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A microbicidal Protecting Breathing Device using an Ultraviolet Germicidal Irradiation (UVGI) air-sterilization unit, is designed and analyzed. The system is producing short-wave UV light which inactivates bacteria, viruses, and protozoa and it is connected to a full-face mask supplying sterilized inhaled air to the user and in a unique way, also sterilizes the exhaled air back to the ambient environment so covering the case of an asymptomatic transmitter. A dedicated control system is developed and built in the device for a full surveillance of the system.

From caretaking activities for elderly people to being assistive in healthcare setup, mobile and non-mobile robots have the potential to be highly applicable and serviceable. The ongoing pandemic has shown that human-to-human contact in healthcare institutions and senior homes must be limited. In this scenario, elderlies and immunocompromised individuals must be exclusively protected. Robots are a promising way to overcome this problem in assisted living environments. In addition, the advent of AI and machine learning will pave a way for intelligent robots with cognitive abilities, while enabling them to be more aware of their surroundings. In this paper, we discuss the general perspectives, potential research opportunities, and challenges arising in the area of robots in assisted living environments and present our research work pertaining to certain application scenarios, i.e., robots in rehabilitation and robots in hospital environments and pandemics, which, in turn, exhibits the growing prospects and interdisciplinary nature of the field of robots in assisted living environment.

The wavenumbers for an obliquely propagating transverse electromagnetic mode via a 3-D array of anisotropic scatterers are theoretically studied and numerically derived through a consistent method based on the dipole approximation. First, it is assumed that the anisotropic particle can be replaced with a set of dipole moments, and, in terms of its polarizabilities and the array interaction coefficients, the dispersion equation of the system is efficiently extracted. Then, the eigenmodes are rapidly retrieved using a computational non-linear equation solver scheme. The proposed technique is applied to two well-known anisotropic metamaterial scatterers, and the desired wavenumbers are accurately evaluated and successfully validated for various angles of propagation.

We present here a fully computational method for obtaining the dispersion diagrams and the field distributions of electromagnetic waves existing in periodic metamaterial structures. Using a finite-element E-B eigenmode formulation, we solve both for the complex propagation constants (eigenvalues) and the field distributions (eigenvectors) of the periodic structure at each given frequency of interest. As a result, we obtain information about the characteristics of the waves inside passbands and stopbands as well. By these means, the mechanisms of interaction of the electromagnetic waves with the eigenmodes of the metamaterials are revealed.

The optimal performance of 3-D planar metamaterial wideband devices is attained by maximizing their frequency bandgap. This, in turn, requires a design optimization procedure and iterative calculations of dispersion diagram points. To this aim, an efficient technique, blending a new mixed-order prism macroelement with an adjustable genetic algorithm (GA), is introduced in this paper for the rapid computation of dispersion diagrams. The developed scheme can launch diverse alternation orders along possible directions, whereas it is significantly more enhanced than existing approximations. In this way, the reduced degrees of freedom (DoF) facilitate the treatment of the derived eigenvalue problem and lead to a rigorous tool for the dispersion diagram of electromagnetic bandgap (EBG) structures, whose performance is intuitively optimized via the GA. For its validation, the featured method is thoroughly applied to diverse metamaterial multilayered setups with demanding geometric details and hard-to-model regions.

A near-optimal design of a log-periodic dipole array (LPDA), suitable for digital video broadcasting-terrestrial (DVB-T) reception (470–790 MHz), is presented. The LPDA is required to provide low standing wave ratio as well as high-gain radiation pattern with sufficient gain flatness over the entire passband, and concurrently achieve low gain for frequencies above 800 MHz to reject LTE800 signals and thus improve the reception quality in the DVB-T band. All the above requirements are better satisfied by applying a novel particle swarm optimization (PSO) variant, called PSO with velocity mutation (PSOvm). PSOvm induces mutation on the velocities of those particles, which are unable to improve their fitness. As shown in this paper, PSOvm comes closer to the above requirements compared to four well-known optimization methods and outperforms the traditional LPDA design method proposed by Carrel. The LPDA geometry chosen for optimization is not the conventional one, and therefore the dipoles are not considered to be included inside a specified angle as proposed by Carrel. Thus, the dipole lengths and distances as well as the boom dimensions are independently optimized. The PSOvm-based LPDA sufficiently meets all the above requirements and thus is suitable for DVB-T reception without the use of an external LTE-band rejection filter.

