Understanding the physical,mechanical behavior,and seepage characteristics of coal under hydro-mechanical coupling holds significant importance for ensuring the stability of surrounding rock formations and preventing ...Understanding the physical,mechanical behavior,and seepage characteristics of coal under hydro-mechanical coupling holds significant importance for ensuring the stability of surrounding rock formations and preventing gas outbursts.Scanning electron microscopy,uniaxial tests,and triaxial tests were conducted to comprehensively analyze the macroscopic and microscopic physical and mechanical characteristics of coal under different soaking times.Moreover,by restoring the stress path and water injection conditions of the protective layer indoors,we explored the coal mining dynamic behavior and the evolution of permeability.The results show that water causes the micro-surface of coal to peel off and cracks to expand and develop.With the increase of soaking time,the uniaxial and triaxial strengths were gradually decreased with nonlinear trend,and decreased by 63.31%and 30.95%after soaking for 240 h,respectively.Under different water injection pressure conditions,coal permeability undergoes three stages during the mining loading process and ultimately increases to higher values.The peak stress of coal,the deviatoric stress and strain at the permeability surge point all decrease with increasing water injection pressure.The results of this research can help improve the understanding of the coal mechanical properties and seepage evolution law under hydro-mechanical coupling.展开更多
Accurately characterizing the liver's mechanical properties is of paramount importance for disease diagnosis,treatment,surgical prosthetic modeling,and impact injury dummies.However,due to its inherent biological ...Accurately characterizing the liver's mechanical properties is of paramount importance for disease diagnosis,treatment,surgical prosthetic modeling,and impact injury dummies.However,due to its inherent biological soft tissue nature,the characterization of mechanical behavior varies across testing methods and sample types.In this study,we employed transmission electron microscope and Micro CT to observe the morphology of the marginal and center of rat livers and conducted macroscopic mechanical tests to characterize their elasticity and viscoelasticity.The results revealed that the central region displayed higher metabolic levels,elongated mitochondria,and an abundance of rough endoplasmic reticulum at the microscale.At the mesoscale,larger diameter portal veins were mainly distributed in the central region,while smaller diameter arteries were predominantly located at the periphery.At the macroscale,under a strain rate of 0.0167 s^(-1),no significant differences were observed in the elastic properties between the two regions.However,as the strain rate increased up to 0.167 s^(-1),the central region displayed higher porosity,resulting in reduced liquid loss,increased hardness,and higher viscosity compared to the periphery.Consequently,the liver demonstrated overall heterogeneity,with isotropic models suitable for the peripheral region,while more intricate models may be required to capture the complexity of the central region with its intricate vasculature.展开更多
Plate structures are employed as important structural components in many engineering applications. Hence, assessing the structural conditions of in-service plate structures is critical to monitoring global structural ...Plate structures are employed as important structural components in many engineering applications. Hence, assessing the structural conditions of in-service plate structures is critical to monitoring global structural health. Modal curvature-based damage detection techniques have recently garnered considerable attention from the research community, and have become a promising vibration-based structural health monitoring solution. However, computing errors arise when calculating modal curvatures from lateral mode shapes, which result from unavoidable measurement errors in the mode shapes as identified from lateral vibration signals; this makes curvature-based algorithms that use a lateral measurement only theoretically feasible, but practically infeasible. Therefore, in this study, long-gauge fiber Bragg grating strain sensors are employed to obtain a modal curvature without a numerical differentiation procedure in order to circumvent the computing errors. Several damage indices based on modal curvatures that were developed to locate beam damage are employed. Both numerical and experimental studies are performed to validate the proposed approach. However, although previous studies have reported relative success with the application of these damage indices on a simple beam, only one damage index demonstrated the capability to locate damage when the stiffness of the local region changed near the sensor.展开更多
Plasma electrolytic oxidation(PEO)coatings were prepared on Al−Mg laminated macro composites(LMCs)using both unipolar and bipolar waveforms in an appropriate electrolyte for both aluminum and magnesium alloys.The tech...Plasma electrolytic oxidation(PEO)coatings were prepared on Al−Mg laminated macro composites(LMCs)using both unipolar and bipolar waveforms in an appropriate electrolyte for both aluminum and magnesium alloys.The techniques of FESEM/EDS,grazing incident beam X-ray diffraction(GIXRD),and electrochemical methods of potentiodynamic polarization and electrochemical impedance spectroscopy(EIS)were used to characterize the coatings.The results revealed that the coatings produced using the bipolar waveform exhibited lower porosity and higher thickness than those produced using the unipolar one.The corrosion performance of the specimens’cut edge was investigated using EIS after 1,8,and 12 h of immersion in a 3.5 wt.%NaCl solution.It was observed that the coating produced using the bipolar waveform demonstrated the highest corrosion resistance after 12 h of immersion,with an estimated corrosion resistance of 5.64 kΩ·cm^(2),which was approximately 3 times higher than that of the unipolar coating.Notably,no signs of galvanic corrosion were observed in the LMCs,and only minor corrosion attacks were observed on the magnesium layer in some areas.展开更多
