Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Her...Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Herein,with crystal and atomic structures of the self-assembled PDI revealed from the X-ray diffraction pattern,the electronic structure is theoretically illustrated by the first-principles density functional theory calculations,suggesting the suitable band structure and the direct electronic transition for efficient photocatalytic oxygen evolution over PDI.It is confirmed that the carbonyl O atoms on the conjugation structure serve as the active sites for oxygen evolution reaction by the crystal orbital Hamiltonian group analysis.The calculations of reaction free energy changes indicate that the oxygen evolution reaction should follow the reaction pathway of H_(2)O→^(*)OH→^(*)O→^(*)OOH→^(*)O_(2)with an overpotential of 0.81 V.Through an in-depth theoretical computational analysis in the atomic and electronic structures,the origin of photocatalytic oxygen evolution activity for PDI is well illustrated,which would help the rational design and modification of polymeric photocatalysts for efficient oxygen evolution.展开更多
Effects of ultrasonic bonding parameters on atomic diffusion, microstructure at the Al-Au interface, and shear strength of Al-Au ultrasonic bonding were investigated by the combining experiments and finite element (FE...Effects of ultrasonic bonding parameters on atomic diffusion, microstructure at the Al-Au interface, and shear strength of Al-Au ultrasonic bonding were investigated by the combining experiments and finite element (FE) simulation. The quantitative model of atomic diffusion, which is related to the ultrasonic bonding parameters, time and distance, is established to calculate the atomic diffusion of the Al-Au interface. The maximum relative error between the calculated and experimental fraction of Al atom is 7.35%, indicating high prediction accuracy of this model. During the process of ultrasonic bonding, Au8Al3 is the main intermetallic compound (IMC) at the Al-Au interface. With larger bonding forces, higher ultrasonic powers and longer bonding time, it is more difficult to remove the oxide particles from the Al-Au interface, which hinders the atomic diffusion. Therefore, the complicated stress state and the existence of oxide particles both promotes the formation of holes. The shear strength of Al-Au ultrasonic bonding increases with increasing bonding force, ultrasonic power and bonding time. However, combined with the presence of holes at especial parameters, the optimal ultrasonic bonding parameter is confirmed to be a bonding force of 23 gf, ultrasonic power of 75 mW and bonding time of 21 ms.展开更多
Electrocatalytic reduction of carbon dioxide(CO_(2))to carbon monoxide(CO)is an effective strategy to achieve carbon neutrality.High selective and low-cost catalysts for the electrocatalytic reduction of CO_(2)have re...Electrocatalytic reduction of carbon dioxide(CO_(2))to carbon monoxide(CO)is an effective strategy to achieve carbon neutrality.High selective and low-cost catalysts for the electrocatalytic reduction of CO_(2)have received increasing attention.In contrast to the conventional tube furnace method,the high-temperature shock(HTS)method enables ultra-fast thermal processing,superior atomic efficiency,and a streamlined synthesis protocol,offering a simplified method for the preparation of high-performance single-atom catalysts(SACs).The reports have shown that nickel-based SACs can be synthesized quickly and conveniently using the HTS method,making their application in CO_(2)reduction reactions(CO_(2)RR)a viable and promising avenue for further exploration.In this study,the effect of heating temperature,metal loading and different nitrogen(N)sources on the catalyst morphology,coordination environment and electrocatalytic performance were investigated.Under optimal conditions,0.05Ni-DCD-C-1050 showed excellent performance in reducing CO_(2)to CO,with CO selectivity close to 100%(−0.7 to−1.0 V vs RHE)and current density as high as 130 mA/cm^(2)(−1.1 V vs RHE)in a flow cell under alkaline environment.展开更多
