Journals >Spectroscopy and Spectral Analysis
Contents
2017
Volume: 37 Issue 8
58 Article(s)
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Evaluation and Correction of Atmosphere Contamination on the Measurement of the Spectral Response of FY-2 Water Vapor Channels
XU Na, HU Xiu-qing, and CHEN Lin
Spectral response is an important parameter of satellite instruments, and is the integrated performance of the reflective and transmission characteristics of each optical element and the spectral response characteristics of detectors. As do not have monochromatic light source devices for onboard spectral calibration,thSpectral response is an important parameter of satellite instruments, and is the integrated performance of the reflective and transmission characteristics of each optical element and the spectral response characteristics of detectors. As do not have monochromatic light source devices for onboard spectral calibration,the spectral response in orbit is usually characterized by prelaunch evaluation in laboratory. Due to lack of vacuum environment, spectral response measurement in laboratory will be certainly contaminated due to atmospheric absorption between the calibration source and the instrument. In order to improve spectral calibration accuracy, influences of atmosphere contamination on the spectral response measurements of FY-2 water vapor channels were assessed based on a series of sensitivity tests using radiative transfer models (RTM). Because of the atmospheric absorption, the spectral responses become unsmooth, and the structure shows good consistency with the transmittance distribution. The channel brightness temperatures (BT) simulated based on contaminated SRF will be overestimated, and the biases increase exponentially over water vapor column. The biases are greater than 0.5 K and less than 1 K only during extremely dry environment with humidity less than 15% and homogeneous path less than 1m. However, when the homogeneous path approaches 4m under a normal ambient condition where the humidity is around 35%, the simulation BT bias can reach 4 K. Atmospheric contamination on spectral response measurement is happen for all water channels of FY-2 series satellites. Spectral correction was implemented for FY-2D by removing horizontal transmittance influence using spectra ratio. The corrected spectral response curve becomes much smooth and the distribution is more physically reasonable. The contamination leads to a warm bias of 2.2 K for clear sky top of atmosphere BT simulation, and a 7.6% positive bias for the blackbody radiance as well as the radiometric calibration calculation. The influence of atmospheric contamination on spectral response measurement is serious, thus can’t be ignored not only for the water vapor channel but for all absorptive channels. The contamination to spectral measurements which can not be neglected should be corrected from dividing the original spectral response by atmospheric transmittance..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2325 (2017)
Study on the Polarization Spectral Image Dehazing
XIA Pu, and LIU Xue-bin
Air pollution has a serious effect on the quality of image, and image taking under hazy weather suffers from poor contrast and resolution. It is of great significance to use the polarimetric spectral information for image dehazing and the research of polarization dehazing for spectral data cube. The data used in this pAir pollution has a serious effect on the quality of image, and image taking under hazy weather suffers from poor contrast and resolution. It is of great significance to use the polarimetric spectral information for image dehazing and the research of polarization dehazing for spectral data cube. The data used in this paper was pushbroomed under moderate hazy weather, and original Vis-NIR polarimetric data of 380~1 000 nm was captured, the original polarimetric images at 450, 550, 650, 750, 850 nm and the dehazed images were studied. The results of the research showed that wavelength had a significant effect on the difference of gray value between targets and background, and both the dynamic range of gray value and the smoothness of histogram were improved after the dehazing process. On average, the image contrast of the far-field targets increased by 5 times. The far-field targets at 450 nm had the lowest contrast, and the dehazing process increased the image contrast by 7.13 times which made the undetectable targets detectable. The far-field targets at 850 nm had the highest contrast, and the dehazing process increased the image contrast by 3.86 times. The dynamic range of histogram of the full image increased to 13.5% to 28.6% from 450 to 850 nm, the dynamic range of histogram of the near-field targets are increased to 33.3% to 44.0%. Based on the analyzation of the possible estimation error, two correction factors were proposed to revise the degree of polarization of the airlight and the intensity of the airlight from an object at an infinite distance, the regularity of the two factors were given to guide the image dehazing process under new conditions. The polarimetric information is obtained through the original data by the Stokes parameters, the dehazing process is based on the polarimetric difference between the air light scattered from the haze particles and the direct light reflected from the objects. The polarization spectral dehazing technique not only expands the application area of the imaging spectrometer, but also provides a new idea for image dehazing..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2331 (2017)
Visible-Near Infrared Hyperspectral Imaging Combined with Chemometric Methods to Distinguish Human Facial Information
YU Yang, ZHANG Xin, LIAO Yi, and ZHANG Zhuo-yong
The human face information, like the fingerprint and iris, can be used for the identification of a person, and is easier to achieve long-range resolution and identification. Hyperspectral imaging can be used to obtain a wealth of chemical properties and a large amount of data for human identity, while we need to use chThe human face information, like the fingerprint and iris, can be used for the identification of a person, and is easier to achieve long-range resolution and identification. Hyperspectral imaging can be used to obtain a wealth of chemical properties and a large amount of data for human identity, while we need to use chemometric methods to extract the chemical characteristics from the image dataset, and the obtained face feature can be used for computer recognition. In this paper, we have investigated the feasibility of the analysis of human face by using hyperspectral imaging combined with chemometric methods. We compared the results of multivariate curve resolution alternating least squares (MCR-ALS) and principal component analysis (PCA). MCR-ALS gave the pure principal components spectra and their corresponding relative concentrations to display the information of the human face, and constraints could be applied conveniently based the features of imaging data. In addition, the method of partial least squares discriminant analysis (PLS-DA) was used to classify the human skin signal spectrum. From the spectra analyzed, the facial information of white and yellow people is similar, and the classification of them are more difficult than that of dark skinned people..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2339 (2017)
Ion Velocity Distribution Function Measurement Based on the Method of Bidirectional Polarized Laser Induced Fluorescence
YANG Xiong, CHENG Mou-sen, and WANG Mo-ge
To evaluate the velocity performance of the accelerated ions in the helicon plasma using the electric double layer effect in a divergent magnetic field, the laser induced fluorescence with a bidirectional polarization method was utilized to measure the ion velocity distribution function near the exit of plasma source. To evaluate the velocity performance of the accelerated ions in the helicon plasma using the electric double layer effect in a divergent magnetic field, the laser induced fluorescence with a bidirectional polarization method was utilized to measure the ion velocity distribution function near the exit of plasma source. In the discharge experiment, Ar was used as the working medium. The laser with central wavelength of 611.662 nm was injected to the plasma axially, by which the primarily ionized ions were stimulated to a higher level and then emitted the fluorescence with wavelength of 461.086 nm. To remove the splitting of laser induced fluorescence spectrum by inverse Zeeman effect in a magnetized plasma, the injected laser was modulated to the left-hand and the right-hand circular polarization by a quarter-wave plate, and the induced fluorescence spectrum were measured respectively. Results show that the wavelength shifts of the two measurements with different magnetic field matched with the theory rather well, which proves the feasibility of the bidirectional polarization method in this work. Furthermore, a Gaussian inverse filter was used as the deconvolution arithmetic to wipe off the natural broadening and saturation broadening from the measured fluorescence signal, then the inverse Zeeman splitting effect was eliminated and the pure Doppler broadening and shift was obtained after dealing with the results by shifting and averaging the results of the two contrary polarization. Under the condition of injected radio-frequency power 600 W, parameters including the stimulated position, the magnetic field strength and the gas pressure were changed to investigate the regulation of ion velocity distribution function. Results indicate that the near-field ion velocity distribution was symmetrical and matched well with a Gaussian distribution, while the far-field ion velocity distribution was somewhat concentrated to the low-velocity part. The averaged ion velocity arises with the increase of the magnetic field strength, while, with the decrease of the gas pressure. In addition, the velocity reduces with the stimulated position more approaching to the downstream of discharge chamber. Although the ion was exhausted with a definite bulk velocity, the order of the accelerated velocity is lower than the expected values of the electric double layer, which attributes more to the bipolar electric field under the restrain of the magnetic field in plasma. Therefore, the compact helicon wave plasma without any extra ion accelerated method couldn’t gain a good thruster performance..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2346 (2017)
Study on Effective Wavelength Calibration Method of Multispectral Pyrometer
LIANG Mei, SUN Bo-jun, SUN Xiao-gang, XIE Jun-yan, and YU Chen-tao
For the problem that the effective wavelength cannot be obtained because the signal is too weak due to fiber coupling during wavelength calibration of optical fiber multi-spectral pyrometer, a new effective wavelength determination method is proposed based on the data of temperature calibration. Based on the Planck’s lFor the problem that the effective wavelength cannot be obtained because the signal is too weak due to fiber coupling during wavelength calibration of optical fiber multi-spectral pyrometer, a new effective wavelength determination method is proposed based on the data of temperature calibration. Based on the Planck’s law, a new method for solving the wavelength is presented, combining with the calibration value ratios of different calibration temperature points. Compared with the traditional method of effective wavelength calibration, the new method proposed in this paper not only provides a new way to get the effective wavelength fast, but also avoids the complexity of the wavelength calibration process. Simulation and experiment were used in this paper to verify the feasibility and effectiveness of the new method. The simulation results showed that the new method which was feasible to get the effective wavelength had the anti-random error ability, and the relative error between the true temperature calculation value based on the effective wavelength and the actual value was less than 0.7%. The experimental results showed that the new method could get the effective wavelength of each channel, and further verify the effectiveness of the proposed method. The new method proposed in this paper can also be applied to other multi-spectral pyrometer, providing a theoretical basis for the development and application of the multi-spectral pyrometer..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2352 (2017)
Experimental Study on Terahertz Spectrum of Lacidipine
HUANG Yu, SUN Ping, ZHANG Zheng, JIN Chen, LIU Wei, and WANG Wen-ai
The terahertz time-domain reflection signals of highly pure Lacidipine (98%) and Lacidipine tablets (2%) were measured and then their absorption and refractive index spectra were extracted respectively. Through comparing the frequencies between the measured absorption peaks and the results calculated by CASTEP softwareThe terahertz time-domain reflection signals of highly pure Lacidipine (98%) and Lacidipine tablets (2%) were measured and then their absorption and refractive index spectra were extracted respectively. Through comparing the frequencies between the measured absorption peaks and the results calculated by CASTEP software, we got the fingerprint of Lacidipine using Lorentz fitting. There were six characteristic frequencies located at 0.62, 0.78, 1.07, 1.28, 1.63 and 1.76 THz, respectively. Because other substances were added into tablets as supplementary materials, and the recognition of absorption characteristics of lacidipine was disturbed by absorption of these substances, the number of characteristic absorption peaks decreased to 4 at 0.62, 0.78, 1.28 and 1.63 THz. In addition, there was a large difference in the refractive index spectra of the pure samples and oral tablets, which was also related to the supplementary materials in the oral administration. Although Lacidipine’s content was very low in the actual Lacidipine oral tablets, THz fingerprint spectrum could still recognize some characteristic frequencies. Therefore, the terahertz time-domain spectroscopy is an effective tool for detecting components of Lacidipine drugs..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2356 (2017)
Terahertz Spectroscopic Identification with Diffusion Maps
NI Jia-peng, SHEN Tao, ZHU Yan, LI Ling-jie, MAO Cun-li, and YU Zheng-tao
Feature extraction is the key issue for the identification of terahertz spectroscopy. For the traditional method, it is identified by different absorption peaks as the features that extracted through manual method. However, for many materials, there are no apparent spectral graphics features in the terahertz band, suchFeature extraction is the key issue for the identification of terahertz spectroscopy. For the traditional method, it is identified by different absorption peaks as the features that extracted through manual method. However, for many materials, there are no apparent spectral graphics features in the terahertz band, such as peaks, valleys and etc. To this end, the researchers reduce the dimension from the high-dimensional terahertz spectroscopy data and extract the features through statistics learning and machine learning methods. Linear method is easy to cause greater error due to the nonlinear nature of terahertz spectroscopy data, especially when different materials of spectrum curves are very similar. To address this issue, a novel terahertz spectroscopy identification approach with Diffusion Maps (DM) was studied in this paper. Diffusion Maps can realize nonlinear dimensionality reduction while maintaining the internal geometry of the data. In addition, the manifold features extracted by the method have good discrimination and clustering performance. Firstly, S-G filter and cubic spline interpolation were used to smooth and uniform the resolution of terahertz transmission spectra of ten kinds of substances in the same frequency band. Secondly, high-dimensional data of terahertz spectra is mapped to the low-dimensional feature space by using DM so that we can extract the manifold features of terahertz spectroscopy. Finally, a Multi-class Support Vector Machine (M-SVM) classifier is applied to classify these terahertz spectra. Experimental results show that, compared with Principal Component Analysis (PCA) and Isometric Mapping (ISOMAP), manifold features of terahertz spectroscopy extracted by DM have higher degree of differentiation. Besides, DM can get the estimation of intrinsic dimension of terahertz spectra directly. So this proposed method provides a novel approach to identify similar terahertz spectrum quickly and accurately..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2360 (2017)
