Particles,including soot,aerosol and ash,usually exist as fractal aggregates.The radiative properties of the particle fractal aggregates have a great influence on studying the light or heat radiative transfer in the p...Particles,including soot,aerosol and ash,usually exist as fractal aggregates.The radiative properties of the particle fractal aggregates have a great influence on studying the light or heat radiative transfer in the particle medium.In the present work,the performance of the single-layer inversion model and the double-layer inversion model in reconstructing the geometric structure of particle fractal aggregates is studied based on the light reflectancetransmittance measurement method.An improved artificial fish-swarm algorithm(IAFSA)is proposed to solve the inverse problem.The result reveals that the accuracy of double-layer inversion model is more satisfactory as it can provide more uncorrelated information than the single-layer inversion model.Moreover,the developed IAFSA show higher accuracy and better robustness than the original artificial fish swarm algorithm(AFSA)for avoiding local optimization problems effectively.As a whole,the present work supplies a useful kind of measurement technology for predicting geometrical morphology of particle fractal aggregates.展开更多
A novel and simple strategy of morphology-controlled Sr Ti O3（ST） micro-scale particle synthesis by the flux method is reported. Systematic experiments are designed to realize the tunable morphologies of the particl...A novel and simple strategy of morphology-controlled Sr Ti O3（ST） micro-scale particle synthesis by the flux method is reported. Systematic experiments are designed to realize the tunable morphologies of the particles when the flux salt,sintering process, and the precursors are changed. The ST plates can be synthesized by plate-like Bi4Ti3O12（BIT） precursors in Na Cl flux. However, the as-synthesized Bi4Ti3O12 grains transform into reticular particles and finally into rods at higher temperature in Na Cl and KCl compounds. Besides, cubic ST particles are also prepared using different precursors as a comparative experiment. This study provides a strategy for further investigations in designing the morphology-controlled particles and efficient anisotropic materials of perovskite structure such as ferroelectric and photocatalyst.展开更多
The discharge morphology of pulsed dielectric barrier discharge(PDBD) plays important roles in its applications. Here, we systematically investigated the effects of the voltage amplitude,discharge gap, and O_(2)conten...The discharge morphology of pulsed dielectric barrier discharge(PDBD) plays important roles in its applications. Here, we systematically investigated the effects of the voltage amplitude,discharge gap, and O_(2)content on the PDBD morphology, and revealed the possible underlying mechanism of the U-shaped formation. First, the morphological evolution under different conditions was recorded. A unique U-shaped region appears in the middle edge region when the gap is larger than 2 mm, while the entire discharge region remains columnar under a 2 mm gap in He PDBD. The width of the discharge and the U-shaped region increase with the increase in voltage, and decrease with the increase of the gap and O_(2)content. To explain this phenomenon,a two-dimensional symmetric model was developed to simulate the spatiotemporal evolution of different species and calculate the electric thrust. The discharge morphology evolution directly corresponds to the excited-state atomic reduction process. The electric thrust on the charged particles mainly determines the reaction region and strongly influences the U-shaped formation.When the gap is less than 2 mm, the electric thrust is homogeneous throughout the entire region,resulting in a columnar shape. However, when the gap is larger than 2 mm or O_(2)is added, the electric thrust in the edge region becomes greater than that in the middle, leading to the U-shaped formation. Furthermore, in He PDBD, the charged particles generating electric thrust are mainly electrons and helium ions, while in He/O_(2)PDBD those that generate electric thrust at the outer edge of the electrode surface are mainly various oxygen-containing ions.展开更多
A covalent organic frameworks(COFs)material with regular pores and stable structure can be used as the host of lithium-sulfur batteries to improve battery kinetics and polysulfides conversion.Herein,we designed and sy...A covalent organic frameworks(COFs)material with regular pores and stable structure can be used as the host of lithium-sulfur batteries to improve battery kinetics and polysulfides conversion.Herein,we designed and synthesized two kinds of rod-liked bulk COFs by adjusting different pore sizes(COF-BTD and COF-TFB),unfortunately,the active sites masking and sluggish kinetics have not met our expectations.Generally,the available layered COFs prepared from mechanochemical can expose abundant active sites and favorable kinetics than bulk COFs.Thus,simple mechanical ball milling is applied to activate the above COFs(M-COFs group).It is worth noting that layered R-COF-BTD is directly synthesized from rod-liked precursors by simple morphological reconstruction.A series of characterization methods are used to systematically explore the advantages of the group of M-COFs@S electrodes in the cycling process,including the effects of specific morphology on the kinetics and transformation of polysulfides.Our research provides a feasible plan for the development and selection of the host material of lithium-sulfur batteries.展开更多