Eleven plant species were collected from the vicinity of lead-battery plant in the city of Gaziantep,Turkey.Lead,cadmium and copper concentrations in the soil and leaves of plants were determined by atomic absorption ...Eleven plant species were collected from the vicinity of lead-battery plant in the city of Gaziantep,Turkey.Lead,cadmium and copper concentrations in the soil and leaves of plants were determined by atomic absorption spectrometry.Lead,Cd and Cu concentrations in the soil samples taken from battery area were found to be in the ranges of 304～602,0.4～0.44 and 31～37 mg·kg-1,respectively.Significantly increased lead concentration up to 2 750 mg·kg-1 was found in the leaves of Eleagnus angustifolia L.plant.The lead concentrations in the other plant leaves taken from 50 m around battery factory followed the order Ailanthus altissima>Morus sp.>Juglans regia L.>Ficus carica L.>Cydonia oblonga Miller>Prunus x domestica L.The plants,Populus nigra L.,Eleagnus angustifolia L.and Salix sp.were found useful for Cd,and the plant,Eleagnus angustifolia L.for Pb,to be considered as potential biomonitor.Especially,leaves of trees and plants taken from the distance of 50 m from battery plant have relatively higher Pb concentrations.Therefore,people who and animals which live in this area and benefit from these soil and plants have vital risks.展开更多
Atomicity is necessary for reliable and secure electronic commerce transaction and to guarantee the participants' interests. An atomic and efficient e-cash (electronic cash) transaction protocol based on the class...Atomicity is necessary for reliable and secure electronic commerce transaction and to guarantee the participants' interests. An atomic and efficient e-cash (electronic cash) transaction protocol based on the classical e-cash scheme is presented. The delivery of digital goods is incorporated into the process of payment in the protocol. Apart from ensuring all three levels of atomicity, the novel protocol features high efficiency and practicability with unfavorable strong assumption removed. Furthermore, the proposed protocol provides non-repudiation proofs for any future disputes. At last, analysis of the atomicity and efficiency is illustrated.展开更多
The hydration film on particle surface plays an important role in bubble-particle adhesion in mineral flotation process. The thicknesses of the hydration films on natural hydrophobic coal and hydrophilic mica surfaces...The hydration film on particle surface plays an important role in bubble-particle adhesion in mineral flotation process. The thicknesses of the hydration films on natural hydrophobic coal and hydrophilic mica surfaces were measured directly by atomic force microscopy (AFM) based on the bending mode of the nominal constant compliance regime in AFM force curve in the present study. Surface and solid-liquid interfacial energies were calculated to explain the forming mechanism of the hydration film and atomic force microscopy data. The results show that there are significant differences in the structure and thickness of hydration films on coal and mica surfaces. Hydration film formed on mica surface with the thickness of 22.5 nm. In contrast, the bend was not detected in the nominal constant compliance regime. The van der Waals and polar interactions between both mica and coal and water molecules are characterized by an attractive effect, while the polar attractive free energy between water and mica (-87.36 mN/m) is significantly larger than that between water and coal (-32.89 mN/m), which leads to a thicker and firmer hydration layer on the mica surface. The interfacial interaction free energy of the coal/water/bubble is greater than that of mica. The polar attractive force is large enough to overcome the repulsive van der Waals force and the low energy barrier of film rupture, achieving coal particle bubble adhesion with a total interfacial free energy of-56.30 mN/m.展开更多
