织起来并部署在安全系统中防御攻击.博客是重要的网络威胁情报来源,及时从中收集网络威胁指标能够快速应对新的安全威胁,但人工阅读并抽取IOC的方式耗时耗力,所以我们迫切需要一种从网络安全博客中自动抽取IOC的方法.为此,本文提出了一种面向网络安全博客的IOC自动抽...