A suction casting experiment was conducted on Zr_(55)Cu_(30)Al_(10)Ni_(5)(at%)amorphous alloy.Using ProCAST software,numerical simulations were performed to analyze the filling and solidification processes.The velocit...A suction casting experiment was conducted on Zr_(55)Cu_(30)Al_(10)Ni_(5)(at%)amorphous alloy.Using ProCAST software,numerical simulations were performed to analyze the filling and solidification processes.The velocity field during the filling process and the temperature field during the solidification process of the alloy melt under different process parameters were obtained.Based on the simulation results,a Zr-based amorphous alloy micro-gear was prepared via casting.The results indicate that increasing the suction casting temperature enhances the fluidity of alloy melt but induces unstable flow rate during filling,which is detrimental to complete filling.Zr-based amorphous micro-gears with a module of 0.6 mm,a tooth top diameter of 8 mm,and 10 teeth were prepared through the suction casting.X-ray diffraction and differential scanning calorimetry analyses confirm that the fabricated micro-gear exhibits characteristic amorphous structural features,demonstrating well-defined geometrical contours and satisfactory forming completeness.展开更多
Inclusions in nickel-based superalloys significantly influence their mechanical properties which limit the application and development.A two-dimensional axisymmetric model coupling electromagnetic flow,heat transfer,a...Inclusions in nickel-based superalloys significantly influence their mechanical properties which limit the application and development.A two-dimensional axisymmetric model coupling electromagnetic flow,heat transfer,and inclusions transport was developed using the finite element method.The effects of current intensity and frequency on the transport behavior of inclusions and removal rate during vacuum induction melting were investigated using this model.To verify the accuracy of the mathematical model,experiments were conducted using the vacuum induction furnace model VIF200.A comparison of the experimental results with the simulation results reveals an excellent agreement.Four eddies exist in the central section of the molten pool,with any two eddies flowing in opposite directions.The drag force exerted by the eddies causes the inclusions converge toward the four corners of the cut surface.Due to buoyancy,an increase in the particle size of inclusions makes it easier for them to be adsorbed by the free surface,a phenomenon that is particularly noticeable for inclusions with a particle size of 400μm.An increase in current intensity changes the adsorption interface of certain 400-μm inclusions from the free surface to the sidewall.Increasing both current intensity and frequency enhances the crucible removal rate of inclusions,with current intensity exerting a more significant effect,increasing the removal rate by approximately 1% for every 150 A.Upon completion of melting,the ingot is typically obtained by pouring or bottom pouring,and inclusions adsorbed to the free surface are difficult to separate.Therefore,higher current intensity and frequency should be employed during melting to enhance the crucible removal rate.展开更多
The growing complexity of electromagnetic(EM)interference has driven significant demand for next-generation absorbers that combine lightweight,flexibility,and good electromagnetic attenuation capability.The low-dimens...The growing complexity of electromagnetic(EM)interference has driven significant demand for next-generation absorbers that combine lightweight,flexibility,and good electromagnetic attenuation capability.The low-dimensional ternary Co_(3)ZnC/Co/CNT composites with hollow structures have been synthesized through in-situ polymerization and high-temperature carbonization.The unique integration of low-dimensional nanostructures and multicomponent heterointerfaces confers exceptional EM absorption properties,achieving a reflection loss of−70.0 dB and significantly reducing radar cross section(RCS)scattering signals.It is particularly meaningful that the numerical simulation of Co_(3)ZnC/Co/CNT metama-terial reveals ultrawideband absorption performance,achieving 10.7 GHz(7.3-18.0 GHz)at a thickness of 4.5 mm and extending to 15 GHz(3.0-18.0 GHz)with a 10.5 mm.Moreover,the Co_(3)ZnC/Co/CNT composites retain meritorious EM absorption properties after flexible film formation,broadening their usability and application scope.These investigations will provide seminal insights encompassing theoretical validation,experimental synthesis,and practical application for the next generation of absorbers.展开更多
The nozzle is a critical component responsible for generating most of the net thrust in a scramjet engine.The quality of its design directly affects the performance of the entire propulsion system.However,most turbule...The nozzle is a critical component responsible for generating most of the net thrust in a scramjet engine.The quality of its design directly affects the performance of the entire propulsion system.However,most turbulence models struggle to make accurate predictions for subsonic and supersonic flows in nozzles.In this study,we explored a novel model,the algebraic stress model k-kL-ARSM+J,to enhance the accuracy of turbulence numerical simulations.This new model was used to conduct numerical simulations of the design and off-design performance of a 3D supersonic asymmetric truncated nozzle designed in our laboratory,with the aim of providing a realistic pattern of changes.The research indicates that,compared to linear eddy viscosity turbulence models such as k-kL and shear stress transport(SST),the k-kL-ARSM+J algebraic stress model shows better accuracy in predicting the performance of supersonic nozzles.Its predictions were identical to the experimental values,enabling precise calculations of the nozzle.The performance trends of the nozzle are as follows:as the inlet Mach number increases,both thrust and pitching moment increase,but the rate of increase slows down.Lift peaks near the design Mach number and then rapidly decreases.With increasing inlet pressure,the nozzle thrust,lift,and pitching moment all show linear growth.As the flight altitude rises,the internal flow field within the nozzle remains relatively consistent due to the same supersonic nozzle inlet flow conditions.However,external to the nozzle,the change in external flow pressure results in the nozzle exit transitioning from over-expanded to under-expanded,leading to a shear layer behind the nozzle that initially converges towards the nozzle center and then diverges.展开更多
The local time-stepping(LTS)algorithm is an adaptive method that adjusts the time step by selecting suitable intervals for different regions based on the spatial scale of each cell and water depth and flow velocity be...The local time-stepping(LTS)algorithm is an adaptive method that adjusts the time step by selecting suitable intervals for different regions based on the spatial scale of each cell and water depth and flow velocity between cells.The method can be optimized by calculating the maximum power of two of the global time step increments in the domain,allowing the optimal time step to be approached throughout the grid.To verify the acceleration and accuracy of LTS in storm surge simulations,we developed a model to simulate astronomical storm surges along the southern coast of China.This model employs the shallow water equations as governing equations,numerical discretization using the finite volume method,and fluxes calculated by the Roe solver.By comparing the simulation results of the traditional global time-stepping algorithm with those of the LTS algorithm,we find that the latter fit the measured data better.Taking the calculation results of Typhoon Sally in 1996 as an example,we show that compared with the traditional global time-stepping algorithm,the LTS algorithm reduces computation time by 2.05 h and increases computation efficiency by 2.64 times while maintaining good accuracy.展开更多