In this paper,a space-time adaptive processing(STAP)method is proposed for the airborne radar with the array amplitude-phase error considered,which is based on atomic norm minimization(ANM).In the conventional ANM-bas...In this paper,a space-time adaptive processing(STAP)method is proposed for the airborne radar with the array amplitude-phase error considered,which is based on atomic norm minimization(ANM).In the conventional ANM-based STAP method,the influence of the array amplitude-phase error is not considered and restrained,which inevitably causes performance deterioration.To solve this problem,the array amplitude-phase error is firstly estimated.Then,by pre-estimating the array amplitude-phase error information,a modified ANM model is built,in which the array amplitude-phase error factor is separated from the clutter response and the clutter covariance matrix(CCM)to improve the estimation accuracy of the CCM.To prove that the atomic norm theory is applicable in the presence of the array amplitude-phase error,the clutter sparsity is analyzed in this paper.Meanwhile,simulation results demonstrate that the proposed method is superior to the state-of-the-art STAP method.Moreover,the measured data is used to verify the effectiveness of the proposed method.展开更多
Interest in preconcentration techniques for the determination of metals at ultratrace levels still continues increasingly because of some disadvantages of flameless atomic absorption spectrometry as well as the high c...Interest in preconcentration techniques for the determination of metals at ultratrace levels still continues increasingly because of some disadvantages of flameless atomic absorption spectrometry as well as the high costs of other sensitive methods in compared to flame atomic absorption spectrometry.In this study,thiol-containing sulfonamide resin was synthesized,characterized and applied as a new sorption material for solid phase extraction of nickel in drinking water samples.After preconcentration procedure,flame atomic absorption spectrometry was used for determinations.Optimum parameters were found to be pH=3.2,contact time=20 min and eluate volume=3 mL.The limit of detection was found to be 0.75 ng·mL-1.The synthesized resin exhibits the superiority in compared to the other adsorption reagents because of the fact that there is no necessity of any complexing reagent,high sorption capacity as well as the relatively fast extraction rate.The Ni concentrations in the studied 21 kind of water samples were found to be in the range of BDL-4.0 ng·mL-1.展开更多
A systematic elaboration is given on atomic and molecular theory problems encountered in dealing with space science and engineering. Three sections are presented in the paper on calculations for gas thermodynamic and ...A systematic elaboration is given on atomic and molecular theory problems encountered in dealing with space science and engineering. Three sections are presented in the paper on calculations for gas thermodynamic and transfer properties, characteristics of the optical radiation from the reentry' bodies, and the interaction between surfaces of man-made satellites and incident particles. Researches on them are much related to the fundamental problems regarding the atomic and molecular theory.展开更多
In this paper, using the MSISE-90 model as the reference atmosphere, we discuss the feasibility and method of deducing the peak densities of the undisturbed atomic oxygen profiles in the MLT region (the mesosphere and...In this paper, using the MSISE-90 model as the reference atmosphere, we discuss the feasibility and method of deducing the peak densities of the undisturbed atomic oxygen profiles in the MLT region (the mesosphere and lower thermosphere region) from OI (557.7 nm) night airglow intersities. The peak densities for different seasons, latitudes and longitudes are deduced from OI (557.7nm) airglow intensities through this expression. We analyze the features of inversion relative errors and discuss the influence of the variations in temperature on inversion errors. The results indicate that all inversion errors are less than 5% except for those at high altitudes in the summer hemisphere. And the impact of the variations in temperature on errors is not significant.展开更多
