fast multipole method for scattering from an arbitrary pec target above or buried in a lossy half space the fast multipole method fmm was originally developed for perfect electric conductors pecs in free space through exploitation of the spectral properties of the free space green s function in the work reported here the fmm is modified for scattering from an arbitrary three dimensional 3 d pec target above or buried in a lossy half space the near terms in the fmm are handled via the original method of moments mom analysis wherein the half space green s function is evaluated efficiently and rigorously through application of the method of complex images the far fmm interactions which employ a clustering of expansion and testing functions utilize an approximation to the green s function dyadic via real image sources and far field reflection dyadics the half space fmm algorithm is validated through comparison with results computed via a rigorous mom analysis further a detailed comparison is performed on the memory and computational requirements of the mom and fmm algorithms for a target in the vicinity of a half space interface

convergence of accelerated modulus based matrix splitting iteration methods for linear complementarity problem with an h matrix the theoretical analysis of the accelerated modulus based matrix splitting iteration methods for the solution of the large sparse linear complementarity problem is further studied the convergence conditions are presented by fully utilizing the h matrix property of the system matrix and the optimal iteration parameters in accelerated modulus based accelerated overrelaxation method are determined by minimizing the spectral radius of the iteration matrix numerical experiments further confirm the theoretical discussion and show that the proposed methods accelerate the convergence of the modulus based matrix splitting methods with less iteration steps and cpu time

absolute value equations abstract we investigate existence and nonexistence of solutions for np hard equations involving absolute values of variables ax x b where a is an arbitrary n n real matrix by utilizing an equivalence relation to the linear complementarity problem lcp we give existence results for this class of absolute value equations aves as well as a method of solution for special cases we also give nonexistence results for our ave using theorems of the alternative and other arguments

moment method analysis of large axially symmetric reflector antennas using entire domain functions the moment method technique utilizing entire domain basis functions is applied to the analysis of large axially symmetric reflector antennas the electric surface current is modeled as a finite series of sinusoids whose domain consists of the entire generating curve this expansion results in a matrix size of less than 5 of that produced with subdomain basis functions only a slight increase in the cpu requirements occurs from this analysis the results from this technique show good agreement when compared to both physical optics and a subdomain based moment method formulation on small axially fed paraboloidal and hyperboloidal reflector antennas extension to a large 100 lambda paraboloidal reflector with f d 0 4 produces results comparable to that obtained using physical optics convergence is obtained with as few as two expansion terms per wavelength discretization of the generating curve with four points per wavelength leads to results which agree within 0 5 db over data from a more densely defined curve

a fast volume integral equation solver for electromagnetic scattering from large inhomogeneous objects in planarly layered media a newly developed iterative method the stabilized biconjugate gradient fast fourier transform bcgs fft method is applied to simulate electromagnetic scattering from large inhomogeneous objects embedded in a planarly layered medium in this fast solver the weak form formulation is applied to obtain a less singular discretization of the volume electric field integral equation several techniques are utilized to speed up the dyadic green s function evaluation to accelerate the operation of the dyadic green s function on an induced current i e the green s operation the green s function is split into convolutional and correlational components so that fft can be applied the cpu time and memory cost of this bcgs fft method is o nlogn and o n respectively where n is the number of unknowns significantly more efficient than the method of moments mom as a result this method is capable of solving large scale electromagnetic scattering problems in a planarly layered background a large scale scattering problem in a layered medium with more than three million unknowns has been solved on a sun ultra 60 workstation with 1 2 gbytes memory

fast algorithm for electromagnetic scattering by buried conducting plates of large size this letter presents a fast algorithm for electromagnetic scattering by buried conducting plates of large size and arbitrary shape using the conjugate gradient cg method combined with the fast fourier transform fft due to the use of fft in handling the cyclic convolutions related to toeplitz matrices the sommerfeld integrals evaluation for the buried scattering problem which is usually time consuming has been reduced to a minimum the memory required for this algorithm is of the order n the number of unknowns and the computational complexity is of order n sub iter nlogn n sub iter is the iteration number n sub iter spl lt n for large problems