Nature-inspired metaheuristics of the swarm intelligence field are a powerful approach to solve electromagnetic optimization problems. Ant lion optimizer (ALO) is a nature-inspired stochastic metaheuristic that mimics the hunting behavior of ant lions using steps of random walk of ants, building traps, entrapment of ants in traps, catching preys, and re-building traps. To extend the classical single-objective ALO, this paper proposes four multiobjective ALO (MOALO) approaches using crowding distance, dominance concept for selecting the elite, and tournament selection mechanism with different schemes to select the leader. Numerical results from a multiobjective constrained brushless direct current (DC) motor design problem show that some MOALO approaches present promising performance in terms of Pareto-optimal solutions.

A versatile and straightforward human body model, comprising simple geometric structures, is consistently developed in this study for the precise electromagnetic field exposure assessment owing to mediated lightning strikes. The proposed model incorporates a realistic set of frequency-dependent media, approximated by a 4-Cole-Cole scheme, while every body part is considered to be occupied by the most dominant medium. For the reliable evaluation of all related electromagnetic quantities, the featured implementation is systematically discretised by means of an efficient finite-difference time-domain algorithm and all results are compared to those of a circuit-based approach, simulated via an electronic circuit software. Moreover, to minimise comparison errors, the most critical human body dimensions are carefully optimised. Finally, the model, so constructed, is employed for the study of a side flash impact and the investigation of a lethal electric discharge possibility through the disruptive effect technique. The benefits of the proposed realisation in the successful prediction of mediated lightning effects are thoroughly validated in terms of various real-world scenarios, which, among others, reveal that the impact on humans is inversely proportional to its distance from the stroked object.

In this paper, an efficient integral equation method is developed for the response and scattering characteristics of cloaked 2-D planar microstrip receiving antennas. The featured technique combines Green’s function for the strip-free structure with the decomposition of the strip into cylindrical thin wires and a radiation integral evaluation for the scattered field. In essence, the desired low-profile operation of the antenna is achieved by overlaying a superstrate slab atop the antenna. Moreover, an optimization process determines the constitutive parameters and thickness of the slab, so that a significantly reduced scattering behavior is obtained. Finally, the performance of the receiving antenna is investigated for a specific range of frequencies around the operating one, while the accuracy of the proposed algorithm is successfully verified through several numerical simulations.

Incorporating standard high-order spatial approximations in the alternating-direction implicit (ADI) finite-difference time-domain method does not suffice for improving the technique’s accuracy, as these operators are capable of reducing spatial errors only. We herein develop an alternative design procedure, which results in the construction of finite-difference expressions that ameliorate the combined space–time flaws. In essence, it is shown that three error formulas are derived from the individual implicit equations, provided that the ADI updates are treated as a single-step process. Then, more efficient spatial expressions can be extracted through proper manipulation of these formulas and subsequent application of error-controlling concepts.

