Based on the geological conditions of coal mining face No.15-14120 at No.8 mine of Pingdingshan coal mining group,the real-time evolution of coal-roof crack network with working face advancing was collected with the h...Based on the geological conditions of coal mining face No.15-14120 at No.8 mine of Pingdingshan coal mining group,the real-time evolution of coal-roof crack network with working face advancing was collected with the help of intrinsically safe borehole video instrument.And according to the geology of this working face,a discrete element model was calculated by UDEC.Combining in situ experimental data with numerical results,the relationship between the fractal dimension of boreholes'wall and the distribution of advanced abutment pressure was studied under the condition of mining advance.The results show that the variation tendency of fractal dimension and the abutment pressure has the same characteristic value.The distance between working face and the peak value of the abutment pressure has a slight increasing trend with the advancing of mining-face.When the working face is set as the original point,the trend of fractal dimension from the far place to the origin can be divided into three phases:constant,steady increasing and constant.And the turning points of these phases are the max-influencing distance(50 m)and peak value(15 m)of abutment pressure.展开更多
In this paper,we propose a finite volume Hermite weighted essentially non-oscillatory(HWENO)method based on the dimension by dimension framework to solve hyperbolic conservation laws.It can maintain the high accuracy ...In this paper,we propose a finite volume Hermite weighted essentially non-oscillatory(HWENO)method based on the dimension by dimension framework to solve hyperbolic conservation laws.It can maintain the high accuracy in the smooth region and obtain the high resolution solution when the discontinuity appears,and it is compact which will be good for giving the numerical boundary conditions.Furthermore,it avoids complicated least square procedure when we implement the genuine two dimensional(2D)finite volume HWENO reconstruction,and it can be regarded as a generalization of the one dimensional(1D)HWENO method.Extensive numerical tests are performed to verify the high resolution and high accuracy of the scheme.展开更多
To study the airflow distribution in human nasal cavity during respiration and the characteristic parameters of nasal structure, three-dimensional, anatomically accurate representations of 30 adult nasal cavity models...To study the airflow distribution in human nasal cavity during respiration and the characteristic parameters of nasal structure, three-dimensional, anatomically accurate representations of 30 adult nasal cavity models were recons- tructed based on processed tomography images collected from normal people. The airflow fields in nasal cavities were simulated by fluid dynamics with finite element software ANSYS. The results showed that the difference of human nasal cavity structure led to different airflow distribution in the nasal cavities and variation of the main airstream passing through the common nasal meatus. The nasal resistance in the regions of nasal valve and nasal vestibule accounted for more than half of the overall resistance. The characteristic model of nasal cavity was extracted on the basis of characteristic points and dimensions deduced from the original models. It showed that either the geometric structure or the airflow field of the two kinds of models was similar. The characteristic dimensions were the characteristic parameters of nasal cavity that could properly represent the original model in model studies on nasal cavity.展开更多
In this article,we establish an 2 decoupling inequality for the surface F_(4)^(2):={(ξ1,ξ2,ξ_(1)^(4)+ξ_(2)^(4)):(ξ1,ξ2)∈[0,1]^(2)}associated with the decomposition adapted to finite type geometry from our previ...In this article,we establish an 2 decoupling inequality for the surface F_(4)^(2):={(ξ1,ξ2,ξ_(1)^(4)+ξ_(2)^(4)):(ξ1,ξ2)∈[0,1]^(2)}associated with the decomposition adapted to finite type geometry from our previous work[Li,Z.,Miao,C.,Zheng,J.:A restriction estimate for a certain surface of finite type in R^(3).J.Fourier Anal.Appl.,27(4),Paper No.63,24 pp.(2021)].The key ingredients of the proof include the so-called generalized rescaling technique,an l^(2) decoupling inequality for the surfaces{(ξ1,ξ2,φ1(ξ1)+ξ42):(ξ1,ξ2)∈[0,1]^(2)}with φ1 being non-degenerate,reduction of dimension arguments and induction on scales.展开更多
Finite element method(FEM) simulations were employed to investigate the quenching residual stress distributions of 7085 aluminum alloy plates.The effect of dimensional variation on the quenching residual stress distri...Finite element method(FEM) simulations were employed to investigate the quenching residual stress distributions of 7085 aluminum alloy plates.The effect of dimensional variation on the quenching residual stress distributions was studied and discussed by using models with different dimensions(length,width,and thickness).The accuracy and efficiency of the models were verified by other numerical examples.The order of the dimension effects on the quenching residual stress distributions is:thickness> width=length.The maximum tensile stress and compressive stress increase from 33 to 190 and 39 to 270 MPa,respectively,as the thickness increases from 30 to 150 mm.The ultimate maximum tensile stress(about190 MPa) is equivalent to half of the quenching yield strength at 20℃,while the ultimate maximum compressive stress(about 300 MPa) is equivalent to 80 % of the quenching yield strength at 20℃.There are stress fluctuations at the edge of the large plate both in rolling and in transverse directions.The ratio of the fluctuation region along the rolling direction and transverse direction increases as the thickness increases,while it decreases as the length or width increases.The actual length of the fluctuation region is almost a constant value for the plates with a thickness of 115 mm(about 500 mm in length and 300 mm in width).展开更多
In this paper we discuss the long time behavior of the initial problem We show that in a weighted Hilbert space there exists a global attractor which is weakly compact and has finite Hausdorff and fractal dimension.
