Since the new curriculum reform,labor education has gradually shed its marginalized position in the“five educations,”and the labor curriculum has become an independent course officially separated from comprehensive ...Since the new curriculum reform,labor education has gradually shed its marginalized position in the“five educations,”and the labor curriculum has become an independent course officially separated from comprehensive practical activity courses.Exploring the practical path of labor curriculum in compulsory education in China has become the primary task of labor education in China.Based on the practical situation of labor curriculum in compulsory education in China,drawing on the theory of overlapping influence domains,and from the perspective of collaborative education among family,school,and community,this paper proposes a curriculum practical path of“school-led”family-school-community collaboration and a curriculum practical path guided by“student-centered”sentiment,in order to provide references for the practice of labor curriculum in compulsory education in China.展开更多
Constrained Delaunay triangulated irregular network is one kind of dynamic data structures used in geosciences. The research on point and edges insertion in CD-TIN is the basis of its application. Comparing with the a...Constrained Delaunay triangulated irregular network is one kind of dynamic data structures used in geosciences. The research on point and edges insertion in CD-TIN is the basis of its application. Comparing with the algorithms of points and constrained edge insertion, there are very a few researches on constrained edge deletion in CD-TIN. Based on the analysis of the polymorphism of constrained edge, virtual points are used to describe the intersection of constrained edges. A new algorithm is presented, called as influence domain retriangulating for virtual point （IDRVP）, to delete constrained edges with virtual points. The algorithm is complete in topology. Finally, the algorithm is tested by some applications cases.展开更多
Using the total ozone mapping spectrometer(TOMS)aerosol optical depth(AOD)data and the sunshine duration,fog days,low cloud cover(LCC),etc.meteorological data in 1979-2000 in North China,as well as empirical orthogona...Using the total ozone mapping spectrometer(TOMS)aerosol optical depth(AOD)data and the sunshine duration,fog days,low cloud cover(LCC),etc.meteorological data in 1979-2000 in North China,as well as empirical orthogonal function(EOF)mode statistical analyses method,the winter aerosol distributive character of Beijing and peripheral city agglomeration and its influence effect on regional climate are investigated in this paper,especially the relation between aerosol influence effect and distinct change regions of eigenvectors of EOF mode.It is found from analyzing the regional distribution of the long-term averaged winter TOMS AOD that there is a large-scale relatively stable high value zone of aerosol concentration in the valley of the Beijing and peripheral U-shape megarelief.A high correlation area of AOD between Beijing and its southern peripheral exists in winter,and in this significant region of aerosol interaction,there is'in-phase'character of the interannual variations of winter AOD,fog days,and LCCs.It indicates that the variations of aerosol in Beijing and its peripheral areas have impacts on interannual changes of fog days and LCCs in this area.The EOF analyses of the meteorological data further reveal the climate change regions and long-term trends of winter sunshine duration-reducing,and LCC-and fog days-increasing in North China.The areas of significant changes of the first EOF eigenvectors(FEE)of sunshine duration,fog days,LCCs almost superpose on corresponding marked regions of interdecadal differences between the 1990s and 1980s,and all accord with the S-N zonal high value pattern and high correlation region of winter AOD in Beijing and its peripheral areas.Interannual variations of their associated time coefficients(ATC)are in phase with that of regional mean AOD,and both of them have a secular rising trend.Results by EOF mode analyses depict the regional climatic change principal character of winter sunshine duration-reducing,and LCC-and fog days-increasing in peripheral areas to the south of Beijing,and reveal the regional influence effect of aerosol,i.e.the high value zone of long-term averaged winter AOD,significant change regions of FEE of sunshine duration,fog days,and LCC all lie in peripheral city agglomeration to the south of Beijing.These distributive features above suggest that there exists a regional strengthening trend of aerosol climatic effect within influence domain in peripheral city agglomeration to the south of Beijing.展开更多
