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A positive trend in the stability of global offshore wind energy

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Acta oceanologica Sinica 2024年第1期43卷 123-134页

作者： Chongwei Zheng dalian naval academy Dalian 116018China Marine Resources and Environment Research Group on the Maritime Silk Road Dalian 116018China Shandong Provincial Key Laboratory of ocean Engineering Ocean University of ChinaQingdao 266100China

The recognition on the trend of wind energy stability is still extremely rare,although it is closely related to acquisition efficiency,grid connection,equipment lifetime,and costs of wind energy *** the 40-year(1979–2018)ERA-Interim data from the European Center for Medium-Range Weather Forecasts,this study presented the spatial-temporal distribution and climatic trend of the stability of global offshore wind energy as well as the abrupt phenomenon of wind energy stability in key regions over the past 40 years with the climatic analysis method and Mann-Kendall(M-K)*** results show the following 5 points.(1)According to the coefficient of variation(C_(v))of the wind power density,there are six permanent stable zones of global offshore wind energy:the southeast and northeast trade wind zones in the Indian,Pacific and Atlantic oceans,the Southern Hemisphere westerly,and a semi-permanent stable zone(North Indian ocean).(2)There are six lowvalue zones for both seasonal variability index(S_(v))and monthly variability index(M_(v))globally,with a similar spatial distribution as that of the six permanent stable zones.M_(v) and S_(v) in the Arabian Sea are the highest in the world.(3)After C_(v),M_(v) and S_(v) are comprehensively considered,the six permanent stable zones have an obvious advantage in the stability of wind energy over other sea areas,with C_(v) below 0.8,M_(v) within 1.0,and S_(v) within 0.7 all the year round.(4)The global stability of offshore wind energy shows a positive climatic trend for the past four decades.C_(v),M_(v) and S_(v) have not changed significantly or decreased in most of the global ocean during 1979 *** is,wind energy is flat or more stable,while the monthly and seasonal variabilities tend to shrink/smooth,which is beneficial for wind energy utilization.(5)C_(v) in the low-latitude Pacific and M_(v) and S_(v) in both the North Indian ocean and the low-latitude Pacific have an obvious abrupt phenomenon at the end of

关键词： global oceans wind energy stability spatial-temporal distribution climatic trend

Discovery of the Significant Impacts of Swell Propagation on Global Wave Climate Change

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Journal of ocean University of China 2024年第3期23卷 594-604页

作者： ZHENG Chongwei dalian naval academy Dalian 116018China Marine Resources and Environment Research Group on the Maritime Silk Road Dalian 116018China

This study compared the differences in the wave climate in the South China Sea and North Indian ocean under these two datasets:ERA-40 wave reanalysis and Mei’s hindcast wave *** the numerical calculation of regional ocean waves,the wave climate characteristics exhibited significant bias if the influence of external swells(swells from afar)was not fully considered,which may provide an incorrect basis for global climate change analysis.1)The trends of the significant wave height(SWH)obtained from the two datasets showed significant differences,such as those of the Bay of Bengal and the Java Sea in *** the past 45 years,SWH from ERA-40(SWH-ERA)exhibited a significant annual increase in low-latitude waters of the North Indian ocean(0.2-0.6 cm yr^(-1))and South China Sea(0.2-0.8 cm yr^(-1)).2)In the Bay of Bengal,the SWH-ERA in each month was generally 0.5 m higher than the SWH from Mei’s hindcast wave data(SWH-Mei)and can reach 1.0 m higher in some months.3)In the Bay of Bengal,SWH-ERA and SWH-Mei increased significantly at annual rates of 0.13 and 0.27 cm yr^(-1),*** increasing trend was mainly reflected after ***-ERA showed a trough in 1975(1.33 m)and a crest in 1992(1.83 m),which were not reflected in SWH-Mei.

关键词： wave climate climatic trend monthly variation annual variation external swell

CFD-based hull optimization in calm water using adaptive grid deformation method

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Journal of Hydrodynamics 2024年第2期36卷 241-262页

作者： Shuguang Wang Yonghwan Kim department of naval Architecture and ocean Engineering Seoul National UniversitySeoulKorea

This paper presents an adaptive grid deformation technique for optimizing ship hull forms using computational fluid dynamics(CFD).The proposed method enables accurate and smooth updates of the hull surface and 3-D CFD grids in response to design *** technique incorporates a two-level point-transformation approach to move the grid points by a few design ***,generic B-splines are utilized to transform grid points according to the displacements of the control points within a defined control *** ensures surface modification accuracy and smoothness,similar to those provided by non-uniform rational ***,radial basis functions are used to interpolate the movements of the control points with a limited set of design *** developed method effectively maintains the mesh quality and simulation *** applying this method to surface and grid adaptation,a regression model is proposed in the form of a second-order polynomial to represent the relationship between the geometric parameters and design *** polynomial is then used to introduce geometric ***,a radial basis function surrogate model for the calm-water resistance is constructed to approximate the objective *** enhanced optimization framework is proposed for CFD–based hull optimization and applied to KVLCC2 to validate its feasibility and efficiency.

