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Determining the effective elastic thickness through cross-correlation between isostatic disturbances

Geodesy and Geodynamics 2024年第3期15卷 241-251页

作者： Nelson Ribeiro-Filho Cristiano Mendel Martins Raissa Moraes Baldez Ivaldevingles Rodrigues de Souza Júnior Franck Eitel Kemgang Ghomsi Instituto Federal do Pará(IFPA) AltamiraParáBrazil Universidade Federal do Pará(UFPA) BelemParáBrazil Nansen-Tutu Center for Marine Environmental Research Department of OceanographyUniversity of Cape TownSouth Africa Geodesy Research Laboratory National Institute of CartographyYaoundeCameroon

The elastic thickness parameter was estimated using the mobile correlation technique between the observed isostatic disturbance and the gravity disturbance calculated through direct gravimetric modeling. We computed the vertical flexure value of the crust for a specific elastic thickness using a given topographic dataset. The gravity disturbance due to the topography was determined after the calculation. A grid of values for the elastic thickness parameter was generated. Then, a moving correlation was performed between the observed gravity data(representing actual surface data) and the calculated data from the forward modeling. The optimum elastic thickness of the particular point corresponded to the highest correlation coefficient. The methodology was tested on synthetic data and showed that the synthetic depth closely matched the original depth, including the elastic thickness value. To validate the results, the described procedure was applied to a real dataset from the Barreirinhas Basin, situated in the northeastern region of Brazil. The results show that the obtained crustal depth is highly correlated with the depth from known models. Additionally, we noted that the elastic thickness behaves as expected, decreasing from the continent towards the ocean. Based on the results, this method has the potential to be employed as a direct estimate of crustal depth and elastic thickness for any region.

关键词： Isostasy Elastic thickness Isostatic disturbance Moho depth cross-correlation

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RESEARCH ON THE ALGORITHM OF BINARY IMAGE cross-correlation FOR UNSTEADY FLOW FIELD MEASUREMENT

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Acta Mechanica Sinica 1999年第1期15卷 32-38页

作者：阮晓东宋向群 YamamotoFujio The State Key Laboratory of Fluid Power Transmission & Control Zhejiang UniversityHangzhou 310027China Department of Mechanical Engineering Fukui UniversityFukui 910-8507Japan

The algorithm of Binary Image cross-correlation (BICC) was developed to measure the unsteady flow field. A vortex flow field was used to test the algorithm by numerical simulation. The results show that BICC is an effective algorithm for particle identification from consecutive images, the accurate velocity vector field can be obtained. The real velocity field in a valve chamber was measured by BICC in this study. From the full-field velocity information, the pressure and vorticity fields were also extracted by post-processing. (Edited author abstract) 6 Refs.

关键词： PIV cross-correlation particle identification post-processing

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CONDITIONAL AVERAGING OF TR-PIV MEASUREMENTS OF WAKE BEHIND SQUARE CYLINDER USING AN IMPROVED cross-correlation APPROACH

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Journal of Hydrodynamics 2010年第1期22卷 29-34页

作者： YU Jun SHI Liu-liu WANG Wei-zhe LIU Ying-zheng Key Laboratory for Power Machinery and Engineering of Ministry of Education Shanghai Jiao Tong University Shanghai 200240 China

An improved phase averaging method based on cross-correlation of the instantaneous velocity field determined by TR-PIV measurements is proposed in this article. A Time-Resolved Particle Image Velocimetry （TR-PIV） is used to measure the two-dimensional wake behind the square cylinder. The phase signals associated with the deterministic appearance of the Karman vortex street are obtained by calculating the correlation matrix of the low-pass filtered velocity field, and can provide the complete information of the phase-averaged wake flow. The results show the advantages of the enhanced methodology in extracting the quasi-periodic flow patterns related to the shedding coherent structures without using additional reference signals.

关键词： PIV cross-correlation coherent structure phase averaging

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AN IMPROVED cross-correlation METHOD FOR(DIGITAL)PARTICLE IMAGE VELOCIMETRY

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Acta Mechanica Sinica 2001年第4期17卷 332-339页

作者：翁文国范维澄廖光煊秦俊 State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230026China

An improved method that brings enhancement in accuracy for the interrogation of (digital) PIV images is described in this paper. This method is based on cross-correlation with discrete window offset, which makes use of a translation of the second interrogation window and rebuilds it considering rotation and shear. The displacement extracted from PIV images is predicted and corrected by means of an iterative procedure. In addition, the displacement vectors are validated at each intermediate of the iteration process. The present improved cross-correlation method is compared with the conventional one in accuracy by interrogation of synthetic and real (digital) PIV images and the interrogation results are discussed.

