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Infrared small target detection based on density peaks searching and weighted multi-feature local difference
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作者 JI Bin FAN Pengxiang +2 位作者 WANG Mengli LIU Yang XU Jiafeng 《Optoelectronics Letters》 2025年第4期218-225,共8页
To address the issues of unknown target size,blurred edges,background interference and low contrast in infrared small target detection,this paper proposes a method based on density peaks searching and weighted multi-f... To address the issues of unknown target size,blurred edges,background interference and low contrast in infrared small target detection,this paper proposes a method based on density peaks searching and weighted multi-feature local difference.Firstly,an improved high-boost filter is used for preprocessing to eliminate background clutter and high-brightness interference,thereby increasing the probability of capturing real targets in the density peak search.Secondly,a triple-layer window is used to extract features from the area surrounding candidate targets,addressing the uncertainty of small target sizes.By calculating multi-feature local differences between the triple-layer windows,the problems of blurred target edges and low contrast are resolved.To balance the contribution of different features,intra-class distance is used to calculate weights,achieving weighted fusion of multi-feature local differences to obtain the weighted multi-feature local differences of candidate targets.The real targets are then extracted using the interquartile range.Experiments on datasets such as SIRST and IRSTD-IK show that the proposed method is suitable for various complex types and demonstrates good robustness and detection performance. 展开更多
关键词 extract featur background clutter density peaks searching infrared small target detection weighted multi feature local difference capturing real targets density peak infrared small target detectionthis
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A Clustering Model Based on Density Peak Clustering and the Sparrow Search Algorithm for VANETs
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作者 Chaoliang Wang Qi Fu Zhaohui Li 《Computers, Materials & Continua》 2025年第8期3707-3729,共23页
Cluster-basedmodels have numerous application scenarios in vehicular ad-hoc networks(VANETs)and can greatly help improve the communication performance of VANETs.However,the frequent movement of vehicles can often lead... Cluster-basedmodels have numerous application scenarios in vehicular ad-hoc networks(VANETs)and can greatly help improve the communication performance of VANETs.However,the frequent movement of vehicles can often lead to changes in the network topology,thereby reducing cluster stability in urban scenarios.To address this issue,we propose a clustering model based on the density peak clustering(DPC)method and sparrow search algorithm(SSA),named SDPC.First,the model constructs a fitness function based on the parameters obtained from the DPC method and deploys the SSA for iterative optimization to select cluster heads(CHs).Then,the vehicles that have not been selected as CHs are assigned to appropriate clusters by comprehensively considering the distance parameter and link-reliability parameter.Finally,cluster maintenance strategies are considered to tackle the changes in the clusters’organizational structure.To verify the performance of the model,we conducted a simulation on a real-world scenario for multiple metrics related to clusters’stability.The results show that compared with the APROVE and the GAPC,SDPC showed clear performance advantages,indicating that SDPC can effectively ensure VANETs’cluster stability in urban scenarios. 展开更多
关键词 VANETS CLUSTER density peak clustering sparrow search algorithm
