For a long time, it has been generally believed that spin-spin interactions can only exist in a theory where Lorentz symmetry is gauged, and a theory with spin-spin interactions is not perturbatively renormalizable. B...For a long time, it has been generally believed that spin-spin interactions can only exist in a theory where Lorentz symmetry is gauged, and a theory with spin-spin interactions is not perturbatively renormalizable. But this is not true. By studying the motion of a spinning particle in gravitational field, it is found that there exist spin-spin interactions in gauge theory of gravity. Its mechanism is that a spinning particle will generate gravitomagnetic field in space-time, and this gravitomagnetic field will interact with the spin of another particle, which will cause spin-spin interactions. So, spin-spin interactions are transmitted by gravitational field. The form of spin-spin interactions in post Newtonian approximations is deduced. This result can also be deduced from the Papapetrou equation. This kind of interaction will not affect the renormalizability of the theory. The spin-spin interactions will violate the weak equivalence principle, and the violation effects are detectable. An experiment is proposed to detect the effects of the violation of the weak equivalence principle.展开更多
Based on the similarity theory,a new experimentalmethod named Similar ExperimentalMethod for Durability of Concrete(SEMDC)was established.The existing experimentalmethods for durability of concrete were summarized,a...Based on the similarity theory,a new experimentalmethod named Similar ExperimentalMethod for Durability of Concrete(SEMDC)was established.The existing experimentalmethods for durability of concrete were summarized,and the merits and demerits of these experimentalmethods were analyzed.Major factors affecting the durability of concrete were found through literature review.These factors were analyzed and the similarity criteria were established according to the similarity theory,and then the SEMDC was established according to the rules of these criteria.The various influentialfactors of the experimentalmethod were analyzed and the merits and demerits of this new experimentalmethod were discussed.According to SEMDC,changing the geometry shrinkage ratio was the only way to accelerate the test in order to keep the experiment similar to the reality.There were few other parameters which need to be changed in SEMDC,making the test easy to be achieved.According to SEMDC,time shrinkage ratio was the square of geometric shrinkage ratio,so an appropriate increase of the geometric shrinkage ratio could accelerate the test.Finally,an example of experimentaldesign for durability of concrete was devised theoretically base on SEMDC theory.展开更多
The energy relationships among all the elements, by which the magnetostrictive transducers are manufactured, in Finite Element Method (FEM) are analyzed, then the expres- sions of FEM dynamics equations and performanc...The energy relationships among all the elements, by which the magnetostrictive transducers are manufactured, in Finite Element Method (FEM) are analyzed, then the expres- sions of FEM dynamics equations and performances formulas for magnetostrictive transducers are derived. The vibrating modes of the class VII transducer and its shell vibration are calcu- lated theoretically and the results point out that there is a breathing mode and if the transducer works at this mode, the transducer will vibrate with a greater volume speed and source level.展开更多
As it is impossible to assume complete rationality in a social dilemma situation, the assumption of bounded rationality is appropriate. Under the bounded rationality, it would be reasonable to assume that one behaves ...As it is impossible to assume complete rationality in a social dilemma situation, the assumption of bounded rationality is appropriate. Under the bounded rationality, it would be reasonable to assume that one behaves according to the heuristics principle. The group identity effect in a social dilemma situation might be very important in order to attain cooperation. The aim of this study was to clarify how to promote a cooperative behavior by avoiding a social dilemma situation. The group heuristics was taken into account, and it was explored how the group heuristics promotes a cooperative behavior in a social dilemma situation. As a result of a two-person game theory experiment, the group heuristics was found to play an important role in a social dilemma situation, and enhance a cooperative behavior. For the following three cases, the higher cooperation rate was attained at the latter half of the experiment: (a) mutual in-group condition, (b) one-way in-group condition, and (f) one-way unknown condition (in-group). In conclusion, the consciousness of in-group membership might help to promote actively mutual cooperation.展开更多
