One-dimensional(1D)one-way waveguides based on topological edge states of two-dimensional(2D)gyromagnetic photonic crystals have been studied extensively.Here,we theoretically propose a three-dimensional(3D)all-dielec...One-dimensional(1D)one-way waveguides based on topological edge states of two-dimensional(2D)gyromagnetic photonic crystals have been studied extensively.Here,we theoretically propose a three-dimensional(3D)all-dielectric gyromagnetic photonic crystal with type-Ⅱ Weyl points.Based on the inclined band properties of the type-Ⅱ Weyl surface states,we design a 2D one-way interface transmission channel on the Weyl crystal.Light waves in such 2D waveguides can be transmitted robustly over metal obstacles almost without any back-reflection,topologically protected by the type-Ⅱ Weyl points.By manipulating the magnetic field or structural parameters,we also achieve the topological phase transition between Weyl phase and 3D Chern insulator phase and obtain the corresponding phase diagram,which provides more possibilities for topological regulation of the surface states.This work suggests a new way to construct unidirectional 2D waveguides with larger area of energy transmission in 3D space,which is a promising platform for developing 3D topological photonic devices.展开更多
As power systems scale up and uncertainties deepen,traditional centralized optimization approaches impose significant computation burdens on large-scale optimization problems,introducing new challenges for power syste...As power systems scale up and uncertainties deepen,traditional centralized optimization approaches impose significant computation burdens on large-scale optimization problems,introducing new challenges for power system scheduling.To address these challenges,this study formulates a distributionally robust optimization(DRO)scheduling model that considers source-load uncertainty and is solved using a novel distributed approach that considers the distribution of tie-line endpoints.The proposed model includes a constraint related to the transmission interface,which consists of several tie-lines between two subsystems and is specifically designed to ensure technical operation security.In addition,we find that tie-line endpoints enhance the speed of distributed computation,leading to the development of a power system partitioning approach that considers the distribution of these endpoints.Further,this study proposes a distributed approach that employs an integrated algorithm of column-and-constraint generation(C&CG)and subgradient descent(IACS)to address the proposed model across multiple subsystems.A case study of two IEEE test systems and a practical provincial power system demonstrates that the proposed model effectively ensures system security.Finally,the scalability and effectiveness of the distributed approach in accelerating problem-solving are confirmed.展开更多
Interfacial thermal resistance plays a crucial role in efficient heat dissipation in modern electronic devices.It is critical to understand the interfacial thermal transport from both experiments and underlying physic...Interfacial thermal resistance plays a crucial role in efficient heat dissipation in modern electronic devices.It is critical to understand the interfacial thermal transport from both experiments and underlying physics.This review is focused on the transient opto-thermal Raman-based techniques for measuring the interfacial thermal resistance between 2D materials and substrate.This transient idea eliminates the use of laser absorption and absolute temperature rise data,therefore provides some of the highest level measurement accuracy and physics understanding.Physical concepts and perspectives are given for the time-domain differential Raman(TD-Raman),frequency-resolved Raman(FRRaman),energy transport state-resolved Raman(ET-Raman),frequency domain ET-Raman(FET-Raman),as well as laser flash Raman and dual-wavelength laser flash Raman techniques.The thermal nonequilibrium between optical and acoustic phonons,as well as hot carrier diffusion must be considered for extremely small domain characterization of interfacial thermal resistance.To have a better understanding of phonon transport across material interfaces,we introduce a new concept termed effective interface energy transmission velocity.It is very striking that many reported interfaces have an almost constant energy transmission velocity over a wide temperature range.This physics consideration is inspired by the thermal reffusivity theory,which is effective for analyzing structure-phonon scattering.We expect the effective interface energy transmission velocity to give an intrinsic picture of the transmission of energy carriers,unaltered by the influence of their capacity to carry heat.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11974119)Science and Technology Project of Guangdong(Grant No.2020B010190001)+1 种基金Guangdong Innovative and Entrepreneurial Research Team Program(Grant No.2016ZT06C594)National Key R&D Program of China(Grant No.2018YFA0306200)。
文摘One-dimensional(1D)one-way waveguides based on topological edge states of two-dimensional(2D)gyromagnetic photonic crystals have been studied extensively.Here,we theoretically propose a three-dimensional(3D)all-dielectric gyromagnetic photonic crystal with type-Ⅱ Weyl points.Based on the inclined band properties of the type-Ⅱ Weyl surface states,we design a 2D one-way interface transmission channel on the Weyl crystal.Light waves in such 2D waveguides can be transmitted robustly over metal obstacles almost without any back-reflection,topologically protected by the type-Ⅱ Weyl points.By manipulating the magnetic field or structural parameters,we also achieve the topological phase transition between Weyl phase and 3D Chern insulator phase and obtain the corresponding phase diagram,which provides more possibilities for topological regulation of the surface states.This work suggests a new way to construct unidirectional 2D waveguides with larger area of energy transmission in 3D space,which is a promising platform for developing 3D topological photonic devices.
基金supported by the National Key R&D Program of China(No.2022YFB2403400)。
文摘As power systems scale up and uncertainties deepen,traditional centralized optimization approaches impose significant computation burdens on large-scale optimization problems,introducing new challenges for power system scheduling.To address these challenges,this study formulates a distributionally robust optimization(DRO)scheduling model that considers source-load uncertainty and is solved using a novel distributed approach that considers the distribution of tie-line endpoints.The proposed model includes a constraint related to the transmission interface,which consists of several tie-lines between two subsystems and is specifically designed to ensure technical operation security.In addition,we find that tie-line endpoints enhance the speed of distributed computation,leading to the development of a power system partitioning approach that considers the distribution of these endpoints.Further,this study proposes a distributed approach that employs an integrated algorithm of column-and-constraint generation(C&CG)and subgradient descent(IACS)to address the proposed model across multiple subsystems.A case study of two IEEE test systems and a practical provincial power system demonstrates that the proposed model effectively ensures system security.Finally,the scalability and effectiveness of the distributed approach in accelerating problem-solving are confirmed.
基金supported by the National Natural Science Foundation of China(No.12204320 for J.L.and 52276080 for Y.X.)US National Science Foundation(CBET1930866 and CMMI2032464 for X.W)J.L.is grateful for the support from Shenzhen Science and Technology Program(JCYJ20220530153401003).
文摘Interfacial thermal resistance plays a crucial role in efficient heat dissipation in modern electronic devices.It is critical to understand the interfacial thermal transport from both experiments and underlying physics.This review is focused on the transient opto-thermal Raman-based techniques for measuring the interfacial thermal resistance between 2D materials and substrate.This transient idea eliminates the use of laser absorption and absolute temperature rise data,therefore provides some of the highest level measurement accuracy and physics understanding.Physical concepts and perspectives are given for the time-domain differential Raman(TD-Raman),frequency-resolved Raman(FRRaman),energy transport state-resolved Raman(ET-Raman),frequency domain ET-Raman(FET-Raman),as well as laser flash Raman and dual-wavelength laser flash Raman techniques.The thermal nonequilibrium between optical and acoustic phonons,as well as hot carrier diffusion must be considered for extremely small domain characterization of interfacial thermal resistance.To have a better understanding of phonon transport across material interfaces,we introduce a new concept termed effective interface energy transmission velocity.It is very striking that many reported interfaces have an almost constant energy transmission velocity over a wide temperature range.This physics consideration is inspired by the thermal reffusivity theory,which is effective for analyzing structure-phonon scattering.We expect the effective interface energy transmission velocity to give an intrinsic picture of the transmission of energy carriers,unaltered by the influence of their capacity to carry heat.
