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spectral characteristics of LiSrBO_3:Tb^(3+) Green Phosphor

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Chemical Research in Chinese Universities 2009年第5期25卷 610-613页

作者： LI Pan-lai WANG Zhi-jun YANG Zhi-ping GUO Qing-lin College of Physics Science ＆ Technology Hebei University Baoding 071002 P. R. China

LiSrBO3：Tb^3＋ green phosphor was synthesized by means of a solid state reaction and its spectral characteristics were studied. The emission spectrum of LiSrBO3：Tb^3＋ consists of four major bands at 486, 544, 595 and 620 nm under the excitation of near ultraviolet irradiation, which are originated from the ^5Da→^7F6, ^5D4→^7F5, ^5D4→^7F4 and ^5D4→^7F3 characteristic transitions of Tb^3＋, respectively. Monitored at 544 nm, the excitation spectrum of the phosphor extends from 220 nm to 390 nm, with the excitation peaks centered at 242, 277, 368 and 381 nm, respectively. The effect of Tb^3＋ concentration on the emission intensity of LiSrBO3：Tb^3＋ was also investigated. The results show that firstly the intensity increases with increasing Tb^3＋ concentration, reaches a maximum value at 3%（molar fraction） Tb^3＋ and then decreases, showing a concentration self-quenching, whose mechanism is proposed as a d-d interaction based on Dexter theory. The emission intensity of LiSrBO3：Tb^3＋ was enhanced by co-doping Li^＋, Na^＋ and K^＋.

关键词： LiSrBO3:Tb^3+ Green phosphor spectral characteristics

Relationship between Environmental Pollution of Coal Mine and spectral characteristics of Nearby Plants

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Journal of University of Science and Technology Beijing 2001年第1期8卷 10-14页

作者： Liqing Lei Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China Inst. of Geogr. Sci./Nat. Rsrc. Res. Chinese Academy of Sciences Beijing 100101 China

Remote sensing technology, as the most advanced method for collecting data, along with the common ways often used in the past on research of environmental science, was integrated to study the relationship between environmental pollution of coal mine and spectral characteristics of nearby plants. With compositive index and mean reflectivity at near infrared, a regression equation was established, and a conclusion was made that spectral reflectivity can be used to distinguish regions with different pollution degree. Through testing with real status of the research region, it is verified that this kind of integration and conclusion not only are helpful for human being in controlling the movement law of pollutants and the corresponding change of coal mine environmental quality but also bring a new way for the research of environment problems of coal mine.

关键词： remote sensing spectral characteristics reflectivity pollution index compositive index atmospheric pollution

Growth,structure and spectral characteristics of KEr_(0.1)Yb_(0.9)(WO_4)_2 laser crystal

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Journal of Rare Earths 2010年第1期28卷 48-53页

作者：张莹刘景和曾繁明林海李春王成伟张学建秦杰明 College of Materials Science and Engineering Changchun University of Science and Technology

The 10 at.% Er3+-doped KYb(WO4)2(KEr0.1Yb0.9(WO4)2) laser crystal with dimensions up to 25 mm×15 mm×10 mm was grown by the Kyropoulos *** crystal structure was identified as β-KEr0.1Yb0.9(WO4)2 by XRD *** TG-DTA curves,the melting point and transition point of the crystal were determined to be 1058 and 1031 °C,*** spectrum and Raman spectrum were measured,and the vibration frequencies of infrared and Raman active modes for the crystal were *** absorption cross ...

关键词： Er3+-doped potassium ytterbium tungstate Kyropoulos method structure spectral characteristics rare earths

Preparation, spectral characteristics and photocatalytic activity of Eu^(3+)-doped WO_3 nanoparticles

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Journal of Rare Earths 2011年第8期29卷 727-731页

作者：王聪曹林 School of Materials Science and Engineering University of Science and Technology Beijing

Eu3＋-WO3 nanoparticles were successfully prepared by the modified method of Pechini. The prepared samples were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, high resolution transmission electron microscopy （HRTEM）, and UV-vis spectroscopy. Results showed that the Eu3＋-WO3 nanoparticles, which had an average external diameter of 10–25 nm, were composed of the different shapes of puncheon and catenary after being pretreated by pH, pressure vessal, and surfactant. Moreover, structural transformation matrix contained different crystals of anorthic and orthorhombic structure. The photocatalytic activities of the nanoparticles were evaluated by photocatalytic decomposition of rhodamine B. Eu3＋-WO3 nanoparticles were more efficient than WO3 and TiO2 on sunlight use ratio. Photocatalysis experiments indicated that the Eu3＋-WO3 nanoparticles exhibited the highest photocatalytic activity.

