A description of inverse energy cascade(from small scale to large scale)in homogeneous isotropic turbulence is introduced by using an eigenvalue method.We show a special isotropic turbulence,in which the initial condi...A description of inverse energy cascade(from small scale to large scale)in homogeneous isotropic turbulence is introduced by using an eigenvalue method.We show a special isotropic turbulence,in which the initial condition is constructed by reversing the velocity field in space,i.e.,the time-reversed turbulence.It is shown that the product of eigenvalues of the rate-of-strain tensor can quantitatively describe the backward energy transfer process.This description is consistent to the velocity derivative skewness Sk.However,compared with Sk,it is easier to be obtained,and it is expected to be extended to anisotropic turbulence.Furthermore,this description also works for the resolved velocity field,which means that it can be used in engineering turbulent flows.The description presented here is desired to inspire future investigation for the modeling of the backward energy transfer process and lay the foundation for the accurate prediction of complex flows.展开更多
Water resource allocation was defined as an input-output question in this paper,and a preliminary input-output index system was set up.Then GEM(group eigenvalue method)-MAUE(multi-attribute utility theory) model was a...Water resource allocation was defined as an input-output question in this paper,and a preliminary input-output index system was set up.Then GEM(group eigenvalue method)-MAUE(multi-attribute utility theory) model was applied to evaluate relative efficiency of water resource allocation plans.This model determined weights of indicators by GEM,and assessed the allocation schemes by MAUE.Compared with DEA(Data Envelopment Analysis) or ANN(Artificial Neural Networks),the model was more applicable in some cases where decision-makers had preference for certain indicators.展开更多
Utilizing the properties of the smallest singular value of a matrix, we propose anew, efficient and reliable algorithm for solving nonsymmetric matrix inverse eigen-value problems, and compare it with a known method. ...Utilizing the properties of the smallest singular value of a matrix, we propose anew, efficient and reliable algorithm for solving nonsymmetric matrix inverse eigen-value problems, and compare it with a known method. We also present numericalexperiments which illustrate our results.展开更多
基金the National Natural Science Foundation of China(Nos.12002318 and51976203)the Central Government Guides Local Science and Technology Development Fund Projects(No.YDZX20191400002850)the Science Foundation of North University of China(No.XJJ201929)。
文摘A description of inverse energy cascade(from small scale to large scale)in homogeneous isotropic turbulence is introduced by using an eigenvalue method.We show a special isotropic turbulence,in which the initial condition is constructed by reversing the velocity field in space,i.e.,the time-reversed turbulence.It is shown that the product of eigenvalues of the rate-of-strain tensor can quantitatively describe the backward energy transfer process.This description is consistent to the velocity derivative skewness Sk.However,compared with Sk,it is easier to be obtained,and it is expected to be extended to anisotropic turbulence.Furthermore,this description also works for the resolved velocity field,which means that it can be used in engineering turbulent flows.The description presented here is desired to inspire future investigation for the modeling of the backward energy transfer process and lay the foundation for the accurate prediction of complex flows.
文摘Water resource allocation was defined as an input-output question in this paper,and a preliminary input-output index system was set up.Then GEM(group eigenvalue method)-MAUE(multi-attribute utility theory) model was applied to evaluate relative efficiency of water resource allocation plans.This model determined weights of indicators by GEM,and assessed the allocation schemes by MAUE.Compared with DEA(Data Envelopment Analysis) or ANN(Artificial Neural Networks),the model was more applicable in some cases where decision-makers had preference for certain indicators.
文摘Utilizing the properties of the smallest singular value of a matrix, we propose anew, efficient and reliable algorithm for solving nonsymmetric matrix inverse eigen-value problems, and compare it with a known method. We also present numericalexperiments which illustrate our results.
