一种MapReduce架构下基于遗传算法的K-Medoids聚类

由互联网时代快速发展而产生的海量数据给传统聚类方法带来了巨大挑战,如何改进聚类算法从而获取有效信息成为当前的研究热点。K-Medoids是一种常见的基于划分的聚类算法,其优点是可以有效处理孤立、噪声点,但面临着初始中心敏感、容易陷入局部最优值、处理大数据时的CPU和内存瓶颈等问题。为解决上述问题,提出了一种MapReduce架构下基于遗传算法的K-Medoids聚类。利用遗传算法的种群进化特点改进K-Medoids算法的初始中心敏感的问题,在此基础上,利用MapReduce并行遗传K-Medoids算法提高算法效率。通过带标签的数据集进行实验的结果表明,运行在Hadoop集群上的基于MapReduce和遗传算法的K-Medoids算法能有效提高聚类的质量和效率。     

改进遗传算法及其在带有目标是最小平均总流程时间的流水调度排序中的应用

提出了一个改进遗传算法的结构,并且应用于带有目标是最小平均总流程时间的流水调度排序中.为了改进一般遗传算法的程序,两个新的操作被引进到这个操作中.这两个操作为:1) 过滤操作:过滤掉在每一代中的最坏的个体,用前一代中的最好的个体替代它;2) 培育操作:当在一定代数内算法不改进时,选择一个培育操作用于培育最有希望的个体.通过大量的随机产生的问题的例子的计算机实验显示出,提出的算法的性能明显好于一般遗传算法,并且和此问题的最好的专门意义的启发式算法相匹配.新的MGA框架很容易扩展到其它最优化当中,只是实施的详细的步骤有所不同.     

基于遗传算法的计算机通信网的拓扑优化设计

1 引言设计计算机通信网的一个基本要求是网络全局有效性,即连通概率。从网络角度,连通概率指的是网络至少简单连通。其除依赖于各计算机系统和通信能力外,主要依赖于通信链路的拓扑设计。对一个给定计算机通信网的最大全局可靠性的网络拓扑优化设计,人们已提出许多启发式算法,但这些算法并未给出精确解。本文采用遗传算法进行设计,成功地解决了这类问题。     

遗传算法在钟表机芯设计中的应用

在钟表机芯设计中，齿轮参数的优化设计是一个组合优化问题，很难用传统优化方法解决.遗传算法是一种基于生物进化原理的启发式搜索方法，近年来，它成功地解决了许多计算难题.使用该算法的难点是如何将具体问题映射成适于该算法的编码以及根据编码进行各种操作.该文对传动系统各齿轮参数序号进行编码，成功地解决了齿轮参数的优化设计问题，也为一般机械设计中传动系统参数的优化提供了经验.通过比较，利用遗传算法得出的参数比用专家系统得出的参数更优.     

Ordinal Hill Climbing Algorithms for Discrete Manufacturing Process Design Optimization Problems

Thispaper introduces ordinal hill climbing algorithms for addressingdiscrete manufacturing process design optimization problems usingcomputer simulation models. Ordinal hill climbing algorithmscombine the search space reduction feature of ordinal optimizationwith the global search feature of generalized hill climbing algorithms.By iteratively applying the ordinal optimization strategy withinthe generalized hill climbing algorithm framework, the resultinghybrid algorithm can be applied to intractable discrete optimizationproblems. Computational results on an integrated blade rotormanufacturing process design problem are presented to illustratethe application of the ordinal hill climbing algorithm. The relationshipbetween ordinal hill climbing algorithms and genetic algorithmsis also discussed. This discussion provides a framework for howthe ordinal hill climbing algorithm fits into currently appliedalgorithms, as well as to introduce a bridge between the twoalgorithms.     

