最短路径模型下的双目立体匹配算法研究

传统的双目立体匹配算法,是通过计算像素点间的相似程度来找出左图像素点和右图像素点的匹配关系。为了提高匹配准确度,当前策略主要是将立体匹配转化为求解能量方程最小化问题,再对全局空间的能量进行优化,如扫描线算法、动态规划算法、图割算法和置信传播算法。然而各个算法有着自身不足,若仅仅从原有的模型出发,难以克服缺点。通过对能量方程最小化问题深入研究,建立了一个最短路径模型,即将能量方程映射到有向图中,通过求解图的最短路径来解能量方程的最小化问题,详细阐述了算法原理后又从视差空间的角度描述了算法的运行图。实验证明最短路径算法克服了上述四种方法的固有缺陷,在准确度较高的同时,有较低的时间复杂度。     

Hopfield网络在视差空间上的立体匹配求解

由于边界区域的匹配精度是立体匹配问题的瓶颈,这里采用一种基于特征的匹配算法来重点研究场景中边界区域的匹配.首先针对立体匹配问题,提出一种基于RBF的边界提取算法,使得边界区域成为待匹配的像素点.研究像素点匹配需要满足的约束,构建相应的能量方程,接着采用Hopfield网络对能量函数进行优化来获得问题的求解.由于针对的是整个边界区域,直接将特征点输入网络会导致神经元数目过多、复杂度过高.为了降低算法复杂度,提出从视差空间上来构造网络模型.最后通过大量实验来验证算法的性能,包括标准图片、噪声图片与真实的场景图片.实验证明新算法能大大提高边界区域精度,克服了立体匹配的瓶颈,明显提高了整体区域精度,算法有很强的鲁棒性和实用性,即使在复杂情况下也能取得较好的效果.     

基于参数方程处理等式约束优化的粒子群算法

针对目前已有的粒子群优化算法求解有等式约束优化问题时对收敛速度和解的精度的影响,提出了一种新的基于参数方程的粒子群优化算法.它是粒子群在初始化和选代进化过程中使用求解参数方程的方法处理等式约束设计出的粒子群优化算法.数值实验结果表明,新算法是有效的.它不仅提高了收敛速度和解的精度,而且是一种通用的智能算法.     

求解互补问题的极大熵社会认知算法

针对传统算法无法获得互补问题的多个最优解的困难,提出了求解互补问题的社会认知优化算法.通过利用NCP函数,将互补问题的求解转化为一个非光滑方程组问题,然后用凝聚函数对其进行光滑化,进而把互补问题的求解转化为无约束优化问题,利用社会认知算法对其进行求解.该算法是基于社会认知理论,通过一系列的学习代理来模拟人类的社会性以及智能性从而完成对目标的优化.该算法对目标函数的解析性质没有要求且容易实现,数值实验结果表明了该方法是有效的.     

基于SQL的图相似性查询方法

图作为一种表示复杂信息的数据结构,被广泛应用于社交网络,知识图谱,语义网,生物信息学和化学信息学等领域.随着各领域应用的普及和深入开展,如何管理这些复杂图数据是目前图数据库技术面临的巨大挑战.图的相似性查询是图数据管理中的热点问题之一.对图查询问题的研究主要包括图的相似性查询等.本文重点研究基于编辑距离（Graph Edit Distance）的图相似性查询处理问题.首先,通过对目前代表性的问题求解算法分析发现,其提出的过滤规则都具有自己的优缺点和适用性.其次,针对已有方法在过滤阶段自身存在优缺点和适用性的问题,提出一种全新的面向关系型数据库的过滤框架,新的过滤框架可以支持所有已有的过滤规则,从而通过结合不同的过滤规则来优化图相似查询算法以提高查询效率.该方法可以最大程度保留不同过滤规则的优点并克服其缺点,从而对不同查询具有普遍适用性.最后,基于PubChem数据集,通过比较算法在求解查询结果的时间消耗,验证本文提出算法的高效性及可扩展性,实验结果表明,本文提出的方法优于现有算法.     

