Processing of materials by ultrashort laser pulses has evolved significantly over the last decade and is starting to reveal its scientific,technological and industrial potential.In ultrafast laser manufacturing,optica...Processing of materials by ultrashort laser pulses has evolved significantly over the last decade and is starting to reveal its scientific,technological and industrial potential.In ultrafast laser manufacturing,optical energy of tightly focused femtosecond or picosecond laser pulses can be delivered to precisely defined positions in the bulk of materials via two-/multi-photon excitation on a timescale much faster than thermal energy exchange between photoexcited electrons and lattice ions.Control of photoionization and thermal processes with the highest precision,inducing local photomodification in sub-100-nm-sized regions has been achieved.State-of-the-art ultrashort laser processing techniques exploit high 0.1–1μm spatial resolution and almost unrestricted three-dimensional structuring capability.Adjustable pulse duration,spatiotemporal chirp,phase front tilt and polarization allow control of photomodification via uniquely wide parameter space.Mature opto-electrical/mechanical technologies have enabled laser processing speeds approaching meters-per-second,leading to a fast lab-to-fab transfer.The key aspects and latest achievements are reviewed with an emphasis on the fundamental relation between spatial resolution and total fabrication throughput.Emerging biomedical applications implementing micrometer feature precision over centimeter-scale scaffolds and photonic wire bonding in telecommunications are highlighted.展开更多
The electronic metal-support interaction(EMSI)is one of most intriguing phenomena in heterogeneous catalysis.In this work,this subtle effect is clearly demonstrated by density functional theory(DFT)calculations of sin...The electronic metal-support interaction(EMSI)is one of most intriguing phenomena in heterogeneous catalysis.In this work,this subtle effect is clearly demonstrated by density functional theory(DFT)calculations of single Pt atom supported on vacancies in a boron nitride nanosheet.Moreover,the relation between the EMSI and the performance of Pt in propane direct dehydrogenation(PDH)is investigated in detail.The charge state and partial density of states of single Pt atom show distinct features at different anchoring positions,such as boron and nitrogen vacancies(Bvac and Nvac,respectively).Single Pt atom become positively and negatively charged on Bvac and Nvac,respectively.Therefore,the electronic structure of Pt can be adjusted by rational deposition on the support.Moreover,Pt atoms in different charge states have been shown to have different catalytic abilities in PDH.The DFT calculations reveal that Pt atoms on Bvac(Pt-Bvac)have much higher reactivity towards reactant/product adsorption and C–H bond activation than Pt supported on Nvac(Pt-Nvac),with larger adsorption energy and lower barrier along the reaction pathway.However,the high reactivity of Pt-Bvac also hinders propene desorption,which could lead to unwanted deep dehydrogenation.Therefore,the results obtained herein suggest that a balanced reactivity for C–H activation in propane and propene desorption is required to achieve optimum yields.Based on this descriptor,a single Pt atom on a nitrogen vacancy is considered an effective catalyst for PDH.Furthermore,the deep dehydrogenation of the formed propene is significantly suppressed,owing to the large barrier on Pt-Nvac.The current work demonstrates that the catalytic properties of supported single Pt atoms can be tuned by rationally depositing them on a boron nitride nanosheet and highlights the great potential of single-atom catalysis in the PDH reaction.展开更多
Direct-fed microbials(DFMs)are feed additives containing live naturally existing microbes that can benefit animals’health and production performance.Due to the banned or strictly limited prophylactic and growth promo...Direct-fed microbials(DFMs)are feed additives containing live naturally existing microbes that can benefit animals’health and production performance.Due to the banned or strictly limited prophylactic and growth promoting usage of antibiotics,DFMs have been considered as one of antimicrobial alternatives in livestock industry.Microorganisms used as DFMs for ruminants usually consist of bacteria including lactic acid producing bacteria,lactic acid utilizing bacteria and other bacterial groups,and fungi containing Saccharomyces and Aspergillus.To date,the available DFMs for ruminants have been largely based on their effects on