Research on Scattering in the THz Quantitative Analysis of Granulated Coal
LIANG Liang, TONG Min-ming, WEI Ming-sheng, LI Meng, and DONG Hai-bo
Spectral distortions are common in quantitative terahertz spectra measurement of granulated coal. These spectra warping in the spectroscopy are caused by electromagnetic wave scattering due to coal particles and HDPE intergranularpore-space developed during tableting process consisted in the tablet. In this paper, an eSpectral distortions are common in quantitative terahertz spectra measurement of granulated coal. These spectra warping in the spectroscopy are caused by electromagnetic wave scattering due to coal particles and HDPE intergranularpore-space developed during tableting process consisted in the tablet. In this paper, an equivalent coal-HDPE mixture tablet is built according to the two substances’ structural differences. The scattering contributions of coal particles and air voids are investigated by using the theories of Foldy-Twersky EFA and iterative Waterman-Truell EFA in the frequency from 2 to 3.5 THz, establishing a quantitative analytical model of intrinsic absorption spectra of coal. The studied 6 samples are mixtures of HDPE powder and granulated coal, whose grain sizes varies from one another while the volume concentration is kept constant. Experimental data are recorded with a THz-TDS setup. The scattering loss caused by air voids is more notable when the size of coal particle is smaller than 38.5 μm. When the coal particle size is between 38.5 and 55 μm, it could be observed that the extinction caused by coal particles is more or less the same with it by the air voids. With the increase of coal particle diameter, the scattering contribution of granulated coal to the total propagation loss becomes evident. The correlation coefficient and RMSE between the original and calibrated spectra indicated that the studied quantitative analytical model could significantly reduce the effect of scattering to the measured THz spectrum of coal sample when coal particle size smaller than 105 μm. This study could provide a theoretical basis for quantitative terahertz spectra measurement of coal..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2365 (2017)
Optical Characteristics and Gas Temperature of a Surface Discharge Plasma Jet Controlled with a Dielectric Barrier
LIN Xiao-tong, LIU Shu-hua, FU Nian, ZHANG Pan-pan, LI Xue-chen, and JIA Peng-ying
A surface discharge plasma jet controlled by a dielectric barrier layer is developed to generate a uniform plasma plume in ambient air at atmospheric pressure through using argon as the working gas. The discharge characteristics of the plasma jet are investigated by electrical and optical methods. It is found that the A surface discharge plasma jet controlled by a dielectric barrier layer is developed to generate a uniform plasma plume in ambient air at atmospheric pressure through using argon as the working gas. The discharge characteristics of the plasma jet are investigated by electrical and optical methods. It is found that the discharge pulses only exist in the positive half cycle of the applied voltage and the pulse number increases with the increasing of the gas flow rate. Spatially resolved measurements are implemented on the plasma plume for the positive half cycle of the applied voltage. It has been found that the plasma plume behaves just like a plasma bullet under different experimental conditions. Each pulse corresponds to a bullet propagating process. The total light emission signal is compared with the discharge current signal, and it is found that the total light emission signal has a time lag with the discharge current signal. The delay time between them obeys the Normal distribution. It decreases with the increasing of the peak value of the applied voltage or the gas flow rate. The gas temperature of the discharge is investigated by using an optical fiber thermometer, and results show that the gas temperature increases with the increasing of the applied voltage or the decreasing of the gas flow rate. Through analyzing the gas discharge mechanism, these experimental phenomena are investigated qualitatively..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2371 (2017)
Application of Particle Swarm Algorithm and GMM-SDR Model in Overlapping Spectrum Peak Analysis
YANG Xi, HUANG Hong-quan, JIANG Kai-ming, CHEN Wen-de, ZHOU Wei, and WANG Man-man
In X-Ray spectrum analysis, the phenomenon of overlapping often occurs among spectrum peaks. In this paper, “Gaussian Mixture Model-Standard Deviation Related”(GMM-SDR) and Particle Swarm Optimization Algorithms were used for overlapping spectrum peak analysis. First, the GMM-SDR model of overlapping peaks was introducIn X-Ray spectrum analysis, the phenomenon of overlapping often occurs among spectrum peaks. In this paper, “Gaussian Mixture Model-Standard Deviation Related”(GMM-SDR) and Particle Swarm Optimization Algorithms were used for overlapping spectrum peak analysis. First, the GMM-SDR model of overlapping peaks was introduced, and the GMM-SDR parameters constitute the particle position. The objective function and the fast algorithm for the fitness function value were proposed. Secondly, the population search technology of particle swarm optimization algorithm was used to search the optimal GMM-SDR before decomposiing the overlapping peaks. In this algorithm, the initial value was set randomly and all measured random data were regarded as a whole. Since the probability matching degree of the model was taken as the fitness value, the method avoided the local convergence problem caused by improper initial value setting, and overcame the destruction of traditional curve fitting method to the original useful data. In fact, the model built with this method is a global optimal solution. The decomposition experiments of four showed high precision of the peak position, peak area and standard deviation with fewer overlapping peaks . The maximum relative error of decomposition of the two overlapping peaks was 0.4%, 0.05%, 2.07%, and which of the three overlapping peaks was 1.2%, 0.04% and 0.74%, respectively, which can be widely used for the decomposition of other overlapping peaks..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2376 (2017)
Characteristics of Spectral Radiation for Al+ During Hypervelocity Impact on 2A12 Aluminum Target
TANG En-ling, SONG Ji-qiu, ZHANG Qing-ming, HAN Ya-fei, HE Li-ping, WANG Meng, XIANG Sheng-hai, XIA Jin, LIU Shu-hua, GUO Kai, ZHANG Shuang, ZHANG Li-jiao, YUAN Jian-fei, and WU Jin
The light flash and plasma effects are produced when the material is subjected to strong shock. Saha formula suiting for caculating ionization degree of plasma generated by hypervelocity impact was derived through hypervelocity impact experiments with multiple kinds of advanced measuring methods and theoretical derivatThe light flash and plasma effects are produced when the material is subjected to strong shock. Saha formula suiting for caculating ionization degree of plasma generated by hypervelocity impact was derived through hypervelocity impact experiments with multiple kinds of advanced measuring methods and theoretical derivations in the paper. All these have provided powerful tools for determining matter composition of projectile and the target during hypervelocity impact. The two-stage light gas gun loading system combined with triple Langmuir probe diagnostic system and spectral radiant measurement system of ESA4000 spectrometer were used to perform three experiments under the different impact velocity conditions. The experimental results showed that the ultra-high speed impacting on 2A12 aluminum target produced flash radiation which contained Al+ spectrum radiation. The relationship between the collision speed and the radiant intensity was further revealed through the analysis of the experimental data. With the increasing of the impact velocity, the spectral radiation intensity enhanced in Al+, and the smaller wavelength spectral line intensity increased rapidly, the longer wavelength spectral line intensity increased slowly in Al+ spectral. Research on aluminum ion radiant temperature and spectral radiant characteristics has important application value during hypervelocity impact on 2A12 aluminum target in the fields of spacecraft space debris shield, missile interception, astrophysics and deep space detection. In addition, characteristic parameter measurement and spectral radiant characteristics of plasma has important theoretical significance in revealing the hypervelocity impact phenomena.at the micro level..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2381 (2017)
Progresses in Applications of Infrared Spectral Analysis Technology to Flotation Process
XU Peng-yun, LI Jing, CHEN Zhou, and YE Hong-qi
Along with the development of flotation theories and practices, the mechanism of the interaction between the flotation reagents and minerals has become the focus of current researches. Infrared spectral analysis technology has gained considerable popularity, thus it has became one of the most important research techniqAlong with the development of flotation theories and practices, the mechanism of the interaction between the flotation reagents and minerals has become the focus of current researches. Infrared spectral analysis technology has gained considerable popularity, thus it has became one of the most important research techniques in the field of action mechanism of flotation reagents with the characteristics of high speed, low cost and nondestructive. Firstly, the important status of infrared spectroscopy is introduced in view of the amount and rate of related literature. Then, infrared spectrum characteristics of common flotation reagents are summarized. Finally, progresses in applications of infrared spectral analysis technology to the collector, inhibitor and activator are described respectively. With this basis, infrared spectrum analysis criteria for action mechanisms of collectors on mineral surfaces are proposed. The chemical reaction between mineral and collector happened when the characteristic peaks of new compound can be found on the treated mineral surfaces. If only the positions of the characteristic peaks are shifted, and the displacement of this shift exceeded the background error of instrument, the chemical adsorption can be confirmed. If the characteristic peaks of new compound cannot be found and the positions of the characteristic peaks are not shifted but distilled water could wash the collectors down from the treated mineral surfaces, the physical adsorption must be confirmed. Meanwhile, two problems in this research field are discussed. On the one hand, mechanism of chemical reaction and chemical adsorption are often confused, on the other hand, background error of the infrared spectrum instrument tends to be ignored. Furthermore, the application of infrared spectroscopy in flotation need to be further investigated in three aspects,including the mechanism of mixing flotation reagents, quantitative analysis and error analysis..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2389 (2017)
Degradation Analysis for FY3B/VIRR Reflective Solar Bands Based on the Dunhuang Radiometric Calibration Site
Lü Jiayan, Chen Lin, He Mingyuan, and Hu Xiuqing
The Visible and Infrared Radiometer (VIRR) boarded on FY3B which is the new generation polar orbit meteorological satellite of China needs constant radiometric calibration after launch for improving the quality of data and better meeting the needs of users. In order to investigate the radiometric response degradation oThe Visible and Infrared Radiometer (VIRR) boarded on FY3B which is the new generation polar orbit meteorological satellite of China needs constant radiometric calibration after launch for improving the quality of data and better meeting the needs of users. In order to investigate the radiometric response degradation of FY3B/VIRR, the radiometric calibration coefficients of its reflective solar bands are calculated by the reflectance-based method, using the in-situ experiment data of Dunhuang radiometric calibration site from 2011 to 2015. The corresponding relative standard deviation of each band’s radiometric calibration coefficient is less than 1.5%, except band 10 which is influenced by water vapor absorption. By comparing with the Aqua/MODIS observation data, the average deviation of our results is less than 2.5%. Then, the annual degradation rates of VIRR are achieved based on its five-year calibration coefficients, compared with the pre-launch calibration coefficient. This paper suggests that: (1) The degradation rate depends on the wavelength of the band, the degradation rate increases with the decrease of wavelength; (2) Compared with the pre-launch calibration coefficient, the VIRR sensor shows dramatic radiometric response change after one-year orbiting operation; (3) In general, the degradation rate decreases with the extension of operating time, especially in the second and the third year; (4) After three-year orbiting operation, the degradation rate of the band with wavelength less than 0.8μm appear to increase; (5) After two-year orbiting operation, the radiometric response of the band with wavelength greater than 0.8μm increases in some period; (6) Comparing to the degradation changes of FY3A/MERSI proposed by Sun, both of the two sensors demonstrate a negative correlation between the degradation rate and the wavelength, but the radiometric responses of MERSI’s band 3 and 13 at 0.65 μm appear to increase, on the contrary, the degradation of VIRR’s band 1 at the same wavelength tends to increase; (7) The annual degradation rate of short wavelength band 7, 8 and 9 is greater than 5% in the long run..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2397 (2017)
Antioxidant Property Prediction of Methanol Extracts of Crude Drug Based on Near Infrared Spectroscopy
LI Cai-yi, ZHANG Guo-ying, DONG Xiu-ying, ZHANG Hai-ying, L Qing-tao, and LING Jian-ya
A prediction model was built to estimate the antioxidant property of methanol extracts of 38 crude drugs using Near Infrared Spectroscopy (NIS) with partial least squares (PLS) regression method. In order to enhance the chemical information and reduce data systemic noise, the effect of spectral pretreatment methods on A prediction model was built to estimate the antioxidant property of methanol extracts of 38 crude drugs using Near Infrared Spectroscopy (NIS) with partial least squares (PLS) regression method. In order to enhance the chemical information and reduce data systemic noise, the effect of spectral pretreatment methods on the model were compared according to the correlation coefficients of cross validation (R2) and the root mean square errors of cross validation (RMSECV). Prediction effects of the samples were investigated with the root mean square errors of prediction (RMSEP), and the residual predictive deviation (RPD). The DPPH method was employed for verification. The present results showed that the calibration model was developed by first derivative+vector normalization with the selected spectral region, R2, RMSECV, RMSEP, and RPD were 0.896 0, 4.35%, 3.62%, and 2.38, respectively. The NIS model established in the present study was relatively stable, accurate and reliable for overall evaluation of antioxidant activity of crude drugs. However, it was necessary to improve the precision and the robustness of the model for practice．.