As the integration of electronic components in high-performance servers increases,heat generation significantly impacts performance and raises failure rates.Therefore,heat dissipation has become a critical concern in ...As the integration of electronic components in high-performance servers increases,heat generation significantly impacts performance and raises failure rates.Therefore,heat dissipation has become a critical concern in electronic circuit design.This study uses numerical simulations to investigate the heat dissipation characteristics of electronic components in air-cooled servers.By adjusting airflow speed,heat sink configurations,and the arrangement of straight-fin heat sinks,we optimize heat dissipation performance and analyze the mechanisms at different airflow speeds.The results show that,at the same airflow speed,the temperature of the heat sink is lower than that of the electronic components,creating a temperature gradient that enhances heat transfer.Compared to a front-to-back arrangement of two straight-fin heat sinks,placing the heat sinks parallel to each other results in a lower maximum component temperature and better temperature uniformity.Heat sinks with fins significantly improve heat dissipation.The heat sink with semicylindrical fins on the rib surface provides the best cooling performance.Moreover,compared to natural convection,the maximum temperature of the electronic components decreases by 56.17%and 61%when the incoming flow velocity is 6 m/s with two parallel flat ribbed heat sinks and front-to-back arrangement,respectively.展开更多
As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-s...As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-sulfur bauxite were simulated using the computational particle fluid dynamics(CPFD) method.The effect of primary air flow velocity on particle velocity,particle volume distribution,furnace temperature distribution and pressure distribution were investigated.Under the condition of the same total flow of natural gas,the impact of the number of inlets on the desulfurization efficiency,atmosphere mass fraction distribution and temperature distribution in the furnace was further investigated.展开更多
Natural gas hydrate widely exists in the South China Sea as clean energy.A three-phase transition layer widely exists in low permeability Class I hydrates in the Shenhu offshore area.Therefore,taking into account the ...Natural gas hydrate widely exists in the South China Sea as clean energy.A three-phase transition layer widely exists in low permeability Class I hydrates in the Shenhu offshore area.Therefore,taking into account the low-permeability characteristics with an average permeability of 5.5 mD and moderate heterogeneity,a 3-D geological model of heterogeneous Class I hydrate reservoirs with three-phase transition layers is established by Kriging interpolation and stochastic modeling method,and a numerical simulation model is used to describe the depressurization production performance of the reservoir.With the development of depressurization,a specific range of complete decomposition zones appear both in the hydrate and transition layers.The entire decomposition zone of the whole reservoir tends to outward and upward diffusion.There is apparent methane escape in the three-phase transition layer.Due to the improvement of local permeability caused by the phase transition of hydrate dissociation,some methane accumulation occurs at the bottom of the hydrate layer,forming a local methane enrichment zone.The methane migration trends in reservoirs are mainly characterized by movement toward production wells and hydrate layers under the influence of gravity.However,due to the permeability limitation of hydrate reservoirs,many fluids have not been effectively produced and remain in the reservoir.Therefore,to improve the effective pressure drop of the reservoir,the perforation method and pressure reduction method were optimized by analyzing the influencing factors based on the gas production rate.The comparative study demonstrates that perforating through the free gas layer combined with one-time depressurization can enhance the effective depressurization and improve production performance.The gas production rate from perforating through the free gas layer can be twice as high as that from perforating through the transition layer.This study can provide theoretical support for the utilization of marine energy.展开更多
The multi-scale modeling combined with the cohesive zone model(CZM)and the molecular dynamics(MD)method were preformed to simulate the crack propagation in NiTi shape memory alloys(SMAs).The metallographic microscope ...The multi-scale modeling combined with the cohesive zone model(CZM)and the molecular dynamics(MD)method were preformed to simulate the crack propagation in NiTi shape memory alloys(SMAs).The metallographic microscope and image processing technology were employed to achieve a quantitative grain size distribution of NiTi alloys so as to provide experimental data for molecular dynamics modeling at the atomic scale.Considering the size effect of molecular dynamics model on material properties,a reasonable modeling size was provided by taking into account three characteristic dimensions from the perspective of macro,meso,and micro scales according to the Buckinghamπtheorem.Then,the corresponding MD simulation on deformation and fracture behavior was investigated to derive a parameterized traction-separation(T-S)law,and then it was embedded into cohesive elements of finite element software.Thus,the crack propagation behavior in NiTi alloys was reproduced by the finite element method(FEM).The experimental results show that the predicted initiation fracture toughness is in good agreement with experimental data.In addition,it is found that the dynamics initiation fracture toughness increases with decreasing grain size and increasing loading velocity.展开更多
The M-shaped multi-row pile foundation retaining structure represents an enhanced version of conventional multi-row anti-sliding support systems.To date,the implementation of M-shaped pile configurations in foundation...The M-shaped multi-row pile foundation retaining structure represents an enhanced version of conventional multi-row anti-sliding support systems.To date,the implementation of M-shaped pile configurations in foundation pit excavations has not been extensively investigated,with particularly scant research focusing on their load-bearing mechanisms and stress redistribution characteristics.Furthermore,numerical modeling methodologies for such geometrically optimized pile networks remain underdeveloped compared to practical engineering applications,creating a notable research-practice gap in geotechnical engineering.A comparative finite element analysis was systematically conducted using ABAQUS software to establish three distinct excavation support configurations:single-row cantilever retaining structures,three-row cantilever configurations,and M-shaped multi-row pile foundation systems.Subsequent numerical simulations enabled quantitative comparisons of critical performance indicators,including pile stress distribution patterns,lateral displacement profiles,and bending moment diagrams across different structural typologies.The parametric investigation revealed characteristic mechanical responses associated with each configuration,establishing corresponding mechanical principles governing the interaction between pile topology and soil-structure behavior towers.The findings of this study provide critical references for the design optimization of M-shaped multi-row pile foundation retaining systems.展开更多
After a long period of water flooding development,the oilfield has entered the middle and high water cut stage.The physical properties of reservoirs are changed by water erosion,which directly impacts reservoir develo...After a long period of water flooding development,the oilfield has entered the middle and high water cut stage.The physical properties of reservoirs are changed by water erosion,which directly impacts reservoir development.Conventional numerical reservoir simulation methodologies typically employ static assumptions for model construction,presuming invariant reservoir geological parameters throughout the development process while neglecting the reservoir’s temporal evolution characteristics.Although such simplifications reduce computational complexity,they introduce substantial descriptive inaccuracies.Therefore,this paper proposes a meshless numerical simulation method for reservoirs that considers time-varying characteristics.This method avoids the meshing in traditional numerical simulation methods.From the fluid flow perspective,the reservoir’s computational domain is discretized into a series of connection units.An influence domain with a certain radius centered on the nodes is selected,and one-dimensional connection units are established between the nodes to achieve the characterization of the flow topology structure of the reservoir.In order to reflect the dynamic evolution of the reservoir’s physical properties during the water injection development process,the time-varying characteristics are incorporated into the formula of the seepage characteristic parameters in the meshless calculation.The change relationship of the permeability under different surface fluxes is considered to update the calculated connection conductivity in real time.By combining with the seepage control equation for solution,a time-varying meshless numerical simulation method is formed.The results show that compared with the numerical simulationmethod of the connection elementmethod(CEM)that only considers static parameters,this method has higher simulation accuracy and can better simulate the real migration and distribution of oil and water in the reservoir.Thismethod improves the accuracy of reservoir numerical simulation and the development effect of oilfields,providing a scientific basis for optimizing the water injection strategy,adjusting the production plan,and extending the effective production cycle of the oilfield.展开更多
