基于模拟退火—遗传算法的非线性密钥序列生成器线性复杂度研究

计算线性等价是研究非线性密钥序列生成器线性复杂度的有效方法。本文先介绍了计算线性等价的模拟退火法,然后使用遗传算法对该算法进行改进,最后使用一组密钥序列生成器对改进后的算法进行性能评估,并将改进后的算法和原算法进行了比较。结果表明改进后的算法能比原算法更有效的找到非线性密钥序列生成器的线性等价。     

一体化小桥式称重传感器的设计

电子称量系统在各个称量领域的应用极为广泛,而桥式称重传感器是电子称量系统的核心元器件。一体化小桥式称重传感器是将底座与弹性体合为一体来大大缩小传感器的几何形体,并将传感器的自重大幅度降低的一种设计方法。这样更便于电子称量系统的安装和维护,缩短电子称量系统的安装和维护周期。     

A grid-based clustering algorithm for wild bird distribution

Advanced satellite tracking technologies provide biologists with long-term location sequence data to understand movement of wild birds then to find explicit correlation between dynamics of migratory birds and the spread of avian influenza. In this paper, we propose a hierarchical clustering algorithm based on a recursive grid partition and kernel density estimation (KDE) to hierarchically identify wild bird habitats with different densities. We hierarchically cluster the GPS data by taking into account the following observations: 1) the habitat variation on a variety of geospatial scales; 2) the spatial variation of the activity patterns of birds in different stages of the migration cycle. In addition, we measure the site fidelity of wild birds based on clustering. To assess effectiveness, we have evaluated our system using a large-scale GPS dataset collected from 59 birds over three years. As a result, our approach can identify the hierarchical habitats and distribution of wild birds more efficiently than several commonly used algorithms such as DBSCAN and DENCLUE.     

Caustic imaging of gallium droplets using mirror electron microscopy

We discuss a new interpretation of mirror electron microscopy (MEM) images, whereby electric field distortions caused by surface topography and/or potential variations are sufficiently large to create caustics in the image contrast. Using a ray-based trajectory method, we consider how a family of rays overlaps to create caustics in the vicinity of the imaging plane of the magnetic objective lens. Such image caustics contain useful information on the surface topography and/or potential, and can be directly related to surface features. Specifically we show how a through-focus series of MEM images can be used to extract the contact angle of a Ga droplet on a GaAs (001) surface.     

基于混合模式的科研信息系统设计与研究

计算机技术的迅猛发展,先进信息化管理理念在管理科研领域中发挥愈来愈大的作用。高等院校的科研管理部门,统筹安排全校科研项目的组织与申报、下达计划、鉴定成果、奖项申报、论文统计、科技资料统计以及社会服务、推广合作等方面的工作,涉及面很广,事务性工作很多。当前的科研管理工作也只有利用科研信息化建设,才能更好的适应海量信息和繁杂的日常工作,才能对科研管理中的各种要素进行合理配置、优化,以保证管理工作的及时性、高效性。目前各高校也都在不断提高信息化管理水平,如何更好的开发和使用高性能的科研管理信息系统势在必行。     

利用Eucalyptus和开源操作系统构建和实现私有云

使用私有云可以带来很大的便利和大大提高资源的使用率以及降低维护费用,如何快捷、低成本构建私有云成为最关键的问题,有许多针对构建私有云思路和设计,有的过于复杂、有的过于投入昂贵、有的维护繁琐.本文论述使用开源操作系统Ubuntu（服务器版）构建和实现一个Eucalyptus结构私有云,并通过该云提供IaaS服务.以这种构建方式能够快速实现私有云,具有成本低廉、维护简单、管理方便的特点.     

High‐order sliding mode control design based on adaptive terminal sliding mode

High‐order sliding mode control techniques are proposed for uncertain nonlinear SISO systems with bounded uncertainties based on two different terminal sliding mode approaches. The tracking error of the output converges to zero in finite time by designing a terminal sliding mode controller. In addition, the adaptive control method is employed to identify bounded uncertainties for eliminating the requirement of boundaries needed in the conventional design. The controllers are derived using Lyapunov theory, so the stability of the closed‐loop system is guaranteed. In the first technique, the developed procedure removes the reaching phase of sliding mode and realizes global robustness. The proposed algorithms ensure establishment of high‐order sliding mode. An illustrative example of a car control demonstrates effectiveness of the presented designs. Copyright © 2011 John Wiley & Sons, Ltd.     

堰塞坝局部溃决输沙率试验研究

本文设计9组堰塞坝溃决的水槽试验,用摄影记录坝体变形的过程,通过录影数据分析,将坝体变形过程数值化,研究坝体级配、坝体内坡和初始溃口宽度对最大输沙率的影响.根据观察到的现象,可以总结以下规律:内坡坡度越大,最大输沙率越大,峰现时刻越早出现;拣选系数越大,最大输沙率先增大,随着粗沙继续增加,反而减小;初始溃口宽度越小,最大输沙率越大,峰现时刻越晚出现.     

山洪灾害特点分析及风险图制作方法探讨

针对我国山洪灾害人员伤亡大,防洪工程建设不经济、移民困难的现实,提出应将非工程措施.特别是绘制洪水风险图,作为目前山洪灾害管理的一项重要措施.在阐明国内外洪水风险图含义的基础上,分析了山区小流域洪水风险图制作中面临的资料缺乏和精度不高的问题,并提出了针对性的编制方法,即选取时段降雨量作为山区小流域洪水风险图绘制方案划分的依据,选择与选定降雨量接近的典型历史洪水作为该方案洪水风险图编制的实例,通过调查过往洪水淹没点情况,并利用GIS技术的空间分析功能进行洪水淹没分析.最后选取江西省黎川县厚村站为例,绘制了厚村站24 h降雨320 mm时的厚村乡洪水风险图.