he electrochemistry of cytochrome C was investigated at a spectrographicgraphite electrode. In phosphate buffer solution (pH= 7. 0) , cytochrome C showedstable and quasi-reversible response. The formal potential E￣(o...he electrochemistry of cytochrome C was investigated at a spectrographicgraphite electrode. In phosphate buffer solution (pH= 7. 0) , cytochrome C showedstable and quasi-reversible response. The formal potential E￣(o') was 0. 015 V (at25℃ , vs. SCE) and the heterogeneous electron transfer rate constant k_s obtainedvaried form 1. 10×10￣(-3) cm · s￣(-1) to 1. 80k×10￣(-3) cm · s￣(-1). The thermodynamic pa-rameters of the electron transfer reaction of cvtochrome C was also estimated. Fur-thermore, the effect of the various electrode surface states on the electrochemistryof cytochrome C was discussed.展开更多
During high power laser welding, the amount of energy reaching the workpiece, the weld penetration and the geometry of the welds are strongly affected by the laser induced plasma. Light emissions during welding were r...During high power laser welding, the amount of energy reaching the workpiece, the weld penetration and the geometry of the welds are strongly affected by the laser induced plasma. Light emissions during welding were recorded by a spectrometer. Based on the collected spectroscopic data, the electron density and the temperature of plasma were calculated using the relative intensity method. Several relationships between weld penetrations and electron density are given.展开更多
/h/ is described differently by different researchers. While some argue that /h/ is a glottal fricative, others argue that it is the voiceless counterpart of the following vowel, yet others argue that /h/ is a glide o.../h/ is described differently by different researchers. While some argue that /h/ is a glottal fricative, others argue that it is the voiceless counterpart of the following vowel, yet others argue that /h/ is a glide or an approximant. However, de- tailed acoustic studies focusing on /h/ are very limited. This study aims to describe the spectrographic characteristics of /h/ in Turkish. Test words consisted of 48 monosyllabic and disyllabic words containing /h/ which was followed by eight Turkish vowels. Totally 1440 tokens were analyzed. After segmentation, /h/ was classified based on its spectrographic characteristics: 1) segment exhibiting formants, 2) segment exhibiting frication (but no formants) with energy in lower frequencies and 3) segment exhibiting almost no energy. In order to find out if there is a significant difference among these three categories, Chi-square test was applied. The spectrographic characteristics of /h/ in Turkish suggest that it is more like the voiceless version of the surrounding vowels, significantly when it is in syllable initial position and the preceding vowel when in syllable final position.展开更多
With the spectrographic analysis, this paper analyzes the concentration of elements inoil, such as Fe, Cu, Cr, Al, Si etc. In order to monitor conditions and diagnose faults, the correlationcoefficient of main element...With the spectrographic analysis, this paper analyzes the concentration of elements inoil, such as Fe, Cu, Cr, Al, Si etc. In order to monitor conditions and diagnose faults, the correlationcoefficient of main elements in oil has been used to study wear characteristics of friction pairs inrunning-in and working periods.展开更多
Higher heating value(HHV)is the key parameter for replacing Refuse-Derived Fuel(RDF)with fossil fuels in the cement industry.HHV can be measured with a bomb calorimeter or predicted from direct elemental data by using...Higher heating value(HHV)is the key parameter for replacing Refuse-Derived Fuel(RDF)with fossil fuels in the cement industry.HHV can be measured with a bomb calorimeter or predicted from direct elemental data by using regression models.Both methods require the continuous use of special laboratory equipment and are time consuming.To overcome these limitations,this study aims to predict the HHV value of RDF from predicted elemental data by using regression models.Therefore,once the predicted elemental data are generated,there will be no need to have continuous elemental data to predict HHV.Predicted elemental data were generated from direct elemental data and Near Infrared(NIR)camera-based spectrometric data by using a deep learning model.A convolutional neural networks(CNN)model was used for deep learning and was trained with 10,500 NIR image samples,each of which was 28×28×1.Different regression models(Linear,Tree,Support-Vector Machine,Ensemble and Gaussian process)were applied for HHV prediction.According to these results,higher R2 values(>0.85)were obtained with Gaussian process models(except for the Rational Quadratic model)for the predicted elemental data.Among the Gaussian models,the highest R2(0.95)but the lowest Root Mean Square Error(RMSE)(0.0563),Mean Squared Error(MSE)(0.0317)and Mean Absolute Error(MAE)(0.0431)were obtained with the Mattern 5/2 model.The results of predictions from predicted elemental data were compared to predictions from direct elemental data.The results show that the regression from predicted elemental data has an adequate prediction(R2=0.95)compared to the prediction from the direct elemental data(R^(2)=0.99).展开更多
The Chang’e-4 mission obtained spectral data of multiple rock targets on the lunar surface.The Modified Gaussian Model(MGM)is usually applied to the spectral interpretation of powder samples,its applicability and acc...The Chang’e-4 mission obtained spectral data of multiple rock targets on the lunar surface.The Modified Gaussian Model(MGM)is usually applied to the spectral interpretation of powder samples,its applicability and accuracy on the rock targets remain to be further evaluated.The rock slice of lunar meteorite NWA 4734 is used to conduct comprehensive analysis of the petrography,mineralogy and laboratory spectroscopy,which will provide important ground truth for the MGM interpretation of lunar in situ spectra of rock samples.First,a scanning electron microscope(SEM),Energy Dispersive Spectrometer(EDS),and Electron Probe Micro-Analyzer(EPMA)analysis results indicate that:(1)almost all plagioclase in NWA 4734 have been converted to maskelynites,which indicate that the meteorite has undergone severe impact metamorphism;(2)the chemical composition of pyroxene and olivine is significantly heterogeneous,showing a distribution characteristic of magnesium-rich core and iron-rich rim,further indicating that NWA 4734 has undergone multiple crystallization and differentiation.Second,this article focuses on the rock slice of NWA 4734ʼs greyscale image of the Back Scattering Electron(BSE),and obtains the proportion of High-Calcium Pyroxene(HCP)in the total pyroxenes of this sample by calculating the area percentage using the pixel counting method.The result shows that the proportion of HCP is 72%±5.4%,which can be used as a ground truth to evaluate the interpretation applicability and accuracy of MGM.A field spectrometer(ASD)is used to measure the visible and near-infrared reflectance spectra(450-2500 nm)of the rock slice from NWA 4734 in the same area as the BSE image obtained by SEM,and MGM is used to deconvolve the ASD spectra,and the average proportion of HCP is estimated to be 71%±10.1%.The results between the MGM and the pixel counting are comparable within the error range,which demonstrates the applicability of MGM on interpretation of the rock samples on the lunar surface.展开更多
