scholarly journals Methodological Basis of The UAVs Use for the Weed Detection

2018 ◽  
Keyword(s):  
Electromagnetic Waves ◽  
Near Infrared ◽  
Classification Method ◽  
Likelihood Method ◽  
Cultivated Plants ◽  
Visible Range ◽  
Infrared Range ◽  
Weed Detection ◽  
Weight Method ◽  
Remote Observation

Purpose. To work out methodological approaches to the use of quadcopters for weeds assesment. Methods. The shooting was carried out using DJI Phantom Vision 2+ and LadyBug Copper Dot. The LadyBug was shoted in the visible and near-infrared range using the 12-megapixel S100 NDVI UAV-Kit camera with elevations: 20 m, 40 m and 60 m. The DJI Phantom Vision 2+ was shot in the visible range of the GoPro 14 megapixel camera altitudes: 10 m, 15 m, 30 m and 60 m. Decryption of photographs was carried out using the controlled classification method in QGIS and TNTmips programs. Weed accounting was performed on control sites 1m2 by weight method, taking into account their qualitative composition. Results. It is shown that the best results of weed recognition during decoding of images was obtained by the use of controlled classification according to the maximum likelihood method under conditions of shooting from heights up to 40 m. In order to improve the recognition of weeds and separate their image from images of cultivated plants, it is expedient to use the object-oriented analysis. At the stage of sunflower budding, about 30% of the weeds are closed from the remote observation, which led to an automatic underestimation of number of weeds. Conclusions. In order to evaluate the crop contamination, it is possible to successfully use the data from UAVs in a visible range of electromagnetic waves under low altitudes (up to 40 meters) and the use of a controlled classification method for decoding images. For the recognition of weeds, the images in the infrared range do not have advantages over images in the visible range. It is necessary to additionally apply ground-based control of weeds to assess the proportion of "hidden" from remote observation of weeds.

scholarly journals Photometric Observations of Aerosol Optical Properties and Emission Flux Rates of Stromboli Volcano Plume during the PEACETIME Campaign

2021 ◽  
Vol 13 (19) ◽  
pp. 4016
Author(s):  
Pasquale Sellitto ◽  
Giuseppe Salerno ◽  
Jean-François Doussin ◽  
Sylvain Triquet ◽  
François Dulac ◽  
...  
Keyword(s):  
Optical Properties ◽  
Near Infrared ◽  
Visible Range ◽  
Infrared Range ◽  
Emission Flux ◽  
Stromboli Volcano ◽  
Aerosol Emission ◽  
Photometric Observations ◽  
Sulphate Aerosols ◽  
Aerosol Emissions

The characterisation of aerosol emissions from volcanoes is a crucial step towards the assessment of their importance for regional air quality and regional-to-global climate. In this paper we present, for the first time, the characterisation of aerosol emissions of the Stromboli volcano, in terms of their optical properties and emission flux rates, carried out during the PEACETIME oceanographic campaign. Using sun-photometric observations realised during a near-ideal full plume crossing, a plume-isolated aerosol optical depth of 0.07–0.08 in the shorter-wavelength visible range, decreasing to about 0.02 in the near infrared range, was found. An Ångström exponent of 1.40 ± 0.40 was also derived. This value may suggest the dominant presence of sulphate aerosols with a minor presence of ash. During the crossing, two separate plume sections were identified, one possibly slightly affected by ash coming from a mild explosion, and the other more likely composed of pure sulphate aerosols. Exploiting the full crossing scan of the plume, an aerosol emission flux rate of 9–13 kg/s was estimated. This value was 50% larger than for typical passively degassing volcanoes, thus pointing to the importance of mild explosions for aerosol emissions in the atmosphere.

scholarly journals Astaxanthin as a new Raman probe for biosensing of specific subcellular lipidic structures: can we detect lipids in cells under resonance conditions?

