Metallic Edge Research Articles

A high extinction ratio plasmonic SU-8 waveguide polarizer

In this paper, a novel method has been proposed for increasing the extinction ratio of a plasmonic waveguide polarizer. Aluminum was coated in a 20-micron multi-strip pattern on the top of a SU-8 waveguide to excite the surface plasmons. The simulation and experimental results showed that the extinction ratio of the multi-strip polarizer was more than those of single-strip polarizers with the same total aluminum-coated length due to the coupling loss between the Al-coated and uncoated regions and also the scattering at the edge of metal. This polarizer was characterized over a wide range of wavelengths and showed the high extinction ratios of 46 dB and 26.8 dB at the wavelengths of 1550 nm and 980 nm, respectively.

Solar glint from uncoated starshade optical edges

The perimeter of a sunflower-like starshade has hundreds of meters of sharp edges that are directly exposed to sunlight. The sunlight diffracts and reflects from the edge resulting in a dual-lobed glint pattern that can be brighter than an exoplanet. We present estimates of the glint brightness distribution for the Starshade Rendezvous Mission and the HabEx Starshade Mission concepts based on measurements of flight-like, environmentally tested, uncoated metallic edges using custom-built scatterometers. A companion paper addresses the performance for edges coated with a thin anti-reflection coating.

Implementation of finite element model in compound propeller blades for using in aircraft

In this paper, the work essentially manages the displaying and investigation of the propeller sharp edge of aircraft for its quality. A propeller cutting edge is intricate 3D model math. This requires very good quality demonstrating CAD programming is utilized for creating the edge model in CATIA V5 R20. This paper comprises of brief insights regarding Fiber Reinforced Plastic materials and the upsides of utilizing composite propeller over the ordinary metallic propeller sharp edge. This paper centers on the metal and composite quality investigation of the propeller cutting edge completed by utilizing the limited component examination. By utilizing ANSYS programming static, modular were done for isotropic material. In this work two unique kinds of propeller for example Aluminum, Composite, were examined utilizing FEA procedures.

The effects of buccal administration of azaperone on the sedation level and biochemical variables of weaned piglets

The aim of the study was to compare the efficacy of buccal and parenteral administration of azaperone in order to achieve pig sedation. The type of study was prospective randomized and double blinded. A total of 40 weaned piglets were divided into 4 groups (10 each) and monitored. Group A was injected intramuscularly (i.m.) with azaperone (Stresnil®, 40 mg/ml inj., Elanco Animal Health) at a dose of 2 mg/kg body weight (b.w.). Group B (control) was given 1 ml of saline buccally. Group C received a dose of 2 mg/kg b.w. of azaperone buccally. Group D was given azaperone buccally at a dose of 4 mg/kg b.w. The response to defined stimulus (a blunt blow of a metal rod into the metal edge of the pen), degree of salivation, movement level, blood plasma azaperone concentration, and the haematological and biochemical variables were included in the study. We found that the buccal administration of azaperone is effective, however, a dose of 4 mg/kg b.w. is required to induce a sedation level comparable to the standard 2 mg/kg b.w. i.m. administration.

Wideband RCS reduction of thin metallic edges mediated by spoof surface plasmon polaritons

The back-scattering from front edge diffraction contributes significantly to mono-static radar cross section under TE-polarization when the specular reflection of an object is eliminated by elaborate shaping. With the aim to suppress the back-scattering of thin metallic edge, we propose to achieve wideband radar cross section (RCS) reduction by integrating an absorbing structure (AS) in front of the edge. The unit cell of AS is composed of a longitudinal array of metallic strips with linearly decreasing lengths. Under TE-polarized illumination, spoof surface plasmon polariton (SSPP) can be excited with high efficiency. Due to the deep-subwavelength property of SSPP, electromagnetic waves are highly confined around the AS, leading to strong local field enhancement and hence to wideband absorption. In this way, back-scattering of the edge is suppressed and the mono-static RCS can be reduced significantly over wide band. To verify this method, we designed, fabricated and measured a prototype. The results of both simulation and measurement indicate that our proposal can significantly suppress edge scattering, whose RCS reduction more than 10 dB achieves at range of 8.8–17.8 GHz under TE polarization. This work provides a new alternative of suppressing edge diffraction and may find applications in electromagnetic compatibility, radar stealth, etc.