Interparticle adhesion force has a controlling effect on the physical and mechanical properties of planetary regolith and rocks.The current research on the adhesion force of planetary regolith and rock particles has b...Interparticle adhesion force has a controlling effect on the physical and mechanical properties of planetary regolith and rocks.The current research on the adhesion force of planetary regolith and rock particles has been primarily based on the assumption of smooth spherical particles to calculate the intergranular adhesion force;this approach lacks consideration for the adhesion force between irregular shaped particles.In our study,an innovative approach was established to directly measure the adhesion force between the arbitrary irregular shaped particles;the probe was modified using simulated lunar soil particles that were a typical representation of planetary regolith.The experimental results showed that for irregular shaped mineral particles,the particle size and mineral composition had no significant influence on the interparticle adhesion force;however,the complex morphology of the contact surface predominantly controlled the adhesion force.As the contact surface roughness increased,the adhesion force gradually decreased,and the rate of decrease gradually slowed;these results were consistent with the change trend predicted via the theoretical models of quantum electrodynamics.Moreover,a theoretical model to predict the adhesion force between the irregular shaped particles was constructed based on Rabinovich’s theory,and the prediction results were correlated with the experimental measurements.展开更多
The particle morphology determined by the sintering process is the director factor affecting the electrochemical performance of Ni-rich NMC cathode materials.To prepare the ideal NMC particles,it is of great significa...The particle morphology determined by the sintering process is the director factor affecting the electrochemical performance of Ni-rich NMC cathode materials.To prepare the ideal NMC particles,it is of great significance to understand the morphological changes during sintering process.In this work,the morphology evolution of LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811)synthesis at temperature ranging from 300–1080℃were observed by in situ SEM.The uniform mixture of spherical Ni_(0.8)Mn_(0.1)Co_(0.1)(OH)_(2)precursor and lithium sources(LiOH)was employed by high temperature solid-state process inside the SEM,which enables us to observe morphology changes in real time.The results show that synthetic reaction of LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)usually includes three processes:the raw materials’dehydration,oxidation,and combination,accompanied by a significant reduction in particle size,which is important reference to control the synthesis temperature.As heating temperature rise,the morphology of mixture also changed from flake to brick-shaped.However,Ni nanoparticle formation is apparent at higher temperature~1000℃,suggesting a structural transformation from a layered to a rock-salt-like structure.Combining the in-situ observed changes in size and morphology,and with the premise of ensuring the morphology change from flakes to bricks,reducing the sintering temperature as much as possible to prevent excessive reduction in particle size and layered to a rock-salt structure transformation is recommended for prepare ideal NMC particles.展开更多
Purpose:Measuring the exact technology complementarity between different institutions is necessary to obtain complementary technology resources for R&D cooperation.Design/methodology/approach:This study constructs...Purpose:Measuring the exact technology complementarity between different institutions is necessary to obtain complementary technology resources for R&D cooperation.Design/methodology/approach:This study constructs a morphology-driven method for measuring technology complementarity,taking medical field as an example.First,we calculate semantic similarities between subjects(S and S)and action-objects(AO and AO)based on the Metathesaurus,forming clusters of S and AO based on a semantic similarity matrix.Second,we identify key technology issues and methods based on clusters of S and AO.Third,a technology morphology matrix of several dimensions is constructed using morphology analysis,and the matrix is filled with subjects-action-objects(SAO)structures according to corresponding key technology issues and methods for different institutions.Finally,the technology morphology matrix is used to measure the technology complementarity between different institutions based on SAO.Findings:The improved technology complementarity method based on SAO is more of a supplementary and refined framework for the traditional IPC method.Research limitations:In future studies we will reprocess and identify the SAO structures which were not in the technology morphology matrix,and find other methods to characterize key technical issues and methods.Furthermore,we will add the comparison between proposed method and traditional and mostly used complementarity measurement method based on industry chain and industry code.Practical implications:This study takes medical field as an example.The morphology-driven method for measuring technology complementarity can be migrated and applied for any given field.Originality/value:From the perspective of complementary technology resources,this study develops and tests a more accurate morphology-driven method for technology complementarity measurement.展开更多
