The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform
Craig E. Manning - One of the best experts on this subject based on the ideXlab platform.
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the chemistry of subduction zone fluids
Earth and Planetary Science Letters, 2004Co-Authors: Craig E. ManningAbstract:Subduction zones generate voluminous magma and mediate global element cycling. Fluids are essential to this activity, yet their behavior is perhaps the most poorly understood aspect of the subduction process. Though many volatile components are subducted, H2O is the most abundant, is preferentially fractionated into the fluid phase, and, among terrestrial volatiles, is by far the most effective solvent. H2O therefore controls the chemical properties of subduction-zone fluids. Rising pressure (P) and temperature (T) along subduction paths yield increased H2O ionization, which enhances Dissolved Solute concentrations. Under appropriate conditions, silicate solubilities may become so high that there is complete miscibility between hydrous melts and dilute aqueous solutions. Miscible fluids of intermediate composition (e.g., 50% silicate, 50% H2O) are commonly invoked as material-transport agents in subduction zones; however, phase relations pose problems for their existence over significant length scales in the mantle. Nevertheless, this behavior provides a key clue pointing to the importance of polymerization of alkali aluminosilicate components in deep fluids. Aqueous aluminosilicate polymers may enhance solubility of important elements even in H2O-rich fluids. Subduction-zone fluids may be surprisingly dilute, having only two to three times the total Dissolved solids (TDS) of seawater. Silica and alkalis are the dominant Solutes, with significant Al and Ca and low Mg and Fe, consistent with a role for aqueous aluminosilicate polymers. Trace-element patterns of fluids carrying only Dissolved silicate components are similar to those of primitive island-arc basalts, implying that reactive flow of H2O-rich, Cl-poor, alkali-aluminosilicate-bearing fluid is fundamental to element transport in the mantle wedge. Better understanding of the interaction of this fluid with the mantle wedge requires quantitative reaction-flow modeling, but further studies are required to achieve this goal.
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The chemistry of subduction-zone fluids
Earth and Planetary Science Letters, 2004Co-Authors: Craig E. ManningAbstract:Subduction zones generate voluminous magma and mediate global element cycling. Fluids are essential to this activity, yet their behavior is perhaps the most poorly understood aspect of the subduction process. Though many volatile components are subducted, H2O is the most abundant, is preferentially fractionated into the fluid phase, and, among terrestrial volatiles, is by far the most effective solvent. H2O therefore controls the chemical properties of subduction-zone fluids. Rising pressure (P) and temperature (T) along subduction paths yield increased H2O ionization, which enhances Dissolved Solute concentrations. Under appropriate conditions, silicate solubilities may become so high that there is complete miscibility between hydrous melts and dilute aqueous solutions. Miscible fluids of intermediate composition (e.g., 50% silicate, 50% H2O) are commonly invoked as material-transport agents in subduction zones; however, phase relations pose problems for their existence over significant length scales in the mantle. Nevertheless, this behavior provides a key clue pointing to the importance of polymerization of alkali aluminosilicate components in deep fluids. Aqueous aluminosilicate polymers may enhance solubility of important elements even in H2O-rich fluids. Subduction-zone fluids may be surprisingly dilute, having only two to three times the total Dissolved solids (TDS) of seawater. Silica and alkalis are the dominant Solutes, with significant Al and Ca and low Mg and Fe, consistent with a role for aqueous aluminosilicate polymers. Trace-element patterns of fluids carrying only Dissolved silicate components are similar to those of primitive island-arc basalts, implying that reactive flow of H2O-rich, Cl-poor, alkali-aluminosilicate-bearing fluid is fundamental to element transport in the mantle wedge. Better understanding of the interaction of this fluid with the mantle wedge requires quantitative reaction-flow modeling, but further studies are required to achieve this goal. © 2004 Elsevier B.V. All rights reserved.
Zoltan K. Nagy - One of the best experts on this subject based on the ideXlab platform.
