Habib Bouhafa - Academia.edu (original) (raw)
Papers by Habib Bouhafa
Applied Mechanics and Materials, 2011
When outdoor air flowing through the tailrace tunnel, it will be handled and its thermodynamic co... more When outdoor air flowing through the tailrace tunnel, it will be handled and its thermodynamic conditions will change under the differences of temperature and water vapor pressure between air and water surface, air and tunnel wall. Utilizing the handled air for space cooling in hydropower station is an energy saving, environmental protection and renewable application of natural cold source. In this paper, a detailed quasi-three-dimensional mathematical model of heat and moisture transfer of tailrace tunnel ventilating was developed and validated against the field test data from Yingxiuwan hydropower station, and the validation shows that the model predicts the test results very well. The model can be used to predict the heat and moisture performance of tailrace tunnel ventilating system.
AIP Conference Proceedings, 2009
ABSTRACT This paper deals with the finite time stability of a particular perturbed systems. We su... more ABSTRACT This paper deals with the finite time stability of a particular perturbed systems. We suppose that the unperturbed system is finite time stable. Using the Lypunov theory and largely inspiring by the Moulay's work, we propose some sufficient conditions to get finite time stability for the considered perturbed system. Numerical simulations and examples are given to illustrate this result.
AIP Conference Proceedings, 2009
This paper deals with the finite time stabilization of a model X4-bidirectional. Using technical ... more This paper deals with the finite time stabilization of a model X4-bidirectional. Using technical of perturbed systems and based on work of R. Mlayeh, L. Beji and A. Abichou intituled ''Yaw-based Control of X4-bidirectional Flyer Planar Motion. We propose a control given stabilization of X4-bidirectional in finite time. Numerical simulations are given to illustrate this result.
Olivae Revista Oficial Del Consejo Oleicola Internacional, 2006
Para evaluar la estabilidad oxidativa del aceite o su susceptibilidad a la oxidacion, se sometio ... more Para evaluar la estabilidad oxidativa del aceite o su susceptibilidad a la oxidacion, se sometio una muestra de aceite de oliva virgen extra a una oxidacion acelerada mediante Rancimat a cuatro temperaturas diferentes ?60, 70, 80 y 90°C? hasta un indice de peroxidos de 20 megO2/kg de aceite. Se evaluaron dos parametros: la evolucion del indice de peroxidos y el contenido en a-tocoferol. El borboteo de aire con un caudal de 25 1/h no modifico los resultados relativos a la evolucion del indice de peroxidos y la concentracion de a-tocoferol durante los ensayos de oxidacion acelerada. Durante el periodo de induccion, las velocidades de formacion de los peroxidos y de la degradacion del a-tocoferol resultan bajas, con reacciones de orden cero y coeficientes de correlacion de las regresiones lineales R2 entre 0,96 y 0,99. Con las cuatro temperaturas de oxidacion y un indice de peroxidos de 20 megO2/kg de aceite, el atocoferol no es el primer antioxidante en degradarse; dichas perdidas son de un 30-40% del contenido inicial. Se han obtenido correlaciones entre acumulacion del peroxido, tiempo de almacenamiento y deterioro del a-tocoferol, y entre el indice de peroxidos y el a-tocoferol.
International Journal of Bifurcation and Chaos, 2015
This paper is devoted to the study of food chain predator–prey model. This model is given by a re... more This paper is devoted to the study of food chain predator–prey model. This model is given by a reaction–diffusion system defined on a circular spatial domain, which includes three-state variables namely, prey and intermediate predator and top predator and incorporates the Holling type II and a modified Leslie–Gower functional response. The aim of this paper is to investigate theoretically and numerically the asymptotic behavior of the interior equilibrium of the model. The local and global stabilities of the positive steady-state solution and the conditions that enable the occurrence of Hopf bifurcation and Turing instability in the circular spatial domain are proved. In the end, we carry out numerical simulations to illustrate how biological processes can affect spatiotemporal pattern formation in a disc spatial domain and different types of spatial patterns with respect to different time steps and diffusion coefficients are obtained.
