Complex flow around floating structures is a highly nonlinear problem,and it is a typical feature in ship and ocean engineering.Traditional experimental methods and potential flow theory have limitations in predicting...Complex flow around floating structures is a highly nonlinear problem,and it is a typical feature in ship and ocean engineering.Traditional experimental methods and potential flow theory have limitations in predicting complex viscous flows.With the improvement of high-performance computing and the development of numerical techniques,computational fluid dynamics(CFD)has become increasingly powerful in predicting the complex viscous flow around floating structures.This paper reviews the recent progress in CFD techniques for numerical solutions of typical complex viscous flows in ship and ocean engineering.Applications to free-surface flows,breaking bow waves of high-speed ship,ship hull-propeller-rudder interaction,vortexinduced vibration of risers,vortex-induced motions of deep-draft platforms,and floating offshore wind turbines are discussed.Typical techniques,including volume of fluid for sharp interface,dynamic overset grid,detached eddy simulation,and fluid-structure coupling,are reviewed along with their applications.Some novel techniques,such as high-efficiency Cartesian grid method and GPU acceleration technique,are discussed in the last part as the future perspective for further enhancement of accuracy and efficiency for CFD simulations of complex flow in ship and ocean engineering.展开更多
The cylindrical shell is one of the main structural parts in ocean engineering structures.These cylinders are mostly of medium length,which means that the radius of the cross section is significantly smaller than the ...The cylindrical shell is one of the main structural parts in ocean engineering structures.These cylinders are mostly of medium length,which means that the radius of the cross section is significantly smaller than the length of the cylindrical shell.From the viewpoint of the shell theory,they belong to the mid-long cylindrical shell category.To solve mechanical problems on this kind of structure,especially a cracked cylindrical shell,analysis based on shell theory is necessary.At present the generally used solving system for the mid-long cylindrical shell is too complicated,difficult to solve,and inapplicable to engineering.This paper introduced the Sanders' mid-long cylindrical shell theory which reduces the difficulty of the solution process,and will be suitable for solving problems with complicated boundary conditions.On this basis,the engineering applications of this theory were discussed in conjunction with the problem of a mid-long cylindrical shell having a circumferential crack.The solution process is simple,and the closed form solution can usually be found.In practical engineering applications,it gives satisfactory precision.展开更多
Electrocatalytic glucose oxidation to high-value chemicals provides a sustainable route for biomass valorization.NiCo-based catalysts have emerged as promising candidates for glucose oxidation reaction owing to the in...Electrocatalytic glucose oxidation to high-value chemicals provides a sustainable route for biomass valorization.NiCo-based catalysts have emerged as promising candidates for glucose oxidation reaction owing to the intrinsic activity of Ni and Co catalytic centers.However,the dynamic evolution and atomic-scale synergy between these centers remain elusive.Herein,we fabricated NiCo_(2)O_(4)nanosheets supported on nickel foam,where Ni preferentially occupies tetrahedral sites to regulate the electronic configuration of octahedral Co.Experimental and theoretical results demonstrate that the incorporation of tetrahedral Ni induces low-to-intermediate spin transition in octahedral Co,thereby optimizing eg orbital occupancy and stabilizing active sites.This spin-state engineering establishes Ni-Co synergistic catalytic centers for the selective oxidation of glucose to formate(FA).At higher potential(≥1.4 V vs.RHE),octahedral Co undergoes reconstruction into excessive active CoOOH and CoO_(2)species,resulting in glucose overoxidation to CO_(2)and intensified competitive oxygen evolution.In contrast,at lower potentials(<1.4 V vs.RHE),tetrahedral Ni facilitates electron delocalization across the Ni–O–Co lattice,thereby stabilizing octahedral Co for glucose adsorption and oxidation.Subsequently,a coupled electrocatalytic system was constructed,achieving 80.7%FA yield with 91.3%Faradaic efficiency(FE)at NiCo_(2)O_(4)anode and H2 evolution rate of 696μmol h^(−1)with 99.9%FE at Pt cathode for 2 h under 1.35 V vs.RHE.This work provides a deep insight into spin-state regulation of the catalytic center,offering valuable guidance for rational catalyst design.展开更多
Most hydrodynamic problems in ship and ocean engineering are complex and highly coupled.Under the trend of intelligent and digital design for ships and ocean engineering structures,comprehensive performance evaluation...Most hydrodynamic problems in ship and ocean engineering are complex and highly coupled.Under the trend of intelligent and digital design for ships and ocean engineering structures,comprehensive performance evaluation and optimization are of vital importance during design.In this process,various coupling effects need to be accurately predicted.With the significant progress of computational fluid dynamics(CFD),many advanced numerical models were proposed to simulate the complex coupling hydrodynamic problems in ship and ocean engineering field.In this paper,five key coupling hydrodynamic problems are introduced,which are hull-propeller-rudder coupling,wave-floating structure coupling,aerodynamic-hydrodynamic coupling,fluid structure coupling and fluid-noise coupling,respectively.The paper focuses on the numerical simulation techniques corresponding to each coupling problem,including the theories and the applications.Future directions and conclusions are provided finally.展开更多
Lightweight materials with wide absorption capabilities,particularly in the C-band,have remained a challenge thus far.Recent research has indicated that effective absorption networks built by microfiber polarization l...Lightweight materials with wide absorption capabilities,particularly in the C-band,have remained a challenge thus far.Recent research has indicated that effective absorption networks built by microfiber polarization loss can be a significant factor in increasing the effective absorption bandwidth(EAB).In this study,leaf vein-like carbon(LVC)was synthesized using an in situ blowing strategy.Taking inspiration from photosynthesis energy conversion mechanisms,a leaf veins-like hierarchical structure was created to establish an effective impedance-matching network and generate a high-density polarization region through leaf vein microfibers.This enhanced polarization relaxation effectively broadens the EAB of the LVC.At a low filling ratio of 6.3 wt%,the EAB of the LVC covers 80%of the C-band,as well as100%of the X-band and Ku-band.Achieving such a wide EAB in the C-band,especially in the multi-band context,relies on impedance matching and optimized polarization relaxation.This work demonstrates the crucial role of leaf vein micronetwork engineering in enhancing the C-band absorption properties of carbon-based materials,thus providing a viable reference for the development of lightweight,broadband,and highly absorptive materials for electromagnetic applications.展开更多
