scholarly journals Multiangular spectra of tree bark for common boreal tree species in Europe

Silva Fennica ◽  
2020 ◽  
Vol 54 (4) ◽  
Author(s):  
Jussi Juola ◽  
Aarne Hovi ◽  
Miina Rautiainen
Keyword(s):  
Tree Species ◽  
Near Infrared ◽  
Wavelength Region ◽  
Tree Height ◽  
Interspecific Variation ◽  
Stem Bark ◽  
Tree Bark ◽  
Support Vector ◽  
Tree Structures ◽  
Infrared Wavelength

Despite the importance of spectral properties of woody tree structures, they are seldom represented in research related to forests, remote sensing, and reflectance modeling. This study presents a novel imaging multiangular measurement set-up that utilizes a mobile handheld hyperspectral camera (Specim IQ, 400–1000 nm), and can measure stem bark spectra in a controlled laboratory setting. We measured multiangular reflectance spectra of silver birch ( Roth), Scots pine ( L.) and Norway spruce ( (L.) Karst.) stem bark, and demonstrated the potential of using bark spectra in identifying tree species using a Support Vector Machine (SVM) based approach. Intraspecific reflectance variability was the lowest in visible (400–700 nm), and the highest in near-infrared (700–1000 nm) wavelength regions. Interspecific variation was the largest in the red, red-edge and near-infrared spectral bands. Spatial variation of reflectance along the tree height and different sides of the stem (north and south) were found. Both birch and pine had increased reflectance in the forward-scattering directions for visible to near-infrared wavelength regions, whilst spruce displayed the same only for the visible wavelength region. In addition, spruce had increased reflectance in the backward-scattering directions. In spite of the intraspecific variations, SVM could identify tree species with 88.8% overall accuracy when using pixel-specific spectra, and with 97.2% overall accuracy when using mean spectra per image. Based on our results it is possible to identify common boreal tree species based on their stem bark spectra using images from mobile hyperspectral cameras.Betula pendulaPinus sylvestrisPicea abies

Fabrication of a bilayer wire grid polarizer in the near infrared wavelength region by using a UV curing nanoimprinting method

2012 ◽  
Vol 61 (10) ◽  
pp. 1714-1719 ◽  
Author(s):  
Yong Ho Lee ◽  
Pazhanisami Peranantham ◽  
Chang Kwon Hwangbo ◽  
Seok-Min Kim
Keyword(s):  
Near Infrared ◽  
Wavelength Region ◽  
Uv Curing ◽  
Wire Grid ◽  
Infrared Wavelength ◽  
Wire Grid Polarizer

Tunable photoluminescence from the visible to near-infrared wavelength region of non-stoichiometric AgInS2 nanoparticles

2012 ◽  
Vol 22 (25) ◽  
pp. 12851 ◽  
Author(s):  
Meilin Dai ◽  
Shoji Ogawa ◽  
Tatsuya Kameyama ◽  
Ken-ichi Okazaki ◽  
Akihiko Kudo ◽  
...  
Keyword(s):  
Near Infrared ◽  
Wavelength Region ◽  
Infrared Wavelength

Analysis and Optimisation of Two-Dimensional Silicon Complex Grating With Different Ridge Heights or Groove Depths for Solar Cells

2013 ◽  
Author(s):  
Pingping Li ◽  
Qiang Cheng ◽  
Hao Wu ◽  
Jinlin Song ◽  
Huaichun Zhou
Keyword(s):  
Solar Cells ◽  
Near Infrared ◽  
Fdtd Method ◽  
Wavelength Region ◽  
Normal Incidence ◽  
Groove Depth ◽  
Radiative Properties ◽  
Two Dimensional ◽  
Infrared Wavelength ◽  
Solar Absorber

In this study, two kinds of two-dimensional (2D) complex gratings are proposed for a potential application as absorbing surfaces for solar cells in the visible and near-infrared wavelength regions, which are based on the superposition of multiple 2D simple gratings with different ridge heights for convex gratings or different groove depths for concave gratings, respectively. Silicon is selected as the complex grating material because it is common in micro/nanofabrication. Compared with one-dimensional (1D) gratings, the new structures present excellent radiative properties to rays from all directions. Besides, the new gratings can achieve satisfactory performance under both TM and TE waves, which cannot be easily obtained by 1D gratings. Furthermore, these two kinds of 2D complex gratings can both achieve higher absorptance in the whole of the interested spectral range by making full use of the microcavity resonance than 2D simple gratings with the same ridge height or groove depth. Taguchi method is employed as an efficient way of searching for the optimal profiles for the 2D complex gratings. The average spectral absorptance of the optimized structure for the 2D complex convex grating with two different ridge heights is above 0.93 within wavelength region from 0.3 to 1.1 μm for both TM and TE waves under normal incidence, which suggests that the proposed structures can be well suitable for solar absorber applications. The Finite-different time-domain (FDTD) method is used for all numerical calculations to obtain spectral absorptance of different structures.

