SPECTROSCOPY AND SPECTRAL ANALYSIS

The Research on Matrix Effect and Correction Technology of Rock Sample in In-Situ Energy Dispersive X-Ray Fluorescence Analysis
Cheng F, Gu Y, Ge LQ, Zhao JK, Li MT and Zhang N
The mineral constituents of the rock sample can be analyzed with in-situ energy dispersive X-ray fluorescence analysis technology (In-situ EDXRF), the matrix effect of rock sample will effects on measurement results. The Monte Carlo simulation method is used to conduct fluorescence analysis spectrum with ideal measurement conditions, which provides analytical data for matrix effect research. The measured spectrum of seventeen kinds rock samples are being simulated, which has the same Cu content. Therefore, the influences with matrix effect of rock sample in in-situ EDXRF take Cu element for example. Based on correlation between Cu Kα X-ray intensity and spectral parameters, considering elements similarity of all kinds rock samples, it is found that the variation the Cu Kα X-ray intensity not only by the control of rock elements composition or rock classification. The matrix effect of rock samples must be classified according correlation between Cu Kα X-ray intensity and spectral parameters. After the matrix effect classification, fifteen kinds of rock samples, which belong to the same matrix effect, can be corrected more effective. Based on principal component analysis of similar matrix effect rock samples, it is found that the scattering background, target element K-series X-ray of X-ray tube and its incoherent scatter intensity can be a good description of Cu Kα X-ray intensity which is affected by rock matrix, thus it can be used to correct the Cu element measurement results. Certainly, this technology can also provide reference for matrix effect correction to other elements in rock.
Comparative Study on Three Pretreatment Methods for Atomic Absorptive Spectrophotometry Determination of Metal Elements in Lycium Barbarum
Wang YM, Zhang LL, Zhang XW, Zhang K, Ma JH, Zhang L, Zhang BL, Su L and Wang JL
A simple, fast and accurate method was explored to determine the mineralelements in Lycium barbaru.Three different pretreatment methods, including dry ashing method, HNO3-H2O2 and HNO3-HClO4 wet digestion, method were employed for digestion of the samples of Lycium barbaru. The concentrations of Na,K,Ca,Mg,Fe,Cu,Zn,Ni,Pb and Cd were determined by using atomic absorption spectrometry. The experimental results showed that the recovery rates of dry ashing method, HNO3-H2O2 and HNO3-HClO4 wet digestion method were in the ranges from 89.88% to 102.15%, 92.34% to 103.21% and 94.52% to 102.10% respectively; the relative standard deviation (RSD) of dry ashing method, HNO3-H2O2 and HNO3-HClO4 wet digestion method were lower than 3.037%, 2.751% and 2.496% separately. The RSD and recovery of three pretreatment methods were all satisfied with the analysis requirements. But compared with dry ashing method and HNO3-H2O2 wet digestion method, the recovery of HNO3-HClO4 wet digestion method was better, and the precision was higher. Besides, compared with three pretreatment methods, the average value of Na, K, Ca, Fe and Cd had statistical difference (p<0.05), and HNO3-HClO4 wet digestion method was significantly higher than others.In addition, HNO3-HClO4 wet digestion method taken a shorter time and less consumption of reagents. Therefore, HNO3-HClO4 wet digestion method can be used as the preferably pretreatment method for the determination of the contents of metal elements by atomic absorption spectrophotometry method.
Study on Smelting Remains of Tangjiadun Site
Wei GF, Gao SL, Qin Y and Wang LQ
The furnace walls and slags from Tangjiadun site in Zongyang County of Anhui Province were analyzed by means of X-ray fluorescence spectrometer (XRF), X-ray diffraction analyzer (XRD), scanning electron microscope (SEM) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) in order to probe into the copper smelting technology of Tangjiadun site. Results show that the furnace walls are from the copper smelting furnaces and the slags are the reduced slag. According to the concentrations of elements As, Ag, Sb and Bi in copper prills, it can be calculated that relative probabilities that these copper prills in the slags come from the copper sulfide ore reach over 87. 87%. Combined with the results of SEM-EDS, the smelting process of “copper sulphide ore-copper” was used in Tangjiadun site, and the smelting remains (slags and prills) were considered as the smelting products of sulphide copper ore. This study is not only beneficial to research on bronze cultural of Zongyang County, but also has very important significance to explore the development and evolution of bronze metallurgy technology in Zongyang-Lujiang area.
