The interaction of nitrilotriacetic acid （NTA） and iminodiacetic acid （IDA） with tungsten（VI） （pH 7.5） and molybdenum（VI） （pH 6.00） has been studied in aqueous solutions at 25℃, and different ionic streng...The interaction of nitrilotriacetic acid （NTA） and iminodiacetic acid （IDA） with tungsten（VI） （pH 7.5） and molybdenum（VI） （pH 6.00） has been studied in aqueous solutions at 25℃, and different ionic strengths （0.1 〈 1 （mol dm^-3） 〈 1.0 for NaClO4） by a combination of potentiometric and UV spectroscopic（260-270 nm） measurements. Dependence on ionic strength was taken into account by using the Bronsted-Guggenheim-Scatchard specific ion interaction theory （SIT） and parabolic model. The data included in this work, together with some previously published data, make it possible to calculate parameters for dependence on ionic strength by using the aforementioned models.展开更多
On basis of test information, the research performed analysis on water production function models of two crops, which indicated that water model of crops in whole growth stage and water model of crops indifferent grow...On basis of test information, the research performed analysis on water production function models of two crops, which indicated that water model of crops in whole growth stage and water model of crops indifferent growth stages have consistency as well as differences, providing references for optimization of irrigation water. Meanwhile, the research analyzed the deficiency of optimization on irrigation water for crops just by Jensen model.展开更多
Determining earth pressure on jacked pipes is essential for ensuring lining safety and calculating jacking force,especially for deep-buried pipes.To better reflect the soil arching effect resulting from the excavation...Determining earth pressure on jacked pipes is essential for ensuring lining safety and calculating jacking force,especially for deep-buried pipes.To better reflect the soil arching effect resulting from the excavation of rectangular jacked pipes and the distribution of the earth pressure on jacked pipes,we present an analytical solution for predicting the vertical earth pressure on deep-buried rectangular pipe jacking tunnels,incorporating the tunnelling-induced ground loss distribution.Our proposed analytical model consists of the upper multi-layer parabolic soil arch and the lower friction arch.The key parameters(i.e.,width and height of friction arch B and height of parabolic soil arch H 1)are determined according to the existing research,and an analytical solution for K l is derived based on the distribution characteristics of the principal stress rotation angle.With consideration for the transition effect of the mechanical characteristics of the parabolic arch zone,an analytical solution for soil load transfer is derived.The prediction results of our analytical solution are compared with tests and simulation results to validate the effectiveness of the proposed analytical solution.Finally,the effects of different parameters on the soil pressure are discussed.展开更多
We obtain the H?lder continuity and joint H?lder continuity in space and time for the random field solution to the parabolic Anderson equation ■ in d-dimensional space, where ■ is a mean zero Gaussian noise with tem...We obtain the H?lder continuity and joint H?lder continuity in space and time for the random field solution to the parabolic Anderson equation ■ in d-dimensional space, where ■ is a mean zero Gaussian noise with temporal covariance γ0 and spatial covariance given by a spectral density μ(ξ). We assume that ■ and ■ , where αi, i = 1, · · ·, d(or α) can take negative value.展开更多
In this paper, we consider the continuous parabolic Anderson model with a logcorrelated Gaussian field, and obtain the precise quenched long-time asymptotics and spatial asymptotics. To overcome the difficulties arisi...In this paper, we consider the continuous parabolic Anderson model with a logcorrelated Gaussian field, and obtain the precise quenched long-time asymptotics and spatial asymptotics. To overcome the difficulties arising from the log-correlated Gaussian field in the proof of the lower bound of the spatial asymptotics, we first establish the relation between quenched long-time asymptotics and spatial asymptotics, and then get the lower bound of the spatial asymptotics through the lower bound of the quenched long-time asymptotics.展开更多