关键词： structural transformation spectral characteristics photocatalysis Eu3+-WO3 rare earths

spectral characteristics OF RAMAN EMISSIONS FROM MINIATURE OPTICALLY PUMPED FAR INFRARED LASER

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SPECTRAL CHARACTERISTICS OF RAMAN EMISSIONS FROM MINIATURE O...

spectral Reflectance characteristics of Different Snow and Snow-Covered Land Surface Objects and Mixed Spectrum Fitting

1998 International Conference on Microwave and Millimeter Wave Technology

作者： Xingshi Zheng Jiayin Qin Xiao Huang Xizhang Luo Yikun Lin Zhongshan University

ISBN: (纸本)0780343085

＜正＞A miniature FIR laser with a sample-tube in 10 or 20cm length were constructed,and the laser’s cavity consisted of a pair of metallic meshes,with NH3 or CH30H molecules as active medium pumped by a TEA-CO2 laser,a series of FIR laser lines were *** taking account of the properties of the Fabry-Perot cavity and the gain characteristics of Raman transitions in the miniature optically pumped FIR laser,the spectral characteristics of the FIR laser were studied.

关键词： Raman lasers optical pumping submillimetre wave lasers laser cavity resonators Fabry-Perot resonators gas lasers spectral characteristics Raman emissions optically pumped far infrared laser laser cavity metallic meshes active medium Fabry-Perot cavity gain characteristics 10 cm 20 cm NH/sub 3/

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光谱学与光谱分析 2011年第9期31卷 2499-2502页

作者： ZHANG Jia-hua ZHOU Zheng-ming WANG Pei-juan YAO Feng-mei Liming Yang Chinese Academy of Meteorological Sciences 13eijing 100081 China Center for Earth Observation and Digital Earth Chinese Academy of Sciences Beijing 100094 China College of Earth Sciences Chinese Academy of Sciences Beijing 100049 China U.S. Geological Survey Center for Earth Resources Observation and Science Sioux Falls South Dakota 57198 USA

The field spectroradiometer was used to measure spectra of different snow and snow-covered land surface objects in Beijing *** result showed that for a pure snow spectrum,the snow reflectance peaks appeared from visible to 800 nm band locations;there was an obvious absorption valley of snow spectrum near 1 030 nm *** with fresh snow,the reflection peaks of the old snow and melting snow showed different degrees of decline in the ranges of 300～1 300,1 700～1 800 and 2 200～2 300 nm,the lowest was from the compacted snow and frozen *** the vegetation and snow mixed spectral characteristics,it was indicated that the spectral reflectance increased for the snow-covered land types(including pine leaf with snow and pine leaf on snow background), due to the influence of snow background in the range of 350～1 300 ***, the spectrum reflectance of mixed pixel remained a vegetation spectral *** the end,based on the spectrum analysis of snow,vegetation,and mixed snow/vegetation pixels,the mixed spectral fitting equations were established,and the results showed that there was good correlation between spectral curves by simulation fitting and observed ones(correlation coefficient R2=0.950 9).

关键词： Snow Snow-covered land surface object spectral characteristics spectral fitting

spectral characteristics Comparison of Two Summer Corn Cultivars under Different Fertilization Treatments

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Asian Agricultural Research 2017年第11期9卷 58-61页

作者： Luyan NIU Fengyun WANG Jiabo SUN Jiye ZHENG Xiaoyan ZHANG Institute of Science and Technology Information Shandong Academy of Agricultural Sciences

