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Experimental research of the AMWG algorithm for assessing amplitude modulation in wind turbine noise

Czapla Marcjanna, Wszołek Tadeusz

Vibrations in Physical Systems

2022

Vol. 33, nr 3

art. no. 2022317

The operation of a wind turbine (WT) is characterized by fluctuations in sound pressure amplitude associated with the passage of the propeller blade through the tower. Amplitude Modulation (AM) is one of the factors that contributes to the increased annoyance of wind turbine noise. The phenomenon of AM is currently the subject of research in many research centers around the world in the context of a parametric assessment of its impact on annoyance. Despite the development of many methods to measure the AM of a WT noise, there is no commonly accepted method. This paper discusses the most crucial factors that stimulate the phenomenon of AM and the implementation in the MATLAB environment of the algorithm to find the frequency and depth of AM proposed by the Amplitude Modulation Working Group (AMWG). The results of verification of the developed algorithm as well as the measurement results of the frequency and depth of modulation for two measurement samples of a 2 MW wind turbine are presented.

Influence of modulation frequency on the synthesis of thin films in pulsed magnetron sputtering processes

Strzelecki G. W., Nowakowska-Langier K., Chodun R., Okrasa S., Wicher B., Zdunek K.

Materials Science Poland

2018

Vol. 36, No. 4

697--703

The research on the influence of modulation frequency on the properties of films synthesized using a unique pulsed power supply combined with a standard unbalanced circular magnetron was conducted in the process of pulsed magnetron sputtering (PMS). It was shown that by using different levels of modulation, the composition of plasma (measured by optical emission spectroscopy, OES) as well as film growth rate and morphology (observed with scanning electron microscope, SEM), can be changed. The impact of modulation is related to the used materials and gases and can vary significantly. It was concluded that modulation frequency can greatly influence the synthesis of materials and can be used as an additional parameter in PMS. Specific relations between modulation frequency and synthesized material require further investigation.