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In this investigation, the far-field scattering of luminescent molecules doped inside a layer of the plasmonic metallic nanoshells with and without the presence of an external point-like electric charge based on the quasistatic approximation is theoretically developed. We study the fluorescence emission from three types of multilayered plasmonic nanoparticles with the spherical shape by evaluating the far-field scattering cross section. In other words, we investigate how the plasmonic nanoshells having a luminescent layer alters the fluorescence emission of active molecules. It is found that a frequency shift in the spectrum is achieved which is strongly sensitive to the geometry and size of the particle and also the tunability increases with the number of layers. This behavior is an important key advantage for the design of plasmonic devices. Also, the calculations show that when an electric charge is positioned near the plasmonic nanoshell, the number of resonance modes increases. The results demonstrate that the fluorescence emission of the luminescent layer is affected when an external point charge is placed next to the multilayer plasmonic nanoshell. [ABSTRACT FROM AUTHOR]

It is shown that the application of the universal Lindhard function for calculating the scattering cross section of atomic particles is, as a rule, limited to the region of scattering angles less than 20°. The results obtained for various popular interaction potentials are compared with the available experimental data. It is shown that the presence of inelastic channels in scattering leads to the appearance of additional maxima in the scattering cross section. Recommendations are given on the use of the universal Lindhard function to describe quasi-elastic scattering in the region η = εsin(θ/2) > 0.01, ε is the reduced impact energy, θ is the scattering angle. At high energies, the scattering is well described by screened Coulomb potentials, and the application of the Lindhard function provides an accuracy of 10% for calculating the scattering cross sections. [ABSTRACT FROM AUTHOR]

In this paper, a characteristic mode (CM)-based design methodology is developed for the reconfigurable microwave metasurface absorbers (MMA) with using commercially available substrates. Theoretical intrinsic connection between modal behaviors and absorption properties is first formulated for the design of the structures. As a proof of the method, a broadband MMA consisting of butterfly elements is step-by-step designed. The positions and values of the impedance loading are determined based on the modal significances and modal currents for broadband operation. The absorption performance is evaluated by the formulated theoretical model and verified by full-wave simulation. After that, a flexible implementation a employed for free-form surfaces conformal. Experimentally, the proposed MMA is fabricated and measured. The absorption fractional bandwidth with reflectivity less than –10 dB is achieved from 3.6 to 11.6 GHz (105%). Good agreements between the simulation and measurement results for both planar and cylindrical cases validate the developed CM-based design methodology. The mimicry of time-varying scattering cross section (SCS) is then further realized through real-time coding absorption states, which is a promising candidate for practical electromagnetic systems.

The scattering of electromagnetic waves by isotropic dielectric cylinders can be dramatically modified by means of vanadium dioxide ( VO 2 ) thin-film coatings. Efficient dynamic control of scattering is achieved due to the variations in material parameters realizable by means of external biasing. In this paper, we study the scattering of terahertz waves in a case where the coating shells are made of VO 2 , a phase-change material, whose thin films may work rather as electromagnetic phase screens in the insulator material phase, but as lossy quasi-metallic components in the metallic material phase. The shells that uniformly cover the dielectric cylinders are investigated. Attention will be paid to the demonstration of the potential of VO 2 in the external control of diverse scattering regimes of the dielectric- VO 2 core–shell scatterer, while conductivity of VO 2 corresponds to rather insignificant variations in temperature. In line with the purposes of this work, it is shown that the different resonant and nonresonant regimes have different sensitivity to the variations in VO 2 conductivity. Both the total scattering cross section and field distributions inside and around the core are studied, as well as the angle-dependent scattering cross section. [ABSTRACT FROM AUTHOR]

The spherical and parabolic wave functions are calculated for the generalized MIC–Kepler system in the continuous spectrum. It is shown that the coefficients of the parabola–sphere and sphere–parabola expansion are expressed in terms of the generalized hypergeometric function . The quantum mechanical problem of scattering in the generalized MIC–Kepler system is solved. [ABSTRACT FROM AUTHOR]