An aperiodic reconfigurable microstrip antenna array is designed to serve as a DVB-T base station antenna operating in a single broadcasting channel. The antenna array is optimized at 698 MHz (center frequency of DVB-T channel 49) to concurrently achieve a particular radiation pattern shaping with high forward gain, main lobe tilting and null filling inside the service area, as well as low sidelobe level outside the service area, and low standing wave ratio at the inputs of all the array elements. To concurrently satisfy all the above requirements, both the geometry dimensions and the array feeding weights (amplitudes and phases) are optimized, thus leading to a complex multi-variable and multi-objective problem. The problem is solved by applying a recently developed particle swarm optimization (PSO) improved variant, called PSO with velocity mutation, in conjunction with the CST software package, which is employed by the PSOvm every time a full-wave analysis is required. Furthermore, all the optimization methods found in the CST environment are compared with the PSOvm. The results show that the PSOvm is capable of producing an antenna array geometry, which is closer to the predefined requirements than the geometries derived by the rest of the optimizers, in the least amount of computational time.

WSNs as adopted in current smart city deployments, must address demanding traffic factors and resilience in failures. Furthermore, caching of data in WSN can significantly benefit resource conservation and network performance. However, data sources generate data volumes that could not fit in the restricted data cache resources of the caching nodes. This unavoidably leads to data items been evicted and replaced. This paper aims to experimentally evaluate the prominent caching techniques in large scale networks that resemble the Smart city paradigm regarding network performance with respect to critical application and network parameters. Through respective result analysis valuable insights are provided concerning the behaviour of caching in typical large scale WSN scenarios.

The purpose of this paper is to present efficient models of new octagonal split ring resonant (O-SRR) periodic structures that can offer practical applications for electromagnetic compatibility (EMC) engineers in the area of absorbing materials. The model of an ultra-thin, compact O-SRR absorber for operation at microwave frequencies is introduced, exhibiting very high absorptive regions. The idea is extended to multi-band performance, where two different setups are demonstrated and analyzed. The physics behind the absorption mechanism for the multi-band structures is explained through the surface mechanism.

The scope of this paper is to present a systematic and versatile method, with minimal computational requirements, that incorporates the use of new electromagnetic bandgap (EBG) structures in stealth technology. Grounded structures are used to ensure zero transmittance resulting to angle independence of the incident radiation. A possible future realistic scenario is simulated and experimentally examined where a metallic plane is fully covered by EBG structures and the monostatic radar cross section is measured. Varying the angle of incidence from 0 ° to 90 °, it is observed that for the worst case scenario the reduction of the monostatic radar cross section (RCS) is almost 19 dB. Finally, to verify our idea, the RCS of a metallic cube also fully covered by EBG structures was examined. The assets of the proposed concept, applied to the design of different patterns, appear to be potentially beneficial for various electromagnetic interference/electromagnetic compatibility configurations.

A further example of multi-band absorption using ultra-thin, polarization-insensitive, wide-angled metamaterial absorbers that operate in multi-frequency bands within the microwave regime is presented in this work. The basic structure geometry is utilised to create multi-band highly absorbing structures by incorporating the scalability property of the metamaterials. Simulation results verify the structure’s ability for high absorption. The multi-band absorbers are promising candidates as absorbing elements in scientific and technical applications because of its multi-band absorption, polarization insensitivity, and wide-angle response. Finally, the current distributions for those structures are presented to gain a better insight into the physics behind the multiple absorption mechanism.

The finite-difference time-domain method is herein combined with polynomial-chaos expansions for the study of axially-symmetric structures featuring material uncertainties. By exploiting the problem's periodicity, we reduce the high computational burden of fully 3D simulations, and reliably extract the necessary statistical information from a single simulation.

A finite-difference time-domain (FDTD) method for simulating wave propagation in Havriliak-Negami (H-N) dispersive media is presented. In an H-N medium, the time-domain polarization relation involves a fractional differential operator, whose analytical evaluation is troublesome. Moreover, if the fractional differential operator is approximated by a sum of fractional time derivatives, the numerical treatment of the polarization relation results in significant memory storage demands, because fractional derivatives are not local. However, by an appropriate approximation of the Grunwald-Letnikov definition of fractional derivatives, an FDTD scheme with reasonable memory requirements is feasible. In particular, the coefficients that appear in the Grunwald-Letnikov definition are approximated by sums of decaying exponentials. As a result, the FDTD scheme is based on recursive equations, while a limited number of auxiliary vectors need to be stored. The proposed scheme has been applied successfully to the simulation of the excitation of an H-N medium by a wideband Gaussian electromagnetic pulse.