The Study of the Rescale Method of the Spectrum Shifting in X-Ray Fluorescence Well Logging
Zhang QX, Zhao JK, Gu Y, Ge LQ, Zhang XY, Zhang J, Wang HD and Zhang L
The X-ray fluorescence well logging technology is a significant method that can make quantitative analysis orsemi-quantitative analysis on the wellface. This method is very important to mineral exploration. The spectrum shifting is often observed in the X-rayfluorescence well logging because the temperature in the well changes acutely. The hardware is used to release the spectrum shifting and the software method is used to rescale the tiny spectrum shifting. There are too manyspectra to be rescaled in a well logging task by manually. In this paper, an auto method to rescale spectrum shifting, via the expert system model which is based on the special process to rescale spectrum shifting in manual, is presented. The symmetric zero-area conversion method, which is not sensitive to the changes of the baseline, is used to research the peaks. And then, the characteristic peaks will be identified by the standard errors, automatically. The prior knowledge (the last energy scale) and the gauss probability density function are used to analyze the peaks qualitatively and confirm the energy of characteristic peaks. Then the least square method is applied energy calibration. The singular deviation point, away from the calibrationline, will be rejected and the energy ratio will be obtained again. This method is applied for rescaling spectrum shifting in 322 spectra and obtains a satisfactory achievement.
Preparation of Rubber Accelerator Tetrabenzylthiuramdisulfide and Its Spectral Analysis
Jia TX, Zhang N, Guo Y, Lu YC, Tian DY and Li HL
In the study, rubber accelerator tetrabenzylthiuramdisulfide (TBzDT) was synthesized with two-step method with hydrogen peroxide as oxidant firstly. TBzDT was detected and characterized with XRD, FT-IR, TG-DTA. Its micro-structure was revealed. Chemical bond types into TBzDT molecule were revealed with FT-IR. TBzDT phase composition and structure were given by crystallographic data from XRD detecting such as cell parameters, crystal face index. The phase composition and qualitative identification of TBzDT structure were completed. Two kinds of information were detected with TG-DTA as to quality change and thermal effect. TBzDT phase transition and decomposition temperature were 142.5, 200.9 ℃ respectively. The decomposition temperature of TBzDT was relevtively high. It could provided reference with research on rubber vulcanizing properties by TBzDT on rubber vulcanizing machine. A little SC2 contained into TBzDT was revealed by FTIR, TG-DTA from different sides.
Application of Joint Skewness Algorithm to Select Optimal Wavelengths of Hyperspectral Image for Maize Seed Classification YANG Sai, ZHU Qi-bing*, HUANG Min
Yang S, Zhu QB and Huang M
As an effective method for the nondestructive measurement of agricultural products quality, hyperspectral imaging technology has been widely studied in the field of seed classification and identification. Feature extraction and optimal wavelength selection are the two critical issues affecting the application of hyperspectral image in the field of seed identification. This study aimed to select optimal wavelengths from hyperspectral image data using joint skewness algorithm, so that they can be deployed in multispectral imaging-based inspection system for the automatic classification of maize seed. The hyperspectral images covering the wavelength range of 438~1 000 nm were acquired for 960 maize seeds including 10 varieties. After extracting the mean spectrum and entropy from the hyperspectral images, the joint skewness algorithm was used to select optimal wavelengths, and the classification models based on support vector machine were developed using the mean spectrum, entropy, and their combination, respectively. The experimental results indicated that the classification accuracy of the models developed by combination of the mean spectrum and entropy were higher than that of the mean spectrum or entropy for either full wavelengths or optimal wavelengths. The classification model for the combination of the mean spectrum and entropy based on the 10 optimal wavelengths selected by the joint skewness algorithm obtained 96.28% accuracy for test samples, with improvements of 4.30% and 20.38% over that of the mean spectrum and entropy, respectively, which was higher than the classification accuracy of the model that developed in the full wavelength (i.e., 93.47%). Meanwhile, the classification model based on joint skewness algorithm yielded the better classification accuracy than that of uninformative viable elimination algorithm, successive projections algorithm, and competitive adaptive reweighed sampling algorithm. This study made the online application of the hyperspectral image technology available for seed identification.
