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Multi-objective steady-state optimization of two-chamber microbial fuel cells

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Chinese Journal of Chemical Engineering 2017年第8期25卷 1000-1012页

作者： Ke Yang yijun he Zifeng Ma Shanghai Electrochemical Energy Devices Research Center Department of Chemical Engineering Shanghai Jiao Tong University

A microbial fuel cell(MFC)is a novel promising technology for simultaneous renewable electricity generation and wastewater *** non-comparable objectives,*** density,attainable current density and waste removal ratio,are often conflicting.A thorough understanding of the relationship among these three conflicting objectives can be greatly helpful to assist in optimal operation of MFC *** this study,a multiobjective genetic algorithm is used to simultaneously maximizing power density,attainable current density and waste removal ratio based on a mathematical model for an acetate two-chamber ***,the level diagrams method is utilized to aid in graphical visualization of Pareto front and decision *** biobjective optimization problems and one three-objective optimization problem are thoroughly *** obtained Pareto fronts illustrate the complex relationships among these three objectives,which is helpful for final decision ***,the integrated methodology of a multi-objective genetic algorithm and a graphical visualization technique provides a promising tool for the optimal operation of MFCs by simultaneously considering multiple conflicting objectives.

关键词： Microbial fuel cell Multi-objective optimization Genetic algorithm Level diagrams Pareto front

Optical flow-based method to estimate internal wave parameters from X-band marine radar images

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Acta Oceanologica Sinica 2022年第9期41卷 149-157页

作者： Jinghan Wen Zhongbiao Chen yijun he School of Marine Sciences Nanjing University of Information Science&TechnologyNanjing210044China Key Laboratory of Space Ocean Remote Sensing and Applications National Satellite Ocean Application ServiceBeijing100081China

The velocity and direction of internal waves(IWs) are important parameters of the ocean,however,traditional observation methods can only obtain the average parameters of IWs for a single location or large ***,a new method based on optical flow is proposed to derive the phase velocity vectors of IWs from X-band marine radar ***,the X-band marine radar image sequence is averaged,and ramp correction is used to reduce the attenuation of gray values with increasing radial ***,the average propagation direction of the IWs is determined using the two-dimensional Fourier transform of the radar images;two radial profiles along this direction are selected from two adjacent radar images;and then,the average phase velocity of the IWs is estimated from these radial ***,the averaged radar images are processed via histogram equalization and binarization to reduce the influence of noise on the radar ***,a weighting factor is determined using the average phase velocity of a reference point;the phase velocities on the wave crest of the IWs are subsequently estimated via the optical flow ***,the proposed method is validated using X-band marine radar image sequences observed on an oil platform in the South China Sea,and the error of the phase velocity is calculated to be 0.000 3–0.073 8 m/*** application conditions of the proposed method are also discussed using two different types of IW packets.

关键词： internal wave X-band marine radar optical flow phase velocity

Simulation and future projection of the mixed layer depth and subduction process in the subtropical Southeast Pacific

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Acta Oceanologica Sinica 2021年第12期40卷 104-113页

作者： Ruibin Xia yijun he Tingting Yang School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China MNR Key Laboratory for Polar Science Polar Research Institute of ChinaShanghai 200136China Laboratory for Regional Oceanography and Numerical Modeling Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China Key Laboratory of Meteorological Disaster Ministry of EducationNanjing 210044China Joint International Research Laboratory of Climate and Environment Change Nanjing 210044China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing 210044China Nanjing Joint Institute for Atmospheric Sciences Nanjing 210008China

The present climate simulation and future projection of the mixed layer depth(MLD)and subduction process in the subtropical Southeast Pacific are investigated based on the geophysical fluid dynamics laboratory earth system model(GFDL-ESM2 M).The MLD deepens from May and reaches its maximum(>160 m)near(24°S,104°W)in September in the historical *** MLD spatial pattern in September is non-uniform in the present climate,which shows three characteristics:(1)the deep MLD extends from the Southeast Pacific to the West Pacific and leads to a"deep tongue"until 135°W;(2)the northern boundary of the MLD maximum is smoothly near 18°S,and MLD shallows sharply to the northeast;(3)there is a relatively shallow MLD zone inserted into the MLD maximum eastern boundary near(26°S,80°W)as a weak"shallow tongue".The MLD nonuniform spatial pattern generates three strong MLD fronts respectively in the three key regions,promoting the subduction *** global warming,the variability of MLD spatial patterns is remarkably diverse,rather than deepening *** all the key regions,the MLD deepens in the south but shoals in the north,strengthing the MLD *** a result,the subduction rate enhances in these *** MLD antisymmetric variability is mainly influenced by various factors,especially the potential-density horizontal advection non-uniform *** that the freshwater flux change helps to deepen the MLD uniformly in the whole basin,so it hardly works on the regional MLD *** study highlights that there are regional differences in the mechanisms of the MLD change,and the MLD front change caused by MLD non-uniform variability is the crucial factor in the subduction response to global warming.