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A DBRTD with a High PVCR and a Peak Current Density at Room Temperature
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作者 易里成荣 谢常青 +2 位作者 王从舜 刘明 叶甜春 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2005年第10期1871-1874,共4页
AlAs/GaAs/In0.1Ga0.9As/GaAs/AlAs double-barrier resonant tunneling diodes (DBRTDs) grown on a semi-insulated GaAs substrate with molecular beam epitaxy is demonstrated. By sandwiching the In0.1 Ga0.9 As layer betwee... AlAs/GaAs/In0.1Ga0.9As/GaAs/AlAs double-barrier resonant tunneling diodes (DBRTDs) grown on a semi-insulated GaAs substrate with molecular beam epitaxy is demonstrated. By sandwiching the In0.1 Ga0.9 As layer between GaAs layers, potential wells beside the two sides of barrier are deepened, resulting in an increase of the peak-to-valley current ratio (PVCR) and a peak current density. A special shape of collector is designed in order to reduce contact resistance and non-uniformity of the current;as a result the total chrrent density in the device is increased. The use of thin barriers is also helpful for the improvement of the PVCR and the peak current density in DBRTDs. The devices exhibit a maximum PVCR of 13.98 and a peak current density of 89kA/cm^2 at room temperature. 展开更多
关键词 resonant tunneling diode peak-to-valley current ratio peak current density
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基于K互近邻与核密度估计的DPC算法 被引量:2
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作者 周玉 夏浩 +1 位作者 刘虹瑜 白磊 《北京航空航天大学学报》 北大核心 2025年第6期1978-1990,共13页
快速搜索和发现密度峰值聚类(DPC)算法是一种基于密度的聚类算法。该算法不需要迭代和过多的设定参数,但由于计算局部密度时没有考虑数据的局部结构,导致无法识别簇密度小的聚类中心。针对此问题,提出基于K互近邻(KN)和核密度估计(KDE)... 快速搜索和发现密度峰值聚类(DPC)算法是一种基于密度的聚类算法。该算法不需要迭代和过多的设定参数,但由于计算局部密度时没有考虑数据的局部结构,导致无法识别簇密度小的聚类中心。针对此问题,提出基于K互近邻(KN)和核密度估计(KDE)的DPC(KKDPC)算法。通过K近邻和核密度估计方法得到数据点的K互近邻数量和局部核密度;将K互近邻数量与局部核密度进行加和获得新的局部密度;根据数据点的局部密度得到相对距离,并通过构建决策图选取聚类中心及分配非中心点。利用人工数据集和真实数据集进行实验,并与DPC、基于密度的噪声空间聚类应用(DBSCAN)、K-means、模糊C均值聚类算法(FCM)、基于K近邻的DPC(DPCKNN)、近邻优化DPC(DPC-NNO)、基于模糊加权共享邻居的DPC(DPC-FWSN)算法进行对比。通过计算调整互信息(AMI)、调整兰德指数(ARI)、归一化互信息(NMI)来验证KKDPC算法的性能。实验结果表明:KKDPC算法能更加准确地识别聚类中心,有效地提高聚类精度。 展开更多
关键词 聚类算法 密度峰值 K近邻 K互近邻 核密度估计
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Modeling of Energy Consumption and Effluent Quality Using Density Peaks-based Adaptive Fuzzy Neural Network 被引量:10
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作者 Junfei Qiao Hongbiao Zhou 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2018年第5期968-976,共9页
Modeling of energy consumption(EC) and effluent quality(EQ) are very essential problems that need to be solved for the multiobjective optimal control in the wastewater treatment process(WWTP). To address this issue, a... Modeling of energy consumption(EC) and effluent quality(EQ) are very essential problems that need to be solved for the multiobjective optimal control in the wastewater treatment process(WWTP). To address this issue, a density peaks-based adaptive fuzzy neural network(DP-AFNN) is proposed in this study. To obtain suitable fuzzy rules, a DP-based clustering method is applied to fit the cluster centers to process nonlinearity.The parameters of the extracted fuzzy rules are fine-tuned based on the improved Levenberg-Marquardt algorithm during the training process. Furthermore, the analysis of convergence is performed to guarantee the successful application of the DPAFNN. Finally, the proposed DP-AFNN is utilized to develop the models of EC and EQ in the WWTP. The experimental results show that the proposed DP-AFNN can achieve fast convergence speed and high prediction accuracy in comparison with some existing methods. 展开更多
关键词 density peaks clustering effluent quality (EQ) energy consumption (EC) fuzzy neural network improved Levenberg-Marquardt algorithm wastewater treatment process (WWTP).