2020 ◽  
Author(s):  
Krzysztof Czamara ◽  
Adriana Adamczyk ◽  
Marta Stojak ◽  
Basseem Radwan ◽  
Malgorzata Baranska
Keyword(s):  
Near Infrared ◽  
Resonance Excitation ◽  
Live Cells ◽  
Visible Range ◽  
Infrared Range ◽  
Dependent Manner ◽  
Chromophore Group ◽  
Group A ◽  
Raman Probe ◽  
Near Infrared Range

AbstractHere we report a new Raman probe for cellular studies on lipids detection and distribution. It is (3S, 3'S)-astaxanthin (AXT), a natural xanthophyll of hydrophobic properties and high solubility in lipids. It contains a chromophore group, a long polyene chain of eleven conjugated C=C bonds including two in the terminal rings, absorbing light in the visible range that coincides with the excitation of lasers commonly used in Raman spectroscopy for studying of biological samples. Depending on the laser, resonance (excitation in the visible range) or pre-resonance (the near infrared range) Raman spectrum of astaxanthin is dominated by bands at ca. 1008, 1158, and 1520 cm−1 that now can be also a marker of lipids distribution in the cells. We showed that AXT accumulates in lipidic structures of endothelial cells in time-dependent manner that provides possibility to visualize e.g. endoplasmic reticulum, as well as nuclear envelope. As a non-toxic reporter, it has a potential in the future studies on e.g. nucleus membranes damage in live cells in a very short measuring time.

Progress in design, nanofabrication and performance of metalenses

2021 ◽  
Author(s):  
Zhenghao WANG ◽  
Yongling WU ◽  
Dongfeng QI ◽  
Wenhui YU ◽  
Hongyu ZHENG
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Visible Range ◽  
Infrared Range ◽  
High Dispersion ◽  
High Resolution Imaging ◽  
Direct Writing ◽  
Nanoscale Structures ◽  
Resolution Imaging ◽  
And Performance

Abstract Metalens has been shown to overcome the diffraction limit of conventional optical lenses to achieve sub-wavelength resolution. Due to its planar structure and lightweight, metalens has the potential applications in the manufacture of flat lenses for cameras and other high resolution imaging optics. However, currently reported metalenses have low focusing efficiencies: 26% - 68% in THz and GHz range, 1% - 91% in near infrared range (NIR), and 5% - 91.6% in the visible range. Far field imaging in the visible light is essential for use in camera and mobile phones, which requires a complex metalens structure with multi-layers of alternating metal and dielectric layers. Most of the reported metalenses work in a single wavelength, mainly due to the high dispersion characteristics of the diffractive metalenses. It remains a challenge to realize high resolution imaging for a wide wavelength band in particular in the visible range. In this review, we report the state-of-the-art in metalens design principle, types of nanoscale structures, and various fabrication processes. We introduce femtosecond laser direct writing based on two-photon polymerization as an emerging nanofabrication technology. We provide an overview of the optical performance of the recently-reported metalenses and elaborate the major research and engineering challenges and future prospects.

scholarly journals Ga-Doped ZnO Coating—A Suitable Tool for Tuning the Electrode Properties in the Solar Cells with CdS/ZnS Core-Shell Quantum Dots

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 137
Author(s):  
Mariya Aleksandrova ◽  
Tatyana Ivanova ◽  
Velichka Strijkova ◽  
Tsvetozar Tsanev ◽  
Ajaya Kumar Singh ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Quantum Dots ◽  
Solar Cells ◽  
Indium Tin Oxide ◽  
Near Infrared ◽  
Optical Transmittance ◽  
Visible Range ◽  
Infrared Range ◽  
Layer System ◽  
Doped Zno

Two layer system from sputtered indium tin oxide (ITO) and gallium doped zinc oxide (Ga:ZnO, GZO) were studied for transparency in the visible electromagnetic range, reflectivity in the near infrared range, conductivity and valent band for a solar cells with quantum dots. The bi-layer coatings produced at optimized oxygen partial pressure, films thickness and surface roughness exhibit improved optical properties without worsening the electrical parameters, even if additional oxygen introduction during the reactive sputtering of the GZO. With an average optical transmittance of 91.3% in the visible range, average reflection and resistivity lower than 0.4 × 10−2 Ω.cm, these coatings are suitable for top electrode in the solar cells. The obtained results reveal that multilayered stacks of transparent ITO/Ga-doped ZnO coatings possess relatively low surface roughness (7–9 nm) and appropriate refractive index. The additional oxidation of GZO films induces modification of the film thickness and respectively of their optical performances.