Horns decorated with openwork metal edges

Horns decorated with openwork metal edges

2D analogue of band-bending in metal–semiconductor junctions: interior to edge-states of single-layered transition metal dichalcogenides

Band-edges and the bandgap of liquid-exfoliated tungsten disulfide and tungsten diselenide (WS2 and WSe2) were measured via scanning tunneling spectroscopy (STS). We have observed that the edges of the dichalcogenides were metallic and the interiors were semiconducting in nature. An explicit band-bending between the semiconducting interior and the metallic edge could be observed in both the 2D transition metal dichalcogenides (TMDs). The Fermi energy pinning in the 2D materials is like conventional band-bending in metal–semiconductor junctions at the 3D scale. We have further have inferred that in order to determine the bandgap of a 2D TMD, localized STS measurements should be carried out away from the edge; in this work, we have determined that the required distance should be more than the width of the depletion region, which we measured as 3.5 and 2.0 nm for WS2 and WSe2, respectively.

Design of a β-Ga2O3 Schottky Barrier Diode With p-Type III-Nitride Guard Ring for Enhanced Breakdown

This work presents the electrostatic analysis of a novel Ga$_2$O$_3$ vertical Schottky diode with three different guard ring configurations to reduce the peak electric field at the metal edges. Highly doped p-type GaN, p-type nonpolar AlGaN and polarization doped graded p-AlGaN are simulated and analyzed as the guard ring material, which forms a heterojunction with the Ga$_2$O$_3$ drift layer. Guard ring with non-polar graded p-AlGaN with a bandgap larger than Ga$_2$O$_3$ is found to show the best performance in terms of screening the electric field at the metal edges. The proposed guard ring configuration is also compared with a reported Ga$_2$O$_3$ Schottky diode with no guard ring and a structure with a high resistive Nitrogen-doped guard ring. The optimized design is predicted to have breakdown voltage as high as 5.3 kV and a specific on-resistance of 3.55 m$\Omega$-cm$^2$ which leads to an excellent power figure of merit of 7.91 GW/cm$^2$.

Molecular beam epitaxy growth and strain-induced bandgap of monolayer 1T′-WTe2 on SrTiO3(001)

A monolayer 1T′-WTe2 film is grown on SrTiO3(001) with in-plane tensile strain. A height of ∼0.7 nm, obvious charge transfer, and incommensurate charge fluctuations in 1T′-WTe2 suggest strong coupling to the STO substrate. Scanning tunneling spectroscopy on the surface reveals that a large energy gap opens at the Fermi level with nearly zero conductance. The opened energy gap decreases with the increase in the WTe2 island size. The lack of the metallic edge state on monolayer 1T′-WTe2/SrTiO3(001) indicates the absence of the quantum spin Hall (QSH) state. Our study here demonstrates that the energy gap of monolayer 1T′-WTe2 can be tuned by lattice strain and illustrates the importance of interface coupling to realize the metallic edge state and QSH in monolayer 1T′-WTe2.

A highly responsive healing agent for the autonomous repair of anti-corrosion coatings on wet surfaces. In operando assessment of the self-healing process

