共查询到16条相似文献,搜索用时 125 毫秒
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基于曲率距离的时间序列相似性搜索方法 总被引:1,自引:0,他引:1
针对几种时间序列相似性度量方法存在的序列元素值依赖性,对序列信息挖掘不充分等问题,该文提出一种新的时间序列分段、近似表示和相似性度量方法。在对序列信息和规律充分挖掘的基础上,对时间序列进行分段并建立了各分段的精确拟合模型,用分段的拟合曲线在各时刻处曲率组成的曲率序列对原时间序列进行近似表示,给出了时间序列的曲率距离定义。最后,提出了基于曲率距离的时间序列相似性搜索算法。该方法充分挖掘了序列信息,对时间序列的主要形态特征进行了有效保留和识别,经实验验证了该方法的有效性、稳定性和准确性。 相似文献
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符号化时间序列聚类是聚类研究中的热点之一,其中关键问题是时间序列符号化相似度问题.本文针对传统的基于欧式距离度量存在的缺陷,以LCS度量为基础,提出了ELCS相似性度量,克服了LCS度量需要依赖线性函数选取的不足.在两类数据集上进行的实验表明,同其他常用度量的比较,该度量有着更好的聚类效果. 相似文献
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介绍了一种分段极性相关的方法,并将其应用于DS-BPSK信号的多个参数估计和伪码捕获。该方法首先通过计算分段相关值的极性序列之间的相关值来估计基带码元极性,然后对分段数据进行平滑以提高信噪比条件,最后再估计伪码序列位数、码片宽度和伪码序列值等参数。仿真结果表明,该方法在输人信噪比R_(SN)=-17 dB条件下,可以同时估计DS-BPSK信号的多个特征参数,也可以进行伪码的快速捕获。 相似文献
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提出了一种处理时间序列中出现数据丢失时的信号谱估计的方法。这时观测所得到的,不再是连续等间隔的时间序列,而是多个数据段,所要进行的即是对这些分段数据的自回归模型的估计。该方法基于标准Burg谱估计算法提出,算法可以建立一个同时适用于各个分段数据的统一的信号模型。在仿真部分的结果显示,与直接使用均值方法进行谱估计相比较,分段Burg算法偏差更小,谱估计更精确。 相似文献
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分段轨迹识别方法是一种将目标轨迹分成若干段曲线,对每一段曲线进行参数估计进而估计目标状态的跟踪方法.基于分段轨迹识别方法提出了一种分段机动识别方法,使之能够适用于更多的目标机动类型.针对速度变化的目标,提出了新的曲线参数描述的模型以及新的优化跟踪性能的代价函数,改进了判断分段结束的条件以及起始新分段的方法.仿真结果表明:分段机动识别方法在稳态性能不变的情况下,能够更好地跟踪加减速目标;同时,分段机动识别方法对于高度机动目标的跟踪性能和准确构造的交互多模型算法相似,且远优于匀速直线运动模型下的卡尔曼滤波器. 相似文献
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针对现有相似实体搜索方法缺乏对于观测序列长度的自适应性,且搜索过程数据存储开销过大,搜索结果准确性较低的问题,该文提出相似度自适应估计的物联网实体高效搜索方法(SAEES)。首先,设计了轻量级观测序列分段表示方法,对传感器采集的实体原始观测序列进行轻量级分段压缩表示,以降低实体观测序列的存储开销。然后,提出了观测序列相似度自适应估计方法,实现对不同观测序列长度的实体相似性的准确估计。最后,设计了高效的相似实体搜索匹配方法,依据所估计的实体相似度进行实体的准确搜索匹配。仿真结果表明,所提方法可大幅提高相似实体搜索的效率。 相似文献
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This article presents an indexing method for 3D mesh models applied to shape and appearance similarity retrieval in database of 3D objects. The approach relies on the multi-resolution Reeb graph matching method proposed by Hilaga et al. in 2001 [1]. In our framework, we consider 3D mesh models of various geometrical complexity, different resolution, and sometimes textured. The original approach, based on the 3D object topology, is not accurate enough to obtain satisfying matching. Therefore we propose to reinforce the topological consistency conditions of the matching and to merge within the graph geometrical and visual information to improve the matching and the calculation of the similarity between models. Besides, all these new attributes can be freely weighted to fit the user requirements for object retrieval. We obtain a flexible multiresolutional and multicriteria representation that we called augmented Multiresolution Reeb Graph (aMrg). The approach has been tested and compared with other methods. It reveals very performant for the retrieval and the classification of similar 3D shapes. 相似文献