guaranteed convergence method of analysis of the scattering by an arbitrarily oriented zero thickness pec disk buried in a lossy half space in this paper a guaranteed convergence method for the accurate and efficient analysis of the electromagnetic scattering by an arbitrarily oriented zero thickness perfectly electrically conducting pec disk buried in a lossy half space is presented an electric field integral equation efie in the vector hankel transform domain is obtained by expanding the unknown surface current density in cylindrical harmonics a convergence of exponential type is achieved by means of galerkin s method with expansion functions reconstructing the expected physical behavior of the bm n th harmonic at the center and the edge of the disk the obtained coefficient matrix can be quickly computed since its elements can be reviewed as the sum of single integrals efficiently evaluable by means of an analytical acceleration technique and double integrals of exponentially decaying functions

on the solutions of a class of dual integral equations occurring in diffraction problems it is shown that there exists a category of two dimensional diffraction problems which can be put into a standard form of dual integral equations these diffraction problems include diffraction of electromagnetic waves by a finite strip a finite slit the diffraction of scalar or vector elastic waves by a rigid strip or crack etc a general method for solving such dual integral equations is given by the artifice of constructing a set of functions of compact support biorthogonal to another given set of functions the sufficient conditions for a given dual integral equations to be solvable in this manner are also determined hence the method forms a complement to the weiner hopf method to illustrate the method solutions are obtained for a bench mark problem the diffraction of light by a finite perfectly conducting strip or equivalently the diffraction of sh waves by a crack comparison with results obtained by others for low intermediate and high frequencies show the utility and accuracy of the method for the entire range of frequencies both the near field and the far field are obtained the latter is shown to correspond to the fraunhoffer diffraction pattern for high frequency it is also shown that for the equivalent crack problem the stress intensity factor sif fluctuates rapidly with changes in the angle of incidence for high frequencies thus making the sif especially sensitive to angle of incidence at high frequencies

on deriving a locally corrected nystrom scheme from a quadrature sampled moment method a novel high order method of moment procedure with quadrature point based discretization is presented the scheme is equivalent to a moment method employing smooth basis and testing functions applying a fixed point numerical quadrature approximation for the outer integral mapping the current to the quadrature points then leads to a formulation that is equivalent to that derived via the locally corrected nystrom method the convergence properties of the current density and rcs for smooth and singular geometries in two and three dimensions are also studied

a new high efficient analysis of the scattering by a perfectly conducting rectangular plate the analysis of the scattering by a perfectly conducting rectangular plate by means of galerkin s method in the spectral domain with products of chebyshev polynomials of first and second kind multiplied by their orthogonal weights as basis functions is fast convergent even for scatterers size of some wavelengths but leads to the numerical evaluation of infinite double integrals of oscillating and slowly decaying functions the aim of this paper is the introduction of a new analytical technique that allows to write such integrals as combinations of very quickly converging integrals

some techniques for solving absolute value equations in this paper we introduce and analyze two new methods for solving the np hard absolute value equations ave a x x b where a is an arbitrary n n real matrix and b rn in the case singular value of a exceeds 1 the comparison with other known methods is carried to show the effectiveness of the proposed methods for a variety of randomly generated problems the ideas and techniques of this paper may stimulate further research

gauss jacobi quadratures for weakly strongly hyper and nearly singular integrals in boundary integral equation methods for domains with sharp edges and corners abstract we present gauss jacobi quadrature rules in terms of hypergeometric functions for the discretization of weakly singular strongly singular hypersingular and nearly singular integrals that arise in integral equation formulations of potential problems for domains with sharp edges and corners the rules are tailored to weight functions with algebraic endpoint singularities of a fairly general form thus allowing one to easily incorporate a wide class of domains into the analysis numerical examples illustrate the accuracy and stability of the proposed algorithms it is shown that the same level of high accuracy can be achieved for any choice of the external variable the usefulness of the method is exemplified by application to the solution of a singular integral equation that arises in time harmonic electromagnetic scattering by either closed or open perfectly conducting cylindrical objects with edges and corners such as polygon cylinders and bent strips some practical aspects concerning the role of nearby singularities in achieving a highly accurate solution of singular integral equations are also discussed

