Feb 25: CEAS Seminar – Passivity-based control of physical systems

Monday, February 25, 2013
11:15 a.m., NC 3212

Dr. Romeo Ortega
Laboratoire de Signaux et Systemes (SUPELEC)
Paris, France

– Abstract –

Energy is one of the fundamental concepts in science and engineering practice, where it is common to view dynamical systems as energy-transformation devices.  This perspective is particularly useful in studying complex nonlinear hybrid systems by decomposing them into simpler subsystems which, upon interconnection, add up their energies to determine the full system’s behavior. The action of a controller may be also understood in energy terms as another dynamical system -typically implemented in a computer- interconnected with the process to modify its behavior.  The control problem can then be recast as finding a dynamical system and an interconnection pattern such that the overall energy function takes the desired form. This “energy shaping” approach is the essence of the controller design technique -known as passivity based control (PBC)- that is introduced in this seminar. Our objectives in this seminar are threefold. First, to call attention to the fact that PBC hinges on the fundamental (and universal) property of energy conservation, hence is (in principle) applicable to all physical systems. Second, to provide the basic tools for its utilization on mechanical, electrical and electromechanical systems.  Third, to illustrate with some modern control applications how the use of energy concepts in PBC theory fosters collaboration with specialists from other disciplines, making the incorporation of process prior knowledge more systematic and providing a lingua franca for communication.



Romeo Ortega was born in Mexico. He obtained his BSc in Electrical and Mechanical Engineering from the National University of Mexico, Master of Engineering from Polytechnical Institute of Leningrad, USSR, and the Docteur D’Etat from the Politechnical Institute of Grenoble, France in 1974, 1978 and 1984, respectively. He then joined the National University of Mexico, where he worked until 1989. He was a Visiting Professor at the University of Illinois in 1987-88 and at the McGill University in 1991-1992, and a Fellow of the Japan Society for Promotion of Science in 1990-1991. He has been a member of the French National Researcher Council (CNRS) since June 1992. Currently he is in the Laboratoire de Signaux et Systemes (SUPELEC) in Paris. His research interests are in the fields of nonlinear and adaptive control, with special emphasis on applications. Dr. Ortega has published three books and more than 200 scientific papers in international journals, with an h-index of 51. He has supervised more than 30 PhD thesis. He is a Fellow Member of the IEEE since 1999 and has served as chairman in several IFAC and IEEE committees and editorial boards.

Feb 18: CEAS Seminar—The role of nutrient levels and algae on DBP formation in Colorado watersheds: Implications for source water quality management

College of Engineering and Applied Science
Spring 2013 Seminar Series


Monday, February 18, 2013
11:15 a.m., NC 3212

“The role of nutrient levels and algae on DBP formation in Colorado watersheds:  Implications for source water quality management”

Fernando L. Rosario-Ortiz
Assistant Professor
Department of Civil, Environmental and Architectural Engineering
University of Colorado, Boulder
Boulder, CO 80309


Drinking water utilities face the challenge of meeting advancing disinfection byproduct (DBP) regulations in order to provide safe drinking water to the public.  In addition to evolving treatment requirements, changes in source water quality are also occurring due to both anthropogenic and climatic influences.  The formation of DBPs from the reaction between dissolved organic matter (DOM) and chlorine depends on chemical properties of source water DOM.  The balance of DOM in water bodies is impacted by both terrestrial sources and autochthonous processes, including algal growth, which can alter the chemical reactivity of DOM. For water utilities that must meet stringent DBP regulations, a basic understanding of source water quality and how it relates to DBP precursor material is an important task. In this presentation, results from a study of utilities and reservoirs sampled throughout the state of Colorado during the summer and fall of 2010 will be discussed.  A total of 300 samples were collected and analyzed from 40 lakes and reservoirs, which were sampled multiple times at different depths. Results include correlations between lake characteristics, nutrients, Chlorophyll a, and DOM properties as they all relate to DBP formation. Overall, this research will aid in understanding the chain of source water quality relationships that correspond to DBP formation.


Dr. Fernando Rosario-Ortiz is an assistant professor of Environmental Engineering at the University of Colorado in Boulder. Dr. Rosario received his BS and MS in Chemistry from the University of Puerto Rico and the California Institute of Technology. He received his doctoral degree from UCLA in environmental science and engineering. He spent four years at the Southern Nevada Water Authority, where he worked with projects related to advanced treatment and organic contaminants. In 2008 he joined the University of Colorado, Boulder. His current research focuses on advanced oxidation processes, characterization of organic matter in watersheds, formation of disinfection byproducts and the fate of organic contaminants in natural environments.