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基于角膜形变计算出一系列生物力学特性参数是训练早期圆锥角膜分类模型的数据基础,因此圆锥角膜轮廓分割的精确性直接影响着早期圆锥角膜分类模型的准确性。本文提出了一种基于残差网络的无监督角膜视频分割方法。通过统一的网格化采样提取一组锚点被同序列视频帧所共用,从而减小网络模型学习特征表示的计算量并且提高了计算效率。同时设计了一个正则化分支对原有的视频集进行相似性转换来解决可能存在的退化解问题。与已有的无监督视频分割任务相比,本实验模型使用了少量的训练数据,但却取得了更高的分割精度和计算效率。 相似文献
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为了实现铁路货车轮对踏面磨耗动态测量,建立了基于激光图像的踏面磨耗检测系统。对该系统中踏面磨耗动态测量方法进行了研究。首先,采用基于量子粒子群优化算法的二维最大相关准则法进行图像分割。然后,采用基于形态学的细化算法和爬虫跟踪法组合的方法提取中心线。接着,采用基于多项式的空间坐标变换算法和双线性插值算法组合的方法对畸变的曲线进行校正。最后,采用曲线匹配技术匹配标准曲线和磨耗曲线。实验结果表明:系统对踏面磨耗的测量误差小于0.2 mm,检测时间2.1 s,满足车辆段修现场使用要求。 相似文献
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This paper presents a segmentation based stereo matching algorithm. For the purposes of both preserving the shape of object surfaces and being robust to under segmentations, we introduce a new scene formulation where the reference image is divided into overlapping lines. The disparity value and the index of pixels on lines are modeled by polynomial functions. Polynomial functions are propagated among lines to obtain smooth surfaces via solving energy minimizing problems. Finally, the disparity of pixels is estimated from the disparity fields provided by lines. Because lines in multiple directions implicitly segment different objects in an under segmentation region, our method is robust for under segmented regions where it is usually difficult for conventional region based methods to produce satisfactory results. Experimental results demonstrate that the proposed method has an outstanding performance compared with the current state-of-the-art methods. The scene representation method in this work is also a powerful approach to surface based scene representations. 相似文献
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Zeinab Naseri Samaghcheh Fatemeh Abdoli Hamid Abrishami Moghaddam Mohammadreza Modaresi Neda Pak 《Signal, Image and Video Processing》2018,12(2):339-346
A new framework for model-based lung tissue segmentation in three-dimensional thoracic CT images is proposed. In the first stage, a parametric model for lung segmenting surface is created using shape representation based on level sets method. This model is constituted by the sum of a mean distance function and a number of weighted eigenshapes. Consequently, unlike the other model-based segmentation methods, there is no need to specify any marker point in this model. In the second stage, the segmenting surface is varied so as to be matched with the binarized input image. For this purpose, a region-based energy function is minimized with respect to the parameters including the weights of eigenshapes and coefficients of a three-dimensional similarity transform. Finally, the resulted segmenting surface is post-processed in order to improve its fitness with the lung borders of the input image. The experimental results demonstrated the outperformance of the proposed framework over its model-based counterparts in model matching stage. Moreover, it performed slightly better in terms of final segmentation results. 相似文献