We explored the optical properties of silver and gold nanospheres by light and electron spectroscopy techniques for applications in light trapping. We first studied the nanoparticles by transmission electron microscopy (TEM) and UV–visible which showed the redshift of surface plasmon frequency with the increase in particle size. The plasmonic properties of isolated nanospheres were probed with high spatial resolution using scanning transmission electron microscope (STEM) fitted with an electron energy loss spectrometer (EELS). The particles were then deposited on bismuth ferrite (BiFeO3) thin films via the drop-casting technique and the light trapping effect was studied by specular reflectance. Two configurations of incident light were used, frontal and rear light incidence. In the former configuration, the light impinges frontally on the nanoparticles and in the latter configuration the light passes first through the BiFeO3 film before hitting the particles. In the frontal configuration, the reflectance showed a significant decrease compared to the case without nanoparticles which was associated with two phenomena: absorption and scattering toward the BiFeO3 film. In order to elucidate which phenomenon predominates, the rear measurement was performed where the scattered light inside the substrate is captured by the detector. In rear reflectance, there was an increase in intensity for large silver nanoparticles compared to the case without nanoparticles revealing that more light was directed inside the substrate. These observations were interpreted by simulations which showed that the best particles for light trapping are silver spheres larger than 60 nm. The results are of potential interest for emerging solar cells considering light trapping. [ABSTRACT FROM AUTHOR]

The scattering cross section of massless scalar waves in the background of an Ayón–Beato–García electrically charged regular black hole is investigated. We obtain the scattering pattern by numerically solving the Klein–Gordon equation. We show that it is possible to find configurations for which the Ayón–Beato–García regular black hole can mimic the scattering properties of the Reissner–Nordström black hole, for arbitrary values of the scattering angle and of the wave frequency, considering low‐to‐moderate values of the normalized electric charge. Our results suggest that the scattering spectra of regular and standard black holes can be indistinguishable. [ABSTRACT FROM AUTHOR]

Enhanced scattering from local surface plasmon resonance by light has attracted much attention due to its special applications in sensor, cell, and biological imaging. Here, we investigate the ratio of scattering to absorption in bimetallic three-layered nanoshells with different geometrical parameters using quasi-static theory. We show that the ratio of scattering to absorption strongly depends on the inner radius, shell thickness, middle dielectric function, and surrounding medium function. To gain insight into the effect of such geometrical parameters on the plasmonic scattering, we also provide a comparison between silver–dielectric–gold nanoshells and gold–dielectric–silver nanoshells. This work provides an alternative approach to analyze the optical properties of bimetallic three-layered nanoshells with potential applications in sensors and photo-detectors. [ABSTRACT FROM AUTHOR]

A complex cylindrical structure consisting of a group of parallel stratified circular lossy dielectric cylinders, embedded in a dielectric circular cylindrical region and surrounded by unbounded dielectric space, is considered in this paper. The scattering of electromagnetic (EM) plane waves by the aforementioned configuration was studied; the EM waves impinged obliquely upon the structure and were arbitrarily polarized. The formulation used was based on the boundary-value approach coupled with the generalized separation of variables method. The EM field in each region of space was expanded in cylindrical wave-functions. Furthermore, the translational addition theorem of these functions was applied in order to match the EM field components on any cylindrical interface and enforce the boundary conditions. The end result of the analysis is an infinite set of linear algebraic equations with the wave amplitudes as unknowns. The system is solved by the truncation of series and unknowns and then matrix inversion; thus, we provide a semi-analytical solution for the scattered far-field and, as a consequence, for the scattering cross section of the complex cylindrical structure. The numerical results focus on calculations of the electric- and magnetic-field intensity of the far-field as well as of the total scattering cross section of several geometric configurations that fall within the aforementioned general structure. The effect of the geometrical and electrical characteristics of the structure on the scattered field was investigated. Specifically, the cylinders' size and spacing, their conductivity and permittivity as well as the incidence direction were modified in order to probe how these variations are imprinted on scattering. Moreover, comparisons with previously published results, as well as convergence tests, were performed; all tests and comparisons proved to be successful. [ABSTRACT FROM AUTHOR]

