- 标题
- 摘要
- 关键词
- 实验方案
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Distinguishing between closely related species of Allium and of Brassicaceae by narrowband hyperspectral imagery
摘要： Classification of crop species is an actively studied topic in remote sensing using multi-spectral image sensors. Unfortunately, the spectral bands available in the multispectral imagery are broad and limited in number to classify the crop species. In this paper, we propose optimal spectral bands to classify Allium (garlic and onion) and Brassicaceae (Chinese cabbage and radish) by using higher-dimensional data from hyperspectral imagery. A decision-tree classifier was used to determine the optimal method to use the high-dimensional data. The high-dimensional data were analysed for all growth stages and considering bandwidths with different full width at half maximum (FWHM) values at 25, 40, 50 and 80 nm. The spectral bands selected for Allium were differentiated into green, blue, and NIR bands for each growth stage. The results show that Allium can be classified clearly as overall accuracy (OA) 1 and kappa coefficient 1 for all FWHM based on March 22 data. For each April 19 and May 12 data, the decision-tree classifier with each 80 nm FWHM and 50 nm FWHM yielded a better classification accuracy of more than OA 0.921 and kappa coefficient 0.839 than other FWHM. The spectral bands selected for Brassicaceae were found to be similar to blue band for all growth stages. Brassicaceae was classified clearly for all FWHM based on October 27 data. Also, Brassicaceae was classified clearly for 25 nm FWHM based on November 25 data and OA, kappa coefficient for 40 nm FWHM and 50 nm FWHM are high as 0.974, 0.947 respectively.
关键词： Decision-tree classifier,Hyperspectral imagery,Classification,Full width at half maximum,Spectral band
更新于2025-09-23 15:23:52
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Reduced order derivation of the two-dimensional band structure of a mixed-mode resonator array
摘要： In this paper, the 2D band structure of a mixed-mode metamaterial resonator array for in-plane waves is investigated. The band structure in the interior and on the boundary of the irreducible Brillouin zone and 1D dispersion diagrams for different propagation angles are calculated numerically and presented. Additionally, a reduced order analytical method is established to compare and approximate the band structure. The studied metamaterial, with a T-shaped cantilever beam as the resonator in its square array repeating unit cells, exhibits branches with mixed P and SV waves except at exactly one angle of propagation. This paper also reports on the occurrence of avoided level crossings, which are related to the existence of exceptional points in the complex domain. A reduced order analytical approach is used that can generate partial (low branches) band structure with relatively little computational effort. The reduced order model agrees well with the numerical results for these low branches and can provide support in mode identification and band sorting. With proper adjustments in parameters, this analytical method will be applicable to other metamaterials that have a similar unit cell structure.
关键词： band structure,reduced order model,resonator array,metamaterial,avoided level crossings,mixed-mode waves
更新于2025-09-23 15:23:52
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Band structure and optical constants of SnS <sub/>2</sub> single crystals
摘要： Absorption (K), reflection (R) and wavelength modulated transmission (ΔT/Δλ) spectra in SnS2 crystals of hexagonal phase (space group P63/mmc) were investigated in temperature interval from 300 to 10 K. It was established that indirect band gap (Eg ind - 2.403 eV) is due to unpolarized indirect transitions between Γ and M points of Brillouin zone. A minimal direct band gap (Eg dir - 2.623 eV) in E||b polarization is formed by direct allowed transitions and in E⊥b polarization (2.698 eV) by forbidden transitions in Γ point of Brillouin zone. A magnitude of refractive index (n) changes from 3 to 4 and has a maximum at 2.6 eV. Optical functions (n, k, ε1 and ε2) in energy region E > Eg (3 - 6.5 eV) were calculated from measured reflection spectra by Kramers-Kronig analysis. Features observed in reflection and optical function spectra were assigned to electron transitions. This electron transitions were localized in framework of theoretically calculated band structure.