The infrared band contains rich opportunities for astronomical research,but due to the limitations of infrared technology,the development of infrared astronomy in China has been far from satisfactory for a long time,e...The infrared band contains rich opportunities for astronomical research,but due to the limitations of infrared technology,the development of infrared astronomy in China has been far from satisfactory for a long time,especially for solar observation.“Accurate Infrared Magnetic field Measurements of the Sun”project(AIMS)is a National Major Scientific Research Instrument Development Project(recommended by the Ministries)supported by the National Natural Science Foundation of China.It is aimed at improving the accuracy of magnetic field measurement by an order of magnitude,by measuring the“Zeeman splitting”directly.In addition,as AIMS is also the first equipment specifically designed for mid-to far-infrared solar observation in the world,we also hope to utilize AIMS to explore potential new scientific research opportunities in the vast infrared region.This article will briefly introduce the scientific objectives,the telescope,the scientific post-focus instruments,and finally summarize the commissioning observations of AIMS.展开更多
BFOSC and YFOSC are the most frequently used instruments in the Xinglong 2.16 m telescope and Lijiang 2.4 m telescope,respectively.We developed a software package named“BYSpec”(BFOSC and YFOSC Spectra Reduction Pack...BFOSC and YFOSC are the most frequently used instruments in the Xinglong 2.16 m telescope and Lijiang 2.4 m telescope,respectively.We developed a software package named“BYSpec”(BFOSC and YFOSC Spectra Reduction Package)dedicated to automatically reducing the long-slit and echelle spectra obtained by these two instruments.The package supports bias and flat-fielding correction,order location,background subtraction,automatic wavelength calibration,and absolute flux calibration.The optimal extraction method maximizes the signal-to-noise ratio and removes most of the cosmic rays imprinted in the spectra.A comparison with the 1D spectra reduced with IRAF verifies the reliability of the results.This open-source software is publicly available to the community.展开更多
AIM: To investigate the protective mechanism of Gingko Biloba extract(EGb761) on the ability of retinal pigment epithelial(RPE) cells to resist light-induced damage in a comparative proteomics study. · METHODS: H...AIM: To investigate the protective mechanism of Gingko Biloba extract(EGb761) on the ability of retinal pigment epithelial(RPE) cells to resist light-induced damage in a comparative proteomics study. · METHODS: Human RPE cells(ARPE-19) were randomly distributed to one of three groups: normal control(NC group) and light-damaged model without or with EGb761 group(M and ME groups,respectively). The light-damaged model was formed by exposing to white light(2 200 ±300)lx for 6h. The RPE cells in ME group were conducted with EGb761(100μg/mL) before light exposure. The soluble cellular proteins extracting from each groups were separated by two-dimensional electrophoresis and stained by silver staining. Different proteins in the profiles of the gels were analyzed by Image Master Software. Two-fold expressing protein spots were identified by Matrix-assisted laser desorption/ ionization tandem time-of-flight(MALDI-TOF/TOF) mass spectrometry. ·RESULTS: NC,M and ME groups displayed 1 892±71,2 145 ±23 and 2 216 ±85 protein spots,respectively. We identified 33 proteins with different expression levels between the NC and M groups,25 proteins between the M and ME groups,and 11 proteins between the NC and ME groups. MALDI-TOF/TOF mass spectrometry successfully identified 16 proteins,including metabolic enzymes,cytoskeletal proteins,anti-oxidation proteins,and others. ·CONCLUSION: Differences in some important proteins,such as cathepsin B,heat shock protein,and cytochrome C reductase,indicated that multiple pathways may be induced in light-damaged RPE cells and the protective effect of EGb761.展开更多
Variogram has been utilized to exploring the spatial heterogeneity of remote sensing images,especially its association with spatial resolution.However,very few attentions have been drawn on evaluating the spatial hete...Variogram has been utilized to exploring the spatial heterogeneity of remote sensing images,especially its association with spatial resolution.However,very few attentions have been drawn on evaluating the spatial heterogeneity of multisensor airborne imagery and its relationship with spectral wavelength.Therefore,an investigation was carried out on multisensor airborne images to determine the relation between spatial heterogeneity and spectral wavelength for woodland,grass,and urban landscapes by applying variogram modeling.The airborne thematic mapper(ATM),compact airborne spectrographic imager(CASI),and Specim AISA Eagle airborne images at Harwood Forest,Monks wood,Cambridge,and River Frome areas,UK,were utilized.Results revealed that(1)the red band contained greater spatial variability than near-infrared wavelengths and other visible wavebands;(2)there was a steep gradient at the red edge in reference to its spatial variability of multisensor airborne images;(3)only for natural landscape such as woodland and grass,near-infrared waveband contains greater within-scene variations than the blue and green bands;(4)compared with the discrepancy of spatial resolution introduced by multisensor images(ATM,CASI,and Eagle),the specific landscape and spectral bands were more important in determining heterogeneity by means of original visible,near-infrared bands,and normalized difference vegetation index(NDVI).These findings remained us to be caution when combining and interpreting spatial variability and spatial structures derived from airborne images with different spatial resolution and spectral wavelength.Additionally,the outcomes of this study also have considerable implications in terms of designing and choosing suitable images for different applications.展开更多
The Lijiang 2.4-meter Telescope(LJT), the largest common-purpose optical telescope in China,has been available to the worldwide astronomical community since 2008. It is located at the Gaomeigu site,Lijiang Observatory...The Lijiang 2.4-meter Telescope(LJT), the largest common-purpose optical telescope in China,has been available to the worldwide astronomical community since 2008. It is located at the Gaomeigu site,Lijiang Observatory(LJO), in the southwest of China. The site has very good observational conditions.During its 10-year operation, several instruments have been equipped on the LJT. Astronomers can perform both photometric and spectral observations. The main scientific goals of LJT include recording photometric and spectral evolution of supernovae, reverberation mapping of active galactic nuclei, investigating the physical properties of binary stars and near-earth objects(comets and asteroids), and identification of exoplanets and all kinds of transients. Until now, the masses of 41 high accretion rate black holes have been measured, and more than 168 supernovae have been identified by the LJT. More than 190 papers related to the LJT have been published. In this paper, the general observation conditions of the Gaomeigu site is introduced at first. Then, the structure of the LJT is described in detail, including the optical, mechanical, motion and control system. The specification of all the instruments and some detailed parameters of the YFOSC is also presented. Finally, some important scientific results and future expectations are summarized.展开更多