improving the feed efficiency and ruminant productivity through enhancing the rumen function such as stabilizing ruminal pH,promoting ruminal fermentation and feed digestion.Recent research has shown emerging evidence that the DFMs may improve performance and health in young ruminants,however,these positive outcomes were not consistent among studies and the modes of action have not been clearly defined.This review summarizes the DFM studies conducted in ruminants in the last decade,aiming to provide the new knowledge on DFM supplementation strategies for various ruminant production stages,and to identify what are the potential barriers and challenges for current ruminant industry to adopt the DFMs.Overall literature research indicates that DFMs have the potential to mitigate ruminal acidosis,improve immune response and gut health,increase productivity(growth and milk production),and reduce methane emissions or fecal shedding of pathogens.More research is needed to explore the mode of action of specific DFMs in the gut of ruminants,and the optimal supplementation strategies to promote the development and efficiency of DFM products for ruminants.展开更多
Diverse natural organisms possess stimulus-responsive structures to adapt to the surrounding environment.Inspired by nature,researchers have developed various smart stimulus-responsive structures with adjustable prope...Diverse natural organisms possess stimulus-responsive structures to adapt to the surrounding environment.Inspired by nature,researchers have developed various smart stimulus-responsive structures with adjustable properties and functions to address the demands of ever-changing application environments that are becoming more intricate.Among many fabrication methods for stimulus-responsive structures,femtosecond laser direct writing(FsLDW)has received increasing attention because of its high precision,simplicity,true three-dimensional machining ability,and wide applicability to almost all materials.This paper systematically outlines state-of-the-art research on stimulus-responsive structures prepared by FsLDW.Based on the introduction of femtosecond laser-matter interaction and mainstream FsLDW-based manufacturing strategies,different stimulating factors that can trigger structural responses of prepared intelligent structures,such as magnetic field,light,temperature,pH,and humidity,are emphatically summarized.Various applications of functional structures with stimuli-responsive dynamic behaviors fabricated by FsLDW,as well as the present obstacles and forthcoming development opportunities,are discussed.展开更多
Voltage source converter based high voltage direct current(VSC-HVDC)can participate in voltage regulation by flexible control to help maintain the voltage stability of the power grid.In order to quantitatively evaluat...Voltage source converter based high voltage direct current(VSC-HVDC)can participate in voltage regulation by flexible control to help maintain the voltage stability of the power grid.In order to quantitatively evaluate its influence on the voltage interaction between VSC-HVDC and line commutated converter based high voltage direct current(LCC-HVDC),this paper proposes a hybrid multi-infeed interaction factor(HMIIF)calculation method considering the voltage regulation control characteristics of VSC-HVDC.Firstly,for a hybrid multi-infeed high voltage direct current system,an additional equivalent operating admittance matrix is constructed to characterize HVDC equipment characteristics under small disturbance.Secondly,based on the characteristic curve between the reactive power and the voltage of a certain VSC-HVDC project,the additional equivalent operating admittance of VSC-HVDC is derived.The additional equivalent operating admittance matrix calculation method is proposed.Thirdly,the equivalent bus impedance matrix is obtained by modifying the alternating current(AC)system admittance matrix with the additional equivalent operating admittance matrix.On this basis,the HMIIF calculation method based on the equivalent bus impedance ratio is proposed.Finally,the effectiveness of the proposed method is verified in a hybrid dual-infeed high voltage direct current system constructed in Power Systems Computer Aided Design(PSCAD),and the influence of voltage regulation control on HMIIF is analyzed.展开更多
