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Calibration and data restoration of light field modulated imaging spectrometer
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作者 Li-Juan Su Qiang-Qiang Yan +2 位作者 Yan Yuan Shi-Feng Wang Yu-Jian Liu 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第8期179-186,共8页
A light field modulated imaging spectrometer (LFMIS) can acquire the spatial-spectral datacube of targets of interest or a scene in a single shot. The spectral information of a point target is imaged on the pixels c... A light field modulated imaging spectrometer (LFMIS) can acquire the spatial-spectral datacube of targets of interest or a scene in a single shot. The spectral information of a point target is imaged on the pixels covered by a microlens. The pixels receive spectral information from different spectral filters to the diffraction and misalignments of the optical components. In this paper, we present a linear spectral multiplexing model of the acquired target spectrum. A calibration method is proposed for calibrating the center wavelengths and bandwidths of channels of an LFMIS system based on the liner-variable filter (LVF) and for determining the spectral multiplexing matrix. In order to improve the accuracy of the restored spectral data, we introduce a reconstruction algorithm based on the total least square (TLS) approach. Simulation and experimental results confirm the performance of the spectrum reconstruction algorithm and validate the feasibility of the proposed calibrating scheme. 展开更多
关键词 light field modulated imaging spectrometer linear-variable filter spectral calibration spectral re-construction
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An Operational Method for Fast Detecting Abnormal Channels in Imaging Spectrometers
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作者 MA Jiping LI Deren TONG Qingxi ZHENG Lanfen 《Geo-Spatial Information Science》 2002年第4期50-54,共5页
Data from abnormal channels in an imaging spectrometer almost always exerts an undesired impact on spectrum matching,classification,pattern recognition and other applications in hyperspectral remote sensing.To solve t... Data from abnormal channels in an imaging spectrometer almost always exerts an undesired impact on spectrum matching,classification,pattern recognition and other applications in hyperspectral remote sensing.To solve this problem,researchers should get rid of the data acquired by these channels.Selecting abnormal channels just in the way of visually examining each band image in a imaging data set is a conceivably hard and boring job.To relieve the burden,this paper proposes a method which exploits the spatial and spectral autocorrelations inherent in imaging spectrometer data,and can be used to speed up and,to a great degree,automate the detection of abnormal channels in an imaging spectrometer.This method is applied easily and successfully to one PHI data set and one Hymap data set,and can be applied to remotely sensed data from other hyperspectral sensors. 展开更多
关键词 imaging spectrometer mutual information IHR
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Performance Comparison of Long-Wave Infrared Imaging Spectrometer Between Dyson Form and Offner Form
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作者 Jiayin Sun Ying Liu +3 位作者 Qiang Sun Chun Li Jian Wang Yang Jiang 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2017年第2期45-50,共6页
In view of the difficulties in traditional long-wave infrared imaging spectrometer which is hard to realize a high signal-to-noise ratio and miniaturization as well under the weak remote sensing signal,Offner convex g... In view of the difficulties in traditional long-wave infrared imaging spectrometer which is hard to realize a high signal-to-noise ratio and miniaturization as well under the weak remote sensing signal,Offner convex grating spectrometer and Dyson concave grating spectrometer,both having concentric structure,are designed and analyzed in the band of 8-12 μm. The diffraction angle expressions of the two spectrometers are obtained and the diffraction characteristics are acquired. Both of the spectrometers are designed in Zemax environment under different F-numbers and different grating constants with the same slit,spatial resolution,spectral resolution and detector. The results show that Dyson grating spectrometer possesses the advantages of higher throughput and smaller volume, and Offner grating spectrometer possesses the advantage of more accessible material and the absence of chromatic aberration. The differences between Dyson form and Offner form show that the former is a better choice in the long-wave infrared imaging spectrometer. 展开更多
关键词 long-wave infrared imaging spectrometer grating constant concentric configuration