We present here a 3-D E-B linear eigenmode formulation for the analysis of periodic structures, including lossy periodic waveguides, photonic crystals, and metamaterials. The proposed finite-element formulation utilizes proper H (curl) vector basis functions for the electric field and H (div) vector basis functions for magnetic flux density. The resulting eigenmode problem is linear, and it enforces periodic boundary conditions in a simple manner via appropriate field transformations and does not exhibit spurious modes. Moreover, it can provide accurate complex-k dispersion diagrams, in terms of both propagation and attenuation constant, while it is also able to deal with either propagating or evanescent modes, including those with oblique propagation directions.

The purpose of this chapter is to offer a survey of the EU funded projects within the scope of Internet of Things and ambient assisted living (AAL) environments. Our analysis concentrates on three main aspects: on the projects’ technical objectives, on the target population group, and on the in-field trials and planned use-cases of each project. For a fair and meaningful comparison, we emphasize to the set of projects that are based on mobile robotic platforms for AAL environments.

The consistent modeling of microwave components with random fluctuations regarding their electromagnetic material parameters is performed in this paper via a 3-D stochastic finite-difference time-domain method. The featured formulation provides precise numerical results with a considerably smaller computational cost compared to the extensively resource-consuming Monte Carlo approach. Numerical simulations of microstrip transmission lines with media uncertainties are conducted in order to verify the accuracy of the proposed technique along with its effectiveness to investigate the operation of complicated microwave structures in a stochastic environment.

The propagating modes on a magnetically biased curved graphene microstrip are thoroughly examined in the present work by means of an efficient finite element modal solver. The influence of the anisotropic surface conductivity due to the magnetic bias is carefully addressed and investigated through a multitude of numerical results, including the effective index and the electric field distribution of the dominant modes.

Aiming at the minimization of numerical dispersion effects in finite-difference time-domain (FDTD) simulations, we investigate the potential of introducing frequency-dependent coefficients in the approximations of differential operators. The proposed methodology exploits some previous results on optimized finite-differences, but initially avoids the necessity for selecting a specific optimization point. Herein, the operators' coefficient formulae are approximated by a low-order polynomial, which is transformed into a finite-difference counterpart using the Helmholtz equation. This modifies the initial spatial stencil and improves performance over all frequencies, which can be further controlled with the least-squares method, leading to various new FDTD schemes of augmented reliability.

We present a series of designs for uniplanar electromagnetic bandgap structures for antennas and microwave circuits. The proposed, easy to fabricate configurations, are based solely on metallic surfaces on layer interfaces, without the use of vias or other kinds of vertical connections. Their use in low profile antenna applications and mutual coupling reduction of planar radiating elements is investigated through an efficient and versatile technique, since the only information needed is the reflection phase and the dispersion diagram of the unit cell.

The accurate and fully 3-D analysis of graphene surface conductivity models by means of a frequency-dependent finite-difference time-domain method is introduced in this paper. For the infinite sheet to be consistently simulated, the novel technique uses a set of periodic boundary conditions that lead to a unit cell excited with a spectral scheme in terms of a total-field/scattered-field formulation. On the other hand, graphene itself is modeled through a subcell approach and a complex surface conductivity concept defined by quantum mechanical equations. This conductivity model is next converted to a volume one in order to permit a realistic time-domain study. Numerical outcomes, addressing a variety of applications, reveal a promising coincidence with those acquired from analytical closed-form expressions.