Microwave remote sensing has become the primary means for sea-ice research, and has been supported by a great deal of field experiments and theoretical studies regarding sea-ice microwave scattering. However, these st...Microwave remote sensing has become the primary means for sea-ice research, and has been supported by a great deal of field experiments and theoretical studies regarding sea-ice microwave scattering. However, these studies have been barely carried in the Bohai Sea. The sea-ice microwave scattering mechanism was first developed for the thin sea ice with slight roughness in the Bohai Sea in the winter of 2012, and included the backscattering coefficients which were measured on the different conditions of three bands(L, C and X), two polarizations(HH and VV), and incident angles of 20° to 60°, using a ground-based scatterometer and the synchronous physical parameters of the sea-ice temperature, density, thickness, salinity, and so on. The theoretical model of the sea-ice electromagnetic scattering is obtained based on these physical parameters. The research regarding the sea-ice microwave scattering mechanism is carried out through two means, which includes the comparison between the field microwave scattering data and the simulation results of the theoretical model, as well as the feature analysis of the four components of the sea-ice electromagnetic scattering. It is revealed that the sea-ice microwave scattering data and the theoretical simulation results vary in the same trend with the incident angles. Also, there is a visible variant in the sensitivity of every component to the different bands.For example, the C and X bands are sensitive to the top surface, the X band is sensitive to the scatterers, and the L and C bands are sensitive to the bottom surface, and so on. It is suggested that the features of the sea-ice surfaces and scatterers can be retrieved by the further research in the future. This experiment can provide an experimental and theoretical foundation for research regarding the sea-ice microwave scattering characteristics in the Bohai Sea.展开更多
Revised September 2013 by T. Damour (IHES, Bures-sur-Yvette, France). Einstein's General Relativity, the current "standard" theory of gravitation, describes gravity as a universal deformation of the Minkowski me...Revised September 2013 by T. Damour (IHES, Bures-sur-Yvette, France). Einstein's General Relativity, the current "standard" theory of gravitation, describes gravity as a universal deformation of the Minkowski metric:展开更多
International and domestic research progress in theory and experiment and applications of the air-to-water sound transmission are presented in this paper. Four classical numerical methods of calculating the underwater...International and domestic research progress in theory and experiment and applications of the air-to-water sound transmission are presented in this paper. Four classical numerical methods of calculating the underwater sound field gener- ated by an airborne source, i.e., the ray theory, the wave solution, the normal-mode theory and the wavenumber integration approach, are introduced. Effects of two special conditions, i.e., the moving airborne source or medium and the rough air-water interface, on the air-to-water sound transmission are reviewed. In experimental studies, the depth and range distributions of the underwater sound field created by different kinds of airborne sources in near-field and far-field, the longitudinal horizontal correlation of underwater sound field and application methods for inverse problems are reviewed.展开更多
Vibrating modes of the manufactured flextensional transducer and its shell are experimentally investigated. The result are consistent with the theoretical calculations. The acoustical performances for the transducer a...Vibrating modes of the manufactured flextensional transducer and its shell are experimentally investigated. The result are consistent with the theoretical calculations. The acoustical performances for the transducer are measured: resonance frequency is 1.16 kHz in the underwater, bandwidth is 680 Hz, mechanical quality factor is 1.71, transmitting current response is 186.1 dB, electromechanical efficiency is 13.1%.展开更多
The ceria-zirconia compound oxide-supported noble metal Pd(Pd@CZ)is widely used in three-way catalyst.Moreover,the surface structure of CZ plays an important role in catalytic activity of Pd.However,how to regulate th...The ceria-zirconia compound oxide-supported noble metal Pd(Pd@CZ)is widely used in three-way catalyst.Moreover,the surface structure of CZ plays an important role in catalytic activity of Pd.However,how to regulate the surface structure of CZ and clarify the structure–activity relationship is still a challenge.In this paper,a strategy is proposed to develop high activity Pd@CZ nanocatalysts by tuning Y doping sites in CZ.The precipitate-deposition method is developed to prepare the novel Ce_(0.485)Zr_(0.485)Y_(0.03)O_(2) composite with surface doping of Y(CZ-Y-S).In addition,the Pd@CZ-Y-S(Pd supported on CZ-Y-S)exhibits superior catalytic activity for HC,CO,and NO oxide,wherein,for CO and C_(3)H_(6) oxidation,the low-temperature activity of Pd@CZ-Y-S is still 20%higher than that of Pd@CZ-Y-B(Y bulk doping)and commercial Pd@CZ after 1000℃/4 h aging.The effect mechanism is further studied by density functional theory(DFT)calculation.Compared with Pd@CZ-Y-B,Pd@CZ-Y-S shows the lower CO oxide reaction energy barriers due to the weaker adsorption strength of O2.The Y surface doping strategy could provide valuable insights for the development of highly efficient Pd@CZ catalyst with extensive applications.展开更多