This paper provides a comprehensive analysis of local and concurrent commutation failure(CF)of multi-infeed high-voltage direct current(HVDC)system considering multi-infeed interaction factor(MIIF).The literature indi...This paper provides a comprehensive analysis of local and concurrent commutation failure(CF)of multi-infeed high-voltage direct current(HVDC)system considering multi-infeed interaction factor(MIIF).The literature indicates that the local CF is not influenced by MIIF,whereas this paper concludes that both the local CF and concurrent CF are influenced by MIIF.The ability of remote converter to work under reduced reactive power enables its feature to support local converter via inter-connection link.The MIIF measures the strength of electrical connectivity between converters.Higher MIIF gives a clearer path to remote converter to support local converter,but at the same time,it provides an easy path to local converter to disturb remote converter under local fault.The presence of nearby converter increases the local commutation failure immunity index(CFII)while reducing concurrent CFII.Higher MIIF causes reactive power support to flow from remote converter to local converter,which reduces the chances of CF.A mathematical approximation to calculate the increase in local CFII for multi-infeed HVDC configurations is also proposed.A power flow approach is used to model the relation between MIIF and reactive power support from remote end.The local and concurrent CFIIs are found to be inverse to each other over MIIF;therefore,it is recommended that there is an optimal value of MIIF for all converters in close electric proximity to maintain CFII at a certain level.The numerical results of established model are compared with PSCAD/EMTDC simulations.The simulation results show the details of the influence of MIIF on local CF and concurrent CF of multi-infeed HVDC,which validates the analysis presented.展开更多
To realize large-scale micro/nanofabrication process in superconducting devices,the nano laser direct writing(NLDW)as a potential tool was implemented.In this paper,thermal effect induced laser-matter(superconducting ...To realize large-scale micro/nanofabrication process in superconducting devices,the nano laser direct writing(NLDW)as a potential tool was implemented.In this paper,thermal effect induced laser-matter(superconducting film)interaction based on laser direct writing on Nb films and laser exposure on photoresist were investigated by simulation and experiment.To avoid nanoscale thermal effect on superconducting films,large-scale superconducting nanoarrays with the area up to 100μm×100μm based on laser exposure on photoresist were fabricated.Compared with laser direct writing on superconducting films,which lead to the degradation of superconducting performance such as critical current,transition temperature,the superconducting nanoarrays based on laser exposure on photoresist maintain excellent superconducting performance without degradation.Besides that,by further optimizing the process parameters and the thickness of photoresist,the nanowires with the width down to nanometers are plausible.Compared with the traditional electron beam and ion beam process,to some extent,the nanowires fabrication process based on NLDW provides a more efficient and cost-effective path for the fabrication of large-area superconducting devices/circuits.展开更多
Fluid-structure-particle interactions in three spatial dimensions happen in many environmental and engineering flows.This paper presents the parallel algorithms for the hybrid diffuse and sharp interface immersed boun...Fluid-structure-particle interactions in three spatial dimensions happen in many environmental and engineering flows.This paper presents the parallel algorithms for the hybrid diffuse and sharp interface immersed boundary(IB)method developed in our previous work.For the moving structure modeled using the sharp interface IB method,a recursive box method is developed for efficiently classifying the background grid nodes.For the particles modeled using the diffuse interface IB method,a‘master-slave’approach is adopted.For the particle-particle interaction(PPI)and particle-structure interaction(PSI),a fast algorithm for classifying the active and inactive Lagrangian points,which discretize the particle surface,is developed for the‘dry’contact approach.The results show that the proposed recursive box method can reduce the classifying time from 52seconds to 0.3 seconds.Acceptable parallel efficiency is obtained for cases with different particle concentrations.Furthermore,the lubrication model is utilized when a particle approaches a wall,enabling an accurate simulation of the rebounding phenomena in the benchmark particle-wall collision problem.At last,the capability of the proposed computational framework is demonstrated by simulating particle-laden turbulent channel flows with rough walls.展开更多
