一种基于广义混沌序列的图像加密技术

 给出一种构造广义混沌序列的方法, 并把该混沌序列应用于数字图像加密.基于n次Bézier曲线和n次有理Bézier曲线给出两种构造广义混沌序列的方法, 生成的混沌序列具有很好的伪随机性. 通过对混沌序列的非线性离散化处理, 可以生成相应的整数型伪随机序列, 利用该整数型混沌序列对数字图像进行加密.数字实验表明, 该算法生成的混沌序列对数字图像加密效果良好, 且该加密算法简单易行, 具有较好的安全性．     

合成孔径声呐Chirp Scaling成像算法

在合成孔径声呐领域中经典的成像处理方法是距离-多普勒算法。距离-多普勒算法的主要缺点是在进行方位处理时需要进行距离二次脉压和在进行距离徙动校正时需要进行插值处理,这样将导致运算量迅速增加,并且降低了成像精度。而ChirpScaling算法是在二维频域中精确实现距离门徙动校正和二次距离压缩,避免了插值运算,用该算法处理了仿真点目标的回波数据,结果表明该算法既能够实现更加精确的成像又能够避免插值运算而提高运算效能。     

彩色图像中椭圆的快速检测算法

椭圆检测是图像处理中常用的技术,由于自然界很多物体都可以用椭圆进行拟合,所以也成为图像分割和目标提取的关键技术.该文分析了椭圆的解析结构,利用椭圆长短轴之间的几何关系,从边缘点集合中选取全局性的参数,快速生成椭圆.算法针对彩色图像,引入了彩色边缘增强算法和基于图搜索的边缘追踪算法,生成封闭的边缘轮廓曲线,对每段曲线进行椭圆拟合,通过拟合评估,形成拟合判决,确定图像中的椭圆区域.算法计算量小,检测速度快,对多椭圆和椭圆弧都能准确检测.     

对Sutherland-Cohen算法的改进

提出了对Sutherland-Cohen算法的改进.通过引进辅助直线进行直线裁剪,只需两次求交运算就即求出线段的可见部分,还减少了对线段的重编码运算,具有和NLN算法相同高的效率.通过引入辅助平面进行三维裁剪,克服了NLN算法不能扩展到三维的缺点,而且其三维裁剪效率高于Sutherland-Cohen算法和梁友栋-Barsky算法.     

集成电路多故障测试生成算法研究

对组合电路的测试生成算法进行研究,介绍具有约束条件的布尔差分算法,还对时序电路的测试生成算法进行研究,九值算法比D算法在做D驱赶时要减少很多次无用的计算,在对电路进行描述时充分考虑了故障对电路的重复影响作用,可以对D算法无法产生测试的故障产生测试矢量.     

基于最小二乘原理的平面任意位置椭圆的评价

给出一种基于最小二乘原理的椭圆误差的评价方法。根据平面任意位置椭圆方程的特点 ,用“变量代换”的手法使得复杂的非线性方程线性化。拟合计算一次完成 ,无需进行诸如圆、球体等拟合算法中所需的叠代循环运算。文中给出了其数学模型和具体的计算方法     

一种优化的二次接线自动生成方法研究

针对已有的二次接线方法在处理继电元件时类型有限、优化效果不好且需要手工生成端子接线图的缺点,提出了一种优化的二次接线自动生成的计算机辅助设计方法。首先采用广度优先搜索算法得到原理图中元件端子的连接关系,同时提出了完全无向图中经过每个顶点一次且仅一次的最短路径算法和改进的Prim最小生成树算法,利用这两个算法可自动生成屏内安装接线图和端子接线图。实践证明,这种优化的二次接线自动生成方法提高了系统的运行速度,并解决了满足布线工艺约束下的连接导线总长度最小的屏内安装接线图和端子排图自动生成之间的瓶颈问题。     

Elrod算法与负压力充零算法的比较

Reynold方程是油膜轴承的压力控制方程,本文对该方程的两个数值算法,即Elrod算法和充零算法,进行了大量的实例运算比较,发现在大多数情况下两者给出的结果比较相近,但Elrod算法有收敛速度慢,不稳定和适用参数范围有限制等缺点。更为不足的是,Elrod算法由于考虑油膜历史,不能由某一瞬时的运动状态确定该时刻的瞬态油膜压力分布。本文认为,在数值求解Reynold方程中充零算法优于Elrod算法。     

一种宽椭圆生成算法

计算机辅助设计领域常涉及宽椭圆生成,宽椭圆生成算法的优劣直接影响设计效果.为了生成一个圆心在原点的标准宽椭圆,每次用单像素宽的椭圆中点扫描转换算法,得到一个单像素宽椭圆上的一个点,填充一个以该点为中心,椭圆宽为直径的圆弧,扫描转换结束后,生成一个无明显视觉缺陷的第一象限1/2宽椭圆.     

