Two-layer Planar Research Articles

Resonance magnetoelectric effect in a three-layer non-symmetric ring structure Ni/PZT/Metglas

The resonant magnetoelectric (ME) effect in a ring-type structure of nickel–lead zirconate titanate–Metglas amorphous alloy (Metglas 2605SA1) has been studied. The use of ring geometry and magnetic layers with different signs of magnetostriction and comparable saturation fields led to a noticeable enhancement in the ME coefficient and a decrease in the optimal bias field, as compared with two-layer planar heterostructures. At the frequency of radial acoustic oscillations of the structure and under circular magnetization, the ME coefficient of 6.4 V (Oe·cm)−1 and ac field sensitivity of 0.6 V Oe−1 were obtained for a permanent bias field of 2 Oe.

Two-Layer Planar Rectangular Inductors and Their Electrical Models for Increased Inductance Density and Figure-of-Merit

This article presents two-layer planar rectangular inductors for increased inductance density and figure-of-merit (FOM). The equivalent lumped electrical models of the proposed inductors are developed. The model consists of the mutual inductance, parasitic capacitance, and self-inductance of the inductor. The closed-form expression for the mutual inductance is derived using the magnetic field law. Two different inductor geometries are developed and fabricated on FR4 substrate, and these are doubly wound top bottom (DWTB) and singly wound top bottom (SWTB) inductors. Four different geometries of DWTB and SWTB inductors are fabricated for analytical and experimental verification. Close agreement is observed between simulated and experimentally measured inductance. Among both, the measured results show that the proposed DWTB inductor has the highest inductance density of 24.43 (nH/mm) for an inductance of 122.2 nH, and a quality factor of 55.06. In addition, the FOM of the proposed SWTB inductor is 52.44, with a self-resonance frequency (SRF) of 386 MHz, and within outer dimension of 4 mm. The proposed inductor design is applicable to any dielectric substrate and scalable for different frequencies of operation.

Planar metal-only omnidirectional retroreflector using transmitarray and blazed grating for TE and TM polarizations.

Retroreflector is a device that reflects light along its incident direction over a continuous range of incident angles. The retroreflectors proposed so far are so bulky and uneven that they cannot be mounted on large structures. Recently, two-layer planar retroreflectors have been proposed in the field of optics and acoustics, but at microwave frequencies only one retroreflector with non-planar overall structure has been presented that doesn't cover omnidirectional incidence and only supports TM polarization. The term omnidirectional means the capability of retroreflectivity in all azimuth angles (φi) and a wide elevation angle (θi) range. In this paper, a novel planar and metal-only retroreflector is proposed at microwave frequencies that efficiently reflects the electromagnetic wave along its incident direction in omnidirectional angle range and supports both TE and TM polarization. The proposed structure consists of two separate cascaded layers. The top layer is a transmitarray structure in which incident waves with different angles are focused at different locations on the bottom layer. The bottom layer reflects back focused waves along its focus direction and two distinct structures are proposed to implement it. The first type is a novel spatially varying blazed grating and the second type is a spatially varying phase gradient metasurface, as used in the optics and aucostics. The first type offers omnidirectional property for both TE and TM polarization while the second type offers higher monostatic RCS for only TE polarization. Simulated and measured results of the proposed retroreflector with the first type bottom layer show an omnidirectional retroreflectivity with half-power (3-dB RCS level) elevation field of view of 60° (-30°to 30°) at frequency of 10 GHz with a normal incidence efficiency of 63%.

