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Articles 31 - 60 of 121
Full-Text Articles in Engineering
Letter To The Editor, Sridhar Ungarala
Letter To The Editor, Sridhar Ungarala
Chemical & Biomedical Engineering Faculty Publications
No abstract provided.
Comments On "Robust And Reliable Estimation Via Unscented Recursive Nonlinear Dynamic Data Reconciliation", Sridhar Ungarala
Comments On "Robust And Reliable Estimation Via Unscented Recursive Nonlinear Dynamic Data Reconciliation", Sridhar Ungarala
Chemical & Biomedical Engineering Faculty Publications
No abstract provided.
The Use Of A Cell Filter For State Estimation In Closed-Loop Nmpc Of Low Dimensional Systems, Sridhar Ungarala, Keyu Li
The Use Of A Cell Filter For State Estimation In Closed-Loop Nmpc Of Low Dimensional Systems, Sridhar Ungarala, Keyu Li
Chemical & Biomedical Engineering Faculty Publications
Combining variants of the Kalman filter and moving horizon estimation (MHE) with nonlinear MPC has been studied before. The MHE is appealing due to its ability to impose constraints and demonstrated superiority over extended Kalman filter. However, nonlinear MPC based on MHE requires solutions to two back to back nonlinear programs. In this paper we propose to use the cell filter (CF) to provide state feedback to the MPC regulator. The cell filter is a piecewise constant approximation of the conditional probability density of the states, whose temporal evolution is modeled by an aggregate Markov chain. Since the CF …
Effect Of Synthesis Time And Treatment On Porosity Of Mesoporous Silica Materials, Asli Ertan, Pradeep Kodumuri, Orhan Talu, Surendra N. Tewari
Effect Of Synthesis Time And Treatment On Porosity Of Mesoporous Silica Materials, Asli Ertan, Pradeep Kodumuri, Orhan Talu, Surendra N. Tewari
Chemical & Biomedical Engineering Faculty Publications
Nitrogen adsorption at 77 K on mesoporous silica materials (MPS) with varying synthesis time and treatment conditions was investigated. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were also used to characterize the mesoporous materials. This study was performed at 6, 24 and 72-h synthesis times. It is shown that 6-h is not enough for complete formation of the MPS material and at least 24-h is necessary. The pore structure starts decaying for the 72-h synthesis time. The three-after-synthesis treatment conditions used were 1) washed, 2) washed and calcined and 3) directly calcined after synthesis. Ethanol/HCl …
Electrodeposition Of Nickel Nanowires And Nanotubes Using Various Templates, Asli Ertan, Surendra N. Tewari, Orhan Talu
Electrodeposition Of Nickel Nanowires And Nanotubes Using Various Templates, Asli Ertan, Surendra N. Tewari, Orhan Talu
Chemical & Biomedical Engineering Faculty Publications
Nickel nanotubes and nanowires are grown by galvanostatic electrodeposition in the pores of 1000, 100, and 15 nm polycarbonate as well as in anodised alumina membranes at a current density of 10 mA cm-2. The effects of pore size, porosity, electrodeposition time, effective current density, and pore aspect ratio are investigated. Nickel nanotube structures are obtained with 1000 nm pore size polycarbonate membrane without any prior treatment method. At the early stages of electrodeposition hollow nickel nanotubes are produced and nanotubes turn into nanowires at longer depositon times. As effective current density accounting for the membrane porosity decreases, the axial …
Oxygen Diffusion Through Natural Extracellular Matrices: Implications For Estimating "Critical Thickness" Values In Tendon Tissue Engineering, Caroline Androjna, Jorge E. Gatica, Joanne M. Belovich, Kathleen A. Derwin
Oxygen Diffusion Through Natural Extracellular Matrices: Implications For Estimating "Critical Thickness" Values In Tendon Tissue Engineering, Caroline Androjna, Jorge E. Gatica, Joanne M. Belovich, Kathleen A. Derwin
Chemical & Biomedical Engineering Faculty Publications
Oxygen is necessary for maintaining cell proliferation and viability and extracellular matrix (ECM) production in 3-dimensional tissue engineering. Typically, diffusion is the primary mode for oxygen transport in vitro; thus, ensuring an adequate oxygen supply is essential. In this study, we determined the oxygen diffusion coefficients of 3 natural ECMs that are being investigated as construct scaffolds for tendon tissue engineering: small-intestine submucosa (SIS), human dermis (Alloderm (R)), and canine fascia lata. Diffusion coefficients were determined using a standard diffusion cell system. The ranges for each matrix type were: SIS: 7 x 10(-6) - 2 x 10(-5) cm(2)/s, Alloderm (R): …
