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Geometric transformations parameters estimation from copy-move forgery using image blobs and keypoints

MULTIMEDIA TOOLS AND APPLICATIONS 2022年第2期81卷 1953-1969页

作者： Patrick, Niyishaka Bhagvati, Chakravarthy Univ Hyderabad Hyderabad India

A copy-move forgery is a passive tampering wherein one or more regions have been copied and pasted within the same image. Often, geometric transformations, including scale, rotation, and rotation+scale are applied to the forged areas to conceal the counterfeits to the copy-move forgery detection methods. Recently, copy-move forgery detection using image blobs have been used to tackle the limitation of the existing detection methods. However, the main limitation of blobs-based copy-move forgery detection methods is the inability to perform the geometric transformation estimation. To tackle the above-mentioned limitation, this article presents a technique that detects copy-move forgery and estimates the geometric transformation parameters between the authentic region and its duplicate using image blobs and scale-rotation invariant keypoints. The proposed algorithm involves the following steps: image blobs are found in the image being analyzed;scale-rotation invariant features are extracted;the keypoints that are located within the same blob are identified;feature matching is performed between keypoints that are located within different blobs to find similar features;finally, the blobs with matched keypoints are post-processed and a 2D affine transformations is computed to estimate the geometric transformation parameters. Our technique is flexible and can easily take in various scale-rotation invariant keypoints including AKAZE, ORB, BRISK, SURF, and SIFT to enhance the effectiveness. The proposed algorithm is implemented and evaluated on images forged with copy-move regions combined with geometric transformation from standard datasets. The experimental results indicate that the new algorithm is effective for geometric transformation parameters estimation.

关键词： blobs CMF CMFD DoG 2D Affine transformation

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Nonlinear turbulent parallel momentum transport due to blobs

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NUCLEAR FUSION 2019年第7期59卷

作者： Li, Yang Li, Jiquan Gao, Zhe Southwestern Inst Phys Chengdu 610041 Sichuan Peoples R China Tsinghua Univ Dept Engn Phys Beijing 100084 Peoples R China

The nonlinear flux term induced by blobs is derived by using an eddy damped quasi-normal Markovian method in a three dimensional Hasegawa-Wakatani system with a strong non-adiabatic assumption. It is shown that the nonlinear flux is comparable to the quasilinear flux in the case of mixing level turbulence and can become dominant in strong turbulence regimes such as blobs. Moreover, when strong non-adiabatic or strong parallel flow shear conditions are considered, for radially elongated blobs or streamers, nonlinear residual flux can provide the opposite parallel momentum flux to the quasilinear flux and negative nonlinear diffusivity, which introduces inward momentum flux, so that rotation in the edge region is possibly reversed and momentum is convected into the core region.

关键词： parallel momentum transport blobs eddy-damped quasi-normal Markovian method nonlinear turbulent transport

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Correlation between the blob properties and global plasma parameters in L-mode on EAST

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PLASMA PHYSICS AND CONTROLLED FUSION 2025年第2期67卷 025006-025006页

作者： Wang, P. Hu, G. H. Chen, L. Wang, Y. F. Shan, L. L. Jiang, X. S. Wang, L. Xu, G. S. Yang, Q. Q. Meng, L. Y. Lin, X. Wang, Y. B. Wu, D. G. Yan, N. Peng, J. Chuzhou Univ Sch Mech & Elect Engn Chuzhou 239000 Peoples R China Chinese Acad Sci Inst Plasma Phys Hefei 230031 Peoples R China Univ Sci & Technol China Hefei 230026 Peoples R China Anhui Kedaoxin Precis Equipment Co Ltd Hefei 230088 Peoples R China

