Metal-halide perovskites (MHPs) materials have been prepared into heterojunction nanowires (NWs), which have recently been widely used in micro/nano scale optoelectronic devices. This work designs a core–shell struct...
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As the core component of the optical system, the design of the main mirror not only directly determines the image quality of the camera but also influences the mechanical balance, thermal stability, and the economic e...
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ISBN:
(纸本)9781510683020
As the core component of the optical system, the design of the main mirror not only directly determines the image quality of the camera but also influences the mechanical balance, thermal stability, and the economic efficiency and difficulty of the overall design and manufacture of the space camera. Given the core position of the main mirror in the performance of the camera, achieving its dual optimization design of high precision and lightweight has become the key technical bottleneck and breakthrough point for promoting the innovation of space camera technology and ensuring the efficient and stable operation of the camera in the extreme space environment. In this paper, the SiC material with high specific stiffness and excellent thermal conductivity is selected as the mirror body material, and the flat back open structure and triangular lightweight holes are adopted. The weight is successfully reduced to 6.7 kg, and the lightweight ratio exceeds 70%, which realizes the structural strengthening and thermal stability improvement of the Φ480mm aperture primary mirror. Additionally, to address the challenge of imaging stability for large-aperture and long-focal-length cameras, this paper designs the support structure of the carbon fiber load-bearing tower for the primary and secondary mirrors and adjusts the support structure based on the topological optimization results to ensure stable connection and support between the primary and secondary mirrors and effectively resist the influence of space environment changes on imaging quality. To verify the scientificity and practicability of the design scheme, finite element simulation analysis is conducted to verify the analysis and optimization. The static analysis results indicate that the total rigid body displacement of the mirror assembly meets the requirements. The modal analysis verifies that the first-order natural frequency of the entire structure of the camera's primary and secondary mirrors is 142.76 Hz, which sa
Landslides are a common natural disaster that can result in substantial casualties. One of the region's most vulnerable to landslides in India is Western Ghats. The risk casualty is reduced with the use of the lan...
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With the continuous improvement of optical system imaging quality requirements in astronomy, aerospace engineering, laser technology and other fields, in order to capture lighter objects and improve image resolution, ...
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In recent years,polarization remotesensing has garnered increasing attention,particularly within the realm of *** accurately simulate polarization information,the vector discrete-ordinate radiative transfer(VDISORT)m...
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In recent years,polarization remotesensing has garnered increasing attention,particularly within the realm of *** accurately simulate polarization information,the vector discrete-ordinate radiative transfer(VDISORT)model developed earlier by the community is further enhanced to an advanced version(referred to as A-VDISORT)through an improved ocean surface *** Fresnel reflection matrix,which includes wind-generated roughness and shading effects,is served by an ocean bidirectional reflection distribution function(BRDF).The simulation from AVDISORT is compared with SCIATRAN for a Rayleigh scattering atmosphere,and the influence of water-leaving radiance is analyzed by the PSTAR(Polarized System for Transfer of Atmospheric Radiation) *** GaoFen-5 Directional Polarimetric Camera(DPC) observations with polarization and multi-angle information,clear-sky pixel recognition over the ocean is first carried *** DPC reflectance of clear conditions is normalized and compared with the *** is shown that A-VDISORT has a high simulation accuracy with a bias of –*** difference between simulation and observation exhibits a standard normal probability distribution function.
This study identifies quantitatively the dominant contributions of meteorological factors on the development of the boundary layer heights(BLH)in the European region,based on 32 years(1990-2021)of radiosonde *** spati...
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This study identifies quantitatively the dominant contributions of meteorological factors on the development of the boundary layer heights(BLH)in the European region,based on 32 years(1990-2021)of radiosonde *** spatial variability of the BLH is further discussed by location,by classifying recording stations as inland,coastal,or *** find that the BLH in Europe varies considerably from day to night and with the *** BLH is higher in winter and lower in summer,with the highest BLH recorded at coastal *** BLH at coastal stations shows a bimodal structure with peaks in spring and autumn;at inland and bay stations,daytime BLH is lower in winter and higher in *** daily amplitudes of BLH at the inland and bay stations are stronger than those at coastal *** on our multiple linear regression analysis and our decoupling analysis of temperature and specific humidity,we report that the development of the nighttime BLH at all types of stations is strongly dominated by the variations of surface wind speed(and,at coastal stations,wind directions).The main contributors to daytime BLH are the near-surface temperature variability at most coastal and inland stations,and,at most bay stations,the variation of the near-surface specific humidity.
