In this study,the hydraulic behavior and sand transport efficiency of the siphon automatic sand discharge device were studied by software simulation tests.By simulating the actual situation,this study analyzed how fac...In this study,the hydraulic behavior and sand transport efficiency of the siphon automatic sand discharge device were studied by software simulation tests.By simulating the actual situation,this study analyzed how factors such as the difference in water level,sediment concentration,and pipeline layout affected the sediment discharge effect.The results show that the sediment discharge device can effectively discharge sediment under diverse operating conditions and show adaptability to different environmental conditions,which indicates that it is suitable for various types of reservoir environments.展开更多
Thiadiamondoids(TDs)have recently attracted increasing attention as molecular proxies for thermochemical sulfate reduction(TSR)reactions in reservoirs.However,their formation mechanisms,as well as the generation and e...Thiadiamondoids(TDs)have recently attracted increasing attention as molecular proxies for thermochemical sulfate reduction(TSR)reactions in reservoirs.However,their formation mechanisms,as well as the generation and evolution processes,remain poorly understood.In this study,simulation experiments with a duration of 160 h were conducted on the model compound 1,3-dimethyladamantane(1,3-DMA)using the CaSO_(4),MgSO_(4),and elemental S systems,with measurements at the 10th,20th,40th,80th and 160th hours during the simulation process being presented.The results indicate that at the end of simulation,the MgSO_(4) system exhibited the lowest residual amounts of 1,3-DMA,suggesting the highest degree of TSR.Four types of non-hydrocarbon compounds with adamantane structures were detected in the liquid products in the three experiment systems:adamantanones,adamantanols,adamantanethiols(ATs),and thiaadamantanes(TAs).Among these,adamantanones exhibited the highest concentrations in the three simulation systems.In addition,TAs were dominated by C_(3)-TAs in the CaSO_(4) and MgSO_(4) systems and by C_(2)-TAs in the elemental S system.The simulation experiments revealed a strong correlation between the concentrations of TAs and adamantanones,suggesting that adamantanones might be the intermediates for TAs.Combined with the synthesis mechanism of TAs from thiaadamamantane-4,8-dione,TDs might have two different genetic mechanisms:(a)low temperature cationic carbon ion rearrangement from diagenesis to early catagenesis stage,and(b)a free sulfur radical mechanism in high-temperature TSR process during middle-late catagenesis.TAs exhibited different generation and evolution processes across different experiment systems.Notably,the MgSO_(4) system revealed that TAs undergo generation,accumulation,and destruction process,corresponding to Easy%Ro values of 0.89%-0.98%,0.98%-1.21%,and>1.21%,respectively.Among these three simulation systems,dibenzothiophenes(DBTs)concentrations consistently trended upwards,indicating TAs have lower thermal stability than DBTs.展开更多
The hybrid CO_(2) thermal technique has achieved considerable success globally in extracting residual heavy oil from reserves following a long-term steam stimulation process.Using microscopic visualization experiments...The hybrid CO_(2) thermal technique has achieved considerable success globally in extracting residual heavy oil from reserves following a long-term steam stimulation process.Using microscopic visualization experiments and molecular dynamics(MD)simulations,this study investigates the microscopic enhanced oil recovery(EOR)mechanisms underlying residual oil removal using hybrid CO_(2) thermal systems.Based on the experimental models for the occurrence of heavy oil,this study evaluates the performance of hybrid CO_(2) thermal systems under various conditions using MD simulations.The results demonstrate that introducing CO_(2) molecules into heavy oil can effectively penetrate and decompose dense aggregates that are originally formed on hydrophobic surfaces.A stable miscible hybrid CO_(2) thermal system,with a high effective distribution ratio of CO_(2),proficiently reduces the interaction energies between heavy oil and rock surfaces,as well as within heavy oil.A visualization analysis of the interactions reveals that strong van der Waals(vdW)attractions occur between CO_(2) and heavy oil molecules,effectively promoting the decomposition and swelling of heavy oil.This unlocks the residual oil on the hydrophobic surfaces.Considering the impacts of temperature and CO_(2) concentration,an optimal gas-to-steam injection ratio(here,the CO_(2):steam ratio)ranging between 1:6 and 1:9 is recommended.This study examines the microscopic mechanisms underlying the hybrid CO_(2) thermal technique at a molecular scale,providing a significant theoretical guide for its expanded application in EOR.展开更多
In the ultra-deep strata of the Tarim Basin,the vertical growth process of strike-slip faults remains unclear,and the vertical distribution of fractured-cavity carbonate reservoirs is complex.This paper investigates t...In the ultra-deep strata of the Tarim Basin,the vertical growth process of strike-slip faults remains unclear,and the vertical distribution of fractured-cavity carbonate reservoirs is complex.This paper investigates the vertical growth process of strike-slip faults through field outcrop observations in the Keping area,interpretation of seismic data from the Fuman Oilfield,Tarim Basim,NW China,and structural physical simulation experiments.The results are obtained mainly in four aspects.First,field outcrops and ultra-deep seismic profiles indicate a three-layer structure within the strike-slip fault,consisting of fault core,fracture zone and primary rock.The fault core can be classified into three parts vertically:fracture-cavity unit,fault clay and breccia zone.The distribution of fracture-cavity units demonstrates a distinct pattern of vertical stratification,owing to the structural characteristics and growth process of the slip-strike fault.Second,the ultra-deep seismic profiles show multiple fracture-cavity units in the strike-slip fault zone.These units can be classified into four types:top fractured,middle connected,deep terminated,and intra-layer fractured.Third,structural physical simulation experiments and ultra-deep seismic data interpretation reveal that the strike-slip faults have evolved vertically in three stages:segmental rupture,vertical growth,and connection and extension.The particle image velocimetry detection demonstrates that the initial fracture of the fault zone occurred at the top or bottom and then evolved into cavities gradually along with the fault growth,accompanied by the emergence of new fractures in the middle part of the strata,which subsequently connected with the deep and shallow cavities to form a complete fault zone.Fourth,the ultra-deep carbonate strata primarily develop three types of fractured-cavity reservoirs:flower-shaped fracture,large and deep fault and staggered overlap.The first two types are larger in size with better reservoir conditions,suggesting a significant exploration potential.展开更多