关键词： optical functions,electronic band structure,layered SnS2 crystals,absorption, reflection and transmission spectra
更新于2025-09-23 15:23:52
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Electronic and optical properties of double perovskite oxide Pb2ScMO6 (M = Ta, Sb) using a first principles approach
摘要： In this study, the electronic and optical properties of the double perovskite (DP) oxides Pb2ScMO6 (M = Sb, Ta) were systematically investigated using the full-potential linearized augmented plane wave model. Calculations were performed using both the generalized gradient approximation and modified Becke–Johnson potentials. The results showed that the O-atom is responsible for the maxima in the density of states (DOS) in the valence band, whereas the Sc-atom contributes to the maximum DOS in the conduction band. The dielectric constants, absorption coefficients, and reflectivity were also calculated for these systems. The results indicated the presence of wide band gaps in both of these DPs, thereby indicating their insulating semiconducting nature.
关键词： photon energy,energy,dielectric,double perovskite,density of states,band gap
更新于2025-09-23 15:23:52
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Luminescent, optical, magnetic and metamaterial behavior of cerium complexes
摘要： The complexes of cerium with nitrogen, oxygen and sulfur donor ligands were prepared by conventional method. These newly synthesized complexes were characterized by FTIR, UV-Vis, DART Mass, TGA, PXRD, SEM and TEM techniques. The magnetic studies were carried out by the vibrating sample magnetometer. The optical constants were measured by absorption and reflection spectra as a function of wavelength. The concentration dependence of refractive index and absorption were observed by the experimental method, which reveals that these parameters are affected by change in concentration. The optical band gap obtained from Tauc-plot indicates its probability to be a good semiconductor. The luminescence behavior of these cerium complexes were observed by the absorption and emission spectra and the emission life time were calculated by their life time spectra.
关键词： Optical band gap,Luminescence,Refractive index,Magnetic studies
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Current-Fed Quasi Z-Source Inverter Based PV Distributed Generation Controller
摘要： Recently, the renewable photovoltaic distributed generation (PV-DG) enjoys a rapid growth globally due to the advancement in solar systems and power electronics technologies. However, the intermittent nature of solar radiation and performance of the attached power converters, inevitably poses some challenges to the power grids integrated large-scale solar-farms (SF). These challenges include frequency oscillations, voltage variation and power quality issues. To overcome these problems, this study proposes a Current-Fed quasi Z-source Inverter (CF-qZSI) as an alternative converter for distribution generation controllers to facilitate the integration of a PV energy source into a weak power system. The detailed model of the CF-qZSI-based distribution controller (CqZDC) and its control system are developed. The dynamic performance of the CqZDC device is evaluated to validate different objectives using an actual field data and RTDS simulation platform.
关键词： frequency stability,current source inverter,wide band gap devices,Accommodation of renewable energy resources,power quality improving,facilitating of distributed electricity generations
更新于2025-09-23 15:23:52
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[IEEE 2017 International Conference on Computing, Communication, Control and Automation (ICCUBEA) - PUNE, India (2017.8.17-2017.8.18)] 2017 International Conference on Computing, Communication, Control and Automation (ICCUBEA) - Analysis of Shape Based Image Retrieval Using Different Wavelets Transforms
摘要： The shape of an object is one of a defining factor in image processing. Here we will be focusing on image retrieval techniques relevant to shape features. The similarity within these shape features are calculated using wavelets transforms, principal components using Singular Value Decomposition(SVD) and clustering via K-Means.