Carbon nanotubes films in glass fiber polymer matrix forming structures with high absorption and shielding performance in X-Band

Thin films based on carbon nanotubes materials are used to form layered structures for electromagnetic absorption and shielding applications over X-Band. Measurements in a WR-90 waveguide with a Vector Network Analyzer are carried out to determine the dielectric characteristics of the materials. Samples of graphene and carbon nanotubes are constructed in an epoxy resin polymeric matrix as a one-layer structure. A two-layer structure based on epoxy resin and glass fiber combined with carbon nanotubes films is also examined. Films have a thickness of around 70 μm and have a significant effect in the attenuation of the electromagnetic field. A decrease of more than 20 dB in the Transmission Coefficient can be achieved even with few carbon nanotubes films placed intermediately in a glass fiber polymer matrix. Simulated results compared to measurements of the waveguide setup show satisfactory agreement. Planar layers composed of the above materials are also examined for electromagnetic absorption and shielding performance. A one-layer planar structure that consists of the above carbon nanotubes films in a glass fiber polymer matrix and has a total thickness of 2.7 mm is proposed. It is intended for high shielding effectiveness applications presenting a shielding effectiveness variating between 27 dB and 42 dB over X-Band. However, for both high shielding and absorption applications, a two-layer planar structure with a total thickness of 5.7 mm is designed. The structure consists of successive carbon nanotubes films in a glass fiber polymer matrix as the bottom layer and carbon nanotubes in an epoxy resin matrix as the top layer. The structure presents a shielding effectiveness between 27 dB and 40 dB over X-Band while absorption can reach 95% around 10 GHz. As shown, adding carbon nanotubes in film structure, even with a thickness in the order of μm, inside a polymer matrix can greatly increase the electromagnetic shielding and absorption performance showing also a high attenuation of electromagnetic field.

Efficient Near-Field Beamforming Using Two-Layer Planar Loop Array for Magnetic Resonance Wireless Power Transfer

This letter presents efficient near-field beamforming using two-layer planar loop array resonator for magnetic resonance wireless power transfer (MR WPT). This two-layer structure provides enhanced power transfer efficiency (PTE) of two important functions by adjusting the lumped capacitance of each loop: beamforming and ability of spatial position freedom and spatial alignment freedom with the receiver. The optimal capacitance of each loop can be found using a genetic algorithm (GA). The three types of two-layer loop arrays such as 1 × 1 and 4 × 4, 2 × 2 and 4 × 4, and 4 × 4 and 4 × 4 are designed at an operating frequency of 6.78 MHz. Overall, these two-layer loop arrays improve the overall simulated PTE compared with that of the 4 × 4 single-layer loop array. Especially, the twolayer loop array of 2 × 2 and 4 × 4 provides the most improved beamforming performance and spatial freedom among them. The measured PTE also increases by about 10% compared with that of the 4 × 4 single-layer loop array.

Simultaneous estimation of parameters in analyzing porous medium combustion—assessment of seven optimization tools

ABSTRACTSimultaneous estimation of the gas velocity, scattering albedo, and downstream pore diameter in a two-layer planar porous matrix involving combined mode conduction, convection, and radiation heat transfer with combustion is reported. Non-local thermal equilibrium between the gas and the solid phase is accounted by separate energy equations for the two phases. Performances of the genetic algorithm, genetic algorithm parallel, simulated annealing, multiple starting point algorithm parallel, pattern search algorithm, pattern search algorithm parallel, and global search algorithm in the simultaneous estimation of three parameters are analyzed. All the algorithms utilize a priori knowledge of the axial gas temperature distribution, and the magnitudes of the convective and the radiative heat fluxes at the outer surface of the porous matrix. With volumetric radiative information needed in the solid phase energy equation computed using the discrete transfer method, the two energy equations are simultaneously solved using the finite volume method. Pattern search algorithm provides better estimation, and computationally it is also the fastest.