求解一类不可微多目标优化问题的社会认知算法*

针对一类不可微多目标优化问题,给出了一个新的算法——极大熵社会认知算法。利用极大熵方法将带有约束的不可微多目标优化问题转化为无约束单目标优化问题,然后利用社会认知算法对其进行求解。该算法是基于社会认知理论,通过一系列的学习代理来模拟人类的社会性和智能性从而完成对目标的优化。利用两个测试算例对其进行测试并与其他算法进行比较,计算结果表明,该算法在求解的准确性和有效性方面均优于其他算法。     

基于改进萤火虫群的区域灾害链挖掘方法

通过建立灾害立体网络模型并定义相似空间向量来对区域灾害链规律进行挖掘,同时转化其中的向量发现问题为一种多峰路径优化问题从而利用萤火虫群算法进行求解,并添加变步长、组亮度控制等优化策略,以改善基本GSO算法在收敛速度及求解精度上的不足,最后通过与基本GSO算法的性能对比实验证明了该改进方法的优越性.     

基于决策图贝叶斯优化进化算法的图K-划分算法

图K-划分问题是一种组合优化问题,可以归结为NP难题.针对该问题本文提出了一种基于决策图贝叶斯优化算法(Bayesian Optimization Algorithm with Decision Graphs,简称DBOA)的图K-划分,该算法利用新的编码和解码方法以及适当的适应度函数来求解图K-划分问题.仿真结果表明了该算法的可行性和有效性.     

基于特征分解的快速位姿图优化算法

位姿图优化(pose graph optimization, PGO)是计算机视觉领域中广泛应用的高维非凸优化算法,很难直接求解,主要依赖于迭代技术,对初始值的质量要求较高,在实践中很难得到保证。针对位姿图优化问题进行了研究,提出了基于特征分解的位姿图简单封闭解算法,该算法首先对PGO问题的最大似然估计进行半定松弛,然后将其转换为特征分解问题,并利用数据的稀疏性设计了改进的模型降阶方法进行求解,进一步提高了算法的计算速度。算法具有可伸缩性、计算成本低和精度高等优点。最后,在模拟和真实的位姿图数据集上进行实验评估,结果表明在不影响精度的情况下,该算法可以快速地进行位姿图优化。     

基于离散数字编码的蚁群连续优化算法

本文提出了一种基于离散编码的蚁群连续优化算法(CACO-DE),用于求解连续优化问题.以往蚁群算法(AC0)的研究,以求解离散优化问题为主,较少涉及连续优化问题.与经典的ACO算法不同,CACO-DE将有限精度的实数转化为一个数字串,数字串的每位取0到9之间的数字,从而实现了用离散编码描述实数的效果.CACO-DE延用了经典ACO算法的框架,并加入了特殊的选择机制、信息素更新方式和局部搜索策略.测试实验结果表明:CA-CO-DE比以往同类算法求解速度更快且精度更高.     

混沌优化算法的性能分析

现代优化算法主要解决全局最优问题，其本质是概率性的．借鉴多种自然现象，人们提出了许多仿生、仿物算法，如禁忌搜索算法（TABU）、模拟退火（SAA）、遗传算法（GA）、进化策略（ES）、蚁群算法（ACA）等．利用混沌的遍历性进行优化搜索就是一种很有趣的研究思路，尤其对于虫口方程人们进行了许多研究，取得了一定的研究成果．但和普通的随机搜索算法相比，其性能之不足也很明显，主要体现在：混沌的遍历性不均匀，在边界处搜索密度高，远不如随机Monte Carlo搜索方法．这就从本质上决定了其搜索性能在普适性上与Monte Carlo算法有差距．仿真计算证实了这个结论．因此对于利用虫口方程进行的混沌优化研究需要谨慎采用．     

基于GMOGSO的多目标流水车间调度问题

针对缓冲区有限的多目标流水车间调度问题, 提出一种基于Pareto 最优的广义多目标萤火虫算法. 通过引入交换子和交换序将基本萤火虫算法离散化, 并将算法拓展为全局搜索过程和局部搜索过程. 进化初期采用全局搜索将种群推向较优区域, 进化中后期采用捕食搜索策略使算法主体在全局搜索和局部搜索间智能切换, 从而保证全局与局部的平衡. 动态变步长策略进一步增强了算法搜索能力. 通过算例测试验证了所提出算法的有效性.

