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Decadal Variability of Global Ocean Significant Wave Height

Journal of Ocean University of China 2015年第5期14卷 778-782页

作者： ZHENG Chongwei ZHOU Lin SHI Weilai LI Xin HUANG Chaofan College of Meteorology and Oceanography People’s Liberation Army University of Science&Technology National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics the Chinese Academy of Sciences Dalian Naval Academy Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology

This paper presents the long-term climate changes of significant wave height(Hs) in 1958–2001 over the entire global ocean using the 45-year European Centre for Medium-Range Weather Forecasts(ECMWF) Reanalysis(ERA-40) wave data. The linear trends in Hs and regional and seasonal differences of the linear trends for Hs were calculated. Results show that the Hs exhibits a significant increasing trend of about 4.6 cm decade-1 in the global ocean as a whole over the last 44 years. The Hs changes slowly during the periods 1958–1974 and 1980–1991, while it increases consistently during the periods 1975–1980 and 1995–1998. The Hs reaches its lowest magnitude in 1975, with annual average wave height about 2 m. In 1992, the Hs has the maximum value of nearly 2.60 m. The Hs in most ocean waters has a significant increasing trend of 2–14 cm decade-1 over the last 44 years. The linear trend exhibits great regional differences. Areas with strong increasing trend of Hs are mainly distributed in the westerlies of the southern Hemisphere and the northern Hemisphere. Only some small areas show obvious decreasing in Hs. The long-term trend of Hs in DJF(December, January, February) and MAM(March, April, May) is much more stronger than that in JJA(June, July, August) and SON(September, October, November). The linear trends of the Hs in different areas are different in different seasons; for instance, the increasing trend of Hs in the westerlies of the Pacific Ocean mainly appears in MAM and DJF.

关键词： global ocean significant wave height long-term trend regional differences seasonal differences dominant season

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Gravitational wave astronomy: the current status

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science China(physics,Mechanics & Astronomy) 2015年第12期58卷 3-43页

作者： BLAIR David JU Li ZHAO ChunNong WEN LinQing CHU Qi FANG Qi CAI RongGen GAO JiangRui LIN XueChun LIU Dong WU Ling-An ZHU ZongHong REITZE David H. ARAI Koji ZHANG Fan FLAMINIO Raffaele ZHU XingJiang HOBBS George MANCHESTER Richard N. SHANNON Ryan M. BACCIGALUPI Carlo GAO Wei XU Peng BIAN Xing CAO ZhouJian CHANG ZiJing DONG Peng GONG XueFei HUANG ShuangLin JU Peng LUO ZiRen QIANG Li'E TANG WenLin WAN XiaoYun WANG Yue XU ShengNian ZANG YunLong ZHANG HaiPeng LAU Yun-Kau NI Wei-Tou School of Physics The University of Western Australia State Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences The School of Physics & Electronic Engineering Shanxi University Laboratory of All-Solid-State Light Sources Institute of Semiconductors Chinese Academy of Science State Key Laboratroy of Modern Optical Instrumentation Department of Optical Engineering Zhejiang University Laboratory of Optical Physics Institute of Physics Chinese Academy of Sciences Gravitational Wave and Cosmology Laboratory Department of Astronomy Beijing Normal University LIGO Laboratory California Institute of Technology Department of Physics University of Florida Department of Physics West Virginia University National Astronomical Observatory of Japan CSIRO Astronomy and Space Science International Centre for Radio Astronomy Research Curtin University SISSA Astrophysics Sector Institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences University of Chinese Academy of Sciences Morningside Center of Mathematics Chinese Academy of Sciences State Key Laboratory of Scientific and Engineering Computing Academy of Mathematics and Systems ScienceChinese Academy of Sciences Department of Mathematics Henan University Department of Mathematics Capital Normal University Department of Geophysics College of the Geology Engineering and Geomatics Chang'an University QUEST Centre of Quantum Engineering and Space-Time Research Leibniz Universitt Hannover Max-Planck-Institut für Gravitationsphysik(Albert Einstein Institut) Aerospace Flight Dynamics Laboratory Beijing Aerospace Control Center Qian Xuesen Laboratory of Launch Vehicle Technology Center for Gravitation and Cosmology Department of Physics Tsing Hua University