tm scattering by perfectly conducting polygonal cross section cylinders a new surface current density expansion retaining up to the second order edge behavior in the analysis of scattering by perfectly conducting cylinders with polygonal cross section by means of surface integral operator formulations fast convergence can be achieved by expanding the surface current density on each side with basis functions factorizing the correct behavior of the fields on the wedges usually the factorized edge behavior is chosen to be coincident with the first order behavior prescribed by meixner s theory however it could not be the correct one and consequently the convergence of the method becomes increasingly slow as the theoretical behavior differs from the real one this phenomenon is particularly notable when one or more of the predicted singularities unexpectedly disappear to overcome this problem in this work the analysis of tm scattering is made by introducing a new expansion devised so that only the first two terms are responsible for the reconstruction of the singularities while the remaining part of the expansion factorizes the second order edge behavior actually the proposed expansion outperforms the one introduced by the authors in a previous work factorizing the first order edge behavior even when this is the correct one

sor like iteration method for solving absolute value equations in this paper we propose an sor like iteration method for solving the absolute value equation ave which is obtained by reformulating equivalently the ave as a two by two block nonlinear equation the convergence results of the proposed iteration method are proved under certain assumptions imposed on the involved parameter numerical experiments are given to demonstrate the feasibility robustness and effectiveness of the sor like iteration method

nystrom type method in three dimensional electromagnetic diffraction by a finite pec rotationally symmetric surface time harmonic electromagnetic wave diffraction by a perfectly electrically conducting pec finite rotationally symmetric surface located in free space is investigated the problem is split to independent azimuth orders and reduced to the sets of coupled hypersingular and singular integral equations ies for the surface current components these ies are discretized by the nystrom type method of discrete singularities using the interpolation type quadrature formulas from the solutions of corresponding matrix equations the near and the far field patterns are obtained the presented method has guaranteed convergence for arbitrary not axially symmetric primary field

the relaxed nonlinear phss like iteration method for absolute value equations finding the solution of the absolute value equation ave a x x b has attracted much attention in recent years in this paper we propose a relaxed nonlinear phss like iterative method which is more efficient than the picard hss iterative method for the ave and is a generalization of the nonlinear hss like iteration method for the ave by using the theory of nonsmooth analysis we prove the convergence of the relaxed nonlinear phss like iterative method for the ave numerical experiments are given to demonstrate the feasibility robustness and effectiveness of the relaxed nonlinear hss like method

a generalized newton method for absolute value equations associated with second order cones in this paper we introduce the absolute value equations associated with second order cones socave in short which is a generalization of the absolute value equations discussed recently in the literature it is proved that the socave is equivalent to a class of second order cone linear complementarity problems soclcp in short in particular we propose a generalized newton method for solving the socave and show that the proposed method is globally linearly and locally quadratically convergent under suitable assumptions we also report some preliminary numerical results of the proposed method for solving the socave and the soclcp which show the efficiency of the proposed method

scattering of electromagnetic waves from a rectangular plate using an enhanced stationary phase method approximation a time efficient high frequency analytical model for the calculation of the scattered field from a perfect electric conductor pec plate is presented here which is based on the physical optics po approximation and the stationary phase method spm using the spm analysis for the three dimensional 3d scattering problem under consideration the scattered electric field is calculated analytically it follows that the analytical formula proposed here yields an accurate and fast algorithm for the calculation of the scattered electromagnetic em field which can be used trustfully in a variety of radio propagation problems the accuracy of the proposed analytical method is checked through a straightforward numerical integration over the po currents as well as through finite element boundary integral full wave exact solution comparison results are given in the far field fresnel zone and the near field area

integral equation analysis of radiating structures of revolution a methods for solving radiation problems involving structures of revolution is presented that is based on the direct solutions of one dimensional integral equations for the currents the kernels of these equations are derived explicitly and their singularities are studied efficient methods for their computation are presented the numerical solution is obtained by a method of moments technique using sinusoidal basis functions applications include the determination of the current densities reflection coefficient and far field patterns for several waveguide fed structures numerical checks and comparisons with experiment demonstrate the accuracy of the method

te scattering by arbitrarily connected conducting strips the scattering by an arbitrary collection of perfectly conducting connected strips is analyzed for te incidence the studied configurations include both closed and open polygonal cross section cylinders as well as more complicated structures in which more than two strips are connected at a point the proposed method is very efficient as few expansion functions are needed in a galerkin scheme this is achieved by means of expansion functions factorizing the correct edge singularity of the electromagnetic field and ensuring the continuity of the current at connecting points