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An imaging spectrometer employing tunable hyperchromatic microlenses 被引量:1
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作者 Phuong-Ha Cu-Nguyen Adrian Grewe +3 位作者 Patrik Feßer Andreas Seifert Stefan Sinzinger Hans Zappe 《Light(Science & Applications)》 SCIE EI CAS CSCD 2015年第1期33-41,共9页
We present the design,fabrication and characterization of hydraulically-tunable hyperchromatic lenses for two-dimensional(2D)spectrally-resolved spectral imaging.These hyperchromatic lenses,consisting of a positive di... We present the design,fabrication and characterization of hydraulically-tunable hyperchromatic lenses for two-dimensional(2D)spectrally-resolved spectral imaging.These hyperchromatic lenses,consisting of a positive diffractive lens and a tunable concave lens,are designed to have a large longitudinal chromatic dispersion and the images of different wavelengths from each other.2D objects of different wavelengths can consequently be imaged using the tunability of the lens system.Two hyperchromatic lens concepts are demonstrated and their spectral characteristics as well as their functionality in spectral imaging applications are shown. 展开更多
关键词 hyperchromatic lens imaging spectrometer tunable filter tunable lens
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A New Method for Measurements of the Poloidal Rotation Velocities and Wavelength Calibration of X-ray Imaging Crystal Spectrometer in Magnetic Fusion Devices
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作者 石跃江 吕波 +3 位作者 王福地 M.BITTER K.W.HILL 叶民友 《Plasma Science and Technology》 SCIE EI CAS CSCD 2015年第4期265-267,共3页
A new simple method is presented for the wavelength calibration and measurement of poloidal rotation velocities with X-ray imaging crystal spectrometer(XICS)in magnetic fusion devices.In this method,the toroidal rot... A new simple method is presented for the wavelength calibration and measurement of poloidal rotation velocities with X-ray imaging crystal spectrometer(XICS)in magnetic fusion devices.In this method,the toroidal rotation of plasma is applied for high precise alignment and wavelength calibration of the poloidal XICS.The measurement threshold of poloidal rotation velocity can be lowered to 1-3 km/s with this method. 展开更多
关键词 X-ray imaging crystal spectrometer wavelength calibration poloidal rotation velocity
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Modeling and analysis for the image mapping spectrometer 被引量:1
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作者 袁艳 丁晓铭 +1 位作者 苏丽娟 王婉悦 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第4期144-155,共12页
The snapshot image mapping spectrometer(IMS) has advantages such as high temporal resolution,high throughput,compact structure and simple reconstructed algorithm.In recent years,it has been utilized in biomedicine,r... The snapshot image mapping spectrometer(IMS) has advantages such as high temporal resolution,high throughput,compact structure and simple reconstructed algorithm.In recent years,it has been utilized in biomedicine,remote sensing,etc.However,the system errors and various factors can cause cross talk,image degradation and spectral distortion in the system.In this research,a theoretical model is presented along with the point response function(PRF) for the IMS,and the influence of the mirror tilt angle error of the image mapper and the prism apex angle error are analyzed based on the model.The results indicate that the tilt angle error causes loss of light throughput and the prism apex angle error causes spectral mixing between adjacent sub-images.The light intensity on the image plane is reduced to 95%when the mirror tilt angle error is increased to ±100 "(≈ 0.028°).The prism apex error should be controlled within the range of 0-36"(0.01°)to ensure the designed number of spectral bands,and avoid spectral mixing between adjacent images. 展开更多
关键词 imaging spectrometers snapshot imaging spectrometer imaging model image mapper
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Absolute partial and total ionization cross sections of carbon monoxide with electron collision from 350 eV to 8000 eV
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作者 Taj Wali Khan 黄伟哲 +2 位作者 王恩亮 单旭 陈向军 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期459-464,共6页
