A novel particle swarm optimizer hybridized with extremal optimization

Particle swarm optimization (PSO) has received increasing interest from the optimization community due to its simplicity in implementation and its inexpensive computational overhead. However, PSO has premature convergence, especially in complex multimodal functions. Extremal optimization (EO) is a recently developed local-search heuristic method and has been successfully applied to a wide variety of hard optimization problems. To overcome the limitation of PSO, this paper proposes a novel hybrid algorithm, called hybrid PSO–EO algorithm, through introducing EO to PSO. The hybrid approach elegantly combines the exploration ability of PSO with the exploitation ability of EO. We testify the performance of the proposed approach on a suite of unimodal/multimodal benchmark functions and provide comparisons with other meta-heuristics. The proposed approach is shown to have superior performance and great capability of preventing premature convergence across it comparing favorably with the other algorithms.     

基于自注意力机制的图像隐写分析方法

针对自适应图像隐写分析难度大、现有的模型难以对图像有利区域进行针对性分析的问题,提出了一种基于自注意力机制的图像隐写分析模型(self-attention steganalysis residual network,SA-SRNet)。该模型将自注意力机制引入SRNet(steganalysis residual network),引导模型更加关注图像全局对隐写分析有利的区域及图像长距离之间的依赖关系,解决了硬注意力机制在训练时容易陷入局部最优的问题。首先,奖励机制利用强化学习使模型找到对隐写分析最有利的检测点;其次,自注意力机制根据检测点生成注意力重点图像;最后,替换机制用注意力重点图像替换识别错误的图像,提高训练集的质量和模型的判别能力。实验在BOSSbase 1.01数据集上进行,结果表明SA-SRNet可获得比SRNet更好的隐写分析准确率,最多可提高1.8%。     

Correction of array failure using grey wolf optimizer hybridized with an interior point algorithm

We design a grey wolf optimizer hybridized with an interior point algorithm to correct a faulty antenna array. If a single sensor fails, the radiation power pattern of the entire array is disturbed in terms of sidelobe level (SLL) and null depth level (NDL), and nulls are damaged and shifted from their original locations. All these issues can be solved by designing a new fitness function to reduce the error between the preferred and expected radiation power patterns and the null limitations. The hybrid algorithm has been designed to control the array’s faulty radiation power pattern. Antenna arrays composed of 21 sensors are used in an example simulation scenario. The MATLAB simulation results confirm the good performance of the proposed method, compared with the existing methods in terms of SLL and NDL.     

A genetic algorithm and a particle swarm optimizer hybridized with Nelder–Mead simplex search

This paper integrates Nelder–Mead simplex search method (NM) with genetic algorithm (GA) and particle swarm optimization (PSO), respectively, in an attempt to locate the global optimal solutions for the nonlinear continuous variable functions mainly focusing on response surface methodology (RSM). Both the hybrid NM–GA and NM–PSO algorithms incorporate concepts from the NM, GA or PSO, which are readily to implement in practice and the computation of functional derivatives is not necessary. The hybrid methods were first illustrated through four test functions from the RSM literature and were compared with original NM, GA and PSO algorithms. In each test scheme, the effectiveness, efficiency and robustness of these methods were evaluated via associated performance statistics, and the proposed hybrid approaches prove to be very suitable for solving the optimization problems of RSM-type. The hybrid methods were then tested by ten difficult nonlinear continuous functions and were compared with the best known heuristics in the literature. The results show that both hybrid algorithms were able to reach the global optimum in all runs within a comparably computational expense.     

A novel quasi-oppositional chaotic antlion optimizer for global optimization

This paper proposes a novel quasi-oppositional chaotic antlion optimizer (ALO) (QOCALO) for solving global optimization problems. ALO is a population based algorithm motivated by the unique hunting behavior of antlions in nature and exhibits strong influence in solving global and engineering optimization problems. In the proposed QOCALO algorithm of the present work, the initial population is generated using the quasi-opposition based learning (QOBL) and the concept of QOBL based generation jumping is utilized inside the main searching strategy of the proposed algorithm. Utilization of QOBL ensures better convergence speed of the proposed algorithm and it also provides better exploration of the search space. Alongside the QOBL, a chaotic local search (CLS) is also incorporated in the proposed QOCALO algorithm. The CLS guides local search around the global best solution that provides better exploitation of the search space. Thus, a better trade-off between exploration and exploitation holds for the proposed algorithm which makes it robust. It is observed that the proposed algorithm offers better results than the original ALO in terms of solution quality and convergence speed. The proposed QOCALO algorithm is implemented and tested, successfully, on nineteen mathematical benchmark test functions of varying complexities and the experimental results are compared to those offered by the basic ALO and some other recently developed nature inspired algorithms. The efficacy of the proposed algorithm is further utilized to solve three real world engineering optimization problems viz. (a) the placement and sizing problem of distributed generators in radial distribution networks, (b) the congestion management problem in power transmission system and (c) the optimal design of pressure vessel.     

