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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) - Broadband Antennas with Reactive Loads
摘要： The results of a study on the expansion of the frequency range of vibrational curved whip and loop antennas are presented. Optimal designs of these antennas with concentrated reactive loads included in the shoulders are proposed. The study was carried out for a design that appears promising for use as a microstrip antenna. It is a Z-shaped antenna of orthogonal linear polarization and loop antenna, supplemented by concentrated capacitive loads. It is shown that in order to obtain in the Z-shaped antenna and loop antenna a regime of a current close to the traveling wave regime and to obtain broadband, it is sufficient to include no more than four capacitive loads of a certain value in the antenna arm. This makes the construction of a broadband antenna and to reduce the expenditure of time and resources for its development and fabrication in comparison with known works in which it was proposed to include in the arm of the antenna a much larger number of reactive loads.
关键词： concentrated capacitive load,distribution of the complex current at the antenna,broadband antenna,standing wave voltage factor,antenna gain factor
更新于2025-09-23 15:21:21
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Dual Emission of a Cyclic Hexanuclear Gold(I) Complex. Interplay between Au <sub/>3</sub> and Au <sub/>2</sub> Ligand-Supported Luminophores
摘要： Finding diverse and tunable molecular structures is relevant towards the design of functional nanostructures. The photoluminescence of complex 1, featuring ligand-supported hexanuclear Au(I) framework compromising a triangular Au3 core of which each apex is connected to an external Au(I) center has revealed a remarkable dual emission at room temperature. The emission bands display maxima centered at λem = 512 and 694 nm with Stokes shift of 19530 and 14410 cm-1 and are attributed to the radiative relaxation of two excited-states centered onto the central Au6 skeleton arising from 5dσ?→6pσ excitation. As suggested by the strikingly different dioxygen dependency of the relative intensity of the two emission bands, the observed dual emission can be tentatively attributed to the incomplete equilibration between two close-lying emissive excited states with singlet and triplet character, most likely due to slow intersystem crossing (ISC) process, yielding green fluorescence and red phosphorescence, respectively; this phenomenon is rarely observed in heavy element compounds. Based on theoretical calculations, these excited-states originated from two different substructures-luminophores of the molecular skeleton, mainly i) the Au3 core, and ii) one specific Au2 unit. Thus, the dual luminescence of 1 originates from the noteworthy inclusion of two luminophores within the overall molecular structure. Both solution and solid-state emission spectra show similar characteristics owing to the intramolecular nature of the suggested luminescence mechanism. Such luminophores can be envisaged as novel metalloligands to be incorporated in larger gold nanoclusters towards the development of intense luminescent molecular devices.
关键词： Au3 and Au2 Ligand-Supported Luminophores,Cyclic Hexanuclear Gold(I) Complex,Photoluminescence,Aurophilic Interactions,Dual Emission
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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Osmium sensitizer with enhanced spin-orbit coupling for panchromatic dye-sensitized solar cells
摘要： Low-lying triplet metal-to-ligand charge transfer (3MLCT) transitions of osmium complexes induced by spin-orbit coupling (SOC) is promising to extend photocurrent response when applied to dye-sensitized solar cells. In this study, we present a newly designed osmium complex (coded CYC-33O), incorporating a 2-thiohexyl-3,4-ethylenedioxythiophene functionalized bipyridyl ancillary ligand to red-shift the absorption and enhance the absorbance of both singlet and triplet MLCT transitions. Time-dependent density functional theory (TDDFT) calculations clearly signify the reinforced 1MLCT and 3MLCT transitions of CYC-33O mainly originate from osmium to 4,4',4"-tricarboxy-2,2':6',2"-terpyridine anchoring ligand, advantaging the heterogeneous electron transfer between CYC-33O and TiO2. The device sensitized with CYC-33O exhibits the panchromatic conversion beyond 1000 nm, yielding the photocurrent density of 19.38 mA cm–2 which is much higher than those of the cells based on the ruthenium analogue (CYC-33R) and model osmium complex (Os-3) sensitizers.
关键词： dye-sensitized solar cell,triplet metal-to-ligand charge transfer (3MLCT),ruthenium complex,spin-orbit coupling (SOC),osmium complex,time-dependent density functional theory (TDDFT)
更新于2025-09-23 15:21:01
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Global Complex Roots and Poles Finding Algorithm Based on Phase Analysis for Propagation and Radiation Problems
摘要： A ?exible and effective algorithm for complex roots and poles ?nding is presented. A wide class of analytic functions can be analyzed, and any arbitrarily shaped search region can be considered. The method is very simple and intuitive. It is based on sampling a function at the nodes of a regular mesh, and on the analysis of the function phase. As a result, a set of candidate regions is created and then the roots/poles are veri?ed using a discretized Cauchy’s argument principle. The accuracy of the results can be improved by the application of a self-adaptive mesh. The effectiveness of the presented technique is supported by numerical tests involving different types of structures, where electromagnetic waves are guided and radiated. The results are veri?ed, and the computational ef?ciency of the method is examined.
