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Role of Horizontal Density Advection in Seasonal Deepening of the Mixed Layer in the Subtropical Southeast Pacific

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Advances in Atmospheric Sciences 2016年第4期33卷 442-451页

作者： Qinyu LIU yiqun lu Physical Oceanography Laboratory Qingdao Collaborative Innovation Center of Marine Science and TechnologyKey Laboratory of Ocean–Atmosphere Interaction and Climate in Universities of ShandongOcean University of China

The mechanisms behind the seasonal deepening of the mixed layer （ML） in the subtropical Southeast Pacific were investigated using the monthly Argo data from 2004 to 2012. The region with a deep ML （more than 175 m） was found in the region of （22°-30°S, 105°-90°W）, reaching its maximum depth （-200 m） near （27°-28°S, 100°W） in September. The relative importance of horizontal density advection in determining the maximum ML location is discussed qualitatively. Downward Ekman pumping is key to determining the eastern boundary of the deep ML region. In addition, zonal density advection by the subtropical countercurrent （STCC） in the subtropical Southwest Pacific determines its western boundary, by carrying lighter water to strengthen the stratification and form a ＂shallow tongue＂ of ML depth to block the westward extension of the deep ML in the STCC region. The temperature advection by the STCC is the main source for large heat loss from the subtropical Southwest Pacific. Finally, the combined effect of net surface heat flux and meridional density advection by the subtropical gyre determines the northern and southern boundaries of the deep ML region： the ocean heat loss at the surface gradually increases from 22~S to 35~S, while the meridional density advection by the subtropical gyre strengthens the strat- ification south of the maximum ML depth and weakens the stratification to the north. The freshwater flux contribution to deepening the ML during austral winter is limited. The results are useful for understanding the role of ocean dynamics in the ML formation in the subtropical Southeast Pacific.

关键词： mixed layer seasonal deepening Southeast Pacific heat flux density advection

Covariability of Subantarctic Mode Water and the Southern Branch of the Subtropical Indian Ocean Countercurrent in Argo Observations

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Journal of Ocean University of China 2021年第6期20卷 1316-1324页

作者： lu yiqun LIU Qinyu XIE Shang-Ping Physical Oceanography Laboratory Ocean University of China and Qingdao National Laboratory for Marine Science and TechnologyQingdao 266100China Scripps Institution of Oceanography University of California San DiegoLa JollaCalifornia 92093USA

The Subantarctic Mode Water(SAMW)forms in the deep mixed layer north of the Antarctic Circumpolar Current and spreads northward into the subtropical *** subtropical South Indian Countercurrent(SICC)flows eastward on the north flank of the thick SAMW layer within 22°-32°S from south of Madagascar at around 25°S,50°E toward western *** dynamical relation of the SAMW and the southern branch of the SICC(30°-32°S)is investigated in this work based on the monthly mean Argo data from 2004 to *** physical properties of the SAMW and its pathway from the formation region are *** of the SAMW in the Indian Ocean sector originates from the deep mixed layers of the southeastern Indian Ocean(about 40°S,85°-105°E)and moves along the subtropical *** takes around ten years to arrive east of Madagascar Island preserving its low potential vor-ticity *** a thick layer with homogeneous vertical properties,the SAMW forces the upper pycnocline to shoal,and the associated eastward shear results in the surface-intensified *** SAMW forms a tongue-shaped thickness pattern,which influ-ences the southern branch of the SICC above the northern flank of the thickest SAMW layer between 24°S and 32°*** seasonal,interannual,and decade variations of the southern branch of the SICC are closely related to the meridional gradient of the underlying SAMW *** SAMW thickened and strengthened from 2005 to 2015,thereby anchoring a strengthened *** interan-nual covariability of the SAMW and SICC further supports the SAMW’s role in driving SICC variability.