Ceria-zirconia mixed oxides(CZMO)are widely used in many important catalysis fields.However,pure CZMO is known to have poor thermal stability.In this paper,a strategy was proposed to design Ce_(0.475)Zr_(0.475)M_(0.05...Ceria-zirconia mixed oxides(CZMO)are widely used in many important catalysis fields.However,pure CZMO is known to have poor thermal stability.In this paper,a strategy was proposed to design Ce_(0.475)Zr_(0.475)M_(0.05)O_(2)(M=La,Y,Pr,Nd,Pm,Sm,Eu,Gd,Tb,Er,Lu,and,Yb)oxide surface with high thermal stability by using first-principles molecular dynamics(FPMD)simulation and experiment method.Through the structure stability analysis at different temperatures,the surface energyγas a function of R_(ion)/D_(ave)is identified as a quantitative structure descriptor for analyzing the doping effect of rare earth(RE)elements on the thermal stability of Ce_(0.475)Zr_(0.475)M_(0.05)O_(2).By doping the suitable RE,γcan be adjusted to the optimal range to enhance the thermal stability of Ce_(0.475)Zr_(0.475)M_(0.05)O_(2).With this strategy,it can be predicted that the sequence of thermal stability improvement is Y>La>Gd>Nd>Pr>Pm>Sm>Eu>Tb>Er>Yb>Lu,which was further verified by our experiment results.After thermal treatment at 1100℃for 10 h,the specific surface area(SSA)of aged Y-CZ and La-CZ samples can reach 21.34 and 19.51 m~2/g,which is 63.02%and 49.04%higher than the CZMO sample without doping because the surface doping of Y and La is in favor of inhibiting the surface atoms thermal displacement.In a word,the strategy proposed in this work can be expected to provide a viable way for designing the highly efficient CZMO materials in extensive applications and promoting the usages of the high-abundance rare-earth elements Y and La.展开更多
A low-frequency multi-mode ultrasonic Lamb wave method suitable for character- izing the thickness, the density and the elastic constants of the ultra-thin transversely isotropic laminate composite is presented. The &...A low-frequency multi-mode ultrasonic Lamb wave method suitable for character- izing the thickness, the density and the elastic constants of the ultra-thin transversely isotropic laminate composite is presented. The 'ultra-thin' here means that the thickness of the plate is much less than the wavelength of the ultrasonic wave so that the echoes from the front and back faces of the plate can't be separated in the time domain. The dispersion equations for the low frequency ultrasonic Lamb waves with the propagation directions parallel and vertical to the fiber direction are derived. In conjunction with the least square algorithm method, the secant algorithm is used to estimate the parameters of the ultra-thin fiber-reinforced composite layer. The evaluation errors and the sensitivity of the method to different paramters of the thin composite are analyzed. The technique has been used to characterize the ultra-thin grass fiber reinforced PES composite with thickness down to ten percents of the ultrasonic wavelength. It is observed that the agreement between the nominal and the estimation values is reasonably good.展开更多
文摘For a long time, it has been generally believed that spin-spin interactions can only exist in a theory where Lorentz symmetry is gauged, and a theory with spin-spin interactions is not perturbatively renormalizable. But this is not true. By studying the motion of a spinning particle in gravitational field, it is found that there exist spin-spin interactions in gauge theory of gravity. Its mechanism is that a spinning particle will generate gravitomagnetic field in space-time, and this gravitomagnetic field will interact with the spin of another particle, which will cause spin-spin interactions. So, spin-spin interactions are transmitted by gravitational field. The form of spin-spin interactions in post Newtonian approximations is deduced. This result can also be deduced from the Papapetrou equation. This kind of interaction will not affect the renormalizability of the theory. The spin-spin interactions will violate the weak equivalence principle, and the violation effects are detectable. An experiment is proposed to detect the effects of the violation of the weak equivalence principle.
基金Funded by the National Natural Science Foundation of China(Nos.50808173 and 51208504)
文摘Based on the similarity theory,a new experimentalmethod named Similar ExperimentalMethod for Durability of Concrete(SEMDC)was established.The existing experimentalmethods for durability of concrete were summarized,and the merits and demerits of these experimentalmethods were analyzed.Major factors affecting the durability of concrete were found through literature review.These factors were analyzed and the similarity criteria were established according to the similarity theory,and then the SEMDC was established according to the rules of these criteria.The various influentialfactors of the experimentalmethod were analyzed and the merits and demerits of this new experimentalmethod were discussed.According to SEMDC,changing the geometry shrinkage ratio was the only way to accelerate the test in order to keep the experiment similar to the reality.There were few other parameters which need to be changed in SEMDC,making the test easy to be achieved.According to SEMDC,time shrinkage ratio was the square of geometric shrinkage ratio,so an appropriate increase of the geometric shrinkage ratio could accelerate the test.Finally,an example of experimentaldesign for durability of concrete was devised theoretically base on SEMDC theory.