In order to facilitate the teaching of industrial processes and experiments on the twin-screw extruder control debugging,and be closer to the actual testing,to reduce the debugging costs and the risk of debugging proc...In order to facilitate the teaching of industrial processes and experiments on the twin-screw extruder control debugging,and be closer to the actual testing,to reduce the debugging costs and the risk of debugging process,the paper designs a hardware-in-loop simulation of twin-screw extruder experiment system which is closer to scene,low cost and high safety.The system through the establishment of twin-screw extruder’s mathematical model on computer to simulate the realistic system and there is hardware practicality in the computer simulation loop.The hardware based on C8051F020 can operate in the simulation loop in real time.In computer software design, we desigh man-machine interface that is intuitive and easy to operate,can reflect twin-screw extruder main operation information vividly.Finally,twin-screw extruder’s 3 heater temperature mathematical model and PID incremental control algorithm are presented.展开更多
The flow field around a spur dike has three-dimensional characteristics. In order to analyze the influence of the flow field on pollutant transport, based on a compressive volume of fluid （VOF） scheme, the three-dim...The flow field around a spur dike has three-dimensional characteristics. In order to analyze the influence of the flow field on pollutant transport, based on a compressive volume of fluid （VOF） scheme, the three-dimensional transient compressive pollutant transport model （CPTM） and the cubic equation （CE） bounded differencing scheme were developed. For the calibration and validation of CPTM, laboratory experiments were carried out in a flume with a non-submerged spur dike. The spur dike was angled at 60°, 90°, and 120° from the upstream direction. The simulation results agreed with the experimental results. The simulations and experiments showed that the distribution of pollutant concentration was determined by circumfluence and the main flow. Concentration decay in the circumfluenee zone was slower than that in the main flow. Downstream of the spur dike, the concentration fluctuation became intensive with the increase of spur dike angle.展开更多
In order to improve our understanding of rock fracture and fault instability driven by high-pressure fluid sources, the authors carried out rock fracture tests using granite under a confining pressure of 80 MPa with f...In order to improve our understanding of rock fracture and fault instability driven by high-pressure fluid sources, the authors carried out rock fracture tests using granite under a confining pressure of 80 MPa with fluid injection in the laboratory. Furthermore, we tested a number of numerical models using the FLAC;modeling software to find the best model to represent the experimental results. The high-speed multichannel acoustic emission（AE） waveform recording system used in this study made it possible to examine the total fracture process through detailed monitoring of AE hypocenters and seismic velocity.The experimental results show that injecting high-pressure oil into the rock sample can induce AE activity at very low stress levels and can dramatically reduce the strength of the rock. The results of the numerical simulations show that major experimental results, including the strength, the temporal and spatial patterns of the AE events, and the role of the fluid can be represented fairly well by a model involving（1） randomly distributed defect elements to model pre-existing cracks,（2） random modification of rock properties to represent inhomogeneity introduced by different mineral grains, and（3）macroscopic inhomogeneity. Our study, which incorporates laboratory experiments and numerical simulations, indicates that such an approach is helpful in finding a better model not only for simulating experimental results but also for upscaling purposes.展开更多
With the development of cold region engineering,it is crucial to study the mechanical properties of frozen soil.In practice,frozen soil is inevitably subject to impact loading,making the study of frozen soil under imp...With the development of cold region engineering,it is crucial to study the mechanical properties of frozen soil.In practice,frozen soil is inevitably subject to impact loading,making the study of frozen soil under impact loading necessary for engineering in cold regions.The split–Hopkinson pressure bar(SHPB)is an important experimental means for obtaining the dynamic performance of materials.In this study,an SHPB experiment was conducted on frozen soil under confining pressure.The frozen soil exhibited an evident strain rate effect and temperature effect under confining pressure.The SHPB experiment on frozen soil under confining pressure was simulated numerically using LS-DYNA software and the Holmquist–Johnson–Cook(HJC)material model.A loading simulation with passive confining pressure and active confining pressure was completed by adding an aluminum sleeve and applying a constant load.The simulation results obtained using the above methods were in good agreement with the experimental results.The strength of the frozen soil under confining pressure was greater than that of the uniaxial impact,and there was an evident confining pressure effect.Furthermore,the confining pressure provided by passive confinement was larger than that provided by active confinement.The passive confining pressure energy absorption efficiency was higher than for the active confining pressure due to the need to absorb more energy under the same damage conditions.The frozen soil exhibited viscoplastic failure characteristics under confining pressure.展开更多
A planar passive walking model with straight legs and round feet was discussed. This model can walk down steps, both on stairs with even steps and with random steps. Simulations showed that models with small moments o...A planar passive walking model with straight legs and round feet was discussed. This model can walk down steps, both on stairs with even steps and with random steps. Simulations showed that models with small moments of inertia can navigate large height steps. Period-doubling has been observed when the space between steps grows. This period-doubling has been validated by experiments, and the results of experiments were coincident with the simulation.展开更多
