The forming of textile reinforcements is an important stage in the manufacturing of textile composite parts with Liquid Composite Molding process.Fiber orientations and part geometry obtained from this stage have sign...The forming of textile reinforcements is an important stage in the manufacturing of textile composite parts with Liquid Composite Molding process.Fiber orientations and part geometry obtained from this stage have significant impact on the subsequent resin injection and final mechanical properties of composite part.Numerical simulation of textile reinforcement forming is in strong demand as it can greatly reduce the time and cost in the determination of the optimized processing parameters,which is the foundation of the low-cost application of composite materials.This review presents the state of the art of forming modeling methods for textile reinforcement and the corresponding experimental characterization methods developed in this field.The microscopic,mesoscopic and macroscopic models are discussed.Studies concerning the simulation of wrinkling are also presented since it is the most common defect occurred in the textile reinforcement forming.Finally,challenges and recommendations on the future research directions for textile reinforcement modeling and experimental characterization are provided.展开更多
This paper describes the BAPAMAN（Binary Actuated Parallel MANipulator） series of parallel manipulators that has been conceived at Laboratory of Robotics and Mechatronics（LARM）. Basic common characteristics of BAPA...This paper describes the BAPAMAN（Binary Actuated Parallel MANipulator） series of parallel manipulators that has been conceived at Laboratory of Robotics and Mechatronics（LARM）. Basic common characteristics of BAPAMAN series are described. In particular, it is outlined the use of a reduced number of active degrees of freedom, the use of design solutions with flexural joints and Shape Memory Alloy（SMA） actuators for achieving miniaturization, cost reduction and easy operation features. Given the peculiarities of BAPAMAN architecture, specific experimental tests have been proposed and carried out with the aim to validate the proposed design and to evaluate the practical operation performance and the characteristics of a built prototype, in particular, in terms of operation and workspace characteristics.展开更多
The electromagnetic properties of high temperature superconductors(HTS)are characterized with the explicit intent to improve their integration in electric power systems.A tape and a coil made of Bismuth Strontium Calc...The electromagnetic properties of high temperature superconductors(HTS)are characterized with the explicit intent to improve their integration in electric power systems.A tape and a coil made of Bismuth Strontium Calcium Copper Oxide(BSCCO)are considered in the presence of electromagnetically active materials in order to mimic properly the electromagnetic environment typical of electrical machines.The characterization consists of the determining the critical current and the AC losses at different values of the frequency and the transport current.The effects induced by the proximity of the active materials are studied and some related experimental issues are analyzedc.展开更多
A tunable two-section amplified feedback laser, which employs an amplifier section as the integrated feedback cavity, is designed and fabricated for dual-mode operation with mode separation of 100 GHz. Detailed simula...A tunable two-section amplified feedback laser, which employs an amplifier section as the integrated feedback cavity, is designed and fabricated for dual-mode operation with mode separation of 100 GHz. Detailed simulations and experimental characterizations on the performance of the laser are presented. Promising dual-mode emission with continuous tuning range over 16 GHz（87.41–103.64 GHz） is experimentally demonstrated.展开更多
We experimentally evaluate and correct the non-equivalence between electrical and radiative heating of solar irradiance absolute radiometer to compensate the systematic error of radiant power measurement at ambient pr...We experimentally evaluate and correct the non-equivalence between electrical and radiative heating of solar irradiance absolute radiometer to compensate the systematic error of radiant power measurement at ambient pressure. A relative difference of the order of 0.08%-0.27% between electrical and radiative heating sensitivities is shown, and the resulting non-equivalence correction factor is calculated. The radiant power measurement equation is modified using the non-equivalence correction factor, a systematic deviation of 0.19% of radiant power measurement is hence eliminated.展开更多