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2402 (2017)
XPS and FTIR Spectroscopy Characterization about the Structure of Coking Coal in Xinyang
GE Tao, ZHANG Ming-xu, and MA Xiang-mei
Structure and occurrence recognition for primary elements in coal are the foundations to acquire coal structural parameters and it is of great significance to construct a coal structure model, study reaction characteristics of coal and rationally utilize coal resources. At present, studies on the coal structure are mosStructure and occurrence recognition for primary elements in coal are the foundations to acquire coal structural parameters and it is of great significance to construct a coal structure model, study reaction characteristics of coal and rationally utilize coal resources. At present, studies on the coal structure are most targeted at coals with a low-medium metamorphic degree. In comparison, the structure of coking coal is rarely studied and no structure model has been presented for it. In this paper, FTIR was adopted to carry out spectral characterization for hydroxyl polar groups, fat composition, aromatic structure, oxygen-containing functional group and miscellaneous atomic structure in Xinyang coking coal. The results demonstrated that, on the one hand, hydroxide radical π hydrogen bond formed by the Xinyang coking coal with π electrons in the aromatic nucleus was a main existing form of hydroxide radical; on the other hand, polymer was a concrete embodiment of associated structures in the coal. Besides, it also indicated that contents of methyne, methyl and methylene went up successively; and, methylene and methyne had a content occupying 82.05% in the total aliphatic hydrocarbon content in coal. The coal contained a great number of alkyl side-chains. Benzene ring-disubstitution and trisubstitution, with 86.74% taking in the total aromatic hydrocarbon content of coal, were primary structures of them. For an oxygen-containing functional group, while hydroxide radical and carbonyl were its principal composition groups, the content of carboxyl and ether group was less than 10%. In the Xinyang coal enriched with silicon, its occurrence lies in forms of Si—O—Si and Si—O—C. The main existing form of nitrogen included pyridine, pyrrole and oxynitride and most nitrogen distributed on edges of building blocks of coal molecules. As far as organic sulfur in coal was concerned, its primary existing form was thiophenic sulfur, the content of which exceeded 60% of the total organic sulfur content, followed by those of sulphone and sulfoxide. Occurrences of mercaptan and thioether were both at a minimum level..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2406 (2017)
Pharmaceutical Discrimination by Using Sparse Denoising Autoencoder Combined with Gaussian Process Based on Near Infrared Spectrum
ZHOU Jie-qian, LIU Zhen-bing, YANG Hui-hua, ZHENG An-bing, PAN Xi-peng, CAO Zhi-wei, WU Kai-yu, YANG Jin-xin, FENG Yan-chun, YIN Li-hui, and HU Chang-qin
In this paper, a new method for pharmaceutical discrimination by the near infrared spectrum is proposed, which is based on the sparse denoising autoencoder (SDAE) combined with Gauss process (GP). First of all, the Mexican hat wavelet transform was used to eliminate noise and baseline drift from the spectra data, then In this paper, a new method for pharmaceutical discrimination by the near infrared spectrum is proposed, which is based on the sparse denoising autoencoder (SDAE) combined with Gauss process (GP). First of all, the Mexican hat wavelet transform was used to eliminate noise and baseline drift from the spectra data, then SDAE network was used to extract the feature and reduce dimension of spectrum. Finally, GP was used for binary classification, in which the GP selected the spectral mixture (SM) kernel function as its covariance function. This classification method was named as wSDAGSM. Autoencoder network has a strong ability of model representation, and GP classifier has the advantage in dealing with small sample data. The WSDAGSM network is able to obtain fewer dimensions and more valuable features by SDAE learning to represent the input data. Meanwhile, the spectral mixture kernel function which has a good expression was used as the covariance function of the GP in the WSDAGSM network. Therefore the WSDAGSM network is conducive to more accurate classification of spectral data. With near infrared spectra of Erythromycin Ethylsuccinate and other pharmaceuticals as experimental data, some classification methods were used after Mexican hat wavelet transform, they were BP neural network (wBP), support vector machine (wSVM), SDAE combined with binary classification of Logistic (wSDAL), SDAE combined with binary classification of GP selected the squared exponential (SE) kernel function (wSDAGSE). And another method was also applied, which was SDAGSM network without Mexican hat wavelet transform. All above methods were used for comparing with wSDAGSM network. Experimental results show that SDAGSM can effectively improve the classification accuracy and stability by applying the wavelet transform to the spectral data. The proposed method wSDAGSM is superior to other classifiers in terms of classification accuracy and stability of the classification results..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2412 (2017)
Study on the Origin Identification and Saponins Content Prediction of Panax notoginseng by FTIR Combined with Chemometrics
LI Yun, XU Fu-rong, ZHANG Jin-yu, and WANG Yuan-zhong
Different origins have significant impact on the secondary metabolites of traditional Chinese medicine (TCM), so identification of origins is helpful for scientific and rational utilization of TCM. Additionally, the detection of active ingredient content is the main way to evaluate the quality of TCM. In this study, weDifferent origins have significant impact on the secondary metabolites of traditional Chinese medicine (TCM), so identification of origins is helpful for scientific and rational utilization of TCM. Additionally, the detection of active ingredient content is the main way to evaluate the quality of TCM. In this study, we established a rapidly method to identify the origins and detect active ingredient content of Panax notoginseng in order to provide some research bases for scientific, rational and specific utilization and rapid quality assessment of P. notoginseng. A total of 117 Fourier transform infrared (FTIR) spectra of P. notoginseng originated from five regions were collected. The discrete wavelet transform was used to process the original spectra in order to remove part of the high-frequency signal caused by noise while partial least squares discriminant analysis (PLS-DA) was used to screen the data with the contribution rate greater than one. Moreover, 70% of the 117 individuals were selected to form the training set by using Kennard-stone algorithm as well as the other 30% were used as prediction set. Training set data were used to establish the discriminant model of support vector machine and the cross-validation method was used for screening optimal parameters as well as the prediction data were utilized to verify the results of discriminant model. The pre-processing data to predict saponins content were processed by standard normal variable transform and discrete wavelet transform. Processed date of FTIR spectra were set as variable X and the total contents of four kinds of saponins in P. notoginseng samples measured by high performance liquid chromatography (HPLC) were set as variable Y. The orthogonal signal correction was used to remove the unrelated data of FTIR to saponins content of P. notoginseng samples. 80% of the individual data were selected as training set and the other 20% were utilized to form the prediction set. The partial least squares regression model was established by training set and the prediction set was utilized to verify the results of the model. The results showed that, (1) The optimal parameters c and g of support vector machine calculated by cross-validation was 2.828 43 and 0.062 5 respectively and the optimal accuracy of training set was 91.463 4%. (2) The support vector machine model was set as the optimal parameter and the accuracy of prediction set was 94.285 7% which showed a high accuracy. (3) The correlation coefficient (R2) and the root mean square error of estimation (RMSEE) of partial least squares regression model established by training set was 0.941 8 and 4.530 7, respectively. (4) The R2 and the root mean square error of prediction (RMSEP) of partial least squares regression model verified by prediction set was 0.962 3 and 3.855 9 respectively showing predictive value of saponins content was close to the value detected by HPLC. FTIR combined with support vector machine could effectively identify different origins of P. notoginseng. Orthogonal single collection and partial least squares regression could accurately predict the value of total four saponins content of P. notoginseng. It could provide a simple, rapid, non-destructive, high sensitive detection method for the quality control of P. notoginseng..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2418 (2017)
Comparison of Reflection and Diffuse Transmission for Detecting Solid Soluble Contents and Ratio of Sugar and Acid in Apples by On-Line Vis/NIR Spectroscopy
LIU Yan-de, WU Ming-ming, LI Yi-fan, SUN Xu-dong, and HAO Yong
The soluble solid contents (SSC) and ratio of sugar and acid are main indices for evaluating the quality of apples. Comparison between diffuse mode and transmittance mode was explored for determination of SSC and ratio of sugar and acid using online detection equipment. 180 samples of watercore and Fuji apples were divThe soluble solid contents (SSC) and ratio of sugar and acid are main indices for evaluating the quality of apples. Comparison between diffuse mode and transmittance mode was explored for determination of SSC and ratio of sugar and acid using online detection equipment. 180 samples of watercore and Fuji apples were divided into the calibration and prediction sets (136∶44) for developing calibration models and assessing the performance of the models. The visible and near infrared (NIR) spectra of watercore and Fuji apples were collected at the speed of 5 samples per second. The partial least square regression models were developed with the spectra preprocessed with multiplicative scatter correction (MSC), standard normal variate transformation (SNV), and baseline correction (BC). 44 new samples were used to evaluate the predictive abilities of the models. By comparison, the transmittance mode was superior to diffuse model. Because the transmittance mode could restrain stray light more effectively. The prediction correlation coefficients (Rp) of the model of soluble solid contents (SSC) was 0.936 and prediction (RMSEP) of the root mean square errors was 0.476°Brix；The prediction correlation coefficients (Rp) of the model of ratio of sugar and acid was 0.785 and prediction (RMSEP) of the root mean square errors was 10.94；The results showed that online detection of soluble solid contents and ratio of sugar and acid of apples based on Vis/NIR diffuse transmit-tance spectroscopy was feasible. The research can provide technical support and reference basis for grading of mass fruits quality..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2424 (2017)
Progress in Laser Induced Breakdown Spectroscopy and Raman Spectroscopy for Hazardous Material Detection
WANG Qian-qian, ZHAO Yu, LU Xiao-gang, PENG Zhong, and LIU Li
In recent years, terrorist attacks utilizing explosives and public safety incidents related to chemical and biological hazards have caused a large number of casualties and property losses. Thus, it is urgent to develop techniques for these hazardous materials detection. Laser-induced breakdown spectroscopy (LIBS) is a In recent years, terrorist attacks utilizing explosives and public safety incidents related to chemical and biological hazards have caused a large number of casualties and property losses. Thus, it is urgent to develop techniques for these hazardous materials detection. Laser-induced breakdown spectroscopy (LIBS) is a spectroscopic analysis technique which uses the light emitted from a laser-induced plasma to determine the composition of the sample based on plasma emission intensities. Raman spectrum can reflect the molecular characteristics of the materials to be measured, and it is widely used in the substances detection and identification. As laser-based spectroscopies, LIBS and Raman spectroscopy are the only currently viable techniques that can be utilized to sense trace amounts of hazardous materials such as explosives and chemical/biological agents at standoff distances because of their intrinsic capability for minimally destructive, in-situ and standoff detection. Therefore, they have gained considerable attention recently. The recent research progresses in hazards detection based on LIBS and Raman spectroscopy are reviewed in this paper. The advantages of LIBS include strong signal intensity, real-time, and the high sensitivity of detection. However, LIBS is subject to poor reproducibility and undesirable matrix effects and hard to discrimate between organic dangerous substances and interferents with the same elements and different molecular structure. Unlike LIBS which provides information on the relative elemental content of molecules within the laser plasma, Raman scattering measures the molecular vibration frequencies and offers the information on the molecular composition of the sample and is suitable for distinguishing organic hazards from organic interferents. One drawback with Raman spectroscopy is the weakness of signal intensity, which makes it sensitive to ambient light and fluorescence. Therefore, integrating LIBS with Raman spectroscopy can provide complementary information and it has the potential to become a useful analytical tool for hazardous materials detection. We emphasize the development of fused LIBS-Raman sensor system for standoff explosive detection in this review. However, combined analysis systems with LIBS and Raman spectroscopy have their own problems such as high cost, complicate structure and data processing, and so on. Further studies on the improvement of detectability of LIBS-Raman combined system for trace hazard detection, the exploitation of strategies for reducing the spectral variability and fusing the data of LIBS and Raman spectroscopy, and the robustness under changing ambient environment conditions need to be further developed. This review compares currently used LIBS, Raman and LIBS-Raman combined techniques for hazardous materials standoff detection. Some prospects of the development of LIBS and Raman spectroscopy for hazards detection are also discussed at the end of the review..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2430 (2017)
Study on Raman Spectrum Characteristics of Pyrite in the Xishimen Gold Deposit in Lingshou, Hebei
GUO Gui-juan, ZHANG De-hui, LI Sheng-rong, XIE Chao, and CUI Yue-ju
The gold-bearing pyrite samples in different production ranges and generations from the Xishimen quartz-vein gold deposit were investigated by micro-Raman spectroscopic measurement. The Raman stretching vibration frequency of two texture type was observed in gold-bearing pyrite: One was the stretching vibration frequenThe gold-bearing pyrite samples in different production ranges and generations from the Xishimen quartz-vein gold deposit were investigated by micro-Raman spectroscopic measurement. The Raman stretching vibration frequency of two texture type was observed in gold-bearing pyrite: One was the stretching vibration frequency of Fe—［S2］2- within 338～343 cm-1; Another was the stretching vibration frequency of Au+—［S2］2- within 374～379 cm-1. Different production ranges and generations of pyrite had different Raman spectra characteristics: All the peaks shift of Au-bearing pyrite had large intensity, big changes and towards low-frequency due to the stretching vibration of Au+—［S2］2-; All the peaks shift of Au-poor pyrite had low intensity, small changes and towards high-frequency due to the stretching vibration of Fe—［S2］2-; The study showed that the main reason of the changes of the Raman spectral was gold-bearing, so the Raman spectral characteristics of gold-bearing pyrites can be used to evaluate gold-bearing properties and geological environment of gold deposits..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2435 (2017)
Raman Spectra Combined with PSO-LSSVM Algorithm for Detecting the Components in Ternary Blended Edible Oil
ZHANG Yan-jun, HE Bao-dan, FU Xing-hu, XU Jin-rui, and ZHOU Kun-peng