In this paper the authors consider the initial boundary value problems of the generalized nonlinear strain waves in elastic waveguides and prove the existence of global attractors and the finiteness of the Hausdorff a...In this paper the authors consider the initial boundary value problems of the generalized nonlinear strain waves in elastic waveguides and prove the existence of global attractors and the finiteness of the Hausdorff and the fractal dimensions of the attractors.展开更多
The h-version adaptive finite element method for 3-D seepage problem ispresented in this paper. The adaptive system includes 4 modules; 3-D mesh generation, finite elementanalysis for 3-D seepage, mesh error estimatio...The h-version adaptive finite element method for 3-D seepage problem ispresented in this paper. The adaptive system includes 4 modules; 3-D mesh generation, finite elementanalysis for 3-D seepage, mesh error estimation and post-process. The effectiveness of this systemis verified by the given example.展开更多
To study the airflow distribution in human nasal cavity during respiration and the characteristic parameters for nasal structure, thirty three-dimensional, anatomically accurate representations of adult nasal cavity m...To study the airflow distribution in human nasal cavity during respiration and the characteristic parameters for nasal structure, thirty three-dimensional, anatomically accurate representations of adult nasal cavity models were reconstructed based on processed tomography images collected from normal people. The airflow fields in nasal cavities were simulated using the fluid dynamics with the finite element software ANSYS. The results showed that the difference of human nasal cavity structure led to varying airflow distribution in the nasal cavities and the main airflow passed through the common nasal meatus. The nasal resistance in the regions of nasal valve and nasal vestibule accounted for more than a half of overall resistance. The characteristic model of nasal cavity was extracted based on the characteristic points and dimensions deducted from the original models. It showed that either the geometric structure or the air-flow field of the two kinds of model was similar. The characteristic dimensions were the characteristic parameters of nasal cavity that properly represented the original model in research for nasal cavity.展开更多
Let χ= be a metric space and let ε be a positive real number. Then a function f: X→Y is defined to be an ε-map if and only if for all y∈Y, the diameter of f-1(y)?is at most ε. In Theorem 10 we will give a new pr...Let χ= be a metric space and let ε be a positive real number. Then a function f: X→Y is defined to be an ε-map if and only if for all y∈Y, the diameter of f-1(y)?is at most ε. In Theorem 10 we will give a new proof for the following well known fact: if χ is totally bounded, then for all ε there exists a finite number n and a continuous ε-map fε: X→Rn (here Rn is the usual n-dimensional Euclidean space endowed with the Euclidean metric). If ε is “small”, then fε is “almost injective”;and still exists even if χ has infinite covering dimension (in this case, n depends on ε, of course). Contrary to the known proofs, our proof technique is effective in the sense, that it allows establishing estimations for n in terms of ε and structural properties of χ.展开更多
Let An be the Beilinson algebra of exterior algebra of an n-dimensional vector space, which is derived equivalent to the endomorphism algebra Endox （T） of a tilting complex T = II^ni=0^Ox （i） of coherent COx-modul...Let An be the Beilinson algebra of exterior algebra of an n-dimensional vector space, which is derived equivalent to the endomorphism algebra Endox （T） of a tilting complex T = II^ni=0^Ox （i） of coherent COx-modules over a projective scheme X = P^nk. In this paper we first construct a minimal projective bimodule resolution of An, and then apply it to calculate k-dimensions of the Hochsehild cohomology groups of An in terms of parallel paths. Finally, we give an explicit description of the cup product and obtain a Gabriel presentation of Hochschild cohomology ring of An. As a consequence, we provide a class of algebras of finite global dimension whose Hochschild cohomology rings have non-trivial multiplicative structures.展开更多