The absolute partial and total cross sections for electron impact ionization of carbon monoxide are reported for electron energies from 350 eV to 8000 eV.The product ions(CO^(+),C^(+),O^(+),CO^(2+),C^(2+),and O^(2+))a... The absolute partial and total cross sections for electron impact ionization of carbon monoxide are reported for electron energies from 350 eV to 8000 eV.The product ions(CO^(+),C^(+),O^(+),CO^(2+),C^(2+),and O^(2+))are measured by employing an ion imaging mass spectrometer and two ion-pair dissociation channels(C^(+)+O^(+)and C^(2+)+O^(+))are identified.The absolute cross sections for producing individual ions and their total,as well as for the ion-pair dissociation channels are obtained by normalizing the data of CO^(+)to that of Ar^(+)from CO-Ar mixture target with a fixed 1:1 ratio.The overall errors are evaluated by considering various kinds of uncertainties.A comprehensive comparison is made with the available data,which shows a good agreement with each other over the energy ranges that are overlapped.This work presents new cross-section data with electron energies above 1000 eV. 展开更多
关键词 electron impact ionization cross sections carbon monoxide ion imaging mass spectrometer
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Symmetrical Processing of Interferogram and Spectrum Reconstruction in Interference Spectrometer
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作者 楚建军 赵达尊 《Journal of Beijing Institute of Technology》 EI CAS 2003年第1期1-5,共5页
Because of its all-reflective layout based on the Fresnel double-mirror interference system, the newly developed Fourier transform imaging spectrometer has a very large spectral bandwidth ranged from a cut-off wavelen... Because of its all-reflective layout based on the Fresnel double-mirror interference system, the newly developed Fourier transform imaging spectrometer has a very large spectral bandwidth ranged from a cut-off wavelength (related to the cut-off wave number σ max ) to far infrared. According to the signal's symmetry and wide-band characteristics, a simple method that can efficiently weaken the low frequency noise in the reconstructed spectrum is presented. Also, according to the symmetry, the eigenvector method is applied to the reconstruction of the spectrum. 展开更多
关键词 Fourier transform interferential imaging spectrometer spectrum reconstruction power spectrum estimation
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New Imaging Spectrometric Method for Rotary Object
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作者 方俊永 赵达尊 +1 位作者 蒋月娟 楚建军 《Journal of Beijing Institute of Technology》 EI CAS 2003年第1期6-10,共5页
A new technique for imaging spectrometer for rotary object based on computed-tomography is proposed. A discrete model of this imaging spectrometric system is established, which is accordant to actual measurements and ... A new technique for imaging spectrometer for rotary object based on computed-tomography is proposed. A discrete model of this imaging spectrometric system is established, which is accordant to actual measurements and convenient for computation. In computer simulations with this method, projections of the object are detected by CCD while the object is rotating, and the original spectral images are numerically reconstructed from them by using the algorithm of computed-tomography. Simulation results indicate that the principle of the method is correct and it performs well for both broadband and narrow-band spectral objects. 展开更多
关键词 imaging spectrometer rotary object COMPUTED-TOMOGRAPHY
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A cross-type imaging electron spectrometer 被引量:1
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作者 YE YuGuang ZOU Hong +6 位作者 WANG YongFu QIN JunFeng SHI WeiHong ZOU JiQing ZHONG WeiYing ZONG QiuGang FU SuiYan 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2023年第3期641-653,共13页
Energetic electron measurement is of great significance to theoretical space physics research and space weather applications.Current energetic electron detectors must cooperate with a spin-stabilized satellite platfor... Energetic electron measurement is of great significance to theoretical space physics research and space weather applications.Current energetic electron detectors must cooperate with a spin-stabilized satellite platform to achieve high angular resolution in pitch angle distribution and three-dimensional(3D)imaging measurement of energetic electrons.This article introduces a cross-type quasi-3D imaging electron spectrometer(IES)based on pinhole imaging technology developed in the laboratory.The imager is composed of five imaging units,including a nine-pixel area array Si-PIN detector imaging unit in the middle and four three-pixel linear array Si-PIN detector imaging units placed in a cross-shape around it.The combination of five imaging units forms two orthogonal nine-pixel linear array detectors(with a common pixel in the middle).There are four pixels with a view angle of 20°×20°in the 45°oblique directions of the cross-type detection array.There are 21 imaging pixels in the entire crosstype sensor head,corresponding to 21 directions.Two multichannel integrated preamplifier ASICs