The estimation of lower atmospheric refractivity from radar sea clutter（RFC） is a complicated nonlinear optimization problem.This paper deals with the RFC problem in a Bayesian framework.It uses the unbiased Markov ...The estimation of lower atmospheric refractivity from radar sea clutter（RFC） is a complicated nonlinear optimization problem.This paper deals with the RFC problem in a Bayesian framework.It uses the unbiased Markov Chain Monte Carlo（MCMC） sampling technique,which can provide accurate posterior probability distributions of the estimated refractivity parameters by using an electromagnetic split-step fast Fourier transform terrain parabolic equation propagation model within a Bayesian inversion framework.In contrast to the global optimization algorithm,the Bayesian-MCMC can obtain not only the approximate solutions,but also the probability distributions of the solutions,that is,uncertainty analyses of solutions.The Bayesian-MCMC algorithm is implemented on the simulation radar sea-clutter data and the real radar seaclutter data.Reference data are assumed to be simulation data and refractivity profiles are obtained using a helicopter.The inversion algorithm is assessed（i） by comparing the estimated refractivity profiles from the assumed simulation and the helicopter sounding data;（ii） the one-dimensional（1D） and two-dimensional（2D） posterior probability distribution of solutions.展开更多
Magnetic properties of conventional grain-oriented electrical steel sheets are different in various directions. In the present paper, Epstein standard samples were cut with different angles to rolling direction, and t...Magnetic properties of conventional grain-oriented electrical steel sheets are different in various directions. In the present paper, Epstein standard samples were cut with different angles to rolling direction, and the corresponding magnetic properties of samples were tested. Results show that the hard magnetization direction to the rolling direction is around 60°. Conventional elliptical models are not accurate to simulate permeability at all magnetic intensities, and parabolic and hybrid models with high accuracy are proposed to simulate relations between permeability and magnetization direction. When magnetic intensity is no less than 10 000 A/m, hybrid model can be used, and when magnetic intensity is less than 10 000 A/m, parabolic model should be applied. Two-stage relation model of permeability and magnetization angles is of significance in improving the accuracy of electromagnetic engineering calculations of electrical steel and can be applied in industrial applications.展开更多
The quadratic rheology model considers the yield stress,viscous stress,turbulent stress and disperse stress,so it is used in this study to derive the velocity profile of debris flows.The quadratic model with the parab...The quadratic rheology model considers the yield stress,viscous stress,turbulent stress and disperse stress,so it is used in this study to derive the velocity profile of debris flows.The quadratic model with the parabolic eddy viscosity was numerically solved,and an analytical solution was derived for the quadratic model with a constant eddy viscosity.These two solutions were compared with the Arai-Takahashi model that excluded the viscous stress and the yield stress.The three models were tested by using 17 experiment cases of debris flows over rigid beds.The results prove that the quadratic model with parabolic and constant eddy viscosities is applicable to muddy and granular flows,whereas the Arai-Takahashi model tends to overestimate the flow velocity near the water surface if a plug-like layer exists.In addition,the von Karman constant and the zero-velocity elevation in the three models are related to sediment concentration.The von Karman constant decreases first and then increases as the sediment concentration increases.The zero-velocity elevation is below the bed surface,likely due to the invalidity of the non-slip boundary condition for the debris flows over fixed beds.展开更多
This study proposed a strategy for effectively diminishing the carrier concentration in Cu_(2)Te by introducing graphene sheets,Based on thermoelectric property measurements and single parabolic band modeling,the inco...This study proposed a strategy for effectively diminishing the carrier concentration in Cu_(2)Te by introducing graphene sheets,Based on thermoelectric property measurements and single parabolic band modeling,the incorporated graphene effectively reduced the carrier concentration,not only enhancing the thermoelectric performance of the Cu_(2)Te/graphene composite but also substantially improving its figure of merit up to ~1.47 at 1000 K,which is 268% higher than that of pristine Cu_(2)Te,This study gives an insight into the control of carrier concentration and thermoelectric properties in Cu_(2)Te,and it could be extended to other copper chalcogenides for excellent thermoelectrics.展开更多
The differential cross section for an electron Raman scattering process in a semiconductor GaAs/AlGaAs double quantum well wire is calculated,and expressions for the electronic states are presented.The system is model...The differential cross section for an electron Raman scattering process in a semiconductor GaAs/AlGaAs double quantum well wire is calculated,and expressions for the electronic states are presented.The system is modeled by considering T = 0 K and also with a single parabolic conduction band,which is split into a subband system due to the confinement.The gain and differential cross-section for an electron Raman scattering process are obtained.In addition,the emission spectra for several scattering configurations are discussed,and interpretations of the singularities found in the spectra are given.The electron Raman scattering studied here can be used to provide direct information about the efficiency of the lasers.展开更多