scholarly journals Selection of Optimal Hyperspectral Wavebands for Detection of Discolored, Diseased Rice Seeds

2019 ◽  
Vol 9 (5) ◽  
pp. 1027 ◽  
Author(s):  
Insuck Baek ◽  
Moon Kim ◽  
Byoung-Kwan Cho ◽  
Changyeun Mo ◽  
Jinyoung Barnaby ◽  
...  
Keyword(s):  
High Throughput Screening ◽  
Near Infrared ◽  
Multispectral Imaging ◽  
Wavelength Region ◽  
Support Vector ◽  
Rice Grain ◽  
Rice Seed ◽  
Forward Selection ◽  
Burkholderia Glumae ◽  
Rice Seeds

The inspection of rice grain that may be infected by seedborne disease is important for ensuring uniform plant stands in production fields as well as preventing proliferation of some seedborne diseases. The goal of this study was to use a hyperspectral imaging (HSI) technique to find optimal wavelengths and develop a model for detecting discolored, diseased rice seed infected by bacterial panicle blight (Burkholderia glumae), a seedborne pathogen. For this purpose, the HSI data spanning the visible/near-infrared wavelength region between 400 and 1000 nm were collected for 500 sound and discolored rice seeds. For selecting optimal wavelengths to use for detecting diseased seed, a sequential forward selection (SFS) method combined with various spectral pretreatments was employed. To evaluate performance based on optimal wavelengths, support vector machine (SVM) and linear and quadratic discriminant analysis (LDA and QDA) models were developed for detection of discolored seeds. As a result, the violet and red regions of the visible spectrum were selected as key wavelengths reflecting the characteristics of the discolored rice seeds. When using only two or only three selected wavelengths, all of the classification methods achieved high classification accuracies over 90% for both the calibration and validation sample sets. The results of the study showed that only two to three wavelengths are needed to differentiate between discolored, diseased and sound rice, instead of using the entire HSI wavelength regions. This demonstrates the feasibility of developing a low cost multispectral imaging technology based on these selected wavelengths for non-destructive and high-throughput screening of diseased rice seed.

Imaging magnetographs for high-resolution solar observations in the visible and near-infrared wavelength region

2003 ◽  
Vol 324 (4) ◽  
pp. 332-333 ◽  
Author(s):  
C. Denker ◽  
L. Didkovsky ◽  
J. Ma ◽  
S. Shumko ◽  
J. Varsik ◽  
...  
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Wavelength Region ◽  
Infrared Wavelength ◽  
Solar Observations

Ultra-Small Photonic-Crystal-Waveguide-Based Y-Splitters Useful in the Near-Infrared Wavelength Region

2004 ◽  
Vol 43 (No. 4A) ◽  
pp. L446-L448 ◽  
Author(s):  
Kuon Inoue ◽  
Yoshimasa Sugimoto ◽  
Naoki Ikeda ◽  
Yu Tanaka ◽  
Kiyoshi Asakawa ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Near Infrared ◽  
Wavelength Region ◽  
Photonic Crystal Waveguide ◽  
Infrared Wavelength

Highly Transparent Y-α-Sialon by Hot Pressing

2011 ◽  
Vol 148-149 ◽  
pp. 599-602
Author(s):  
Ying Chun Shan ◽  
Hui Ye ◽  
Jiu Jun Xu ◽  
Jiang Tao Li
Keyword(s):  
Hot Pressing ◽  
Single Phase ◽  
Near Infrared ◽  
Wavelength Region ◽  
High Hardness ◽  
Optical Transmittance ◽  
Nitrogen Atmosphere ◽  
Infrared Wavelength ◽  
Dense Microstructure ◽  
Equiaxed Grain

The single-phase Y-α-sialon ceramics with highly optical transmittance were produced by hot pressing starting mixtures of Si3N4, AlN, Al2O3and Y2O3at 1900 °C for 0.5 h in a nitrogen atmosphere. The resultant sialon shows very high optical transparency in the near infrared wavelength region, about 70% for 0.8 mm thickness. In addition to highly transmittance, the Y-α-sialon also show high hardness (19 GPa) and well fracture toughness (4 MPa•m1/2), which attribute to the compound microstructure of uniform, equiaxed grain with a grain size of 2 μm and small aspect ration elongated α-sialon (<2) with a length no more than 5 μm. The high transparent was attribute to the uniform dense microstructure and pure single-phase α-sialon.

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