The Research of On-Orbit Calibration Method Based on Solar Diffuser
Huang WX, Zhang LM, Si XL, Cao XJ, Lj JL, Wang W and Zhu XM
As one of the most important ways of improving the calibration accuracy at present, the calibration method based on a solar diffuser(SD) is an independent calibration way with advantages of high accuracy, high frequency and high efficiency . The principles, methods and implementation process of on-orbit calibration based on the SD is described in this thesis. The radiance reference for calibration in space is found and the physical model of the on-orbit reflectance calibration is provided. The main factor which affects the calibration uncertainty is the determination of the SD bidirectional reflectance distribution function (BRDF) value by analyzing the physical models of on-orbit calibration. Thus, the timing selection of the on-orbit calibration is introduced and the BRDF in the range of angles variety within the calibration timing is tested in the lab. During the on-orbit calibration time, the high accuracy on-orbit calibration in the remote sensors’ whole life is achieved by the accurate radiance input which is ensured by monitoring and correcting the SD BRDF value from its fabrication to its life end. Finally, the on-orbit calibration uncertainty is estimated based on the measurement levels of the parameters in the physical model. And the uncertainties of on-orbit reflectance calibration and method of radiance calibration are better than 2.03% and 2.04% by type B standard uncertainty evaluation method.
Emission Spectrometry for the Detection of Methane Based on Gas Ionization Discharge Microplasma at Room Temperature
Shen LH, Wang HN, Chen PJ, Yu CX, Deng HN and Zhang CX
A microplasma-generating device was developed by using needle-plate electrode discharge with the incorporation a Pt/carbon nanotube (CNT) nanocomposite-decorated FTO electrode. When an alternating current voltage of 1.32 kV and a low power consumption of 13 W in nitrogen (N2) carrier gas are applied, the system can be applied to detect methane at room temperature. The main characteristic lines were assigned to CH, C2 and Hα during the discharge process of CH4 at room temperature.The emission intensity of C2 at 516 nm is linear with the concentration of CH4 from 0.5% to 4.0% (φ), and the detection limit (S/N=3) is 0.19% (φ). The emission intensity of Hα at 656 nm is linear with the concentration of CH4 from 0.1% to 3.0%(φ)with the detection limit (S/N=3) is 0.03% (φ). The relative standard deviation (RSD) is less than 2% from 11 repetitive analyses using 3.2% CH4. The Pt/CNT nanocomposite-modified FTO electrode exhibited enhanced sensing performance with precise, repeatability and linear correlation compared with that of the pure MWNT/FTO electrode and bare FTO electrode. When CH4 were discharged in air, the emission spectra of CH4 was different from that in N2. It was found that C2 peak was disappeared and the Hα intensity was also liner to the concentration of CH4 in the range of 0.5%~4%. The established system exhibited advantages with small size, simple fabrication and operation at room temperature compared to other detection system.
Study on Hydrogen Fluoride at High Temperature Detection Method with Temperature Correction Based on Laser Technology
He Y, Shang YJ, You K, Gao YW, Chen C and Liu WQ
Hydrogen fluoride(HF) is one of the important character gases for fault diagnosis of gas insulation switch (GIS) in the system of substation equipment. The high-accuracy, fast- response and real-time detection method of HF is a focus in industrial and environmental fields. In this research, the HF detection experiment system was set up at first based on laser absorption spectroscopy technology combined with anti-corrosion multiple reflection cell made by monel steel. Moreover, the laser absorption spectral characteristics of HF at different temperature were analyzed, then the coefficient partition function curve and absorption linestrength curve according to the distribution function coefficient in HITRAN database were studied. As the most important work, the concentration inversion algorithm was designed here with HF character spectrum analysis and temperature parameter correction method for accurate concentration inversion after the basic study. At last, the continuous experimental results were obtained by HF sample gases of different concentration considerating the temperature characteristic of the multiple reflection cell. When the multiple reflection cell was heat and stay stably, the biggest detection error of concentration inversion was 5.33% and 5.87% at 313 and 323 K respectively without temperature correction, and that was 1.20% and 1.47% respectively after temperature correction. By continuous detection and culculation, the detection limit is 8.7×10-5 mmol·mol-1 at 323 K which is a little higher than 6.3×10-5 mmol·mol-1 at 290 K(20 m optical length). Although the detection error with temperature correction at high temperature was higher than it at room temperature, the results show that it was lower than that without correction at the same temperature. It was verified that the this spectrum detection method and concentration inversion algorithm works stably and reliably, so this technology could realize HF real-time monitoring demand in chemical production field and it will provide the effective technical support in gas emission regulation in safety and environment protection for our country.