The uniplanar cross-like compact EBG structure is thoroughly assessed by means of a computational FEM-based eigenvalue analysis. A careful inspection of the dispersion diagram reveals the existence of a nearly-TEM mode that compromises the bandgap behavior, a fact that is also confirmed in coupling performance investigations. The structure is then modified and optimized to maximize the resulting bandgap zone, for mutual coupling reduction in WiMAX MIMO arrays.

A new solution to the problem of implementing extended-stencil finite-difference operators across material interfaces is presented in this paper for time-domain electromagnetic simulations. In essence, modified spatial approximations are applied within a transition layer that encloses the discontinuity, while preserving the stencil size of the scheme employed in the homogeneous areas. The necessary difference expressions are determined with the aid of a straightforward design procedure, which is based on the reliable modeling of exact solutions, following a one-dimensional formulation. The proposed approach, whose beneficial effects are exemplified via numerical simulations, is analyzed for the case of the (2,4) method. Yet, its concepts are global and easily adapted to any discretization algorithm.

The systematic construction of a 3D generalized explicit method with adjustable mesh density is presented in this paper for the consistent analysis of large-scale applications. The novel algorithm introduces a parametric hybridization of a conformal multimodal finite-difference time-domain and a curvilinear pseudospectral time-domain technique which lead to optimized simulations. Updated independently, these procedures are interconnected by flexible boundary conditions and Runge-Kutta integrators, while their media sensitivity receives efficient tuning. Further enhancement is achieved via stencil patterns that exploit structural periodicity. So, the proposed schemes yield highly precise and affordable results devoid of grid errors, as certified by several real-world problems.

An enhanced 3-D alternating-direction implicit finite-difference time-domain method for the systematic analysis of double negative metamaterial-based waveguide and antenna devices is presented in this paper. Being fully frequency-dependent, the new scheme introduces a set of generalized multidirectional operators which incorporate the suitable Lorentz-Drude model and subdue inherent lattice deficiencies for broad spectra. So dispersion errors, as time-steps exceed the Courant limit, are drastically minimized yielding fast and accurate solutions for propagating and evanescent waves. The technique is applied in the design of microwave structures, realized via the prior model or networks of thin wires and split-ring resonators. Numerical results certify its merits, without requiring elongated simulations and excessive overheads

A site-specific numerical model, based on the finite-difference time-domain method, is developed in this paper for the indoor radio channel. The scenario of interest is concerned with wave propagation in a typical office environment, for which several simulations are performed considering different placements of the transmitting antenna. Both the 2- and 5-GHz bands are examined, where contemporary wireless local area networks operate. Important channel characteristics are evaluated via the estimation of received power levels, as well as the examination of small-scale fading and time dispersion

A consistent technique for the highly accurate solution of partial differential equations (PDEs) that control the advancement of various electromagnetic field problems is presented in this paper. The new algorithm secedes from the rigid finite-differencing framework of most mainstream time-domain approaches, casting all governing PDEs into space-time form to obtain a robust temporal update process. Spatial discretization, on the other hand, is conducted by truncating the proper Fourier spectrum via a windowing operation and inversion of the ensuing filtered series. So, the proposed schemes allow the stable extraction of discrete transfer-function equivalents and decrease the overall dispersion error, as proven by various instructive applications

This paper presents a curvilinearly‐established finite‐difference time‐domain methodology for the enhanced 3D analysis of electromagnetic and acoustic propagation in generalised electromagnetic compatibility devices, junctions or bent ducts. Based on an exact multimodal decomposition and a higher‐order differencing topology, the new technique successfully treats complex systems of varying cross‐section and guarantees the consistent evaluation of their scattering parameters or resonance frequencies. To subdue the non‐separable modes at the structures' interfaces, a convergent grid approach is developed, while the tough case of abrupt excitations is also studied. Thus, the proposed algorithm attains significant accuracy and savings, as numerically verified by various practical problems.