Evolution Equations & Control Theory, 2015
In this paper, we present a predator-prey model with modified Leslie-Gower and Beddington-DeAngel... more In this paper, we present a predator-prey model with modified Leslie-Gower and Beddington-DeAngelis functional response. The model is governed by a two dimensional reaction diffusion system defined on a disc domain. The conditions of boundedness, existence of a positively invariant and attracting set are proved. Sufficient conditions of local and global stability of the positive steady state are established. In the end, we carry out some numerical simulations in order to illustrate our theoretical results and to interpret how biological processes affect spatio-temporal pattern formation.
2014 Second World Conference on Complex Systems (WCCS), 2014
ABSTRACT In the present work, we are investigating the spatiotemporal dynamics predator-prey mode... more ABSTRACT In the present work, we are investigating the spatiotemporal dynamics predator-prey model with modified Leslie-Gower and Beddington-DeAngelis functional response. This model is given by a reaction diffusion system defined on a circular spatial domain. We prove the existence of critical lines of Hopf and Turing bifurcations in the circular spatial domain by using mathematical theory. In the end, we carry out numerical simulations to interpret how biological processes affect spatiotemporal pattern formation in a disc spatial domain and the role of the bifurcation parameter on the solutions of the model.
International Journal of Food Engineering, 2012
In this study, response surface methodology (RSM) was used to optimize the extraction conditions ... more In this study, response surface methodology (RSM) was used to optimize the extraction conditions of polysaccharides from the pulp of Zizyphus lotus fruit. A central composite rotatable design (CCRD) was used for experimental design and analysis of the results to obtain the optimal processing parameters. Ethanol concentration, extraction temperature, extraction time and water to raw material ratio were found to have a significant effect ( p < 0.05) on the yield of Zizyphus lotus polysaccharide. The 3-D response surface and contour plots, derived from the mathematical model, were applied to determine the optimal conditions. The optimum conditions were as follows: water to raw material ratio 22.04:1, ethanol concentration of 83.30 %, extraction time of 2.65 h, and extraction temperature of 66.31 °C. Under these conditions, the experimental percentage value was 17.35±0.07 %, which is in well close agreement with the value predicted by the model (17.29 %). The results of physicochem...
Applied Mechanics and Materials, 2011
When outdoor air flowing through the tailrace tunnel, it will be handled and its thermodynamic co... more When outdoor air flowing through the tailrace tunnel, it will be handled and its thermodynamic conditions will change under the differences of temperature and water vapor pressure between air and water surface, air and tunnel wall. Utilizing the handled air for space cooling in hydropower station is an energy saving, environmental protection and renewable application of natural cold source. In this paper, a detailed quasi-three-dimensional mathematical model of heat and moisture transfer of tailrace tunnel ventilating was developed and validated against the field test data from Yingxiuwan hydropower station, and the validation shows that the model predicts the test results very well. The model can be used to predict the heat and moisture performance of tailrace tunnel ventilating system.
AIP Conference Proceedings, 2009
ABSTRACT This paper deals with the finite time stability of a particular perturbed systems. We su... more ABSTRACT This paper deals with the finite time stability of a particular perturbed systems. We suppose that the unperturbed system is finite time stable. Using the Lypunov theory and largely inspiring by the Moulay's work, we propose some sufficient conditions to get finite time stability for the considered perturbed system. Numerical simulations and examples are given to illustrate this result.
AIP Conference Proceedings, 2009
This paper deals with the finite time stabilization of a model X4-bidirectional. Using technical ... more This paper deals with the finite time stabilization of a model X4-bidirectional. Using technical of perturbed systems and based on work of R. Mlayeh, L. Beji and A. Abichou intituled ''Yaw-based Control of X4-bidirectional Flyer Planar Motion. We propose a control given stabilization of X4-bidirectional in finite time. Numerical simulations are given to illustrate this result.
