共查询到19条相似文献,搜索用时 62 毫秒
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对黏钢加固结构黏接层缺陷对超声检测信号的影响进行了深入研究,并提出了一种基于机器学习的黏接层缺陷识别的新型方法.首先,该文基于直接接触式的脉冲回波反射法对黏钢构件进行有限元模拟,并阐述了超声波在黏钢构件中的传播规律;其次,通过分析局部段超声回波信号及相关信号特征,讨论了不同缺陷变量对超声回波信号的影响规律;最后,建立了黏钢构件超声时程响应数据集,并对比了不同机器学习模型对缺陷大小、位置的分类识别性能,形成了黏钢构件黏接层缺陷识别方法.结果表明,局部段超声回波信号及其特征随着缺陷大小、位置的改变呈规律性变化,能够对缺陷信息进行初步区分.同时,该文提出的基于RF模型的黏钢构件黏接层缺陷识别方法能够有效识别黏钢构件黏接层缺陷,具有较广阔的工程应用前景. 相似文献
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林茂森林锐洪灵悦肖永豪 《数学建模及其应用》2020,(4):85-93
针对电力巡检中由于无人机航拍绝缘子图像尺寸大,导致小目标检测难的问题,提出一种结合滑动窗口和主流神经网络的改进算法,对大尺寸图像中绝缘子串珠的分割以及缺陷区域的定位进行研究.在绝缘子串珠分割问题上,采用滑动窗口结合Mask R-CNN神经网络算法进行图像分割;在绝缘子缺陷检测问题上,结合滑动窗口和非极大值抑制算法对Yolo-v4神经网络进行改进,提高绝缘子缺陷区域小目标检测的精度.实验结果表明,分割所得绝缘子串珠掩膜图与标准掩膜图的相似度(Dice系数)为85.68%,与人工标记的绝缘子区域相比达到更高的相似度,绝缘子缺陷定位的平均精度均值(mean AP)为94.88%,与真实数据相比,平均重叠度为86.93%. 相似文献
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在电子屏幕的生产中,缺陷检测是生产线中重要一环.目前很多生产线仍然通过人工观察的方式,其结果依赖人工经验而不稳定,且生产成本高,因而人工检测需通过机器智能技术替换.针对工业生产中要求简单可靠、准确实时,且需快速应用于新生产线的特点,文章设计了一种基于图像处理的屏幕缺陷检测算法.基于新的边缘检测算法,通过比较正常区域与有... 相似文献
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基于网络商盟的信任交易管理机制研究 总被引:1,自引:0,他引:1
如何建立有效的信任交易管理机制是网络交易信任管理中的一个重要问题。在分析现有网络信任交易机制局限性的基础上,根据网络交易信任问题的特点和现实社会中商业联盟的特性,提出一种基于网络商盟的信任交易管理机制,建立事前防范,事中协调,事后惩罚三位一体的欺诈约束机制,保障网络交易的安全性。本研究有效解决三方面问题:1)解决新注册用户难以开展业务的问题;2)有效防止会员通过变换身份进行欺诈;3)降低网络交易平台仲裁的工作量。采用博弈理论分析该机制下的交易方行为,可以证明诚信交易是长期博弈的子博弈完美纳什均衡策略。 相似文献
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《数学的实践与认识》2013,(20)
随着互联网的飞速发展,互联网用户和应用都在快速增长,对于网络服务质量的要求也越来越高,拥塞控制已经成为一个十分重要的问题.基于网络效用最大化的模型研究了多路径网络的拥塞控制问题,将此问题建模为基于用户发送速率的凸规划问题,基于对偶分解得到了分布式的求解方法,仿真结果验证了算法的收敛性.研究内容对多路径的TCP开发具有一定的参考意义. 相似文献
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针对传统板形模式识别方法存在精度低、鲁棒性弱的问题,提出了一种混合优化RBF-BP组合神经网络板形模式识别方法。首先利用自组织映射网络(SOM)对样本聚类,利用聚类后的网络拓扑结构确定RBF的中心,并计算RBF的宽度,克服了传统聚类算法随机选取中心导致聚类结果不稳定的问题。然后利用遗传算法(GA)良好的全局搜索能力优化整个网络的权值。RBF-BP组合神经网络是由一个RBF子网和一BP子网串联构成的,该网络同时具备BP神经网络能较好地预测未知样本的能力以及RBF神经网络的逼近速度快的优点。并以某900HC可逆冷轧机板形识别为应用背景,在MATLAB2010a环境下进行仿真实验,结果表明混合优化RBF-BP组合神经网络的板形模式识别方法能够识别出常见的板形缺陷,提高了板形缺陷识别精度并具有较好的鲁棒性,可以满足板带轧机高精度的板形控制要求。 相似文献
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基于交互耦合网络的项目组合决策模型研究 总被引:1,自引:0,他引:1
随着项目活动进入“大尺度”时代,复杂性成为现代化项目组合管理中的突出问题。在项目组合决策系统复杂性分析基础上,提出了交互耦合网络视角下的项目组合决策系统表征方法;借鉴非线性动力学建模方法构建项目组合决策系统复杂动力网络模型,结合模型的稳定解和稳定条件将项目组合决策系统划分为竞争型、共生型、强依存型和弱依存型,并通过数值仿真方法对系统的稳定域、分岔和混沌进行分析。研究表明,项目组合决策系统的复杂性和稳定性依赖于系统内交互关系作用,改善协作关系,避免过分竞争,以系统整体为先优化配置有利于项目组合目标实现。 相似文献
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A laser ultrasonic method for nondestructive evaluation of the structure of composite materials is proposed. Specimens of graphite-epoxy composites with compaction-type defects and air cavities are investigated. The method is based on the laser thermooptical generation of wide-band acoustic pulses - optoacoustic (OA) signals - in the material investigated. The acoustic pulses backscattered by structural ingomogeneities and defects are registered by a wide-band piezotransducer, which makes it possible to detect acoustic pulses in the frequency range from 0.1 to 30 MHz. Since the generation and detection of acoustic pulses takes place on the front surface of the specimen, this method allows us to carry out nondestructive evaluation with one-sided access to the object under study. The spectral and correlation analyses of backscattered OA signals are used for mathematical processing of the experimental data. The method developed makes it possible to determine the type of defects and the depth of their location. 相似文献
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通过对某武器系统软件测试所得缺陷数据与软件规模之间关系的分析,建立了基于软件测试的软件缺陷预测模型.通过本项研究,可以在武器系统软件研制的初期阶段对软件可能含有的缺陷数量和缺陷等级进行预测,为软件研制过程的质量保证活动策划提供依据. 相似文献
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针对一类具有不确定性扰动的非线性系统,将设计的系统线性观测器产生的误差信号作为残差,采用一种具有高斯型激励函数的动态神经网络(DNN)对残差信号进行分析处理,得到了系统的鲁棒故障检测方法.文中分析了该方法的稳定性和故障检测的鲁棒性,并通过算例验证了该方法的有效性. 相似文献