The dust distribution law acting at the top of a blast fumace(BF)is of great significance for understanding gas flow distribution and mitigating the negative influence of dust particles on the accuracy and service lif...The dust distribution law acting at the top of a blast fumace(BF)is of great significance for understanding gas flow distribution and mitigating the negative influence of dust particles on the accuracy and service life of detection equipment.The harsh environment inside a BF makes it difficult to describe the dust disthibution.This paper adresses this problem by proposing a dust distribution k-Sε-u_(p)model based on interphase(gas-powder)coupling.The proposed model is coupled with a k-Sεmodel(which describes gas flow movement)and a u_(p)model(which depicts dust movement).First,the kinetic energy equation and turbulent dissipation rate equation in the k-Sεmodel are established based on the modeling theory and single Green-function two scale direct interaction approximation(SGF-TSDIA)theory.Second,a dust particle mnovement u_(p)model is built based on a force analysis of the dust and Newton's laws of motion.Finally,a coupling factor that descibes the interphase interaction is proposed,and the k-Sε-u_(p)model,with clear physical meaning.ligorous mathematical logic,and adequate generality,is dleveloped.Siumulation results and o-site verification show that the k-Sε-u_(p)model not only has high precision,but also reveals the aggregate distribution features of the dust,which are helpful in optimizing the installation position of the detection equipment and imnproving its accuracy and service life.展开更多
Based on the interface shear tests,the macro-and meso-mechanical behaviors of interaction between coral sand and different structure surfaces are studied,in which CCD camera is used to capture digital images to analyz...Based on the interface shear tests,the macro-and meso-mechanical behaviors of interaction between coral sand and different structure surfaces are studied,in which CCD camera is used to capture digital images to analyze the evolution of the interaction band and a particle analysis apparatus is applied to studying the distribution characteristics of particle morphology.This study proposes four-stage evolution process based on the shear stress−strain curve.During the shear process,coral sand particles slide and rotate within the interaction band,causing the changes in shear stress and vertical displacement.In addition,the effects of structure surface roughness on shear strength,volume change and particle breakage are illustrated that the greater the roughness of slabs is,the larger the shear stress is,the more obvious the contraction effect is and the more the particles break.Furthermore,the change in particle’s 3D morphology during the breakage will change not only their size but also other morphological characteristics with convergence and self-organization.展开更多
基金support by a project‘ReSoft’(SEN-13/2015)from the Research Council of Lithuaniasupport by JSPS Kakenhi Grant No.15K04637+1 种基金support via ARC Discovery DP120102980Gintas Šlekys for the partnership project with Altechna Ltd on industrial fs-laser fabrication.
文摘Processing of materials by ultrashort laser pulses has evolved significantly over the last decade and is starting to reveal its scientific,technological and industrial potential.In ultrafast laser manufacturing,optical energy of tightly focused femtosecond or picosecond laser pulses can be delivered to precisely defined positions in the bulk of materials via two-/multi-photon excitation on a timescale much faster than thermal energy exchange between photoexcited electrons and lattice ions.Control of photoionization and thermal processes with the highest precision,inducing local photomodification in sub-100-nm-sized regions has been achieved.State-of-the-art ultrashort laser processing techniques exploit high 0.1–1μm spatial resolution and almost unrestricted three-dimensional structuring capability.Adjustable pulse duration,spatiotemporal chirp,phase front tilt and polarization allow control of photomodification via uniquely wide parameter space.Mature opto-electrical/mechanical technologies have enabled laser processing speeds approaching meters-per-second,leading to a fast lab-to-fab transfer.The key aspects and latest achievements are reviewed with an emphasis on the fundamental relation between spatial resolution and total fabrication throughput.Emerging biomedical applications implementing micrometer feature precision over centimeter-scale scaffolds and photonic wire bonding in telecommunications are highlighted.