Doppler Lidar with High Sensitivity and Large Dynamic Range for Atmospheric Wind Measurement
Wang L, Tan LQ, Chang B, Lu GG, Gao F and Hua DX
Doppler wind Lidar is an important method for atmospheric wind measurement. The Doppler frequency shift of backscattering spectrum due to the wind is detected from the transmissions of frequency discrimination. High sensitivity and large dynamic range measurement is difficult for atmospheric wind measurement because of the limitationof frequency discriminator characteristic. In this paper, a frequency discriminator constructed with Dual fiber Mach-Zehnder interferometer is proposed. Two fiber Mach-Zehnder interferometers with different atmospheric wind detection dynamic range and sensitivity are designed and used to measure Doppler frequency shift at the same time. The optical path difference of FMZI-2 is 13.7 cm which can realize large dynamic range wind measurement (±100 m·s-1) and the optical path difference of FMZI-1is designed to be 74.8 cm which can realize high sensitivity detection. Moreover, the absolute wind velocity of FMZI-1 channel can be corrected by the measurement result of FMZI-2 channel. Thus the high sensitivity and large dynamic range wind detection can be realized. The sensitivity, SNR and wind error of two channels are simulated and analyzed for different parameters. The results indicate that the system can realize the wind error less than 1 m·s-1 for large dynamic range(±100 m·s-1) wind velocity, which is a beneficial exploration for high sensitivity and large dynamic range Doppler wind lidar.
Solution Cathode Glow Discharge Based on Charge Coupled Device Detector
Liu X, Yang XT, Zhan XC, Yuan JH, Fan XT and Jiao J
In 21st century, many countries pay much attention to lithium because lithium is an ideal material for green energy and light alloys as well as an important kind of strategic resources. The main source of lithium is from salt lake brine. China has rich resources of salt lake brine, but these brine resources are mainly distributed in the remote western region, which are in urgent need of portable analytical instrument for on-site exploration and exploitation. However, the available experimental techniques at present can not achieve the target of on-site analysis. Over the past decade, based on atmospheric pressure solution cathode glow discharge-atomic emission spectrometry (SCGD-AES) has been paid attention to analytical researchers because it runs without common air conditions such as fuel gas, carrier gas and vacuum environment. On the basis of previous studies of other researchers, we have developed a portable SCGD based on a charge coupled device (CCD) detector by ourselves, which is short for Li-K analyzer. The length, width, height and weight of the portable Li-K analyzer is 35 cm, 19 cm, 27 cm and 10 kg, respectively, which is very conducive to carry. This work selected the wavelength of 670.78 nm as the characteristic spectral line of Li and has established a rapid analytical method for Li in salt lake brine based on two different types of brines from Tibet. Under the optimum operating conditions, the detection limit of Li was 4 ng·mL-1 and the measured precision (RSD) was better than 2%. The analytical results of Li were much different from those obtained by inductively coupled plasma-mass spectrometry (ICP-MS) with different dilution ratios by standard curve method, which may be related to the matrix effect of solution. However, the analytical results of Li agreed well with the results obtained by ICP-MS using standard addition method, which showed that standard addition method can effectively reduce the matrix effect and improve the analytical accuracies. A great deal of experimental results showed that standard addition method could obtain accurate results of Li using only two points and can greatly reduce the workloads. This work laid a methodological foundation for on-site determination of Li in salt lake brine by the portable Li-K analyzer.