The addition of nanoparticles serves as an effective reinforcement strategy for polymeric coatings,utilizing their unique characteristics as well as extraordinary mechanical,thermal,and electrical properties.The excep...The addition of nanoparticles serves as an effective reinforcement strategy for polymeric coatings,utilizing their unique characteristics as well as extraordinary mechanical,thermal,and electrical properties.The exceptionally high surface-to-volume ratio of nanoparticles imparts remarkable reinforcing potentials,yet it simultaneously gives rise to a prevalent tendency for nanoparticles to agglomerate into clusters within nanocomposites.The agglomeration behavior of the nanoparticles is predominantly influenced by their distinct microstructures and varied weight concentrations.This study investigated the synergistic effects of nanoparticle geometric shape and weight concentration on the dispersion characteristics of nanoparticles and the physical-mechanical performances of nano-reinforced epoxy coatings.Three carbon-based nanoparticles,nanodiamonds(NDs),carbon nanotubes(CNTs),and graphenes(GNPs),were incorporated into epoxy coatings at three weight concentrations(0.5%,1.0%,and 2.0%).The experimental findings reveal that epoxy coatings reinforced with NDs demonstrated the most homogenous dispersion characteristics,lowest viscosity,and reduced porosity among all the nanoparticles,which could be attributed to the spherical geometry shape.Due to the superior physical properties,ND-reinforced nanocomposites displayed the highest abrasion resistance and tensile properties.Specifically,the 1.0wt%ND-reinforced nanocomposites exhibited 60%,52%,and 97%improvements in mass lost,tensile strength,and failure strain,respectively,compared to pure epoxy.Furthermore,the representative volume element(RVE)modeling was employed to validate the experimental results,while highlighting the critical role of nanoparticle agglomeration,orientation,and the presence of voids on the mechanical properties of the nanocomposites.Nano-reinforced epoxy coatings with enhanced mechanical properties are well-suited for application in protective coatings for pipelines,industrial equipment,and automotive parts,where high wear resistance is essential.展开更多
The insertion and extraction of lithium ions in active materials lead to significant volumetric deformation,resulting in stresses that drive the mechanical degradation of these materials.This accumulation of mechanica...The insertion and extraction of lithium ions in active materials lead to significant volumetric deformation,resulting in stresses that drive the mechanical degradation of these materials.This accumulation of mechanical degradation ultimately leads to mechanical failure in lithium-ion batteries(LIB).This paper summarizes the experimental characterization techniques used to observe the mechanical degradation of lithium battery cells,electrodes,and particles across macro,micro,and nano scales.Additionally,the mechanical failure model for LIB that spans from the microscopic to the macroscopic scale has been outlined.Finally,we analyze the current challenges and opportunities,including the standardization of battery measurements,the quantification of mechanical failures,and the correlation between mechanical failures and electrochemical performance.展开更多
This paper introduces a model for characterizing the contact behavior of irregular asperities,transforming it into a superposition of sinusoidal asperity contact behaviors.A new sinusoidal asperity model is developed ...This paper introduces a model for characterizing the contact behavior of irregular asperities,transforming it into a superposition of sinusoidal asperity contact behaviors.A new sinusoidal asperity model is developed for bilin-ear hardening under plane strain conditions.Empirical equations are proposed,considering geometric shapes,tangent modulus,and Young’s modulus.The frequency of asperity height is extracted through Fourier transform for irregular asperities.Contact area and pressure are predicted using the sinusoidal asperity model,and the behavior of irregular asperities is obtained by superimposing those with the first three frequencies.Experimen-tal validation is conducted with milling and knurling-formed asperities,showing good alignment between the model and experimental results.In rough surface models,the proposed irregular asperity model exhibits greater accuracy in predicting contact behavior than a single sinusoidal asperity when interference exceeds 10%of the amplitude.展开更多
Two measurement techniques are investigated to characterize photodetector linearity. A model for the two-tone and three-tone photodetector systems is developed to thoroughly investigate the influences of setup compone...Two measurement techniques are investigated to characterize photodetector linearity. A model for the two-tone and three-tone photodetector systems is developed to thoroughly investigate the influences of setup components on the measurement results. We demonstrate that small bias shifts from the quadrature point of the modulator will induce deviation into measurement results of the two-tone system, and the simulation results correspond well to experimental and calculation results.展开更多