The design and fabrication processes of a novel scanner with minimized coupling motions for a high-speed atomic force microscope （AFM） were addressed. An appropriate design modification was proposed through the anal...The design and fabrication processes of a novel scanner with minimized coupling motions for a high-speed atomic force microscope （AFM） were addressed. An appropriate design modification was proposed through the analyses of the dynamic characteristics of existing linear motion stages using a dynamic analysis program, Recurdyn. Because the scanning speed of each direction may differ, the linear motion stage for a high-speed scanner was designed to have different resonance frequencies for the modes, with one dominant displacement in the desired directions. This objective was achieved by using one-direction flexure mechanisms for each direction and mounting one stage for fast motion on the other stage for slow motion. This unsymmetrical configuration separated the frequencies of two vibration modes with one dominant displacement in each desired direction, and hence suppressed the coupling between motions in two directions. A pair of actuators was used for each axis to decrease the crosstalk between the two motions and give a sufficient force to actuate the slow motion stage, which carried the fast motion stage, A lossy material, such as grease, was inserted into the flexure hinge to suppress vibration problems that occurred when using an input triangular waveforrn. With these design modifications and the vibration suppression method, a novel scanner with a scanning speed greater than 20 Hz is achieved.展开更多
Formic acid oxidation reaction(FAOR),as the anodic reaction in direct formic acid fuel cells,has attracted much attention but increasing the mass activity and stability of catalysts still face a bottleneck to meet the...Formic acid oxidation reaction(FAOR),as the anodic reaction in direct formic acid fuel cells,has attracted much attention but increasing the mass activity and stability of catalysts still face a bottleneck to meet the requirements of practical applications.In the past decades,researchers developed many strategies to fix these issues by improving the structure of catalysts and the newly raised single atom catalysts(SACs)show the high mass activity and stability in FAOR.This review first summarized the reaction mechanism involved in FAOR.The mass activity as well as stability of catalysts reported in the past five years have been outlined.Moreover,the synthetic strategies to improve the catalytic performance of catalysts are also reviewed in this work.Finally,we proposed the research directions to guide the rational design of new FAOR catalysts in the future.展开更多
应用Realizable k-ε湍流模型和VOF(Volume of Fraction)两相流模型对某压力旋流喷嘴进行数值研究,分析了旋流室锥角、旋流孔角度及喷嘴入口压力变化对雾化锥角、雾化粒径及分布、液滴速度分布等参数的影响。结果表明:雾化锥角受旋流室...应用Realizable k-ε湍流模型和VOF(Volume of Fraction)两相流模型对某压力旋流喷嘴进行数值研究,分析了旋流室锥角、旋流孔角度及喷嘴入口压力变化对雾化锥角、雾化粒径及分布、液滴速度分布等参数的影响。结果表明:雾化锥角受旋流室锥角的影响幅度随压力增大而减小,雾化粒径及分布受旋流室锥角影响不明显,当旋流室锥角为90°时雾化范围广且雾化稳定性好;雾化锥角随旋流孔角度增大先增后减,当角度为45°时雾化锥角最大,平均粒径及其分布更佳;当喷嘴入口压力逐渐增大时,雾化锥角与雾化粒径均逐渐减小,液滴速度区间逐渐缩小,当入口压力达到0.4 MPa时,Sauter粒径及液滴粒径分布趋于稳定,液滴速度分布最为集中。展开更多
基金supported by National Natural Science Foundation of China(No.523B2070,No.52225606).
文摘Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Herein,with crystal and atomic structures of the self-assembled PDI revealed from the X-ray diffraction pattern,the electronic structure is theoretically illustrated by the first-principles density functional theory calculations,suggesting the suitable band structure and the direct electronic transition for efficient photocatalytic oxygen evolution over PDI.It is confirmed that the carbonyl O atoms on the conjugation structure serve as the active sites for oxygen evolution reaction by the crystal orbital Hamiltonian group analysis.The calculations of reaction free energy changes indicate that the oxygen evolution reaction should follow the reaction pathway of H_(2)O→^(*)OH→^(*)O→^(*)OOH→^(*)O_(2)with an overpotential of 0.81 V.Through an in-depth theoretical computational analysis in the atomic and electronic structures,the origin of photocatalytic oxygen evolution activity for PDI is well illustrated,which would help the rational design and modification of polymeric photocatalysts for efficient oxygen evolution.