Developing high-performance non-precious metal electrocatalysts for oxygen reduction reaction(ORR)is crucial for the commercialization of fuel cells and metal-air batteries.However,doped carbon-based materials only sh...Developing high-performance non-precious metal electrocatalysts for oxygen reduction reaction(ORR)is crucial for the commercialization of fuel cells and metal-air batteries.However,doped carbon-based materials only show good ORR activity in alkaline medium,and become less effective in acidic environment.We believe that an appropriate combination of both ionic and electronic transport path,and well dopant distribution of doped carbon-based materials would help to realize high ORR performance un-der both acidic and alkaline cond让ions.Accordingly,a nitrogen and sulfur co-doped carbon framework with hierarchical through-hole structure is fabricated by morphology-controlled solid-state pyrolysis of poly(aniline-co-2-ami no thiophenol)foam.The uniform high concentrations of nitrogen and sulfur,high intrinsic conductivity,and integrated three dimensional ionic and electronic transfer passageways of the 3D porous structure lead to synergistic effects in catalyzing ORR.As a result,the limiting current density of the carbonized poly(aniline-co-2-aminothiophenol)foam is equivalent to commercial Pt/C in acidic environment,and twice the latter in alkaline medium.展开更多
The effect of mechanical strength of the dispersed particle gel(DPG)on its macro plugging performance is significant,however,little study has been reported.In this paper,DPG particles with different mechanical strengt...The effect of mechanical strength of the dispersed particle gel(DPG)on its macro plugging performance is significant,however,little study has been reported.In this paper,DPG particles with different mechanical strengths were obtained by mechanical shearing of bulk gels prepared with different formula.Young’s moduli of DPG particles on the micro and nano scales were measured by atomic force microscope for the first time.The mapping relationship among the formula of bulk gel,the Young’s moduli of the DPG particles and the final plugging performance were established.The results showed that when the Young’s moduli of the DPG particles increased from 82 to 328 Pa,the plugging rate increased significantly from 91.46%to 97.10%due to the distinctly enhanced stacking density and strength at this range.While when the Young’s moduli of the DPG particles surpassed 328 Pa,the further increase of plugging rate with the Young’s moduli of the DPG particles became insignificant.These results indicated that the improvement of plugging rate was more efficient by adjusting the Young’s moduli of the DPG particles within certain ranges,providing guidance for improving the macroscopic application properties of DPG systems in reservoir heterogeneity regulation.展开更多
The sensitivity of moving particle semi-implicit(MPS)simulations to numerical parameters is investigated in this study.Although the verifcation and validation(V&V)are important to ensure accurate numerical results...The sensitivity of moving particle semi-implicit(MPS)simulations to numerical parameters is investigated in this study.Although the verifcation and validation(V&V)are important to ensure accurate numerical results,the MPS has poor perfor-mance in convergences with a time step size.Therefore,users of the MPS need to tune numerical parameters to ft results into benchmarks.However,such tuning parameters are not always valid for other simulations.We propose a practical numerical condition for the MPS simulation of a two-dimensional wedge slamming problem(i.e.,an MPS-slamming condition).The MPS-slamming condition is represented by an MPS-slamming number,which provides the optimum time step size once the MPS-slamming number,slamming velocity,deadrise angle of the wedge,and particle size are decided.The simulation study shows that the MPS results can be characterized by the proposed MPS-slamming condition,and the use of the same MPS-slamming number provides a similar fow.展开更多
基金supported by the National Natural Science Foundation of China(No.51806103)the Natural Science Foundation of Jiangsu Province(No.BK20170800)Aeronautical Science Foundation of China(No.201928052002)。
文摘Particles,including soot,aerosol and ash,usually exist as fractal aggregates.The radiative properties of the particle fractal aggregates have a great influence on studying the light or heat radiative transfer in the particle medium.In the present work,the performance of the single-layer inversion model and the double-layer inversion model in reconstructing the geometric structure of particle fractal aggregates is studied based on the light reflectancetransmittance measurement method.An improved artificial fish-swarm algorithm(IAFSA)is proposed to solve the inverse problem.The result reveals that the accuracy of double-layer inversion model is more satisfactory as it can provide more uncorrelated information than the single-layer inversion model.Moreover,the developed IAFSA show higher accuracy and better robustness than the original artificial fish swarm algorithm(AFSA)for avoiding local optimization problems effectively.As a whole,the present work supplies a useful kind of measurement technology for predicting geometrical morphology of particle fractal aggregates.
