Periodic Structures
Mostrando 1-12 de 96 artigos, teses e dissertações.
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1. Project and Analysis of Quasi-Periodic PBG for Microstrip Antenna
Abstract In this work the influence of quasi-periodic distributions of air holes with 6, 12 and 6-fold modified symmetries, applied to the substrate of a rectangular microstrip patch antenna are analyzed. To validate the study, parameters such as S11 parameter, bandwidth, total gain, radiation pattern and electric field were investigated through computationa
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2020-06
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2. A Novel Fractal Multi-band Frequency Selective Surface
Abstract In this paper, a new multiband fractal frequency selective surface (MF-FSS) is proposed. The work presents a new fractal design methodology for FSSs with Swastika fractal patch elements. The proposed MF-FSS includes periodic arrays of metallic patches, printed on a single layer substrate. The structure parametric analysis is carried out in terms of
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 19/06/2019
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3. LA PERIODICIDAD DE LOS ELEMENTOS Y EL DESEMPEÑO DE LOS MATERIALES: UN COMPLEMENTO PARA LA COMPRENSIÓN DE LA TABLA PERIÓDICA
The United Nations (UN) has proclaimed 2019 as the International Year of the Periodic Table of Chemical Elements (IYPT 2019). For that reason, it is considered pertinent to highlight the importance of the periodic system in the scientific and technological development of the chemistry; therefore, a discussion of some applications of the periodicity of the el
Quím. Nova. Publicado em: 2019-02
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4. A direct technique for the homogenization of periodic beam-like structures by transfer matrix eigen-analysis
Abstract To homogenize lattice beam-like structures, a direct approach based on the matrix eigen- and principal vectors of the state transfer matrix is proposed and discussed. The Timoshenko couple-stress beam is the equivalent continuum medium adopted in the homogenization process. The girders unit cell transmits two kinds of bending moments: the first is g
Lat. Am. j. solids struct.. Publicado em: 10/07/2018
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5. Mean scatterer space estimation from ultrasound signals combining singular spectral analysis and entropy
AbstractIntroduction: Ultrasound (US) is a nonionizing radiation capable of real time imaging at low cost. Its most attractive application is quantitative tissue characterization with the objective of differentiating normal tissues from diseased tissues. In this study, an automated method using singular spectrum analysis (SSA) to estimate the mean scatterer
Res. Biomed. Eng.. Publicado em: 2018-06
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6. HIGH PRESSURE BEHAVIOR OF CRYSTALLINE DIHYDROXYLAMMONIUM 5,5'-BISTETRAZOLE-1,1'-DIOLATE: FIRST-PRINCIPLES STUDY
Density functional theory (DFT) periodic calculations were performed to study the geometrical and electronic structures of energetic compound dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) under the pressure ranging from 0 to 400 GPa. The optimized crystal structure by the local density approximation (LDA) with CA-PZ functional matches well with
Quím. Nova. Publicado em: 2017-10
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7. Computational Simulations of Morphological Transformations by Surface Structures: The Case of Rutile TiO2 phase
Computational simulations based on periodic density functional theory have been carried out to investigate the control of crystal morphology by accurate values of surface energies by Wulff theorem. This method can be used as a very useful tool for the design and knowledge of synthesis of new materials. In a special case, rutile TiO2 phase, exhibits great var
Mat. Res.. Publicado em: 10/04/2017
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8. Dynamic Properties of Coupled Tube-Array Structures with the Axial Loads
Abstract The tube-array structures coupled both with the fluid and the axial load is focused. In a heat exchanger, the tubes are frequently affected by cold and hot fluid shock waves. Thus, tubes are often found to be vibrated and even to be worn out. This vibration may not only alter the performance of the tubes but also introduce the damage in the heat exc
Lat. Am. j. solids struct.. Publicado em: 2016-12
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9. Comparative study of periodicity estimation methods using ultrasonic signals
Abstract Introduction Various signal-processing techniques have been proposed to extract quantitative information about internal structures of tissues from the original radio frequency (RF) signals instead of an ultrasound image. The quantifiable parameter called the mean scatterer spacing (MSS) can be useful to detect changes in the quasi-periodic microstr
Res. Biomed. Eng.. Publicado em: 09/09/2016
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10. Chromatic Dispersion of an Optical Fiber Based on Photonic Quasicrystals with Twelve-Fold Symmetry and its Application as Directional Coupling
Abstract Optical fibers composed by photonic quasicrystals it is based on aperiodic structures characterized by at least two different symmetrical patterns from the base matrix. In this work, an optical fiber composed by quasi-periodic and symmetric matrix was analyzed using the finite element method in conjunction with cylindrical perfectly matched layers.
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2015-12
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11. Phenotype and cell proliferation activity of duct-like structures in human sublingual glands: a histological and immunohistochemical study
There are several age-related microscopic changes in the salivary glands, including the increase in the number of duct-like structures (DLS). However, the true origin and the phenotype of the DLS are not known. Objective To evaluate the phenotype and the cell proliferation index of the DLS of human sublingual glands. Material and Methods Sixty sublingual gla
J. Appl. Oral Sci.. Publicado em: 2015-06
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12. Dinâmica temporal de pausas e hesitações na fala semi-espontânea / Time dynamics of pauses and hesitations in semi-spontaneous speech
Premissa: esta pesquisa partiu da premissa de que pausas demarcativas estão relacionadas ao planejamento conceitual e hesitações, à formulação linguística. O planejamento conceitual refere-se a um esquema abstrato do texto falado, composto pelas informações que o falante julga relevantes de acordo com sua meta comunicativa. A formulação linguísti
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 23/02/2012