Sesquiterpanes are ubiquitous components of crude oils and ancient sediments.Liquid saturated hydrocarbons from simulated pyrolysis experiments on immature organic-rich mudstone collected from the Lower Cretaceous Hes...Sesquiterpanes are ubiquitous components of crude oils and ancient sediments.Liquid saturated hydrocarbons from simulated pyrolysis experiments on immature organic-rich mudstone collected from the Lower Cretaceous Hesigewula Sag were analyzed by gas chromatography-mass spectrometry(GC-MS).C14 bicyclic sesquiterpanes,namely,8β(H)-drimane,8β(H)-homodrimane,and 8 a(H)-homodrimane were detected and identified on basis of their diagnostic fragment ions(m/z123,179,193,and 207),and previously published mass spectra data,and these bicyclic sesquiterpanes presented relatively regular characteristics in their thermal evolution.The ratios 8β(H)-drimane/8β(H)-homodrimane,8β(H)-homodrimane/8 a(H)-homodrimane,and 8β(H)-drimane/8 a(H)-homodrimane all show a clear upward trend with increasing temperature below the temperature turning point.Thus,all these ratios can be used as evolution indexes of source rocks in the immature-lowmaturity stage.However,the last two ratios may be more suitable than the first ratio as valid parameters for measuring the extent of thermal evolution of organic matter in the immature-low-maturity stage because their change amplitude with increasing temperature is more obvious.展开更多
To investigate the metal flow during the railway wheel forming process, experiments and finite element method （FEM） simulation were carried out. An axisymmetric modeling for the wheel rolling process was proposed to...To investigate the metal flow during the railway wheel forming process, experiments and finite element method （FEM） simulation were carried out. An axisymmetric modeling for the wheel rolling process was proposed to predict the metal flow in radial direction, by which the whole multi-stage forming process could be simulated in axisymmetric and integral way. The result shows that the axisymmetric simulation method was an effective method to explore the metal flow in radial direction and to analyze the relationships of tools motion during the wheel rolling. The detail information about metal flow in railway wheel forming process was obtained. The metal in the wheel web was from the area near the half radius of the original billet; the chill zone of the billet became an envelope of the rim and part of the web with a maximum thickness of about 6 mm below the tread. At the wheel rolling stage, the metal in the rim flowed towards the web; the metal near the surfaces of the conjunction region between the web and rim suffered severe shear deformation.展开更多
In modem manufacturing, a new type of sheet metal part with step cross-section in both inner hole and outer edge is proposed. The traditional stamping separating processes can only produce sheet metal part with vertic...In modem manufacturing, a new type of sheet metal part with step cross-section in both inner hole and outer edge is proposed. The traditional stamping separating processes can only produce sheet metal part with vertical cross-section. According to the latest developing theory and potential of cold pressure forming： combination of pressure and cold forging, a new flow control forming of sheet metal（FCF） is excogitated based on blanking process of general stamping and combined with cold forging processes such as extrusion and coining, etc, which is aiming at the above-mentioned new type of sheet metal part. With utilization of this new process, the new type of sheet metal parts can be manufactured. In order to shorten the testing period, the numerical simulation was carried out by using DEFORM-3D software, and both deformation and mechanics rules were analyzed. Based on the simulation, both punching part and blanked parts of this new type were successfully developed. Then a new conception of optimal distance between the step walls of inner hole and outside edge was proposed and the design principle for its numerical value was inferred. Furthermore, a mold set for combination of stamping ＆ cold forging was designed and manufactured, by which the technologic experiments were taken for validation with Aluminum plate of thickness 2.35 mm for power battery cover board, which verified the principle of the distance between the step walls. The research of cold pressure forming of thin sheet metal with step cross-section is significant, not only to the development of modem mechanical manufacture, but also to metal plastic forming science.展开更多
In order to obtain the reasonable operating conditions and minimize the power consumption in the stirred bioreactor, the hydrodynamic experiments in the stirred bioreactor have been taken to obtain the basic data. Sub...In order to obtain the reasonable operating conditions and minimize the power consumption in the stirred bioreactor, the hydrodynamic experiments in the stirred bioreactor have been taken to obtain the basic data. Subsequently, an Eulerian model for the gas–liquid–solid three phase flow in the stirred bioreactor has been proposed and the CFD simulation has been conducted. By comparing the results of experiment and simulation, it can be concluded that the simulation results were consistent with the experimental data. The inner relationship between operating variables and indicators could be obtained by comparing the results of just suspension speed, gas holdup, power consumption and operational maps, further the reasonable operating conditions could be also determined under the minimum power consumption. The operational maps could provide the theoretical foundation for industrial application of the gas–liquid–solid stirred bioreactors under the low solid concentration(no more than 20 wt%).展开更多
A mobile robot developed by Wuhan University for full-path hotline inspection on 220 kV transmission lines was presented. With 4 rotating joints and 2 translational ones, such robot is capable of traveling along non- ...A mobile robot developed by Wuhan University for full-path hotline inspection on 220 kV transmission lines was presented. With 4 rotating joints and 2 translational ones, such robot is capable of traveling along non- obstaclestraight-line segment and surmounting straight-line segment obstacles as well as transferring between two spans automatically. Lagrange’s equations were utilized to derive dynamic equations of all the links, including items of inertia, coupling inertia, Coriolis acceleration, centripetal acceleration and gravity. And a dynamic response experiment on elemental motions of robot prototype’s travelling along non-obstacle straight-line segment and surmounting obstacles was performed on 220 kV 1∶1 simulative overhanging transmission-line in laboratory. In addition, dynamic numerical simulation was conducted in the corresponding condition. Comparison and analysis on results of experiment and numerical simulation have validated theoretical model and simulation resolution. Therefore, the dynamic model formed hereunder can be used for the study of robot control.展开更多
