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
Observation and research on solar radio emission have unique scientific values in solar and space physics and related space weather forecasting applications, since the observed spectral structures may carry important ...Observation and research on solar radio emission have unique scientific values in solar and space physics and related space weather forecasting applications, since the observed spectral structures may carry important information about energetic electrons and underlying physical mechanisms. In this study, we present the design of a novel dynamic spectrograph that has been installed at the Chashan Solar Radio Observatory operated by the Laboratory for Radio Technologies, Institute of Space Sciences at Shandong University. The spectrograph is characterized by real-time storage of digitized radio intensity data in the time domain and its capability to perform off-line spectral analysis of the radio spectra. The analog signals received via antennas and amplified with a low-noise amplifier are converted into digital data at a speed reaching up to 32 k data points per millisecond. The digital data are then saved into a high- speed electronic disk for further off-line spectral analysis. Using different word lengths （1-32k） and time cadences （5 ms-10 s） for off-line fast Fourier transform analysis, we can obtain the dynamic spectrum of a radio burst with different （user-defined） temporal （5 ms-10 s） and spectral （3 kHz-320kHz） resolutions. This enables great flexibility and convenience in data analysis of solar radio bursts, especially when some specific fine spectral structures are under study.展开更多
We present our state-of-the-art version of a frequency comb for calibration of astronomical spectrographs. The mode spacing of the frequency comb can be designed to match the resolution of a spectrograph. Combined wit...We present our state-of-the-art version of a frequency comb for calibration of astronomical spectrographs. The mode spacing of the frequency comb can be designed to match the resolution of a spectrograph. Combined with its excellent accuracy and stability, the spectral coverage of more than 70% of the whole visible spectrum range makes the frequency comb an ideal calibration source. In addition, the new version introduces the automatic start-up function that brings convenience to the astronomers.展开更多
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
The Coude Echelle Spectrograph(CES)was originally mounted on Xinglong 2.16 m telescope in 1994.When the High Resolution Fiber-fed Spectrograph(HRS)was commissioned at Xinglong 2.16 m telescope,the red path of CES was ...The Coude Echelle Spectrograph(CES)was originally mounted on Xinglong 2.16 m telescope in 1994.When the High Resolution Fiber-fed Spectrograph(HRS)was commissioned at Xinglong 2.16 m telescope,the red path of CES was moved to Lijiang 1.8 m telescope,following some redesign and reinstallation.The CES of Lijiang 1.8 m telescope has the spectral resolution(R=λ/?λ)ranging from 20000 to 50000 corresponding to different slit widths.With a 2 k×2 k PI CCD,CES has a wavelength coverage between 570 nm to 1030 nm.In particular,the resolution of 37000 at 0.5 mm slit corresponds to 1.3′′on the sky.The limiting magnitude is V=11.5 with the use of the tip-tilt feedback system,and the S/N is about 40 for 1 hour exposure at 600 nm(R=37000).During the installation of CES,the tip-tilt mirror technology had successfully fulfilled high precision guiding and tracking for high resolution spectral observation and significantly improved the observation efficiency.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
The Scientific Experimental system in Near SpacE(SENSE)consists of different types of instruments that will be installed on a balloon-based platform to characterize near-space environmental parameters.As one of the ma...The Scientific Experimental system in Near SpacE(SENSE)consists of different types of instruments that will be installed on a balloon-based platform to characterize near-space environmental parameters.As one of the main scientific payloads,the middle and near ultraviolet spectrograph(MN-UVS)will provide full spectra coverage from middle ultraviolet(MUV,200−300 nm)to near ultraviolet(NUV,300−400 nm)with a spectral resolution of 2 nm.Its primary mission is to acquire data regarding the UV radiation background of the upper atmosphere.The MN-UVS is made up of six primary components:a fore-optical module,an imaging grating module,a UV intensified focal plane module,a titanium alloy frame,a spectrometer control module,and a data processing module.This paper presents in detail the engineering design of each functional unit of the MN-UVS,as well as the instrument’s radiometric calibration,wavelength calibration,impact test,and low-pressure discharge test.Furthermore,we are able to report ground test and flight test results of high quality,showing that the MN-UVS has a promising future in upcoming near-space applications.展开更多
In 2016,an exposure meter was installed on the Lijiang Fiber-fed High-Resolution Spectrograph to monitor the coupling of starlight to the science fiber during observations.Based on it,we investigated a method to estim...In 2016,an exposure meter was installed on the Lijiang Fiber-fed High-Resolution Spectrograph to monitor the coupling of starlight to the science fiber during observations.Based on it,we investigated a method to estimate the exposure flux of the CCD in real time by using the counts of the photomultiplier tubes(PMT)of the exposure meter,and developed a piece of software to optimize the control of the exposure time.First,by using flat-field lamp observations,we determined that there is a linear and proportional relationship between the total counts of the PMT and the exposure flux of the CCD.Second,using historical observations of different spectral types,the corresponding relational conversion factors were determined and obtained separately.Third,the method was validated using actual observation data,which showed that all values of the coefficient of determination were greater than 0.92.Finally,software was developed to display the counts of the PMT and the estimated exposure flux of the CCD in real-time during the observation,providing a visual reference for optimizing the exposure time control.展开更多