Identification of Coalmine Water Inrush Source with PCA-BP Model Based on Laser-Induced Fluorescence Technology
Wang Y, Zhou MR, Yan PC, He CY and Liu D
The water inrush should been rapidly and accurately identified during preventing coalmine water inrush. The laser induced fluorescent (LIF) spectrum technology provides a new method to identify water inrush with the characteristics of high sensitivity, quick and accurate monitoring. In order to identify water inrush, this paper introduces the spectrum technology of LIF to obtain water inrush fluorescence spectra data. The spectral preprocessing methods of Savitzky-Golay(SG) and Multiplicative Scatter Correction (MSC) have been used to eliminate noise spectra in collecting process. Principal component analysis (PCA) extracts feature information, for SG reprocessing data, when the number of principal component is 3, the cumulative contribution rate can reach 99.76 percent. This method has largely retained the information of original data. This paper chooses the classification model with 3 layers BP neural network, constructing by different training and testing sets. The classification model with SG preprocessing has achieved accurate identification, however, appeared few false identification for MSC and original data. The result shows that SG preprocessing is better than MSC. Research results show that the classification model with PCA and BP neural network can effectively identify coalmine water inrush, and have the strong self-organizing, self-learning ability.
Study on Determination of Molybdenum in Molybdenum Concentrate by Atomic Absorption Spectrometry Indirectly
Qu W, Zhou CY, Cai LL and Li WJ
For the determination of molybdenum in molybdenum concentrate,lead molybdate gravimetric method was considered as standard method. In order to ensure the lead ions to be washed thoroughly from the entrained precipitate, lead molybdate precipitate was washed, filtered repeatedly, then ashed and burned. This method cannot satisfy the rapid measurement demand of mineral processing and metallurgy scientific research due to its time consuming. In the present work, molybdenum was determined by atomic absorption spectrometry indirectly and a rapid analysis method for molybdenum in molybdenum concentrate was proposed. The sample was dissolved by nitric acid, potassium chlorate and sulfuric acid, pH was adjusted by acetic acid and ammonium acetate buffer solution to pH 5~7, then a certain amount and excess of lead standard was added. Based on lead molybdate was considered as undissolved electrolyte on room temperature, the solubility of lead molybdate was 1.16×10-5g, far less than 0.01 g, was considered as the undissolved electrolyte, the electrolyte insoluble at a certain temperature can complete precipitation, usually compared with the solubility production product Qc and the relative size of constant Ksp, when Qc>Ksp, solution was supersaturated, precipitation was precipitate completely, the content of molybdenum in molybdenum concentrate was 40%~60%, the amount of lead was 0.125 0~0.150 0 g, took the minimum calculated solution lead molybdate ion product, Qc=[Pb2+][MoO2-4]=2.51×10-5,Ksp=1.0×10-13,QcKsp,Therefore lead molybdate precipitate can be precipitated completely, after dry filtered, the excess of lead ions were determined by atomic absorption spectrometry, the content of molybdenum was calculated by subtraction method. In this paper, the amount of acetic acid-ammonium acetate buffer solution, the amount of lead standard, time of lead molybdate precipitation, heating time and maximum amount of coexisting ions such as W6+, Sn4+, Cu2+, etc were investigated. Compared with lead molybdate gravimetric method, repeatedly washing, ashing and burning with lead molybdate were eliminated by proposed method, which was simple, easy to master and was able to cut the analysis time in half. The control experiments were conducted by lead molybdate gravimetric method and proposed method. After the results were implemented by mathematical statistics, it can be concluded that it had good accuracy and precision for the proposed method, which can be applied to rapid analysis of molybdenum in molybdenum concentrate for mineral processing and metallurgy.