One of the ways to use a focused ion beam in lithographic processes to create nanostructures is through the exposure of special sensitive materials, i.e., resists. As a result of exposure, the solubility of such a material increases ("positive" resist) or, conversely, decreases ("negative" resist). Subsequent selective irradiation and development of the resist make it possible to create a predetermined pattern on the substrate. This work is aimed at developing the theoretical foundations for this ion lithography method. A practically important case of stopping heavy ions in an organic resist, the average atomic mass of which is much less than the mass of the incident ion, is considered. Expressions for the "energy" and transport lengths of ions are obtained. The calculations are carried out assuming a power-law interaction potential. The "energy" length characterizes the depth of penetration of ions into the material, and the transport length is related to beam expansion due to scattering. Therefore, these lengths are the main characteristics of the zone in which the ion-beam energy is absorbed. [ABSTRACT FROM AUTHOR]

A new approach based artificial electromagnetic materials (AEMMs) with low transmission loss is proposed for phase array scattering cross section (SCS) reduction. By putting an AEMM unit with different transmission phase above a phased array element, a new array element with different scattering phase can be constructed. Then, a low‐SCS array aperture can be synthesized based on the new element by taking advantage of its tunable scattering phase. An 8 × 8 array prototype is fabricated to validate the radiation and scattering characteristics of the proposed low‐SCS phased array. The measured results indicate that its SCS is controlled in the operating bandwidth of the phased array antenna with an acceptable degradation of radiation characteristics. [ABSTRACT FROM AUTHOR]

Electromagnetic response of clustered charged particles is the foundation of electromagnetic wave interaction with various natural phenomena, such as sandstorm, cloud, and volcano eruption. Previous studies usually employed assumption of independent charged particles, without considering the coupling between them. Here, we build up a general numerical model considering the multiple scattering effect, and test it with a charged two- and four-particle system. The numerical results show that independence assumption fails, while the number density of clustered charged particles is getting larger. This work may pave the way for deeper understanding on the electromagnetic interaction of clustered charged particles.

A one‐dimensional (1‐D) ultra‐wideband conformal connected slot array with reduced scattering characteristics is presented. The proposed array accomplishes a practical design completely conformal to a wing platform by closely attaching the antenna aperture to the curved surface. A conformal metamaterial absorber (CMA) structure is employed to control the out‐of‐band scattering, and the resistive patches are analyzed for the reduction of radiation loss. Additionally, a parasitic metal block is introduced for the improvement of VSWRs in the low‐frequency band. The designed 1‐D infinite array is able to achieve 4:1 impedance bandwidth from 0.5 to 2.0 GHz with an active VSWR <3.0 for scanning up to ±45°. In comparison with the reference array, a significant monostatic scattering reduction is achieved from 6.0 to 18.0 GHz with the radiation performances well preserved. The overall thickness of the conformal array is only about 0.31λh at the highest operating frequency. A 2 × 8 conformal array prototype is fabricated and measured. Measured results are in good agreement with simulated ones, thus demonstrating effectiveness. [ABSTRACT FROM AUTHOR]

Using limit transitions in the general relations for the surface relaxation and radiation damping rates in a prolate and an oblate ellipsoidal nanoparticle, the corresponding expressions for rod-shaped and disk-shaped particles are obtained. The frequency dependences of the statistically averaged efficiencies of the absorption and scattering of electromagnetic radiation by nanoparticles of different shapes are calculated. Calculations were performed for Au, Ag, Cu, and Pt nanostructures. The effect of the shape and material of the nanoparticle on the number and position of the maxima and the absorption and scattering efficiency is analyzed. It is found that the presence of two maxima in the frequency dependence of the scattering efficiency for nanodisks is associated with the manifestation of a longitudinal and transverse surface plasmon resonance. [ABSTRACT FROM AUTHOR]

