Involution Narrowing Algebra

The narrowing algebra formalism underlying CLP(intervals) consists of lattice-ordered monoids of monotone contractions on the lattice of states; these are generated by the canonical idempotent operators of the primitive relations of the constraint system used for the problem. This mathematical structure has some similarities with that of some classical operator rings, even though the underlying states form a non-Boolean lattice instead of a linear space. In this paper we show that in the restricted case of certain binary interval convex primitives, there is a broken symmetry which can be restored by generalizing the state lattice to produce an involution on the important fragment of the narrowing algebra. This involution allows some basic theorems of classical *-rings to be ported into this domain.     

Type-level Computation Using Narrowing in Ωmega

Ωmega is an experimental system that combines features of both a programming language and a logical reasoning system. Ωmega is a language with an infinite hierarchy of computational levels. Terms at one level are classified (or typed) by terms at the next higher level. In this paper we report on using two different computational mechanisms. At the value level, computation is performed by reduction, and is largely unconstrained. At all higher levels, computation is performed by narrowing.     

移动闭塞条件下基于双曲列控策略的发车间隔时间计算

列车间隔时间关乎铁路行车安全和效率。对未来铁路移动闭塞系统发车间隔时间的科学计算进行探讨,引入了能够反映经验丰富司机驾车列车优化行为的基于双曲函数的列车行为控制模型;然后,讨论了列车分段运动方程和车站发车作业、进路解锁等环节,以及各种误差因素,并将它们与基于双曲函数的列车行为控制模型有机结合起来,建立了计算移动闭塞条件下车站发车间隔时间的数学模型,给出了两种不同情形的车站发车间隔时间计算方法,数值仿真试验验证了算法的有效性和可行性。对移动闭塞条件下车站发车环节的列车行为控制和行车组织有较大参考价值。     

A Steganography Based on Optimal Multi-Threshold Block Labeling

Hiding secret data in digital images is one of the major research fields in information security. Recently, reversible data hiding in encrypted images has attracted extensive attention due to the emergence of cloud services. This paper proposes a novel reversible data hiding method in encrypted images based on an optimal multi-threshold block labeling technique (OMTBL-RDHEI). In our scheme, the content owner encrypts the cover image with block permutation, pixel permutation, and stream cipher, which preserve the in-block correlation of pixel values. After uploading to the cloud service, the data hider applies the prediction error rearrangement (PER), the optimal threshold selection (OTS), and the multi-threshold labeling (MTL) methods to obtain a compressed version of the encrypted image and embed secret data into the vacated room. The receiver can extract the secret, restore the cover image, or do both according to his/her granted authority. The proposed MTL labels blocks of the encrypted image with a list of threshold values which is optimized with OTS based on the features of the current image. Experimental results show that labeling image blocks with the optimized threshold list can efficiently enlarge the amount of vacated room and thus improve the embedding capacity of an encrypted cover image. Security level of the proposed scheme is analyzed and the embedding capacity is compared with state-of-the-art schemes. Both are concluded with satisfactory performance.     

分组密码统一描述模型研究

介绍分组密码统一描述模型建立的背景和现实可行性,通过对现有大量分组密码算法结构的研究,对算法各个部分的功能进行归纳,提取分组密码算法的多个通用组件,给出从2种不同角度建立的分组密码统一描述模型——模型的组件关系形式和分组密码流程形式,并对各个通用组件进行了定义和功能说明,应用该模型描述Camellia算法。     

一种基于最优模块匹配的新型加权中值滤波算法

为了去除图像中的噪声,提出了一种新型的加权滤波算法,算法思想是基于大范围的最优模块匹配,根据模块之间的相似度来衡量像素点之间的相关性,从而确定对中心点像素贡献的大小,赋予像素点不同大小的权值,来恢复被噪声点污染的信号点,达到去除噪声、保护图像边缘信息的目的。实验表明新算法在滤波性能方面优于现有的一些改进算法,即使在高密度噪声下,也能取得较好的滤波效果。     

约束逻辑程序设计的变量压缩事件分析

该文涉及的约束逻辑程序设计(CLP)是一在二叉树上进行搜索的过程,提高搜索效率是CLP的主要研究方向之一。在CLP中约束推理机是核心,由变量组、约束过滤器、临时容器、推理引擎组成。在介绍了约束推理机激活过滤器,对变量进行区间压缩后,提出引入变量事件,总结为三种类型:SINGLE、BOUND和DOMCHG,用于减少过滤器的激发次数。实验结果表明,变量事件能够促进约束推理机的搜索效率,缩短二叉树搜索的时间,可以更快寻找到答案。     

成组更换策略下的备件库存决策仿真研究

针对成组更换策略下备件需求的特点,建立了无限使用期的成组更换策略与备件库存控制联合优化仿真模型。该模型通过模拟系统在预防维修间隔期T内的维修活动,得到1个预防维修间隔期内的总费用,然后在系统运行M(M足够大)个周期下,以期望单位时间总费用最小为目标,优化预防维修间隔期T和最大库存水平S。最后,基于案例,运用MATLAB对模型进行仿真优化计算,并分析了相关参数对模型优化结果的影响。     

利用动态块与属性块技术制作图幅

块是AutoCAD图形设计中的一个重要概念,随着AutoCAD软件功能的日渐增强,块功能也得到极大的增强,分别引入了动态块和属性块的概念。该文详细叙述了如何运用AutoCAD中的动态块功能来制作不同尺寸大小的图幅,以及利用属性块功能制作图幅中标题栏的过程,并且介绍了图幅块的使用方法。     