As a renewable energy source,the thermal conversion of poultry manure,is a promising waste treatment solution that can generate circular economic outputs such as energy and reduce greenhouse gas emissions.Currently,pr...As a renewable energy source,the thermal conversion of poultry manure,is a promising waste treatment solution that can generate circular economic outputs such as energy and reduce greenhouse gas emissions.Currently,pressurized gasification of poultry manure is still a novel research field,especially when combined with a novel technological route of oxy-fuel gasification.Oxy-fuel gasification is a newly proposed and promising gasification technology for power generation that facilitates future carbon capture and storage.In this work,based on a commercially operated industrial-scale chicken manure gasification power plant in Singapore,we presented an interesting first exploration of the coupled pressurization technology for oxy-fuel gasification of poultry manure using CFD numerical simulation,analyzed the effects of pressure and oxygen enrichment concentration as well as the coupling mechanism between them,and discussed the conversion and emission of nitrogen-and sulfur-containing pollutants.The results indicate that under oxy-fuel gasification condition(Oxy-30,i.e.,30%O_(2)/70%CO_(2)),as the pressure increases from 0.1 to 0.5 MPa,the CO concentration in the syngas increases slightly,the H_(2)concentration increases to approximately 25%,and the CH4 concentration(less than 1%)decreases,resulting in an increase in the calorific value of syngas from 5.2 to 5.6 MJ·m^(-3).Compared to atmospheric pressure conditions,a relatively higher oxygen-enriched concentration interval(Oxy-40 to Oxy-50)under pressurized conditions is advantageous for autothermal gasification.Pressurization increases NO precursors production and also promotes homogeneous and heterogeneous reduction of NO,and provides favorable conditions for self-desulfurization.This work offers reference for the realization of a highly efficient and low-energy-consumption thermochemical treatment of livestock manure coupled with negative carbon emission technology.展开更多
Smelting with oxygen bottom blowing is one of the main methods used in the frame of copper pyrometallurgy.With this approach,feed materials and oxygen-enriched air are introduced in reversed order to enhance multiphas...Smelting with oxygen bottom blowing is one of the main methods used in the frame of copper pyrometallurgy.With this approach,feed materials and oxygen-enriched air are introduced in reversed order to enhance multiphaseflow within the furnace.Understanding the flow structure and temperature distribution in this setup is crucial foroptimizing production.In this study,gas-liquid interactions,and temperature profiles under varying air-injectionconditions are examined by means of numerical simulation for a 3.2 m×20 m furnace.The results indicate that thehigh-velocity regions are essentially distributed near the lance within the reaction region and the flue gas outlet,while low-velocity regions are located close to the furnace walls on both side of the reaction region.Dead regionsappear in the sedimentation region,with gas velocities surpassing those of the molten phase.As the injection rateincreases from 0.50 to 0.80 Nm3/s,the stabilization time of the average liquid surface velocity decreases from 2.6 sto 1.9 s,exhibiting a similar trend to the gas holdup.During stabilization,the average liquid surface velocity risesfrom 0.505 to 0.702 m/s.The average turbulent kinetic energy(TKE)of the fluid in the molten bath increases from0.095 to 0.162 m^(2)/s^(2).The proportion of the area distribution with TKE greater than 0.10 m^(2)/s^(2) and the gas holdupat steady state both rise with an increase in the injection quantity.The maximum splashing height of the melt growsfrom approximately 0.756 to 1.154 m,with the affected area expanding from 14.239 to 20.498 m^(2).Under differentworking conditions with varying injection quantities,the average temperature changes in melt zone and flue gaszone of the furnace are small.The temperature in the melt and in the flue-gas zone spans the interval 1200℃–1257℃,and 1073℃–1121℃,respectively.The temperature distribution of the melt and flue gas reveals a patterncharacterized by elevated temperatures in the reaction zone,gradually transitioning to lower temperatures in thesedimentation region.展开更多
To mitigate the sand burial of highways in sandy regions,a separated subgrade design was widely adopted in the embankments of high-grade highways,but the problem of sand deposition on subgrade slopes and pavements sti...To mitigate the sand burial of highways in sandy regions,a separated subgrade design was widely adopted in the embankments of high-grade highways,but the problem of sand deposition on subgrade slopes and pavements still happens frequently.Based on the theory of wind-sand two-phase flow,this paper constructed a three-dimensional model of the separated subgrade,the wind-sand flow transport law around the subgrade with varying median strip widths and concave depths was simulated by Fluent software.After comparison and analysis of seven subgrade models,the flow field distribution,wind speed horizontal variation,and erosion-deposition characteristics were investigated.The findings are as follows:(1)The width of the median strip in the separated subgrade had significant influences on the wind-sand flow.The smooth passage of wind-sand flow over the road surface was facilitated with the increase of the median strip width.However,sand deposition in the median strip happened.It can lead to secondary sand damage of downwind subgrade and increase the work load of road sand removal for subsequent maintenance.(2)The obstruction to airflow and sand accumulation was aggravated with greater concave depth of the median strip.Therefore,it is advisable to minimize the concave depth of the median strip in case of more sand damage.(3)A median strip width exceeding 12 m(possibly without guardrails)for an integral embankment without enough road land is recommended.Conversely,median strip width of over 40 m for separate subgrade with unrestricted land is suggested.(4)In the case of sand deposition in the existing separated subgrade,the median strip can be filled by sand deposition or other materials,then was covered with gravel to form a flat ground like Gobi smooth surface,which can let the wind-blown sand flow pass through the subgrade section without sand deposition.展开更多
Shale gas production involves complex gas-water two-phase flow,with flow patterns in proppant-filled fractures playing a critical role in determining production efficiency.In this study,3D geometric models of 40/70 me...Shale gas production involves complex gas-water two-phase flow,with flow patterns in proppant-filled fractures playing a critical role in determining production efficiency.In this study,3D geometric models of 40/70 mesh ceramic particles and quartz sand proppant clusters were elaborated using computed tomography(CT)scanning.These models were used to develop a numerical simulation framework based on the lattice Boltzmann method(LBM),enabling the investigation of gas-water flow behavior within proppant-filled fractures under varying driving forces and surface tensions.Simulation results at a closure pressure of 15 MPa have revealed that ceramic particles exhibit a simpler and more porous internal structure than quartz sand of the same size.Under identical flow conditions,ceramic proppants demonstrate higher fluid replacement efficiency.Replacement efficiency increases with higher porosity,greater driving force,and lower surface tension.Furthermore,fluid displacement is strongly influenced by pore geometry:flow is faster in straighter and wider channels,with preferential movement through larger pores forming dominant flow paths.The replacement velocity exhibits a characteristic time evolution,initially rapid,then gradually decreasing,correlating positively with the development of these dominant channels.展开更多
