scholarly journals Hyperspectral Characterization and Chlorophyll Content Inversion Study of Reclaimed Vegetation in Rare Earth Mines

2021 ◽  
Author(s):  
Hengkai Li ◽  
Feng Xu ◽  
Beibei Zhou ◽  
Zhian Wei
Keyword(s):  
Rare Earth ◽  
Chlorophyll Content ◽  
Spectral Characteristics ◽  
Visible Region ◽  
Small Sample ◽  
Spectral Variation ◽  
Estimation Model ◽  
Spectral Parameters ◽  
Network Algorithm ◽  
Sparse Autoencoder

Abstract Taking the Lingbei rare earth mining area in Dingnan county of Jiangxi Province as the research object of the reclaimed vegetation, the original spectrum, derivative spectrum and the continuum removed spectrum of the reclaimed vegetation were detected. The spectral characteristics and variation regularity of the typical reclaimed vegetation were analyzed, the correlation between chlorophyll content and spectral characteristic index of reclaimed vegetation was analyzed, and the sensitive spectral parameters were extracted. Partial Least Squares Algorithm, Back Propagation Neural Network Algorithm and Sparse Autoencoder Network Algorithm were selected to construct the estimation model of chlorophyll content, and compare the accuracy. The results show that; The vegetation spectrum of rare earth mine reclamation has the spectral characteristics of higher reflectance in visible region, red shift of green peak and red valley, blue shift of “red edge”, with less spectral variation in bamboo willow; Variability in the sensitive spectral parameters extracted from different vegetation; Sparse Autoencoder network algorithm is the optimal estimation model (R2 value of three vegetation is 0.9117,0.7418 and 0.9815 respectively). In the case of the small sample, it has higher estimation precision and universality for different reclaimed vegetation.

Kathodo- und Photolumineszenz der Seltenerd-aktivierten Wirtsgitter Ba2La2B2+Te2O12 (B = Zn, Mg)

1986 ◽  
Vol 41 (6) ◽  
pp. 866-870 ◽  
Author(s):  
H.-D. Autenrieth ◽  
S. Kemmler-Sack
Keyword(s):  
Electronic Structure ◽  
Rare Earth ◽  
Visible Region ◽  
Host Lattice ◽  
Rare Earth Ions ◽  
New Host ◽  
Emission Efficiency ◽  
Transfer Processes ◽  
Trivalent Rare Earth ◽  
Host Lattices

By activation of the new host lattices Ba2La2B2+Te2O12 (B = Zn, Mg) with trivalent rare earth ions Ln3+ = Pr. Sm, Eu, Tb, Dy, Ho, Tm an emission in the visible region is observed. The influence of the electronic structure and concentration on the relative emission efficiency as well as the host lattice participation in the energy transfer processes are discussed.

Effects of Long-Term Tracheostomy on Spectral Characteristics of Vowel Production

1991 ◽  
Vol 34 (5) ◽  
pp. 1057-1065 ◽  
Author(s):  
Ruth Saletsky Kamen ◽  
Ben C. Watson
Keyword(s):  
Vocal Tract ◽  
Spectral Characteristics ◽  
Group Differences ◽  
Vowel Production ◽  
Formant Frequency ◽  
Motor Patterns ◽  
Spectral Parameters ◽  
Oral Motor ◽  
Vowel Space

This study investigated the effects of long-term tracheostomy on the development of speech. Eight children who underwent tracheotomy during the prelingual period were compared to matched controls on selected spectral parameters of the speech acoustic signal and standard measures of oral-motor, phonologic, and articulatory proficiency. Analysis of formant frequency values revealed significant between-group differences. Children with histories of long-term tracheostomy showed reduced acoustic vowel space, as defined by group formant frequency values. This suggests that these children were limited in their ability to produce extreme vocal tract configurations for vowels /a,i,u/ postdecannulation. Oral motor patterns were less mature, and sound substitutions were not only more variable for this group, but also reflected a persistent overlay of maladaptive compensations developed during cannulation.

Preparation, Characterization and its Photocatalytic Performance of Rare Earth Element Erbium Doped with TiO2 Material

2012 ◽  
Vol 568 ◽  
pp. 380-383
Author(s):  
Song Tian Li ◽  
Guo Xu He ◽  
Wei Ma ◽  
Yan Hua Liu
Keyword(s):  
Titanium Dioxide ◽  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Photocatalytic Performance ◽  
Sol Gel ◽  
Visible Region ◽  
Erbium Doped ◽  
Sol Gel Process ◽  
Reduce Energy Consumption

In order to expand photoresponse range of TiO2, reduce energy consumption of semiconductor material optical catalytic, certain amount of rare earth element Erbiun was doped during preparation of anatase titanium dioxide to improve the light absorption and photocatalysis efficiency. A series of rare earth element doped TiO2 material were prepared by sol-gel process, and characterized by means of UV-vis diffuse reflectance spectra. UV-vis absorption verified that doping of Er3+ enhanced absorptive capacity of catalyst in visible region. The photocatalytic performance of anatase titanium dioxide and rare earth element Erbiun doped with TiO2 to basic fuchsin were studied.