scattering by polygonal cross section dielectric cylinders at oblique incidence we analyze the scattering by polygonal cross section lossless dielectric cylinders illuminated by an obliquely incident plane wave the problem is formulated in terms of a system of surface integral equations opportunely devised so as to be valid for objects with edges and incident angles including the total reflection limit angle by means of galerkin s method in the spectral domain with analytically fourier transformable expansion functions factorizing the correct edge behaviors and continuity conditions of the unknowns convergence of exponential type is achieved and the coefficients of the scattering matrix are reduced to single integrals that can be efficiently evaluated numerical results for both near field and far field parameters are presented showing the quick convergence of the method even when applied to composite cylindrical objects

weaker convergent results of the generalized newton method for the generalized absolute value equations abstract in this paper we further analyze the generalized newton method for the generalized absolute value equations some new convergent conditions for the generalized newton method are obtained which are superior to those appeared in previously published works numerical experiments are given to demonstrate the effectiveness of the generalized newton method

full wave analysis and optimization of a tara like shield assisted paraboloidal reflector antenna using a nystrom type method using the recently developed method based on the rigorous theory of singular and hypersingular integral equations ies and nystrom type discretization a paraboloidal reflector assisted with a conical shield is investigated to decrease the computation time we propose a new method of calculation of the modal green s functions in the quasi optical range the far and near fields of the studied reflector are analyzed in the transmission and reception cases and reveal fine features that escape asymptotic analysis elementary numerical optimization of the shield assisted paraboloidal antenna is performed

method of analytical regularization in the analysis of axially symmetric excitation of imperfect circular disk antennas abstract this work presents accurate numerical method and computational results in the modeling of the axisymmetric radiation of resistive and thin dielectric circular disk on substrate antennas to simulate resistive and thin dielectric disk features we use two side generalized boundary conditions gbc the analysis is based on the singular integral equations ies and the method of analytical regularization mar exploiting a galerkin method gm with judicious basis functions which convert ies into the fredholm second kind infinite matrix equations unlike previously known numerical techniques this guarantees convergence and enables us to compute the solution with controlled accuracy even in sharp resonances numerical results demonstrate the effect of disk losses and transparency on the fundamental radiation phenomena and help improve antenna characteristics such as radiation efficiency

reflection and transmission of weakly inhomogeneous anisotropic and bianisotropic layers calculated by perturbation method with the use of perturbation theory the zero and higher order approximations are obtained for characteristic matrices reflection and transmission operators scalar reflectance and transmittance of monochromatic electromagnetic waves impinging on a transparent weakly inhomogeneous stratified bianisotropic medium the proposed procedure of perturbation series formation enables finding the corrections to the reflection and transmission factors in closed form for specified coordinate dependencies for the material tensors of the bianisotropic layers the general expressions obtained are applied to calculate the first order corrections for normal incident light on i a twisted uniaxial slab ii an isotropic medium with arbitrary inhomogeneity profile and iii a one dimensional photonic crystal with arbitrary number of layers exact and approximate solutions of the wave equations are numerically compared

diffraction of electromagnetic plane wave by a rectangular plate and a rectangular hole in the conducting plate the problems of diffraction of an electromagnetic plane wave by a perfectly conducting rectangular plate and its complementary problem diffraction by a rectangular hole in an infinite conducting plate are rigorously solved using the method of the kobayashi 1931 potential the mathematical formulation involves dual integral equations derived from the potential integrals and the boundary condition on the plane where a plate or hole is located the weighting functions in the potential integrals are determined by applying the properties of the weber schafheitlin s integrals and the solution is obtained in the form of a matrix equation illustrative computations are given for the far diffracted field pattern and the current densities induced on the plate the results of the patterns are compared with the results obtained from physical optics po and the physical theory of diffraction ptd the agreement is fairly good particularly with the ptd solutions

an efficient method for optimal correcting of absolute value equations by minimal changes in the right hand side our goal in this work is to give an optimum correction of the infeasible absolute value equations ave in order to make the mentioned system feasible we apply the minimal correction using the l 2 norm by changing just the right hand vector we will show that this problem can be formulated as an unconstrained optimization problem with a quadratic objective function we propose an extension of newton s method for solving unconstrained objective optimization some examples are provided to illustrate the efficiency and validity of our proposed method