Micro-alloying design of wrought magnesium(Mg) alloys is an important strategy to achieve high mechanical properties at a low cost. In the last two decades, significant progress has been made from both theory and expe...Micro-alloying design of wrought magnesium(Mg) alloys is an important strategy to achieve high mechanical properties at a low cost. In the last two decades, significant progress has been made from both theory and experiment. In the present review, we try to summarize recent advances in micro-alloying design of wrought Mg alloys from both theoretical and pragmatic perspectives, and provide fundamental data required for establishing the relationship between chemical composition and mechanical properties of Mg alloys. We start with theoretical attempts for understanding the mechanical properties of Mg alloys at different scales, by involving first principle calculations,molecular dynamics, cellular automata, and crystal plasticity. Then, the role of alloying elements is discussed for a series of promising Mg alloys such as Mg-Al, Mg-Zn, Mg-RE(rare-earth element), Mg-Sn, and Mg-Ca families.Potential challenges in the micro-alloying design of Mg alloys are highlighted at the end. The review is expected to provide helpful guidance for the intelligent design of novel wrought Mg alloys and inspire more innovative ideas in this field.展开更多
It is remarkable,the recent advances concerning the development of numerical modeling frameworks to simulate the infill panels'seismic behavior.However,there is a lack of experimental data of their mechanical prop...It is remarkable,the recent advances concerning the development of numerical modeling frameworks to simulate the infill panels'seismic behavior.However,there is a lack of experimental data of their mechanical properties,which are of full importance to calibrate the numerical models.The primary objective of this paper is to present an extensive experimental campaign of mechanical characterization tests of infill masonry walls made with three different types of masonry units:lightweight vertical hollow concrete blocks and hollow clay bricks.Four different types of experimental tests were carried out,namely:compression strength tests,diagonal tensile strength tests,and flexural strength tests parallel and perpendicular to the horizontal bed joints.A total amount of 80 tests were carried out and are reported in the present paper.The second objective of this study was to compare the mechanical properties of as-built and existing infill walls.The results presented and discussed herein,will be in terms of strain-stress curves and damages observed within the tests.It was observed a fragile behavior in the panels made with hollow clay horizontal bricks,without propagation of cracks.The plaster increased the flexural strength by 57%.展开更多
The mechanical characterization of a 4×4 air-coupled array of Piezoelectric Micromachined Ultrasonic Transducers(PMUTs)is pre-sented.The experimental campaign consists of three set of experi-mental tests,namely:t...The mechanical characterization of a 4×4 air-coupled array of Piezoelectric Micromachined Ultrasonic Transducers(PMUTs)is pre-sented.The experimental campaign consists of three set of experi-mental tests,namely:topography measurements,small signal dynamic measurements,and vibrometry in the non-linear dynamic regime.The behavior of three different kinds of PMUT are reported.They differ according to the thermo-electrical treatment that has been applied to the piezoelectric material.The presence of the fabrication induced residual stresses is investigated and the treat-ment effect is evaluated in terms of the initial deflected configura-tion.The results reported in this paper represent an experimental mechanical investigation useful for the design of PMUT structures with advanced functionalities in the linear and non-linear regime.展开更多
The breaking of nonpolar N≡N bond of dinitrogen is the biggest dilemma for electrocatalytic nitrogen reduction reaction(NRR)application,driving electron migration between catalysts and N≡N bond(termed“πback-donat...The breaking of nonpolar N≡N bond of dinitrogen is the biggest dilemma for electrocatalytic nitrogen reduction reaction(NRR)application,driving electron migration between catalysts and N≡N bond(termed“πback-donation”process)is crucial for attenuating interfacial energy barrier but still remains challenging.Herein,using density functional theory calculations,we revealed that constructing a unique hetero-dicationic Mo^(4+)-Mo^(6+)pair could effectively activate N≡N bond with a lying-down chemisorption configuration by an asymmetrical“πback-donation”process.As a proof-of-concept demonstration,we synthesized MoO_(2)@MoO_(3)heterostructure with double Mo sites(Mo^(4+)-Mo^(6+)),which are embedded in graphite,for electrochemical nitrogen reduction.Impressively,this hetero-dicationic Mo^(4+)-Mo^(6+)pair catalysts display more excellent catalytic performance with a high NH_(3)yield(60.9μg·h^(-1)·mg^(-1))and Faradic efficiency(23.8%)as NRR catalysts under ambient conditions than pristine MoO_(2)and MoO_(3).Operando characterizations using synchrotron-based spectroscopic techniques identified the emergence of a key^(*)N_(2)Hy intermediate on Mo sites during NRR,which indicates that the Mo sites are active sites and the NRR process tends to follow an associative mechanism.This novel type of hetero-dicationic catalyst has tremendous potential as a new class of transition metal-based catalysts with promising applications in electrocatalysis and catalysts for energy conversion and storage.展开更多