are integrated in the sensor head to realize particle signal readout from 21 pixels.With a back-end electronics system,each pixel can achieve high energy resolution detection of 50–600 keV electrons.Radioactive sources and electron accelerators are used to calibrate the cross-type imaging sensor head,and the results demonstrate its good energy and directional detection characteristics(the energy resolution reaches 6.9 keV for the incident 200 keV electron beam).We performed simulations on the imaging sensor head’s ability to measure the electron pitch angle distribution on the three-axis stabilized platform,and the results show that the sensor head can perform quasi-three-dimensional detection of electrons incident within 2πsolid angles on the three-axis stabilized satellite platform,with an average angular resolution of the electron pitch angle distribution of less than 6°. 展开更多
关键词 energetic electron detection imaging electron spectrometer cross-type sensor head pitch angle distribution
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Snow Cover Variation and Streamflow Simulation in a Snow-fed River Basin of the Northwest Himalaya 被引量:5
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作者 Vaibhav SHARMA V.D.MISHRA P.K.JOSHI 《Journal of Mountain Science》 SCIE CSCD 2012年第6期853-868,共16页
Snowmelt is an important component of any snow-fed river system.The Jhelum River is one such transnational mountain river flowing through India and Pakistan.The basin is minimally glacierized and its discharge is larg... Snowmelt is an important component of any snow-fed river system.The Jhelum River is one such transnational mountain river flowing through India and Pakistan.The basin is minimally glacierized and its discharge is largely governed by seasonal snow cover and snowmelt.Therefore,accurate estimation of seasonal snow cover dynamics and snowmeltinduced runoff is important for sustainable water resource management in the region.The present study looks into spatio-temporal variations of snow cover for past decade and stream flow simulation in the Jhelum River basin.Snow cover extent(SCE) was estimated using MODIS(Moderate Resolution Imaging Spectrometer) sensor imageries.Normalized Difference Snow Index(NDSI) algorithm was used to generate multi-temporal time series snow cover maps.The results indicate large variation in snow cover distribution pattern and decreasing trend in different sub-basins of the Jhelum River.The relationship between SCE-temperature,SCE-discharge and discharge-precipitation was analyzed for different seasons and shows strong correlation.For streamflow simulation of the entire Jhelum basin Snow melt Runoff Model(SRM) used.A good correlation was observed between simulated stream flow and in-situ discharge.The monthly discharge contribution from different sub-basins to the total discharge of the Jhelum River was estimated using a modified version of runoff model based on temperature-index approach developed for small watersheds.Stream power - an indicator of the erosive capability of streams was also calculated for different sub-basins. 展开更多
关键词 Snow cover extent(SCE) Streamflow Snow Melt Runoff Model(SRM) Normalized Difference Snow Index(NDSI) Jhelum basin Moderate Resolution imaging spectrometer(MODIS)
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The Seasonal Variations of Aerosols over East Asia as Jointly Inferred from MODIS and OMI 被引量:5
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作者 LIU Qi DING Wei-Dong FU Yun-Fei 《Atmospheric and Oceanic Science Letters》 2011年第6期330-337,共8页
Data on aerosol optical thickness(AOT) and single scattering albedo(SSA) derived from Moderate Resolution Imaging Spectrometer(MODIS) and Ozone Monitoring Instrument(OMI) measurements,respectively,are used jointly to ... Data on aerosol optical thickness(AOT) and single scattering albedo(SSA) derived from Moderate Resolution Imaging Spectrometer(MODIS) and Ozone Monitoring Instrument(OMI) measurements,respectively,are used jointly to examine the seasonal variations of aerosols over East Asia.The seasonal signals of the total AOT are well defined and nearly similar over the land and over the ocean.These findings indicate a natural cycle of aerosols that originate primarily from natural emissions. In contrast,the small-sized aerosols represented by the fine-mode AOT,which are primarily generated over the land by human activities,do not have evident seasonalscale fluctuations.A persistent maximum of aerosol loadings centered over the Sichuan basin is associated with considerable amounts of fine-mode aerosols throughout the year.Most regions exhibit a general spring maximum. During the summer,however,the aerosol loadings are the most marked over north central China.This occurrence may result