In this paper, the power spectrum and phononic properties of the quasi onedimensional Severin aperiodic multilayer was investigated. Multilayer phononic structures with their phononic band gap properties can be used as filters of mechanical waves. In the paper, the implementation of the Finite Difference Time Domain (FDTD) algorithm with discrete Fourier transform and the Transfer Matrix Method algorithm in the Wolfram Language in Mathematica was made.
The study analyzed the inuence of structural defects on the process of magnetization in the area called the approach to ferromagnetic saturation for bulk Fe60Co10WxNb2Y8B20−x (x = 0, 1) alloys. For this purpose, the magnetization studies were performed in the elds range of 0 T to 2 T using a LakeShore vibrating magnetometer. On the basis of the Kronmüller theory an analysis of the magnetization curves was conducted and the type of occurring structural defects in the studied alloys was established. Then, using a Monte Carlo method the eective anisotropy of the tested samples was designated.
This paper presents the results of studies on the magnetic properties of the Fe60Co10Mo2Y8B20 alloy. The samples were fabricated in the form of plates by the injection-casting method. The structure of the investigated alloy, in the as-quenched state and after annealing, was veried by using X-ray diractometry. The magnetization curves as a function of temperature were measured by a force magnetometer. From thermomagnetic curves the Curie temperature of the alloy was determined. As a critical parameter β was chosen to be equal to 0.36 for these calculations, it conrmed that the alloys may be considered as ferromagnetic of the Heisenberg type. Additionally, using a vibrating sample magnetometer the magnetization and coercivity eld were studied (in magnetic eld up to 2 T).
Geopolymer concrete has the potential to replace ordinary Portland cement which can reduce carbon dioxide emission to the environment. The addition of different amounts of steel fibers, as well as different types of end-shape fibers, could alter the performance of geopolymer concrete. The source of aluminosilicate (fly ash) used in the production of geopolymer concrete may lead to a different result. This study focuses on the comparison between Malaysian fly ash geopolymer concrete with the addition of hooked steel fibers and geopolymer concrete with the addition of straight-end steel fibers to the physical and mechanical properties. Malaysian fly ash was first characterized by x-ray fluorescence (XRF) to identify the chemical composition. The sample of steel fiber reinforced geopolymer concrete was produced by mixing fly ash, alkali activators, aggregates, and specific amounts of hook or straight steel fibers. The steel fibers addition for both types of fibers are 0%, 0.5%, 1.0%, 1.5%, and 2.0% by volume percentage. The samples were cured at room temperature. The physical properties (slump, density, and water absorption) of reinforced geopolymer concrete were studied. Meanwhile, a mechanical performance which is compressive, as well as the flexural strength was studied. The results show that the pattern in physical properties of geopolymer concrete for both types of fibers addition is almost similar where the slump is decreased with density and water absorption is increased with the increasing amount of fibers addition. However, the addition of hook steel fiber to the geopolymer concrete produced a lower slump than the addition of straight steel fibers. Meanwhile, the addition of hook steel fiber to the geopolymer concrete shows a higher density and water absorption compared to the sample with the addition of straight steel fibers. However, the difference is not significant. Besides, samples with the addition of hook steel fibers give better performance for compressive and flexural strength compared to the samples with the addition of straight steel fibers where the highest is at 1.0% of fibers addition.
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