PSO-SVM在网络入侵检测中的应用

为了提高网络入侵检测效果以加强网络安全性,提出一种网络状态特征和支持向量机(SVM)参数联合选择的网络入侵检测模型(PSO-SVM).以网络入侵检测正确率作为目标,特征子集和SVM参数作为约束条件建立数学模型,通过粒子群优化算法对模型进行求解,找到最优特征子集和SVM参数,利用KDD Cup 99数据集对算法性能进行测试.测试结果表明,相对于其它入侵检测算法,PSO-SVM可以找到更优特征子集和SVM参数,加快了检测速度,有效地提高了网络入侵检测正确率,为网络入侵检测提供了一种新的研究思路.     

改进蚁群算法优化支持向量机的网络入侵检测

针对支持向量机参数优化问题,为了提高网络入侵检测率,提出一种变异蚁群算法优化支持向量机的网络入侵检测模型(MACO-SVM)。首先采用蚁群搜索路径节点代表支持向量机参数,并将网络入侵检测率为目标函数,然后通过蚁群算法的全局寻优能力和反馈机制寻找最优参数,并对蚂蚁进行高斯变异,克服蚁群陷入局部极值,最后将最优路径上的节点连接起来得到 SVM的最优参数,建立最优网络入侵检测模型。采用KDD99数据集对模型进行仿真实验,仿真结果表明,MACO-SVM的网络入侵检测速度要快于其它网络入侵检测模型,而且提高了网络入侵检测率。     

改进蚁群算法和支持向量机的网络入侵检测

为了提高网络入侵检测的正确率,提出一种改进蚁群优化算法（ACO）和支持向量机（SVM）相融合的网络入侵检测方法（ACO-SVM）。将SVM模型参数作为蚂蚁的位置向量,采用动态随机抽取的方法来确定目标个体引导蚁群进行全局搜索,同时在最优蚂蚁邻域内进行小步长局部搜索,找到SVM最优参数,采用最优参数建立网络入侵检测模型。利用KDDCUP99数据集对ACO-SVM性能进行测试,结果表明,ACO-SVM提高了网络入侵检测正确率,降低了误报率,可以为网络安全提供有效保证。     

PSO-SVM算法在网络入侵检测中的研究

保证网络运行的安全性,防止外来攻击与破坏,进行准确检测.由于网络入侵具有不确性,针对复杂性和多样性,传统检测方法不能有效对这种特性进行识别,导致目前网络入侵检测准确率低.为了提高网络入侵检测准确率,将粒子群(PSO)算法引入到网络人侵检测中,用优化SVM参数.PSO-SVM将网络入侵检测数据输入到SVM中学习,将SVM参数作为PSO中的粒子,把网络人侵检测准确率作为PSO的目标函数,然后通过粒子之间相互协作得到SVM最优参数,最后对网络入侵数据进行检测并输出网络人侵检测结果.在Matlab平台上采用DRAP网络入侵数据集对PSO-SVM进行仿真.实验结果表明,改进的方法PSO-SVM检测速度快,检测准确率高,为网络安全提供可靠保障.     

PCA-SVM在网络入侵检测中的仿真研究

研究网络安全问题,针对网络入侵数据是一种小样本、高维和冗余数据,传统检测方法无法进行很好降维且基于大样本数据,因此入侵检测率低.为了提高网络入侵检测率和网络安全,提出一种主成分分析(PCA)的支持向量机(SVM)网络入侵检测方法(PCA-SVM).PCA-SVM首先通过PCA对网络入侵原始数据进行维数和消除冗余信息处理,减少了支持向量机的输入,采用粒子算法对支持向量机参数进行优化,获得最优网络入侵支持向量机检测模型,最后最优支持向量机模型对网络入侵数据进行测试.采用网络数据集在Madab平台上对PCA-SVM算法进行仿真,结果表明,采用PCA-SVM加快了网络入侵检测速度,提高了检测率,降低了网络入侵漏报率,为网络入侵检测提供了一种实时检测工具.     

粒子群优化支持向量机的入侵检测算法

为了提高网络入侵的检测正确率,针对网络入侵检测中特征选择问题,将二值粒子群优化算法(BPSO)用于网络入侵特征选择,结合支持向量机(SVM)提出了一种基于BPSO-SVM的网络入侵检测算法。该算法将网络入侵检测转化为多分类问题,采用wrapper特征选择模型,以SVM为分类器,通过样本训练分类器,根据分类结果,利用BPSO算法在特征空间中进行全局搜索,选择最优特征集进行分类。实验结果表明,BPSO-SVM有效降低了特征维数,显著提高了网络入侵的检测正确率,还大大缩短了检测时间。     