Physically based adaptive preconditioning for early vision

Several problems in early vision have been formulated in the past in a regularization framework. These problems, when discretized, lead to large sparse linear systems. In this paper, we present a novel physically based adaptive preconditioning technique which can be used in conjunction with a conjugate gradient algorithm to dramatically improve the speed of convergence for solving the aforementioned linear systems. A preconditioner, based on the membrane spline, or the thin plate spline, or a convex combination of the two, is termed a physically based preconditioner for obvious reasons. The adaptation of the preconditioner to an early vision problem is achieved via the explicit use of the spectral characteristics of the regularization filter in conjunction with the data. This spectral function is used to modulate the frequency characteristics of a chosen wavelet basis, and these modulated values are then used in the construction of our preconditioner. We present the preconditioner construction for three different early vision problems namely, the surface reconstruction, the shape from shading, and the optical flow computation problems. Performance of the preconditioning scheme is demonstrated via experiments on synthetic and real data sets     

Multiobjective scheduling algorithm for flexible manufacturing systems with Petri nets

In this work, we focus on general multi-objective scheduling problems that can be modeled using a Petri net framework. Due to their generality, Petri nets are a useful abstraction that captures multiple characteristics of real-life processes.To provide a general solution procedure for the abstraction, we propose three alternative approaches using an indirect scheme to represent the solution: (1) a genetic algorithm that combines two objectives through a weighted fitness function, (2) a non dominated sorting genetic algorithm (NSGA-II) that explicitly addresses the multi-objective nature of the problem and (3) a multi-objective local search approach that simultaneously explores multiple candidate solutions. These algorithms are tested in an extensive computational experiment showing the applicability of this general framework to obtain quality solutions.     

Approximative Coding Methods for Channel Representations

Most methods that address computer vision problems require powerful visual features. Many successful approaches apply techniques motivated from nonparametric statistics. The channel representation provides a framework for nonparametric distribution representation. Although early work has focused on a signal processing view of the representation, the channel representation can be interpreted in probabilistic terms, e.g., representing the distribution of local image orientation. In this paper, a variety of approximative channel-based algorithms for probabilistic problems are presented: a novel efficient algorithm for density reconstruction, a novel and efficient scheme for nonlinear gridding of densities, and finally a novel method for estimating Copula densities. The experimental results provide evidence that by relaxing the requirements for exact solutions, efficient algorithms are obtained.     

Toward designing intelligent PDEs for computer vision: An optimal control approach

Many computer vision and image processing problems can be posed as solving partial differential equations (PDEs). However, designing a PDE system usually requires high mathematical skills and good insight into the problems. In this paper, we consider designing PDEs for various problems arising in computer vision and image processing in a lazy manner: learning PDEs from training data via an optimal control approach. We first propose a general intelligent PDE system which holds the basic translational and rotational invariance rule for most vision problems. By introducing a PDE-constrained optimal control framework, it is possible to use the training data resulting from multiple ways (ground truth, results from other methods, and manual results from humans) to learn PDEs for different computer vision tasks. The proposed optimal control based training framework aims at learning a PDE-based regressor to approximate the unknown (and usually nonlinear) mapping of different vision tasks. The experimental results show that the learnt PDEs can solve different vision problems reasonably well. In particular, we can obtain PDEs not only for problems that traditional PDEs work well but also for problems that PDE-based methods have never been tried before, due to the difficulty in describing those problems in a mathematical way.     

Parallel and deterministic algorithms from MRFs: surfacereconstruction

Deterministic approximations to Markov random field (MRF) models are derived. One of the models is shown to give in a natural way the graduated nonconvexity (GNC) algorithm proposed by A. Blake and A. Zisserman (1987). This model can be applied to smooth a field preserving its discontinuities. A class of more complex models is then proposed in order to deal with a variety of vision problems. All the theoretical results are obtained in the framework of statistical mechanics and mean field techniques. A parallel, iterative algorithm to solve the deterministic equations of the two models is presented, together with some experiments on synthetic and real images     

