Polarization insensitive symmetrical structured double negative (DNG) metamaterial absorber for Ku-band sensing applications

Metamaterial absorber (MMA) is now attracting significant interest due to its attractive applications, such as thermal detection, sound absorption, detection for explosive, military radar, wavelength detector, underwater sound absorption, and various sensor applications that are the vital part of the internet of things. This article proposes a modified square split ring resonator MMA for Ku-band sensing application, where the metamaterial structure is designed on FR-4 substrate material with a dielectric constant of 4.3 and loss tangent of 0.025. Perfect absorption is realized at 14.62 GHz and 16.30 GHz frequency bands, where peak absorption is about 99.99% for both frequency bands. The proposed structure shows 70% of the average absorption bandwidth of 420 MHz (14.42–14.84 GHz) and 480 MHz (16.06–16.54 GHz). The metamaterial property of the proposed structure is investigated for transverse electromagnetic mode (TEM) and achieved negative permittivity, permeability, and refractive index property for each absorption frequency band at 0°, 45°, and 90° polarization angles. Interference theory is also investigated to verify the absorption properties. Moreover, the permittivity sensor application is investigated to verify the sensor performance of the proposed structure. Finally, a comparison with recent works is performed, which shows that the proposed MMA can be a good candidate for Ku-band perfect absorber and sensing applications.

New coaxial low-pass filters with ultra-wide and spurious free stopband

Modern space communication systems often need high-power low-frequency (UHF, L-, S-, and C-band) low-pass filters (LPFs) with wide stopbands extending to Ka-band and beyond. Current design approaches frequently fail to meet these requirements completely. This paper proposes a new coaxial LPF concept and design methodology. The LPF consists of an array of cavity elements, which operate with transverse electromagnetic mode (TEM) and transverse magnetic (TM)-coupled resonances, and thus achieve a frequency response with a reflection zero at DC and transmission zeroes at targeted stopband locations. The design method is based on positioning the cavities in a quasi-periodic order, which efficiently spreads the transmission zeroes over the stopband, while keeping the characteristic impedance matched to the input/output interfaces over the passband. This design concept yields an ultra-wide, continuous and modal spurious-free stopband, while maintaining a low insertion loss, high peak power capacity, and low sensitivity to production tolerances.

Graphene-based dual-band near-perfect absorption in Rabi splitting between topological edge and Fabry-Perot cavity modes

We propose a graphene embedded one-dimensional (1D) topological photonic crystal heterostructure, where the strong coupling occurs between the topological edge mode (TEM) and the Fabry-Perot cavity mode (CM). It is shown that the strong coupling leads to the hybridization between TEM and CM, with a Rabi splitting. Based on finite element method (FEM), a dual-band near-perfect absorption, which can be actively tuned by the Fermi energy of the graphene and incident angle, is found in the Rabi splitting region. Theoretically, the TEM-CM coupling can be analyzed by the classic oscillator model. In particular, when the Fermi energy of graphene slightly increases around 0.4 eV, the dual-band near-perfect absorption shows a rapid decrease from one to zero, which offers a possible way for absorption optical switches.

Turbulent impurity transport simulations in Wendelstein 7-X plasmas

A study of turbulent impurity transport by means of quasilinear and nonlinear gyrokinetic simulations is presented for Wendelstein 7-X (W7-X). The calculations have been carried out with the recently developed gyrokinetic code stella. Different impurity species are considered in the presence of various types of background instabilities: ion temperature gradient (ITG), trapped electron mode (TEM) and electron temperature gradient (ETG) modes for the quasilinear part of the work; ITG and TEM for the nonlinear results. While the quasilinear approach allows one to draw qualitative conclusions about the sign or relative importance of the various contributions to the flux, the nonlinear simulations quantitatively determine the size of the turbulent flux and check the extent to which the quasilinear conclusions hold. Although the bulk of the nonlinear simulations are performed at trace impurity concentration, nonlinear simulations are also carried out at realistic effective charge values, in order to know to what degree the conclusions based on the simulations performed for trace impurities can be extrapolated to realistic impurity concentrations. The presented results conclude that the turbulent radial impurity transport in W7-X is mainly dominated by ordinary diffusion, which is close to that measured during the recent W7-X experimental campaigns. It is also confirmed that thermodiffusion adds a weak inward flux contribution and that, in the absence of impurity temperature and density gradients, ITG- and TEM-driven turbulence push the impurities inwards and outwards, respectively.

Radiation forces study of a Laguerre Gaussian beam type TEM∗01 on a dielectric sphere in the Rayleigh scattering regime

From the invention of the Optical Tweezer (OT) in 1986, these devices have been considered as high-level tools for research in the areas such as biology and microbiology. A theoretical study obtaining equations for gradient and scattering forces that exert an OT when the illumination beam is a doughnut-shaped mode TEM∗01 linearly polarized is realized. This work focuses on the behavior of radiation forces on a dielectric sphere in the Rayleigh regime. In order to facilitate the phenomenological analysis of the behavior of the radiation forces a graphical user interface is created.