The paper presents a method which combines the Raman spectrum and the least square support vector machine (LSSVM) based on particle swarm optimization (PSO) to detect the content of three components of edible blend oil rapidly and quantitatively. In this paper, three components of edible oil were investigated. The charThe paper presents a method which combines the Raman spectrum and the least square support vector machine (LSSVM) based on particle swarm optimization (PSO) to detect the content of three components of edible blend oil rapidly and quantitatively. In this paper, three components of edible oil were investigated. The characteristic peak intensity of Raman spectra was extracted by four pretreatments of the spectra. Then in the training samples, the characteristic peak intensity and the percentage of mixed oil samples were used as the input values and the output values of the regression analysis model. The mathematical models of LSSVM and PSO-LSSVM were established after different pretreatments. The predictive ability of the model was analyzed by the correlation coefficient and mean square error in the test samples. The traditional LSSVM algorithm for nonlinear modeling has many issues, such as its kernel parameter σ and the regularization parameter γ have great influences on the learning model and generalization ability. The fitting precision and generalization ability of the model are dependent on its related parameters, and the time consuming is too long while the optimal step size is too little; however, the global optimal values are hardly to get while the optimization step size is large. Yet, the PSO-LSSVM algorithm has the PSO algorithm advantages of fast convergence and global search capability, which can overcome the problems of time consuming and blindness in LSSVM algorithm. So the kernel parameters σ and γ of LSSVM algorithm are optimized by Global optimization ability and fast convergence characteristics of PSO algorithm. In the quantitative analysis of the three components of edible blend oil, the validation set correlation coefficients of the model for soybean oil, peanut oil and sunflower kernel oil were 0.967 7, 0.997 2 and 0.995 3, respectively; in addition, the mean square errors were 0.054 9, 0.009 2 and 0.047 1, respectively. Compared with the LSSVM algorithm, the prediction accuracy of PSO-LSSVM model is higher and the convergence rate is faster which has been verified by the experiments. Thus, the method can detect the content of the three components of edible oil accurately..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2440 (2017)
The Constraints on the Method of Using Cryogenic Raman Spectroscopy to Determine the Salinities of Fluid Inclusions
CHEN Xiao-lan, ZHOU Zhen-zhu, HAN Zuo-zhen, and LIN Yu-xiang
Knowledge of the salinity of fluid inclusions, including the type of salts and their amounts, is of great importance for the interpretation of geological fluids and their role in rockforming processes like diagenesis, metamorphism, and hydrothermal processes. One of the most vital binary fluid systems for understandingKnowledge of the salinity of fluid inclusions, including the type of salts and their amounts, is of great importance for the interpretation of geological fluids and their role in rockforming processes like diagenesis, metamorphism, and hydrothermal processes. One of the most vital binary fluid systems for understanding geological processes is the NaCl-H2O system. The salinity of aqueous solutions in fluid inclusions is commonly determined with microthermometry. Moreover, the cryogenic Raman spectra of hydrates of chloride salts in fluid inclusions can be not only used to calculate salinities, but also used to distinguish different brine types. Theoretically, the salinity of one fluid inclusion can’t be calculated via the Raman spectrum in a single point because of the heterogeneity of the fluid inclusion at low temperature and the location of focus range of the laser beam. In order to have a better understanding of the characteristics of phase change of fluid inclusions at low temperature and reveal their Raman spectra responses to salinities, this paper studied the crystallization process and Raman spectroscopy of ice and hydrohalite in NaCl solutions with 5 different salinities. The result shows that in the process of freezing and heating, the crystallization of hydrohalite occurs from an interstitial, hypersaline liquid among the prior formed ice crystals. The forming of hydrohalite may depend on the concentration of brine. The relative intensities of p1 ［(3 402±1) cm-1］ and p2 ［(3 419±1) cm-1］, which are the two of four characteristic Raman peaks, are very stable, while the variation of the relative intensities of the other two peaks p3 ［(3 432±2) cm-1］ and p4 ［(3 535±4) cm-1］ increase with the salinity increasing because of different relative crystal orientations of hydrohalite compared to the polarized laser beam. Therefore, the characteristic ratios of Raman peaks at different points in the same sample are usually variable, and the traditional method of calculating salinities of the fluid inclusion using cryogenic Raman spectrum at one single point makes a big error. Based on large data statistics and analysis, the results indicate that the statistical average value of characteristic Raman peaks maybe reflects the salinity of the fluid inclusion better for the first time. With respect to the relative intensity and the width at half height of the characteristic Raman peaks, the total peaks’ area shows the best linear dependence on the salinity, which is the first choice for the calculation of the salinity of brine. The results of this study expounds the suitable experimental operation and data analysis methods of the salinity calculation of brine using cryogenic Raman spectroscopy, and illustrates the applied conditions of this method in fluid inclusions analysis. Although it’s a complex operation process to calculate salinity using cryogenic Raman spectra, this method is very important because of its anti-interference, large applied range and reliability..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2446 (2017)
The Effect of Clove on the Variation of Fluorescence Characteristic during Low Density Lipoprotein Oxidation
ZENG Jun-jie, JIANG Shen-hua, FENG Hua, and SU Guo-xing
Oxidation of LDL has been regarded as the key factor which leads to AS, the fluorescent characteristic of LDL developed a series of changes during LDL oxidation. The traditional and three-dimensional flourescence contour spectroscopy were used to evaluate the inhibition effects of clove against the changes of fluoresceOxidation of LDL has been regarded as the key factor which leads to AS, the fluorescent characteristic of LDL developed a series of changes during LDL oxidation. The traditional and three-dimensional flourescence contour spectroscopy were used to evaluate the inhibition effects of clove against the changes of fluorescent characteristic of LDL in the process of oxidation in this paper. The results indicated as follows: the optimal measurement time point of LDL incubation for fluorescence was 48 h; fluorescence of Trp quenching, fluorescent chromophore redshift, Lys residues contained in apoB-100 being modified by reactive aldehydes generated during oxidation, the generation of fluorescent materials and lipofuscins and the variation of three-dimensional fluorescence were significantly inhibited, respectively, and the inhibition effects were positively related with concentrations of clove crude extracts. Moreover, in this experiment it was found that the different polarity components of clove (n-hexane fraction (clove essential oil), ethyl acetate fraction, n-butyl alcohol fraction and water fraction) possessed different activities on influencing the changes of fluorescent characteristic of LDL during LDL oxidation. Among these fractions, n-hexane fraction possessed the strongest activities against Trp fluorescence quenching, fluorescent chromophore redshift and the variation of three-dimensional fluorescence. However, the inhibition efficiencies of ethyl acetate fraction were the highest against the generation of fluorescent materials and lipofuscins, Lys residues being modified by reactive aldehydes. The results suggest that clove has the preferable inhibitory action on the variation of fluorescence characteristic during LDL oxidation, and the main components of inhibition focus on the essential oil and ethyl acetate fraction. This research provides a reference on further components analysis, research and development of functional foods of clove..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2452 (2017)
Analysis of Leucine and Isoleucine for Low-Frequency Collective Absorption Spectrum Using Terahertz Time-Domain Spectroscopy
HUANG Li-juan, ZHANG Xin, WANG Guo, and ZHANG Zhuo-yong
Terahertz (THz, 1=1012 Hz) wave refers to the frequency in the 0.1~10 THz spectra of electromagnetic radiation. THz time domain spectroscopy (THz-TDS) can provide the structure information of the material and configuration to distinguish different amino acid isomers, and amino acid isomers detection is useful for the qTerahertz (THz, 1=1012 Hz) wave refers to the frequency in the 0.1~10 THz spectra of electromagnetic radiation. THz time domain spectroscopy (THz-TDS) can provide the structure information of the material and configuration to distinguish different amino acid isomers, and amino acid isomers detection is useful for the quality control of the food and pharmaceutical potency. Leucine and isoleucine are homologous isomers. They have very similar molecular structures, but different chemical and physical properties. Biological macromolecular terahertz absorption is related with intermolecular hydrogen bond vibration and rotational level about the dipole transition, and it can be used for fingerprint identification of molecular dipole transition. In this paper, the terahertz time-domain spectroscopy (THz-TDS) and Fourier transform infrared spectroscopy (FTIR) were used to measure the absorption spectroscopy of leucine and isoleucine at room temperature. A number of different well-resolved THz absorption peaks for the two components were observed, but their infrared absorption peaks were almost overlapped. In parallel with the experiment, the computed vibrational spectra was also obtained by using first principles calculations based on the density functional theory (DFT). The theoretical results fit well with the experimental results..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2462 (2017)
The Characteristics of Particulate and Dissolved Organic Matter of Sewage Treatment Plant Effluent Water by Infrared and Fluorescence Spectroscopy
YU Min-da, HE Xiao-song, TAN Wen-bing, XI Bei-dou, ZHANG Hui, MA Li-na, ZHANG Yuan, ANG Qiu-ling, and GAO Ru-tai
The effluents from municipal wastewater treatment plant are believed to be a main water source of reclaimed water. However, the composition of organic matter in the effluents is unclear, which places a potential risk on the receiving waters body. Therefore, it is important to obtain the information on the composition aThe effluents from municipal wastewater treatment plant are believed to be a main water source of reclaimed water. However, the composition of organic matter in the effluents is unclear, which places a potential risk on the receiving waters body. Therefore, it is important to obtain the information on the composition and structure of organic matter in sewage plant, which will facilitate to improve the sewage treatment plants and to establishment the emission standard of harmful substances in wastewater effluent. Fourier transform infrared spectroscopy (FTIR) and three dimensional fluorescence excitation-emission matrix spectroscopy (EEM) were combined with second derivative infrared and fluorescence regional integration analysis to identify the composition and structure of particulate organic matter (POM) and dissolved organic matter (DOM) isolated from four sewage effluents (W1, W2, W3, and W4). The results showed that, POM in the effluents mainly consisted of aliphatic, aromatic, alkanes, carbohydrate and mineral salts, while DOM was primarily composed of carbohydrate, organic acid, proteins, peptides and hydrocarbons. As to POM in the effluents from the four sewage treatment plants, the sewage treatment plant W1 had higher aromatic substances and lower mineral salts; the sewage plant W2 had a higher carbohydrate content compared with the sewage plant W1; the sewage plant W3 had a higher aliphatic, protein and carbohydrate; and the sewage plant W4 was mainly composed of carboxylic acids and aromatic substances. As to DOM, W1 and W2 had a similar composition. The DOM in W1 and W2 comprised mainly the aromatic organic acid with high macromolecular, which accounts for 73.9% and 67.7% of the total DOM. However, W3 and W4 consisted mainly of proteins, peptides, carbohydrate and protein-like substances, which was responsible for 71.3% and 53.5% of the DOM. The results demonstrated that, FTIR spectroscopy coupled with second derivative analysis could be used to identify the main composition and structure differences between POM and DOM. EEM spectra combined with fluorescence regional integration can be applied to further quantitatively distinguish the composition differences of different effluent wastewater..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2467 (2017)
Study on Interaction between Coomassie Brilliant Blue G-250 and Bovine Serum Albumin by Fluorescence Spectroscopy and Molecular Modeling
WANG Yong-gang, YANG Guang-rui, MA Xue-qing, LENG Fei-fan, MA Jian-zhong, and WANG Xiao-li
The interaction of coomassie brilliant blue G-250 (CBBG-250) with bovine serum albumin (BSA) was investigated by the methods of fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD). Fluorescence data showed that the quenching of BSA by CBBG-250 was result of forming theThe interaction of coomassie brilliant blue G-250 (CBBG-250) with bovine serum albumin (BSA) was investigated by the methods of fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD). Fluorescence data showed that the quenching of BSA by CBBG-250 was result of forming the complex of BSA-CBBG-250, and CBBG-250 effectively quenched the intrinsic fluorescence of BSA via static quenching. According to Stern-Volmer equation, the binding parameters between CBBG-250 and BSA were determined. The enthalpy change (ΔH) and entropy change (ΔS) were calculated to be -4.38 kJ·mol-1 and -6.16 J·mol-1·K-1, indicating that the hydrogen bonds and hydrophobic interactions played a dominant role in the binding. The conformational investigation revealed the α-helical structure was decreased and the polypeptides of BSA were slightly folded with the addition of CBBG-250 by synchronous fluorescence. Fourier infrared spectrum showed that the peak position of amide band Ⅰ (1 600～1 700 cm-1) and amide band Ⅱ (1 600～1 500 cm-1) of the BSA characteristic absorbing peaks was blueshifted. The amide band I moved from 1 650 to 1 710 cm-1, and amide band Ⅱ moved from 1 573 to 1 544 cm-1, which indicated the structure of alpha helix features (1 650～1 658 cm-1) and beta-fold (1 620～1 640 cm-1 and 1 645 cm-1) had changed. The content of α-helical structure decreased from 42.15% to 1.27% by circular dichroism. The main reasons were the microenvironment polarity of tryptophan changed with the addition of CBBG-250 increased, two interaction between BSA and CBBG-250 including the hydrogen bonding and van der Waals force occurred, and then the secondary structure of BSA was changed, which was confirmed by Molecular modeling..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2474 (2017)
Ultraviolet-Initiated Template Polymerization of Cationic Polyacrylamide and Its Sludge Dewatering Performance
ZHANG Zheng-an, ZHENG Huai-li, HUANG Fei, FU Mao-mei, LI Xiang, and ZHOU Yu-hao
Cationic polyacrylamide (CPAM), is often used asflocculantin water treatment and sludge dewatering. CPAM prepared with traditional methods can’t react completelydue to the randomly-scattering cationic units in its molecules, resulting in its flocculation efficiency decline. So this study tried to use a novel method to Cationic polyacrylamide (CPAM), is often used asflocculantin water treatment and sludge dewatering. CPAM prepared with traditional methods can’t react completelydue to the randomly-scattering cationic units in its molecules, resulting in its flocculation efficiency decline. So this study tried to use a novel method to prepare CPAM, i. e., acrylamide (AM) and diallyldimethylammonium chloride (DMDAAC) selected as monomers and poly sodium polyacrylate (PAAS) with two different molecular weights selected as the template, the template polymers (TPDA1 and TPDA2) were polymerized with ultraviolet (UV)-initiated template polymerization. The common polymer (NTPDA) of AM and DMDAAC was also polymerized through UV -initiated synthesis for comparison. All polymers were characterized with Fourier transform infrared (FTIR) spectroscopy, 1H nuclear magnetic resonance (1H NMR) spectroscopy and scanning electron microscopy (SEM), and used to sludge dewatering experiment. The spectrum analysis revealed that the template addition improved the reactivity ratio of DMD, as a result, the micro-block structure with DMDAAC continuous distribution were generated in polymer molecules, which improved the flocculation performance of polymer, especially charge neutralization; the SEMresult showed TPDA1 and TPDA2 both had a higher specific surface area and fractal dimension than NTPDA； the sludge dewatering experiment proved template polymers possessed preferable dewaterability and more permissive pH condition for application; In the optimal conditions of TPDA1 dose of 50.0 mg·L-1 and wastewater of pH 8, the sludge moisture content dropped to the lowest level of 72.5%. The molecular weight of template also had influence on polymer properties, and the template with smaller molecular weight had preferable dewaterability..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2480 (2017)
