Tetragonal structural(t-NdVO4)nanorod-arrays were fabricated by simple one-pot hydrothermal method.The phase,morphology and microstructure of NdVO4 were characterized by X-ray diffractometer,scanning electron microsco...Tetragonal structural(t-NdVO4)nanorod-arrays were fabricated by simple one-pot hydrothermal method.The phase,morphology and microstructure of NdVO4 were characterized by X-ray diffractometer,scanning electron microscope(SEM),transmission electron microscope(TEM),dispersive X-ray spectrometer(EDS)and selected area electron diffraction(SAED)techniques.t-NdVO4 nanorods are single-crystalline with a length of 100 nm and a diameter of 25 nm,which grow orientally along the direction of(112)crystalline plane and self-assemble to form nanorod-arrays.The results show that Eu^3+-doping interrupts the formation of NdVO4 nanorod-arrays,and then leads to the red-shift of the strongest luminescence emission of Nd3+transition from 4D3/2 state to 4I11/2 and decreases its intensity of the fluorescence emission at 400 nm sharply.The research results have some reference values to optimize the photoluminescence performance of rare earth vanadates.展开更多
A new diabatic potential energy matrix(PEM)of the coupled~^(1)ππ^(*)and~1πσ*states for the~1πσ*-mediated photodissociation of thiophenol was constructed using a neural network(NN)approach.The diabatization of th...A new diabatic potential energy matrix(PEM)of the coupled~^(1)ππ^(*)and~1πσ*states for the~1πσ*-mediated photodissociation of thiophenol was constructed using a neural network(NN)approach.The diabatization of the PEM was specifically achieved by our recent method[Chin.J.Chem.Phys.34,825(2021)],which was based on adiabatic energies without the associated costly derivative couplings.The equation of motion coupled cluster with single and double excitations(EOM-CCSD)method was employed to compute adiabatic energies of two excited states in this work due to its high accuracy,simplicity,and efficiency.The PEM includes three dimensionalities,namely the S-H stretch,C-S-H bend,and C-C-S-H torsional coordinates.The root mean square errors of the NN fitting for the S1 and S2 states are 0.89 and 1.33 me V,respectively,suggesting the high accuracy of the NN method as expected.The calculated lifetimes of the S1 vibronic 00 and31 states are found to be in reasonably good agreement with available theoretical and experimental results,which validates the new EOM-CCSD-based PEM fitted by the NN approach.The combination of the diabatization scheme solely based on the adiabatic energies and the use of EOM-CCSD method makes the construction of reliable diabatic PEM quite simple and efficient.展开更多
In thermoacoustic system,the characteristic of complex compliance of a regenerator has a great influence on energy stored and dissipation of the whole engine.In order to investigate the performance of regenerators wit...In thermoacoustic system,the characteristic of complex compliance of a regenerator has a great influence on energy stored and dissipation of the whole engine.In order to investigate the performance of regenerators with different matrix geometries and materials coupled with different acoustic systems,an experimental measurement and analysis method was presented.By measuring the resonant frequency,the complex compliance and quality factor of five kinds of matrix were experimentally analyzed respectively in the system of loudspeaker-driven thermoacoustic resonator(TAR)with different lengths.The experimental results show that the real part of complex compliance of the regenerator with pin-array has a maximum value among the measured matrixes and its quality factor is the largest(28.222)with the least dissipation factor of 0.035 4.So the pin-array matrix is testified to behave more excellently on the energy conversion than other matrixes.Compared with other factors the complex compliance of a regenerator contributes more to the performance of a thermoacoustic system.展开更多
The present paper assessed a feasibility study to build a small-size anaerobic digester, where a forage legume, （Alfalfa, IVledicago sativa L.）, together with other crops, such as sorghum, could be used. Alfalfa is ...The present paper assessed a feasibility study to build a small-size anaerobic digester, where a forage legume, （Alfalfa, IVledicago sativa L.）, together with other crops, such as sorghum, could be used. Alfalfa is a highly sustainable crop, since it can fix nitrogen, with the benefit of avoiding underground water pollution by nitrates, its residual products are rich with nitrogen, thus improving soil structure and fertility more than popular graminaceous crops such as corn, and it needs little irrigation. All these characteristics make it one of the vegetable species with the lowest energy and water needs for growing. The aims of this feasibility study are： （1） optimization of feedstock in the bio-digester; （2） typology of bio-digester; （3） size of bio-digester in relation with land availability for growing the energy crops; （4） the utilization of bio-gas produced by bio-digester as fuel in combined heat and power systems; （5） disposal of waste-water according to regional and national laws. The final aim of this study is to verify the possibility to develop an alternative economical use of marginal soils in relatively dry areas of central Italy that could be applied in other areas with similar climatic conditions.展开更多
An exact solution for simply-supported laminated beams with material properties variable with temperature under a combination of uniform thermo-load and mechanical loads was investigated,based on the two-dimensional(2...An exact solution for simply-supported laminated beams with material properties variable with temperature under a combination of uniform thermo-load and mechanical loads was investigated,based on the two-dimensional(2-D)thermo-elasticity theory.Firstly,the beam was divided into a series of layers with uniform material properties along the interfaces of the beam.The uniform thermo-load acted on each layer was transformed into a combination of the normal surface forces acted at the two ends and the transverse thermo-load.Secondly,the state space method was employed to obtain the general solutions of displacements and stresses in an arbitrary layer.Thirdly,based on the interfacial continuity conditions between adjacent layers,the relations of displacement and stress components between the top and bottom layers of the beam were recursively derived by use of the transfer-matrix method.The unknowns in the solutions can be solved by the mechanical loads acted on the top and bottom surfaces.The convergence of the present solutions was checked.The comparative study of the present solutions with the Timoshenko’s solutions and the finite element(FE)solutions was carried out.The effects of material properties variable with temperature on the thermo-elastic behavior of laminated beams were discussed in detail.展开更多
基金Project(51202066)supported by the National Natural Science Foundation of ChinaProject(NCET-13-0784)supported by the Program for New Century Excellent Talents of the Education Ministry,China。
文摘Tetragonal structural(t-NdVO4)nanorod-arrays were fabricated by simple one-pot hydrothermal method.The phase,morphology and microstructure of NdVO4 were characterized by X-ray diffractometer,scanning electron microscope(SEM),transmission electron microscope(TEM),dispersive X-ray spectrometer(EDS)and selected area electron diffraction(SAED)techniques.t-NdVO4 nanorods are single-crystalline with a length of 100 nm and a diameter of 25 nm,which grow orientally along the direction of(112)crystalline plane and self-assemble to form nanorod-arrays.The results show that Eu^3+-doping interrupts the formation of NdVO4 nanorod-arrays,and then leads to the red-shift of the strongest luminescence emission of Nd3+transition from 4D3/2 state to 4I11/2 and decreases its intensity of the fluorescence emission at 400 nm sharply.The research results have some reference values to optimize the photoluminescence performance of rare earth vanadates.
