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A theoretical study of the multigrid three-dimensional variational data assimilation scheme using a simple bilinear interpolation algorithm

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Acta Oceanologica Sinica 2013年第3期32卷 80-87页

作者： LI Wei XIE Yuanfu HAN Guijun Key Laboratory of State Oceanic Administration for Marine Environmental Information Technology National Marine Data and Information ServiceState Oceanic Administration NOAA Earth System Research Laboratory BoulderCO 80305-3337USA

In order to solve the so-called ＂bull-eye＂ problem caused by using a simple bilinear interpolation as an observational mapping operator in the cost function in the multigrid three-dimensional variational （3DVAR） data assimilation scheme, a smoothing term, equivalent to a penalty term, is introduced into the cost function to serve as a means of troubleshooting. A theoretical analysis is first performed to figure out what on earth results in the issue of ＂bull-eye＂, and then the meaning of such smoothing term is elucidated and the uniqueness of solution of the multigrid 3DVAR with the smoothing term added is discussed through the theoretical deduction for one-dimensional （1D） case, and two idealized data assimilation experiments （one- and two-dimensional （2D） cases）. By exploring the relationship between the smoothing term and the recursive filter theoretically and practically, it is revealed why satisfied analysis results can be achieved by using such proposed solution for the issue of the multigrid 3DVAR.

关键词： multigrid three-dimensional variational data assimilation bilinear interpolation

Using WGM2012 to Compute Gravity Anomaly Corrections of Leveling Observations in China

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Journal of Geodesy and Geoinformation Science 2023年第1期6卷 88-94页

作者： Yanhui CAI Li ZHANG Xu MA National Quality Inspecting and Testing Center of Surveying and Mapping Beijng 100830China

Gravity Anomaly Correction(GAC)is a very important term in leveling data processing.In most cases,it is troublesome for field surveyors to measure gravity when leveling.In this paper,based on the complete Bouguer Gravity Anomaly(BGA)map of WGM2012,the feasibility of replacing in-situ gravity surveying in China is investigated.For leveling application,that is to evaluate the accuracy of WGM2012 in China.Because WGM2012 is organized with a standard rectangle grid,two interpolation methods,bilinear interpolating and Inverse Distance Weighted(IDW)interpolating,are proposed.Four sample areas in China,i.e.,Hanzhong,Chengdu,Linzhi and Shantou,are selected to evaluate the systems bias and precision of WGM2012.Numerical results show the average system bias of WGM2012 BGA in west China is about-100.1 mGal(1 mGal=10^(-5) m/s^(2))and the standard deviation is about 30.7 mGal.Tests in Shantou indicate the system bias in plain areas is about-130.4 mGal and standard deviation is about 6.8 mGal.All these experiments means the accuracy of WGM2012 is limited in high mountain areas of western China,but in plain areas,such as Shantou,WGM2012 BGA map is quite good for most leveling applications after calibrating the system bias.

关键词： Bouguer Gravity Anomaly(BGA) Gravity Anomaly Correction(GAC) precise leveling WGM2012 bilinear interpolation Inverse Distance Weighted(IDW)interpolation

An image compressed sensing algorithm based on adaptive nonlinear network

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Chinese Physics B 2020年第5期29卷 243-253页

作者：郭媛陈炜敬世伟 School of Computer and Control Engineering Qiqihar UniversityQiqihar 161006China

Traditional compressed sensing algorithm is used to reconstruct images by iteratively optimizing a small number of measured values.The computation is complex and the reconstruction time is long.The deep learning-based compressed sensing algorithm can greatly shorten the reconstruction time,but the algorithm emphasis is placed on reconstructing the network part mostly.The random measurement matrix cannot measure the image features well,which leads the reconstructed image quality to be improved limitedly.Two kinds of networks are proposed for solving this problem.The first one is ReconNet’s improved network IReconNet,which replaces the traditional linear random measurement matrix with an adaptive nonlinear measurement network.The reconstruction quality and anti-noise performance are greatly improved.Because the measured values extracted by the measurement network also retain the characteristics of image spatial information,the image is reconstructed by bilinear interpolation algorithm(bilinear)and dilate convolution.Therefore a second network USDCNN is proposed.On the BSD500 dataset,the sampling rates are 0.25,0.10,0.04,and 0.01,the average peak signal-noise ratio(PSNR)of USDCNN is 1.62 dB,1.31 dB,1.47 dB,and 1.95 dB higher than that of MSRNet.Experiments show the average reconstruction time of USDCNN is 0.2705 s,0.3671 s,0.3602 s,and 0.3929 s faster than that of ReconNet.Moreover,there is also a great advantage in anti-noise performance.