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Formation of the mass density peak at the magnetospheric equator triggered by EMIC waves 被引量:4
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作者 ZuXiang Xue ZhiGang Yuan +2 位作者 XiongDong Yu ShiYong Huang Zheng Qiao 《Earth and Planetary Physics》 CSCD 2021年第1期32-41,共10页
We report a simultaneous observation of two band electromagnetic ion cyclotron(EMIC)waves and toroidal Alfvén waves by the Van Allen Probe mission.Through wave frequency analyses,the mass densityρis found to be ... We report a simultaneous observation of two band electromagnetic ion cyclotron(EMIC)waves and toroidal Alfvén waves by the Van Allen Probe mission.Through wave frequency analyses,the mass densityρis found to be locally peaked at the magnetic equator.Perpendicular fluxes of ions(<100 eV)increase simultaneously with the appearances of EMIC waves,indicating a heating of these ions by EMIC waves.In addition,the measured ion distributions also support the equatorial peak formation,which accords with the result of the frequency analyses.The formation of local mass density peaks at the equator should be due to enhancements of equatorial ion concentrations,which are triggered by EMIC waves’perpendicular heating on low energy ions. 展开更多
关键词 toroidal Alfvén waves EMIC waves magnetoseismology equatorial mass density peak
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Peak of Electron Density in F2-Layer Parameters Variability at Quiet Days on Solar Minimum 被引量:2
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作者 Emmanuel Nanéma Moustapha Konaté Frédéric Ouattara 《Journal of Modern Physics》 2019年第3期302-309,共8页
This study deals with Peak of electron density in F2-layer sensibility scale during quiet time on solar minimum. Peaks of electron density in F2-layer (NmF2) values at the quietest days are compared to those carried o... This study deals with Peak of electron density in F2-layer sensibility scale during quiet time on solar minimum. Peaks of electron density in F2-layer (NmF2) values at the quietest days are compared to those carried out from the two nearest days (previous and following of quietest day). The study uses International Reference Ionosphere (IRI) for ionosphere modeling. The located station is Ouagadougou, in West Africa. Solar minimum of phase 22 is considered in this study. Using three core principles of ionosphere modeling under IRI running conditions, the study enables to carry out Peak of electron density in F2-layer values during the quietest days of the characteristic months for the four different seasons. These parameters are compared to those of the previous and the following of the quietest days (the day before and following each quietest selected day) at the same hour. The knowledge of NmF2 values at the quietest days and at the two nearest days enables to calculate the relative error that can be made on this parameter. This calculation highlights insignificant relative errors. This means that NmF2 values at the two nearest days of each quietest day on solar minimum can be used for simulating the quietest days’ behavior. NmF2 values obtained by running IRI model have good correlation with those carried out by Thermosphere-Ionosphere-Electrodynamics-General Circulation Model (TIEGCM). 展开更多
关键词 IONOSPHERE peak of Electron density in F2-Layer Solar Cycle QUIET Day International Reference IONOSPHERE Model
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基于DPK-means与隶属因子的低压配电台区拓扑识别方法 被引量:1
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作者 梁婧超 魏斌 +1 位作者 孟润泉 谭非同 《电网与清洁能源》 北大核心 2025年第6期73-82,共10页
针对低压配电台区内拓扑结构不清晰,台区内层级关系不明确的问题,提出了一种基于密度峰值K均值聚类算法(density peak K-means,DPK-means)与隶属因子的低压配电台区全层级网络拓扑识别方法。采用Z-Score标准化方法对特征的差异进行放大... 针对低压配电台区内拓扑结构不清晰,台区内层级关系不明确的问题,提出了一种基于密度峰值K均值聚类算法(density peak K-means,DPK-means)与隶属因子的低压配电台区全层级网络拓扑识别方法。采用Z-Score标准化方法对特征的差异进行放大;采用DPK-means对台区内用户的相位进行区分识别;提出一种基于电压曲线相似度的隶属因子计算方法,识别出台区内“分支箱—表箱—用户”的隶属关系,从而实现低压配电台区“配电变压器—分支箱—表箱—用户—相位”的全层级拓扑识别;在实际算例模型中分析验证了所提方法的有效性。 展开更多
关键词 低压配电台区 拓扑识别 密度峰值K均值聚类算法(density peak K-means dpK-means) 隶属因子
