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Several applications of a cylindrical waveguide filled with inhomogeneous materials have been demonstrated. Analytical solutions for modes, an inhomogeneous cylindrical waveguide, are available only for a few material parameters and those are also mostly approximations. We have obtained exact analytical solutions for cylindrical waveguides filled with different inhomogeneous and anisotropic material parameters. Different sets of material parameters are obtained using the geometric transformation method. The analytical and numerical modal field distributions, the value of cutoff frequencies and effective mode indices for different propagating modes are well matched to each other. The inhomogeneity can be used to miniaturize the radial dimensions of the waveguide. This is highly desirable for many applications like sensing, near-field coupling and magnetic resonance imaging (MRI). [ABSTRACT FROM AUTHOR]

The interaction of a stratified cylinder with an elliptically inhomogeneous plane wave is introduced and also determined through a rigorous theoretical approach. The scattered electromagnetic field by a multilayered cylinder is investigated through an application of the generalized Vector Cylinder Harmonics (VCH) expansion. The exact mathematical model to represent this scenario considers the so-called complex-angle formalism reaching a superposition of Vectorial Cylindrical-Harmonics and the T-matrix formulation to contemplate the multi-scattering process between the cylinders. The validation of the procedure was accomplished with a comparison between the numerical results obtained with the Finite Element Method (FEM) in Comsol Multiphysics environment and a homemade Matlab code. [ABSTRACT FROM AUTHOR]

The guaranteed performance consensus problem for multi-agent systems with Lipschitz nonlinear dynamics is investigated, where the interaction topology is directed. Both switching and fixed interaction topologies are considered. By the matrix transformation method, the guaranteed performance consensus problems are transferred into guaranteed performance stabilisation problems. Then, the criteria of guaranteed performance consensus for nonlinear multi-agent systems with switching and fixed interaction topologies are obtained, respectively. For the introduced performance function, an upper bound is given. Finally, numerical simulations are given to demonstrate the effectiveness of the proposed results. [ABSTRACT FROM AUTHOR]

The T matrix method can be formulated to study Beltrami planewave scattering by a sphere composed of an orthorhombic dielectric magnetic material immersed in a chiral medium. Whereas an orthorhombic dielectric-magnetic material whose permeability dyadic is a scalar multiple of its permittivity dyadic is pathologically unirefringent and anisotropic. A chiral medium characterized by either a left-handedness or a right-handedness in its microstructure is birefringent and not anisotropic. The backscattering efficiency has an undulating behaviour with increase in electrical size and is highly affected by constitutive anisotropy of the sphere. Multiple lobes appear in theplots of the differential scattering efficiency when the incident field is left-circularly polarized wave. Peaks of curves of the backscattering effciency appear at lower frequencies for an incident left-circularly polarized wave and at higher frequencies for a right-circularly polarized wave incidence, if the sphere is impedance-matched to the ambient chiral medium. [ABSTRACT FROM AUTHOR]

In this paper, a light scattering model for Total Internal Reflection Microscopy (TIRM) is described. The model handles the scattering by an axisymmetric particle of arbitrary orientation situated in the evanescent field near a plane surface, and the imaging of the scattered light via microscope optics. The scattering problem is solved by using the -matrix method and the rotation addition theorem for spherical vector wave functions, while the image of the scattered field is computed by using the Debye diffraction integral. The numerical simulations provide evidence of two working regimes for TIRM: the first regime, corresponding to an incident angle less than the critical angle of total internal reflection, provides information on the size and the orientation of the particle, while the second regime, corresponding to an incident angle larger than the critical angle of total internal reflection, is recommended for measuring the distance between the particle and plane surface. [ABSTRACT FROM AUTHOR]