关键词： PIV DPIV cross-correlation discrete window offset

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Reconstruction of sub cross-correlation cancellation technique for unambiguous acquisition of BOC(kn, n) signals

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Journal of Systems Engineering and Electronics 2019年第5期30卷 852-860页

作者： JI Yuanfa CHEN Xiaoqian FU Qiang SUN Xiyan ZHEN Weimin Guangxi Key Laboratory of Precision Navigation Technology and Application Guilin University of Electronic TechnologyGuilin 541004China National&Local Joint Engineering Research Center of Satellite Navigation Positioning and Location Service Guilin 541004China Key Laboratory of Radio Wave Environment and Modeling Technology Qingdao 266000China

In order to solve the problem of ambiguous acquisition of BOC signals caused by its property of multiple peaks,an unambiguous acquisition algorithm named reconstruction of sub cross-correlation cancellation technique(RSCCT)for BOC(kn,n)signals is proposed.In this paper,the principle of signal decomposition is combined with the traditional acquisition algorithm structure,and then based on the method of reconstructing the correlation function.The method firstly gets the sub-pseudorandom noise(PRN)code by decomposing the local PRN code,then uses BOC(kn,n)and the sub-PRN code cross-correlation to get the sub cross-correlation function.Finally,the correlation peak with a single peak is obtained by reconstructing the sub cross-correlation function so that the ambiguities of BOC acquisition are removed.The simulation shows that RSCCT can completely eliminate the side peaks of BOC(kn,n)group signals while maintaining the narrow correlation of BOC,and its computational complexity is equivalent to sub carrier phase cancellation(SCPC)and autocorrelation side-peak cancellation technique(ASPeCT),and it reduces the computational complexity relative to BPSK-like.For BOC(n,n),the acquisition sensitivity of RSCCT is 3.25 dB,0.81 dB and 0.25 dB higher than binary phase shift keying(BPSK)-like,SCPC and ASPeCT at the acquisition probability of 90%,respectively.The peak to average power ratio is 1.91,3.0 and 3.7 times higher than ASPeCT,SCPC and BPSK-like at SNR=–20 dB,respectively.For BOC(2n,n),the acquisition sensitivity of RSCCT is 5.5 dB,1.25 dB and 2.69 dB higher than BPSK-like,SCPC and ASPeCT at the acquisition probability of 90%,respectively.The peak to average power ratio is 1.02,1.68 and 2.12 times higher than ASPeCT,SCPC and BPSK-like at SNR=–20 dB,respectively.

关键词： signal decomposition sub cross-correlation reconstructingcorrelation function acquisition performance

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Fusion of Gaussian Mixture Models for Maneuvering Target Tracking in the Presence of Unknown cross-correlation

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Chinese Journal of Electronics 2016年第2期25卷 270-276页

作者： ZHU Hongyan GUO Kai CHEN Shuo School of Electronic and Information Engineering Xi'an Jiaotong University China Electronics Technology Group Corporation No.28 Research Institute

The paper addresses the problem of estimation fusion for maneuvering target tracking in the presence of unknown cross-correlation. To improve the fusion accuracy, two major points are concerned. Firstly, the Interacting multiple model(IMM) estimator is performed for each sensor, and the local estimate is represented by a Gaussian mixture model instead of a Gaussian density to keep more details of the local tracker. Next, a close-formed solution of fusing two Gaussian mixtures in the Covariance intersection(CI) framework is derived to cope with the unknown cross-correlation of local estimation errors. Experimental results demonstrate that the proposed approach provides some improvements in the fusion accuracy over the competitive methods.

关键词： Gaussian mixture model(GMM) Estimation fusion Interacting multiple model(IMM) Covariance intersection(CI) cross-correlation

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MEASURING SEA ICE DRIFT VIA cross-correlation OF RADAR ICE IMAGES

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Journal of Hydrodynamics 2004年第6期16卷 716-720页

作者： SUNHe-quan SHENYong-ming QiuDa-hong StateKeyLaboratoryofCoastalandOffshoreEngineering DalianUniversityofTechnologyDalian116023China

The motion of sea ice has a great effect on winter navigation, and oil fieldexploration in the Bohai Sea. It is very important to measure the ice drift accurately andefficiently. As a practical technique, radar imagery has been used for sea ice monitoring andforecasting for a long time.Combining with the radar imagery and cross-correlation technique, a newmeasurement method based on the cross-correlation of radar ice images is specified in this paper toobtain full field measurement of sea ice drift. The theory and fast implementation ofcross-correlation are presented briefly in the paper, including the filtering method to modify theinvalid vectors. To show deeply the validity of the present method, the velocity maps of sea icedrift are provided in the paper, which are calculated from the radar images grabbed in the LiaodongGulf. The comparison with the traditional tracing method is also conducted.