新的基于混沌搜索的组优化算法

为提高组搜索优化(GSO)算法的性能,结合混沌方法的全局搜索特性,提出一种新的基于混沌搜索的组搜索优化（CGSO）算法。此方法中,生产者利用混沌搜索方法不断寻找较好的位置;占领者结合当前生产者的位置和自己运动到目前为止的最好位置对自己当前的位置进行更新;徘徊者采用混沌变异方法探索新的位置。该算法运用Logistic映射的初值敏感性扩大搜索范围,利用其全局遍历性进行位置搜索,有效地提高了算法的全局收敛性。采用CGSO、GSO算法对四个典型的函数优化问题进行了仿真实验,仿真结果验证了方法的有效性。     

基于卷积神经网络的图像隐写分析方法

为了提高卷积神经网络(CNN)在图像隐写分析领域的分类效果,构建了一个新的卷积神经网络模型（steganalysis-convolutional neural networks,S-CNN）进行隐写分析。该模型采用两层卷积层和两层全连接层,减少了卷积层的层数;通过在激活函数前增加批量正规化层对模型进行优化,避免了模型在训练过程中陷入过拟合;取消池化层,减少嵌入信息的损失,从而提高模型的分类效果。实验结果表明,相比传统的图像隐写分析方法,该模型减少了隐写分析步骤,并且具有较高的隐写分析准确率。     

基于显著性检测的图像隐写分析方法

针对图像隐写分析难度大、现有的检测模型难以对图像隐写区域进行针对性检测的问题,提出了一种基于显著性检测的图像隐写分析方法.该方法利用显著性检测技术引导隐写分析模型更加关注图像隐写区域的特征.首先,显著性检测模块生成图像的显著性区域;其次,区域筛选模块筛选出与隐写区域重合度较高的显著性图,利用图像融合技术与原始图像进行融...     

基于小波系数相关性的图像隐写分析

提出了一种基于小波包分解和小波系数相关性的通用型图像隐写分析方法。对差分处理后的图像进行小波包分解,提取图像及其小波子带的高阶统计量作为特征。利用图像小波系数在尺度方向和空间方向的相关性,使用马尔可夫模型挖掘小波系数层内和层间相关性,提取转移概率矩阵作为特征。针对H4PGP、F5和OutGuess隐写算法的实验表明,方法对上述三种隐写算法具有较好的检测效果。     

A novel chaotic differential evolution hybridized with quadratic programming for short-term hydrothermal coordination

In this paper, a viable global optimizer based on chaotic differential evolution is hybridized with sequential quadratic programming, an efficient local search technique to exploit short-term hydrothermal coordination (STHTC) involved for power generation and its efficient management. A multi-objective optimization framework is established for minimizing the total cost of thermal generators with valve point loading effects satisfying power balance constraint as well as generator operating and hydrodischarge limits, respectively. The proposed model is implemented on various systems comprising hydrogenerating units as well as different thermal units. The results are compared with state-of-the-art heuristic techniques recently employed on STHTC problems, while the reliability, stability and effectiveness of the proposed framework are validated through the comprehensive analysis of Monte Carlo simulations.

     

A particle swarm optimizer with chaotic self-feedback for global optimization of multimodal functions

This paper proposes an improved particle swarm optimization （PSO） with iterative chaotic map with infinite collapses （ICMIC） perturbations （ICMICPSO） for global optimization of multimodal functions. The chaotic perturbation generated by the ICMIC is incorporated into the particle＇s velocity updating rule as self-feedback to make the particles have a larger potential space to fly. With the coefficient of chaotic perturbation decaying, the dynamics of ICMICPSO algorithm is a chaotic dynamics first and then a steepest descent dynamics. The proposed ICMICPSO method as hybrid optimization is tested on several widely used multimodal functions. Numerical results of the proposed algorithm are compared with that of some other Chaotic PSO variants available in the existing literature. The performance studies demonstrate that the effectiveness and efficiency of the proposed ICMICPSO approach are comparably to or better than that of the other CPSO variants for solving the global optimization of multimodal functions.     

