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This paper treats self-consistently the interplay between slow magnetosonic wave penetration and edge plasma DC biasing using a two-field fluid approach. The RF and DC parts are coupled by non-linear RF and DC sheath boundary conditions at lateral boundaries of the simulation domain. Within this approach two mechanisms of RF-induced DC current flows are outlined, depending on the toroidal symmetry of the RF drive. The numerical implementation of the model using COMSOL, its validation against explicit simplified solutions and its planned improvements are discussed. [ABSTRACT FROM AUTHOR]

In this chapter we aim to adapt a propagation model for Salalah city (Oman) as we examine the applicability of Okumura-Hata model in Oman in GSM frequency band. The study is a part of an ongoing work by authors, which is being carried out for an urban area on the data obtained from local operator. We accomplished the modification of the model by investigating the variation in pathloss between the measured and predicted values, according to the Okumura-Hata propagation model for a cell in Salalah city and then finding the missing experimental data with cubic regression and spline interpolation. We also verified it by applying the model for other cells. The mean square error (MSE) was calculated between measured path loss values and those predicated on the basis of Okumura-Hata model for an open area. The MSE went up to 6dB, which is an acceptable value for the signal prediction. The model showed a significant difference in an open area that allowed necessary changes to be introduced in the model. Modified equation was also re-verified for another new cell in an open area which gave acceptable results. Theoretical simulation by Okumura-Hata Model and the obtained experimental data is compared and analyzed further using a cubic regression on the set of the experimental data. Scatter plot of the experimental data on pathloss verses distance reveals a third order polynomial trend in the experimental data. Therefore, the cubic regression model was used to estimate the parameters by minimizing the sum of squares of the white noise. The coefficient of determination of this regression suggested that about 90% variation in pathloss can be explained. Theoretical simulation by Okumura-Hata Model and the obtained experimental data is compared and analyzed further using a piece-wise cubic spline to interpolate the set of the experimental data and finding the missing experimental data points. [ABSTRACT FROM AUTHOR]

The brightness of the sound generated by brass instruments at high dynamic level is mainly due to the essential nonlinearity of the wave propagation in the pipe. The bright instruments such as the trumpet and the trombone (high brassiness) are different from more mellow brass instruments such as saxhorns or flugelhorns (low brassiness). The bright instruments have an almost cylindrical pipe segment just downstream of the mouthpiece. The conical bore of the saxhorns in this region implies a faster decay of the wave which reduces the nonlinear wave steepening. To investigate the differences between the brassiness of different instruments, crescendos have to be played (experiments) or simulated (theory). Then a spectral enrichment parameter, characterising the rate of spectral enrichment with increasing dynamic level, can be extracted for each instrument. A frequency-domain numerical model of brass instrument sound production is proposed as a tool to predict the spectral enrichment parameter (brassiness characterisation). It is based on generalized Burger's equations applied to weakly nonlinear wave propagation in non uniform ducts. The relevance of the present tool is evaluated by doing simulations of periodic regimes using typical brass instrument's bores, from which the spectral enrichment parameters are calculated, and compared to measured ones. [ABSTRACT FROM AUTHOR]