基金Project(2022YFB3707201) supported by the National Key R&D Program of ChinaProject(U2341254) supported by the Ye Qisun Science Foundation of National Natural Science Foundation of China+1 种基金Projects(0604022GH0202143,0604022SH0201143) supported by the NPU Aoxiang Distinguished Young Scholars,ChinaProject supported by the Funding of Young Top-notch Talent of the National Ten Thousand Talent Program,China。
文摘Effects of ultrasonic bonding parameters on atomic diffusion, microstructure at the Al-Au interface, and shear strength of Al-Au ultrasonic bonding were investigated by the combining experiments and finite element (FE) simulation. The quantitative model of atomic diffusion, which is related to the ultrasonic bonding parameters, time and distance, is established to calculate the atomic diffusion of the Al-Au interface. The maximum relative error between the calculated and experimental fraction of Al atom is 7.35%, indicating high prediction accuracy of this model. During the process of ultrasonic bonding, Au8Al3 is the main intermetallic compound (IMC) at the Al-Au interface. With larger bonding forces, higher ultrasonic powers and longer bonding time, it is more difficult to remove the oxide particles from the Al-Au interface, which hinders the atomic diffusion. Therefore, the complicated stress state and the existence of oxide particles both promotes the formation of holes. The shear strength of Al-Au ultrasonic bonding increases with increasing bonding force, ultrasonic power and bonding time. However, combined with the presence of holes at especial parameters, the optimal ultrasonic bonding parameter is confirmed to be a bonding force of 23 gf, ultrasonic power of 75 mW and bonding time of 21 ms.
基金supported by the National Key R&D Program of China(2024YFB4106400)National Natural Science Foundation of China(22209200,52302331)。
文摘Electrocatalytic reduction of carbon dioxide(CO_(2))to carbon monoxide(CO)is an effective strategy to achieve carbon neutrality.High selective and low-cost catalysts for the electrocatalytic reduction of CO_(2)have received increasing attention.In contrast to the conventional tube furnace method,the high-temperature shock(HTS)method enables ultra-fast thermal processing,superior atomic efficiency,and a streamlined synthesis protocol,offering a simplified method for the preparation of high-performance single-atom catalysts(SACs).The reports have shown that nickel-based SACs can be synthesized quickly and conveniently using the HTS method,making their application in CO_(2)reduction reactions(CO_(2)RR)a viable and promising avenue for further exploration.In this study,the effect of heating temperature,metal loading and different nitrogen(N)sources on the catalyst morphology,coordination environment and electrocatalytic performance were investigated.Under optimal conditions,0.05Ni-DCD-C-1050 showed excellent performance in reducing CO_(2)to CO,with CO selectivity close to 100%(−0.7 to−1.0 V vs RHE)and current density as high as 130 mA/cm^(2)(−1.1 V vs RHE)in a flow cell under alkaline environment.
文摘Eleven plant species were collected from the vicinity of lead-battery plant in the city of Gaziantep,Turkey.Lead,cadmium and copper concentrations in the soil and leaves of plants were determined by atomic absorption spectrometry.Lead,Cd and Cu concentrations in the soil samples taken from battery area were found to be in the ranges of 304～602,0.4～0.44 and 31～37 mg·kg-1,respectively.Significantly increased lead concentration up to 2 750 mg·kg-1 was found in the leaves of Eleagnus angustifolia L.plant.The lead concentrations in the other plant leaves taken from 50 m around battery factory followed the order Ailanthus altissima>Morus sp.>Juglans regia L.>Ficus carica L.>Cydonia oblonga Miller>Prunus x domestica L.The plants,Populus nigra L.,Eleagnus angustifolia L.and Salix sp.were found useful for Cd,and the plant,Eleagnus angustifolia L.for Pb,to be considered as potential biomonitor.Especially,leaves of trees and plants taken from the distance of 50 m from battery plant have relatively higher Pb concentrations.Therefore,people who and animals which live in this area and benefit from these soil and plants have vital risks.
基金This project was supported by the National Natural Science Foundation of China (70031020).
文摘Atomicity is necessary for reliable and secure electronic commerce transaction and to guarantee the participants' interests. An atomic and efficient e-cash (electronic cash) transaction protocol based on the classical e-cash scheme is presented. The delivery of digital goods is incorporated into the process of payment in the protocol. Apart from ensuring all three levels of atomicity, the novel protocol features high efficiency and practicability with unfavorable strong assumption removed. Furthermore, the proposed protocol provides non-repudiation proofs for any future disputes. At last, analysis of the atomicity and efficiency is illustrated.