Gas phase fluidized bed processes have been widely applied to polyethylene production.In these processes,the flow,mass transfer,and reaction rate on the microscale and macroscale are strongly coupled because of the mu...Gas phase fluidized bed processes have been widely applied to polyethylene production.In these processes,the flow,mass transfer,and reaction rate on the microscale and macroscale are strongly coupled because of the multiphase and multiscale nature of the fluidization system.Understanding mesoscale phenomena is therefore essential to the quantitative translation of the knowledge obtained from the microscale to the macroscale.This paper reviews the development of ethylene polymerization gas phase processes while focussing on studies regarding mesoscale phenomena.These include experimental characterizations,mathematical modelling and control strategies.Trends and future developments in this field are also discussed.展开更多
Research into the fundamental properties of microcapsules and use of the results to develop a wide variety of products in industries such as printing, fast-moving consumer goods, construction, pharmaceuticals, and agr...Research into the fundamental properties of microcapsules and use of the results to develop a wide variety of products in industries such as printing, fast-moving consumer goods, construction, pharmaceuticals, and agrochemicals is a dynamic and ever-progressing field of study. For microcapsules to be effective in providing protection from harsh environments or delivering large payloads, it is essential to have a good understanding of their properties to enable quality control during formulation, storage, and applications. This review aims to outline the commonly used techniques for determining the physicochemical, struc- tural, and mechanical properties of microcapsules, and highlights the interlinked nature of these three areas with respect to the end-use industrial application. This review provides information on techniques that are well supported in the literature, and also examines microcapsule analytical techniques that will become more prevalent as a result of new technological developments or extensions from other areas of study.展开更多
基金funding support from the Young Fund of Natural Science Foundation of Shaanxi province,China(No.2020JQ-121)Fundamental Research Funds for the Central Universities,China(No.31020190502002)。
文摘The forming of textile reinforcements is an important stage in the manufacturing of textile composite parts with Liquid Composite Molding process.Fiber orientations and part geometry obtained from this stage have significant impact on the subsequent resin injection and final mechanical properties of composite part.Numerical simulation of textile reinforcement forming is in strong demand as it can greatly reduce the time and cost in the determination of the optimized processing parameters,which is the foundation of the low-cost application of composite materials.This review presents the state of the art of forming modeling methods for textile reinforcement and the corresponding experimental characterization methods developed in this field.The microscopic,mesoscopic and macroscopic models are discussed.Studies concerning the simulation of wrinkling are also presented since it is the most common defect occurred in the textile reinforcement forming.Finally,challenges and recommendations on the future research directions for textile reinforcement modeling and experimental characterization are provided.
文摘This paper describes the BAPAMAN（Binary Actuated Parallel MANipulator） series of parallel manipulators that has been conceived at Laboratory of Robotics and Mechatronics（LARM）. Basic common characteristics of BAPAMAN series are described. In particular, it is outlined the use of a reduced number of active degrees of freedom, the use of design solutions with flexural joints and Shape Memory Alloy（SMA） actuators for achieving miniaturization, cost reduction and easy operation features. Given the peculiarities of BAPAMAN architecture, specific experimental tests have been proposed and carried out with the aim to validate the proposed design and to evaluate the practical operation performance and the characteristics of a built prototype, in particular, in terms of operation and workspace characteristics.
文摘The electromagnetic properties of high temperature superconductors(HTS)are characterized with the explicit intent to improve their integration in electric power systems.A tape and a coil made of Bismuth Strontium Calcium Copper Oxide(BSCCO)are considered in the presence of electromagnetically active materials in order to mimic properly the electromagnetic environment typical of electrical machines.The characterization consists of the determining the critical current and the AC losses at different values of the frequency and the transport current.The effects induced by the proximity of the active materials are studied and some related experimental issues are analyzedc.
