网络视频监控

随着数字化信息的飞速发展和网络技术的日益成熟,网络视频监控系统由于其自身相对于传统闭路电视监控的明显优势,必将成为安防领域的主流。本文分析了网络视频监控系统的几种构架和各自的优缺点,并详细阐述了其中的一种及其所采用的数字视频服务器的工作原理。     

基于IBE和数字水印的电子印章解决方案

为了满足电子交易中电子文档的可用性、安全性、权威性,提出了一种基于IBE(Identity Based Encryp-tion)技术和数字水印技术的电子印章解决方案。该方案使用IBE技术分配成对的密钥完成水印的嵌入和提取验证。在保证与基于PKI(Public Key Infrastructure)技术的印章系统具有等同安全强度的同时,具有降低成本、提高效率的优点。     

一种基于MPEG-2 AAC编码的音频水印方法

提出了一种针对MPEG-2 AAC压缩音频的脆弱水印算法.该算法利用了AAC中MDCT量化系数大于15的Huffman编码特性来嵌入水印,并依据水印的频率分布和音频信号感知熵PE的大小对嵌入算法进行了分析和改进.实验表明,该算法具有较高隐藏率和良好的不可感知性,并且水印的嵌入和提取过程十分方便快速,适合进行实时分析.     

基于数字微镜技术的阿达玛变换近红外光谱仪

构建了一个基于数字微镜技术的新型阿达玛变换近红外光谱仪.光学信号采用光纤引入,以光栅作为分光元件,利用数字微镜代替传统的机械式阿达玛模板进行光学编码调制,使用单点InGaAs红外探测器检测调制后的光信号,通过快速阿达玛解码还原出原始光谱.通过实验检验了光谱仪的分辨率、信噪比、稳定性以及谱图获取速度等指标.实验结果表明,...     

闭环光纤陀螺全数字式信号检测方法研究

研制成功基于阶梯波调制技术的闭环光纤陀螺全数字式信号检测系统.提出了闭环光纤陀螺几个重要参数的测试方法,并给出了实验结果.     

声光可调谐滤波器成像光谱仪实时预处理系统

为了快速实时地预处理声光可调谐滤波器（AOTF）成像光谱仪的数据,分析了AOTF成像光谱仪数据特点及预处理算法,采用数字信号处理器（DSP）作为核心器件代替传统的PC机处理平台,提出了一种基于两片ADSP-TS201的外部总线共享与链路口混合耦合的双DSP并行处理系统方案。结合实际需求,设计了流水线处理方式并合理分配预处理任务。用实验方法对系统的功能进行了验证,结果表明：双DSP并行处理系统完成一帧AOTF成像光谱仪数据的预处理仅需23.5 ms,比原有PC机处理速度提高了13倍左右,满足了实时性要求,促进了AOTF成像光谱仪系统化、模块化、小型化并兼具实时处理能力的发展。     

Tailoring light with a digital micromirror device

A digital micromirror device (DMD) is a product of micromechanics. The DMD employs numerous micromirrors as the actuating components to switch small portions of light on and off. During the past few decades, such devices have been widely applied in digital light processing technology. The expanding range of applications makes the DMD increasingly important in various research aspects. Recent advances demonstrate that the DMD is potentially better than the traditional liquid crystal spatial light modulator in speed, spectrum sensitivity, and polarization modulation. These characteristics have been verified in a series of recently reported experiments. This review summarizes the related theory, experimental techniques, and applications for wavefront shaping with DMDs in both statically shaping various spatial modes and dynamically compensating for wavefront distortion caused by the scattering medium.

     

基于中英文字符型属性的数据库水印算法

提出了一种基于中英文字符型属性的数据库数字水印算法。通过元组哈希值和字符属性值长度计算出预测嵌入位置,根据预测嵌入位置所在的字节序号确定水印嵌入位置。以ASCII字符集的不可见字符作为水印信号,将版权图像嵌入宿主数据库。嵌入的水印信号具有不可见性,并且保持数据库的原始可用性,可实现水印的盲提取。该算法对添加元组、删除元组、修改属性值、添加与删除属性以及元组与属性重排等常见数据库攻击具有较强的鲁棒性。     

An approach for sensing marine plankton using digital holographic imaging

The goal of this paper is to use digital holographic imaging for sensing marine plankton in recording sampling volume. The process stage of this approach includes: wavefront recording using in-line holographic recording set up and numerical reconstruction using Fresnel approximation and convolution algorithm. So, by capturing hologram of marine plankton and reconstructing hologram, the recorded optical field of marine plankton is retrieved. Digital holographic imaging is an extremely powerful technique for the study of marine plankton fields as it allows instantaneous, noninvasive, high-resolution recording of substantial volumes. Finally, this paper presents that it is possible for digital holographic imaging system to sense marine plankton according to laboratory results.