A complex cylindrical structure consisting of a group of parallel stratified circular lossy dielectric cylinders, embedded in a dielectric circular cylindrical region and surrounded by unbounded dielectric space, is considered in this paper. The scattering of electromagnetic (EM) plane waves by the aforementioned configuration was studied; the EM waves impinged obliquely upon the structure and were arbitrarily polarized. The formulation used was based on the boundary-value approach coupled with the generalized separation of variables method. The EM field in each region of space was expanded in cylindrical wave-functions. Furthermore, the translational addition theorem of these functions was applied in order to match the EM field components on any cylindrical interface and enforce the boundary conditions. The end result of the analysis is an infinite set of linear algebraic equations with the wave amplitudes as unknowns. The system is solved by the truncation of series and unknowns and then matrix inversion; thus, we provide a semi-analytical solution for the scattered far-field and, as a consequence, for the scattering cross section of the complex cylindrical structure. The numerical results focus on calculations of the electric- and magnetic-field intensity of the far-field as well as of the total scattering cross section of several geometric configurations that fall within the aforementioned general structure. The effect of the geometrical and electrical characteristics of the structure on the scattered field was investigated. Specifically, the cylinders’ size and spacing, their conductivity and permittivity as well as the incidence direction were modified in order to probe how these variations are imprinted on scattering. Moreover, comparisons with previously published results, as well as convergence tests, were performed; all tests and comparisons proved to be successful.

The cascade multiplication of atoms in a solid target is considered theoretically for different types of scattering cross section. The solution of the transport equation in some cases is found in an analytical form, in others it is reduced to numerical integration. Formulas are obtained for the energy distribution and the total number of cascade atoms, as well as for the total cascade energy as functions of the target depth and the type of atomic interaction. The theoretical results generalize the Landau–Rumer theory of cascade showers to the case of arbitrary types of atomic potentials, from the hard-sphere potential to the Coulomb potential. [ABSTRACT FROM AUTHOR]

The authors proposed analytical models applicable to monolayer and multilayer mantle cloaks for suppressing the scattering fields of electrically large conducting objects using printed ultrathin metasurfaces. To analyse the proposed structure, the two‐sided impedance surface method is used and the scattering cross section (SCS) is obtained using Mie theory. It is shown that using surface impedance expression obtained from the analytical model for monolayer mantle cloak they can design a proper unit cell of a metasurface to reduce significantly total scattering from the cylinder. The proposed mantle cloaks in this work are mainly designed to minimise simultaneously several scattering multi‐poles of a relatively large object around considerably broad bandwidth. Numerical results and full‐wave simulation show good cloaking performance in designed frequency. The simulated results using their analytical models as well as the full‐wave results show that the multilayer mantle cloak is an optimised candidate for cloaking of electrically large objects. The proposed multilayer mantle cloak confirms 3.6 dB SCS gain to cancel the scattering fields of a perfect electric conductor cylinder with a radius of 1.425λ0 at the designed frequency. Finally, they consider a cluster of closely spaced and overlapping three cloaked cylinders for suppression of electromagnetic fields.

In recent years, a progressive interest in the implementation of wireless access to cardiovascular implants has been established. This manifests in new devices, such as arterial pressure sensors, or additional functionalities added to established implants like stents. However, common stent designs, possessing highly optimized mechanical properties, often consist of cylindrically arranged struts with connections in-between which can be considered as short-circuited inductive coils. As a consequence, the small inductance raises the resonance frequency, which may decrease the in vivo performance of the wireless connection between the stent and the external readout device. Thus, new designs were developed to overcome this limitation, for example by avoiding the short-circuit due to a helical arrangement of the struts. Within this work we compare the performance of a common stent design and a helical design by means of numerical simulations. We are using two designs which only differ in the arrangement of the struts. The electromagnetic and mechanical properties are investigated using a finitedifference time-domain algorithm and finite element method, respectively. We will show that a common stent design exhibits resonance frequencies in the gigahertz regime, much higher than the frequencies of comparable helical designs. Furthermore, we compare the mechanical performance of the two designs and reveal individual distinctions in the radial stiffness, bending stiffness, and the von Mises stress.

Herein, we report quasi-static theory-based simulations on size-asymmetric Au and Ag nanosphere dimers in which size-dependent damping induced by the electron-surface interaction is prominent. The sensitivity of plasmon-hybridized modes of both asymmetric nanodimers with respect to the size ratio of the nanospheres forming nanodimer, the refractive index of surrounding medium, nanogap, and the local dielectric perturbation in the surrounding medium in the presence of the semi-infinite substrate is studied systematically. In each case, the theoretical sensitivity value is estimated for parallel and perpendicular polarizations. Moreover, for comparison, the dependence of plasmon modes of size-symmetric nanosphere dimers on the size-dependent damping is investigated. [ABSTRACT FROM AUTHOR]