In the centenary year of Einstein's General Theory of Relativity, this paper reviews the current status of gravitational wave astronomy across a spectrum which stretches from attohertz to kilohertz frequencies. Sect. 1 of this paper reviews the historical development of gravitational wave astronomy from Einstein's first prediction to our current understanding the spectrum. It is shown that detection of signals in the audio frequency spectrum can be expected very soon, and that a north-south pair of next generation detectors would provide large scientific benefits. Sect. 2 reviews the theory of gravitational waves and the principles of detection using laser interferometry. The state of the art Advanced LIGO detectors are then described. These detectors have a high chance of detecting the first events in the near future. Sect. 3 reviews the KAGRA detector currently under development in Japan,which will be the first laser interferometer detector to use cryogenic test masses. Sect. 4 of this paper reviews gravitational wave detection in the nanohertz frequency band using the technique of pulsar timing. Sect. 5 reviews the status of gravitational wave detection in the attohertz frequency band, detectable in the polarisation of the cosmic microwave background, and discusses the prospects for detection of primordial waves from the big bang. The techniques described in sects. 1–5 have already placed significant limits on the strength of gravitational wave sources. Sects. 6 and 7 review ambitious plans for future space based gravitational wave detectors in the millihertz frequency band. Sect. 6 presents a roadmap for development of space based gravitational wave detectors by China while sect. 7 discusses a key enabling technology for space interferometry known as time delay interferometry.

关键词： gravitational waves ground based detectors pulsar timing spaced based detectors CMB

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Prediction of iliac limb occlusion after endovascular aneurysm repair for abdominal aortic aneurysm by anatomical and near-wall hemodynamic characteristics combining numerical simulation and in vitro experiment

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Computer Methods and Programs in Biomedicine 2025年 268卷 108845-108845页

作者： Zhang, Xuelan Che, Yue Li, Chunxiao Cao, Xiran Wang, Xiaoxiao Zhang, Yidan Li, Gaoyang Zhu, Jing Luo, Mingyao Shu, Chang School of Mathematics and Physics University of Science and Technology Beijing Beijing 100083 China Department of Chemical Engineering Imperial College London South Kensington Campus LondonSW7 2AZ United Kingdom State Key Laboratory of Cardiovascular Disease Center of Vascular Surgery Fuwai Hospital National Center for Cardiovascular Diseases Chinese Academy of Medical Sciences and Peking Union Medical College Beijing 100037 China Institute of Fluid Science Tohoku University 2-1-1 Katahira Aoba-ku Sendai980-8577 Japan Department of Vascular Surgery Central-China Subcenter of National Center for Cardiovascular Diseases Henan Cardiovascular Disease Center Fuwai Central-China Cardiovascular Hospital Central China Fuwai Hospital of Zhengzhou University Zhengzhou450046 China Department of Vascular Surgery Fuwai Yunnan Cardiovascular Hospital Affiliated Cardiovascular Hospital of Kunming Medical University Kunming650102 China Department of Vascular Surgery The Second Xiangya Hospital of Central South University Changsha410000 China

Background and Objective: Iliac limb occlusion (ILO) is a serious complication of endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA), and most require timely reintervention. The study aims to explore pathogenesis, risk factors and prediction models of ILO combining anatomical and near-wall hemodynamic characteristics. Methods: 75 AAA patients with EVAR (occlusion 25;patency 50) were included. Pre-EVAR and early post-EVAR anatomical (proximal neck angulation, radius, curvature, torsion and tortuosity) and near-wall hemodynamic parameters (time-averaged wall shear stress [TAWSS], oscillatory shear index [OSI] and relative residence time [RRT]) were quantified based on numerical simulation validated through in vitro experiment. The causation of ILO was investigated statistically in three perspectives: differences between patent and occluded patients, effect of EVAR and asymmetries between occluded and patent iliac arteries (IAs). A new parameter, the difference ratio of EVAR (DRE) or IAs (DRI), was proposed to evaluate the degree of changes caused by EVAR and asymmetries between bilateral IAs. Results: The occluded patients had higher TAWSS (p = 0.004) and larger torsion of common IA (p = 0.033) at pre-EVAR than patent patients. At early post-EVAR, OSI and RRT of future occluded IA were significantly higher than patent IA. The difference ratio of pre-EVAR and early post-EVAR RRT (DRE of RRT) on occluded IA was also higher than that on patent IA (p = 0.025). A prediction model for ILO (area under curve = 0.924) was developed combining anatomical and near-wall hemodynamic variables, where DRI of pre-EVAR OSI had the highest odds ratio [OR] of 5.45 (1.77‒16.74, p = 0.003), and pre-EVAR radius of external IA had the lowest OR of 0.06 (0.01‒0.45, p = 0.007). Conclusions: High TAWSS and large torsion at pre-EVAR, and excessive increase in RRT by EVAR (DRE) might induce ILO. Higher asymmetry of pre-EVAR OSI between bilateral IAs (DRI) and smaller radius o

关键词： Shear bands

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Statistical analysis and simulation method of forward scattering clutter in bistatic radar

Statistical analysis and simulation method of forward scatte...

