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Abstract

The effectiveness of half flat tip serrations on reducing fan blade trailing edge noise was investigated using experimental methods. The experiments were conducted at an anechoic chamber under different rotating fan speeds. Numerical simulations were performed to investigate the mass flow rate generated by the serrated fan and compared with that by the baseline fan. The experimental results showed that the overall amount of noise reduction decreased with the increasing of the distance away from the fan. It was found that the effectiveness of the serrations was not proportional with the rotating speed of the fan where it was most effective at 263 rpm and 2041 rpm with noise reductions about 3.1 dBA and 3.5 dBA, respectively. This phenomenon might be depended on how trailing edge vortex would interact with the serrations at different speeds of the fan. The reduction of mass flow rate reduced with the increasing of the rotating speed and the highest reduction was found at 263 rpm which was about 18% and this reduction was accompanied by overall noise reduction of 3.1 dBA.

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Authors and Affiliations

Hsiao Mun Lee
Kian Meng Lim
Jinlong Xie
Heow Pueh Lee
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Abstract

Aurivillius Bi5Ti3FeO15 (BTF) and Bi5-xNdxTi3FeO15 (BNTF) ceramics were successfully synthesized by a simple solid state reaction method. Ceramics were prepared from simple oxide powders Bi2O3, TiO­2, Nd2O3 and Fe2O3. The microstructure, structure, chemical composition and dielectric properties of the obtained materials were examined. Dielectric properties were investigated in a wide range of temperatures (T = 25ºC-550ºC) and frequencies (20Hz-1MHz).
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Authors and Affiliations

N. Kocoń
1
J. Dzik
ORCID: ORCID
D. Szalbot
1
ORCID: ORCID
T. Pikula
2
ORCID: ORCID
M. Adamczyk-Habrajska
1
ORCID: ORCID
B. Wodecka-Duś
1
ORCID: ORCID

  1. University of Silesia, Institute of Materials Science, 12 Zytnia Str., 41-200 Sosnowiec, Poland
  2. Lublin University of Technology, Institute of Electronics and Information Technology, 38A Nadbystrzycka Str., 20-618 Lublin, Poland
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Abstract

This paper presents that the effect of single aperture size of metallic enclosure on electrical shielding effectiveness (ESE) at 0 – 1 GHz frequency range has been investigated by using both Robinson’s analytical formulation and artificial neural networks (ANN) methods that are multilayer perceptron (MLP) networks and a radial basis function neural network (RBFNN). All results including measurement have been compared each other in terms of aperture geometry of metallic enclosure. The geometry of single aperture varies from square to rectangular shape while the open area of aperture is fixed. It has been observed that network structure of MLP 3-40-1 in modeling with ANN modeled with fewer neurons in the sense of overlapping of faults and data and modeled accordingly. In contrast, the RBFNN 3-150-1 is the other detection that the network structure is modeled with more neurons and more. It can be seen from the same network-structured MLP and RBFNN that the MLP modeled better. In this paper, the impact of dimension of rectangular aperture on shielding performance by using RBFNN and MLP network model with ANN has been studied, as a novelty.

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Authors and Affiliations

Ibrahim Bahadir Basyigit
Habib Dogan

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