An efficient and robust numerical algorithm for estimating parameters in Turing systems

We present a new algorithm for estimating parameters in reaction–diffusion systems that display pattern formation via the mechanism of diffusion-driven instability. A Modified Discrete Optimal Control Algorithm (MDOCA) is illustrated with the Schnakenberg and Gierer–Meinhardt reaction–diffusion systems using PDE constrained optimization techniques. The MDOCA algorithm is a modification of a standard variable step gradient algorithm that yields a huge saving in computational cost. The results of numerical experiments demonstrate that the algorithm accurately estimated key parameters associated with stationary target functions generated from the models themselves. Furthermore, the robustness of the algorithm was verified by performing experiments with target functions perturbed with various levels of additive noise. The MDOCA algorithm could have important applications in the mathematical modeling of realistic Turing systems when experimental data are available.     

Multicomponent transport algorithms for partially ionized mixtures

We investigate iterative methods for solving linear systems arising from the kinetic theory of gases and providing multicomponent transport coefficients of partially ionized plasmas. We consider the situations of weak and strong magnetic fields as well as electron temperature nonequilibrium and the linear systems are investigated in their natural constrained singular symmetric form. Stationary iterative techniques are considered with new more singular formulations of the transport linear systems as well as orthogonal residuals algorithms. The new formulations are derived by considering generalized inverses with nullspaces of increasing dimension. Numerical tests are performed with high temperature air and iterative techniques lead to fast and accurate evaluation of the transport coefficients for all ionization levels and magnetic field intensities.     

Chaos based multiple image encryption using multiple canonical transforms

We propose a new method for multiple image encryption using linear canonical transforms and chaotic maps. Three linear canonical transforms and three chaotic maps are used in the proposed technique. The three linear canonical transforms that have been used are the fractional Fourier transform, the extended fractional Fourier transform and the Fresnel transform. The three chaotic maps that have been used are the tent map, the Kaplan-Yorke map and the Ikeda map. These chaotic maps are used to generate the random phase masks and these random phase masks are known as chaotic random phase masks. The mean square error and the signal to noise ratio have been calculated. Robustness of the proposed technique to blind decryption has been evaluated. Optical implementation of the technique has been proposed. Experimental and simulations results are presented to verify the validity of the proposed technique.     

Optical image encryption based on two beams’ interference

We proposed a method for optical image encryption on the basis of interference theory. An optical image can be produced by the interference of two beams passed two different masks. One of the masks can only modulate the phase of the beam and another can only modulate the amplitude of the beam. The encryption method is quite simple and does not need iterative algorithm. The results of simulation coincide with our method and demonstrate the feasibility of this method.     

Image sharing scheme based on discrete fractional random transform

We present a novel image sharing algorithm based on the discrete fractional random transform (DFRNT). The secret image is shared into several shadow images in the DFRNT domain together with some noise images as the encryption keys to increase the security. The decryption only requires a part of shadow images and therefore is independent of those noise images. The (t,n) threshold sharing scheme can be implemented completely by the proposed algorithm. The numerical simulations have demonstrated the effectiveness of this image sharing scheme.     

Image encryption based on double random amplitude coding in random Hartley transform domain

We propose an image encryption scheme based on double random amplitude coding technique by using random Hartley transform, which is defined according to the random Fourier transform. The significant feature of this algorithm is that the encrypted image is real and convenient for storage as well as transfer of the encrypted information. Moreover, the algorithm has enhanced security and the correct information of original image can be well protected under bare decryption, blind decryption and brute force attacks. Numerical simulation results are also presented in support of the proposed scheme.     

导弹防御系统的X波段雷达能力分析

导弹防御系统中的X波段雷达主要对来袭导弹飞行中段的目标进行探测、跟踪和识别,对GBI拦截弹提供中制导信息等。根据X波段雷达的性能参数,分析了其实际的探测识别能力,这对我国导弹突防研究具有重要的参考价值。     

基于粒子群算法的车间作业调度问题

通过对车间调度问题的描述,针对传统算法寻优效率低的弱点,提出了一种基于粒子群算法的车间作业调度问题的解决方案.对粒子群算法的基本原理进行了阐述,并对粒子群算法的编码、参数的选择以及解码进行了研究,以最小化最大流程时间作为评价算法的性能指标,将其用于编程求解典型调度问题.仿真结果表明,粒子群算法在求解车间作业调度的应用上是十分有效的.     

基于AVR单片机的高温高压消毒柜控制系统

介绍了一款基于AVR单片机为核心的高温高压消毒柜控制电路,该系统采用ATMEGA16L单片机为核心控制一些外围元件,把需要测量的模拟信号转换为数字信号后,再通过软件进行处理,并输出控制信号给外围电路来控制加热泵及真空泵等的工作,从而产生高温高压实现消毒的功能.     

内网安全数据保密技术分析与比较

内网安全经过多年发展已日渐丰富,包括了身份认证、授权管理、数据保密和监控审计4大领域,论文通过对目前主要的内网安全数据保密关键技术讨论和分析,给出了不同内网安全数据保密技术的优缺点,并对其应用领域进行了讨论。