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Microseism Variations in Response to Antarctic Seasonal Changes in Sea Ice Extent

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Earthquake Research in China 2020年第2期34卷 264-284页

作者： XU Xiaoqing LIN Jianmin FANG Sunke Marine Acoustics and Remote Sensing laboratory Zhejiang Ocean UniversityZhoushan 316021China key laboratory of ocean observation-imaging testbed of zhejiang province Ocean CollegeZhejiang UniversityZhoushan 316021China State key laboratory of Marine Geology School of Ocean and Earth ScienceTongji UniversityShanghai 200092China

The temporal and spatial distributions of Antarctic sea ice play important roles in both the generation mechanisms and the signal characteristics of microseisms. This link paves the way for seismological investigations of Antarctic sea ice. Here we present an overview of the current state of seismological research about microseisms on Antarctic sea ice. We first briefly review satellite remote-sensing observations of Antarctic sea ice over the past 50 years. We then systematically expound upon the generation mechanisms and source distribution of microseisms in relation to seismic noise investigations of sea ice, and the characteristics of Antarctic microseisms and relationship with sea ice variations are further analyzed. We also analyze the continuous data recorded at seismic station BEAR in West Antarctica from 2011 to 2018 and compare the microseism observations with the corresponding satellite remotesensing observations of Antarctic sea ice. Our results show that:(1) the microseisms from the coastal regions of West Antarctica exhibit clear seasonal variations,SFM with maximum intensities every April-May and minimum intensities around every October-November;while DFM intensities peak every February-March,and reach the minimum around every October. Comparatively,the strong seasonal periodicity of Antarctic sea ice in better agreement with the observed DFM;and(2) microseism decay is not synchronous with sea ice expansion since the microseism intensity is also linked to the source location,source intensity(e. g.,ocean storms,ocean wave field),and other factors. Finally, we discuss the effect of Southern Annular Mode on Antarctic sea ice and microseisms,as well as the current limitations and potential of employing seismological investigations to elucidate Antarctic sea ice variations and climate change.

关键词： Antarctic sea ice Microseism Climate change Southern annular Mode

Measurement of the absorption coefficient for acoustical coating samples using multi-channel inverse filter

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Chinese Journal of Acoustics 2020年第3期39卷 372-386页

作者： SONG Hao MA Xiaochen LI Jun LI Jianlong Systems Engineering Research Institute of Chinese Shipbuilding Industry Beijing 100036 College of Information Science and Electronic Engineering Zhejiang UniversityHangzhou 310027 key laboratory of ocean observation-imaging testbed of zhejiang province Zhoushan 316021

A method of measuring the absorption coefficient for acoustical coating samples by use of the multi-channel inverse filter based on the least square method was ***,the responses of the circuit channels and the underwater acoustical channels are estimated,the retransmitted inverse signals for the multiple transducers can be estimated using the least square method,and the cost function constructed by the multi-channel inverse filtering theory can be ***,by retransmitting the inverse signals,the incident signal at the position of the acoustical coating sample is focused with high resolution,low level of side lobes and a narrow pulse signal in temporal domain,which improves the measurement accuracy of the absorption coefficient for acoustical coating samples at low *** performance of the spatio-temporal focusing for the proposed method is demonstrated by *** validity of the method is verified by experiments carried out in a cylindrical tank for a steel plate sample in the frequency range 0.8-5.0 *** experimental results show that the proposed method is effective to the measurement of the absorption coefficient for acoustical coating samples in non-free field,and is especially applicable to low-frequency measurements.