In the process of thin-wall parts assembly for an antenna,the parts assembly deformation deviation is occurring due to the riveting assembly.In view of the riveting assembly deformation problems,it can be analyzed thr...In the process of thin-wall parts assembly for an antenna,the parts assembly deformation deviation is occurring due to the riveting assembly.In view of the riveting assembly deformation problems,it can be analyzed through transient and static simulation.In this work,the theoretical deformation model for riveting assembly is established with round head rivet.The simulation analysis for riveting deformation is carried out with the riveting assembly piece including four rivets,which comparing with the measuring points experiment results of riveting test piece through dealing with the experimental data using the point coordinate transform method and the space line fitting method.Simultaneously,the deformation deviation of the overall thin-wall parts assembly structure is analyzed through finite element simulation;and its results are verified by the measuring experiment for riveting assembly with the deformation deviation of some key points on the thin-wall parts.Through the comparison analysis,it is shown that the simulation results agree well with the experimental results,which proves the correctness and effectiveness of the theoretical analysis,simulation results and the given experiment data processing method.Through the study on the riveting assembly for thin-wall parts,it will provide a theoretical foundation for improving thin-wall parts assembly quality of large antenna in future.展开更多
Fluvial dynamic landform is produced by reaction between fluvial bchaviour and suffoce matenal. It possesses apparent environmental effects. As a branch of gcomorphology, the fiuvial dynandc gcomorphology is a margina...Fluvial dynamic landform is produced by reaction between fluvial bchaviour and suffoce matenal. It possesses apparent environmental effects. As a branch of gcomorphology, the fiuvial dynandc gcomorphology is a marginal science among fiuid dynalnics, sediment mechaltics and fluvial goomorphology. With physical modelling by sindlarity based on Newtonian mechanics, and pnnciple of the same effect bot diffend struCture based on systelnahc theory, it is possible to study propenies, formation and processes in fluvial dynamic gcomorphology. A new research method, which is a combination of mathematical simulation by computer with physical modelling will be deveoped.展开更多
In this study, the glass transition and uniaxial tensile properties of a commercially available epoxy adhesive were investigated using experimental measurements and molecular dynamics （MD） simulation. Differential s...In this study, the glass transition and uniaxial tensile properties of a commercially available epoxy adhesive were investigated using experimental measurements and molecular dynamics （MD） simulation. Differential scanning calorimetry （DSC） was used to study the change of glass transition temperature （Tg） with cross-link density （CLD）. Uniaxial tensile test was performed to measure the Young＇s modulus （E）, Poisson＇s ratio （v） and yielding strength （tyv）. In MD simulation, the complicated epoxy system was simplified as the mixture of two kinds of simple molecules, with the key information well preserved and the less important details omitted. The molecular model of the cross-linked epoxy network was constructed and its mechanical properties were calculated using MD simulation. Overall, the MD simulation results agreed with experimental ones, which proved the validity of the molecular model and justified the simplification method of the industry- level epoxy system.展开更多
Vegetation plays a key role in improving wind environment of residential districts,and is helpful for creating a comfortable and beautiful living environment.The optimal design of vegetation for wind environment impro...Vegetation plays a key role in improving wind environment of residential districts,and is helpful for creating a comfortable and beautiful living environment.The optimal design of vegetation for wind environment improvement in winter was investigated by carrying out field experiments in Heqingyuan residential area in Beijing,and after that,numerical simulation with SPOTE(simulation platform for outdoor thermal environment) experiments for outdoor thermal environment of vegetation was adopted for comparison.The conclusions were summarized as follows:1) By comparing the experimental data with simulation results,it could be concluded that the wind field simulated was consistent with the actual wind field,and the flow distribution impacted by vegetation could be accurately reflected;2) The wind velocity with vegetation was lower than that without vegetation,and the wind velocity was reduced by 46%;3) By adjusting arrangement and types of vegetation in the regions with excessively large wind velocity,the pedestrian-level wind velocity could be obviously improved through the simulation and comparison.展开更多
Thermochemical sulfate reduction (TSR) in geological deposits can account for the accumulation of H2S in deep sour gas reservoirs. In this paper, thermal simulation experiments on the reaction of CH4-CaSO4 were carri...Thermochemical sulfate reduction (TSR) in geological deposits can account for the accumulation of H2S in deep sour gas reservoirs. In this paper, thermal simulation experiments on the reaction of CH4-CaSO4 were carried out using an autoclave at high temperatures and high pressures. The products were characterized with analytical methods including carbon isotope analysis. It is found that the reaction can proceed to produce H2S, H2O and CaCO3 as the main products. Based on the experimental results, the carbon kinetic isotope fractionation was investigated, and the value of Ki (kinetic isotope effect) was calculated. The results obtained in this paper can provide useful information to explain the occurrence of H2S in deep carbonate gas reservoirs.展开更多
The physiological structure of the upper respiratory tract is complex and varies with each individual,and the circulating air has turbulent performance.In this paper,based on computed tomography(CT)medical images publ...The physiological structure of the upper respiratory tract is complex and varies with each individual,and the circulating air has turbulent performance.In this paper,based on computed tomography(CT)medical images published online and the three-dimensional(3D)printing technology,a 3D model of the human upper respiratory tract was reconstructed and an experimental device of the upper respiratory tract was made.We implemented the respiratory experiment and measured the flow rate,and a scale-adaptive κ-ω model is applied for numerical simulation,the results are in good agreement.The flow field during respiratory was analyzed by coronal velocity cross section,vortex line and particle tracks.We found that the relatively strong shear effect happens at the areas of nasal valve and nasopharynx.In the middle and upper nasal tract,vortex line separation occurs and there is significant passage effect.The results indicate that SAS method is effective in studying upper respiratory airflow.展开更多
基金Supported by the National Undergraduate Innovation Training Program(Project No.202211437036).