Research and Application of Linear Mixing Model of Two-Component Mixed Edible Oil
XU Hong, MING Dong, LI Ying-xin, QI Hong-zhi, SUN Mei-xiu, and YANG Ji-chun
A linear mixing model of the two-component mixed edible oil was proposed based on the assumption that the absorption coefficient of the two-component mixed edible oil can be obtained by the linear combination of absorption coefficients of two raw oils according to the mixing proportion. Based on the Lambert-Beer’s Law,A linear mixing model of the two-component mixed edible oil was proposed based on the assumption that the absorption coefficient of the two-component mixed edible oil can be obtained by the linear combination of absorption coefficients of two raw oils according to the mixing proportion. Based on the Lambert-Beer’s Law, a series of absorption equations of the incident light was constructed to describe variations of light intensity after the same source light respectively passing through the two raw oils and their proportional mixture with the same thickness. As a result, a formula was derived to calculate the mixing proportion of the two-component mixed edible oil, which was a new method to quantitatively analyze the proportion of adulterated edible oil. According to the theory of errors, the calculation difference of mixing proportion to the actual value was analyzed by the total differential methods, and the result demonstrated that there was an optimal wavelength where the products of the absorption light intensity of two raw oils and the difference value between their absorbance were larger, and less calculation difference could be obtained. A VIS/NIR spectral detection system was assembled and used to validate the mixing proportions of corn oil adulterated in peanut oil, soybean oil adulterated in peanut oil and soybean oil adulterated in corn oil. The results showed that the principle of choosing the optimal testing wavelength was correct, and the relative errors between calculation values and actual values were less than 5% for adulterating proportions above 10%(v/v), as well as the correlation coefficients were 0.999 4, 0.999 7 and 0.999 3 with RMS errors of 0.006 9, 0.005 1 and 0.007 6. The results proved that the proposed linear mixing model was practicable. The comparative experiments, which were operated on the stacked series of two separate oil samples with same mixing proportions, also verified the correctness of the linear mixing model and the method for choosing the testing wavelength. In addition, these comparative experiments revealed that the parallelism of light source and verticality of oil vessels were important to the detection accuracy of mixing proportion. This paper introduces a new method of detecting the mixing proportion of two-component mixed edible oil which differs from the traditional method of spectroscopy combined with chemometrics. In this method, the mixing proportion of two-component mixed edible oil can be precisely computed only after three times data collection of absorption spectra of the two raw oils and their mixture..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2486 (2017)
A New Multivariate Classification and Identification Method of Spectroscopy
WU Yan-xian, SONG Chun-feng, YUAN Hong-fu, ZHAO Zhong, TIAN Ling-ling, YAN Yu-jiang, TIAN Wen-liang, and WANG Li
In the SIMCA, the parameters of PCA model and F test are used to construct T2 and Q for classification, and Euclidean distance is used to determine the range of sample distribution of the model. Since the range which is defined by Euclidean distance is a circle in the plane of T2 vs Q, the boundary of actual samples whIn the SIMCA, the parameters of PCA model and F test are used to construct T2 and Q for classification, and Euclidean distance is used to determine the range of sample distribution of the model. Since the range which is defined by Euclidean distance is a circle in the plane of T2 vs Q, the boundary of actual samples which distributes in some directions and irregular space cannot be presented accurately. Besides, SIMCA is still inaccurate for classification and identification in theory. Therefore, a new multivariate classification and identification method was proposed using Mahalanobis Distance instead of Euclidean distance in this paper. Experiments of infrared spectra of blending edible oils and near infrared spectra of animal furs were designed to compare the performance of the new method and SIMCA. The recognition rates of the new method and SIMCA for three kinds of furs are 85.5% and 75%, respectively. The recognition rates of the new method and SIMCA for two classes of blending edible oils are 65% and 55%, respectively. It has shown that the new method is superior to SIMCA in the performance of discriminating the different materials with a small difference in their chemical composition..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2493 (2017)
Multi Spectral True Temperature Inversion Algorithm Based on Emissivity Deviation Constraints
GU Wei-hong, MA Zhao, XING Jian, LI Ming, and SONG Wen-long
Multispectral thermometry inversion based on the continuous temperature measurement algorithm has attracted more and more attentions because there is no prior assumption of emissivity models, but needs to set the appropriate initial temperature and emissivity range and the iteration time is longer, and not suitable forMultispectral thermometry inversion based on the continuous temperature measurement algorithm has attracted more and more attentions because there is no prior assumption of emissivity models, but needs to set the appropriate initial temperature and emissivity range and the iteration time is longer, and not suitable for on-line measurement. An improved continuous temperature method searching emissivity deviation was proposed for fast true temperature inversion. The problem of searching the emissivity in the continuous temperature measurement method was changed to search the emissivity deviation, and the function relationship between the deviation of each iteration result and the deviation of the iteration stop condition and the error of emissivity was fitted. Through this function relationship, the emissivity deviation was determined by each iteration result, which could quickly reduce the search range of the emissivity, and improve the efficiency of the calculation. Simulation results for 4 kinds of spectral emissivity models showed that the new algorithm did not need to set the initial temperature range. compared with the continuous measurement method, the computational efficiency was improved by more than 60% in the premise of ensuring the accuracy of inversion..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2500 (2017)
Spectral Study on the Interaction between Cytochrome c and ProliNONOate
TANG Qian, GONG Ting-ting, SHI Shan-shan, CAO Hong-yu, WANG Li-hao, YU Yong, SHAN Ya-ming, and ZHENG Xue-fang
It played an important role in the detection of mitochondrial apoptosis that the interaction of Cytochrome(Cyt c) with NO, thus the research is still a hotspot issue for the chemists and biologists. In this paper, Ultraviolet (UV-Vis) absorbance spectra, UV-Vis time course spectra, circular dichroism (CD), synchronous It played an important role in the detection of mitochondrial apoptosis that the interaction of Cytochrome(Cyt c) with NO, thus the research is still a hotspot issue for the chemists and biologists. In this paper, Ultraviolet (UV-Vis) absorbance spectra, UV-Vis time course spectra, circular dichroism (CD), synchronous fluorescence spectra and electron paramagnetic resonance (EPR) technology were used to research the coordination reaction mechanism of different valence states Cyt c with proliNO/NO and its spatial conformation changes. The results showed that Cyt c could directly react with NO without other reagents. And its secondary structure would change during the experiment. It has been established that the electronic configurations of iron ions in porphyrin complexes are controlled in the nature by a number of axial ligands, peripheral substituents attached to the porphyrin macrocycle, deformation of the porphyrin ring and solvent effects. During the experiment, proliNO/NO was added to the sample of Cyt c, and NO gas would generate, then entered into the solution, finally the distal methionine heme ligand was displaced, Cyt c could bind NO, that is, the Fe—S broke down, and the Fe-N formed. At the same time, generating a new cytochrome c-NO (Cyt c-NO) complex. Cyt c-NO binary complexes were instability and would dissociate, and dissociation process of Cyt c-NO binary complexes was belonging to a first-order reaction with the dissociation rate of (0.071 1±0.039 6) s-1. The secondary structure of Cyt c was affected by proliNO/NO concentration. When the concentrate of proliNO/NO was below to 8.6×10-4 mol·L-1, the peak changes of 222 nm and 208 nm was very weak, and the α-helix increased from 33.1% to 44.1%. And it continued to increase, the secondary structure of Cyt c took place a great change. The tiny changes illustrated that a new compound generated, but excessive proliNO/NO can break the structure of Cyt c. Taken together, we have demonstrated that an understanding of the interaction mechanism of NO with cytc, and the reaction mechanism of NO with ferri- and ferro-cytochrome c have important implications for the inhibition of mitochondrial oxygen consumption by NO and the mitochondrial metabolism of NO..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2505 (2017)
Detection of Internal Quality in Fresh Jujube Based on Moisture Compensation and Visible/Near Infrared Spectra
SUN Hai-xia, XUE Jian-xin, ZHANG Shu-juan, LIU Jiang-long, and ZHAO Xu-ting
In order to establish a stable and reliable detection model to identify the quality of fresh jujube, the visible/near-infrared reflection spectroscopy techniques and the method of moisture compensation were used to detect the internal quality of fresh jujube. Moisture content (MC), soluble solid content (SSC), firmnessIn order to establish a stable and reliable detection model to identify the quality of fresh jujube, the visible/near-infrared reflection spectroscopy techniques and the method of moisture compensation were used to detect the internal quality of fresh jujube. Moisture content (MC), soluble solid content (SSC), firmness, soluble protein content (PC) and vitamin C content (VC)were used as internal quality index of Huping Jujube, regression coefficient (RC) was applied to select effective wavelengths and least squares-support vector machines (LS-SVM) models were built based on the effective wavelengths, respectively. The results of the five RC-LS-SVM models were obtained with the determination coefficient of every prediction (R2P) of MC, SSC, PC, VC, firmness as 0.859 5, 0.884 0, 0.867 1, 0.909 9 and 0.826 1, respectively. The root mean square error of prediction (RMSEP) of MC, SSC, PC, VC, firmness were 1.243 1, 1.005 3, 3.324 9, 0.479 8 and 0.056 7, respectively. Then, wavelengths overlapped with or closed to characteristic wavelengths of moisture content were removed from characteristic wavelengths of SSC, PC, VC and firmness, respectively. Characteristic wavelengths of moisture content were composed of distinct moisture absorption peak on fresh jujube(960, 1 200, 1 400, 1 780 and 1 900 nm)and characteristic wavelengths selected by RC of PLSR model of moisture content. Characteristic wavelengths after the moisture compensation of each index (SSC, PC, VC, firmness) was used to carry out data fusion with moisture content of fresh jujube, moisture compensation LS-SVM model of each index (SSC, PC, VC, firmness) was built based on fused data, respectively. The results indicated that the model’s accuracy of firmness was improved after moisture compensation, Ｒ２P and RMSEP were 0.830 5 and 0.055 3, respectively. The results also revealed that the model accuracy of SSC, VC and PC were reduced respectively after moisture compensation, R2P were 0.804 1, 0.878 2 and 0.837 8, respectively and RMSEP were 1.347 3, 0.638 0 and 3.503 2 respectively. Finally, the correlation relationship between the quality indexes was analyzed. The results indicated that an significant correlation relationship was revealed between moisture content and firmness in the 0.05 level, an extremely significant correlation relationship was revealed between moisture content and any of the other three indexes (SSC, PC, VC) in the 0.01 level. This research shows that prediction model based on the method of moisture compensation can be effective to realize evaluation of the internal comprehensive quality on Fresh Jujube. What’s more, there is an interaction between moisture content and any of the other four indexes. In fact, prediction models based on the other quality indexes are affected by moisture content. This research provides a new method for the decoupling of interaction between the various internal quality indexes in the spectroscopy detection..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2513 (2017)
Non-Destructive Pigment Identification Method of Ancient Murals Based on Visible Spectrum
LIANG Jin-xing, and WAN Xiao-xia
Mineral pigments is the color rendering basic of ancient murals, the visible spectrum of mineral pigment reflects its chemical composition and physical properties. Different mineral pigments have different spectral shapes because of different absorb properties for visible spectrum, even the same mineral pigment often sMineral pigments is the color rendering basic of ancient murals, the visible spectrum of mineral pigment reflects its chemical composition and physical properties. Different mineral pigments have different spectral shapes because of different absorb properties for visible spectrum, even the same mineral pigment often shows different spectral amplitudes as it is grinded to different levels of particle size. According to the spectral features of mineral pigments above, a non-destructive pigment identification method of ancient murals based on visible spectrum is proposed. The normalized spectral curve, first derivative and second derivative extracted from spectral reflectance are combined to construct the identification feature space and the matching error (ME) calculated by multiply the normalized euclidean distance and angle between spectral feature from wall paintings and reference database is adopted as the criterion for pigment chemical property identification. The function relationship between mean spectral reflectance and mean particle size of the mineral pigments with particle size levels is constructed for pigment particle size identification. The proposed method is validated by the ancient murals in Mogao Grottoes based on the constructed pigment reference database and in-situ non-destructive spectral measurement method. The techniques of using pigments in murals and the differences of pigment used in different dynasties are tentatively analyzed and explained based on the identification results of malachite and lapis lazuli. The authors believe that the proposed method will provide effective support for in-depth studies on ancient murals..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2519 (2017)
The Spectral Characterizations of Chitosan Based Flocculants Synthesized by Photopolymerization