A Computer Model Of Gluconeogenesis And Lipid Metabolism In The Perfused Liver, Elie Chalhoub, Richard W. Hanson, Joanne M. Belovich
A Computer Model Of Gluconeogenesis And Lipid Metabolism In The Perfused Liver, Elie Chalhoub, Richard W. Hanson, Joanne M. Belovich
Chemical & Biomedical Engineering Faculty Publications
A mathematical model of the perfused rat liver was developed to predict intermediate metabolite concentrations and fluxes in response to changes in various substrate concentrations in the perfusion medium. The model simulates gluconeogenesis in the liver perfused separately with lactate and pyruvate and the combination of these substrates with fatty acids (oleate). The model consists of key reactions representing gluconeogenesis, glycolysis, fatty acid metabolism, tricarboxylic acid cycle, oxidative phosphorylation, and ketogenesis. Michaelis-Menten-type kinetic expressions, with control by ATP/ADP, are used for many of the reactions. For key regulated reactions (fructose-1,6-bisphosphatase, phosphofructokinase, pyruvate carboxylase, pyruvate dehydrogenase complex, and pyruvate kinase), rate …
Bayesian Estimation Via Sequential Monte Carlo Sampling-Constrained Dynamic Systems, Lixin Lang, Wen-Shiang Chen, Bhavik R. Bakshi, Prem K. Goel, Sridhar Ungarala
Bayesian Estimation Via Sequential Monte Carlo Sampling-Constrained Dynamic Systems, Lixin Lang, Wen-Shiang Chen, Bhavik R. Bakshi, Prem K. Goel, Sridhar Ungarala
Chemical & Biomedical Engineering Faculty Publications
Nonlinear and non-Gaussian processes with constraints are commonly encountered in dynamic estimation problems. Methods for solving such problems either ignore the constraints or rely on crude approximations of the model or probability distributions. Such approximations may reduce the accuracy of the estimates since they often fail to capture the variety of probability distributions encountered in constrained linear and nonlinear dynamic systems. This article describes a practical approach that overcomes these shortcomings via a novel extension of sequential Monte Carlo (SMC) sampling or particle filtering. Inequality constraints are imposed by accept/reject steps in the algorithm. The proposed approach provides samples representing …
Analysis Of Thermal Effects In Infrared And Interference Microscopy: N-Butane-5a And Methanol-Ferrierite Systems, Lars Heinke, Christian Chmelik, Pavel Kortunov, Dhananjai B. Shah, S. Brandani, Douglas M. Ruthven, Jörg Kärger
Analysis Of Thermal Effects In Infrared And Interference Microscopy: N-Butane-5a And Methanol-Ferrierite Systems, Lars Heinke, Christian Chmelik, Pavel Kortunov, Dhananjai B. Shah, S. Brandani, Douglas M. Ruthven, Jörg Kärger
Chemical & Biomedical Engineering Faculty Publications
Recently, infrared and interference microscopy methods have been increasingly applied to measure internal concentration gradients and hence the uptake of different adsorbates in zeolite crystals. In contrast to conventional macroscopic batch uptake techniques, these microscopic/mesoscopic methods measure changes associated with single zeolite crystals. The analysis of data from these measurements to determine micropore diffusivities has been performed on the basis of the assumption that isothermal conditions prevail during both the adsorption and desorption experiments. This assumption is critically examined in this paper for the case of methanol diffusion in ferrierite crystals during adsorption and desorption to vacuum. It is shown …
Anwendung Von Interferenz- Und Ir-Mikroskopie Zur Charakterisierung Und Untersuchung Des Stofftransportes In Nanoporösen Materialien, Lars Heinke, Christian Chmelik, Pavel Kortunov, Sergey Vasenkov, Douglas M. Ruthven, Dhananjai B. Shah, Jörg Kärger
Anwendung Von Interferenz- Und Ir-Mikroskopie Zur Charakterisierung Und Untersuchung Des Stofftransportes In Nanoporösen Materialien, Lars Heinke, Christian Chmelik, Pavel Kortunov, Sergey Vasenkov, Douglas M. Ruthven, Dhananjai B. Shah, Jörg Kärger
Chemical & Biomedical Engineering Faculty Publications
Die Anwendung der Interferenz-Mikroskopie bedeutet einen entscheidenden Durchbruch in der Untersuchung des Stofftransports von Gastmolekülen in nanoporösen Wirtsmaterialien. Diese Technik ermöglicht die Beobachtung der zeitaufgelösten intrakristallinen Konzentrationsprofile, die durch eine Änderung des umgebenden Gasdruckes entstehen. Dieser Ansatz wurde zur Untersuchung von Adsorptions- und Desorptionsprozessen in verschiedenen Zeolithsystemen verwendet. Die Vorteile dieser Technik, vor allem wenn sie mit Infrarotabsorptionsmessungen kombiniert wird, werden an Hand der experimentellen Resultate des Methanol-in-Ferrierit-Systems illustriert.