关键词： sea ice drift radar ice image cross-correlation

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A Configurable Circuit for cross-correlation in Real-Time Image Matching

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Journal of Computer Science & Technology 2017年第6期32卷 1305-1318页

作者： Quan Zhou Liang Yang Hui Cao Department of Integrated Circuit Design Xi'an Microelectronics Technology Institute Xi'an 710065 China

cross-correlation （CC） is the most time-consuming in the implementation of image matching algorithms based on the correlation method. Therefore, how to calculate CC fast is crucial to real-time image matching. This work reveals that the single cascading multiply-accumulate （CAMAC） and concurrent multiply-accumulate （COMAC） architectures which have been widely used in the past, actually, do not necessarily bring about a satisfactory time performance for CC. To obtain better time performance and higher resource efficiency, this paper proposes a configurable circuit involving the advantages of CAMAC and COMAC for a large amount of multiply-accumulate （MAC） operations of CC in exhaustive search. The proposed circuit works in an array manner and can better adapt to changing size image matching in real-time processing. Experimental results demonstrate that this novel circuit which involves the two structures can complete vast MAC calculations at a very high speed. Compared with existing related work, it improves the computation density further and is more flexible to use.

关键词： cross-correlation image matching multiply-accumulate speed-up ratio template matching

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On the cross-correlation Distribution of d-Ary Generalized Legendre-Sidelnikov Sequences

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Chinese Journal of Electronics 2018年第2期27卷 287-291页

作者： KE Pinhui YE Zhifan ZHANG Shengyuan CHANG Zuling Fujian Provincial Key Laboratory of Network Security and Cryptology Fujian Normal University School of Mathematics and Statistics Zhengzhou University

The cross-correlation distribution of constant multiple sequences of the d-ary generalized LegendreSidelnikov sequences is investigated via character sums. An upper on the cross-correlation values of the sequences is then presented. As a byproduct, the autocorrelation distribution of d-ary Sidelnikov sequence is completely determined, which is only known in a special case.

关键词： Autocorrelation cross-correlation Legendre-Sidelnikov sequence Multiplicative character Finite field

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A Fast Two-Stage Black-Box Deep Learning Network Attacking Method Based on cross-correlation

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Computers, Materials & Continua 2020年第7期64卷 623-635页

作者： Deyin Li Mingzhi Cheng Yu Yang Min Lei Linfeng Shen State Key Laboratory of Public Big Data Guizhou UniversityGuiyang550025China School of Cyberspace Security Beijing University of Posts and TelecommunicationsBeijing100876China College of New Media Beijing Institute of Graphic CommunicationBeijing102600China School of Computing Science Simon Fraser UniversityBurnabyCanada

Deep learning networks are widely used in various systems that require classification.However,deep learning networks are vulnerable to adversarial attacks.The study on adversarial attacks plays an important role in defense.Black-box attacks require less knowledge about target models than white-box attacks do,which means black-box attacks are easier to launch and more valuable.However,the state-of-arts black-box attacks still suffer in low success rates and large visual distances between generative adversarial images and original images.This paper proposes a kind of fast black-box attack based on the cross-correlation(FBACC)method.The attack is carried out in two stages.In the first stage,an adversarial image,which would be missclassified as the target label,is generated by using gradient descending learning.By far the image may look a lot different than the original one.Then,in the second stage,visual quality keeps getting improved on the condition that the label keeps being missclassified.By using the cross-correlation method,the error of the smooth region is ignored,and the number of iterations is reduced.Compared with the proposed black-box adversarial attack methods,FBACC achieves a better fooling rate and fewer iterations.When attacking LeNet5 and AlexNet respectively,the fooling rates are 100%and 89.56%.When attacking them at the same time,the fooling rate is 69.78%.FBACC method also provides a new adversarial attack method for the study of defense against adversarial attacks.

关键词： Black-box adversarial attack cross-correlation two-module

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