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基于Matrix Profile的时间序列分割技术改进
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作者 刘贺贺 贺延俏 +2 位作者 邓诗卓 吴刚 王波涛 《软件学报》 EI CSCD 北大核心 2023年第11期5267-5281,共15页
时间序列分割是数据挖掘领域中的一个重要研究方向.目前基于矩阵轮廓(matrix profile,MP)的时间序列分割技术得到了越来越多研究人员的关注,并且取得了不错的研究成果.不过该技术及其衍生算法仍然存在不足:首先,基于矩阵轮廓的快速低代... 时间序列分割是数据挖掘领域中的一个重要研究方向.目前基于矩阵轮廓(matrix profile,MP)的时间序列分割技术得到了越来越多研究人员的关注,并且取得了不错的研究成果.不过该技术及其衍生算法仍然存在不足:首先,基于矩阵轮廓的快速低代价语义分割算法中对给定活动状态的时间序列分割时,最近邻之间通过弧进行连接,会出现弧跨越非目标活动状态匹配相似子序列问题;其次,现有提取分割点算法在提取分割点时采用给定长度窗口,容易得到与真实值偏差较大的分割点,降低准确性.针对以上问题,提出一种限制弧跨越的时间序列分割算法(limit arc curve cross-FLOSS,LAC-FLOSS),该算法给弧添加权重,形成一种带权弧,并通过设置匹配距离阈值解决弧的跨状态子序列误匹配问题.此外,提出一种改进的提取分割点算法(improved extract regimes,IER),它通过纠正弧跨越(corrected arc crossings,CAC)序列的形状特性,从波谷中提取极值,避免直接使用窗口在非拐点处取到分割点的问题.在公开数据集datasets_seg和MobiAct上面进行对比实验,验证以上两种解决方案的可行性和有效性. 展开更多
关键词 活动分割 可穿戴传感器 矩阵轮廓 带权弧
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基于活动轮廓结合目标匹配遥感图像识别算法 被引量:1
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作者 张勇 《军民两用技术与产品》 2017年第2期67-68,共2页
随着当今遥感技术的飞速发展,遥感图像的精度和复杂度越来越高,为了从复杂大量的遥感图像中识别出感兴趣的目标区域,本文提出了活动轮廓分割结合目标匹配的遥感图像识别算法.所提出的活动轮廓算法,基于一个区域外法线向量的演化曲线模型... 随着当今遥感技术的飞速发展,遥感图像的精度和复杂度越来越高,为了从复杂大量的遥感图像中识别出感兴趣的目标区域,本文提出了活动轮廓分割结合目标匹配的遥感图像识别算法.所提出的活动轮廓算法,基于一个区域外法线向量的演化曲线模型,改善了原始的轮廓模型的边缘泄露问题和运算速率.新设计的模型用来提取目标匹配所需要的模板区域,并对其进行填充来构造完整模板.之后通过具有方向不变性的圆投影算法来进行目标区域的匹配进行筛选,并进一步对筛选出来的区域通过具有良好的几何区域不变性的仿射不变矩对目标区域进行分析,从而得出最终所判断的目标区域.最后通过实验验证了所设计的算法具有计算速率快,初始化限定少,演化能力强和鲁棒性强的特点.本算法适用于多种刚性目标的遥感图像识别. 展开更多
关键词 遥感图像 目标识别 活动轮廓分割 圆投影匹配 仿射不变矩
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基于CSJMM-AS-GAC的马陆葡萄病虫害识别研究 被引量:2
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作者 王兴旺 郑汉垣 王素青 《河南农业科学》 北大核心 2022年第6期154-163,共10页
为了提高马陆葡萄病虫害的识别准确率,有效地进行马陆葡萄病虫害防控,对测地线活动轮廓模型(GAC)进行改进,通过引入动态系数函数将马陆葡萄病虫害图像边界区域与非边界区域进行精确划分,从而实现准确分割病虫害图像模糊和凹陷边界,提出... 为了提高马陆葡萄病虫害的识别准确率,有效地进行马陆葡萄病虫害防控,对测地线活动轮廓模型(GAC)进行改进,通过引入动态系数函数将马陆葡萄病虫害图像边界区域与非边界区域进行精确划分,从而实现准确分割病虫害图像模糊和凹陷边界,提出并建立了精确分割测地线活动轮廓模型(ASGAC)。接下来为了克服复杂背景下训练样本不足造成的误差,提出了Core损失函数,建立了CoreSoftmax联合监督机制(CSJMM),从而确立了基于CSJMM的精确分割测地线活动轮廓模型(CSJMM-ASGAC)。结果表明,CSJMM-AS-GAC训练集初始准确率为65.46%,验证集准确率为95.67%,测试集准确率为93.95%,Kappa系数达到0.913 8,召回率达到89.21%,CSJMM-AS-GAC对于马陆葡萄病虫害识别准确率达到94.06%。CSJMM-AS-GAC的整体性能、识别准确率、召回率等指标都优于常用的病虫害识别模型。 展开更多
关键词 马陆葡萄 病虫害识别 损失函数 分割 测地线活动轮廓模型 精确分割测地线活动轮廓模型 召回率
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Fast Texture Segmentation Based on Semi-Local Region Descriptor and Active Contour 被引量:10
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作者 Nawal Houhou Jean-Philippe Thiran Xavier Bresson 《Numerical Mathematics(Theory,Methods and Applications)》 SCIE 2009年第4期445-468,共24页
In this paper, we present an efficient approach for unsupervised segmentation of natural and textural images based on the extraction of image features and a fast active contour segmentation model. We address the probl... In this paper, we present an efficient approach for unsupervised segmentation of natural and textural images based on the extraction of image features and a fast active contour segmentation model. We address the problem of textures where neither the gray-level information nor the boundary information is adequate for object extraction. This is often the case of natural images composed of both homogeneous and textured regions. Because these images cannot be in general directly processed by the gray-level information, we propose a new texture descriptor which intrinsically defines the geometry of textures using semi-local image information and tools from differential geometry. Then, we use the popular Kullback-Leibler distance to design an active contour model which distinguishes the background and textures of interest. The existence of a minimizing solution to the proposed segmentation model is proven. Finally, a texture segmentation algorithm based on the Split-Bregrnan method is introduced to extract meaningful objects in a fast way. Promising synthetic and real-world results for gray-scale and color images are presented. 展开更多
