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大气水平不均匀条件下电波折射修正法——辐射计法 被引量:1
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作者 张瑜 程显海 《飞行器测控技术》 1998年第2期30-33,共4页
对于大气水平不均匀性较大的地区,用59型探空仪测量大气剖面,然后用大气球面分层法计算电波折射误差,其精度不会太高。本文提出了用微波辐射计直接测量电波传播路径上大气射亮度温度而得到电波折射正量的方法-辐射计法。由于辐射... 对于大气水平不均匀性较大的地区,用59型探空仪测量大气剖面,然后用大气球面分层法计算电波折射误差,其精度不会太高。本文提出了用微波辐射计直接测量电波传播路径上大气射亮度温度而得到电波折射正量的方法-辐射计法。由于辐射计法是直接在电波传播路径上进行测量,直接反应大气的空间结构和时变特性,并且不需要施放探空仪,具有方便、灵活、实时、全天候和修正精度高等优点,因此是一种非常实用的高精度电波折射修正方法。 展开更多
关键词 大气 水平不均匀性 电波折射修正 辐射计法
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太阳选择性吸收涂层的中温法向发射比测试对比
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作者 王健 魏其睿 李德杰 《太阳能学报》 EI CAS CSCD 北大核心 2012年第3期409-413,共5页
采用紫外-可见光-红外分光光度计、傅里叶红外光谱仪,在室温条件下,测量Mo-SiO2太阳选择性吸收涂层在空气300℃退火前后0.34~25.00μm波长范围内的近法向反射光谱曲线。假设室温和高温条件下光谱反射特性不变,根据基尔霍夫定律计算出... 采用紫外-可见光-红外分光光度计、傅里叶红外光谱仪,在室温条件下,测量Mo-SiO2太阳选择性吸收涂层在空气300℃退火前后0.34~25.00μm波长范围内的近法向反射光谱曲线。假设室温和高温条件下光谱反射特性不变,根据基尔霍夫定律计算出涂层在不同温度下的法向发射比。采用辐射计法,测量同一片样品在200℃、300℃时的法向发射比,两种方法得出的数值差异仅为0.02~0.03。经误差分析发现,在保证涂层退火前后反射光谱曲线不变、工作温度不超过300℃的情况下,基于室温反射光谱曲线和中温辐射计法的结果在测试仪器的误差范围内基本等效。 展开更多
关键词 太阳选择性吸收涂层 向发射比 反射光谱 辐射计法
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便携式半球发射率测试仪设计 被引量:1
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作者 冀中祥 《科技风》 2017年第3期120-120,共1页
通过合理设计,设计研究了一种便携式半球发射率测试仪。该文着重叙述了测试仪的测试原理、结构组成、测试过程及测量精度分析等。此设计研究对材料半球发射率的测试及新材料的研究有着十分重要的意义。
关键词 半球发射率 辐射计法 隔热涂料 便携式
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A new algorithm for sea-surface wind-speed retrieval based on the L-band radiometer onboard Aquarius 被引量:3
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作者 王进 张杰 +1 位作者 范陈清 王晶 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2015年第5期1115-1123,共9页
Aquarius is the second satellite mission to focus on the remote sensing of sea-surface salinity from space and it has mapped global sea-surface salinity for nearly 3 years since its launch in 2011. However,benefiting ... Aquarius is the second satellite mission to focus on the remote sensing of sea-surface salinity from space and it has mapped global sea-surface salinity for nearly 3 years since its launch in 2011. However,benefiting from the high atmospheric transparency and moderate sensitivity to wind speed of the L-band brightness temperature(TB),the Aquarius L-band radiometer can actually provide a new technique for the remote sensing of wind speed. In this article,the sea-surface wind speeds derived from TBs measured by Aquarius' L-band radiometer are presented,the algorithm for which is developed and validated using multisource wind speed data,including Wind Sat microwave radiometer and National Data Buoy Center buoy data,and the Hurricane Research Division of the Atlantic Oceanographic and Meteorological Laboratory wind field product. The error analysis indicates that the performance of retrieval algorithm is good. The RMSE of the Aquarius wind-speed algorithm is about 1 and 1.5 m/s for global oceans and areas of tropical hurricanes,respectively. Consequently,the applicability of using the Aquarius L-band radiometer as a near all-weather wind-speed measuring method is verified. 展开更多
关键词 microwave radiometer Aquarius wind speed L-BAND
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Stratospheric Aerosol Extinction Profile Retrieval from SCIAMACHY Limb Measurements 被引量:1
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作者 YANG Jing-Mei ZONG Xue-Mei 《Atmospheric and Oceanic Science Letters》 CSCD 2014年第3期265-268,共4页
Stratospheric aerosol extinction profiles are retrieved from Scanning Imaging Absorption Spectrometer for Atmospheric Cartography(SCIAMACHY) limb scatter measurements.In the process of retrieval,the SCIATRAN radiative... Stratospheric aerosol extinction profiles are retrieved from Scanning Imaging Absorption Spectrometer for Atmospheric Cartography(SCIAMACHY) limb scatter measurements.In the process of retrieval,the SCIATRAN radiative transfer model is used to simulate the limb scattering radiation received by the SCIAMACHY instrument,and an optimal estimation algorithm is used to calculate the aerosol extinction profiles.Sensitivity analyses are performed to investigate the impact of the surface albedo on the accuracy of the retrieved aerosol extinction profiles in the northern midlatitudes.It is found that the errors resulting from the bias of the assumed surface albedo in the retrieval are generally below 6%.The retrieved SCIAMACHY aerosol extinction profiles are compared with corresponding Stratospheric Aerosol and Gas Experiment(SAGE) II measurements,and the results indicate that for the zonal mean profiles,the SCIAMACHY retrievals show good agreement with SAGE II measurements,with the absolute differences being less than 2.3×10-5 km-1 from 14–25 km,and less than 5.9×10-6 km-1 from 25–35 km;and the relative differences being within 20% over the latitude range of 14–35 km. 展开更多
