In industrial processes,there exist faults that have complex effect on process variables.Complex and simple faults are defined according to their effect dimensions.The conventional approaches based on structured resid...In industrial processes,there exist faults that have complex effect on process variables.Complex and simple faults are defined according to their effect dimensions.The conventional approaches based on structured residuals cannot isolate complex faults.This paper presents a multi-level strategy for complex fault isolation.An extraction procedure is employed to reduce the complex faults to simple ones and assign them to several levels.On each level,faults are isolated by their different responses in the structured residuals.Each residual is obtained insensitive to one fault but more sensitive to others.The faults on different levels are verified to have different residual responses and will not be confused.An entire incidence matrix containing residual response characteristics of all faults is obtained,based on which faults can be isolated.The proposed method is applied in the Tennessee Eastman process example,and the effectiveness and advantage are demonstrated.展开更多
The influences of biological,chemical,and flow processes on soil structure through microbially induced carbonate precipitation(MICP)are not yet fully understood.In this study,we use a multi-level thresholding segmenta...The influences of biological,chemical,and flow processes on soil structure through microbially induced carbonate precipitation(MICP)are not yet fully understood.In this study,we use a multi-level thresholding segmentation algorithm,genetic algorithm(GA)enhanced Kapur entropy(KE)(GAE-KE),to accomplish quantitative characterization of sandy soil structure altered by MICP cementation.A sandy soil sample was treated using MICP method and scanned by the synchrotron radiation(SR)micro-CT with a resolution of 6.5 mm.After validation,tri-level thresholding segmentation using GAE-KE successfully separated the precipitated calcium carbonate crystals from sand particles and pores.The spatial distributions of porosity,pore structure parameters,and flow characteristics were calculated for quantitative characterization.The results offer pore-scale insights into the MICP treatment effect,and the quantitative understanding confirms the feasibility of the GAE-KE multi-level thresholding segmentation algorithm.展开更多
Improving wound healing efficiency is a key issue for high performance dressings.The surface topology of fibers in wound dressings plays an important role in regulating cell behaviors during the regeneration.Herein,a ...Improving wound healing efficiency is a key issue for high performance dressings.The surface topology of fibers in wound dressings plays an important role in regulating cell behaviors during the regeneration.Herein,a polycaprolactone(PCL)scaffold with a shish-kebab structure was prepared by electrospinning and solution-induced crystallization.L929 cells were used to investigate the behavior of fibroblasts on the multi-level microfiber.The results showed that the shish-kebab fiber-based scaffold enhanced the cell proliferation when compared with the normal fiber and the fiber with a porous structure.Protein absorption,cell adhesive force,and cell modulus also increased by the shish-kebab fiber.The shish-kebab fiber-based scaffold with improved fibroblast-regulation ability can be applied in rapid wound healing.展开更多
Under saturation dosage of all kinds of SP, the free water amount was examined by centrifuge. The distribution of solution and flocculation microstructures in fresh cement paste was observed in three- dimensional spac...Under saturation dosage of all kinds of SP, the free water amount was examined by centrifuge. The distribution of solution and flocculation microstructures in fresh cement paste was observed in three- dimensional space by confocal laser scanning microscope（CLSM）. Results indicate that SP can increase the free water amount by destroying the flocculated cement particle structure and different free water amount is released by different kinds of SP. The changes of the size of flocculation structures and the dispersion of solution were obviously detected with confocal laser scanning microscope： the size of flocculation structures was smaller and more dispersed in fresh cement paste with polycarboxylate superplasticizer, but the size of flocculation structures was bigger and cannot be dispersed uniformly in fresh cement paste with others SP. The multi- level flocculation structures theoretical model of fresh cement paste was then set up. The theory indicates that different kinds of SP with different dispersion strength will open the flocculation structures at different levels, which in turn present different water reducing rate.展开更多
