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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

THE COUPLING OF NBEM AND FEM FOR QUASILINEAR PROBLEMS IN A BOUNDED OR UNBOUNDED DOMAIN WITH A CONCAVE ANGLE

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Journal of Computational Mathematics 2013年第3期31卷 308-325页

作者： Baoqing liu Qikui Du Jiangsu Key Laboratory for NSLSCS School of Mathematical Sciences Nanjing Normal University Nanjing 210023 China College of Applied Mathematics Nanjing University of Finance and Economics Nanjing 210043 China

Based on the Kirchhoff transformation and the natural boundary element method, we investigate a coupled natural boundary element method and finite element method for quasi-linear problems in a bounded or unbounded domain with a concave angle. By the principle of the natural boundary reduction, we obtain natural integral equation on circular arc artificial boundaries, and get the coupled variational problem and its numerical method. Moreover, the convergence of approximate solutions and error estimates are obtained. Finally, some numerical examples are presented to show the feasibility of our method. Our work can be viewed as an extension of the existing work of H.D. Han et al..

关键词： Quasilinear elliptic equation Concave angle domain Natural integral equation

From one linear genome to a graph-based pan-genome: a new era for genomics

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Science China(Life Sciences) 2020年第12期63卷 1938-1941页

作者： Yucheng liu Zhixi Tian State Key Laboratory of Plant Cell and Chromosome Engineering Center for Genome EditingInstitute of Genetics and Developmental BiologyInnovation Academy for Seed DesignChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

The seeds for genomics were sown with the development of DNA sequencing(Sanger et al., 1977), cultivated with each advance in molecular biology, and have since grown into one of the most important aspects of the life sciences. With the sequencing of the first draft human genome(Venter et al.,2001), the era of post-genomics began. Once one genome has been sequenced, it can be used as the reference for a certain species, and sequences from individuals can be mapped onto it to compare genetic variations among different lines.

关键词： Sanger genome genomics

Single-phase evolution path to new record efficiency of kesterite solar cells

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Science China Chemistry 2024年第2期67卷 420-421页

作者： Yixiong Ji Fangyang liu School of Metallurgy and Environment Central South UniversityChangsha410083China ARC Centre of Excellence in Exciton Science School of ChemistryUniversity of Melbourne3010MelbourneVictoriaAustralia

Over the past few years, there have been significant advancements in uncovering previously sealed records in the kesterite solar cell. This also has led to substantial growth marked by multiple groups achieving successive efficiency breakthroughs, shining a renewed spotlight on this promising photovoltaic material that had previously been overlooked due to its low efficiency.

关键词： breakthrough sealed successive

ON STABILITY AND REGULARIZATION FOR BACKWARD HEAT EQUATION

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Chinese Annals of Mathematics,Series B 2003年第1期24卷 35-44页

作者： liu JIJUN LUO DINGJUN Department of Mathematics Nanjing Normal University Nanjing 210097 China and Department of Mathematics Southeast University Nanjing 210096 China.Department of Mathematics Nanjing Normal University Nanjing 210097 China.

Consider a backward heat equation in a bounded domain Ω (?) R2 with the noisy data in the initial time geometry. The aim is to find the temperature for 0 < ε < t < T. For this ill-posed problem, the authors give a continuous dependence estimate of the solution. Moreover, the convergence rate of the approximate solution is also given.

关键词： Heat equation Inverse problem Stability Regularization

Intelligent identification of landslides in loess areas based on the improved YOLO algorithm:a case study of loess landslides in Baoji City

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Journal of Mountain Science 2023年第11期20卷 3343-3359页

作者： liu Qing WU Ting-ting DENG Ya-hong liu Zhi-heng School of Mechanical and Electrical Engineering Huainan Normal UniversityHuainan 232038China School of Geomatics Anhui University of Science and TechnologyHuainan 232001China School of Geology Engineering and Geomatics Chang’an UniversityXi’an 710064China School of Aerospace Science and Technology Xidian UniversityXi'an 710064China

Loess landslides are one of the geological hazards prevalent in mountainous areas of Loess Plateau,seriously threatening people's lives and property *** identification of landslides is a prerequisite for reducing the risk of landslide *** landslide interpretation methods often have the disadvantage of being laborious and difficult to use on a large scale compared with the recently developed deep learning-based landslide detection *** this study,we propose an improved deep learning model,landslide detectionyou only look once(LD-YOLO),based on the existing you only look once(YOLO)model for the intelligent identification of old and new landslides in loess ***,remote sensing images of landslides in Baoji City,Shaanxi Province,China are acquired from the Google Earth Engine *** landslide images of Baoji City(excluding Qianyang County)are used to establish a loess landslide dataset for training the *** landslide data of Qianyang County is used to verify the detection performance of the *** focal and efficient IoU(Focal-EIoU)loss function and efficient channel attention(ECA)mechanism are incorporated into the 7th version of YOLO(YOLOv7)model to construct the LD-YOLO model,which makes it more suitable for the landslide detection *** experiments yielded an improved LD-YOLO model with average precision of 92.05%,precision of 92.31%,recall of 90.28%,and F1-score of 91.28%for loess landslide *** landslides in Qianyang County were divided into two test sets,new landslides and old landslides,which were used to test the detection performance of LD-YOLO for both types of *** results show that LD-YOLO detects old landslides with a detection precision of 82.75%and a recall of 80%.When detecting new landslides,the detection precision is 94.29%and the recall is 91.67%.It indicates that our proposed LD-YOLO model has strong detection performance for both new and old landslides in loess areas