A Distributed Model Of Carbohydrate Transport And Metabolism In The Liver During Rest And High-Intensity Exercise, E Chalhoub, L. Xie, V. Balasubramanian, Joanne M. Belovich
A Distributed Model Of Carbohydrate Transport And Metabolism In The Liver During Rest And High-Intensity Exercise, E Chalhoub, L. Xie, V. Balasubramanian, Joanne M. Belovich
Chemical & Biomedical Engineering Faculty Publications
A model of reaction and transport in the liver was developed that describes the metabolite concentration and reaction flux dynamics separately within the tissue and blood domains. The blood domain contains equations for convection, axial dispersion, and transport to the surrounding tissue; and the tissue domain consists of reactions representing key carbohydrate metabolic pathways. The model includes the metabolic heterogeneity of the liver by incorporating spatial variation of key enzymatic maximal activities. Simulation results of the overnight fasted, resting state agree closely with experimental values of overall glucose uptake and lactate output by the liver. The incorporation of zonation …
Noninvasive Quantification Of Fluid Mechanical Energy Losses In The Total Cavopulmonary Connection With Magnetic Resonance Phase Velocity Mapping, Anand K. Venkatachari, Sandra S. Halliburton, Randolph M. Setser, Richard D. White, George P. Chatzimavroudis
Noninvasive Quantification Of Fluid Mechanical Energy Losses In The Total Cavopulmonary Connection With Magnetic Resonance Phase Velocity Mapping, Anand K. Venkatachari, Sandra S. Halliburton, Randolph M. Setser, Richard D. White, George P. Chatzimavroudis
Chemical & Biomedical Engineering Faculty Publications
A major determinant of the success of surgical vascular modifications, such as the total cavopulmonary connection (TCPC), is the energetic efficiency that is assessed by calculating the mechanical energy loss of blood flow through the new connection. Currently, however, to determine the energy loss, invasive pressure measurements are necessary. Therefore, this study evaluated the feasibility of the viscous dissipation (VD) method, which has the potential to provide the energy loss without the need for invasive pressure measurements. Two experimental phantoms, a U-shaped tube and a glass TCPC, were scanned in a magnetic resonance (MR) imaging scanner and the images were …
Procedure To Quantify Biofilm Activity In Carriers Used In Wastewater Treatment Systems, James Bolton, Archana Tummala, Chirag Kapadia, Manoj Dandamudi, Joanne M. Belovich
Procedure To Quantify Biofilm Activity In Carriers Used In Wastewater Treatment Systems, James Bolton, Archana Tummala, Chirag Kapadia, Manoj Dandamudi, Joanne M. Belovich
Chemical & Biomedical Engineering Faculty Publications
A procedure is presented for evaluating and comparing the biological activity of biofilms attached to various biofilm carriers by measurement of the glucose consumption rate. This technique allows for the economical design and selection of small particulate biofilm carriers that will maximize substrate removal when used in industrial-scale fluidized bioreactors. Methods for ensuring reproducible results are described. To support the glucose consumption rate findings, biofilm dry weights were obtained at the conclusion of activity rate experiments, and scanning electron micrographs were taken to evaluate the presence of biofilm and to view surface characteristics. Fourteen different biofilm carriers were evaluated ranging …
Phosphate Reactions As Mechanisms Of High-Temperature Lubrication, Anitha Nagarajan, Carolina Garrido, Jorge E. Gatica, Wilfredo Morales
Phosphate Reactions As Mechanisms Of High-Temperature Lubrication, Anitha Nagarajan, Carolina Garrido, Jorge E. Gatica, Wilfredo Morales
Chemical & Biomedical Engineering Faculty Publications
One of the major problems preventing the operation of advanced gas turbine engines at higher temperatures is the inability of currently used liquid lubricants to survive at these higher temperatures under friction and wear conditions. Current state-of-the-art organic liquid lubricants rapidly degrade at temperatures above 300 °C; hence some other form of lubrication is necessary. Vapor-phase lubrication is a promising new technology for high-temperature lubrication. This lubrication method employs a liquid phosphate ester that is vaporized and delivered to bearings or gears; the vapor reacts with the metal surfaces, generating a solid lubricious film that has proven very stable at …
