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USV Laboratory D 113 |
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The project entitled “Constructive
and disruptive effects of noise in nonlinear systems with hysteresis” is
aimed at providing a comprehensive analysis for stochastically driven
hysteretic systems from various areas of science. While the quasi-static
analysis of hysteretic systems has reached some degree of maturity, the
stochastic and dynamic analysis is currently under major developments. This research is supported by Marie
Curie International Reintegration Grant no. PIRG-02-GA-2007-224904 within
the 7th European Community Framework
Programme for period May 1st, 2008 – April 30th, 2012. These Marie Curie
Actions are individual grants which are aimed at researchers from the EU and
Associated States who have carried out research outside Europe for at least 5
years and who wish to return to Europe. The project is implemented at “Stefan
cel Mare” University of Suceava, Romania by Dr. Mihai Dimian, who had performed
research in United States of America for more than 5 years at University of
Maryland, College Park and Howard University, Washington DC where he held the
positions of Distinguished Graduate Research Assistant and Assistant
Professor, respectively. For the first reporting
period (01.05.2008-30.04.2010), the three
scientific objectives of the project were the development of methods for the
stochastic analysis of systems with hysteresis, the characterization of the
alternative solutions to the data storage technology, and description of
noise effects in photonic devices. In addition, the researcher aimed at
establishing a laboratory for research of hysteretic systems at the host
institution, as well as developing national and international collaborations in
the area of the project. In 2008, the researcher founded at Stefan cel Mare University of Suceava,
the Laboratory for Research of Hysteretic Systems (LRHS) as a component of
the Systems and Processes Control Center. The laboratory room has been
recently renovated and furnished by the University and has been made
available since the first day of my reintegration project. The main IT
infrastructure of RHS lab includes 14 computer workstations and 7 portable
computers with diverse simulation and data analysis software, while the
experimental research infrastructure includes Nanosurf Scanning Tunneling
Microscope, Signal and noise generators, Oscilloscopes and spectrum
analyzers, Antenna Training and Measurement System, Diode-Pumped Solid-State
Laser Kit, and Microwave Technology Training System. Most of the
infrastructure has been acquired since the researcher reintegration with the
financial support from the Stefan cel Mare University and Romanian Ministry
of Education, Research and Innovation. Regarding the scientific objectives, the researcher has developed in
collaboration with Dr. Petru Andrei from Florida State University a general
numerical approach to complex hysteretic systems with stochastic inputs,
which leads to a unitary framework for the analysis of various stochastic
aspects of hysteresis, including thermal relaxation, data collapse, field
cooling/zero field cooling, and noise passage. Various differential,
integral, and algebraic models of hysteresis were considered while the input processes
are generated from arbitrary given spectra. The resulting statistical
technique, based on Monte-Carlo simulations, has been successfully tested
against several analytical results available in the literature or derived by
the researcher based on the Preisach formalism of hysteresis and the theory
of stochastic processes on graphs. The developed method is suitable for the
analysis of a wide range of noise induced phenomena in nonlinear systems with
hysteresis from various areas of science and engineering, as well as for the
design and control of diverse magnetic, micro-electromechanical, electronics
and photonic devices with hysteresis. A special attention of this work has
been devoted to noise influence on current magnetic recording techniques, as
well as on several unconventional alternatives, such as spin polarized current assisted recording,
precessional switching, toggle switching where temperature-dependent
operating regions were obtained. Another important limitation addressed by this project is related to the
fact that noise is usually an internal feature of a physical system with
limited control from experimental point of view. His experimental approach
circumvents this difficulty by using electronic noise generators, which
provide a wide selection for noise characteristics, and a set of
parallel-connected Schmidt triggers, which play the role of hysteretic
rectangular loop operators. In the area of photonic devices, a special research interest of this
project has been devoted to the needs for interconnections between various
types of physical systems. Mechanical-electrical optoisolator transducers
have been developed by his group using Polaroid optocouplers to convert a
rotational and/or a translation movement into electrical signal. By using a
Schmitt trigger circuit, the Polaroid optocoupler has been transformed into a
mechanical-electrical transducer with hysteresis which has various potential
applications in the area of automation, communications and mechatronics. An
additional research focus in the area of photonics has been oriented towards
spin crossover (SCO) phenomena that occur in some transition metal complexes.