a new method of solution of hallen s problem a wide class of electromagnetic scattering problems can be expressed as a system of dual integral equations this kind of integral equation occurring in boundary value problems wherein there is one equation for a certain region and another for the dual domain is usual in diffraction problems considerable attention has been drawn by many researchers in the field of optics acoustics scattering of elastic waves accelerator physics and antenna theory wiener hopf techniques enable us to solve such kinds of integral equations when the two regions are contiguous and semi infinite unfortunately wiener hopf techniques do not apply if one of the regions is finite this is the case for realistic scatterers such as irises antennas and drift tubes in accelerators in this article a general method for solving such dual integral equations is discussed and applied to a particular case hallen s equation of cylindrical antennas this method consists of a transformation of the dual integral equations into a fre

study of mixed order basis functions for the locally corrected nystro spl uml m method a high order locally corrected nystro spl uml m lcn method employing the mixed order basis functions proposed by c 80al spl iota s 80kan and peterson is presented for the electromagnetic scattering by targets composed of both dielectric and conducting bodies an integral operator based on a combined field formulation for conducting surfaces and a mu spl uml ller formulation for dielectric surfaces is used it is found that for general scattering objects mixed order basis functions accelerate the convergence of the lcn solution can eliminate spurious charges and can significantly reduce the condition number of the impedance matrix

diffraction by three semi infinite planes an explicit solution to the scattering of a plane wave by three parallel equidistant semi infinite planes is derived the solution involves a wiener hopf factorization of a 2 2 matrix various properties of the scattered field are obtained

closed form modal green s functions for accelerated computation of bodies of revolution to solve problems of bodies of revolution bor using the method of moments the modal green s function is used which is defined as the radiation field of a circular loop antenna with sinusoidal current distribution it is a group of oscillating integrals that forms the bottleneck for further accelerating the computation of bor problems in this paper we propose closed form expressions for near axis far distance modal green s functions which can be used to accelerate the computation of bor problems especially when the object is slim a criterion is presented based on a rigorous error analysis to guarantee its range of applications both the scattering and radiation examples are presented to demonstrate the validity and efficiency of the proposed expressions

scattering by a circular cylinder buried under a slightly rough surface the cylindrical wave approach an analytical numerical technique for the scattering problem of a plane wave by a cylinder buried under a rough surface based on the cylindrical wave approach is presented the rough deviations on the interface are dealt with by means of the small perturbation method reflection and transmission coefficients are evaluated in a first order approximation and fields are the sum of a zeroth order solution relevant to flat surface and first order perturbation fields associated to the surface roughnesses numerical results are obtained through an exact evaluation of the spectral integrals giving results both in near and far field regions for the case of an interface with sinusoidal profile the approach is validated through comparisons with the literature and results showing the effect of geometrical and physical parameters on the scattered field are reported

on the convergence analysis of two step modulus based matrix splitting iteration method for linear complementarity problems in this paper we analyze the convergence of the two step modulus based matrix splitting iteration method for the large sparse linear complementarity problems which is proposed by zhang 2011 7 the convergence conditions are presented when the system matrix is a positive definite matrix and an h matrix respectively in particular we establish new convergence conditions when the system matrix is an h matrix

wave propagation through cantor set media chaos scaling and fractal structures propagation of waves through cantor set media is investigated by renormalization group analysis for specific values of wave numbers transmission coefficients are shown to be governed by the logistic map and in the chaotic region they show sensitive dependence on small changes in parameters of the system such as the index of refraction for other values of wave numbers our numerical results suggest that light transmits completely or reflects completely by the cantor set media text c ensuremath infty it is also shown that transmission coefficients exhibit a local scaling behavior near complete transmission if the complete transmission is achieved at a wave number ensuremath kappa ensuremath kappa ensuremath ast with a rational ensuremath kappa ensuremath ast ensuremath pi the scaling function is obtained analytically by using the euler totient function and the local scaling behavior is confirmed numerically