As a facility used for astronomical research, the Lijiang 2.4-m telescope of Yunnan Astronomical Observatories, requires the ability to change one auxiliary instrument with another in as short a time as possible. This...As a facility used for astronomical research, the Lijiang 2.4-m telescope of Yunnan Astronomical Observatories, requires the ability to change one auxiliary instrument with another in as short a time as possible. This arises from the need to quickly respond to scientific programs （e.g. transient observation, time domain studies） and changes in observation conditions （e.g. seeing and weather conditions）. In this paper, we describe the design, construction and test of hardware and software in the rapid instrument exchange system （RIES） for the Cassegrain focal station of this telescope, which enables instruments to be quickly changed at night without much loss of observing time. Tests in the laboratory and at the telescope show that the image quality and pointing accuracy of RIES are satisfactory. With RIES, we observed the same Landolt standard stars almost at the same time with the Princeton Instruments VersArray 1300B Camera （PICCD） and the Yunnan Faint Object Spectrograph and Camera （YFOSC）, while both were mounted at the Cassegrain focus. A quasi-simultaneous comparison shows that the image quality of the optical system inside the YFOSC is comparable with that provided by the PICCD.展开更多
We applied a Monte Carlo method -- simulated annealing algorithm -- to carry out the design of multilayer achromatic waveplate. We present solutions for three-, six- and ten-layer achromatic waveplates. The optimized ...We applied a Monte Carlo method -- simulated annealing algorithm -- to carry out the design of multilayer achromatic waveplate. We present solutions for three-, six- and ten-layer achromatic waveplates. The optimized retardance settings are found to be 89°51′39″ ± 0°33′37″ and 89°54′46″ ± 0°22′4″ for the six- and ten-layer waveplates, respectively, for a wavelength range from 1000 nm to 1800 nm. The polarimetric properties of multilayer waveplates are investigated based on several numerical experiments. In contrast to previously proposed three-layer achromatic waveplate, the fast axes of the new six- and ten-layer achromatic waveplate remain at fixed angles, independent of the wavelength. Two applications of multilayer achromatic waveplate are discussed, the general-purpose phase shifter and the birefringent filter in the Infrared Imaging Magnetograph （IRIM） system of the Big Bear Solar Observatory （BBSO）. We also checked an experimental method to measure the retardance of waveplates.展开更多
The Large sky Area Multi-Object fiber Spectroscopic Telescope(LAMOST)is a Chinese national scientific research facility operated by National Astronomical Observatories,Chinese Academy of Sciences(NAOC).The LAMOST surv...The Large sky Area Multi-Object fiber Spectroscopic Telescope(LAMOST)is a Chinese national scientific research facility operated by National Astronomical Observatories,Chinese Academy of Sciences(NAOC).The LAMOST survey for the Milky Way Galaxy and extra-galactic objects has been carried out for several years.The accuracies in measuring radial velocity are expected to be 5 km s-1 for the low resolution spectroscopic survey(R=1800),and 1 km s-1 for the medium resolution mode.The stability of spectrograph is the main factor affecting the accuracies in measuring radial velocity,so an Active Flexure Compensation Method(AFCM)based on Back Propagation Neural Network(BPNN)is proposed in this paper.It utilizes a deep BP(4-layer,5-layer etc.)model of thermal-induced flexure to periodically predict and apply flexure corrections by commanding the corresponding tilt and tip motions to the camera.The spectrograph camera system is adjusted so that the positions of these spots match those in a reference image.The simulated calibration of this compensation method analytically illustrates its performance on LAMOST spectrograph.展开更多
The absorption band center of visible and near infrared reflectance spectra is a key spectral parameter for lunar mineralogical studies, especially for the mafic minerals（olivine and pyroxene） of mare basalts, which...The absorption band center of visible and near infrared reflectance spectra is a key spectral parameter for lunar mineralogical studies, especially for the mafic minerals（olivine and pyroxene） of mare basalts, which have two obvious absorption bands at 1000 nm（Band I） and 2000 nm（Band II）. Removal of the continuum from spectra, which was developed by Clark and Roush and used to isolate the particular absorption feature, is necessary to estimate this parameter. The Moon Mineralogy Mapper（M3） data are widely used for lunar mineral identification. However, M3 data show a residual thermal effect, which interferes with the continuum removal, and systematic differences exist among optical data taken during different optical periods. This study investigated a suitable continuum removal method and compared the difference between two sets of M3 data taken during different optical periods, Optical Period 1B（OP1B）and Optical Period 2A（OP2A）. Two programs for continuum removal are reported in this paper. Generally,a program respectively constructs two straight lines across Band I and Band II to remove the continuum,which is recommended for locating band centers, because it can find the same Band I center with different right endpoints. The optimal right endpoint for continuum removal is mainly dominated by two optical period data at approximately 2480 and 2560 nm for OP1 B and OP2 A data, respectively. The band center values derived from OP1 B data are smaller than those derived from OP2 A data in Band I but larger in Band II, especially for the spectra using longer right endpoints（〉2600 nm）. This may be due to the spectral slopes of OP1 B data being steeper than those of OP2 A data in Band I but gentler in Band II. These results were applied to Mare Humorum and Mare Nubium, and the measurements were found to mainly vary from intermediate- to high-Ca pyroxene.展开更多
It is expected that ongoing and future space-borne planet survey missions including Transiting Exoplanet Survey Satellite(TESS),PLATO and Earth 2.0 will detect thousands of small to medium-sized planets via the transi...It is expected that ongoing and future space-borne planet survey missions including Transiting Exoplanet Survey Satellite(TESS),PLATO and Earth 2.0 will detect thousands of small to medium-sized planets via the transit technique,including over a hundred habitable terrestrial rocky planets.To conduct a detailed study of these terrestrial planets,particularly the cool ones with wide orbits,the exoplanet community has proposed various follow-up missions.The currently proposed European Space Agency mission Ariel is the first step for this purpose,and it is capable of characterization of planets down to warm super-Earths mainly using transmission spectroscopy.The NASA Large Ultraviolet/Optical/Infrared Surveyor mission proposed in the Astro2020 Decadal Survey white paper will endeavor to further identify habitable rocky planets,and is expected to launch around 2045.In the meanwhile,China is funding a concept study of a 6 m class space telescope named Tianlin(a UV/Opt/NIR large aperture space telescope)that aims to start its operation within the next 10–15 yr and last for 5+yr.Tianlin will be primarily aimed at the discovery and characterization of rocky planets in the habitable zones around nearby stars and to search for potential biosignatures mainly using the direct imaging method.Transmission and emission spectroscopy at moderate to high resolution will be carried out as well on a population of exoplanets to strengthen the understanding of the formation and evolution of exoplanets.It will also be utilized to perform in-depth studies of the cosmic web and early galaxies,and constrain the nature of dark matter and dark energy.We describe briefly the primary scientific motivations and main technical considerations based on our preliminary simulation results.We find that a monolithic off-axis space telescope with primary mirror diameter larger than 6 m equipped with a high contrast coronagraph can identify water in the atmosphere of a habitable-zone Earth-like planet around a Sunlike star.More simulations for the detectability of other key biosignatures including O_(3),O_(2),CH_(4)and chlorophyll are coming.展开更多
