粒子群可拓的新冠肺炎建模与仿真

本文提出了一种基于粒子群可拓神经网络预测模型.根据国外近段时间每日新增新冠肺炎确诊人数,利用可拓神经网络模型对国外日新增新冠肺炎确诊人数进行预测,并利用粒子群算法(PSO)对权值进行优化,最后与LSSVM、ABC-LSSVM及PSO-LSSVM模型进行比较.结果表明:采用文中提出的粒子群可拓神经网络模型拟合效果较好,精...     

后量子密码算法的侧信道攻击与防御综述

为了解决量子计算对公钥密码安全的威胁,后量子密码成为密码领域的前沿焦点研究问题.后量子密码通过数学理论保证了算法的安全性,但在具体实现和应用中易受侧信道攻击,这严重威胁到后量子密码的安全性.基于美国NIST第2轮候选算法和中国CACR公钥密码竞赛第2轮的候选算法,针对基于格、基于编码、基于哈希、基于多变量等多种后量子密...     

基于溶液图像时序特征的元素组分含量动态监测系统

针对稀土萃取过程中组分含量难以实时监测以及现有组分含量检测方法耗时、耗内存的现状,设计了一种基于溶液图像时序特征的元素组分含量动态监测系统。首先使用图像采集装置获取萃取槽体溶液的时序图像,考虑萃取液颜色特性和单一颜色空间的不全面性,采用主成分分析（PCA）方法在HSI和YUV融合的颜色空间提取图像的时序特征,并结合生产指标构造基于鲸鱼优化算法（WOA）的最小二乘支持向量机（LSSVM）分类器来对工况状态进行判断。然后当工况处于非最佳状态时,在HSV颜色空间对图像提取颜色直方图和颜色矩特征,并开发以溶液图像间的混合特征差值的线性加权值为相似度度量的图像检索系统,从而获取组分含量值。最后进行镨/钕萃取槽体混合溶液测试,结果表明该系统能够实现元素组分含量的动态监测。     

基于PCA与权重贝叶斯的工作面煤与瓦斯突出预测

为实现对工作面煤与瓦斯突出快速、准确和动态的预测,提出一种基于主成分分析和权重贝叶斯的工作面煤与瓦斯突出预测方法,通过建立工作面煤与瓦斯突出预测的权重贝叶斯模型进行突出危险性等级预测.利用主成分分析确定预测模型中分类变量权重以提高预测准确性.在此基础上,设计基于相似度的训练样本数据更新方式实现对突出预测模型的有效重构....     

基于等几何分析的柔性多体系统建模方法研究

近三十年来,柔性多体系统动力学取得长足进步,尤其是以绝对节点坐标方法(Absolute Nodal Coordinate Formulation, ANCF)为代表的非线性有限元已被用来处理复杂的柔性多体系统动力学问题.但绝对节点坐标方法采用斜率矢量作为广义坐标,导致系统自由度多,计算效率低.针对柔性多体系统,基于非均匀有理B样条(Non-Uniform Rational B-Splines, NURBS)曲线和曲面分别提出了Euler-Bernoulli细长梁单元和Kirchhoff-Love薄壳单元,在完全拉格朗日格式下,根据Green应变张量对单元变形进行描述,结合第二类Piola-Kirchhoff应力张量给出单元应变能公式,推导了单元的弹性力和弹性力雅可比矩阵表达式,最后通过静力学及动力学数值算例对提出的两类单元的性能进行对比和验证,为柔性多体系统建模提供了一种精确高效的新单元.     