邻域匹配和分类匹配的分形块编码

值域块的分形编码，是值域块与定义域块池中的定义域块逐一匹配后产生的。这一匹配过程是影响分形块编码速度的深层原因，此文改全局匹配为邻域匹配和分类匹配，从二条途径探讨了缩短匹配时间的方法。实验结果表明，领域匹配及分类匹配的分形块编码的时间，但信噪比略有下降。     

改进蚁群算法求解两地间时间最优路径

为提高蚁群算法的运算效率,提出一种改进的蚁群算法来求解问题。研究中中引入阀值排序算法对搜索路径进行优化,解决了蚁群算法前期搜索路径的盲目性问题。改进的蚁群算法加快了收敛速度,并提高了稳定性。经仿真试验证明,改进蚁群算法性在减少算法的迭代次数和提高解的稳定性方面有了较大的提高,并且能很好的用于求解路径时间最优问题。     

区间算术在软件测试中的应用

程序结构测试可以分为4个阶段:静态分析、路径选择、测试数据生成和动态分析.本文应用区间算术在测试数据生成阶段对约束集求解.由于正则约束式的引入,能够处理复杂的逻辑表达式组,找到一组解以供第4阶段动态分析使用.文中提出的算法具有非常大的灵活性,可以处理非线性约束,经改进后,它甚至可以处理包含函数的表达式.     

收货时间窗软约束下绿色多式联运路径优化

绿色多式联运不仅能有效降低物流成本,提升物流效率,而且能减少环境污染,随着我国综合运输体系的建设与完善,对绿色多式联运的研究已成为热点问题。针对带收货时间窗的绿色多式联运路径选择问题,将收货时间窗作为软约束,运输时限与收货人满意度结合,同时考虑基于运输成本大小的承运人满意度,构建了满意度权重不确定的绿色多式联运路径选择模型。通过Matlab仿真求解,结果表明,模型对运输时限与收货时间窗的关系把控合理,兼顾了承运人和收货人双方的利益。针对不同的运输货物,通过调整双方满意度权重可以得出更加切合实际的最优运输路径,运输时间不拘泥于固定收货时间窗内,且在运输费用上具有明显的优越性。     

基于空时块编码的飞行器全向无线通信分析

将空时块编码引入飞行器全向无线传输中,用于抑制传统飞行器全向通信中不同天线发送信号在空间中发生干涉的问题.从等效合成天线增益和适合的应用场景两方面对基于空时块编码的传输方案的性能进行分析和讨论.针对不同的传输场景进行了仿真评估.仿真结果表明:使用空时块编码的方案性能与天线数量和天线方向图有关;相比传统方案,采用空时块编码能够有效抑制信号在空间中的深衰减,降低通信链路中断概率,从而大幅改善飞行器全向通信能力.     

Optimal Time Substitution in a Control Process

Control for the current state of a process by observation is investigated. The aim functional is defined by the ratio of integrals of integrands dependent on control functions. By this functional, control is interpreted as a time substitution control. Optimal control functions for certain classes of control functions and a method for computing them are determined. Relay control functions and related functions are shown to be optimal.__________Translated from Avtomatika i Telemekhanika, No. 8, 2005, pp. 64–83.Original Russian Text Copyright © 2005 by Kharlamov.This work was supported by the Program “Control for Mechanical Systems” no. 19 of the Presidium of the Russian Academy of Sciences and National School Grant, no. 2258.2003.1.     

Dynamic interval index structure in constraint database systems

Interval index structure plays an important role in constraint database systems.A dynamic interval index structure DM-tree is presented in this paper.The advantage of the DM-tree compared with other interval index structures is that the dynamic operations of insertion and deletion can be operated on the new structure.The storage complexity of the tree is O(n),and the query I/O complexity is O(longn t/B).To improve the performance of the inserting and deleting operations some methods such as neighbored-constraint and update-late are applied.The I/O complexity of inserting and deleting operations is the same as that in B-tree.i.e.,.O(logn).     

Finite‐Time Optimal Formation Control for Second‐Order Multiagent Systems

This paper studies the problem of finite‐time optimal formation control for second‐order multiagent systems in situations where the formation time and/or the cost function need to be considered. The finite‐time optimal formation control laws are proposed for the cases with or without a leader, respectively. For the case of control being constrained, the time optimal formation problem is considered and an algorithm is designed to derive a feasible solution for the problem concerned. Although the feasible solution may not be optimal, it can provide a lower bound for time for the formation problem with control constraints. Once the given formation time is lower than this bound, the control constraints cannot be ensured. Finally, some numerical examples are given to illustrate the effectiveness of the theoretical results.     

区块链中区块截留攻击的研究与分析

区块截留攻击又称扣块攻击,是存在于区块链中的一种攻击方式,攻击者通过渗透进目标矿池中进行消极挖矿以达成破坏目标矿池的目的.简要介绍了挖矿机制和区块截留攻击的工作原理,总结了区块截留攻击的几种模型,并对现有的区块截留攻击模型的攻击方式和收益进行了研究,分析出其攻击效果.构造了一个在提升收益率的同时提升收益速度的区块截留攻...     

内网安全产品中的旁路阻断技术分析

内网安全的理念是建立可信、可控的内部安全网络,旁路阻断作为内网安全可控的技术手段,通过与网络监听的结合,利用构造TCP回应包、DNS欺骗、ARP欺骗等多种方式对非法节点进行阻断,给出了旁路阻断的技术原理分析,并给出基于WinPcap的设计框架。