一种新的数据加密技术

讨论了数据加密的一般方法和基本概念,介绍了一种新的数据加密方法,这种方法在计算开销和加密强度等方面,优于传统的加密体制。     

一种便携式水下语音通信设备加密方法

为了提升水下便携式语音通信设备的信息保密性,提出一种模拟语音信息时间要素加密和频谱要素加密的双重加密方法,并通过MATLAB仿真验证了该加密方法的可行性.此外,介绍采用该加密方法的便携式水下加密语音通信机的设备组成及其在不同保密要求场合的使用方法,为便携式水下加密语音通信机的工程应用奠定理论基础.     

球面波照明下傅里叶变换全息多图像加密方法研究

为了减少加密系统所用模板数,简化隐藏图像对解密过程的影响,采用球面波照明研究了基于傅里叶变换全息的多图像加密隐藏方法,并进行了加密、加密图像隐藏和解密的理论分析和数值模拟,加密图像和原始图像间的相关系数趋于0,宿主图像和加密图像的叠加系数0.3时,宿主图像和隐藏图像的相关系数趋于1,解密图像和原始图像间的相关系数趋于1。结果表明,该加密隐藏方法的加密、解密和隐藏效果良好。     

基于联合变换相关器和矢量分解的图像加密方法

为了提高基于联合变换相关器(JTC)的加密方法的 抗攻击能力,提出了一种基于 JTC和矢量分解的图像加密方法。在加密过程中,通过计算机预处理, 先将待加密图像进行了基于干涉原理的矢量分解,再利用基于JTC的 光学加密系统进行图像加密并记录加密图像。解密时,通过其中一个密钥解密联 合功率谱得到一幅纯相位图,再与另一个与明文相关的密钥进行相干叠加得到相 应解密结果。本文加密系统易于实现,通过矢量分解增加了一个与明文相关的密钥, 破坏了加密图像和原始图像间的线性关系,有效地提高了系统安全性。仿真实验 结果和分析验证了本文加密方法的可行性和安全性。     

一种新的混沌加密系统方案原理

文中讨论了混沌的不可预测性,论证了不可预测的混沌信号的产生方法,并对混沌加密和常规加密系统进行了对比.在此基础上,提出了一个混沌与常规加密级联的系统方案.本文的主要工作在于阐述新方案的原理,提出了发挥混沌系统的不可预测性在混沌加密中的作用和将混沌加密与常规加密方法结合起来的思想.分析表明,这是提高加密系统安全性的一个新的重要研究课题.     

关系数据库中字符数据的保序加密方法

对数值型数据保持顺序加密方法进行了分析,在此基础上提出了一种在关系数据库中针对字符数据的保序加密方法。详细阐述了其加密原理和密文索引结构,对重复性数据的加密处理和算法抗攻击性进行了分析。最后分别从时间开销、空间开销两个方面对算法进行了实验验证,实验结果表明该方法既保证了数据库安全性,又解决了加密数据库的查询性能问题。     

基于MP3编码过程的音频加密研究

提出了一种使用Lorenz混沌系统,Logistic混沌系统和MP3编码过程相结合的音频加密方法。首先由Lorenz混沌系统与Logistic混沌系统产生一张混沌表,根据混沌表生成的混沌序列作为加密序列。加密序列将MP3数据帧中的比例因子和霍夫曼码加密,这种加密方法不仅保证了安全性,同时也提高了加密的效率。     

利用数字全息和相位恢复算法实现信息加密

提出了一种基于数字全息技术和相位恢复算法的信息加密方法。运用相位恢复算法得到数字全息图的纯相位频谱分布,实现了对全息图的加密;对纯相位频谱分布实施逆傅里叶变换(IFT)则可以得到解密后的全息图。利用菲涅耳近似法和卷积法对解密后的全息图进行数字重构得到了再现像。该加密方法区别于常用的随机相位加密方法,不再需要制作随机相位板。实验结果表明,该加密方法既适用于对二维图像加密,也适用于对三维物体进行加密。     

基于RSA算法和超混沌的复合加密方案

结合RSA公钥算法和超混沌加密信号两者的优缺点,提出了一种基于RSA算法和超混沌的复合加密方案.理论分析和仿真结果表明,RSA算法抵抗选择密文攻击、公共模数攻击和低指数攻击的能力得到了提高,同时也不存在混沌加密方法在密钥空间设计上的问题.该方案充分利用了两种加密方法的优点,而克服了各自的缺点,因此其安全性能明显优于单独使用任一加密方法的安全性能.     

VFP字段加／解密算法的实践

按字段级和文件级对VFP数据加密/解密方法进行了分类,详细分析了这两种方法的优缺点,指出了用传统的二进制I/O方式对数据库文件加密/解密较难适应Windows环境的原因,进而从密码学的角度叙述了多随机数加密技术的加密/解密的原理,阐述了多随机数加密/解密算法技术的特点及实现方法,并给出数据库字段加密/解密算法的实现函数.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.