关键词： Hull-form optimization adaptive grid deformation ship resistance OpenFOAM radial basis function(RBF)surrogate model

Westward Migration of Tropical Cyclone Activity in the Western North Pacific during 1982–2020:Features and Possible Causes

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Journal of Meteorological Research 2024年第1期38卷 1-9页

作者： Jian ZHONG Huadong DU Yuqin WU Yuehua PENG China Satellite Maritime Tracking and Control department Jiangyin 2144312 College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 4100733 dalian naval academy Dalian 1160184 Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029

The westward migration of tropical cyclone(TC)activity has been identified in the western North Pacific(WNP),but the related features and causes remain ***,based on the best track data from China,Japan,and the US,and the NCEP–NCAR reanalysis data in 1982–2020,we investigate characteristics of the westward migration of the WNP TC activity with various metrics,and reveal possible causes for the migration of TC tracks through analyzing its seasonality and dependence on environmental *** results show that the WNP TCs show significant westward migrations in a number of metrics,including location of tracks,genesis,the first track point at which TC reaches its lifetime-maximum intensity,and the last track point in the TC *** is found that TC tracks exhibit more significant westward migrations in the easterly steering flow than in the westerly steering ***,the TC longitude shift shows notable seasonal variations,for which the TCs in the easterlies move further west than those in the westerlies during July–September,vice versa during October–*** dependence of the westward migration of TC tracks on background steering flow is associated with the different environmental *** westward shift in the westerly steering is mainly due to the reduced vertical wind shear(VWS),while the weakened zonal easterly steering and reduced VWS are both closely related to the westward migration in the easterly *** results have important implications for understanding current and future variations in TC longitude shift.

关键词： tropical cyclone westward migration steering flow vertical wind shear

Numerical simulation of inlet placement on sewage characteristics in the rounded square aquaculture tank with single inlet

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Journal of oceanology and Limnology 2024年第4期42卷 1359-1382页

作者： Xiaozhong REN Yixuan HU Yinxin ZHOU Shupeng DU Wei SUN Hangfei LIU Chenxu ZHAO Ying LIU Key Laboratory of Environment Controlled Aquaculture(dalian ocean University)Ministry of Education Dalian 116023China College of Marine Science and Environment Dalian Ocean UniversityDalian 116023China College of ocean and Civil Engineering Dalian Ocean UniversityDalian 116023China Zhejiang University Hangzhou 310058China

To improve the self-cleaning ability of aquaculture tank and the efficiency of circulating water,physical and numerical experiments were conducted on the influence of inlet structure on sewage discharge in a rounded square aquaculture tank with a single *** on the physical model of the tank,analysis of how inlet structure adjustment affects sewage discharge efficiency and flow field characteristics was conducted to provide suitable flow field conditions for sinkable solid particle *** addition,an internal flow field simulation was conducted using the RNG k-εturbulence model in hydraulic drive *** a solid-fluid multiphase model was created to investigate how the inlet structure affects sewage collection in the rounded square aquaculture tank with single inlet and *** finding revealed that the impact of inlet structure is considerably affecting sewage *** conditions of C/B=0.07-0.11(the ratio of horizontal distance between the center of the inlet pipe and the tank wall(C)to length of the tank(B))andα=25°(αis the angle between the direction of the jet and the tangential direction of the arc angle)resulted in optimal sewage collection,which is similar to the flow field experiment in the rounded square aquaculture tank with single inlet and *** excellent correlation was revealed between sewage collection and fluid circulation stability in the aquaculture *** present study provided a reference for design and optimization of circulating aquaculture tanks in aquaculture industry.

关键词： rounded square aquaculture tank sewage collection characteristic inlet structure computational fluid dynamic

Modeling the Interaction between Vacancies and Grain Boundaries during Ductile Fracture

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 2019-2034页

作者： Mingjian Li Ping Yang Pengyang Zhao department of Engineering Mechanics School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China

The experimental results in previous studies have indicated that during the ductile fracture of pure metals,vacancies aggregate and form voids at grain ***,the physical mechanism underlying this phenomenon remains not fully *** study derives the equilibrium distribution of vacancies analytically by following thermodynamics and the micromechanics of crystal *** derivation suggests that vacancies cluster in regions under hydrostatic compression to minimize the elastic strain ***,a finite element model is developed for examining more general scenarios of interaction between vacancies and grain *** model is first verified and validated through comparison with some available analytical solutions,demonstrating consistency between finite element simulation results and analytical solutions within a specified numerical accuracy.A systematic numerical study is then conducted to investigate the mechanism that might govern the micromechanical interaction between grain boundaries and the profuse vacancies typically generated during plastic *** simulation results indicate that the reduction in total elastic strain energy can indeed drive vacancies toward grain boundaries,potentially facilitating void nucleation in ductile fracture.

