转发关于“浙江大学西湖机械论坛”的通知
张旭飞 (2015/10/5 21:25:50) 浏览:1403 评论:0
附录 详细介绍
Dr. Whitlow W.L Au
报告人简介:
Whitlow W. L. Au received his B.S. in Electrical Engineering from University of Hawaii in 1962; M.S. in Electrical Engineering in 1964 from Washington State University; and Ph.D. in Electrical Science in 1970 from Washington State University. Dr. Au is a leading expert in bioacoustics specializing in biosonar of odontocetes (dolphins, porpoises, and toothed whales). He is the author of the widely known book The Sonar of Dolphins (1993) and, with Mardi Hastings, Principles of Marine Bioacoustics (2008). The former book was evaluated in Nature 366, 376 (1993) that “... Whitlow Au has written a splendid book, which is likely to become a classic in its field, and of considerable interest well outside it.”, and in Science 260, 1672 (1993) that “Au’s book is an excellent synthesis of the mountain of work on dolphin sonar ...”. Dr. Au was honored as a Fellow of the Acoustical Society of America in 1990 and awarded the ASA’s first Silver Medal in Animal Bioacoustics in 1998. His current position is the Chief Scientist of the Marine Mammal Research Program of the Hawaii Institute of Marine Biology at the University of Hawaii.
报告题目：The best sonar system on this planet: the sonar of dolphins
Dolphins have very sophisticated short-range sonar that surpasses all technological sonar in its capabilities to perform complex target discrimination and recognition tasks. The system that the U.S. Navy has for detecting mines buried under ocean sediment is one that uses Atlantic bottlenose dolphins. However, close examination of the dolphin sonar system will reveal that the dolphin acoustic “hardware” is fairly ordinary and not very special. The transmitted signals have peak-to-peak amplitudes as high as 225 - 228 dB re 1 mPa, which translate to an rms value of approximately 210 - 213 dB. The transmit beamwidth is fairly broad at about 10o in both the horizontal and vertical planes and the receiving beamwidth is slightly broader by several degrees. The auditory filters are not very narrow with Q values of about 8.4. Despite these fairly ordinary features of the acoustic system, these animals still demonstrate very unusual and astonishing capabilities. The dolphin biosonar system will be discussed from the perspective of a technological sonar system consisting of a signal projection section including signal generation, propagation through the head and directivity index, a reception section including receiving sensitivity, directivity, and internal filtering process, and a signal processing section.
Some of the capabilities of the dolphin sonar system will be presented and the reasons for their keen sonar capabilities such as discriminating and recognizing different fish species, differences in wall thickness of metal cylinders and differences in the composition of metallic targets will be discussed. Important features of their sonar include the broadband click-like signals used, adaptive sonar search capabilities and large dynamic range of its auditory system.
Dr. Michael J. Buckingham
报告人简介:
Michael J. Buckingham is Distinguished Professor specializing in ocean acoustics at the Marine Physical Laboratory, Scripps Institution of Oceanography, University of California San Diego. He received a B.Sc. (Honours) in physics and a Ph.D. in solid-state physics from the University of Reading, U.K. Prior to joining Scripps, he was an Individual Merit Senior Principal Scientific Officer at the Royal Aerospace Establishment, U.K, during which time he served as the U.K. National Representative on the Scientific Committee of the Marine Science and Technology (MAST) Programme, Commission of European Communities, Brussels, Belgium. For two years, he was attached to the British Embassy as an exchange scientist at the Naval Research Laboratory, Washington, D. C. He has held Visiting Professor appointments in the Department of Ocean Engineering, Massachusetts Institute of Technology, and the Institute of Sound and Vibration Research, University of Southampton, U.K.; and he is currently a Visiting Professor at the National Key Laboratory of Science and Technology on Sonar, Hangzhou, China. He is a cofounder of the Acoustical Oceanography Technical Committee of the ASA, he recently served on the Executive Council of the ASA, and he is an Editor-in-Chief of the Journal of Computational Acoustics. He is a Fellow of the Acoustical Society of America, the Institute of Acoustics, and the Institute of Engineering and Technology. He was the recipient of the Clerk Maxwell Premium from the IERE, the A. B. Wood Medal from the Institute of Acoustics, and he has received a number of other awards for his research. He holds a private pilot certificate with instrument and glider ratings.
报告题目：Sound Waves and Shear Waves in Unconsolidated Marine Sediments
Unconsolidated marine sediments are saturated granular materials in which the grains are not bonded together but are held in contact either by gravity, in the case of coarser materials (sands), or by electrostatic forces in finer-grained media (muds and clays). Although the inter-particle forces differ between the coarse- and fine-grained sediments, the wave properties of these materials often exhibit similar features. For instance, all unconsolidated sediments support two types of wave, a longitudinal sound wave and a transverse shear wave. There is a growing body of evidence that, over an extended frequency range, the attenuation of both the sound wave and the shear wave varies approximately as the first power of frequency in coarse- and fine-grained materials. Thissuggests that the wave properties of marine sediments are determined by inter-granular interactions; but that the type of force holding the grains in contact, whether it be inertial or electrostatic, has little affect on the wave behavior of sediments. This reasoning provides the basis for a unified theory of wave propagation in marine sediments, which applies to a variety of sediment types ranging from coarse sands to fine silts and clays. The theory, known as the grain-shearing (GS) theory, relies primarily on the fact that the sediment grains move against one another as sound and shear waves propagate through the medium. The grain-shearing theory will be briefly reviewed and comparisons with extensive data sets will be presented. (Research supported by ONR.)