Atom-phonon coupling model has been used to explain, in a relatively simple
manner, the thermodynamic behavior of SCO materials upon application of
thermal noise or light. An intensive activity has been done during the first two years of the
project in order to develop national and international research
collaborations for the newly founded laboratory and to integrate the project
research in international research networks. At the international level, the
researcher had close and productive research collaborations with the groups
led by Prof. dr. Petru Andrei from Florida State University (U.S.A.), Prof.
dr. Jorge Linares from University of Versailles St. Quentin (France),
and Prof. dr. Lieven de Stryker from
KaHo University, Gent (Belgium), respectively. At the national level,
collaborations have been established with the groups led by Prof.dr.
Alexandru Stancu from “Al.I.Cuza” University, Iasi, and Prof.dr. Horia
Gavrila from Politehnica University, Bucharest. For the second reporting
period (May 1st, 2010 – April 30th, 2012),
the three scientific objectives of the project were the identification of
noise benefits in hysteretic systems, the description of noise influence on
the behavior of shape-memory alloys, and the description of the role of noise
in the neuron activity. In addition, the researcher aimed at stimulating
student interest in the research activities related to the project topics and
at forming human resources capable to develop research projects in this area
at the European standards. A special objective in the last part of the
project was to attract complementary resources for funding the project
research directions after the termination of this grant. While it is mostly experienced as a disruptive effect, noise can also
play a constructive role in hysteretic systems, activating a resonance
response. Recent studies on nonlinear systems proved that such phenomena are
quite common and their applications range from signal processing to climate
models. This phenomenon is generally known as coherence resonance, when is
solely induced by noise, and stochastic resonance, when an external
oscillatory signal is present. However, most of these systems can be
theoretically framed into two-state models or simple variants thereof. Dr.
Dimian has developed in collaboration with Dr. Petru Andrei from Florida
State University a general framework for the analysis of noise induced
phenomena in hysteretic systems with complex metastable state configuration
driven by arbitrary colored noise. It was proved that various complex
hysteretic systems can exhibit such noise induced resonance of the system
response. The quantities used in our study to characterize this behavior are
signal amplification and signal-to-noise ratio, which displays a maximum at
the resonant noise strength. The resulting statistical technique that
includes various algebraic, differential, and integral models of hysteresis
as well as arbitrary colored noise have been implemented in freely available
academic software. This general framework has also been used to study noise
influence on neuronal models. Exceeding this proposal objective, the
researcher has also started an interesting work on modeling neuron
stimulations by using rapidly changing magnetic field. Various hysteretic models have been used for modeling and simulating the
behavior of shape memory alloy with a special emphasize on designing phase
shifter for smart antenna. Several type of phase shifter have been considered
and used to design efficient linear and circular phased antenna arrays. Based
on the collaboration with Dr. Dimian on this topic, one of our PhD students
had successfully defended his thesis by designing, building, and testing
phased antenna arrays. Actually, Dr. Dimian has played an important role in
stimulating many of our students to do research. He was especially attentive
to the undergraduate and graduate students who joined his research group making
them capable of producing publishable research results as well as developing
research projects in this area at the European standards. Three of them have
successfully defended their doctoral theses and seven have received their
master degree. Most of group members have obtained various scholarships to
performed research in prestigious universities from Belgium, France, Italy
and Germany. His work with the students has also tried to meet the student
interests and abilities leading to a variety of topics from the proposal area
and even beyond, such as radio-frequency identification systems, smart
lighting systems or cyber-infrastructures development. A special effort has been devoted to attract funding for the continuation
of project research directions after the termination of this grant. Dr.
Dimian has been very successful in this endeavor being awarded one of the
very few national grants for a Young Research Team in value of 547000 lei
(approximately 125000 euro) with the project “Analysis of noise and fluctuations
induced phenomena in spintronic and semiconductor devices.” In conclusion, the activities have been performed
according to the proposed plan and the project objectives have been fully
achieved. The scientific results had been disseminated in seventeen
peer-reviewed publications, one book and in twenty three presentations at
international conferences, as well as through the project website
http://www.eed.usv.ro/condishyst . Other manuscripts featuring results
obtained in this project are currently in preparation, including a second
book. For his research activity, Dr. Dimian has received a prestigious award
in the competition “Romanian Researcher of the Year” organized by “Dinu
Patriciu” Foundation. Based on his
outstanding results Dr. Mihai Dimian has been appointed full professor with
tenure at “Stefan cel Mare” University of Suceava by the Romanian Minister of
Education, Youth and Sports, being one of the youngest full professors in
Romania. His recognition as one of the national leaders in engineering
research is also proven by his selection as a member of the Engineering
Commission of the National Research Council. By taken also into account that
Dr. Dimian has been elected and appointed on May 1st, 2012, as Vice-Rector
for Scientific Activities of “Stefan cel Mare” University of Suceava, it can
be concluded that he has fully and successfully reintegrated in the European
Union due to this Marie Curie grant. |