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IET International Radar Conference 2013

作者： Chuan-fang Zhang Chang-jiang Liu Cheng Hu Xiang-rong Liu School of Information and Electronics Beijing Institute of Technology China 100081 National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing China

The research of statistical properties and simulation methods of radar clutter have vital importance to the design, simulation and development of radar systems. Based on the analysis of some experimental data of forward scattering radar (FSR) clutter, it was found that under low wind speed and narrow dynamic range, the amplitude of FSR clutter was subject to K distribution; while under high wind speed or wide dynamic range, it was subject to lognormal distribution; the clutter power spectrum was subject to the fourth-order all-pole model. With the above statistical analysis, the forward scatter coherent clutter was simulated using a method combining zero-memory nonlinear transformation with spherically invariant random process. The statistical characteristics of the simulated clutter were identical to those of the measured clutter, which verified the validity of this method.

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Periodic Structures and Its Interaction to EM Wave Spectrum, Ideas From X-Ray to MW Wave

Periodic Structures and Its Interaction to EM Wave Spectrum,...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Yunhui Tang Lu Gao Ruzhi Wang Shengjun Zhang Hang Song Yuning Zhang Xia Ai Lei Xie Luting Jiao Xiaoling Zhang Jing He Jiaqi Liu Beijing University of Technology Beijing China National Key Laboratory of Science & Technology on Test Physics and Numerical Mathematics Beijing China Beijing Institute of Space Long March Vehicle Beijing China

X-ray is an important tool for characterizing materials, which is based on the idea that all crystals are composed of atoms or molecules stacking in a particular type, basically expressing as unit cell, diffracting the incident ray with a proper type. In analogue, the periodic structures which are mostly constructed artificially show special desired properties, such as the properties of grating, frequency selective surfaces, metamaterials and metasurface. In this paper, A study was done on the insight of the relation of wave interaction with periodic structures based on X-ray diffraction and control of electromagnetic waves.

关键词： Frequency selective surfaces Stacking Electromagnetic scattering Crystals X-ray diffraction Metasurfaces Computational electromagnetics

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Dual-Polarized Filtering Antenna for Base Station Application

Dual-Polarized Filtering Antenna for Base Station Applicatio...

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International Conference on Microwave and Millimeter Wave technology Proceedings

作者： Chao Feng Ding Xiu Yin Zhang Zhi Jie Zhang Yun Fei Cao Lu Gao Jun Yang School of Electronic and Information Engineering South China University of Technology Guangzhou China The State Key Laboratory of Millimeter Waves Nanjing China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

In this paper, a broadband dual-polarized filtering dipole is proposed for base station application. Filtering response is obtained by adding simple slits on each arm of the traditional dual polarized dipole antenna. Both lower and upper stopband radiation nulls are generated. The operating bandwidth of the proposed antenna is 1.7-2.9 GHz (52%). The out-of-band suppression level is about 10 dB within 0.69-1.5 GHz and 3.3-3.8 GHz. The simulated port isolation is more than 26 dB. The proposed antenna element is suitable for potential base station applications.

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PolSAR Image Edge Detection via Structure Tensor Analysis

PolSAR Image Edge Detection via Structure Tensor Analysis

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IEEE International Geoscience and Remote Sensing Symposium

作者： Xiangrong Liu Wei Mao Shunsheng Zhang Lei Wu Wen-Qin Wang National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Sch. of Info. Comm. Engin. University of Electronic Science and Technology of China Chengdu China

The weighted structure tensor (ST) can be usually used on edge detection of multi-channel images, including polarimetric synthetic aperture radar (polSAR) images. The traditional weighting method is average weighting, each channel considered to provide the same edge information. But in fact different channels tend to contain different amount of edge information, so the traditional weighting method cannot be adopted to extract full edge information of the multi-channel images. This letter proposes a novel weighting method for ST, in which the weight of each channel is obtained by the eigenvalue-measured way. Experimental results show that the proposed method outperforms the traditional method on edge detection.