关键词 AEROSOL extinction profileSCIAMACHY limb measurements
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Estimating the Predictability of the Quasi-Biweekly Oscillation Using the Nonlinear Local Lyapunov Exponent Approach 被引量:1
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作者 SHI Zhen DING Rui-Qiang 《Atmospheric and Oceanic Science Letters》 2012年第5期389-393,共5页
The quasi-biweekly oscillation (QBWO) is a major intraseasonal variability (ISV) in the tropics. Based on bandpass-filtered outgoing longwave radiation (OLR) and wind field data, the predictability limits of the QBWO ... The quasi-biweekly oscillation (QBWO) is a major intraseasonal variability (ISV) in the tropics. Based on bandpass-filtered outgoing longwave radiation (OLR) and wind field data, the predictability limits of the QBWO in boreal summer and boreal winter are investigated using the nonlinear local Lyapunov exponent (NLLE) approach The analysis shows that the evolution of the mean error growth of the QBWO in boreal summer and the evolution of the mean error growth in boreal winter are comparable Both curves exhibit rapid growth in the initial stage followed by a slowly fluctuating, ascending trend before saturation is reached. As a result, the potential predictability limits for the boreal summer QBWO are very close to those for the boreal winter QBWO, with a lead time of approximately three weeks. Given the current limitations in the simulation and prediction of ISV, including the QBWO, the results of this study provide a useful reference for assessing the predictability of the QBWO using model simulations. 展开更多
关键词 QBWO EOF PREDICTABILITY NLLE
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Imaging algorithm for synthetic aperture interferometric radiometer in near field 被引量:4
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作者 ZHANG Cheng WU Ji +1 位作者 LIU Hao YAN JingYe 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第8期2224-2231,共8页
With the benefits of digital IC technology development, the synthetic aperture interferometric radiometer (SAIR) technique is growing fast and expanding to more and more application areas. The near field imaging detec... With the benefits of digital IC technology development, the synthetic aperture interferometric radiometer (SAIR) technique is growing fast and expanding to more and more application areas. The near field imaging detection is a potential application which has received increasing demand recently. Because the Fourier imaging theory of the traditional SAIR is based on far-field approximation, it will be invalid for near-field condition. This paper is devoted to establishing a new accurate imaging algorithm for near-field SAIR imaging. Firstly, the visibility function in near field is deduced and the relationship of which to far-field visibility function is analyzed. Then, a numerical method based on pseudo inverse and focal plane approximation is developed. The effectivity of this method is tested with imaging simulation of point source and extended source, and the superiority is also demonstrated by comparing with the existing phase-modified Fourier transform method. At last, the field experiment with one-dimensional SAIR instrument is performed to validate the practical feasibility of this method. 展开更多
关键词 synthetic aperture interferometric radiomter (SAIR) near field imaging numerical method pseudo inversion
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A study of the acoustical radiation force considering attenuation 被引量:3
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作者 WU RongRong LIU XiaoZhou GONG XiuFen 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第7期1237-1245,共9页