基金the Scientific Fund of Shaanxi Province and the Youth Scientific Fund ofShaanxi Normal University
文摘The energy relationships among all the elements, by which the magnetostrictive transducers are manufactured, in Finite Element Method (FEM) are analyzed, then the expres- sions of FEM dynamics equations and performances formulas for magnetostrictive transducers are derived. The vibrating modes of the class VII transducer and its shell vibration are calcu- lated theoretically and the results point out that there is a breathing mode and if the transducer works at this mode, the transducer will vibrate with a greater volume speed and source level.
文摘As it is impossible to assume complete rationality in a social dilemma situation, the assumption of bounded rationality is appropriate. Under the bounded rationality, it would be reasonable to assume that one behaves according to the heuristics principle. The group identity effect in a social dilemma situation might be very important in order to attain cooperation. The aim of this study was to clarify how to promote a cooperative behavior by avoiding a social dilemma situation. The group heuristics was taken into account, and it was explored how the group heuristics promotes a cooperative behavior in a social dilemma situation. As a result of a two-person game theory experiment, the group heuristics was found to play an important role in a social dilemma situation, and enhance a cooperative behavior. For the following three cases, the higher cooperation rate was attained at the latter half of the experiment: (a) mutual in-group condition, (b) one-way in-group condition, and (f) one-way unknown condition (in-group). In conclusion, the consciousness of in-group membership might help to promote actively mutual cooperation.
基金The National Science Foundation for Young Scientists of China under contract No.41306193the National Special Research Fund for Non-Profit Marine Sector under of China under contract No.201105016the European Space Agency-Ministry of Science and Technology of the People’s Republic of China(ESA-MOST)Dragon 3 Cooperation Programme under contract No.10501
文摘Microwave remote sensing has become the primary means for sea-ice research, and has been supported by a great deal of field experiments and theoretical studies regarding sea-ice microwave scattering. However, these studies have been barely carried in the Bohai Sea. The sea-ice microwave scattering mechanism was first developed for the thin sea ice with slight roughness in the Bohai Sea in the winter of 2012, and included the backscattering coefficients which were measured on the different conditions of three bands(L, C and X), two polarizations(HH and VV), and incident angles of 20° to 60°, using a ground-based scatterometer and the synchronous physical parameters of the sea-ice temperature, density, thickness, salinity, and so on. The theoretical model of the sea-ice electromagnetic scattering is obtained based on these physical parameters. The research regarding the sea-ice microwave scattering mechanism is carried out through two means, which includes the comparison between the field microwave scattering data and the simulation results of the theoretical model, as well as the feature analysis of the four components of the sea-ice electromagnetic scattering. It is revealed that the sea-ice microwave scattering data and the theoretical simulation results vary in the same trend with the incident angles. Also, there is a visible variant in the sensitivity of every component to the different bands.For example, the C and X bands are sensitive to the top surface, the X band is sensitive to the scatterers, and the L and C bands are sensitive to the bottom surface, and so on. It is suggested that the features of the sea-ice surfaces and scatterers can be retrieved by the further research in the future. This experiment can provide an experimental and theoretical foundation for research regarding the sea-ice microwave scattering characteristics in the Bohai Sea.
文摘Revised September 2013 by T. Damour (IHES, Bures-sur-Yvette, France). Einstein's General Relativity, the current "standard" theory of gravitation, describes gravity as a universal deformation of the Minkowski metric:
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11434012 and 11674349)
文摘International and domestic research progress in theory and experiment and applications of the air-to-water sound transmission are presented in this paper. Four classical numerical methods of calculating the underwater sound field gener- ated by an airborne source, i.e., the ray theory, the wave solution, the normal-mode theory and the wavenumber integration approach, are introduced. Effects of two special conditions, i.e., the moving airborne source or medium and the rough air-water interface, on the air-to-water sound transmission are reviewed. In experimental studies, the depth and range distributions of the underwater sound field created by different kinds of airborne sources in near-field and far-field, the longitudinal horizontal correlation of underwater sound field and application methods for inverse problems are reviewed.
基金the Scientific fund of Shaanxi Province and the Youth Scientific fund of Shaanxi Normal University.
文摘Vibrating modes of the manufactured flextensional transducer and its shell are experimentally investigated. The result are consistent with the theoretical calculations. The acoustical performances for the transducer are measured: resonance frequency is 1.16 kHz in the underwater, bandwidth is 680 Hz, mechanical quality factor is 1.71, transmitting current response is 186.1 dB, electromechanical efficiency is 13.1%.
