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[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic, Czech Republic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Novel Method of Total Spectral Radiant Flux Standard Realization
摘要： Modern metrology of SSL sources requires a modified approach to future realization of reference standards. This is caused by the fact that traditional broad band and omni-directional light sources used are being replaced by high intensity sources with a specific directional light intensity distribution. At the same time the importance of LED lighting quality assurance is increasing as this new type of lighting is currently replacing traditional light sources in many applications. The specifics of an integrating sphere-spectroradiometer measurement system require the calibration with the use of a reference standard with known Spectral Radiant Flux Distribution, Luminous flux as well as the Luminous Intensity Distribution (LID) to compensate for the sphere system non-uniform reflectance properties. This way the accuracy of the sphere system calibration will allow to measure various types of LED products in conformance with the EN 13032-4:2015, LED lamps, modules and luminaires modules, lamps regardless of their spatial distribution properties. This paper will cover basic concepts and details of a novel method of Total Spectral Radiant Flux (TSRF) realization and description of a TSRF standard facility developed for the Russian National Metrology Institute – VNIIOFI, Moscow. The method (and the developed facility) is based on a goniospectroradiometer system traceable to a standard Black Body and allowing the calibration of a light source in terms of TSRF and additionally providing LID data of the source.
关键词： calibration,measurement,total spectral radiant flux
更新于2025-09-23 15:21:21
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Computation of Excitation Frequencies for Nonlinear Wave Scattering and Generation Processes
摘要： Resonant properties of scattering and generation of waves by a nonlinear layered object are numerically investigated by means of a self-consistent iterative algorithm. The excitation takes place close to the eigen frequencies of linearized induced dielectric permittivities, and the resulting properties of the nonlinear layered object are analyzed. Special consideration is given to the dynamics of the spectra and the energy characteristics of scattering and generation waves.
关键词： nonlinear layers,self-consistent analysis,resonant scattering and generation,induced spectral problems
更新于2025-09-23 15:21:21
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Graded Band Diode for Noise Generation in Terahertz Range
摘要： The noise signal sources at subterahertz(sub- in many terahertz(THz) region are useful THz) and applications such as tomographic imaging, spectroscopy, radars and other. The GaInAs-based diodes for noise generation in the sub-THz and THz region are proposed. The diodes based on the mechanism of impact ionization in graded- gap region and static high field domain formation near cathode. Ensemble Monte Carlo technique was used for diodes analyze. The spectral noise density power is calculated for difference profiles of spatial Ga distribution in GaInAs. It is found that the spectral noise density power of the proposed diodes exceeds the one of GaAs-based diodes by at least an order of magnitude.
关键词： spectral noise density power,impact ionization,compound,static cathode domain,graded band
更新于2025-09-23 15:21:21
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A new filter for dimensionality reduction and classification of hyperspectral images using GLCM features and mutual information
摘要： Dimensionality reduction is an important preprocessing step of the hyperspectral images classification (HSI), it is inevitable task. Some methods use feature selection or extraction algorithms based on spectral and spatial information. In this paper, we introduce a new methodology for dimensionality reduction and classification of HSI taking into account both spectral and spatial information based on mutual information. We characterise the spatial information by the texture features extracted from the grey level cooccurrence matrix (GLCM); we use Homogeneity, Contrast, Correlation and Energy. For classification, we use support vector machine (SVM). The experiments are performed on three well-known hyperspectral benchmark datasets. The proposed algorithm is compared with the state of the art methods. The obtained results of this fusion show that our method outperforms the other approaches by increasing the classification accuracy in a good timing. This method may be improved for more performance.
关键词： hyperspectral images,spectral and spatial features,classification,SVM,mutual information,GLCM,grey level cooccurrence matrix,support vector machine
更新于2025-09-23 15:21:21
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[Springer Series in Optical Sciences] Fano Resonances in Optics and Microwaves Volume 219 (Physics and Applications) || Study of Fano Resonance in the Core-Level Absorption Spectrum in Terms of Complex Spectral Analysis
摘要： We study theoretically the core absorption spectrum of an impurity embedded in a tight-binding chain in terms of complex spectral analysis. The absorption spectral pro?le associated with the resonance states in principle exhibits an asymmetric Fano-type structure, even without apparent multiple interference transition paths. The asymmetric Fano absorption pro?le is attributed to the complex-valued oscillator strength of the transition to the resonance state belonging to the extended Hilbert space. The boundary condition on the continuum causes a large energy dependence of the self-energy, so that it enhances the nonlinearity of the eigenvalue problem of the effective Hamiltonian, yielding several non-analytic resonance states. The optical transitions to these resonance states constitute the overall absorption spectrum structure.