Reliable In-Plane Velocity Measurements With Magnetic Resonance Velocity Imaging, Haosen Zhang, Sandra S. Halliburton, Andan K. Venkatachari, Randolph M. Setser, Richard D. White, George P. Chatzimavroudis
Reliable In-Plane Velocity Measurements With Magnetic Resonance Velocity Imaging, Haosen Zhang, Sandra S. Halliburton, Andan K. Venkatachari, Randolph M. Setser, Richard D. White, George P. Chatzimavroudis
Chemical & Biomedical Engineering Faculty Publications
Magnetic resonance (MR) imaging is a well-known diagnostic imaging modality. In addition to its high-quality imaging capabilities, hydrogen-based MR can also provide non-invasively the velocity of water-based fluids in all three spatial directions (through-plane and in-plane) in an image. Many previous studies showed that MR velocity imaging can accurately measure the through-plane velocity. The aim of this study was to evaluate how reliable are the in-plane velocity measurements in an image. The axial velocity of water in horizontal tubes (inner diameter: 14.7–26.2 mm) was measured with segmented (fast) and non-segmented (slow) k-space MR velocity …
Adsorption Of Lactic Acid From Fermentation Broth And Aqueous Solutions On Zeolite Molecular Sieves, Isam H. Aljundi, Joanne M. Belovich, Orhan Talu
Adsorption Of Lactic Acid From Fermentation Broth And Aqueous Solutions On Zeolite Molecular Sieves, Isam H. Aljundi, Joanne M. Belovich, Orhan Talu
Chemical & Biomedical Engineering Faculty Publications
The recovery of lactic acid from fermentation broth and aqueous solutions was studied by adsorption on Silicalite molecular sieves. Batch experiments were used to measure the adsorption isotherms of the lactic acid on Silicalite. A linear correlation was found for both solutions. Silicalite showed a higher adsorptive capacity in the case of the aqueous solution than that of the fermentation broth. Henry’s constants were estimated as Formula Not Shown and Formula Not Shown for the aqueous and broth solutions, respectively. The effect of temperature on adsorption was also studied in batch mode. Henry’s constant dependency on …
Single-Collector Experiments And Modeling Of Acoustically Aided Mesh Filtration, Michael T. Grossner, Donald L. Feke, Joanne M. Belovich
Single-Collector Experiments And Modeling Of Acoustically Aided Mesh Filtration, Michael T. Grossner, Donald L. Feke, Joanne M. Belovich
Chemical & Biomedical Engineering Faculty Publications
A model for the motion of particles driven by acoustic and hydrodynamic effects in the vicinity of a cylindrical collector has been previously reported. This trajectory model was developed to describe the essential physics that underlies an ultrasonically aided particle-filtration process in which a porous mesh is used to capture particles two orders of magnitude smaller than the pore size. To validate this trajectory model, experiments were performed to elucidate the detailed motion of particles in the neighborhood of a single cylindrical collector. Images of 54-μm-diameter polystyrene particles in aqueous suspension responding to acoustic and hydrodynamic forces were …
Transport Analysis And Model For The Performance Of An Ultrasonically Enhanced Filtration Process, Michael T. Grossner, Joanne M. Belovich, Donald L. Feke
Transport Analysis And Model For The Performance Of An Ultrasonically Enhanced Filtration Process, Michael T. Grossner, Joanne M. Belovich, Donald L. Feke
Chemical & Biomedical Engineering Faculty Publications
This paper presents an analysis of a filtration technique that uses ultrasound to aid the collection of small particles (tens of microns in diameter) from suspension. In this method, particles are retained within a porous mesh that is subjected to a resonant ultrasonic field, even though the pore size of the mesh is two orders of magnitude greater than the particle diameter. The role of acoustic forces in driving the retention phenomena has previously been studied on a micro-scale, which included modeling and experimental verification of particle motion and trapping near a single element of the mesh. Here, we build …