基金supported by the National Natural Science Foundation of China(No.22073073)the Startup Foundation of Northwest UniversityThe Double First-Class University Construction Project of Northwest University。
文摘A new diabatic potential energy matrix(PEM)of the coupled~^(1)ππ^(*)and~1πσ*states for the~1πσ*-mediated photodissociation of thiophenol was constructed using a neural network(NN)approach.The diabatization of the PEM was specifically achieved by our recent method[Chin.J.Chem.Phys.34,825(2021)],which was based on adiabatic energies without the associated costly derivative couplings.The equation of motion coupled cluster with single and double excitations(EOM-CCSD)method was employed to compute adiabatic energies of two excited states in this work due to its high accuracy,simplicity,and efficiency.The PEM includes three dimensionalities,namely the S-H stretch,C-S-H bend,and C-C-S-H torsional coordinates.The root mean square errors of the NN fitting for the S1 and S2 states are 0.89 and 1.33 me V,respectively,suggesting the high accuracy of the NN method as expected.The calculated lifetimes of the S1 vibronic 00 and31 states are found to be in reasonably good agreement with available theoretical and experimental results,which validates the new EOM-CCSD-based PEM fitted by the NN approach.The combination of the diabatization scheme solely based on the adiabatic energies and the use of EOM-CCSD method makes the construction of reliable diabatic PEM quite simple and efficient.
基金Projects(50676068,50576024)supported by the National Natural Science Foundation of China
文摘In thermoacoustic system,the characteristic of complex compliance of a regenerator has a great influence on energy stored and dissipation of the whole engine.In order to investigate the performance of regenerators with different matrix geometries and materials coupled with different acoustic systems,an experimental measurement and analysis method was presented.By measuring the resonant frequency,the complex compliance and quality factor of five kinds of matrix were experimentally analyzed respectively in the system of loudspeaker-driven thermoacoustic resonator(TAR)with different lengths.The experimental results show that the real part of complex compliance of the regenerator with pin-array has a maximum value among the measured matrixes and its quality factor is the largest(28.222)with the least dissipation factor of 0.035 4.So the pin-array matrix is testified to behave more excellently on the energy conversion than other matrixes.Compared with other factors the complex compliance of a regenerator contributes more to the performance of a thermoacoustic system.
文摘The present paper assessed a feasibility study to build a small-size anaerobic digester, where a forage legume, （Alfalfa, IVledicago sativa L.）, together with other crops, such as sorghum, could be used. Alfalfa is a highly sustainable crop, since it can fix nitrogen, with the benefit of avoiding underground water pollution by nitrates, its residual products are rich with nitrogen, thus improving soil structure and fertility more than popular graminaceous crops such as corn, and it needs little irrigation. All these characteristics make it one of the vegetable species with the lowest energy and water needs for growing. The aims of this feasibility study are： （1） optimization of feedstock in the bio-digester; （2） typology of bio-digester; （3） size of bio-digester in relation with land availability for growing the energy crops; （4） the utilization of bio-gas produced by bio-digester as fuel in combined heat and power systems; （5） disposal of waste-water according to regional and national laws. The final aim of this study is to verify the possibility to develop an alternative economical use of marginal soils in relatively dry areas of central Italy that could be applied in other areas with similar climatic conditions.
基金Project(2012CB026205)supported by the National Basic Research Program of ChinaProjects(51608264,51778289)supported by the National Natural Science Foundation of ChinaProject(2014Y01)supported by the Transportation Science and Technology Project of Jiangsu Province,China
文摘An exact solution for simply-supported laminated beams with material properties variable with temperature under a combination of uniform thermo-load and mechanical loads was investigated,based on the two-dimensional(2-D)thermo-elasticity theory.Firstly,the beam was divided into a series of layers with uniform material properties along the interfaces of the beam.The uniform thermo-load acted on each layer was transformed into a combination of the normal surface forces acted at the two ends and the transverse thermo-load.Secondly,the state space method was employed to obtain the general solutions of displacements and stresses in an arbitrary layer.Thirdly,based on the interfacial continuity conditions between adjacent layers,the relations of displacement and stress components between the top and bottom layers of the beam were recursively derived by use of the transfer-matrix method.The unknowns in the solutions can be solved by the mechanical loads acted on the top and bottom surfaces.The convergence of the present solutions was checked.The comparative study of the present solutions with the Timoshenko’s solutions and the finite element(FE)solutions was carried out.The effects of material properties variable with temperature on the thermo-elastic behavior of laminated beams were discussed in detail.
