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Influence of rod diameter on acoustic band gaps in 2D phononic crystal

Gruszka K., Nabiałek M., Szota M.

Archives of Materials Science and Engineering

2014

Vol. 68, nr 1

24--30

Purpose: The purpose of this paper is to investigate influence of changing the fill factor (or rod diameter) on acoustic properties of phononic crystal made of mercury rods inside of water matrix. Change in construction of primary cell without changing the shape of rod may cause shifts in bands leading to widening of forbidden band gaps, which is the basis of modern composite material designing process. Design/methodology/approach: Band structure is determined by using the finite element study known as finite difference frequency domain simulation method. This is achieved by virtual construction and simulation of primary cell of phononic crystal. Phononic crystals are special devices which by periodic arrangement of properties related to the sound can affect the transmission of acoustic waves thru their body. Findings: The fill factor/rod diameter has a significant influence on the acoustic band structure of studied phononic crystal which can be divided in two mainly effects: fission and compression of band structure. Research limitations/implications: In order to better understand basic properties of phononic crystals and to get full control over the band gaps a series of similar calculations should be done for broader range of frequencies covering both infrasound and ultrasound wavelength regions. Also structures of other cut shape of rod and different primary cell structure resulting in diverse phononic crystal structure should be investigated in the future. Practical implications: Phononic crystals are important devices in variety of applications ranging from noise control through acoustic computing, health applications and entertainment up to military applications. Therefore full knowledge about specific working conditions and elementary properties is necessary for complete control in targeted applications. Controlling the fill factor is one of the simplest methods to achieve specific band gap positions and widths. Originality/value: The novelty is in use of different phase materials with similar acoustic characteristics affecting the hole sonic properties of device manifested by their calculated band structure. The target group are scientists interested in practical applications of various acoustic materials.

Local attenuation of electromagnetic field generated by wireless communication system inside the building

Choroszuho A., Butryło B.

Przegląd Elektrotechniczny

2011

R. 87, nr 7

123-126

The aim of this paper is an analysis of propagation of a high frequency electromagnetic wave (f=1.8 GHz) in a part of the building. Three typical technologies (i.e. the brick, the reinforced slabs, and the passive building), commonly used in construction of buildings are evaluated. Some phenomena connected with interaction of electromagnetic field with the complex, non-ideal material structures are presented and discussed. The influence of physical properties of materials, and the effect of obstacles such as additional wall are examined. A discussion connected with the influence of the reinforcement and the additional walls on the distribution of electromagnetic field is useful for designers of wireless networks.

Celem publikacji jest analiza propagacji fali elektromagnetycznej wewnątrz części budynku. Analiza dotyczy trzech powszechnie stosowanych typów konstrukcji budowlanych, w których wykorzystuje się: cegły, zbrojone płyty betonowe lub beton komórkowy. Artykuł zawiera dyskusję dotyczącą zjawisk fizycznych związanych z polem elektromagnetycznym występujących w złożonych konstrukcjach. Badany jest wpływ fizycznych właściwości materiałowych i konstrukcji ścian działowych na rozkład pola elektromagnetycznego. Wnioski mogą być źródłem wiedzy dla projektantów bezprzewodowych sieci.