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413 results on '"POPESCU, Dumitru"'

110. Observer based control for a PV system modeled by a Fuzzy Takagi Sugeno model

Author

Miron Cristian, Aitouche Abdel, Popescu Dumitru, and Christov Nicolai

Subjects
Nonlinear system, Observer (quantum physics), Takagi sugeno, Computer Science::Systems and Control, Control theory, Control (management), Photovoltaic system, Control engineering, Computer Science::Artificial Intelligence, Fuzzy logic, Block (data storage), Mathematics, Compensation (engineering)
Abstract

This paper deals with a design of a Fuzzy Takagi Sugeno Observer for a class of nonlinear Photovoltaic (PV) systems. First, a nonlinear PV plant with a Takagi-Sugeno (TS) fuzzy model is presented. Then a model-based fuzzy observer design utilizing the concept of the Parallel Distributed Compensation (PDC) is used, in which observer gains are obtained by solving Linear Matrix Inequalities (LMIs). The control block based on MPPT algorithm will use in real-time the result provided by the nonlinear observer.

Published
2015

111. WATER QUALITY AND STRUCTURE OF FISH POPULATIONS IN DIFFERENT AREAS OF THE TIMIS RIVER.

Author

LAZU, Eduard Ştefan, BURA, Marian, BĂNAŢEAN-DUNEA, Ioan, POPESCU, Alin Cosmin, IANCU, Tiberiu, PEŢ, Ioan, ŢTEF, Lavinia, DRONCA, Dorel, NICULA, Marioara, AHMADI, Mirela, POPESCU, Dumitru, and PĂCALĂ, Nicolae

Subjects
WATER quality, COMPOSITION of water, FISH quality, FISH populations, RIVERS, SEBASTES marinus
Abstract

Researchers have been conducted on the Timis River, during which 6 fishing stations were established where 6 determinations of the chemical composition of water were made and the existing fish populations were evaluated. In the water of Timis River, from springs to the mouth, increased the 5 days-biochemical oxygen demand (BOD5 from 1.80 to 3.58 mg O2/l), also the accumulation of nitrates (from 1.82 to 2.77 mg/l), nitrites accumulation (from 0.015 to 0.045 mg/l), chlorides (from 2.50 to 8.51 mg/l) and hardness (from 1.27 to 5.52 dH°). In the Timiș river 36 fish species have been identified, which proves a good ecological status. Depending on the physic-chemical properties of the water, salmonids fish population was spread only in the mountain area, and cyprinids in hills and low land area. A large distribution was expressed in Barbel, Chub, Chased the Umber and Spirlin, which were found between the Teregova fishing station (mountain area), Lugoj stations (hilly area) and stations from Sag and Graniceri (lowlands area). In the warm waters of low lands were found: Bream, ide, pike-perk, sterlet, Verner, eels and Wheatear. [ABSTRACT FROM AUTHOR]

Published
2019

112. WATER QUALITY IN DIFFERENT AREAS OF TIMIS RIVER COURSE IN ROMANIA.

Author

LAZU, Eduard Ştefan, BURA, Marian, BĂNAŢEAN-DUNEA, Ioan, POPESCU, Alin Cosmin, IANCU, Tiberiu, PEŢ, Ioan, DRONCA, Dorel, PĂTRUICĂ, Silvia, SIMIZ, Eliza, NICULA, Marioara, DUMITRESCU, Gabi, AHMADI, Mirela, POPESCU, Dumitru, and PĂCALĂ, Nicolae

Subjects
WATER quality, COMPOSITION of water, WATER hardness, RIVERS
Abstract

Researchers have been conducted in the Timis River, which springs from the Semenic Mountains, in the western part of Romania. On its course on Romania's territory were established 6 sampling stations (Accumulation Three waters-Feneşti Confluence, Teregova, Lugoj-CFR Bridge, Lugoj-Timişana Confluence, Şag and Grăniceri) where analyzes were made of the chemical composition of the water. Analysis of the results showed an increase from upstream to downstream of 5 days-biochemical oxygen demand (B.O.D.5) (from 1.75 to 3.66 mg/l), also the accumulation of nitrates (from 1.53 to 3.08 mg/l), nitrites (from 0.01 to 0.10 mg/l), chloride (from 2.50 to 8.51 mg/l) and water hardness (from 1.12 to 6.02 dH°). [ABSTRACT FROM AUTHOR]

Published
2019

113. Optimisation en sciences de l'ingénieur. Méthodes exactes (Systèmes Automatisés, RTA)

Author

POPESCU Dumitru, BORNE Pierre, STEFANOIU Dan, FILIP Florin-Gheorghe, POPESCU Dumitru, BORNE Pierre, STEFANOIU Dan, and FILIP Florin-Gheorghe

Abstract

Optimisation en sciences de l'ingénieur présente les principales méthodes exactes d'optimisation statique et dynamique. Parmi les méthodes décrites, figurent : la programmation linéaire avec plusieurs implémentations et la programmation non linéaire, particulièrement détaillée compte tenu de la grande variété d'algorithmes existants ; la programmation dynamique avec divers exemples d'application ; les réseaux de Hopfield ; l'optimisation en identification des systèmes ; l'optimisation des systèmes dynamiques avec notamment l'application à la commande des processus, l'optimisation des systèmes de grandes dimensions et des systèmes d'information. Didactique, cet ouvrage propose des références permettant au lecteur d'approfondir les diverses méthodes traitées. Lorsque les algorithmes étudiés le permettent, sans trop agrandir les présentations, des exemples d'implémentation sont proposés.

