- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Subwavelength polarization optics via individual and coupled helical traveling-wave nanoantennas
摘要： Soil spectral allocation or classification is usually conducted on air-dried soils. However, the field soils are not all air-dried, and the change of soil moisture will affect soil reflectance. We introduce a soil allocation model that considers the effect of soil moisture for the purpose of eliminating the effect of soil moisture. The topsoil spectral curves of four typical soils from the Songnen Plain in Northeast China were re-sampled to 10-nm intervals and converted to first-derivative spectral curves and continuum removal curves. The spectral feature parameters were extracted from continuum removal curves in the visible-near infrared (VNIR) range (350–2500 nm), and the range of 430–2400 nm was used to build soil allocation models for reducing the effect of noise. Samples with different soil moisture were mixed into air-dried soils and we calculated the coefficient of variation (CV) of different inputs to assess the effect of soil moisture and to find allocation indices that were not affected by soil moisture. We used allocation indices of Zhang et al. (2018) because of the high accuracy of their DT (Decision Tree) model to allocate mixed-soil samples. We also used allocation indices that were not affected by soil moisture to allocate mixed-soil samples with decision tree (DT), multinomial logistic regression (MLR) and multi-layer perception neural network (MLPNN), and compared the results of the two methods. The results show the following: 1) As SFPs were built with shorter bands, SFP was less sensitive to soil moisture than PCR and PCFD and thus SFP is more suitable to build soil allocation models that consider the effect of soil moisture as input than PCR and PCFD. 2) Differences in soil moisture had little effect on absorption valley shoulders, symmetry and absorption positions, moderate effect on absorption area and depth, and a major effect on the slope of different bands. 3) The effect of soil moisture on continuum removal curves of different soil classes was variable. There was little effect on Arenosols, a moderate effect on Chernozems and Cambisols, and a large effect on Phaeozems. 4) The accuracy of the DT model using allocation indices that were not affected by soil moisture was 91.892% with a Kappa coefficient of 0.888. Our results suggest that it is feasible to build soil spectral allocation models that are not affected by soil moisture, and this improves the universality of soil spectral allocation, especially to field soils, which can be of considerable help in soil classification.
关键词： Decision tree,Visible-near infrared,Soil moisture,Spectral feature parameter,Soil spectral allocation
更新于2025-09-11 14:15:04
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Extraction of Uncertain Parameters of Double-Diode Model of a Photovoltaic Panel Using Simulated Annealing Optimization
摘要： In this article, our goal is to improve the estimation of the parameters of solar photovoltaic models by using the simulated annealing (SA) algorithm. The proposed approach takes into account the uncertainties of measurements. This approach consists of three steps. The ?rst is the extraction of the parameters in a conventional manner based on SA. Then, in order to reduce the search interval of parameters, we will determine the uncertainties of the measurements of each parameter. Finally, we will determine the instantaneous parameters, taking into account the results of the ?rst two steps. For the validation of proposed theoretical developments, the proposed approach is applied to two di?erent commercial solar panel parameter estimation problems (the monocrystalline solar module STM6-40/36 and the polycrystalline silicon cells photovoltaic module Sharp ND-R250A5). The results obtained are compared with well-established algorithms to con?rm its e?ectiveness. These comparisons have shown that the proposed method exhibits largely more e?ective performances than existing methods in the literature.
关键词： uncertainties,polycrystalline silicon cells,solar photovoltaic models,simulated annealing,monocrystalline solar module,parameter estimation
更新于2025-09-11 14:15:04
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Self-assembled chiral nanoribbons studied by terahertz time-domain spectroscopy and other biological methods
摘要： Massive Multiple Input Multiple Output (MIMO) has been widely considered as one of the most promising technologies for the fifth-generation (5G) wireless communication. In massive MIMO system, the research on channel characteristics is important. In this paper, the characteristics for massive MIMO channels at both 2 GHz and 6 GHz are investigated. Based on the real-world measurements, the channel parameters in the delay and frequency domains are extracted to show the non-stationary phenomenon over the large-scale antenna array. Furthermore, the characteristics of the angular parameters extracted by space-alternating generalized expectation-maximization (SAGE) algorithm are investigated and the fluctuations are modeled. The results for different frequencies are useful for deep understanding of massive MIMO channels in the future.
关键词： Massive MIMO,Channel characteristics,Angular parameter
更新于2025-09-11 14:15:04
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Small-angle measurement in laser autocollimation based on a common-path compensation method
摘要： In this study, a common-path compensation method is proposed for the laser beam drift resulting from the air parameters to enhance the stability of small-angle measurement in laser autocollimation. The measuring and reference beams generated with this method can propagate along approximately the same route such that the drifts in the two beams are nearly equal. Therefore, the angular drift of the measuring beam can be adequately compensated by that of the reference beam. The compensation principle was analyzed, and the experimental results revealed that, with three types of air parameter disturbances, the static measurement stability was better than 0.193 arcsec in 100 min after compensation, and the compensation rate was higher than 86.6%. Additionally, the dynamic measurement stability was 0.227 arcsec in 50 s after compensation, and the compensation rate was 53.6%. It is confirmed that the proposed method is effective for laser autocollimation.
关键词： Laser autocollimation,angle measurement,stability,common-path compensation,drift,air parameter
更新于2025-09-11 14:15:04
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Time-domain Formulation of a Multi-layer Plane Circuit Coupled with Lumped-parameter Circuits using Maxwell Equations
摘要： We calculate electromagnetic phenomena in the multi-layer plane circuit starting from the Maxwell equations. We present a numerical method of potential and current density in two-dimensional conductors, where their time developments are treated as phenomena of wave propagation. We treat the plane conductors by dividing them into small finite-volume elements, similar to the case of the partial element equivalent circuit method, and the transport equations are then solved by the finite-difference time-domain method. Furthermore, we develop a calculation method for the boundary in a multi-layer plane by applying the method we have used in multi-transmission lines. We formulate the boundary conditions of a multi-layer plane coupled with lumped-parameter circuits and introduce an algorithm to reduce calculation costs that are largely associated with the two-dimensional extension from the multi-transmission-line case. We perform calculations of the wave propagation of potential, current density, and charge density in the time domain for a simple plane circuit. these calculations are presented as supplementary materials of the present paper.
