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Earthquake engineering and engineering Vibration 2024年第3期23卷 637-648页

作者： Lulu Yan Ding-Hao Yu Research Center for Geotechnical and Structural engineering Technology of Liaoning Province Dalian UniversityDalian116622China state key laboratory of coastal and offshore engineering Dalian University of TechnologyDalian 116024China

In this study,a novel equivalent damping ratio model that is suitable for reinforced concrete(RC)structures considering cyclic degradation behavior is developed,and a new equivalent linearization analysis method for implementing the proposed equivalent damping ratio model for use in seismic damage evaluation is *** this end,Ibarra’s peak-oriented model,which incorporates an energy-based degradation rule,is selected for representing hysteretic behavior of RC structure,and the optimized equivalent damping for predicting the maximum displacement response is presented by using the empirical method,in which the effect of cyclic degradation is ***,the relationship between the hysteretic energy dissipation of the inelastic system and the elastic strain energy of the equivalent linear system is established so that the proposed equivalent linear system can be directly integrated with the Park-Ang seismic model to implement seismic damage *** to the simplicity of the equivalent linearization method,the proposed method provides an efficient and reliable way of obtaining comprehensive insight into the seismic performance of RC *** verification demonstrates the validity of the proposed method.

关键词： degrading system equivalent linear system equivalent damping seismic damage RC structures

Observing eddy dye patches induced by shear instabilities in the surf zone on a plane beach

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Acta Oceanologica Sinica 2024年第3期43卷 15-29页

作者： Chunping Ren Nannan Fu Chong Yu Yuchuan Bai Kezhao Fang state key laboratory of Hydraulic engineering Simulation and Safety Tianjin UniversityTianjin 300072China College of Water Resource Science and engineering Taiyuan University of TechnologyTaiyuan 030024China state key laboratory of coastal and offshore engineering Dalian University of TechnologyDalian 116024China

The effects of surf zone eddy generated by alongshore currents on the deformation and transport of dye are still poorly understood,and related tracer release experiments are ***,a tracer release laboratory experiment was conducted under monochromatic,unidirectional incident waves with a large incident angle(30°)on a plane beach with a 1:100 slope in a large wave basin.A charge-coupled device suspended above the basin recorded the dye patch *** evolution of eddy dye patch was observed and the transport and diffusion were analyzed based on the collected ***,a linear instability numerical model was adopted to calculate the perturbation velocity field at the initial *** observation and image processing results show that surf zone eddy patches occurred and were separated from the original dye *** numerical analysis results demonstrate that the structure of the perturbation velocity field is consistent with the experimental observations,and that the ejection of eddy patches shoreward or offshore may be ascribed to the double vortex.

关键词： surf zone tracer release experiment evolution of eddy patch shear instability of alongshore currents

Dynamic Coupling Analysis of Semisubmersible Platform Float-over Method for Docking Case

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Journal of Ocean University of China 2024年第2期23卷 345-357页

作者： DING Hongyan QIN Licheng ZHANG Puyang SONG Zhengrong XIE Weiwei state key laboratory of Hydraulic engineering Simulation and Safety Tianjin UniversityTianjin 300072China offshore Oil engineering Co. Ltd.Tianjin 300461China

In this paper,the multi-body coupled dynamic characteristics of a semisubmersible platform and an HYSY 229 barge were ***,coupled hydrodynamic analysis of the HYSY 229 barge and the semisubmersible platform was *** hydrodynamic parameters were obtained using the retardation function method of three-dimensional frequency-domain potential flow *** results of the hydrodynamic analysis were highly consistent with the test findings,verifying the accuracy of the multifloating hydrodynamic coupling analysis,and key hydrodynamic parameters were solved for different water depths and the coupling *** to the obtained results,the hydrodynamic influence was the largest in shallow waters when the coupling effect was ***,the coupled motion equation combined with viscous damping,fender system,and mooring system was established,and the hydrodynamics,floating body motion,and dynamic response of the fender system were *** analysis revealed good agreement among the surge,sway,and yaw motions of the two floating ***,when the wave period reached 10 s,the motion of the two floating bodies showed severe shock,and a relative motion was also ***,excessive constraints should be added between the two floating bodies during construction to ensure construction *** numerical analysis and model test results of the semisubmersible platform and HYSY 229 barge at a water depth of 42 m and sea conditions of 0°,45°,and 90° were in good agreement,and the error was less than 5%.The maximum movement of the HYSY 229 barge reached 2.61 m in the sway direction,whereas that of the semisubmersible platform was 2.11 *** construction,excessive constraints should be added between the two floating bodies to limit their relative movement and ensure construction safety.

