A second order technique is presented for the evaluation of peak/off-peak price functions, based ... more A second order technique is presented for the evaluation of peak/off-peak price functions, based on marginal cost methods, in energy storage technologies. This method is particulary useful in statical optimization of the fundamental parameters required for planning energy storage plants. Its application permits to transform the original dynamic optimization problem into its statical equivalent, thus reducing considerably the computing time needed. This transformation introduces two additional parameters to be optimized using statical optimization methods, i.e. charging and discharging duration.
The research results presented here are part of a more extensive effort regarding sustained bioco... more The research results presented here are part of a more extensive effort regarding sustained bioconvection in porous media. Bioconvection is the phenomenon of gravity driven fluid motion due to buoyancy forces resulting from density differences between the fluid and motile micro-organisms suspended in the fluid. While the field of bio-convection in pure fluids emerged substantially over the past decade the corresponding effects of bio-convection in porous media received much less attention, despite the fact that micro-organisms grow naturally in porous environments; soil, food and human tissues serve as basic examples. The research focuses in two major new directions. The first deals with the theoretical and experimental investigation of bio-convection in porous media. The second major new direction is linked to the sustainability of the bio-convection motion. The existing work on bio-convection in both pure fluids and porous media exclude micro-organism growth during the bio-convection because the time scales concerned were very short. However, when the question of the sustainability of this convection over long times arises, microorganism growth has to be accounted for. If sustained bio-convection in porous media is possible it opens the avenue to investigate its impact on microbial proliferation in soil, food and human tissue, an important avenue for application of the theoretical results. Then, if bio-convection enhances microbial proliferation it may be undesirable in some cases, e.g. in food, or it might be desirable if specific micro-organisms that can be used for contaminated soil remediation will be "helped" by the bio-convection process to access contaminated regions in the soil. The theoretical and experimental results presented in this paper reflect the process of monotonic growth of motile microorganisms (e.g. the PAOI strain of Pseudomonas Aeruginosa) to be included in the bioconvection process. A new proposed model is shown to be the appropriate one to better reflect both conceptually as well as practically the microbial growth process.
SpringerBriefs in applied sciences and technology, Jul 29, 2015
The effect of the Coriolis acceleration on natural convection is presented in this chapter. When ... more The effect of the Coriolis acceleration on natural convection is presented in this chapter. When the imposed thermal gradient is perpendicular to the direction of the centrifugal body force unconditional natural convection occurs. Then the Coriolis effect is reflected in creation of secondary flows in a cross section perpendicular to the direction of the main convection. When the natural convection occurs due to gravitational buoyancy and the thermal gradient is parallel to the direction of the gravity body force natural convection occurs conditionally. Stability analysis is then required and presented for stationary or possibly oscillatory convection. Weak nonlinear solutions identify then the direction of the bifurcations for different values of the controlling parameters.
A review on the transition to weak turbulence and chaotic natural convection in porous media is p... more A review on the transition to weak turbulence and chaotic natural convection in porous media is presented in this chapter. In particular, the question on how can one obtain the transition point analytically is emphasized and topics such as the hysteresis phenomenon linked to this transition is discussed. Fractal types of results obtained by comparing solutions at different accuracy levels are finally presented to conclude the chapter.
International Journal of Non-linear Mechanics, Mar 1, 2001
The derivation of a set of compatibility conditions for the equivalence between a weak non-linear... more The derivation of a set of compatibility conditions for the equivalence between a weak non-linear analytical solution and any computational or numerical solution is presented. Both direct and inverse transformations are derived and shown to apply well for arbitrary initial conditions, provided that a validity condition of the asymptotic expansion associated with the weak non-linear solution is not violated. The results presented by using these compatibility conditions for a comparison between computational and analytical transitional values of a scaled Rayleigh number, that represents the point of transition from steady-to-chaotic solutions, show very good agreement within the validity domain of the asymptotic expansion.
SpringerBriefs in applied sciences and technology, Jul 29, 2015
Modeling of flow and heat transfer in rotating porous media is introduced in this chapter. The go... more Modeling of flow and heat transfer in rotating porous media is introduced in this chapter. The governing equations are presented and transformed into dimensionless form in order, among others, to identifying conditions for neglecting terms in these equations. The classification of different types of rotating flows in porous media concludes the chapter.
Microorganism growth and reproduction have been traditionally modeled independently of the direct... more Microorganism growth and reproduction have been traditionally modeled independently of the direct effect of the metabolic process. The latter caused inconsistencies between the modeling results and experimental data. A major inconsistency was linked to the experimentally observed lag phase in the growth process. Attempts to associate the lag phase to delay processes have been recently proven incorrect. The only other alternative is the existence of unstable stationary states resulting from the explicit inclusion of the metabolic mass transfer process via the resource consumption and utilization. The proposed theory that accounts for the latter is presented, analyzed, and compared with experimental data both qualitatively as well as quantitatively.