基于精化的TrustZone多安全分区建模与形式化验证

TrustZone作为ARM处理器上的可信执行环境技术,为设备上安全敏感的程序和数据提供一个隔离的独立执行环境.然而,可信操作系统与所有可信应用运行在同一个可信环境中,任意组件上的漏洞被利用都会波及系统中的其他组件.虽然ARM提出了S-EL2虚拟化技术,支持在安全世界建立多个隔离分区来缓解这个问题,但实际分区管理器中仍可能存在分区间信息泄漏等安全威胁.当前的分区管理器设计及实现缺乏严格的数学证明来保证隔离分区的安全性.详细研究了ARM TrustZone多隔离分区架构,提出一种基于精化的TrustZone多安全分区建模与安全性分析方法,并基于定理证明器Isabelle/HOL完成了分区管理器的建模和形式化验证.首先,基于逐层精化的方法构建了多安全分区模型RMTEE,使用抽象状态机描述系统运行过程和安全策略要求,建立多安全分区的抽象模型并实例化实现分区管理器的具体模型,遵循FF-A规范在具体模型中实现了事件规约;其次,针对现有分区管理器设计无法满足信息流安全性验证的不足,设计了基于DAC的分区间通信访问控制,并将其应用到TrustZone安全分区管理器的建模与验证中;再次,证明了具体模型...     

Hierarchical Reliable Multicast: Performance Analysis and Optimal Placement of Proxies

This paper studies the use of multicast together with proxy nodes for reliably disseminating data from a single source to a large number of receivers. In order to achieve reliability, data must be retransmitted in case of loss either by the source or by special network nodes, called proxies. Each proxy is responsible for reliably delivering the data to a subgroup it is assigned. The multicast tree is partitioned into subgroups that form a hierarchy rooted at the source, hence the term hierarchical reliable multicast. The performance of this approach strongly depends on the topology and the loss characteristics of the underlying tree and the location of proxies. In the first part of the paper, we study the processing and bandwidth performance of such a reliable multicast dissemination given the tree and the placement of proxies. In the second part of the paper, we develop dynamic programming algorithms that give a placement of a fixed number of proxies on an arbitrary tree that minimizes the bandwidth used for reliable transfer. The first algorithm provides an optimal solution to the multicast proxies location problem in polynomial time, in the number of nodes and proxies. The second is an approximation algorithm that gives a solution with cost within a chosen precision from the optimal, in an improved running time. An optimal and an approximate solution are also provided for the proxies location problem if unicast is used for transmissions. Applications of this dynamic programming approach to related problems are discussed.     

文本结构分析与基于示例的文本过滤

本文简要介绍了文本过滤的背景和发展,提出了基于示例的中文文本过滤模型．其基本思想是首先对于用户提出的示例文本进行文本结构分析,采用本文提出的文本层次分析方法,提取文本特征,形成主题词表示的用户模版（ｕｓｅｒ ｐｒｏｆｉｌｅ）,然后进行了文本过滤,同时引进段落匹配机制,提高过滤效率．通过用户反馈,改进用户模版．     

基于QoE的路测软件数据存储与分析模块设计与实现

传统的基于KPI评估体系的路测软件不能满足无线网络优化中用户感知（QoE）的要求,本文以QoE为导向,采用内存-磁盘映射存储机制设计出了一种适合路测软件的数据存储结构,提出了一种后台数据分析模块的设计方案,使用分析管理器为用户提供定制自定义分析项目的接口,使用表达式编辑器为用户提供定制自定义参数、事件和指标的接口。实际测试结果表明,数据库系统的设计很好的满足路测软件对数据存取的要求,后台分析模块的设计使得后台数据分析更加灵活高效,符合QoE评估体系的要求。     

Automatic eye fixations identification based on analysis of variance and covariance

Eye movement is the simplest and repetitive movement that enables humans to interact with the environment. The common daily activities, such as reading a book or watching television, involve this natural activity, which consists of rapidly shifting our gaze from one region to another. In clinical application, the identification of the main components of eye movement during visual exploration, such as fixations and saccades, is the objective of the analysis of eye movements: however, in patients affected by motor control disorder the identification of fixation is not banal. This work presents a new fixation identification algorithm based on the analysis of variance and covariance: the main idea was to use bivariate statistical analysis to compare variance over x and y to identify fixation. We describe the new algorithm, and we compare it with the common fixations algorithm based on dispersion. To demonstrate the performance of our approach, we tested the algorithm in a group of healthy subjects and patients affected by motor control disorder.