关键词： Fano resonance,core-level absorption spectrum,complex spectral analysis,extended Hilbert space,resonance states
更新于2025-09-23 15:21:21
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Coherence properties of a random electromagnetic vortex beam propagating in biological tissues
摘要： Based on the extended Huygens-Fresnel principle and the unified theory of polarization and coherence, the coherence properties of random electromagnetic Gaussian Schell model (GSM) vortex beams propagating through biological tissues were investigated. It was shown that with an increasing propagation distance, the change in the spectral degree of coherence |μ(ρ, ?ρ, z)| is more complex than that of μ(0, ρ, z). If the change in |μ(ρ, ?ρ, z)| is divided into the preceding and latter stages, then the change in μ(0, ρ, z) is similar to that of |μ(ρ, ?ρ, z)| at the latter stage. The wavelength of the far-infrared beam (λ = 10.6 μm) is similar to that emitted by the biological tissues, and a resonance with water molecules occurs in the biological tissues. At the initial plane, the larger ρx corresponds to a smaller value of |μ(ρ, ?ρ, z)|, and during the propagation process, the spatial coherent interval is wider for |μ(ρ, ?ρ, z)| than for μ(0, ρ, z). The fluctuation change depth of |μ(ρ, ?ρ, z)| in the biological tissues is somewhat shallower than that of μ(0, ρ, z) under the same conditions, such as the same biological tissue, the same wavelength, or the same interval between two field points. In addition, the spatial self-correlation length σ yy has an effect on |μ(ρ, ?ρ, z)| and on μ(0, ρ, z) to a different extent, while the changes in these two quantities are independent of the spatial mutual-correlation length σ xy of the random electromagnetic GSM vortex beam.
关键词： vortex beam,Spectral degree of coherence,cross-spectral density matrix,biological tissues
更新于2025-09-23 15:21:01
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Synthesis and Spectral Characteristics of BODIPY Dyes with Two or Three Dipyrrin Domains
摘要： Several boron-dipyrrin (BODIPY) based fluorophores with two and three dipyrrin cores were synthesized and investigated in solvents under the concentration variation. Comparative analysis of spectral and photophysical changes under increasing the number of the cores in the dye molecule was made. Mutual influence of dipyrrin cores was detected leading to the increasing of the compounds rigidity and, thus, the absence of fluorescent molecular rotor effects under the viscosity variation. Aggregation induced quenching, which was observed for many mono-domain BODIPY dyes is reduced in case of investigated poly-domain compounds.
关键词： Aggregation induced spectral changes,Intramolecular rotation,Spectral properties,Synthesis,BODIPY
更新于2025-09-23 15:21:01
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[IEEE 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Sao Paulo, Brazil (2019.10.7-2019.10.9)] 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Spectral Analysis of a Nanodipole Array above the Surface Impedance of Graphene by Greena??s Function
摘要： In this paper, we present a spectral analysis of a nanodipole array above a graphene layer by the Periodic Green’s Function (PGF) method. The graphene layer deposited on a dielectric substrate is modeled as a surface impedance with conductivity described by the Kubo model. The Green’s function is obtained by the complex two-dimensional Fourier series transform, with impedance condition at the interface between the dielectric media. We performed a parametric analysis of the in?uence of chemical potential on the absorbance and the electromagnetic ?elds in the spectral domain. For the modeling used, the dispersion characteristic of graphene is also veri?ed. From the spectral analysis we investigated the emergence of the Surface Plasmon Polariton (SPP) pole in the spectral representation. Finally, we compared the model based on impedance condition with a formulation that considers graphene with a ?nite thickness.
关键词： Spectral Analysis,Plasmonics,Green’s Function,Graphene
更新于2025-09-23 15:21:01
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Effect of Concentration on the Spectrala??Luminescent Properties of Quantum Dots in Colloidal Solutions
摘要： The effect the concentration of double-shell CdSe/CdS/ZnS semiconductor colloidal quantum dots has on the measured parameters of the absorption and luminescence spectra of a solutions of these quantum dots in toluene is studied via optical spectroscopy. Possible mechanisms of the effect the concentration of quantum dots in the solutions has on the characteristics of the luminescence spectra are analyzed.
关键词： optical spectroscopy,colloidal solutions,concentration,quantum dots,spectral-luminescent properties
更新于2025-09-23 15:21:01
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A fully coupled numerical simulation of a hybrid concentrated photovoltaic/thermal system that employs a therminol VP-1 based nanofluid as a spectral beam filter
摘要： The realistic numerical modelling of multiphysics applications is an efficient way to precisely predict the operation of concentrated solar systems. Although many multiphysics conjugating approaches have been proposed in the literature, it is difficult to adopt such methods into simulating complex concentrated solar technologies. Consequently, this study introduces a novel 2D:3D numerical optical, thermal and electric coupling approach for a hybrid compound parabolic concentrator photovoltaic/thermal (CPC-PV/T) collector using a nanofluid as a spectral beam filter. In this approach, the volumetric absorbed radiation in each component of the system obtained from the non-gray 2D model is patched into the 3D model as a volumetric heat source using sophisticated computational tools. The main features of the full coupling method (FCM) are extensively analyzed and compared with the other two coupling methods previously adopted. Further, the module performance has been investigated employing both the nanofluid and base-fluid spectrum filters (BF-filter) compared with a stand-alone concentrated PV cell. From findings, the FCM can be applied to reveal more realistic operation characteristics of the proposed system compared with the other approaches, since the FCM can take into account the non-uniformity of solar illumination and the direction of reflected solar beams upon the receiver, along with the variation in the optical characteristics of utilized materials over the solar irradiance. Additionally, suspending indium tin oxide (ITO) nanoparticles into the Therminol VP1 oil raises the absorption rate over the thermal-bands with 62.5% higher than the use of BF-filter, whilst the cell temperature and the transmitted irradiance within the PV-band are obviously declined.
关键词： Radiative heat transfer,Multiphysics coupling method,Nanofluid,Concentrated photovoltaic/thermal system,Spectral beam filter
更新于2025-09-23 15:21:01