from anthropogenic fine particles,such as sulfate and nitrate.Four typical regions were selected to perform a covariation analysis of the monthly gridded AOT and SSA.Over southwestern and southeastern China,if the aerosol loadings are small to moderate they are composed primarily of the highly absorptive aerosols. However,more substantial aerosol loadings probably represent less-absorptive aerosols.The opposite covariation pattern occurring over the coastal-adjacent oceans suggests that the polluted oceanic atmosphere is closely correlated with the windward terrestrial aerosols.North central China is strongly affected by dust aerosols that show moderate absorption.This finding may explain the lower variability in the SSA that accompanies increasing aerosol loadings in this region. 展开更多
关键词 aerosol optical thickness single scattering albedo seasonal variation Moderate Resolution imaging spectrometer Ozone Monitoring Instrument
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Validation of Global Evapotranspiration Product(MOD16) Using Flux Tower Data from Panjin Coastal Wetland,Northeast China 被引量:7
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作者 DU Jia SONG Kaishan 《Chinese Geographical Science》 SCIE CSCD 2018年第3期420-429,共10页
Recent advances in remote sensing technology and methods have resulted in the development of an evapotranspiration(ET) product from the Moderate Resolution Imaging Spectrometer(MOD16). The accuracy of this product how... Recent advances in remote sensing technology and methods have resulted in the development of an evapotranspiration(ET) product from the Moderate Resolution Imaging Spectrometer(MOD16). The accuracy of this product however has not been tested for coastal wetland ecosystems. The objective of this study therefore is to validate the MOD16 ET product using data from one eddy covariance flux tower situated in the Panjin coastal wetland ecosystem within the Liaohe River Delta, Northeast China. Cumulative ET data over an eight-day period in 2005 from the flux tower was calculated to coincide with the MOD16 products across the same period. Results showed that data from the flux tower were inconsistent with that gained form the MOD16 ET. In general, results from Panjin showed that there was an underestimation of MOD16 ET in the spring and fall, with Biases of -2.27 and -3.53 mm/8 d, respectively(–40.58% and -49.13% of the observed mean). Results for Bias during the summer had a range of 1.77 mm/8 d(7.82% of the observed mean), indicating an overestimation of MOD16 ET. According to the RMSE, summer(6.14 mm/8 d) achieved the lowest value, indicating low accuracy of the MOD16 ET product. However, RMSE(2.09 mm/8 d) in spring was the same as that in the fall. Relationship between ET and its relevant meteorological parameters were analyzed. Results indicated a very good relationship between surface air temperature and ET. Meanwhile a significant relationship between wind speed and ET also existed. The inconsistent comparison of MOD16 and flux tower-based ET are mainly attributed to the parameterization of the Penman-Monteith model, flux tower measurement errors, and flux tower footprint vs. MODIS pixels. 展开更多
关键词 Moderate Resolution imaging spectrometer(MODIS) MOD16 evapotranspiration validation coastal wetland eddy covariance flux tower
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Vegetation Phenology in Permafrost Regions of Northeastern China Based on MODIS and Solar-induced Chlorophyll Fluorescence 被引量:1
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作者 WEN Lixiang GUO Meng +3 位作者 YIN Shuai HUANG Shubo LI Xingli YU Fangbing 《Chinese Geographical Science》 SCIE CSCD 2021年第3期459-473,共15页
Vegetation phenology is an indicator of vegetation response to natural environmental changes and is of great significance for the study of global climate change and its impact on terrestrial ecosystems.The normalized ... Vegetation phenology is an indicator of vegetation response to natural environmental changes and is of great significance for the study of global climate change and its impact on terrestrial ecosystems.The normalized difference vegetation index(NDVI)and enhanced vegetation index(EVI),extracted from the Moderate Resolution Imaging Spectrometer(MODIS),are widely used to monitor phenology by calculating land surface reflectance.However,the applicability of the vegetation index based on‘greenness'to monitor photosynthetic activity is hindered by poor observation conditions(e.g.,ground shadows,snow,and clouds).Recently,satellite measurements of solar-induced chlorophyll fluorescence(SIF)from OCO-2 sensors have shown great potential for studying vegetation phenology.Here,we tested the feasibility of SIF in extracting phenological metrics in permafrost regions of