At present, the mainstream method is directly reduced the platform of the six series branch to six drive rods for analysis and modeling refers to inverse kinematic of the parallel six-degree-of-freedom (6-DOF) Stewart platform, and ignored the influence of the joints that excluded the driving leg on the Stewart platform, resulted in the mathematical model lack of accuracy, there is error in the actual platform. In this paper, the mathematical analysis method of inverse kinematic of the parallel six-degree-of-freedom Stewart platform based on homogeneous coordinate transformation is studied. The relationship of spatial coordinate system is worked up by using the Denavit-Hartenberg (DH) method on the upper and lower platforms and each branch of parallel 6-DOF Stewart platform. Considering the influence among the series branch joints, the transfer relationship is established by using the three-dimensional vector and the homogeneous coordinate transformation matrix between the adjacent joint coordinate systems. The length of the branch drive lever is treated as a variable, the vector equation of the platform system is deduced based on the geometric relation of the parallel 6-DOF Stewart platform. The application of this method in the kinematic inverse solution of parallel 6-DOF Stewart platform is given, verified the correctness of this method. Thinks to the data validation of the actual Stewart platform, it is proved that the proposed method can be applied to the kinematic inverse of parallel 6-DOF Stewart platform that composed of series branch. [ABSTRACT FROM AUTHOR]

This study discusses the different techniques for speed control of single-phase induction motor with two asymmetrical main and auxiliary windings based on Rotor Field-Oriented Control (RFOC) method. In the presented methods, transformation matrices are introduced and applied to the equations of single-phase induction motor. It is shown by applying these rotational transformations to the unbalanced equations of single-phase induction motor, equations of single-phase induction motor are transformed into symmetrical equations. These rotational transformations are achieved based from the steady-state equivalent circuit of single-phase induction motor. Finally, a method for RFOC of single-phase induction motor is proposed. Results show the good performance of the proposed method. [ABSTRACT FROM PUBLISHER]

In order to model the near infrared spectral difference between two instruments, this paper presents an approach based on multi-task learning for multivariate instrument standardization. A multi-task learning approach using trace norm regularization is employed to estimate the transformation matrix in direct standardization, and then is extended to the construction of the nonlinear transformation. The proposed approach is compared with the piecewise direct standardization (PDS) on two real data sets. Experimental results show that the proposed approach sometimes outperforms the conventional PDS method, and the multi-task learning method can be a promising way to overcome the over-fitting problem existing in direct standardization. [ABSTRACT FROM PUBLISHER]

The diameters of soot monomers may not be constant in the single fractal aggregated soot particle. The optical properties of light absorbing soot particles aggregated with poly-disperse monomers were studied using the superposition T-matrix method. Soot aggregates were generated with different log-normal probability distribution functions (PDF) of soot monomer diameter, according to the same soot volumes and monomer numbers. The single scattering properties of soot particles were calculated at a wavelength of 550 nm, assuming a soot refractive index of 1.95 + 0.79i and a mass density of 1.8 g/cm3. The random-orientation averaging results indicated that the optical properties of soot aggregates were fairly varied for the different distributions of the monomer diameters. In these simulations, the extinction and absorption of soot aggregates were slightly (<10%) affected by the monomer poly-dispersity. The simulated mass absorption cross-sections (MAC) of fresh dry soot particles aggregated with poly-disperse monomers reached up to 6.62 ± 0.07 m2/g, which was closer to the measurement (7.5 ± 1.2 m2/g) than the assumption of volume-equivalent mono-disperse monomer (6.36 ± 0.06 m2/g). Moreover, the optical properties of soot coated with an organic shell were calculated, and the optical results showed that the absorption cross-sections of the internally mixed soot particles were also slightly (<8%) influenced by the monomer poly-dispersity. We found that the effect of the monomer poly-dispersity on the light scattering and the single scattering albedo may be considerably large (up to ˜50% in extreme cases) for fresh dry soot aggregates. This effect on light scattering should be taken into account for those aggregates composed of monomers with widely distributed diameters. Copyright 2015 American Association for Aerosol Research [ABSTRACT FROM PUBLISHER]

This paper introduces a general inversion method to simultaneously reconstruct scatterers with different boundary conditions such as Dirichlet, Neumann, Robin, and transmission boundaries without a priori information on their locations, shapes, or physical properties. The forward scattering of mixed scatterers is modeled by a unified framework of T-matrix method, while the objective function considered in the inverse problem is solved by a subspace-based optimization method. The unknowns are T-matrix coefficients, from which the types of boundary conditions of scatterers are identified. Numerical examples show that this method is able to recover not only the shapes of scatterers but also their physical properties and parameters. [ABSTRACT FROM PUBLISHER]