基金supported by the National Science Foundation of China(91545117)the Natural Science Foundation of Liaoning Province(201602676)+1 种基金the Fundamental Research Funds for Colleges and Universities in Liaoning Province(LQN201703)the Startup Foundation for Doctors of Shenyang Normal University(BS201620)~~
文摘The electronic metal-support interaction(EMSI)is one of most intriguing phenomena in heterogeneous catalysis.In this work,this subtle effect is clearly demonstrated by density functional theory(DFT)calculations of single Pt atom supported on vacancies in a boron nitride nanosheet.Moreover,the relation between the EMSI and the performance of Pt in propane direct dehydrogenation(PDH)is investigated in detail.The charge state and partial density of states of single Pt atom show distinct features at different anchoring positions,such as boron and nitrogen vacancies(Bvac and Nvac,respectively).Single Pt atom become positively and negatively charged on Bvac and Nvac,respectively.Therefore,the electronic structure of Pt can be adjusted by rational deposition on the support.Moreover,Pt atoms in different charge states have been shown to have different catalytic abilities in PDH.The DFT calculations reveal that Pt atoms on Bvac(Pt-Bvac)have much higher reactivity towards reactant/product adsorption and C–H bond activation than Pt supported on Nvac(Pt-Nvac),with larger adsorption energy and lower barrier along the reaction pathway.However,the high reactivity of Pt-Bvac also hinders propene desorption,which could lead to unwanted deep dehydrogenation.Therefore,the results obtained herein suggest that a balanced reactivity for C–H activation in propane and propene desorption is required to achieve optimum yields.Based on this descriptor,a single Pt atom on a nitrogen vacancy is considered an effective catalyst for PDH.Furthermore,the deep dehydrogenation of the formed propene is significantly suppressed,owing to the large barrier on Pt-Nvac.The current work demonstrates that the catalytic properties of supported single Pt atoms can be tuned by rationally depositing them on a boron nitride nanosheet and highlights the great potential of single-atom catalysis in the PDH reaction.
基金The authors acknowledge funding support from Ministry of Alberta Agriculture Results Driven Agriculture Research(2018F097R and 2021F124R)NSERC Discovery Grant.
文摘Direct-fed microbials(DFMs)are feed additives containing live naturally existing microbes that can benefit animals’health and production performance.Due to the banned or strictly limited prophylactic and growth promoting usage of antibiotics,DFMs have been considered as one of antimicrobial alternatives in livestock industry.Microorganisms used as DFMs for ruminants usually consist of bacteria including lactic acid producing bacteria,lactic acid utilizing bacteria and other bacterial groups,and fungi containing Saccharomyces and Aspergillus.To date,the available DFMs for ruminants have been largely based on their effects on improving the feed efficiency and ruminant productivity through enhancing the rumen function such as stabilizing ruminal pH,promoting ruminal fermentation and feed digestion.Recent research has shown emerging evidence that the DFMs may improve performance and health in young ruminants,however,these positive outcomes were not consistent among studies and the modes of action have not been clearly defined.This review summarizes the DFM studies conducted in ruminants in the last decade,aiming to provide the new knowledge on DFM supplementation strategies for various ruminant production stages,and to identify what are the potential barriers and challenges for current ruminant industry to adopt the DFMs.Overall literature research indicates that DFMs have the potential to mitigate ruminal acidosis,improve immune response and gut health,increase productivity(growth and milk production),and reduce methane emissions or fecal shedding of pathogens.More research is needed to explore the mode of action of specific DFMs in the gut of ruminants,and the optimal supplementation strategies to promote the development and efficiency of DFM products for ruminants.
基金supported by the National Natural Science Foundation of China (Nos. 52122511, 52105492, and 62005262)the National Key Research and Development Program of China (No. 2021YFF0502700)+2 种基金the Students’ Innovation and Entrepreneurship Foundation of USTC (Nos. CY2022G32 and XY2022G02CY)the USTC Research Funds of the Double First-Class Initiative (No. YD2340002009)CAS Project for Young Scientists in Basic Research (No. YSBR-049)
文摘Diverse natural organisms possess stimulus-responsive structures to adapt to the surrounding environment.Inspired by nature,researchers have developed various smart stimulus-responsive structures with adjustable properties and functions to address the demands of ever-changing application environments that are becoming more intricate.Among many fabrication methods for stimulus-responsive structures,femtosecond laser direct writing(FsLDW)has received increasing attention because of its high precision,simplicity,true three-dimensional machining ability,and wide applicability to almost all materials.This paper systematically outlines state-of-the-art research on stimulus-responsive structures prepared by FsLDW.Based on the introduction of femtosecond laser-matter interaction and mainstream FsLDW-based manufacturing strategies,different stimulating factors that can trigger structural responses of prepared intelligent structures,such as magnetic field,light,temperature,pH,and humidity,are emphatically summarized.Various applications of functional structures with stimuli-responsive dynamic behaviors fabricated by FsLDW,as well as the present obstacles and forthcoming development opportunities,are discussed.