基金supported in part by the National 973 Project of China(No.2011CB301702)the National 863 Project of China(No.2013AA014202)the National Natural Science Foundation of China(Nos.61201103,61335009,61274045,and 61205031)
文摘A tunable two-section amplified feedback laser, which employs an amplifier section as the integrated feedback cavity, is designed and fabricated for dual-mode operation with mode separation of 100 GHz. Detailed simulations and experimental characterizations on the performance of the laser are presented. Promising dual-mode emission with continuous tuning range over 16 GHz（87.41–103.64 GHz） is experimentally demonstrated.
基金supported by the National Natural Science Foundation of China under Grant No.41227003
文摘We experimentally evaluate and correct the non-equivalence between electrical and radiative heating of solar irradiance absolute radiometer to compensate the systematic error of radiant power measurement at ambient pressure. A relative difference of the order of 0.08%-0.27% between electrical and radiative heating sensitivities is shown, and the resulting non-equivalence correction factor is calculated. The radiant power measurement equation is modified using the non-equivalence correction factor, a systematic deviation of 0.19% of radiant power measurement is hence eliminated.
基金supported by the National Science Foundation(NSF)(No.CMMI-1750316)Pipeline and Hazardous Materials Safety Administration(PHMSA)of U.S.Department of Transportation(No.693JK31950008CAAP).
文摘The addition of nanoparticles serves as an effective reinforcement strategy for polymeric coatings,utilizing their unique characteristics as well as extraordinary mechanical,thermal,and electrical properties.The exceptionally high surface-to-volume ratio of nanoparticles imparts remarkable reinforcing potentials,yet it simultaneously gives rise to a prevalent tendency for nanoparticles to agglomerate into clusters within nanocomposites.The agglomeration behavior of the nanoparticles is predominantly influenced by their distinct microstructures and varied weight concentrations.This study investigated the synergistic effects of nanoparticle geometric shape and weight concentration on the dispersion characteristics of nanoparticles and the physical-mechanical performances of nano-reinforced epoxy coatings.Three carbon-based nanoparticles,nanodiamonds(NDs),carbon nanotubes(CNTs),and graphenes(GNPs),were incorporated into epoxy coatings at three weight concentrations(0.5%,1.0%,and 2.0%).The experimental findings reveal that epoxy coatings reinforced with NDs demonstrated the most homogenous dispersion characteristics,lowest viscosity,and reduced porosity among all the nanoparticles,which could be attributed to the spherical geometry shape.Due to the superior physical properties,ND-reinforced nanocomposites displayed the highest abrasion resistance and tensile properties.Specifically,the 1.0wt%ND-reinforced nanocomposites exhibited 60%,52%,and 97%improvements in mass lost,tensile strength,and failure strain,respectively,compared to pure epoxy.Furthermore,the representative volume element(RVE)modeling was employed to validate the experimental results,while highlighting the critical role of nanoparticle agglomeration,orientation,and the presence of voids on the mechanical properties of the nanocomposites.Nano-reinforced epoxy coatings with enhanced mechanical properties are well-suited for application in protective coatings for pipelines,industrial equipment,and automotive parts,where high wear resistance is essential.
基金funded by the Key Research and Development Project of Guangdong Province(No.2023B0909050004)the National Natural Science Foundation of China(No.12402214).
文摘The insertion and extraction of lithium ions in active materials lead to significant volumetric deformation,resulting in stresses that drive the mechanical degradation of these materials.This accumulation of mechanical degradation ultimately leads to mechanical failure in lithium-ion batteries(LIB).This paper summarizes the experimental characterization techniques used to observe the mechanical degradation of lithium battery cells,electrodes,and particles across macro,micro,and nano scales.Additionally,the mechanical failure model for LIB that spans from the microscopic to the macroscopic scale has been outlined.Finally,we analyze the current challenges and opportunities,including the standardization of battery measurements,the quantification of mechanical failures,and the correlation between mechanical failures and electrochemical performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.12272227 and 11732009).