A linear 3-D transformation that can be used for the enhancement of crop marks related to buried archaeological features is developed and presented in this article. The methodology is based on three steps: (1) recalculation of the ground narrowband spectroradiometric measurements to the multispectral Landsat 5 Thematic Mapper (TM) sensor, based on the relative response filter of the sensor, (2) application of principal component analysis (PCA) transformation in order to determine the initial axes used for the orthogonal transformation, followed by (3) a 3-D rotation of the PCA axes. The linear coefficients of the transformation were retrieved and adjusted to different phenological stages of the crops. The transformation was successfully evaluated using bothin situmeasurements and Landsat 5 TM images in two different archaeological case studies. The proposed transformation tends to enhance archaeological signatures better than other established vegetation indices or algorithms, while the methodology can be expanded to any other multispectral satellite images using only the visible and very near-infrared part of the spectrum. [ABSTRACT FROM PUBLISHER]

This paper addresses the problem of grid map merging for multi-robot systems, which can be resolved by acquiring the map transformation matrix (MTM) among robot maps. Without the initial correspondence or any rendezvous among robots, the only way to acquire the MTM is to find and match the common regions of individual robot maps. This paper proposes a novel map merging technique which is capable of merging individual robot maps by matching the spectral information of robot maps. The proposed technique extracts the spectra of robot maps and enhances the extracted spectra using visual landmarks. Then, the MTM is accurately acquired by finding the maximum cross-correlation among the enhanced spectra. Experimental results in outdoor environments show that the proposed technique was performed successfully. Also, the comparison result shows that the map merging errors were significantly reduced by the proposed technique. [ABSTRACT FROM AUTHOR]

We use the superposition T-matrix method to compute the linear and circular depolarization ratios for randomly oriented spheroids with an equivalent-volume size parameter kreq = 10 and absorptive inclusions (black carbon). Peterson and Strom's method was used to compute the depolarization ratios for inhomogeneous particles, together with Mishchenko's orientation averaging procedure. The effects of the size, shape and location of the core are computed and analyzed for spheroid and sphere particle. From the results, we can see that light backscattering differences by spheroid particles has to be taken into account when an inner core exists. [ABSTRACT FROM AUTHOR]

The momentum- and frequency-dependent T-matrix operator for the scattering of electromagnetic waves by a dielectric/conducting and para- or diamagnetic sphere is derived as a Mie-type series, and presented in a compact form emphasizing various symmetry properties, notably the unitarity identity. This result extends to magnetic properties one previously obtained for purely dielectric contrasts by other authors. Several situations useful to spatially-dispersive effective-medium approximations to one-body order are examined. Partial summation of the Mie series is achieved in the case of elastic scattering. [ABSTRACT FROM AUTHOR]

A new approach to the sequential design of experiments for the rapid optimization of multiple response, multiple controllable factor processes is presented. The approach is Bayesian and is based on an approximation of the cost to go of the underlying dynamic programming formulation. The approximation is based on a matrix T posterior predictive density for the predicted responses over the length of the experimental horizon that allows the responses to be cross-correlated and/or correlated over time. The case of an unknown variance is addressed; the assumed models are linear in the parameters but can be nonlinear in the factors. It is shown that the proposed approach has dual-control features, initially probing the process to reduce the parameter uncertainties and eventually converging to the desired solution. The convergence of the proposed method is numerically studied and convergence conditions discussed. Performance comparisons are given with respect to a known-parameters controller, the efficient global optimization algorithm, popular in sequential optimization of deterministic engineering metamodels, and with respect to the classical use of response surface designs followed by an optimization step. [ABSTRACT FROM AUTHOR]

A comparison is presented of a number of simulation techniques that are used to compute the scattering of electromagnetic radiation by metallic nanostructures. The simulation techniques considered here are Mie theory, the T-Matrix null-field method, the discrete-dipole approximation, the finite-element method and the finite-difference time-domain method. The suitability of each technique is compared in terms of the accuracy, computation time and the range of geometries to which it can be applied. Using each technique, we perform example calculations by simulating the optical response of an 80 nm diameter Au sphere in vacuum. Our main conclusions are summarised in tabulated form, so that the findings presented in this article may serve as a useful reference guide to those looking for suitable numerical tools to model the optical response of metallic nanostructures. [ABSTRACT FROM AUTHOR]