基金financial support from the State Key Basic Research Program of China(Nos.2011CB201201and 2010CB226802)the National Natural Science Foundation of China(No.51204112)
文摘Based on the geological conditions of coal mining face No.15-14120 at No.8 mine of Pingdingshan coal mining group,the real-time evolution of coal-roof crack network with working face advancing was collected with the help of intrinsically safe borehole video instrument.And according to the geology of this working face,a discrete element model was calculated by UDEC.Combining in situ experimental data with numerical results,the relationship between the fractal dimension of boreholes'wall and the distribution of advanced abutment pressure was studied under the condition of mining advance.The results show that the variation tendency of fractal dimension and the abutment pressure has the same characteristic value.The distance between working face and the peak value of the abutment pressure has a slight increasing trend with the advancing of mining-face.When the working face is set as the original point,the trend of fractal dimension from the far place to the origin can be divided into three phases:constant,steady increasing and constant.And the turning points of these phases are the max-influencing distance(50 m)and peak value(15 m)of abutment pressure.
基金supported by the NSFC grant 12101128supported by the NSFC grant 12071392.
文摘In this paper,we propose a finite volume Hermite weighted essentially non-oscillatory(HWENO)method based on the dimension by dimension framework to solve hyperbolic conservation laws.It can maintain the high accuracy in the smooth region and obtain the high resolution solution when the discontinuity appears,and it is compact which will be good for giving the numerical boundary conditions.Furthermore,it avoids complicated least square procedure when we implement the genuine two dimensional(2D)finite volume HWENO reconstruction,and it can be regarded as a generalization of the one dimensional(1D)HWENO method.Extensive numerical tests are performed to verify the high resolution and high accuracy of the scheme.
基金the National Natural Science Foundation of China (1047202510672036)the Natural Science Foundation of Liaoning Province,China (20032109)
文摘To study the airflow distribution in human nasal cavity during respiration and the characteristic parameters of nasal structure, three-dimensional, anatomically accurate representations of 30 adult nasal cavity models were recons- tructed based on processed tomography images collected from normal people. The airflow fields in nasal cavities were simulated by fluid dynamics with finite element software ANSYS. The results showed that the difference of human nasal cavity structure led to different airflow distribution in the nasal cavities and variation of the main airstream passing through the common nasal meatus. The nasal resistance in the regions of nasal valve and nasal vestibule accounted for more than half of the overall resistance. The characteristic model of nasal cavity was extracted on the basis of characteristic points and dimensions deduced from the original models. It showed that either the geometric structure or the airflow field of the two kinds of models was similar. The characteristic dimensions were the characteristic parameters of nasal cavity that could properly represent the original model in model studies on nasal cavity.
基金Supported by National key R&D program of China(Grant No.2021YFA1002500),NSFC(Grant No.12271051),PFCAEP project(Grant No.YZJJLX201901)。
文摘In this article,we establish an 2 decoupling inequality for the surface F_(4)^(2):={(ξ1,ξ2,ξ_(1)^(4)+ξ_(2)^(4)):(ξ1,ξ2)∈[0,1]^(2)}associated with the decomposition adapted to finite type geometry from our previous work[Li,Z.,Miao,C.,Zheng,J.:A restriction estimate for a certain surface of finite type in R^(3).J.Fourier Anal.Appl.,27(4),Paper No.63,24 pp.(2021)].The key ingredients of the proof include the so-called generalized rescaling technique,an l^(2) decoupling inequality for the surfaces{(ξ1,ξ2,φ1(ξ1)+ξ42):(ξ1,ξ2)∈[0,1]^(2)}with φ1 being non-degenerate,reduction of dimension arguments and induction on scales.