Blood Flow Measurements With Magnetic Resonance Phase Velocity Mapping, George P. Chatzimavroudis
Blood Flow Measurements With Magnetic Resonance Phase Velocity Mapping, George P. Chatzimavroudis
Chemical & Biomedical Engineering Faculty Publications
Magnetic resonance (MR) phase velocity mapping (PVM) is a non-invasive technique that can measure the flow velocity in any spatial direction in an imaging slice. This technique has wide application in the clinical field in quantifying blood flow, as well as in non-biomedical areas. This review describes the value and/or potential of MR PVM as a diagnostic/monitoring technique in heart valve regurgitation and in the total cavo-pulmonary connection. A single slice placed in the aortic root can accurately quantify the aortic regurgitant volume. A multi-slice control volume method has high potential for the quantification of the mitral regurgitant volume. …
Segmentation Of Non-Viable Myocardium In Delayed Enhancement Magnetic Resonance Images, Arunark Kolipaka, George P. Chatzimavroudis, Richard D. White, Thomas P. O’Donnell, Randolph M. Setser
Segmentation Of Non-Viable Myocardium In Delayed Enhancement Magnetic Resonance Images, Arunark Kolipaka, George P. Chatzimavroudis, Richard D. White, Thomas P. O’Donnell, Randolph M. Setser
Chemical & Biomedical Engineering Faculty Publications
Purpose: To evaluate six algorithms for segmenting non-viable left ventricular (LV) myocardium in delayed enhancement (DE) magnetic resonance imaging (MRI). Methods: Twenty-three patients with known chronic ischemic heart disease underwent DE-MRI. DE images were first manually thresholded using an interactive region-filling tool to isolate non-viable myocardium. Then, six thresholding algorithms, based on the image intensity characteristics of either LV blood pool (BP), viable LV myocardium, or both, were applied to each image. For the Mean−2SDBP algorithm, thresholds were equal to the mean BP intensity minus twice its standard deviation. For the Mean+2SDSemi, Mean+3SDSemi, Mean+2SDAuto …
Fractionation Of Cell Mixtures Using Acoustic And Laminar Flow Fields, Manoj Kumar, Donald L. Feke, Joanne M. Belovich
Fractionation Of Cell Mixtures Using Acoustic And Laminar Flow Fields, Manoj Kumar, Donald L. Feke, Joanne M. Belovich
Chemical & Biomedical Engineering Faculty Publications
A fractionation method applicable to different populations of cells in a suspension is reported. The separation was accomplished by subjecting the suspension to a resonant ultrasonic field and a laminar flow field propagating in orthogonal directions within a thin, rectangular chamber. Steady, laminar flow transports the cell suspension along the chamber, while the ultrasonic field causes the suspended cells to migrate to the mid-plane of the chamber at rates related to their size and physical properties. A thin flow splitter positioned near the outlet divides the effluent cell suspension into two product streams, thereby allowing cells that respond faster to …
Relationship Between The Extent Of Non-Viable Myocardium And Regional Left Ventricular Function In Chronic Ischemic Heart Disease, Arunark Kolipaka, George P. Chatzimavroudis, Richard D. White, Michael L. Lieber, Randolph M. Setser
Relationship Between The Extent Of Non-Viable Myocardium And Regional Left Ventricular Function In Chronic Ischemic Heart Disease, Arunark Kolipaka, George P. Chatzimavroudis, Richard D. White, Michael L. Lieber, Randolph M. Setser
Chemical & Biomedical Engineering Faculty Publications
Purpose. To define the relationship between left ventricular (LV) regional contractile function and the extent of myocardial scar in patients with chronic ischemic heart disease and multi-vessel coronary artery disease. Methods. Twenty-three patients with chronic ischemic heart disease and 5 healthy volunteers underwent magnetic resonance imaging (MRI). In patients, the relative area ( Percent Scar) and transmural extent (Transmurality) of myocardial infarction were computed from short-axis delayed enhancement images. In each image, myocardial segments were categorized based on the extent of infarction they contained, with 6 categories each for Percent Scar and Transmurality: normal, from healthy volunteers; and 0%; 1–25%, …