基金supported by the Technology Project of the State Grid Corporation Headquarters Management(Contract No.5100-202158467A-0-0-00).
文摘Voltage source converter based high voltage direct current(VSC-HVDC)can participate in voltage regulation by flexible control to help maintain the voltage stability of the power grid.In order to quantitatively evaluate its influence on the voltage interaction between VSC-HVDC and line commutated converter based high voltage direct current(LCC-HVDC),this paper proposes a hybrid multi-infeed interaction factor(HMIIF)calculation method considering the voltage regulation control characteristics of VSC-HVDC.Firstly,for a hybrid multi-infeed high voltage direct current system,an additional equivalent operating admittance matrix is constructed to characterize HVDC equipment characteristics under small disturbance.Secondly,based on the characteristic curve between the reactive power and the voltage of a certain VSC-HVDC project,the additional equivalent operating admittance of VSC-HVDC is derived.The additional equivalent operating admittance matrix calculation method is proposed.Thirdly,the equivalent bus impedance matrix is obtained by modifying the alternating current(AC)system admittance matrix with the additional equivalent operating admittance matrix.On this basis,the HMIIF calculation method based on the equivalent bus impedance ratio is proposed.Finally,the effectiveness of the proposed method is verified in a hybrid dual-infeed high voltage direct current system constructed in Power Systems Computer Aided Design(PSCAD),and the influence of voltage regulation control on HMIIF is analyzed.
基金This work was supported by science and technology project of China Southern Power Grid(No.ZBKJXM20180104).
文摘This paper provides a comprehensive analysis of local and concurrent commutation failure(CF)of multi-infeed high-voltage direct current(HVDC)system considering multi-infeed interaction factor(MIIF).The literature indicates that the local CF is not influenced by MIIF,whereas this paper concludes that both the local CF and concurrent CF are influenced by MIIF.The ability of remote converter to work under reduced reactive power enables its feature to support local converter via inter-connection link.The MIIF measures the strength of electrical connectivity between converters.Higher MIIF gives a clearer path to remote converter to support local converter,but at the same time,it provides an easy path to local converter to disturb remote converter under local fault.The presence of nearby converter increases the local commutation failure immunity index(CFII)while reducing concurrent CFII.Higher MIIF causes reactive power support to flow from remote converter to local converter,which reduces the chances of CF.A mathematical approximation to calculate the increase in local CFII for multi-infeed HVDC configurations is also proposed.A power flow approach is used to model the relation between MIIF and reactive power support from remote end.The local and concurrent CFIIs are found to be inverse to each other over MIIF;therefore,it is recommended that there is an optimal value of MIIF for all converters in close electric proximity to maintain CFII at a certain level.The numerical results of established model are compared with PSCAD/EMTDC simulations.The simulation results show the details of the influence of MIIF on local CF and concurrent CF of multi-infeed HVDC,which validates the analysis presented.
基金supported by the National Natural Science Foundation of China(No.12104112)the Natural Science Foundation of Shandong Province(No.ZR2021QA036).
文摘To realize large-scale micro/nanofabrication process in superconducting devices,the nano laser direct writing(NLDW)as a potential tool was implemented.In this paper,thermal effect induced laser-matter(superconducting film)interaction based on laser direct writing on Nb films and laser exposure on photoresist were investigated by simulation and experiment.To avoid nanoscale thermal effect on superconducting films,large-scale superconducting nanoarrays with the area up to 100μm×100μm based on laser exposure on photoresist were fabricated.Compared with laser direct writing on superconducting films,which lead to the degradation of superconducting performance such as critical current,transition temperature,the superconducting nanoarrays based on laser exposure on photoresist maintain excellent superconducting performance without degradation.Besides that,by further optimizing the process parameters and the thickness of photoresist,the nanowires with the width down to nanometers are plausible.Compared with the traditional electron beam and ion beam process,to some extent,the nanowires fabrication process based on NLDW provides a more efficient and cost-effective path for the fabrication of large-area superconducting devices/circuits.