基金Project supported by the National Natural Science Foundation of China(Grant No.11404004)
文摘A novel and simple strategy of morphology-controlled Sr Ti O3（ST） micro-scale particle synthesis by the flux method is reported. Systematic experiments are designed to realize the tunable morphologies of the particles when the flux salt,sintering process, and the precursors are changed. The ST plates can be synthesized by plate-like Bi4Ti3O12（BIT） precursors in Na Cl flux. However, the as-synthesized Bi4Ti3O12 grains transform into reticular particles and finally into rods at higher temperature in Na Cl and KCl compounds. Besides, cubic ST particles are also prepared using different precursors as a comparative experiment. This study provides a strategy for further investigations in designing the morphology-controlled particles and efficient anisotropic materials of perovskite structure such as ferroelectric and photocatalyst.
基金financial support from the Interdisciplinary Fund of the Wuhan National High Magnetic Field Center (No. WHMFC202101)。
文摘The discharge morphology of pulsed dielectric barrier discharge(PDBD) plays important roles in its applications. Here, we systematically investigated the effects of the voltage amplitude,discharge gap, and O_(2)content on the PDBD morphology, and revealed the possible underlying mechanism of the U-shaped formation. First, the morphological evolution under different conditions was recorded. A unique U-shaped region appears in the middle edge region when the gap is larger than 2 mm, while the entire discharge region remains columnar under a 2 mm gap in He PDBD. The width of the discharge and the U-shaped region increase with the increase in voltage, and decrease with the increase of the gap and O_(2)content. To explain this phenomenon,a two-dimensional symmetric model was developed to simulate the spatiotemporal evolution of different species and calculate the electric thrust. The discharge morphology evolution directly corresponds to the excited-state atomic reduction process. The electric thrust on the charged particles mainly determines the reaction region and strongly influences the U-shaped formation.When the gap is less than 2 mm, the electric thrust is homogeneous throughout the entire region,resulting in a columnar shape. However, when the gap is larger than 2 mm or O_(2)is added, the electric thrust in the edge region becomes greater than that in the middle, leading to the U-shaped formation. Furthermore, in He PDBD, the charged particles generating electric thrust are mainly electrons and helium ions, while in He/O_(2)PDBD those that generate electric thrust at the outer edge of the electrode surface are mainly various oxygen-containing ions.
基金supported by the National Natural Science Foundation of China,China(No.81927809).
文摘A covalent organic frameworks(COFs)material with regular pores and stable structure can be used as the host of lithium-sulfur batteries to improve battery kinetics and polysulfides conversion.Herein,we designed and synthesized two kinds of rod-liked bulk COFs by adjusting different pore sizes(COF-BTD and COF-TFB),unfortunately,the active sites masking and sluggish kinetics have not met our expectations.Generally,the available layered COFs prepared from mechanochemical can expose abundant active sites and favorable kinetics than bulk COFs.Thus,simple mechanical ball milling is applied to activate the above COFs(M-COFs group).It is worth noting that layered R-COF-BTD is directly synthesized from rod-liked precursors by simple morphological reconstruction.A series of characterization methods are used to systematically explore the advantages of the group of M-COFs@S electrodes in the cycling process,including the effects of specific morphology on the kinetics and transformation of polysulfides.Our research provides a feasible plan for the development and selection of the host material of lithium-sulfur batteries.