The mechanical behavior of cohesive soil is sensitized to drying-wetting cycles under confinements.However,the hydromechanical coupling effect has not been considered in current constitutive models.A macro-micro analy...The mechanical behavior of cohesive soil is sensitized to drying-wetting cycles under confinements.However,the hydromechanical coupling effect has not been considered in current constitutive models.A macro-micro analysis scheme is proposed in this paper to investigate the soil deformation behavior under the coupling of stress and drying-wetting cycles.A new device is developed based on CT(computerized tomography)workstation to apply certain normal and shear stresses on a soil specimen during drying-wetting cycles.A series of tests are conducted on a type of loess with various coupling of stress paths and drying-wetting cycles.At macroscopic level,stress sensor and laser sensor are used to acquire stress and strain,respectively.The shear and volumetric strain increase during the first few drying-wetting cycles and then become stable.The increase of the shear stress level or confining pressure would cause higher increase rate and the value of shear strain in the process of drying-wetting cycles.At microscopic level,the grayscale value(GSV)of CT scanning image is characterized as the proportion of soil particles to voids.A fabric state parameter is proposed to characterize soil microstructures under the influence of stress and drying-wetting cycle.Test results indicate that the macroand micro-responses show high consistence and relevance.The stress and drying-wetting cycles would both induce collapse of the soil microstructure,which dominants degradation of the soil mechanical properties.The evolution of the macro-mechanical property of soil exhibits a positive linear relationship with the micro-evolution of the fabric state parameter.展开更多
Extensive research has been conducted on remaining oil in the Daqing Oilfield during high water cuts’late stage,but few studies have offered multi-level analyses from both macro and micro perspectives for remaining o...Extensive research has been conducted on remaining oil in the Daqing Oilfield during high water cuts’late stage,but few studies have offered multi-level analyses from both macro and micro perspectives for remaining oil under varying formation conditions and displacement methods.This article focuses on the remaining oil in the S,P,and G reservoirs of Daqing Oilfield by employing the frozen section analysis method on the cores from the S,P,and G oil layers.The research identifies patterns among them,revealing that the Micro Remaining Oil types in these cores primarily include pore surface thin film,corner,throat,cluster,intergranular adsorption,and particle adsorption.Among these,intergranular adsorption contains the highest amount of remaining oil(the highest proportion reaches 60%)and serves as the main target for development potential.The overall distribution pattern of the Micro Remaining Oil in the S,P,and G oil layers shows that as flooding intensity increases,the amount of free-state remaining oil gradually decreases,while bound-state remaining oil gradually increases.The study also examines eight typical coring wells for macroscopic remaining oil,finding four main types in the reservoir:interlayer difference,interlayer loss,interlayer interference,and injection-production imperfect types.Among these,the injection-production imperfect type has the highest remaining oil content and is the primary target for development potential.Analyzing the reservoir utilization status and oil flooding efficiency reveals that as water flooding intensifies,the oil displacement efficiency of the oil layer gradually decreases,while the efficiency of oil layer displacement improves.Strongly flooded cores exhibit less free-state remaining oil than weakly flooded cores,making displacement more challenging.This study aims to provide a foundation and support for the development of remaining oil in the S,P,and G oil layers.展开更多
A massive amount of plastic waste has presented an immense management challenge.This escalating ecological damage,coupled with the detrimental effects of plastics infiltrating the marine food web,poses a significant t...A massive amount of plastic waste has presented an immense management challenge.This escalating ecological damage,coupled with the detrimental effects of plastics infiltrating the marine food web,poses a significant threat to human livelihoods.To combat this,there is a call for the development of plastic detection algorithms using remote sensing data.Here we tested a new index,referred to index_(MP),to detect clusters of floating macro plastics in the ocean using satellite imagery.The index_(MP)was applied to convolution high-pass filtered(3×3)Sentinel 2 Level 1 C images,showing the potential to reduce atmospheric interference and enhance the object edges,thereby improving the clarity of detection.In the analysis,we used three scatter plots to identify and assess plastic pixels.To differentiate the common features of plastic from non-plastic objects,the Sentinel 2 bands 5,8,and 9 were plotted against index_(MP)calculated and convolution high-pass filtered Level 1 C(CHPIC)images.The plastic pixels,clustering in the three scatter plots,showed positive‘X’,i.e.,CHPIC image value and‘Y’,i.e.,each band 5,8,and 9 reflectance values,along with a CHPIC image value exceeding 0.05.Using the index_(MP)and scatter plot analysis,we identified plastic pixels containing 14%or more plastic bottles.Detection of other types of plastics,such as fishing nets and plastic bags,required pixel proportions greater than 50%.Hence,plastic bottles were notably responsive even at a low pixel fraction.We further explored the classification of plastic and non-plastic objects by analyzing reed(plant)pixels;the differentiation between plastic and reed was conducted in the band 5 and 9 scatter plots.展开更多