关键词： mixed layer depth mixed layer depth front subduction ocean potential-density advection

Ocean wave parameters retrieved directly from compact polarimetric SAR data

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Acta Oceanologica Sinica 2022年第4期41卷 129-137页

作者： Yu Liu yijun he Biao Zhang School of Electronic and Information Engineering Nanjing University of Information Science&TechnologyNanjing 210044China School of Marine Science Nanjing University of Information Science&TechnologyNanjing 210044China

We aim to directly invert wave parameters by using the data of a compact polarimetric synthetic aperture radar(CP SAR)and validate the effectiveness of ocean wave parameter retrieval from the circular transmit/linear receive mode andπ/4 compact polarimetric *** data from the RADARSAT-2 fully polarimetric SAR on the C-band were used to obtain the compact polarimetric SAR images,and a polarimetric SAR wave retrieval algorithm was used to verify the sea surface wave *** the data and algorithm,there is no need to estimate complex hydrodynamic modulation transfer functions,even at large radar incidence ***,the radar backscattering cross-sections and backscattering cross-section of the radar linearly polarized with any polarization orientation angle were calculated in the two compact polarimetric SAR ***,the wave slopes along the azimuth direction and the range direction were calculated directly using CP SAR ***,we obtained the slope spectrum of the wave from the estimated wave slopes along azimuth and range *** wave parameters extracted from the synthetic wave slope spectrum were compared with those obtained from buoy observations of the National Data Buoy Center,verifying a suitable agreement.

关键词： RADARSAT-2 CP SAR wave parameters wave slope spectrum

A speckle noise suppression method based on surface waves investigation and monitoring data

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Acta Oceanologica Sinica 2023年第1期42卷 131-141页

作者： Jingwei Gu Xiuzhong Li yijun he School of Marine Sciences Nanjing University of Information Science&TechnologyNanjing210044China

The internal energy distribution of waves can be described using ocean-wave *** many ways,obtaining wave spectra on a global scale is *** waves investigation and monitoring onboard the Chinese-French oceanography satellite is the first space-borne instrument for detecting wave spectra specially,which was launched on October 29,*** can avoid the shortage of synthetic aperture radar detection results while still having some problems,especially with the effects of speckle *** this study,a method to suppress the speckle noise is ***,the empirical formula for background speckle noise is ***,many spatio-temporal representative fluctuation spectra are classified and ***,rational transfer function filtering is used to obtain speckle noise close to the along-track ***,a signal-to-noise ratio threshold is used to suppress the abnormal speckle *** method solves the problems existing in previous denoising methods,such as excessive denoising in the along-track direction and the inability of some abnormal noises to be denoised in the two-dimensional directional wave spectra.

关键词： speckle noise surface waves investigation and monitoring WaveWatch III wave spectra

Atmospheric and oceanic responses to Super Typhoon Mangkhut in the South China Sea:a coupled CROCO-WRF simulation

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Journal of Oceanology and Limnology 2023年第4期41卷 1369-1388页

作者： Mingyu LI yijun he Guoqiang LIU School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China Marine Science and Engineering Guangdong Laboratory Zhuhai 519000China Department of Engineering Mathematics and Internetworking Dalhousie UniversityHalifax B3H 4R2Canada Bedford Institute of Oceanography Fisheries and Oceans CanadaDartmouth B2Y 4A2Canada

The South China Sea(SCS)is the largest marginal sea in the Northwest Pacific Ocean,and it encounters frequent *** atmosphere and ocean will create significant thermal and dynamic responses during the intense disturbance caused by ***,these responses have not been thoroughly investigated owing to the complicated marine *** to the satellite data,the SCS Basin was observed to have a strong sea surface temperature(SST)response to Typhoon Mangkhut,resulting in widespread SST cooling.A coupled model was used to investigate the atmospheric and oceanic responses to Typhoon ***-track data,satellite SST,and ARGO measurements show that the coupled WRF-CROCO simulation displays better track,intensity,SST,temperature,and salinity profiles than those of the WRF-only *** show that the typhoon induced rightward intensifications in wind speed,ocean current,and *** following are some remarkable atmosphere and ocean responses:(1)the SST below the inner-core region is cooled by 1℃,resulting in a 37%-44%decrease in wet enthalpy,and the central pressure is increased by~9 ***,the changes in SST below the innercore region of the SCS Basin have a significant impact on air-sea fluxes under high-wind conditions;(2)the ocean boundary layer analysis shows that near-inertial oscillations on the right side of the typhoon track and a strong inertial current up to~2.28 m/s in the upper ocean were observed,which resonated with the local wind and flow field on the right side and induced strong SST cooling;(3)a decrease in SST decreased the moist static energy of the typhoon boundary layer,thereby weakening the typhoon’s *** difference in equivalent potential temperature and sea surface pressure have a good correlation,indicating that the influence of moist static energy on typhoon intensity cannot be overlooked.

