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1.
电力大数据主要来源于电力生产和电能使用的发电、输电、变电、配电、用电和调度各个环节,,如何运用这些数据提高电力管理工作的智能化水平已经成为相关电力环节十分重要的研究课题之一。但现有电力大数据中用到的聚类方法却不能发现任意形状的数据集聚类类别(即类簇),这影响了电力大数据在应用中的计算精度与计算时长。因此提出了一种新的算法,即使用局部密度峰值和基于共享邻点的距离,更好地结合了密度与距离的关系,表示出数据之间的差异。使用局部密度峰值并用基于共享邻点的距离来构造最小生成树,然后重复切割最长的边,直到找到给定数量的簇。在电力大数据应用上的实验结果表明,该算法在具有良好的效果。  相似文献   
2.
Image color clustering is a basic technique in image processing and computer vision, which is often applied in image segmentation, color transfer, contrast enhancement, object detection, skin color capture, and so forth. Various clustering algorithms have been employed for image color clustering in recent years. However, most of the algorithms require a large amount of memory or a predetermined number of clusters. In addition, some of the existing algorithms are sensitive to the parameter configurations. In order to tackle the above problems, we propose an image color clustering method named Student's t-based density peaks clustering with superpixel segmentation (tDPCSS), which can automatically obtain clustering results, without requiring a large amount of memory, and is not dependent on the parameters of the algorithm or the number of clusters. In tDPCSS, superpixels are obtained based on automatic and constrained simple non-iterative clustering, to automatically decrease the image data volume. A Student's t kernel function and a cluster center selection method are adopted to eliminate the dependence of the density peak clustering on parameters and the number of clusters, respectively. The experiments undertaken in this study confirmed that the proposed approach outperforms k-means, fuzzy c-means, mean-shift clustering, and density peak clustering with superpixel segmentation in the accuracy of the cluster centers and the validity of the clustering results.  相似文献   
3.
针对高岭土矿物在X-射线衍射分析过程中,组成矿物之间存在特征峰重合无法定量各组分含量的情形。该测算通过X-射线物相定量分析、化学成分分析、氧化物在矿物中所占比例等参数进行换算,计算出了高岭土各组成矿物的含量。  相似文献   
4.
在基于远场涡流的拼接套管检测中,拼接套管各管道分析的复杂性会因为远场涡流两次穿透套管壁的特性而增加.当发射线圈处于缺陷位置时,作者已提出基于双接收线圈的伪峰移除方法.当发射线圈处于正常管道位置时,伪峰移除方法并不能移除检测信号中发射线圈处管道的信息,所以本文提出弥补该不足点的方法.该方法首先通过去伪峰方法将检测信号中发射线圈附近的管道情况统一转化为无缺陷的情况;然后,采用维纳去卷积滤波器获取拼接套管上缺陷(接箍可视为缺陷)的位置信息,并根据缺陷位置反向定位拼接套管正常位置.最后,统一移除检测信号中发射线圈处管道的信息.该方法通过仪器测试科索#1井得到验证,有利于提高远场涡流在拼接套管检测分析中的实用性.  相似文献   
5.
Thermal neutron spectra in the graphite bulk of slab geometry with boron carbide were measured at temperatures from 20 to -800°C by the time-of-flight method, using a 100 MeV electron linear accelerator. The results were compared with calculation based on the multi-group S 8 method using Young-Koppel's scattering law. Fairly good agreement is obtained between the calculated and measured spectra except in a limited range of energy just above the peak of the thermal spectra. Considering the uncertainty in the spectrum calculations, the scattering kernel of graphite based on the scattering law will be accurate sufficiently to evaluate the infinite multiplication factor of a graphite moderated reactor within an error of about 0.15%. It is also emphasized from the two-dimensional S 4 calculations that the effect of reentrant hole perturbation should be so significant in the graphite bulk as to decrease the peak of the thermal spectra by 10-12%.  相似文献   
6.
X‐ray photoelectron spectroscopy (XPS) is a quantitative surface analysis technique used to identify the elemental composition, empirical formula, chemical state, and electronic state of an element. The kinetic energy of the electrons escaping from the material surface irradiated by an x‐ray beam produces a spectrum. XPS identifies chemical species and quantifies their content and the interactions between surface species. It is minimally destructive and is sensitive to a depth between 1–10nm. The elemental sensitivity is in the order of 0.1 atomic %. It requires ultra high vacuum ( Pa) in the analysis chamber and measurement time varies from minutes to hours per sample depending on the analyte. XPS dates back 50 years ago. New spectrometers, detectors, and variable size photon beams, reduce analysis time and increase spatial resolution. An XPS bibliometric map of the 10 000 articles indexed by Web of Science[1] identifies five research clusters: (i) nanoparticles, thin films, and surfaces; (ii) catalysis, oxidation, reduction, stability, and oxides; (iii) nanocomposites, graphene, graphite, and electro‐chemistry; (iv) photocatalysis, water, visible light, and ; and (v) adsorption, aqueous solutions, and waste water.  相似文献   
7.