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K-means Find Density Peaks in Molecular Conformation Clustering 被引量:1
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作者 Guiyan Wang Ting Fu +5 位作者 Hong Ren Peijun Xu Qiuhan Guo Xiaohong Mou Yan Li Guohui Li 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2022年第2期353-368,I0026-I0030,I0003,共22页
Performing cluster analysis on molecular conformation is an important way to find the representative conformation in the molecular dynamics trajectories.Usually,it is a critical step for interpreting complex conformat... Performing cluster analysis on molecular conformation is an important way to find the representative conformation in the molecular dynamics trajectories.Usually,it is a critical step for interpreting complex conformational changes or interaction mechanisms.As one of the density-based clustering algorithms,find density peaks(FDP)is an accurate and reasonable candidate for the molecular conformation clustering.However,facing the rapidly increasing simulation length due to the increase in computing power,the low computing efficiency of FDP limits its application potential.Here we propose a marginal extension to FDP named K-means find density peaks(KFDP)to solve the mass source consuming problem.In KFDP,the points are initially clustered by a high efficiency clustering algorithm,such as K-means.Cluster centers are defined as typical points with a weight which represents the cluster size.Then,the weighted typical points are clustered again by FDP,and then are refined as core,boundary,and redefined halo points.In this way,KFDP has comparable accuracy as FDP but its computational complexity is reduced from O(n^(2))to O(n).We apply and test our KFDP method to the trajectory data of multiple small proteins in terms of torsion angle,secondary structure or contact map.The comparing results with K-means and density-based spatial clustering of applications with noise show the validation of the proposed KFDP. 展开更多
关键词 K-means find density peaks Molecular clustering density-based spatial clustering of applications with noise
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Fast density peak-based clustering algorithm for multiple extended target tracking 被引量:4
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作者 SHEN Xinglin SONG Zhiyong +1 位作者 FAN Hongqi FU Qiang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2019年第3期435-447,共13页
The key challenge of the extended target probability hypothesis density (ET-PHD) filter is to reduce the computational complexity by using a subset to approximate the full set of partitions. In this paper, the influen... The key challenge of the extended target probability hypothesis density (ET-PHD) filter is to reduce the computational complexity by using a subset to approximate the full set of partitions. In this paper, the influence for the tracking results of different partitions is analyzed, and the form of the most informative partition is obtained. Then, a fast density peak-based clustering (FDPC) partitioning algorithm is applied to the measurement set partitioning. Since only one partition of the measurement set is used, the ET-PHD filter based on FDPC partitioning has lower computational complexity than the other ET-PHD filters. As FDPC partitioning is able to remove the spatially close clutter-generated measurements, the ET-PHD filter based on FDPC partitioning has good tracking performance in the scenario with more clutter-generated measurements. The simulation results show that the proposed algorithm can get the most informative partition and obviously reduce computational burden without losing tracking performance. As the number of clutter-generated measurements increased, the ET-PHD filter based on FDPC partitioning has better tracking performance than other ET-PHD filters. The FDPC algorithm will play an important role in the engineering realization of the multiple extended target tracking filter. 展开更多
关键词 FAST density peak-based clustering (FdpC) MULTIPLE extended target partition probability hypothesis density (PHD) filter track.