基金supported by the National Natural Science Foundation of China(Nos.U22A20166,52104141,12172230 and U2013603)the Department of Science and Technology of Guangdong Province(No.2019ZT08G315)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515012654).
文摘Interparticle adhesion force has a controlling effect on the physical and mechanical properties of planetary regolith and rocks.The current research on the adhesion force of planetary regolith and rock particles has been primarily based on the assumption of smooth spherical particles to calculate the intergranular adhesion force;this approach lacks consideration for the adhesion force between irregular shaped particles.In our study,an innovative approach was established to directly measure the adhesion force between the arbitrary irregular shaped particles;the probe was modified using simulated lunar soil particles that were a typical representation of planetary regolith.The experimental results showed that for irregular shaped mineral particles,the particle size and mineral composition had no significant influence on the interparticle adhesion force;however,the complex morphology of the contact surface predominantly controlled the adhesion force.As the contact surface roughness increased,the adhesion force gradually decreased,and the rate of decrease gradually slowed;these results were consistent with the change trend predicted via the theoretical models of quantum electrodynamics.Moreover,a theoretical model to predict the adhesion force between the irregular shaped particles was constructed based on Rabinovich’s theory,and the prediction results were correlated with the experimental measurements.
基金supported by the funding from Beijing municipal high level innovative team building program(IDHT20190503)the National Natural Science Foundation of China(22075006)。
文摘The particle morphology determined by the sintering process is the director factor affecting the electrochemical performance of Ni-rich NMC cathode materials.To prepare the ideal NMC particles,it is of great significance to understand the morphological changes during sintering process.In this work,the morphology evolution of LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811)synthesis at temperature ranging from 300–1080℃were observed by in situ SEM.The uniform mixture of spherical Ni_(0.8)Mn_(0.1)Co_(0.1)(OH)_(2)precursor and lithium sources(LiOH)was employed by high temperature solid-state process inside the SEM,which enables us to observe morphology changes in real time.The results show that synthetic reaction of LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)usually includes three processes:the raw materials’dehydration,oxidation,and combination,accompanied by a significant reduction in particle size,which is important reference to control the synthesis temperature.As heating temperature rise,the morphology of mixture also changed from flake to brick-shaped.However,Ni nanoparticle formation is apparent at higher temperature~1000℃,suggesting a structural transformation from a layered to a rock-salt-like structure.Combining the in-situ observed changes in size and morphology,and with the premise of ensuring the morphology change from flakes to bricks,reducing the sintering temperature as much as possible to prevent excessive reduction in particle size and layered to a rock-salt structure transformation is recommended for prepare ideal NMC particles.
基金This work was supported by the General Program of National Natural Science Foundation of China under(Grant Nos.71774012,72104246,71673024)the Fundamental Research Funds for the Central Universities(22CX04010B)the strategic research project of the Development Planning Bureau of the Chinese Academy of Sciences(Grant No.GHJ-ZLZX-2019-42).The findings and observations in this paper are those of the authors and do not necessarily reflect the views of the supporters.