Deep Underground Science and Engineering(DUSE)is pleased to release this issue with feature articles reporting the advancement in several research topics related to deep underground.This issue contains one perspective...Deep Underground Science and Engineering(DUSE)is pleased to release this issue with feature articles reporting the advancement in several research topics related to deep underground.This issue contains one perspective article,two review articles,six research articles,and one case study article.These articles focus on underground energy storage,multiscale modeling for correlation between micro-scale damage and macro-scale structural degradation,mineralization and formation of gold mine,interface and fracture seepage,experimental study on tunnel-sand-pile interaction,and high water-content materials for deep underground space backfilling,analytical solutions for the crack evolution direction in brittle rocks,and a case study on the squeezing-induced failure in a water drainage tunnel and the rehabilitation measures.展开更多
Owing to their high flexibility and directional actuation capabilities,macro fiber composites(MFCs)have attracted significant attention for the active control of structures,especially in the nonlinear vibration suppre...Owing to their high flexibility and directional actuation capabilities,macro fiber composites(MFCs)have attracted significant attention for the active control of structures,especially in the nonlinear vibration suppression applications for large-scale flexible structures.In this paper,an MFC-based self-feedback system is introduced for the active control of geometrically nonlinear steady-state forced vibrations in functionally graded carbon nanotube reinforced composite(FG-CNTRC)plates subject to transverse mechanical loads.Based on the first-order shear deformation theory and the von Kármán nonlinear strain-displacement relationship,the nonlinear vibration control equations of the plate with MFC sensor and actuator layers are derived by Hamilton's principle.These equations are discretized by the finite element method(FEM),and solved by the Newton-Raphson and direct iterative methods.A velocity feedback control algorithm is introduced,and the effects of the control gain and the MFC actuator position on the nonlinear vibration active control effectiveness are analyzed.Additionally,a nonlinear resonance analysis is carried out,considering the effects of carbon nanotube(CNT)volume fraction and distribution type.The results indicate that the intrinsic characteristics of the structures significantly influence the vibration behavior.Furthermore,the appropriate selections of control gain and MFC position are crucial for the effective active control of the structures.The present work provides a promising route of the active and efficient nonlinear vibration suppression for various thin-walled structures.展开更多
Underground pumped storage power plant(UPSP)is an innovative concept for space recycling of abandoned mines.Its realization requires better understanding of the dynamic performance and durability of reservoir rock.Thi...Underground pumped storage power plant(UPSP)is an innovative concept for space recycling of abandoned mines.Its realization requires better understanding of the dynamic performance and durability of reservoir rock.This paper conducted ultrasonic detection,split Hopkinson pressure bar(SHPB)impact,mercury intrusion porosimetry(MIP),and backscatter electron observation(BSE)tests to investigate the dynamical behaviour and microstructure of sandstone with cyclical dry-wet damage.A coupling FEM-DEM model was constructed for reappearing mesoscopic structure damage.The results show that dry-wet cycles decrease the dynamic compressive strength(DCS)with a maximum reduction of 39.40%,the elastic limit strength is reduced from 41.75 to 25.62 MPa.The sieved fragments obtain the highest crack growth rate during the 23rd dry-wet cycle with a predictable life of 25 cycles for each rock particle.The pore fractal features of the macropores and micro-meso pores show great differences between the early and late cycles,which verifies the computational statistics analysis of particle deterioration.The numerical results show that the failure patterns are governed by the strain in pre-peak stage and the shear cracks are dominant.The dry-wet cycles reduce the energy transfer efficiency and lead to the discretization of force chain and crack fields.展开更多
Scientists and engineers are looking forward to new manufacturing technologies to realize the integrated fabrication of macro shape and microstructure for the components with a short production chain, which can also s...Scientists and engineers are looking forward to new manufacturing technologies to realize the integrated fabrication of macro shape and microstructure for the components with a short production chain, which can also save materials and reduce energy consumption. Additive manufacturing (AM) technology is a new fabrication pattern with a character of a lay-by-lay material deposition. The components are fabricated in a bottom-up way, from points, lines, to layers and volume, which provided a capability to solve the impossible integrated fabrication problem for micro- and macro-structure by using conventional manufacturing technologies. Thus, based on integrated fabrication of micro- and macro- structures, research team in Xi’an Jiaotong University has been focusing on technological innovations and applications of advanced additive manufacturing technologies. Novel additive manufacturing principles have been proposed and explored, by which new AM processes and equipment for met- als, composites, ceramics, and biomaterials have been developed to support the industrial applications. Additive manufacturing and cutting-edge applications of advanced composite structure, metamaterials, bio-implants, and monocrystal alloy components have been investigated to push the new development of integrated fabrication of micro- and macro- structures.展开更多