Acoustical tweezer is a primary application of the radiation force of a sound field. When an ultrasound focused beam passes through a micro-particle, like a cell or living biological specimens, the particle will be ma... Acoustical tweezer is a primary application of the radiation force of a sound field. When an ultrasound focused beam passes through a micro-particle, like a cell or living biological specimens, the particle will be manipulated accurately without physical contact and invasion, due to the three-dimensional acoustical trapping force. Based on the Ray acoustics approach in the Mie regime, this work discusses the effects on the particle caused by Gaussian focused ultrasound, studies the acoustical trapping force of spherical Mie particles by ultrasound in any position, and analyzes the numerical calculation on the two-dimensional acoustical radiation force. This article also analyzes the conditions for the acoustical trapping phenomenon, and discusses the impact of the initial position and size of the particle on the magnitude of the acoustical radiation force. Furthermore, this paper considers the ultrasonic attenuation in a particle in the case of two-dimension, studies the attenuation's effects on the acoustical trapping force, and amends the calculation to the ordinary case with attenuation. 展开更多
关键词 radiation force ultrasonic attenuation acoustical tweezers trapping force
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Terahertz band simulations using two different radiative transfer models
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作者 Linjun PAN Daren Lü 《Science China Earth Sciences》 SCIE EI CAS CSCD 2018年第10期1482-1490,共9页
A high-resolution dual-band terahertz(THz) radiometer was designed to measure vertical distributions of chemical elements in the middle atmosphere of the Tibetan Plateau. A forward simulation, which always should be c... A high-resolution dual-band terahertz(THz) radiometer was designed to measure vertical distributions of chemical elements in the middle atmosphere of the Tibetan Plateau. A forward simulation, which always should be conducted firstly for the development of a matching retrieval algorithm, has not been done before. We use two radiative transfer models, ARTS and AM, to simulate the water vapor, ozone and carbon monoxide spectra on the plateau based on the spectral design of the THz radiometer. The emission line characteristics of the three gases in this spectral band are identified. Reasons for the differences in the spectral simulations between the two models are analyzed for individual gases. The impact of several different spectral parameter settings on the simulations are evaluated through a series of sensitivity experiments. This study suggests that the ARTS is more suitable for the development of the THz radiometer retrieval algorithm. An optimal parameter setting of the ARTS for the three elements are given. 展开更多
关键词 Terahertz radiation RADIOMETER Radiative transfer model Spectral simulation PLATEAU
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The development of an algorithm to enhance and match the resolution of satellite measurements from AMSR-E 被引量:4
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作者 WANG YongQian SHI JianCheng +2 位作者 JIANG LingMei DU JinYang TIAN BangSen 《Science China Earth Sciences》 SCIE EI CAS 2011年第3期410-419,共10页
Microwave radiometers have many applications because of their penetration ability. However, two major problems remain that obstruct the development of microwave research. One factor that limits their commercial applic... Microwave radiometers have many applications because of their penetration ability. However, two major problems remain that obstruct the development of microwave research. One factor that limits their commercial application is the relatively low resolution of microwave radiometers. The other is the non-uniform spatial resolution for each frequency of the radiometer. The resolution mismatch becomes a critical consideration when observations at two or more frequencies must be combined. In this paper, we have used the Backus-Gilbert method to solve these two problems, while AMSR-E is chosen as the research object. First, we derived the Backus-Gilbert method in detail. The simulated data were then used to decide the optimum parameters in the Backus-Gilbert method. To enhance the resolution, the Backus-Gilbert method has been applied to the AMSR-E data, which covered the Mexico Gulf and the Amazon River. After resolution was enhanced, detailed information was obtained and compared with visible high resolution data. To match the resolution, the AMSR-E data from the Oklahoma Little Washed were used to compute the Microwave Vegetation Index (MVI), which was developed by J. C. Shi. Compared to the original MVIs, the information contained in the MVIs that were processed by the Backus-Gilbert method is more reliable. 展开更多
