We utilize the topological-geometrical structure imposed by the Heterotic superstring theory on spacetime in conjunction with the K3 Kähler manifold to explain the mysterious nature of dark matter and its cou...We utilize the topological-geometrical structure imposed by the Heterotic superstring theory on spacetime in conjunction with the K3 Kähler manifold to explain the mysterious nature of dark matter and its coupling to the pure dark energy density of the cosmos. The analogous situations in the case of a Kerr black hole as well as the redundant components of the Riemannian tensor are pointed out and the final result was found to be in complete agreement with all previous theoretical ones as well as all recent accurate measurements and cosmic observations. We conclude by commenting briefly on the Cantorian model of Zitterbewegung and the connection between Olbers’s paradox and dark energy.展开更多
Surface wettability plays a significant role in reducing solid–liquid frictional resistance,especially the superhydrophilic/hydrophilic interface because of its excellent thermodynamic stability.In this work,poly(acr...Surface wettability plays a significant role in reducing solid–liquid frictional resistance,especially the superhydrophilic/hydrophilic interface because of its excellent thermodynamic stability.In this work,poly(acrylic acid)-poly(acrylamide)(PAA–PAM)hydrogel coatings with different thicknesses were prepared in situ by polydopamine(PDA)-UV assisted surface catalytically initiated radical polymerization.Fluid drag reduction performance of hydrogel surface was measured using a rotational rheometer by the plate–plate mode.The experimental results showed that the average drag reduction of hydrogel surface could reach up to about 56%in Couette flow,which was mainly due to the interfacial polymerization phenomenon that enhanced the ability of hydration layer to delay the momentum dissipation between fluid layers and the diffusion behavior of surface.The proposed drag reduction mechanism of hydrogel surface was expected to shed new light on hydrogel–liquid interface interaction and provide a new way for the development of steady-state drag reduction methods.展开更多
Energy management is an important issue in the operation of hybrid electric trains.To achieve optimal energy utilization,this paper proposes a dynamic programming approach considering state space reduction to solve th...Energy management is an important issue in the operation of hybrid electric trains.To achieve optimal energy utilization,this paper proposes a dynamic programming approach considering state space reduction to solve the optimization problem.Dynamic programming,as an exact algorithm,has a clear advantage in terms of solution accuracy,but its efficiency is low when dealing with large-scale optimization problems.Firstly,the paper introduces the topology and operation modes of hydrogen fuel cell hybrid trains,as well as the basic principles and computational steps of dynamic programming.Secondly,several state reduction strategies are designed to improve solution efficiency,and an objective function considering both passenger experience and operational costs is proposed.The numerical experimental results demonstrate that the proposed method not only solves the inherent problems of dynamic programming but also outperforms traditional dynamic programming and level set-based optimization methods in terms of computational accuracy and time.Furthermore,experimental results based on real driving conditions validate the applicability of the proposed method.展开更多
文摘We utilize the topological-geometrical structure imposed by the Heterotic superstring theory on spacetime in conjunction with the K3 Kähler manifold to explain the mysterious nature of dark matter and its coupling to the pure dark energy density of the cosmos. The analogous situations in the case of a Kerr black hole as well as the redundant components of the Riemannian tensor are pointed out and the final result was found to be in complete agreement with all previous theoretical ones as well as all recent accurate measurements and cosmic observations. We conclude by commenting briefly on the Cantorian model of Zitterbewegung and the connection between Olbers’s paradox and dark energy.
基金financially supported by National Natural Science Foundation of China(51905519,22032006,U2030201,and U21A2046).
文摘Surface wettability plays a significant role in reducing solid–liquid frictional resistance,especially the superhydrophilic/hydrophilic interface because of its excellent thermodynamic stability.In this work,poly(acrylic acid)-poly(acrylamide)(PAA–PAM)hydrogel coatings with different thicknesses were prepared in situ by polydopamine(PDA)-UV assisted surface catalytically initiated radical polymerization.Fluid drag reduction performance of hydrogel surface was measured using a rotational rheometer by the plate–plate mode.The experimental results showed that the average drag reduction of hydrogel surface could reach up to about 56%in Couette flow,which was mainly due to the interfacial polymerization phenomenon that enhanced the ability of hydration layer to delay the momentum dissipation between fluid layers and the diffusion behavior of surface.The proposed drag reduction mechanism of hydrogel surface was expected to shed new light on hydrogel–liquid interface interaction and provide a new way for the development of steady-state drag reduction methods.
文摘Energy management is an important issue in the operation of hybrid electric trains.To achieve optimal energy utilization,this paper proposes a dynamic programming approach considering state space reduction to solve the optimization problem.Dynamic programming,as an exact algorithm,has a clear advantage in terms of solution accuracy,but its efficiency is low when dealing with large-scale optimization problems.Firstly,the paper introduces the topology and operation modes of hydrogen fuel cell hybrid trains,as well as the basic principles and computational steps of dynamic programming.Secondly,several state reduction strategies are designed to improve solution efficiency,and an objective function considering both passenger experience and operational costs is proposed.The numerical experimental results demonstrate that the proposed method not only solves the inherent problems of dynamic programming but also outperforms traditional dynamic programming and level set-based optimization methods in terms of computational accuracy and time.Furthermore,experimental results based on real driving conditions validate the applicability of the proposed method.