Weight reduction has attracted much attention among ship designers and ship owners.In the present work,based on an improved bi-directional evolutionary structural optimization(BESO) method and surrogate model method,w...Weight reduction has attracted much attention among ship designers and ship owners.In the present work,based on an improved bi-directional evolutionary structural optimization(BESO) method and surrogate model method,we propose a hybrid optimization method for the structural design optimization of beam-plate structures,which covers three optimization levels:dimension optimization,topology optimization and section optimization.The objective of the proposed optimization method is to minimize the weight of design object under a group of constraints.The kernel optimization procedure(KOP) uses BESO to obtain the optimal topology from a ground structure.To deal with beam-plate structures,the traditional BESO method is improved by using cubic box as the unit cell instead of solid unit to construct periodic lattice structure.In the first optimization level,a series of ground structures are generated based on different dimensional parameter combinations,the KOP is performed to all the ground structures,the response surface model of optimal objective values and dimension parameters is created,and then the optimal dimension parameters can be obtained.In the second optimization level,the optimal topology is obtained by using the KOP according to the optimal dimension parameters.In the third optimization level,response surface method(RSM) is used to determine the section parameters.The proposed method is applied to a hatch cover structure design.The locations and shapes of all the structural members are determined from an oversized ground structure.The results show that the proposed method leads to a greater weight saving,compared with the original design and genetic algorithm(GA) based optimization results.展开更多
In some competitions the rules clearly state that all participating cars must install a restrictor valve structure in the intake system of the engine.The intake air volume of the engine is considerably affected due to...In some competitions the rules clearly state that all participating cars must install a restrictor valve structure in the intake system of the engine.The intake air volume of the engine is considerably affected due to the existence of such a valve.Indeed,a small interface diameter through which gas flows can lead to considerable flow resistance and loss.In this study,a four-cylinder engine for FSC racing is analyzed using a combined method based on numerical simulation and experiments.The analysis reveals that the main factors affecting the intake air volume are the intake manifold and the volume of the resonance chamber.The influence of such factors is assessed using a single variable method and an optimal model and parameters are obtained accordingly.Comparison of different results show that the maximum torque for the optimized system is increased from the original 42.6 N·m to 46.9 N·m,thus demonstrating an increase of 10.6%.These findings provide a theoretical basis for the design of the intake system and the improvement of engine performance.展开更多
Based on forward modeling of detachment fold, this study presents a method to analyze multi-level detachment structures and identify the authenticity of deep-seated anticlines using time-domain seismic section. The st...Based on forward modeling of detachment fold, this study presents a method to analyze multi-level detachment structures and identify the authenticity of deep-seated anticlines using time-domain seismic section. The steps include the conversion of the time-migrated seismic image into depth domain image using a constant velocity field, structural interpretation of the depth seismic image, measurement of each structural relief area and each height above reference level, plotting of area-height relationship chart with piecewise fitting etc. The area-depth correlation can help the division of structural sequences, the definition of detachment levels, the calculation of the tectonic shortening, and the identification of deep-seated structure. The segment area-height relationship is a feature of multi-level detachment structures, while little or no linear correlation between area and height is an indicator of non-deformation or pseudo-anticline. Regardless of the uncertainty of area-height relationship, the segment slopes will correspond to the differential shortenings of multi-level detachments, the intersection between adjacent segments will give the height of detachment surface above reference level and then help define the detachment level in original time-domain seismic section. This method can make use of time-domain seismic data to determine the geologic structure of complicated structure areas and assess risks of deep exploration targets. It has achieved good results in southern Junggar and eastern Sichuan areas.展开更多