the northeastern China,exploring the characteristics of SIF in the study of vegetation phenology and the differences between NDVI and EVI.The results show that NDVI has obvious SOS advance and EOS lag,and EVI is closer to SIF.The growing season length based on SIF is often the shortest,while it can represent the true phenology of vegetation because it is closely related to photosynthesis.SIF is more sensitive than the traditional remote sensing indices in monitoring seasonal changes in vegetation phenology and can compensate for the shortcomings of traditional vegetation indices.We also used the time series data of MODIS NDVI and EVI to extract phenological metrics in different permafrost regions.The results show that the length of growing season of vegetation in predominantly continuous permafrost(zone I)is longer than in permafrost with isolated taliks(zone II).Our results have certain significance for understanding the response of ecosystems in cold regions to global climate change. 展开更多
关键词 vegetation phenology PERMAFROST Moderate Resolution imaging spectrometer(MODIS) solar-induced chlorophyll fluorescence(SIF) northeastern China
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Effects of optical axis direction on optical path difference and lateral displacement of Savart polariscope 被引量:1
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作者 张淳民 任文艺 穆廷魁 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第2期243-252,共10页
A simple method is applied to calculating the optical path difference (OPD) of a plane parallel uniaxial plate with an arbitrary optical axis direction. Then, the theoretical expressions of the OPD and lateral displ... A simple method is applied to calculating the optical path difference (OPD) of a plane parallel uniaxial plate with an arbitrary optical axis direction. Then, the theoretical expressions of the OPD and lateral displacement (LD) of Savart polariscope under non-ideal conditions are obtained exactly. The variations of OPD and LD are simulated, and some important conclusions are obtained when the optical axis directions have an identical tolerance of /pm 1^{{/circ}}. An application example is given that the tolerances of optical axis directions are gained according to the spectral resolution tolerances of the stationary polarization interference imaging spectrometer (SPIIS). Several approximate formulae are obtained for explaining some conclusions above. The work provides a theoretical guidance for the optic design, crystal processing, installation and debugging, data analysis and spectral reconstruction of the SPIIS. 展开更多
关键词 stationary polarization interference imaging spectrometer Savart polariscope optical axis optical path difference
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Temperature Influence on Divergence Angles of Quartz Crystal Wollaston Prism
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作者 赵爽 吴福全 +4 位作者 张东升 赵昕 王进喜 薛美 仲纬纲 《Chinese Physics Letters》 SCIE CAS CSCD 2008年第7期2470-2472,共3页
We propose a structural angle and main refractive indices as two key factors to understand the temperature influence on the divergence angles of the Wollaston prism. The temperature influence on the divergence angles ... We propose a structural angle and main refractive indices as two key factors to understand the temperature influence on the divergence angles of the Wollaston prism. The temperature influence on the divergence angles of quartz crystal Wollaston prism is studied theoretically. The results show that divergence angles decrease with increasing temperature, while the divergence angle of e-light decrease more quickly than that of o-light. The testing system is established to verify the above results, and the experimental results are in agreement well with the theoretical analysis. 展开更多
关键词 POLARIZATION imaging spectrometer
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Anti-proton contamination design of the imaging energetic electron spectrometer based on Geant4 simulation 被引量:7
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作者 LUO Lin ZOU Hong +4 位作者 ZONG QiuGang WANG LingHua CHEN HongFei SHI WeiHong YU XiangQian 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2015年第8期1385-1391,共7页
The measurement of energetic particles plays an important role in the space environment monitoring and space weather forecasting.The accuracy of the energetic electron measurement is seriously influenced by the proton... The measurement of energetic particles plays an important role in the space environment monitoring and space weather forecasting.The accuracy of the energetic electron measurement is seriously influenced by the proton contamination.An anti-proton contamination design for the sensor of imaging energetic electron spectrometer is introduced in this paper.According to the electron and proton spectrum on the typical satellite orbits calculated by the radiation belt models,the efficiency of the anti-proton contamination design is estimated by the Geant4 simulation and the design is optimized based on the simulation results. 展开更多
