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Experimental investigation about the incipient velocity of spherical particles on a hemispherical bed surface

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Particuology 2024年第5期88卷 49-61页

作者： Chuannan Li Jie Chen Changbo Jiang Xie Li Zhiyuan Wu School of Hydraulic and Environmental Engineering Changsha University of Science & TechnologyChangsha 410114China key laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province Changsha 410114China key laboratory of Water-Sediment Sciences and Water disaster Prevention of Hunan Province Changsha 410114China

The sediment particles play a huge role in shaping the bed load *** this research,240 water-tunnel experiments are carried out to investigate the incipient velocity of the observation particles in two particle *** accurately predict the incipient velocity of the observation particles,the equation is conceived by the rolling instability *** incipient velocity equations and experimental data are used to analyze the trend of dispersive pressure and the effect of arrangement position on *** find that it is appropriate to choose the coefficient of drag as 0.261 and the coefficient of lift as 0.198 for the incipient velocity equation of spherical particles on the hemispherical bed ***,the dispersive pressure is closely related to the flow state,particle size,and particle arrangement,which leads to the incipient velocity of the observation particle being at a minimum when the interference particle angle is 45°.Finally,the particle spacing and the projected area changed with the arrangements,directly affecting the incipient velocity of the observed *** analysis of four aspects for the coefficients,dispersive pressure,different particle spacing,and projected area will facilitate the prediction of particle incipient velocity,especially on hemispherical beds.

关键词： Hemispherical bed surface Observed particle Interference particle Dispersive pressure Incipient velocity

Characteristics of orthorhombic anisotropic seismic response induced by horizontal in situ stress in vertical transversely isotropic media

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Science China Earth Sciences 2024年第7期67卷 2291-2310页

作者： Xinpeng PAN Chengxu LU Zhizhe ZHAO Jianxin LIU School of Geoscience and Info-Physics Central South UniversityChangsha 410083China Hunan key Labraory of Nonferrous Resources and Geological disaster Exploration Central South University Changsha 410083China key laboratory of Metallogenic prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University) Ministry of EducationChangsha 410083China PowerChina Zhongnan Engineering Corporation Limited Changsha 410014China

Sedimentary strata typically exhibit the characteristics of transverse isotropy(VTI)with a vertical axis of ***,fractures in sedimentary strata tend to produce anisotropic closure due to horizontal in situ stress,resulting in pronounced orthorhombic anisotropy in VTI media under such stress conditions and influencing the propagation behavior of seismic *** studies have primarily focused on the elastic wave velocity anisotropy induced by applied stress in isotropic background media,neglecting the impact of VTI background media on the anisotropy induced by horizontal in situ stress and the response characteristics of seismic wave *** address these gaps,we first establish the effective elastic stiffness tensor of VTI media under horizontal in situ stress using nonlinear acoustoelastic ***,we derive the accurate and linearized approximate equations for P-wave seismic reflectivity of VTI media under horizontal in situ stress,based on wave equations and scattering theory,***,we compare and analyze the characteristics of orthorhombic anisotropic seismic response induced by horizontal in situ stress at various types of elastic reflection *** results demonstrate that the linearized approximation of the seismic reflection response characteristics closely aligns with the accurate equations under conditions of small stress below 10 MPa,effectively capturing the azimuth-dependent orthorhombic anisotropy induced by horizontal in situ stress in VTI *** results of this study also provide a novel theoretical approach and valuable insights into the seismic prediction of in situ stress.

关键词： Horizontal in situ stress Nonlinear acoustoelastic theory Linear slip theory Orthorhombic anisotropy Stress seismic prediction

Seasonal variation of mesoscale eddy intensity in the global ocean

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Acta Oceanologica Sinica 2024年第1期43卷 48-58页

作者： Yongcan Zu Yue Fang Shuangwen Sun Libao Gao Yang Yang Guijun Guo First Institute of Oceanography/key laboratory of marine Science and Numerical Modeling Ministry of Natural ResourcesQingdao 266061China laboratory for Regional Oceanography and Numerical Modeling Laoshan LaboratoryQingdao 266237China Shandong key laboratory of marine Science and Numerical Modeling Qingdao 266061China

Mesoscale eddies are a prominent oceanic phenomenon that plays an important role in oceanic mass transport and energy *** by rotational speed,the eddy intensity is one of the most fundamental properties of an ***,the seasonal spatiotemporal variation in eddy intensity has not been examined from a global ocean *** this study,we unveil the seasonal spatiotemporal characteristics of eddy intensity in the global ocean by using the latest satellite-altimetry-derived eddy trajectory data *** results suggest that the eddy intensity has a distinct seasonal variation,reaching a peak in spring while attaining a minimum in autumn in the Northern Hemisphere and the opposite in the Southern *** seasonal variation of eddy intensity is more intense in the tropical-subtropical transition zones within latitudinal bands between 15°and 30°in the western Pacific Ocean,the northwestern Atlantic Ocean,and the eastern Indian Ocean because baroclinic instability in these areas changes *** analysis found that the seasonal variation of baroclinic instability precedes the eddy intensity by a phase of 2–3 months due to the initial perturbations needing time to grow into mesoscale eddies.