The flow structure around the intake of a vertical pump is investigated experimentally and numerically in order to obtain a guideline in designing the optimum shape of the intake of vertical pumps, in which their inst...The flow structure around the intake of a vertical pump is investigated experimentally and numerically in order to obtain a guideline in designing the optimum shape of the intake of vertical pumps, in which their installation area is demanded to be minimum without losing the high performance. We concentrate our attention on the expansion ratio of the intake as a representative characteristic of the shape of the pumps and investigate the effect of the expansion ratio on pump performance. It is concluded that the optimum expansion ratio ranges in 1.1-1.2 if we take into consideration that the area needed for the installation of the pump should be minimum.展开更多
The northwestern Sichuan region has experienced multi-stage tectonic evolution including marine cratonic basin from the Sinian to the Middle Triassic and intra-continental basin from the Late Triassic to the Cenozoic....The northwestern Sichuan region has experienced multi-stage tectonic evolution including marine cratonic basin from the Sinian to the Middle Triassic and intra-continental basin from the Late Triassic to the Cenozoic. Several regional tectonic activities caused complicated stratigraphic distribution and structural deformations in the deep-buried layers. During the key tectonic periods, some characteristic sedimentary and deformation structures were formed, including the step-shaped marginal carbonate platform of Dengying Formation, the western paleo-high at the end of Silurian, and the passive continental margin of the Late Paleozoic–Middle Triassic. The Meso-Cenozoic intra-continental compressional tectonic processes since the Late Triassic controlled the formation of complex thrusting structures surrounding and inside the northwestern basin. The northern Longmenshan fold-thrust belt has a footwall in-situ thrust structure,which is controlled by two sets of detachments in the Lower Triassic and Lower Cambrian and presents as a multi-level deformation structure with the shallow folds, the middle thin-skin thrusts and the deeper basement-involved folds. The thrust belt in front of the Micangshan Mountain shows a double-layer deformation controlled by the Lower Triassic salt detachment, which is composed by the upper monocline and deep-buried imbricate thrust structures. The interior of the basin is characterized by several rows of large-scale basement-involved folds with NEE strike direction. From the perspective of structural geology, the favorable exploration reservoirs and belts in northwestern Sichuan have obvious zoning characteristics. The favorable exploration layers of Dengying Formation of Upper Sinian are mainly distributed in the eastern and northern areas of the northwestern Sichuan Basin, in which the Jiulongshan structural belt, Zitong syncline and Yanting slope are the most favorable. The Lower Paleozoic was transformed by Caledonian paleo-uplift and late Cenozoic folding, and the midwest area such as the Zitong syncline is a potential area for hydrocarbon exploration. The favorable part of the Upper Paleozoic is mainly distributed in the northern Longmenshan belt and its frontal area, where the deep-buried thin-skin thrust structures in the footwall are the key exploration targets.展开更多
The fuel delivery laws of horizontal tanks are no longer adequate for efficient supply under complex flight conditions,while the supply characteristics of non-horizontal tanks are not sufficiently explored.In this wor...The fuel delivery laws of horizontal tanks are no longer adequate for efficient supply under complex flight conditions,while the supply characteristics of non-horizontal tanks are not sufficiently explored.In this work,the piston-driven fuel supply devices with external slit-shaped and novel built-in cube-,sphere-,and dome-shaped intakes were selected as the research objects.The conveying sensitivity of devices at different tilt angles was investigated using two-fluid model.The results indicate that as the tilt angle increases from 0◦to 90◦,the fluctuation in mass flow rate of powder under the cube-,sphere-,and dome-shaped intakes increases by about 53.8%,46.6%,and 35.0%,respectively,while the slit-shaped intake decreases by about 1.0%.The gas under the built-in intake migrates from the head of the device to the outlet,while the gas under the external intake is distributed near the wall of the conical convergence section,and the fluctuations in pressure and relative pressure drop of the former are more intense than those of the latter.At varying tilt angles,the area of gas phase under external intake is approximately 15 times that of the built-in.At low tilt angles(0◦and 30◦),the variations in gas-solid velocities and powder concentration are similar for the domeand slit-shaped intakes.As the tilt angle increases,the fluctuation in these two physical quantities in the cubeand sphere-shaped intakes is larger than in other cases.At a high tilt angle(90◦),the built-in cube-shaped intake exhibits the least satisfactory supply performance.展开更多