The precise compact modeling of magnetic devices is pivotal for the integrated design of spin-transfer torque magnetic tunnel junction(STT-MTJ)in conjunction with CMOS circuitry.This work presents a macro model for an...The precise compact modeling of magnetic devices is pivotal for the integrated design of spin-transfer torque magnetic tunnel junction(STT-MTJ)in conjunction with CMOS circuitry.This work presents a macro model for an STT-MTJ which is compatible with SPICE simulation platforms.The model accurately replicates the electrical performance of the MTJ,encompassing the resistance-voltage characteristics and the pulse-width-dependent state switching behavior,and is validated with various experimental data.Additionally,the impact of process variations,particularly those affecting the MTJ diameter and barrier thickness is investigated and summarized in a corner model.Monte Carlo simulations demonstrate that our adaptable and streamlined model can be efficiently incorporated into the design of integrated circuits.展开更多
Immersion of scaffolds in Simulated Body Fluid(10SBF)is a standardized method for evaluating their bioactivity,simulating in vivo conditions where apatite deposits can be formed on the surface of scaffold,facilitating...Immersion of scaffolds in Simulated Body Fluid(10SBF)is a standardized method for evaluating their bioactivity,simulating in vivo conditions where apatite deposits can be formed on the surface of scaffold,facilitating bone integration and ensuring their suitability for bone implant purposes,ultimately contributing to long-term implant success.The effect of apatite deposition on bioactivity and cell behavior of TiO_(2)scaffolds was studied.Scaffolds were soaked in 10SBF for different durations to form HAP layer on their surface.The results proved the development of a hydroxyapatite film resembling the mineral composition of bone Extracellular Matrix(ECM)on the TiO_(2)scaffolds.The XRD test findings showed the presence of hydroxyapatite layer similar to bone at the depth of 10 nm.A decrease in the specific surface area(18.913 m^(2)g^(−1)),the total pore volume(0.045172 cm^(3)g^(−1)(at p/p0=0.990)),and the mean pore diameter(9.5537 nm),were observed by BET analysis which confirmed the formation of the apatite layer.It was found that titania scaffolds with HAP coating promoted human osteosarcoma bone cell(MG63)cell attachment and growth.It seems that immersing the scaffolds in 10SBF to form HAP coating before utilizing them for bone tissue engineering applications might be a good strategy to promote bioactivity,cell attachment,and implant fixation.展开更多
The microscopic characteristics and mechanical properties of rocks change after the action of acid on deep shale,which affects the fracturing effect.Accordingly,we designed and conducted indoor experiments related to ...The microscopic characteristics and mechanical properties of rocks change after the action of acid on deep shale,which affects the fracturing effect.Accordingly,we designed and conducted indoor experiments related to the changes in macro and microscopic characteristics after the interaction of acid with the shale of Wujiaping Formation,based on which the characteristic law of fracture volume modification after acid fracturing was studied using numerical simulation.The results demonstrate that the pores and fractures are enlarged and the structure is significantly loosened after the acid immersion.And a 15%concentration of hydrochloric acid can effectively dissolve shale.Furthermore,the degree of acid-etching reaction is highly variable because of the different carbonate content,which reveals the strong inhomogeneity of the shale system in the Wujiaping Group reservoir section.After the acid interacted with the shale rock samples,the triaxial compressive strength,elastic modulus,and Poisson’s ratio of shale decreased.Moreover,the evaluation of the effect after acid fracturing simulated by fracturing software revealed that the smaller the value of elastic modulus in shale-based reservoirs,the more favorable the fracture volume modification.This discovery not only provides a theoretical basis for the expansion and extension patterns of acid-fracturing in carbonaceous shale formations but also offers research methods and theoretical insights for the fundamental exploration of other deep-seated oil and gas resources.展开更多
Piezoelectric materials are capable of actuation and sensing and have been used in a wide variety of smart devices and structures.Active fiber composite and macro fiber composite are newly developed types of piezoelec...Piezoelectric materials are capable of actuation and sensing and have been used in a wide variety of smart devices and structures.Active fiber composite and macro fiber composite are newly developed types of piezoelectric composites,and show superior properties to monolithic piezoelectric wafer due to their distinctive structures.Numerous work has focused on the performance prediction of the composites by evaluation of structural parameters and properties of the constituent materials with analytical and numerical methods.Various applications have been explored for the piezoelectric fiber composites,including vibration and noise control,health monitoring,morphing of structures and energy harvesting,in which the composites play key role and demonstrate the necessity for further development.展开更多