关键词： compressed sensing deep learning bilinear interpolation dilate convolution

Fast bowtie effect elimination for MODIS L1B data

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The Journal of China Universities of Posts and Telecommunications 2010年第1期17卷 120-126页

作者： REN Rui-zhi,GUO Shu-xu,GU Ling-jia College of electronic science and engineering,Jilin University,Changchun 130012,China College of electronic science and engineering Jilin University Changchun 130012 China

The bowtie effect refers to geometry distortions for the moderate resolution imaging spectrum-radiometer （MODIS） level 1B （L1 B） data. Till now, to eliminate the bowtie effect, numerous methods are proposed. However, most of them have limitations in computation efficiency. Through a comparative study of existing methods, this article puts forward a fast method to eliminate the bowtie effect using the ephemeris data. In this method, the rough positions of overlapping data are first detected. Because of the influence caused by the instrarnent characters and the earth＇s curvature, the positions of overlapping data need to be rectified to obtain more precise results. The optimal rectification method used in this article is selected by comparing three methods. By using the optimal method, the rectified MODIS data can be obtained. The experiments demonstrate that the bowtie effect can be eliminated in less than 1 s. In contrast, other traditional methods spend at least 3 s, thus the proposed method is faster and more effective.

关键词： bowtie effect MODIS bilinear interpolation overlapping data rectification

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对流占优扩散问题的特征AGE方法

高等学校计算数学学报 2011年第4期33卷 347-357页

作者：钱凌志冯新龙新疆大学数学与系统科学学院石河子大学理学院数学系

引言在科学与工程计算的研究领域中,许多自然现象可以用对流扩散方程模型进行描述,例如热传导及其它扩散现象、化学反应、某些生物形态、各种粒子的输运等等.因此构造求解对流扩散问题的高性能数值解法具有非常重要的理论和应用价值.对... 详细信息

引言在科学与工程计算的研究领域中,许多自然现象可以用对流扩散方程模型进行描述,例如热传导及其它扩散现象、化学反应、某些生物形态、各种粒子的输运等等.因此构造求解对流扩散问题的高性能数值解法具有非常重要的理论和应用价值.对流占优扩散方程求解的主要困难在于对流占优项的存在以及小粘性系数情形.1982年,Douglas和Russell提出了特征差分和特征有限元方法数值求解这类问题.近年来,

关键词： convection-dominated diffusion problem characteristic-difference scheme AGE method bilinear interpolation stability

Study on Method of Correcting Tilt Car License Plate Characters

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Study on Method of Correcting Tilt Car License Plate Charact...

Study of FPGA-based Visual Detection for Pointer Dial

第十二届全国青年通信学术会议

作者： Wang Dajiang Fu Wei Zhang Yu Zhao Zhengze Information Science and Engineering College Yanshan University Hebei Qinhuangdao 066004 China

＜正＞Tilt car license plate would bring bad influences to character segmentation and character recognition in car license plate recognition system,to solve this problem,a new way for car license plate tilt correction was introduced.The new way firstly adopted an initialized threshold which was suit for car license plate and Ostu method to binaries the gray image,and divided car license plate image into the left part and the right part,calculated each white pels’ height of each part,and calculated the average height of each part,using the two average heights,the tilt degree（slope）of car license plate and the tilt angle could be figured out approximately.Rotating the tilt image by way of bilinear interpolation rotation.interpolation which follows the principle of bilinear interpolation was used for those dots which could not locate in integer coordinates,accordingly the tilt car license plate image could be corrected.Both the theory analysis and the experiment result prove that this new way can achieve the goal of tilt correction,and its anti-jamming capability is perfect.

关键词： Tilt Correction bilinear interpolation Threshold Binarization

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Study of FPGA-based Visual Detection for Pointer Dial