Oscar D. Crisalle
Ph.D.,1990,University of California-Santa Barbara
Professor
Ph : 352-392-5120
crisalle@che.ufl.edu
429 Chemical Engineering Building
 
Areas
Analysis and design of control systems
Real-time remote control over the Internet
Manufacture of photovoltaic devices
Control of fuel-cell powered systems
Analysis and Design of Control Systems
Keywords : Process Control

Models of processing systems only approximate physical reality. A major challenge addressed by our research is the design of controllers that, in spite of the uncertainty present in the model, can deliver high performance and also guarantee stable behavior. Such controllers are called robust. The effort focuses on the synthesis of robust controllers using methodologies such as pole-placement, predictive-control, and frequency-domain techniques based on the novel concept of a Nyquist Robust Stability Margin proposed by our group.

Since many processes of interest are inherently nonlinear, controllers designed using linear systems theory may experience severe performance degradation. Appropriate control designs that address relevant nonlinear features are needed. We are investigating the use of new methods for the analysis and design of adaptive, predictive, and sliding-mode control strategies, and the integration of the resulting techniques within the framework of computer aided tools.

We are developing technologies that enable the operation of control laboratory facilities in real time by students in geographically remote locations. The user accesses the laboratory using the Internet and a standard web browser, and can introduce manipulations and observe the response of the physical system. Applications of these research results include educational programs, as well as technology that allows the operation of complex chemical plants by personnel located in other parts of the world.

 
Control of Fuel-Cell Powered Systems
Keywords : Process Control, Energy
One of our research branches focuses on the technological challenges posed by systems powered by fuel cells. In particular, transportation vehicles with on-board hydrogen generation which require the deployment of effective multivariable and highly coupled control strategies that operate at different time scales. For example, the response time of the fuel cell is faster than that of an on-board methanol reformer, though it is slower than the response of the back-up battery systems in the vehicle. Multivariable predictive control techniques are being developed to support the key requirements of this technology, with an emphasis on fuel-cell-powered urban buses for passenger transportation.
 
Manufacture of Thin-Film Photovoltaic Devices
Keywords : Energy, Materials/Devices
Our team is investigating novel photo-absorber materials that we synthesize and using a plasma migration-enhanced epitaxial growth reactor capable of growing single-crystal thin films. In addition, photovoltaic buffer films are grown and optimized using chemical bath deposition methods, and transparent conducting oxides are deposited via magnetron sputtering methods, giving our group full capabilities for manufacturing and characterizing thin-film photovoltaic cells that achieve desirable solar-energy-to-electricity conversion efficiencies.
 
Recent Publications
1. Kim, W.K., Payzant, E.A., Kim, S., Speakman, S.A., Crisalle, O.D. and Anderson, T.J., “Reaction Kinetics of CuGaSe2 Formation from a GaSe/CuSe Bilayer Precursor Film,” Journal of Crystal Growth, 310(10) (2008) 2987.
2. Jung, K., Hayden, L.A., Crisalle, O.D., Eisenstadt, W.R., Fox, R.M., Navratil, P., Campbell, R.L., McCuen, C. and Lewis, M., “A New Characterization and Calibration Method for 3 dB-Coupled On-Wafer Measurements,” IEEE Transactions on Microwave Theory and Techniques, 56(5) (2008) 1193.
3 Braatz, R.D. and Crisalle, O.D., “Chemical Process Control,” International Journal of Robust and Nonlinear Control, 17(13) (2007) 1161.
4. Kim, W.K., Payzant, E.A., Anderson, T.J. and Crisalle, O.D., “In Situ Investigation of the Selenization Kinetics of Cu-Ga Precursors using Time-Resolved High-Temperature X-ray Diffraction,” Thin Solid Films, 515 (2007) 5837.
5. Al-Shamali, S.A. Ji, B., Crisalle, O.D., and Latchman, H.A., “The Nyquist Robust Sensitivity Margin for Uncertain Closed-Loop Systems,” International Journal of Robust and Nonlinear Control, 15, (2005) 619.