A transcendental equation occurs when we compute the dispersion relations of an electromagnetic waveguide, such as a planar multilayer waveguide. Without an initial guess, the Sakurai-Sugiura projection method (SSM) can obtain solutions to the transcendental equation in a region bounded by a contour integral path in the complex plane. In this paper, a criterion employing the condition number of eigenvalues as a simple index to distinguish physical solutions from spurious ones in the SSM is presented, and a transcendental equation of a multilayer waveguide obtained by the transfer matrix method is solved by the SSM. Numerical results show the usefulness of the index and good agreement with the results of the argument principle method and Newton's method.
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http://dx.doi.org/10.1364/JOSAA.32.001216 | DOI Listing |
Sci Rep
November 2024
College of Electronic and Information Engineering, Shandong University of Science and Technology, Qingdao, 266590, China.
Selective Harmonic Elimination Pulse Width Modulation (SHEPWM) has excellent harmonic characteristics, but its nonlinear transcendental system of equations is difficult to be solved, and the practical application encounters a bottleneck. In this paper, a modulation optimization method for seven-level SHEPWM inverter based on the Evolutionary Particle Swarm Optimization (EPSO) algorithm is proposed to address this problem, so that the algorithm quickly converges to the global optimum solution. The EPSO algorithm incorporates a population optimization strategy in two phases to improve the population diversity in real time.
View Article and Find Full Text PDFBehav Sci (Basel)
November 2024
Department of Special Education & Counselling, The Education University of Hong Kong, Hong Kong, China.
Community lay leaders are critical in connecting professional services and general populations in communities. However, limited studies have explored the potential protective factors for psychological health among this group of people. In addition, based on the complex nature of spiritual health, the inconsistent findings of previous studies also suggested that different domains of spiritual health may shape psychological health differently in different contexts and among different socio-demographic groups.
View Article and Find Full Text PDFCogn Neurodyn
April 2024
Department of Mathematics and Information Science, Henan University of Economics and Law, Zhengzhou, 450046 China.
Multiple delays and connection topology are the key parameters for the realistic modeling of networks. This paper discusses the influences of time delays and connection weight on multi-delay artificial neural models with inertial couplings. Firstly, sufficient conditions of some singularities involving static bifurcation, Hopf bifurcation, and pitchfork-Hopf bifurcation are presented by analyzing the transcendental characteristic equation.
View Article and Find Full Text PDFContin Mech Thermodyn
August 2024
Department of Mechanical and Process Engineering, ETH Zürich, Leonhardstrasse 27, 8092 Zürich, Switzerland.
We perform a complete spectral analysis of the linear three-dimensional Boltzmann BGK operator resulting in an explicit transcendental equation for the eigenvalues. Using the theory of finite-rank perturbations, we confirm the existence of a critical wave number which limits the number of hydrodynamic modes in the frequency space. This implies that there are only finitely many isolated eigenvalues above the essential spectrum at each wave number, thus showing the existence of a finite-dimensional, well-separated linear hydrodynamic manifold as a combination of invariant eigenspaces.
View Article and Find Full Text PDFCogn Neurodyn
June 2024
School of Mathematics, Southeast University, Nanjing, 210096 China.
The dynamics of integer-order Cohen-Grossberg neural networks with time delays has lately drawn tremendous attention. It reveals that fractional calculus plays a crucial role on influencing the dynamical behaviors of neural networks (NNs). This paper deals with the problem of the stability and bifurcation of fractional-order Cohen-Grossberg neural networks (FOCGNNs) with two different leakage delay and communication delay.
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