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Since there were a lot of amino, hydroxyl, and N- acetyl reactive functional groups distributed on the chitosan macromolecule chains. The modification of chitosan as natural green flocculants had received more and more attentions, but the graft copolymer product thereof spectroscopic characterizations were rarely reporSince there were a lot of amino, hydroxyl, and N- acetyl reactive functional groups distributed on the chitosan macromolecule chains. The modification of chitosan as natural green flocculants had received more and more attentions, but the graft copolymer product thereof spectroscopic characterizations were rarely reported. Therefore, the spectroscopic characterization and analysis of the chitosan-based flocculants were of great significance. The chitosan based flocculant CS-P(AM-DMDAAC) was synthesized by photopolymerization method using chitosan (CS), acrylamide (AM), and diallyl dimethyl ammonium chloride (DMDAAC) as the monomers of graft copolymerization. X-ray diffraction (XRD), Ultraviolet spectroscopy (UV), and Infrared (IR) spectroscopy were applied to investigate the structural characteristics of CS-P(AM-DMDAAC). The characteristic of spectrum and the attributions of characteristic absorption peaks of CS, AM, DMDAAC, and CS-P(AM-DMDAAC) were analyzed by the X-ray diffraction (XRD), ultraviolet spectroscopy (UV), and infrared spectroscopy (IR). The effects of degree of deacetylation of chitosan, concentration of chitosan, cationic degree of graft copolymer on X-ray diffraction (XRD), Ultraviolet spectroscopy (UV), and Infrared (IR) spectrum of CS-P (AM-DMDAAC) were systematically investigated. Ultraviolet spectroscopy (UV) and Infrared (IR) spectrum demonstrated that AM and DMDMAAC were successfully grafted onto CS to prepare CS-P (AM-DMDAAC). The increase of chitosan concentration led to weakening spectrum symmetry. X-ray diffraction showed that the crystal structure of chitosan was transformed into amorphous structure by the graft copolymerization. Compared with the amorphous structure, the crystal structure was more easily hydrated, so the graft copolymer product had more excellent solubility..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2527 (2017)
The Investigation of Spectral Polarization of Vegetation Canopy Basing on the Field Measurements
WU Di, and SUN Zhong-qiu
For remote sensing of vegetation, light scattered from canopy is partly polarized, which is the basis data for the polarized remote sensing. Thus, it is significant to perform the field polarization measurement of vegetation canopy using the ground-base instrument. The field polarization measurement data not only contaFor remote sensing of vegetation, light scattered from canopy is partly polarized, which is the basis data for the polarized remote sensing. Thus, it is significant to perform the field polarization measurement of vegetation canopy using the ground-base instrument. The field polarization measurement data not only contain the physical polarization property of vegetation canopy, but also can be used to match with the polarimetry measurements from airborne and spaceborne sensors. Several previous studies have paid some attentions to the polarization of vegetation canopies, because of some airborne and spaceborne instruments can be used to obtain multi-angular polarized information. However, the investigation about the field measurements is rare. To study the contribution of this polarized light to multi-angular observations of reflectance over vegetation canopy, a hyperspectral bidirectional polarized reflectance data of one type of vegetation canopy acquired over a wide viewing range in field was analyzed in this paper. Then, it was analyzed with respect to basic physical polarized reflectance mechanisms. The impact of angular data sampling and the variation of the polarized spectral reflectance were also analyzed. Furthermore, we compared the modeled polarization from two current polarimetric models with our measured polarization of vegetation canopy at selected wavelength. Analyses showed that all the models were good fitted to the measurements; there was a very small spectral variability of the polarized reflectance of vegetation canopies. The good agreement between polarization measurements and modeled results confirms the ability of models and the accuracy of field experiments. These results, deepening our understanding of the scattering properties of vegetation canopies, suggest that we can model the polarization accurately by all the current polarimetric models; they are valuable for the development of polarized remote sensing applications on earth science and useful for studying the contribution of earth polarization on the atmosphere polarization..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2533 (2017)
Effect of Different Dust Weight Levels on Unban Canopy Reflectance Spectroscopy
SUN Teng-teng, LIN Wen-peng, LI Ying, GUO Pu-pu, and ZENG Ying
In order to explore the effect of different dust weight on vegetation canopy spectrum, we selected Shanghai Normal university as the study area located in the center of Shanghai and determined the canopy spectral reflectance under different grades of foliar dust including Sophora japonica, Bauhinia, Photinia fraseri, VIn order to explore the effect of different dust weight on vegetation canopy spectrum, we selected Shanghai Normal university as the study area located in the center of Shanghai and determined the canopy spectral reflectance under different grades of foliar dust including Sophora japonica, Bauhinia, Photinia fraseri, Vinca etc using ASD FieldSpec 3. Then we weighed the foliar dust of corresponding species using electronic analytical balance in the laboratory and calculated dust catching of each plant. On this basis, we analyzed the influence of different foliar dust weight on canopy spectral characteristics of plants. After analyzing the different spectral curves, we got some conclusions. The spectral reflectance of plant canopy between 710～1 350 nm reduced as the foliar dust increasing and the difference among the three curves was large. The different dust weight impacting on the reflectance spectrum of vegetation was more complicated in 350～710 and 1 450～1 750 nm. The difference between the three curves was small in 350～710 and 1 450～1 750 nm bands but the ratio of difference was not small. The influence of foliar dust on canopy spectral of plants was not only related with the weight of dust but also related with species of plants. In the vicinity of the “green peak” and “red edge”, the slope of the plants reduced with the increasing of the amount of dust. The sensitivity of the spectral curves of different spieces or different wavelengths of the same plant to the dust was different. The foliar dust did not led to the phenomenon of red edge displacement, but it weakened the “twin peaks” phenomenon of the first derivative of red edge. The difference between “peak” and “secondary peak” reduced as the dust weight increasing and red edge was located in 719 nm. Finding the relationship between foliar dust or different dust weight and vegetation canopy spectrum will be of great significance for hyperspectral remote sensing application in this field..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2539 (2017)
Study on Nondestructive Detection with Net for Intact Hosui Pear by Online Spectroscopy
LIU Yan-de, WU Ming-ming, SUN Xu-dong, ZHU Dan-ning, HAN Ru-bing, CHENG Meng-jie, YE Ling-yu, and YE Shuang-hui
Subsurface damage and soluble solid content (SSC) are important indexes for evaluating the quality of hosui pear. The feasibility was discussed for nondestructive detecting with net for SSC of intact hosui pear by online visible-near infrared (visible-NIR) transmittance spectroscopy. Ten tungsten halogen lamps were insSubsurface damage and soluble solid content (SSC) are important indexes for evaluating the quality of hosui pear. The feasibility was discussed for nondestructive detecting with net for SSC of intact hosui pear by online visible-near infrared (visible-NIR) transmittance spectroscopy. Ten tungsten halogen lamps were installed in a sorting line. The total power of lamp was 1 000 watt. The spectra were recorded with the integration time of 80 ms in the wavelength range of 600~900 nm when the samples were conveyed at the speed of five samples per second. The light sources were illuminated from both sides of the production line, and the detector received light from the bottom of the fruit cup. The spectrum of each sample was recorded automatically by use of the hardware trigger mode. The index plate and driving gear were mounted on the same shaft. The location of the index plate's tooth was matched with the location of the fruit cup. Hall sensor was placed at a height of 2 mm above the tooth of the index plate. When the index plate turned one tooth, a Hall sensor sent a 3.5 V high frequency signal to trigger spectrometer to save one spectrum. The response properties of visible-NIR spectra for normal pears and pears with net were analyzed. The effective information of the spectra of pears with net was reduced, and the new method of polynomial fitting was used to eliminate this problem. The influence of pears with net on SSC determination was also explored by partial least square (PLS) regression models, and PLS model was employed with normal pears and pears with net. The robust model was developed by the spectra which eliminates the influence of net by binomial fitting. Therefore, a new strategy was proposed for detection of SSC of intact pears by online visible-NIR transmittance spectroscopy. The new samples, which were not used in the calibration, were used to access the abilities of predicting SSC of intact pears. The accuracy of sorting grade was 94.4% according to the SSC values and the SEP was 0.328°Brix of predicting SSC. The results showed that nondestructive detecting with net for SSC of intact hosui pear was feasible by visible-NIR transmittance spectroscopy. The research can provide technical support and reference basis for grading of mass fruits quality..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2546 (2017)
Nondestructive Detecting Rottenness Defect of Citrus By Using Hyper-Spectra Imaging Technology
CHU Bing-quan, ZHANG Hai-liang, LUO Wei, and HE Yong
Rottenness is a prevalent and devastating disease that threats citrus fruit. Automatic detection of rottenness can enhance the competitiveness and profitability of the citrus industry. In this study, hyper-spectral image technology was used nondestructively to detect citrus rottenness. Spectral curve in defects peel reRottenness is a prevalent and devastating disease that threats citrus fruit. Automatic detection of rottenness can enhance the competitiveness and profitability of the citrus industry. In this study, hyper-spectral image technology was used nondestructively to detect citrus rottenness. Spectral curve in defects peel region of interest was analyzed and combined with principal component analysis to extract the four best bands. Principal component was used based on four best bands: 615 nm and 680 nm, 710 nm and 725 nm peaks combination respectively and ultimately selected component (PC-2) as image classification and recognition obtained from the 615 nm and 680 nm principal component analysis and identification rate was 100% with a simple threshold segmentation. These results showed that using hyper-spectral as a kind of detection methods could be used for the evaluation of citrus rotteness recognition..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2551 (2017)
Study on the Quality Classification of Sausage with Hyperspectral Infrared Band
GONG Ai-ping, WANG Qi, and SHAO Yong-ni
Hyperspectral image is a kind of rapid and nondestructive analysis technology widely used in the food industry. Chinese sausage has a long history, which is a very ancient carnivorous food production and preservation technology. According to the physicochemical characteristics of sausage, Chinese commercial industry stHyperspectral image is a kind of rapid and nondestructive analysis technology widely used in the food industry. Chinese sausage has a long history, which is a very ancient carnivorous food production and preservation technology. According to the physicochemical characteristics of sausage, Chinese commercial industry standard divided sausage into top-class, first-class and second-class. The near infrared (NIR) hyperspectral band information of sausage applied the successive projection algorithm (SPA) to extract the characteristic bands, and then respectively established grading model of PLSR (all band) and SPA-MLR (characteristic band). The decision coefficient of the SPA-MLR model based on the characteristic wavelength was 0.929, and the correct rate was 100%. The results showed that the near infrared spectral information of hyperspectral image could be used for fast and nondestructive analysis of sausage..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2556 (2017)
Effect of Plasma Density on Discharge Produced Plasma Extreme Ultraviolet Source
XU Qiang, ZHAO Yong-peng, WANG Qi, and YANG Yong-tao
Condition of the plasma is one of the key factors affecting the power and the conversion efficiency of the expreme ultraviolet(EUV) source. The effects of the Xe flow rate on spectra and plasma for discharge produced plasma extreme ultraviolet source were investigated theoretically and experimentally, which was importaCondition of the plasma is one of the key factors affecting the power and the conversion efficiency of the expreme ultraviolet(EUV) source. The effects of the Xe flow rate on spectra and plasma for discharge produced plasma extreme ultraviolet source were investigated theoretically and experimentally, which was important to optimize the running condition of the EUV source. Moreover, the relationship between the distributions of abundances of ions and electron temperature as well as the density under non-local thermodynamic equilibrium were simulated with the Collisional-Radiation model. The variation tendency of the intensity for Xe8+~Xe11+ 4d—5p transitions on electron temperature was derived. The spectra detected by the rowland spectrometer was detected and analyzed under different density of the plasma with the capillary discharge produced plasma technology. Meanwhile, the effect of Xe gas flow rate on the condition of the plasma was studied as well. The experiments and theory showed that, during the Z-pinch process, the temperature decreased when the flow rate of Xe was increasing. And the average electron temperature was approximated to 29 eV when the current was 28 kA and the flow rate of Xe was 0.4 sccm. Meanwhile, the optimal flow rate for 13.5 nm(2%bandwidth) emission, mainly due to 4d—5p transition of Xe10+ ions, was among 0.3~0.4 sccm..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2560 (2017)
Accurate Determination of Boron Content and Isotope in Salt
PENG Zhang-kuang, LI Hai-jun, CHAI Xiao-li, XIAO Ying-kai, ZHANG Yan-ling, YANG Jian, and MA Yun-qi
The accurate content of boron directly restricts the boron isotope determination by using Positive Thermal Ionization Mass spectrometry based on Cs2BO+2 ion. At present, there is a big problem in determination of high salt and low boron samples with Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES), maThe accurate content of boron directly restricts the boron isotope determination by using Positive Thermal Ionization Mass spectrometry based on Cs2BO+2 ion. At present, there is a big problem in determination of high salt and low boron samples with Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES), mainly in two aspects: high salt matrix interference and instrument detection limit, and simple dilution can not solve these difficulties very well. At present, the above two problems will be encountered when determining the boron content in the salt samples by ICP-OES, therefore, it is necessary to enrich boron and remove the matrix ions. In this paper, Amberlite IRA 743 boron-specific resin is applied to purify the boron element, and the high-salt matrix can be removed, but there are some sodium ions adsorbing at the same time. Using 3 mol·L-1 NH3·H2O can remove most of the adsorbed sodium ions and have no effect on the adsorbed boron. Then eluting boron from the resin with10 mL 0.1 mol·L-1 HCl at 75 ℃. 208.900 nm was chosen as the detection wavelength for boron, and the recoveries were in the range of 106.00%～108.40%; the detection identification and quantification limits are 0.006 and 0.02 mol·L-1, respectively. Through the 12 times repeated experiments under different salinities, the relative standard deviations range from 1.94% to 3.37%, which less than 5%, so we think the method is feasible, and there is no accidental error. Combining with this method and Positive Thermal Ionization Mass spectrometry based on Cs2BO+2ion, the deternination of the boron content and isotopic composition of eight salt samples are achieved..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2564 (2017)
Research on the Relationship between Main Rock Metal Elements Content, Physical Parameters and Spectral Features in Tahe Area
YANG Chang-bao, LIU Na, ZHOU Zhen-chao, LI Shang-nan, ZHANG Chen-xi, and SONG Jiang-tao