Traditional topology optimization methods often introduce weak artificial material to mimic voids to avoid the singularity of the global stiffness matrix and carry out topology optimization with a fixed finite element...Traditional topology optimization methods often introduce weak artificial material to mimic voids to avoid the singularity of the global stiffness matrix and carry out topology optimization with a fixed finite element(FE)mesh.This treatment,however,may not only increase the computational cost for structural analysis but also lead to unfavorable numerical instabilities,especially when large deformations and dynamic/buckling behaviors are involved.In the present work,a new meshless moving morphable component-based method(ML-MMC),which structural analysis is carried out only on the solid region occupied by components,is proposed.In this approach,the coupling of discrete components is achieved through the adaptively constructed influence domain of the meshless shape function.Therefore,the singularity problem of the stiffness matrix can be naturally avoided without introducing weak artificial material.Compared with traditional methods,the number of degrees of freedoms(DOFs)can be reduced substantially under this treatment.The effectiveness of the proposed approach is also illustrated by some representative examples.展开更多
Recently,the radial point interpolation meshfree method has gained popularity owing to its advantages in large deformation and discontinuity problems,however,the accuracy of this method depends on many factors and the...Recently,the radial point interpolation meshfree method has gained popularity owing to its advantages in large deformation and discontinuity problems,however,the accuracy of this method depends on many factors and their influences are not fully investigated yet.In this work,three main factors,i.e.,the shape parameters,the influence domain size,and the nodal distribution,on the accuracy of the radial point interpolation method(RPIM)are systematically studied and conclusive results are obtained.First,the effect of shape parameters(R,q)of the multi-quadric basis function on the accuracy of RPIM is examined via global search.A new interpolation error index,closely related to the accuracy of RPIM,is proposed.The distribution of various error indexes on the R q plane shows that shape parameters q[1.2,1.8]and R[0,1.5]can give good results for general 3-D analysis.This recommended range of shape parameters is examined by multiple benchmark examples in 3D solid mechanics.Second,through numerical experiments,an average of 30 40 nodes in the influence domain of a Gauss point is recommended for 3-D solid mechanics.Third,it is observed that the distribution of nodes has significant effect on the accuracy of RPIM although it has little effect on the accuracy of interpolation.Nodal distributions with better uniformity give better results.Furthermore,how the influence domain size and nodal distribution affect the selection of shape parameters and how the nodal distribution affects the choice of influence domain size are also discussed.展开更多
文摘Since the new curriculum reform,labor education has gradually shed its marginalized position in the“five educations,”and the labor curriculum has become an independent course officially separated from comprehensive practical activity courses.Exploring the practical path of labor curriculum in compulsory education in China has become the primary task of labor education in China.Based on the practical situation of labor curriculum in compulsory education in China,drawing on the theory of overlapping influence domains,and from the perspective of collaborative education among family,school,and community,this paper proposes a curriculum practical path of“school-led”family-school-community collaboration and a curriculum practical path guided by“student-centered”sentiment,in order to provide references for the practice of labor curriculum in compulsory education in China.
文摘Constrained Delaunay triangulated irregular network is one kind of dynamic data structures used in geosciences. The research on point and edges insertion in CD-TIN is the basis of its application. Comparing with the algorithms of points and constrained edge insertion, there are very a few researches on constrained edge deletion in CD-TIN. Based on the analysis of the polymorphism of constrained edge, virtual points are used to describe the intersection of constrained edges. A new algorithm is presented, called as influence domain retriangulating for virtual point （IDRVP）, to delete constrained edges with virtual points. The algorithm is complete in topology. Finally, the algorithm is tested by some applications cases.
基金supported by the Major State Basic Research Development Program("973"Project)(Grant No.TG1999045700)the International Sci-Tech Cooperative Project of the Ministry of Science and Technology of the People's Republic of China(Grant No.2004DFA06100).