The correlations between blob properties and plasma density ne, plasma current Ip, edge safety factor Q95, toroidal magnetic field Bt, plasma stored energy WMHD, heating power Pheating, upper triangularity delta U, and the outer midplane gap in the L-mode plasmas on EAST are studied. It was found that the blob size and lifetime exhibit a strong positive correlation with plasma density, toroidal magnetic field, and edge safety factor, and a strong negative correlation with plasma current, heating power, and stored energy. Conversely, the blob detection rate shows essentially the opposite correlations with these parameters. Given that the normalized collisionality parameter Lambda is proportional to ne, Bt, Q95 and inversely proportional to Ip and Te, it suggests that the normalized collisionality parameter Lambda may play a crucial role in influencing blob size, lifetime, and detection rate. However, the radial velocity of blobs was found to be only negatively correlated with the heating power and independent of other parameters, indicating that it is not only affected by the collisionality Lambda. The dependence of blob velocity on the heating power may be related to the effect of the heating power on the Ex B flow of the background plasma. In addition, the plasma configuration in the range of this study has no noticeable impact on the blob properties measured in this study.

关键词： blobs plasma parameters scrape-off layer EAST

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Filament simulations for stellarators;a review of recent progress

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FRONTIERS IN PHYSICS 2024年 12卷

作者： Shanahan, Brendan Max Planck Inst Plasmaphys IPP Greifswald Germany

A review of recent advances in simulations of turbulent filaments with relevance to stellarators is presented. Progress in performing global edge turbulence simulations is discussed as well as results from seeded filament simulations with applications to the unique environment of a stellarator island divertor-including abrupt changes in connection length and highly-nonuniform curvature drive. It is determined that the motion of filaments generally follows the average curvature, but strong nonuniform perturbations can shear a filament and reduce the overall transport. The coherence of filament transport is also determined to be influenced by the collisionality and electron plasma beta. By simplifying the simulation geometries, large parameter scans can be performed which accurately reflect the macroscopic transport of filaments observed in Wendelstein 7-X. Comparisons to experiments are discussed, and a the develeopment of a synthetic diagnostic has been able to inform experimental measurements by quantifying potential sources of error in filament propagation measurements. A discussion of the necessary extension to more complex multifluid models, and the scope for near-term filament simulations in stellarators, is provided.

关键词： blobs filaments stellarator BOUT plus plus BSTING

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On how structures convey non-diffusive turbulence spreading

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NUCLEAR FUSION 2024年第6期64卷 064002-064002页

作者： Long, Ting Diamond, P. H. Ke, Rui Chen, Zhipeng Cao, Mingyun Xu, Xin Xu, Min Hong, Rongjie Tian, Wenjing Yuan, Jinbang Liu, Yanmin Yan, Qinghao Yang, Qinghu Shen, Chengshuo Guo, Weixin Wang, Lu Nie, Lin Wang, Zhanhui Hao, Guangzhou Wang, Nengchao Chen, Zhongyong Pan, Yuan Li, Jiquan Chen, Wei Zhong, Wulyu Southwestern Inst Phys Chengdu Peoples R China Univ Calif San Diego Dept Astron Astrophys & Phys Santa Cruz CA 95064 USA Huazhong Univ Sci & Technol Sch Elect & Elect Engn State Key Lab Adv Electromagnet Technol Int Joint Res Lab Magnet Confinement Fus & Plasma Wuhan 430074 Peoples R China Univ Calif Los Angeles Los Angeles CA USA Tsinghua Univ Beijing Peoples R China

We report on comprehensive experimental studies of turbulence spreading in edge plasmas. These studies demonstrate the relation of turbulence spreading and entrainment to intermittent convective density fluctuation events or bursts (i.e. blobs and holes). The non-diffusive character of turbulence spreading is thus elucidated. The turbulence spreading velocity (or mean jet velocity) manifests a linear correlation with the skewness of density fluctuations, and increases with the auto-correlation time of density fluctuations. Turbulence spreading by positive density fluctuations is outward, while spreading by negative density fluctuations is inward. The degree of symmetry breaking between outward propagating blobs and inward propagating holes increases with the amplitude of density fluctuations. Thus, blob-hole asymmetry emerges as crucial to turbulence spreading. These results highlight the important role of intermittent convective events in conveying the spreading of turbulence, and constitute a fundamental challenge to existing diffusive models of spreading.

