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Nonlinear modelling of Activated Sludge Process

Frącz P.

Poznan University of Technology Academic Journals. Electrical Engineering

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2016

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No. 88

187--197

EN

A computer simulation model for the Activated Sludge Process (ASP) of a wastewater treatment plant (WWT) is presented in this paper. The model is based on non-linear equations, which depend on wastewater concentration and flow, which values vary with time. The proposed ASM1R3 model is a reduced version of the common ASM1 model due to the fact it involves only three state variables: Ss –the dissolved biodegradable organic substrate, SNO – the dissolved nitrate nitrogen and SNH – the dissolved ammonia nitrogen. In an experimental verification the model was considered as well fitted to empirical data. The proposed model is characterized by relatively low computational complexity and can be successfully applied as integral part of the overriding control systems of the WWT plant. As a result of conducted studies it was found that it is possible to apply the ASM1R3 model to optimize and improve the WWT process parameters of the regarded plant.

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Ranking of the Nonlinearities of Electrodynamic Loudspeakers

Ravaund R., Lemarquand G., Lemarquand V., Roussel T.

Archives of Acoustics

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2010

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Vol. 35, No. 1

49-66

EN

The aim of this paper is to present a way of ranking the nonlinearities of electrodynamic loudspeakers. For this purpose, we have constructed a nonlinear analytic model which takes into account the variations of the small signal parameters. The determination of these variations is based on a very precise measurement of the electrical impedance of the electrodynamic loudspeaker. First, we present the experimental method to identify the variations of these parameters, then we propose to study theoretically the importance of these nonlinearities according to the input level or the input frequency. We show that the parameter which creates most of the distortions is not always the same and depends mainly on both the input level and the input frequency. Such results can be very useful for optimization of electrodynamic loudspeakers.

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A new approach of virtual finite element experimentation as a means for modeling advanced machining processes

Hassan A.I., Kosmol J.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2001

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z. 15

143-148

EN

Despite the large number of models of advanced machining processes, such as abrasive waterjet machining (AWJM), which have been developed so far, there still has been confusion about the nature by which workpiece surfaces are eroded. The finite element method (FEM) could provide both qualitative and quantitative means in order to explain the AWJ erosion process. This paper presents an attempt to model the AWJM process using the powerful tool of the finite element method. The main objective is to develop an FE model which would enable to predict the depth of cut without any cutting experiments. In the new model, interaction of the abrasive particle with the workpiece material is traced at small time increments. The model accurately predicts the depth of cut as a result of AWJ impact and the FE results are in good agreement with experimental results.

PL

Nowe podejście do nieliniowego modelowania obróbki strumieniem wodnościernym (AWJM) metodą elementów skończonych jest przedmiotem referatu. To podejście uwzględnia ruch cząstki ścierniwa od momentu opuszczenia dyszy mieszającej aż do odbicia się od powierzchni przedmiotu obrabianego po wykonaniu pracy skrawania z bardzo małym krokiem czasowym rzędu 0,01 μs. Badania symulacyjne pozwoliły na śledzenie zagłębiania się cząstki ścierniwa w materiale przedmiotu. Wykazały że wzrost ciśnienia cieczy zwiększa głębokość penetracji cząstki ścierniwa a tym samym i głębokość cięcia strumieniem cieczy. Bardzo istotny jest także wniosek o niezwykle krótkim czasie procesu odkształcania się warstwy wierzchniej pod działaniem cząstki ścierniwa, który nie przekracza 0,5 μs. Można więc sądzić, że opracowany model elementów skończonych dokładniej symuluje wzajemne oddziaływania warstwy wierzchniej przedmiotu obrabianego i cząstki ścierniwa.