关键词： subantarctic mode water South Indian Ocean Countercurrent Argo observations long-term change interannual vari-ability

North Pacific Eastern Subtropical Mode Water simulation and future projection

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Acta Oceanologica Sinica 2015年第3期34卷 25-30页

作者： XIA Ruibin LIU Qinyu XU Lixiao lu yiqun Physical Oceanography Laboratory/Qingdao Collaborative Innovation Center of Marine Science and Technology Key Laboratory of Ocean-Atmosphere Interaction and Climate in Universities of ShandongOcean University of China

The present climate simulation and future projection of the Eastern Subtropical Mode Water （ESTMW） in the North Pacific are investigated based on the Geophysical Fluid Dynamics Laboratory Earth System Model （GFDL-ESM2M）. Spatial patterns of the mixed layer depth （MLD） in the eastern subtropical North Pacific and the ESTMW are well simulated using this model. Compared with historical simulation, the ESTMW is produced at lighter isopycnal surfaces and its total volume is decreased in the RCP8.5 runs, because the subduction rate of the ESTMW decreases by 0.82×10？6 m/s during February–March. In addition, it is found that the lateral induction decreasing is approximately four times more than the Ekman pumping, and thus it plays a dominant role in the decreased subduction rate associated with global warming. Moreover, the MLD during February–March is banded shoaling in response to global warming, extending northeastward from the east of the Hawaii Islands （20°N, 155°W） to the west coast of North America （30°N, 125°W）, with a max-imum shoaling of 50 m, and then leads to the lateral induction reduction. Meanwhile, the increased north-eastward surface warm current to the east of Hawaii helps strengthen of the local upper ocean stratification and induces the banded shoaling MLD under warmer climate. This new finding indicates that the ocean surface currents play an important role in the response of the MLD and the ESTMW to global warming.

关键词： eastern subtropical mode water global warming mixed layer depth subduction rate heat advection

DepthGAN: GAN-based depth generation from semantic layouts

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Computational Visual Media 2024年第3期10卷 505-522页

作者： Yidi Li Jun Xiao yiqun Wang Zhengda lu School of Artificial Intelligence University of Chinese Academy of SciencesBeijingChina College of Computer Science Chongqing UniversityChongqingChina

Existing GAN-based generative methodsare typically used for semantic image synthesis. Wepose the question of whether GAN-based architecturescan generate plausible depth maps and find thatexisting methods have difficulty in generating depthmaps which reasonably represent 3D scene structuredue to the lack of global geometric ***, we propose DepthGAN, a novel method ofgenerating a depth map using a semantic layout asinput to aid construction, and manipulation of wellstructured 3D scene point clouds. Specifically, wefirst build a feature generation model with a cascadeof semantically-aware transformer blocks to obtaindepth features with global structural *** our semantically aware transformer block, wepropose a mixed attention module and a semanticallyaware layer normalization module to better exploitsemantic consistency for depth features ***, we present a novel semantically weighteddepth synthesis module, which generates adaptivedepth intervals for the current scene. We generate thefinal depth map by using a weighted combination ofsemantically aware depth weights for different depthranges. In this manner, we obtain a more accuratedepth map. Extensive experiments on indoor andoutdoor datasets demonstrate that DepthGAN achievessuperior results both quantitatively and visually for thedepth generation task.

关键词： depth map generation generative model transformer scene generation

Atmospheric gaseous organic acids in winter in a rural site of the North China Plain

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Journal of Environmental Sciences 2022年第3期34卷 190-203页

作者： Xiaoyu Hu Gan Yang Yiliang Liu yiqun lu Yuwei Wang Hui Chen Jianmin Chen Lin Wang Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP^(3)) Department of Environmental Science and EngineeringFudan UniversityShanghai 200438China IRDR International Center of Excellence on Risk Interconnectivity and Governance on Weather/Climate Extremes Impact and Public Health Fudan UniversityShanghai 200433China Collaborative Innovation Center of Climate Change Nanjing 210023China Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092China