Olivae Revista Oficial Del Consejo Oleicola Internacional, 2006
Para evaluar la estabilidad oxidativa del aceite o su susceptibilidad a la oxidacion, se sometio ... more Para evaluar la estabilidad oxidativa del aceite o su susceptibilidad a la oxidacion, se sometio una muestra de aceite de oliva virgen extra a una oxidacion acelerada mediante Rancimat a cuatro temperaturas diferentes ?60, 70, 80 y 90°C? hasta un indice de peroxidos de 20 megO2/kg de aceite. Se evaluaron dos parametros: la evolucion del indice de peroxidos y el contenido en a-tocoferol. El borboteo de aire con un caudal de 25 1/h no modifico los resultados relativos a la evolucion del indice de peroxidos y la concentracion de a-tocoferol durante los ensayos de oxidacion acelerada. Durante el periodo de induccion, las velocidades de formacion de los peroxidos y de la degradacion del a-tocoferol resultan bajas, con reacciones de orden cero y coeficientes de correlacion de las regresiones lineales R2 entre 0,96 y 0,99. Con las cuatro temperaturas de oxidacion y un indice de peroxidos de 20 megO2/kg de aceite, el atocoferol no es el primer antioxidante en degradarse; dichas perdidas son de un 30-40% del contenido inicial. Se han obtenido correlaciones entre acumulacion del peroxido, tiempo de almacenamiento y deterioro del a-tocoferol, y entre el indice de peroxidos y el a-tocoferol.
International Journal of Bifurcation and Chaos, 2015
This paper is devoted to the study of food chain predator–prey model. This model is given by a re... more This paper is devoted to the study of food chain predator–prey model. This model is given by a reaction–diffusion system defined on a circular spatial domain, which includes three-state variables namely, prey and intermediate predator and top predator and incorporates the Holling type II and a modified Leslie–Gower functional response. The aim of this paper is to investigate theoretically and numerically the asymptotic behavior of the interior equilibrium of the model. The local and global stabilities of the positive steady-state solution and the conditions that enable the occurrence of Hopf bifurcation and Turing instability in the circular spatial domain are proved. In the end, we carry out numerical simulations to illustrate how biological processes can affect spatiotemporal pattern formation in a disc spatial domain and different types of spatial patterns with respect to different time steps and diffusion coefficients are obtained.
Evolution Equations & Control Theory, 2015
In this paper, we present a predator-prey model with modified Leslie-Gower and Beddington-DeAngel... more In this paper, we present a predator-prey model with modified Leslie-Gower and Beddington-DeAngelis functional response. The model is governed by a two dimensional reaction diffusion system defined on a disc domain. The conditions of boundedness, existence of a positively invariant and attracting set are proved. Sufficient conditions of local and global stability of the positive steady state are established. In the end, we carry out some numerical simulations in order to illustrate our theoretical results and to interpret how biological processes affect spatio-temporal pattern formation.
2014 Second World Conference on Complex Systems (WCCS), 2014
ABSTRACT In the present work, we are investigating the spatiotemporal dynamics predator-prey mode... more ABSTRACT In the present work, we are investigating the spatiotemporal dynamics predator-prey model with modified Leslie-Gower and Beddington-DeAngelis functional response. This model is given by a reaction diffusion system defined on a circular spatial domain. We prove the existence of critical lines of Hopf and Turing bifurcations in the circular spatial domain by using mathematical theory. In the end, we carry out numerical simulations to interpret how biological processes affect spatiotemporal pattern formation in a disc spatial domain and the role of the bifurcation parameter on the solutions of the model.
International Journal of Food Engineering, 2012
In this study, response surface methodology (RSM) was used to optimize the extraction conditions ... more In this study, response surface methodology (RSM) was used to optimize the extraction conditions of polysaccharides from the pulp of Zizyphus lotus fruit. A central composite rotatable design (CCRD) was used for experimental design and analysis of the results to obtain the optimal processing parameters. Ethanol concentration, extraction temperature, extraction time and water to raw material ratio were found to have a significant effect ( p < 0.05) on the yield of Zizyphus lotus polysaccharide. The 3-D response surface and contour plots, derived from the mathematical model, were applied to determine the optimal conditions. The optimum conditions were as follows: water to raw material ratio 22.04:1, ethanol concentration of 83.30 %, extraction time of 2.65 h, and extraction temperature of 66.31 °C. Under these conditions, the experimental percentage value was 17.35±0.07 %, which is in well close agreement with the value predicted by the model (17.29 %). The results of physicochem...