关键词： Super Typhoon Mangkhut coupled ocean-atmosphere model wet enthalpy inertial current

Numerical study on interaction between eddies and the Kuroshio Current east of Taiwan,China

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Journal of Oceanology and Limnology 2021年第2期39卷 388-402页

作者： Yunlong SHI Dezhou YANG yijun he School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of SciencesQingdao 266071China Function Laboratory for Ocean Dynamics and Climate Qingdao National Laboratory for Marine Science and TechnologyQingdao 266000China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China

We investigated the interaction between mesoscale eddies and the Kuroshio Current east of Taiwan,China,using a fine-resolution regional general circulation *** eddies are injected into a region east of Taiwan,China,according to the quasi-geostrophic theory of stratified *** eddies propagated westward at the velocity of the first baroclinic mode Rossby *** eddies collide with the Kuroshio Current east of Taiwan,China,the spatial structure and volume transport of the Kuroshio Current shows a significant *** upper 600 m of the anticyclonic eddy cannot cross the Kuroshio Current to reach the region west of the Kuroshio Current;rather,these waters flow northward along the eastern side of the Kuroshio *** upper water carried by the anticyclonic eddies cannot reach the shelf of the East China Sea(ECS).In contrast,the waters in the upper layer of the cyclonic eddy reach the western side of the Kuroshio Current and then flow *** dynamic mechanism analysis shows that the interaction between the Kuroshio Current and the cyclonic(anticyclonic)eddy decrease(increase)the horizontal potential vorticity(PV)gradient,or PV barrier,whereby the cyclonic(anticyclonic)eddy can(cannot)cross the Kuroshio *** study implies that the continental shelf could potentially be influenced by cyclonic eddies in the open ocean,which can transport heat and material from the upper open ocean across the Kuroshio Current to the shelf waters.

关键词： mesoscale eddies Kuroshio eddy-Kuroshio interaction east of Taiwan,China

Global air-sea surface carbon dioxide transfer velocity and flux estimated using 17 a altimeter data and a new algorithm

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Acta Oceanologica Sinica 2013年第7期32卷 24-33页

作者： YU Tan he yijun YAN Xiaohai Institute of Oceanology Chinese Academy of Sciences University of Chinese Academy of Sciences School of Marine Sciences Nanjing University of Information Science and Technology Key Laboratory of Chinese Academy of Sciences for Ocean Circulation and Waves (KLOCAW ) Institute of OceanologyChinese Academy of Sciences College of Marine Sciences Shanghai Ocean University Center for Remote Sensing University of Delaware

The global distributions of the air-sea CO2 transfer velocity and flux are retrieved from TOPEX/Poseidon and Jason altimeter data from October 1992 to December 2009 using a combined algorithm. The 17 a average global, area-weighted, Schmidt number-corrected mean gas transfer velocity is 21.26 cm/h, and the full exploration of the uncertainty of this estimate awaits further data. The average total CO2 flux （calculated by carbon） from atmosphere to ocean during the 17 a was 2.58 Pg/a. The highest transfer velocity is in the circumpolar current area, because of constant high wind speeds and currents there. This results in strong CO2 fluxes. CO2 fluxes are strong but opposite direction in the equatorial east Pacific Ocean, because the air-sea CO2 partial pressure difference is the largest in the global cceans. The results differ from the previous studies calculated using the wind speed. It is demonstrated that the air-sea transfer velocity is very important for estimating air-sea CO2 flux. It is critical to have an accurate estimation for improving calculation of CO2 flux within climate change studies.

关键词： altimeter remote sensing sea surface carbon dioxide transfer velocity carbon dioxide flux

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A new method to retrieve salinity profiles from sea surface salinity observed by SMOS satellite

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Acta Oceanologica Sinica 2015年第9期34卷 85-93页

作者： YANG Tingting CheN Zhongbiao he yijun School of Marine Sciences Nanjing University of Information Science and Technology

This paper proposes a new method to retrieve salinity profiles from the sea surface salinity （SSS） observed by the Soil Moisture and Ocean Salinity （SMOS） satellite. The main vertical patterns of the salinity profiles are firstly extracted from the salinity profiles measured by Argo using the empirical orthogonal function. To determine the time coefficients for each vertical pattern, two statistical models are developed. In the linear model, a transfer function is proposed to relate the SSS observed by SMOS （SMOS_SSS） with that measured by Argo, and then a linear relationship between the SMOS_SSS and the time coefficient is established. In the nonlinear model, the neural network is utilized to estimate the time coefficients from SMOS_SSS, months and positions of the salinity profiles. The two models are validated by comparing the salinity profiles retrieved from SMOS with those measured by Argo and the climatological salinities. The root-mean-square error （RMSE） of the linear and nonlinear model are 0.08-0.16 and 0.08-0.14 for the upper 400 m, which are 0.01-0.07 and 0.01-0.09 smaller than the RMSE of climatology. The error sources of the method are also discussed.

关键词： salinity profile Soil Moisture and Ocean Salinity (SMOS) data Argo data sea surface salinity