关键词： edge plasma turbulence spreading non-diffusive blobs holes

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Blob velocities and sizes in the Alcator C-Mod scrape-off layer for ohmic and high confinement mode plasmas

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NUCLEAR MATERIALS AND ENERGY 2025年 43卷

作者： Helgeland, A. D. Losada, J. M. Terry, J. L. Garcia, O. E. UiT Arctic Univ Norway Dept Phys & Technol N-9037 Tromso Norway MIT Plasma Sci & Fus Ctr Cambridge MA 02139 USA

An improved time delay estimation method is used to calculate the velocity of cross-field blob motion in the scrape-off layer of Alcator C-Mod for an ohmic and two high confinement (H-mode) plasmas;an edge localized mode free and an enhanced D-alpha H-mode. The gas puff imaging data analysis results are interpreted in the framework of a stochastic model that describes the fluctuations as a super-position of uncorrelated blob-like structures. In all confinement modes investigated, the scrape-off layer is dominated by large amplitude, blob-like filaments moving radially outwards with velocities in the range from 400 to 1000 m/s. blobs in high confinement mode plasmas have similar velocities and sizes as in ohmic plasma, which is consistent with the close similarity of conditionally averaged burst shapes and frequency spectra for the confinement modes investigated.

关键词： Alcator C-mod Scrape-off layer blobs Turbulence Transport Fluctuations Stochastic modeling

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Blob properties in I-mode and ELM-free H-mode compared to L-mode on EAST

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Plasma Science and Technology 2023年第4期25卷 51-60页

作者：汪平胡广海王亮颜宁仲小明徐国盛冯喜叶扬丁根凡余林刘阿娣段艳敏李二众徐立清刘海庆丁锐张斌李妙辉丁伯江秦成明张新军王晓洁吕波张凌吴茗甫臧庆林新邹晓岚宋云涛 Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People’s Republic of China University of Science and Technology of China Hefei 230026People’s Republic of China Institute of Energy Hefei Comprehensive National Science CentreHefei 230031People’s Republic of China Shenzhen University Shenzhen 518061People’s Republic of China CEA IRFMF-13108 St Paul Les DuranceFrance

The blob properties in I-mode and ELM-free H-mode plasmas compared to L-mode have been investigated on the EAST tokamak,including the blob detection rate Nb,sizeδb,lifetimeτb and radial velocity vr,*** blob properties in L-mode and I-mode are similar,and those in ELM-free H-mode are different to *** blob Nbis smaller whileτbis larger in *** experimental blob sizeδband velocity scalings vr,b-δb show a good agreement with the theoretical *** variation in blob properties during the L-I and H-L transitions,and their relations to the scrape-off layer(SOL)density,edge and SOL turbulence,and SOL collisionality are *** suppression of the edge(inside the last closed flux surface)turbulence is not reflected in the blob behavior,while the blob detection rate shows a correlation with the SOL density and its low-frequency(3–50 kH z)*** addition,the blob detection rate is found to increase with the divertor collisionalityΛdiv,indicating a dependence of blob behavior onΛ*** differences in blob detection rates among the three operating regimes might be due to their different SOL densities and *** investigation contributes to understanding the influences of edge and SOL plasma parameters on the blob behavior.

关键词： blobs I-mode ELM-free H-mode lithium beam emission spectroscopy EAST

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Effect of Polar Cap Patches on the High-Latitude Upper Thermospheric Winds

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JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 2024年第8期129卷

作者： Cai, L. Aikio, A. Oyama, S. Ivchenko, N. Vanhamaki, H. Virtanen, I. Buchert, S. Mekuriaw, M. L. Zhang, Y. Univ Oulu Space Phys & Astron Oulu Finland Nagoya Univ Inst Space Earth Environm Res Nagoya Japan Natl Inst Polar Res Tachikawa Japan KTH EECS Space & Plasma Phys Stockholm Sweden Uppsala Univ Uppsala Sweden Johns Hopkins Univ Appl Phys Lab Laurel MD USA