The development of biochar has triggered a hot-spot in various research fields including agriculture,energy,environment,and materials.Biochar-based materials provide a novel approach against environmental challenging ...The development of biochar has triggered a hot-spot in various research fields including agriculture,energy,environment,and materials.Biochar-based materials provide a novel approach against environmental challenging issues.Considering the rapid development of biochar materials,this review serves as a valuable platform to summarize the recent progress on the theoretical investigation and engineering applications of biochar materials in environmental remediation.For a better understanding of the structure-application relationships,the structural properties of biochar from macroscopic and microscopic aspects are summarized.The multilevel structures including elements,phases,surface chemistry,and molecular are highlighted to elucidate the multi-functional properties of biochars.Sorption,catalysis,redox reaction,and biological activity of biochar are briefly illustrated,which influence the transport,transformation,and removal of organic and inorganic pollutants in the environments.According to the multi-level structures and structure-application relationships of biochar,specific biochar-based materials and devices have been designed for practical environmental application.The important progress on the functionalization and device of biochar-based materials,including magnetic biochars,2D and 3D biochar-based macrostructures,immobilized microorganism on biochar,and biochar-amended biofilters are highlighted.The environmental friendliness and sustainability of biochar-based materials,considering the whole cycle from synthesis to application,are evaluated.展开更多
Optimal design of gas intake in powder fuel supply systems is crucial for performance of aerospace engines.There is little research on the impact of intake structure on powder conveying performance.Three novel interna...Optimal design of gas intake in powder fuel supply systems is crucial for performance of aerospace engines.There is little research on the impact of intake structure on powder conveying performance.Three novel internal intakes were proposed,which are spherical,cube-shaped,and dome-shaped.After validation,CFD simulations demonstrate that fluctuation of mass flow rate of powders in the dome-shaped intake is reduced by about 73.3%compared with the annular external one.Variation trends of phase velocities are similar for the spherical and cube-shaped intakes,while those are similar for the annular external and dome-shaped internal intakes.Fluctuation of area of gas zone for the annular external and spherical internal intakes is larger than that for the cube-shaped and dome-shaped internal intakes.Pressure and relative pressure drop in the fluidization chamber have a stable stage,and fluctuation of relative pressure drop is small when dome-shaped internal intake is used.展开更多
基金Supported by the National Natural Science Foundation of China(60574047)the National High Technology Research and Development Program of China(2007AA04Z168,2009AA04Z154)the Research Fund for the Doctoral Program of Higher Education in China(20050335018)
文摘In industrial processes,there exist faults that have complex effect on process variables.Complex and simple faults are defined according to their effect dimensions.The conventional approaches based on structured residuals cannot isolate complex faults.This paper presents a multi-level strategy for complex fault isolation.An extraction procedure is employed to reduce the complex faults to simple ones and assign them to several levels.On each level,faults are isolated by their different responses in the structured residuals.Each residual is obtained insensitive to one fault but more sensitive to others.The faults on different levels are verified to have different residual responses and will not be confused.An entire incidence matrix containing residual response characteristics of all faults is obtained,based on which faults can be isolated.The proposed method is applied in the Tennessee Eastman process example,and the effectiveness and advantage are demonstrated.
基金supported by the National Natural Science Foundation of China(Grant Nos.42077232 and 42077235)the Key Research and Development Plan of Jiangsu Province(Grant No.BE2022156).
文摘The influences of biological,chemical,and flow processes on soil structure through microbially induced carbonate precipitation(MICP)are not yet fully understood.In this study,we use a multi-level thresholding segmentation algorithm,genetic algorithm(GA)enhanced Kapur entropy(KE)(GAE-KE),to accomplish quantitative characterization of sandy soil structure altered by MICP cementation.A sandy soil sample was treated using MICP method and scanned by the synchrotron radiation(SR)micro-CT with a resolution of 6.5 mm.After validation,tri-level thresholding segmentation using GAE-KE successfully separated the precipitated calcium carbonate crystals from sand particles and pores.The spatial distributions of porosity,pore structure parameters,and flow characteristics were calculated for quantitative characterization.The results offer pore-scale insights into the MICP treatment effect,and the quantitative understanding confirms the feasibility of the GAE-KE multi-level thresholding segmentation algorithm.