蝙蝠算法优化神经网络的网络入侵检测

研究网络入侵安全问题,网络入侵具有隐蔽性、随机性和突发性等复杂变化特点,传统方法无法描述变化规律,导致入侵检测正确率低。为了提高网络入侵检测效果,针对BP神经网络参数优化问题,提出一种蝙蝠算法优化BP神经网络的权网络入侵检测模型(BA-BPNN)。首先将BP神经网络参数编码为蝙蝠个体,并以网络入侵检测正确率作为个体适应度函数,然后通过模拟蝙蝠飞行过程找到BP神经网络最优参数,最后根据最优参数建立网络入侵检测模型。在Matlab 2012平台采用KDD CUP 99数据集仿真测试,结果表明,BA-BPNN解决了传统神经网络模型存在的难题,提高网络入侵检测正确率。     

基于改进鲸鱼算法的工控系统入侵检测研究

针对工控入侵检测模型训练时间长、检测率低的问题,文章提出一种改进的鲸鱼算法(IWOA)来优化SVM入侵检测模型中的参数。改进的鲸鱼算法首先引入AFSA的自适应步长和拥挤度因子,加快全局收敛速度,避免种群位置过度拥挤导致的算法早熟现象;其次,在局部搜索中加入高斯变异算子使算法跳出局部最优区域。将IWOA运用到SVM入侵检测模型参数寻优,对工控系统天然气管道数据集进行仿真,仿真结果表明,该模型检测正确率和检测速度明显提高。     

基于AFSA-SVM的网络入侵检测模型

特征选择是网络入侵检测研究中的核心问题,为了提高网络入侵检测率,提出一种人工鱼群算法（AFSA）和支持向量机（SVM）相融合的网络入侵检测模型（AFSA-SVM）。将网络特征子集编码成人工鱼的位置,以5折交叉验证SVM训练模型检测率作为特征子集优劣的评价标准,通过模拟鱼群的觅食、聚群及追尾行为找到最优特征子集,SVM根据最优特征子集进行网络入侵检测,并采用KDD CUP 99数据集进行仿真测试。仿真结果表明,相对于粒子群优化算法、遗传算法和原始特征法,AFSA-SVM提高了入侵检测效率和检测率,是一种有效的网络入侵检测模型。     

基于萤火虫群优化支持向量机的网络入侵检测方法

为了解决支持向量机(SVM)方法应用于网络入侵检测中存在的参数设置和由样本不均带来的分类面偏斜问题,文章提出了一种基于萤火虫群优化支持向量机(GSO-SVM)的解决方案;算法在进行参数寻优的同时增加了修正因子,实现对分类面的修正,并采用萤火虫群算法进行求解,提高算法跳出局部最优的能力;在DARPA数据集上的检测精度达到97.33%,优于SVM和SVDD方法;实验结果表明文章提出的方法能够有效提高入侵检测模型的泛化性,降低误报率和漏报率。     

Web前端性能优化方案与实践

针对Web前端性能低下的问题,通过分析归纳Web中从后端到前端的B/S架构原理、浏览器缓存、浏览器的加载方式、服务器关于HTTP相关的配置等过程中一些影响前端性能优化的因素,系统地提出一个旨在提高网页加载速度、呈现速度和用户体验,整体性、通用性强的完整Web前端性能优化解决方案。该解决方案包括服务器端优化、HTML优化、Java Script优化、CSS优化、图片优化等内容。并在HTTP代理工具Fiddler搭建的512 KB慢网速下通过Speed Tracer监测UI Thread,寻找基于HTML5技术的Web移动电子商务项目"指尖点餐系统"的点餐页面前端性能中的瓶颈,根据所提出的Web前端性能优化解决方案对其进行优化实践。优化前后的Timeline以及UI Thread对比分析表明,优化后加载时间降低了82%,页面渲染降低了32%,脚本执行减少了79%。     

Seeker optimisation (human group optimisation) algorithm with chaos

Seeker optimisation algorithm (SOA), also referred to as human group metaheuristic optimisation algorithms form a very hot area of research, is an emerging population-based and gradient-free optimisation tool. It is inspired by searching behaviour of human beings in finding an optimal solution. The principal shortcoming of SOA is that it is easily trapped in local optima and consequently fails to achieve near-global solutions in complex optimisation problems. In an attempt to relieve this problem, in this article, chaos-based strategies are embedded into SOA. Five various chaotic-based SOA strategies with four different chaotic map functions are examined and the best strategy is chosen as the suitable chaotic scheme for SOA. The results of applying the proposed chaotic SOA to miscellaneous benchmark functions confirm that it provides accurate solutions. It surpasses basic SOA, genetic algorithm, gravitational search algorithm variant, cuckoo search optimisation algorithm, firefly swarm optimisation and harmony search the proposed chaos-based SOA is expected successfully solve complex engineering optimisation problems.     

The multi-disciplinary design of a large-scale civil aircraft wing taking account of manufacturing costs

This paper presents results from a major research programme funded by the European Union and involving 14 partners from across the Union. It shows how a complex tool set was assembled which was able to optimise a large civil airliner wing for weight, drag and cost. A multi-level MDO process was constructed and implemented through a hierarchical system in which cost comprised the top level. Conventional structural sizing parameters were employed to optimise structural weight but the upper-level optimisation used 6 overall design variables representing major design parameters. The paper concludes by presenting results from a case study which included all the components of the total design system.     