基金Project supported by the National Natural Science Foundation of China(Nos.12202456 and12172360)the Basic Science Center Program for“Multiscale Problems in Nonlinear Mechanics”of the National Natural Science Foundation of China(No.11988102)the China Postdoctoral Science Foundation(No.2021M693241)。
文摘Fluid-structure-particle interactions in three spatial dimensions happen in many environmental and engineering flows.This paper presents the parallel algorithms for the hybrid diffuse and sharp interface immersed boundary(IB)method developed in our previous work.For the moving structure modeled using the sharp interface IB method,a recursive box method is developed for efficiently classifying the background grid nodes.For the particles modeled using the diffuse interface IB method,a‘master-slave’approach is adopted.For the particle-particle interaction(PPI)and particle-structure interaction(PSI),a fast algorithm for classifying the active and inactive Lagrangian points,which discretize the particle surface,is developed for the‘dry’contact approach.The results show that the proposed recursive box method can reduce the classifying time from 52seconds to 0.3 seconds.Acceptable parallel efficiency is obtained for cases with different particle concentrations.Furthermore,the lubrication model is utilized when a particle approaches a wall,enabling an accurate simulation of the rebounding phenomena in the benchmark particle-wall collision problem.At last,the capability of the proposed computational framework is demonstrated by simulating particle-laden turbulent channel flows with rough walls.
基金supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(61621062)the National Major Scientific Research Equipment of China(61927803)+1 种基金the National Natural Science Foundation of China(61933015)National Natural Science Foundation for Young Scholars of China(61903325)。
文摘The dust distribution law acting at the top of a blast fumace(BF)is of great significance for understanding gas flow distribution and mitigating the negative influence of dust particles on the accuracy and service life of detection equipment.The harsh environment inside a BF makes it difficult to describe the dust disthibution.This paper adresses this problem by proposing a dust distribution k-Sε-u_(p)model based on interphase(gas-powder)coupling.The proposed model is coupled with a k-Sεmodel(which describes gas flow movement)and a u_(p)model(which depicts dust movement).First,the kinetic energy equation and turbulent dissipation rate equation in the k-Sεmodel are established based on the modeling theory and single Green-function two scale direct interaction approximation(SGF-TSDIA)theory.Second,a dust particle mnovement u_(p)model is built based on a force analysis of the dust and Newton's laws of motion.Finally,a coupling factor that descibes the interphase interaction is proposed,and the k-Sε-u_(p)model,with clear physical meaning.ligorous mathematical logic,and adequate generality,is dleveloped.Siumulation results and o-site verification show that the k-Sε-u_(p)model not only has high precision,but also reveals the aggregate distribution features of the dust,which are helpful in optimizing the installation position of the detection equipment and imnproving its accuracy and service life.
基金Project(2017YFC0805406)supported by the National Key Research and Development Program of ChinaProjects(51879142,51679123)supported by the National Natural Science Foundation of ChinaProject(2020-KY-04)supported by the Research Fund Program of the State Key Laboratory of Hydroscience and Engineering,China。
文摘Based on the interface shear tests,the macro-and meso-mechanical behaviors of interaction between coral sand and different structure surfaces are studied,in which CCD camera is used to capture digital images to analyze the evolution of the interaction band and a particle analysis apparatus is applied to studying the distribution characteristics of particle morphology.This study proposes four-stage evolution process based on the shear stress−strain curve.During the shear process,coral sand particles slide and rotate within the interaction band,causing the changes in shear stress and vertical displacement.In addition,the effects of structure surface roughness on shear strength,volume change and particle breakage are illustrated that the greater the roughness of slabs is,the larger the shear stress is,the more obvious the contraction effect is and the more the particles break.Furthermore,the change in particle’s 3D morphology during the breakage will change not only their size but also other morphological characteristics with convergence and self-organization.