The Multi-wavelength Spectrometer is a medium-dispersion（R^130 000）grating spectrometer installed on the New Vacuum Solar Telescope at the Fuxian Solar Observatory,Yunnan Astronomical Observatory,Chinese Academy of ...The Multi-wavelength Spectrometer is a medium-dispersion（R^130 000）grating spectrometer installed on the New Vacuum Solar Telescope at the Fuxian Solar Observatory,Yunnan Astronomical Observatory,Chinese Academy of Sciences.It is designed to accurately observe the velocity and magnetic fields of the Sun.The present configuration of this spectrometer allows us to simultaneously observe three different solar spectral lines.This work is dedicated to showing the first observations carried out in both the Hαand Ca II 8542 A lines.We give a detailed description of the data reduction process,focusing on the retrieval of a flat field from the high-resolution spectral data.Two different methods are also performed and compared to eliminate the residual fringe in the reduced data.The real spectral resolution and instrumental profile are analyzed based on the final results,which indicate that this spectrometer presently satisfies the expected performance and it is ready for further scientific observations.展开更多
Sky subtraction is a key technique in data reduction of multi-fiber spectra. Knowledge of characteristics related to the instrument is necessary to determine the method adopted in sky subtraction. In this study, we de...Sky subtraction is a key technique in data reduction of multi-fiber spectra. Knowledge of characteristics related to the instrument is necessary to determine the method adopted in sky subtraction. In this study, we describe the sky subtraction method designed for the Large sky Area Multi-Object fiber Spectroscopic Telescope （LAMOST） survey. The method has been integrated into the LAMOST 2D Pipeline v2.6 and applied to data from LAMOST DR3 and later. For LAMOST, calibration using sky emission lines is used to alleviate the position-dependent （and thus time-dependent） ,-~ 4% fiber throughput uncertainty and small wavelength instability （0.1/~） during observation. Sky subtraction using principal component analysis （PCA） further reduces 25% of the sky line residual from OH fines in the red part of LAMOST spectra after the master sky spectrum, which is derived from a B-spline fit of 20 sky fibers in each spectrograph. Using this approach, values are adjusted by a sky emission line and subtracted from each fiber. Further analysis shows that our wavelength calibration accuracy is about 4.5 km s-1, and the averages of residuals after sky subtraction are about 3% for sky emission lines and 3% for the continuum region. The relative sky subtraction residuals vary with moonlight background brightness, and can reach as low as 1.5% for regions that have sky emission lines during a dark night. Tests on F stars with both similar sky emission line strength and similar object continuum intensity show that the sky emission line residual of LAMOST is smaller than that of the SDSS survey.展开更多
Solar radio spectra and their temporal evolution provide important clues to understand the energy release and electron acceleration process in the corona,and are commonly used to diagnose critical parameters such as t...Solar radio spectra and their temporal evolution provide important clues to understand the energy release and electron acceleration process in the corona,and are commonly used to diagnose critical parameters such as the magnetic field strength.However,previous solar radio telescopes cannot provide high-quality data with complete frequency coverage.Aiming to develop a generalized solar radio observing system,in this study,we designed a digital receiving system that could capture solar radio bursts with a broad bandwidth and a large dynamic range.A dual-channel analog-to-digital converter(ADC)printed circuit board assembly(PCBA)with a sampling rate of 14-bit,1.25 Giga samples per second(GSPS)cooperates with the field-programmable-gate-array(FPGA)chip XC7K410T in the design.This receiver could realize the real-time acquisition and preprocessing of high-speed data of up to 5 GB s^(-1),which ensures high time and spectral resolutions in observations.This receiver has been used in the solar radio spectrometer working in the frequency range of 35 to 40 GHz in Chashan Solar Observatory(CSO)established by Shandong University,and will be further developed and used in the solar radio interferometers.The full-power bandwidth of the PCBA in this receiving system could reach up to 1.5 GHz,and the performance parameters(DC–1.5 GHz)are obtained as follows:spur free dynamic range(SFDR)of 64.7–78.4 dB,signal-to-noise and distortion(SINAD)of 49.1–57.2 dB,and effective number of bits(ENOB)of>7.86 bit.Based on the receiver that we designed,real-time solar microwave dynamic spectra have been acquired and more solar microwave bursts with fine spectral structures are hopeful to be detected in the coming solar maximum.展开更多
The Visible and Near-Infrared Imaging Spectrometer （VNIS）, using two acousto-optic tunable filters as dispersive components, consists of a VIS/NIR imag- ing spectrometer （0.45-0.95 μm）, a shortwave IR spectromet...The Visible and Near-Infrared Imaging Spectrometer （VNIS）, using two acousto-optic tunable filters as dispersive components, consists of a VIS/NIR imag- ing spectrometer （0.45-0.95 μm）, a shortwave IR spectrometer （0.9-2.4 p.m） and a calibration unit with dust-proofing functionality. The VNIS was utilized to detect the spectrum of the lunar surface and achieve in-orbit calibration, which satisfied the re- quirements for scientific detection. Mounted at the front of the Yutu rover, lunar ob- jects that are detected with the VNIS with a 45° visual angle to obtain spectra and ge- ometrical data in order to analyze the mineral composition of the lunar surface. After landing successfully on the Moon, the VNIS performed several explorations and cal- ibrations, and obtained several spectral images and spectral reflectance curves of the lunar soil in the region of Mare Imbrium. This paper describes the working principle and detection characteristics of the VNIS and provides a reference for data processing and scientific applications.展开更多
文摘he electrochemistry of cytochrome C was investigated at a spectrographicgraphite electrode. In phosphate buffer solution (pH= 7. 0) , cytochrome C showedstable and quasi-reversible response. The formal potential E￣(o') was 0. 015 V (at25℃ , vs. SCE) and the heterogeneous electron transfer rate constant k_s obtainedvaried form 1. 10×10￣(-3) cm · s￣(-1) to 1. 80k×10￣(-3) cm · s￣(-1). The thermodynamic pa-rameters of the electron transfer reaction of cvtochrome C was also estimated. Fur-thermore, the effect of the various electrode surface states on the electrochemistryof cytochrome C was discussed.