The Beijing Faint Object Spectrograph and Camera （BFOSC） is one of the most important instruments operating in conjunction with the 2.16-m telescope at Xinglong Observatory. Every year there are - 20 SCI-papers publ...The Beijing Faint Object Spectrograph and Camera （BFOSC） is one of the most important instruments operating in conjunction with the 2.16-m telescope at Xinglong Observatory. Every year there are - 20 SCI-papers published based on observational data acquired with this telescope. In this work, we have systemically measured the total efficiency of the BFOSC that operates as part of the 2.16-m reflector, based on observations of two ESO flux standard stars. We have obtained the total efficiencies of the BFOSC instrument of different grisms with various slit widths in almost all ranges, and analyzed factors which effect the efficiency of this telescope and spectrograph. For astronomical observers, the result will be useful for them to select a suitable slit width, depending on their scientific goals and weather conditions during observations. For technicians, the result will help them to systemically identify the real efficiency of the telescope and spectrograph, and to further improve the total efficiency and observing capacity of the telescope technically.展开更多
A brief description of the NAO coude echelle spectrograph mounted on the 2.16 m telescope at Xinglong station is given. This echelle spectrograph is located at the coudé focus with a prism cross disperser. The ec...A brief description of the NAO coude echelle spectrograph mounted on the 2.16 m telescope at Xinglong station is given. This echelle spectrograph is located at the coudé focus with a prism cross disperser. The echelle image covers the spectral region from 330 to 1100 nm displayed in 80 spectral orders in one exposure through two light beams. With a slit height of 2mm, spectral orders are separated by 15 to 23 pixels in blue region and by 7 to 19 pixels in red region. Alternatively, two additional resolution modes corresponding to different focal length cameras with resolving power R 16000, 170 000 in the blue beam and R = 13000, 170 000 in the red beam could be provided by this spectrograph. The bias, dark, wavelength calibration, flat field and science exposure are described in details. The limiting magnitude for 1 hour exposure with an S/N ratio of 100 scales to V = 9.5 in the red path and to V = 7.2 in the blue path.展开更多
Taking use of the solar spectrograph in Yunnan Observatory, we built a model to estimate the spectral fluxes of solar spectrograph with computer and confirmed the result by observations. The spectral fluxes in visible...Taking use of the solar spectrograph in Yunnan Observatory, we built a model to estimate the spectral fluxes of solar spectrograph with computer and confirmed the result by observations. The spectral fluxes in visible and near infrared bands were calculated for the solar spectrograph of Yunnan Observatory.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
Integrated photonic spectrographs could provide a new generation of low-cost,highly integrated,high-performance optical terminal instruments for astronomical observations.However,these spectrographs still face the cha...Integrated photonic spectrographs could provide a new generation of low-cost,highly integrated,high-performance optical terminal instruments for astronomical observations.However,these spectrographs still face the challenge of high spectral resolution.In this Letter,we demonstrate a cascaded phase-modulated waveguide array(CPMWA)spectrograph,with designed and measured spectral resolutions of 100,000 and 68,000,respectively.A spectral reconstruction method is proposed to minimize the influence of the phase error induced during the chip fabrication process and increase the spectral contrast to 20 dB.This type of spectrograph demonstrates promising potential for high-resolution spectrum observations in astronomy.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
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 National Natural Science Foundation of China(41331068,11503014 and U1431103)the China Postdoctoral Science Foundation(2016M600538)
文摘Observation and research on solar radio emission have unique scientific values in solar and space physics and related space weather forecasting applications, since the observed spectral structures may carry important information about energetic electrons and underlying physical mechanisms. In this study, we present the design of a novel dynamic spectrograph that has been installed at the Chashan Solar Radio Observatory operated by the Laboratory for Radio Technologies, Institute of Space Sciences at Shandong University. The spectrograph is characterized by real-time storage of digitized radio intensity data in the time domain and its capability to perform off-line spectral analysis of the radio spectra. The analog signals received via antennas and amplified with a low-noise amplifier are converted into digital data at a speed reaching up to 32 k data points per millisecond. The digital data are then saved into a high- speed electronic disk for further off-line spectral analysis. Using different word lengths （1-32k） and time cadences （5 ms-10 s） for off-line fast Fourier transform analysis, we can obtain the dynamic spectrum of a radio burst with different （user-defined） temporal （5 ms-10 s） and spectral （3 kHz-320kHz） resolutions. This enables great flexibility and convenience in data analysis of solar radio bursts, especially when some specific fine spectral structures are under study.