An analytical model of a floating heaving box integrated with a vertical flexible porous membrane placed right next to the box applications to wave energy extraction and breakwater systems is developed under the reduc...An analytical model of a floating heaving box integrated with a vertical flexible porous membrane placed right next to the box applications to wave energy extraction and breakwater systems is developed under the reduced wave equation.The theoretical solutions for the heave radiating potential to the assigned physical model in the corresponding zones are attained by using the separation of variables approach along with the Fourier expansion.Applying the matching eigenfunction expansion technique and orthogonal conditions,the unknown coefficients that are involved in the radiated potentials are determined.The attained radiation potential allows the computation of hydrodynamic coefficients of the heaving buoy,Power Take-Off damping,and wave quantities.The accuracy of the analytical solution for the hydrodynamic coefficients is demonstrated for different oblique angles with varying numbers of terms in the series solution.The current analytical analysis findings are confirmed by existing published numerical boundary element method simulations.Several numerical results of the hydrodynamic coefficients,power capture,power take-off optimal damping,and transmission coefficients for numerous structural and physical aspects are conducted.It has been noted that the ideal power take-off damping increases as the angle of incidence rises,and the analysis suggests that the ability to capture waves is more effective in shallower waters compared to deeper ones.展开更多
A hybrid model combining Fully Non-Linear Potential Flow Theory(FNPT)based on the Finite Element Method(FEM)and the Unified Navier-Stokes equation,using the 3D Improved Meshless Local Petrov Galerkin method with Ranki...A hybrid model combining Fully Non-Linear Potential Flow Theory(FNPT)based on the Finite Element Method(FEM)and the Unified Navier-Stokes equation,using the 3D Improved Meshless Local Petrov Galerkin method with Rankine Source(IMLPG_R),is developed to study wave interactions with a porous layer.In previous studies,the above formulations are applied to wave interaction with fixed cylindrical structures.The present study extends this framework by integrating a unified governing equation within the hybrid modeling approach to capture the dynamics of wave interaction with porous media.The porous layers are employed to replicate the wave-dissipating behavior of the structure.A weak coupling strategy is implemented within a designated buffer zone,wherein field variables from the 2D Fully Nonlinear Potential Theory(FNPT)simulations are transferred to the 3D Improved Moving Least Squares-based Petrov-Galerkin(IMLPG_R)model at each time step.This domain decomposition significantly reduces computational cost compared to a full 3D simulation by partitioning the domain into two subregions:the FNPT domain representing the far-field without structures,and the IMLPG_R domain encompassing the porous region.The Unified Navier-Stokes formulation is extended by incorporating additional drag forces governed by Darcy’s law to model the resistance introduced by the porous medium.A stationary background node framework is utilized for interpolation by fluid particles at each time step to accommodate the porous representation.To enhance numerical stability and accuracy,particularly in the presence of sloping boundaries,the Particle Shifting Technique(PST)is integrated into the IMLPG_R model.This implementation involves a modified version of the PST algorithm,where key parameters such as the weight function,velocity ratio,and radius of influence are optimized for IMLPG_R.This is the first time the application of 3D IMLPG_R for porous structure has been reported.Further,the model is subsequently validated against experimental data.展开更多
Rock slope instability is a prevalent geological hazard that imposes significant adverse impacts on engineering activities.Although existing studies have focused on homogeneous rock slopes,the theoretical models for q...Rock slope instability is a prevalent geological hazard that imposes significant adverse impacts on engineering activities.Although existing studies have focused on homogeneous rock slopes,the theoretical models for quantifying the stability of softhard interbedded anti-inclined slopes remain underdeveloped,primarily due to the complex force transfer mechanisms involved.This study proposed a novel theoretical model for the stability analysis of soft-hard interbedded anti-inclined slopes under rainfall conditions.The framework models stratified rock layers as layered cantilever beams with material heterogeneity.Based on the principle of deformation compatibility,it comprehensively accounted for interlayer force transfer and strength degradation resulting from differential deformations among rock layers.Furthermore,it integrated the critical instability length induced by the self-weight of rock layers to determine the fracture depth.The proposed method was validated against engineering case studies and physical model tests,with error falling within an acceptable range.Compared to existing theoretical methods,the proposed method provided a more realistic representation of the slope's stress field.The analysis results demonstrate that rainfall not only reduces the inclination angle of the failure surface but also leads to an approximate 30%decrease in the safety factor.The proposed theoretical model is particularly useful for quickly calculating the stability of soft-hard interbedded anti-inclined rock slope under rainfall conditions,compared to complex and time-consuming numerical simulation calculations.展开更多
This study examines the methods to plan the development of offshore oilfields over the years,which are used to support the decision-making on the development of offshore oilfields.About 100 papers are analysed and cat...This study examines the methods to plan the development of offshore oilfields over the years,which are used to support the decision-making on the development of offshore oilfields.About 100 papers are analysed and categorised into different groups of main early-stage decisions.The present study stands in contrast to the contributions of the operations research and system engineering review articles,on the one hand,and the petroleum engineering review articles,on the other.This is because it does not focus on one methodological approach,nor does it limit the literature analysis by offshore oilfield characteristics.Consequently,the present analysis may offer valuable insights,for instance,by identifying environmental planning decisions as a recent yet highly significant concern that is currently being imposed on decision-making process.Thus,it is evident that the incorporation of safety criteria within the technical-economic decision-making process for the design of production systems would be a crucial requirement at development phase.展开更多