Deepwater drilling riser is the key equipment connecting the subsea wellhead and floating drilling platform.Due to complex marine environment,vortex-induced vibration(ViV)will be generated on riser,which will induce f...Deepwater drilling riser is the key equipment connecting the subsea wellhead and floating drilling platform.Due to complex marine environment,vortex-induced vibration(ViV)will be generated on riser,which will induce fatigue failure and even cause unpredictable drilling accidents.Therefore,it is important to study the ViV characteristics of deepwater drilling riser and reveal the main controlling factors for ensuring the safe and efficient operation of deepwater drilling engineering.In this paper,the ViV of deepwater drilling riser is numerically simulated in time domain based on the discrete vortex method(DvM).A hydrodynamic analysis model and governing equation of VIV is proposed with considering the effect of riser motion using DVM and slice method,where the governing equation is solved by Runge-Kutta method.Model validation is performed,which verified the correctness and accuracy of the mechanical model and the solution method.On this basis,the influence of the number of control points,current velocity,riser outer diameter,shear flow and top tension on the ViV characteristics of deepwater drilling risers are discussed in detail.The results show that with the increase of current velocity,the vibration amplitude of deepwater drilling riser decreases obviously,while the vibration frequency increases gradually.However,if the outer diameter of riser increases,the vibration amplitude increases,while the vibration frequency decreases gradually.The top tension also has great influence on the VIV of riser.When the top tension is 1.25 G,the VIV is suppressed to a certain extent.This study has guiding significance for optimal design and engineering control of deepwater drilling riser.展开更多
Oilfields worldwide are increasingly grappling with challenges such as early water breakthrough and high water production,yet direct,targeted solutions remain elusive.In recent years,chemical flooding techniques desig...Oilfields worldwide are increasingly grappling with challenges such as early water breakthrough and high water production,yet direct,targeted solutions remain elusive.In recent years,chemical flooding techniques designed for tertiary oil recovery have garnered significant attention,with microgel flooding emerging as a particularly prominent area of research.Despite its promise,the complex mechanisms underlying microgel flooding have been rarely investigated numerically.This study aims to address these gaps by characterizing the distribution of microgel concentration and viscosity within different pore structures.To enhance the accuracy of these characterizations,the viscosity of microgels is adjusted to account for the shear effects induced by flow rate and the swelling effects driven by salinity variations.The absolute permeability of the rock and the relative permeability of both oil and microgel are also analyzed to elucidate the mechanisms of microgel flooding.Additionally,a connectivity model is employed to achieve a quantitative representation of fluid flow capacity.The proposed model is validated through conceptual examples and applied to real oilfield blocks,demonstrating its accuracy and practical applicability.展开更多
To improve the photovoltaic conversion efficiency(PCE)of silicon heterojunction(SHJ)solar cells,this study focuses on optimizing the physical parameters of the sun-side-doped layer and proposes strategies to address t...To improve the photovoltaic conversion efficiency(PCE)of silicon heterojunction(SHJ)solar cells,this study focuses on optimizing the physical parameters of the sun-side-doped layer and proposes strategies to address the challenges posed by Fermi level pinning in wide bandgap designs.Using AFORS-HET simulations,we systematically investigate the effects of bandgap width,doping concentration,and defect state distribution on the energy band structure,interface electric field,and carrier transport dynamics.The results reveal that maintaining the Fermi level within 0.3 eV of the conduction band is essential for optimal device performance.A wider bandgap(>1.8 eV)enhances the utilization of short-wavelength light and significantly suppresses interface recombination,leading to an increase in short-circuit current density(J_(sc))by 0.8 mA/cm^(2).This benefit comes with a delicate balance between minimizing defect state density and improving doping efficiency.This study provides theoretical insights into the optimization of doped layer physical parameters and proposes practical solutions,including nano-crystallization and low-doping interface strategies,to improve the performance of SHJ solar cells and support industrial applications.展开更多
0 INTRODUCTION In recent years,modern railways have been actively under construction in the complex mountainous area of Southwest China.However,rockfall poses a significant threat to both construction and operation ph...0 INTRODUCTION In recent years,modern railways have been actively under construction in the complex mountainous area of Southwest China.However,rockfall poses a significant threat to both construction and operation phases of railway projects(Yan et al.,2023;Chen et al.,2022;Fanos and Pradhan,2018).展开更多
Strong low-frequency energy beneath a hydrocarbon reservoir is called a seismic low-frequency shadow and can be used as a hydrocarbon indicator （Tarter et al., 1979） bu the physical mechanism of the observed low-fre...Strong low-frequency energy beneath a hydrocarbon reservoir is called a seismic low-frequency shadow and can be used as a hydrocarbon indicator （Tarter et al., 1979） bu the physical mechanism of the observed low-frequency shadow is still unclear. To stud） the mechanism, we performed seismic numerical simulation of geological models with a hydrocarbon-bearing zone using the 2-D diffusive-viscous wave equation which car effectively model the characteristics of velocity dispersion and transform the seismic dat~ centered in a target layer slice within a time window to the time-frequency domain by usinl time-frequency signal analysis and sort the frequency gathers to common frequency cubes. Then, we observe the characteristics of the seismic low-frequency shadow in the common frequency cubes. The numerical simulations reveal that the main mechanism of seismic lowfrequency shadows is attributed to high attenuation of the medium to high seismic frequency components caused by absorption in the hydrocarbon-filled reservoir. Results from a practical example of seismic low-frequency shadows show that it is possible to identify the reservoir by the low-frequency shadow with high S/N seismic data.展开更多
基金National Natural Science Foundation of China(51971103)Key Research and Development Program in Gansu Province(20YF8GA052)。
文摘A suction casting experiment was conducted on Zr_(55)Cu_(30)Al_(10)Ni_(5)(at%)amorphous alloy.Using ProCAST software,numerical simulations were performed to analyze the filling and solidification processes.The velocity field during the filling process and the temperature field during the solidification process of the alloy melt under different process parameters were obtained.Based on the simulation results,a Zr-based amorphous alloy micro-gear was prepared via casting.The results indicate that increasing the suction casting temperature enhances the fluidity of alloy melt but induces unstable flow rate during filling,which is detrimental to complete filling.Zr-based amorphous micro-gears with a module of 0.6 mm,a tooth top diameter of 8 mm,and 10 teeth were prepared through the suction casting.X-ray diffraction and differential scanning calorimetry analyses confirm that the fabricated micro-gear exhibits characteristic amorphous structural features,demonstrating well-defined geometrical contours and satisfactory forming completeness.