基金Project(2014BAB01B03)supported by the National Key Technology R&D Program During the 12th Five-Yean Plan of ChinaProject(51774286)supported by the National Natural Science Foundation of ChinaProject(BK20150192)supported by the Natural Science Foundation of Jiaaagsu Province,China
文摘The hydration film on particle surface plays an important role in bubble-particle adhesion in mineral flotation process. The thicknesses of the hydration films on natural hydrophobic coal and hydrophilic mica surfaces were measured directly by atomic force microscopy (AFM) based on the bending mode of the nominal constant compliance regime in AFM force curve in the present study. Surface and solid-liquid interfacial energies were calculated to explain the forming mechanism of the hydration film and atomic force microscopy data. The results show that there are significant differences in the structure and thickness of hydration films on coal and mica surfaces. Hydration film formed on mica surface with the thickness of 22.5 nm. In contrast, the bend was not detected in the nominal constant compliance regime. The van der Waals and polar interactions between both mica and coal and water molecules are characterized by an attractive effect, while the polar attractive free energy between water and mica (-87.36 mN/m) is significantly larger than that between water and coal (-32.89 mN/m), which leads to a thicker and firmer hydration layer on the mica surface. The interfacial interaction free energy of the coal/water/bubble is greater than that of mica. The polar attractive force is large enough to overcome the repulsive van der Waals force and the low energy barrier of film rupture, achieving coal particle bubble adhesion with a total interfacial free energy of-56.30 mN/m.
基金supported by the Fund for Foreign Scholars in University Research and Teaching Programs(the 111 Project)(B18039)。
文摘In this paper,a space-time adaptive processing(STAP)method is proposed for the airborne radar with the array amplitude-phase error considered,which is based on atomic norm minimization(ANM).In the conventional ANM-based STAP method,the influence of the array amplitude-phase error is not considered and restrained,which inevitably causes performance deterioration.To solve this problem,the array amplitude-phase error is firstly estimated.Then,by pre-estimating the array amplitude-phase error information,a modified ANM model is built,in which the array amplitude-phase error factor is separated from the clutter response and the clutter covariance matrix(CCM)to improve the estimation accuracy of the CCM.To prove that the atomic norm theory is applicable in the presence of the array amplitude-phase error,the clutter sparsity is analyzed in this paper.Meanwhile,simulation results demonstrate that the proposed method is superior to the state-of-the-art STAP method.Moreover,the measured data is used to verify the effectiveness of the proposed method.
文摘Interest in preconcentration techniques for the determination of metals at ultratrace levels still continues increasingly because of some disadvantages of flameless atomic absorption spectrometry as well as the high costs of other sensitive methods in compared to flame atomic absorption spectrometry.In this study,thiol-containing sulfonamide resin was synthesized,characterized and applied as a new sorption material for solid phase extraction of nickel in drinking water samples.After preconcentration procedure,flame atomic absorption spectrometry was used for determinations.Optimum parameters were found to be pH=3.2,contact time=20 min and eluate volume=3 mL.The limit of detection was found to be 0.75 ng·mL-1.The synthesized resin exhibits the superiority in compared to the other adsorption reagents because of the fact that there is no necessity of any complexing reagent,high sorption capacity as well as the relatively fast extraction rate.The Ni concentrations in the studied 21 kind of water samples were found to be in the range of BDL-4.0 ng·mL-1.
文摘A systematic elaboration is given on atomic and molecular theory problems encountered in dealing with space science and engineering. Three sections are presented in the paper on calculations for gas thermodynamic and transfer properties, characteristics of the optical radiation from the reentry' bodies, and the interaction between surfaces of man-made satellites and incident particles. Researches on them are much related to the fundamental problems regarding the atomic and molecular theory.