300 rock samples from Tahe area of Heilongjiang province were tested in terms of 350~2 500 nm spectral reflectance, susceptibility, density, porosity and content of metal elements (Fe, Mn, Ti, Zr, V, Zn, Pb, Nb, Co, Bi) with the calculation of the absorption depth. With this basis, the correlation analysis based on the300 rock samples from Tahe area of Heilongjiang province were tested in terms of 350~2 500 nm spectral reflectance, susceptibility, density, porosity and content of metal elements (Fe, Mn, Ti, Zr, V, Zn, Pb, Nb, Co, Bi) with the calculation of the absorption depth. With this basis, the correlation analysis based on the method, an investigation was conducted to the characteristic response relationship between the metal element content of collected rock samples, physical parameters and spectral reflectance; besides, the correlation coefficient between metal elements and spectral absorption depth of rock samples as well as the correlation coefficient between physical parameters and spectral reflectance were calculated. The results were found as follows:(1)In the vicinity of 410 nm, the diorite porphyrite correlation coefficient of metal element and absorption depth exists the sharp peaks and troughs, and reaches extreme value.(2) Among the correlation of the metal element and the absorption depth, intrusive rocks correlation is significantly higher than that of other rock types.(3) Near 1 400 nm, the metal element and the absorption depth, and various physical properties of the spectral reflectance correlation exists sharp peaks and troughs. Wherein the correlation between the susceptibility, density, porosity and the spectral reflectance in the visible range fluctuates greatly. (4) In the range of 1 900~2 500 nm, the correlation coefficient between the metal element and the spectrum absorption depth, the physical parameters and the spectral reflectance fluctuate greatly, in which the metal elements and the spectral absorption depth were significantly correlated, and the correlation coefficient reached the extreme value. In this paper, the relationship between physical properties and the spectral characteristics of the metal element is further studied, which is of great significance in detecting reflectance of different lithology and different bands and distribution of different metal elements..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2569 (2017)
Detection of Caloric Value of Coal Using Laser-Induced Breakdown Spectroscopy Combined with BP Neural Networks
LI Yue-sheng, LU Wei-ye, ZHAO Jing-bo, FENG Guo-xing, WEI Dong-ming, LU Ji-dong, YAO Shun-chun, and LU Zhi-min
As a major indicator of coal property, the high accuracy and fast calorific value quantitative analysis plays a significant role in combustion efficiency and economic operation. Laser-induced breakdown spectroscopy (LIBS) was proposed to calibrate the calorific value of 35 coal samples combined with BP neural networks As a major indicator of coal property, the high accuracy and fast calorific value quantitative analysis plays a significant role in combustion efficiency and economic operation. Laser-induced breakdown spectroscopy (LIBS) was proposed to calibrate the calorific value of 35 coal samples combined with BP neural networks and cluster analysis. The calibration curve established on a certain type of coal samples can not be applied directly to the quantitative analysis for different types of coal considering the influence of matrix effect on the LIBS spectral data. Three different groups were classified with K-means clustering method according to the calorific value, ash content and volatile matter. The training set and the prediction set were optimized. Based on the correlation analysis of analytical line intensity and calorific value, taking into account the physical meaning of the analytical line, the peak intensity of 12 elements was taken as the input parameter of BP neural network model which was established for calorific value analysis of coal samples. The performance of the BP network and the comparison result of 3 different groups samples were studied. The result indicate that the R2 value of calibration curve is 0.996, relative error (RE) and the relative standard deviation (RSD) of calorific value is less than 3.42% and 4.23%, respectively, performing good results of repeated measurement. The calibration curve has different prediction ability for three group coal samples. The influence of experimental parameter fluctuation and matrix effect was reduced in a certain degree using peak intensity as the input parameter. The repeatability and accuracy of quantitative analysis results can be further improved by establishing BP neutral network for various type of coal samples specifically. The analytical results of calorific value based on LIBS technology combined with BP neural network were well predicted, which was potentially proven as a promising technologyy for fast on-line analysis..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2575 (2017)
Improvement of LIBS Accuracy in Detecting Pb in Pork by Physical Pretreatment of Samples
YANG Hui, WANG Cai-hong, LIU Mu-hua, CHEN Tian-bing, HUANG Lin, and YAO Ming-yin
Agricultural products have complex matrix prohibiting the development of LIBS (laser induced breakdown spectroscopy) in detecting its composition, especially tracing toxic heavy metals. The work was aiming at improving the sensitivity and accuracy of LIBS in predicting heavy metals in farm products. Fresh pork was chosAgricultural products have complex matrix prohibiting the development of LIBS (laser induced breakdown spectroscopy) in detecting its composition, especially tracing toxic heavy metals. The work was aiming at improving the sensitivity and accuracy of LIBS in predicting heavy metals in farm products. Fresh pork was chosen and dipped in Pb solution for making polluted samples. The samples were dried, ground to powder and pressed to pellets to remove the effect of water. The LIBS spectra of fresh and dried pork were collected at the same experimental conditions. The results demonstrated that the intensity of Pb was similar and obscure in fresh samples, but quite strong and clear in dried ones. The linear calibration curve between real content of Pb and intensity of Pb Ⅰ 405.78 showed that the correlation coefficient was poor in fresh pork and good in dried samples and the limit of detection of dried samples is 5.13 mg·kg-1. This experiment testified that the sensitivity and accuracy could be improved after the fresh samples were pretreated by simple physical methods, and it is potential in predicting heavy metals in farm products by LIBS. And this method can also be applied to other meat of detection by LIBS..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2580 (2017)
Study of Variable Selection Method Based on PLS for Quantitatively Measuring Heavy Metal in Water with LIBS
HU Li, ZHAO Nan-jing, LI Da-chuang, TANG Lei, and FANG Li
The spectral characteristics of multiple variables were regularly extracted for concentration inversion in the quantitative analysis of heavy metal with LIBS. However, overlapped spectral information might be contained among variables and the complexity of the regression model also would be increased. To extract effectThe spectral characteristics of multiple variables were regularly extracted for concentration inversion in the quantitative analysis of heavy metal with LIBS. However, overlapped spectral information might be contained among variables and the complexity of the regression model also would be increased. To extract effective feature variables, the variable selection method based on PLS was studied. PLS model established with the concentration of the element under test used as the dependent variable and multiple LIBS spectrum characteristic variables used as independent variables. The optimal variable subset was extracted on the basis of the original variable importance projection index for variable selection. The results showed that the optimal variable subset for Pb was composed of the Pb Ⅰ 405.78 nm peak, the spectral values before Pb Ⅰ 405.78 nm peak, the intensity corrected by the internal standard element and the signal to background in lake water, and the correlation coefficient square of the training set was 0.912. The optimal variable subset was used for PLS regression analysis, and RSD and RE of the test set were 10.2% and 7.9%, respectively, significantly better than the predictive results of the internal standard. It also showed that variable screening results for different elements and different water samples was applicative to some extent, but the internal standard element failed in correction for different water samples. The results provided high quality characteristic data for the LIBS quantitative analysis, and the methods also provided a reference for other quantitative analysis involving variable selection..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2585 (2017)
X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) Analysis of Steel Slags in Different Treatment Process and Active Index Prediction Model
CHEN Hua, LI Hui, DONG Shuo, GU Heng-xing, YANG Gang, and XU De-long
Steel slags in different treatment processes (such as layer pouring slag from converter, rotating furnace slag from converter, casting slag, desulfurized slag, layer pouring slag from electric furnace and rotating furnace slag from electric furnace) were set as the research objects. Research on steel slag’s chemical coSteel slags in different treatment processes (such as layer pouring slag from converter, rotating furnace slag from converter, casting slag, desulfurized slag, layer pouring slag from electric furnace and rotating furnace slag from electric furnace) were set as the research objects. Research on steel slag’s chemical composition and phase composition was carried out by X-Ray diffraction (XRD) and X-Ray fluorescence (XRF). The relationship of chemical composition, phase composition and activity was fitted by steel slag activity index prediction model with back-propagation neural network. The results showed that steel slag treatment process is different, its chemical composition and phase composition are obviously different. Steel slag activity index prediction model is of good compliance, and the relative errors are 2.42% and -2.54%, which can fully reflect the mapping relationship between input layer and output layer..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2590 (2017)
An Anti-Noise Method for Radial Velocity Measurement of M-Type Stars
YI Zhen-ping, PAN Jing-chang, SONG Yi-han, and LUO A-li
M dwarfs are the most common stars in the Milky Way, and their motion brings to light the evolution of the Milky Way. Radial velocity (RV) of M dwarf is one of the most important parameters to reflect its motion. Chinese large scale scientific construction project LAMOST survey has obtained hundreds of thousands of M-tM dwarfs are the most common stars in the Milky Way, and their motion brings to light the evolution of the Milky Way. Radial velocity (RV) of M dwarf is one of the most important parameters to reflect its motion. Chinese large scale scientific construction project LAMOST survey has obtained hundreds of thousands of M-type stars and their radial velocities measurement which needs the automatic and efficient program. The most commonly used method of measuring the radial velocity of an M star is to cross correlation between its observed spectra and the template spectra. However, in the actual process, idiosyncrasies of individual spectra and noises often lead to the loss of accuracy of radial velocities. To alleviate the effect induced by the above factors, in this paper, we try to improve radial velocities measurement of M dwarfs especially for those spectra with higher signal noise ratio but with local noises. A statistical method combining experienced features is proposed to select discriminative wavelength ranges of spectra for radial velocity measurement, avoiding noise affected wavelength regions. Some spectra from LAMOST DR3 M-type catalogue are used to test this method and the results are compared with the radial velocities of the same target from APOGEE. The experimental results show that the proposed method can effectively improve the accuracy of radial velocity measurement for M-type stars by reducing the influence of local spectral noises..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2594 (2017)
A New Method for Second Harmonic Baseline Correction and Noise Elimination on Residual Oxygen Detection in Packaged Xilin Bottle
LIU Yong-sheng, HE Jian-jun, ZHU Gao-feng, YANG Chun-hua, and GUI Wei-hua
For the proven technology and fast noncontact advantages of gas concentration measurement, the tunable diode laser absorption spectroscopy (TDLAS) is very suitable for the residual oxygen concentration detection in the packaged Xilin bottle. In this paper, TDLAS is used for residual oxygen detection in the packaged xilFor the proven technology and fast noncontact advantages of gas concentration measurement, the tunable diode laser absorption spectroscopy (TDLAS) is very suitable for the residual oxygen concentration detection in the packaged Xilin bottle. In this paper, TDLAS is used for residual oxygen detection in the packaged xilin bottle. The detection light goes through the air and glass bottle, and the scattering and attenuation to the glass wall of the laser are the main interferences which have a great impact on the stability of the second harmonic signal. This paper designed and built the residual oxygen detection system in packaged bottle based on TDLAS. According to the second harmonic signal collected from the system, a new method based on wavelet transform is proposed and the effect is obvious. Firstly, using “sym6” wavelet, the measured signal was decomposed by five layers of wavelet, and the corresponding baseline slope was obtained according to the low frequency component of each layer. Then, the baseline slope of the original signal was obtained by weighted average of the five baseline slopes. According to the obtained baseline slope, the original signal was processed by the baseline, and the reconstructed signal was obtained after the wavelet decomposition and the soft threshold processing. The measurement results of the bottle with 21% oxygen concentration showed that the relative error between the treated and the theoretical signals decreased from 1.26% to 0.12%, which proved that this method could solve the problems of baseline drift and noise interference in the process of residual oxygen concentration detection, and overcome the interference of the glass wall to the second harmonic signal, providing a high quality signal for measuring oxygen concentration..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2598 (2017)
A Detection System Design of Echelle Diffraction Efficiency and Stray Coefficient
SHEN Chun-yang, CUI Ji-cheng, SUN Ci, WANG Wei, CHEN Jian-jun, and LI Xiao-tian
Echelle, which is highly appreciated due to its excellent properties in recent years, has the advantages of low groove density, wide blaze angle, high diffraction grades, wide spectral range, high dispersion ratio, and high spectral resolution. Diffraction efficiency and stray light coefficient which can express the quEchelle, which is highly appreciated due to its excellent properties in recent years, has the advantages of low groove density, wide blaze angle, high diffraction grades, wide spectral range, high dispersion ratio, and high spectral resolution. Diffraction efficiency and stray light coefficient which can express the quality of the echelle directly reflect the optical properties of the echelle. Thus, accurate measuring of the diffraction efficiency and stray light coefficient is the precondition for grating applications. Therefore, based on the diffraction theory of echelle, the paper creatively puts forward a thought of using one system measuring echelle diffraction efficiency and stray light coefficient. The system introduces a double-rail structure, possessing the advantages of simple and novel structure, multiple functions in one machine. Through theoretical analysis and calculation, the structural parameters of the detection system are determined. The results indicate that the system can be used to measure echelle diffraction efficiency with the spectral range from 190 to 1 100 nm, and the system can also be used to measure echelle stray light with the spectral range from 200 to 800 nm, achieving the purpose for measurement of diffraction efficiency and stray light in one system..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2603 (2017)
Design of Hyperspectral Polarimetic Imaging System Based on LCTF and LCVR
YANG Fan-chao, LI Yong, HU Bing-liang, KONG Liang, WEI Ru-yi, and LI Hong-bo
A hyperspectral polarimetic imaging system was proposed based on LCTF and LCVR. The system could break the limit of incomplete polarization acquiring by the conventional single LCTF system and acquire the full Stokes parameters of targets. It used the 4 different groups of phase retardance of LCVRs to build a 4×4 A hyperspectral polarimetic imaging system was proposed based on LCTF and LCVR. The system could break the limit of incomplete polarization acquiring by the conventional single LCTF system and acquire the full Stokes parameters of targets. It used the 4 different groups of phase retardance of LCVRs to build a 4×4 inversion algorithm matrix to calculate the original full polarization information. After calibration of the Retardance-Voltage characters of two LCVRs, the inversion algorithm was verified by laser at 633nm. The measured errors of full Stokes parameters, corresponding calculated degree and angel of linear polarization were analyzed, and the inversion algorithm was proved work well. The results indicated that the hyperspectral polarimetric imaging system could provide reliable hyperspectral and polarization information for remote sensing..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2610 (2017)
