Conferences, Lectures, & Seminars
Events for April
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Microchannel Acoustophoresis in Biochips
Wed, Apr 07, 2010 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Henrik Bruus Professor Department of Micro- and NanotechnologyTechnical University of DenmarkDTU Bldg. 345east DK-2800 Kongens Lyngby Denmark ABSTRACT:Within the past five years there has been a significant increase in the number of novel applications of ultrasound standing waves for particle handling in microfluidic biochips. In spite of this growing interest, detailed measurements of the resonance line shapes are lacking. We present such measureÂments, published recently in Lab Chip 10, 563 (2010), based on tracking of individual polystyrene microbeads during acoustophoretic motion in straight water-filled microchannels in silicon/glass chips subject to piezo-induced ultrasonic pressure fields. From the measured line shapes we extract the corresponding Q-values and thus gain insight in the nature of the acoustic energy dissipation in such systems. The talk will end with examples of on-chip in vivo acoustophoresis of cells.
Location: Seaver Science Library, SSL Rm 150
Audiences: Everyone Is Invited
Contact: April Mundy
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Physical constraints of small-scale motility in fluids
Wed, Apr 14, 2010 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Eric LaugaAssistant ProfessorMechanical/Aerospace EngineeringUniversity of California, San DiegoABSTRACT:
Hydrodynamics plays a crucial role in many cellular processes. One example is the locomotion of cells such as bacteria, spermatozoa, and essentially half of the microorganisms on earth. These organisms typically possess flagella, slender whiplike appendages which are actuated in a periodic fashion in a fluid environment, thereby giving rise to propulsion. Motivated by recent experimental data, we consider in this talk three problems on the nonlinear hydrodynamics of swimming cells. We first address the observed flagellar synchronization between eukaryotic cells swimming in close proximity. We then discuss the locomotion of cells in complex (polymeric) fluids. We finally explain why cells swimming in confined environments are attracted to nearby boundaries.
Location: Seaver Science Library, Rm 150
Audiences: Everyone Is Invited
Contact: April Mundy
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On the Limiting Behavior of Regularizations of the Euler Equations with Vortex Sheet Initial Data
Wed, Apr 21, 2010 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Monika Nitsche Associate Professor Department of Mathematics University of New Mexico, Albuquerque ABSTRACT:
The vortex sheet is a mathematical model for a shear layer in which the layer is approximated by a surface. Vortex sheet evolution has been shown to approximate the motion of shear layers well, both in the case of free layers and of separated flows at sharp edges. Generally, the evolving sheets develop singularities in finite time. To approximate the fluid past this time, the motion is regularized and the sheet defined as the limit of zero regularization. However, besides weak existence results in special cases, very little is known about this limit. In particular, it is not known whether the limit is unique or whether it depends on the regularization. I will discuss several regularizing mechanisms, including physical ones such as fluid viscosity, and purely numerical ones such as the vortex blob and the Euler-alpha methods. I will show results for a model problem and discuss some of the unanswered questions of interest. --------------------------------------------------------------------------------Professor Nitsche received her PhD degree in 1992 from University of Michigan Ann Arbor under the guidance of Prof. Robert Krasny. She held various postdoctoral position (UC Boulder, IMA, OSU, Tufts) until she joined the faculty of the department of Mathematics at the University of New Mexico, Albuquerque in 1999. Her research interests lie in the numerical study of vortex flows and the development of numerical methods for such flows. She has also done some work on internal waves in density stratified flows.
Location: Seaver Science Library, Rm 150
Audiences: Everyone Is Invited
Contact: April Mundy
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Is the Current Dominant Aircraft Configuration Optimal
Fri, Apr 23, 2010 @ 02:00 PM - 03:00 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
By RJ HuyssenNorth West University,Pretoria, South AfricaDiomedes Inc.ABSTRACT:
Given that flight efficiency is governed by the laws of nature it is reasonable to expect that a dominance would emerge in the way that aircraft designers configure aircraft for various flight objectives. Such dominance has already established itself from the early years of human aviation and indeed prevails today. One might conclude that this configuration represents the optimal configuration for the majority of design objectives. Yet, this does not seem to be the case. Is there perhaps another aircraft configuration which could offer better flight efficiency to the majority of flight objectives? In the light of the adverse environmental impact of aviation we are obliged to meet our flight objectives in the most efficient way and should therefore consider this question very seriously.In this talk, we shall place the Exploitation of flight into the general context of Possibility, Opportunity and Discovery to explain the existence of the current dominate aircraft configuration. A careful rethinking of the engineering process of Design in relation to the natural process of Evolution then allows us to analyse the observed differences in the evolved dominant configuration and that engineered today. We may then answer the question as whether this difference should exist at all.
Location: Stauffer Lecture Hall, Room 100
Audiences: Everyone Is Invited
Contact: April Mundy
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Aerodynamics of Nano-Flyers
Wed, Apr 28, 2010 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Daniel WeihsDistinguished ProfessorFaculty of Aerospace Engineering and Autonomous Systems
ProgramTechnionIsrael Institute of TechnologyHaifa, 32000, IsraelABSTRACT:Some of the smallest flying insects have unique comb-like wings, with non-continuous surfaces. These have span lengths of mm size. In this talk, I will analyze the aerodynamics of such surfaces, showing how they can produce lift at Reynolds numbers of o(1). These findings are then used to build and test artificial nano-flyers of mm size wingspan and several generations of such nano-gliders and nano-flyers will be shown and future developments discussed.Distinguished Professor Daniel Weihs of the Technion Faculty of Aerospace Engineering holds the Richmond Chair in Life Sciences at the Technion and is Chairman of the Israel National Committee for Space Research and head of the Technion Autonomous Systems Program. He is a a foreign member of the U.S. National Academy of Engineering and Fellow of the American Physical Society.Prof. Weihs received his bachelor's, master's and doctoral degrees at Technion from 1964 to 1971. Prof. Weihs worked at the University of Cambridge, England 1971-1973, returned to the Technion as a senior lecturer in 1973; he was appointed full professor in 1983 and distinguished professor (one of only 5 at the Technion) in 2002. Part of the Technion leadership for many years, Prof. Weihs has served as Provost, Dean of the Graduate School and of the Faculty of Aerospace Engineering, Director of the Samuel Neaman Institute for Advanced Studies in Science and Technology and Director of the Asher Space Research Institute.Throughout his career, Prof. Weihs has consulted for the Israeli ministries of Defense, Internal Security, Commerce & Industry, Science, and for public and private organizations in Europe, the United States and Canada, including NASA, NOAA, IBM and Atlas-Copco. He has been on the board of firms such as Israel Aircraft Industries, Beth Shemesh Engines, Israel Limnological and Oceanographic Research Corp, and Teuza-Fairchild VC fund, and of Ben Gurion University and Holon Institute of Technology. He has been a member of the Steering Committee of the Israel Space Agency for 20 years and head of its Scientific Satellite Sub-Committee. He has published more than 140 scientific papers and one book, and has lectured throughout the world on subjects of biofluid dynamics, aerospace engineering and life sciences.
Location: Seaver Science Library, Room 150 (SSL 150)
Audiences: Everyone Is Invited
Contact: April Mundy