The magnetic properties and magnetocaloric effects of amorphous and crystalline Gd55Co35Ni10 ribbons are investigated.A main phase with a Ho 12 Co 7-type monoclinic structure(space group P21/c) and a minor phase with ...The magnetic properties and magnetocaloric effects of amorphous and crystalline Gd55Co35Ni10 ribbons are investigated.A main phase with a Ho 12 Co 7-type monoclinic structure(space group P21/c) and a minor phase with a Ho4Co3-type hexagonal structure(space group P63/m) are obtained for crystalline ribbon after annealing.The amorphous ribbons order ferromagnetically and undergo a second-order transition at 192 K.For crystalline Gd55Co35Ni10 ribbons,two magnetic phase transitions occur at 158 and 214 K,respectively.The peak value of-△SM under a field change of 0-5 T is 6.5 J/kg K at 192 K for amorphous Gd55Co35Ni10 ribbons.A relatively large magnetic entropy change(～5.0 J/kg K) under a field change of 0-5 T for the crystalline Gd55Co35Ni10 ribbons is obtained in the temperature interval range of 154-214 K.The large platform of magnetic entropy change and the negligible thermal/magnetic hysteresis loss mean the crystalline Gd55Co35Ni10 compound can satisfy the requirement of the Ericsson-type refrigerator working in the temperature range from 154K to 214K.展开更多
Discrete Global Grid Systems(DGGSs) are spatial references that use a hierarchical tessellation of cells to partition and address the entire globe. They provide an organizational structure that permits fast integratio...Discrete Global Grid Systems(DGGSs) are spatial references that use a hierarchical tessellation of cells to partition and address the entire globe. They provide an organizational structure that permits fast integration between multiple sources of large and variable geospatial data sufficient for visualization and analysis. Despite a significant body of research supporting hexagonal DGGSs as the superior choice, the application thereof has been hindered owing in part to the lack of a rational hierarchy with an efficient addressing system. This paper presents an algebraic model of encoding scheme for the Aperture 3 Hexagonal(A3H) DGGS. Firstly, the definition of a grid cell, which is composed of vertices, edges, and a center, is introduced to describe fundamental elements of grids. Secondly, by identifying the grid cell with its center, this paper proves that cell centers at different levels can be represented exactly using a mixed positional number system in the complex plane through the recursive geometric relationship between two successive levels, which reveals that grid cells are essentially special complex radix numbers. Thirdly, it is shown that through the recursive geometric relationship of successive odd or even levels, the mixed positional number system can also be applied to uniquely represent cell centers at different levels under specific constraint conditions, according to which the encoding scheme is designed. Finally, it is shown that by extending the scheme to 20 triangular faces of the regular icosahedron,multi-resolution grids on closed surfaces of the icosahedron are addressed perfectly. Contrast experiments show that the proposed encoding scheme has the advantages of theoretical rigor and high programming efficiency and that the efficiency of cross-face adjacent cell searching is 242.9 times that of a similar scheme. Moreover, the proposed complex radix number representation is an ideal formalized description tool for grid systems. The research ideas introduced herein can be used to create a universal theoretical framework for DGGSs.展开更多
基金supported by the Guangdong Provincial Science and Technology Program(Grant Nos.2010B050300008,2009B090300273 and 2007B010600043)the Guangzhou Municipal Science and Technology Program(Grant No.12F582080022)+1 种基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry (Grant No.x2clB7120290)the Fundamental Research Funds for the Central Universities(Grant Nos.2011ZM0014 and 2012ZZ0013)
文摘The magnetic properties and magnetocaloric effects of amorphous and crystalline Gd55Co35Ni10 ribbons are investigated.A main phase with a Ho 12 Co 7-type monoclinic structure(space group P21/c) and a minor phase with a Ho4Co3-type hexagonal structure(space group P63/m) are obtained for crystalline ribbon after annealing.The amorphous ribbons order ferromagnetically and undergo a second-order transition at 192 K.For crystalline Gd55Co35Ni10 ribbons,two magnetic phase transitions occur at 158 and 214 K,respectively.The peak value of-△SM under a field change of 0-5 T is 6.5 J/kg K at 192 K for amorphous Gd55Co35Ni10 ribbons.A relatively large magnetic entropy change(～5.0 J/kg K) under a field change of 0-5 T for the crystalline Gd55Co35Ni10 ribbons is obtained in the temperature interval range of 154-214 K.The large platform of magnetic entropy change and the negligible thermal/magnetic hysteresis loss mean the crystalline Gd55Co35Ni10 compound can satisfy the requirement of the Ericsson-type refrigerator working in the temperature range from 154K to 214K.
基金supported by the National Natural Science Foundation of China (Grant No. 41671410)the Postdoctoral Science Foundation of China (Grant No. 2013T60161)the Excellent Young Scholar Foundation of Information Engineering University (Grant No. 2016610802)
文摘Discrete Global Grid Systems(DGGSs) are spatial references that use a hierarchical tessellation of cells to partition and address the entire globe. They provide an organizational structure that permits fast integration between multiple sources of large and variable geospatial data sufficient for visualization and analysis. Despite a significant body of research supporting hexagonal DGGSs as the superior choice, the application thereof has been hindered owing in part to the lack of a rational hierarchy with an efficient addressing system. This paper presents an algebraic model of encoding scheme for the Aperture 3 Hexagonal(A3H) DGGS. Firstly, the definition of a grid cell, which is composed of vertices, edges, and a center, is introduced to describe fundamental elements of grids. Secondly, by identifying the grid cell with its center, this paper proves that cell centers at different levels can be represented exactly using a mixed positional number system in the complex plane through the recursive geometric relationship between two successive levels, which reveals that grid cells are essentially special complex radix numbers. Thirdly, it is shown that through the recursive geometric relationship of successive odd or even levels, the mixed positional number system can also be applied to uniquely represent cell centers at different levels under specific constraint conditions, according to which the encoding scheme is designed. Finally, it is shown that by extending the scheme to 20 triangular faces of the regular icosahedron,multi-resolution grids on closed surfaces of the icosahedron are addressed perfectly. Contrast experiments show that the proposed encoding scheme has the advantages of theoretical rigor and high programming efficiency and that the efficiency of cross-face adjacent cell searching is 242.9 times that of a similar scheme. Moreover, the proposed complex radix number representation is an ideal formalized description tool for grid systems. The research ideas introduced herein can be used to create a universal theoretical framework for DGGSs.