基金This study was financially supported by the National Natural Science Foundation of China(No.52204376)Youth Foundation of Hebei Province(No.E2022103007)+2 种基金Young Elite Scientists Sponsorship Program by CAST 2021QNRC001High Tech Zone Science and Technology Project of Yanjiao(No.YJXM211211)Youth Fund Project of GRINM(No.G12620223129035).
文摘The ceria-zirconia compound oxide-supported noble metal Pd(Pd@CZ)is widely used in three-way catalyst.Moreover,the surface structure of CZ plays an important role in catalytic activity of Pd.However,how to regulate the surface structure of CZ and clarify the structure–activity relationship is still a challenge.In this paper,a strategy is proposed to develop high activity Pd@CZ nanocatalysts by tuning Y doping sites in CZ.The precipitate-deposition method is developed to prepare the novel Ce_(0.485)Zr_(0.485)Y_(0.03)O_(2) composite with surface doping of Y(CZ-Y-S).In addition,the Pd@CZ-Y-S(Pd supported on CZ-Y-S)exhibits superior catalytic activity for HC,CO,and NO oxide,wherein,for CO and C_(3)H_(6) oxidation,the low-temperature activity of Pd@CZ-Y-S is still 20%higher than that of Pd@CZ-Y-B(Y bulk doping)and commercial Pd@CZ after 1000℃/4 h aging.The effect mechanism is further studied by density functional theory(DFT)calculation.Compared with Pd@CZ-Y-B,Pd@CZ-Y-S shows the lower CO oxide reaction energy barriers due to the weaker adsorption strength of O2.The Y surface doping strategy could provide valuable insights for the development of highly efficient Pd@CZ catalyst with extensive applications.
基金Project supported by China Postdoctoral Science Foundation(2020M680616)Major State Research Development Program of Hebei province(20374202D)。
文摘Ceria-zirconia mixed oxides(CZMO)are widely used in many important catalysis fields.However,pure CZMO is known to have poor thermal stability.In this paper,a strategy was proposed to design Ce_(0.475)Zr_(0.475)M_(0.05)O_(2)(M=La,Y,Pr,Nd,Pm,Sm,Eu,Gd,Tb,Er,Lu,and,Yb)oxide surface with high thermal stability by using first-principles molecular dynamics(FPMD)simulation and experiment method.Through the structure stability analysis at different temperatures,the surface energyγas a function of R_(ion)/D_(ave)is identified as a quantitative structure descriptor for analyzing the doping effect of rare earth(RE)elements on the thermal stability of Ce_(0.475)Zr_(0.475)M_(0.05)O_(2).By doping the suitable RE,γcan be adjusted to the optimal range to enhance the thermal stability of Ce_(0.475)Zr_(0.475)M_(0.05)O_(2).With this strategy,it can be predicted that the sequence of thermal stability improvement is Y>La>Gd>Nd>Pr>Pm>Sm>Eu>Tb>Er>Yb>Lu,which was further verified by our experiment results.After thermal treatment at 1100℃for 10 h,the specific surface area(SSA)of aged Y-CZ and La-CZ samples can reach 21.34 and 19.51 m~2/g,which is 63.02%and 49.04%higher than the CZMO sample without doping because the surface doping of Y and La is in favor of inhibiting the surface atoms thermal displacement.In a word,the strategy proposed in this work can be expected to provide a viable way for designing the highly efficient CZMO materials in extensive applications and promoting the usages of the high-abundance rare-earth elements Y and La.
基金the National Natural Science Foundation of China (No. 69631020) and theOffice of Naval Research of America (00014-93-1-0340).
文摘A low-frequency multi-mode ultrasonic Lamb wave method suitable for character- izing the thickness, the density and the elastic constants of the ultra-thin transversely isotropic laminate composite is presented. The 'ultra-thin' here means that the thickness of the plate is much less than the wavelength of the ultrasonic wave so that the echoes from the front and back faces of the plate can't be separated in the time domain. The dispersion equations for the low frequency ultrasonic Lamb waves with the propagation directions parallel and vertical to the fiber direction are derived. In conjunction with the least square algorithm method, the secant algorithm is used to estimate the parameters of the ultra-thin fiber-reinforced composite layer. The evaluation errors and the sensitivity of the method to different paramters of the thin composite are analyzed. The technique has been used to characterize the ultra-thin grass fiber reinforced PES composite with thickness down to ten percents of the ultrasonic wavelength. It is observed that the agreement between the nominal and the estimation values is reasonably good.