On May 21,2023,the Macao Science Satellite-1B(MSS-1B),a low-inclination,low-latitude,and high-precision scientific exploration satellite for geomagnetic fields and space environments,was successfully launched.The sola...On May 21,2023,the Macao Science Satellite-1B(MSS-1B),a low-inclination,low-latitude,and high-precision scientific exploration satellite for geomagnetic fields and space environments,was successfully launched.The solar X-ray detector(SXD),one of the two major scientific payloads onboard the MSS-1B,has obtained a large amount of solar X-ray radiation data,which reveals the distribution law of the magnetic field in the low Earth orbit,as well as the coupling law of the Earth's magnetic field and the solar radiation and energy particle distributions.First,the overall design of the multi-detection-unit,broad-energy-range,small-volume,and low-power SXD was implemented to achieve the scientific objectives of the mission.Second,the technical indicators of the instrument were decomposed into various components,and the key technologies,such as collimator,processing circuit,thermal,and payload dataset designs,were reviewed.Third,the backgrounds,including electronic noise,cosmic diffuse X-ray background,and high-energy background in the Earth's radiation belts in and out of the field of view,were analyzed for the instrument.Then,the ground calibrations of the energy response,detection efficiency,and temperature-dependent peak drift of the SXD flight model were conducted.Finally,the in-orbit temperature,energy spectrum data,background,and solar flare process observation of the instrument in the in-orbit test stage are presented,verifying the instrument design,analysis,and ground calibration,providing a foundation for obtaining accurate solar X-ray radiation data,and achieving the scientific objectives of the satellite.展开更多
Survivability is used to evaluate the ability of the satellite to complete the mission after failure,while the duration of maintaining performance is often ignored.An effective backup strategy can restore the constell...Survivability is used to evaluate the ability of the satellite to complete the mission after failure,while the duration of maintaining performance is often ignored.An effective backup strategy can restore the constellation performance timely,and maintain good network communication performance in case of satellite failure.From the perspective of network utility,the low Earth orbit(LEO)satellite constellation survivable graphical eva-luation and review technology(GERT)network with backup satel-lites is constructed.A network utility transfer function algorithm based on moment generating function and Mason formula is proposed,the network survivability evaluation models of on-orbit backup strategy and ground backup strategy are established.The survivable GERT model can deduce the expected mainte-nance time of LEO satellite constellation under different fault states and the network utility generated during the state mainte-nance period.The case analysis shows that the proposed surviv-able GERT model can consider the satellite failure rate,backup satellite replacement rate,maneuver control replacement ability and life requirement,and effectively determine the optimal sur-vivable backup strategy for LEO satellite constellation with limi-ted resources according to the expected network utility.展开更多
Since Prof. Jorg SCHLAICH from the University of Stuttgart in Germany built the first solar chimney power plant （SCPP） prototype in the early 1980s, research on SCPP technology has aroused worldwide attention from e...Since Prof. Jorg SCHLAICH from the University of Stuttgart in Germany built the first solar chimney power plant （SCPP） prototype in the early 1980s, research on SCPP technology has aroused worldwide attention from experiment, to theory and then feasibility studies for large-scale commercial application.展开更多
Super-long span bridges demand high design requirements and involve many difficulties when constructed,which is an important indicator to reflect the bridge technical level of a country.Over the past three decades,a l...Super-long span bridges demand high design requirements and involve many difficulties when constructed,which is an important indicator to reflect the bridge technical level of a country.Over the past three decades,a large percentage of the new long-span bridges around the world were built in China,and thus,abundant technological innovations and experience have been accumulated during the design and construction.This paper aims to review and summarize the design and construction practices of the superstructure,the substructure,and the steel deck paving of the long-span bridges during the past decades as well as the current operation status of the existing long-span bridges in China.A future perspective was given on the developing trend of high-speed railway bridge,bridge over deep-sea,health monitoring and maintenance,intellectualization,standard system,and information technology,which is expected to guide the development direction for the construction of future super long-span bridges and promote China to become a strong bridge construction country.展开更多
The photovoltaic-thermal collector is one of the most interesting technology for solar energy conversion,com-bining electric and thermal energy production in a single device.Vapour-compression heat pump is already con...The photovoltaic-thermal collector is one of the most interesting technology for solar energy conversion,com-bining electric and thermal energy production in a single device.Vapour-compression heat pump is already considered the most suitable clean technology for buildings thermal energy needs.The combination of these two technologies in an integrated“photovoltaic-thermal solar-assisted heat pump”(PVT-SAHP)system allows reaching a high fraction of the building thermal needs covered by renewable energy sources and to improve the performances of both the photovoltaic-thermal collector and the heat pump.The first is cooled down increasing its energy conversion efficiency,while providing low-temperature thermal energy to the second,which benefits from a higher evaporation temperature.The review study presents the state-of-art of photovoltaic-thermal solar-assisted heat pump systems intended to cover thermal energy needs in buildings,with a particular focus on the integration methodologies,the possible configurations,the use of different sources and the design of sub-system components.These issues are addressed by much scientific research,to improve the reliability and applicability of this technology,as an option for the building decarbonization.This study aims to present PVT-SAHP systems in an organic and critical way to propose a useful tool for future research developments.More in detail,the work highlights the fact that the integration of photovoltaic-thermal collectors as evaporator of the heat pump in direct-expansion systems allows the highest heat recovery and performances.However,the distinction of the two circuits lead to more reliable,flexible and robust systems,especially when combined with a second heat source,being able to cover both heating and cooling needs.The implementation of real-time control strategy,as well as the continuous development of the compressor and refrigerant industries is positively influencing this technology,which is receiving more and more attention from scientific research as a suitable solution for nearly zero energy buildings.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42327802)the National Key R&D Program of China(Grant No.2022YFF0708100)。
