0 INTRODUCTION Due to the rapid population growth and the accelerated urbanization process,the contradiction between the demand for expanding ground space and the limited available land scale is becoming increasingly ...0 INTRODUCTION Due to the rapid population growth and the accelerated urbanization process,the contradiction between the demand for expanding ground space and the limited available land scale is becoming increasingly prominent.China has implemented and completed several largescale land infilling and excavation projects(Figure 1),which have become the main way to increase land resources and expand construction land.展开更多
Infrared and terahertz waves constitute pivotal bands within the electromagnetic spectrum,distinguished by their robust penetration capabilities and non-ionizing nature.These wavebands offer the potential for achievin...Infrared and terahertz waves constitute pivotal bands within the electromagnetic spectrum,distinguished by their robust penetration capabilities and non-ionizing nature.These wavebands offer the potential for achieving high-resolution and non-destructive detection methodologies,thereby possessing considerable research significance across diverse domains including communication technologies,biomedical applications,and security screening systems.Two-dimensional materials,owing to their distinctive optoelectronic attributes,have found widespread application in photodetection endeavors.Nonetheless,their efficacy diminishes when tasked with detecting lower photon energies.Furthermore,as the landscape of device integration evolves,two-dimensional materials struggle to align with the stringent demands for device superior performance.Topological materials,with their topologically protected electronic states and non-trivial topological invariants,exhibit quantum anomalous Hall effects and ultra-high carrier mobility,providing a new approach for seeking photosensitive materials for infrared and terahertz photodetectors.This article introduces various types of topological materials and their properties,followed by an explanation of the detection mechanism and performance parameters of photodetectors.Finally,it summarizes the current research status of near-infrared to far-infrared photodetectors and terahertz photodetectors based on topological materials,discussing the challenges faced and future prospects in their development.展开更多
0 INTRODUCTION Landslide is one of the most common and serious natural disasters in the world,which causes great damage to social development and people's life and property safety(Wei et al.,2024;Froude and Petley...0 INTRODUCTION Landslide is one of the most common and serious natural disasters in the world,which causes great damage to social development and people's life and property safety(Wei et al.,2024;Froude and Petley,2018).Landslides are responsible for an average of thousands of deaths and billions of economic losses annually(Dai et al.,2023).The study of landslide geomorphology plays a crucial role in many aspects such as landslide formation mechanisms,dynamic process,and prevention and control(Hou et al.,2024;Wang et al.,2024),and provides scientific support for infrastructure construction,road route selection,and urban land planning(Vargas-Cuervo et al.,2024;Laimer,2017).Therefore,it is essential to gain a better understanding of those roles and to further contribute to disaster prevention and reduction.展开更多
INTRODUCTION In southern Shaanxi,China,the government is implementing a“pre-emptive”migration away from remote mountains and contiguous areas with extreme poverty(Figure 1).The direct aim is to eradicate extreme pov...INTRODUCTION In southern Shaanxi,China,the government is implementing a“pre-emptive”migration away from remote mountains and contiguous areas with extreme poverty(Figure 1).The direct aim is to eradicate extreme poverty and protect the ecological integrity in mountainous areas.However,this policy can not only reduce human damage to natural protected areas and wildlife habitats,but more importantly,bid farewell to the areas where geo-disasters are frequent,the risk of farmers'exposure to disasters is eliminated.展开更多
0 INTRODUCTION The Lajia Site in Guanting Basin in the Upper Reaches of the Yellow River,China,is known as the'Pompeii of the East'.It is adjacent to Xunhua and Hualong counties,and is also situated in the tra...0 INTRODUCTION The Lajia Site in Guanting Basin in the Upper Reaches of the Yellow River,China,is known as the'Pompeii of the East'.It is adjacent to Xunhua and Hualong counties,and is also situated in the transitional zone between the Tibetan Plateau and the Loess Plateau(Figures 1a and 1b)(Wei et al.,2024).展开更多
Continuous co-phase traction power system is an effective method to eliminate neutral sections and provide high quality power for both the public grid and the catenary.The substations have the ability to provide coope...Continuous co-phase traction power system is an effective method to eliminate neutral sections and provide high quality power for both the public grid and the catenary.The substations have the ability to provide cooperative support to each other to reduce capacity and improve system reliability.A fast power control method for substations is needed due to rapid load changes and low overload capability of the system.This paper proposes a fast power control method based on high-speed communication between substations,with additional transient power control to significantly improve the dynamic response of the system.展开更多