The electrical resistivity and absolute thermoelectric power of the liquid Cux-Bi(1-x) system have been measured over the whole composition range from the liquidus to 1100°C. The thermal conductivity is deduced from measurements of these two properties. The experimental results are interpreted and discussed in term of the extended Faber-Ziman formula using the t-matrix formalism with hard-sphere structure factors. The concentration and energy dependence of the phase shifts have been taken into account for a complete conductivity and thermopower calculation. [ABSTRACT FROM AUTHOR]

The resonance and radiation characteristics of a spherical microstrip with its circular metallic patch located inside a coating, possessing an arbitrary number of layers, are investigated. The developed methodology combines the Legendre transform with a T-matrix method. The appropriate basis functions for the surface current on the patch are chosen according to the cavity model. The complex resonant frequencies are the singular points of a homogeneous linear system, resulting by following a Galerkin's technique. The numerical results of this article propose novel multi-layered spherical microstrip configurations. More precisely, a new type of excitation that concerns an amplifying layer located between core and patch is proposed. The control mechanism of the amplifying capability via the layer's thickness and dielectric constant is reported. Moreover, the behavior of a microstrip with two airgaps that are surrounded by a zero-index material is analyzed. Finally, a coating's continuous distribution, following a “shifted” Luneburg law, is treated by a step approximation of the radial function of its dielectric constant, and the achieved high quality factor of such a microstrip is discussed. [ABSTRACT FROM AUTHOR]

The viscoelastic properties of phase‐separated poly(methyl methacrylate) (PMMA) and poly(styrene–co‐maleic anhydride) (SMA) blend systems have been investigated. It is shown that the samples of initial off‐symmetric and symmetric compositions show different characteristic viscoelastic properties, which are the reflections of different internal morphologies. Except for the well‐known characteristic deviations of the storage modulus at low frequencies, other rheological functions such as weighted relaxation spectrum, van Gurp–Palmen plots, and Cole–Cole plots also show significantly different shapes corresponding to droplet‐matrix and co‐continuous morphology. Based on these findings we propose that such characteristic fingerprints can be used for inferring the internal structure. [ABSTRACT FROM AUTHOR]

In this contribution, a fast iterative method to solve for the fields scattered by thin layers of particles is presented. The particles are randomly positioned within the layer and are characterized by means of their T -matrix. The memory complexity of the problem is reduced by dividing the layer into uniform cells. Different preconditioning techniques are applied to yield an iterative solution. The speed and the memory requirements of the presented algorithm are compared to a direct calculation approach. As an example, the scattered fields of up to 6000 dielectric spheres that are excited with a gaussian beam are calculated. [ABSTRACT FROM AUTHOR]

The T-matrix method, which is also known as the null field method (NFM) or extended boundary condition method (EBCM), has established itself as a well known and highly regarded method for calculating light scattering by non-spherical particles. Its biggest advantage is the possibility to obtain all information about the scattering characteristics of the particle and to store it into one matrix. This enables one to do additional investigations with low efforts. Unfortunately the standard NFM fails to converge for particles with extremely non-spherical particle shapes, like long cylinders or coin-like flat cylinders. In this paper we investigate light scattering by finite particles in the form of an oblate disc sphere, which can be described as flat cylinders with a rounded edge. We use an advanced form of the T-matrix method—the null field method with discrete sources (NFM-DS). By presenting light scattering results we would like to demonstrate the potential this advanced NFM-DS offers. It allows one to calculate particle shapes with aspect ratios (relation between radius and thickness of the particle) up to 100:1 and size parameters (relation between radius and wavelength) up to 30. [ABSTRACT FROM AUTHOR]

This paper describes exactly a new formulation of the T-matrix method with R-matrix expression for the electromagnetic diffraction efficiency about a case that the dielectric-coated metallic Fourier grating is illuminated by a plane wave. We show that the parameters of numerical calculations are widely applied by using R-matrix expression for the thick dielectric coating although this formulation is restricted for groove depth of the grating in a conventional T-matrix method. [ABSTRACT FROM AUTHOR]