scholarly journals Detection of Stress in Cotton (Gossypium hirsutum L.) Caused by Aphids Using Leaf Level Hyperspectral Measurements

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2798 ◽  
Author(s):  
Tingting Chen ◽  
Ruier Zeng ◽  
Wenxuan Guo ◽  
Xueying Hou ◽  
Yubin Lan ◽  
...  
Keyword(s):  
Near Infrared ◽  
Short Wave ◽  
Visible Range ◽  
Infrared Range ◽  
Spectral Indices ◽  
Cotton Aphid ◽  
Simple Method ◽  
Aphid Infestation ◽  
Chl A ◽  
Leaf Level

: Remote sensing can be a rapid, accurate, and simple method for assessing pest damage on plants. The objectives of this study were to identify spectral wavelengths sensitive to cotton aphid infestation. Then, the normalized difference spectral indices (NDSI) and ratio spectral indices (RSI) based on the leaf spectrum were obtained within 350–2500 nm, and their correlation with infestation were qualified. The results showed that leaf spectral reflectance decreased in the visible range (350–700 nm) and the near-infrared range (NIR, 700–1300 nm) as aphid damage severity increased, and significant differences were found in blue, green, red, NIR and short-wave infrared (SWIR) band regions between different grades of aphid damage severity. Decrease in Chlorophyll a (Chl a) pigment was more significant than that in Chlorophyll (Chl b) in the infested plants and the Chl a/b ratio showed a decreasing trend with increase in aphid damage severity. The sensitive spectral bands were mainly within NIR and SWIR ranges. The best spectral indices NDSI (R678, R1471) and RSI (R1975, R1904) were formulated with these sensitive spectral regions through reducing precise sampling method. These new indices along with 16 other stress related indices compiled from literature were further tested for their ability to detect aphid damage severity. The two indices in this study showed significantly higher coefficients of determination (R2 of 0.81 and 0.81, p < 0.01) and the least RMSE values (RMSE of 0.50 and 0.49), and hence have potential application in assessing aphid infestation severity in cotton.

scholarly journals Plasmonic Elliptical Nanohole Arrays for Chiral Absorption and Emission in the Near-Infrared and Visible Range

2021 ◽  
Vol 11 (13) ◽  
pp. 6012
Author(s):  
Emilija Petronijevic ◽  
Ramin Ghahri ◽  
Concita Sibilia
Keyword(s):  
Near Infrared ◽  
Plane Waves ◽  
Polarization Degree ◽  
Visible Range ◽  
Infrared Range ◽  
Excitation Wavelength ◽  
Plasmonic Nanostructures ◽  
Large Set ◽  
Absorption And Emission ◽  
Nanohole Arrays

Chiral plasmonic nanostructures with tunable handedness-dependent absorption in the visible and infrared offer chiro-optical control at the nanoscale. Moreover, coupling them with emitting layers could lead to chiral nanosources, important for nanophotonic circuits. Here, we propose plasmonic elliptical nanohole arrays (ENHA) for circularly dependent near-infrared and visible emission. We first investigate broadband chiral behavior in an Au-ENHA embedded in glass by exciting it with plane waves. We then study the coupling of ENHA with a thin emitting layer embedded in glass; we focus on the emission wavelengths which provided high chirality in plane-wave simulations. Our novel simulation set-up monitors the chirality of the far-field emission by properly averaging a large set of homogeneously distributed, randomly oriented quantum sources. The intrinsic chirality of ENHA influences the circular polarization degree of the emitting layer. Finally, we study the emission dependence on the field distribution at the excitation wavelength. We demonstrate the chiral absorption and emission properties for Au-ENHA emitting in the near-infrared range, and for Ag-ENHA which is excited in green range and emits in the Lumogen Red range. The simple geometry of ENHA can be fabricated with low-cost nanosphere lithography and be covered with emission gel. We thus believe that this design can be of great importance for tunable chiral nanosources.