文摘In this study,the hydraulic behavior and sand transport efficiency of the siphon automatic sand discharge device were studied by software simulation tests.By simulating the actual situation,this study analyzed how factors such as the difference in water level,sediment concentration,and pipeline layout affected the sediment discharge effect.The results show that the sediment discharge device can effectively discharge sediment under diverse operating conditions and show adaptability to different environmental conditions,which indicates that it is suitable for various types of reservoir environments.
基金funded by the Natural Science Foundation of China(Grants Nos.42272167,U24B6001,and 41772153)Science&Technology Project of Sinopec(Grant Nos.P23167 and P24173).
文摘Thiadiamondoids(TDs)have recently attracted increasing attention as molecular proxies for thermochemical sulfate reduction(TSR)reactions in reservoirs.However,their formation mechanisms,as well as the generation and evolution processes,remain poorly understood.In this study,simulation experiments with a duration of 160 h were conducted on the model compound 1,3-dimethyladamantane(1,3-DMA)using the CaSO_(4),MgSO_(4),and elemental S systems,with measurements at the 10th,20th,40th,80th and 160th hours during the simulation process being presented.The results indicate that at the end of simulation,the MgSO_(4) system exhibited the lowest residual amounts of 1,3-DMA,suggesting the highest degree of TSR.Four types of non-hydrocarbon compounds with adamantane structures were detected in the liquid products in the three experiment systems:adamantanones,adamantanols,adamantanethiols(ATs),and thiaadamantanes(TAs).Among these,adamantanones exhibited the highest concentrations in the three simulation systems.In addition,TAs were dominated by C_(3)-TAs in the CaSO_(4) and MgSO_(4) systems and by C_(2)-TAs in the elemental S system.The simulation experiments revealed a strong correlation between the concentrations of TAs and adamantanones,suggesting that adamantanones might be the intermediates for TAs.Combined with the synthesis mechanism of TAs from thiaadamamantane-4,8-dione,TDs might have two different genetic mechanisms:(a)low temperature cationic carbon ion rearrangement from diagenesis to early catagenesis stage,and(b)a free sulfur radical mechanism in high-temperature TSR process during middle-late catagenesis.TAs exhibited different generation and evolution processes across different experiment systems.Notably,the MgSO_(4) system revealed that TAs undergo generation,accumulation,and destruction process,corresponding to Easy%Ro values of 0.89%-0.98%,0.98%-1.21%,and>1.21%,respectively.Among these three simulation systems,dibenzothiophenes(DBTs)concentrations consistently trended upwards,indicating TAs have lower thermal stability than DBTs.
基金financially supported by the National Natural Science Foundation of China(No.U20B6003)the China Scholarship Council(No.202306440015)a project of the China Petroleum&Chemical Corporation(No.P22174)。
文摘The hybrid CO_(2) thermal technique has achieved considerable success globally in extracting residual heavy oil from reserves following a long-term steam stimulation process.Using microscopic visualization experiments and molecular dynamics(MD)simulations,this study investigates the microscopic enhanced oil recovery(EOR)mechanisms underlying residual oil removal using hybrid CO_(2) thermal systems.Based on the experimental models for the occurrence of heavy oil,this study evaluates the performance of hybrid CO_(2) thermal systems under various conditions using MD simulations.The results demonstrate that introducing CO_(2) molecules into heavy oil can effectively penetrate and decompose dense aggregates that are originally formed on hydrophobic surfaces.A stable miscible hybrid CO_(2) thermal system,with a high effective distribution ratio of CO_(2),proficiently reduces the interaction energies between heavy oil and rock surfaces,as well as within heavy oil.A visualization analysis of the interactions reveals that strong van der Waals(vdW)attractions occur between CO_(2) and heavy oil molecules,effectively promoting the decomposition and swelling of heavy oil.This unlocks the residual oil on the hydrophobic surfaces.Considering the impacts of temperature and CO_(2) concentration,an optimal gas-to-steam injection ratio(here,the CO_(2):steam ratio)ranging between 1:6 and 1:9 is recommended.This study examines the microscopic mechanisms underlying the hybrid CO_(2) thermal technique at a molecular scale,providing a significant theoretical guide for its expanded application in EOR.
基金Supported by the National Natural Science Foundation of China(42362026)Key R&D Project of Xinjiang Uygur Autonomous Region(2024B01015).