关键词： coating steel inverse

Machine-vision-based acquisition,pointing,and tracking system for underwater wireless optical communications

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Chinese Optics Letters 2021年第5期19卷 25-30页

作者： Jiaming Lin Zihao Du Chuying Yu Wenmin Ge Weichao Lü Huan Deng Chao Zhang Xiao Chen Zejun Zhangu Jing Xu ptical Communications laboratory Ocean CollegeZhejiang UniversityZhoushan 316021China key laboratory of ocean observation-imaging testbed of zhejiang province Ocean CollegeZhejiang UniversityZhoushan 316021China The Engineering Research Center of oceanic Sensing Technology and Equipment Ministry of Education Zhejiang UniversityZhoushan 316021China

Due to the proliferation of underwater vehicles and sensors,underwater wireless optical communication(UWOC)is a key enabler for ocean exploration with a strong reliance on short-range bandwidth-intensive communications.A stable optical link is of primary importance for UWOC.A compact,low-power,and low-cost acquisition,pointing,and tracking(APT)system is proposed and experimentally demonstrated to realign the optical link within 0.04 s,even when the UWOC transmitter and receiver are in relative *** system successfully achieves rapid auto-alignment through a 4 m tap water channel with a relatively large number of ***,the required minimum illumination value is measured to be as low as7.1 lx,implying that the proposed APT scheme is robust to dim underwater ***,mobility experiments are performed to verify the performance of the APT *** proposed system can rapidly and automatically align moving targets in complex and unstable underwater environments,which can potentially boost the practical applications of UWOC.

关键词： acquisition pointing and tracking underwater wireless optical communication

Effects of sediment acoustic characteristics on low-frequency acoustic field distribution in shallow water

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Chinese Journal of Acoustics 2021年第1期40卷 46-62页

作者： ZHU Hanhao XIAO Rui ZHU Jun TANG Jun ZHANG Haigang ZHENG Guangxue Institute of Marine Science and Technology Zhejiang Ocean UniversityZhoushan 316022 State key laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190 Institute of Naval Architecture and Mechanical-Electrical Engineering Zhejiang Ocean UniversityZhoushan 316022 key laboratory of ocean observation-imaging testbed of zhejiang province Zhejiang UniversityZhoushan 316021 College of Underwater Acoustic Engineering Harbin Engineering UniversityHarbin 150001

Most of the published literatures on low-frequency underwater sound propagation are focused on the sound propagation features in the water column,while studies on sound propagation features in the sediment layer or the semi-infinite basement are *** this paper,based on the wave equation,a computational model for sound energy flux in the sediment layer and the basement as well as in the water column is proposed under a cylindrical coordinate *** this basis,the effects of various sediment acoustic parameters on the sound energy distribution and the corresponding mechanisms are elaborated through numerical examples and acoustic *** results reveal that,in a situation where sediment P-wave speed>water sound speed> sediment S-wave speed,the greater the values of density and P-wave speed in sediment,the more likely it is that the sound energy remains in the water column without leaking to the sea ***,the influence of the variation of S-wave speed is *** influence on the sound propagation in the fluid layer is approximately negligible if the sediment layer is sufficiently thick.

关键词： basement shallow thick

Method for the distinguish of normal modes in shallow water under near field

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Chinese Journal of Acoustics 2020年第3期39卷 300-314页

作者： ZHU Hanhao XIAO Rui ZHU Jun ZHENG Guangxue TANG Jun TANG Yunfeng Institute of Marine Science and Technology Zhejiang Ocean UniversityZhoushan 316022 State key laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190 Institute of Naval Architecture and Mechanical-electrical Engineering Zhejiang Ocean UniversityZhoushan 316022 key laboratory of ocean observation-imaging testbed of zhejiang province Zhejiang UniversityZhoushan 316021 College of Underwater Acoustic Engineering Harbin Engineering UniversityHarbin 150001

This paper proposes a method to distinguish the normal modes in shallow water under near *** method,which is based on frequency-wavenumber(F-K)transform,employs the 2D matrix comprising near field horizontal multi-channel *** signals are transformed from the time-space domain to the frequency-wavenumber domain,and the normal modes in the signals are distinguished by extracting the wavenumbers component at each frequency for each order in the frequency-wavenumber *** practical reliability and validity of this method are verified by performing numerical simulation and a tank experiment,and the results showed that the normal modes in the Pekeris waveguide below 200 Hz could be obtained reliably at 500 m by using this method.