In this paper, we study some ergodic theorems of a class of linear systems of interacting diffusions, which is a parabolic Anderson model. First, under the assumption that the transition kernel a = （a（i,j））i,j∈s ...In this paper, we study some ergodic theorems of a class of linear systems of interacting diffusions, which is a parabolic Anderson model. First, under the assumption that the transition kernel a = （a（i,j））i,j∈s is doubly stochastic, we obtain the long-time convergence to an invariant probability measure Vh starting from a bounded a-harmonic function h based on self-duality property, and then we show the convergence to the invariant probability measure Uh holds for a broad class of initial distributions. Second, if （a（i, j））i,j∈s is transient and symmetric, and the diffusion parameter c remains below a threshold, we are able to determine the set of extremal invariant probability measures with finite second moment. Finally, in the case that the transition kernel （a（i,j））i,j∈s is doubly stochastic and satisfies Case I （see Case I in [Shiga, T.： An interacting system in population genetics. J. Math. Kyoto Univ., 20, 213-242 （1980）]）, we show that this parabolic Anderson model locally dies out independent of the diffusion parameter c.展开更多
Due to the complex interplay between composition,synthesis parameters and the performance of thermoelectric materials,the optimization of thermoelectric materials needs to be complemented by modelling.A relatively sim...Due to the complex interplay between composition,synthesis parameters and the performance of thermoelectric materials,the optimization of thermoelectric materials needs to be complemented by modelling.A relatively simple and thus popular approach is the so called single parabolic band model,which allows for an efficient optimization of the material properties and a benchmarking of different materials based on relatively few,well available experimental results.As complex band structures are common for high performance materials,single parabolic band modelling is also employed with apparent success for material systems where the underlying assumptions are not well fulfilled.In order to assess the validity of a single parabolic band analysis for such systems,the thermoelectric properties for two model systems are calculated:one with a single band that is twofold degenerate and one with a light and a heavy band.Even if the density of states masses and the scattering potentials are kept identical,the transport properties and in particular the Hall coefficients differ significantly,which leads to an incorrectly determined carrier concentration.As the carrier concentration is the base for the single parabolic band analysis,all the quantities obtained from it(optimum carrier concentration,effective mass,deformation potential)are determined incorrectly as well.展开更多
For the project of pipe jacking in cohesionless soil,it is key to determine the vertical load on jacked pipe so as to predict the jacking force accurately.In this paper,a new parabolic soil arching model was proposed ...For the project of pipe jacking in cohesionless soil,it is key to determine the vertical load on jacked pipe so as to predict the jacking force accurately.In this paper,a new parabolic soil arching model was proposed to calculate the vertical load on jacked pipe.This proposed analytical model was composed of parabolic soil arching zone,parabola-typed collapse zone and friction arch zone.Combined with existing literature,the key parameters(i.e.,height of parabolic soil arching,horizontal pressure coefficient and width and height of friction arch)were determined.In addition,considering that the trajectory of major stress is parabola,the formula of horizontal pressure coefficient was deduced in the friction arch.The parabolic soil arching zone is assumed as a three-hinged arch with reasonable arch axis,and the formula of load transfer was derived considering the transition effect of parabolic soil arching.The results of experiment,theoretical models and numerical model were adopted to verify the proposed analytical model.Finally,the influence of the key parameters on the vertical load on jacked pipe were also discussed in detail.This work provides a meaningful reference for evaluating the vertical load on jacked pipe for design of pipe jacking.展开更多
文摘The interaction of nitrilotriacetic acid （NTA） and iminodiacetic acid （IDA） with tungsten（VI） （pH 7.5） and molybdenum（VI） （pH 6.00） has been studied in aqueous solutions at 25℃, and different ionic strengths （0.1 〈 1 （mol dm^-3） 〈 1.0 for NaClO4） by a combination of potentiometric and UV spectroscopic（260-270 nm） measurements. Dependence on ionic strength was taken into account by using the Bronsted-Guggenheim-Scatchard specific ion interaction theory （SIT） and parabolic model. The data included in this work, together with some previously published data, make it possible to calculate parameters for dependence on ionic strength by using the aforementioned models.