文摘In the ultra-deep strata of the Tarim Basin,the vertical growth process of strike-slip faults remains unclear,and the vertical distribution of fractured-cavity carbonate reservoirs is complex.This paper investigates the vertical growth process of strike-slip faults through field outcrop observations in the Keping area,interpretation of seismic data from the Fuman Oilfield,Tarim Basim,NW China,and structural physical simulation experiments.The results are obtained mainly in four aspects.First,field outcrops and ultra-deep seismic profiles indicate a three-layer structure within the strike-slip fault,consisting of fault core,fracture zone and primary rock.The fault core can be classified into three parts vertically:fracture-cavity unit,fault clay and breccia zone.The distribution of fracture-cavity units demonstrates a distinct pattern of vertical stratification,owing to the structural characteristics and growth process of the slip-strike fault.Second,the ultra-deep seismic profiles show multiple fracture-cavity units in the strike-slip fault zone.These units can be classified into four types:top fractured,middle connected,deep terminated,and intra-layer fractured.Third,structural physical simulation experiments and ultra-deep seismic data interpretation reveal that the strike-slip faults have evolved vertically in three stages:segmental rupture,vertical growth,and connection and extension.The particle image velocimetry detection demonstrates that the initial fracture of the fault zone occurred at the top or bottom and then evolved into cavities gradually along with the fault growth,accompanied by the emergence of new fractures in the middle part of the strata,which subsequently connected with the deep and shallow cavities to form a complete fault zone.Fourth,the ultra-deep carbonate strata primarily develop three types of fractured-cavity reservoirs:flower-shaped fracture,large and deep fault and staggered overlap.The first two types are larger in size with better reservoir conditions,suggesting a significant exploration potential.
文摘In order to facilitate the teaching of industrial processes and experiments on the twin-screw extruder control debugging,and be closer to the actual testing,to reduce the debugging costs and the risk of debugging process,the paper designs a hardware-in-loop simulation of twin-screw extruder experiment system which is closer to scene,low cost and high safety.The system through the establishment of twin-screw extruder’s mathematical model on computer to simulate the realistic system and there is hardware practicality in the computer simulation loop.The hardware based on C8051F020 can operate in the simulation loop in real time.In computer software design, we desigh man-machine interface that is intuitive and easy to operate,can reflect twin-screw extruder main operation information vividly.Finally,twin-screw extruder’s 3 heater temperature mathematical model and PID incremental control algorithm are presented.
基金supported by the Eleventh Five-year Scientific and Technical Plan (Grant No. 2006BAK01B02-03)the Course Foundation of Nanjing University of Technology (Grant No. 39714004)
文摘The flow field around a spur dike has three-dimensional characteristics. In order to analyze the influence of the flow field on pollutant transport, based on a compressive volume of fluid （VOF） scheme, the three-dimensional transient compressive pollutant transport model （CPTM） and the cubic equation （CE） bounded differencing scheme were developed. For the calibration and validation of CPTM, laboratory experiments were carried out in a flume with a non-submerged spur dike. The spur dike was angled at 60°, 90°, and 120° from the upstream direction. The simulation results agreed with the experimental results. The simulations and experiments showed that the distribution of pollutant concentration was determined by circumfluence and the main flow. Concentration decay in the circumfluenee zone was slower than that in the main flow. Downstream of the spur dike, the concentration fluctuation became intensive with the increase of spur dike angle.
基金supported by State Key Laboratory of Earthquake Dynamics,China
文摘In order to improve our understanding of rock fracture and fault instability driven by high-pressure fluid sources, the authors carried out rock fracture tests using granite under a confining pressure of 80 MPa with fluid injection in the laboratory. Furthermore, we tested a number of numerical models using the FLAC;modeling software to find the best model to represent the experimental results. The high-speed multichannel acoustic emission（AE） waveform recording system used in this study made it possible to examine the total fracture process through detailed monitoring of AE hypocenters and seismic velocity.The experimental results show that injecting high-pressure oil into the rock sample can induce AE activity at very low stress levels and can dramatically reduce the strength of the rock. The results of the numerical simulations show that major experimental results, including the strength, the temporal and spatial patterns of the AE events, and the role of the fluid can be represented fairly well by a model involving（1） randomly distributed defect elements to model pre-existing cracks,（2） random modification of rock properties to represent inhomogeneity introduced by different mineral grains, and（3）macroscopic inhomogeneity. Our study, which incorporates laboratory experiments and numerical simulations, indicates that such an approach is helpful in finding a better model not only for simulating experimental results but also for upscaling purposes.
基金This work was supported by the National Natural Science Foundation of China(Grants 11672253 and 11972028)the Opening Foundation of the State Key Laboratory of Frozen Soil Engineering(Grant SKLFSE201918)and the Opening Foundation of the State Key Laboratory for Strength and Vibration of Mechanical Structures(Grant SV2019-KF-19).
文摘With the development of cold region engineering,it is crucial to study the mechanical properties of frozen soil.In practice,frozen soil is inevitably subject to impact loading,making the study of frozen soil under impact loading necessary for engineering in cold regions.The split–Hopkinson pressure bar(SHPB)is an important experimental means for obtaining the dynamic performance of materials.In this study,an SHPB experiment was conducted on frozen soil under confining pressure.The frozen soil exhibited an evident strain rate effect and temperature effect under confining pressure.The SHPB experiment on frozen soil under confining pressure was simulated numerically using LS-DYNA software and the Holmquist–Johnson–Cook(HJC)material model.A loading simulation with passive confining pressure and active confining pressure was completed by adding an aluminum sleeve and applying a constant load.The simulation results obtained using the above methods were in good agreement with the experimental results.The strength of the frozen soil under confining pressure was greater than that of the uniaxial impact,and there was an evident confining pressure effect.Furthermore,the confining pressure provided by passive confinement was larger than that provided by active confinement.The passive confining pressure energy absorption efficiency was higher than for the active confining pressure due to the need to absorb more energy under the same damage conditions.The frozen soil exhibited viscoplastic failure characteristics under confining pressure.