A methodology to enrich epoxy coatings of an effective self-healing feature on wet surfaces was developed as a further step on for practical corrosion protection issues. To this aim, a polyetheramine was chemically engineered by grafting catechol units and then successfully encapsulated in microcapsules (MCs) to be finally embedded into an epoxy resin deposited on steel panels. Fourier transform infrared spectroscopy (FTIR), thin-layer chromatography, and 1D and 2D nuclear magnetic resonance spectroscopy confirmed the successful polyetheramine modification by dopamine units. Different dosages of catechol-modified polyetheramine were encapsulated within poly(styrene-co-acrylonitrile) shell via electrospray method to study the influence of dopamine grafting on the healing performance. Scanning electron microscopy (SEM) analysis revealed the formation of the spherical MCs, while FTIR and TGA analyses confirmed the successful encapsulation. The highly responsive self-healing coatings were then prepared by embedding amine- and isocyanate-containing MCs (1:1 weight ratio; 3 wt% overall) as a dual-capsule system exploiting the polyurea formation as a fast healing reaction. In operando electrochemical impedance spectroscopy (EIS) tests were employed to study the underwater self-healing performance. According to the EIS results, monotonically increasing variation with time of the charge transfer resistance was correlated with a fast and effective underwater self-healing performance for the sample using 40 wt% of a catechol-modified healing agent. Such results, combined with others including SEM investigation on the underwater healed samples, point to an improved adhesion of the growing dopamine-bearing polymer to both underlying metal and epoxy edges of the scratch.Graphic abstract

On the topological immunity of corner states in two-dimensional crystalline insulators

A higher-order topological insulator (HOTI) in two dimensions is an insulator without metallic edge states but with robust zero-dimensional topological boundary modes localized at its corners. Yet, these corner modes do not carry a clear signature of their topology as they lack the anomalous nature of helical or chiral boundary states. Here, we demonstrate using immunity tests that the corner modes found in the breathing kagome lattice represent a prime example of a mistaken identity. Contrary to previous theoretical and experimental claims, we show that these corner modes are inherently fragile: the kagome lattice does not realize a higher-order topological insulator. We support this finding by introducing a criterion based on a corner charge-mode correspondence for the presence of topological midgap corner modes in n-fold rotational symmetric chiral insulators that explicitly precludes the existence of a HOTI protected by a threefold rotational symmetry.

Analytical Modeling of Participation Reduction in Superconducting Coplanar Resonator and Qubit Designs Through Substrate Trenching

A strategy aimed at decreasing dielectric loss in coplanar waveguides (CPW) and qubits involves the creation of trenches in the underlying substrate within the gaps of the overlying metallization. Participation of contamination layers residing on surfaces and interfaces in these designs can be reduced due to the change in the effective dielectric properties between the groundplane and conductor metallization. Although finite element method approaches have been previously applied to quantify this decrease, an analytical method is presented that can uniquely address geometries possessing small to intermediate substrate trench depths. Conformal mapping techniques produce transformed CPW and qubit geometries without substrate trenching but a non-uniform contamination layer thickness. By parametrizing this variation, one can calculate surface participation through the use of a two-dimensional, analytical approximation that properly captures singularities in the electric field intensity near the metallization corners and edges. Examples demonstrate two regimes with respect to substrate trench depth that capture an initial increase in substrate-to-air surface participation due to the trench sidewalls and an overall decrease in surface participation due to the reduction in the effective dielectric constant, and are compared to experimental measurements to extract loss tangents on this surface.

P‐115: Research on Waviness Improvement for Foldable Display and Relevant Ultra‐Thin Metal Plate Modeling Process

Since the creep was an inherent characteristic of polymer materials, the all‐polymer Organic Light‐Emitting Diode (OLED) display module exhibited a permanent deformation that could not be recovered by itself. We hoped to use ultra‐thin metal plate as a support to reduce the irreversible module waviness. However, there would be a risk of crack failure causing by the stress concentration at the metal edges of the folding area. After researching among three conventional metal cutting methods (punch, etch and laser‐cut), we compared the morphologies of the cutting edges and found that the punch process was optimal for ultra‐thin metal plate cutting.

