Naredni sastanak Seminara mehanike održaće se u ponedeljak, 4. jula, u 13h na Matematičkom institutu SANU, sala 307 F.
Predavač: Prof. Subhash C. Sinha, Alumni Professor and Director of Nonlinear Systems Research Laboratory, Department of Mechanical Engineering, Auburn University, AL 36849, USA
Naslov predavanja: ANALYSIS AND CONTROL OF PARAMETRICALLY EXCITED SYSTEMS: A NEW APPROACH
Abstrakt: A general framework for the analysis and control of parametrically excited linear/nonlinear dynamical systems is presented. This class of problems appears in the modeling of rotorcraft blades in forward flight, asymmetric rotor-bearing systems, automotive components such as connecting rods, universal joints, asymmetric satellites, fluids under gravity modulations, etc. These dynamical systems are represented by a set of differential equations which contain time-periodic coefficients. First, an efficient computational scheme for the solution of linear problem is discussed through an application of Chebyshev polynomials. The idea is further developed to obtain the Lyapunov-Floquet (L-F) transformation associated with a linearized or a quasilinear time-periodic dynamical system. An application of L-F transformation yields equivalent systems whose linear parts are time-invariant. Therefore, the controls for all time-periodic linear systems can be designed using the standard time-invariant methods such as pole placement or optimal control theory. A symbolic control technique for Floquet multiplier placement is also suggested for linear time-periodic systems. In the case of nonlinear systems, a periodic orbit in the original coordinates has a fixed point representation after the L-F transformation. The local stability and bifurcation analyses are studied via time-dependent 'center manifold reduction' and 'normal form theory'. Results for fold, flip and secondary Hopf bifurcations are discussed. Bifurcation control and feedback linearization techniques for nonlinear time-periodic systems are also developed and applied to some typical problems. Further, the order reduction problem associated with free and forced parametrically excited large-scale nonlinear systems is also addressed using an invariant manifold approach. A methodology for reduced order controller design is also suggested. The practical significance of these approaches is demonstrated through simulations and experimental investigations of a number of mechanical systems. These include vibration control of a multi-bladed rotor, shafts supported by magnetic bearings, bifurcation analyses of a flexible slider crank mechanism and an autoparametric mechanical system, among others.
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Sastanak Seminara Geometrija, vizuelizacija i obrazovanje sa primenama održaće se u četvrtak, 30. juna 2011, od 17:15 u sali 301f Matematičkog instituta, Knez Mihajlova 36.
Predavač: Ivan Dimitrijević
Naslov predavanja: Ajnštajnova jednačina za gravitaciono polje i njena f(R) modifikacija, 2. deo
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Naredni sastanak CGTA seminara održaće se u utorak, 28. juna u 18h , u projektor sali na Matematičkom fakultetu
Kreda Lutalica: John Milnor kao dobitnik Abelove nagrade za 2011 godinu.
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Naredni sastanak Seminara za primenjenu matematiku održaće se u utorak, 28. juna 2011. u 14:15 h na Matematičkom institutu SANU, sala 301f, 3. sprat.
Predavači: Zoran Obradović, Director, Center for Data Analytics and Biomedical Informatics, Temple University, Philadelphia, USA
Naslov predavanja: SPATIO-TEMPORAL ANALYSIS OF MULTI-SOURCE DATA IN REMOTE SENSING
ABSTRACT: In this talk we will first present an overview of the results obtained over the last five years on our data mining based study aimed at understanding spatio-temporal distribution of aerosol by taking advantage of collected measurements from multiple ground and satellite-based sensors. In more details we will describe our recent method for information fusion and learning from data of varying quality based on Continuous Conditional Random Fields. Finally, we will discuss our effective method for learning from spatio-temporal data with a large fraction of missing values. This method that will be published at IJCAI 2011 outperformed alternatives when imputing 80% of nonrandom missing values in aerosol observations. Using such enlarged data we have developed a predictor of aerosol optical depth that was much more accurate than predictors based on alternative imputation methods when tested rigorously over entire continental US in year 2005.
SPEAKER INFORMATION:
Zoran Obradović, professor of Computer and Information Sciences and the director of the Center for Data Analytics and Biomedical Informatics at Temple University in Philadelphia is an internationally recognized leader in data mining and bioinformatics. He has published about 230 articles addressing data mining challenges in health informatics, climate and ecological management, the social sciences, and other domains. Obradovic was the program chair at six, track chair at seven and program committee member at about 40 international conferences on data mining. He currently serves as an editorial board member at seven journals and is the executive editor at the journal on Statistical Analysis and Data Mining which is the official publication of the American Statistical Association (ASA).
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U periodu 19-26. juna u Beogradu će boraviti prof Shahar Nevo sa Univerziteta Bar-Ilan iz Izraela.
Prof Nevo će održati predavanje pod naslovom "Q_\alpha-NORMALITY AND ENTIRE FUNCTIONS" u okviru Seminara Odeljenja za Matematiku u petak, 24.6. u 14 časova u sali 2 SANU.
Abstrakt predavanja može se preuzeti OVDE
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Sastanak Seminara Geometrija, vizuelizacija i obrazovanje sa primenama održaće se u četvrtak, 23. juna 2011, od 17:15 u sali 301f Matematičkog instituta, Knez Mihajlova 36.
Predavač: Jelena Grujić
Naslov predavanja: Ajnštajnova jednačina za gravitaciono polje i njena f(R) modifikacija, 1. deo
Apstrakt predavanja biće naknadno objavljen.
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Naredni sastanak Odeljenja za matematiku održaće se u sredu, 22. juna 2011. u 14 časova u sali 2 SANU.
