检索结果-南通市图书馆

Flower Pollination Heuristics for Parameter Estimation of Electromagnetic plane waves

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2021年第8期68卷 2529-2543页

作者： Sadiq Akbar Muhammad Asif Zahoor Raja Naveed Ishtiaq Chaudhary Fawad Zaman Hani Alquhayz Department of Electronics University of PeshawarPeshawar25120Pakistan Future Technology Research Center National Yunlin University of Science and TechnologyDouliou64002Taiwan Department of Electrical Engineering International Islamic UniversityIslamabad44000Pakistan Department of Electrical Engineering COMSATS University IslamabadIslamabad44000Pakistan Department of Computer Science and Information College of Science in ZulfiMajmaah UniversityAl-Majmaah11952Saudi Arabia

For the last few decades,the parameter estimation of electromagnetic plane waves i.e.,far field sources,impinging on antenna array geometries has attracted a lot of researchers due to their use in radar,sonar and under water acoustic environments.In this work,nature inspired heuristics based on the flower pollination algorithm(FPA)is designed for the estimation problem of amplitude and direction of arrival of far field sources impinging on uniform linear array(ULA).Using the approximation in mean squared error sense,a fitness function of the problem is developed and the strength of the FPA is utilized for optimization of the cost function representing scenarios for various number of sources non-coherent located in the far field.The worth of the proposed FPA based nature inspired computing heuristic is established through assessment studies on fitness,histograms,cumulative distribution function and box plots analysis.The other worthy perks of the proposed scheme include simplicity of concept,ease in the implementation,extendibility and wide range of applicability to solve complex optimization problems.These salient features make the proposed approach as an attractive alternative to be exploited for solving different parameter estimation problems arising in nonlinear systems,power signal modelling,image processing and fault diagnosis.

关键词： Direction of arrival flower pollination algorithm plane waves parameter estimation

Reflection of plane waves from a micropolar thermoelastic solid half-space with impedance boundary conditions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Ocean Engineering and Science 2019年第2期4卷 122-131页

作者： Baljeet Singh Anand Kumar Yadav Deepak Gupta Department of Mathematics Post Graduate Government CollegeSector 11ChandigarhIndia Department of Mathematics M.M.University MullanaAmbalaIndia

In this paper,the governing equations of linear,isotropic,homogeneous and generalized micropolar thermoelasticity are specialized in a plane.The governing equations are solved for plane harmonic wave solutions.Two separate velocity equations are obtained which indicate the existence of four plane waves with distinct speeds.A problem on reflection of plane waves from a thermally insulated/isothermal surface is considered with impedance boundary conditions.Appropriate potentials for incident and reflected waves are formulated which satisfy the boundary conditions at a plane surface.Relations between reflection coefficients as well as the expressions of energy ratios for various reflected waves are obtained.For illustration,the reflection coefficients and energy ratios of reflected waves are computed for relevant material parameters of an aluminium-epoxy composite.Effect of impedance parameters on all reflected waves is shown graphically at each angle of incidence.

关键词： Micropolar thermoelasticity Impedance boundary plane waves Reflection coefficients Energy ratios.

Reflection and transmission of elastic waves at an interface between two micropolar piezoelectric half-spaces

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Ocean Engineering and Science 2019年第3期4卷 227-237页

作者： Baljeet Singh Asha Sangwan Jagdish Singh Department of Mathematics Post Graduate Government CollegeSector 11Chandigarh 160011India Department of Mathematics Government CollegeSamplaRohtak 124001HaryanaIndia Department of Mathematics Maharshi Dayanand UniversityRohtak 124001HaryanaIndia

In the present paper,we consider a problem of reflection and transmission of plane waves at an interface between two different transversely isotropic micropolar piezoelectric half-spaces.The plane wave solution of governing equations for micropolar piezoelectric medium indicates the propagation of three coupled plane waves.An incident plane wave at an interface between two dissimilar half-spaces generates three reflected and three transmitted waves.The relations between amplitude ratios of reflected and transmitted waves are derived which,in general,depend on material parameters and angle of incidence.The explicit expressions for energy ratios of reflected and transmitted waves are also obtained.For relevant material parameters,the results are illustrated graphically to show the micropolar piezoelectric effects on variations of amplitude ratios and the square root of energy ratios against the angle of incidence.

关键词： plane waves Micropolar piezoelectricity Reflection and transmission Amplitude ratios Energy ratios

A Modified Discontinuous GalerkinMethod for Solving Efficiently Helmholtz Problems

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2012年第2期11卷 335-350页

作者： Magdalena Grigoroscuta-Strugaru Mohamed Amara Henri Calandra Rabia Djellouli INRIA Bordeaux Sud-Ouest Research Center Team Project Magique-3D and LMA/CNRS UMR 5142Universit´e de Pau et des Pays de l’AdourFrance BCAM Basque Center for Applied MathematicsBilbaoSpain. TOTAL Avenue LarribauPauFrance Department of Mathematics California State University Northridge and Interdisciplinary Research Institute for the SciencesIRISUSA

A new solution methodology is proposed for solving efficiently Helmholtz problems.The proposed method falls in the category of the discontinuous Galerkin methods.However,unlike the existing solution methodologies,this method requires solving(a)well-posed local problems to determine the primal variable,and(b)a global positive semi-definite Hermitian system to evaluate the Lagrange multiplier needed to restore the continuity across the element edges.Illustrative numerical results obtained for two-dimensional interior Helmholtz problems are presented to assess the accuracy and the stability of the proposed solution methodology.

关键词： Helmholtz equation discontinuous Galerkin plane waves Lagrange multipliers inf-sup condition waveguide problems

ANALYSIS OF THE RETURNED SIGNAL MODEL IN BISTATIC RADAR SYSTEMS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 1997年第4期10卷 51-57页

作者： Yin Chengyou, Xu Shanjia, Wang Dongjin, Zhou Linyun (Department of Electronic Engineering and Information Science, University of Science and Technology of China, Hefei, 230027, China)

Taking the relativistic effect of high velocity moving target into account, the Doppler shift, polarization deflection, reflection coefficient and phase delay of reflected electric field are analyzed rigorously under the assumptions that incident signal to the target is a plane wave and the target is a perfect conductor plane; and their analytic expressions are obtained. The present results are of practical significance to some extent for the accurate expression of the wideband returned signal of a high velocity moving target in the bistatic radar system and for the understanding of wideband ambiguity functions.

关键词： multistatic radar plane waves relativistic effects signal model ambiguity function