基金financially supported by the National Basic Research Program of China(No.2012CB619504)the National Natural Science Foundation of China(No.51274046)
文摘Finite element method(FEM) simulations were employed to investigate the quenching residual stress distributions of 7085 aluminum alloy plates.The effect of dimensional variation on the quenching residual stress distributions was studied and discussed by using models with different dimensions(length,width,and thickness).The accuracy and efficiency of the models were verified by other numerical examples.The order of the dimension effects on the quenching residual stress distributions is:thickness> width=length.The maximum tensile stress and compressive stress increase from 33 to 190 and 39 to 270 MPa,respectively,as the thickness increases from 30 to 150 mm.The ultimate maximum tensile stress(about190 MPa) is equivalent to half of the quenching yield strength at 20℃,while the ultimate maximum compressive stress(about 300 MPa) is equivalent to 80 % of the quenching yield strength at 20℃.There are stress fluctuations at the edge of the large plate both in rolling and in transverse directions.The ratio of the fluctuation region along the rolling direction and transverse direction increases as the thickness increases,while it decreases as the length or width increases.The actual length of the fluctuation region is almost a constant value for the plates with a thickness of 115 mm(about 500 mm in length and 300 mm in width).
基金This project is supported by the National Natural Sciences Foundation of China!No. 19571010
文摘In this paper we discuss the long time behavior of the initial problem We show that in a weighted Hilbert space there exists a global attractor which is weakly compact and has finite Hausdorff and fractal dimension.
基金the National Natural Science Foundation of China (No. 19861004).
文摘In this paper the authors consider the initial boundary value problems of the generalized nonlinear strain waves in elastic waveguides and prove the existence of global attractors and the finiteness of the Hausdorff and the fractal dimensions of the attractors.
文摘The h-version adaptive finite element method for 3-D seepage problem ispresented in this paper. The adaptive system includes 4 modules; 3-D mesh generation, finite elementanalysis for 3-D seepage, mesh error estimation and post-process. The effectiveness of this systemis verified by the given example.
文摘To study the airflow distribution in human nasal cavity during respiration and the characteristic parameters for nasal structure, thirty three-dimensional, anatomically accurate representations of adult nasal cavity models were reconstructed based on processed tomography images collected from normal people. The airflow fields in nasal cavities were simulated using the fluid dynamics with the finite element software ANSYS. The results showed that the difference of human nasal cavity structure led to varying airflow distribution in the nasal cavities and the main airflow passed through the common nasal meatus. The nasal resistance in the regions of nasal valve and nasal vestibule accounted for more than a half of overall resistance. The characteristic model of nasal cavity was extracted based on the characteristic points and dimensions deducted from the original models. It showed that either the geometric structure or the air-flow field of the two kinds of model was similar. The characteristic dimensions were the characteristic parameters of nasal cavity that properly represented the original model in research for nasal cavity.
文摘Let χ= be a metric space and let ε be a positive real number. Then a function f: X→Y is defined to be an ε-map if and only if for all y∈Y, the diameter of f-1(y)?is at most ε. In Theorem 10 we will give a new proof for the following well known fact: if χ is totally bounded, then for all ε there exists a finite number n and a continuous ε-map fε: X→Rn (here Rn is the usual n-dimensional Euclidean space endowed with the Euclidean metric). If ε is “small”, then fε is “almost injective”;and still exists even if χ has infinite covering dimension (in this case, n depends on ε, of course). Contrary to the known proofs, our proof technique is effective in the sense, that it allows establishing estimations for n in terms of ε and structural properties of χ.
基金supported by National Natural Science Foundation of China (Grant Nos.10971206 and 11171325)Important Foundation of Hubei Provincial Department of Education (Grant No.D20101003)
文摘Let An be the Beilinson algebra of exterior algebra of an n-dimensional vector space, which is derived equivalent to the endomorphism algebra Endox （T） of a tilting complex T = II^ni=0^Ox （i） of coherent COx-modules over a projective scheme X = P^nk. In this paper we first construct a minimal projective bimodule resolution of An, and then apply it to calculate k-dimensions of the Hochsehild cohomology groups of An in terms of parallel paths. Finally, we give an explicit description of the cup product and obtain a Gabriel presentation of Hochschild cohomology ring of An. As a consequence, we provide a class of algebras of finite global dimension whose Hochschild cohomology rings have non-trivial multiplicative structures.