文摘On basis of test information, the research performed analysis on water production function models of two crops, which indicated that water model of crops in whole growth stage and water model of crops indifferent growth stages have consistency as well as differences, providing references for optimization of irrigation water. Meanwhile, the research analyzed the deficiency of optimization on irrigation water for crops just by Jensen model.
基金Project(2022YJS073)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2024YFE0198500)supported by the National Key Research and Development Program of China:Intergovernmental International Science and Technology Innovation CooperationProject(U2469207)supported by the National Natural Science Foundation Railway Innovation and Development Joint Fund Project,China。
文摘Determining earth pressure on jacked pipes is essential for ensuring lining safety and calculating jacking force,especially for deep-buried pipes.To better reflect the soil arching effect resulting from the excavation of rectangular jacked pipes and the distribution of the earth pressure on jacked pipes,we present an analytical solution for predicting the vertical earth pressure on deep-buried rectangular pipe jacking tunnels,incorporating the tunnelling-induced ground loss distribution.Our proposed analytical model consists of the upper multi-layer parabolic soil arch and the lower friction arch.The key parameters(i.e.,width and height of friction arch B and height of parabolic soil arch H 1)are determined according to the existing research,and an analytical solution for K l is derived based on the distribution characteristics of the principal stress rotation angle.With consideration for the transition effect of the mechanical characteristics of the parabolic arch zone,an analytical solution for soil load transfer is derived.The prediction results of our analytical solution are compared with tests and simulation results to validate the effectiveness of the proposed analytical solution.Finally,the effects of different parameters on the soil pressure are discussed.
基金supported by an NSERC granta startup fund of University of Albertasupported by Martin Hairer’s Leverhulme Trust leadership award
文摘We obtain the H?lder continuity and joint H?lder continuity in space and time for the random field solution to the parabolic Anderson equation ■ in d-dimensional space, where ■ is a mean zero Gaussian noise with temporal covariance γ0 and spatial covariance given by a spectral density μ(ξ). We assume that ■ and ■ , where αi, i = 1, · · ·, d(or α) can take negative value.
基金supported by the National Natural Science Foundation of China (12201282)the Institute of Meteorological Big Data-Digital Fujian and the Fujian Key Laboratory of Data Science and Statistics (2020L0705)the Education Department of Fujian Province (JAT200325)。
文摘In this paper, we consider the continuous parabolic Anderson model with a logcorrelated Gaussian field, and obtain the precise quenched long-time asymptotics and spatial asymptotics. To overcome the difficulties arising from the log-correlated Gaussian field in the proof of the lower bound of the spatial asymptotics, we first establish the relation between quenched long-time asymptotics and spatial asymptotics, and then get the lower bound of the spatial asymptotics through the lower bound of the quenched long-time asymptotics.
