Apparent directional spectral emissivity determination of semitransparent materials

An inverse estimation method and corresponding measurement system are developed to measure the apparent spectral directional emissivities of semitransparent materials. The normal spectral emissivity and transmissivity serve as input for the inverse analysis. Consequently, the refractive index and absorption coefficient of the semitransparent material could be retrieved by using the pseudo source adding method as the forward method and the stochastic particle swarm optimization algorithm as the inverse method. Finally, the arbitrary apparent spectral directional emissivity of semitransparent material is estimated by using the pseudo source adding method given the retrieval refractive index and absorption coefficient. The present system has the advantage of a simple experimental structure, high accuracy, and excellent capability to measure the emissivity in an arbitrary direction. Furthermore, the apparent spectral directional emissivity of sapphire at 773 K is measured by using this system in a spectral range of 3 μm-12 μm and a viewing range of 0°-90°. The present method paves the way for a new directional spectral emissivity measurement strategy.

Underwater Directional Acoustic Source Based on Pentamode Material

An underwater directional acoustic emitter is conceived with a highly anisotropic lattice material,whose acoustic characteristics manifest strong dependence on the orientation of the lattice material’s principal axis.Exploiting these features,a cylindrical structure made of such anisotropic lattice material is engineered to possess distinct impedance values in different directions,thereby facilitating wave emission along the principal axis while inducing reflection in other directions.Notably,through numerical simulations,it is demonstrated that the emission direction can be effectively manipulated by adjusting the principal axis orientation,concurrently enhancing the emitted power.In contrast to previous directional acoustic structures,the compact emitter presented in this study can get rid of the size-wavelength constraint,enabling effective control of low-frequency waves.

Mapping urban carbon emissions in relation to local climate zones:Case of the building sector in Bangkok Metropolitan Administration,Thailand

This study focuses on carbon emissions of the building sector in relation to local climate zone(LCZ)classification,concentrating on two major parts.First,we estimated carbon emissions in the building sector,which were cal-culated for weekdays and weekends real-time daily energy consumption patterns.The estimations were divided into direct(from petroleum products consumption)and indirect emissions(from electricity consumption).Sec-ond,we examined urban carbon emissions mapping in relation to LCZ.Bangkok Metropolitan Administration(BMA)was used as the case study and 2016 as the base year for examination.The results illustrate that indirect emissions in Bangkok can be up to ten times higher than direct emissions.The analysis indicates that LCZ,such as compact high-rise,large low-rise,light industry,and warehouse zones had a relatively higher carbon emission intensity than others.Additionally,we identified that the compact high-rise zone has the highest indirect emission intensity,while the light industry and warehouse zone have the greatest direct emission intensity.These results provide insights into the dynamics of carbon emission characteristics in the building sector and the methodology purported here can be used to support low carbon city planning and policymaking in Bangkok.

Influencing factors and paths of direct carbon emissions from the energy consumption of rural residents in central China determined using a questionnaire survey

Rural residents have unique lifestyle characteristics,energy consumption methods,energy-saving behaviors,and awareness.And the direct carbon emission from rural residents is based on the combined effect of multiple factors.In order to address the complexity of factors affecting the direct carbon emissions from rural household,this study used a structural equation model to examine the effect of multi-factor variables on direct carbon emissions from rural households in central China.Data were collected using questionnaires and surveys in six cities in central China to reflect the daily reality of rural residents.The results show that quality of life and awareness of energy conservation can affect the direct carbon emissions of rural residents.Family characteristics and awareness of energy conservation affected carbon emissions indirectly by affecting the daily behaviors and quality of life of the residents;consumption characteristics,energy-saving behaviors,and energy conservation policies are not the main factors contributing to the direct carbon emissions of the residents.Based on the results,future studies can focus on energy conservation education,improvement of the living habits,coal energy use efficiency,and energy consumption structure of residences.

Interprovincial transfer of embodied air pollution in China

This study uses a multi-regional input-output model to measure the consumption-based transfer of embodied air pollution across provinces in China.Revised direct exhaust emissions are compared under regional and industrial standards to reveal the static volume distribution and dynamic transfer paths.The results show that China is characterized by a net inflow of atmospheric pollution pressure.The amount of interprovincial transfer exhibits a two-level divergence.The distribution of net outflow areas exhibits a certain degree of dispersion and uniformity,whereas net inflow areas exhibit local agglomeration.The main transfer paths are from east to west and south to north.Eastern coastal areas are the primary source of embodied pollution transfer,whereas northern coastal areas and the middle reaches of the Yellow River account for the primary concentrations of pollution inflows.The proportion of major industry contributions approximately conforms to the Pareto principle;different resource endowments may provide comparative advantages and thus distinct distributions.

Room-temperature continuous-wave InP-based 2.01 μm microcavity lasers in whispering-gallery modes with InGaAsSb quantum well

We demonstrated an electrically pumped InP-based microcavity laser operating in continuous-wave mode.The active region is designed with antimony surfactants to enhance the gain at 2 μm,and a selective electrical isolation scheme is used to secure continuous-wave operation for the microcavity laser at room temperature.The lasers were fabricated as a notched elliptical resonator,resulting in a highly unidirectional far-field profile with an in-plane beam divergence of less than 2°.Single-mode emission was obtained over the entire dynamic range,and the laser frequencies were tuned linearly with the pumping current.Overall,these directional lasers pave the way for portable and highly integrated on-chip sensing applications.