基金Project(52225403)supported by the National Natural Science Foundation of ChinaProject(2023YFF0615401)supported by the National Key Research and Development Program of China+1 种基金Projects(2023NSFSC0004,2023NSFSC0790)supported by Science and Technology Program of Sichuan Province,ChinaProject(2021-CMCUKFZD001)supported by the Open Fund of State Key Laboratory of Coal Mining and Clean Utilization,China。
文摘Understanding the physical,mechanical behavior,and seepage characteristics of coal under hydro-mechanical coupling holds significant importance for ensuring the stability of surrounding rock formations and preventing gas outbursts.Scanning electron microscopy,uniaxial tests,and triaxial tests were conducted to comprehensively analyze the macroscopic and microscopic physical and mechanical characteristics of coal under different soaking times.Moreover,by restoring the stress path and water injection conditions of the protective layer indoors,we explored the coal mining dynamic behavior and the evolution of permeability.The results show that water causes the micro-surface of coal to peel off and cracks to expand and develop.With the increase of soaking time,the uniaxial and triaxial strengths were gradually decreased with nonlinear trend,and decreased by 63.31%and 30.95%after soaking for 240 h,respectively.Under different water injection pressure conditions,coal permeability undergoes three stages during the mining loading process and ultimately increases to higher values.The peak stress of coal,the deviatoric stress and strain at the permeability surge point all decrease with increasing water injection pressure.The results of this research can help improve the understanding of the coal mechanical properties and seepage evolution law under hydro-mechanical coupling.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2241273,12172034,U20A20390,and 11827803)the Beijing Municipal Natural Science Foundation(Grant No.7212205)+1 种基金the 111 project(Grant No.B13003)the Fundamental Research Funds for the Central Universities.
文摘Accurately characterizing the liver's mechanical properties is of paramount importance for disease diagnosis,treatment,surgical prosthetic modeling,and impact injury dummies.However,due to its inherent biological soft tissue nature,the characterization of mechanical behavior varies across testing methods and sample types.In this study,we employed transmission electron microscope and Micro CT to observe the morphology of the marginal and center of rat livers and conducted macroscopic mechanical tests to characterize their elasticity and viscoelasticity.The results revealed that the central region displayed higher metabolic levels,elongated mitochondria,and an abundance of rough endoplasmic reticulum at the microscale.At the mesoscale,larger diameter portal veins were mainly distributed in the central region,while smaller diameter arteries were predominantly located at the periphery.At the macroscale,under a strain rate of 0.0167 s^(-1),no significant differences were observed in the elastic properties between the two regions.However,as the strain rate increased up to 0.167 s^(-1),the central region displayed higher porosity,resulting in reduced liquid loss,increased hardness,and higher viscosity compared to the periphery.Consequently,the liver demonstrated overall heterogeneity,with isotropic models suitable for the peripheral region,while more intricate models may be required to capture the complexity of the central region with its intricate vasculature.
文摘Plate structures are employed as important structural components in many engineering applications. Hence, assessing the structural conditions of in-service plate structures is critical to monitoring global structural health. Modal curvature-based damage detection techniques have recently garnered considerable attention from the research community, and have become a promising vibration-based structural health monitoring solution. However, computing errors arise when calculating modal curvatures from lateral mode shapes, which result from unavoidable measurement errors in the mode shapes as identified from lateral vibration signals; this makes curvature-based algorithms that use a lateral measurement only theoretically feasible, but practically infeasible. Therefore, in this study, long-gauge fiber Bragg grating strain sensors are employed to obtain a modal curvature without a numerical differentiation procedure in order to circumvent the computing errors. Several damage indices based on modal curvatures that were developed to locate beam damage are employed. Both numerical and experimental studies are performed to validate the proposed approach. However, although previous studies have reported relative success with the application of these damage indices on a simple beam, only one damage index demonstrated the capability to locate damage when the stiffness of the local region changed near the sensor.
文摘Plasma electrolytic oxidation(PEO)coatings were prepared on Al−Mg laminated macro composites(LMCs)using both unipolar and bipolar waveforms in an appropriate electrolyte for both aluminum and magnesium alloys.The techniques of FESEM/EDS,grazing incident beam X-ray diffraction(GIXRD),and electrochemical methods of potentiodynamic polarization and electrochemical impedance spectroscopy(EIS)were used to characterize the coatings.The results revealed that the coatings produced using the bipolar waveform exhibited lower porosity and higher thickness than those produced using the unipolar one.The corrosion performance of the specimens’cut edge was investigated using EIS after 1,8,and 12 h of immersion in a 3.5 wt.%NaCl solution.It was observed that the coating produced using the bipolar waveform demonstrated the highest corrosion resistance after 12 h of immersion,with an estimated corrosion resistance of 5.64 kΩ·cm^(2),which was approximately 3 times higher than that of the unipolar coating.Notably,no signs of galvanic corrosion were observed in the LMCs,and only minor corrosion attacks were observed on the magnesium layer in some areas.