Temperature regulation for thermoplastic micro-forming of bulk metallic glass: Robust control design using buck converter

Abstract This article presents the design, identification, simulation, and control of a buck converter implemented for bulk metallic glass thermoplastic micro-forming. In manufacturing of multi-faceted bulk metallic glass knife edge, the temperature of the micro-forming sample is critical to the thermoplastic deformation, which determines the quality of the blade edge shape. We propose a nested inner-current outer-temperature control system for high-fidelity temperature regulation. The inner-current control loop is implemented on a modified buck converter, which allows high-power rectified AC input and outputs current that can be regulated with a precision of 2 % over a bandwidth of 5 Hz. We use switch-averaged electrical model together with feedback linearization to address complex nonlinear dynamics that describe a buck converter, and to enable it using linear control design methods. The outer-temperature control design ensures temperature regulation of a heater by prescribing real-time reference power that the current-control loop should provide. The challenge of nonlinear relationship between the required reference power and the regulated current is addressed by exploiting the high-bandwidth of the inner-current loop. The control objectives of regulation performance and robustness to modelling uncertainties are posed and solved in an optimal control (H∞) framework. Experimental results demonstrate that our control design achieved the required temperature regulation at 673 K within 0.03 K. An improvement of over 5000 % is demonstrated when compared with previously implemented control designs. Moreover, the buck converter-based system enables regulation accuracies that were not possible with other popular existing methods such as TRIAC and traditional relay switches.

Electric field emission characteristics of a triode-structured metallic edge emitter from geometric conditions

Spindt-tip type cold electron emission has potential in various applications; however, it has a limited current capacity that prevents the emitters from being used for higher current sources, and the fabrication of the emitters is not easy. In this study, we investigate the electric field emission characteristics of a triode-structured metallic edge emitter from geometric conditions. We perform a systematic simulation based on Fowler-Nordheim theory to analyze the feasibility of using the proposed emitter. The dependences of the emission current, electron transmittance, and region of the triode mode on specific geometrical parameters, including the anode-gate vertical distance, gate-cathode vertical distance, gate-cathode horizontal distance, anode voltage, and gate voltage, are analyzed. The results show that the electric field for a narrow gate-cathode vertical distance is superior to the electric field of the gate electrode for a narrow gate-cathode horizontal distance, while the electric field for a wide gate-cathode vertical gap is more dominant than the electric field of the anode electrode for a wide gate-cathode horizontal gap. Moreover, the electron transmittance gradually increases with a low gate voltage, wide anode-gate vertical distance, and high anode voltage, and the region of the triode mode also increases with a high gate voltage, wide anode-gate vertical distance, and low anode voltage. Consequently, our results appear to be effective for an optimization in an experiment and are expected to improve present electric field emission techniques.

Features and Advantages of Applying Anisotropic Magnetoresistive Field Sensors to Testing the Full Volume of Small- and Medium-Diameter Pipes

The work is devoted to a comparative study of magnetoresistive and Hall magnetic field sensors used as primary transducers in multichannel magnetic flaw-detection systems. The principle of operation and application features of anisotropic magnetoresistive (AMR) field sensors are considered. Comparative tests of AMR and Hall sensors were carried out. The main objective of these studies was to select optimum measuring transducers necessary to achieve the required metrological and operational characteristics. We have developed and investigated a multichannel magnetoresistive system for measuring fields due to defects and processing the results of nondestructive testing using a magnetic (MFL—magnetic flux leakage) method. Based on this method, a new small-sized flaw-detection facility has been created and introduced in the industry for automated continuous in-process magnetic inspection and identification of defects in electric-welded small- and medium-diameter pipes over the entire wall thickness, i.e., over the entire product volume. It is shown that the use of computer technologies and high-resolution thin-film matrix transducers made using advanced technology for manufacturing AMR sensors significantly increases the capabilities of the flaw detector and makes it possible to detect not only defects such as violations of metal continuity and edge displacements, but also defects caused by violation of welding conditions such as cracks, fistulas, arc freezings, and sticking edges in the weld area. The system based on new-generation single-chip thin-film matrix transducers is highly sensitive and allows detecting both surface and bulk defects in a noncontact manner with a large gap and at a high speed.