This study is aimed to explore the spectrum reflection characteristics of summer corn leaves in different fertilization *** hyperspectral remote sensing technology,the experiments were conducted in fields to collect the hyperspectral images of Denghai 605( DH605) and Ludan 981( LD981) in different growth period under five fertilization treatments,and then the reflectance of corn ear leaves was extracted by ENVI software. The five fertilization treatments included the control( CK) with no fertilization,40 kg and 30 kg of controlled-release fertilizer per 666. 67 m2 as base( K40 and K30),50 kg and 40 kg of compound fertilizer per 666. 67 m2 as base with 15 kg urea as seed fertilizer( F50 + N and F40 + N). The reflectance spectrums of the two corn cultivars under different fertilization treatments showed the approximately same changing trend with a reflection peak at green band( 550 nm) and a higher reflection platform at near infrared band( 760 nm-1050 nm). At the heading to filling stage,the reflectance of DH605 and LD981 was the highest under the CK,followed by the K30 and F40 + N respectively. At the filling to dough stage,the reflectance of DH605 and LD981 was the highest under the treatment K30 and F40 + N respectively,which was obviously higher than that of the other treatments. In the conditions of compound fertilizer,except the late filling stage,LD981 had little higher reflectance than DH605 at the other stages. In the conditions of controlled-release fertilizer and at dough to mature stage,LD981 had obviously higher reflectance compared to the other stages,and also higher than that of DH605; there was not obvious difference in reflectance LD981 and DH605 at the other stages.

关键词： Fertilization Summer corn Ear leaf spectral reflectance spectral characteristics

Experimental investigation of spectral evolution in flash radiation by hypervelocity impact on aluminum plates

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Defence Technology（防务技术） 2024年第7期37卷 96-110页

作者： Xing Chen Yonggang Lu Zhiwen Li Zhonghua Cui Institute of Systems Engineering China Academy of Engineering PhysicsMianyang 621900SichuanChina Chongqing Qianwei Technology Group Co. LtdChongqing 401121China

In this study,a series of hypervelocity impact tests were carried out based on a two-stage light gas gun,and the sequence spectrum and radiation evolution data of the impact products under different impact conditions were *** diameter of the projectile is 3-5 mm,the impact velocity is 3.13-6.58 km/s,and the chamber pressure is 0.56-990 *** spectrum of ejected debris cloud in the 250-310 nm band were obtained using a transient spectral measurement system and a multi-channel radiometer measurement *** test results reveal that the flash radiation intensity increases as a power function with the kinetic energy of the ***,the peak value of the line spectrum decreases as the chamber vacuum degree increases,while the radiation width gradually *** line spectrum in the spectral characterization curve corresponds to the ejected debris clouds splitting phase,which does not produce significant line spectrum during material fragmentation and is dominated by the continuum spectrum produced by blackbody *** will appear one or three characteristic peaks in the flash radiation time curve,the first and second peaks correspond to the penetration phase and the third peak corresponds to the expansion phase of the ejected debris clouds on the time scale,the first and second peaks are more sensitive to the chamber vacuum degree,and when the pressure is higher than 99 Pa,the first and second characteristic peaks will *** radiant heat attenuation of the flash under different impact conditions is significantly different,the attenuation exponent has a power function relationship with the impact velocity and the chamber vacuum degree,while the attenuation exponent has a linear relationship with the diameter of the projectile,the specific expression of the attenuation exponent is obtained by *** findings from this research can serve as a valuable reference for remote diagnostic technologies based on flash radiation characte

关键词： Hypervelocity impact Flash radiation Evolution spectral characteristics Damage evaluation

Mellin Transform-Based Correction Method for Linear Scale Inconsistency of Intrusion Events Identification in OFPS

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Photonic Sensors 2018年第3期8卷 220-227页

作者： Baocheng WANG Dandan QU Qing TIAN Liping PANG School of Computer North China University of Technology Beijing 100144 China School of Electrical and Information Engineering North China University of Technology Beijing 100144 China School of Aviation Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100191China

For the problem that the linear scale of intrusion signals in the optical fiber pre-warning system （OFPS） is inconsistent, this paper presents a method to correct the scale. Firstly, the intrusion signals are intercepted, and an aggregate of the segments with equal length is obtained. Then, the Mellin transform （MT） is applied to convert them into the same scale. The spectral characteristics are obtained by the Fourier transform. Finally, we adopt back-propagation （BP） neural network to identify intrusion types, which takes the spectral characteristics as input. We carried out the field experiments and collected the optical fiber intrusion signals which contain the picking signal, shoveling signal, and running signal. The experimental results show that the proposed algorithm can effectively improve the recognition accuracy of the intrusion signals.

关键词： Linear scale OFPS MT BP neural network spectral characteristics