基金Project supported by the National Natural Science Foundation of China (Grant No. 41105013)the National Natural Science Foundation of Jiangsu Province,China (Grant No. BK2011122)+1 种基金the Open Issue Foundation of Key Laboratory of Meteorological Disaster of Ministry of Education,China (Grant No. KLME1109)the City Meteorological Scientific Research Fund,China (Grant No. IUMKY&UMRF201111)
文摘The estimation of lower atmospheric refractivity from radar sea clutter（RFC） is a complicated nonlinear optimization problem.This paper deals with the RFC problem in a Bayesian framework.It uses the unbiased Markov Chain Monte Carlo（MCMC） sampling technique,which can provide accurate posterior probability distributions of the estimated refractivity parameters by using an electromagnetic split-step fast Fourier transform terrain parabolic equation propagation model within a Bayesian inversion framework.In contrast to the global optimization algorithm,the Bayesian-MCMC can obtain not only the approximate solutions,but also the probability distributions of the solutions,that is,uncertainty analyses of solutions.The Bayesian-MCMC algorithm is implemented on the simulation radar sea-clutter data and the real radar seaclutter data.Reference data are assumed to be simulation data and refractivity profiles are obtained using a helicopter.The inversion algorithm is assessed（i） by comparing the estimated refractivity profiles from the assumed simulation and the helicopter sounding data;（ii） the one-dimensional（1D） and two-dimensional（2D） posterior probability distribution of solutions.
基金National Natural Science Foundation of China(51174057,51274062)the National High Technology Research and Development Program(2012AA03A503)
文摘Magnetic properties of conventional grain-oriented electrical steel sheets are different in various directions. In the present paper, Epstein standard samples were cut with different angles to rolling direction, and the corresponding magnetic properties of samples were tested. Results show that the hard magnetization direction to the rolling direction is around 60°. Conventional elliptical models are not accurate to simulate permeability at all magnetic intensities, and parabolic and hybrid models with high accuracy are proposed to simulate relations between permeability and magnetization direction. When magnetic intensity is no less than 10 000 A/m, hybrid model can be used, and when magnetic intensity is less than 10 000 A/m, parabolic model should be applied. Two-stage relation model of permeability and magnetization angles is of significance in improving the accuracy of electromagnetic engineering calculations of electrical steel and can be applied in industrial applications.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(No.2019QZKK0902)National Natural Science Foundation of China(No.41601004 and 41702369)Scientific and Technological Project in Henan Province(No.212102310055).
文摘The quadratic rheology model considers the yield stress,viscous stress,turbulent stress and disperse stress,so it is used in this study to derive the velocity profile of debris flows.The quadratic model with the parabolic eddy viscosity was numerically solved,and an analytical solution was derived for the quadratic model with a constant eddy viscosity.These two solutions were compared with the Arai-Takahashi model that excluded the viscous stress and the yield stress.The three models were tested by using 17 experiment cases of debris flows over rigid beds.The results prove that the quadratic model with parabolic and constant eddy viscosities is applicable to muddy and granular flows,whereas the Arai-Takahashi model tends to overestimate the flow velocity near the water surface if a plug-like layer exists.In addition,the von Karman constant and the zero-velocity elevation in the three models are related to sediment concentration.The von Karman constant decreases first and then increases as the sediment concentration increases.The zero-velocity elevation is below the bed surface,likely due to the invalidity of the non-slip boundary condition for the debris flows over fixed beds.
基金supported by the MSIT(Ministry of Science and ICT),Korea,under the ITRC(Information Technology Research Center)support program supervised by the IITP(Institute of Information&Communications Technology Planning&Evaluation)(ⅡTP-2020-2020-0-01655)funded and conducted under the Competency Development Program for Industry Specialists of the Korean Ministry of Trade,Industry and Energy(MOTIE),operated by Korea Institute for Advancement of Technology(KIAT)(No.P0012453,Next-generation Display Expert Training Project for Innovation Process and Equipment,Materials Engineers)。
文摘This study proposed a strategy for effectively diminishing the carrier concentration in Cu_(2)Te by introducing graphene sheets,Based on thermoelectric property measurements and single parabolic band modeling,the incorporated graphene effectively reduced the carrier concentration,not only enhancing the thermoelectric performance of the Cu_(2)Te/graphene composite but also substantially improving its figure of merit up to ~1.47 at 1000 K,which is 268% higher than that of pristine Cu_(2)Te,This study gives an insight into the control of carrier concentration and thermoelectric properties in Cu_(2)Te,and it could be extended to other copper chalcogenides for excellent thermoelectrics.