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A Method of Inversing the Peak Density of Atomic Oxygen Vertical Distribution in the MLT Region From the OI (557.7 nm)Night Airglow Intensity 被引量:3
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作者 H. Gao J. Y. Xu W. Yuan 《空间科学学报》 CAS CSCD 北大核心 2005年第5期484-489,共6页
In this paper, using the MSISE-90 model as the reference atmosphere, we discuss the feasibility and method of deducing the peak densities of the undisturbed atomic oxygen profiles in the MLT region (the mesosphere and... In this paper, using the MSISE-90 model as the reference atmosphere, we discuss the feasibility and method of deducing the peak densities of the undisturbed atomic oxygen profiles in the MLT region (the mesosphere and lower thermosphere region) from OI (557.7 nm) night airglow intersities. The peak densities for different seasons, latitudes and longitudes are deduced from OI (557.7nm) airglow intensities through this expression. We analyze the features of inversion relative errors and discuss the influence of the variations in temperature on inversion errors. The results indicate that all inversion errors are less than 5% except for those at high altitudes in the summer hemisphere. And the impact of the variations in temperature on errors is not significant. 展开更多
关键词 原子 MLT 气辉 天文
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Density peaks clustering based integrate framework for multi-document summarization 被引量:2
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作者 BaoyanWang Jian Zhang +1 位作者 Yi Liu Yuexian Zou 《CAAI Transactions on Intelligence Technology》 2017年第1期26-30,共5页
We present a novel unsupervised integrated score framework to generate generic extractive multi- document summaries by ranking sentences based on dynamic programming (DP) strategy. Considering that cluster-based met... We present a novel unsupervised integrated score framework to generate generic extractive multi- document summaries by ranking sentences based on dynamic programming (DP) strategy. Considering that cluster-based methods proposed by other researchers tend to ignore informativeness of words when they generate summaries, our proposed framework takes relevance, diversity, informativeness and length constraint of sentences into consideration comprehensively. We apply Density Peaks Clustering (DPC) to get relevance scores and diversity scores of sentences simultaneously. Our framework produces the best performance on DUC2004, 0.396 of ROUGE-1 score, 0.094 of ROUGE-2 score and 0.143 of ROUGE-SU4 which outperforms a series of popular baselines, such as DUC Best, FGB [7], and BSTM [10]. 展开更多
关键词 Multi-document summarization Integrated score framework density peaks clustering Sentences rank
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ON DOUBLE PEAK PROBABILITY DENSITY FUNCTIONS OF DUFFING OSCILLATOR TO COMBINED DETERMINISTIC AND RANDOM EXCITATIONS
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作者 戎海武 王向东 +2 位作者 孟光 徐伟 方同 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2006年第11期1569-1576,共8页
The principal resonance of Duffing random external excitation was investigated. oscillator to combined deterministic and The random excitation was taken to be white noise or harmonic with separable random amplitude an... The principal resonance of Duffing random external excitation was investigated. oscillator to combined deterministic and The random excitation was taken to be white noise or harmonic with separable random amplitude and phase. The method of multiple scales was used to determine the equations of modulation of amplitude and phase. The one peak probability density function of each of the two stable stationary solutions was calculated by the linearization method. These two one-peak-density functions were combined using the probability of realization of the two stable stationary solutions to obtain the double peak probability density function. The theoretical analysis are verified by numerical results. 展开更多