Study on Adsorption and Desorption Characteristics of Cd2+ and Cu2+ on the Surface Sediments of Sanhuhekou of Yellow River by Using ICP-MS
Zuo H, Chen YZ, Chen JH, Guo Y, Wang RM, Fang F, Zhao JY and Liu Y
In order to study the interaction mechanism between Cd2+, Cu2+ and surface sediments in the upper reaches of the Yellow River, the surface sediment of Sanhuhekou (YRSSM) was chosen as research object with inductively coupled plasma mass spectrometry (ICP-MS) as analysis method. The adsorption reaction condition such as liquid-solid ratio, reaction time and pH were optimized, and the adsorption and desorption characteristics of Cd2+ and Cu2+ onto the surface sediments under the optimized experimental conditions were studied. The results showed that the adsorption capacity of Cu2+ was greater than that of Cd2+, the equilibrium absorption capacity were 0.88 and 0.13 mg·g-1 under each optimum experimental condition, respectively. The adsorptions of Cu2+ and Cd2+ were in accord with the pseudo-second-order kinetic, while adsorption rate of Cu2+ was also greater than that of Cd2+. The adsorption thermodynamics data were in accordance with the Freundlich model and the fitting. Results showed that the adsorption process of Cu2+ and Cd2+ belonged to the preferential adsorption, and were endothermic and spontaneous processes. The desorption process showed that the Elovich equation were suitable for Cd2+ and Cu2+ and belonged to the heterogeneous diffusion. Multi-ions competitive adsorption and desorption experiments indicated that Cu2+ was influenced more by co-existing ion. The study revealed not only the mechanism of adsorption and desorption between Cd2+, Cu2+ and surface sediment in Sanhuhekou, but also the influence of coexisting ions on the adsorption and desorption characteristics. The results demonstrated that the distribution mechanism of heavy metals between solid-liquid phases, and provided a theoretical basis for the migration ability of heavy metals. It also had a guiding significance for establishing heavy metals preventive and control measures of the study area.
Research on Straightness Error Compensation of Grating Ruling Machine
Huang YS, Dong CC, Huang YB, Sheng B, Zhou HY, Sun L, Yang HM and Zhang DW
Echelle grating is a kind of special diffraction grating. Working with high diffraction orders and big diffraction angle, which has the advantages of high resolution and full wave shining. It has been widely used in high-end spectrum instrument, which greatly promoted the development of aerospace, astronomy, medical, military, environment and other cutting-edge technology. However, professional scoring system needs to be customized, and the price is very expensive. The use of sophisticated ultra precision machining equipment to process in the ladder grating can greatly reduce the preparation cost of the mother plate of the ladder grating. Due to the bad straightness and high accumulative error of ultra precision single point diamond lathe, it can’t satisfy the demand of preparation when preparing the echelle grating, casuing the bad diffraction wave front. In order to reduce the straightness error, this paper comes up with the error compensation for the single point diamond lathe. Firstly, we make the first compensation based on the accumulative error curve. When the compensation ratio is 0.75 to 0.85, the peak valley value (pv) of the diffraction wave front is about 400 nm, reaching its greatest effect of the first straightness compensation. Secondly, we make the straightness compensation according to the diffraction wave front curve of the blazed order. The pv of the diffraction wave front is about 83nm. The results show that the diffraction wave front is greatly improved which is beneficial to improve the quality of the grating, and has a guiding role in the actual grating characterization.
Study on Emission Spectrum of Radicals in Remediation System of Polluted Soil with Pulsed Discharge Plasma in Oxygen
Zhou GS, Wang HJ, Wu QS and Guo H
Based on the advantage of spectroscopy method and the significant effect of ·OH and ·O in advanced oxidation degradation system, the change of relative emission spectra intensities of the ·OH and the ·O in a pulsed discharge plasma (PDP) system bubbled with oxygen were tested by using the spectrum detecting technique in this research. The PDP system with needle-to-net electrode was set up in the paper to remediate the polluted soil. The relative emission spectra intensities of the ·OH and the ·O formed in the PDP system with oxygen (O2) bubbling were detected with the spectrograph to illustrate the critical effect of the ·OH and the ·O on the organic compound degradation in the PDP system. The changes of the relative emission spectra intensities of the ·OH and the ·O under the conditions of without soil addition, with the original soil addition, with the organic compound polluted soil addition and with the organic compound-heavy metal polluted soil addition were firstly investigated in the paper. The effect of peak pulse voltage, electrode gap and O2 flow rate on the relative emission spectra intensities of the ·OH and the ·O were also studied to explain the changing rule of the active species in the PDP system. The obtained results show that the addition of soil are beneficial to the formation of the ·OH and the ·O in PDP system for the soil remediation. The relative emission spectra intensities of the ·OH and the ·O in the PDP system with organic compounds polluted soil addition were lower than those in the PDP system with the original soil addition, which proved the oxidation of the ·OH and the ·O on the organic compounds degradation in the remediation system, and the addition of heavy metal ions were favorable to the degradation of the organic compounds in the PDP system. Furthermore, the increase of the peak pulse voltage as well as theO2 flow rate was in favor of the formation of the ·OH and the ·O, while the relative emission spectra intensities of the ·OH and the ·O were lower under the condition of the higher electrode gap, which demonstrated that the higher electrode gap were not in favor of the active species formation. In the study, based on the description of the pivotal role of ·OH and the ·O in the PDP system for the polluted soil remediation, the influence rule of the main factors during the process of polluted soil remediation in the PDP system on the content of ·OH and the ·O were analyzed. This research will provide some basic experimental evidence for the application of PDP technology on the polluted soil remediation.