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随着竞争的日趋激烈,越来越多的服务商采用质量保证策略作为竞争手段以吸引顾客,然而现有研究缺乏对该策略下的质量缺陷补偿问题的深入分析。鉴于此,本文系统地分析了质量保证策略下服务商的质量缺陷补偿问题:首先分析了当服务价格外生时,服务商的最优质量缺陷补偿决策;然后分别探讨在服务价格内生变化和服务供给变动的影响下,服务商的最优质量缺陷补偿;最后,通过数值分析,探寻在服务价格和服务供给的双重变动影响下,服务商的最优质量缺陷补偿。本文拓展了服务质量的研究,对于指导服务型企业如何制定质量缺陷补偿具有较强的实践启示意义。 相似文献
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In software defect prediction with a regression model, too many metrics extracted from static code and aggregated (sum, avg, max, min) from methods into classes can be candidate features, and the classical feature selection methods, such as AIC, BIC, should be processed at a given model. As a result, the selected feature sets are significantly different for various models without a reasonable interpretation. Maximal information coefficient (MIC) presented by Reshef et al.\ucite{4} is a novel method to measure the degree of the interdependence between two continuous variables, and an available computing method is also given based on the observations. This paper firstly use the MIC between defect counts and each feature to select features, and then conduct the power transformation on the selected features, and finally build up the principal component Poisson and negative binomial regression model. All experiments are conducted on KC1 data set in NASA repository on the level of class. The block-regularized $m\times 2$ cross-validated sequential $t$-test is employed to test the difference of performance of two models. The performance measures of a model in this paper are FPA, AAE, ARE. The experimental results show that
1) the aggregated features, such as sum, avg, max, are selected by MIC except min, which are significantly different from AIC, BIC; 2) the power transformation
to the features can improve the performance for majority of models; 3) after PCA and factorial analysis, two clear factors are obtained in the model. One
corresponds to the aggregated features via avg and max, and the other corresponds to the aggregated features with sum. Therefore, the model owns a reasonable interpretation. Conclusively, the aggregated features with sum, avg, max are significantly effective for software defect prediction, and the regression
model based on the selected features by MIC has some advantages. 相似文献
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We consider a defect-correction method that combines a first-order upwinded difference scheme with a second-order central difference scheme for a model singularly perturbed convection–diffusion problem in one dimension on a class of Shishkin-type meshes. The method is shown to be convergent, uniformly in the diffusion parameter , of second order in the discrete maximum norm. As a corollary we derive error bounds for the gradient approximation of the upwind scheme. Numerical experiments support our theoretical results. 相似文献
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We propose a sequential importance sampling strategy to estimate subgraph frequencies and detect network motifs. The method is developed by sampling subgraphs sequentially node by node using a carefully chosen proposal distribution. Viewing the subgraphs as rooted trees, we propose a recursive formula that approximates the number of subgraphs containing a particular node or set of nodes. The proposal used to sample nodes is proportional to this estimated number of subgraphs. The method generates subgraphs from a distribution close to uniform, and performs better than competing methods. We apply the method to four real-world networks and demonstrate outstanding performance in practical examples. Supplemental materials for the article are available online. 相似文献