关键词 AMSR-E resolution enhancement resolution match Backus-Gilbert
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Comparison of Extrapolation and Interpolation Methods for Estimating Daily Photosynthetically Active Radiation(PAR)——A Case Study of the Poyang Lake National Nature Reserve,China 被引量:1
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作者 WU Guofeng Jan de Leeuw +2 位作者 Andrew K. Skidmore LIU Yaolin Herbert H. T. Prins 《Geo-Spatial Information Science》 2010年第4期235-242,共8页
Measurements of photosynthetically active radiation (PAR), which are indispensable for simulating plant growth and productivity, are generally very scarce. This study aimed to compare two extrapolation and one inte... Measurements of photosynthetically active radiation (PAR), which are indispensable for simulating plant growth and productivity, are generally very scarce. This study aimed to compare two extrapolation and one interpolation methods for estimating daily PAR reaching the earth surface within the Poyang Lake national nature reserve, China. The daily global solar radiation records at Nanchang meteorological station and daily sunshine duration measurements at nine meteorological stations around Poyang Lake were obtained to achieve the objective. Two extrapolation methods of PARs using recorded and estimated global solar radiation at Nanchang station and three stations (Yongxiu, Xingzi and Duchang) near the nature reserve were carried out, respectively, and a spatial interpolation method combining triangulated irregular network (TIN) and inverse distance weighting (IDW) was imple- mented to estimate daily PAR. The performance evaluation of the three methods using the PARs measured at Dahuchi Conservation Station (day number of measurement = 105 days) revealed that: (1) the spatial interpolation method achieved the best PAR estima- tion (R2 - 0.89, s.c. = 0.99, F= 830.02, P 〈 0.001 ); (2) the extrapolation method from Nanchang station obtained an unbiased result (R2 = 0.88, s.c. = 0.99, F = 745.29, P 〈 0.001); however, (3) the extrapolation methods from Yongxiu, Xingzi and Duchang stations were not suitable for this specific site for their biased estimations. Considering the assumptions and principles supporting the extrapolation and interpolation methods, the authors conclude that the spatial interpolation method produces more reliable results than the extrapolation methods and holds the greatest potential in all tested methods, and more PAR measurements should be recorded to evaluate the seasonal, yearly and spatial stabilities of these models for their application to the whole nature reserve of Poyang Lake. 展开更多
关键词 photosynthetically active radiation (PAR) EXTRAPOLATION INTERPOLATION triangulated irregular network (TIN) inverse distance weighting (IDW)
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Enhanced emission at 2.85 μm of Ho^(3+)/Pr^(3+) co-doped α-Na YF_4 single crystal
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作者 王成 夏海平 +8 位作者 冯治刚 张志雄 江东升 张健 盛启国 汤庆阳 何仕楠 江浩川 陈宝玖 《Optoelectronics Letters》 EI 2016年第1期56-60,共5页
The Ho^(3+)/Pr^(3+) co-doped Na YF4 single crystals with various Pr^(3+) concentrations and constant Ho^(3+) molar percentage of ~1% were grown by an improved Bridgman method.Compared with the Ho^(3+) single-doped Na ... The Ho^(3+)/Pr^(3+) co-doped Na YF4 single crystals with various Pr^(3+) concentrations and constant Ho^(3+) molar percentage of ~1% were grown by an improved Bridgman method.Compared with the Ho^(3+) single-doped Na YF4 crystal,an obviously enhanced emission band at 2.85 μm is observed under 640 nm excitation.The Judd-Ofelt strength parameters(?2,?4 and ?6) are calculated,the radiative transition probabilities(A),the fluorescence branching ratios(β) and the radiative lifetime(τrad) are obtained in the meantime.The energy transfer from Pr^(3+) to Ho^(3+) and the optimum fluorescence emission of Ho^(3+) ions around 2.85 μm are investigated.Moreover,the maximum emission cross section of above samples at 2.85 μm is calculated to be 0.72×10^(-20) cm2 for the Na YF4 single crystal with Ho^(3+) molar percentage of 1% and Pr^(3+) molar percentage of 0.5% according to the measured absorption spectrum.All results suggest that the Ho^(3+)/Pr^(3+) co-doped Na YF4 single crystal may have potential applications in mid-infrared lasers. 展开更多
关键词 Absorption spectroscopy Crystal growth from melt Energy transfer FLUORESCENCE Optical glass
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