关键词： M-band Wavelets,Singular Valve Decomposition,Shape features,K-Means
更新于2025-09-23 15:23:52
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - High Spatial Soil Moisture Mapping Using Small Unmanned Aerial System
摘要： Soil moisture is of fundamental importance to many hydrological, biological and biogeochemical processes, plays an important role in the development and evolution of convective weather and precipitation，and impacts precision agriculture, water resource management, and flood runoff prediction. The launch of NASA’s Soil Moisture Active/Passive (SMAP) mission in 2015 provide new passive global measurements of soil moisture and surface freeze/thaw state at fixed crossing times and spatial resolutions of 36 km. There exists a need for measurements of soil moisture on much smaller spatial scales and arbitrary diurnal times for SMAP validation, precision agriculture, flood runoff prediction, evaporation and transpiration studies of boundary layer heat transport, and tundra thaw studies. The Lobe Differencing Correlation Radiometer (LDCR) provides a means of mapping soil moisture on spatial scales as small as several meters (i.e., the height of the platform). Compared with various other proposed methods of validation based on either in situ measurements or existing airborne sensors suitable for manned aircraft deployment, the integrated design of the LDCR on a lightweight small unmanned aerial system (sUAS) can provide sub-watershed (~km scale) coverage at very high spatial resolution (~15 m) suitable for scaling scale studies. The Tempest sUAS, flies at very low operator cost compared to manned aircraft. To demonstrate the LDCR Rev A and Rev B, several flights had been performed during field experiments at the Canton Oklahoma Soilscape site on September 8th and 9th, 2015 and Yuma Colorado Irrigation Research Foundation (IRF) site from June to August 2016, and October 2017. The LDCR antenna temperature and soil moisture maps will be presented, and scientific intercomparisons between LDCR soil moisture data and in-situ measurements will be presented.
关键词： unmanned aerial system,L-band radiometer,soil moisture mapping
更新于2025-09-23 15:23:52
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[IEEE 2018 2nd International Conference on Telematics and Future Generation Networks (TAFGEN) - Malaysia (2018.7.24-2018.7.26)] 2018 2nd International Conference on Telematics and Future Generation Networks (TAFGEN) - Design of 28/38 GHz Dual-Band Triangular-Shaped Slot Microstrip Antenna Array for 5G Applications
摘要： Nowadays, evolving an advanced technology for the next generation of wireless cellular communication networks has put a great interest for researchers over the world. This aim is to accomplish the growing demand for advanced data rates. The fifth generation (5G) promises more advantages and benefits to the world. It will create an essential difference over 4G. The design of 5G antenna providing broad bandwidth is very important to ensure the performance of 5G networks. In this paper, microstrip antennas array of single, two, four and six elements dual-band (28/38GHz) for 5G applications are discussed. The proposed antennas are printed on 1.575 mm-thick Rogers Duroid 5880 substrate with dielectric constant of εr= 2.2 and loss tangent (tan δ) of 0.0009. They consist of a triangular shaped radiating patch fed by a 50 ? microstrip line. The antenna bandwidth is furthered by etching the triangular shaped slot on the ground plane. The highest gain is provided by the antenna with six elements array for both frequencies. The maximum gain of 7.47 dBi with return loss of -30.70 dB at 28 GHz and 12.1 dBi with return loss of -34.5 dB at 38 GHz are obtained.
关键词： array antenna,dual band antenna,5G antenna,microstrip antenna
更新于2025-09-23 15:23:52
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Investigating flexible band-stop metamaterial filter over THz
摘要： Metamaterial filter is a novel type of photoelectric device. In this study, a triple-band band-stop filter for terahertz is fabricated by magnetron sputtering of periodic metamaterial resonators on flexible polyimide substrates. The band-stop resonant points of the filter are 107.3, 167.45, and 209.9 GHz, and the 3 dB bandwidths are 14.13, 14.03, and 22.44 GHz. S21 parameters at the resonance point reach ?30.217, ?30.432, and ?38.618 dB, thereby possibly achieving an excellent frequency blocking performance. Simultaneously, the stop-band can be adjusted by controlling the length of the metamaterial unit size, thus modifying the frequency of the filter.
关键词： Terahertz wave,Photoelectric device,Band-stop filter,Metamaterials
更新于2025-09-23 15:23:52