A Finite Element Analysis Model for Partial Discharges in Silicone Gel under a High Slew Rate, High-Frequency Square Wave Voltage in Low-Pressure Conditions

Wide bandgap (WBG) devices made from materials such as SiC, GaN, Ga2O3 and diamond, which can tolerate higher voltages and currents compared to silicon-based devices, are the most promising approach for reducing the size and weight of power management and conversion systems. Silicone gel, which is the existing commercial option for encapsulation of power modules, is susceptible to partial discharges (PDs). PDs often occur in air-filled cavities located in high electric field regions around the sharp edges of metallization in the gel. This study focuses on the modeling of PD phenomenon in an air filled-cavity in silicone gel for the combination of (1) a fast, high-frequency square wave voltage and (2) low-pressure conditions. The low-pressure condition is common in the aviation industry where pressure can go as low as 4 psi. To integrate the pressure impact into PD model, in the first place, the model parameters are adjusted with the experimental results reported in the literature and in the second place, the dependencies of various PD characteristics such as dielectric constant and inception electric field on pressure are examined. Finally, the reflections of these changes in PD intensity, duration and inception time are investigated. The results imply that the low pressure at high altitudes can considerably affect the PD inception and extinction criterion, also the transient state conditions during PD events. These changes result in the prolongation of PD events and more intense ones. As the PD model is strongly dependent upon the accurate estimation electric field estimation of the system, a finite-element analysis (FEA) model developed in COMSOL Multiphysics linked with MATLAB is employed that numerically calculates the electric field distribution.

Measurement of the x-ray effective focal spot size with edge response analysis using digital detectors.

Purpose: For the focal spot measurement of x-ray tubes, we propose a practical method in which only a metal edge and a digital detector are used, together with a process of removing detector blur inherently associated. Approach: The evaluation was made through the optical transfer function (OTF) measurements using the edge response of a 1-mm-thick tungsten plate. First, we made the acquisition of a geometrically magnified edge response, which consists of focal spot penumbra and detector blur, followed by the acquisition of nonmagnified edge response, which includes only detector blur. Then the detector blur was removed by taking the ratio of the two OTFs. Finally, the focal spot profile was obtained by the inverse Fourier transform of this ratio. Results: Resultant full widths at the half-maximum of a small focus profile were for the proposed method and for the conventional slit method with film, indicating excellent agreement between both methods. Comparing between results obtained using two flat panel detectors with different pixel pitches (0.143 and 0.175mm) confirmed no differences with these variations. Conclusion: Through the whole study, the accuracy and the practicality of the proposed method were demonstrated, indicating a possibility of the method to be widely used to evaluate the effective focal spot size and profile of x-ray systems.

Extraordinary magnetoresistance in encapsulated monolayer graphene devices

We report a proof-of-concept study of extraordinary magnetoresistance (EMR) in devices of monolayer graphene encapsulated in hexagonal boron nitride having metallic edge contacts and a central metal shunt. Extremely large EMR values, MR=(R(B)−R0)/R0∼105, are achieved in part because R0 approaches or crosses zero as a function of the gate voltage, exceeding that achieved in high mobility bulk semiconductor devices. We highlight the sensitivity, dR/dB, which in two-terminal measurements is the highest yet reported for EMR devices and in particular exceeds previous results in graphene-based devices by a factor of 20. An asymmetry in the zero-field transport is traced to the presence of pn-junctions at the graphene-metal shunt interface.

Possible Luttinger liquid behavior of edge transport in monolayer transition metal dichalcogenide crystals

In atomically-thin two-dimensional (2D) semiconductors, the nonuniformity in current flow due to its edge states may alter and even dictate the charge transport properties of the entire device. However, the influence of the edge states on electrical transport in 2D materials has not been sufficiently explored to date. Here, we systematically quantify the edge state contribution to electrical transport in monolayer MoS2/WSe2 field-effect transistors, revealing that the charge transport at low temperature is dominated by the edge conduction with the nonlinear behavior. The metallic edge states are revealed by scanning probe microscopy, scanning Kelvin probe force microscopy and first-principle calculations. Further analyses demonstrate that the edge-state dominated nonlinear transport shows a universal power-law scaling relationship with both temperature and bias voltage, which can be well explained by the 1D Luttinger liquid theory. These findings demonstrate the Luttinger liquid behavior in 2D materials and offer important insights into designing 2D electronics.