scholarly journals Nano Gold Spheres and Rods: Synthesis and Characterization

2021 ◽  
Vol 2114 (1) ◽  
pp. 012032
Author(s):  
Saif M. Ali ◽  
Logean Qadri Al-Karam
Keyword(s):  
Near Infrared ◽  
Visible Range ◽  
Infrared Range ◽  
Nano Gold ◽  
Atomic Force ◽  
Transmission Electron ◽  
Three Samples ◽  
Uv Visible ◽  
Shape Sphere ◽  
Two Peaks

Abstract The present study aims to synthesised nano gold with chemical method with two shape sphere and rod with multi diameter and aspect ratio and then characterize the synthesised material with Atomic Force Microscope (AFM), Transmission Electron Microscope (TEM) and Ultraviolet-visible (UV–Visible ) spectrophotometer. The AFM and TEM characterization result of three samples for each sphere and rods show that the synthesised material are in nano range with diameter 31.9 nm, 36.19 nm and 79.37 nm respectively for nano sphere and diameters 39.9nm, 36.05 nm and 28 nm respectively for nano-rods samples and the UV-Visible spectrophotometer show that peak of surface plasmon resonance of nano-sphere are at wavelengths 532 nm, 535 nm and 546 nm and all are in the visible range and nano-rod have two peaks one in the visible range at wavelengths 525nm,518nm and 531nm and the other peak is in the near infrared range at wavelengths 633nm, 680nm and 875 nm respectively.

scholarly journals Suppressing material loss in the visible and near-infrared range for functional nanophotonics using bandgap engineering

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Mingsong Wang ◽  
Alex Krasnok ◽  
Sergey Lepeshov ◽  
Guangwei Hu ◽  
Taizhi Jiang ◽  
...  
Keyword(s):  
Near Infrared ◽  
High Efficiency ◽  
Incident Light ◽  
Resonant Mode ◽  
Higher Order ◽  
Visible Range ◽  
Infrared Range ◽  
Bandgap Engineering ◽  
Material Loss ◽  
Near Infrared Range

Abstract All-dielectric nanostructures have recently opened exciting opportunities for functional nanophotonics, owing to their strong optical resonances along with low material loss in the near-infrared range. Pushing these concepts to the visible range is hindered by their larger absorption coefficient, thus encouraging the search for alternative dielectrics for nanophotonics. Here, we employ bandgap engineering to synthesize hydrogenated amorphous Si nanoparticles (a-Si:H NPs) offering ideal features for functional nanophotonics. We observe significant material loss suppression in a-Si:H NPs in the visible range caused by hydrogenation-induced bandgap renormalization, producing strong higher-order resonant modes in single NPs with Q factors up to ~100 in the visible and near-IR range. We also realize highly tunable all-dielectric meta-atoms by coupling a-Si:H NPs to photochromic spiropyran molecules. ~70% reversible all-optical tuning of light scattering at the higher-order resonant mode under a low incident light intensity is demonstrated. Our results promote the development of high-efficiency visible nanophotonic devices.

Microcrystalline and Amorphous Photovoltaic Silicon Materials Performance Optimization

2016 ◽  
Vol 870 ◽  
pp. 74-82 ◽  
Author(s):  
S.N. Chebotarev ◽  
A.S. Pashchenko ◽  
D.A. Arustamyan
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Performance Optimization ◽  
Near Infrared ◽  
Open Circuit ◽  
Visible Range ◽  
Infrared Range ◽  
Improved Performance ◽  
Crystalline Solar Cell

A design of a thin-film solar cell based on microcrystalline and amorphous silicon α-Si:H(n-i-p)/μс-Si:O(n-i-p)/μс-Si:H(n-i-p) was proposed. A physical model and software to calculate the functional characteristics of these solar cells were developed. The numerical simulation results show that the efficiency of the optimized thin-film solar cells may reach up to 16.3 %, open circuit voltage 1.96 V, fill factor 78 %. Improved performance of the non-crystalline solar cell is achieved by an increase in absorbance in the visible range 500 – 800 nm to 40 – 60 % and in the near-infrared range of the solar radiation 800 – 1100 nm to 70 – 75 %.

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