numerical solution of the helmholtz equation in 2d and 3d using a high order nystrom discretization we show how to solve time harmonic scattering problems by means of a high order nystrom discretization of the boundary integral equations of wave scattering in 2d and 3d the novel aspect of our new method is its use of local corrections to the discretized kernel in the vicinity of the kernel singularity enhanced by local corrections the new algorithm has the simplicity and speed advantages of the traditional nystrom method but also enjoys the advantages of high order convergence for controlling solution error we explain the practical details of implementing a scattering code based on a high order nystrom discretization and demonstrate by numerical example that a scattering code based on this algorithm can achieve high order convergence to the correct answer we also demonstrate its performance advantages over a high order galerkin code

a generalization of the gauss seidel iteration method for solving absolute value equations based on the gauss seidel splitting we present a new matrix splitting iteration method called generalized gauss seidel ggs iteration method for solving the large sparse absolute value equation ave a x x b where a r n n and b r n and investigate its convergence properties moreover by preconditioning ave a preconditioned variant of the ggs pggs method is presented numerical experiments illustrate the efficiency of both ggs and pggs iterations

locally corrected multidimensional quadrature rules for singular functions accurate numerical integration of singular functions usually requires either adaptivity or product integration both interfere with fast summation techniques and thus hamper large scale computations this paper presents a method for computing highly accurate quadrature formulas for singular functions which combine well with fast summation methods given the singularity and the n nodes we first construct weights which integrate smooth functions with order k accuracy then we locally correct a small number of weights near the singularity to achieve order k accuracy on singular functions as well the method is highly efficient and runs in o nk 2d n log 2 n time and o k 2d n space we derive precise error bounds and time estimates and confirm them with numerical results which demonstrate the accuracy and efficiency of the method in large scale computations as part of our implementation we also construct a new adaptive multidimensional product gauss quadrature routine with an effective error

the diffraction of stress waves by a plane finite crack in two dimensions uniqueness and existence in this paper we consider the two dimensional problem of the diffraction of stress waves by a finite plane crack in a homogeneous isotropic elastic solid we prove that provided the elastic displacement is bounded this problem has at most one solution also by introducing a new class of green functions we are able to give a constructive proof of existence the solution is given in terms of the solution of any one of a class of fredholm integral equations of the second kind

the use of the fft for the efficient solution of the problem of electromagnetic scattering by a body of revolution the enhancement of the computational efficiency of the body of revolution scattering problem is discussed with a view of making it practical for solving large body problems the problem of the electromagnetic scattering by a perfectly conducting body is considered although the methods provided can be extended to multilayered dielectric bodies as well typically the generation of the elements of the moment method matrix consumes a major portion of the computational time it is shown how this time can be significantly reduced by manipulating the expression for the matrix elements in a manner that allows one to compute them efficiently by using the fast fourier transform fft a technique for extracting the singularity of the green s function that appears within the integrands of the matrix diagonal is also presented further enhancing the usefulness of the fft it is shown that with the use of the method discussed here the computational time can be improved by at least an order of magnitude for large bodies in comparison to that for previous algorithms

exponentially converging nystro spl uml m s methods for systems of singular integral equations with applications to open closed strip or slot loaded 2 d structures this paper concerns the fast highly accurate and exponentially convergent solution of three sets of integral equations pertaining to two dimensional generalized microstrip or microslot structures the analysis relies on nystroumlm s method with due regard to all singular integrals and slowly converging series that appear in the kernels the sophisticated treatment and efficient computation of such series and integrals is of paramount importance entailing the use of advanced techniques as a result of our specialized treatment the discretization procedures developed herein a fully account for both the singular nature of the kernels and the singularities of the solution at the edges b obviate the need for taking inner products with testing functions c appear to converge exponentially versus matrix size and d enable expressing all matrix elements via single finite sums detailed numerical examples and case studies illustrate the simplicity flexibility and remarkable efficiency of the algorithms