A systematic, non‐orthogonal FDTD algorithm for the unified and fully dual construction of curvilinear PMLs in 3‐D lossy electromagnetic and advective acoustic problems, is presented in this paper. Postulating a consistent mathematical formulation, the novel methodology introduces a set of general vector parametric equations that describe wave propagation in both media and facilitate the effective treatment of the remarkably complex, arbitrarily‐aligned (non‐uniform) source or mean flow terms, particularly at low frequencies. The discretization procedure is performed via accurate higher‐order FDTD topological concepts, which along with a well‐posed variable transformation, suppress the undesired lattice dispersion and anisotropy errors. Hence, due to these additional degrees of design freedom and their optimal establishment, the new stable PMLs (split‐field or Maxwellian) accomplish a critical attenuation of the evanescent, vorticity or elastic wave families by carefully accounting for every loss mechanism. Numerical investigation reveals the superiority of the proposed technique in terms of various open‐region, waveguide and ducted‐domain simulations.

This paper presents a general explicit finite-difference time-domain scheme for transient nonlinear electromagnetic eddy-current problems. Some existing methods are discussed, while the DuFort-Frankel algorithm is chosen for its simplicity and efficiency. The problem of domain termination is efficiently treated by means of a perfectly matched layer for eddy currents. The proposed algorithm isolates the exterior static problem from the interior explicit algorithm, thus involving only a reduced and easier system matrix solution.

In this paper, we present a general explicit finite difference time domain (FDTD) algorithm for transient electromagnetic problems at low frequencies. A detailed theoretical analysis is given, based on a nonstandard finite difference scheme, which is studied in terms of stability and consistency. The study reveals a whole class of finite difference diffusion schemes with different properties. Some of the existing methods are special cases of this general framework and an optimal algorithm is proposed. The application of finite difference methods to eddy current problems requires the introduction of a hybrid methodology, which combines the explicit differencing scheme for the diffusion equation with a boundary element method (BEM) for the open regions. The resulting algorithm involves a simple time stepping iteration, without any system solution, thus being remarkably robust.

The path integral analysis has been used to examine the propagation of a Gaussian beam in two cases. First in free space and second in a space with a non‐penetrable obstacle, placed parallel to the direction of propagation. Full analytical equations have been given in both cases and results have been taken in the same spatial coordinates in order to facilitate comparisons. No numerical instabilities have been observed and the method seems to be quite tractable and easily extended in spaces with more that one obstacle.

A finite element formulation for the solution of 3D eddy current problems in terms of the electric intensity E is presented. A weak formulation, based on a Galerkin weighted residual procedure, is presented and edge elements, that impose only tangential continuity across element interfaces of the approximated field, are employed for the discretization of the problem with the finite element method. The reliability and validity of the suggested method is verified by its application to the calculation of the 3D eddy current distribution in two conducting systems.

In this paper we propose a new explicit Whitney Element-Time-Domain method for the solution of Maxwell's equations in three dimensions. This scheme could be considered a generalization of the well known Finite Difference Time Domain (FDTD) method for unstructured meshes. However, an entirely different methodology is introduced, based on the use of higher order tangential and normal vector finite elements. The exploitation of higher order approximations in an elaborate leapfrog scheme permits the use of the primary mesh only, thus avoiding the implementation of dual mesh. The new method is, finally, applied to a typical high frequency electromagnetic field formulation.

In the present paper, a simplified human body, stroked by a lightning touch voltage, is implemented via lumped elements and analysed through the finite-difference time-domain (FDTD) method. The results, so extracted, are compared with those of an electronic circuit simulator. Furthermore, the current induced to the human body in the vicinity of a lightning stroked object, is accurately calculated by the FDTD algorithm, which overwhelms the circuit modeller that is unable to simulate non-contact scenarios.

A full vector beam propagation method, which is based on the split-operator approach, is developed and it is applied on 3-D z-dependent structures. The coupling between the transverse and axial components of the electric field, which stems from the variation of the refractive index along the direction of propagation, is fully retained. Various numerical implementations are proposed and assessed. Numerical applications are from the field of integrated optics.