文摘We present our state-of-the-art version of a frequency comb for calibration of astronomical spectrographs. The mode spacing of the frequency comb can be designed to match the resolution of a spectrograph. Combined with its excellent accuracy and stability, the spectral coverage of more than 70% of the whole visible spectrum range makes the frequency comb an ideal calibration source. In addition, the new version introduces the automatic start-up function that brings convenience to the astronomers.
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.
基金supported by the National Natural Science Foundation of China(11603072,11727806 and 11573069)the National Science Foundation of Yunnan(2016FA001)the CAS“Light of West China” Program and the Youth Innovation Promotion Association of the CAS.
文摘The Coude Echelle Spectrograph(CES)was originally mounted on Xinglong 2.16 m telescope in 1994.When the High Resolution Fiber-fed Spectrograph(HRS)was commissioned at Xinglong 2.16 m telescope,the red path of CES was moved to Lijiang 1.8 m telescope,following some redesign and reinstallation.The CES of Lijiang 1.8 m telescope has the spectral resolution(R=λ/?λ)ranging from 20000 to 50000 corresponding to different slit widths.With a 2 k×2 k PI CCD,CES has a wavelength coverage between 570 nm to 1030 nm.In particular,the resolution of 37000 at 0.5 mm slit corresponds to 1.3′′on the sky.The limiting magnitude is V=11.5 with the use of the tip-tilt feedback system,and the S/N is about 40 for 1 hour exposure at 600 nm(R=37000).During the installation of CES,the tip-tilt mirror technology had successfully fulfilled high precision guiding and tracking for high resolution spectral observation and significantly improved the observation efficiency.
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.
基金This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(grant XDA17010203,XDA17010201).
文摘The Scientific Experimental system in Near SpacE(SENSE)consists of different types of instruments that will be installed on a balloon-based platform to characterize near-space environmental parameters.As one of the main scientific payloads,the middle and near ultraviolet spectrograph(MN-UVS)will provide full spectra coverage from middle ultraviolet(MUV,200−300 nm)to near ultraviolet(NUV,300−400 nm)with a spectral resolution of 2 nm.Its primary mission is to acquire data regarding the UV radiation background of the upper atmosphere.The MN-UVS is made up of six primary components:a fore-optical module,an imaging grating module,a UV intensified focal plane module,a titanium alloy frame,a spectrometer control module,and a data processing module.This paper presents in detail the engineering design of each functional unit of the MN-UVS,as well as the instrument’s radiometric calibration,wavelength calibration,impact test,and low-pressure discharge test.Furthermore,we are able to report ground test and flight test results of high quality,showing that the MN-UVS has a promising future in upcoming near-space applications.
