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Time-Delayed Systems, Bridging Between Theory and Critical Applications


Prof. Nejat Olgac
Mechanical Engineering Department
University of Connecticut, Storrs, USA

Invitation to the lecture on Tuesday, December 5, 2017
at 14:00 (2 o'clock p.m.)
in the lecture room 3, in UTIA's building
Pod Vodárenskou věží 4, Prague 8


Practically motivated investigations have been conducted for over six decades in the machine tool’s regenerative chatter area bringing the time delayed dynamics into question. These efforts went on almost completely decoupled from the theoretical developments in mathematics, almost in the same chronological time span.

In this presentation we wish to take a journey bridging variety of application-based research studies to the theory. Some industrial problems that await solution and corresponding theoretical developments will be revisited. Missed opportunities of cross-breeding between the two groups of researchers and potentially fertile new venues are also reviewed. Interwoven nature of knowledge creation between the practice and theory will be displayed with video clips and numerical simulations.

Several focus points in the talk are as time permits:
  (a)   A concept of actively tuned vibration absorbers, the “Delayed Resonator”,
         which is inspired from machine tool chatter phenomenon
  (b)   Neutral class of Time-Delayed Systems (TDS) in practice
  (c)   Cluster Treatment of Characteristic Roots (CTCR) paradigm
         and its impact on single and multiple delay systems
  (d)   Chatter stabilization in Simultaneous Machining
         using “Delay Scheduling” method
  (e)   “Spectral Delay” and “Building Block” concepts for multiple
         and rationally independent delay cases
  (f)    Stability of multi-agent swarm control
  (g)   Thermo-acoustic Instability in combustion systems.


Nejat Olgac, Dr. Eng. Sci. Columbia Univ. 1976, M.Sc. Technical Univ. of Istanbul, Turkey 1972 (summa-cum-laude), both in Mechanical Engineering. He was engaged in manufacturing industry in Istanbul (1976-81). Since 1981 he has been a professor with the Mechanical Engineering Department of the University of Connecticut. His re-search interests are in robust nonlinear controls, active vibration absorption, time-delayed systems, micromanipulation in bio-engineering. He is the director of Advanced Laboratory for Robotics, Automation and Manufacturing (ALARM) at UConn.

Dr. Olgac holds four patents, three on the Delayed Resonator active vibration suppression technique (1995-1996-1999) and a fourth one on anti-chatter concepts in simultaneous machining (2011). He was Visiting Professor at INRIA (Sophia-Antipolis, France) 1988-89, SEW Eurodrive Fellow - Guest Professor at Technical Univ. of Munich, Germany in 1995-96, Visiting Professor at Harvard University 2002-03, and at Czech Tech. Univ. Prague 2017-18).

He served on the editorial board of the ASME Trans. of Dynamic Systems, Measurement and Control (1996-2004), and the guest editor of the Special Issue of JDSMC on Time Delayed Systems (June, 2003), is presently on the Editorial Boards of IEEE, Tran. Control System Technology, J. Vibration and Control, Int. J. of Mechatronics and Manufacturing Systems. He also served a member and later as the Chairman of the Executive Committee of the ASME Dynamic Systems and Control Division (2001-6). He was the General Chair of IFAC Time Delay Systems Workshop (TDS) 2012, and General Chairman of ASME Dynamic Systems and Controls Conference, DSCC 2013.He was a member of the ASME Systems and Design Group Operating Board, he also served on the A2C2 (American Automatic Control Council) Board of Directors 2013-16.

He is the recipient of a UCONN Research Excellence Award (2015) and ASME Distinguished Engineer of the Year, Hartford Chapter, CT (2015). Prof. Olgac is a member of the Connecticut Academy of Science and Engineering (CASE), Fellow of ASME and Senior Member of IEEE.

The lecture is public. Anyone who is interested is welcome.

01.08.2018 - 13:08