Dr. Andrew N. Norris
报告人简介:
Andrew Norris received his B.Sc. (1977) and M.Sc. (1978) in Mathematical Physics from University College, Dublin, Ireland, and Ph.D. (1981) in Engineering Sciences and Applied Mathematics from Northwestern University, U.S.A. Dr. Norris is an internationally recognized expert in modeling of acoustic and elastic wave phenomena. In his 35-year research career he has worked on topics ranging from ultrasonic nondestructive evaluation for detecting cracks, modeling of underground sound for geophysical prospecting, structural acoustics for naval applications, and consulting to industry on acoustics and structural dynamics. He enjoys tackling problems that combine physics, engineering science, applied mathematics and numerical simulation. His current interests are in developing fundamental models for mechanical metamaterials that exhibit extraordinary wave bearing properties. Dr. Norris joined Rutgers University in 1985 after post-doc positions at Northwestern University and at Exxon Research and Engineering Corporate Laboratories, NJ, and is currently Distinguished Professor of Mechanical and Aerospace Engineering in the School of Engineering. He has authored or co-authored more than 160 papers in refereed journals, is editor in chief of the journal Wave Motion, and a member of the board of Editors of several journals including the Journal of the Acoustical Society of America, Mathematics and Mechanics of Solids, and the Journal of Elasticity. Dr. Norris has received numerous honors and awards. The most significant ones include: Per Bruel Gold Medal for Noise Control and Acoustics, ASME, Nov. 2014; Fulbright Fellowship to visit France, 2013; Rayleigh Lecture Award, ASME, Nov. 2011; Visiting Scientist, Laboratoire de Mécanique Physique, Université Bordeaux 1, 2008-13; Fellow of the Institute of Mathematics and Applications, 2012; Fellow of the Acoustical Society of America, 1998; Visiting Fellowship, Royal Irish Academy, 1991; Royal Society Fellowship to visit universities in the United Kingdom, Feb. – March 1991; Walter P. Murphy Fellowship, Northwestern University, 1979; University Scholarships and Prizes, University College Dublin, 1976, 1977.
报告题目：Acoustic Metamaterials: Mathematical modeling and potential applications
The talk will outline some challenges in modeling and computation of acoustic metamaterials. Cloaking, for instance, requires that the metamaterial reduce the scattering cross-section of a given object. It should be fairly obvious that this is impossible to achieve at all frequencies. However, by choice of metamaterial once can obtain the effect at either a narrow band around a single frequency using resonances, or over a broadband in the quasistatic regime. We focus attention on the low frequency problem, and outline different strategies using either effective anisotropic density or anisotropic stiffness. Both approaches require material properties not observed in nature, hence metamaterials, and each has its advantages and disadvantages. We show that low frequency acoustic transparency can be obtained if and only if the metamaterial supports supersonic waves. It is interesting to note that low frequency transparency is not possible in electromagnetics (EM) because of the limit on the speed of light. This is an example of one of several fundemantal differences between acoustic and EM metamaterials, which imply quite different approaches to modeling. For instance, minimization of the total scattering cross-section of the low frequency cloak over all frequencies has a direct formulation in the time domain, one that does not exist for EM. The talk will discuss new modeling and computational issues that arise.
Dr. Martin Ochmann
报告人简介:
Martin Ochmann is Professor at Beuth Hochschule für Technik Berlin – University of Applied Sciences, Germany. He received a doctor degree (1985) and habilitation in Technical Acoustics (1990) at the Technical University of Berlin at the Institute of Technical Acoustics of Prof. Manfred Heckl. He is directing the researcher group Computational Acoustics (PG-CA) at Beuth Hochschule and several corresponding acoustical research projects. His research activities cover sound radiation from vibrating surfaces, fluid-structure interaction, acoustical scattering, numerical acoustics, boundary element methods, and duct acoustics. He has published more than 160 research papers in the field of Computational and Theoretical Acoustics. He was Chairman of the Technical Committee Physical Acoustics of the German Acoustical Society, DEGA and had organized eight annual workshops at the Physik-Zentrum in Bad Honnef, Germany. He was Associate Editor of the Journal of the Acoustical Society of America (2001-2005), and Chairman of the Technical Committee Computational Acoustics of the European Acoustical Association (2002-2013). As General Co-Chair he was responsible for hosting the German Annual Conference on Acoustics DEGA 2010 at Beuth Hochschule Berlin. After he had been Vice-President from 2010 to 2013, he is now President of the German Acoustical Society since July 2013.