Invisibility andPTsymmetry

For a general complex scattering potential defined on a real line, we show that the equations governing invisibility of the potential are invariant under the combined action of parity and time-reversal ($\mathcal{P}\mathcal{T}$) transformation. We determine the $\mathcal{P}\mathcal{T}$-symmetric as well as non-$\mathcal{P}\mathcal{T}$-symmetric invisible configurations of an easily realizable exactly solvable model that consists of a two-layer planar slab consisting of optically active material. Our analysis shows that although $\mathcal{P}\mathcal{T}$ symmetry is neither necessary nor sufficient for the invisibility of a scattering potential, it plays an important role in the characterization of the invisible configurations. A byproduct of our investigation is the discovery of certain configurations of our model that are effectively reflectionless in a spectral range as wide as several hundred nanometers.

Capacitive humidity sensor with a coplanar electrode structure based on anodised porous alumina film

A simple and new relative humidity (RH) capacitive sensor with a two-layer planar structure based on anodic aluminium oxide (AAO) film serving as a sensing layer has been fabricated. A pair of separated tantalum thin films under the AAO layer served as two coplanar electrodes. AAO film was fabricated by anodising deposited aluminium thin film in oxalic acid. The influence of the pore size and thickness of the AAO film, and the electrode spacing, on the performance of the sensor was investigated. The RH sensor with a thicker AAO film and narrower electrode spacing was more sensitive. By pore widening, the sensitivity of the sensor can be improved. The achieved average sensitivity as high as ∼3.57 pF/RH% was obtained for sensors with an AAO layer of 2 µm thickness and 80 nm pore size. These results were explained using the partial capacitance method and parallel-serial model. In addition, under the humidity range of 20–80%, sensors with 70 nm pores had the highest sensitivity, which was interpreted in terms of effective permittivity and anion concentration. This study provides an easy method to fabricate high-performance humidity sensors with very simple structures for practical applications.

Numerical Simulation of Fire Resistance Performance for Planar Frame with Concrete Filled Steel Tubular Columns and Steel Beams

In this paper, the fire resistance performance of the unprotected two-layer and two-cross planar frame, which is composed of concrete filled steel tubular columns and steel beams, was analyzed under local fire by ANSYS. After analyzing the structure with the method of hot - structural coupling using standard heating curve ISO-834, some consequence were obtained such as the regularity of temperature field distribution of beams and columns and the fire endurance and critical temperature of the structure. It turned out that the bottom flange at the end of the beams appeared local buckling when the structure reached the limit state by fire, and the first plastic hinge appeared at the end of beams. Furthermore, because the horizontal displacement of column is small, the overall collapse of structure can be avoided effectively.

Transient two-layer thin-film flow

The transient two-layer thin-film planar flow is investigated theoretically in this study. The interplay among inertia, viscous and surface/interfacial tension is emphasized. It is found that the film and interface profiles, as well as the flow field, are strongly influenced by the viscosity ratio, velocity and film thickness ratios at inception, and the surface-to-interfacial tension ratio. The nonlinear stability of the steady state reveals the formation of a solitary wave after flow inception, which propagates in the form of a convective instability, with the steady state recovered only in the tail (upstream) region of the wave. In the presence of surface/interfacial tension, surface modulation appears, which grows in wavelength and amplitude with position. The flow is found to be particularly stable for higher viscosity of the lower film layer. Copyright © 2010 John Wiley & Sons, Ltd.

Low-frequency magnetoelectric effect in a Galfenol-PZT planar composite structure

The forward and inverse magnetoelectric (ME) effects are experimentally studied in a two-layer planar structure containing mechanically coupled Galfenol and PZT plates. The process of production of polycrystalline Galfenol plates and their magnetic and magnetostriction characteristics are described. For the forward ME conversion, the dependences of the amplitude of the voltage generated by the structure on the magnitude and orientation of a dc magnetic field and the frequency and amplitude of a modulating magnetic field are measured. For the inverse ME conversion, the dependences of the amplitude of the change in the magnetic induction of the structure on the dc magnetic field and the frequency of an ac electric field applied to the structure are measured. The efficiencies of the forward and inverse ME conversion are estimated for the case of low-frequency field modulation and under conditions of the resonance excitation of bending and longitudinal mechanical vibrations in the structure.