An effective hybrid optimization strategy for job-shop scheduling problems

Simulated annealing is a naturally serial algorithm, but its behavior can be controlled by the cooling schedule. Genetic algorithm exhibits implicit parallelism and can retain useful redundant information about what is learned from previous searches by its representation in individuals in the population, but GA may lose solutions and substructures due to the disruptive effects of genetic operators and is not easy to regulate GA's convergence. By reasonably combining these two global probabilistic search algorithms, we develop a general, parallel and easily implemented hybrid optimization framework, and apply it to job-shop scheduling problems. Based on effective encoding scheme and some specific optimization operators, some benchmark job-shop scheduling problems are well solved by the hybrid optimization strategy, and the results are competitive with the best literature results. Besides the effectiveness and robustness of the hybrid strategy, the combination of different search mechanisms and structures can relax the parameter-dependence of GA and SA.Scope and purposeJob-shop scheduling problem (JSP) is one of the most well-known machine scheduling problems and one of the strongly NP-hard combinatorial optimization problems. Developing effective search methods is always an important and valuable work. The scope and purpose of this paper is to present a parallel and easily implemented hybrid optimization framework, which reasonably combines genetic algorithm with simulated annealing. Based on effective encoding scheme and some specific optimization operators, the job-shop scheduling problems are well solved by the hybrid optimization strategy.     

An LMI approach to control-oriented identification and model (In) validation of LPV systems

This note proposes a control-oriented identification framework for a class of linear parameter varying systems that takes into account both the dependence of part of the model on time-varying parameters as well as the possible existence of a nonparametric component. The main results of the note show that the problems of obtaining and validating a model for these systems can be recast as linear matrix inequality feasibility problems. Moreover, as the information is completed, the algorithm is shown to converge in the l/sub 2/-induced topology to the actual plant. Additional results include deterministic bounds on the identification error. These results are illustrated with a practical example arising in the context of active vision.     

Bilinear modeling via augmented Lagrange multipliers (BALM)

This paper presents a unified approach to solve different bilinear factorization problems in computer vision in the presence of missing data in the measurements. The problem is formulated as a constrained optimization where one of the factors must lie on a specific manifold. To achieve this, we introduce an equivalent reformulation of the bilinear factorization problem that decouples the core bilinear aspect from the manifold specificity. We then tackle the resulting constrained optimization problem via Augmented Lagrange Multipliers. The strength and the novelty of our approach is that this framework can seamlessly handle different computer vision problems. The algorithm is such that only a projector onto the manifold constraint is needed. We present experiments and results for some popular factorization problems in computer vision such as rigid, non-rigid, and articulated Structure from Motion, photometric stereo, and 2D-3D non-rigid registration.     

基于图像显著性检测的图像分割

图像分割在许多图像处理和机器视觉问题中是一个非常重要的过程,是将一幅图分割成几个显著的区域,然而不能将其中最显著的目标直接分割出来,需要进一步处理。为此本文采用显著性检测的算法实现了对目标的分割。显著性区域检测可以应用于目标检测、图像检索、图像分割等机器视觉问题。使用杨等人提出的基于图论的流形排序算法检测显著性算法得到显著性图,再结合mean-shift分割算法,实现了对视觉显著性目标分割提取,可获得可观的图像分割结果,并将此算法应用到了森林火灾检测中,能对图像中的火焰部分进行有效的分割提取。     

文化遗传算法的研究及其在函数优化中的应用

为了提高遗传算法的性能,将遗传算法纳入到文化算法框架中组成群体空间和信念空间,提出一种新的优化算法。在群体空间的遗传进化过程中引入随机种群来增加算法的勘探能力,并组织较差个体依概率与信念空间中更新后的优秀个体进行交叉操作;在信念空间充分利用对优秀个体所包含信息的开采能力并采用耗散结构来提高整个空间的自组织能力,更新优秀个体,在很大程度上提高了算法的速度和效率。实验结果表明,新算法能有效地应用于函数优化。     

A smart surface inspection system using faster R-CNN in cloud-edge computing environment