关键词： waveguide shallow normal

具有超薄Al_(2)O_(3)钝化层的高性能近红外PtSe_(2)/n-Ge异质结光电探测器

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Science China Materials 2023年第7期66卷 2777-2787页

作者：朱清海陈叶馨朱笑东孙一军程志渊徐敬徐明生 School of Micro-Nano Electronics State Key Laboratory of Silicon MaterialsZhejiang UniversityHangzhou 310027China State key laboratory of Silicon Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China College of Information Science&Electronic Engineering Zhejiang UniversityHangzhou 310027China key laboratory of ocean observation-imaging testbed of zhejiang province Ocean CollegeZhejiang UniversityZhoushan 316021China

二维(2D)材料正被广泛用于宽带响应光电探测器(PD).然而,基于2D材料的宽带响应PD通常对红外波长的响应较差.在此,我们报告了垂直PtSe_(2)/超薄Al_(2)O_(3)/Ge PD在近红外照明下的优异光响应性能.我们直接硒化沉积在Al_(2)O_(3)/Ge上的P... 详细信息

二维(2D)材料正被广泛用于宽带响应光电探测器(PD).然而,基于2D材料的宽带响应PD通常对红外波长的响应较差.在此,我们报告了垂直PtSe_(2)/超薄Al_(2)O_(3)/Ge PD在近红外照明下的优异光响应性能.我们直接硒化沉积在Al_(2)O_(3)/Ge上的Pt膜以形成PtSe_(2)层.超薄Al_(2)O_(3)钝化层起到表面改性的作用,有效地削弱了光生载流子的复合.在1550 nm的光照下,我们的PtSe_(2)/超薄Al_(2)O_(3)/Ge PD的工作面积为50μm×50μm,并在零偏压下获得了4.09 A W^(-1)、32.6/18.9μs的大响应度和快速上升/下降时间.在-5 V的外加电压下,PtSe_(2)/超薄Al_(2)O_(3)/Ge PD的响应度和响应速度分别高达38.18 A W^(-1)和9.6/7.7μs.我们发现器件的工作面积对光响应特性有很大的影响.此外,我们证明PtSe_(2)/超薄Al_(2)O_(3)/Ge PD阵列在室温下显示出了优异的紫外、可见光和红外成像能力.我们的研究表明,PtSe_(2)/超薄Al_(2)O_(3)/Ge异质结在设计具有优异近红外响应性能的新兴宽带光电子器件方面具有巨大的应用前景.

关键词： 2D PtSe_(2) germanium passivation layer near-infrared photodetector

水声FBMC-OQAM通信的时变信道估计与符号检测

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哈尔滨工程大学学报（英文版） 2023年第3期22卷 636-649页

作者：陆雪松江雨林李静萱魏艳涂星滨瞿逢重 key laboratory of ocean observation-imaging testbed of zhejiang province Zhoushan 316021China Engineering Research Center of oceanic Sensing Technology and Equipment Ministry of EducationZhejiang UniversityZhoushan 316021China

Filter bank multicarrier(FBMC)systems with offset quadrature amplitude modulation(OQAM)need long data blocks to achieve high spectral ***,the transmission of long data blocks in underwater acoustic(UWA)communication systems often encounters the challenge of time-varying *** paper proposes a time-varying channel tracking method for short-range high-rate UWA FBMC-OQAM communication ***,a known preamble is used to initialize the channel estimation at the initial time of the signal ***,the estimated channel is applied to detect data symbols at several symbol *** detected data symbols are then reused as new pilots to estimate the next time *** the above steps,the unified transmission matrix model is extended to describe the time-varying channel input-output model in this paper and is used for symbol *** results show that the channel tracking error can be reduced to less than−20 dB when the channel temporal coherence coefficient exceeds 0.75 within one block period of FBMC-OQAM *** with conventional known-pilot-based methods,the proposed method needs lower system overhead while exhibiting similar time-varying channel tracking *** sea trial results further proved the practicability of the proposed method.