Zinc-air batteries(ZABs)are promising candidates for flexible electronics due to their high energy density and low cost.However,their development is hindered by the sluggish kinetics of the oxygen evolution reaction(O...Zinc-air batteries(ZABs)are promising candidates for flexible electronics due to their high energy density and low cost.However,their development is hindered by the sluggish kinetics of the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR).Herein,we present a novel heterostructured electrocatalyst composed of vertically aligned N-doped graphene(NVG)arrays anchored on Ru-doped ceria(RCO)nanofibers,synthesized via a one-step plasma-enhanced chemical vapor deposition process.Notably,during the plasma-enhanced driven NVG growth,Ru nanoparticles are spontaneously in-situ exsolved from the RCO lattice,forming a unique Ru@RCO-NVG heterostructure.Density functional theory calculations reveal that the Ru@RCO-NVG heterojunction induces interfacial electronic redistribution,thereby significantly lowering the energy barriers for both OER and ORR.Benefiting from the synergistic effects,the Ru@RCO-NVG catalyst exhibits exceptional intrinsic activity towards OER/ORR(an overpotential of 370 mV for OER at 10 mA cm^(−2)and a half-wave potential of 0.86 V for ORR),and higher all-solid-state flexible ZAB performance(peak power density of 286.1 mW cm^(−2)),surpassing commercial Pt/C-IrO_(2)catalysts.This work not only advances the integration of synergistic graphene/ceria composites but also offers a promising strategy for designing efficient electrocatalysts for next-generation energy conversion technologies.展开更多
To address critical challenges in nighttime ship detection—high small-target missed detection(over 20%),insufficient lightweighting,and limited generalization due to scarce,low-quality datasets—this study proposes a...To address critical challenges in nighttime ship detection—high small-target missed detection(over 20%),insufficient lightweighting,and limited generalization due to scarce,low-quality datasets—this study proposes a systematic solution.First,a high-quality Night-Ships dataset is constructed via CycleGAN-based day-night transfer,combined with a dual-threshold cleaning strategy(Laplacian variance sharpness filtering and brightness-color deviation screening).Second,a Cross-stage Lightweight Fusion-You Only Look Once version 8(CLF-YOLOv8)is proposed with key improvements:the Neck network is reconstructed by replacing Cross Stage Partial(CSP)structure with the Cross Stage Partial Multi-Scale Convolutional Block(CSP-MSCB)and integrating Bidirectional Feature Pyramid Network(BiFPN)for weighted multi-scale fusion to enhance small-target detection;a Lightweight Shared Convolutional and Separated Batch Normalization Detection-Head(LSCSBD-Head)with shared convolutions and layer-wise Batch Normalization(BN)reduces parameters to 1.8M(42% fewer than YOLOv8n);and the FocalMinimum Point Distance Intersection over Union(Focal-MPDIoU)loss combines Minimum Point Distance Intersection over Union(MPDIoU)geometric constraints and Focal weighting to optimize low-overlap targets.Experiments show CLFYOLOv8 achieves 97.6%mAP@0.5(0.7% higher than YOLOv8n)with 1.8 M parameters,outperforming mainstream models in small-target detection,overlapping target discrimination,and adaptability to complex lighting.展开更多
Crack detection accuracy in computer vision is often constrained by limited annotated datasets.Although Generative Adversarial Networks(GANs)have been applied for data augmentation,they frequently introduce blurs and ...Crack detection accuracy in computer vision is often constrained by limited annotated datasets.Although Generative Adversarial Networks(GANs)have been applied for data augmentation,they frequently introduce blurs and artifacts.To address this challenge,this study leverages Denoising Diffusion Probabilistic Models(DDPMs)to generate high-quality synthetic crack images,enriching the training set with diverse and structurally consistent samples that enhance the crack segmentation.The proposed framework involves a two-stage pipeline:first,DDPMs are used to synthesize high-fidelity crack images that capture fine structural details.Second,these generated samples are combined with real data to train segmentation networks,thereby improving accuracy and robustness in crack detection.Compared with GAN-based approaches,DDPM achieved the best fidelity,with the highest Structural Similarity Index(SSIM)(0.302)and lowest Learned Perceptual Image Patch Similarity(LPIPS)(0.461),producing artifact-free images that preserve fine crack details.To validate its effectiveness,six segmentation models were tested,among which LinkNet consistently achieved the best performance,excelling in both region-level accuracy and structural continuity.Incorporating DDPM-augmented data further enhanced segmentation outcomes,increasing F1 scores by up to 1.1%and IoU by 1.7%,while also improving boundary alignment and skeleton continuity compared with models trained on real images alone.Experiments with varying augmentation ratios showed consistent improvements,with F1 rising from 0.946(no augmentation)to 0.957 and IoU from 0.897 to 0.913 at the highest ratio.These findings demonstrate the effectiveness of diffusion-based augmentation for complex crack detection in structural health monitoring.展开更多
The coupled chemo-mechanical impact of supercritical CO_(2)-H_(2)O(ScCO_(2)-H_(2)O)reactions on fracture geometry and nonlinear flow regimes in deep shale under confining pressures remains inadequately quantified.This...The coupled chemo-mechanical impact of supercritical CO_(2)-H_(2)O(ScCO_(2)-H_(2)O)reactions on fracture geometry and nonlinear flow regimes in deep shale under confining pressures remains inadequately quantified.This study systematically investigates the effects of ScCO_(2)-H_(2)O-shale interactions on fracture morphology and flow properties under confining pressures from 15 MPa to 40 MPa by integrating XRD(X-ray diffraction),micro-CT,3D surface profilometry,and multistage steady-state flow experiments.The results demonstrate that ScCO_(2)-H_(2)O exposure drives pyrite/feldspar dissolution and localized clay precipitation,resulting in fracture branching and macroscopic aperture regularization.Critically,confining pressure dictates the net hydraulic response:under low confining pressure(15-25 MPa),dissolution dominates,enhancing permeability,flow efficiency(Q/VP),and pre-linear flow behavior(n<1).At high confining pressures(30-40 MPa)mechanical compaction and mineral precipitation amplify flow resistance,shifting the flow regime toward quasi-linear behavior,as inertial effects become negligible compared to dominant viscous forces and increased flow resistance.Confining pressure thus critically mediates the dissolution-precipitation balance during ScCO_(2)-H_(2)O treatment,with an optimal window of 15-25 MPa identified for enhancing conductivity while minimizing clogging risk.These findings provide a quantitative framework for predicting stress-dependent flow evolution in chemically altered shale fractures.展开更多