Automated surface inspection has become a hot topic with the rapid development of machine vision technologies. Traditional machine vision methods need experts to carefully craft image features for defect detection. This limits their applications to wider areas. The emerging convolutional neural networks (CNN) can automatically extract features and yield good results in many cases. However, the CNN-based image classification methods are more suitable for flat surface texture inspection. It is difficult to accurately locate small defects in geometrically complex products. Furthermore, the computational power required in CNN algorithms is usually high and it is not efficient to be implemented on embedded hardware. To solve these problems, a smart surface inspection system is proposed using faster R-CNN algorithm in the cloud-edge computing environment. The faster R-CNN as a CNN-based object detection method can efficiently identify defects in complex product images and the cloud-edge computing framework can provide fast computation speed and evolving algorithm models. A real industrial case study is presented to illustrate the effectiveness of the proposed method. The results show that the proposed method can provide high detection accuracy within a short time.     

Genetic process mining: an experimental evaluation

One of the aims of process mining is to retrieve a process model from an event log. The discovered models can be used as objective starting points during the deployment of process-aware information systems (Dumas et al., eds., Process-Aware Information Systems: Bridging People and Software Through Process Technology. Wiley, New York, 2005) and/or as a feedback mechanism to check prescribed models against enacted ones. However, current techniques have problems when mining processes that contain non-trivial constructs and/or when dealing with the presence of noise in the logs. Most of the problems happen because many current techniques are based on local information in the event log. To overcome these problems, we try to use genetic algorithms to mine process models. The main motivation is to benefit from the global search performed by this kind of algorithms. The non-trivial constructs are tackled by choosing an internal representation that supports them. The problem of noise is naturally tackled by the genetic algorithm because, per definition, these algorithms are robust to noise. The main challenge in a genetic approach is the definition of a good fitness measure because it guides the global search performed by the genetic algorithm. This paper explains how the genetic algorithm works. Experiments with synthetic and real-life logs show that the fitness measure indeed leads to the mining of process models that are complete (can reproduce all the behavior in the log) and precise (do not allow for extra behavior that cannot be derived from the event log). The genetic algorithm is implemented as a plug-in in the ProM framework.     

Empirical modelling of genetic algorithms.

This paper addresses the problem of reliably setting genetic algorithm parameters for consistent labelling problems. Genetic algorithm parameters are notoriously difficult to determine. This paper proposes a robust empirical framework, based on the analysis of factorial experiments. The use of a graeco-latin square permits an initial study of a wide range of parameter settings. This is followed by fully crossed factorial experiments with narrower ranges, which allow detailed analysis by logistic regression. The empirical models derived can be used to determine optimal algorithm parameters and to shed light on interactions between the parameters and their relative importance. Refined models are produced, which are shown to be robust under extrapolation to up to triple the problem size.     

Memetic算法在智能组卷问题中的应用

Memetic算法是一种启发式搜索方法,常用于解决一些NP问题。本文通过对遗传Memetic算法的改进与优化,结合智能组卷问题的特点,提出一套完整的解决方案。算法使用Memetic算法框架,全局搜索策略采用分段实数编码的遗传算法,融合了算法的交叉变异操作,局部搜索策略采用模拟退火算法,有效解决陷入局部最优问题。通过不同算法的对比实验表明,本文提出的Memetic算法能够快速高效地解决智能组卷问题,大大提升试卷生成质量,减少迭代次数,可快速获得最优解。      

双目视觉测量系统摄像机外部参数标定研究

针对双目立体视觉测量系统中摄像机标定问题,讨论了基于标准长度的外部参数标定方法,选定了摄像机透视投影模型,采用双摄像机同时对放置于视场内的十字靶标拍摄多幅图像,得出了基于LabVIEW开发的摄像机标定方法.该方法利用了LabVIEW的开发环境,使用了数学工具包,将遗传算法与LM算法相结合,优化迭代获得摄像机外部参数,运算速度和精度大大提高.开发的模块可用于基于LabVIEW开发的工程软件进行高精度尺寸现场测量.在双目立体视觉测量系统标定结果基础上对标准靶进行测量,测量结果标准差达到0.1.