Narrow Results

As was pointed out in some recent papers, the fluctuations in the secondary particle distribution of extensive air showers at observation level exhibit a complex structure which can be interpreted as a white noise plus a 1/f noise. The resulting coloured noise fits very well into the framework of the universal multitractal theory. In this paper we compare the e⁺ and e^- density fluctuations generated by different primary cosmic rays, namely, high energy γ rays, protons, and helium, oxygen and iron nuclei, and the universal multifractal parameters for all these primaries are calculated for several samples. The performed analysis reveals that the Levy index and the mean codimension depend monotonically on the mass of the primary cosmic ray. Some future applications of the multifractal properties of extensive air showers are suggested.

Self-similar and generally scaling laws are pointed out in time series issued from different types of data. The analysis of these structures has been conducted via many advanced mathematical tools such as wavelets. In this paper, we propose to exploit some self-similar type models for the modeling of time series issued from air quality and/or pollution data, by using wavelet multifractal techniques. The applied models are shown to involve self-similar, multi-scaling and also noised structures. The resulting models are applied empirically on a sample of data issued from air pollution factors in the northwestern region of Tabuk governorate in Saudi Arabia. Some of the chemicals and materials are essential components of many air pollution factors such as PM10 and PM2.5 particles.