Conferences, Lectures, & Seminars
Events for March
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Control and Suppression of Interfacial Instabilities by Shear
Wed, Mar 03, 2010 @ 03:00 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
JOHN LAUFER LECTURE SERIESStephen H. Davis Walter P. Murphy Professor of Engineering Sciences
and Applied MathematicsandMcCormick School (Institute) Professor Engineering Sciences and Applied Mathematics
DepartmentRobert R. McCormick School of Engineering and
Applied ScienceNorthwestern University Evanston, IL 60208ABSTRACT: There has been recent work on the control of instabilities using feedback and control theory to at least delay instability. Here, we shall discuss an alternative in which imposed shear flows can delay or eliminate interfacial instabilities though the shear triggers others that are less 'harmful.' This will be illustrated by the suppression of Van der Waals rupture instability in ultra-thin liquid films. --------------------------------------------------------------------------------BIO:Stephen H. Davis received all his degrees at Rensselaer Polytechnic. He has been Research Mathematician at the RAND Corporation, Lecturer in Mathematics at Imperial College, London, and Assistant, Associate Professor and Full Professor of Mechanics at the Johns Hopkins University. He is Editor of the Journal of Fluid Mechanics and the Annual Review of Fluid Mechanics. He has authored 200 refereed technical papers in the fields of Fluid Mechanics and Materials Science and the book Theory of Solidification. He has twice been Chairman of the Division of Fluid Dynamics of the American Physical Society, is a Fellow of the American Physical Society, is a member of the National Academy of Sciences, the National Academy of Engineering, and the American Academy of Arts and Sciences, and was the 1994 recipient of the Fluid Dynamics Prize of the APS and the 2001 G. I. Taylor Medal of the Society of Engineering Science.
Location: Davidson Conference Center, (DCC) Board Room
Audiences: Everyone Is Invited
Contact: April Mundy
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New Synthesis and Sintering Methods in Materials Research
Wed, Mar 10, 2010 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Olivia A. Graeve Associate Professor Kazuo Inamori School of Engineering Alfred University2 Pine Street Alfred, NY 14802 ABSTRACT:This talk will present an overview of leading precipitation processes for the synthesis of nanostructured ceramic and metallic powders, with special emphasis placed on reverse micelle synthesis for the preparation of oxides and combustion synthesis for the preparation of borides. Specific examples will include the preparation of yttria-doped zirconia (Y-ZrO2) and lanthanum hexaboride (LaB6). The talk will also describe advanced sintering techniques for nanostructured materials. For the case of Y-ZrO2, the thermal stability of the synthesized particles will be described. Transmission electron microscopy and Williamson-Hall analysis from x-ray diffraction have shown that the crystallite size ranges from 5-50 nm. A detailed study on the level of agglomeration and the particle size of the nanopowders will be described and corroborated using dynamic light scattering. Reaction parameters such as precursor concentration, aging time, and water-to-surfactant ratio were varied to optimize the synthesis process. Some of the powders were subsequently sintered using spark plasma sintering (SPS). Dense compacts of >98% density were obtained in 20 minutes. The feasibility of preparing nanocrystalline LaB6 powders via a controlled combustion synthesis process will also be presented. These powders are extraordinarily strong electron emitters with applications in micro- and nano-satellite propulsions systems, where they can serve as substitutes for chemical propellants, such that the electrons being emitted by the material are the source of propulsion. The synthesis reaction for the preparation of the powders is described below. During this process, controlled amounts of lanthanum nitrate (oxidizer) and boron were reacted with carbohydrazide (fuel) in a muffle furnace at 320°C. As the reactants were heated, the oxidizer and fuel reacted to form a fine violet powder that contains both nanocrystalline LaB6 and unreacted boron. After synthesis, the unreacted boron was removed from the powders using a controlled acid wash. The resulting phase-pure and faceted LaB6 powders were then characterized using x-ray diffraction for phase purity and crystallite size, and scanning electron microscopy for particle morphology.
Location: Seaver Science Library, SSL Room 150
Audiences: Everyone Is Invited
Contact: April Mundy
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Electrospray and Its Applications
Wed, Mar 24, 2010 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Daren Chen Associate Professor Department of Energy, Environmental and Chemical Engineering Washington University in St. Louis St. Louis, MO 63130 ABSTRACT:Electrospray technique (i.e., electrohydrodynamic atomization), has been proposed for many modern applications. Examples of the applications include the surface coating, agricultural treatments, emulsion, fuel spraying, micro-or nano- encapsulation, ink-jet printers, colloid micro-thrusters, electrospray mass spectrometry (ES MS) for macromolecular detection in biochemical applications, monodisperse super micro-and nono- particle generation, enhancement of droplet mixing, targeted drug delivery by inhalation, power production, and electrospray gene transfection. Among all the operational modes involved in electrospray process the cone-jet mode has been investigated and applied for the majority of above-described applications. It is because of its capability to produce un-agglomerated, monodisperse particles in the sub-micrometer and nanometer diameter ranges. Among different setups, single-capillary electrospray systems were often used in various applications. However, limitation of single-capillary electrospray is encountered in modern electrospray applications, especially in the biomedical and pharmaceutical areas. Dual-capillary electrospray (ES) technique was thus proposed to overcome the limit of a single-capillary electrospray system, thereby broadening the applications of electrospray technique. In this presentation we will first review the electrospray history and its fundamental principles, then present its modern applications in biomedical and pharmaceutical areas.
Location: Seaver Science Library SSL, Room 150
Audiences: Everyone Is Invited
Contact: April Mundy
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Morphing Surfaces for Flow Control
Wed, Mar 31, 2010 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Beverley McKeon Assistant Professor of Aeronautics California Institute of Technology Pasadena, CA ABSTRACT:In this talk I will discuss opportunities for performance enhancement of aeronautical configurations using on-demand changes to surface morphology. It is well known that surface roughness can degrade the performance of aerodynamic bodies, for example by triggering early transition of laminar boundary layers or increasing skin friction drag in turbulent ones, but can we use this knowledge to our advantage? I will describe our work interrogating the response of different receptive flow configurations to this type of actuation, through experiments and computations, and demonstrating novel ways of reconfiguring modern materials to generate "morphing surfaces", or thin skins capable of undergoing dynamic changes in surface roughness in response to low power inputs. Can we actively optimize the dimples on a golf ball for maximum range or directional correction? Not yet. ... --------------------------------------------------------------------------------Beverley McKeon has been an Assistant Professor of Aeronautics in the Graduate Aerospace Laboratories at Caltech (GALCIT) since 2006. Her research interests include interdisciplinary approaches to manipulation of boundary layer flows using morphing surfaces and fundamental investigations of wall turbulence at high Reynolds number. She was the recipient of a Presidential Early Career award (PECASE) in 2009 and an NSF CAREER award in 2008. Prior to joining GALCIT, she was a Royal Society Dorothy Hodgkin Research Fellow and postdoc in the Department of Aeronautics at Imperial College London, after receiving a B.A. and M.Eng. from the University of Cambridge (1996) and Ph.D. in Mechanical and Aerospace Engineering from Princeton University (2003) under the guidance of Lex Smits.
Location: Seaver Science Library, SSL Rm 150
Audiences: Everyone Is Invited
Contact: April Mundy