文摘Using the total ozone mapping spectrometer(TOMS)aerosol optical depth(AOD)data and the sunshine duration,fog days,low cloud cover(LCC),etc.meteorological data in 1979-2000 in North China,as well as empirical orthogonal function(EOF)mode statistical analyses method,the winter aerosol distributive character of Beijing and peripheral city agglomeration and its influence effect on regional climate are investigated in this paper,especially the relation between aerosol influence effect and distinct change regions of eigenvectors of EOF mode.It is found from analyzing the regional distribution of the long-term averaged winter TOMS AOD that there is a large-scale relatively stable high value zone of aerosol concentration in the valley of the Beijing and peripheral U-shape megarelief.A high correlation area of AOD between Beijing and its southern peripheral exists in winter,and in this significant region of aerosol interaction,there is'in-phase'character of the interannual variations of winter AOD,fog days,and LCCs.It indicates that the variations of aerosol in Beijing and its peripheral areas have impacts on interannual changes of fog days and LCCs in this area.The EOF analyses of the meteorological data further reveal the climate change regions and long-term trends of winter sunshine duration-reducing,and LCC-and fog days-increasing in North China.The areas of significant changes of the first EOF eigenvectors(FEE)of sunshine duration,fog days,LCCs almost superpose on corresponding marked regions of interdecadal differences between the 1990s and 1980s,and all accord with the S-N zonal high value pattern and high correlation region of winter AOD in Beijing and its peripheral areas.Interannual variations of their associated time coefficients(ATC)are in phase with that of regional mean AOD,and both of them have a secular rising trend.Results by EOF mode analyses depict the regional climatic change principal character of winter sunshine duration-reducing,and LCC-and fog days-increasing in peripheral areas to the south of Beijing,and reveal the regional influence effect of aerosol,i.e.the high value zone of long-term averaged winter AOD,significant change regions of FEE of sunshine duration,fog days,and LCC all lie in peripheral city agglomeration to the south of Beijing.These distributive features above suggest that there exists a regional strengthening trend of aerosol climatic effect within influence domain in peripheral city agglomeration to the south of Beijing.
基金supported by the National Natural Science Foundation(Grant Nos.11821202,11732004,12002077 and 12002073)the National Key Research and Development Plan(Grant No.2020YFB1709401)+2 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.DUT21-RC(3)076 and DUT20RC(3)020)the Doctoral Scientific Research Foundation of Liaoning Province(Grant No.2021-BS-063)111 Project(Grant No.B14013).
文摘Traditional topology optimization methods often introduce weak artificial material to mimic voids to avoid the singularity of the global stiffness matrix and carry out topology optimization with a fixed finite element(FE)mesh.This treatment,however,may not only increase the computational cost for structural analysis but also lead to unfavorable numerical instabilities,especially when large deformations and dynamic/buckling behaviors are involved.In the present work,a new meshless moving morphable component-based method(ML-MMC),which structural analysis is carried out only on the solid region occupied by components,is proposed.In this approach,the coupling of discrete components is achieved through the adaptively constructed influence domain of the meshless shape function.Therefore,the singularity problem of the stiffness matrix can be naturally avoided without introducing weak artificial material.Compared with traditional methods,the number of degrees of freedoms(DOFs)can be reduced substantially under this treatment.The effectiveness of the proposed approach is also illustrated by some representative examples.
基金Project(2010CB732103)supported by the National Basic Research Program of ChinaProject(51179092)supported by the National Natural Science Foundation of ChinaProject(2012-KY-02)supported by the State Key Laboratory of Hydroscience and Engineering,China
文摘Recently,the radial point interpolation meshfree method has gained popularity owing to its advantages in large deformation and discontinuity problems,however,the accuracy of this method depends on many factors and their influences are not fully investigated yet.In this work,three main factors,i.e.,the shape parameters,the influence domain size,and the nodal distribution,on the accuracy of the radial point interpolation method(RPIM)are systematically studied and conclusive results are obtained.First,the effect of shape parameters(R,q)of the multi-quadric basis function on the accuracy of RPIM is examined via global search.A new interpolation error index,closely related to the accuracy of RPIM,is proposed.The distribution of various error indexes on the R q plane shows that shape parameters q[1.2,1.8]and R[0,1.5]can give good results for general 3-D analysis.This recommended range of shape parameters is examined by multiple benchmark examples in 3D solid mechanics.Second,through numerical experiments,an average of 30 40 nodes in the influence domain of a Gauss point is recommended for 3-D solid mechanics.Third,it is observed that the distribution of nodes has significant effect on the accuracy of RPIM although it has little effect on the accuracy of interpolation.Nodal distributions with better uniformity give better results.Furthermore,how the influence domain size and nodal distribution affect the selection of shape parameters and how the nodal distribution affects the choice of influence domain size are also discussed.