文摘A planar passive walking model with straight legs and round feet was discussed. This model can walk down steps, both on stairs with even steps and with random steps. Simulations showed that models with small moments of inertia can navigate large height steps. Period-doubling has been observed when the space between steps grows. This period-doubling has been validated by experiments, and the results of experiments were coincident with the simulation.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41672117 and 41503034)the Hubei Provincial Natural Science Foundation of China (Project No. 2017CFA027)+1 种基金the Open Subject of Shandong Provincial Key Laboratory of Depositional Mineralization & Sedimentary Mineral (Baojun Liu Geoscience Science Foundation) (DMSM2017084)the Open Subject of the State Key Laboratory of Petroleum Resources and Prospecting (PRP/open-1509)
文摘Sesquiterpanes are ubiquitous components of crude oils and ancient sediments.Liquid saturated hydrocarbons from simulated pyrolysis experiments on immature organic-rich mudstone collected from the Lower Cretaceous Hesigewula Sag were analyzed by gas chromatography-mass spectrometry(GC-MS).C14 bicyclic sesquiterpanes,namely,8β(H)-drimane,8β(H)-homodrimane,and 8 a(H)-homodrimane were detected and identified on basis of their diagnostic fragment ions(m/z123,179,193,and 207),and previously published mass spectra data,and these bicyclic sesquiterpanes presented relatively regular characteristics in their thermal evolution.The ratios 8β(H)-drimane/8β(H)-homodrimane,8β(H)-homodrimane/8 a(H)-homodrimane,and 8β(H)-drimane/8 a(H)-homodrimane all show a clear upward trend with increasing temperature below the temperature turning point.Thus,all these ratios can be used as evolution indexes of source rocks in the immature-lowmaturity stage.However,the last two ratios may be more suitable than the first ratio as valid parameters for measuring the extent of thermal evolution of organic matter in the immature-low-maturity stage because their change amplitude with increasing temperature is more obvious.
基金Sponsored by National High-tech Research and Development Program(863 Program)of China(2008AA030703)
文摘To investigate the metal flow during the railway wheel forming process, experiments and finite element method （FEM） simulation were carried out. An axisymmetric modeling for the wheel rolling process was proposed to predict the metal flow in radial direction, by which the whole multi-stage forming process could be simulated in axisymmetric and integral way. The result shows that the axisymmetric simulation method was an effective method to explore the metal flow in radial direction and to analyze the relationships of tools motion during the wheel rolling. The detail information about metal flow in railway wheel forming process was obtained. The metal in the wheel web was from the area near the half radius of the original billet; the chill zone of the billet became an envelope of the rim and part of the web with a maximum thickness of about 6 mm below the tread. At the wheel rolling stage, the metal in the rim flowed towards the web; the metal near the surfaces of the conjunction region between the web and rim suffered severe shear deformation.
文摘In modem manufacturing, a new type of sheet metal part with step cross-section in both inner hole and outer edge is proposed. The traditional stamping separating processes can only produce sheet metal part with vertical cross-section. According to the latest developing theory and potential of cold pressure forming： combination of pressure and cold forging, a new flow control forming of sheet metal（FCF） is excogitated based on blanking process of general stamping and combined with cold forging processes such as extrusion and coining, etc, which is aiming at the above-mentioned new type of sheet metal part. With utilization of this new process, the new type of sheet metal parts can be manufactured. In order to shorten the testing period, the numerical simulation was carried out by using DEFORM-3D software, and both deformation and mechanics rules were analyzed. Based on the simulation, both punching part and blanked parts of this new type were successfully developed. Then a new conception of optimal distance between the step walls of inner hole and outside edge was proposed and the design principle for its numerical value was inferred. Furthermore, a mold set for combination of stamping ＆ cold forging was designed and manufactured, by which the technologic experiments were taken for validation with Aluminum plate of thickness 2.35 mm for power battery cover board, which verified the principle of the distance between the step walls. The research of cold pressure forming of thin sheet metal with step cross-section is significant, not only to the development of modem mechanical manufacture, but also to metal plastic forming science.
基金Supported by the National Natural Science Foundation of China(21476049,21506033)Department of Science and Technology of Fujian Province,China(2014R1004-3,2015J01052,2016H4023 and FG-2016005)
文摘In order to obtain the reasonable operating conditions and minimize the power consumption in the stirred bioreactor, the hydrodynamic experiments in the stirred bioreactor have been taken to obtain the basic data. Subsequently, an Eulerian model for the gas–liquid–solid three phase flow in the stirred bioreactor has been proposed and the CFD simulation has been conducted. By comparing the results of experiment and simulation, it can be concluded that the simulation results were consistent with the experimental data. The inner relationship between operating variables and indicators could be obtained by comparing the results of just suspension speed, gas holdup, power consumption and operational maps, further the reasonable operating conditions could be also determined under the minimum power consumption. The operational maps could provide the theoretical foundation for industrial application of the gas–liquid–solid stirred bioreactors under the low solid concentration(no more than 20 wt%).