基金funded by the National Natural Science Foundation of China(NSFC,Nos.11803088,12003068 and 12063002)Civil Aerospace preresearch project D020302+2 种基金the science research grants from the China Manned Space Project with NO.CMS-CSST-2021-B10Yunnan Science Foundation of China(202001AU070077)SinoGerman Scientist Mobility Programme M-0086。
文摘In 2016,an exposure meter was installed on the Lijiang Fiber-fed High-Resolution Spectrograph to monitor the coupling of starlight to the science fiber during observations.Based on it,we investigated a method to estimate the exposure flux of the CCD in real time by using the counts of the photomultiplier tubes(PMT)of the exposure meter,and developed a piece of software to optimize the control of the exposure time.First,by using flat-field lamp observations,we determined that there is a linear and proportional relationship between the total counts of the PMT and the exposure flux of the CCD.Second,using historical observations of different spectral types,the corresponding relational conversion factors were determined and obtained separately.Third,the method was validated using actual observation data,which showed that all values of the coefficient of determination were greater than 0.92.Finally,software was developed to display the counts of the PMT and the estimated exposure flux of the CCD in real-time during the observation,providing a visual reference for optimizing the exposure time control.
基金supported by the Open Project Program of the Key Laboratory of Optical Astronomy,National Astronomical Observatories,Chinese Academy of Sciencesthe National Natural Science Foundation of China(Grant Nos.11503045 and 11373003)+1 种基金National Program on Key Research and Development Project(2016YFA0400804)National Key Basic Research Program of China(2015CB857002)
文摘The Beijing Faint Object Spectrograph and Camera （BFOSC） is one of the most important instruments operating in conjunction with the 2.16-m telescope at Xinglong Observatory. Every year there are - 20 SCI-papers published based on observational data acquired with this telescope. In this work, we have systemically measured the total efficiency of the BFOSC that operates as part of the 2.16-m reflector, based on observations of two ESO flux standard stars. We have obtained the total efficiencies of the BFOSC instrument of different grisms with various slit widths in almost all ranges, and analyzed factors which effect the efficiency of this telescope and spectrograph. For astronomical observers, the result will be useful for them to select a suitable slit width, depending on their scientific goals and weather conditions during observations. For technicians, the result will help them to systemically identify the real efficiency of the telescope and spectrograph, and to further improve the total efficiency and observing capacity of the telescope technically.
基金This wor is supported by NKBRSF G1999075406the National Natural Science FOundation of China under gran No. 19725312 and No.
文摘A brief description of the NAO coude echelle spectrograph mounted on the 2.16 m telescope at Xinglong station is given. This echelle spectrograph is located at the coudé focus with a prism cross disperser. The echelle image covers the spectral region from 330 to 1100 nm displayed in 80 spectral orders in one exposure through two light beams. With a slit height of 2mm, spectral orders are separated by 15 to 23 pixels in blue region and by 7 to 19 pixels in red region. Alternatively, two additional resolution modes corresponding to different focal length cameras with resolving power R 16000, 170 000 in the blue beam and R = 13000, 170 000 in the red beam could be provided by this spectrograph. The bias, dark, wavelength calibration, flat field and science exposure are described in details. The limiting magnitude for 1 hour exposure with an S/N ratio of 100 scales to V = 9.5 in the red path and to V = 7.2 in the blue path.
文摘Taking use of the solar spectrograph in Yunnan Observatory, we built a model to estimate the spectral fluxes of solar spectrograph with computer and confirmed the result by observations. The spectral fluxes in visible and near infrared bands were calculated for the solar spectrograph of Yunnan Observatory.
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.
基金supported by the National Natural Science Foundation of China(Nos.11973009,11933005,U23A20381,11904232,11774235,and 61705130)the Jiangsu Provincial Key Research and Development Program(No.BE2023080)+3 种基金the Chinese Academy of Sciences(No.KGFZD-145-23-04-03)the National Key Research and Development Program of China(No.2022YFE0107400)the Science and Technology Commission of Shanghai Municipality(Nos.23010503600 and 23530730500)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning(No.GZ2020015).
文摘Integrated photonic spectrographs could provide a new generation of low-cost,highly integrated,high-performance optical terminal instruments for astronomical observations.However,these spectrographs still face the challenge of high spectral resolution.In this Letter,we demonstrate a cascaded phase-modulated waveguide array(CPMWA)spectrograph,with designed and measured spectral resolutions of 100,000 and 68,000,respectively.A spectral reconstruction method is proposed to minimize the influence of the phase error induced during the chip fabrication process and increase the spectral contrast to 20 dB.This type of spectrograph demonstrates promising potential for high-resolution spectrum observations in astronomy.
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.