关键词 Duffing oscillator double peak probability density function multiple scale method linearization method
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Impact of E×B flow shear stabilization on particle confinement and density peaking at JET
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作者 W BUANGAM J GARCIA +1 位作者 T ONJUN JET Contributors 《Plasma Science and Technology》 SCIE EI CAS CSCD 2020年第6期60-73,共14页
The impact of the E×B flow shear stabilization on particle transport and density peaking at JET is analyzed in the framework of integrated modelling with the CRONOS code.For that purpose,plasmas from a power scan... The impact of the E×B flow shear stabilization on particle transport and density peaking at JET is analyzed in the framework of integrated modelling with the CRONOS code.For that purpose,plasmas from a power scan which show a significant increasing of density peaking with the injected neutral beam injection power have been used as a modeling basis.By means of simulations with the quasilinear model GLF23 for the heat and particle transport,a strong link between the particle confinement and E×B flow shear stabilization is found.This is particularly important close to the pedestal region where the particle pinch direction becomes strongly inward for high E×B flow shear values.Such impact introduces some non-negligible deviation from the well-known collisonality dependence of the density peaking,whose general trend has been also obtained in the framework of this modelling by performing pedestal density scans. 展开更多
关键词 particle confinement density peaking flow shear transport
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基于GWO CFDP算法的速度传感器干扰源识别 被引量:1
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作者 姜楠 张健穹 +2 位作者 臧杰锋 李相强 王庆峰 《机械与电子》 2025年第3期74-80,共7页
为了准确判断列车行驶时TCU速度传感器的干扰来源,提出了基于灰狼算法(GWO)改进的密度峰值快速聚类(CFDP)算法。首先,对列车实测干扰信号进行特征分析;然后,通过采用2层稀疏自编码网络连同核主成分分析,对预处理后的信号完成特征的自提... 为了准确判断列车行驶时TCU速度传感器的干扰来源,提出了基于灰狼算法(GWO)改进的密度峰值快速聚类(CFDP)算法。首先,对列车实测干扰信号进行特征分析;然后,通过采用2层稀疏自编码网络连同核主成分分析,对预处理后的信号完成特征的自提取与降维;最后,利用所提出的GWO CFDP算法实现4种干扰工况的分类识别。实验结果表明,所提出的干扰源识别算法对4种干扰工况的识别准确率达到99.0%,验证了该算法在干扰源识别领域的有效性和实用价值。 展开更多
关键词 速度传感器 密度峰值聚类 灰狼算法 稀疏自编码 核主成分分析
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Improved Density Peaking Algorithm for Community Detection Based on Graph Representation Learning
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作者 Jiaming Wang Xiaolan Xie +1 位作者 Xiaochun Cheng Yuhan Wang 《Computer Systems Science & Engineering》 SCIE EI 2022年第12期997-1008,共12页
There is a large amount of information in the network data that we canexploit. It is difficult for classical community detection algorithms to handle network data with sparse topology. Representation learning of netwo... There is a large amount of information in the network data that we canexploit. It is difficult for classical community detection algorithms to handle network data with sparse topology. Representation learning of network data is usually paired with clustering algorithms to solve the community detection problem.Meanwhile, there is always an unpredictable distribution of class clusters outputby graph representation learning. Therefore, we propose an improved densitypeak clustering algorithm (ILDPC) for the community detection problem, whichimproves the local density mechanism