文摘This paper introduces a model for characterizing the contact behavior of irregular asperities,transforming it into a superposition of sinusoidal asperity contact behaviors.A new sinusoidal asperity model is developed for bilin-ear hardening under plane strain conditions.Empirical equations are proposed,considering geometric shapes,tangent modulus,and Young’s modulus.The frequency of asperity height is extracted through Fourier transform for irregular asperities.Contact area and pressure are predicted using the sinusoidal asperity model,and the behavior of irregular asperities is obtained by superimposing those with the first three frequencies.Experimen-tal validation is conducted with milling and knurling-formed asperities,showing good alignment between the model and experimental results.In rough surface models,the proposed irregular asperity model exhibits greater accuracy in predicting contact behavior than a single sinusoidal asperity when interference exceeds 10%of the amplitude.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61574019,61674018 and 61674020the Fund of State Key Laboratory of Information Photonics and Optical Communicationsthe Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20130005130001
文摘Two measurement techniques are investigated to characterize photodetector linearity. A model for the two-tone and three-tone photodetector systems is developed to thoroughly investigate the influences of setup components on the measurement results. We demonstrate that small bias shifts from the quadrature point of the modulator will induce deviation into measurement results of the two-tone system, and the simulation results correspond well to experimental and calculation results.
基金the financial supports from the National Natural Science Foundation of China (Nos. U1764253, U2037601, 52001037, 51971044, 52101126)the National Defense Basic Scientific Research Program of China, China Postdoctoral Science Foundation (No. 2021M700566)+3 种基金the Natural Science Foundation of Chongqing, China (No. cstc2019jcyjmsxm X0234)Chongqing Science and Technology Commission, China (No. cstc2017zdcyzdzx X0006)Chongqing Scientific and Technological Talents Program, China (No. KJXX2017002)Qinghai Science and Technology Program, China (No. 2018-GX-A1)。
文摘Micro-alloying design of wrought magnesium(Mg) alloys is an important strategy to achieve high mechanical properties at a low cost. In the last two decades, significant progress has been made from both theory and experiment. In the present review, we try to summarize recent advances in micro-alloying design of wrought Mg alloys from both theoretical and pragmatic perspectives, and provide fundamental data required for establishing the relationship between chemical composition and mechanical properties of Mg alloys. We start with theoretical attempts for understanding the mechanical properties of Mg alloys at different scales, by involving first principle calculations,molecular dynamics, cellular automata, and crystal plasticity. Then, the role of alloying elements is discussed for a series of promising Mg alloys such as Mg-Al, Mg-Zn, Mg-RE(rare-earth element), Mg-Sn, and Mg-Ca families.Potential challenges in the micro-alloying design of Mg alloys are highlighted at the end. The review is expected to provide helpful guidance for the intelligent design of novel wrought Mg alloys and inspire more innovative ideas in this field.
基金The authors would like to acknowledge the support financially support by:Project POCI-01-0145-FEDER 007457-CONSTRUCT-Institute of R&D in Structures and Construction funded by FEDER funds through COMPETE2020-Programa Operacional Competi-tividade e Intermacionalizacao(POCD)national funds through FCT-Fundacao para a Cienciaea Tecnologia,namely through the research project P0CI-01-0145-FEDER-016898-ASPASSI-Safety Evaluation and Retroftting of Infill masonry enclosure Walls for Seismic demands.
文摘It is remarkable,the recent advances concerning the development of numerical modeling frameworks to simulate the infill panels'seismic behavior.However,there is a lack of experimental data of their mechanical properties,which are of full importance to calibrate the numerical models.The primary objective of this paper is to present an extensive experimental campaign of mechanical characterization tests of infill masonry walls made with three different types of masonry units:lightweight vertical hollow concrete blocks and hollow clay bricks.Four different types of experimental tests were carried out,namely:compression strength tests,diagonal tensile strength tests,and flexural strength tests parallel and perpendicular to the horizontal bed joints.A total amount of 80 tests were carried out and are reported in the present paper.The second objective of this study was to compare the mechanical properties of as-built and existing infill walls.The results presented and discussed herein,will be in terms of strain-stress curves and damages observed within the tests.It was observed a fragile behavior in the panels made with hollow clay horizontal bricks,without propagation of cracks.The plaster increased the flexural strength by 57%.
基金This work was supported by the ECSEL JOINT UNDERTAKING[826452].