An approach for improving the invisibility performance of mantle cloak is proposed. It is based on an interesting observation that the cloaking performance of mantle cloak can be significantly enhanced if the cloak is operated under tilted conditions with respect to the incident radiation (such that the wave is incident obliquely onto the cloak). The mantle cloak is thus designed by judiciously choosing the value of surface impedance corresponding to the tilt angle. It is because the optimum value of surface impedance changes with the tilt angle. An analytical method is devised for the calculation of optimum surface impedance under tilted conditions and subsequently verified with Ansys HFSS simulations. It is also shown that by deliberately tilting the mantle cloak, numerous advantages over normal incidence scenario, are obtained, such as (a) significant reduction in total scattering width, (b) considerable enhancement in bandwidth, and (c) increase in performance robustness with respect to the dispersion of surface impedance. These advantages of operating under tilted conditions are well elucidated by comparing it with that for normal incidence scenario previously presented in various literatures. The metasurface cloak is subsequently realized using I-shaped unit cell structure and varactor diodes, and cloaking performance is analyzed using HFSS simulations. [ABSTRACT FROM AUTHOR]

In this paper, the scattering characteristics an infinite dielectric periodic surface are investigated in detail. The Fourier expression of scattering field of the periodic surface is obtained by using the Rayleigh hypothesis and the Floquet theorem. Using the extended boundary condition method and the T‐matrix method, the scattering amplitude factor is solved, and the correctness of the algorithm is verified by use of the law of energy conservation. The scattering cross section of the periodic surface in the infinitely long region is derived by improving the formula of the finite one as its length is increased. Furthermore, the effects of the incident wave parameters and geometric structure parameters on the scattering of the periodic surface are analyzed and discussed. The results show that the period and amplitude of the surface corrugations determine the number of scattering intensity peaks, and influence the scattering intensity distribution with permittivity significantly. Key Points: By use of extended boundary condition method (EBCM) and T‐matrix method, the scattering amplitude factor is solvedThe scattering cross section of the infinite periodic surface is derived by extending the length of the finite periodic surfaceThe scattering characteristics of dielectric periodic surfaces with several important parameters (such as period, amplitude, and incident angle) are investigated [ABSTRACT FROM AUTHOR]

Scattering of plane electromagnetic waves by a dielectric circular cylinder in the vicinity of a conducting strip is presented. Two methods of solution are introduced. The first is an exact solution in which the scattered field from conducting strip is expressed in terms of Fourier series of radial and angular Mathieu function of unknown coefficient. Meanwhile the scattered field from the circular cylinder is expressed in terms of Fourier series of Bessel functions of unknown coefficient. The unknown coefficient can be obtained by enforcing the boundary conditions. The application of the boundary condition requires the use of the addition theorem of Mathieu to Bessel functions and vice versa. The second method is based in an asymptotic technique introduced by Karp and Russek for solving scattering by wide slit. The technique assumes the total scattered field from the strip and the dielectric cylinder as the sum of the scattered fields from the individual element due to a plane incident wave plus scattered fields from factious line sources of unknown intensity located at the center of every element. The line sources account for the multiple scattering effect. By enforcing the boundary conditions, the intensity of the line sources can be calculated. Numerical examples are calculated using both methods showing excellent agreement in all cases. [ABSTRACT FROM AUTHOR]

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The motion of a self-propelled body excites internal waves that modulate wind-induced microscale waves and affect the radar scattering cross section of rough sea surfaces. This process is closely related to factors such as stratification, propulsion effect, and radar parameters. Based on this, this study establishes and partially verifies a computational model for the scattering cross section of the internal wave wake left by an underwater self-propelled body. The model incorporates the first-order resonant internal waves of the stratified flow field as the dominant component of the wake-effect internal waves and determines the equivalent source size using the wake evolution model, thereby effectively simulating the characteristics of the surface flow field when the net momentum of the underwater vessel is nonzero. By solving the wave-action conservation equations, the wave spectrum of the modulated surface is derived, and the tilt and convergence/divergence effects caused by internal waves are comprehensively considered through the facet scattering model to assess their impact on the synthetic aperture radar (SAR) scattering cross section. Overall, this study systematically elucidates the correlation mechanism between the flow field and the radar system. • Obtaining the internal wave wake field of a nonstationary moving object based on quality and equivalent momentum sources. • Probing the modulation of microscale waves at the sea surface by the velocity field of the internal wave wake based on the conservation of wave action. • Investigating the scattering fieldby considering the Bragg effect of short wavesand the tilted effect of internal and surface long waves. [ABSTRACT FROM AUTHOR]