     

A whale optimization algorithm based on quadratic interpolation for high-dimensional global optimization problems

Whale Optimization Algorithm (WOA), as a new population-based optimization algorithm, performs well in solving optimization problems. However, when tackling high-dimensional global optimization problems, WOA tends to fall into local optimal solutions and has slow convergence rate and low solution accuracy. To address these problems, a whale optimization algorithm based on quadratic interpolation (QIWOA) is presented. On the one hand, a modified exploration process by introducing a new parameter is proposed to efficiently search the regions and deal with the premature convergence problem. On the other hand, quadratic interpolation around the best search agent helps QIWOA to improve the exploitation ability and the solution accuracy. Moreover, the algorithm tries to make a balance between exploitation and exploration. QIWOA is compared with several state-of-the-art algorithms on 30 high-dimensional benchmark functions with dimensions ranging from 100 to 2000. The experimental results show that QIWOA has faster convergence rate and higher solution accuracy than both WOA and other population-based algorithms. For functions with a flat or sharp bottom, QIWOA is difficult to find the global optimum, but it still performs best compared with other algorithms.     

具有混合群智能行为的萤火虫群优化算法研究

萤火虫群优化算法是一种新型的群智能优化算法,基本的萤火虫群优化算法存在收敛精度低等问题。为了提高算法的性能,借鉴蜂群和鸟群的群体智能行为,改进萤火虫群优化算法的移动策略。运用均匀设计调整改进算法的参数取值。若干经典测试问题的实验仿真结果表明,引入混合智能行为大幅提升了算法的优化性能。     

Accelerated genetic algorithm based on search-space decomposition for change detection in remote sensing images

Detecting change areas among two or more remote sensing images is a key technique in remote sensing. It usually consists of generating and analyzing a difference image thus to produce a change map. Analyzing the difference image to obtain the change map is essentially a binary classification problem, and can be solved by optimization algorithms. This paper proposes an accelerated genetic algorithm based on search-space decomposition (SD-aGA) for change detection in remote sensing images. Firstly, the BM3D algorithm is used to preprocess the remote sensing image to enhance useful information and suppress noises. The difference image is then obtained using the logarithmic ratio method. Secondly, after saliency detection, fuzzy c-means algorithm is conducted on the salient region detected in the difference image to identify the changed, unchanged and undetermined pixels. Only those undetermined pixels are considered by the optimization algorithm, which reduces the search space significantly. Inspired by the idea of the divide-and-conquer strategy, the difference image is decomposed into sub-blocks with a method similar to down-sampling, where only those undetermined pixels are analyzed and optimized by SD-aGA in parallel. The category labels of the undetermined pixels in each sub-block are optimized according to an improved objective function with neighborhood information. Finally the decision results of the category labels of all the pixels in the sub-blocks are remapped to their original positions in the difference image and then merged globally. Decision fusion is conducted on each pixel based on the decision results in the local neighborhood to produce the final change map. The proposed method is tested on six diverse remote sensing image benchmark datasets and compared against six state-of-the-art methods. Segmentations on the synthetic image and natural image corrupted by different noise are also carried out for comparison. Results demonstrate the excellent performance of the proposed SD-aGA on handling noises and detecting the changed areas accurately. In particular, compared with the traditional genetic algorithm, SD-aGA can obtain a much higher degree of detection accuracy with much less computational time.     

The improvement of glowworm swarm optimization for continuous optimization problems

Glowworm swarm optimization (GSO) algorithm is the one of the newest nature inspired heuristics for optimization problems. In order to enhances accuracy and convergence rate of the GSO, two strategies about the movement phase of GSO are proposed. One is the greedy acceptance criteria for the glowworms update their position one-dimension by one-dimension. The other is the new movement formulas which are inspired by artificial bee colony algorithm (ABC) and particle swarm optimization (PSO). To compare and analyze the performance of our proposed improvement GSO, a number of experiments are carried out on a set of well-known benchmark global optimization problems. The effects of the parameters about the improvement algorithms are discussed by uniform design experiment. Numerical results reveal that the proposed algorithms can find better solutions when compared to classical GSO and other heuristic algorithms and are powerful search algorithms for various global optimization problems.     