diffraction of elastic waves by a penny shaped crack analytical and numerical results the diffraction of time harmonic stress waves by a penny shaped crack in an infinite elastic solid is an important problem in fracture mechanics and in the theory of the ultrasonic inspection of materials martin proc r soc lond a 378 263 1981 has proved that the corresponding linear boundary value problem has precisely one solution and that this solution can be constructed by solving a two dimensional fredholm integral equation of the second kind however this integral equation has a complicated matrix kernel and the components of its vector solution are coupled the main purpose of the present paper is to show how martin s integral equation can be explicitly solved in terms of a sequence of functions each of which satisfies a very simple scalar integral equation of the second kind this simplification may be made for any incident wave for an incident plane wave further simplifications are possible we show that the solution at an arbitrary angle of incidence can be derived from the solution at a particular angle of incidence namely grazing incidence the resulting computational procedure is especially attractive if only the stressintensity factors or the far field displacements are required finally we present some numerical results for the scattering of a p wave at normal incidence and an sv wave at oblique incidence and compare these with those of other authors

a generalized newton method for absolute value equations associated with circular cones in this paper we study a class of absolute value equations associated with circular cone ccave for short which is a generalization of the absolute value equations discussed recently in the literature analogously to the fact that circular cone is the very generalization of the second order cone we show that the ccave is equivalent to a class of circular cone linear complementarity problems and hence generalize the well known equivalence between absolute value equations and linear complementarity problems useful properties of the generalized differential of the absolute value function over the circular cone are investigated which helps to propose a generalized newton method for solving the ccave the convergence of this method is established under mild conditions as well as the efficiency of which is illustrated by some preliminary numerical results

finite element analysis of complex axisymmetric radiating structures a finite element method fem is developed for the analysis of complex axisymmetric radiating structures the method is based on the electric field formulation with the transverse field expanded in terms of edge based vector basis functions and the azimuth component expanded using nodal based scalar basis functions this mixed representation of the electric field eliminates spurious solutions and permits an easy treatment of boundary conditions on conducting surfaces as well as across material interfaces the fem mesh is truncated using a previously developed cylindrical perfectly matched layer pml the method has been successfully applied to three radiating structures a corrugated horn antenna a spherical luneburg lens and a half maxwell fish eye numerical results are presented to show the validity accuracy and efficiency of the method

exponentially converging nystrom methods in scattering from infinite curved smooth strips part 1 tm case low order subdomain basis methods of moments provide little help when highly accurate electromagnetic computations are required high order modeling on the other hand can fill the need for enhanced accuracy but at the expense of greater implementation cost to supplement such methods this paper presents nystrom techniques both easily implemented and highly accurate relevant to te scattering by arbitrarily shaped smooth infinite curved strips the analysis takes full account of both the singular nature of the kernels and the singularities of the solution at the edges as a result the proposed solutions are exponentially converging in addition by eliminating inner product integrals closed form analytical expressions are obtained for all matrix elements thus our algorithms have very low implementation and computational cost detailed numerical examples and case studies amply demonstrate the efficiency stability and extremely high accuracy of the algorithms these algorithms apply uniformly from electrically small to electrically large conducting screens with only slight modifications the present analysis can be also used to obtain exponentially converging galerkin solutions

an isotropic elastic medium containing a cylindrical borehole with a rigid plug abstract an analytical and numerical analysis is made of an isotropic elastic medium containing a cylindrical borehole of infinite length in which is located a tightly fitting rigid plug of finite length both the pulling of the plug and the occurrence of a radial misfit are considered the boundary conditions are mixed with zero radial and shear stresses at the bore surface outside the plug region and displacements given across the plug surface using integral representations for a love auxiliary function the crucial step is the analytical incorporation of the square root singularity at boundary condition junctions this is done by using neumann bessel function series representations of the integrand kernels of boundary condition stresses such that discontinuous weber schafheitlin integrals can be used to satisfy these conditions exactly displacement conditions are solved in terms of integrals of products of bessel functions the solutions provide expressions for the far field behaviour of a kelvin point load solution for the plug pull case and a combined centre of expansion plus double force for radial misfit numerical results show good convergence of the method and the correct singular behaviours of borehole surface stresses

propagation of classical waves in nonperiodic media scaling properties of an optical cantor filter wave propagation through a subclass of deterministic nonperiodic media namely fractal cantor multilayer structures are investigated theoretically as well as experimentally transmission spectra of cantor structures are found to have two distinctive properties scalability and sequential splitting closely related to the geometrical peculiarities of the multilayers a systematic correlation between structural self similarity and spectral regularities of cantor multilayers is established