An in-built N^(+)pocket electrically doped tunnel field-effect transistor(ED-TFET)-based biosensor has been reported for the first time.The proposed device begins with a PN junction structure with a control gate(CG)an...An in-built N^(+)pocket electrically doped tunnel field-effect transistor(ED-TFET)-based biosensor has been reported for the first time.The proposed device begins with a PN junction structure with a control gate(CG)and two polarity gates(PG1 and PG2).Utilizing the polarity bias concept,a narrow N^(+)pocket is formed between the source and channel without the need for additional doping steps,achieved through biasing PG1 and PG2 at-1.2 V and 1.2 V,respectively.This method not only addresses issues related to doping control but also eliminates constraints associated with thermal budgets and simplifies the fabrication process compared to traditional TFETs.To facilitate biomolecule sensing within the device,a nanogap cavity is formed in the gate dielectric by selectively etching a section of the polarity gate dielectric layer toward the source side.The investigation into the presence of neutral and charged molecules within the cavities has been conducted by examining variations in the electrical properties of the proposed biosensor.Key characteristics assessed include drain current,energy band,and electric field distribution.The performance of the biosensor is measured using various metrics such as drain current(I_(DS)),subthreshold swing(SS),threshold voltage(V_(TH)),drain current ratio(I_(ON)/I_(OFF)).The proposed in-built N^(+)pocket ED-TFET-based biosensor reaches a peak sensitivity of 1.08×10~(13)for a neutral biomolecule in a completely filled nanogap with a dielectric constant of 12.Additionally,the effects of cavity geometry and different fill factors(FFs)on sensitivity are studied.展开更多
1.Introduction Artificial intelligence(AI)is rapidly reshaping geoscience,from Earth observation interpretation and hazard forecasting to subsurface characterisation and Earth system modelling(Kochupillai et al.,2022;...1.Introduction Artificial intelligence(AI)is rapidly reshaping geoscience,from Earth observation interpretation and hazard forecasting to subsurface characterisation and Earth system modelling(Kochupillai et al.,2022;Sun et al.,2024).These capabilities emerge at a time when geoscientific evidence is increasingly informing high-stakes decisions about climate adaptation,resource development,and disaster risk reduction(McGovern et al.,2022).展开更多
Based on the analysis of the advantages and disadvantages of some vertical coordinates applied in the calculation of the Changjiang diluted water （CDW）, a new hybrid vertical coordinate is designed, which uses σ co...Based on the analysis of the advantages and disadvantages of some vertical coordinates applied in the calculation of the Changjiang diluted water （CDW）, a new hybrid vertical coordinate is designed, which uses σ coordinate for current and σ-z coordinate for salinity. To combine the current and salinity, the Eulerian-Lagrangian method is used for the salinity calculation, and the baroclinic pressure gradient （BPG） is calculated on the salinity sited layers. The new hybrid vertical coordinate is introduced to the widely used model of POM （Princeton Ocean Model） to make a new model of POM-σ-z. The BPG calculations of an ideal case show that POM-σ-z model brings smaller error than POM model does. The simulations of CDW also show that POM-σ-z model is better than POM model on simulating the salinity and its front.展开更多
The phase change characteristic of the power source of an underwater glider propelled by the ocean＇s thermal energy is the key factor in glider attitude control. A numerical model has been established based on the en...The phase change characteristic of the power source of an underwater glider propelled by the ocean＇s thermal energy is the key factor in glider attitude control. A numerical model has been established based on the enthalpy method to analyze the phase change heat transfer process under convective boundary conditions. Phase change is not an isothermal process, but one that occurs at a range of temperature. The total melting time of the material is very sensitive to the surrounding temperature. When the temperature of the surroundings decreases 8 degrees, the total melting time increases 1.8 times. But variations in surrounding temperature have little effect on the initial temperature of phase change, and the slope of the temperature time history curve remains the same. However, the temperature at which phase change is completed decreases significantly. Our research shows that the phase change process is also affected by container size, boundary conditions, and the power source＇s cross sectional area. Materials stored in 3 cylindrical containers with a diameter of 38ram needed the shortest phase change time. Our conclusions should be helpful in effective design of underwater glider power systems.展开更多
Knowledge-Based Engineering （KBE） is introduced into the ship structural design in this paper. From the implementation of KBE, the design solutions for both Rules Design Method （RDM） and Interpolation Design Meth...Knowledge-Based Engineering （KBE） is introduced into the ship structural design in this paper. From the implementation of KBE, the design solutions for both Rules Design Method （RDM） and Interpolation Design Method （IDM） are generated. The corresponding Finite Element （FE） models are generated. Topological design of the longitudinal structures is studied where the Gaussian Process （GP） is employed to build the surrogate model for FE analysis. Multi-objective optimization methods inspired by Pareto Front are used to reduce the design tank weight and outer surface area simultaneously. Additionally, an enhanced Level Set Method （LSM） which employs implicit algorithm is applied to the topological design of typical bracket plate which is used extensively in ship structures. Two different sets of boundary conditions are considered. The proposed methods show satisfactory efficiency and accuracy.展开更多
It has been proved that the thermally insulated ocean pipeline has advantages over the conventional pipe-in-pipe pipeline. The risk of using the thermally insulated pipeline is that the exterior layers covering the st...It has been proved that the thermally insulated ocean pipeline has advantages over the conventional pipe-in-pipe pipeline. The risk of using the thermally insulated pipeline is that the exterior layers covering the steel pipe may be. pulled off if the shear stress on the interface induced by the pullout fore from the tensioner is greater than the binding fore between two neighboring layers during installation. This paper develops a procedure to calculate the shear stress on the interface. The binding force between two neighboring layers can be determined with full scale model tests. The safety of the thermally insulated pipe under installation can then be checked by comparison of the interface shear stress with the binding force.展开更多
基金supported by the National Natural Science Foundation of China(51809169,51879159)Chang Jiang Scholars Program(T2014099)+2 种基金Shanghai Excellent Academic Leaders Program(17XD1402300)Innovative Special Project of Numerical Tank of Ministry of Industry and Information Technology of China(2016-23/09)National Key Research and Development Program of China(2019YFB1704203,2019YFC0312400).