基金funded by National Key R&D Program of China(Grant No.2023YFC3007001)Beijing Natural Science Foundation(Grant No.8244053)China Postdoctoral Science Foundation(Grant No.2024M754065).
文摘The mechanical behavior of cohesive soil is sensitized to drying-wetting cycles under confinements.However,the hydromechanical coupling effect has not been considered in current constitutive models.A macro-micro analysis scheme is proposed in this paper to investigate the soil deformation behavior under the coupling of stress and drying-wetting cycles.A new device is developed based on CT(computerized tomography)workstation to apply certain normal and shear stresses on a soil specimen during drying-wetting cycles.A series of tests are conducted on a type of loess with various coupling of stress paths and drying-wetting cycles.At macroscopic level,stress sensor and laser sensor are used to acquire stress and strain,respectively.The shear and volumetric strain increase during the first few drying-wetting cycles and then become stable.The increase of the shear stress level or confining pressure would cause higher increase rate and the value of shear strain in the process of drying-wetting cycles.At microscopic level,the grayscale value(GSV)of CT scanning image is characterized as the proportion of soil particles to voids.A fabric state parameter is proposed to characterize soil microstructures under the influence of stress and drying-wetting cycle.Test results indicate that the macroand micro-responses show high consistence and relevance.The stress and drying-wetting cycles would both induce collapse of the soil microstructure,which dominants degradation of the soil mechanical properties.The evolution of the macro-mechanical property of soil exhibits a positive linear relationship with the micro-evolution of the fabric state parameter.
文摘Extensive research has been conducted on remaining oil in the Daqing Oilfield during high water cuts’late stage,but few studies have offered multi-level analyses from both macro and micro perspectives for remaining oil under varying formation conditions and displacement methods.This article focuses on the remaining oil in the S,P,and G reservoirs of Daqing Oilfield by employing the frozen section analysis method on the cores from the S,P,and G oil layers.The research identifies patterns among them,revealing that the Micro Remaining Oil types in these cores primarily include pore surface thin film,corner,throat,cluster,intergranular adsorption,and particle adsorption.Among these,intergranular adsorption contains the highest amount of remaining oil(the highest proportion reaches 60%)and serves as the main target for development potential.The overall distribution pattern of the Micro Remaining Oil in the S,P,and G oil layers shows that as flooding intensity increases,the amount of free-state remaining oil gradually decreases,while bound-state remaining oil gradually increases.The study also examines eight typical coring wells for macroscopic remaining oil,finding four main types in the reservoir:interlayer difference,interlayer loss,interlayer interference,and injection-production imperfect types.Among these,the injection-production imperfect type has the highest remaining oil content and is the primary target for development potential.Analyzing the reservoir utilization status and oil flooding efficiency reveals that as water flooding intensifies,the oil displacement efficiency of the oil layer gradually decreases,while the efficiency of oil layer displacement improves.Strongly flooded cores exhibit less free-state remaining oil than weakly flooded cores,making displacement more challenging.This study aims to provide a foundation and support for the development of remaining oil in the S,P,and G oil layers.
基金Supported by the Guangdong Special Support Program for Key Talents Team Program(No.2019BT02H594)the PI Project of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2021GD0810)the Major Project of National Social Science Foundation of China(No.21ZDA097)。
文摘A massive amount of plastic waste has presented an immense management challenge.This escalating ecological damage,coupled with the detrimental effects of plastics infiltrating the marine food web,poses a significant threat to human livelihoods.To combat this,there is a call for the development of plastic detection algorithms using remote sensing data.Here we tested a new index,referred to index_(MP),to detect clusters of floating macro plastics in the ocean using satellite imagery.The index_(MP)was applied to convolution high-pass filtered(3×3)Sentinel 2 Level 1 C images,showing the potential to reduce atmospheric interference and enhance the object edges,thereby improving the clarity of detection.In the analysis,we used three scatter plots to identify and assess plastic pixels.To differentiate the common features of plastic from non-plastic objects,the Sentinel 2 bands 5,8,and 9 were plotted against index_(MP)calculated and convolution high-pass filtered Level 1 C(CHPIC)images.The plastic pixels,clustering in the three scatter plots,showed positive‘X’,i.e.,CHPIC image value and‘Y’,i.e.,each band 5,8,and 9 reflectance values,along with a CHPIC image value exceeding 0.05.Using the index_(MP)and scatter plot analysis,we identified plastic pixels containing 14%or more plastic bottles.Detection of other types of plastics,such as fishing nets and plastic bags,required pixel proportions greater than 50%.Hence,plastic bottles were notably responsive even at a low pixel fraction.We further explored the classification of plastic and non-plastic objects by analyzing reed(plant)pixels;the differentiation between plastic and reed was conducted in the band 5 and 9 scatter plots.
