The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

Takanori Fujiwara - One of the best experts on this subject based on the ideXlab platform.

  • Expanding Polyhedral Universe in Regge Calculus
    Progress of Theoretical and Experimental Physics, 2017
    Co-Authors: Ren Tsuda, Takanori Fujiwara
    Abstract:

    The closed Friedmann-Lemaitre-Robertson-Walker (FLRW) universe of Einstein gravity with positive cosmological constant in three dimensions is investigated by using the Collins-Williams formalism in Regge calculus. A spherical Cauchy surface is replaced with Regular Polyhedrons. The Regge equations are reduced to differential equations in the continuum time limit. Numerical solutions to the Regge equations approximate well the continuum FLRW universe during the era of small edge length. The deviation from the continuum solution becomes larger and larger with time. Unlike the continuum universe, the polyhedral universe expands to infinite within finite time. To remedy the shortcoming of the model universe we introduce geodesic domes and pseudo-Regular Polyhedrons. It is shown that the pseudo-Regular Polyhedron model can approximate well the results of the Regge calculus for the geodesic domes. The pseudo-Regular Polyhedron model approaches the continuum solution in the infinite frequency limit.

Kingleung Wong - One of the best experts on this subject based on the ideXlab platform.

  • Complete heat transfer solutions of an insulated Regular Polyhedron by using an RPSWT model
    Energy Conversion and Management, 2005
    Co-Authors: Jenn-fa Lee, Kingleung Wong, Wen Lih Chen
    Abstract:

    Abstract The heat transfer characteristics for an insulated Regular Polyhedron (including sphere) are analyzed by using the same RPSWT model in the present study as that used by Wong and Chou previously [Energy Convers. Manage. 44 (2003) 3015]. The thermal resistance of the inner convection term and the wall conduction term in the heat transfer rate are not neglected in the present study. Thus, the complete heat transfer solution will be obtained. The present results can be applied more extensively to practical situations, such as an insulated gas tank. The results of the critical thickness t cr and the neutral thickness t e are independent of the values of J (generated by the effect of the inner convection term and the wall conduction term). However, the heat transfer rates are dependent on the values of J . The present study shows that the thermal resistance of the inner convection term and the body conduction term cannot be neglected in the heat transfer equation in situations of low to medium inner convection coefficients h i and/or low to medium wall conductivities K and/or great wall thickness t 1 , especially in situations with small body sizes or/and great outer convection coefficients h o .

  • heat transfer characteristics of an insulated Regular Polyhedron by using a Regular polygon top solid wedge thermal resistance model
    Energy Conversion and Management, 2003
    Co-Authors: Kingleung Wong, Huannming Chou
    Abstract:

    The relation of the critical and the neutral thickness and heat transfer characteristics for an insulated Regular Polyhedron are investigated by using a new Regular polygon top solid wedge thermal resistance (RPSWT) model obtained from a solid angle concept. It is found that the dimensionless heat transfer characteristics of the insulated Polyhedrons are the same as those of an insulated sphere even though their actual heat transfer rates are different. It is also found that the conventional constant surface area plate model cannot be used to analyze the insulated Polyhedrons, especially in situations of small to medium body size and/or with a greater insulation thickness. The single RPSWT model should also be applied to the heat transfer problem of the wedge block with a Regular polygon top.

Huannming Chou - One of the best experts on this subject based on the ideXlab platform.

Ren Tsuda - One of the best experts on this subject based on the ideXlab platform.

  • Expanding Polyhedral Universe in Regge Calculus
    Progress of Theoretical and Experimental Physics, 2017
    Co-Authors: Ren Tsuda, Takanori Fujiwara
    Abstract:

    The closed Friedmann-Lemaitre-Robertson-Walker (FLRW) universe of Einstein gravity with positive cosmological constant in three dimensions is investigated by using the Collins-Williams formalism in Regge calculus. A spherical Cauchy surface is replaced with Regular Polyhedrons. The Regge equations are reduced to differential equations in the continuum time limit. Numerical solutions to the Regge equations approximate well the continuum FLRW universe during the era of small edge length. The deviation from the continuum solution becomes larger and larger with time. Unlike the continuum universe, the polyhedral universe expands to infinite within finite time. To remedy the shortcoming of the model universe we introduce geodesic domes and pseudo-Regular Polyhedrons. It is shown that the pseudo-Regular Polyhedron model can approximate well the results of the Regge calculus for the geodesic domes. The pseudo-Regular Polyhedron model approaches the continuum solution in the infinite frequency limit.

Yeong-nan Yeh - One of the best experts on this subject based on the ideXlab platform.

  • Topological analysis of some special graphs. III. Regular polyhedra
    Journal of Cluster Science, 1991
    Co-Authors: Shyi-long Lee, Yeung-long Luo, Yeong-nan Yeh
    Abstract:

    A Regular Polyhedron is isomorphic to a cluster on which every face has same number of bonds and every atom has an equal number of coordinating atoms. A general strategy for generating the eigenvectors and the eigenvalues of Regular polyhedra is given. Not sign analyses are also performed on the eigenvectors of Regular polyhedra. The results provide us a quick way to grasp the topological feature of the electronic structure of clusters having interesting topology.

  • Topological analysis of some special graphs. III. Regular polyhedra
    Journal of Cluster Science, 1991
    Co-Authors: Shyi-long Lee, Yeung-long Luo, Yeong-nan Yeh
    Abstract:

    A Regular Polyhedron is isomorphic to a cluster on which every face has same number of bonds and every atom has an equal number of coordinating atoms. A general strategy for generating the eigenvectors and the eigenvalues of Regular polyhedra is given. Net sign analyses are also performed on the eigenvectors of Regular polyhedra. The results provide us a quick way to grasp the topological feature of the electronic structure of clusters having interesting topology.