Steady two-layer gravity-driven thin-film flow

Steady two-layer thin-film planar flow under gravity is investigated theoretically in this study. The film is assumed to emerge out of a channel and flow over a straight plate. The interplay among inertia, viscous and surface or interfacial tension is emphasized. It is found that the film and interface profiles, as well as the flow field, are strongly influenced by the viscosity ratio, film thickness ratio at inception, and surface-to-interfacial tension ratio. In the absence of surface and interfacial tension, the profiles of the film layers vary monotonically streamwise. The surface tension effect leads to waviness in layer profiles, with increasing wave number as the surface tension effect is reduced.

Analytical Solution of Two-Layer Beam Taking into account Interlayer Slip and Shear Deformation

A mathematical model is proposed and its analytical solution derived for the analysis of the geometrically and materially linear two-layer beams with different material and geometric characteristics of an individual layer. The model takes into account the effect of the transverse shear deformation on displacements in each layer. The analytical study is carried out to evaluate the influence of the transverse shear deformation on the static and kinematic quantities. We study a simply supported two-layer planar beam subjected to the uniformly distributed load. Parametric studies have been performed to investigate the influence of shear by varying material and geometric parameters, such as interlayer slip modulus (K), flexural-to-shear moduli ratios (E∕G) and span-to-depth ratios (L∕h). The comparison of the results for vertical deflections shows that shear deformations are more important for high slip modulus, for “short” beams with small L∕h ratios, and beams with high E∕G ratios. In these cases, the effect of the shear deformations becomes significant and has to be addressed in design. It also becomes apparent that models, which consider the partial interaction between the layers, should be employed if beams have very flexible connections.

Locking-free two-layer Timoshenko beam element with interlayer slip

A new locking-free strain-based finite element formulation for the numerical treatment of linear static analysis of two-layer planar composite beams with interlayer slip is proposed. In this formulation, the modified principle of virtual work is introduced as a basis for the finite element discretization. The linear kinematic equations are included into the principle by the procedure, similar to that of Lagrangian multipliers. A strain field vector remains the only unknown function to be interpolated in the finite element implementation of the principle. In contrast with some of the displacement-based and mixed finite element formulations of the composite beams with interlayer slip, the present formulation is completely locking-free. Hence, there are no shear and slip locking, poor convergence and stress oscillations in these finite elements. The generalization of the composite beam theory with the consideration of the Timoshenko beam theory for the individual component of a composite beam represents a substantial contribution in the field of analysis of non-slender composite beams with an interlayer slip. An extension of the present formulation to the non-linear material problems is straightforward. As only a few finite elements are needed to describe a composite beam with great precision, the new finite element formulations is perfectly suited for practical calculations.

An Efficient Neural Algorithm for Two-layer Planarization Problem in Graph Drawing

A neural algorithm for the two-layer planarization problem using a gradient ascent learning of the Hopfield network is presented. This algorithm which is designed to embed a two-layer graph on a plane, uses the Hopfield network to get a near-maximal two-layer planar subgraph, and increases the energy by modifying the weights and the thresholds in gradient ascent direction to help the network escape from the state of near-maximal two-layer planar subgraph to the state of the maximal two-layer planar subgraph. The experimental results show that the proposed algorithm generates much better solutions than traditional Hopfield network and simulated annealing.

Supernova Experiments on the Nova Laser

Supernova (SN) 1987A focused attention on the critical role of hydrodynamic instabilities in the evolution of supernovae. To test the modeling of these instabilities, we are developing laboratory experiments of hydrodynamic mixing under conditions relevant to supernovae. Initial results were reported by Kane et al. in a recent paper. The Nova laser is used to generate a 10-15 Mbar shock at the interface of a two-layer planar target, which triggers perturbation growth, due to the Richtmeyer-Meshkov instability, and to the Rayleigh-Taylor instability as the interface decelerates. This resembles the hydrodynamics of the He-H interface of a Type II supernova at intermediate times, up to a few times 103 s. The experiment is modeled using the hydrodynamics codes HYADES and CALE, and the supernova code PROMETHEUS. Results of the experiments and simulations are presented. We also present new analysis of the bubble velocity, a study of two-dimensional versus three-dimensional difference in growth at the He-H interface of SN 1987A, and designs for two-dimensional versus three-dimensional hydro experiments.