关键词： wave propagation,multi-layer plane circuit,electromagnetic phenomena,lumped-parameter circuits,potential and current density,numerical method,finite-difference time-domain method,Maxwell equations
更新于2025-09-11 14:15:04
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Modified Search Strategies Assisted Crossover Whale Optimization Algorithm with Selection Operator for Parameter Extraction of Solar Photovoltaic Models
摘要： Extracting accurate values for involved unknown parameters of solar photovoltaic (PV) models is very important for modeling PV systems. In recent years, the use of metaheuristic algorithms for this problem tends to be more popular and vibrant due to their e?cacy in solving highly nonlinear multimodal optimization problems. The whale optimization algorithm (WOA) is a relatively new and competitive metaheuristic algorithm. In this paper, an improved variant of WOA referred to as MCSWOA, is proposed to the parameter extraction of PV models. In MCSWOA, three improved components are integrated together: (i) Two modi?ed search strategies named WOA/rand/1 and WOA/current-to-best/1 inspired by di?erential evolution are designed to balance the exploration and exploitation; (ii) a crossover operator based on the above modi?ed search strategies is introduced to meet the search-oriented requirements of di?erent dimensions; and (iii) a selection operator instead of the “generate-and-go” operator used in the original WOA is employed to prevent the population quality getting worse and thus to guarantee the consistency of evolutionary direction. The proposed MCSWOA is applied to ?ve PV types. Both single diode and double diode models are used to model these ?ve PV types. The good performance of MCSWOA is veri?ed by various algorithms.
关键词： metaheuristic,solar photovoltaic,whale optimization algorithm,parameter extraction
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - Zatoka, Ukraine (2018.9.9-2018.9.14)] 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - Theoretical Model of the Processes of Nanostructuring the Material Surface under the Influence of Laser Radiation
摘要： The transition between different structural states of a surface of a solid after influence of laser radiation can be presented by the self-consistent behavior of three parameters: the relaxation field, the fields of stress and the concentration of relaxation zones. Within the framework of the Lorentz system, the transition between stable states of formations on the surface of a solid was presented. The dependence of the stationary value of the order parameter, at which the formation of relaxation zones is possible, was obtained. The intermittent version of the formation of relaxation zones was examined using the mechanism of first order phase transition.
关键词： phase transition,nanostructure,residual deformation,relaxation parameter
更新于2025-09-11 14:15:04
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A double-image encryption scheme based on amplitude-phase encoding and discrete complex random transformation
摘要： In this paper, a novel double image encryption scheme based on amplitude-phase encoding and discrete complex random transform (DCRT) is proposed. Firstly, two images are merged into a plural matrix by precoding, and the synthetic signal is modulated by the phase mask which is calculated from Chen chaotic sequences generated by using the self-adapting parameter as initial values. Then the modulated signal is encrypted by amplitude-phase encoding and the DCRT. The ?nal cipher-text is decomposed into amplitude and phase to obtain two encrypted images. Experimental results and performance analysis show that the proposed encryption scheme can effectively resist different attacks such as the differential attack and statistical attack etc., and can be used for the secure communications.
关键词： Amplitude-phase encoding,DCRT,Self-adapting parameter,Double-image encryption
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Chongqing (2018.6.27-2018.6.29)] 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Geometric Continuity Conditions for H-Bézier Curves of Degree n
摘要： With the aim to tackle the problem that the complex composite curves can not be constructed by using a single curve, the geometric continuity conditions for H-Bézier curves of degree n with shape parameter are investigated. The H-Bézier curves of degree n not only inherit the major properties of the classical Bézier curve of degree n, but also have a prominent performance on adjusting their shapes by changing shape parameter. Based on the analysis of the basis functions and the necessary and sufficient conditions of G1 and G2 geometric continuity between two adjacent H-Bézier curves of degree n are proposed. Modeling examples provided show that the derived continuity conditions are effective and hence can greatly enhances problem-solving abilities in complex curves design by using H-Bézier curves.
关键词： H-Bézier curves,geometric continuity conditions,curves design,shape parameter
更新于2025-09-11 14:15:04
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Systematic enumeration and proficient chemical sensing applications of Eu3+@CeO2 nanocrystals
摘要： Current study displayed the application of hydrothermal method for the preparation of highly crystalline nanocrystals of Eu3+ doped cerium oxide (Eu@CeO2) particles. The influence of doping percentage and annealing effects were studied on the crystalline nature and morphology of particles. The size, optical properties and lattice parameters were calculated as a function of dopant concentrations and their discrepancies were explained in detail. Integration of Eu3+ ions on CeO2 could unlock a new trail to optimize the photoluminescence properties of formed nanocrystals. The generated oxygen vacancies (Vo··) have the ability to affect the characteristic features of cerium oxide in solid state. The variations in the nature of surface defect in presence of Eu3+ ions with CeO2 nanoparticles were explained with the results of XPS studies. The obtained results validated that defect-induced band gap modification by Eu3+ ion doping on CeO2 could be employed as effective chemical sensor for harmful metal ions in real water samples.
关键词： photoluminescence,lattice parameter,crystalline,doped Cerium oxide,oxygen vacancies,hydrothermal
更新于2025-09-11 14:15:04