A second order technique is presented for the evaluation of peak/off-peak price functions, based ... more A second order technique is presented for the evaluation of peak/off-peak price functions, based on marginal cost methods, in energy storage technologies. This method is particulary useful in statical optimization of the fundamental parameters required for planning energy storage plants. Its application permits to transform the original dynamic optimization problem into its statical equivalent, thus reducing considerably the computing time needed. This transformation introduces two additional parameters to be optimized using statical optimization methods, i.e. charging and discharging duration.
The research results presented here are part of a more extensive effort regarding sustained bioco... more The research results presented here are part of a more extensive effort regarding sustained bioconvection in porous media. Bioconvection is the phenomenon of gravity driven fluid motion due to buoyancy forces resulting from density differences between the fluid and motile micro-organisms suspended in the fluid. While the field of bio-convection in pure fluids emerged substantially over the past decade the corresponding effects of bio-convection in porous media received much less attention, despite the fact that micro-organisms grow naturally in porous environments; soil, food and human tissues serve as basic examples. The research focuses in two major new directions. The first deals with the theoretical and experimental investigation of bio-convection in porous media. The second major new direction is linked to the sustainability of the bio-convection motion. The existing work on bio-convection in both pure fluids and porous media exclude micro-organism growth during the bio-convection because the time scales concerned were very short. However, when the question of the sustainability of this convection over long times arises, microorganism growth has to be accounted for. If sustained bio-convection in porous media is possible it opens the avenue to investigate its impact on microbial proliferation in soil, food and human tissue, an important avenue for application of the theoretical results. Then, if bio-convection enhances microbial proliferation it may be undesirable in some cases, e.g. in food, or it might be desirable if specific micro-organisms that can be used for contaminated soil remediation will be "helped" by the bio-convection process to access contaminated regions in the soil. The theoretical and experimental results presented in this paper reflect the process of monotonic growth of motile microorganisms (e.g. the PAOI strain of Pseudomonas Aeruginosa) to be included in the bioconvection process. A new proposed model is shown to be the appropriate one to better reflect both conceptually as well as practically the microbial growth process.
SpringerBriefs in applied sciences and technology, Jul 29, 2015
The effect of the Coriolis acceleration on natural convection is presented in this chapter. When ... more The effect of the Coriolis acceleration on natural convection is presented in this chapter. When the imposed thermal gradient is perpendicular to the direction of the centrifugal body force unconditional natural convection occurs. Then the Coriolis effect is reflected in creation of secondary flows in a cross section perpendicular to the direction of the main convection. When the natural convection occurs due to gravitational buoyancy and the thermal gradient is parallel to the direction of the gravity body force natural convection occurs conditionally. Stability analysis is then required and presented for stationary or possibly oscillatory convection. Weak nonlinear solutions identify then the direction of the bifurcations for different values of the controlling parameters.
A review on the transition to weak turbulence and chaotic natural convection in porous media is p... more A review on the transition to weak turbulence and chaotic natural convection in porous media is presented in this chapter. In particular, the question on how can one obtain the transition point analytically is emphasized and topics such as the hysteresis phenomenon linked to this transition is discussed. Fractal types of results obtained by comparing solutions at different accuracy levels are finally presented to conclude the chapter.
International Journal of Non-linear Mechanics, Mar 1, 2001
The derivation of a set of compatibility conditions for the equivalence between a weak non-linear... more The derivation of a set of compatibility conditions for the equivalence between a weak non-linear analytical solution and any computational or numerical solution is presented. Both direct and inverse transformations are derived and shown to apply well for arbitrary initial conditions, provided that a validity condition of the asymptotic expansion associated with the weak non-linear solution is not violated. The results presented by using these compatibility conditions for a comparison between computational and analytical transitional values of a scaled Rayleigh number, that represents the point of transition from steady-to-chaotic solutions, show very good agreement within the validity domain of the asymptotic expansion.
SpringerBriefs in applied sciences and technology, Jul 29, 2015
Modeling of flow and heat transfer in rotating porous media is introduced in this chapter. The go... more Modeling of flow and heat transfer in rotating porous media is introduced in this chapter. The governing equations are presented and transformed into dimensionless form in order, among others, to identifying conditions for neglecting terms in these equations. The classification of different types of rotating flows in porous media concludes the chapter.
Microorganism growth and reproduction have been traditionally modeled independently of the direct... more Microorganism growth and reproduction have been traditionally modeled independently of the direct effect of the metabolic process. The latter caused inconsistencies between the modeling results and experimental data. A major inconsistency was linked to the experimentally observed lag phase in the growth process. Attempts to associate the lag phase to delay processes have been recently proven incorrect. The only other alternative is the existence of unstable stationary states resulting from the explicit inclusion of the metabolic mass transfer process via the resource consumption and utilization. The proposed theory that accounts for the latter is presented, analyzed, and compared with experimental data both qualitatively as well as quantitatively.
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Papers by Peter Vadasz