关键词 energetic particle measurement imaging energetic electron spectrometer anti-proton design Geant4 simulation
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Observation of Central Toroidal Rotation Induced by ICRF on EAST
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作者 潘夏云 王福地 +8 位作者 张新军 吕波 陈俊 李颖颖 符佳 石跃江 余羿 叶民友 万宝年 《Plasma Science and Technology》 SCIE EI CAS CSCD 2016年第2期114-119,共6页
Core plasma rotation of both L-mode and H-mode discharges with ion cyclotron range of frequency(ICRF) minority heating(MH) scheme was measured with a tangential X-ray imaging crystal spectrometer on EAST(Experime... Core plasma rotation of both L-mode and H-mode discharges with ion cyclotron range of frequency(ICRF) minority heating(MH) scheme was measured with a tangential X-ray imaging crystal spectrometer on EAST(Experimental Advanced Superconducting Tokamak).Cocurrent central impurity toroidal rotation change was observed in ICRF-heated L-and H-mode plasmas.Rotation increment as high as 30 km/s was generated at ~1.7 MW ICRF power.Scaling results showed similar trend as the Rice scaling but with significant scattering,especially in L-mode plasmas.We varied the plasma current,toroidal field and magnetic configuration individually to study their effect on L-mode plasma rotation,while keeping the other major plasma parameters and heating unchanged during the scanning.It was found that larger plasma current could induce plasma rotation more efficiently.A scan of the toroidal magnetic field indicated that the largest rotation was obtained for on-axis ICRF heating.A comparison between lower-single-null(LSN)and double-null(DN) configurations showed that LSN discharges rendered a larger rotation change for the same power input and plasma parameters. 展开更多
关键词 central toroidal rotation ICRF flow drive minority heating X-ray imaging crystal spectrometer
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Freeform spectrometer enabling increased compactness 被引量:8
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作者 Jacob Reimers Aaron Bauer +1 位作者 Kevin P Thompson Jannick P Rolland 《Light(Science & Applications)》 SCIE EI CAS CSCD 2017年第1期646-655,共10页
We present optical designs with freeform optics in the context of hyperspectral imaging.Results show designs that are 5×more compact in volume than similar designs using conventional spherical or aspherical surfa... We present optical designs with freeform optics in the context of hyperspectral imaging.Results show designs that are 5×more compact in volume than similar designs using conventional spherical or aspherical surfaces.We will show how combining the concepts of spatial and spectral-band broadening,which will be introduced in this paper,led to the improvement in compactness that is uniquely enabled by freeform optics. 展开更多
关键词 ABERRATIONS freeform optics imaging spectrometer
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Wavelet-based threshold denoising for imaging hyperspectral data 被引量:1
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作者 Yang Hao Zhang Dongyan +1 位作者 Huang Linsheng Zhao Jinling 《International Journal of Agricultural and Biological Engineering》 SCIE EI CAS 2014年第3期36-42,共7页
Imaging spectroradiometer is highly susceptible to noise.Accurately quantitative processing with higher quality is obligatory before any derivative analysis,especially for precision agricultural application.Using the ... Imaging spectroradiometer is highly susceptible to noise.Accurately quantitative processing with higher quality is obligatory before any derivative analysis,especially for precision agricultural application.Using the self-developed Pushbroom Imaging Spectrometer(PIS),a wavelet-based threshold(WT)denoising method was proposed for the PIS imaging hyperspectral data.The WT with PIS was evaluated by comparing with other popular denoising methods in pixel scale and in regional scale.Furthermore,WT was validated by chlorophyll concentration retrieval based on red-edge position extraction.The result indicated that the determination coefficient R2 of the chlorophyll concentration inversion model of winter wheat leaves was improved from 0.586 to 0.811.It showed that the developed denoising method allowed effective denoising while maintaining image quality,and presented significant advantages over conventional methods. 展开更多
关键词 WAVELET DENOISING spectral domain Pushbroom imaging spectrometer red edge position
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