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Accurate and fast simulation of electromagnetic waves for well-to-ground transmission in transverse isotropic media 期刊论文 OAI收割
CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION, 2023, 卷号: 66, 期号: 1, 页码: 122-130
作者: Liang PengFei; Zhen QiHui; Yun Zhe; Fu ChangMin; Wang Ruo

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收藏 | 浏览/下载：30/0 | 提交时间：2023/03/30

Moment methods Integral equation Elemetry Electromagnetic Efficient modeling

An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242 期刊论文 OAI收割
Astronomy and Astrophysics, 2020, 卷号: 641, 页码: A101
作者: HXMT

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收藏 | 浏览/下载：65/0 | 提交时间：2022/02/08

accretion accretion disks black hole physics X-rays: binaries time Astrophysics - High Energy Astrophysical Phenomena Abstract:
Aims: Flip-flops are top-hat-like X-ray flux variations, which have been observed in some transient accreting black hole binary systems, and feature simultaneous changes in the spectral hardness and the power density spectrum (PDS). They occur at a crucial time in the evolution of these systems, when the accretion disc emission starts to dominate over coronal emission. Flip-flops remain a poorly understood phenomenon, so we aim to thoroughly investigate them in a system featuring several such transitions.
Methods: Within the multitude of observations of Swift J1658.2-4242 during its outburst in early 2018, we detected 15 flip-flops, enabling a detailed analysis of their individual properties and the differences between them. We present observations by XMM-Newton, NuSTAR, Astrosat, Swift, Insight-HXMT, INTEGRAL, and ATCA. We analysed their light curves, searched for periodicities, computed their PDSs, and fitted their X-ray spectra, to investigate the source behaviour during flip-flop transitions and how the interval featuring flip-flops differs from the rest of the outburst.
Results: The flip-flops of Swift J1658.2-4242 are of an extreme variety, exhibiting flux differences of up to 77% within 100 s, which is much larger than what has been seen previously. We observed radical changes in the PDS simultaneous with the sharp flux variations, featuring transitions between the quasi-periodic oscillation types C and A, which have never been observed before. Changes in the PDS are delayed, but more rapid than changes in the light curve. Flip-flops occur in two intervals within the outburst, separated by about two weeks in which these phenomena were not seen. Transitions between the two flip-flop states occurred at random integer multiples of a fundamental period of 2.761 ks in the first interval and 2.61 ks in the second. Spectral analysis reveals the high and low flux flip-flop states to be very similar, but distinct from intervals lacking flip-flops. A change of the inner temperature of the accretion disc is responsible for most of the flux difference in the flip-flops. We also highlight the importance of correcting for the influence of the dust scattering halo on the X-ray spectra.

Image deformation based on contour using moving integral least squares 期刊论文 OAI收割
IET IMAGE PROCESSING, 2019, 卷号: 13, 期号: 1, 页码: 152-160
作者: Yu, Chong; Chen, Xi; Yin, Lei; Shu, Chang; Zhao, Li

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deformation least squares approximations optimisation image registration splines (mathematics) computational geometry feature extraction medical image processing deformation function effective image deformation methods contour image deformation method Integral Least Squares optimisation control contours desired contours intuitive deformations

Trapezoidal Rule for Computing Supersingular Integral on a Circle 期刊论文 OAI收割
JOURNAL OF SCIENTIFIC COMPUTING, 2016, 卷号: 66, 期号: 2, 页码: 740-760
作者: Li, Jin; Rui, Hongxing; Yu, Dehao

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收藏 | 浏览/下载：30/0 | 提交时间：2018/07/30

Supersingular integral Composite trapezoidal rule Error expansion Superconvergence Boundary element methods

AFMPB: An adaptive fast multipole, Poisson-Boltzmann solver for calculating electrostatics in biomolecular systems 期刊论文 OAI收割
COMPUTER PHYSICS COMMUNICATIONS, 2010, 卷号: 181, 期号: 6, 页码: 1150-1160
作者: Lu, Benzhuo; Cheng, Xiaolin; Huang, Jingfang; McCammon, J. Andrew

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收藏 | 浏览/下载：27/0 | 提交时间：2018/07/30

Poisson-Boltzmann equation Boundary integral equation Node-patch method Krylov subspace methods Fast multipole methods Diagonal translations

Analysis of a diffractive microlens using the finite-difference time-domain method (EI CONFERENCE) 会议论文 OAI收割
作者: Liu Y.; Liu H.; Liu H.; Liu H.; Liu Y.