文摘During high power laser welding, the amount of energy reaching the workpiece, the weld penetration and the geometry of the welds are strongly affected by the laser induced plasma. Light emissions during welding were recorded by a spectrometer. Based on the collected spectroscopic data, the electron density and the temperature of plasma were calculated using the relative intensity method. Several relationships between weld penetrations and electron density are given.
文摘/h/ is described differently by different researchers. While some argue that /h/ is a glottal fricative, others argue that it is the voiceless counterpart of the following vowel, yet others argue that /h/ is a glide or an approximant. However, de- tailed acoustic studies focusing on /h/ are very limited. This study aims to describe the spectrographic characteristics of /h/ in Turkish. Test words consisted of 48 monosyllabic and disyllabic words containing /h/ which was followed by eight Turkish vowels. Totally 1440 tokens were analyzed. After segmentation, /h/ was classified based on its spectrographic characteristics: 1) segment exhibiting formants, 2) segment exhibiting frication (but no formants) with energy in lower frequencies and 3) segment exhibiting almost no energy. In order to find out if there is a significant difference among these three categories, Chi-square test was applied. The spectrographic characteristics of /h/ in Turkish suggest that it is more like the voiceless version of the surrounding vowels, significantly when it is in syllable initial position and the preceding vowel when in syllable final position.
文摘With the spectrographic analysis, this paper analyzes the concentration of elements inoil, such as Fe, Cu, Cr, Al, Si etc. In order to monitor conditions and diagnose faults, the correlationcoefficient of main elements in oil has been used to study wear characteristics of friction pairs inrunning-in and working periods.
基金supported by the Turkish Scientific and Technological Research Council(TUBITAK)(Project No.118Y135).
文摘Higher heating value(HHV)is the key parameter for replacing Refuse-Derived Fuel(RDF)with fossil fuels in the cement industry.HHV can be measured with a bomb calorimeter or predicted from direct elemental data by using regression models.Both methods require the continuous use of special laboratory equipment and are time consuming.To overcome these limitations,this study aims to predict the HHV value of RDF from predicted elemental data by using regression models.Therefore,once the predicted elemental data are generated,there will be no need to have continuous elemental data to predict HHV.Predicted elemental data were generated from direct elemental data and Near Infrared(NIR)camera-based spectrometric data by using a deep learning model.A convolutional neural networks(CNN)model was used for deep learning and was trained with 10,500 NIR image samples,each of which was 28×28×1.Different regression models(Linear,Tree,Support-Vector Machine,Ensemble and Gaussian process)were applied for HHV prediction.According to these results,higher R2 values(>0.85)were obtained with Gaussian process models(except for the Rational Quadratic model)for the predicted elemental data.Among the Gaussian models,the highest R2(0.95)but the lowest Root Mean Square Error(RMSE)(0.0563),Mean Squared Error(MSE)(0.0317)and Mean Absolute Error(MAE)(0.0431)were obtained with the Mattern 5/2 model.The results of predictions from predicted elemental data were compared to predictions from direct elemental data.The results show that the regression from predicted elemental data has an adequate prediction(R2=0.95)compared to the prediction from the direct elemental data(R^(2)=0.99).
文摘The Chang’e-4 mission obtained spectral data of multiple rock targets on the lunar surface.The Modified Gaussian Model(MGM)is usually applied to the spectral interpretation of powder samples,its applicability and accuracy on the rock targets remain to be further evaluated.The rock slice of lunar meteorite NWA 4734 is used to conduct comprehensive analysis of the petrography,mineralogy and laboratory spectroscopy,which will provide important ground truth for the MGM interpretation of lunar in situ spectra of rock samples.First,a scanning electron microscope(SEM),Energy Dispersive Spectrometer(EDS),and Electron Probe Micro-Analyzer(EPMA)analysis results indicate that:(1)almost all plagioclase in NWA 4734 have been converted to maskelynites,which indicate that the meteorite has undergone severe impact metamorphism;(2)the chemical composition of pyroxene and olivine is significantly heterogeneous,showing a distribution characteristic of magnesium-rich core and iron-rich rim,further indicating that NWA 4734 has undergone multiple crystallization and differentiation.Second,this article focuses on the rock slice of NWA 4734ʼs greyscale image of the Back Scattering Electron(BSE),and obtains the proportion of High-Calcium Pyroxene(HCP)in the total pyroxenes of this sample by calculating the area percentage using the pixel counting method.The result shows that the proportion of HCP is 72%±5.4%,which can be used as a ground truth to evaluate the interpretation applicability and accuracy of MGM.A field spectrometer(ASD)is used to measure the visible and near-infrared reflectance spectra(450-2500 nm)of the rock slice from NWA 4734 in the same area as the BSE image obtained by SEM,and MGM is used to deconvolve the ASD spectra,and the average proportion of HCP is estimated to be 71%±10.1%.The results between the MGM and the pixel counting are comparable within the error range,which demonstrates the applicability of MGM on interpretation of the rock samples on the lunar surface.
文摘The infrared band contains rich opportunities for astronomical research,but due to the limitations of infrared technology,the development of infrared astronomy in China has been far from satisfactory for a long time,especially for solar observation.“Accurate Infrared Magnetic field Measurements of the Sun”project(AIMS)is a National Major Scientific Research Instrument Development Project(recommended by the Ministries)supported by the National Natural Science Foundation of China.It is aimed at improving the accuracy of magnetic field measurement by an order of magnitude,by measuring the“Zeeman splitting”directly.In addition,as AIMS is also the first equipment specifically designed for mid-to far-infrared solar observation in the world,we also hope to utilize AIMS to explore potential new scientific research opportunities in the vast infrared region.This article will briefly introduce the scientific objectives,the telescope,the scientific post-focus instruments,and finally summarize the commissioning observations of AIMS.