基金Fundamental Research Funds for the Central Universities,China(Nos.2232018G-01 and 2232020G-01)Initial Research Funds for Young Teachers of Donghua University,China。
文摘Improving wound healing efficiency is a key issue for high performance dressings.The surface topology of fibers in wound dressings plays an important role in regulating cell behaviors during the regeneration.Herein,a polycaprolactone(PCL)scaffold with a shish-kebab structure was prepared by electrospinning and solution-induced crystallization.L929 cells were used to investigate the behavior of fibroblasts on the multi-level microfiber.The results showed that the shish-kebab fiber-based scaffold enhanced the cell proliferation when compared with the normal fiber and the fiber with a porous structure.Protein absorption,cell adhesive force,and cell modulus also increased by the shish-kebab fiber.The shish-kebab fiber-based scaffold with improved fibroblast-regulation ability can be applied in rapid wound healing.
基金Funded by the National Natural Science Foundation of China(No.50872151)the Outstanding Innovative Talents Program of China University of Mining&Technology(Beijing)(No.00-800015Z637)
文摘Under saturation dosage of all kinds of SP, the free water amount was examined by centrifuge. The distribution of solution and flocculation microstructures in fresh cement paste was observed in three- dimensional space by confocal laser scanning microscope（CLSM）. Results indicate that SP can increase the free water amount by destroying the flocculated cement particle structure and different free water amount is released by different kinds of SP. The changes of the size of flocculation structures and the dispersion of solution were obviously detected with confocal laser scanning microscope： the size of flocculation structures was smaller and more dispersed in fresh cement paste with polycarboxylate superplasticizer, but the size of flocculation structures was bigger and cannot be dispersed uniformly in fresh cement paste with others SP. The multi- level flocculation structures theoretical model of fresh cement paste was then set up. The theory indicates that different kinds of SP with different dispersion strength will open the flocculation structures at different levels, which in turn present different water reducing rate.
基金the National Natural Science Foundation of China(No.51509033)
文摘Weight reduction has attracted much attention among ship designers and ship owners.In the present work,based on an improved bi-directional evolutionary structural optimization(BESO) method and surrogate model method,we propose a hybrid optimization method for the structural design optimization of beam-plate structures,which covers three optimization levels:dimension optimization,topology optimization and section optimization.The objective of the proposed optimization method is to minimize the weight of design object under a group of constraints.The kernel optimization procedure(KOP) uses BESO to obtain the optimal topology from a ground structure.To deal with beam-plate structures,the traditional BESO method is improved by using cubic box as the unit cell instead of solid unit to construct periodic lattice structure.In the first optimization level,a series of ground structures are generated based on different dimensional parameter combinations,the KOP is performed to all the ground structures,the response surface model of optimal objective values and dimension parameters is created,and then the optimal dimension parameters can be obtained.In the second optimization level,the optimal topology is obtained by using the KOP according to the optimal dimension parameters.In the third optimization level,response surface method(RSM) is used to determine the section parameters.The proposed method is applied to a hatch cover structure design.The locations and shapes of all the structural members are determined from an oversized ground structure.The results show that the proposed method leads to a greater weight saving,compared with the original design and genetic algorithm(GA) based optimization results.
基金Guangxi colleges and universities young and middle-aged teachers basic ability improvement project,which is called“Optimization Analysis of Gasoline Engine Performance Based on the Inlet Throttle for FSC Intake System”(No.2018KY0654)。
文摘In some competitions the rules clearly state that all participating cars must install a restrictor valve structure in the intake system of the engine.The intake air volume of the engine is considerably affected due to the existence of such a valve.Indeed,a small interface diameter through which gas flows can lead to considerable flow resistance and loss.In this study,a four-cylinder engine for FSC racing is analyzed using a combined method based on numerical simulation and experiments.The analysis reveals that the main factors affecting the intake air volume are the intake manifold and the volume of the resonance chamber.The influence of such factors is assessed using a single variable method and an optimal model and parameters are obtained accordingly.Comparison of different results show that the maximum torque for the optimized system is increased from the original 42.6 N·m to 46.9 N·m,thus demonstrating an increase of 10.6%.These findings provide a theoretical basis for the design of the intake system and the improvement of engine performance.