关键词： float-over method semisubmersible platform coupling hydrodynamic fender system time-domain analysis

Three-dimensional finite element simulation and reconstruction of jointed rock models using CT scanning and photogrammetry

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Journal of Rock Mechanics and Geotechnical engineering 2024年第4期16卷 1348-1361页

作者： Yingxian Lang Zhengzhao Liang Zhuo Dong state key laboratory of coastal and offshore engineering Dalian University of TechnologyDalian116024China School of Energy Science and engineering Henan Polytechnic UniversityJiaozuo454003China

The geometry of joints has a significant influence on the mechanical properties of *** simplify the curved joint shapes in rocks,the joint shape is usually treated as straight lines or planes in most laboratory experiments and numerical *** this study,the computerized tomography (CT) scanning and photogrammetry were employed to obtain the internal and surface joint structures of a limestone sample,*** describe the joint geometry,the edge detection algorithms and a three-dimensional (3D) matrix mapping method were applied to reconstruct CT-based and photogrammetry-based jointed rock *** comparison tests,the numerical uniaxial compression tests were conducted on an intact rock sample and a sample with a joint simplified to a plane using the parallel computing *** results indicate that the mechanical characteristics and failure process of jointed rocks are significantly affected by the geometry of *** presence of joints reduces the uniaxial compressive strength (UCS),elastic modulus,and released acoustic emission (AE) energy of rocks by 37%–67%,21%–24%,and 52%–90%,*** to the simplified joint sample,the proposed photogrammetry-based numerical model makes the most of the limited geometry information of *** UCS,accumulative released AE energy,and elastic modulus of the photogrammetry-based sample were found to be very close to those of the CT-based *** UCS value of the simplified joint sample (i.e.38.5 MPa) is much lower than that of the CT-based sample (i.e.72.3 MPa).Additionally,the accumulative released AE energy observed in the simplified joint sample is 3.899 times lower than that observed in the CT-based *** scanning provides a reliable means to visualize the joints in rocks,which can be used to verify the reliability of photogrammetry *** application of the photogrammetry-based sample enables detailed analysis for estimating the mechanical properties of jointed rocks.

关键词： X-ray computerized tomography(CT)scanning Photogrammetry Parallel computing Numerical simulation Uniaxial compression test Digital image processing

Simulating the evolution of focused waves by a two-layer Boussinesq-type model

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Acta Oceanologica Sinica 2024年第5期43卷 91-99页

作者： Ping Wang Zhongbo Liu Kezhao Fang Wenfeng Zou Xiangke Dong Jiawen Sun state Environmental Protection key laboratory of Marine Ecosystem Restoration National Marine Environmental Monitoring CenterDalian 116023China College of Transportation engineering Dalian Maritime UniversityDalian 116026China state key laboratory of coastal and offshore engineering Dalian University of TechnologyDalian 116024China

Accurate simulation of the evolution of freak waves by the wave phase focusing method requires accurate linear and nonlinear properties,especially in deep-water *** this paper,we analyze the ability to simulate deep-water focused waves of a two-layer Boussinesq-type(BT)model,which has been shown to have excellent linear and nonlinear *** further improve the numerical accuracy and stability,the internal wavegenerated method is introduced into the two-layer Boussinesq-type ***,the sensitivity of the numerical results to the grid resolution is analyzed to verify the convergence of the model;secondly,the focused wave propagating in two opposite directions is simulated to prove the symmetry of the numerical results and the feasibility of the internal wave-generated method;thirdly,the limiting focused wave condition is simulated to compare and analyze the wave surface and the horizontal velocity of the profile at the focusing position,which is in good agreement with the measured *** the simulation of focused waves in very deep waters agrees well with the measured values,which further demonstrates the capability of the two-layer BT model in simulating focused waves in deep waters.