Organic acids are important contributors to the acidity of atmospheric precipitation,but their existence in the Chinese atmosphere is largely *** this study,twelve atmospheric gaseous organic acids,including C_(1)-C_(9) alkanoic acids,methacrylic acid,pyruvic acid,and benzoic acid,were observed in the suburb of Wangdu,Hebei Province,a typical rural site in the northern China plain from 16^(th) December,2018 to 22^(nd) January,2019,using a Vocus■ Proton-Transfer-Reaction time-of-flight mass spectrometer(Vocus PTR-ToF).The quantification of C_(2)-C_(4) alkanoic acids by the Vocus PTR-ToF was calibrated according to the titration of a NaOH solution by C_(2)-C_(4) alkanoic acids from home-made permeation sources,and the other organic acids except for formic acid were quantified based on the k_(cap)-sensitivity linearity in the Vocus PTR-ToF,whereas formic acid was not quantified because our instrument setting led to a significant underestimation in its *** average total concentration of eleven gaseous organic acids was 6.96±5.20 ppbv(parts per billion by volume).The average concentration of acetic acid was the highest(3.86±3.00 ppbv),followed by propanoic acid,butyric acid,and methacrylic *** straw burning was likely the dominant source of the observed gaseous organic acids according to the good correlations between acetonitrile and organic acids and between particulate K+and organic acids,and traffic emissions could also have *** episodes with continuously high concentrations of organic acids,short-distance transport dominated in Wangdu according to the backward trajectory ***,Shijiazhuang,and Hengshui areas were the main source areas based on potential source contribution function and concentration weighing track analysis.

关键词： Gaseous organic acids Vocus PTR-ToF North China plain

Atmospheric gaseous aromatic hydrocarbons in eastern China based on mobile measurements:Spatial distribution,secondary formation potential and source apportionment

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Journal of Environmental Sciences 2023年第8期130卷 102-113页

作者： Lingling Yuan Hongli Wang Yaqin Gao Guofa Ren yiqun lu Shengao Jing Wen Tan Liang Zhu Yu Shang Jing An Cheng Huang Institute of Environmental Pollution and Health School of Environmental and Chemical EngineeringShanghai UniversityShanghai 200444China State of Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Complex Shanghai Academy of Environmental SciencesShanghai 200233China Tofwerk China Nanjing 210000China

Monocyclic aromatic hydrocarbons(MAHs)and polycyclic aromatic hydrocarbons(PAHs)are both well known as hazardous air pollutants and also important anthropogenic precursors of tropospheric ozone(O3)and secondary organic aerosols(SOA).In recent years,there have been intensive studies covering MAHs emission from various sources and their behavior under stimulated photochemical *** in-situ measurements of PAHs presence and variations in ambient air are *** we conducted large geometrical scale mobile measurements for 16 aromatic hydrocarbons(AHs,including 7 MAHs and 9 PAHs)in eastern China between October 27 and November 8,*** unique dataset has allowed for some insights in terms of AHs concentration variations,accompanying chemical composition,source contributions and spatial distributions in eastern *** general,AHs showed a clear concentration variability between the south and the north of the Yangtze River Delta(YRD).The concentrations of PAHs were approximately 9%of AHs,but contributed 23%of SOA formation *** apportionment via positive matrix factorization(PMF)model revealed that industrial processes as the largest source(44%)of observed AHs,followed by solvent usage(21%),vehicle exhaust(19%),coal combustion(11%)and coking processes(6%).In the perspective of PAHs sources,coal combustion emissions were identified as the dominating factor of a share of 41%–52%in eastern *** findings complemented the simultaneously monitoring information of PAHs and MAHs in eastern China,revealed the importance of PAHs to SOA formation and highlighted the necessity of formulating strategies to reduce emissions from anthropogenic sources and reduce risks to human health.

关键词： Monocyclic/polycyclic aromatics Spatial distribution Source apportionment Eastern China Mobile measurements

NEW LASING OF CESIUM ATOMIN NOBLE GAS

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Chinese Science Bulletin 1986年第17期31卷 1213-1216页

作者： lu yiqun Anhui Institute of Optics and Fine Mechanics Academia Sinica Hefei

Since Robinowtz first found stimulated emission in the alkali vapor by means of optical pumping,Sorokin has obtained a set of stimulated emission lines using lasers of 1.06μand 7658(?)to pump Cs varpor,and *** got continuous stimulated emission using Cw dye laser to pump Cs *** simple calculation,we know that the gain from the excited state Cs(6d)to the Cs(6p)is about 10.