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Population balance model based multi-objective optimization and robustness analysis of a continuous plug flow antisolvent crystallizer
2014 American Control Conference, 2014Co-Authors: Bradley J. Ridder, Aniruddha Majumder, Zoltan K. NagyAbstract:Crystallization is a major separation process in the pharmaceutical industry. Most crystallizations are performed batchwise, but there is great incentive for switching to continuous operation. We have investigated the modeling, simulation, optimization, and robustness of a multi-segmented, multi-addition plug-flow crystallizer (MSMA-PFC). The design accepts multiple antisolvent flows along its length, permitting localized control of supersaturation. A mass balance equation was used to track the depletion of Dissolved Solute (flufenamic acid), and a population balance equation for tracking the crystal size distribution. Multiobjective optimization was done using the antisolvent flowrates into each segment as decision variables. The genetic algorithm was used to calculate the Pareto frontiers for the two competing objectives of maximizing average crystal size (L43), and minimizing coefficient of variation (CV). The sensitivity of the Pareto frontier to variation in the growth and nucleation kinetic parameters was investigated. The robustness of a single solution was examined as well with respect to error in the kinetic parameters, as well as to errors in antisolvent flowrate.
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Population Balance Model-Based Multiobjective Optimization of a Multisegment Multiaddition (MSMA) Continuous Plug-Flow Antisolvent Crystallizer
Industrial & Engineering Chemistry Research, 2014Co-Authors: Bradley J. Ridder, Aniruddha Majumder, Zoltan K. NagyAbstract:Crystallization is a major separation process in the pharmaceutical industry. Most crystallizations are performed batchwise, but there is great incentive for converting them to continuous operations. This paper investigates the modeling, simulation, and optimization of a special antisolvent plug-flow crystallizer: the multisegmented, multiaddition plug-flow crystallizer (MSMA-PFC). The MSMA-PFC accepts multiple antisolvent flows along its length, permitting finer control of supersaturation. A steady-state population balance equation was applied for tracking the crystal size distribution, and a mass balance equation was used to track the depletion of Dissolved Solute (flufenamic acid). A multiobjective optimization framework was applied to determine the antisolvent flow rates into each segment that simultaneously maximize the average crystal size, and minimize the coefficient of variation. The set of coupled differential equations was solved, depending on circumstance, with either the method-of-moments (MO...
Suveen N. Mathaudhu - One of the best experts on this subject based on the ideXlab platform.
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influence of mn Solute content on grain size reduction and improved strength in mechanically alloyed al mn alloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014Co-Authors: Kristopher A Darling, Anthony J Roberts, L Armstrong, D Kapoor, M A Tschopp, Laszlo J. Kecskes, Suveen N. MathaudhuAbstract:Abstract Al–Mn alloys with a solid-solution Mn content ranging from 0 to 3.1 at% were successfully prepared by high energy mechanical alloying at room temperature of an Al–8 at% Mn sample. The solubility level obtained is up to five times the equilibrium solubility limit of Mn in Al (from 0.62 at% Mn). In general, the observed microstructures are consistent with being a nanocomposite composed of an Al–Mn solid solution matrix with dispersed Mn particles. For alloys with solid solutions up to 3.1 at%, increasing the Mn content correlated with a decrease in the matrix grain size down to a minimum of 12 nm. High hardness values of ~4 GPa were obtained. The main strengthening mechanism of the Al–Mn alloys is attributed to the grain size reduction. Further attempts to increase the Dissolved Solute content resulted in the precipitation of the Al 6 Mn equilibrium intermetallic phase.
R Chawla - One of the best experts on this subject based on the ideXlab platform.
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Improvement of the one-dimensional Dissolved-Solute convection equation using the QUICKEST–ULTIMATE algorithm
Nuclear Engineering and Design, 2020Co-Authors: Davide Bertolotto, Annalisa Manera, Rafael Macian-juan, R ChawlaAbstract:The U.S.-NRC best-estimate system code TRACE adopts a finite volumes, first-order upwind discretization scheme to solve the Dissolved-Solute convection equation. Such a scheme is known to strongly suffer from numerical diffusion, which can be a significant drawback in analyzing certain safety relevant scenarios in nuclear power plants, e.g. with plugs of Solute (or plugs of diluting water) traveling from the loops to the core and thus affecting the reactivity of the system. In such cases, high-order upwind convecting schemes are better suited to discretize and solve the Solute convection equation. In particular, the explicit QUICKEST (Quadratic Upwind Interpolation for Convective Kinematics with Estimated Streaming Terms) scheme, together with the ULTIMATE (Universal Limiter for Transient Interpolation Modeling of the Advective Transport Equation) limiter, offers an attractive solution, thanks to the overall third-order accuracy, the intrinsic stability of the upwind scheme and the limited increase in computational costs. In order to demonstrate the feasibility and the advantages of the implementation of such a solution strategy in TRACE, the scheme has been implemented in the code and verified for simple geometries (e.g. straight pipes) and for a double T-junction loop, the latter in the context of using a CFD (Computational Fluid dynamics) code coupled with TRACE.