关键词： focused waves numerical simulation Boussinesq-type model velocity profile

Bi2S3 nanofiber bunch for highly efficient CO2 electroreduction to formate at low overpotential

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Rare Metals 2024年第7期43卷 3391-3399页

作者： Li Wang Wen-Ke Gui Shan Jiang Liang Wang Jian-Ping Yang state key laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and EngineeringDonghua University Centre for Catalysis and Clean Energy Griffith UniversityGold Coast Campus

Electrochemical conversion of CO2into valuable chemicals represents a promising strategy to alleviate the environmental issues caused by excessive CO2levels in the *** this work,Bi2S3with different morphologies have b... 详细信息

关键词： Carbon dioxide

The mechanisms of thermal solidification agent promoting steam diversion in heavy oil reservoirs

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Petroleum Science 2024年第3期21卷 1902-1914页

作者： Zhan-Xi Pang Qian-Hui Wang Qiang Meng Bo Wang Dong Liu state key laboratory of Petroleum Resources and engineering China University of Petroleum (Beijing) Liaohe Oilfield Institute CNPC China Henan Oilfield Institute Sinopec China Tianjin Branch of China National offshore Oil Company (CNOOC) Ltd.

At high cycles of steam huff & puff, oil distribution in reservoirs becomes stronger heterogeneity due to steam channeling. Thermal solidification agent can be used to solve this problem. Its solution is a lowviscosity liquid at normal temperature, but it can be solidified above 80°C. The plugging degree is up to 99% at 250°C. The sweep efficiency reaches 59.2%, which is 7.3% higher than pure steam injection. In addition, simultaneous injection of viscosity reducer and/or nitrogen foams can further enhance oil recovery. The mechanism of this technology depends on its strong plugging ability, which changes the flowing pattern of steam to effectively mobilize remaining oil. Viscosity reducer and nitrogen foams further expand the sweep range and extends the effective period. Therefore, thermal solidification agent can plug steam channeling paths and adjust steam flowing direction to significantly enhance oil recovery at high cycles of steam huff & puff.

关键词： Heavy oil reservoir Steam huff & puff Steam channeling Steam diversion Plugging performance Mechanism analysis

Potassium isotopic signatures of modern offshore detrital sediments from different climatic regimes and the implications

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Science China Earth Sciences 2024年第2期67卷 405-419页

作者： Jun MU Tianyu CHEN Qian YU Shichao AN Jianfang CHEN Xuefa SHI Weiqiang LI state key laboratory for Mineral Deposits Research School of Earth Sciences and EngineeringNanjing UniversityNanjing210023China Ministry of Education key laboratory for coast and Island Development School of Geography and Ocean ScienceNanjing UniversityNanjing210023China state key laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou310012China key laboratory of Marine Geology and Metallogeny First Institute of OceanographyMinistry of Natural ResourcesQingdao266061China

Potassium isotopes are a novel tracer for continental *** K isotope studies on chemical weathering generally targeted weathering profiles under a particular climate region,yet the effects of chemical weathering on K isotopes under different climatic backgrounds remain ***,little is known about the K isotope signatures of modern unconsolidated detrital ***,we report K isotopic data of surficial seafloor sediments from continental shelves along the east coast of China(ECC),as well as those around the tropical Hainan island in the northern South China *** ECC sediments have a relatively narrow distribution ofδ^(41)K(with reference to NIST3141a)values,which range from(-0.40±0.01)‰to(-0.57±0.04)‰,with an average of(-0.51±0.09)‰.By contrast,δ^(41)K values of Hainan offshore sediments display a larger variation,ranging from(-0.28±0.07)‰to(-0.67±0.02)‰.Theδ^(41)K values of Hainan offshore sediments exhibit negative correlations with the chemical index of alteration(CIA),Al/K,Ti/K,and total iron(FeT),which underlines the control of chemical weathering on K isotopic signatures of detritus inputs into *** also measured Mg isotope compositions for the same samples;interestingly,the variability inδ^(26)Mg of the samples is small(~0.24‰)for all ECC and Hainan offshore sediments,andδ^(26)Mg values do not show clear correlations with indexes of chemical *** study demonstrates the link between K isotopic variability of detrital sediments and climatic conditions including rainfall intensity,which indicates that K isotopes of the detrital component of marine sediments could be applied to study Earth’s climate in deep ***δ^(41)K values of the offshore detrital sediments are significantly less variable than those of pelagic marine sediments,highlighting the importance of distinguishing the effects of diagenesis and neoformation of clay minerals from continental weathering in attempts to study deep-time climate-weathering