Comparative Study of Data Compression Methods for Large Aperture Static Imaging Spectrometer
Yu L, Liu XB, Li HB and Liu GZ
Facing the problem of choosing different data source as compressing object results in different compression effect, several techniques are investigated to explore a better data source which can reduce the loss of image and spectral information while getting higher compression ratio in the compression work of the large aperture static imaging spectrometer. In this paper the optical path difference dimension data source of LASIS was proposed after analyzing the characteristic of LASIS and then compared with the LASIS and LAMIS data source in detail. The SWIR data collected with the principle prototype of LASIS were used in our experiment. Firstly, three forms of data sources were extracted after detailedly introducing their data characteristic and extracting methods. Secondly, the mature algorithms in engineering JPEG and JPEG2000 were employed to compress and reconstruct the three forms of data sources respectively. Finally, the compression effect was evaluated in the aspect of image content, interference dimension, spectral dimension and compression ratio respectively, and the original spectral curves of three materials choosing from the field of view and those after reconstruction were extracted next, then the loss of spectral information of these three materials were measured by using the SA (Spectral Angle) and RQE (Relative Quadratic Error) values of the spectral curves to evaluate the compression effect. It is demonstrated that using the optical path difference dimension data as compressing object shows obvious advantages compared with LASIS and LAMIS, which achieves a combination of higher compression ratio, lower mean square error, lower peak signal noise ratio and less information loss that is competitive with the best results from the literature. The results show that the proposed optical path difference dimension data source has good performance in preserving the spatial and spectral information during the compression of LASIS than the other two common forms data sources of LASIS.
Study on Detection Sensitivity of Heavy Metal in Water Based on LIBS Combined with Electrode Enrichment Method
Wang YY, Zhao NJ, Ma MJ, Fang L, Yu Y, Meng DS, Gu YH, Jia Y, Liu JG and Liu WQ
In order to improve the detection sensitivity of laser-induced breakdown spectroscopy (LIBS) and lower the limit of the detection of elements, LIBS combined with Aluminum electrode enrichment method is adopted to analyze heavy metals such as Pb,Cdand Ni in the water. The relationship between the characteristic spectral intensity and the key parameters-voltage of electrode method is discussed, the spectral intensity increases first and then decreases with the increase of voltage. The spectral intensity reaches the maximum value when the enrichment voltage is 1.2 V while the optimal enrichment voltage value is 1.2 V. The stability of characteristic spectral lines of heavy metals is studied, and the relative standard deviation(RSD) of spectral intensity of Pb, Cd and Ni is 5.98%,4.25 % and 5.27% respectively, the result shows that the spectral line obtained by this method has high stability. A series of samples in the range of 0~0.13 mg·L-1 are prepared and quantitatively analyzed, the limit of detection of Pb, Cd and Ni is obtained 1.2,3.1 and 1.7 ppb respectively. The above result shows that LIBS combined with aluminum electrode enrichment method can effectively improve the stability of characteristic spectral lines and lower the limit of detection of Pb,Cd and Ni. This research also provides a method to further improve detection sensitivity of LIBS and analysis ability of heavy metal in the water.