Analysis of Periodic Structures Made of Pins Inside a Parallel Plate Waveguide

In this work, we have analyzed different versions of periodic structures made with metallic pins located inside a parallel plate waveguide (PPWG), varying the symmetry and disposition of the pins. The analysis focuses on two main parameters related to wave propagation. On one hand, we have studied how the different proposed structures can create a stopband so that the parallel plate modes can be used in gap waveguide technology or filtering structures. On the other hand, we have analyzed the dispersion and equivalent refractive index of the first propagating transverse electromagnetic mode (TEM). The results show how the use of complex structures made with pins in the top and bottom plates of a PPWG have no advantages in terms of the achieved stopband size. However, for the case of the propagating mode, it is possible to find less dispersive modes and a higher range of equivalent refractive indices when using double-pin structures compared to a reference case with single pins.

Stellarator microinstabilities and turbulence at low magnetic shear

Gyrokinetic simulations of drift waves in low-magnetic-shear stellarators reveal that simulation domains comprised of multiple turns can be required to properly resolve critical mode structures important in saturation dynamics. Marginally stable eigenmodes important in saturation of ion temperature gradient modes and trapped electron modes in the Helically Symmetric Experiment (HSX) stellarator are observed to have two scales, with the envelope scale determined by the properties of the local magnetic shear and an inner scale determined by the interplay between the local shear and magnetic field-line curvature. Properly resolving these modes removes spurious growth rates that arise for extended modes in zero-magnetic-shear approximations, enabling use of a zero-magnetic-shear technique with smaller simulation domains and attendant cost savings. Analysis of subdominant modes in trapped electron mode (TEM)-driven turbulence reveals that the extended marginally stable modes play an important role in the nonlinear dynamics, and suggests that the properties induced by low magnetic shear may be exploited to provide another route for turbulence saturation.

LAS COMPETENCIAS BÁSICAS SE PUEDEN DESARROLLAR A TRAVÉS DE LA MODALIDAD DUAL EN UN LICEO TÉCNICO PROFESIONAL DE ALTA VULNERABILIDAD

RESUMEN En el contexto de la Educación Técnica Profesional, la Modalidad Dual ha constituido una apuesta del Ministerio de Educación de Chile para mejorar la formación Técnica Profesional en la Enseñanza Media. El cambio ha involucrado una innovación curricular en torno al desarrollo de competencias básicas donde, además del docente y el aula tradicional, concurren otros agentes y otros escenarios que comparten la labor de enseñar. En este contexto la investigación consignada, de acuerdo a sus objetivos y formulación metodológica, describe las características de la formación Técnico Profesional Dual de la especialidad de Administración del Complejo Educacional Monseñor Guillermo Carlos Hartl de la comuna de Pitrufquén, en Chile. Se pretende indagar la efectividad del currículo integrado a través de la evaluación de logro de las competencias básicas de alumnos/as que cursan el 4° Año Medio de dicha especialidad (con modalidad Dual), en directa relación al perfil de egreso y profesional exigido y en contraste, con la de alumnos de la especialidad de “Electricidad”, sin la Modalidad Dual. PALABRAS CLAVE: Diseño curricular, currículum, competencias básicas, didáctica, metodología. ABSTRACT In the context of Vocational Technical Education, Dual Mode has been a commitment of the Ministry of Education of Chile to improve training Professional Technical High School. The change has involved a curricular innovation around the development of core competencies where besides the teacher and the traditional classroom, attend other agents and other scenarios that share the work of teaching. In this context the research contained, according to its objectives and methodological formulation describes the characteristics of the Dual Vocational Technical Training specialty Administration Educational Complex Monsignor William Carlos Hartl Pitrufquén commune in Chile. It aims to investigate the effectiveness of integrated curriculum through the evaluation of achievement of basic skills alumni / ae who attend the 4th Year Half of that specialty (Dual mode) directly related graduate profile and professional required to and in contrast with that of students in the specialty of "Electricity" without the Dual Mode. KEYWORDS: Curriculum design, curriculum, basic skills, teaching methodology. RESUMO No contexto da Educação Profissional Técnica, o Dual Mode tem sido um compromisso do Ministério da Educação do Chile para melhorar a formação profissional. A mudança envolveu uma inovação curricular em torno do desenvolvimento de competências centrais, onde, além do ensino e da sala de aula tradicional, frequentam outros agentes e outros cenários que compartilham o trabalho de ensino. Neste contexto, a pesquisa continha, de acordo com os seus objetivos e formulação metodológica, a descrição de características da especialidade formação técnica profissional de Gestão do Complexo Educacional Dom Carlos Guillermo Hartl da cidade de Pitrufquén, Chile. O estudo tem como objetivo investigar a eficácia do currículo integrado através da avaliação da consecução das competências básicas dos alunos, diretamente relacionadas e o profissional necessário em contraste, os alunos com especialidade em "Electricidade" sem o modo dual. PALAVRAS-CHAVE: Desenho curricular, currículo, habilidades básicas, didática, metodologia.

Modeling the Effect of Beam Shaping at Selective Laser Melting

The influence of the laser-beam radial distribution of the energy flux density is theoretically studied for the Gaussian distribution (mode TEM00), and doughnut distribution of TEM01* mode for the values of the Peclet number from 0 to 3. The model of linear thermal conduction in the target indicates that profile TEM00 is the best for thermo-activated treatment processes that can be accomplished in a wide temperature range and profile TEM01* can be advantageous for a narrow range of the permissible processing temperature. If the phase transitions of melting/solidification and evaporation are included into the model, the estimate of the width of the laser-treated band is reduced but the tendencies predicted by the linear model are not changed.