文摘Deep Underground Science and Engineering(DUSE)is pleased to release this issue with feature articles reporting the advancement in several research topics related to deep underground.This issue contains one perspective article,two review articles,six research articles,and one case study article.These articles focus on underground energy storage,multiscale modeling for correlation between micro-scale damage and macro-scale structural degradation,mineralization and formation of gold mine,interface and fracture seepage,experimental study on tunnel-sand-pile interaction,and high water-content materials for deep underground space backfilling,analytical solutions for the crack evolution direction in brittle rocks,and a case study on the squeezing-induced failure in a water drainage tunnel and the rehabilitation measures.
基金Project supported by the National Natural Science Foundation of China(Nos.12072003 and 12372003)Beijing Natural Science Foundation of China(No.1222001)。
文摘Owing to their high flexibility and directional actuation capabilities,macro fiber composites(MFCs)have attracted significant attention for the active control of structures,especially in the nonlinear vibration suppression applications for large-scale flexible structures.In this paper,an MFC-based self-feedback system is introduced for the active control of geometrically nonlinear steady-state forced vibrations in functionally graded carbon nanotube reinforced composite(FG-CNTRC)plates subject to transverse mechanical loads.Based on the first-order shear deformation theory and the von Kármán nonlinear strain-displacement relationship,the nonlinear vibration control equations of the plate with MFC sensor and actuator layers are derived by Hamilton's principle.These equations are discretized by the finite element method(FEM),and solved by the Newton-Raphson and direct iterative methods.A velocity feedback control algorithm is introduced,and the effects of the control gain and the MFC actuator position on the nonlinear vibration active control effectiveness are analyzed.Additionally,a nonlinear resonance analysis is carried out,considering the effects of carbon nanotube(CNT)volume fraction and distribution type.The results indicate that the intrinsic characteristics of the structures significantly influence the vibration behavior.Furthermore,the appropriate selections of control gain and MFC position are crucial for the effective active control of the structures.The present work provides a promising route of the active and efficient nonlinear vibration suppression for various thin-walled structures.
基金the National Natural Science Foundation of China(Nos.52374147,42372328,and U23B2091)National Key Research and Development Program of China(No.2023YFC3804200)Xinjiang Uygur Autonomous Region Science and Technology Major Program(No.2023A01002).
文摘Underground pumped storage power plant(UPSP)is an innovative concept for space recycling of abandoned mines.Its realization requires better understanding of the dynamic performance and durability of reservoir rock.This paper conducted ultrasonic detection,split Hopkinson pressure bar(SHPB)impact,mercury intrusion porosimetry(MIP),and backscatter electron observation(BSE)tests to investigate the dynamical behaviour and microstructure of sandstone with cyclical dry-wet damage.A coupling FEM-DEM model was constructed for reappearing mesoscopic structure damage.The results show that dry-wet cycles decrease the dynamic compressive strength(DCS)with a maximum reduction of 39.40%,the elastic limit strength is reduced from 41.75 to 25.62 MPa.The sieved fragments obtain the highest crack growth rate during the 23rd dry-wet cycle with a predictable life of 25 cycles for each rock particle.The pore fractal features of the macropores and micro-meso pores show great differences between the early and late cycles,which verifies the computational statistics analysis of particle deterioration.The numerical results show that the failure patterns are governed by the strain in pre-peak stage and the shear cracks are dominant.The dry-wet cycles reduce the energy transfer efficiency and lead to the discretization of force chain and crack fields.
文摘Scientists and engineers are looking forward to new manufacturing technologies to realize the integrated fabrication of macro shape and microstructure for the components with a short production chain, which can also save materials and reduce energy consumption. Additive manufacturing (AM) technology is a new fabrication pattern with a character of a lay-by-lay material deposition. The components are fabricated in a bottom-up way, from points, lines, to layers and volume, which provided a capability to solve the impossible integrated fabrication problem for micro- and macro-structure by using conventional manufacturing technologies. Thus, based on integrated fabrication of micro- and macro- structures, research team in Xi’an Jiaotong University has been focusing on technological innovations and applications of advanced additive manufacturing technologies. Novel additive manufacturing principles have been proposed and explored, by which new AM processes and equipment for met- als, composites, ceramics, and biomaterials have been developed to support the industrial applications. Additive manufacturing and cutting-edge applications of advanced composite structure, metamaterials, bio-implants, and monocrystal alloy components have been investigated to push the new development of integrated fabrication of micro- and macro- structures.