关键词： Loess landslide Deep learning Attention mechanism Data augmentation You only look once(YOLO)

Recent Advances in Soft Biological Tissue Manipulating Technologies

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Chinese Journal of Mechanical Engineering 2022年第3期35卷 3-36页

作者： Zhihua liu Zhirong Liao Dong Wang Chengyong Wang Chengli Song Haonan Li Yao liu Guangdong University of Technology GuangzhouChina Guangdong Provincial Key Laboratory of Minimally Invasive Surgical Instruments and Manufacturing Technology Guangdong University of TechnologyGuangzhouChina Faculty of Engineering University of NottinghamNottinghamUK Faculty of Engineering University of ExeterExeterUK School of Medical Instrument and Food Engineering University of Shanghai for Science and TechnologyShanghaiChina Shanxi Key Laboratory of Advanced Manufacturing Technology North University of ChinaTaiyuanChina

Biological soft tissues manipulation,including conventional(mechanical)and nonconventional(laser,waterjet and ultrasonic)processes,is critically required in most surgical ***,the soft tissues,with their nature of anisotropic and viscoelastic mechanical properties,and high biological and heat sensitivities,are difficult to ***,the mechanical and thermal induced damage on the surface and surrounding tissue during the surgery can impair the proliferative phase of ***,understanding the manipulation mechanism and the resulted surface damage is of importance to the *** recent years,more and more scholars carried out researches on soft biological tissue cutting in order to improve the cutting performance of surgical instruments and reduce the surgery induced tissue ***,there is a lack of compressive review that focused on the recent advances in soft biological tissue manipulating ***,this review paper attempts to provide an informative literature survey of the state-of-the-art of soft tissue manipulation processes in *** is achieved by exploring and recollecting the different soft tissue manipulation techniques currently used,including mechanical,laser,waterjet and ultrasonic cutting and advanced anastomosis and reconstruction processes,with highlighting their governing removal mechanisms as well as the surface and subsurface damages.

关键词： Soft biological tissue Surgical processing Tissue cutting Tissue welding

Rational design of FeS_(2)microspheres as high-performance catalyst for electrooxidation of hydrazine

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Journal of Materials Science & Technology 2022年第15期110卷 161-166页

作者： Jie Sun Chuangwei liu Wenhan Kong Jie liu Liangyu Ma Song Li Yuanhong Xu Institute of Biomedical Engineering College of Life SciencesCollege of Materials Science and EngineeringQingdao UniversityQingdao 266071China Department of Energy Conversion and Storage Technical University of Denmark2800 Kgs.LyngbyDenmark Key Lab for Anisotropy and Texture of Materials School of Materials Science and Engineering Northeastern UniversityShenyang 110819China

Inspired by the relatively recognized performance of transition metal sulfides in the oxidation of hydrazine,the catalytic properties of FeS_(2) and Fe_(3)S_(4) are compared via the density functional theory *** to the different coordination numbers of iron-sulfur,the free energies of the dehydrogenation steps on FeS_(2) are far less than those on Fe_(3)S_(4),which led to the much better catalytic performance of FeS_(2).Accordingly,FeS_(2) microspheres are rationally proposed as a more efficient electrocatalyst for hydrazine oxidation,which is then prepared by a facile one-step hydrothermal *** FeS_(2)microspheres show great activity for hydrazine oxidation with an onset oxidation potential of 0.22 V *** hydrogen electrode,and a peak current density of 16 m A cm^(-2).Meanwhile,stability and high faradaic efficiency(3.5e-/N_(2)H_(4))is obtained for hydrazine oxidation to N_(2).

关键词： Rational design Hydrazine electrooxidation FeS_(2)microspheres Electrochemistry

CFD simulation study of the effect of baffles on the fluidized bed for hydrogenation of silicon tetrachloride

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Chinese Journal of Chemical Engineering 2022年第5期35卷 219-228页

作者： Ning liu Xingping liu Fumin Wang Feng Xin Mingshuai Sun Yi Zhai Xubin Zhang School of Chemical Engineering and Technology Tianjin UniversityTianjin 300350China Xinte Energy Co. Ltd.UrumchiXinjiang 830011China

In this study,the effect of channel baffles and louver baffles on the flow pattern in the large-scale industrial fluidized beds was studied by computational fluid dynamics(CFD)***,the effect of flow pattern on the chemical reaction performance was studied for the first *** results showed that the gas velocity distributed more uniformly,solid particles dispersed more homogeneously and aggregation scarcely occurred in the fluidized bed with louver baffles than that with channel *** residence time distribution indicated that louver baffles remarkably suppressed gas back-mixing in comparison with channel *** reasonable agreements of pressure distribution and reaction results between the simulation in the bed with channel baffles and the data on a large-scale industrial apparatus demonstrated the accuracy of the CFD *** predicted conversion of SiCl_(4) in the bed with louver baffles(27.44%)was higher than that with channel baffles(22.69%),indicating that louver baffles markedly improved the performance of the fluidized *** study could provide useful information for future structural improvements of baffles in large-scale fluidized beds.

关键词： Fluidized-bed Baffle Gas-solids flow Hydrogenation Computational fluid dynamics