Landslide susceptibility assessment is crucial in predicting landslide occurrence and potential risks.However,traditional methods usually emphasize on larger regions of landsliding and rely on relatively static enviro...Landslide susceptibility assessment is crucial in predicting landslide occurrence and potential risks.However,traditional methods usually emphasize on larger regions of landsliding and rely on relatively static environmental conditions,which exposes the hysteresis of landslide susceptibility assessment in refined-scale and temporal dynamic changes.This study presents an improved landslide susceptibility assessment approach by integrating machine learning models based on random forest(RF),logical regression(LR),and gradient boosting decision tree(GBDT)with interferometric synthetic aperture radar(InSAR)technology and comparing them to their respective original models.The results demonstrated that the combined approach improves prediction accuracy and reduces the false negative and false positive errors.The LR-InSAR model showed the best performance in dynamic landslide susceptibility assessment at both regional and smaller scale,particularly when identifying areas of high and very high susceptibility.Modeling results were verified using data from field investigations including unmanned aerial vehicle(UAV)flights.This study is of great significance to accurately assess dynamic landslide susceptibility and to help reduce and prevent landslide risk.展开更多
This paper proposes a novel hybrid multilevel converter with DC fault-blocking capability, i.e., the neutral-point clamped hybrid multilevel converter(NHMC).By employing two types of unipolar full-bridge submodules al...This paper proposes a novel hybrid multilevel converter with DC fault-blocking capability, i.e., the neutral-point clamped hybrid multilevel converter(NHMC).By employing two types of unipolar full-bridge submodules along with director switches, which are composed of seriesconnected insulated-gate bipolar transistors, the NHMC combines the features and advantages of the neutral-point clamped converter and the modular multilevel converter.The basic topology, operating principles, modulation scheme, and energy-balancing scheme of the NHMC are presented. The DC fault-blocking capability of the NHMC is investigated. The number of power electronic devices used by the NHMC is calculated and compared with other multilevel converters, showing that the proposed NHMC can be an economical and feasible option for medium-voltage DC transmission with overhead lines. Simulation results demonstrate the features and operating scheme of the proposed NHMC.展开更多
A novel DC traction power supply system suitable for energy feeding and de-icing is proposed in this paper for an urban rail transit catenary on the basis of the full bridge submodule (FBSM) modular multilevel convert...A novel DC traction power supply system suitable for energy feeding and de-icing is proposed in this paper for an urban rail transit catenary on the basis of the full bridge submodule (FBSM) modular multilevel converter (MMC). The FBSM-MMC is a novel type of voltage source converter (VSC) and can directly control the output DC voltage and conduct bipolar currents, thus flexibly controlling the power flow of the urban rail transit catenary. The proposed topology can overcome the inherent disadvantages of the output voltage drop in the diode rectifier units, increase the power supply distance and reduce the number of traction substations. The flexible DC technology can coordinate multiple FBSM-MMCs in a wide area and jointly complete the bidirectional control of catenary power flow during the operation of the electric locomotive, so as to realize the local consumption and optimal utilization of the recovered braking energy of the train. In addition, the FBSM-MMCs can also adjust the output current when the locomotive is out of service to prevent the catenary from icing in winter. The working modes of the proposed topology are illustrated in detail and the control strategy is specially designed for normal locomotive operations and catenary de-icing. Simulation cases conducted by PSCAD/EMTDC validate the proposed topology and its control strategy.展开更多
基金funded by the Key Research and Development Program of Shaanxi Province(No.2024SFYBXM-669)the National Natural Science Foundation of China(No.42271078)。
文摘0 INTRODUCTION Due to the rapid population growth and the accelerated urbanization process,the contradiction between the demand for expanding ground space and the limited available land scale is becoming increasingly prominent.China has implemented and completed several largescale land infilling and excavation projects(Figure 1),which have become the main way to increase land resources and expand construction land.