关键词： FBMC-OQAM Underwater acoustic communications Channel estimation Time-varying channel Data reuse Iterative estimation

基于信道短化和圆球译码的水声通信迭代序列检测

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哈尔滨工程大学学报（英文版） 2024年第1期23卷 238-246页

作者：瞿逢重方浩涂星滨魏艳章旻昊杨劭坚 The Engineering Research Center of oceanic Sensing Technology and Equipment Ministry of EducationZhoushan 316021China the key laboratory of ocean observation-imaging testbed of zhejiang province Zhejiang UniversityZhoushan 316021China Hainan Institute of zhejiang University Sanya 572025China

The demand for high-data-rate underwater acoustic communications(UACs)in marine development is increasing;however,severe multipaths make demodulation a *** decision feedback equalizer(DFE)is one of the most popular equalizers in UAC;however,it is not the optimal *** maximum likelihood sequence estimation(MLSE)is the optimal algorithm,its complexity increases exponentially with the number of channel taps,making it challenging to apply to ***,this paper proposes a complexity-reduced MLSE to improve the bit error rate(BER)performance in multipath *** the proposed algorithm,the original channel is first shortened using a channel-shortening method,and several dominant channel taps are selected for ***,sphere decoding(SD)is performed in the following *** are applied to eliminate inter-symbol interference caused by weak channel *** simulation and sea experiment demonstrate the superiority of the proposed *** simulation results show that channel shortening combined with SD can drastically reduce computational complexity,and iterative SD performs better than DFE based on recursive least squares(RLS-DFE),DFE based on improved proportionate normalized least mean squares(IPNLMS-DFE),and channel estimation-based DFE(CE-DFE).Moreover,the sea experimental results at Zhairuoshan Island in Zhoushan show that the proposed receiver scheme has improved BER performance over RLSDFE,IPNLMS-DFE,and *** with the RLS-DFE,the BER,after five iterations,is reduced from 0.0076 to 0.0037 in the 8–12 k Hz band and from 0.1516 to 0.1145 in the 13–17 k Hz band at a distance of 2000 ***,the proposed algorithm makes it possible to apply MLSE in UAC in practical scenarios.

关键词： Underwater acoustic communications(UACs) Maximum likelihood sequence estimation(MLSE) Channel shortening Sphere decoding(SD) Iterative detection

observational study of super typhoon Meranti (2016) using satellite, surface drifter, Argo float and reanalysis data

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Acta oceanologica Sinica 2021年第1期40卷 70-84页

作者： Hui Chen Shuang Li Hailun He Jinbao Song Zheng Ling Anzhou Cao Zhongshui Zou Wenli Qiao ocean College Zhejiang UniversityZhoushan 316021China State key laboratory of Satellite ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China key laboratory of Coastal Resources and Environment in Continental and Deep Sea of Department of Education of Guangdong ProvinceGuangdong Ocean UniversityZhanjiang 524088China

The present work describes the basic features of super typhoon Meranti(2016)by multiple data *** mainly focus on the upper ocean response to Meranti using multiplatform satellites,in situ surface drifter and Argo floats,and compare the results with the widely used idealized wind vortex model and reanalysis *** pre-existing meso-scale eddy provided a favor underlying surface boundary condition and also modulated the upper ocean response to *** show that the maximum sea surface cooling was 2.0℃after *** satellite surface wind failed to capture the core structure of Meranti as the idealized wind vortex model *** to the observation of sea surface drifters,the near-inertial currents were significantly enhanced during the passage of *** temperature and salinity profiles from Argo floats revealed both the mixed-layer extension and subsurface upwelling induced by *** comparison results show that the sea surface temperature and surface wind in the reanalysis datasets differs from those in remote sensing *** surface cooling is similar in both satellite and in situ observation,and sea surface salinity response has a lower correlation with the precipitation rate.

关键词： super typhoon satellite data sea surface temperature surface wind