Predavač: Sergej Melihov, Steklov institut Ruske Akademije nauka
Naslov predavanja: COMBINATORIAL METHODS IN EMBEDDING THEORY
Abstract: We offer the following explanation of the statement of the Kuratowski graph planarity criterion and of 6/7 of the statement of the Robertson-Seymour-Thomas intrinsic linking criterion. Let us call a cell complex 'dichotomial' if to every cell there corresponds a unique cell with the complementary set of vertices. Then every dichotomial cell complex is PL homeomorphic to a sphere; there exist precisely two 3-dimensional dichotomial cell complexes, and their 1-skeleta are K_5 and K_{3,3}; and precisely six 4-dimensional ones, and their 1-skeleta all but one graphs of the Petersen family.
In higher dimensions n>2, we observe that in order to characterize those compact n-polyhedra that embed in S^{2n} in terms of finitely many "prohibited minors", it suffices to establish finiteness of the list of all (n-1)-connected n-dimensional finite cell complexes that do not embed in S^{2n} yet all their proper subcomplexes and proper cell-like combinatorial quotients embed there. Our main result is that this list contains the n-skeleta of (2n+1)-dimensional dichotomial cell complexes. The 2-skeleta of 5-dimensional dichotomial cell complexes include (apart from the three joins of the i-skeleta of (2i+2)-simplices) at least ten non-simplicial complexes.
The talk is based on the preprint http://arxiv.org/abs/1103.5457
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U periodu od 19-26. juna, kao gost Matematičkog fakulteta i Matematičkog instituta SANU, u Beogradu će boraviti Sergej Melihov (Sergey Melikhov) sa instituta Steklov iz Moskve. Prof. Melihov je poznati ruski specijalist za topologiju i kombinatoriku. Posebno interesantan aspekt njegovog rada su radovi vezani za probleme ulaganja koji generališu klasične rezultate o ulaganjima grafova (knotless, linkless embeddings, itd.) i simplicijalnih kompleksa (van Kampen-ove opstrukcije), kao i primena tehnika iz diferencijalne topologije.
Prof. Melihov će održati jedno predavanje u sredu u okviru Odeljenja za matematiku (14:00, sala II SANU) namenjeno širem krugu slušalaca, kao i ciklus od dva predavanja u okviru CGTA seminara.
Utorak, 21. jun u 18h, projektor sala na Matematičkom fakultetu
Naslov predavanja: Van Kampen obstruction and its relatives, I
Četvrtak, 23. jun u 10h, sala 302, Matematičog instituta SANU
Naslov predvanja: Van Kampen obstruction and its relatives, II
Pozivamo sve ljubitelje topologije i njenih primena kao i studente matematike na ova interesantna predavanja.
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Naredni sastanak Seminara za primenjenu matematiku održaće se u utorak, 21. juna 2011. u 14:15 h na Matematičkom institutu SANU, sala 301f, 3. sprat.
Predavači: Milica i Milovan Matijević, Mineco Computers
Naslov predavanja: ISTRAŽIVAČKO-RAZVOJNI KAPACITETI U OBLASTI INFORMACIONO KOMUNIKACIONIH TEHNOLOGIJA U SRBIJI
Sadržaj: Evropska komisija - Direktorat za informaciono društvo (EC-DG INFSO) naručili su studiju istraživačno-razvojnih kapaciteta u IKT oblasti u Srbiji. Studija je istovremeno radjena kada i u drugim
novopridruženim članicama EU. Glavni cilj istraživanja bio je da se prikažu postojeći istrazivačko-razvojni kapaciteti u IKT oblasti, sa namerom da se Srbija što efikasnije uključi u evropski istraživački
prostor, pre svega u FP7-ICT program. Analiza je uključivala sledeće zadatke:
- Identifikaciju glavnih nosilaca istrazivačko-razvojne delatnosti, centara izvrsnosti i potencijalnih centara izvrsnosti i njihovih oblasti ekspertize. U tom kontekstu, napravljena je baza podataka "Ko je ko u IKT istraživanjima u Srbiji".
- Analizu mogućnosti i prepreka za uspešnije učešće i integraciju Srbije u FP7-ICT projekte. Predlog akcija na nacionalnom i evropskom nivou, koje treba preduzeti da bi se povećalo učešće srpskih istraživačkih organizacija u FP7-ICT projektima.
- Analizu tekuće i planirane infrastrukture za istraživanje i razvoj u IKT oblasti.
- Pregled studija i strateških dokumenata važnih za istraživanje i razvoj u IKT oblasti u Srbiji.
- Analizu dosadašnje uspešnosti srpskih istraživačkih organizacija u FP6 i FP7-ICT projektima.
Studija je finalizovana i prihvaćena od strane Evropske komisije, Ministarstva za nauku, kao i Ministarstva za telekomunikacije i informaciono društvo, kao tačna slika IKT kapaciteta u Srbiji, istovremeno prikazujući ključne organizacije sa njihovim odgovarajućim oblastima ekspertize.
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Sastanak Seminara Geometrija, vizuelizacija i obrazovanje sa primenama održaće se u četvrtak, 16. juna 2011, od 17:15 u sali 301f Matematičkog instituta, Knez Mihajlova 36.
Predavač: Djordje Kadijević
Naslov: The use of spreadsheets in the finance industry
Sadržaj: Spreadsheets are major tools in the finance industry. In order to find out how these tools are used, we examined recently published research papers and interviewed seven experienced bankers. This examination showed that spreadsheets may be used insufficiently, uncritically, and erroneously. By focusing on the quality of data and models (to be) exploited, this paper presents main details of this business-risky use of spreadsheets. Implications for vocational education are included.
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