Riparian Salicaceae are prolific producers of short‐lived seeds that require very restrictive hydro‐geomorphic conditions for establishment. It is generally assumed that if floods are able to create nursery sites timed with seed dispersal, recruitment will occur. Other spatial and temporal seed dispersal patterns besides the dispersal period have historically received little attention. However, seed dispersal patterns can be highly variable between regions, species and over the years. In this paper, we report the seed dispersal patterns of three dominant riparian Salicaceae trees in Europe: Populus alba, P. nigra and Salix alba to suggest possible trade‐offs between seed dispersal patterns, germinability, longevity and establishment. Seed rain of the three species was monitored in 33 glue‐coated traps for three months yearly from 2006 to 2008 in an 8‐km stretch of the Middle Ebro River (N Spain), which has a pluvio‐nival regime. P. alba dispersed seeds earlier during a shorter time period and with a fewer number of seed release pulses compared with P. nigra, and especially with S. alba. With overlapping seed dispersal periods, the two latter species occupy similar landform units but rarely compete with P. alba, usually at higher elevations, as shown in a previous study in the same study area. The three species had very high germinability immediately after release (>90%), but longevity in S. alba was eight times shorter than that of its two Populus counterparts. We suggest that S. alba has compensated its lower seed quality with a more spaced seed release in several pulses of similar magnitude. With similar seed dispersal patterns and germinability but a higher longevity, P. nigra had a much higher density of individuals than S. alba in the recruitment zones of the study area. We hope that our results may inform river managers about how to optimize river flows to promote sexual regeneration of these species. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
8.
Operating at different manufacturing steps, multiphase modeling and analysis of the batch process are advantageous to improving monitoring performance and understanding manufacturing processes. Although many phase partition algorithms have been proposed, they have some disadvantages and cause problems: (1) time sequence disorder, which requires elaborate post‐treatments; (2) a lack of quantitative index to indicate transition patterns; and (3) tunable parameters that cannot be quantitatively determined. To effectively overcome these problems, an iterative two‐step sequential phase partition algorithm is proposed in the present work. In the first step, initial phase partition results are obtained by checking changes of the control limit of squared prediction error. Sequentially, the fast search and find of density peaks clustering algorithm is employed to adjust the degradation degree and update the phase partition results. These two steps are iteratively executed until a proper degradation degree is found for the first phase. Then, the remaining phases are processed one by one using the same procedure. Moreover, a statistical index is quantitatively defined based on density and distance analysis to judge whether a process has transitions, and when the transition regions begin and end. In this way, the phases and transition patterns are quantitatively determined without ambiguity from the perspective of monitoring performance. The effectiveness of the proposed method is illustrated by a numerical example and a typical industrial case. Several typical phase partition algorithms are also employed for comprehensive comparisons with the proposed method. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2358–2373, 2016  相似文献   
9.
利用HPGe铀能谱88~100 keV能区确定铀富集度方法研究   总被引:1,自引:1,他引:0  
利用铀材料γ能谱88~100 keV能区中γ、X射线重峰分解确定同位素丰度的方法,是铀同位素分析商用软件MGAU、MGA++等的核心技术。本文建立了γ、X射线峰形模型,提出了效率拟合因子修正效率的方法,并自行编写了铀富集度分析程序。用HPGe γ谱仪对两种化学形态、铀富集度范围为1.80%~90.1%的铀样品进行了测量,以验证自编程序的可行性。利用本文所编写的程序分析实验能谱,得到的芯块样品分析结果与标称值的相对偏差小于2%,粉末样品分析结果与标称值的相对偏差小于1%。  相似文献   
10.
Abstract

One result of this research showed the relationship of the crack propagation into the burden as decoupling increased from 1 to 3. The resulting data indicated that the explosive generated gas pressure was the dominate parameter for breaking rock in confined boreholes. The shock energy did not have time to play an effective role in burden breakage, for by the time the stress wave returned to the face, the burden had broken under pressure.  相似文献   
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