Fast Measurements Of Flow Through Mitral Regurgitant Orifices With Magnetic Resonance Phase Velocity Mapping, Haosen Zhang, Sandra S. Halliburton, Richard D. White, George P. Chatzimavroudis
Fast Measurements Of Flow Through Mitral Regurgitant Orifices With Magnetic Resonance Phase Velocity Mapping, Haosen Zhang, Sandra S. Halliburton, Richard D. White, George P. Chatzimavroudis
Chemical & Biomedical Engineering Faculty Publications
Magnetic-resonance (MR) phase velocity mapping (PVM) shows promise in measuring the mitral regurgitant volume. However, in its conventional nonsegmented form, MR-PVM is slow and impractical for clinical use. The aim of this study was to evaluate the accuracy of rapid, segmented k-spaceMR-PVM in quantifying the mitral regurgitant flow through a control volume (CV) method. Two segmented MR-PVM schemes, one with seven (seg-7) and one with nine (seg-9) lines per segment, were evaluated in acrylic regurgitant mitral valve models under steady and pulsatile flow. A nonsegmented (nonseg) MR-PVM acquisition was also performed for reference. The segmented acquisitions were …
Mushy-Zone Rayleigh Number To Describe Macrosegregation And Channel Segregate Formation During Directional Solidification Of Metallic Alloys, Surendra N. Tewari, R. Tiwari, G. Magadi
Mushy-Zone Rayleigh Number To Describe Macrosegregation And Channel Segregate Formation During Directional Solidification Of Metallic Alloys, Surendra N. Tewari, R. Tiwari, G. Magadi
Chemical & Biomedical Engineering Faculty Publications
A recently defined mushy-zone Rayleigh number (R-aM) that includes side-branching contributions to the mushy-zone permeability has been examined for its correlation with the longitudinal macrosegregation and channel segregate formation. The Rayleigh number shows (1) a strong correlation between the extent of longitudinal macrosegregation and increase in the mushy-zone convection and (2) a good ability to predict the formation of channel segregates during directional solidification.
A Comparison Between Growth Morphology Of "Eutectic" Cells/Dendrites And Single-Phase Cells/Dendrites, Surendra N. Tewari, S. V. Raj, L. E. Locci
A Comparison Between Growth Morphology Of "Eutectic" Cells/Dendrites And Single-Phase Cells/Dendrites, Surendra N. Tewari, S. V. Raj, L. E. Locci
Chemical & Biomedical Engineering Faculty Publications
Directionally solidified (DS) intermetallic and ceramicbased eutectic alloys with an in-situ composite microstructure microstructure containing finely distributed, long aspect ratio, fiber, or plate reinforcements are being seriously examined for several advanced aero-propulsion applications. In designing these alloys, additional solutes need to be added to the base eutectic composition in order to improve their high temperature strength, and provide for adequate toughness and resistance to environmental degradation. Solute addition, however, promotes instability at the planar liquid-solid interface resulting in the formation of two-phase eutectic “colonies.”[1–4] Because morphology of eutectic colonies is very similar to the single-phase cells and dendrites, the stability …
Heat Transfer In A Thin Liquid Film In The Presence Of An Electric Field, Rama Subba Reddy Gorla, Jorge E. Gatica, Bahman Ghorashi, Pijarn Ineure, Larry W. Byrd
Heat Transfer In A Thin Liquid Film In The Presence Of An Electric Field, Rama Subba Reddy Gorla, Jorge E. Gatica, Bahman Ghorashi, Pijarn Ineure, Larry W. Byrd
Chemical & Biomedical Engineering Faculty Publications
Heat transfer enhancement in an evaporating thin liquid film utilizing a electric field under isothermal interfacial condition is presented. A new mathematical model subjected to van der Waals attractive forces, capillary pressure, and an electric field is developed to describe the heat transfer enhancement in the evaporating thin liquid film. The effect of the electrostatic field on the curvature of the thin film, evaporative flux, pressure gradient distribution, heat flux, and heat transfer coefficient in the thin film is presented. The results show that applying an electric field can enhance heat transfer in a thin liquid film significantly. in addition, …