文摘Complex flow around floating structures is a highly nonlinear problem,and it is a typical feature in ship and ocean engineering.Traditional experimental methods and potential flow theory have limitations in predicting complex viscous flows.With the improvement of high-performance computing and the development of numerical techniques,computational fluid dynamics(CFD)has become increasingly powerful in predicting the complex viscous flow around floating structures.This paper reviews the recent progress in CFD techniques for numerical solutions of typical complex viscous flows in ship and ocean engineering.Applications to free-surface flows,breaking bow waves of high-speed ship,ship hull-propeller-rudder interaction,vortexinduced vibration of risers,vortex-induced motions of deep-draft platforms,and floating offshore wind turbines are discussed.Typical techniques,including volume of fluid for sharp interface,dynamic overset grid,detached eddy simulation,and fluid-structure coupling,are reviewed along with their applications.Some novel techniques,such as high-efficiency Cartesian grid method and GPU acceleration technique,are discussed in the last part as the future perspective for further enhancement of accuracy and efficiency for CFD simulations of complex flow in ship and ocean engineering.
基金Supported by the National Natural Science Foundation of China under Grant No.（50579023）.
文摘The cylindrical shell is one of the main structural parts in ocean engineering structures.These cylinders are mostly of medium length,which means that the radius of the cross section is significantly smaller than the length of the cylindrical shell.From the viewpoint of the shell theory,they belong to the mid-long cylindrical shell category.To solve mechanical problems on this kind of structure,especially a cracked cylindrical shell,analysis based on shell theory is necessary.At present the generally used solving system for the mid-long cylindrical shell is too complicated,difficult to solve,and inapplicable to engineering.This paper introduced the Sanders' mid-long cylindrical shell theory which reduces the difficulty of the solution process,and will be suitable for solving problems with complicated boundary conditions.On this basis,the engineering applications of this theory were discussed in conjunction with the problem of a mid-long cylindrical shell having a circumferential crack.The solution process is simple,and the closed form solution can usually be found.In practical engineering applications,it gives satisfactory precision.
基金financially supported by the National Natural Science Foundation of China (22472199)Chinese Universities Scientific Fund (15055009)Central University Guided Funds for Building World-Class Universities (Disciplines) and Advancing Characteristic Development
文摘Electrocatalytic glucose oxidation to high-value chemicals provides a sustainable route for biomass valorization.NiCo-based catalysts have emerged as promising candidates for glucose oxidation reaction owing to the intrinsic activity of Ni and Co catalytic centers.However,the dynamic evolution and atomic-scale synergy between these centers remain elusive.Herein,we fabricated NiCo_(2)O_(4)nanosheets supported on nickel foam,where Ni preferentially occupies tetrahedral sites to regulate the electronic configuration of octahedral Co.Experimental and theoretical results demonstrate that the incorporation of tetrahedral Ni induces low-to-intermediate spin transition in octahedral Co,thereby optimizing eg orbital occupancy and stabilizing active sites.This spin-state engineering establishes Ni-Co synergistic catalytic centers for the selective oxidation of glucose to formate(FA).At higher potential(≥1.4 V vs.RHE),octahedral Co undergoes reconstruction into excessive active CoOOH and CoO_(2)species,resulting in glucose overoxidation to CO_(2)and intensified competitive oxygen evolution.In contrast,at lower potentials(<1.4 V vs.RHE),tetrahedral Ni facilitates electron delocalization across the Ni–O–Co lattice,thereby stabilizing octahedral Co for glucose adsorption and oxidation.Subsequently,a coupled electrocatalytic system was constructed,achieving 80.7%FA yield with 91.3%Faradaic efficiency(FE)at NiCo_(2)O_(4)anode and H2 evolution rate of 696μmol h^(−1)with 99.9%FE at Pt cathode for 2 h under 1.35 V vs.RHE.This work provides a deep insight into spin-state regulation of the catalytic center,offering valuable guidance for rational catalyst design.
基金Project supported by the National Natural Science Foundation of China(Grant No.51879159,51809169 and 51909160)the National Key Research and Development Program of China(Grant Nos.2019YFB1704200,2019YFC0312400)+2 种基金This work was supported by the Chang Jiang Scholars Program(Grant No.T2014099)the Shanghai Excellent Academic Leaders Program(Grant No.17XD1402300)the Innovative Special Project of Numerical Tank of Ministry of Industry and Information Technology of China(2016-23/09).
文摘Most hydrodynamic problems in ship and ocean engineering are complex and highly coupled.Under the trend of intelligent and digital design for ships and ocean engineering structures,comprehensive performance evaluation and optimization are of vital importance during design.In this process,various coupling effects need to be accurately predicted.With the significant progress of computational fluid dynamics(CFD),many advanced numerical models were proposed to simulate the complex coupling hydrodynamic problems in ship and ocean engineering field.In this paper,five key coupling hydrodynamic problems are introduced,which are hull-propeller-rudder coupling,wave-floating structure coupling,aerodynamic-hydrodynamic coupling,fluid structure coupling and fluid-noise coupling,respectively.The paper focuses on the numerical simulation techniques corresponding to each coupling problem,including the theories and the applications.Future directions and conclusions are provided finally.
基金financially supported by the National Natural Science Youth Foundation of China(No.52402086)Natural Science Foundation of Shandong Province(No.ZR2023QE002)+6 种基金Youth Innovation Team Program in Colleges of Shandong Province(No.2023KJ144)Shandong Province Science and Technology Small and Medium-sized Enterprises Innovation Capability Improvement Project(No.2022TSGC1158)China Postdoctoral Science Foundation(No.2021M691963)Key Research and Development Program of Shandong Province of China(No.2020JMRH0503)the Fundamental Research Funds for the Central Universities(No.HIT.OCEF.2021003)National Natural Science Foundation of China(No.52272067)Doctoral Scientific Research Start-up Foundation from Shandong University of Technology(No.4041/419008)
文摘Lightweight materials with wide absorption capabilities,particularly in the C-band,have remained a challenge thus far.Recent research has indicated that effective absorption networks built by microfiber polarization loss can be a significant factor in increasing the effective absorption bandwidth(EAB).In this study,leaf vein-like carbon(LVC)was synthesized using an in situ blowing strategy.Taking inspiration from photosynthesis energy conversion mechanisms,a leaf veins-like hierarchical structure was created to establish an effective impedance-matching network and generate a high-density polarization region through leaf vein microfibers.This enhanced polarization relaxation effectively broadens the EAB of the LVC.At a low filling ratio of 6.3 wt%,the EAB of the LVC covers 80%of the C-band,as well as100%of the X-band and Ku-band.Achieving such a wide EAB in the C-band,especially in the multi-band context,relies on impedance matching and optimized polarization relaxation.This work demonstrates the crucial role of leaf vein micronetwork engineering in enhancing the C-band absorption properties of carbon-based materials,thus providing a viable reference for the development of lightweight,broadband,and highly absorptive materials for electromagnetic applications.