基金Supported by the China National Science and Technology Major Project(2016ZX 05003-001)
文摘Based on forward modeling of detachment fold, this study presents a method to analyze multi-level detachment structures and identify the authenticity of deep-seated anticlines using time-domain seismic section. The steps include the conversion of the time-migrated seismic image into depth domain image using a constant velocity field, structural interpretation of the depth seismic image, measurement of each structural relief area and each height above reference level, plotting of area-height relationship chart with piecewise fitting etc. The area-depth correlation can help the division of structural sequences, the definition of detachment levels, the calculation of the tectonic shortening, and the identification of deep-seated structure. The segment area-height relationship is a feature of multi-level detachment structures, while little or no linear correlation between area and height is an indicator of non-deformation or pseudo-anticline. Regardless of the uncertainty of area-height relationship, the segment slopes will correspond to the differential shortenings of multi-level detachments, the intersection between adjacent segments will give the height of detachment surface above reference level and then help define the detachment level in original time-domain seismic section. This method can make use of time-domain seismic data to determine the geologic structure of complicated structure areas and assess risks of deep exploration targets. It has achieved good results in southern Junggar and eastern Sichuan areas.
文摘The flow structure around the intake of a vertical pump is investigated experimentally and numerically in order to obtain a guideline in designing the optimum shape of the intake of vertical pumps, in which their installation area is demanded to be minimum without losing the high performance. We concentrate our attention on the expansion ratio of the intake as a representative characteristic of the shape of the pumps and investigate the effect of the expansion ratio on pump performance. It is concluded that the optimum expansion ratio ranges in 1.1-1.2 if we take into consideration that the area needed for the installation of the pump should be minimum.
基金Supported by the China National Science and Technology Major Project(2016ZX05003-001)PetroChina Science and Technology Project(2016E-0601,2016B-0501)
文摘The northwestern Sichuan region has experienced multi-stage tectonic evolution including marine cratonic basin from the Sinian to the Middle Triassic and intra-continental basin from the Late Triassic to the Cenozoic. Several regional tectonic activities caused complicated stratigraphic distribution and structural deformations in the deep-buried layers. During the key tectonic periods, some characteristic sedimentary and deformation structures were formed, including the step-shaped marginal carbonate platform of Dengying Formation, the western paleo-high at the end of Silurian, and the passive continental margin of the Late Paleozoic–Middle Triassic. The Meso-Cenozoic intra-continental compressional tectonic processes since the Late Triassic controlled the formation of complex thrusting structures surrounding and inside the northwestern basin. The northern Longmenshan fold-thrust belt has a footwall in-situ thrust structure,which is controlled by two sets of detachments in the Lower Triassic and Lower Cambrian and presents as a multi-level deformation structure with the shallow folds, the middle thin-skin thrusts and the deeper basement-involved folds. The thrust belt in front of the Micangshan Mountain shows a double-layer deformation controlled by the Lower Triassic salt detachment, which is composed by the upper monocline and deep-buried imbricate thrust structures. The interior of the basin is characterized by several rows of large-scale basement-involved folds with NEE strike direction. From the perspective of structural geology, the favorable exploration reservoirs and belts in northwestern Sichuan have obvious zoning characteristics. The favorable exploration layers of Dengying Formation of Upper Sinian are mainly distributed in the eastern and northern areas of the northwestern Sichuan Basin, in which the Jiulongshan structural belt, Zitong syncline and Yanting slope are the most favorable. The Lower Paleozoic was transformed by Caledonian paleo-uplift and late Cenozoic folding, and the midwest area such as the Zitong syncline is a potential area for hydrocarbon exploration. The favorable part of the Upper Paleozoic is mainly distributed in the northern Longmenshan belt and its frontal area, where the deep-buried thin-skin thrust structures in the footwall are the key exploration targets.