报告题目：Acoustical Green's functions for half-space BEM
The lecture provides an overview of Green's function about impedance planes, which can be used as cornerstones for a boundary element method (BEM) in half-spaces. In general, the sound field caused by a monopole source above an impedance plane can be calculated by using a continuous superposition of point sources (superposition integral, also called complex equivalent source method CESM, see [1]). For pure absorbing or masslike impedances, these equivalent sources are located along a line in the mirror space below the plane. For a more general surface impedance, an application of Cauchy’s integral theorem shows that convergence can only be achieved by using complex locations for the image point sources.
This superposition integral is the starting point for the derivation of two further results:
1. The transient sound field caused by a Dirac delta impulse function above an infinite locally reacting plane can be calculated by applying the inverse Fourier transform of the corresponding half-space Green’s function in frequency domain. For a locally reacting plane with masslike character and also with pure absorbing behavior, it is possible to express the resulting impulse response in closed form. Such a result is surprising, since corresponding formulations in frequency domain are not available yet. By using a convolution technique, formulas for point sources with a general time dependency are derived. For special signals like an exponentially decaying time signal or a triangular shaped impulse, the resulting sound field can be presented in terms of elementary functions. The transient half-space Green’s function can be used for formulating an efficient boundary element formulation in time domain over the ground [2].
2. Assuming that a monopole source is moving with constant velocity at constant height above the impedance plane, the sound field can be expressed in analytical form by combining a Lorentz transformation with the superposition integral. For an absorbing impedance, the half-space Green’s function comprises a line of monopoles and of dipoles. The method of stationary phase leads to an asymptotic solution for the reflection coefficient which agrees with known results from literature [3].
[1] M. Ochmann, The complex equivalent source method for sound propagation over an impedance plane, J. Acoust. Soc. Am., 116(6), 3304-3311, 2004.
[2] M. Ochmann: Closed form solutions for the acoustical impulse response over a masslike or an absorbing plane: J. Acoust. Soc. Am., 129 (6), 3502-3512, 2011.
[3] M. Ochmann: Exact solutions for sound radiation from a moving monopole above an impedance plane, J. Acoust. Soc. Am., 133 (4), 1911-1921, 2013.
Dr. Sean F. Wu
报告人简介:
Sean F. Wu received his BSME from Zhejiang University (China) in 1982; MSME and Ph.D. from Georgia Institute of Technology in 1987. Dr. Wu joined the Department of Mechanical Engineering at Wayne State University (WSU) as Assistant Professor in 1988; promoted to Associate Professor in 1995 and Professor in 1999. He was voted unanimously to the Charles DeVlieg Professor of Mechanical Engineering from 2002 – 2005; and appointed by the Board of Governors to the rank of University Distinguished Professor in 2005 and holds this title to date. Dr. Wu’s areas of interest are acoustics, vibration, noise control, signal processing, and computational neurology. Dr. Wu is the inventor of the world famous three-dimensional acoustic field reconstruction with HELS, which brought about a brand new method and technology for near field acoustic holography. Dr. Wu holds the rank of Fellow in the Acoustical Society of America (ASA) and American Society of Mechanical Engineers (ASME). Dr. Wu has served as the Chair of the Structural Acoustics Technical Committee of the ASME Noise Control and Acoustics Division from 1995 – 2000; Vice Chair of the ASME Noise Control and Acoustics Division from 1999 – 2000; Chair of the ASME Noise Control and Acoustics Division from 2000 – 2001; Chair of the Per Bruel Gold Medal Nominating Committee of the ASME Noise Control and Acoustics Division from 2001 – 2002; Chair of the Technical Committee of the Structural Acoustics and Vibration of the ASA from 2006 – 2008. Dr. Wu is the Co-Founder of SenSound, LLC and served as the Vice President for Technology and the Chief Technology Officer from 2003 – 2008. Dr. Wu has served as an Editor for the Journal of Computational Acoustics (JCA) from 2002 – 2008, Co-Editor-in-Chief for JCA from 2008 to date, an Associate Editor for Journal of the Acoustical Society of America (JASA) since 2003, and an Editor for the Express Letters of JASA since 2012.
报告题目：The Future of Noise Diagnostics
In tackling challenging noise and vibration problems, people always feel the need to employ more sensors or develop better ones that may acquire the critical acoustic and vibration data accurately and efficiently, so that users can obtain a better understanding of the underlying mechanisms and device cost-effective solution strategies. Sensors are designed and built smaller and lighter, so that many of them may be applied simultaneously without substantially altering the characteristics of sound and vibration responses of target structures. It is not uncommon nowadays for engineers to apply hundreds of sensors simultaneously to analyze complex sound and vibration problems. For example, many original equipment manufacturers (OEMs) are opting to use hundreds of sensors to identify the root causes of structure-borne sound or aerodynamically generated noise problems. The present lecture aims to demonstrate that in addition to hardware development, there is another aspect, or more important one, which has often escaped people’s attention, namely, a better science and technology development that can address many challenging issues not attainable by relying on hardware alone. In fact, this lecture shows that one can utilize a better science to solve challenging noise and vibration problems with basic and very few sensors. Examples of using some of the latest developments in sciences and technologies to analyze aerodynamically generated automobile flow noise problems, and on-line product quality control testing using very few sensors are presented.
相关内容：