基于微处理器的数字信号传输性能分析仪的研究

根据数字基带传输系统的基本原理,设计了一套基于微处理的简易数字信号传输性能分析仪,系统主要由数字信号发送模块、信号传输模块和数字信号接收分析模块三部分构成,其中信号发送模块由数字信号发生器和信道模拟低通滤波器等组成.整个系统采用微处理器STM32F103实现码元速率的控制、信道切换、噪声电平调节、扩频与解扩以及同步信号的提取.系统经测试,解码的曼彻斯特编码数据与发送端完全一致,同步信号稳定和可靠.     

云计算安全关键技术分析

云计算以一种新兴的共享基础架构的方法,提供资源池化的由网络、信息和存储等组成的服务、应用、信息和基础设施等的使用。云计算的按需自服务、宽带接入、虚拟化资源池、快速弹性架构、可测量的服务和多租户等特点,直接影响到了云计算环境的安全威胁和相关的安全保护策略。云计算具备了众多的好处,从规模经济到应用可用性,其绝对能给应用环境带来一些积极的因素。如今,在广大云计算提供商和支持者的推崇下,众多企业用户已开始跃跃欲试。然而,云计算也带来了一些新的安全问题,由于众多用户共享IT基础架构,安全的重要性非同小可。本文分析了云计算特定的安全需求和解决方案以及国内外的研究和产品现状。     

Fractional directional derivative and identification of blur parameters of motion-blurred image

The blur direction and extent of motion-blurred image, which is degraded by the relative motion between the camera and object scene, are needed in the methods of image restoration, such as blind deconvolution. The recently developed identification method is based on integer-order derivative, which can directly extract the blur angle and extent from blurred image itself. However, this method is sensitive to noise. As an extension to the fractional-order derivative, a noncausal fractional-order directional derivative operator is derived. Based on this new operator, a novel method identifying blur parameters is developed in this work. The performance comparison between the fractional-order and integer-order methods are also presented, which demonstrate that the former provides better immunity to noise and capacity to identify the motion-blur direction and extent.     

基于滤光片型可变光衰减器的测试及控制设计

以Santec公司OVA-650可变光衰减模块为设计对象,设计制作用户可控制数字光衰减器.分析OVA-650的衰减原理,建立测试系统,确定步进电机移动步数与衰减量之间的关系.测试OVA-650内部衰减量与反馈电压之间的对应关系并建立衰减量与电压的对换表,采用Matlab进行数值分析及曲线拟合,得到衰减量与电压关系的真实曲线,建立对应关系.建立用户控制系统,键盘输入用户想得到的衰减量.本设计采用二相八拍控制步进电机,选择12位模数转换芯片MAX197,并采用自适应环路算法,精确定位到键盘输入的衰减量,可控制范围为0～35dB,整个系统误差控制在±0.1dB以内,液晶显示到0.01dB.     

“军事通信基础”课程设计

统编“军事通信基础”教材已经投入教学,相应的课程标准也已制定,因此,深入领会课程标准、精心设计教学思路和单元内容、周密组织教学实施、科学评价教学效果,开拓学生视野、加强实践操作能力,优化教学构想等环节成为课程教学良性发展的关键因素。基于此形成了课程设计,旨在培养学生任职能力和素质,提高教学质量。一期的教学实践初步验证了课程设计的必要性和有效性。     

Temperature-dependent investigation of a high-breakdown voltage andlow-leakage currentGa0.51In0.49P/In0.15Ga0.85Aspseudomorphic HEMT

We reported a newly designed double delta-doped GaInP/InGaAs pseudomorphic HEMT with high temperature-dependent performances. In addition to the novel aspects of the proposed HEMT structure, temperature-dependent behaviors including a high-voltage (40 V) and a low-leakage current (17 nA/mm) are further improved by eliminating mesa-sidewall effect. We obtained nearly current-independent transconductance in the temperature of 300-450 K. The measured current gain cutoff frequency f_T and maximum oscillation frequency f _max for a 1-μm gate device are 12 and 28.4 GHz, respectively     

Spectral anomalies of diffracted Hermite-Gaussian beams in the neighborhood of focus

The spectral behavior of spatially coherent polychromatic Hermite-Gaussian (H-G) beams focused by an aperture lens is studied by using the propagation law of the cross-spectral density function. An analytical expression for the spectrum of focused H-G beams is derived, which is related to the original spectrum and spectral modifier, and the spectral modifier is dependent on the truncation parameter, Fresnel number, and position parameter. Detailed numerical results are given to illustrate the spectral anomalies of diffracted H-G beams in the neighborhood of focus.     

铜及铜合金表面改性研究的可行性

钢铁渗硫提高了钢铁零部体的自润滑性能，从而提高耐磨件寿命。从这一观点出发，分析铜及铜合金渗硫的可能性，改善铜及铜合金零件的耐磨性，延长部件寿命，把辉光放电渗硫这一新技术引用到铜及铜合金表面改性的研究。     

预裂爆破技术的发展

介绍了预裂爆破技术在美国、加拿大等国家工程爆破中的应用与发展以及我国在这方面的进展。