基金supported by the National Key R&D Program of China(Grant No.2024YFA1211300)Outstanding Youth Foundation of NSFC(Grant No.62322515)+5 种基金Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Shanghai Natural Science Foundation Project(Grant No.24ZR1493100)International Partnership Program of Chinese Academy of Sciences(Grant No.112GJHZ2024039FN)the support from Analytical Instrumentation Center(#SPST-AIC10112914)Soft Matter Nanofab(#SPST-SMN180827)Quantum Device Lab,Shanghai Tech University。
文摘Infrared and terahertz waves constitute pivotal bands within the electromagnetic spectrum,distinguished by their robust penetration capabilities and non-ionizing nature.These wavebands offer the potential for achieving high-resolution and non-destructive detection methodologies,thereby possessing considerable research significance across diverse domains including communication technologies,biomedical applications,and security screening systems.Two-dimensional materials,owing to their distinctive optoelectronic attributes,have found widespread application in photodetection endeavors.Nonetheless,their efficacy diminishes when tasked with detecting lower photon energies.Furthermore,as the landscape of device integration evolves,two-dimensional materials struggle to align with the stringent demands for device superior performance.Topological materials,with their topologically protected electronic states and non-trivial topological invariants,exhibit quantum anomalous Hall effects and ultra-high carrier mobility,providing a new approach for seeking photosensitive materials for infrared and terahertz photodetectors.This article introduces various types of topological materials and their properties,followed by an explanation of the detection mechanism and performance parameters of photodetectors.Finally,it summarizes the current research status of near-infrared to far-infrared photodetectors and terahertz photodetectors based on topological materials,discussing the challenges faced and future prospects in their development.
基金funded by the Key Research and Development Projects of Shaanxi Province(No.2024SFYBXM-669)the National Natural Science Foundation of China(No.42271078)。
文摘0 INTRODUCTION Landslide is one of the most common and serious natural disasters in the world,which causes great damage to social development and people's life and property safety(Wei et al.,2024;Froude and Petley,2018).Landslides are responsible for an average of thousands of deaths and billions of economic losses annually(Dai et al.,2023).The study of landslide geomorphology plays a crucial role in many aspects such as landslide formation mechanisms,dynamic process,and prevention and control(Hou et al.,2024;Wang et al.,2024),and provides scientific support for infrastructure construction,road route selection,and urban land planning(Vargas-Cuervo et al.,2024;Laimer,2017).Therefore,it is essential to gain a better understanding of those roles and to further contribute to disaster prevention and reduction.
基金funded by the Key Research and Development Program of Shaanxi(No.2024SF-YBXM-669)the National Natural Science Foundation of China(No.42271078)。
文摘INTRODUCTION In southern Shaanxi,China,the government is implementing a“pre-emptive”migration away from remote mountains and contiguous areas with extreme poverty(Figure 1).The direct aim is to eradicate extreme poverty and protect the ecological integrity in mountainous areas.However,this policy can not only reduce human damage to natural protected areas and wildlife habitats,but more importantly,bid farewell to the areas where geo-disasters are frequent,the risk of farmers'exposure to disasters is eliminated.
基金funded by the National Natural Science Foundation of China(No.42271078)the Key Research and Development Program of Shaanxi(No.2024SF-YBXM669)。
文摘0 INTRODUCTION The Lajia Site in Guanting Basin in the Upper Reaches of the Yellow River,China,is known as the'Pompeii of the East'.It is adjacent to Xunhua and Hualong counties,and is also situated in the transitional zone between the Tibetan Plateau and the Loess Plateau(Figures 1a and 1b)(Wei et al.,2024).