文摘On May 21,2023,the Macao Science Satellite-1B(MSS-1B),a low-inclination,low-latitude,and high-precision scientific exploration satellite for geomagnetic fields and space environments,was successfully launched.The solar X-ray detector(SXD),one of the two major scientific payloads onboard the MSS-1B,has obtained a large amount of solar X-ray radiation data,which reveals the distribution law of the magnetic field in the low Earth orbit,as well as the coupling law of the Earth's magnetic field and the solar radiation and energy particle distributions.First,the overall design of the multi-detection-unit,broad-energy-range,small-volume,and low-power SXD was implemented to achieve the scientific objectives of the mission.Second,the technical indicators of the instrument were decomposed into various components,and the key technologies,such as collimator,processing circuit,thermal,and payload dataset designs,were reviewed.Third,the backgrounds,including electronic noise,cosmic diffuse X-ray background,and high-energy background in the Earth's radiation belts in and out of the field of view,were analyzed for the instrument.Then,the ground calibrations of the energy response,detection efficiency,and temperature-dependent peak drift of the SXD flight model were conducted.Finally,the in-orbit temperature,energy spectrum data,background,and solar flare process observation of the instrument in the in-orbit test stage are presented,verifying the instrument design,analysis,and ground calibration,providing a foundation for obtaining accurate solar X-ray radiation data,and achieving the scientific objectives of the satellite.
基金This work was supported by the National Natural Science Foundation of China(72271124,52232014,72071111,71801127,71671091).
文摘Survivability is used to evaluate the ability of the satellite to complete the mission after failure,while the duration of maintaining performance is often ignored.An effective backup strategy can restore the constellation performance timely,and maintain good network communication performance in case of satellite failure.From the perspective of network utility,the low Earth orbit(LEO)satellite constellation survivable graphical eva-luation and review technology(GERT)network with backup satel-lites is constructed.A network utility transfer function algorithm based on moment generating function and Mason formula is proposed,the network survivability evaluation models of on-orbit backup strategy and ground backup strategy are established.The survivable GERT model can deduce the expected mainte-nance time of LEO satellite constellation under different fault states and the network utility generated during the state mainte-nance period.The case analysis shows that the proposed surviv-able GERT model can consider the satellite failure rate,backup satellite replacement rate,maneuver control replacement ability and life requirement,and effectively determine the optimal sur-vivable backup strategy for LEO satellite constellation with limi-ted resources according to the expected network utility.
文摘Since Prof. Jorg SCHLAICH from the University of Stuttgart in Germany built the first solar chimney power plant （SCPP） prototype in the early 1980s, research on SCPP technology has aroused worldwide attention from experiment, to theory and then feasibility studies for large-scale commercial application.
文摘Super-long span bridges demand high design requirements and involve many difficulties when constructed,which is an important indicator to reflect the bridge technical level of a country.Over the past three decades,a large percentage of the new long-span bridges around the world were built in China,and thus,abundant technological innovations and experience have been accumulated during the design and construction.This paper aims to review and summarize the design and construction practices of the superstructure,the substructure,and the steel deck paving of the long-span bridges during the past decades as well as the current operation status of the existing long-span bridges in China.A future perspective was given on the developing trend of high-speed railway bridge,bridge over deep-sea,health monitoring and maintenance,intellectualization,standard system,and information technology,which is expected to guide the development direction for the construction of future super long-span bridges and promote China to become a strong bridge construction country.
文摘The photovoltaic-thermal collector is one of the most interesting technology for solar energy conversion,com-bining electric and thermal energy production in a single device.Vapour-compression heat pump is already considered the most suitable clean technology for buildings thermal energy needs.The combination of these two technologies in an integrated“photovoltaic-thermal solar-assisted heat pump”(PVT-SAHP)system allows reaching a high fraction of the building thermal needs covered by renewable energy sources and to improve the performances of both the photovoltaic-thermal collector and the heat pump.The first is cooled down increasing its energy conversion efficiency,while providing low-temperature thermal energy to the second,which benefits from a higher evaporation temperature.The review study presents the state-of-art of photovoltaic-thermal solar-assisted heat pump systems intended to cover thermal energy needs in buildings,with a particular focus on the integration methodologies,the possible configurations,the use of different sources and the design of sub-system components.These issues are addressed by much scientific research,to improve the reliability and applicability of this technology,as an option for the building decarbonization.This study aims to present PVT-SAHP systems in an organic and critical way to propose a useful tool for future research developments.More in detail,the work highlights the fact that the integration of photovoltaic-thermal collectors as evaporator of the heat pump in direct-expansion systems allows the highest heat recovery and performances.However,the distinction of the two circuits lead to more reliable,flexible and robust systems,especially when combined with a second heat source,being able to cover both heating and cooling needs.The implementation of real-time control strategy,as well as the continuous development of the compressor and refrigerant industries is positively influencing this technology,which is receiving more and more attention from scientific research as a suitable solution for nearly zero energy buildings.