基金Supported by the National Science Foundation of China (40225011, 40336054)National Research Project (G2000078407)project of CAS (KZCX3-SW-217)International Collaboration Research Team Program of the Chinese Academy of Sciencesthe China-Russia Joint Research Center on Space WeatherChinese Academy of Sciences
文摘In this paper, using the MSISE-90 model as the reference atmosphere, we discuss the feasibility and method of deducing the peak densities of the undisturbed atomic oxygen profiles in the MLT region (the mesosphere and lower thermosphere region) from OI (557.7 nm) night airglow intersities. The peak densities for different seasons, latitudes and longitudes are deduced from OI (557.7nm) airglow intensities through this expression. We analyze the features of inversion relative errors and discuss the influence of the variations in temperature on inversion errors. The results indicate that all inversion errors are less than 5% except for those at high altitudes in the summer hemisphere. And the impact of the variations in temperature on errors is not significant.
基金Work(R0A-2007-000-20042-0) partly supported by the Second Stage of Brain Korea 21 Projectspartly by the Korea Science and Engineering Foundation (KOSEF) through the National Research Laboratory Program funded by the Ministry of Science and Technology of Korea
文摘The design and fabrication processes of a novel scanner with minimized coupling motions for a high-speed atomic force microscope （AFM） were addressed. An appropriate design modification was proposed through the analyses of the dynamic characteristics of existing linear motion stages using a dynamic analysis program, Recurdyn. Because the scanning speed of each direction may differ, the linear motion stage for a high-speed scanner was designed to have different resonance frequencies for the modes, with one dominant displacement in the desired directions. This objective was achieved by using one-direction flexure mechanisms for each direction and mounting one stage for fast motion on the other stage for slow motion. This unsymmetrical configuration separated the frequencies of two vibration modes with one dominant displacement in each desired direction, and hence suppressed the coupling between motions in two directions. A pair of actuators was used for each axis to decrease the crosstalk between the two motions and give a sufficient force to actuate the slow motion stage, which carried the fast motion stage, A lossy material, such as grease, was inserted into the flexure hinge to suppress vibration problems that occurred when using an input triangular waveforrn. With these design modifications and the vibration suppression method, a novel scanner with a scanning speed greater than 20 Hz is achieved.
基金Project(22102218)supported by the National Natural Science Foundation of ChinaProject(2022RC1110)supported by the Science and Technology Innovation Program of Hunan Province,ChinaProject(2022QNRC001)supported by the Young Elite Scientists Sponsorship Program by CAST,China。
文摘Formic acid oxidation reaction(FAOR),as the anodic reaction in direct formic acid fuel cells,has attracted much attention but increasing the mass activity and stability of catalysts still face a bottleneck to meet the requirements of practical applications.In the past decades,researchers developed many strategies to fix these issues by improving the structure of catalysts and the newly raised single atom catalysts(SACs)show the high mass activity and stability in FAOR.This review first summarized the reaction mechanism involved in FAOR.The mass activity as well as stability of catalysts reported in the past five years have been outlined.Moreover,the synthetic strategies to improve the catalytic performance of catalysts are also reviewed in this work.Finally,we proposed the research directions to guide the rational design of new FAOR catalysts in the future.
文摘应用Realizable k-ε湍流模型和VOF(Volume of Fraction)两相流模型对某压力旋流喷嘴进行数值研究,分析了旋流室锥角、旋流孔角度及喷嘴入口压力变化对雾化锥角、雾化粒径及分布、液滴速度分布等参数的影响。结果表明:雾化锥角受旋流室锥角的影响幅度随压力增大而减小,雾化粒径及分布受旋流室锥角影响不明显,当旋流室锥角为90°时雾化范围广且雾化稳定性好;雾化锥角随旋流孔角度增大先增后减,当角度为45°时雾化锥角最大,平均粒径及其分布更佳;当喷嘴入口压力逐渐增大时,雾化锥角与雾化粒径均逐渐减小,液滴速度区间逐渐缩小,当入口压力达到0.4 MPa时,Sauter粒径及液滴粒径分布趋于稳定,液滴速度分布最为集中。