The Research of Flatfielding Correction Method for Spatial Heterodyne Spectrometer at Systematic Level
Shi HL, Li ZW, Luo HY and Xiong W
It can’t satisfy the requirement of correction for response non-uniformity at systematic levelif only if the array detector for spatial heterodyne spectrometer is corrected. Traditional methods, such as irradiation with uniform source and column-flat-fielding, are not suitable for spatial heterodyne spectrometer. The article expounds convection arm-blocking method for spatial heterodyne spectrometer briefly at first. This method leads to kinds of mismatches including pixel and sub-pixel level shift and rotation in a single arm data after gluing gratings. The effect of registration accuracy of flatfielding coefficients has been analyzed for the experimental breadboard. The result shows that the registration accuracy of flatfielding coefficients needs to be better than 0.1 pixel for the breadboard. The shift at pixel level is calculated by solving the rotational degree by using logarithm-polar coordinate and phase correlation method for the requirement of registration. The shift at sub-pixel level is estimated with DFT based on matrix multiplication. The flow path of flatfielding method at systematic level is concluded. The integral condition of interferometer after actual gluing is modulated by adjusting the positions of gratings slightly. The flatfielding flow path is applied to the data acquired from the modulated interferometer after gluing. Then, the result is compared with the spectrum after the correction with totally matched signal arm data. The final result shows that the spectral deviation is 0.6% between the two spectra compared with the spectral deviation of 4.1% without correction. The accuracy of recovered spectrum after correction has been improved markedly. This can be the foundation for the follow data processing.
Preparation and Photocatalytic Activity of CeO2 Loaded Porous Alkali-Activated Steel Slag-Based Catalyst
Kang L, Zhang YJ, Zhang L, Zhang K and Yang MY
High value-added utilization of solid wastes is one of the important ways of sustainable development. A novel pore size-controlled alkali-activated steel slag-based cementitious material (PASSCM) was synthesized by adjusting the content of pore forming agent of acrylic resin emulsion. Meanwhiel, a new type of porous steel slag-based catalyst loaded CeO2 was prepared via incipient wetness impregnation method in the paper. The composition, structure and optical properties of photocatalysts were characterized with XRF, XRD, BET and UV-Vis DRS. Meanwhile, the photocatalytic performance of hydrogen production from water was evaluated. The results showed that adding pore-forming agent changed the pore structure and the mesoporous volume increased by 70.27% of alkali-activated steel slag-based cementitious material. The mesoporous volume increased by 144.14% in photocatalyst loaded 8 Wt% CeO2. In the simulated solar source irradiation for 6 h, the photocatalyst loaded 8wt%CeO2 exhibiting the highest photocatalytic hydrogen production activity (7 653 μmol·g-1) and hydrogen generation rate [1 275.5 μmol·(g·h)-1], which were attributed to mesoporous volume increases the mass transfer rate of the water molecules, and in the formation of the coupled semiconductors, the high dispersion of the CeO2 active component and the FeO in the carrier promoted the high efficiency separation of the photogenerated electron-hole pairs.
Multi-Band Texture Image Fusion Based on the Embedded Multi-Scale Decomposition and Possibility Theory
Lin SZ, Wang DJ, Wang XX and Zhu XH
The combination of multi-scale transform and the rules which are “high-frequency coefficients combined by selecting the maximum gray value or energy” and “low-pass ones combined by weighting average” is an effective method in dual-band image fusion. However, when these methods are used to fuse multi-band images, sequential weighted average often leads the weakening of the inherent different information of original images, which affects the subsequent target recognition and scene understanding. The problem is more obvious when fusing multi-band images with texture features. In order to describe the scene in a more comprehensive and precise way, a new multi-band texture image fusion method based on embedded multi-scale decomposition and possibility theory is proposed. The method consists of three parts. The original multi-band images are decomposed into their high- and low-frequency components through a multi-scale transform. The high-frequency components are fused per-pixel by extracting the maximum gray value, whereas the last layer of low-frequency components of original multi-band images with the largest standard deviation is blocked through the another multi-scale transform. Based on the specific sizes and positions of these blocks, the remaining two original images are divided. All the blocks from three bands are traversely fused according to the possibility theory, and the low-frequency image is formed by mosaicing these fused blocks. Then, this image is inversely transformed with its high-frequency counterparts to get the final fusion image. This method not only integrates the pixel-level with feature-level fusion methods, but also integrates the space domain with transform domain technologies together, and solves the problem of sawtooth effect on the edge of the target through the different fusion rules with the different sizes of blocks. The validity of the method proposed is proved.