基金Project supported by the National Science and Technology Major Project of China(Grant No.2020AAA0109003)。
文摘The precise compact modeling of magnetic devices is pivotal for the integrated design of spin-transfer torque magnetic tunnel junction(STT-MTJ)in conjunction with CMOS circuitry.This work presents a macro model for an STT-MTJ which is compatible with SPICE simulation platforms.The model accurately replicates the electrical performance of the MTJ,encompassing the resistance-voltage characteristics and the pulse-width-dependent state switching behavior,and is validated with various experimental data.Additionally,the impact of process variations,particularly those affecting the MTJ diameter and barrier thickness is investigated and summarized in a corner model.Monte Carlo simulations demonstrate that our adaptable and streamlined model can be efficiently incorporated into the design of integrated circuits.
文摘Immersion of scaffolds in Simulated Body Fluid(10SBF)is a standardized method for evaluating their bioactivity,simulating in vivo conditions where apatite deposits can be formed on the surface of scaffold,facilitating bone integration and ensuring their suitability for bone implant purposes,ultimately contributing to long-term implant success.The effect of apatite deposition on bioactivity and cell behavior of TiO_(2)scaffolds was studied.Scaffolds were soaked in 10SBF for different durations to form HAP layer on their surface.The results proved the development of a hydroxyapatite film resembling the mineral composition of bone Extracellular Matrix(ECM)on the TiO_(2)scaffolds.The XRD test findings showed the presence of hydroxyapatite layer similar to bone at the depth of 10 nm.A decrease in the specific surface area(18.913 m^(2)g^(−1)),the total pore volume(0.045172 cm^(3)g^(−1)(at p/p0=0.990)),and the mean pore diameter(9.5537 nm),were observed by BET analysis which confirmed the formation of the apatite layer.It was found that titania scaffolds with HAP coating promoted human osteosarcoma bone cell(MG63)cell attachment and growth.It seems that immersing the scaffolds in 10SBF to form HAP coating before utilizing them for bone tissue engineering applications might be a good strategy to promote bioactivity,cell attachment,and implant fixation.
基金This study is supported by a Scientific Research Project of Sinopec(Program No.P21087-2)the Open Fund of Key Laboratory of Marine Oil&Gas Reservoirs Production,Sinopec(Grant No.33550000-22-FW2099-0004).
文摘The microscopic characteristics and mechanical properties of rocks change after the action of acid on deep shale,which affects the fracturing effect.Accordingly,we designed and conducted indoor experiments related to the changes in macro and microscopic characteristics after the interaction of acid with the shale of Wujiaping Formation,based on which the characteristic law of fracture volume modification after acid fracturing was studied using numerical simulation.The results demonstrate that the pores and fractures are enlarged and the structure is significantly loosened after the acid immersion.And a 15%concentration of hydrochloric acid can effectively dissolve shale.Furthermore,the degree of acid-etching reaction is highly variable because of the different carbonate content,which reveals the strong inhomogeneity of the shale system in the Wujiaping Group reservoir section.After the acid interacted with the shale rock samples,the triaxial compressive strength,elastic modulus,and Poisson’s ratio of shale decreased.Moreover,the evaluation of the effect after acid fracturing simulated by fracturing software revealed that the smaller the value of elastic modulus in shale-based reservoirs,the more favorable the fracture volume modification.This discovery not only provides a theoretical basis for the expansion and extension patterns of acid-fracturing in carbonaceous shale formations but also offers research methods and theoretical insights for the fundamental exploration of other deep-seated oil and gas resources.
基金Project(51072235) supported by the National Natural Science Foundation of ChinaProject(11JJ1008) supported by the Natural Science Foundation of Hunan Province,China+2 种基金Project(20110162110044) supported by the PhD Program Foundation of Ministry of Education of ChinaProject(7433001207) supported by Hunan Provincial Innovation Foundation for Postgraduate,ChinaProject(2001JF3215) supported by Hunan Provincial Science and Technology Plan,China
文摘Piezoelectric materials are capable of actuation and sensing and have been used in a wide variety of smart devices and structures.Active fiber composite and macro fiber composite are newly developed types of piezoelectric composites,and show superior properties to monolithic piezoelectric wafer due to their distinctive structures.Numerous work has focused on the performance prediction of the composites by evaluation of structural parameters and properties of the constituent materials with analytical and numerical methods.Various applications have been explored for the piezoelectric fiber composites,including vibration and noise control,health monitoring,morphing of structures and energy harvesting,in which the composites play key role and demonstrate the necessity for further development.