基金Open access funding provided by FCT|FCCN(b-on)the Strategic Research Plan of the Centre for Marine Technology and Ocean Engineering(CENTEC),which is financed by the Portuguese Foundation for Science and Technology(Fundação para a Ciência e Tecnologia-FCT)under contract UIDB/UIDP/00134/2020.
文摘An analytical model of a floating heaving box integrated with a vertical flexible porous membrane placed right next to the box applications to wave energy extraction and breakwater systems is developed under the reduced wave equation.The theoretical solutions for the heave radiating potential to the assigned physical model in the corresponding zones are attained by using the separation of variables approach along with the Fourier expansion.Applying the matching eigenfunction expansion technique and orthogonal conditions,the unknown coefficients that are involved in the radiated potentials are determined.The attained radiation potential allows the computation of hydrodynamic coefficients of the heaving buoy,Power Take-Off damping,and wave quantities.The accuracy of the analytical solution for the hydrodynamic coefficients is demonstrated for different oblique angles with varying numbers of terms in the series solution.The current analytical analysis findings are confirmed by existing published numerical boundary element method simulations.Several numerical results of the hydrodynamic coefficients,power capture,power take-off optimal damping,and transmission coefficients for numerous structural and physical aspects are conducted.It has been noted that the ideal power take-off damping increases as the angle of incidence rises,and the analysis suggests that the ability to capture waves is more effective in shallower waters compared to deeper ones.
基金funded by Prime Minister’s Research Fellowship(PMRF),grant number SB22230924OEPMRF008608.
文摘A hybrid model combining Fully Non-Linear Potential Flow Theory(FNPT)based on the Finite Element Method(FEM)and the Unified Navier-Stokes equation,using the 3D Improved Meshless Local Petrov Galerkin method with Rankine Source(IMLPG_R),is developed to study wave interactions with a porous layer.In previous studies,the above formulations are applied to wave interaction with fixed cylindrical structures.The present study extends this framework by integrating a unified governing equation within the hybrid modeling approach to capture the dynamics of wave interaction with porous media.The porous layers are employed to replicate the wave-dissipating behavior of the structure.A weak coupling strategy is implemented within a designated buffer zone,wherein field variables from the 2D Fully Nonlinear Potential Theory(FNPT)simulations are transferred to the 3D Improved Moving Least Squares-based Petrov-Galerkin(IMLPG_R)model at each time step.This domain decomposition significantly reduces computational cost compared to a full 3D simulation by partitioning the domain into two subregions:the FNPT domain representing the far-field without structures,and the IMLPG_R domain encompassing the porous region.The Unified Navier-Stokes formulation is extended by incorporating additional drag forces governed by Darcy’s law to model the resistance introduced by the porous medium.A stationary background node framework is utilized for interpolation by fluid particles at each time step to accommodate the porous representation.To enhance numerical stability and accuracy,particularly in the presence of sloping boundaries,the Particle Shifting Technique(PST)is integrated into the IMLPG_R model.This implementation involves a modified version of the PST algorithm,where key parameters such as the weight function,velocity ratio,and radius of influence are optimized for IMLPG_R.This is the first time the application of 3D IMLPG_R for porous structure has been reported.Further,the model is subsequently validated against experimental data.
基金supported by the Chongqing Water Conservancy Science and Technology Project(grant number:CQSLK-202329)the Natural Science Foundation of Chongqing,China(grant number:CSTB2022NSCQ-MSX0991)+1 种基金the National Natural Science Foundation of China(grant number:52378327)the Chongqing Natural Science Foundation Innovation Development Joint Fund(grant number:CSTB2022NSCQ-LZX0049)。
文摘Rock slope instability is a prevalent geological hazard that imposes significant adverse impacts on engineering activities.Although existing studies have focused on homogeneous rock slopes,the theoretical models for quantifying the stability of softhard interbedded anti-inclined slopes remain underdeveloped,primarily due to the complex force transfer mechanisms involved.This study proposed a novel theoretical model for the stability analysis of soft-hard interbedded anti-inclined slopes under rainfall conditions.The framework models stratified rock layers as layered cantilever beams with material heterogeneity.Based on the principle of deformation compatibility,it comprehensively accounted for interlayer force transfer and strength degradation resulting from differential deformations among rock layers.Furthermore,it integrated the critical instability length induced by the self-weight of rock layers to determine the fracture depth.The proposed method was validated against engineering case studies and physical model tests,with error falling within an acceptable range.Compared to existing theoretical methods,the proposed method provided a more realistic representation of the slope's stress field.The analysis results demonstrate that rainfall not only reduces the inclination angle of the failure surface but also leads to an approximate 30%decrease in the safety factor.The proposed theoretical model is particularly useful for quickly calculating the stability of soft-hard interbedded anti-inclined rock slope under rainfall conditions,compared to complex and time-consuming numerical simulation calculations.
基金the Strategic Research Plan of the Centre for Marine Technology and Ocean Engineering(CENTEC),which is financed by the Portuguese Foundation for Science and Technology(Fundação para a Ciência e a Tecnologia FCT)under contract UIDB/UIDP/00134/2020.