关键词 Semi-local image information Beltrami framework metric tensor active contour Kullback-Leibler distance split-Bregman method.
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Jacquard image segmentation using Mumford-Shah model
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作者 冯志林 尹建伟 +1 位作者 陈刚 董金祥 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2006年第2期109-116,共8页
Jacquard image segmentation is one of the primary steps in image analysis for jacquard pattern identification. The main aim is to recognize homogeneous regions within a jacquard image as distinct, which belongs to dif... Jacquard image segmentation is one of the primary steps in image analysis for jacquard pattern identification. The main aim is to recognize homogeneous regions within a jacquard image as distinct, which belongs to different patterns. Active contour models have become popular for finding the contours of a pattern with a complex shape. However, the performance of active contour models is often inadequate under noisy environment. In this paper, a robust algorithm based on the Mumford-Shah model is proposed for the segmentation of noisy jacquard images. First, the Mumford-Shah model is discretized on piecewise linear finite element spaces to yield greater stability. Then, an iterative relaxation algorithm for numerically solving the discrete version of the model is presented. In this algorithm, an adaptive triangular mesh is refined to generate Delaunay type triangular mesh defined on structured triangulations, and then a quasi-Newton numerical method is applied to find the absolute minimum of the discrete model. Experimental results on noisy jacquard images demonstrated the efficacy of the proposed algorithm. 展开更多
关键词 Mumford-Shah model Image segmentation Active contour Variational method Jacquard image
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搭起活动舞台,唱好习作大戏
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作者 叶超 《当代家庭教育》 2018年第7期143-143,共1页
在对小学生进行写作教学时,老师经常会遭遇到很多状况,其中缺少内容,无话可说可以说是一个普遍性存在的问题。之所以会这样,还是由于孩子缺少一双善于发现的眼睛,没有积极捕捉到身边可以利用的素材。本文将从活动入手,唤起学生沉睡的习... 在对小学生进行写作教学时,老师经常会遭遇到很多状况,其中缺少内容,无话可说可以说是一个普遍性存在的问题。之所以会这样,还是由于孩子缺少一双善于发现的眼睛,没有积极捕捉到身边可以利用的素材。本文将从活动入手,唤起学生沉睡的习作思维,促使学生在活动中去观察、去思考、去感悟、去创作,即热热闹闹搭建活动舞台,开开心心唱好习作大戏。 展开更多
关键词 习作教学 开展活动 分割活动 系列活动 德育活动
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Comparative study on the performance of textural image features for active contour segmentation
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作者 MORARU Luminita MOLDOVANU Simona 《Science China(Life Sciences)》 SCIE CAS 2012年第7期637-644,共8页
We present a computerized method for the semi-automatic detection of contours in ultrasound images. The novelty of our study is the introduction of a fast and efficient image function relating to parametric active con... We present a computerized method for the semi-automatic detection of contours in ultrasound images. The novelty of our study is the introduction of a fast and efficient image function relating to parametric active contour models. This new function is a combination of the gray-level information and first-order statistical features, called standard deviation parameters. In a comprehensive study, the developed algorithm and the efficiency of segmentation were first tested for synthetic images. Tests were also performed on breast and liver ultrasound images. The proposed method was compared with the watershed approach to show its efficiency. The performance of the segmentation was estimated using the area error rate. Using the standard devia- tion textural feature and a 5x5 kernel, our curve evolution was able to produce results close to the minimal area error rate (namely 8.88% for breast images and 10.82% for liver images). The image resolution was evaluated using the con- trast-to-gradient method. The experiments showed promising segmentation results. 展开更多
关键词 active contour model image feature area error rate
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