关键词： complex modes,Complex roots ?nding algorithm,propagation,radiation
更新于2025-09-23 15:21:01
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Mathematical Operations of Transmissive Near Fields Controlled by Metasurface with Phase and Amplitude Modulations
摘要： Metasurfaces show great potential due to their powerful ability to manipulate electromagnetic waves as desired, which has been widely investigated in the microwave, terahertz, infrared, and visible regimes. Here, it is proposed to control near-field distributions through use of a metasurface with both amplitude and phase modulations. A C-shaped particle is designed to provide stable and continuous amplitude and phase profiles independently of transmitted waves by varying its opening and orientation angles. Benefiting from both amplitude and phase modulations on the metasurface, differentiation and integration on electric-field distributions can be achieved by changing the arrangements of complex coefficients on the metasurface. Besides, the differential operation can be utilized to show the edges of predesigned electric-field distributions. It is believed that the proposed method will accelerate the pace of metasurfaces towards many applications by engineering and operating the near-field distributions.
关键词： metasurfaces,complex amplitudes,amplitude modulation,phase modulation,integral operations,differential operations
更新于2025-09-23 15:21:01
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On short-range pulse propagation described by (2 + 1)-dimensional Schr??dinger's hyperbolic equation in nonlinear optical fibers
摘要： The (2 + 1)-dimensional Schr?dinger complex equations are essential physical models that describe the short-range pulse spread in nonlinear media fiber optics. We construct novel complex solutions to Schr?dinger’s complex hyperbolic model by using two different techniques. One method is characterized by the efficient algebraic equations that eventually form. Meanwhile, it uses the dependency variable expressions and its derivatives in the differential equation of the polynomial of a solitary wave. New acquired solutions are rational and exponential solutions expressed by periodic solutions. The solutions are illustrated through 3D- and 2D- plots to clarify the physical features for this model.
关键词： New soliton solutions,Hyperbolic (2 + 1)- dimensional Schr?dinger equation,Complex transformation
更新于2025-09-23 15:21:01
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[IEEE 2020 Moscow Workshop on Electronic and Networking Technologies (MWENT) - Moscow, Russia (2020.3.11-2020.3.13)] 2020 Moscow Workshop on Electronic and Networking Technologies (MWENT) - Measurement of the Dynamic Characteristics of Separate Spectral Bands of the LEDs Electroluminescence Spectra
摘要： A method for measuring the 3 dB frequency of the full modulation of separate spectral components of electroluminescence spectrum of light-emitting diodes (LEDs) is described. The method consists in passing through the LED a series of current pulses having the shape of a meander, and the emission spectrum of the LED is measured by a spectrometer OceanOptics USB2000+ in the mode of signal accumulation. As the pulse frequency increases, the intensity of all spectral components of the LED emission spectrum decreases. The frequency at which the optical signal decreases 1.19 times relative to the level measured at a low frequency is taken as the 3 dB frequency of the separate spectral component of the LED electroluminescence spectrum. By using the pulse signal it is possible to increase the sensitivity of the measuring means compared to the measuring means using the harmonic test signal. A description of the hardware-software complex implementing said measurement method is presented. The results of testing the measuring complex by the electroluminescence spectra of commercial green InGaN-based LEDs at the current range of 10-5...10-2 A and the current frequency range of 0.001...10 MHz are presented. The developed hardware-software complex and the method for estimating the spectral recombination parameters of heterojunction LEDs can be used both for the purpose of diagnosing the quality of LEDs and in developing structural and technological solutions for creating new light-emitting structures.
关键词： electroluminescence spectra,measuring complex,measurement method,3 dB frequency,light-emitting diode (LED),radiative and nonradiative charge carriers lifetime
更新于2025-09-23 15:21:01
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Vector dissipative light bullets in optical laser beam
摘要： The dynamics of light bullets propagating in nonlinear media with linear/nonlinear, gain/loss and coupling described by the (2+1)-dimensional vectorial cubic–quintic complex Ginzburg–Landau (CGL) equations is considered. The evolution and the stability of the vector dissipative optical light bullets, generated from an asymmetric input with respect to two transverse coordinates x and y, are studied. We use the variational method to find a set of differential equations characterizing the variation of the light bullet parameters in the laser cavity. This approach allows us to analyze the influence of various physical parameters on the dynamics of the propagating beam and its relevant parameters. Then, we solve the original coupled (2+1)D cubic–quintic CGL equation using the split-step Fourier method. Numerical results and analytical predictions are confronted, and a good agreement between the two approaches is obtained.
关键词： split-step Fourier method,nonlinear media,light bullets,complex Ginzburg–Landau equations,variational method
更新于2025-09-23 15:21:01
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The classification of plants by laser-induced breakdown spectroscopy based on two chemometric methods
摘要： The applications of laser-induced breakdown spectroscopy (LIBS) on classifying complex natural organics are relatively limited and their accuracies still needs to be improved. To study the methods on classification of complex organics, three kinds of fresh leaves were measured by LIBS in this work. 100 spectra from 100 samples of each kind of leaves were measured and then they were divided into training set and test set in a ratio of 7:3. Two algorithms of chemometric methods including the partial least squares discriminant analysis (PLS-DA) and principal component analysis Mahalanobis distance (PCA-MD) were used to identify these leaves. By using 23 lines from 16 elements or molecules as input data, these two methods can both classify these three kinds of leaves successfully. The classification accuracies of training set are both up to 100% by PCA-MD and PLS-DA, respectively. The classification accuracies of test set are 93.3% by PCA-MD and 97.8% by PLS-DA, respectively. It means that PLS-DA is better than PCA-MD in classifying plant leaves. Because the components in PLS-DA process are more suitable for classification than those in PCA-MD process. We think that this work can provide a reference for plant traceability using LIBS.
关键词： classification of complex organics,partial least squares discriminant analysis,principal component analysis Mahalanobis distance,laser-induced breakdown spectroscopy
更新于2025-09-23 15:21:01