Dynamic Ant Colony Optimisation

Ant Colony optimisation has proved suitable to solve static optimisation problems, that is problems that do not change with time. However in the real world changing circumstances may mean that a previously optimum solution becomes suboptimal. This paper explores the ability of the ant colony optimisation algorithm to adapt from the optimum solution for one set of circumstances to the optimal solution for another set of circumstances. Results are given for a preliminary investigation based on the classical travelling salesman problem. It is concluded that, for this problem at least, the time taken for the solution adaption process is far shorter than the time taken to find the second optimum solution if the whole process is started over from scratch.     

Enhanced leader PSO (ELPSO): A new PSO variant for solving global optimisation problems

Particle swarm optimisation (PSO) is a well-established optimisation algorithm inspired from flocking behaviour of birds. The big problem in PSO is that it suffers from premature convergence, that is, in complex optimisation problems, it may easily get trapped in local optima. In this paper, a new PSO variant, named as enhanced leader PSO (ELPSO), is proposed for mitigating premature convergence problem. ELPSO is mainly based on a five-staged successive mutation strategy which is applied to swarm leader at each iteration. The experimental results confirm that in all terms of accuracy, scalability and convergence rate, ELPSO performs well.     

A genetic algorithm for combined topology and shape optimisations

A method to find optimal topology and shape of structures is presented. With the first the optimal distribution of an assigned mass is found using an approach based on homogenisation theory, that seeks in which elements of a meshed domain it is present mass; with the second the discontinuous boundaries are smoothed. The problem of the optimal topology search has an ON/OFF nature and has suggested the employment of genetic algorithms. Thus in this paper a genetic algorithm has been developed, which uses as design variables, in the topology optimisation, the relative densities (with respect to effective material density) 0 or 1 of each element of the structure and, in the shape one, the coordinates of the keypoints of changeable boundaries constituted by curves. In both the steps the aim is that to find the variable sets producing the maximum stiffness of the structure, respecting an upper limit on the employed mass. The structural evaluations are carried out with a FEM commercial code, linked to the algorithm. Some applications have been performed and results compared with solutions reported in literature.     

A new effective operator for the hybrid algorithm for solving global optimisation problems

Hybrid algorithms have been recently used to solve complex single-objective optimisation problems. The ultimate goal is to find an optimised global solution by using these algorithms. Based on the existing algorithms (HP_CRO, PSO, RCCRO), this study proposes a new hybrid algorithm called MPC (Mean-PSO-CRO), which utilises a new Mean-Search Operator. By employing this new operator, the proposed algorithm improves the search ability on areas of the solution space that the other operators of previous algorithms do not explore. Specifically, the Mean-Search Operator helps find the better solutions in comparison with other algorithms. Moreover, the authors have proposed two parameters for balancing local and global search and between various types of local search, as well. In addition, three versions of this operator, which use different constraints, are introduced. The experimental results on 23 benchmark functions, which are used in previous works, show that our framework can find better optimal or close-to-optimal solutions with faster convergence speed for most of the benchmark functions, especially the high-dimensional functions. Thus, the proposed algorithm is more effective in solving single-objective optimisation problems than the other existing algorithms.     

一种解决复合形局部最优及加速计算的方法

对求解非线性约束优化问题的复合形法陷入局部最优的问题进行探讨,给出了一种改进的方法.改进后的方法不仅可以有效地寻找全局最优解,而且计算速度较传统复合形算法快.     

Finding the maximal membership in a fuzzy set of an element from another fuzzy set

The problem of finding the maximal membership grade in a fuzzy set of an element from another fuzzy set is an important class of optimisation problems manifested in the real world by situations in which we try to find what is the optimal financial satisfaction we can get from a socially responsible investment. Here, we provide a solution to this problem. We then look at the proposed solution for fuzzy sets with various types of membership grades, ordinal, interval value and intuitionistic.     

Chaotic bat swarm optimisation (CBSO)

Bat swarm optimisation (BSO) is a novel heuristic optimisation algorithm that is being used for solving different global optimisation problems. The paramount problem in BSO is that it severely suffers from premature convergence problem, that is, BSO is easily trapped in local optima. In this paper, chaotic-based strategies are incorporated into BSO to mitigate this problem. Ergodicity and non-repetitious nature of chaotic functions can diversify the bats and mitigate premature convergence problem. Eleven different chaotic map functions along with various chaotic BSO strategies are investigated experimentally and the best one is chosen as the suitable chaotic strategy for BSO. The results of applying the proposed chaotic BSO to different benchmark functions vividly show that premature convergence problem has been mitigated efficiently. Actually, chaotic-based BSO significantly outperforms conventional BSO, cuckoo search optimisation (CSO), big bang-big crunch algorithm (BBBC), gravitational search algorithm (GSA) and genetic algorithm (GA).