关键词： seasonal variation mesoscale eddy intensity baroclinic instability global ocean

LPCS Ni-Zn-Al_(2)O_(3) Intermediate Layer Enhanced SPS NiCr-Cr_(3)C_(2) Coating with Higher Corrosion and Wear Resistances

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Journal of Wuhan University of technology(Materials Science) 2024年第1期39卷 188-195页

作者：白杨 LI Yan XING Lukuo LI Xiangbo WANG Zhenhua State key laboratory of marine Coatings Marine Chemical Research Institute Co.Ltd.Qingdao 266071China College of Mechanical and Electrical Engineering University of China Petroleum(East China)Qingdao 266580China Science and technology on marine Corrosion and Protection laboratory Luoyang Ship Materials Research InstituteQingdao 266101China

The double-layer NiCr-Cr_(3)C_(2)/Ni-Zn-Al_(2)O_(3) coatings with sufficient corrosion and wear resistance were prepared on low carbon steel *** intermediate layers Ni-Zn-Al_(2)O_(3) were fabricated by using low-pressure cold spray (LPCS) method to improve the salt fog corrosion resistance properties of the supersonic plasma spray (SPS) NiCr-Cr_(3)C_(2) *** friction and wear performance for the double-layer and single-layer NiCr-Cr_(3)C_(2) coatings were carried out by line-contact reciprocating sliding,*** with the coating surface analysis techniques,the effect of the salt fog corrosion on the tribological properties of the double-layer coatings was *** results showed that the double-layer coatings exhibited better wear resistance than that of the single-layer coatings,due to the better corrosion resistance of the intermediate layer;the wear mass losses of the double-layer coatings was reduced by 70%than that of the single layer coatings and the wear mechanism of coatings after salt fog corrosion conditions is mainly corrosion wear.

关键词： low-pressure cold spray NiCr-Cr_(3)C_(2)coating wear behavior salt fog corrosion

Pilot-Free End-to-End Underwater Acoustic Communication System Based on Autoencoder

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Journal of Communications and Information Networks 2024年第3期9卷 233-243页

作者： Yizhe Wang Deqing Wang Liqun Fu School of Informatics and Key Laboratory of Underwater Acoustic Communication and Marine Information Technology of Ministry of EducationXiamen UniversityXiamen 361005China

The long delay spreads and significant Doppler effects of underwater acoustic(UWA)channels make the design of the UWA communication system more *** this paper,we propose a learning-based end-to-end framework for UWA communications,leveraging a double feature extraction network(DFEN)for data *** DFEN consists of an attentionbased module and a mixer-based module for channel feature extraction and data feature extraction,*** the diverse nature of UWA channels,we propose a stack-network with a two-step training strategy to enhance *** avoiding the use of pilot information,the proposed network can learn data mapping that is robust to UWA *** results show that our proposed algorithm outperforms the baselines by at least 2 dB under bit error rate(BER)10^(−2)on the simulation channel,and surpasses the compared neural network by at least 5 dB under BER 5×10^(−2)on the experiment channels.

关键词： underwater acoustic communications autoencoder time-varying channel

Failure evolution and disaster prediction of rock under uniaxial compression based on non-extensive statistical analysis of electric potential

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International Journal of Mining Science and technology 2024年第7期34卷 975-993页

作者： Tiancheng Shan Zhonghui Li Haishan Jia Enyuan Wang Xiaoran Wang Yue Niu Xin Zhang Dong Chen Shan Yin Quancong Zhang State key laboratory of Coal Mine disaster Prevention and Control China University of Mining and TechnologyXuzhou 221116China National Engineering Research Center for Coal Gas Control China University of Mining and TechnologyXuzhou 221116China School of Safety Engineering China University of Mining and TechnologyXuzhou 221116China State key laboratory for Fine Exploration and Intelligent Development of Coal Resources China University of Mining and TechnologyXuzhou 221116China State key laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China

Rock failure can cause serious geological disasters,and the non-extensive statistical features of electric potential(EP)are expected to provide valuable information for disaster *** this paper,the uniaxial compression experiments with EP monitoring were carried out on fine sandstone,marble and granite samples under four displacement *** Tsallis entropy q value of EPs is used to analyze the selforganization evolution of rock *** the influence of displacement rate and rock type on q value are explored by mineral structure and fracture modes.A self-organized critical prediction method with q value is *** results show that the probability density function(PDF)of EPs follows the q-Gaussian *** displacement rate is positively correlated with q *** the displacement rate increasing,the fracture mode changes,the damage degree intensifies,and the microcrack network becomes *** influence of rock type on q value is related to the burst intensity of energy release and the crack fracture *** q value of EPs can be used as an effective prediction index for rock failure like b value of acoustic emission(AE).The results provide useful reference and method for the monitoring and early warning of geological disasters.

