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    Tytuł:
    Analysis of the possibility of shaping the sound diffusion coefficient of diffusers based on acoustic metamaterials
    Autorzy:
    Rubacha, Jarosław
    Powiązania:
    https://bibliotekanauki.pl/articles/2202416.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    metamaterial
    sound diffusion
    diffusion coefficient
    metamateriał
    dyfuzja dźwięku
    współczynnik dyfuzji
    Opis:
    The article presents the analysis of the possibilities of using acoustic metamaterial to build sound diffusers. The diffusers composed of slots loaded with a curved quarter-wave resonator were investigated. Such solutions induce dispersion and the slow sound effect to increase the effective depth of the quarter-wave resonator. The sound diffusion coefficient was calculated with the use of numerical models of diffusers. Next, obtained results were compared with the Schroeder diffuser. In conclusion, it was shown, that acoustic metamaterials affect the frequency band of the diffuser and the effectiveness of the obtained sound diffusers depend on relative width of slits.
    Źródło:
    Vibrations in Physical Systems; 2022, 33, 2; art. no. 2022210
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sound diffuser made of acoustic metamaterial: numerical and experimental investigation
    Autorzy:
    Rubacha, Jarosław
    Powiązania:
    https://bibliotekanauki.pl/articles/2146653.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    metamaterial
    sound diffusion
    diffusion coefficient
    metamateriał
    dyfuzja dźwięku
    współczynnik dyfuzji
    Opis:
    The use of metamaterials in room acoustics is becoming more and more popular. Their advantage is the possibility of adjusting the parameters of the systems in the desired frequency range and the reduction of dimensions compared to the existing solutions. This paper discusses the numerical design and experimental verification of sound diffuser based on the acoustic metamaterials: a slit with added quart-wave length resonator. The transfer matrix method is used to make a numerical model of the metamaterial cell, which was used to build a model of a diffuser composed of N = 7 cells. Then, the dimensions of the diffuser were optimized to obtain the sound diffusion in a wide frequency range. The sound dispersion coefficient was also calculated using the FEM method. The numerical results were compared with the measurements and it was shown that it is possible to make a broadband sound diffuser with the use of metamaterials.
    Źródło:
    Vibrations in Physical Systems; 2021, 32, 2; art. no. 2021207
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Computation and experimental comparison of the deformation behavior of pantographic structures with different micro-geometry under shear and torsion
    Autorzy:
    Yang, Hua
    Müller, Wolfgang H.
    Powiązania:
    https://bibliotekanauki.pl/articles/281645.pdf
    Data publikacji:
    2019
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    nonlinear elasticity
    metamaterial
    numerical simulation
    Opis:
    Additive manufacturing methods, commonly known as 3D printing, allow more sophisticated designs to be created. Willingly designed substructures incorporated into the solid open up new possibilities for uncommon macroscopic deformation behavior. Such a man-made structure is also referred to as a metamaterial. A detailed simulation of a polymer-based metamaterial is challenging but accurately possible by means of the theory of elasticity. In this study, we present experimental investigations of a metamaterial composed of pantographic substructures of different internal geometry. The pantographic structures show an unexpected type of deformation, which can be modeled via elasticity with the aid of direct numerical simulation by using the Finite Element (FE) method. In other words, a detailed mesh is generated involving the substructure. The metamaterial is additively manufactured out of a common polymer showing nonlinear elastic deformation and, therefore, hyperelastic material models are used. Specifically, analytical solutions of a circular cylinder are examined and compared in the case of extension and torsion in order to comprehend the effects of the coefficients inherent to the energy function of the hyperelastic model. Finally, FE computations of pantographic structures are performed and compared with the experimental measurements.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2019, 57, 2; 421-434
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Polarization dependent high refractive index metamaterial with metallic dielectric grating structure in infrared band
    Autorzy:
    Li, Jianmin
    Chen, Peng
    Fang, Bo
    Cai, Jinhui
    Zhang, Le
    Wu, Yinglai
    Jing, Xufeng
    Powiązania:
    https://bibliotekanauki.pl/articles/2172825.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    metamaterial
    high refractive index
    infrared band
    Opis:
    According to the theory of high refractive index of metamaterials, a composite structure of metal dielectric grating was designed to achieve high refractive index in infrared band. Based on the S-parameter inversion algorithm, we extracted the effective permittivity, the effective permeability, and the effective refractive index of the designed metamaterial. By changing the geometric parameters of the composite grating metamaterial structure, the effective refractive index of the designed metamaterial reaches more than 8.0 at the infrared resonance frequency. This is a high refractive index that many natural materials cannot achieve. It is noteworthy that the metamaterial structure has obvious polarization sensitivity. The metamaterial structure has both high refractive index and wideband zero refractive index properties when different polarized light is incident. At the same time, we further investigate the influence of metamaterial geometric parameters on the effective refractive index of metamaterials. Also, we propose a double grating metamaterial structure to obtain more degrees of freedom of metamaterial on the effective refractive index.
