Mode-locked microcombs with flat spectral profiles provide the high signal-to-noise ratio and are in high demand for wavelength division multiplexing(WDM)-based applications,particularly in future high-capacity commun...Mode-locked microcombs with flat spectral profiles provide the high signal-to-noise ratio and are in high demand for wavelength division multiplexing(WDM)-based applications,particularly in future high-capacity communication and parallel optical computing.Here,we present two solutions to generate local relatively flat spectral profiles.One microcavity with ultra-flat integrated dispersion is pumped to generate one relatively flat single soliton source spanning over 150 nm.Besides,one extraordinary soliton crystal with single vacancy demonstrates the local relatively flat microcomb lines when the inner soliton spacings are slightly irregular.Our work paves a new way for soliton-based applications owing to the relatively flat spectral characteristics.展开更多
In this study, the pollutant dispersion within street canyons is studied by experiments conducted in an environmental wind tunnel. The vehicular exhaust emissions are modeled using a line source. The pollutant （smoke...In this study, the pollutant dispersion within street canyons is studied by experiments conducted in an environmental wind tunnel. The vehicular exhaust emissions are modeled using a line source. The pollutant （smoke） concentrations inside the canyons are measured based on a light scattering technique. The pollutant concentrations within the four different street canyons containing the galleries and the three-level flat-roofs under both the isolated and urban environments are obtained and discussed. For each of the four canyon configurations investigated, it is found that there is an obvious discrepancy between the pollutant dispersion patterns under the isolated environment and the urban environment. The three-level fiat roof is found to significantly influence the pollutant distribution pattern in a street canyon. In order to clarify the impacts of the wedge-shaped roofs on the pollutant dispersion inside an urban street canyon of an aspect ratio of 1.0, the pollutant distributions inside urban street canyons of three different wedge-shaped roof combinations are measured and analyzed. It is revealed that the pollutant distribution pattern inside the urban street canyon of an aspect ratio of 1.0 is influenced greatly by the wedge-shaped roof, especially, when an upward wedge-shaped roof is placed on the upstream building of the canyon. Images from this study may be utilized for a rough evaluation of the computational fluid dynamics （CFD） models and for helping architects and urban planners to select the canyon configurations with a minimum negative impact on the local air quality.展开更多
Indoor air dynamics and quality in high density residential buildings can be complex as it is affected by both building parameters,pollution sources,and outdoor meteorological conditions.The present study used CONTAM ...Indoor air dynamics and quality in high density residential buildings can be complex as it is affected by both building parameters,pollution sources,and outdoor meteorological conditions.The present study used CONTAM simulations to investigate the intra-building transport and concentration of an inert pollutant continuously emitted from an underground garage of a 15-floor building under moderate Mediterranean weather.The effects of outdoor meteorological conditions(air temperature,wind speed and direction)on indoor distribution of the emitted pollutant was tested under constant conditions.The importance of using actual transient meteorological data and the impact of their temporal resolution on calculated concentrations and exposure levels were also investigated.Vertical profiles of air exchange rate(AER)and CO concentration were shown to be sensitive to indoor-outdoor temperature difference,which controls the extent of the stack effect and its importance relative to wind effect.Even under constant conditions,transient mode simulations revealed that the time needed for pollutant distribution to reach steady state can be quite long(>24h in some cases).The temporal resolution(Ih vs.8h)of the meteorological data input was also found to impact calculated exposure levels,in an extent that varied with time,meteorological conditions and apartment position.展开更多
基金funding support from Dream X International Innovation Teamthe support from the startup grant from Nanyang Technological University (022527-00001)。
文摘Mode-locked microcombs with flat spectral profiles provide the high signal-to-noise ratio and are in high demand for wavelength division multiplexing(WDM)-based applications,particularly in future high-capacity communication and parallel optical computing.Here,we present two solutions to generate local relatively flat spectral profiles.One microcavity with ultra-flat integrated dispersion is pumped to generate one relatively flat single soliton source spanning over 150 nm.Besides,one extraordinary soliton crystal with single vacancy demonstrates the local relatively flat microcomb lines when the inner soliton spacings are slightly irregular.Our work paves a new way for soliton-based applications owing to the relatively flat spectral characteristics.
基金Project supported by the National Natural Science Foun-dation of China(Grant No.51536006)the Innovation Program of Shanghai Municipal Education Commission(Grant No.10ZZ95)the Hujiang Foundation of China(Grant No.B14003)
文摘In this study, the pollutant dispersion within street canyons is studied by experiments conducted in an environmental wind tunnel. The vehicular exhaust emissions are modeled using a line source. The pollutant （smoke） concentrations inside the canyons are measured based on a light scattering technique. The pollutant concentrations within the four different street canyons containing the galleries and the three-level flat-roofs under both the isolated and urban environments are obtained and discussed. For each of the four canyon configurations investigated, it is found that there is an obvious discrepancy between the pollutant dispersion patterns under the isolated environment and the urban environment. The three-level fiat roof is found to significantly influence the pollutant distribution pattern in a street canyon. In order to clarify the impacts of the wedge-shaped roofs on the pollutant dispersion inside an urban street canyon of an aspect ratio of 1.0, the pollutant distributions inside urban street canyons of three different wedge-shaped roof combinations are measured and analyzed. It is revealed that the pollutant distribution pattern inside the urban street canyon of an aspect ratio of 1.0 is influenced greatly by the wedge-shaped roof, especially, when an upward wedge-shaped roof is placed on the upstream building of the canyon. Images from this study may be utilized for a rough evaluation of the computational fluid dynamics （CFD） models and for helping architects and urban planners to select the canyon configurations with a minimum negative impact on the local air quality.
文摘Indoor air dynamics and quality in high density residential buildings can be complex as it is affected by both building parameters,pollution sources,and outdoor meteorological conditions.The present study used CONTAM simulations to investigate the intra-building transport and concentration of an inert pollutant continuously emitted from an underground garage of a 15-floor building under moderate Mediterranean weather.The effects of outdoor meteorological conditions(air temperature,wind speed and direction)on indoor distribution of the emitted pollutant was tested under constant conditions.The importance of using actual transient meteorological data and the impact of their temporal resolution on calculated concentrations and exposure levels were also investigated.Vertical profiles of air exchange rate(AER)and CO concentration were shown to be sensitive to indoor-outdoor temperature difference,which controls the extent of the stack effect and its importance relative to wind effect.Even under constant conditions,transient mode simulations revealed that the time needed for pollutant distribution to reach steady state can be quite long(>24h in some cases).The temporal resolution(Ih vs.8h)of the meteorological data input was also found to impact calculated exposure levels,in an extent that varied with time,meteorological conditions and apartment position.