Retention And Viability Characteristics Of Mammalian Cells In An Acoustically Driven Polymer Mesh, Zhaowei Wang, Paul Grabenstetter, Donald L. Feke, Joanne M. Belovich
Retention And Viability Characteristics Of Mammalian Cells In An Acoustically Driven Polymer Mesh, Zhaowei Wang, Paul Grabenstetter, Donald L. Feke, Joanne M. Belovich
Chemical & Biomedical Engineering Faculty Publications
A processing approach for the collection and retention of mammalian cells within a high porosity polyester mesh having millimeter-sized pores has been studied. Cell retention occurs via energizing the mesh with a low intensity, resonant acoustic field. The resulting acoustic field induces the interaction of cells with elements of the mesh or with each other and effectively prevents the entrainment of cells in the effluent stream. Experiments involving aqueous suspensions of polystyrene particles were used to provide benchmark data on the performance of the acoustic retention cell. Experiments using mouse hybridoma cells showed that retention densities of over 1.5 × …
Effect Of Crucible Diameter Reduction On The Convection, Macrosegregation, And Dendritic Morphology During Directional Solidification Of Pb-2.2 Wt Pct Sb Alloy, Jun Chen, Surendra N. Tewari, G. Magadi, H. C. Degroh Iii
Effect Of Crucible Diameter Reduction On The Convection, Macrosegregation, And Dendritic Morphology During Directional Solidification Of Pb-2.2 Wt Pct Sb Alloy, Jun Chen, Surendra N. Tewari, G. Magadi, H. C. Degroh Iii
Chemical & Biomedical Engineering Faculty Publications
The Pb-2.2 wt pct Sb alloy has been directionally solidified in 1, 2-, 3-, and 7-mm-diameter crucibles with planar and dendritic liquid-solid interface morphology. For plane front solidification, the experimentally observed macrosegregation along the solidified length follows the relationship proposed by Favier.([17,18]) Application of a 0.4 T transverse magnetic field has no effect on the extent of convection. Reducing the ampoule diameter appears to decrease the extent of convection. However, extensive convection is still present even in the 1-mm-diameter crucible. An extrapolation of the observed behavior indicates that nearly diffusive transport conditions require ampoules that are about 40 mum in …
A Mushy-Zone Rayleigh Number To Describe Interdendritic Convection During Directional Solidification Of Hypoeutectic Pb-Sb And Pb-Sn Alloys, Surendra N. Tewari, R. Tiwari
A Mushy-Zone Rayleigh Number To Describe Interdendritic Convection During Directional Solidification Of Hypoeutectic Pb-Sb And Pb-Sn Alloys, Surendra N. Tewari, R. Tiwari
Chemical & Biomedical Engineering Faculty Publications
Based on measurements of the specific dendrite surface area (S-nu), fraction of interdendritic liquid (phi), and primary dendrite spacing (lambda(1)) on transverse sections in a range of directionally solidified hypoeutectic Pb-Sb and Pb-Sn alloys that were grown at thermal gradients varying from 10 to 197 K cm(-1) and growth speeds ranging from 2 to 157 mum s(-1), it is observed that S-nu = lambda(1)(-1) S*(-0.33) (3.38 - 3.29 phi + 8.85 phi(2)), where S* = D-l G(eff)/V m(1) C-o (k - 1)/k, with D-l being the solutal diffusivity in the melt, G(eff) being the effective thermal gradient, V being the …
Directional Solidification And Convection In Small Diameter Crucibles, Jun Chen, P. K. Sung, D. R. Poirier, H. C. De Groh Iii
Directional Solidification And Convection In Small Diameter Crucibles, Jun Chen, P. K. Sung, D. R. Poirier, H. C. De Groh Iii
Chemical & Biomedical Engineering Faculty Publications
Pb–2.2 wt.% Sb alloy was directionally solidified in 1, 2, 3 and 7 mm diameter crucibles. Pb–Sb alloy presents a solutally unstable case. Under plane–front conditions, the resulting macrosegregation along the solidified length indicates that convection persists even in the 1 mm diameter crucible. Al–2 wt.% Cu alloy was directionally solidified because this alloy was expected to be stable with respect to convection. Nevertheless, the resulting macrosegregation pattern and the microstructure in solidified examples indicated the presence of convection. Simulations performed for both alloys show that convection persists for crucibles as small as 0.6 mm of diameter …