题目：A Force Element Theory with Application to Insect Flight (Part A)
Effective medium properties of periodic acoustic and elastic materials (Part B)
报告人： 张建成 教授
Professor, Institute of Applied Mechanics, National Taiwan University
报告内容摘要：
Part A: Bird or insect flight has been of great interest to general audience, not only to scientists. Numerous studies have been devoted to investigation in aerodynamics of insect wings. For example, here we examine the hovering flight. It is generally considered that the lift supporting the insect comes from the unsteadiness of the flight. However, unsteadiness may include many components: the motion of wing, vortex in the flow as well as the surface vorticity. The various contributions are now examined by the force element theory developed by the authors to gain more insight into the mechanism.
Part B: First, we consider effective mass densities of periodic acoustic media, which have been posed in different forms for composite solid-in-fluid materials in different physical dimensions. In this study, we derive a unified formula from homogenization analysis that explains the source of difference of effective mass densities. The analysis further shows anisotropy in mass density components for dimensions greater than one, yielding a direction-dependent effective mass density. Next, we examine effective modes of acoustic waves in periodic solid layers in ideal or viscous fluids. In particular, at the long-wavelength limit, a three-scale homogenization analysis is developed to derive the effective group velocities in analytical forms for the shear-vertical (SV) waves as well as for the longitudinal-shear-horizontal (P-SH) waves. It is found that propagating modes, i.e., modes with real group velocities, may be supported even if the fluid phase is viscous. A criterion for the existence of a vanishing effective viscosity is derived based on composite medium constants and the filling ratio of the fluid phase. The critical filling ratios at which an evanescent mode changes to a propagating mode are given for various solid-water systems.
主持人：佘振苏 教授 (Part A)
苏先樾 教授 (Part B)
时间：11月11日（周二）
下午3:00 (Part A) 4:00(Part B)
地点：力学楼434会议室
欢迎广大师生光临！要求力学系研究生必须参加。
联系人：刘才山 62756177
报告人简介：
張建成
(Chien-Cheng Chang)
Current Positions:
Research Fellow and Director, Division of Mechanics,
Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan, R.O.C.
Professor, Institute of Applied Mechanics, National Taiwan University (NTU or Taida),
Taipei 106, Taiwan, R.O.C.
Contact numbers and Email addresses:
Tel: 886-2-3366-5671 or 5672; Fax: 886-2-2362-5238
(Emails) mechang@gate.sinica.edu.tw; changcc@iam.ntu.edu.tw
Institute of Applied Mechanics, National Taiwan University,
No. 1, Roosevelt Road Section 4, Taipei City 106, Taiwan, R.O.C.
Education:
Prof. Chang attended National Taiwan University (Taipei, 1976-1980), receiving the Bachelor degree
in Chemical Engineering. In 1982, he was awarded a University Fellowship to do an advanced
graduate study at University of California, Berkeley and received the Ph.D. degree (Mathematics) in
1985.
Experience:
After obtaining his Ph.D. degree, Prof. Chang worked at the Lawrence Berkeley National Laboratory
as a Research Associate. In 1986, he went to Minneapolis, holding a Postdoctoral Fellowship at the
NSF-funded Institute for Mathematics and its Applications. Since 1987, he has been a faculty member
at the Institute of Applied Mechanics, National Taiwan University, Associate Professor (1987) and
Professor (1993), and has been appointed as a Distinguished Professor since 2007. From 1987 to
present, he had held visiting positions at University Erlangen-Nurnburg (1994-1995, the Humboldt
Foundation), University of California, Berkeley (Fall, 1997, NSC Visiting Program), Columbia
University (Fall, 1998), and HKUST (Hong Kong, Spring, 2003) under a Distinguished Visiting
Scholar Program. Since 2005, Prof. Chang has held a joint appointment in Academia Sinica on
mission to establish Division of Mechanics in the Research Center for Applied Sciences.
Fields of research interest:
Fluid mechanics, Micro & nano-fluidics, Biomechanics & Imaging,
Mechanics of microstructures, and Optics of photonic& plasmonic crystals
Prof. Chang has done research works in the fields of fluid mechanics and scientific computation,
specializing in vortex dynamics and turbulence, theory of forces in hydrodynamics/aerodynamics.
Recently, he has also done research works in biological modeling and imaging as well as in mechanics
of micro-scale composites and nano-optics/plasmonics for metallic/dielectric materials. Over the past
20 years, Prof. Chang has supervised 15 doctoral theses and more than 40 MS theses, all in the
National Taiwan University.