CHLOROPHYLL ANALYSIS OF WHOLE RAPESEED KERNELS BY NEAR INFRARED REFLECTANCE

1982 ◽  
Vol 62 (4) ◽  
pp. 875-884 ◽  
Author(s):  
RUSSELL TKACHUK ◽  
F. D. KUZINA
Keyword(s):  
Chlorophyll Content ◽  
Near Infrared ◽  
Good Accuracy ◽  
Visible Region ◽  
Infrared Region ◽  
Multiple Correlation Coefficient ◽  
Multiple Correlation ◽  
Near Infrared Reflectance ◽  
Laboratory Results ◽  
Near Infrared Region

Chlorophyll content was determined in whole rapeseed samples, from Regent and Candle cultivars, by using a reflectance technique in the visible and near infrared region. Chlorophyll content was estimated with good accuracy when predicted results for 42 samples of Regent, 37 samples of Candle and 79 samples for both cultivars combined were compared with standard laboratory results. For Regent, a multiple correlation coefficient (R) of 0.944 and a standard error of estimate (Sy) of 4.7 were obtained when reflectance was measured at six wavelengths. For Candle, R = 0.963 and Sy = 4.4, using another six wavelengths. For both cultivars combined, R = 0.939 and Sy = 4.8, again using a different set of six wavelengths. Wavelengths for predicting chlorophyll were selected from the 630-to 754-nm visible region, and from the 1640- to 2176-nm near infrared region. This reflectance method described for whole rapeseed is rapid, involves no sample preparation, and leaves the seed intact and available for other uses.

Electron Microprobe and Photoluminescence Analysis of Europium-Doped Gallium Nitride Light Emitters

2002 ◽  
Vol 743 ◽  
Author(s):  
R. W. Martin ◽  
S. Dalmasso ◽  
K. P. O'Donnell ◽  
Y. Nakanishi ◽  
A. Wakahara ◽  
...  
Keyword(s):  
Electron Beam ◽  
Rare Earth ◽  
Visible Region ◽  
Depth Profiling ◽  
Luminescence Spectra ◽  
Light Emitters ◽  
Doping Density ◽  
Annealing Conditions ◽  
Electron Transitions ◽  
Doped Glass

ABSTRACTRare-earth doped GaN structures offer potential for optical devices emitting in the visible region [1,2]. We describe a study of MOVPE grown GaN-on-sapphire epilayers implanted with Europium ions, producing characteristic red emission lines between 540 and 680 nm due to intra-4f(n) electron transitions. As-implanted and subsequently annealed samples are investigated using a combination of wavelength dispersive x-ray analysis (WDX), electron microscopy, cathodoluminescence (CL) and photoluminescence (PL). WDX is shown to be a powerful technique for quantifying rare-earth concentrations in GaN, with varying electron beam voltages allowing a degree of depth profiling, further enhanced by the simultaneous collection of room temperature luminescence (CL) from the analysed region [3]. The intensities of the sharp lines observed in the luminescence spectrum are compared to the doping density (between 1014 – 1015 cm−2) and the Eu content measured by WDX, using a Eu-doped glass standard. Differences observed in the luminescence spectra produced by laser and electron beam excitation will be discussed along with the importance of the annealing conditions, which “heal” defects visible in the electron micrographs.

Luminescence in the Visible Region from Annealed Thin ALD-ZnO Films Implanted with Different Rare Earth Ions

2018 ◽  
Vol 215 (16) ◽  
pp. 1700889 ◽  
Author(s):  
Renata Ratajczak ◽  
Elzbieta Guziewicz ◽  
Slawomir Prucnal ◽  
Grzegorz Łuka ◽  
Roman Böttger ◽  
...  
Keyword(s):  
Rare Earth ◽  
Visible Region ◽  
Rare Earth Ions ◽  
Zno Films

scholarly journals The Value of Sentinel-2 Spectral Bands for the Assessment of Winter Wheat Growth and Development

2019 ◽  
Vol 11 (17) ◽  
pp. 2050 ◽  
Author(s):  
Andrew Revill ◽  
Anna Florence ◽  
Alasdair MacArthur ◽  
Stephen Hoad ◽  
Robert Rees ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Chlorophyll Content ◽  
Management Practices ◽  
Near Infrared ◽  
Spectral Characteristics ◽  
Crop Management ◽  
Area Index ◽  
Spectral Bands ◽  
The Mean ◽  
Sentinel 2

Leaf Area Index (LAI) and chlorophyll content are strongly related to plant development and productivity. Spatial and temporal estimates of these variables are essential for efficient and precise crop management. The availability of open-access data from the European Space Agency’s (ESA) Sentinel-2 satellite—delivering global coverage with an average 5-day revisit frequency at a spatial resolution of up to 10 metres—could provide estimates of these variables at unprecedented (i.e., sub-field) resolution. Using synthetic data, past research has demonstrated the potential of Sentinel-2 for estimating crop variables. Nonetheless, research involving a robust analysis of the Sentinel-2 bands for supporting agricultural applications is limited. We evaluated the potential of Sentinel-2 data for retrieving winter wheat LAI, leaf chlorophyll content (LCC) and canopy chlorophyll content (CCC). In coordination with destructive and non-destructive ground measurements, we acquired multispectral data from an Unmanned Aerial Vehicle (UAV)-mounted sensor measuring key Sentinel-2 spectral bands (443 to 865 nm). We applied Gaussian processes regression (GPR) machine learning to determine the most informative Sentinel-2 bands for retrieving each of the variables. We further evaluated the GPR model performance when propagating observation uncertainty. When applying the best-performing GPR models without propagating uncertainty, the retrievals had a high agreement with ground measurements—the mean R2 and normalised root-mean-square error (NRMSE) were 0.89 and 8.8%, respectively. When propagating uncertainty, the mean R2 and NRMSE were 0.82 and 11.9%, respectively. When accounting for measurement uncertainty in the estimation of LAI and CCC, the number of most informative Sentinel-2 bands was reduced from four to only two—the red-edge (705 nm) and near-infrared (865 nm) bands. This research demonstrates the value of the Sentinel-2 spectral characteristics for retrieving critical variables that can support more sustainable crop management practices.

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