文摘The mechanical characterization of a 4×4 air-coupled array of Piezoelectric Micromachined Ultrasonic Transducers(PMUTs)is pre-sented.The experimental campaign consists of three set of experi-mental tests,namely:topography measurements,small signal dynamic measurements,and vibrometry in the non-linear dynamic regime.The behavior of three different kinds of PMUT are reported.They differ according to the thermo-electrical treatment that has been applied to the piezoelectric material.The presence of the fabrication induced residual stresses is investigated and the treat-ment effect is evaluated in terms of the initial deflected configura-tion.The results reported in this paper represent an experimental mechanical investigation useful for the design of PMUT structures with advanced functionalities in the linear and non-linear regime.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.11975234,11775225,12075243,and 12005227)the Users with Excellence Program of Hefei Science Center CAS(Nos.2021HSC-UE002,2020HSCUE002,and 2019HSC-UE002)+5 种基金the Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2020HSC-CIP013)the Postdoctoral Science Foundation of China(Nos.2019M662202,2020M682041,and 2020TQ0316)the Fundamental Research Funds for the Central Universities(No.WK2310000103)The support from the Ministry of Science and Technology of China(No.2017YFA0204904)is gratefully acknowledgedThe numerical calculations in this paper have been done on the supercomputing system in the Supercomputing Center of University of Science and Technology of ChinaThis work was partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.
文摘The breaking of nonpolar N≡N bond of dinitrogen is the biggest dilemma for electrocatalytic nitrogen reduction reaction(NRR)application,driving electron migration between catalysts and N≡N bond(termed“πback-donation”process)is crucial for attenuating interfacial energy barrier but still remains challenging.Herein,using density functional theory calculations,we revealed that constructing a unique hetero-dicationic Mo^(4+)-Mo^(6+)pair could effectively activate N≡N bond with a lying-down chemisorption configuration by an asymmetrical“πback-donation”process.As a proof-of-concept demonstration,we synthesized MoO_(2)@MoO_(3)heterostructure with double Mo sites(Mo^(4+)-Mo^(6+)),which are embedded in graphite,for electrochemical nitrogen reduction.Impressively,this hetero-dicationic Mo^(4+)-Mo^(6+)pair catalysts display more excellent catalytic performance with a high NH_(3)yield(60.9μg·h^(-1)·mg^(-1))and Faradic efficiency(23.8%)as NRR catalysts under ambient conditions than pristine MoO_(2)and MoO_(3).Operando characterizations using synchrotron-based spectroscopic techniques identified the emergence of a key^(*)N_(2)Hy intermediate on Mo sites during NRR,which indicates that the Mo sites are active sites and the NRR process tends to follow an associative mechanism.This novel type of hetero-dicationic catalyst has tremendous potential as a new class of transition metal-based catalysts with promising applications in electrocatalysis and catalysts for energy conversion and storage.
基金This work was supported by the National Natural Science Foun-dation of China(Grant No.91434205)the National Science Fund for Distinguished Young(Grant No.21525627)the Natural Science Foundation of Zhejiang Province for Young(Grant No.LQ18B060001).
文摘Gas phase fluidized bed processes have been widely applied to polyethylene production.In these processes,the flow,mass transfer,and reaction rate on the microscale and macroscale are strongly coupled because of the multiphase and multiscale nature of the fluidization system.Understanding mesoscale phenomena is therefore essential to the quantitative translation of the knowledge obtained from the microscale to the macroscale.This paper reviews the development of ethylene polymerization gas phase processes while focussing on studies regarding mesoscale phenomena.These include experimental characterizations,mathematical modelling and control strategies.Trends and future developments in this field are also discussed.
文摘Research into the fundamental properties of microcapsules and use of the results to develop a wide variety of products in industries such as printing, fast-moving consumer goods, construction, pharmaceuticals, and agrochemicals is a dynamic and ever-progressing field of study. For microcapsules to be effective in providing protection from harsh environments or delivering large payloads, it is essential to have a good understanding of their properties to enable quality control during formulation, storage, and applications. This review aims to outline the commonly used techniques for determining the physicochemical, struc- tural, and mechanical properties of microcapsules, and highlights the interlinked nature of these three areas with respect to the end-use industrial application. This review provides information on techniques that are well supported in the literature, and also examines microcapsule analytical techniques that will become more prevalent as a result of new technological developments or extensions from other areas of study.