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improvement of the one dimensional Dissolved Solute convection equation using the quickest ultimate algorithm
Nuclear Engineering and Design, 2011Co-Authors: Davide Bertolotto, Annalisa Manera, Rafael Macianjuan, R ChawlaAbstract:The U.S.-NRC best-estimate system code TRACE adopts a finite volumes, first-order upwind discretization scheme to solve the Dissolved-Solute convection equation. Such a scheme is known to strongly suffer from numerical diffusion, which can be a significant drawback in analyzing certain safety relevant scenarios in nuclear power plants, e.g. with plugs of Solute (or plugs of diluting water) traveling from the loops to the core and thus affecting the reactivity of the system. In such cases, high-order upwind convecting schemes are better suited to discretize and solve the Solute convection equation. In particular, the explicit QUICKEST (Quadratic Upwind Interpolation for Convective Kinematics with Estimated Streaming Terms) scheme, together with the ULTIMATE (Universal Limiter for Transient Interpolation Modeling of the Advective Transport Equation) limiter, offers an attractive solution, thanks to the overall third-order accuracy, the intrinsic stability of the upwind scheme and the limited increase in computational costs. In order to demonstrate the feasibility and the advantages of the implementation of such a solution strategy in TRACE, the scheme has been implemented in the code and verified for simple geometries (e.g. straight pipes) and for a double T-junction loop, the latter in the context of using a CFD (Computational Fluid dynamics) code coupled with TRACE.
Bradley J. Ridder - One of the best experts on this subject based on the ideXlab platform.
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Population balance model based multi-objective optimization and robustness analysis of a continuous plug flow antisolvent crystallizer
2014 American Control Conference, 2014Co-Authors: Bradley J. Ridder, Aniruddha Majumder, Zoltan K. NagyAbstract:Crystallization is a major separation process in the pharmaceutical industry. Most crystallizations are performed batchwise, but there is great incentive for switching to continuous operation. We have investigated the modeling, simulation, optimization, and robustness of a multi-segmented, multi-addition plug-flow crystallizer (MSMA-PFC). The design accepts multiple antisolvent flows along its length, permitting localized control of supersaturation. A mass balance equation was used to track the depletion of Dissolved Solute (flufenamic acid), and a population balance equation for tracking the crystal size distribution. Multiobjective optimization was done using the antisolvent flowrates into each segment as decision variables. The genetic algorithm was used to calculate the Pareto frontiers for the two competing objectives of maximizing average crystal size (L43), and minimizing coefficient of variation (CV). The sensitivity of the Pareto frontier to variation in the growth and nucleation kinetic parameters was investigated. The robustness of a single solution was examined as well with respect to error in the kinetic parameters, as well as to errors in antisolvent flowrate.
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Population Balance Model-Based Multiobjective Optimization of a Multisegment Multiaddition (MSMA) Continuous Plug-Flow Antisolvent Crystallizer
Industrial & Engineering Chemistry Research, 2014Co-Authors: Bradley J. Ridder, Aniruddha Majumder, Zoltan K. NagyAbstract:Crystallization is a major separation process in the pharmaceutical industry. Most crystallizations are performed batchwise, but there is great incentive for converting them to continuous operations. This paper investigates the modeling, simulation, and optimization of a special antisolvent plug-flow crystallizer: the multisegmented, multiaddition plug-flow crystallizer (MSMA-PFC). The MSMA-PFC accepts multiple antisolvent flows along its length, permitting finer control of supersaturation. A steady-state population balance equation was applied for tracking the crystal size distribution, and a mass balance equation was used to track the depletion of Dissolved Solute (flufenamic acid). A multiobjective optimization framework was applied to determine the antisolvent flow rates into each segment that simultaneously maximize the average crystal size, and minimize the coefficient of variation. The set of coupled differential equations was solved, depending on circumstance, with either the method-of-moments (MO...