关键词： Potassium isotopes Magnesium isotopes Chemical weathering Detrital sediments Climatic regimes Mean annual precipitation

Experimental Study on Towing Characteristics of Composite Bucket Wellhead Platform

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China Ocean engineering 2024年第3期38卷 531-542页

作者： ZHANG Pu-yang LIU Ying-fei LE Cong-huan DING Hong-yan BAI Yu state key laboratory of Hydraulic engineering Intelligent Construction and Operation Tianjin UniversityTianjin 300072China

With the rapid development of large-scale development of marginal oilfields in China,simple wellhead platforms that are simple in structure and easy to install have become an inevitable choice in the process of oilfield ***,traditional simple wellhead platforms are often discarded after a single *** pursuit of a more costeffective approach to developing marginal oilfields,this paper proposes a new offshore oil field development facility—an integrated bucket foundation for wellhead *** verify the safety of its towing behavior and obtain the dynamic response characteristics of the structure,this paper takes a bucket integrated bucket foundation for wellhead platform with a diameter of 40 m as the research *** combining physical model tests and numerical simulations,it analyzes the static stability and dynamic response characteristics of the structure during towing,complete with the effects of the draft,wave height,wave period,and towing point height,which produce the dynamic responses of the structure under different influence factors,such as roll angle,pitch angle,heave acceleration and towing force as well as the sensibility to transport *** results show that the integrated bucket foundation for wellhead platform is capable of self-floating towing,and its movement is affected by the local environment,which will provide a reference for actual projects.

关键词： composite bucket foundation wellhead platform air flotation towing model test

Polyp-Canal Reconstruction Reveals Evolution Toward Complexity in Corals

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Research 2024年第1期2023卷 417-428页

作者： Yixin Li Xin Liao Xin Wang Yuanchao Li Hongwei Zhao Yunpeng Zhao Junyuan Chen Chunpeng He Zuhong Lu state key laboratory of Bioelectronics School of Biological Science and Medical EngineeringSoutheast UniversityNanjing 210096China state key laboratory of coastal and offshore engineering Dalian University of TechnologyDalian 116024China Guangxi key Lab of Mangrove Conservation and Utilization Guangxi Mangrove Research CenterGuangxi Academy of SciencesBeihai 536000China Hainan Academy of Ocean and Fishery Sciences Haikou 571126China state key laboratory of Marine Resources Utilization in South China Sea Hainan UniversityHaikou 570228China Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences39 East Beijing RoadNanjing 210008China

Modern scleractinian corals are classified into robust,complex,and basal clades through comparative molecular ***,only few morphological or biological criteria can systematically determine the evolutionary trajectories of these major scleractinian coral ***,we obtained the structural information of 21 scleractinian coral species representing robust and complex clades:High-resolution micro-computed tomography was used to reconstruct the polyp-canal systems in their colonies and to visualize the dynamic polyp growth *** found that the emergence of mesh-like canals may distinguish representatives of complex and robust *** differences in polyp-canal connections suggest distinct evolutionary trajectories among coral species:The formation of the canal network promoted the development of more complex coral structures,and coral polyps within this network formed calices of very similar volume,following precise axial growth *** influence of individual polyps on the coral colony becomes less significant as coral structures become more complex,and coral species with more complicated polyp-canal systems occupied niches more *** work supplements current evolutionary studies on reef-building corals,providing insight for further studies on coral growth patterns.

关键词： Coral representing directions