基金financially supported by the National Natural Science Foundation of China(Nos.52422408 and 52171031)Excellent Youth Fund of Liaoning Natural Science Foundation(No.2023JH3/10200001)Liaoning Xingliao Talents-Top-notch Young Talents Project(No.XLYC2203064).
文摘Inclusions in nickel-based superalloys significantly influence their mechanical properties which limit the application and development.A two-dimensional axisymmetric model coupling electromagnetic flow,heat transfer,and inclusions transport was developed using the finite element method.The effects of current intensity and frequency on the transport behavior of inclusions and removal rate during vacuum induction melting were investigated using this model.To verify the accuracy of the mathematical model,experiments were conducted using the vacuum induction furnace model VIF200.A comparison of the experimental results with the simulation results reveals an excellent agreement.Four eddies exist in the central section of the molten pool,with any two eddies flowing in opposite directions.The drag force exerted by the eddies causes the inclusions converge toward the four corners of the cut surface.Due to buoyancy,an increase in the particle size of inclusions makes it easier for them to be adsorbed by the free surface,a phenomenon that is particularly noticeable for inclusions with a particle size of 400μm.An increase in current intensity changes the adsorption interface of certain 400-μm inclusions from the free surface to the sidewall.Increasing both current intensity and frequency enhances the crucible removal rate of inclusions,with current intensity exerting a more significant effect,increasing the removal rate by approximately 1% for every 150 A.Upon completion of melting,the ingot is typically obtained by pouring or bottom pouring,and inclusions adsorbed to the free surface are difficult to separate.Therefore,higher current intensity and frequency should be employed during melting to enhance the crucible removal rate.
基金supported by the National University of Defense Technology Independent Innovation Science Fund(Nos.24-ZZCXJDZ-42 and XJJC2024088)Hefei Municipal Natural Science Foundation(No.K130936103)The authors extend their gratitude to Ms.Zhang from Scientific Compass(www.shiyanjia.com)for providing invaluable assistance.
文摘The growing complexity of electromagnetic(EM)interference has driven significant demand for next-generation absorbers that combine lightweight,flexibility,and good electromagnetic attenuation capability.The low-dimensional ternary Co_(3)ZnC/Co/CNT composites with hollow structures have been synthesized through in-situ polymerization and high-temperature carbonization.The unique integration of low-dimensional nanostructures and multicomponent heterointerfaces confers exceptional EM absorption properties,achieving a reflection loss of−70.0 dB and significantly reducing radar cross section(RCS)scattering signals.It is particularly meaningful that the numerical simulation of Co_(3)ZnC/Co/CNT metama-terial reveals ultrawideband absorption performance,achieving 10.7 GHz(7.3-18.0 GHz)at a thickness of 4.5 mm and extending to 15 GHz(3.0-18.0 GHz)with a 10.5 mm.Moreover,the Co_(3)ZnC/Co/CNT composites retain meritorious EM absorption properties after flexible film formation,broadening their usability and application scope.These investigations will provide seminal insights encompassing theoretical validation,experimental synthesis,and practical application for the next generation of absorbers.
基金supported by the Zhejiang Provincial Key Research and Development Program of China(No.2020C01020).
文摘The nozzle is a critical component responsible for generating most of the net thrust in a scramjet engine.The quality of its design directly affects the performance of the entire propulsion system.However,most turbulence models struggle to make accurate predictions for subsonic and supersonic flows in nozzles.In this study,we explored a novel model,the algebraic stress model k-kL-ARSM+J,to enhance the accuracy of turbulence numerical simulations.This new model was used to conduct numerical simulations of the design and off-design performance of a 3D supersonic asymmetric truncated nozzle designed in our laboratory,with the aim of providing a realistic pattern of changes.The research indicates that,compared to linear eddy viscosity turbulence models such as k-kL and shear stress transport(SST),the k-kL-ARSM+J algebraic stress model shows better accuracy in predicting the performance of supersonic nozzles.Its predictions were identical to the experimental values,enabling precise calculations of the nozzle.The performance trends of the nozzle are as follows:as the inlet Mach number increases,both thrust and pitching moment increase,but the rate of increase slows down.Lift peaks near the design Mach number and then rapidly decreases.With increasing inlet pressure,the nozzle thrust,lift,and pitching moment all show linear growth.As the flight altitude rises,the internal flow field within the nozzle remains relatively consistent due to the same supersonic nozzle inlet flow conditions.However,external to the nozzle,the change in external flow pressure results in the nozzle exit transitioning from over-expanded to under-expanded,leading to a shear layer behind the nozzle that initially converges towards the nozzle center and then diverges.
基金National Natural Science Foundation of China(No.52071306)the Natural Science Foundation of Shandong Province(No.ZR2019MEE050)the Natural Science Foundation of Zhejiang Province(No.LZ22E090003).
文摘The local time-stepping(LTS)algorithm is an adaptive method that adjusts the time step by selecting suitable intervals for different regions based on the spatial scale of each cell and water depth and flow velocity between cells.The method can be optimized by calculating the maximum power of two of the global time step increments in the domain,allowing the optimal time step to be approached throughout the grid.To verify the acceleration and accuracy of LTS in storm surge simulations,we developed a model to simulate astronomical storm surges along the southern coast of China.This model employs the shallow water equations as governing equations,numerical discretization using the finite volume method,and fluxes calculated by the Roe solver.By comparing the simulation results of the traditional global time-stepping algorithm with those of the LTS algorithm,we find that the latter fit the measured data better.Taking the calculation results of Typhoon Sally in 1996 as an example,we show that compared with the traditional global time-stepping algorithm,the LTS algorithm reduces computation time by 2.05 h and increases computation efficiency by 2.64 times while maintaining good accuracy.
基金supported by the key technology project of China Southern Power Grid Corporation(GZKJXM20240009).