Macao science Satellite-1(MSS-1)is a two-star constellation mission sponsored jointly by the China National Space Administration(CNSA)and the Macao University of science and technology(MUST).The mission aims to explor...
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Macao science Satellite-1(MSS-1)is a two-star constellation mission sponsored jointly by the China National Space Administration(CNSA)and the Macao University of science and technology(MUST).The mission aims to explore the geomagnetic field and space particle radiation environment in low-inclination low Earth *** satellite A of MSS-1(MSS-1A)carries the third-generation high-energy electron spectrometer(HES),developed by Peking University,to detect high-energy *** HES sensor head utilizes a conventionalΔE-E silicon detector telescope,enabling measurements of high-energy electrons within a 45°cone angle field of view,ranging from 0.3 to 3.0 *** a new generation of high-energy electron detectors(HEDs),the HES operates by default in the in-orbit multi-channel mode,allowing 128 segmented linear distributed energy bin counting measurements with a time resolution of 1 *** energy resolution observations of high-energy electrons in the inner radiation belt by the HES onboard MSS-1A can help investigate the following questions:Do MeVelectrons exist in the inner radiation belt?What is the production mechanism of relativistic electrons in the inner radiation belt?
Evapotranspiration(ET)plays a crucial role in the global water and energy *** instantaneous ET(ET_(i))to daily ET(ET_(d))is vital for thermal-based ET *** methods-such as the constant evaporative fraction method(ConEF...
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Evapotranspiration(ET)plays a crucial role in the global water and energy *** instantaneous ET(ET_(i))to daily ET(ET_(d))is vital for thermal-based ET *** methods-such as the constant evaporative fraction method(ConEF),radiation-based method,and evaporative ratio method-often overlook environmental factors,leading to biased estimates of ET_(d)from ET_(i).To resolve this issue,this study aimed to assess four machine learning(ML)algorithms-XGBoost,LightGBM,AdaBoost,and Random Forest-to integrate meteorological and remotesensing data for upscaling ETi across 88 global flux *** ML model was tested with eight different variable *** indicated that XGBoost exhibited the best performance,with a root mean square error(RMSE)generally below 13 W m^(-2)in estimating ET_(d)from ET_(i).The best variable combination simultaneously considers evaporative fraction,available energy,meteorology factors,remotesensing albedo,normalized vegetation index,and leaf area *** this combination,the XGBoost model achieved an R^(2)=0.88 and an RMSE=12.33 W m^(-2),outperforming the ConEF method(R^(2)=0.71 and RMSE=18.86 Wm^(-2))and its *** findings support the application of ML models in ET upscaling,enabling ET estimation across large spatiotemporal scales.
Discovering ancient agricultural terraces in desert regions is important for the monitoring of long-term climate changes on the Earth's surface. However, traditional ground surveys are both costly and limited in s...
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The potential for future energy crises is a problem the world is currently facing. Many countries are switching from fossil to renewable energy to prevent an energy crisis. One of the most developed renewable energy t...
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The potential for future energy crises is a problem the world is currently facing. Many countries are switching from fossil to renewable energy to prevent an energy crisis. One of the most developed renewable energy today is solar energy. Easy installation makes solar energy installation not only on a large scale but also on a home scale. Urban areas will be very suitable for building solar photovoltaic (PV) roofs due to minimal open areas. In installing rooftop solar PV, sound planning is needed to predict the energy potential that can be provided by solar energy on the rooftop of a building. Spatial modeling can be done to determine the energy potential and suitable location for rooftop solar PV installation. In building rooftop solar PV modeling, the level of detail of the building will affect the results of the model. The rooftop's shape and the building's height will affect the amount of solar radiation going into the building. However, the higher the level of detail of the building, the higher the cost and processing time will be. This study will review the differences in modeling the potential of rooftop solar PV using different levels of detail. This research will integrate solar radiation data from remotesensing to determine the energy potential of solar radiation and digital surface model data from photogrammetry to create a level of detail for buildings. Integration of solar radiation data and the level of detail of the building will use hillshade analysis. Hillshade analysis can review the shadow effect on the rooftop of a building which will be directly related to the potential of solar energy on the rooftop of the building. This study determines the energy potential on the rooftop of the building with different levels of detail, namely 0, 1, and actual shape, to determine the difference in energy potential in the three scenarios. Hopefully, this research will determine the best level of detail for modeling rooftop solar PV. The best model that can sho
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