关键词： Image edge detection Eigenvalues and eigenfunctions Estimation Optical imaging Hyperspectral imaging Corner detection

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Influence of Sea Surface Temperature on the Predictability of Idealized Tropical Cyclone Intensity

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Journal of Tropical Meteorology 2021年第4期27卷 355-367页

作者： ZHONG Quan-jia LI Jian-ping LI Shu-wen WANG Yuan DING Rui-qiang ZHANG Li-feng State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 China Multispheres and Earth System(FDOMES)/Key Laboratory of Physical Oceanography/Academy of the Future Oceans Ocean University of ChinaQingdaoShandong 266100 China Laboratory for Ocean Dynamics and Climate Pilot Qingdao National Laboratory for Marine Science and TechnologyQingdaoShandong 266100 China Key Laboratory of Cloud-Precipitation Physics and Severe Storms(LACS) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 China College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101 China State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing 100875 China

The role of sea surface temperature(SST)forcing in the development and predictability of tropical cyclone(TC)intensity is examined using a large set of idealized numerical experiments in the Weather Research and Forecasting(WRF)*** results indicate that the onset time of rapid intensification of TC gradually decreases,and the peak intensity of TC gradually increases,with the increased magnitude of *** predictability limits of the maximum 10 m wind speed(MWS)and minimum sea level pressure(MSLP)are~72 and~84 hours,*** of the analyses of variance for different simulation time confirm that the MWS and MSLP have strong signal-to-noise ratios(SNR)from 0-72 hours and a marked decrease beyond 72 *** the horizontal and vertical structures of wind speed,noticeable decreases in the magnitude of SNR can be seen as the simulation time increases,similar to that of the SLP or perturbation *** results indicate that the SST as an external forcing signal plays an important role in TC intensity for up to 72 hours,and it is significantly weakened if the simulation time exceeds the predictability limits of TC intensity.

关键词： predictability nonlinear local Lyapunov exponent signal-to-noise ratios tropical cyclone intensity sea surface temperature

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Two-Dimensional Imaging With Stationary Nonuniform Frequency Diverse Array Transmitter

Two-Dimensional Imaging With Stationary Nonuniform Frequency...

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IEEE International Geoscience and Remote Sensing Symposium

作者： Xiangrong Liu Wei Mao Lei Wu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Sch. of Info. Comm. Engin. University of Electronic Science and Technology of China Chengdu China

This paper proposes a simple two-dimensional imaging via stationary nonuniform frequency diverse array (FDA) transmitter by exploiting FDA both range and angle dependent transmit beampattern. The nonuniform FDA transmitter only generates range-dependent beampattern, so that two-dimensional (range-angle dimension) imaging of targets can be achieved without the employment of moving radar platform, by jointly utilizing the only range-dependent transmitter beampattern and general single-antenna or phased-array antenna. The effectiveness of the proposed method is verified by simulation results.

关键词： Radar imaging Imaging Frequency diversity Radar antennas Transmitters Radar remote sensing

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Design and Simulation of a Planar Printed Slot Array Antenna

Design and Simulation of a Planar Printed Slot Array Antenna

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2023 IEEE International Workshop on Electromagnetics: Applications and Student Innovation Competition, iWEM 2023

作者： Xiaofei, Shi Jiaxin, Shi Jiaqi, Liu Zhongyi, Fang Lei, Wang Lizhong, Song Shandong Institute of Space Electronic Technology Yantai264003 China Harbin Institute of Technology School of Electronics and Information Engineering Harbin150001 China Harbin Institute of Technology at Weihai School of Information Science and Engineering Weihai264209 China Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Beijing100076 China Shandong Huayu Aerospace Technology Co. Ltd Yantai264003 China

ISBN: (纸本)9798350336740

This paper designs an array antenna with a planar printed structure. The antenna element adopts a rectangular slot antenna, and the antenna element is excited by a T-shaped feeding structure. The microstrip power distribution network is used to feed the antenna radiator array with equal power. The microstrip power distribution network and slot radiator array are located on top and bottom of dielectric substrate, and the array antenna is implemented by use of the printed circuit technology. In order to improve the gain, a metal reflector ground is placed below the dielectric substrate. A planar printed slot array antenna working in X band is designed. The coaxial line is used to feed the array antenna at the bottom. The whole antenna structure is easy to feed and suitable for fabrication. The designed array antenna was numerically calculated using full wave electromagnetic simulation software. At a working frequency of 10.1GHz, the voltage standing wave ratio (VSWR) of the antenna is about 1.35, and the gain is about 21.46dB. The design of the antenna scheme can be used as a reference for the actual application of engineering. © 2023 IEEE.

关键词： Slot antennas

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