收藏 | 浏览/下载：31/0 | 提交时间：2013/03/25

The finite-difference time-domain (FDTD) method is used as rigorous electromagnetic analysis model to calculate the field for a diffractive microlens (DML). The FDTD is used for the entire solution rather than using a near- to far-field propagation method to obtain the far-field energy distribution thus all the results are vector based. We derived a formula to calculate the magnitude of electric field which is time dependent and can be used to graphically show the light wave propagation and focusing process through a DML. Both the comparison and the integral methods are presented to obtain wave amplitude in full solution space and the distribution of light energy behind a DML is illustrated based on the wave amplitude. The formula of diffractive efficiency of the DML is derived from a time-averaged Ponyting vector which can indicate the propagation direction of light energy. Application of these formulations in the analysis of a DML example demonstrates the high accuracy and efficiency of our method. 2010 Society of Photo-Optical Instrumentation Engineers.

Correction of the non-uniformity for multi-TDICCD mosaic camera on FPGA (EI CONFERENCE) 会议论文 OAI收割
2010 International Conference on E-Product E-Service and E-Entertainment, ICEEE2010, November 7, 2010 - November 9, 2010, Henan, China
Zhu H.; Xue X.; Ma T.; Li H.; Si G.; Guo Y.

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To solve the non-uniformity problem of multi Time Delay Integral Charge Couple Device (TDICCD) mosaic camera several common non-uniformity correction methods are discussed. Secondly a non-uniformity correction algorithm is proposed and implemented on Field-Programmable Gate Array (FPGA) platform. Firstly the correction algorithm is designed. Finally the generation and definition of non-uniformity are introduced considering the fix-point processing ability of FPGA the correction algorithm is optimized properly and implemented on FPGA. The experimental results indicate that the non-uniformity can be decreased from 8.3%to 2.0% in 1s for 3-TDICCD mosaic camera's images with the proposed correction algorithm at 96TDI stage proving that this correction algorithm is of high real-time performance good practicality and satisfies the requirements of the target system. 2010 IEEE.

Earth elevation map production and high resolution sensing camera imaging analysis (EI CONFERENCE) 会议论文 OAI收割
Optoelectronic Imaging and Multimedia Technology, October 18, 2010 - October 20, 2010, Beijing, China
作者: Dai L.

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The Earth's digital elevation which impacts space camera imaging has prepared and imaging has analysed. Based on matching error that TDI CCD integral series request of the speed of image motion statistical experimental methods-Monte Carlo method is used to calculate the distribution histogram of Earth's elevation in image motion compensated model which includes satellite attitude changes orbital angular rate changes latitude longitude and the orbital inclination changes. And then elevation information of the earth's surface from SRTM is read. Earth elevation map which produced for aerospace electronic cameras is compressed and spliced. It can get elevation data from flash according to the shooting point of latitude and longitude. If elevation data between two data the ways of searching data uses linear interpolation. Linear interpolation can better meet the rugged mountains and hills changing requests. At last the deviant framework and camera controller are used to test the character of deviant angle errors TDI CCD camera simulation system with the material point corresponding to imaging point model is used to analyze the imaging's MTF and mutual correlation similarity measure simulation system use adding cumulation which TDI CCD imaging exceeded the corresponding pixel horizontal and vertical offset to simulate camera imaging when stability of satellite attitude changes. This process is practicality. It can effectively control the camera memory space and meet a very good precision TDI CCD camera in the request matches the speed of image motion and imaging. 2010 SPIE.

The multi-projection method for weakly singular Fredholm integral equations of the second kind 期刊论文 OAI收割
INTERNATIONAL JOURNAL OF COMPUTER MATHEMATICS, 2010, 卷号: 87, 期号: 14, 页码: 3254-3265
作者: Long, Guangqing; Nelakanti, Gnaneshwar

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收藏 | 浏览/下载：25/0 | 提交时间：2018/07/30

super-convergence rates multi-projection methods singularity preserving Petrov-Galerkin methods integral equations

Fast Fourier-Galerkin methods for first-kind logarithmic-kernel integral equations on open arcs 期刊论文 OAI收割
SCIENCE CHINA-MATHEMATICS, 2010, 卷号: 53, 期号: 1, 页码: 1-22
作者: Wang Bo; Wang Rui; Xu YueSheng

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收藏 | 浏览/下载：19/0 | 提交时间：2018/07/30

Dirichlet problem open arc singular boundary integral equations Fourier-Galerkin methods logarithmic potentials