文摘A mobile robot developed by Wuhan University for full-path hotline inspection on 220 kV transmission lines was presented. With 4 rotating joints and 2 translational ones, such robot is capable of traveling along non- obstaclestraight-line segment and surmounting straight-line segment obstacles as well as transferring between two spans automatically. Lagrange’s equations were utilized to derive dynamic equations of all the links, including items of inertia, coupling inertia, Coriolis acceleration, centripetal acceleration and gravity. And a dynamic response experiment on elemental motions of robot prototype’s travelling along non-obstacle straight-line segment and surmounting obstacles was performed on 220 kV 1∶1 simulative overhanging transmission-line in laboratory. In addition, dynamic numerical simulation was conducted in the corresponding condition. Comparison and analysis on results of experiment and numerical simulation have validated theoretical model and simulation resolution. Therefore, the dynamic model formed hereunder can be used for the study of robot control.
基金Project(51675100)supported by the National Natural Science Foundation of ChinaProject(2016ZX04004008)supported by the National Numerical Control Equipment Major Project of ChinaProject(6902002116)supported by the Foundation of Certain Ministry of China
文摘In the process of thin-wall parts assembly for an antenna,the parts assembly deformation deviation is occurring due to the riveting assembly.In view of the riveting assembly deformation problems,it can be analyzed through transient and static simulation.In this work,the theoretical deformation model for riveting assembly is established with round head rivet.The simulation analysis for riveting deformation is carried out with the riveting assembly piece including four rivets,which comparing with the measuring points experiment results of riveting test piece through dealing with the experimental data using the point coordinate transform method and the space line fitting method.Simultaneously,the deformation deviation of the overall thin-wall parts assembly structure is analyzed through finite element simulation;and its results are verified by the measuring experiment for riveting assembly with the deformation deviation of some key points on the thin-wall parts.Through the comparison analysis,it is shown that the simulation results agree well with the experimental results,which proves the correctness and effectiveness of the theoretical analysis,simulation results and the given experiment data processing method.Through the study on the riveting assembly for thin-wall parts,it will provide a theoretical foundation for improving thin-wall parts assembly quality of large antenna in future.
文摘Fluvial dynamic landform is produced by reaction between fluvial bchaviour and suffoce matenal. It possesses apparent environmental effects. As a branch of gcomorphology, the fiuvial dynandc gcomorphology is a marginal science among fiuid dynalnics, sediment mechaltics and fluvial goomorphology. With physical modelling by sindlarity based on Newtonian mechanics, and pnnciple of the same effect bot diffend struCture based on systelnahc theory, it is possible to study propenies, formation and processes in fluvial dynamic gcomorphology. A new research method, which is a combination of mathematical simulation by computer with physical modelling will be deveoped.
文摘In this study, the glass transition and uniaxial tensile properties of a commercially available epoxy adhesive were investigated using experimental measurements and molecular dynamics （MD） simulation. Differential scanning calorimetry （DSC） was used to study the change of glass transition temperature （Tg） with cross-link density （CLD）. Uniaxial tensile test was performed to measure the Young＇s modulus （E）, Poisson＇s ratio （v） and yielding strength （tyv）. In MD simulation, the complicated epoxy system was simplified as the mixture of two kinds of simple molecules, with the key information well preserved and the less important details omitted. The molecular model of the cross-linked epoxy network was constructed and its mechanical properties were calculated using MD simulation. Overall, the MD simulation results agreed with experimental ones, which proved the validity of the molecular model and justified the simplification method of the industry- level epoxy system.
基金Project(50878111) supported by the National Natural Science Foundation of China
文摘Vegetation plays a key role in improving wind environment of residential districts,and is helpful for creating a comfortable and beautiful living environment.The optimal design of vegetation for wind environment improvement in winter was investigated by carrying out field experiments in Heqingyuan residential area in Beijing,and after that,numerical simulation with SPOTE(simulation platform for outdoor thermal environment) experiments for outdoor thermal environment of vegetation was adopted for comparison.The conclusions were summarized as follows:1) By comparing the experimental data with simulation results,it could be concluded that the wind field simulated was consistent with the actual wind field,and the flow distribution impacted by vegetation could be accurately reflected;2) The wind velocity with vegetation was lower than that without vegetation,and the wind velocity was reduced by 46%;3) By adjusting arrangement and types of vegetation in the regions with excessively large wind velocity,the pedestrian-level wind velocity could be obviously improved through the simulation and comparison.
文摘Thermochemical sulfate reduction (TSR) in geological deposits can account for the accumulation of H2S in deep sour gas reservoirs. In this paper, thermal simulation experiments on the reaction of CH4-CaSO4 were carried out using an autoclave at high temperatures and high pressures. The products were characterized with analytical methods including carbon isotope analysis. It is found that the reaction can proceed to produce H2S, H2O and CaCO3 as the main products. Based on the experimental results, the carbon kinetic isotope fractionation was investigated, and the value of Ki (kinetic isotope effect) was calculated. The results obtained in this paper can provide useful information to explain the occurrence of H2S in deep carbonate gas reservoirs.
基金supported by the Fundamental Research Funds for the Central Universities of China (Grant 17LGJC41)
文摘The physiological structure of the upper respiratory tract is complex and varies with each individual,and the circulating air has turbulent performance.In this paper,based on computed tomography(CT)medical images published online and the three-dimensional(3D)printing technology,a 3D model of the human upper respiratory tract was reconstructed and an experimental device of the upper respiratory tract was made.We implemented the respiratory experiment and measured the flow rate,and a scale-adaptive κ-ω model is applied for numerical simulation,the results are in good agreement.The flow field during respiratory was analyzed by coronal velocity cross section,vortex line and particle tracks.We found that the relatively strong shear effect happens at the areas of nasal valve and nasopharynx.In the middle and upper nasal tract,vortex line separation occurs and there is significant passage effect.The results indicate that SAS method is effective in studying upper respiratory airflow.