Ferroelastic lead phosphate-type (LP) crystals undergo a sequence of phase transition $\bm{R\bar{\hbox{\bi 3}}m - C\hbox{\bi 2}/c}$ and $\bm{R\bar{\hbox{\bi 3}}m - P\hbox{\bi 2}_{\sb{\bi 1}}/c}$ [1]. The ferroic domain pattern depends on the spontaneous strain which can be diluted by the chemical composition. Light scattering from ferroelastic materials and its computer model was presented by T-matrix method at the structural phase transition. We discussed numerical procedure of T-matrix method and improved new computer program to calculate the scattering properties for domain structure of LP-type ferroelastic materials. Then, we report results of these calculations for polydispersive, randomly oriented spheroid with a refractive index, different semi-axis ratios and different size parameters. The calculation results are very close to our previous study of light scattering by spherical, cylindrical structures and convex particles. [ABSTRACT FROM AUTHOR]

First, we give a necessary and sufficient condition for torsion-free finite rank subgroups of arbitrary abelian groups to be purifiable. An abelian group G is said to be a strongly ADE decomposable group if there exists a purifiable T(G)-high subgroup of G. We use a previous result to characterize ADE decomposable groups of finite torsion-free rank. Finally, in an extreme case of strongly ADE decomposable groups, we give a necessary and sufficient condition for abelian groups of finite torsion-free rank to be splitting. [ABSTRACT FROM AUTHOR]

A computer model of light scattering from the domain structure of Pb 3 MgNb 3 O 9 (PMN) was obtained by the T-matrix method. First we discuss numerical aspects of T-matrix computations specific for ellipsoids and present results of benchmark computations for a simple ellipsoid model. Then we report results of extensive computations for poly-disperse, randomly oriented ellipsoids with the refractive index of PMN [2.15 + ki, ( k = 0.01, 0.008, 0.015)] semi-axis ratios of 1/2, 1/1.5, 1/3, 1/4 and effective size parameters ranging from 0 to 15. These computations parallel to our previous study of light scattering by poly-disperse, randomly oriented spheroids are used to compare scattering properties of two classes of particles. [ABSTRACT FROM AUTHOR]

A calculation procedure for obtaining the complete set of scattering coefficients and incident, scattered and internal electric fields in terms of the vector spherical harmonics for a multilayered nonlinear structure (as model of polydomain ferroelectric) is proposed by using the T-matrix method. [ABSTRACT FROM AUTHOR]

A methodology is described to calculate the static effective permittivity for a two-dimensional multiphase lattice composed of dielectric and/or conducting circular cylinders. This methodology uses an accurate T-matrix method to determine the dipole moments of the cylinders immersed in a uniform electric field, and then computes the effective permittivity by relating the lattice to a macroscopic model. With this methodology, the multiple scattering solution for the infinite lattice is presented in a succinct matrix-vector notation and is valid for any lattice type. The static effective permittivity equation described in this work allows us to account for the effect of all mutual interactions between the cylinders. This methodology is used to calculate the static effective permittivity for a two-phase lattice of metallic inclusions. These results are compared with the Maxwell Garnett formula and another formula presented by Kharadly and Jackson. Three additional examples are presented including two-phase dielectric lattices, multiphase lattices, and clusters. The static effective permittivity in all three situations deviates from the Maxwell Garnett result at high-volume fractions, as expected. This deviation is the most obvious for the cluster lattice because of the significant mutual coupling between the cylinders, even at relatively low-volume fraction. [ABSTRACT FROM AUTHOR]

Presents an abstract of the article `Determination of Transition Matrices for Inomogeneous Dielectric Bodies By A Wave Propagator Method,' which appeared in `Progress in Electromagnetics Research.'

Discusses the profile of a metallic Fourier grating composed of first and second sinusoidal waves. Rigorous expression presented in terms of Bessel functions; Numerical calculation of diffraction efficiencies versus incident angles; Anomalies for the surface plasmon of a gold grating.