This study focuses on the poorly known effect of polar cap patches (PCPs) on the ion-neutral coupling in the F-region. The PCPs were identified by total electron content measurements from the Global Navigation Satellite System (GNSS) and the ionospheric parameters from the Defense Meteorological Satellite Program spacecraft. The EISCAT incoherent scatter radars on Svalbard and at Troms & oslash;, Norway observed that PCPs entered the nightside auroral oval from the polar cap and became plasma blobs. The ionospheric convection further transported the plasma blobs to the duskside. Simultaneously, long-lasting strong upper thermospheric winds were detected in the duskside auroral oval by a Fabry-Perot Interferometer (FPI) at Troms & oslash;and in the polar cap by the Gravity Recovery and Climate Experiment satellite. Using EISCAT ion velocities and plasma parameters as well as FPI winds, the ion drag acting on neutrals and the time constant for the ion drag could be estimated. Due to the arrival of PCPs/blobs and the accompanied increase in the F-region electron densities, the ion drag is enhanced between about 220 and 500 km altitudes. At the F peak altitudes near 300 km, the median ion drag acceleration affecting neutrals more than doubled and the associated median e-folding time decreased from 4.4 to 2 hr. The strong neutral wind was found to be driven primarily by the ion drag force due to large-scale ionospheric convection. Our results provide a new insight into ionosphere-thermosphere coupling in the presence of PCPs/blobs. This study investigates how the evolution of the polar cap patches (PCPs) affects the upper layer of the Earth's atmosphere, termed the thermosphere. PCPs are dense patches of charged particles that move from the dayside to the nightside of the high-latitude ionosphere through the polar cap region. Using the measurements by multiple ground-based instruments and satellites, this study found that PCPs can enhance the formation of strong upper th

关键词： upper thermospheric wind polar cap patches ionosphere-thermosphere ion-neutral coupling blobs high-latitude electrodynamics

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Experimental investigation of scrape-off layer blob high density transition in L-mode plasmas on EAST

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Plasma Science and Technology 2022年第7期24卷 129-136页

作者： Ping WANG Guanghai HU Ning YAN Guosheng XU Lingyi MENG Zhikang LU Lin YU Manni JIA Yifeng WANG Liang CHEN Heng LAN Xiang LIU Mingfu WU Liang WANG Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031People's Republic of China University of Science and Technology of China Hefei 230026People's Republic of China College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060People's Republic of China Advanced Energy Research Center Shenzhen UniversityShenzhen 518060People's Republic of China Institute of Energy Hefei Comprehensive National Science CentreHefei 230031People's Republic of China

Lithium Beam Emission Spectroscopy systems in the outer midplane and divertor Langmuir probe arrays embedded in the divertor target plates,are utilized to investigate the scrape-off layer(SOL)blob transition and its relation with divertor detachment on *** blob transition in the near SOL is observed during the density ramp-up *** the plasma density,normalized to the Greenwald density limit,exceeds a threshold of f_(GW)~0.5,the blob size and lifetime increases by 2–3 times,while the blob detection rate decreases by about 2 *** addition,a weak density shoulder is observed in the near SOL region at the same density *** analysis indicates that the divertor detachment is highly correlated with the blob transition,and the density threshold of blob transition is consistent with that of the access to the outer divertor *** potential physical mechanisms are *** results could be useful for the understanding of plasma-wall interaction issues in future devices that will operate under a detached divertor and high density conditions(over the blob transition threshold).

关键词： blobs divertor detachment L-mode EAST

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On the origin of plasma density blobs

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PHYSICS LETTERS A 2016年第46期380卷 3905-3907页

作者： Krasheninnikov, S. I. Univ Calif San Diego 9500 Gilman Dr La Jolla CA 92093 USA

By keeping nonlinear Boltzmann factor in electron density dependence on electrostatic potential it is demonstrated that large plasma density blobs, often seen in experiment inside separatrix, can exist within the framework of drift wave dynamics. The estimates show that plasma density in a blob can be 3 times higher that average plasma density, but hardly exceeds this limit, which in a ball park is in agreement with experimental observations. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Plasma Drift waves blobs

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