文摘As the integration of electronic components in high-performance servers increases,heat generation significantly impacts performance and raises failure rates.Therefore,heat dissipation has become a critical concern in electronic circuit design.This study uses numerical simulations to investigate the heat dissipation characteristics of electronic components in air-cooled servers.By adjusting airflow speed,heat sink configurations,and the arrangement of straight-fin heat sinks,we optimize heat dissipation performance and analyze the mechanisms at different airflow speeds.The results show that,at the same airflow speed,the temperature of the heat sink is lower than that of the electronic components,creating a temperature gradient that enhances heat transfer.Compared to a front-to-back arrangement of two straight-fin heat sinks,placing the heat sinks parallel to each other results in a lower maximum component temperature and better temperature uniformity.Heat sinks with fins significantly improve heat dissipation.The heat sink with semicylindrical fins on the rib surface provides the best cooling performance.Moreover,compared to natural convection,the maximum temperature of the electronic components decreases by 56.17%and 61%when the incoming flow velocity is 6 m/s with two parallel flat ribbed heat sinks and front-to-back arrangement,respectively.
基金supported by the National Key Research and Development Program of China(2022YFC2904400)Guangxi Science and Technology Major Project(Gui Ke AA23023033)。
文摘As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-sulfur bauxite were simulated using the computational particle fluid dynamics(CPFD) method.The effect of primary air flow velocity on particle velocity,particle volume distribution,furnace temperature distribution and pressure distribution were investigated.Under the condition of the same total flow of natural gas,the impact of the number of inlets on the desulfurization efficiency,atmosphere mass fraction distribution and temperature distribution in the furnace was further investigated.
基金supported by the Sinopec Technology Research and Development Project(No.30000000-22-ZC0607-0235,No.33550000-22-ZC0607-0009)the National Natural Science Foundation of China(No.52334002).
文摘Natural gas hydrate widely exists in the South China Sea as clean energy.A three-phase transition layer widely exists in low permeability Class I hydrates in the Shenhu offshore area.Therefore,taking into account the low-permeability characteristics with an average permeability of 5.5 mD and moderate heterogeneity,a 3-D geological model of heterogeneous Class I hydrate reservoirs with three-phase transition layers is established by Kriging interpolation and stochastic modeling method,and a numerical simulation model is used to describe the depressurization production performance of the reservoir.With the development of depressurization,a specific range of complete decomposition zones appear both in the hydrate and transition layers.The entire decomposition zone of the whole reservoir tends to outward and upward diffusion.There is apparent methane escape in the three-phase transition layer.Due to the improvement of local permeability caused by the phase transition of hydrate dissociation,some methane accumulation occurs at the bottom of the hydrate layer,forming a local methane enrichment zone.The methane migration trends in reservoirs are mainly characterized by movement toward production wells and hydrate layers under the influence of gravity.However,due to the permeability limitation of hydrate reservoirs,many fluids have not been effectively produced and remain in the reservoir.Therefore,to improve the effective pressure drop of the reservoir,the perforation method and pressure reduction method were optimized by analyzing the influencing factors based on the gas production rate.The comparative study demonstrates that perforating through the free gas layer combined with one-time depressurization can enhance the effective depressurization and improve production performance.The gas production rate from perforating through the free gas layer can be twice as high as that from perforating through the transition layer.This study can provide theoretical support for the utilization of marine energy.
基金Funded by the National Natural Science Foundation of China Academy of Engineering Physics and Jointly Setup"NSAF"Joint Fund(No.U1430119)。
文摘The multi-scale modeling combined with the cohesive zone model(CZM)and the molecular dynamics(MD)method were preformed to simulate the crack propagation in NiTi shape memory alloys(SMAs).The metallographic microscope and image processing technology were employed to achieve a quantitative grain size distribution of NiTi alloys so as to provide experimental data for molecular dynamics modeling at the atomic scale.Considering the size effect of molecular dynamics model on material properties,a reasonable modeling size was provided by taking into account three characteristic dimensions from the perspective of macro,meso,and micro scales according to the Buckinghamπtheorem.Then,the corresponding MD simulation on deformation and fracture behavior was investigated to derive a parameterized traction-separation(T-S)law,and then it was embedded into cohesive elements of finite element software.Thus,the crack propagation behavior in NiTi alloys was reproduced by the finite element method(FEM).The experimental results show that the predicted initiation fracture toughness is in good agreement with experimental data.In addition,it is found that the dynamics initiation fracture toughness increases with decreasing grain size and increasing loading velocity.
文摘The M-shaped multi-row pile foundation retaining structure represents an enhanced version of conventional multi-row anti-sliding support systems.To date,the implementation of M-shaped pile configurations in foundation pit excavations has not been extensively investigated,with particularly scant research focusing on their load-bearing mechanisms and stress redistribution characteristics.Furthermore,numerical modeling methodologies for such geometrically optimized pile networks remain underdeveloped compared to practical engineering applications,creating a notable research-practice gap in geotechnical engineering.A comparative finite element analysis was systematically conducted using ABAQUS software to establish three distinct excavation support configurations:single-row cantilever retaining structures,three-row cantilever configurations,and M-shaped multi-row pile foundation systems.Subsequent numerical simulations enabled quantitative comparisons of critical performance indicators,including pile stress distribution patterns,lateral displacement profiles,and bending moment diagrams across different structural typologies.The parametric investigation revealed characteristic mechanical responses associated with each configuration,establishing corresponding mechanical principles governing the interaction between pile topology and soil-structure behavior towers.The findings of this study provide critical references for the design optimization of M-shaped multi-row pile foundation retaining systems.
基金funded by the 14th Five-Year Plan Major Science and Technology Project of CNOOC project number KJGG2021-0506.
文摘After a long period of water flooding development,the oilfield has entered the middle and high water cut stage.The physical properties of reservoirs are changed by water erosion,which directly impacts reservoir development.Conventional numerical reservoir simulation methodologies typically employ static assumptions for model construction,presuming invariant reservoir geological parameters throughout the development process while neglecting the reservoir’s temporal evolution characteristics.Although such simplifications reduce computational complexity,they introduce substantial descriptive inaccuracies.Therefore,this paper proposes a meshless numerical simulation method for reservoirs that considers time-varying characteristics.This method avoids the meshing in traditional numerical simulation methods.From the fluid flow perspective,the reservoir’s computational domain is discretized into a series of connection units.An influence domain with a certain radius centered on the nodes is selected,and one-dimensional connection units are established between the nodes to achieve the characterization of the flow topology structure of the reservoir.In order to reflect the dynamic evolution of the reservoir’s physical properties during the water injection development process,the time-varying characteristics are incorporated into the formula of the seepage characteristic parameters in the meshless calculation.The change relationship of the permeability under different surface fluxes is considered to update the calculated connection conductivity in real time.By combining with the seepage control equation for solution,a time-varying meshless numerical simulation method is formed.The results show that compared with the numerical simulationmethod of the connection elementmethod(CEM)that only considers static parameters,this method has higher simulation accuracy and can better simulate the real migration and distribution of oil and water in the reservoir.Thismethod improves the accuracy of reservoir numerical simulation and the development effect of oilfields,providing a scientific basis for optimizing the water injection strategy,adjusting the production plan,and extending the effective production cycle of the oilfield.