in the original algorithm and can betteraccommodate class clusters of different shapes. And we study the communitydetection in network data. The algorithm is paired with the benchmark modelGraph sample and aggregate (GraphSAGE) to show the adaptability of ILDPCfor community detection. The plotted decision diagram shows that the ILDPCalgorithm is more discriminative in selecting density peak points compared tothe original algorithm. Finally, the performance of K-means and other clusteringalgorithms on this benchmark model is compared, and the algorithm is proved tobe more suitable for community detection in sparse networks with the benchmarkmodel on the evaluation criterion F1-score. The sensitivity of the parameters ofthe ILDPC algorithm to the low-dimensional vector set output by the benchmarkmodel GraphSAGE is also analyzed. 展开更多
关键词 Representation learning data mining low-dimensional embedding community detection density peaking algorithm
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基于改进DPC的毫米波雷达多目标跟踪研究
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作者 耿双双 谢广明 +1 位作者 管浩丞 文家燕 《广西科技大学学报》 2025年第4期97-106,共10页
为解决路侧毫米波雷达数据分布不均匀、噪点较多,导致雷达在多目标跟踪方面准确性下降的问题,本文在密度峰值聚类(density peaks clustering,DPC)算法的基础上,提出一种适用于毫米波雷达数据改进的DPC算法。该方法结合匈牙利匹配算法和... 为解决路侧毫米波雷达数据分布不均匀、噪点较多,导致雷达在多目标跟踪方面准确性下降的问题,本文在密度峰值聚类(density peaks clustering,DPC)算法的基础上,提出一种适用于毫米波雷达数据改进的DPC算法。该方法结合匈牙利匹配算法和无迹卡尔曼滤波算法(unscented Kalman filter,UKF),实现77 GHz毫米波雷达在不同车流密度路面上的跟踪验证。实验结果表明:改进后的DPC算法能够在大幅度提高毫米波雷达数据聚类精度的同时,有效提高多目标跟踪算法的跟踪精度。 展开更多
关键词 毫米波雷达 多目标跟踪 密度峰值聚类(dpC) 匈牙利匹配 无迹卡尔曼滤波(UKF)
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DP半岛街头抢劫犯罪案件热点时空模式 被引量:58
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作者 徐冲 柳林 +2 位作者 周素红 叶信岳 姜超 《地理学报》 EI CSCD 北大核心 2013年第12期1714-1723,共10页
选取H市中心城区DP半岛作为研究区域,以岛上2006-2011年发生的街头抢劫案件(共373起)作为研究对象,将DP半岛内街头抢劫案件的时空分布特征分别从宏观和局部微观两个尺度层面进行系统的分析。首先,对岛上的街头抢劫案件按年、月和小时进... 选取H市中心城区DP半岛作为研究区域,以岛上2006-2011年发生的街头抢劫案件(共373起)作为研究对象,将DP半岛内街头抢劫案件的时空分布特征分别从宏观和局部微观两个尺度层面进行系统的分析。首先,对岛上的街头抢劫案件按年、月和小时进行统计分析,总结其在不同时间尺度上的变化规律:2007年开始的严打使案件数量逐年减少,直到2010年才略有回升;春节期间(二月前后)的案件数量明显高于其他月份;晚上22:00-23:00期间是案件高发时段。其次,利用Kernel密度方法对研究区街头抢劫犯罪的宏观空间分布进行整体的辨别,剥离出犯罪热点空间分布,分析热点与道路网和土地利用的关联性,结果表明热点多分布于主干道、通达性高的节点或土地利用混合度高的地方。最后,选出4个最主要的热点从微观尺度进行分析,PAI指数表明这4个热点在时间上是稳定的,从2006年到2011年一直存在。依据"热点时空类型矩阵"的时间分布和空间分布模式,将这4个稳定热点归类到不同微观时空模式,并对每类模式下的街头抢劫犯罪提出有针对性的防控对策,以便优化警力资源的配置、最大限度抑制和减少犯罪的发生。 展开更多
关键词 dp半岛 街头抢劫 kernel密度 PAI指数 时空类型矩阵
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不同应变速率下DP钢变形行为的微观机理研究 被引量:5
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作者 徐超 朱超群 +1 位作者 何燕霖 李麟 《上海金属》 CAS 北大核心 2014年第3期1-5,共5页
利用3 000 kN电子万能试验机和ZWICK HTM5020高速拉伸试验装置研究了双相钢(DP钢)在不同应变速率(10-4~600 s-1)下的拉伸变形行为,并结合XRD分析对双相钢组织中的位错密度进行了计算。结果表明,在准静态拉伸过程中,双相钢组织中的... 利用3 000 kN电子万能试验机和ZWICK HTM5020高速拉伸试验装置研究了双相钢(DP钢)在不同应变速率(10-4~600 s-1)下的拉伸变形行为,并结合XRD分析对双相钢组织中的位错密度进行了计算。结果表明,在准静态拉伸过程中,双相钢组织中的位错密度基本不变,其抗拉强度、断裂延伸率随应变速率变化也不明显;而在动态拉伸条件下,随着应变速率的增加,双相钢组织中的位错密度不断增加,抗拉强度也相应增加,塑性降低,最终导致能量吸收下降。 展开更多
关键词 双相钢 应变速率 变形行为 位错密度 能量吸收
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一种基于CFSFDP改进算法的重要地点识别方法研究 被引量:5
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作者 马春来 单洪 +1 位作者 马涛 朱立新 《计算机应用研究》 CSCD 北大核心 2017年第1期136-140,共5页
为解决CFSFDP聚类算法由于无法自动选择簇中心点而难以应用于重要地点识别的问题,引入一种簇中心点自动选择策略对算法进行改进。该策略将簇中心点权值的变化趋势作为自动划分簇中心的依据,有效避免了通过决策图判决簇中心点的方法所带... 为解决CFSFDP聚类算法由于无法自动选择簇中心点而难以应用于重要地点识别的问题,引入一种簇中心点自动选择策略对算法进行改进。该策略将簇中心点权值的变化趋势作为自动划分簇中心的依据,有效避免了通过决策图判决簇中心点的方法所带来的误差。将CFSFDP改进算法与数据预处理及逆向地理编码等技术结合起来,能够以较高的精度实现重要地点识别。实验以Foursquare数据为例,结果表明CFSFDP改进算法比DBSCAN具有更高的准确率和较低的计算量,进一步证明了该方法在处理稀疏位置数据的重要地点识别问题上具有一定优越性。 展开更多
关键词 重要地点识别 速度剪枝 基于密度的聚类 密度峰值 簇中心
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