    Źródło:
    Optica Applicata; 2022, 52, 3; 441--460
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Overview of applications of wire medium in radio engineering means
    Przegląd zastosowań konstrukcji z przewodów w urządzeniach radiowych
    Autorzy:
    Khobzei, M.
    Vovchuk, D.
    Michalska, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/407958.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
    Tematy:
    wire media
    superlens
    hyperlens
    brush
    metamaterial
    struktura z przewodów
    supersoczewka
    hipersoczewka
    struktura z losowym rozmieszczeniem przewodów
    metamateriał
    Opis:
    This paper presents an overview of the main possible applications of wire medium in different field of radio engineering. Wire media possesses the unique electromagnetic properties. There is a number for approaches for manufacturing the wire media of different shapes from microwave frequency up to optical one. The wire media that consists of parallel metallic rods finds application for narrow and broadband power radiation in photovoltaic devices, imaging, endoscopy and many others. The wire metastructures such as hyperlens and brush are applicable to the antennas of wide frequency range.
    W niniejszej pracy dokonano przeglądu głównych możliwych zastosowań struktur z przewodów w różnych dziedzinach inżynierii radiowej. Struktury z przewodów posiadają unikalne właściwości. Istnieje wiele podejść do wytwarzania struktur o różnych kształtach i zastosowaniach od zakresu częstotliwości mikrofalowych do optycznych. Struktury składające się z równoległych przewodników są wykorzystywane do transmisji fal wąskopasmowych i szerokopasmowych fal elektromagnetycznych w urządzeniach fotowoltaicznych, transferu obrazów, endoskopii i wielu innych. Konstrukcje z przewodów, takie jak hiperłącza oraz z losowym rozmieszczeniem przewodów, mogą być wykorzystywane do projektowania anten działających w szerokim zakresie częstotliwości.
    Źródło:
    Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2018, 8, 4; 32-35
    2083-0157
    2391-6761
    Pojawia się w:
    Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    MIMO Antenna Design and Optimization with Enhanced Bandwidth for Wireless Applications
    Autorzy:
    Redd, Mekala Harinath
    Sheela, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1839311.pdf
    Data publikacji:
    2020
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    HFSS
    metamaterial
    mutual coupling
    permittivity
    reflection coefficient
    Opis:
    This paper demonstrates a compact MIMO (Multi Input Multi Output) fractal type antenna for ultra-wide band applications. The proposed antenna is manufactured on a lowcost substrate material and the design is analyzed for various iterations in terms of reflection coefficient, gain, and bandwidth. The 50 Ω transmission line feed is used for both fractal patches and a metamaterial structure is used as the ground plane. The proposed design achieved a wide-band frequency response between 5.8 and 15 GHz, with the reflection coefficient of less than –10 dB. Reduced mutual coupling, positive gain and stable radiation patterns were observed throughout the operating band as well. The bandwidth of 9.2 GHz is achieved with the use of a metamaterial structure on the ground plane. The ECC and diversity gain obtained prove the excellent diversity performance of the antenna. The design was simulated using HFSS software and was tested in a lab.