基金supported by the National Natural Science Foundation of China(52306131)the Natural Science Foundation of Jiangsu Province(BK20230847)+2 种基金the Key Project of the National Natural Science Foundation of China(52336005)the Fundamental Research Funds for the Central Universities(2242024RCB0036)the Open Project Program of State Key Laboratory of Low-carbon Smart Coal-fired Power Generation and Ultra-clean Emission(D2024FK156).
文摘As a renewable energy source,the thermal conversion of poultry manure,is a promising waste treatment solution that can generate circular economic outputs such as energy and reduce greenhouse gas emissions.Currently,pressurized gasification of poultry manure is still a novel research field,especially when combined with a novel technological route of oxy-fuel gasification.Oxy-fuel gasification is a newly proposed and promising gasification technology for power generation that facilitates future carbon capture and storage.In this work,based on a commercially operated industrial-scale chicken manure gasification power plant in Singapore,we presented an interesting first exploration of the coupled pressurization technology for oxy-fuel gasification of poultry manure using CFD numerical simulation,analyzed the effects of pressure and oxygen enrichment concentration as well as the coupling mechanism between them,and discussed the conversion and emission of nitrogen-and sulfur-containing pollutants.The results indicate that under oxy-fuel gasification condition(Oxy-30,i.e.,30%O_(2)/70%CO_(2)),as the pressure increases from 0.1 to 0.5 MPa,the CO concentration in the syngas increases slightly,the H_(2)concentration increases to approximately 25%,and the CH4 concentration(less than 1%)decreases,resulting in an increase in the calorific value of syngas from 5.2 to 5.6 MJ·m^(-3).Compared to atmospheric pressure conditions,a relatively higher oxygen-enriched concentration interval(Oxy-40 to Oxy-50)under pressurized conditions is advantageous for autothermal gasification.Pressurization increases NO precursors production and also promotes homogeneous and heterogeneous reduction of NO,and provides favorable conditions for self-desulfurization.This work offers reference for the realization of a highly efficient and low-energy-consumption thermochemical treatment of livestock manure coupled with negative carbon emission technology.
基金Supported by Yunnan Fundamental Research Projects(Nos.202301AT070469,202301AT070275)Supported by Yunnan Major Scientific and Technological Projects(No.202202AG050002).
文摘Smelting with oxygen bottom blowing is one of the main methods used in the frame of copper pyrometallurgy.With this approach,feed materials and oxygen-enriched air are introduced in reversed order to enhance multiphaseflow within the furnace.Understanding the flow structure and temperature distribution in this setup is crucial foroptimizing production.In this study,gas-liquid interactions,and temperature profiles under varying air-injectionconditions are examined by means of numerical simulation for a 3.2 m×20 m furnace.The results indicate that thehigh-velocity regions are essentially distributed near the lance within the reaction region and the flue gas outlet,while low-velocity regions are located close to the furnace walls on both side of the reaction region.Dead regionsappear in the sedimentation region,with gas velocities surpassing those of the molten phase.As the injection rateincreases from 0.50 to 0.80 Nm3/s,the stabilization time of the average liquid surface velocity decreases from 2.6 sto 1.9 s,exhibiting a similar trend to the gas holdup.During stabilization,the average liquid surface velocity risesfrom 0.505 to 0.702 m/s.The average turbulent kinetic energy(TKE)of the fluid in the molten bath increases from0.095 to 0.162 m^(2)/s^(2).The proportion of the area distribution with TKE greater than 0.10 m^(2)/s^(2) and the gas holdupat steady state both rise with an increase in the injection quantity.The maximum splashing height of the melt growsfrom approximately 0.756 to 1.154 m,with the affected area expanding from 14.239 to 20.498 m^(2).Under differentworking conditions with varying injection quantities,the average temperature changes in melt zone and flue gaszone of the furnace are small.The temperature in the melt and in the flue-gas zone spans the interval 1200℃–1257℃,and 1073℃–1121℃,respectively.The temperature distribution of the melt and flue gas reveals a patterncharacterized by elevated temperatures in the reaction zone,gradually transitioning to lower temperatures in thesedimentation region.
基金supported by the Third Xinjiang Scientific Expedition and Research Program-Investigation and Risk Assessment of Drought and Aeolian Disasters in Tarim River Basin(No.2021xjkk0300)the National Natural Science Foundation of China(No.62466056)the subject of'the technical scheme and application demonstration of sand disaster prevention and control of Xinjiang expressway to engineering practice,Xinjiang Transportation Investment(Group)Co.,Ltd.(No.XJJTZKX-FWCG-202401-0043).
文摘To mitigate the sand burial of highways in sandy regions,a separated subgrade design was widely adopted in the embankments of high-grade highways,but the problem of sand deposition on subgrade slopes and pavements still happens frequently.Based on the theory of wind-sand two-phase flow,this paper constructed a three-dimensional model of the separated subgrade,the wind-sand flow transport law around the subgrade with varying median strip widths and concave depths was simulated by Fluent software.After comparison and analysis of seven subgrade models,the flow field distribution,wind speed horizontal variation,and erosion-deposition characteristics were investigated.The findings are as follows:(1)The width of the median strip in the separated subgrade had significant influences on the wind-sand flow.The smooth passage of wind-sand flow over the road surface was facilitated with the increase of the median strip width.However,sand deposition in the median strip happened.It can lead to secondary sand damage of downwind subgrade and increase the work load of road sand removal for subsequent maintenance.(2)The obstruction to airflow and sand accumulation was aggravated with greater concave depth of the median strip.Therefore,it is advisable to minimize the concave depth of the median strip in case of more sand damage.(3)A median strip width exceeding 12 m(possibly without guardrails)for an integral embankment without enough road land is recommended.Conversely,median strip width of over 40 m for separate subgrade with unrestricted land is suggested.(4)In the case of sand deposition in the existing separated subgrade,the median strip can be filled by sand deposition or other materials,then was covered with gravel to form a flat ground like Gobi smooth surface,which can let the wind-blown sand flow pass through the subgrade section without sand deposition.