基金supported by the National Natural Science Foundation of China under grant No.U2031144partially supported by the Open Project Program of the Key Laboratory of Optical Astronomy,National Astronomical Observatories,Chinese Academy of Sciences+5 种基金supported by the National Key R&D Program of China with No.2021YFA1600404the National Natural Science Foundation of China(12173082)the Yunnan Fundamental Research Projects(grant 202201AT070069)the Top-notch Young Talents Program of Yunnan Provincethe Light of West China Program provided by the Chinese Academy of Sciencesthe International Centre of Supernovae,Yunnan Key Laboratory(No.202302AN360001)。
文摘BFOSC and YFOSC are the most frequently used instruments in the Xinglong 2.16 m telescope and Lijiang 2.4 m telescope,respectively.We developed a software package named“BYSpec”(BFOSC and YFOSC Spectra Reduction Package)dedicated to automatically reducing the long-slit and echelle spectra obtained by these two instruments.The package supports bias and flat-fielding correction,order location,background subtraction,automatic wavelength calibration,and absolute flux calibration.The optimal extraction method maximizes the signal-to-noise ratio and removes most of the cosmic rays imprinted in the spectra.A comparison with the 1D spectra reduced with IRAF verifies the reliability of the results.This open-source software is publicly available to the community.
基金Supported by National Natural Science Foundation of China(No.30500676)
文摘AIM: To investigate the protective mechanism of Gingko Biloba extract(EGb761) on the ability of retinal pigment epithelial(RPE) cells to resist light-induced damage in a comparative proteomics study. · METHODS: Human RPE cells(ARPE-19) were randomly distributed to one of three groups: normal control(NC group) and light-damaged model without or with EGb761 group(M and ME groups,respectively). The light-damaged model was formed by exposing to white light(2 200 ±300)lx for 6h. The RPE cells in ME group were conducted with EGb761(100μg/mL) before light exposure. The soluble cellular proteins extracting from each groups were separated by two-dimensional electrophoresis and stained by silver staining. Different proteins in the profiles of the gels were analyzed by Image Master Software. Two-fold expressing protein spots were identified by Matrix-assisted laser desorption/ ionization tandem time-of-flight(MALDI-TOF/TOF) mass spectrometry. ·RESULTS: NC,M and ME groups displayed 1 892±71,2 145 ±23 and 2 216 ±85 protein spots,respectively. We identified 33 proteins with different expression levels between the NC and M groups,25 proteins between the M and ME groups,and 11 proteins between the NC and ME groups. MALDI-TOF/TOF mass spectrometry successfully identified 16 proteins,including metabolic enzymes,cytoskeletal proteins,anti-oxidation proteins,and others. ·CONCLUSION: Differences in some important proteins,such as cathepsin B,heat shock protein,and cytochrome C reductase,indicated that multiple pathways may be induced in light-damaged RPE cells and the protective effect of EGb761.
基金The authors gratefully acknowledge the financial support received for this work from the National Natural Science Foundation of China[grant numbers 41471362 and 41071267]the Scientific Research Foundation for Returned Scholars,Ministry of Education of China(LXKQ201202)+1 种基金the Science and Technology Department of Fujian Province of China[grant numbers 2012I0005 and 2012J01167]The authors would like to thank the Natural Environment Research Council of UK for the provision of the airborne remote sensing data,and Ben Taylor and Gabriel Amable who kindly offered help in processing these data.
文摘Variogram has been utilized to exploring the spatial heterogeneity of remote sensing images,especially its association with spatial resolution.However,very few attentions have been drawn on evaluating the spatial heterogeneity of multisensor airborne imagery and its relationship with spectral wavelength.Therefore,an investigation was carried out on multisensor airborne images to determine the relation between spatial heterogeneity and spectral wavelength for woodland,grass,and urban landscapes by applying variogram modeling.The airborne thematic mapper(ATM),compact airborne spectrographic imager(CASI),and Specim AISA Eagle airborne images at Harwood Forest,Monks wood,Cambridge,and River Frome areas,UK,were utilized.Results revealed that(1)the red band contained greater spatial variability than near-infrared wavelengths and other visible wavebands;(2)there was a steep gradient at the red edge in reference to its spatial variability of multisensor airborne images;(3)only for natural landscape such as woodland and grass,near-infrared waveband contains greater within-scene variations than the blue and green bands;(4)compared with the discrepancy of spatial resolution introduced by multisensor images(ATM,CASI,and Eagle),the specific landscape and spectral bands were more important in determining heterogeneity by means of original visible,near-infrared bands,and normalized difference vegetation index(NDVI).These findings remained us to be caution when combining and interpreting spatial variability and spatial structures derived from airborne images with different spatial resolution and spectral wavelength.Additionally,the outcomes of this study also have considerable implications in terms of designing and choosing suitable images for different applications.
基金supported by the Joint Research Fund in Astronomy (U1631127, U1631129 and U1831204) under cooperative agreement between the National Natural Science Foundation of China (NSFC) and Chinese Academy of Sciences (CAS)the National Natural Science Foundation of China (NSFC) (11473068, 11603072 and 11573067)+1 种基金the National Key R&D Program of China (2018YFA0404603)supported by the Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences (CAS)
文摘The Lijiang 2.4-meter Telescope(LJT), the largest common-purpose optical telescope in China,has been available to the worldwide astronomical community since 2008. It is located at the Gaomeigu site,Lijiang Observatory(LJO), in the southwest of China. The site has very good observational conditions.During its 10-year operation, several instruments have been equipped on the LJT. Astronomers can perform both photometric and spectral observations. The main scientific goals of LJT include recording photometric and spectral evolution of supernovae, reverberation mapping of active galactic nuclei, investigating the physical properties of binary stars and near-earth objects(comets and asteroids), and identification of exoplanets and all kinds of transients. Until now, the masses of 41 high accretion rate black holes have been measured, and more than 168 supernovae have been identified by the LJT. More than 190 papers related to the LJT have been published. In this paper, the general observation conditions of the Gaomeigu site is introduced at first. Then, the structure of the LJT is described in detail, including the optical, mechanical, motion and control system. The specification of all the instruments and some detailed parameters of the YFOSC is also presented. Finally, some important scientific results and future expectations are summarized.