Study on the Relative Radiance Calibration Method of Large Array Filter-Type Multispectral Imaging System
WANG Jian-wei, PEI Lin-lin, TAN Zheng, HUANG Min, L Qun-bo, LIU Yang-yang, and LI Wei-yan
The full frame transfer sensor with large array is used in the large array filter-type multi-spectral imaging system, and a mechanical shutter is employed to avoid the images blurred. But the mechanical shutter is unstable, reducing the mosaic images’ uniformity and producing RGB images’ color bar with bias.The paper pThe full frame transfer sensor with large array is used in the large array filter-type multi-spectral imaging system, and a mechanical shutter is employed to avoid the images blurred. But the mechanical shutter is unstable, reducing the mosaic images’ uniformity and producing RGB images’ color bar with bias.The paper proposed a method of relative radiance calibration based on objects’ radiance coherence.The correction factors were obtained by the different images with same objects, and used to correct the images based on the first frame. The mosaic images’ first difference was introduced to appraise the images uniformity before and after correction. The field data were corrected by this method, which indicated that the method could correct the non-uniformity of mosaic images and the color bar with bias. The method is unsensitive to the accuracy of mosaicking, and can be used widely..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2615 (2017)
Two-Photon, Three-Photon, Four-Photon Near-Infrared Quantum Cutting Luminescence of Er3+ Activator in Oxyfluoride Vitroceramics
CHEN Xiao-bo, LI Song, GUO Jing-hua, ZHOU Gu, FAN Ting-ting, YU Chun-lei, ZHENG Dong, ZHAO Guo-ying, TAO Jing-fu, LIN Wei, CHEN Luan, and HU Li-li
Two-photon, three-photon, and four-photon near-infrared quantum cutting luminescence of Er3+∶oxyfluoride vitroceramics are studied. X-ray diffraction, absorption, visible to near infrared luminescence and excitation spectra of Er3+-doped oxyfluoride vitroceramics have been measured. We found that when the concentrationTwo-photon, three-photon, and four-photon near-infrared quantum cutting luminescence of Er3+∶oxyfluoride vitroceramics are studied. X-ray diffraction, absorption, visible to near infrared luminescence and excitation spectra of Er3+-doped oxyfluoride vitroceramics have been measured. We found that when the concentration of the Er3+ ion increased from 0.5% to 2.0%, the infrared excitation spectra intensities of the Er3+ ion enhanced by approximately 5.64, 4.26, 2.77, 7.31, 6.76, 4.75, 2.40, 11.14, 2.88, and 4.61 times for the 4I15/2→2G7/2, 4I15/2→4G9/2, 4I15/2→4G11/2, 4I15/2→2H9/2, 4I15/2→(4F3/2, 4F5/2), 4I15/2→4F7/2, 4I15/2→2H11/2, 4I15/2→4S3/2, 4I15/2→4F9/2, and 4I15/2→4I9/2 transitions. Meanwhile, it can also be found that the visible excitation spectra intensity of the Er3+ ion decreased by approximately 1.36, 1.93, 3.43, 1.01, 2.24, and 2.28 times for the 4I15/2→2G7/2, 4I15/2→4G9/2, 4I15/2→4G11/2, 4I15/2→2H9/2, 4I15/2→(4F3/2, 4F5/2), and 4I15/2→4F7/2 absorption transitions of the Er3+ ion, respectively. That is to say, the samples exhibited a 2 to 11 times enhancement in both infrared luminescence and excitation intensities, with a concomitant one to three times decreasing of both visible luminescence and excitation intensities. Moreover, the excitation spectra of 1 543.0 and 550.0 nm luminescence were very similar both in shape and peak wavelength, confirming that the multiphoton near-infrared quantum cutting luminescence phenomena were found. In order to analyze the process and mechanism of quantum cutting better, we measured the variation of main visible and infrared luminescence intensity based on the excitation intensity. It found that all visible and infrared luminescence intensity was linear depended on the excitation intensity basically. In which, the variation of the visible luminescence intensity depended on the excitation intensity was slightly larger than linear. It is resulted from the very small absorption of excited state. The variation of the infrared 1 543.0 nm luminescence intensity depended on the excitation intensity was slightly smaller than linear. It is the characteristic phenomena of quantum cutting luminescence. It found that two-photon quantum cutting luminescence of 4I9/2 state mainly resulted from the {4I9/2→4I13/2, 4I15/2→4I13/2} ETr31-ETa01 cross-energy transfer process. Three-photon quantum cutting luminescence of the 4S3/2 state mainly result from the {4S3/2→4I9/2, 4I15/2→4I13/2} ETr53-ETa01 and {4I9/2→4I13/2, 4I15/2→4I13/2} ETr31-ETa01 cross-energy transfer process. Four-photon quantum cutting of 2H9/2 mainly results from the {2H9/2→4I13/2, 4I15/2→4S3/2} ETr91-ETa05, {4S3/2→4I9/2, 4I15/2→4I13/2} ETr53-ETa01 and {4I9/2→4I13/2, 4I15/2→4I13/2} ETr31-ETa01 cross-energy transfer process. These measured results are useful for the next-generation of quantum cutting solar cells, a current hot point globally..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2619 (2017)
Preparation and Luminescence Properties of a New Green Emitting Ca3Mg3Si4O14∶Eu2+ Phosphor
PAN Hua-yan, WANG Le, LI Yang-hui, WU Tuo, and LUO Dong
Green light-emitting Ca3Mg3Si4O14∶Eu2+ phosphors were prepared by solid-state reaction using CaCO3, MgO, SiO2 and Eu2O3 as raw materials. The effects of Eu-doping concentration and fluxes (NH4Cl, BaF2) on the crystal structure, luminescence property, and thermal stability of phosphor were studied, which were characteriGreen light-emitting Ca3Mg3Si4O14∶Eu2+ phosphors were prepared by solid-state reaction using CaCO3, MgO, SiO2 and Eu2O3 as raw materials. The effects of Eu-doping concentration and fluxes (NH4Cl, BaF2) on the crystal structure, luminescence property, and thermal stability of phosphor were studied, which were characterizes by X-ray diffraction (XRD), and photoluminescence (PL) spectra, respectively. The XRD results show that the crystal structure of Ca3Mg3Si4O14∶Eu2+ is consistent with the calculated patterns, which investigated the crystal structure of the compound Ca3Mg3Si4O14∶Eu2+. The phosphor has strong excitation around 360～450 nm and exhibits a broad emission band with a maximum at 530 nm under 440 nm excitation. With the increase of Eu2+ concentration, the phosphor shows a red-shift and the quenching concentration of Eu2+ is about 6%. With the introduction of NH4Cl and BaF2 as fluxes, the luminous intensity of Ca3Mg3Si4O14∶Eu2+ phosphor has been improved. Compared with the luminescence intensity of Ca3Mg3Si4O14∶Eu2+phosphor without flux, the photoluminescence intensity increased by 70% when adding NH4Cl as flux. Furthermore, the emission intensity reduced by only 7.6% and 14% at 150 ℃ for Ca3Mg3Si4O14∶Eu2+ phosphor and commercial green phosphor. The Ca3Mg3Si4O14∶Eu2+ phosphor also possesses high thermal stability, and these luminescnce properties indicate that Ca3Mg3Si4O14∶Eu2+ phosphor is a promising green phosphor for use in solid-state white lighting..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2627 (2017)
A Fast Raman Baseline Correction Algorithm Based on Automatic Linear Fitting
ZHANG Wan-li, ZHU Jian, LI Jian-jun, and ZHAO Jun-wu
Raman spectroscopy occupies an important position in modern spectroscopy technique due to its numerous advantages such as non-invasive, high-sensitivity, etc. Meanwhile baseline correction is one of the key technologies of Raman qualitative and quantitative analysis, thus it is meaningful to develop high performance alRaman spectroscopy occupies an important position in modern spectroscopy technique due to its numerous advantages such as non-invasive, high-sensitivity, etc. Meanwhile baseline correction is one of the key technologies of Raman qualitative and quantitative analysis, thus it is meaningful to develop high performance algorithms for baseline correction for the purpose to improve the effectiveness and accuracy of analytical results. Because of the defect of traditional algorithms for the problem to correct baselines of a group of Raman spectra which have a similar background, this paper proposed a fast Raman baseline correction algorithm (FRBCA) based on automatic linear fitting for this problem and demonstrated its fundamental ideas and the implementation process of this algorithm. In the FRBCA algorithm, firstly one of the spectra was selected automatically as a reference spectrum and estimated its baseline and the mask points by the automatic linear fitting algorithm, then the baselines of other spectra which have a high relativity to the selected spectrum were estimated quickly based on the mask points of reference spectrum. Separate treatment was called for those spectra which does not satisfy the condition. This innovation makes the algorithm has strong robustness and can be suitable for the complex Raman spectrum baseline correction scenario. In addition, some actual Raman spectral data were used to test performance of the algorithm and make a comparison between the proposed algorithm and the traditional algorithm. The results show that fast Raman baseline correction algorithm proposed in this article allows a fast Roman baseline correction for a number of Raman spectral data. It reduces the consuming time more than 30% while has a similar performance at the correction result no worse than the algorithm correcting the Raman spectroscopy individually. The method presented in this article is conceptually simple, easy to implement, fully automated and doesn’t need additional parameters, making it suitable for the fully automated baseline correction of large numbers of spectra which have a similar background..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2632 (2017)
Synthesis of Cr, Ag Co-Doped ZnS Nanomaterials and Its Adsorption Capability for Reactive Dyes
ZHAI Hao-ying, and ZOU Hao
Cr, Ag co-doped wurtzite ZnS nanomaterials were prepared by hydrothermal method, and the effects about different reaction time and different doping ratio of Cr and Ag on optical property of ZnS nanomaterials were investigated. The optical performance and structure of Cr, Ag co-doped ZnS materials were characterized resCr, Ag co-doped wurtzite ZnS nanomaterials were prepared by hydrothermal method, and the effects about different reaction time and different doping ratio of Cr and Ag on optical property of ZnS nanomaterials were investigated. The optical performance and structure of Cr, Ag co-doped ZnS materials were characterized respectively by fluorescence spectrophotometer, infrared spectrometer, X-ray differaction (XRD), and scanning electron microscope (SEM), and the adsorption performance for four kinds of reactive dyes such as methyl violet (MV), butylrhodamine B (BRB), tetrachlorotetrabromo fluorescein (TCTBF) and eosin B (EB) was discussed further. The results showed that Cr3+ and Ag+ replaced and embeded into the location of Zn2+, and doped into the crystal lattice of ZnS. Thus the optical property and morphology of doped ZnS nanomaterials changed according to the optical characterization and SEM. That is to say, after being doped into Cr and Ag, the fluorescence intensity of ZnS was reduced, moreover, it has normal shape, puffy surface and pompon-like structure. And the morphology and the optical property of doped ZnS nanomaterials were optimum as 12 h of the reaction time, and doping proportion of Cr and Ag were respectively 1%. According to the N2 isothermal adsorption-desorption analysis, the specific surface area and pore size distribution of Cr, Ag co-doped ZnS materials were calculated. Meanwhile, the doped ZnS materials were used to adsorb MV, BRB, TCTBF and EB respectively. And the influence of doped ZnS materials on adsorptivity for several reactive dyes were inspected from the factors such as adsorption time, temperature and pH value respectively. Then the maximum adsorption quantity of Cr, Ag co-doped ZnS materials for four reactive dyes was obtained under the conditions about 7 of pH value and 9, 11, 9 and 9 h of absorption separately at room temperature..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2638 (2017)
Mechanism of the Green Cosolvent Triethylene Glycol on the Process of Electrochemical Oxidation of Acetylene
SONG Xiu-li, YANG Hui-min, LIU Xian, JIAN Xuan, and LIANG Zhen-hai
A new view to determine concentration of dissolved acetylene in ambient temperature and pressure was put forward, and solubility of acetylene in different solvents was investigated by UV-Vis. (UV-Vis spectrophotometry). Influence of cosolvents such as acetone, TEG (triethylene glycol), DMSO (dimethyl sulfoxide), DMF (NA new view to determine concentration of dissolved acetylene in ambient temperature and pressure was put forward, and solubility of acetylene in different solvents was investigated by UV-Vis. (UV-Vis spectrophotometry). Influence of cosolvents such as acetone, TEG (triethylene glycol), DMSO (dimethyl sulfoxide), DMF (N,N-dimethyl formamide) especially the green cosolvent of TEG and its mechanism and volume fraction, temperature and scan rate on the process of electrochemical oxidation of acetylene at Pt electrode were examined by CV (cyclic voltammetry). The analysis results show that the concentration of dissolved acetylene can be determined accurately through claret-colored copper acetylide by UV-Vis. (at 542 nm), the solubility order of acetylene in different solvents is DMF>DMSO>TEG>acetone, the hydrogen bonding interactions were identified as the main interaction controlling the mutual solubility of the H2O in Na2SO4 solution and TEG in the system, and when the supporting electrolyte is 0.5 mol·L-1 Na2SO4 with TEG (vol.9%), the dissolved acetylene can be the most easily oxidized by OH· from the electrolysis process of Na2SO4 solution and the ipa (anodic peak current) is maximum, the process of electrochemical oxidation of acetylene at Pd electrode is under adsorption control and irreversible, the Ea (apparent activation energy) of the process of electrochemical oxidation of acetylene at Pd electrode is 13.20 kJ·mol-1. This study expects to seek a kind of good solvent acetylene and provides theoretical basis and experimental guidance to the research of electrochemical oxidation acetylene process and the development of sensor for acetylene (especially electrochemical sensor for acetylene), green chemistry and acetylene chemical industry..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2645 (2017)
Single-Wavelength Oxygen Saturation Detection Fusing Optical Absorption and Scattering Properties: A Phantom Study
MA Yao, GAO Bo, CHEN Chang, ZHAO Xin, QIAN Zheng, and GONG Min
Oxygen saturation (SO2) for clinical observation of the disease changes provides a meaningful indicator. Traditional oxygen saturation analyses adopt the dual-wavelength and multi-wavelength photoplethysmography to achieve non-invasive detection to reduce the pain of patients. In this paper, a novel approach combining Oxygen saturation (SO2) for clinical observation of the disease changes provides a meaningful indicator. Traditional oxygen saturation analyses adopt the dual-wavelength and multi-wavelength photoplethysmography to achieve non-invasive detection to reduce the pain of patients. In this paper, a novel approach combining single wavelength laser optical absorption induced photoacoustic and optical scattering, was developed to noninvasively measure blood oxygen saturation, the concentration of deoxygenated haemoglobin (HbR) and oxyhemoglobin (HbO2). A theoretical derivation between the absorption and scattering light characteristics and linear relationship of photoacoustic spectroscopy built the single-wavelength oxygen saturation detection technology, so parameters analysis and imaging of tissue could also be obtained. Here, the phantom experiment successfully demonstrated the quantization of the concentration of a dual-ink combined with green-red ink imitating a blood with hemoglobin and oxygenated hemoglobin. The proportion of red ink, that is to say, pseudo-SO2 was measured with experimental errorless than 6.97%. Then the pseudo-SO2 was imaged in the single tube cross-section for blood vessel copy. Unlike conventional multi-wavelength photoacoustic or near infrared spectroscopy approaches, the proposed single-wavelength method significantly lowers the cost of laser system and portable implementations..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 2652 (2017)
[in Chinese]
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 8, 1 (2017)
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