A new gradient based particle swarm optimization algorithm for accurate computation of global minimum

Stochastic optimization algorithms like genetic algorithms (GAs) and particle swarm optimization (PSO) algorithms perform global optimization but waste computational effort by doing a random search. On the other hand deterministic algorithms like gradient descent converge rapidly but may get stuck in local minima of multimodal functions. Thus, an approach that combines the strengths of stochastic and deterministic optimization schemes but avoids their weaknesses is of interest. This paper presents a new hybrid optimization algorithm that combines the PSO algorithm and gradient-based local search algorithms to achieve faster convergence and better accuracy of final solution without getting trapped in local minima. In the new gradient-based PSO algorithm, referred to as the GPSO algorithm, the PSO algorithm is used for global exploration and a gradient based scheme is used for accurate local exploration. The global minimum is located by a process of finding progressively better local minima. The GPSO algorithm avoids the use of inertial weights and constriction coefficients which can cause the PSO algorithm to converge to a local minimum if improperly chosen. The De Jong test suite of benchmark optimization problems was used to test the new algorithm and facilitate comparison with the classical PSO algorithm. The GPSO algorithm is compared to four different refinements of the PSO algorithm from the literature and shown to converge faster to a significantly more accurate final solution for a variety of benchmark test functions.     

Stereo matching using weighted dynamic programming on a single-direction four-connected tree

In recent years, stereo matching based on dynamic programming (DP) has been widely studied and various tree structures are proposed to improve the matching accuracy. However, previous DP-based algorithms do not incorporate all the smoothness functions determined by the edges between the adjacent pixels in the image, which will usually lead to lower matching accuracies. In this paper, we propose a novel stereo matching algorithm based on weighted dynamic programming on a single-direction four-connected (SDFC) tree. The SDFC tree structure is a new tree structure which includes all the edges in the image and the disparity of a pixel can be affected by all the edges in the image. However, in the SDFC tree, conventional DP-based algorithms will make the pixels that are far away from the root node provide higher energy than the nearby pixels, which will decrease the matching accuracy. So, the weighted dynamic programming approach is proposed to optimize the energy function on the new tree structure, and all the pixels in the SDFC tree are treated equivalently. Dynamic programming in the SDFC tree of every pixel in the image separately is very time-consuming, so a fast DP optimization method is designed for the SDFC tree, which reduces the computational complexity of the proposed weighted DP algorithm to 12 times of conventional DP based algorithm. Experiments show that our algorithm not only produces quite smooth and reasonable disparity maps which are close to the state-of-the-art results, but also can be implemented quite efficiently. Performance evaluations on the Middlebury data set show that our method ranks top in all the DP-based stereo matching algorithms, even better than the algorithms that apply segmentation techniques. Experimental results in an unmanned ground vehicle (UGV) test bed show that our algorithm gets very good matching results in different outdoor conditions, even on the asphaltic road which is considered to be textureless. This illustrates the robustness of our algorithm.     

An Artificial Bee Colony algorithm with guide of global & local optima and asynchronous scaling factors for numerical optimization

Artificial Bee Colony (ABC) algorithm is a wildly used optimization algorithm. However, ABC is excellent in exploration but poor in exploitation. To improve the convergence performance of ABC and establish a better searching mechanism for the global optimum, an improved ABC algorithm is proposed in this paper. Firstly, the proposed algorithm integrates the information of previous best solution into the search equation for employed bees and global best solution into the update equation for onlooker bees to improve the exploitation. Secondly, for a better balance between the exploration and exploitation of search, an S-type adaptive scaling factors are introduced in employed bees’ search equation. Furthermore, the searching policy of scout bees is modified. The scout bees need update food source in each cycle in order to increase diversity and stochasticity of the bees and mitigate stagnation problem. Finally, the improved algorithms is compared with other two improved ABCs and three recent algorithms on a set of classical benchmark functions. The experimental results show that the our proposed algorithm is effective and robust and outperform than other algorithms.