Search results for "satu"
showing 10 items of 1367 documents
Modeling Round Robin Test: An Uncoupled Approach
2014
Abstract The solution of the modeling test presented in the paper is based on an uncoupled hydro-mechanical approach. Firstly, the controlled infiltration process is modeled by a finite element transient groundwater seepage software. Afterwards, calculated pore water pressures at successive instants are used for the slope stability analysis. Time evolution of the slope stability is analysed by using the infinite slope model, according to the classical limit equilibrium method.
Fuzzy control for Electric Power Steering System with assist motor current input constraints
2015
Abstract Friction and disturbances of the road are the main sources of nonlinearity in the Electric Power Steering (EPS) System. Consequently, conventional linear controllers design based on a simplified linear model of the EPS system will result in poor dynamic performance or system instability. On the other hand, a brush-type DC motor is more used in EPS control with an input current that is limited in practice. The control laws designed without taking into account the saturation effect may have undesirable consequences on the system stability. In this paper, a Takagi–Sugeno (T−S) fuzzy is used to represent the nonlinear behavior of an EPS system, and stabilization conditions for nonlinea…
Hidden oscillations in stabilization system of flexible launcher with saturating actuators
2013
Abstract In the paper the attitude stabilization system of the unstable flexible launcher with saturating input is considered. It is demonstrated that due to actuator saturation the system performance can significantly degrade. The analytical-numerical method is applied to demonstrate possibility of hidden oscillations and localize their attractor.
Parameter identification of induction motor model by means of State Space-Vector Model Output Error Minimization
2014
This paper proposes a technique for the off-line estimation of the electrical parameters of the equivalent circuit of an Induction Machines (IM), and focuses on the application of an algorithm based on the minimization of a suitable cost function involving the differences between the measured stator current direct (sD) and quadrature (sQ) components and the corresponding estimated by the IM state model. This method exploits an entire start-up transient of the IM to estimate all of the 4 electrical parameters of the machine (Rs, Ls, σLs, Tr). It proposes also a set of tests to be made in order to estimate the variation of the magnetic parameters of the IM versus the rotor magnetizing current…
Connected pathway relative permeability from pore-scale imaging of imbibition
2016
Abstract Pore-scale images obtained from a synchrotron-based X-ray computed micro-tomography (µCT) imbibition experiment in sandstone rock were used to conduct Navier–Stokes flow simulations on the connected pathways of water and oil phases. The resulting relative permeability was compared with steady-state Darcy-scale imbibition experiments on 5 cm large twin samples from the same outcrop sandstone material. While the relative permeability curves display a large degree of similarity, the endpoint saturations for the µCT data are 10% in saturation units higher than the experimental data. However, the two datasets match well when normalizing to the mobile saturation range. The agreement is p…
Insight into the role of the zeolitization process in enhancing the adsorption performance of kaolinite/diatomite geopolymer for effective retention …
2021
Abstract Diatomite/kaolinite-based geopolymer (GP) was synthesized and incorporated in zeolitization process (Z/GP) to investigate the role of the zeolite phases in inducing its retention capacity of the dissolved Sr (II) ions in water. The retention of Sr (II) ions using Z/GP in comparison with GP was evaluated based on both batch and fixed-bed column studies. In the batch study, the zeolitized geopolymer (Z/GP) shows enhancement in the Sr (II) retention capacity (193.7 mg/g) as compared to the normal geopolymer (102 mg/g). Moreover, the recyclability studies demonstrate higher stability for Z/GP than GP with a retention percentage higher than 90% for five reusing runs. The kinetic and the…
Combined effects of eutrophication and warming on polyunsaturated fatty acids in complex phytoplankton communities:A mesocosm experiment
2022
Climate change and eutrophication are among the main stressors of shallow freshwater ecosystems, and their effects on phytoplankton community structure and primary production have been studied extensively. However, their combined effects on the algal production of polyunsaturated fatty acids (PUFA), specifically, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are currently unresolved. Moreover, the proximate reasons for changes in phytoplankton EPA and DHA concentrations are unclear, i.e., the relative importance of ecological (changes in the community composition) vs. ecophysiological (within taxa changes in EPA and DHA levels) factors. We investigated the responses of phytopla…
Assessment of flushing methods for the removal of heavy chlorinated compounds DNAPL in an alluvial aquifer.
2017
International audience; Immiscible mobilization and foam flushing were assessed as low surfactant consuming technologies, for the enhanced recovery of dense non-aqueous phase liquid (DNAPL) residual at a site contaminated by heavy chlorinated compounds. Preliminary experiments in well-controlled conditions demonstrated the phenomena involved in these remediation technologies and their limitations. Furthermore, we characterized the technologies according to by their surfactant consumption (per kg of DNAPL recovered) and the final DNAPL saturation reached. Surfactant foam flushing (SFF) produced lower DNAPL saturation than immiscible mobilization, thanks to its higher viscosity. However, its …
Effect of pH, substrate and free nitrous acid concentrations on ammonium oxidation rate.
2012
Respirometric techniques have been used to determine the effect of pH, free nitrous acid (FNA) and substrate concentration on the activity of the ammonium oxidizing bacteria (AOB) present in an activated sludge reactor. With this aim, bacterial activity has been measured at different pH values (ranging from 6.2 to 9.7), total ammonium nitrogen concentrations (ranging from 0.1 to 10 mg TAN L-1) and total nitrite concentrations (ranging from 3 to 43 mg NO2-N L-1). According to the results obtained, the most appropriate kinetic expression for the growth of AOB in activated sludge reactors has been established. Substrate half saturation constant and FNA and pH inhibition constants have been obt…
Greenhouse gases from membrane bioreactors: Mathematical modelling, sensitivity and uncertainty analysis
2017
In this study a new mathematical model to quantify greenhouse gas emissions (namely, carbon dioxide and nitrous oxide) from membrane bioreactors (MBRs) is presented. The model has been adopted to predict the key processes of a pilot plant with pre-denitrification MBR scheme, filled with domestic and saline wastewater. The model was calibrated by adopting an advanced protocol based on an extensive dataset. In terms of nitrous oxide, the results show that an important role is played by the half saturation coefficients related to nitrogen removal processes and the model factors affecting the oxygen transfer rate in the aerobic and MBR tanks. Uncertainty analysis showed that for the gaseous mod…