关键词： pumping lasing alkali excited stimulated noble moved bright eliminate 拟色

Exceptional catalytic effect of novel rGO-supported Ni-Nb nanocomposite on the hydrogen storage properties of MgH_(2)

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Journal of Materials Science & Technology 2024年第5期172卷 83-93页

作者： Samuel Guemou Liuting Zhang Shuai Li yiqun Jiang Tao Zhong Zichuan lu Ren Zhou Fuying Wu Qian Li School of Energy and Power Instrumental Analysis CenterJiangsu University of Science and TechnologyZhenjiang 212003China National Engineering Research Center for Magnesium Alloys&National Key Laboratory of Advanced Casting Technologies&College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Chongqing Institute of New Energy Storage Materials and Equipment Chongqing 401135China Max Planck Institute for Iron Research Düsseldorf 40237Germany

The design of an excellent active catalyst to improve the sluggish kinetic and thermodynamic properties of magnesium hydride(MgH_(2))remains a great challenge to achieve its practical *** this study,a novel Ni-Nb/rGO nanocomposite catalyst was successfully prepared by one-spot hydrothermal and sub-sequent calcination *** novel Ni-Nb/rGO nanocomposite exhibits an exceptional catalytic effect on improving MgH_(2) sorption ***,the onset desorption temperature of MgH_(2)+10 wt%Ni-Nb/rGO composite is reduced to 198℃,much lower than that of undoped MgH_(2)(330℃).In-terestingly,the composite can release 5.0,5.9,and 6.0 wt%H_(2) within 10 min at 245,260,and 275℃,***,the dehydrogenated MgH_(2)+10 wt%Ni-Nb/rGO composite starts to absorb hydrogen even at room temperature with approximate 2.75 wt%H_(2) uptake at 75℃under 3 MPa H_(2) pressure within 30 min and exhibits excellent stability by maintaining 6.0 wt%hydrogen content after 20 cycles at 300℃.Chou’s model suggests that the de/hydrogenation kinetics of Ni-Nb/rGO-modified MgH_(2) switches from surface penetration model to diffusion model at lower ***,the ac-tivation energies(E a)for the de/hydrogenation of MgH_(2)+10 wt%Ni-Nb/rGO are reduced to 57.8 kJ/mol and 33.9 kJ/mol,which are significantly lower than those of undoped MgH_(2).The work demonstrates that the addition of a novel ternary Ni-Nb/rGO catalyst is an effective strategy to not only boost the sorption kinetics of MgH_(2) but also maintain its cycling property.

关键词： Hydrogen storage materials Magnesium hydride Ni-Nb/rGO Kinetic analysis Catalytic mechanism

Wind-Vortex-Induced Vibrations of a Deepwater Jacket Pipe and Vibration Suppression Using a Nonlinear Energy Sink

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Journal of Ocean University of China 2024年第3期23卷 633-642页

作者： LIU Liqin YU Yongjun CHEN yiqun State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China China Classification Society Haikou 570102China

The purpose of this study is to investigate the suppression effect of a nonlinear energy sink(NES)on the wind-vortex-induced pipe vibration and explore the influence of damping,stiffness,and NES installation position on the suppression *** this work,the wind-vortex-induced vibration of an elastic pipe of a deepwater jacket was studied,and vibrations were suppressed by using an NES.A van der Pol wake oscillator was used to simulate vortex-induced force,and the dynamic equation of the pipe considering the NES was *** Galerkin method was applied to discretize the motion equation,and the vortex-induced vibration(VIV)of the pipe at reduced wind speeds was numerically *** novelty of this research is that particle swarm optimization was used to optimize the parameters of the NES to improve vibration *** influence of the installation position,nonlinear stiffness,and damping parameters of the NES on vibration suppression was *** showed that the optimized parameter combinations of the NES can effectively reduce wind-vortex-induced pipe *** installation position of the NES had a significant effect on vibration suppression,and the midpoint of the pipe was the optimal NES installation *** increase in stiffness or a 10% decrease in damping may cause vibration suppression *** results of this study provide some guidance for VIV suppression in deepwater jacket pipes.

关键词： deepwater jacket wind-vortex-induced vibration NES PSO vibration suppression effect analysis