    Źródło:
    Journal of Telecommunications and Information Technology; 2020, 4; 22-26
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the yield surface of a typical bending-dominant periodic lattice metamaterial
    Autorzy:
    Wang, Yongjun
    Liu, Jinxing
    Powiązania:
    https://bibliotekanauki.pl/articles/2200879.pdf
    Data publikacji:
    2023
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    bending-dominant periodic lattice
    BDPL
    yield
    metamaterial
    strain energy equivalence
    Opis:
    A theoretical method for analyzing the initial yield of a typical bending-dominant peri- odic lattice (BDPL) is established. Based on the principle of strain energy equivalence, the macroscopic effective stiffnesses of lattices are calculated. An empirical formula is employed to consider the contributions of both the axial force and bending moment. The initial yield surface of BDPL can be figured out by comparing the effective stress of each strut to the yield strength of the matrix material. The method is applicable to various BDPLs, which we believe is a helpful extension to the method for lattices comprising axial-tension bars in the literature.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2023, 61, 1; 175--187
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study on Metamaterial-based Bio-inspired Microstrip Antenna Array for 5G Enabled Mobile Health Technology
    Autorzy:
    Colaco, John
    Cotta, Jillian
    Powiązania:
    https://bibliotekanauki.pl/articles/2055230.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    microstrip
    antenna
    bio-inspired
    array
    split-ring
    resonators
    metamaterial
    5G
    Opis:
    5G is a fifth-generation wireless technology that enables extremely fast data transfers and massive connection capacity. Existing Mobile health technology requires more reliable connection power and data transfer rates. The purpose of this research is to design, analyse, and compare the performance of a bio-inspired lotus-shaped microstrip patch antenna array with two to three radiating elements. The proposed antenna utilizes proximity coupled indirect microstrip transmission line feeding technique operating in the 24 GHz-30 GHz frequency band. The results indicate that performance continues to improve as the number of radiating elements increases. Moreover, each radiating element is loaded with complementary and non-complementary split-ring resonators (SRRs). The performance of the proposed microstrip antenna array is then analysed and compared with and without split-ring resonators. The findings validate that the proposed bio-inspired metamaterial-based microstrip patch array antenna is more reliable and performs better than an antenna without SRRs.
    Źródło:
    International Journal of Electronics and Telecommunications; 2022, 68, 2; 201--207
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Narrow transmission mode in one-dimensional symmetric defective photonic crystal containing metamaterial and high Tc superconductor
    Autorzy:
    Srivastava, Sanjeev K.
    Aghajamali, Alireza
    Powiązania:
    https://bibliotekanauki.pl/articles/173630.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    photonic crystal
    photonic band gap
    transmission spectra
    transmission mode
    defect mode
    metamaterial
    negative index material
    superconductor photonic crystal
    Opis:
    We theoretically investigate the properties of narrow transmission mode (defect mode) within the reflection band in one-dimensional symmetric defective photonic crystal containing double negative metamaterial and high temperature superconductors. The transmittance spectrum of the proposed structure is obtained by using the characteristic or transfer matrix method. The results show that by increasing the thickness of air defect, transmission mode shifts towards the lower frequency side. But when the thickness of a superconductor layer is increased, transmission mode shifts towards the high frequency side. Further, the effect of temperature variation of superconducting defect on the defect mode has been investigated and found that when the temperature of superconducting layer increases the frequency of defect mode is red shifted. The shift in frequency has smaller value in the lower temperature region than in the higher temperature region, even if the change in temperature is same. Finally we have discussed the effect of variation of thickness on the defect mode by using the double negative metamaterial as defect layer in place of superconductor layer. The result shows that we get two modes for smaller thickness of double negative layer but only a single mode for larger thickness.
    Źródło:
    Optica Applicata; 2019, 49, 1; 37-50
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A New Implementation of UWB CRLH Based Antennas for Wireless Communications
    Autorzy:
    Alibakhshi-Kenari, M.
    Naser-Mogaddasi, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/307909.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    composite right/left-handed transmission lines
    metamaterial
    modern wireless communication systems
    portable device
    printed Q-shaped antennas
    small antennas
    ultra-wideband antennas
    Opis:
    In this article, a novel ultra wideband (UWB) small antennas based on the composite right/left-handed transmission lines structures are proposed. The antennas are pre- sented with best in size, bandwidth and radiation patterns. Their physical size and the operational frequency depend on the unit cell size and the equivalent transmission line model parameters of the CRLH-TL. To realize characteristics of frst proposed model, Q-shaped gaps printed into rectangular radiation patches are used. The antenna based on composite right/left-handed transmission lines is composed of two unit cells, each of which occupies only 10.8 x 8.6 mm and covers the 2.7{9.3 GHz bandwidth for VSWR < 2. The peak gain and radiation effciency, are 5.78 dBi and 42.1% 9.3 GHz, respectively. Moreover, the second designed antenna has the same size and enhancement bandwidth, gain and radiation effciency than the rst proposed antenna with similar design procedure. It is constructed of the printed Q-shaped four unit cells. The length, width and height are 21.6, 8.6 and 1.6 mm, respectively, and it covers 4.1{11.7 GHz bandwidth for VSWR < 2 having highest gain (7.18 dBi) and radiation effciency (92.69%) at 4.1 GHz.
    Źródło:
    Journal of Telecommunications and Information Technology; 2015, 1; 42-52
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-10 z 10

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