Scaling supernova hydrodynamics to the laboratory

Supernova (SN) 1987A focused attention on the critical role of hydrodynamic instabilities in the evolution of supernovae. To test the modeling of these instabilities, we are developing laboratory experiments of hydrodynamic mixing under conditions relevant to supernovae. Initial results were reported in J. Kane et al. [Astrophys. J. 478, L75 (1997) and B. A. Remington et al., Phys. Plasmas 4, 1994 (1997)]. The Nova laser is used to generate a 10–15 Mbar shock at the interface of a two-layer planar target, which triggers perturbation growth due to the Richtmyer–Meshkov instability, and to the Rayleigh–Taylor instability as the interface decelerates. This resembles the hydrodynamics of the He-H interface of a Type II supernova at intermediate times, up to a few ×103 s. The scaling of hydrodynamics on microscopic laser scales to the SN-size scales is presented. The experiment is modeled using the hydrodynamics codes HYADES [J. T. Larson and S. M. Lane, J. Quant. Spect. Rad. Trans. 51, 179 (1994)] and CALE [R. T. Barton, Numerical Astrophysics (Jones and Bartlett, Boston, 1985), pp. 482–497], and the supernova code PROMETHEUS [P. R. Woodward and P. Collela, J. Comp. Phys. 54, 115 (1984)]. Results of the experiments and simulations are presented. Analysis of the spike-and-bubble velocities using potential flow theory and Ott thin-shell theory is presented, as well as a study of 2D versus 3D differences in perturbation growth at the He-H interface of SN 1987A.

Modeling and calculation of the capacitance of a planar capacitor containing a ferroelectric thin film

The capacitance of a two-layer planar capacitor containing a thin layer of SrTiO3 is calculated by conformal mapping using the partial capacitanc e method. Simple formulas are obtained for approximation calculation of the capacitances of individual components of a planar structure, and their limits of applicability are determined. A relation for the capacitance of a planar capacitor is derived which takes account of the size effect in a ferroelectric film within the context of the partial capacitance method. The calculated result is compared with the experimentally measured capacitance.

A two-layer planar microwave absorber

A two-layer microwave absorber on a planar conducting surface is considered. Design equations are presented for material and geometric parameters leading to zero reflection under normal incidence. The special case of a lossy magnetic layer followed by a lossy dielectric layer is studied in detail and design curves are provided. A broad low-reflection bandwidth is demonstrated © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 15: 170–173, 1997.

Supernova-relevant Hydrodynamic Instability Experiments on the Nova Laser

Supernova 1987A focused attention on the critical role of hydrodynamic instabilities in the evolution of supernovae. To test the modeling of these instabilities, we are developing laboratory experiments of hydrodynamic mixing under conditions relevant to supernovae. The target consists of a two-layer planar package composed of 85 μm Cu backed by 500 μm CH2, having a single-mode sinusoidal perturbation at the interface, with λ = 200 μm and η0 = 20 μm. The Nova Laser is used to generate a 10-15 Mbar [(10-15) × 1012 dyne cm2] shock at the interface, which triggers perturbation growth as a result of the Richtmyer-Meshkov instability, followed by the Rayleigh-Taylor instability as the interface decelerates. This resembles the hydrodynamics of the He-H interface of a Type II supernova at intermediate times, up to a few times 103 s. The experiment is modeled using the hydrodynamics codes HYADES and CALE and the supernova code PROMETHEUS. Results of the experiments and simulations are presented.