文摘The differential cross section for an electron Raman scattering process in a semiconductor GaAs/AlGaAs double quantum well wire is calculated,and expressions for the electronic states are presented.The system is modeled by considering T = 0 K and also with a single parabolic conduction band,which is split into a subband system due to the confinement.The gain and differential cross-section for an electron Raman scattering process are obtained.In addition,the emission spectra for several scattering configurations are discussed,and interpretations of the singularities found in the spectra are given.The electron Raman scattering studied here can be used to provide direct information about the efficiency of the lasers.
基金The first author is supported by National Natural Science Foundation of China (Grant Nos. 10531070,11071008)SRF for ROCS,Science and Technology Ministry 973 project (2006CB805900)the Doctoral Program Foundation of the Ministry of Education,China
文摘In this paper, we study some ergodic theorems of a class of linear systems of interacting diffusions, which is a parabolic Anderson model. First, under the assumption that the transition kernel a = （a（i,j））i,j∈s is doubly stochastic, we obtain the long-time convergence to an invariant probability measure Vh starting from a bounded a-harmonic function h based on self-duality property, and then we show the convergence to the invariant probability measure Uh holds for a broad class of initial distributions. Second, if （a（i, j））i,j∈s is transient and symmetric, and the diffusion parameter c remains below a threshold, we are able to determine the set of extremal invariant probability measures with finite second moment. Finally, in the case that the transition kernel （a（i,j））i,j∈s is doubly stochastic and satisfies Case I （see Case I in [Shiga, T.： An interacting system in population genetics. J. Math. Kyoto Univ., 20, 213-242 （1980）]）, we show that this parabolic Anderson model locally dies out independent of the diffusion parameter c.
基金the endorsement from the German Aerospace Center(DLR),Germany Executive Board Member for Space Research and Technology and the financial support from the Young Research Group Leader Program as well as financial support by the Deutscher Akademischer AustauschdienstDepartment of Science Technology(DAAD-DST)Germany-India collaboration(Project ID:57317956)Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)project number 396709363.
文摘Due to the complex interplay between composition,synthesis parameters and the performance of thermoelectric materials,the optimization of thermoelectric materials needs to be complemented by modelling.A relatively simple and thus popular approach is the so called single parabolic band model,which allows for an efficient optimization of the material properties and a benchmarking of different materials based on relatively few,well available experimental results.As complex band structures are common for high performance materials,single parabolic band modelling is also employed with apparent success for material systems where the underlying assumptions are not well fulfilled.In order to assess the validity of a single parabolic band analysis for such systems,the thermoelectric properties for two model systems are calculated:one with a single band that is twofold degenerate and one with a light and a heavy band.Even if the density of states masses and the scattering potentials are kept identical,the transport properties and in particular the Hall coefficients differ significantly,which leads to an incorrectly determined carrier concentration.As the carrier concentration is the base for the single parabolic band analysis,all the quantities obtained from it(optimum carrier concentration,effective mass,deformation potential)are determined incorrectly as well.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFC1509704)Young Teachers’Research Ability Improvement Plan of Beijing University of Civil Engineering and Architecture(Grant No.X23005)Beijing Municipal Engineering Institute.
文摘For the project of pipe jacking in cohesionless soil,it is key to determine the vertical load on jacked pipe so as to predict the jacking force accurately.In this paper,a new parabolic soil arching model was proposed to calculate the vertical load on jacked pipe.This proposed analytical model was composed of parabolic soil arching zone,parabola-typed collapse zone and friction arch zone.Combined with existing literature,the key parameters(i.e.,height of parabolic soil arching,horizontal pressure coefficient and width and height of friction arch)were determined.In addition,considering that the trajectory of major stress is parabola,the formula of horizontal pressure coefficient was deduced in the friction arch.The parabolic soil arching zone is assumed as a three-hinged arch with reasonable arch axis,and the formula of load transfer was derived considering the transition effect of parabolic soil arching.The results of experiment,theoretical models and numerical model were adopted to verify the proposed analytical model.Finally,the influence of the key parameters on the vertical load on jacked pipe were also discussed in detail.This work provides a meaningful reference for evaluating the vertical load on jacked pipe for design of pipe jacking.