The evaluation of eddy currents in cylindrical geometries is examined analytically by using a method, which utilises the second order magnetic vector potential. As an example the three‐dimensional problem of the calculation of eddy currents inside a long conducting cylinder excited by a saddle shaped coil is studied.

In this paper a new technique for mutual coupling reduction of uniplanar MIMO antennas is presented. The only necessary information needed, is the transmission coefficient of a plane wave which is propagating over a specific structure, of a new proposed geometry.

In this paper, the design of novel, polarization-insensitive metamaterial absorbers that operate in the microwave regime is presented. The proposed unit cell comprises an electric ring resonator and a pair of crossed wires imprinted on the opposite faces of a dielectric substrate. The performance of the structure can be further enhanced by adding multiple layers of the optimized surface along the propagation direction, while keeping the dimensions of the device relatively small compared to the wavelength. Finally, unit cells designed for different resonant frequencies can be placed adjacent to each other in order to create multiple absorption bands. The results of the proposed concept appear to be very promising for various EMI/EMC applications.

A boundary element technique is applied to an integral formulation of the electromagnetic field quantities, of the electric vector and magnetic scalar potentials for the evaluation of the propagation phenomenon in stratified media, of planar or cylindrical geometry, due to electric dipole sources. The use of the above described potentials simplify the solution procedure, because of the degrees of freedom, which can de introduced in choosing relations between the field quantities. The main goal of these relations is to make the numerical solution easier, while the Maxwell equations and the boundary conditions remain unaffected. Besides a three‐dimensional problem is treated as a two dimensional one. Results and plots of the field, are given for both cases of the geometry. The method can be used for determining the field inside the earth in geological studies, propagation in stratified media, cable technology, shielding problems e.t.c.

The solution of a 3-dimensional problem is, almost in all cases, a quite difficult task, since a great computational effort is required. AT-Ω method accompanied by a boundary element technique is presented for the evaluation of the field inside a conducting cylinder of finite length. The excitation is a current dipole with harmonic time variation (electric Hertzian dipole), located somewhere inside the cylinder. According to the method the problem is split into smaller independent successive problems, requiring much less computational effort.

A method is presented for the calculation of the electromagnetic field in systems of single-layer or multilayer coaxial cylindrical shells of infinite length excited by an oscillating current source arbitrarily oriented inside the first shell. The electric vector potential T and the magnetic scalar potential Omega are used for the evaluation of the quantities of the problem. The Helmholtz equations for T and Omega are transformed into integral equations by the use of the Green's function method. Applying the boundary element method, three systems of simultaneous equations have to be solved to give the sought field quantity. >

A method, which is using the electric vector potential T and the magnetic scalar potential Ω is presented for the calculation of the electro‐magnetic field inside conducting cylinders of infinite length.The current source is an oscillating current dipole arbitrarilly oriented. The Green's function method is used for the transformation of the Helmholtz's equations for T and Ω into integral ones. Finally a boundary element technique is used to obtain a system of simultaneous equations. In this system the number of the unknows is greater than the number of the availiable simultaneous equations.Thus some additional conditions between the field quantities, have to be added to the boundary conditions to obtain the final solution of the problem. Problems of electrical machines, electromagnetic shielding or even, problems related to human bodies can be treated with the following analysis.

The consistent and cost-effective modeling of large-scale EMC structures, is presented in this paper via a novel parametric hybrid method. The proposed scheme blends a stencil-optimized time-domain algorithm in curvilinear coordinates and a modified finite-element time-domain approach to divide the problem into smaller flexible regions. Constructing a class of curvilinear 3-D operators, the framework assigns weights to each spatial increment and approximates spatial derivatives through interpolating polynomials. An important asset is that the two techniques are updated independently and interconnected by versatile boundary conditions. Numerical results from different realistic EMC setups verify our method and reveal its universal applicability.