关键词： Ductile fracture vacancy grain boundary micromechanical finite element method

Existence of long-range magnetic order in Heisenberg spin nanoribbons with edge modification

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Communications in Theoretical Physics 2024年第7期76卷 134-144页

作者： Da-cheng Ma Ling-yi Cui Chu-xiao Sun Xiao-dan Chi Zheng-Nan XianYu An Du College of Science Northeastern UniversityShenyang 110819China department of Basic Science Dalian Naval AcademyDalian 116018China department of Physics College of SciencesShenyang University of Chemical TechnologyShenyang 110142China National Frontiers Science Center for Industrial Intelligence and Systems Optimization Northeastern UniversityChina Key Laboratory of Data Analytics and Optimization for Smart Industry(Northeastern University) Ministry of EducationChina

Long-range magnetic order appears on a side decorated Heisenberg spin nanoribbon at nonzero temperature,although no spontaneous magnetization exists in a one-or two-dimensional isotropic Heisenberg model at any nonzero temperature according to the Mermin-Wagner *** use of the spin Green's function method,we calculated the magnetizations of Heisenberg nanoribbons decorated by side spins with single-ion anisotropy and found that the system exhibits a nonzero transition temperature,whether the decorated edge spins of the system link together or separate from each *** the width of the nanoribbon achieves infinite limit,the transition temperatures of the system tend to the same finite constant eventually whether one edge or both edges are decorated by side spins in the *** results reveal that the magnetism of a low-dimensional spin system is different from that of a threedimensional spin *** the single-ion anisotropy of edge spins in a Heisenberg spin nanoribbon can be modulated by an electric field experimentally,various useful long-range magnetic orders of the system can be *** work can provide a detailed theoretical basis for designing and fabricating next-generation low-dimensional magnetic random-access memory.

关键词： Nanoribbon magnetic anisotropy long-range magnetic order Heisenberg model transition temperature

Protective Graphite Coating for Two-Dimensional Carbon/Carbon Composites

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Fluid Dynamics & Materials Processing 2024年第1期20卷 97-108页

作者： Wei Shi Zhengyi Li Xiaobing Xu Yingshui Yu Xiaofei Ding Heng Ju School of Mechanical and Power Engineering Dalian Ocean UniversityDalian116023China School of Mechanical and Electrical Engineering Gongqing Institute of Science and TechnologyJiujiang332020China

Two-dimensional carbon/carbon(2D C/C)composites are a special class of carbon/carbon composites,generally obtained by combining resin-impregnated carbon fiber clothes,which are then cured and *** study deals with the preparation of a protective coating for these *** coating,based on graphite,was prepared by the slurry *** effect of graphite and phenolic resin powders with different weight ratios was *** results have shown that the coating slurry can fill the pores and cracks of the composite surface,thereby densifying the surface layer of the *** the increase of the graphite powder/phenolic resin weight ratio,the coating density is enhanced while the coating surface flatness decreases;moreover,the protective ability of coating against erosion first increases(from 1:3 to 2:2)and then decreases(from 2:2 to 3:1).When the weight ratio is about 1:1,the coating for 2D C/C composites exhibits the best erosion resistance,which greatly aids these materials during gas *** this case,the erosion rate is decreased by approximately 41.5%at the impact angle of 30°and 52.3%at normal impact,*** can be attributed to the ability of the coating slurry to infiltrate into the substrate,thereby bonding the fibers together and increasing the compactness of the 2D C/C composites.

关键词： Carbon/carbon composites graphite coating microstructure erosion resistance

Constitutive Behavior of the Interface between UHPC and Steel Plate without Shear Connector:From Experimental to Numerical Study

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1863-1888页

作者： Zihan Wang Boshan Zhang Hui Wang Qing Ai Xingchun Huang School of naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China department of Bridge Engineering Tongji UniversityShanghai200092China

The application of ultra-high performance concrete(UHPC)as a covering layer for steel bridge decks has gained widespread *** employing a connection without a shear connector between the steel plate and UHPC,namely,the sandblasted interface and the epoxy adhesive with sprinkled basalt aggregate interface,the installation cannot only be simplified but also the stress concentration resulting from the welded shear connectors can be *** study develops constitutive models for these two interfaces without shear connectors,based on the interfacial pull-off and push-out *** validation,three-point bending tests on the steel-UHPC composite plates are *** results indicated that the proposed bilinear traction-separation model for the sandblasted interface and the trapezoidal traction-separation model for the epoxy adhesive with sprinkled basalt aggregate interface can generally calibrate the interfacial ***,the utilization of the experimentally determined pure shear strength underestimates the load-carrying capacity of the composite plates in the case of three-point bending *** recalling the Mohr-Coulomb criterion,this underestimation is attributed to the enhancement of the interface shear strength by the presence of normal stress.

关键词： Cohesive zone model interfacial behavior finite element simulation UHPC steel plate