[Display omitted] • Detailed theoretical study of structural, spectroscopic and electron scattering cross section study of glycolaldehyde. • Quantum chemical calculations for ground and excited states are performed using DFT and TD-DFT methods. • In the absence of sufficient experimental data on excited states of glycolaldehyde, we compare VES calculations with the available experimental data for an analogous molecule acetaldehyde. • Maiden theoretical attempt to provide Low-energy (0.1 to 20 eV) scattering cross-sectional data using R-matrix method. • We have detected one π* shape resonance in all the three models viz. SE, SEP and CC model. Detailed theoretical investigations on structural, spectroscopic and electron scattering cross sections of glycolaldehyde, the first ever detected sugar in space are reported in this work. Spectroscopic calculations are performed on the ground and excited states of glycolaldehyde using density functional theory (DFT) and time-dependent density functional theory (TDDFT), respectively. The optimized geometrical parameters and vibrational spectrum are in good agreement with the earlier reported work. Vertical excited state (VES) energies at the TDDFT/B3LYP/aug-cc-PVQZ level of theory along with detailed assignments are reported up to 30 transitions. The TDDFT predicted Rydberg series energies are compared with the Rydberg series of glycolaldehyde converging to its first IP, computed using the standard Rydberg formula and are found to be in good agreement. In the absence of sufficient experimental data on excited states of glycolaldehyde, the theoretical results are validated by comparison of VES calculations performed at the same level of theory with the available experimental data for an analogous molecule viz. acetaldehyde. Triplet excited-state energies for glycolaldehyde are reported here for the first time. Electron impact cross section calculations in the energy range 0.1 to 20 eV are carried out using ab-initio R-matrix method. We have detected one π* shape resonance in all the three models viz. SE, SEP and CC, which may also lead to a possible fragmentation channel wherein a hydrogen atom is removed from the molecule forming a glycolaldehyde dehydrogenated anionic radical (C 2 H 3 O 2 −). The π* shape resonance is correlated with the corresponding molecular orbital electronic structure calculations. Additionally, differential, electronic excitation, ionization and total cross sections are reported here for the first time. [ABSTRACT FROM AUTHOR]

The low-energy spectrum of ions reflected from the surface of a solid is calculated theoretically and by means of the computer simulation method. The theory is based on numerical solution of the transport equation by of the method of discrete streams; and computer simulation, on the model of binary collisions and local inelastic energy losses. It is shown that, for small energies of reflected ions, their energy distributions are described by the universal formula containing the only constant. The value of this constant varies weakly when passing from the hard-core potential to the Coulomb one. [ABSTRACT FROM AUTHOR]

Scattering of ultrashort electromagnetic pulses on the dense strongly coupled plasma is under consideration in the frame of hard ion sphere model. The electron distribution inside the ion sphere is obtained from self‐consistent solution of the Shrodinger equation for bound electrons and the Poisson equation for free electrons. The electron density distribution is determined by plasma electron temperatures. The ion density of Al plasmas under consideration is of the order of 1020–1022 cm−3, the electron temperature changes between 54 and 816 eV. Dynamical polarizability of the hard sphere determining the scattering cross sections is calculated using the modified local plasma frequency approximation. The spectrum of scattering cross section has maxima in the vicinity of the mean plasma frequency. Dependencies of scattering probability on carrier frequency and pulse duration are analysed in detail. The transition of the total scattering probabilities from nonlinear time dependence at small times to standard linear ones with the increase of pulse duration is demonstrated. [ABSTRACT FROM AUTHOR]