基金Supported by the National Natural Science Foundation of China
文摘As a facility used for astronomical research, the Lijiang 2.4-m telescope of Yunnan Astronomical Observatories, requires the ability to change one auxiliary instrument with another in as short a time as possible. This arises from the need to quickly respond to scientific programs （e.g. transient observation, time domain studies） and changes in observation conditions （e.g. seeing and weather conditions）. In this paper, we describe the design, construction and test of hardware and software in the rapid instrument exchange system （RIES） for the Cassegrain focal station of this telescope, which enables instruments to be quickly changed at night without much loss of observing time. Tests in the laboratory and at the telescope show that the image quality and pointing accuracy of RIES are satisfactory. With RIES, we observed the same Landolt standard stars almost at the same time with the Princeton Instruments VersArray 1300B Camera （PICCD） and the Yunnan Faint Object Spectrograph and Camera （YFOSC）, while both were mounted at the Cassegrain focus. A quasi-simultaneous comparison shows that the image quality of the optical system inside the YFOSC is comparable with that provided by the PICCD.
文摘We applied a Monte Carlo method -- simulated annealing algorithm -- to carry out the design of multilayer achromatic waveplate. We present solutions for three-, six- and ten-layer achromatic waveplates. The optimized retardance settings are found to be 89°51′39″ ± 0°33′37″ and 89°54′46″ ± 0°22′4″ for the six- and ten-layer waveplates, respectively, for a wavelength range from 1000 nm to 1800 nm. The polarimetric properties of multilayer waveplates are investigated based on several numerical experiments. In contrast to previously proposed three-layer achromatic waveplate, the fast axes of the new six- and ten-layer achromatic waveplate remain at fixed angles, independent of the wavelength. Two applications of multilayer achromatic waveplate are discussed, the general-purpose phase shifter and the birefringent filter in the Infrared Imaging Magnetograph （IRIM） system of the Big Bear Solar Observatory （BBSO）. We also checked an experimental method to measure the retardance of waveplates.
基金support of the National Natural Science Foundation of China(Grant No.11503005)Jiangsu Students’ Innovation and Entrepreneurship Training Program(201910294155Y and 201810294059X)the National Undergraduate Training Program for Innovation and Entrepreneurship(201810294099).
文摘The Large sky Area Multi-Object fiber Spectroscopic Telescope(LAMOST)is a Chinese national scientific research facility operated by National Astronomical Observatories,Chinese Academy of Sciences(NAOC).The LAMOST survey for the Milky Way Galaxy and extra-galactic objects has been carried out for several years.The accuracies in measuring radial velocity are expected to be 5 km s-1 for the low resolution spectroscopic survey(R=1800),and 1 km s-1 for the medium resolution mode.The stability of spectrograph is the main factor affecting the accuracies in measuring radial velocity,so an Active Flexure Compensation Method(AFCM)based on Back Propagation Neural Network(BPNN)is proposed in this paper.It utilizes a deep BP(4-layer,5-layer etc.)model of thermal-induced flexure to periodically predict and apply flexure corrections by commanding the corresponding tilt and tip motions to the camera.The spectrograph camera system is adjusted so that the positions of these spots match those in a reference image.The simulated calibration of this compensation method analytically illustrates its performance on LAMOST spectrograph.
基金supported by the Macao Science and Technology Development Fund(048/2012/A2,091/2013/A3 and 039/2013/A2)the National High Technology Research and Development Program of China(863 Program,2015AA123704)the National Natural Science Foundation of China(Nos.41172296 and 41422110)
文摘The absorption band center of visible and near infrared reflectance spectra is a key spectral parameter for lunar mineralogical studies, especially for the mafic minerals（olivine and pyroxene） of mare basalts, which have two obvious absorption bands at 1000 nm（Band I） and 2000 nm（Band II）. Removal of the continuum from spectra, which was developed by Clark and Roush and used to isolate the particular absorption feature, is necessary to estimate this parameter. The Moon Mineralogy Mapper（M3） data are widely used for lunar mineral identification. However, M3 data show a residual thermal effect, which interferes with the continuum removal, and systematic differences exist among optical data taken during different optical periods. This study investigated a suitable continuum removal method and compared the difference between two sets of M3 data taken during different optical periods, Optical Period 1B（OP1B）and Optical Period 2A（OP2A）. Two programs for continuum removal are reported in this paper. Generally,a program respectively constructs two straight lines across Band I and Band II to remove the continuum,which is recommended for locating band centers, because it can find the same Band I center with different right endpoints. The optimal right endpoint for continuum removal is mainly dominated by two optical period data at approximately 2480 and 2560 nm for OP1 B and OP2 A data, respectively. The band center values derived from OP1 B data are smaller than those derived from OP2 A data in Band I but larger in Band II, especially for the spectra using longer right endpoints（〉2600 nm）. This may be due to the spectral slopes of OP1 B data being steeper than those of OP2 A data in Band I but gentler in Band II. These results were applied to Mare Humorum and Mare Nubium, and the measurements were found to mainly vary from intermediate- to high-Ca pyroxene.
基金supported by the National Natural Science Foundation of China(NSFC,grants Nos.62127901,11988101,42075123 and 42005098)the National Key R&D Program of China No.2019YFA0405102+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(CAS),grant Nos.XDA15016200 and XDA15072113supported by the Chinese Academy of Sciences(CAS),through a grant to the CAS South America Center for Astronomy(CASSACA)in Santiago,Chilethe science research grants from the China Manned Space Project with No.CMS-CSST-2021-B12.
文摘It is expected that ongoing and future space-borne planet survey missions including Transiting Exoplanet Survey Satellite(TESS),PLATO and Earth 2.0 will detect thousands of small to medium-sized planets via the transit technique,including over a hundred habitable terrestrial rocky planets.To conduct a detailed study of these terrestrial planets,particularly the cool ones with wide orbits,the exoplanet community has proposed various follow-up missions.The currently proposed European Space Agency mission Ariel is the first step for this purpose,and it is capable of characterization of planets down to warm super-Earths mainly using transmission spectroscopy.The NASA Large Ultraviolet/Optical/Infrared Surveyor mission proposed in the Astro2020 Decadal Survey white paper will endeavor to further identify habitable rocky planets,and is expected to launch around 2045.In the meanwhile,China is funding a concept study of a 6 m class space telescope named Tianlin(a UV/Opt/NIR large aperture space telescope)that aims to start its operation within the next 10–15 yr and last for 5+yr.Tianlin will be primarily aimed at the discovery and characterization of rocky planets in the habitable zones around nearby stars and to search for potential biosignatures mainly using the direct imaging method.Transmission and emission spectroscopy at moderate to high resolution will be carried out as well on a population of exoplanets to strengthen the understanding of the formation and evolution of exoplanets.It will also be utilized to perform in-depth studies of the cosmic web and early galaxies,and constrain the nature of dark matter and dark energy.We describe briefly the primary scientific motivations and main technical considerations based on our preliminary simulation results.We find that a monolithic off-axis space telescope with primary mirror diameter larger than 6 m equipped with a high contrast coronagraph can identify water in the atmosphere of a habitable-zone Earth-like planet around a Sunlike star.More simulations for the detectability of other key biosignatures including O_(3),O_(2),CH_(4)and chlorophyll are coming.