最大似然阵处理的迭代算法

本文提出了在最大似然阵处理中以矢量的内积运算代替交错投影法的二次项运算的迭代算法。这种算法减小了运算量,收敛、性能好。计算机模拟结果验证了算法的有效性。     

基于批量划分的无等待流水车间订单接受问题研究

在无等待流水车间环境下,考虑订单分批量加工策略的订单接受问题,建立问题的数学模型。由于问题的NP难特性,提出改进的遗传算法对模型进行求解。改进的算法采用正向和反向NEH算法与随机方法产生初始种群,在算法更新过程中将禁忌搜索算法嵌入到遗传算法中来实现局部搜索,避免算法陷入局部最优。最后,算例表明批量划分策略能够有效减少订单的完成时间,实现订单总收益的最大化。通过算法对比,说明了改进遗传算法具有较好的求解效果。     

解复杂二次整数规划问题的新型分枝定界算法

针对二次整数规划问题的特征，本文对传统分枝定界算法做了一系列的改进，其包括用HNF算法寻求初始整数可行解、对变量进行某种先验排序以确定分枝变量的选取次序、及针对变量的特性来选取分枝方向等，给出了可用于求解中大规模复杂二次整数规划问题的改进型分枝定界算法。数值试验结果表明所给算法大大改进了传统的分枝定界算法，并有广泛的适用性。     

Bi-level heat exchanger network synthesis with evolution method for structure optimization and memetic particle swarm optimization for parameter optimization

The synthesis of heat exchanger networks (HENs) is a complex problem because of the nonlinearity that results from the integer and continuous variables. Here, a bi-level algorithm for the optimal design of a HEN is proposed that attempts to optimize separately the integer and continuous variables on two levels. The master level is a problem-oriented evolution method generating new candidate HEN structures. The slave level is a memetic particle swarm optimization, an improved particle swarm optimization combined with a local search component, improvement of neighbourhood topologies and control parameter preference. The slave level minimizes the total annual cost (TAC) of a given structure received from the master level, and then sends this value back to the master level for structure evolution. The proposed bi-level method is applied to several cases taken from the literature, which demonstrate its reliable search ability in both structure space and continuous variable space and its ability to optimize the system, producing generally lower TACs than previously used methods.     

Greedy robust wind farm layout optimization with feasibility guarantee

This article proposes a method with light data requirements for generating robust wind farm layouts. Robustness in this work is quantified as the lowest energy conversion efficiency of the wind farm across all wind directions. A quadratic integer programming formulation for generating robustness-maximizing layouts is presented. Small instances of the proposed formulation can be solved to optimality using branch and bound. A modified greedy algorithm that guarantees solution feasibility with regards to inter-turbine safety distance is proposed to find solutions to larger problem instances. A series of experiments were conducted using real world wind data collected at two sites to demonstrate the trade-offs in power generation between robust layouts and power output maximizing layouts. The results show a loss of around 1.1% in hourly power generation in return for an increase in minimum power output of 1% to 45% across all directions for robust layouts generated in the experiments. The increase in robustness largely depends on the shape and orientation of the wind farm relative to the dominant wind direction, as well as the difference between the average wind speed at the site of the wind farm and rated wind speed of the turbines.     

Simultaneous Shifted Continued Fraction Expansions in Quadratic Time

In the theory of stream ciphers, important measures to assess the randomness of a given bit sequence are the linear and the jump complexity, both obtained from the continued fraction expansion (c.f.e.) of the generating function of the sequence. This paper describes a way to compute all continued fraction expansions (and thereby the linear complexity profiles, l.c.p.'s) of the shifted sequences , , , simultaneously in at most bit operations on bit space. If is not fixed beforehand, but varies during the computation, we have to start from . In this case we obtain the result in bit operations on space or as well in bit operations on linear space. In comparison, the well-known Berlekamp--Massey algorithm, when applied iteratively, needs O steps. A recent algorithm of Stephens and Lunnon works in O integer operations, but only gives the l.c.p., not the complete c.f.e. Received: April 29, 1996; revised version: November 3, 1997     

Accurate phase extraction algorithm based on Gram–Schmidt orthonormalization and least square ellipse fitting method

An accurate algorithm by combing Gram–Schmidt orthonormalization and least square ellipse fitting technology is proposed, which could be used for phase extraction from two or three interferograms. The DC term of background intensity is suppressed by subtraction operation on three interferograms or by high-pass filter on two interferograms. Performing Gram–Schmidt orthonormalization on pre-processing interferograms, the phase shift error is corrected and a general ellipse form is derived. Then the background intensity error and the corrected error could be compensated by least square ellipse fitting method. Finally, the phase could be extracted rapidly. The algorithm could cope with the two or three interferograms with environmental disturbance, low fringe number or small phase shifts. The accuracy and effectiveness of the proposed algorithm are verified by both of the numerical simulations and experiments.     

k-supplier问题的贪婪近似算法

给定无向完全图G=(V,E)和正整数k,图G的顶点集V被划分为子集F和子集D=V-F.k-supplier问题主要研究如何寻找F中顶点数不多于k的子集S,使得S中的顶点到D中顶点的最大距离最小.研究了k-supplier问题,得到了一个近似比为3的多项式时间贪婪近似算法,并通过实例验证了该算法的有效性.     

An effective hybrid cuckoo search and genetic algorithm for constrained engineering design optimization

This article presents an effective hybrid cuckoo search and genetic algorithm (HCSGA) for solving engineering design optimization problems involving problem-specific constraints and mixed variables such as integer, discrete and continuous variables. The proposed algorithm, HCSGA, is first applied to 13 standard benchmark constrained optimization functions and subsequently used to solve three well-known design problems reported in the literature. The numerical results obtained by HCSGA show competitive performance with respect to recent algorithms for constrained design optimization problems.