文摘Shale gas production involves complex gas-water two-phase flow,with flow patterns in proppant-filled fractures playing a critical role in determining production efficiency.In this study,3D geometric models of 40/70 mesh ceramic particles and quartz sand proppant clusters were elaborated using computed tomography(CT)scanning.These models were used to develop a numerical simulation framework based on the lattice Boltzmann method(LBM),enabling the investigation of gas-water flow behavior within proppant-filled fractures under varying driving forces and surface tensions.Simulation results at a closure pressure of 15 MPa have revealed that ceramic particles exhibit a simpler and more porous internal structure than quartz sand of the same size.Under identical flow conditions,ceramic proppants demonstrate higher fluid replacement efficiency.Replacement efficiency increases with higher porosity,greater driving force,and lower surface tension.Furthermore,fluid displacement is strongly influenced by pore geometry:flow is faster in straighter and wider channels,with preferential movement through larger pores forming dominant flow paths.The replacement velocity exhibits a characteristic time evolution,initially rapid,then gradually decreasing,correlating positively with the development of these dominant channels.
基金the financial support from National Key R&D Program of China(Grant number:2024YFC2815100)Natural Science Foundation of China(Grant number:52322110)Beijing Nova Program(Grant number:20230484341).
文摘Deepwater drilling riser is the key equipment connecting the subsea wellhead and floating drilling platform.Due to complex marine environment,vortex-induced vibration(ViV)will be generated on riser,which will induce fatigue failure and even cause unpredictable drilling accidents.Therefore,it is important to study the ViV characteristics of deepwater drilling riser and reveal the main controlling factors for ensuring the safe and efficient operation of deepwater drilling engineering.In this paper,the ViV of deepwater drilling riser is numerically simulated in time domain based on the discrete vortex method(DvM).A hydrodynamic analysis model and governing equation of VIV is proposed with considering the effect of riser motion using DVM and slice method,where the governing equation is solved by Runge-Kutta method.Model validation is performed,which verified the correctness and accuracy of the mechanical model and the solution method.On this basis,the influence of the number of control points,current velocity,riser outer diameter,shear flow and top tension on the ViV characteristics of deepwater drilling risers are discussed in detail.The results show that with the increase of current velocity,the vibration amplitude of deepwater drilling riser decreases obviously,while the vibration frequency increases gradually.However,if the outer diameter of riser increases,the vibration amplitude increases,while the vibration frequency decreases gradually.The top tension also has great influence on the VIV of riser.When the top tension is 1.25 G,the VIV is suppressed to a certain extent.This study has guiding significance for optimal design and engineering control of deepwater drilling riser.
基金supported by the National Natural Science Foundation project“Micro-Scale Effect of Oil-Gas Flow and the Mechanism of Enhancing Shale Oil Recovery by Natural Gas Injection”(No.52074317)。
文摘Oilfields worldwide are increasingly grappling with challenges such as early water breakthrough and high water production,yet direct,targeted solutions remain elusive.In recent years,chemical flooding techniques designed for tertiary oil recovery have garnered significant attention,with microgel flooding emerging as a particularly prominent area of research.Despite its promise,the complex mechanisms underlying microgel flooding have been rarely investigated numerically.This study aims to address these gaps by characterizing the distribution of microgel concentration and viscosity within different pore structures.To enhance the accuracy of these characterizations,the viscosity of microgels is adjusted to account for the shear effects induced by flow rate and the swelling effects driven by salinity variations.The absolute permeability of the rock and the relative permeability of both oil and microgel are also analyzed to elucidate the mechanisms of microgel flooding.Additionally,a connectivity model is employed to achieve a quantitative representation of fluid flow capacity.The proposed model is validated through conceptual examples and applied to real oilfield blocks,demonstrating its accuracy and practical applicability.
基金supported by the National Natural Science Foundation of China(Grant Nos.61991441 and 62004218)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB01000000)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2021005).
文摘To improve the photovoltaic conversion efficiency(PCE)of silicon heterojunction(SHJ)solar cells,this study focuses on optimizing the physical parameters of the sun-side-doped layer and proposes strategies to address the challenges posed by Fermi level pinning in wide bandgap designs.Using AFORS-HET simulations,we systematically investigate the effects of bandgap width,doping concentration,and defect state distribution on the energy band structure,interface electric field,and carrier transport dynamics.The results reveal that maintaining the Fermi level within 0.3 eV of the conduction band is essential for optimal device performance.A wider bandgap(>1.8 eV)enhances the utilization of short-wavelength light and significantly suppresses interface recombination,leading to an increase in short-circuit current density(J_(sc))by 0.8 mA/cm^(2).This benefit comes with a delicate balance between minimizing defect state density and improving doping efficiency.This study provides theoretical insights into the optimization of doped layer physical parameters and proposes practical solutions,including nano-crystallization and low-doping interface strategies,to improve the performance of SHJ solar cells and support industrial applications.
基金supported by the Open Research Fund of Key Laboratory of Geological Hazards on Three Gorges Reservoir Area(China Three Gorges University),Ministry of Education(No.2022KDZ03)the Science and Technology Projects of Yunnan Provincial Science and Technology Department(No.202401AT070328)+1 种基金the Young talents project of“Xingdian Talent Support Program”in Yunnan Province(No.YNWR-QNBJ-2020-019)the Fund Project of China Academy of Railway Sciences Co.,Ltd.(No.2021YJ178)。
文摘0 INTRODUCTION In recent years,modern railways have been actively under construction in the complex mountainous area of Southwest China.However,rockfall poses a significant threat to both construction and operation phases of railway projects(Yan et al.,2023;Chen et al.,2022;Fanos and Pradhan,2018).
基金supported by the National Hi-tech Research and Development Program of China (863 Program) (Grant No. 2006AA0AA 02 - 2).
文摘Strong low-frequency energy beneath a hydrocarbon reservoir is called a seismic low-frequency shadow and can be used as a hydrocarbon indicator （Tarter et al., 1979） bu the physical mechanism of the observed low-frequency shadow is still unclear. To stud） the mechanism, we performed seismic numerical simulation of geological models with a hydrocarbon-bearing zone using the 2-D diffusive-viscous wave equation which car effectively model the characteristics of velocity dispersion and transform the seismic dat~ centered in a target layer slice within a time window to the time-frequency domain by usinl time-frequency signal analysis and sort the frequency gathers to common frequency cubes. Then, we observe the characteristics of the seismic low-frequency shadow in the common frequency cubes. The numerical simulations reveal that the main mechanism of seismic lowfrequency shadows is attributed to high attenuation of the medium to high seismic frequency components caused by absorption in the hydrocarbon-filled reservoir. Results from a practical example of seismic low-frequency shadows show that it is possible to identify the reservoir by the low-frequency shadow with high S/N seismic data.