基于环境信息熵的点线视觉里程计自适应优化器设计

针对即时定位与建图技术中点线视觉里程计在环境纹理发生变化时运行效率低下的问题,设计了一种基于环境信息熵的特征提取自适应优化器,以提高原有点线视觉里程计算法的效率及鲁棒性。优化器以图像信息熵作为主要影响因子,确定里程计的最优提取特征,生成包含特征提取选择的策略信息地图;对未探索区域的纹理环境进行预判性计算,与策略地图快速匹配,得到该区域的最优特征提取策略。在TUM数据集环境下测试了具有优化器的点线视觉里程计(APL-VO)的平均处理时间及建图效果。实验结果显示,与原有算法相比,具有自适应优化器的点线视觉里程计在复合环境中具有更强的鲁棒性及建图效率。     

基于鸽群算法的Fuch混沌蝗虫算法

针对蝗虫算法(GOA)存在位置更新易陷于局部最优和收敛精度低等问题,提出一种基于鸽群算法的Fuch混沌蝗虫算法(PFGOA).首先用Fuch混沌映射初始化种群;然后将正弦余弦算子嵌入到位置更新公式,同时将鸽子搜索算子加入优化过程,并且通过改变惯性权重c来改善和平衡该算法的探索和开发能力;最后对最优个体引入非线性惯性权重,增加算法全局搜索能力,跳出局部最优.通过对11个测试函数进行仿真测试以及用Wilcoxon秩和检验的方法进行差异显著性统计检验的实验结果证明,改进后的算法性能更优,求解精度更高,显著性更好.     

基于新残差网络的图像隐写分析方法

卷积神经网络在隐写分析领域取得了一系列进展,但现有网络结构大多都是专用隐写分析,只针对某一类隐写算法有效.为了提高模型的泛化能力,提出了一种基于新残差网络的图像隐写分析算法.构建了残差分组融合网络结构(W-R2 N),采用分组融合的方式来提高提取多尺度特征的能力,增大每层网络的感受野范围,并且增加每组卷积的对角相关性.相对于Xu-Net和SRNET在S-UNIWARD嵌入率为0.4 bpp情况下隐写分析准确率分别提高了17.13％和0.81％.实验结果表明,相对于现有卷积神经网络,该模型泛化能力更好,并且能够有效提高隐写分析的准确率.     

基于密集连接网络的图像隐写分析

针对目前传统的隐写分析技术对特征集要求越来越高的问题,构建了一个密集连接网络模型（Steganalysis-Densely Connected Convolutional Networks,S-DCCN）进行图像隐写分析,避免了人工提取特征,提高了隐写分析效率。首先,在网络层之前添加高通滤波层（HPF）进行滤波,加快模型训练速度。经过滤波后的图像进入两层卷积层进行特征提取,在卷积层之后使用了5组密集连接模块来解决网络加深带来的梯度消失问题,密集连接模块之间通过过度层来控制整个网络的宽度。实验结果表明,相比传统的图像隐写分析算法和卷积神经网络技术,该模型有效提高了隐写分析的准确率和泛化性能。     

Image universal steganalysis based on best wavelet packet decomposition

Based on the best wavelet packet decomposition of images, a new universal steganalysis method with high detection correct ratio is proposed. First, the best wavelet packet decomposition of image based on the Shannon entropy information cost function is made. Second, high order absolute characteristic function moments of histogram extracted from the coefficient subbands obtained by best wavelet packet decomposition are regarded as features. Finally, these features are processed and a back-propagation (BP) ne...     

基于马尔可夫模型和特征融合的图像隐写分析

提出一种针对JPEG图像隐写的通用隐写分析方法.根据量化后分块DCT系数绝对值构造水平、垂直和zigzag方向的差分数组,利用三向差分数组马尔可夫模型挖掘量化后分块DCT块内邻近系数相关性,提取转移概率矩阵的特征.对三向特征加权融合后进行隐写分析,以提高分类性能.对安全性较高的JPEG隐写OutGuess和F5,在不同嵌入率下进行隐写分析.实验结果显示,引入特征融合后隐写分析的检出率明显提高.     

离散混沌系统类随机性的符号熵分析法

采用符号熵分析法,分析和讨论了经典的Logistic映射和Henon映射的类随机性强弱.先将离散混沌系统产生的实数序列转化为二进制序列,然后进行编码,计算其符号熵,绘制其符号熵图,并深入讨论了系统参数和初始值对符号熵的影响.数值仿真分析表明,符号熵法能定量区别不同离散混沌系统类随机性的强弱.同时作为随机源,Logistic映射比Henon映射好.     

连续混沌系统类随机性的符号熵分析法

采用符号熵分析法,分析和讨论了经典的Lorenz连续混沌系统和Rossler连续混沌系统的类随机性强弱。先将连续混沌系统产生的实数序列转化为二进制序列,然后进行编码,计算其符号熵,绘制其符号熵图,并深入讨论了系统参数和初始值对符号熵的影响。数值仿真分析表明,符号熵法能定量区别不同连续混沌系统类随机性的强弱。同时作为随机源,Lorenz混沌系统比R?ssler混沌系统好。     

Spatial context cross entropy function based multilevel image segmentation using multi-verse optimizer

Multimedia Tools and Applications - In this paper, a context-sensitive energy curve based cross-entropy method for multilevel color image segmentation is proposed. In thresholding approaches,...