文摘This study examines the methods to plan the development of offshore oilfields over the years,which are used to support the decision-making on the development of offshore oilfields.About 100 papers are analysed and categorised into different groups of main early-stage decisions.The present study stands in contrast to the contributions of the operations research and system engineering review articles,on the one hand,and the petroleum engineering review articles,on the other.This is because it does not focus on one methodological approach,nor does it limit the literature analysis by offshore oilfield characteristics.Consequently,the present analysis may offer valuable insights,for instance,by identifying environmental planning decisions as a recent yet highly significant concern that is currently being imposed on decision-making process.Thus,it is evident that the incorporation of safety criteria within the technical-economic decision-making process for the design of production systems would be a crucial requirement at development phase.
基金supported by the National Natural Science Foundation of China(Grant No.22479133,and No.22469008)the Natural Science Foundation of Guangdong Province(Grant No.2024A1515012235).
文摘Zinc-air batteries(ZABs)are promising candidates for flexible electronics due to their high energy density and low cost.However,their development is hindered by the sluggish kinetics of the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR).Herein,we present a novel heterostructured electrocatalyst composed of vertically aligned N-doped graphene(NVG)arrays anchored on Ru-doped ceria(RCO)nanofibers,synthesized via a one-step plasma-enhanced chemical vapor deposition process.Notably,during the plasma-enhanced driven NVG growth,Ru nanoparticles are spontaneously in-situ exsolved from the RCO lattice,forming a unique Ru@RCO-NVG heterostructure.Density functional theory calculations reveal that the Ru@RCO-NVG heterojunction induces interfacial electronic redistribution,thereby significantly lowering the energy barriers for both OER and ORR.Benefiting from the synergistic effects,the Ru@RCO-NVG catalyst exhibits exceptional intrinsic activity towards OER/ORR(an overpotential of 370 mV for OER at 10 mA cm^(−2)and a half-wave potential of 0.86 V for ORR),and higher all-solid-state flexible ZAB performance(peak power density of 286.1 mW cm^(−2)),surpassing commercial Pt/C-IrO_(2)catalysts.This work not only advances the integration of synergistic graphene/ceria composites but also offers a promising strategy for designing efficient electrocatalysts for next-generation energy conversion technologies.
基金the Shandong Provincial Key Research and Development Program(Grant No.2024SFGC0201).
文摘To address critical challenges in nighttime ship detection—high small-target missed detection(over 20%),insufficient lightweighting,and limited generalization due to scarce,low-quality datasets—this study proposes a systematic solution.First,a high-quality Night-Ships dataset is constructed via CycleGAN-based day-night transfer,combined with a dual-threshold cleaning strategy(Laplacian variance sharpness filtering and brightness-color deviation screening).Second,a Cross-stage Lightweight Fusion-You Only Look Once version 8(CLF-YOLOv8)is proposed with key improvements:the Neck network is reconstructed by replacing Cross Stage Partial(CSP)structure with the Cross Stage Partial Multi-Scale Convolutional Block(CSP-MSCB)and integrating Bidirectional Feature Pyramid Network(BiFPN)for weighted multi-scale fusion to enhance small-target detection;a Lightweight Shared Convolutional and Separated Batch Normalization Detection-Head(LSCSBD-Head)with shared convolutions and layer-wise Batch Normalization(BN)reduces parameters to 1.8M(42% fewer than YOLOv8n);and the FocalMinimum Point Distance Intersection over Union(Focal-MPDIoU)loss combines Minimum Point Distance Intersection over Union(MPDIoU)geometric constraints and Focal weighting to optimize low-overlap targets.Experiments show CLFYOLOv8 achieves 97.6%mAP@0.5(0.7% higher than YOLOv8n)with 1.8 M parameters,outperforming mainstream models in small-target detection,overlapping target discrimination,and adaptability to complex lighting.
基金the National Natural Science Foundation of China(Grant No.:52508343)the Fundamental Research Funds for the Central Universities(Grant No.:B250201004).
文摘Crack detection accuracy in computer vision is often constrained by limited annotated datasets.Although Generative Adversarial Networks(GANs)have been applied for data augmentation,they frequently introduce blurs and artifacts.To address this challenge,this study leverages Denoising Diffusion Probabilistic Models(DDPMs)to generate high-quality synthetic crack images,enriching the training set with diverse and structurally consistent samples that enhance the crack segmentation.The proposed framework involves a two-stage pipeline:first,DDPMs are used to synthesize high-fidelity crack images that capture fine structural details.Second,these generated samples are combined with real data to train segmentation networks,thereby improving accuracy and robustness in crack detection.Compared with GAN-based approaches,DDPM achieved the best fidelity,with the highest Structural Similarity Index(SSIM)(0.302)and lowest Learned Perceptual Image Patch Similarity(LPIPS)(0.461),producing artifact-free images that preserve fine crack details.To validate its effectiveness,six segmentation models were tested,among which LinkNet consistently achieved the best performance,excelling in both region-level accuracy and structural continuity.Incorporating DDPM-augmented data further enhanced segmentation outcomes,increasing F1 scores by up to 1.1%and IoU by 1.7%,while also improving boundary alignment and skeleton continuity compared with models trained on real images alone.Experiments with varying augmentation ratios showed consistent improvements,with F1 rising from 0.946(no augmentation)to 0.957 and IoU from 0.897 to 0.913 at the highest ratio.These findings demonstrate the effectiveness of diffusion-based augmentation for complex crack detection in structural health monitoring.
基金support from the Science and Technology Innovation Program of Hunan Province(Grant No.2023RC1021)the Natural Science Foundation of Sichuan Province(Grant No.2025YFHZ0323).-。
文摘The coupled chemo-mechanical impact of supercritical CO_(2)-H_(2)O(ScCO_(2)-H_(2)O)reactions on fracture geometry and nonlinear flow regimes in deep shale under confining pressures remains inadequately quantified.This study systematically investigates the effects of ScCO_(2)-H_(2)O-shale interactions on fracture morphology and flow properties under confining pressures from 15 MPa to 40 MPa by integrating XRD(X-ray diffraction),micro-CT,3D surface profilometry,and multistage steady-state flow experiments.The results demonstrate that ScCO_(2)-H_(2)O exposure drives pyrite/feldspar dissolution and localized clay precipitation,resulting in fracture branching and macroscopic aperture regularization.Critically,confining pressure dictates the net hydraulic response:under low confining pressure(15-25 MPa),dissolution dominates,enhancing permeability,flow efficiency(Q/VP),and pre-linear flow behavior(n<1).At high confining pressures(30-40 MPa)mechanical compaction and mineral precipitation amplify flow resistance,shifting the flow regime toward quasi-linear behavior,as inertial effects become negligible compared to dominant viscous forces and increased flow resistance.Confining pressure thus critically mediates the dissolution-precipitation balance during ScCO_(2)-H_(2)O treatment,with an optimal window of 15-25 MPa identified for enhancing conductivity while minimizing clogging risk.These findings provide a quantitative framework for predicting stress-dependent flow evolution in chemically altered shale fractures.
