基于Logistic混沌系统的图像加密算法研究

给出了一种基于Logistic混沌系统的快速数字图像加密算法.首先通过给定的密钥序列生成混沌系统的初值,由此初值生成混沌矩阵;然后利用此混沌矩阵与原图像进行按位异或运算得到中间过渡图像;最后再对中间过渡图像作混沌置乱运算和混沌块置乱操作.该算法的优点是不论融合还是置乱均是利用混沌序列进行操作.实验数据表明,该算法简单易行,加密与恢复效果良好,具有较好的安全性.     

阳宗海浮游生物群落结构研究

采用生物多样性指数方法,对2013年阳宗海湖泊的浮游生物群落结构进行研究。结果表明,阳宗海湖泊共检出浮游植物7门39属,蓝藻门的拟鱼腥藻和泽丝藻为优势种群;浮游动物鉴定出33种,轮虫为优势种;浮游植物和浮游动物的香浓多样性指数在1.10~2.83之间,均匀度指数在0.37~0.88之间,属于中度污染,阳宗海湖泊已处于中营养状态,并有向富营养化过渡的趋势。     

An elastic net-based hybrid hypothesis method for compressed video sensing

Multimedia Tools and Applications - Compressed Sensing, an emerging framework for signal processing, can be used in image and video application, especially when available resources at the...     

A study of optimal viewing distance in a parallax barrier 3D display

The optimal viewing distance was proposed as a parameter for designing a parallax barrier 3D display. It can be designed based on simple geometric method and by considering the pitches of image display pixels and parallax barrier, or even including the aperture ratios of the image display pixels and parallax barrier. It can be analyzed by using ray tracing method. By considering the optical refraction index of the cover glass, the angular behavior of the system becomes more realistic; however, the geometric method is difficult to be used. We propose a revised method for estimating the view distance and angular behavior. In this paper, we have demonstrated a designated eye position (DEP) for each view and shown that multiple DEPs make a circular curve around the center of the display. We prove the new concept by comparing the optical ray tracing calculations and optical measurement.     

A nonsmooth IMC method for mechanical systems with backlash

This paper proposes a discrete-time nonsmooth internal model control （NSIMC） approach for mechanical transmission systems described by so-called sandwich system with backlash. In this method, a dynamic compensator is introduced to compensate for the effect of the input linear subsystem. Thus, the sandwich systems with backlash can be simplified as a pseudo-Hammerstein system with backlash. The corresponding NSIMC strategy is designed to control this system. The design procedure of the controller is presented based on the analysis on the robust stability by considering the model errors involved with the effect of backlash as well as the compensated error of the input linear subsystem. Moreover, as the model is switched among the different operating zones, the robust filters are proposed to guarantee the robust stability and satisfactory control performance of the system.     

Nonsmooth identification of mechanical systems with backlash-like hysteresis

Backlash-like hysteresis is one of the nonsmooth and multi-valued nonlinearities usually existing in mechanical systems. The traditional identification method is quite difficult to be used to model the systems involved with such complex nonlinearities. In this paper, a nonsmooth recursive identification algorithm for the systems with backlash-like hysteresis is proposed. In this method, the concept of Clarke subgradient is introduced to approximate the gradients at nonsmooth points and the so-called bundle method is used to obtain the optimization search direction in nonsmooth cases. Then, a recursive algorithm based on the idea of bundle method is developed for parameter estimation. After that, the convergence analysis of the algorithm is investigated. Finally, simulation results to validate the proposed method on a simulated mechanical transmission system are presented.     

Multiconsensus of second order multiagent systems with directed topologies

A novel multiconsensus problem is introduced in multiagent systems. The states of multiple agents in each subnetwork asymptotically converge to a consistent value with information exchanges among subnetworks. The multiconsensus problem of second order multiagent systems with directed topologies is studied. Three linear protocols are proposed to solve the multiconsensus problem. Necessary and sufficient conditions are derived based on matrix theory. Simulations are provided to demonstrate the effectiveness of the theoretical results.     

水调自动化系统信息检索功能的设计与实现

从软件系统设计、信息检索设计、图形界面设计等多个角度说明了信息检索的设计方法,分析了信息检索在水调自动化系统中的应用,以业务应用为目标,协调了软件开发与图形界面的交互设计,阐述了其在水调自动化系统中应用功能的实现方式。     

单螺杆大振幅振动对挤出影响的数值模拟研究

借助CFD专用模拟软件PolyFlow,本文模拟了动态塑化单螺杆挤出机计量段中,聚合物熔体在单螺杆大振幅振动条件下的三维非等温输送流场,研究了大振幅振动力场对挤出产量、功率及螺杆特性的影响。模拟结果显示:振动参数有一个可选范围,当螺杆振动幅值超过该范围而落入横流反向区时,挤出流率将急剧下降,产能比严重降低,螺杆特性变软。