基金partially supported by the National Natural Science Foundation of China (Grant No. 11103075)the West Light Foundation of Chinese Academy of Sciences
文摘The Multi-wavelength Spectrometer is a medium-dispersion（R^130 000）grating spectrometer installed on the New Vacuum Solar Telescope at the Fuxian Solar Observatory,Yunnan Astronomical Observatory,Chinese Academy of Sciences.It is designed to accurately observe the velocity and magnetic fields of the Sun.The present configuration of this spectrometer allows us to simultaneously observe three different solar spectral lines.This work is dedicated to showing the first observations carried out in both the Hαand Ca II 8542 A lines.We give a detailed description of the data reduction process,focusing on the retrieval of a flat field from the high-resolution spectral data.Two different methods are also performed and compared to eliminate the residual fringe in the reduced data.The real spectral resolution and instrumental profile are analyzed based on the final results,which indicate that this spectrometer presently satisfies the expected performance and it is ready for further scientific observations.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant No.11503054)NSFC Key Program(Grant No.11333004)+6 种基金the National Key Basic Research Program of China(Program 973Grant No.2014CB845700)The Guo Shou Jing Telescope(the Large sky Area Multi-Object fiber Spectroscopic Telescope,LAMOST)is a National Major Scientific Project built by the Chinese Academy of Sciencesthe project has been provided by the National Development and Reform CommissionSDSS-Ⅲhas been provided by the Alfred P.Sloan Foundationthe Participating Institutions,the National Science Foundationthe U.S.Department of Energy Office of Science
文摘Sky subtraction is a key technique in data reduction of multi-fiber spectra. Knowledge of characteristics related to the instrument is necessary to determine the method adopted in sky subtraction. In this study, we describe the sky subtraction method designed for the Large sky Area Multi-Object fiber Spectroscopic Telescope （LAMOST） survey. The method has been integrated into the LAMOST 2D Pipeline v2.6 and applied to data from LAMOST DR3 and later. For LAMOST, calibration using sky emission lines is used to alleviate the position-dependent （and thus time-dependent） ,-~ 4% fiber throughput uncertainty and small wavelength instability （0.1/~） during observation. Sky subtraction using principal component analysis （PCA） further reduces 25% of the sky line residual from OH fines in the red part of LAMOST spectra after the master sky spectrum, which is derived from a B-spline fit of 20 sky fibers in each spectrograph. Using this approach, values are adjusted by a sky emission line and subtracted from each fiber. Further analysis shows that our wavelength calibration accuracy is about 4.5 km s-1, and the averages of residuals after sky subtraction are about 3% for sky emission lines and 3% for the continuum region. The relative sky subtraction residuals vary with moonlight background brightness, and can reach as low as 1.5% for regions that have sky emission lines during a dark night. Tests on F stars with both similar sky emission line strength and similar object continuum intensity show that the sky emission line residual of LAMOST is smaller than that of the SDSS survey.
基金the National Natural Science Foundation of China 11703017,11790303(11790300),11803017,41774180,41904158,11973031the China Postdoctoral Science Foundation(2019M652385)+2 种基金Open Research Program CAS Key Laboratory of Solar ActivityNational Astronomical Observatories(KLSA201907)Young Scholars Program of Shandong University,Weihai(20820201005)。
文摘Solar radio spectra and their temporal evolution provide important clues to understand the energy release and electron acceleration process in the corona,and are commonly used to diagnose critical parameters such as the magnetic field strength.However,previous solar radio telescopes cannot provide high-quality data with complete frequency coverage.Aiming to develop a generalized solar radio observing system,in this study,we designed a digital receiving system that could capture solar radio bursts with a broad bandwidth and a large dynamic range.A dual-channel analog-to-digital converter(ADC)printed circuit board assembly(PCBA)with a sampling rate of 14-bit,1.25 Giga samples per second(GSPS)cooperates with the field-programmable-gate-array(FPGA)chip XC7K410T in the design.This receiver could realize the real-time acquisition and preprocessing of high-speed data of up to 5 GB s^(-1),which ensures high time and spectral resolutions in observations.This receiver has been used in the solar radio spectrometer working in the frequency range of 35 to 40 GHz in Chashan Solar Observatory(CSO)established by Shandong University,and will be further developed and used in the solar radio interferometers.The full-power bandwidth of the PCBA in this receiving system could reach up to 1.5 GHz,and the performance parameters(DC–1.5 GHz)are obtained as follows:spur free dynamic range(SFDR)of 64.7–78.4 dB,signal-to-noise and distortion(SINAD)of 49.1–57.2 dB,and effective number of bits(ENOB)of>7.86 bit.Based on the receiver that we designed,real-time solar microwave dynamic spectra have been acquired and more solar microwave bursts with fine spectral structures are hopeful to be detected in the coming solar maximum.
基金Supported by the National Natural Science Foundation of China
文摘The Visible and Near-Infrared Imaging Spectrometer （VNIS）, using two acousto-optic tunable filters as dispersive components, consists of a VIS/NIR imag- ing spectrometer （0.45-0.95 μm）, a shortwave IR spectrometer （0.9-2.4 p.m） and a calibration unit with dust-proofing functionality. The VNIS was utilized to detect the spectrum of the lunar surface and achieve in-orbit calibration, which satisfied the re- quirements for scientific detection. Mounted at the front of the Yutu rover, lunar ob- jects that are detected with the VNIS with a 45° visual angle to obtain spectra and ge- ometrical data in order to analyze the mineral composition of the lunar surface. After landing successfully on the Moon, the VNIS performed several explorations and cal- ibrations, and obtained several spectral images and spectral reflectance curves of the lunar soil in the region of Mare Imbrium. This paper describes the working principle and detection characteristics of the VNIS and provides a reference for data processing and scientific applications.