基金supported by the National Natural Science Foundation of China(grant No.12102161)the Key Research Program of Jiangxi Province,China(grant No.20232BBE50005)the Natural Science Foundation of Jiangxi Province,China(grant No.20224BAB214060).
文摘The fuel delivery laws of horizontal tanks are no longer adequate for efficient supply under complex flight conditions,while the supply characteristics of non-horizontal tanks are not sufficiently explored.In this work,the piston-driven fuel supply devices with external slit-shaped and novel built-in cube-,sphere-,and dome-shaped intakes were selected as the research objects.The conveying sensitivity of devices at different tilt angles was investigated using two-fluid model.The results indicate that as the tilt angle increases from 0◦to 90◦,the fluctuation in mass flow rate of powder under the cube-,sphere-,and dome-shaped intakes increases by about 53.8%,46.6%,and 35.0%,respectively,while the slit-shaped intake decreases by about 1.0%.The gas under the built-in intake migrates from the head of the device to the outlet,while the gas under the external intake is distributed near the wall of the conical convergence section,and the fluctuations in pressure and relative pressure drop of the former are more intense than those of the latter.At varying tilt angles,the area of gas phase under external intake is approximately 15 times that of the built-in.At low tilt angles(0◦and 30◦),the variations in gas-solid velocities and powder concentration are similar for the domeand slit-shaped intakes.As the tilt angle increases,the fluctuation in these two physical quantities in the cubeand sphere-shaped intakes is larger than in other cases.At a high tilt angle(90◦),the built-in cube-shaped intake exhibits the least satisfactory supply performance.
基金This project was supported by the National Natural Science Foundations of China(21621005,and 21537005,21425730)the National Key Technology Research and Development Program of China(2018YFC1800705).
文摘The development of biochar has triggered a hot-spot in various research fields including agriculture,energy,environment,and materials.Biochar-based materials provide a novel approach against environmental challenging issues.Considering the rapid development of biochar materials,this review serves as a valuable platform to summarize the recent progress on the theoretical investigation and engineering applications of biochar materials in environmental remediation.For a better understanding of the structure-application relationships,the structural properties of biochar from macroscopic and microscopic aspects are summarized.The multilevel structures including elements,phases,surface chemistry,and molecular are highlighted to elucidate the multi-functional properties of biochars.Sorption,catalysis,redox reaction,and biological activity of biochar are briefly illustrated,which influence the transport,transformation,and removal of organic and inorganic pollutants in the environments.According to the multi-level structures and structure-application relationships of biochar,specific biochar-based materials and devices have been designed for practical environmental application.The important progress on the functionalization and device of biochar-based materials,including magnetic biochars,2D and 3D biochar-based macrostructures,immobilized microorganism on biochar,and biochar-amended biofilters are highlighted.The environmental friendliness and sustainability of biochar-based materials,considering the whole cycle from synthesis to application,are evaluated.
基金the National Natural Science Foundation of China(grant No.12102161)the Aeronautical Science Foundation of China(grant No.20200001056001).
文摘Optimal design of gas intake in powder fuel supply systems is crucial for performance of aerospace engines.There is little research on the impact of intake structure on powder conveying performance.Three novel internal intakes were proposed,which are spherical,cube-shaped,and dome-shaped.After validation,CFD simulations demonstrate that fluctuation of mass flow rate of powders in the dome-shaped intake is reduced by about 73.3%compared with the annular external one.Variation trends of phase velocities are similar for the spherical and cube-shaped intakes,while those are similar for the annular external and dome-shaped internal intakes.Fluctuation of area of gas zone for the annular external and spherical internal intakes is larger than that for the cube-shaped and dome-shaped internal intakes.Pressure and relative pressure drop in the fluidization chamber have a stable stage,and fluctuation of relative pressure drop is small when dome-shaped internal intake is used.
