Department of
Automatic Control and Systems Engineering

Română (Romanian)

Department presentations

Department presentations:

 

  • Scientific seminary presentation – 8 December 2016:
    • author: Tudor Corneliu Ionescu
    • title: Families of moment matching-based reduced order models for linear descriptor systems
    • abstract:In this work a moment-matching procedure for descriptor systems is presented. Based on a time-domain notion
      of moments, parametrized families of reduced order models matching the moments of the original system are derived. An example of exploiting the flexibility of choosing the free matrix parameters is demonstrated by achieving two-sided moment matching, i. e., obtaining reduced order models of order matching 2 moments. In this context, a connection with the Loewner framework is shown which is a special case of the framework presented herein.
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  • Scientific seminary presentation – 8 December 2016:
    • author: Ionela Prodan
    • title: Power balancing in a DC microgrid elevator system through constrained optimization
    • abstract:This work consisders the problem of power balancing in a DC microgrid. A PH (port Hamiltonian) formalism is used to describe the systems components and interconnections. Energy and power conervation are kept for the discretized model. An economic model predictive controller is used for scheduling the microgrid power management. The proposed approach is validated through simulation
      results on a particular DC microgrid elevator system.
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  • PhD thesis presentation – 29 October 2016:
    • author: Teodor Cioaca
    • title: Mixed wavelet and nonlinear mean shift filters for large data
    • abstract: Graph-based wavelet lifting scheme designs were explored and implemented for data samples describing terrain patches with additional attributes. Such techniques can prove useful for accelerating specific filtering methods that cannot directly be applied to very dense and large models. We propose/exemplify such an approach by coupling a spatial domain scheme with a non-linear mean shift algorithm that works directly on the lowest resolution model of the multiresolution representation of the given input.
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  • Scientific seminary presentation – 20 October 2016:
    • author: Janetta Culita
    • title: Modelarea si identificarea unei instalatii hidraulice cu doua rezervoare
    • abstract:
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  • Scientific seminary presentation – 12 May 2016:
    • author: Catalin Petrescu
    • title: Utilizarea regimului discontinuu de conductie in invertoarele conectate la retea
    • abstract: Invertoarele conectate la retea sint dispozitive care transforma curentul continuu (generat de surse de energie regenerabila) in curent alternativ care este introdus in reteaua electrica. Functionarea acestor invertoare presupune controlul curentului introdus in retea care este un semnal de tip armonic. Structurile clasice de invertoare functioneaza ca surse de tensiune controlata. Prin conectarea acestora la retea se realizeaza o punere in paralel a doua surse de tensiune (invertor si retea) prin intermediul unui filtru de tip trece-jos care la frecventa retelei prezinta o impedanta redusa.

      Din acest motiv, curentul introdus in retea este puternic dependent atit de valoarea instantanee a tensiunii retelei cit si de comanda generata de regulatorul de curent. Practic, sistemul este extrem de sensibil la perturbatiile existente in tensiunea retelei ceea ce face dificil controlul curentului.

      Pentru imbunatatirea performantelor propunem o noua schema de comanda a invertoarelor care transforma invertorul intr-o sursa de putere controlata reducind astfel sensibilitatea curentului introdus in retea atit la perturbatii cit si la modificarile comenzii.

      Schema se bazeaza pe echivalarea invertorului prin doua convertoare de curent continuu si fortarea acestora sa functioneze in regim  discontinuu de conductie.

      Acest mod de functionare este caracterizat insa de un model neliniar, iar metoda de control pe care o propunem se bazeaza pe compensarea acestei neliniaritati folosind valorile masurate ale principalilor parametri electrici.

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  • Scientific seminary presentation – 5 May 2016:
    • author: Florin Stoican
    • title: Explicit mRPI sests for dynamics with zonotopic disturbances (english)
    • abstract: This presentation provides a robust positive invariance (RPI) outer approximation of the minimal RPI (mRPI) set associated to linear dynamics with zonotopic disturbances.
      We prove that the candidate sets considered are either RPI or become so with a scaling factor. The results are based on the concomitant computation of extremal points and their extremal hyperplanes. Lastly, we show that successive RPI representations become monotonically “tighter” as their complexity increases.
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  • PhD thesis presentation – 14 April 2016:
    • author: Cristian Flutur
    • title: Tehnici de factorizare pentru reglarea sistemelor generalizate (romanian)
    • abstract: Squaring down with simultaneous zeros cancellation by series compensation of a general (possibly polynomial or improper) linear system is investigated. All static and dynamical compensators that spotlight minimal McMillan degree are parameterized. This general result is particularized to get compensators that preserve the L2 or L∞ norm of the original system, either in continuous or discretetime. All results are completely general, numerically sound, and based on general realizations allowing for poles at infinity.
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  • Scientific seminary presentation – 31 March 2016:
    • author: Tudor Corneliu Ionescu
    • title: Aproximari precise ale sistemelor liniare – potrivirea bilaterala a momentelor in domeniul timp (romanian)
    • abstract: In aceasta lucrare este studiata problema aproximarilor precise ale sistemelor liniare prin metoda potrivirii momentelor in domeniul timp, o problema deosebit de dificila. Mai precis, este calculat modelul de ordinul n care aproximeaza sistemul dat prin potrivirea a 2n momente in doua seturi distincte de puncte de interpolare. Aceasta metoda o numim potrivirea bilaterala a momentelor. Atunci cand seturile de puncte de interpolare sunt identice, tratam problema potrivirii momentelor sistemului si ale derivatei sale in punctele de interpolare date. Solutia acestei probleme sta la baza conditiilor necesare de ordinul intai ale problemei de aproximare optima in norma 2 a sistemelor liniare. Calculul celor doua modele propuse se face prin selectarea corespunzartoare a parametrilor modelelor din familiile de modele care potrivesc n momente ale sistemului. Practic cele doua modele (unice) se gasesc la intersectia celor doua familii. Expunerea se va incheia cu un exemplu ilustrativ.
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  • Habilitation thesis presentation – 17 March 2016:
    • author: Monica Dragoicea
    • title: Advances in Service Systems Engineering: a Modelling and Simulation Approach
    • abstract: The new research domain presented in this thesis is strongly related to the application  of Service Science body of knowledge as high level design guidelines in the development of improved smart services with IT support. Actually, the thesis describes an exploration towards the usability evaluation of Service Science principles and their transposition into design guidelines of complex service systems of the future. It reinforces the interest to evolve the exploration perspective towards a methodology more specifically targeted to Service Systems Engineering, taking into considerations socio-technical aspects. Exploration in Service Science is considered today as a good opportunity for researchers and practitioners to advance their research.
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  • Scientific seminary presentation – 25 February 2016:
    • author: Ion Necoara
    • title: Convergenta liniara a algoritmilor de ordinul I pentru probleme ne-tari convexe (romanian)
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