关键词： Electric potential Non-extensive statistical feature Displacement rate q-Gaussian distribution Precursor prediction Rock materials

Sarcocinerenoids A—J,Eight Rare Capnosane-Type and Two New Cage-Type Cembranoids with Promoting Angiogenesis Activity from the South China Sea Soft Coral Sarcophyton cinereum

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Chinese Journal of Chemistry 2024年第8期42卷 815-822页

作者： Yue Mi Yanan Yang Xuli Tang Xiao Han Guoqiang Li key laboratory of marine Drugs Chinese Ministry of EducationSchool of Medicine and PharmacyOcean University of ChinaQingdaoShandong266003 China laboratory of marine Drugs and Biological Products National Laboratory for Marine Science and TechnologyQingdaoShandong266235 China College of Chemistry and Chemical Engineering Ocean University of ChinaQingdaoShandong266100 China

Backgroundand Originality Content,Cembranoids are a structurally diverse class of diterpenoids commonly occurring in marine and terrestrial organisms.(+)-Cembrene was the first reported cembranoid diterpenoid discovered in 1962,l and more than 1400 cembranoid diterpenoids have been identified in the last six decades,[2]Cembranoids are characterized by a 14-membered carbocyclic ring,an isopropyl group and three methyl groups,which form their core carbon *** processes such as oxidation,oxidative rearrangements and transannular cyclizations occur in organisms,leading to the formation of distinctive specialized metabolites such as epoxide,lactone,ester,furan,pyrane and other ringbased cembranoids.[2-3]

关键词： Soft coral Sarcophyton cinereum Capnosane-type cembranoids Absolute configurations Activities Natural products NMR spectroscopy Liquid chromatography X-raydiffraction Chiral resolution

Multiple Matching Attenuation Based on Curvelet Domain Extended Filtering

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Journal of Ocean University of China 2024年第4期23卷 924-932页

作者： HUA Qingfeng CHEN Zhang HE Huili TAN Jun CHEN Haifeng LI Guanbao SONG Peng ZHAO Bo JIANG Xiuping key laboratory of marine Geology and Metallogeny First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China laboratory for marine Mineral Resources Qingdao Marine Science and Technology CenterQingdao 266237China College of marine Geoscience Ocean University of ChinaQingdao 266100China BGP Inc. China National Petroleum CorporationZhuozhou 072750China key laboratory of Submarine Geosciences and Prospecting Techniques Ministry of EducationQingdao 266100China

The paper develops a multiple matching attenuation method based on extended filtering in the curvelet domain,which combines the traditional Wiener filtering method with the matching attenuation method in curvelet ***,the method uses the predicted multiple data to generate the Hilbert transform records,time derivative records and time derivative records of Hilbert ***,the above records are transformed into the curvelet domain and multiple matching attenuation based on least squares extended filtering is ***,the attenuation results are transformed back into the time-space *** on the model data and field data show that the method proposed in the paper effectively suppress the multiples while preserving the primaries ***,it has higher accuracy in eliminating multiple reflections,which is more suitable for the multiple attenuation tasks in the areas with complex structures compared to the time-space domain extended filtering method and the conventional curvelet transform method.

关键词： multiple matching attenuation curvelet domain extended filtering

A semi-infinite beam theoretical model on predicting rock slope subsidence induced by underground mining

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Journal of Mountain Science 2024年第2期21卷 633-647页

作者： LIU Xinrong WANG Nanyun ZHONG Zuliang DU Libing LIANG Erwei School of Civil Engineering Chongqing UniversityChongqing 400045China State key laboratory of Coal Mine disaster Dynamics and Control Chongqing 400044China key laboratory of New technology for Construction of Cities in Mountain Area of Ministry of Education Chongqing 400045China School of Geoscience and technology Southwest Petroleum UniversityChengdu 610500China

When the mining goaf is close to the cliff,rock slope subsidence induced by underground mining is significantly affected by its boundary *** this study,an analytical method is proposed by considering the key strata as a semi-infinite Euler-Bernoulli beam rested on a Winkler foundation with a local subsidence *** analytical solutions of deflection are derived by analyzing the boundary and continuity conditions of the ***,the analytical solutions are verified by the results from experimental tests,FEM and InSAR,*** that,the influence of changing parameters on deflections is studied with sensitivity *** results show that the distance between goaf and cliff significantly affects the deflection of semi-infinite *** response of semi-infinite beam is obviously determined by the length of goaf and the bending stiffness of *** comparisons between semi-infinite beam and infinite beam illustrate the ascendancy of the improved model in such problems.

关键词： key strata Mining rock slope Winkler foundation Euler-Bernoulli beam Subsidence prediction