ZrP_(2)O_(7) is a promising wave-transparent material due to its low dielectric constant and low dielectric loss,but its inherent phase transition characteristic at approximately 300℃ limits its high-temperature appl...ZrP_(2)O_(7) is a promising wave-transparent material due to its low dielectric constant and low dielectric loss,but its inherent phase transition characteristic at approximately 300℃ limits its high-temperature application.Therefore,suppressing the phase transition is necessary for ZrP_(2)O_(7),to serve in extremely harsh environments.In this work,introducing Ti and Hf into ZrP_(2)O_(7) causes significant lattice distortion and an increase in entropy,both of which synergistically limit the crystal structure transformation.In addition,enhanced phonon scattering by mismatch of atomic mass and local distortion leads to a reduction in the thermal conductivity.Lattice distortions also cause changes in both bond length and tilting angle,so that(Ti_(1/3)Zr_(1/3)Hf_(1/3))P_(2)O_(7) does not undergo sudden expansion as does ZrP_(2)O_(7).(Ti_(1/3)Zr_(1/3)Hf_(1/3))ZrP_(2)O_(7) maintains excellent dielectric properties,which highlights it as a promising high-temperature wave-transparent material.展开更多
This paper presents a topology optimization approach for the surface flows on variable design domains.Via this approach,the matching between the pattern of a surface flow and the 2-manifold used to define the pattern ...This paper presents a topology optimization approach for the surface flows on variable design domains.Via this approach,the matching between the pattern of a surface flow and the 2-manifold used to define the pattern can be optimized,where the 2-manifold is implicitly defined on another fixed 2-manifold named as the base manifold.The fiber bundle topology optimization approach is developed based on the description of the topological structure of the surface flow by using the differential geometry concept of the fiber bundle.The material distribution method is used to achieve the evolution of the pattern of the surface flow.The evolution of the implicit 2-manifold is realized via a homeomorphous map.The design variable of the pattern of the surface flow and that of the implicit 2-manifold are regularized by two sequentially implemented surface-PDE filters.The two surface-PDE filters are coupled,because they are defined on the implicit 2-manifold and base manifold,respectively.The surface Navier-Stokes equations,defined on the implicit 2-manifold,are used to describe the surface flow.The fiber bundle topology optimization problem is analyzed using the continuous adjoint method implemented on the first-order Sobolev space.Several numerical examples have been provided to demonstrate this approach,where the combination of the viscous dissipation and pressure drop is used as the design objective.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Nos.52202078 and 52202126)the Leading Talent Project of the National Special Support Program(No.2022WRLJ003)+1 种基金the Guangdong Basic and Applied Basic Research Foundation for Distinguished Young Scholars(No.2021B1515020083)the Guangdong Basic and Applied Basic Research Foundation(Nos.2021A1515110293 and 2022A1515012201).
文摘ZrP_(2)O_(7) is a promising wave-transparent material due to its low dielectric constant and low dielectric loss,but its inherent phase transition characteristic at approximately 300℃ limits its high-temperature application.Therefore,suppressing the phase transition is necessary for ZrP_(2)O_(7),to serve in extremely harsh environments.In this work,introducing Ti and Hf into ZrP_(2)O_(7) causes significant lattice distortion and an increase in entropy,both of which synergistically limit the crystal structure transformation.In addition,enhanced phonon scattering by mismatch of atomic mass and local distortion leads to a reduction in the thermal conductivity.Lattice distortions also cause changes in both bond length and tilting angle,so that(Ti_(1/3)Zr_(1/3)Hf_(1/3))P_(2)O_(7) does not undergo sudden expansion as does ZrP_(2)O_(7).(Ti_(1/3)Zr_(1/3)Hf_(1/3))ZrP_(2)O_(7) maintains excellent dielectric properties,which highlights it as a promising high-temperature wave-transparent material.
基金Supported by National Natural Science Foundation of China (Grant No.51875545)Innovation Grant of Changchun Institute of Optics+2 种基金Fine Mechanics and Physics (CIOMP)CAS Project for Young Scientists in Basic Research of China (Grant No.YSBR-066)Science and Technology Development Program of Jilin Province of China (Grant No.SKL202302020)。
文摘This paper presents a topology optimization approach for the surface flows on variable design domains.Via this approach,the matching between the pattern of a surface flow and the 2-manifold used to define the pattern can be optimized,where the 2-manifold is implicitly defined on another fixed 2-manifold named as the base manifold.The fiber bundle topology optimization approach is developed based on the description of the topological structure of the surface flow by using the differential geometry concept of the fiber bundle.The material distribution method is used to achieve the evolution of the pattern of the surface flow.The evolution of the implicit 2-manifold is realized via a homeomorphous map.The design variable of the pattern of the surface flow and that of the implicit 2-manifold are regularized by two sequentially implemented surface-PDE filters.The two surface-PDE filters are coupled,because they are defined on the implicit 2-manifold and base manifold,respectively.The surface Navier-Stokes equations,defined on the implicit 2-manifold,are used to describe the surface flow.The fiber bundle topology optimization problem is analyzed using the continuous adjoint method implemented on the first-order Sobolev space.Several numerical examples have been provided to demonstrate this approach,where the combination of the viscous dissipation and pressure drop is used as the design objective.