基金Project supported by the Ministry of Education’s Supply and Demand Matching Employment and Education Project(Grant No.2024110776329)。
文摘An in-built N^(+)pocket electrically doped tunnel field-effect transistor(ED-TFET)-based biosensor has been reported for the first time.The proposed device begins with a PN junction structure with a control gate(CG)and two polarity gates(PG1 and PG2).Utilizing the polarity bias concept,a narrow N^(+)pocket is formed between the source and channel without the need for additional doping steps,achieved through biasing PG1 and PG2 at-1.2 V and 1.2 V,respectively.This method not only addresses issues related to doping control but also eliminates constraints associated with thermal budgets and simplifies the fabrication process compared to traditional TFETs.To facilitate biomolecule sensing within the device,a nanogap cavity is formed in the gate dielectric by selectively etching a section of the polarity gate dielectric layer toward the source side.The investigation into the presence of neutral and charged molecules within the cavities has been conducted by examining variations in the electrical properties of the proposed biosensor.Key characteristics assessed include drain current,energy band,and electric field distribution.The performance of the biosensor is measured using various metrics such as drain current(I_(DS)),subthreshold swing(SS),threshold voltage(V_(TH)),drain current ratio(I_(ON)/I_(OFF)).The proposed in-built N^(+)pocket ED-TFET-based biosensor reaches a peak sensitivity of 1.08×10~(13)for a neutral biomolecule in a completely filled nanogap with a dielectric constant of 12.Additionally,the effects of cavity geometry and different fill factors(FFs)on sensitivity are studied.
基金supported by the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20240937)the Natural Science Foundation of Shandong Province(Grant No.ZR2021QE187)+2 种基金the Shandong Higher Education“Young Entrepreneurship Talents Introduction and Cultivation Program”Project(Grant No.ZXQT20221228001)the Natural Science Foundation of China(Grant No.42502273)the Science and Technology Innovation Program of Hunan Province(Grant No.2022RC4028).
文摘1.Introduction Artificial intelligence(AI)is rapidly reshaping geoscience,from Earth observation interpretation and hazard forecasting to subsurface characterisation and Earth system modelling(Kochupillai et al.,2022;Sun et al.,2024).These capabilities emerge at a time when geoscientific evidence is increasingly informing high-stakes decisions about climate adaptation,resource development,and disaster risk reduction(McGovern et al.,2022).
文摘Based on the analysis of the advantages and disadvantages of some vertical coordinates applied in the calculation of the Changjiang diluted water （CDW）, a new hybrid vertical coordinate is designed, which uses σ coordinate for current and σ-z coordinate for salinity. To combine the current and salinity, the Eulerian-Lagrangian method is used for the salinity calculation, and the baroclinic pressure gradient （BPG） is calculated on the salinity sited layers. The new hybrid vertical coordinate is introduced to the widely used model of POM （Princeton Ocean Model） to make a new model of POM-σ-z. The BPG calculations of an ideal case show that POM-σ-z model brings smaller error than POM model does. The simulations of CDW also show that POM-σ-z model is better than POM model on simulating the salinity and its front.
基金Supported by the Sustainable Energy Propulsion System Program of 211’s Engineering Foundation, Shanghai Jiaotong University.
文摘The phase change characteristic of the power source of an underwater glider propelled by the ocean＇s thermal energy is the key factor in glider attitude control. A numerical model has been established based on the enthalpy method to analyze the phase change heat transfer process under convective boundary conditions. Phase change is not an isothermal process, but one that occurs at a range of temperature. The total melting time of the material is very sensitive to the surrounding temperature. When the temperature of the surroundings decreases 8 degrees, the total melting time increases 1.8 times. But variations in surrounding temperature have little effect on the initial temperature of phase change, and the slope of the temperature time history curve remains the same. However, the temperature at which phase change is completed decreases significantly. Our research shows that the phase change process is also affected by container size, boundary conditions, and the power source＇s cross sectional area. Materials stored in 3 cylindrical containers with a diameter of 38ram needed the shortest phase change time. Our conclusions should be helpful in effective design of underwater glider power systems.
基金financially supported by the Project of Ministry of Education and Finance of China(Grant Nos.200512 and 201335)the Project of the State Key Laboratory of Ocean Engineering,Shanghai Jiao Tong University(Grant No.GKZD010053-10)
文摘Knowledge-Based Engineering （KBE） is introduced into the ship structural design in this paper. From the implementation of KBE, the design solutions for both Rules Design Method （RDM） and Interpolation Design Method （IDM） are generated. The corresponding Finite Element （FE） models are generated. Topological design of the longitudinal structures is studied where the Gaussian Process （GP） is employed to build the surrogate model for FE analysis. Multi-objective optimization methods inspired by Pareto Front are used to reduce the design tank weight and outer surface area simultaneously. Additionally, an enhanced Level Set Method （LSM） which employs implicit algorithm is applied to the topological design of typical bracket plate which is used extensively in ship structures. Two different sets of boundary conditions are considered. The proposed methods show satisfactory efficiency and accuracy.
文摘It has been proved that the thermally insulated ocean pipeline has advantages over the conventional pipe-in-pipe pipeline. The risk of using the thermally insulated pipeline is that the exterior layers covering the steel pipe may be. pulled off if the shear stress on the interface induced by the pullout fore from the tensioner is greater than the binding fore between two neighboring layers during installation. This paper develops a procedure to calculate the shear stress on the interface. The binding force between two neighboring layers can be determined with full scale model tests. The safety of the thermally insulated pipe under installation can then be checked by comparison of the interface shear stress with the binding force.