The authors proposed analytical models applicable to monolayer and multilayer mantle cloaks for suppressing the scattering fields of electrically large conducting objects using printed ultrathin metasurfaces. To analyse the proposed structure, the two‐sided impedance surface method is used and the scattering cross section (SCS) is obtained using Mie theory. It is shown that using surface impedance expression obtained from the analytical model for monolayer mantle cloak they can design a proper unit cell of a metasurface to reduce significantly total scattering from the cylinder. The proposed mantle cloaks in this work are mainly designed to minimise simultaneously several scattering multi‐poles of a relatively large object around considerably broad bandwidth. Numerical results and full‐wave simulation show good cloaking performance in designed frequency. The simulated results using their analytical models as well as the full‐wave results show that the multilayer mantle cloak is an optimised candidate for cloaking of electrically large objects. The proposed multilayer mantle cloak confirms 3.6 dB SCS gain to cancel the scattering fields of a perfect electric conductor cylinder with a radius of 1.425λ0 at the designed frequency. Finally, they consider a cluster of closely spaced and overlapping three cloaked cylinders for suppression of electromagnetic fields. [ABSTRACT FROM AUTHOR]

An analytic solution is presented to the scattering of a left circularly polarized (LCP) plane wave from a chiral elliptic cylinder placed in another infinite chiral medium, using the method of separation of variables. The incident, scattered, as well as the transmitted electromagnetic fields are expressed using appropriate angular and radial Mathieu functions and expansion coefficients. The unknown scattered and transmitted field expansion coefficients are subsequently determined by imposing proper boundary conditions at the surface of the elliptic cylinder. Numerical results are presented graphically as normalized scattering widths for elliptic cylinders of different sizes and chiral materials, to show the effects of these on the scattering widths. [ABSTRACT FROM AUTHOR]

The scattering of in-plane P- and SV-waves by a multi-coated circular nanofiber with deformable interfaces is of interest. To this end, in the present work, after introducing two kinds of interface momenta defined as the derivative of the interface excess kinetic energy with respect to the average and relative velocities at the interface, we extend the elastostatic theory of Gurtin et al. (1998) on deformable interfaces to the elastodynamic theory and derive the interface equations of motion using Hamilton principle. The effects of the generalized interface properties including the interface inertial parameters and interface stiffness towards stretch and slip on the dynamic stress concentration factor and the scattering cross section will be examined through some numerical examples. These results reveal that the effect of the interface inertial parameters becomes significant as the frequency of the incident wave increases. Moreover, as it will be shown, in the case where the interfaces are treated to be deformable, a larger number of resonance modes are captured for low-frequency waves as a result of the compliancy of the interfaces. It will also be seen that the resonant frequencies pertinent to the local deformations of the interface, increase with the interface stiffness parameters and decrease with the interface inertial parameters introduced in this work. These results can be used for tuning the resonant frequencies by selecting appropriate geometrical sizes and materials. Such phenomena can also be useful for designing locally resonant sonic materials with nano-sized lattice parameters. [ABSTRACT FROM AUTHOR]

An analytical dependence of the cross section for the small-angle scattering of polarized neutrons at spin waves in helimagnets formed because of Dzyaloshinskii—Moriya interaction in cubic crystals without an inversion center (the space group is P213) is obtained. It is assumed that the dispersion of spin waves in helimagnets with the wave vector ks polarized by a magnetic field is larger than the critical field HC2 of the transition to the ferromagnetic phase and has the form Eq = A(q − ks ) + gμB(H − HС2). It is shown that the cross section for neutron scattering at the two-dimensional map of angles (θx, θy) is two circles of the radii θC with the centers ±θS, corresponding to the Bragg angle of diffraction by a helix oriented along the applied magnetic field H. The radii of these two circles θC are directly related to the stiffness of spin waves A of the magnetic system and depends on the applied magnetic field: θC2=θ02−gμBHEnθ0, where θ0=h22Amn and En and mn are the neutron energy and mass. It is shown that the scattering cross section depends on the neutron polarization, which is evidence of the chiral character of spin waves in the Dzyaloshinskii—Moriya helimagnets even in the completely polarized phase. The cases of neutron scattering at magnons where θ0 ≤ θS and θS ≥ θ0 are considered. The case of neutron scattering at spin waves in helimagnets is compared with analogous scattering at ferromagnets where θS → 0. [ABSTRACT FROM AUTHOR]