文摘Purpose:Measuring the exact technology complementarity between different institutions is necessary to obtain complementary technology resources for R&D cooperation.Design/methodology/approach:This study constructs a morphology-driven method for measuring technology complementarity,taking medical field as an example.First,we calculate semantic similarities between subjects(S and S)and action-objects(AO and AO)based on the Metathesaurus,forming clusters of S and AO based on a semantic similarity matrix.Second,we identify key technology issues and methods based on clusters of S and AO.Third,a technology morphology matrix of several dimensions is constructed using morphology analysis,and the matrix is filled with subjects-action-objects(SAO)structures according to corresponding key technology issues and methods for different institutions.Finally,the technology morphology matrix is used to measure the technology complementarity between different institutions based on SAO.Findings:The improved technology complementarity method based on SAO is more of a supplementary and refined framework for the traditional IPC method.Research limitations:In future studies we will reprocess and identify the SAO structures which were not in the technology morphology matrix,and find other methods to characterize key technical issues and methods.Furthermore,we will add the comparison between proposed method and traditional and mostly used complementarity measurement method based on industry chain and industry code.Practical implications:This study takes medical field as an example.The morphology-driven method for measuring technology complementarity can be migrated and applied for any given field.Originality/value:From the perspective of complementary technology resources,this study develops and tests a more accurate morphology-driven method for technology complementarity measurement.
基金financial support by the National Natural Science Foundation of China (Grant: 51333008)Young Teacher Training Program of Sun Yat-sen University (Grant: 17lgpy86)
文摘Developing high-performance non-precious metal electrocatalysts for oxygen reduction reaction(ORR)is crucial for the commercialization of fuel cells and metal-air batteries.However,doped carbon-based materials only show good ORR activity in alkaline medium,and become less effective in acidic environment.We believe that an appropriate combination of both ionic and electronic transport path,and well dopant distribution of doped carbon-based materials would help to realize high ORR performance un-der both acidic and alkaline cond让ions.Accordingly,a nitrogen and sulfur co-doped carbon framework with hierarchical through-hole structure is fabricated by morphology-controlled solid-state pyrolysis of poly(aniline-co-2-ami no thiophenol)foam.The uniform high concentrations of nitrogen and sulfur,high intrinsic conductivity,and integrated three dimensional ionic and electronic transfer passageways of the 3D porous structure lead to synergistic effects in catalyzing ORR.As a result,the limiting current density of the carbonized poly(aniline-co-2-aminothiophenol)foam is equivalent to commercial Pt/C in acidic environment,and twice the latter in alkaline medium.
基金financially supported by the National Key Research and Development Program of China(No.2019YFA0708700)National Natural Science Foundation of China(52174054,51804326)Shandong Provincial Natural Science Foundation(ZR2019BEE046)
文摘The effect of mechanical strength of the dispersed particle gel(DPG)on its macro plugging performance is significant,however,little study has been reported.In this paper,DPG particles with different mechanical strengths were obtained by mechanical shearing of bulk gels prepared with different formula.Young’s moduli of DPG particles on the micro and nano scales were measured by atomic force microscope for the first time.The mapping relationship among the formula of bulk gel,the Young’s moduli of the DPG particles and the final plugging performance were established.The results showed that when the Young’s moduli of the DPG particles increased from 82 to 328 Pa,the plugging rate increased significantly from 91.46%to 97.10%due to the distinctly enhanced stacking density and strength at this range.While when the Young’s moduli of the DPG particles surpassed 328 Pa,the further increase of plugging rate with the Young’s moduli of the DPG particles became insignificant.These results indicated that the improvement of plugging rate was more efficient by adjusting the Young’s moduli of the DPG particles within certain ranges,providing guidance for improving the macroscopic application properties of DPG systems in reservoir heterogeneity regulation.
文摘The sensitivity of moving particle semi-implicit(MPS)simulations to numerical parameters is investigated in this study.Although the verifcation and validation(V&V)are important to ensure accurate numerical results,the MPS has poor perfor-mance in convergences with a time step size.Therefore,users of the MPS need to tune numerical parameters to ft results into benchmarks.However,such tuning parameters are not always valid for other simulations.We propose a practical numerical condition for the MPS simulation of a two-dimensional wedge slamming problem(i.e.,an MPS-slamming condition).The MPS-slamming condition is represented by an MPS-slamming number,which provides the optimum time step size once the MPS-slamming number,slamming velocity,deadrise angle of the wedge,and particle size are decided.The simulation study shows that the MPS results can be characterized by the proposed MPS-slamming condition,and the use of the same MPS-slamming number provides a similar fow.