基金supported by the National Natural Science Foundation of China under Grant 52277190the Major Science and Technology Projects of China Railway Electrification Engineering Group Co.,LTD.(20192001148).
文摘Continuous co-phase traction power system is an effective method to eliminate neutral sections and provide high quality power for both the public grid and the catenary.The substations have the ability to provide cooperative support to each other to reduce capacity and improve system reliability.A fast power control method for substations is needed due to rapid load changes and low overload capability of the system.This paper proposes a fast power control method based on high-speed communication between substations,with additional transient power control to significantly improve the dynamic response of the system.
基金the National Natural Science Foundation of China(Grant No.42271078)Key Research and Development Program of Shaanxi(2024SF-YBXM-669)。
文摘Landslide susceptibility assessment is crucial in predicting landslide occurrence and potential risks.However,traditional methods usually emphasize on larger regions of landsliding and rely on relatively static environmental conditions,which exposes the hysteresis of landslide susceptibility assessment in refined-scale and temporal dynamic changes.This study presents an improved landslide susceptibility assessment approach by integrating machine learning models based on random forest(RF),logical regression(LR),and gradient boosting decision tree(GBDT)with interferometric synthetic aperture radar(InSAR)technology and comparing them to their respective original models.The results demonstrated that the combined approach improves prediction accuracy and reduces the false negative and false positive errors.The LR-InSAR model showed the best performance in dynamic landslide susceptibility assessment at both regional and smaller scale,particularly when identifying areas of high and very high susceptibility.Modeling results were verified using data from field investigations including unmanned aerial vehicle(UAV)flights.This study is of great significance to accurately assess dynamic landslide susceptibility and to help reduce and prevent landslide risk.
基金supported by Key Science and Technology Project of China Southern Power Grid(Research on Key Technologies and Demonstration Application of Flexible Coordinated Control of Electromagnetic Loop Network in Metropolitan Power Grid with High Load Density,No.GZHKJ00000101)
文摘This paper proposes a novel hybrid multilevel converter with DC fault-blocking capability, i.e., the neutral-point clamped hybrid multilevel converter(NHMC).By employing two types of unipolar full-bridge submodules along with director switches, which are composed of seriesconnected insulated-gate bipolar transistors, the NHMC combines the features and advantages of the neutral-point clamped converter and the modular multilevel converter.The basic topology, operating principles, modulation scheme, and energy-balancing scheme of the NHMC are presented. The DC fault-blocking capability of the NHMC is investigated. The number of power electronic devices used by the NHMC is calculated and compared with other multilevel converters, showing that the proposed NHMC can be an economical and feasible option for medium-voltage DC transmission with overhead lines. Simulation results demonstrate the features and operating scheme of the proposed NHMC.
基金supported in part by National Key Research and Development Program of China(2017YFB1200801)Continuous Co-phase Traction Power System based on Static Power Converter(20192001148).
文摘A novel DC traction power supply system suitable for energy feeding and de-icing is proposed in this paper for an urban rail transit catenary on the basis of the full bridge submodule (FBSM) modular multilevel converter (MMC). The FBSM-MMC is a novel type of voltage source converter (VSC) and can directly control the output DC voltage and conduct bipolar currents, thus flexibly controlling the power flow of the urban rail transit catenary. The proposed topology can overcome the inherent disadvantages of the output voltage drop in the diode rectifier units, increase the power supply distance and reduce the number of traction substations. The flexible DC technology can coordinate multiple FBSM-MMCs in a wide area and jointly complete the bidirectional control of catenary power flow during the operation of the electric locomotive, so as to realize the local consumption and optimal utilization of the recovered braking energy of the train. In addition, the FBSM-MMCs can also adjust the output current when the locomotive is out of service to prevent the catenary from icing in winter. The working modes of the proposed topology are illustrated in detail and the control strategy is specially designed for normal locomotive operations and catenary de-icing. Simulation cases conducted by PSCAD/EMTDC validate the proposed topology and its control strategy.