Published
2013

134. Plants Growth on Different Fertilized Agricultural Land and Metal Bioavailability.

Author

Morariu, Florica Emilia, Peţ, Ioan, Mâşu, Smaranda, Neidoni, Dorian Gabriel, Horablaga, Adina, Ciobanu, Gheorghe, Ferencz, Gabriela Daniela, and Popescu, Dumitru

Subjects
PLANT growth, BIOAVAILABILITY, FARMS
Abstract

The study compares the amounts of Zea mays, grains, cobs and stalks, harvested on fertilized / unfertilized variant with different fertilizers: M-control, V1-fertilized with sewage sludge 50 t/ha + indigenous volcanic tuff, 5 t/ha, V2- fertilized with sewage sludge 50 t/ha, V3-fertilized with cattle manure, 50 t/ha. The amount of grains and cobs harvested from variant fertilized with cattle manure or sewage sludge mixed with indigenous volcanic tuff were similar. The amount of cobs and grains harvests from variant fertilized with sewage sludge mixed with indigenous volcanic tuff were higher between 15.1-17.5%, respectively 15.4-19.1% than those harvested from variant fertilized with sewage sludge. The indigenous volcanic tuff used as addition at sewage sludge was an important factor for the reduction of bioavailability of metals in the aerial tissues of the plant. The amount of toxic metals, Cd, Cr, Ni, Pb and Zn from the tissues of Zea mays plants was below the maximum limits allowed by the UE rules. [ABSTRACT FROM AUTHOR]

Published
2018

135. Chemical Reactor Control

Author

Popescu Dumitru and Azzouzi Messaouda

Subjects
Computer science, Nuclear engineering, Chemical reactor
Published
2012

136. Modeling and power regulation of horizontal variable speed wind turbines

Author

Pintea, Andreea, Wang, Haoping, Christov, Nicolai, Borne, Pierre, Popescu, Dumitru, Automatica si Controlul Proceselor si Calculatoarelor (ACPC), University Politehnica of Bucharest [Romania] (UPB), Modélisation, Information et Systèmes - UR UPJV 4290 (MIS), Université de Picardie Jules Verne (UPJV), Université de Lille, Sciences et Technologies, and Centrale Lille

Subjects
wind turbines, [INFO.INFO-AU]Computer Science [cs]/Automatic Control Engineering, linear quadratic control, nonlinear systems
Abstract

International audience; This paper deals with the development of a nonlinear model of a horizontal variable speed wind turbine, the obtaining of an appropriate linear model and the design and analysis of a linear quadratic controller with disturbance estimation. The optimisation criteria will have to define an acceptable compromise between the limitations of the power level in the above rated wind speeds and the maintenance of the aerodynamic properties of the rotor at high solicitations exerted by the wind. The main control objective is to provide an amount of energy that will not exceed the nominal parameters of the generator and thus avoid overheating.

Published
2011

137. Optimal control of variable speed wind turbines

Author

Pintea, Andreea, Christov, Nicolai, Borne, Pierre, Popescu, Dumitru, Badea, A., Automatica si Controlul Proceselor si Calculatoarelor (ACPC), University Politehnica of Bucharest [Romania] (UPB), Systèmes Non Linéaires et à Retards (SyNeR), Centre de Recherche en Informatique, Signal et Automatique de Lille - UMR 9189 (CRIStAL), Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Automatique, Génie Informatique et Signal (LAGIS), and Université de Lille, Sciences et Technologies-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
LQR, optimal control, [INFO.INFO-AU]Computer Science [cs]/Automatic Control Engineering, MED, Wind turbine
Abstract

International audience; This paper proposes a MIMO linear quadratic regulator (LQR) controller designed for a horizontal variable speed wind turbine with focus on the operating range referring to the above rated wind speeds. The operating conditions of wind turbines make them subject to fluctuating loads that create fatigue and lead to damage. Alleviating these loads would reduce the needed materials, and increase the lifespan and the quality of the produced energy. The optimality of the entire system is defined in relation with the trade-off between the wind energy conversion maximization and the minimization of the fatigue in the mechanical structure. The solution of a control using an LQR regulator is presented. The performances of the optimal control are assessed and discussed by means of a set of simulations.

Published
2011

138. H∞ controller design for variable speed wind turbines

Author

Pintea, Andreea, Christov, Nicolai, Borne, Pierre, Popescu, Dumitru, Automatica si Controlul Proceselor si Calculatoarelor (ACPC), University Politehnica of Bucharest [Romania] (UPB), Systèmes Non Linéaires et à Retards (SyNeR), Centre de Recherche en Informatique, Signal et Automatique de Lille - UMR 9189 (CRIStAL), Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Automatique, Génie Informatique et Signal (LAGIS), and Université de Lille, Sciences et Technologies-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
wind turbine, [INFO.INFO-AU]Computer Science [cs]/Automatic Control Engineering, load alleviation, h-infinity
Abstract

International audience; In this paper, the application of a robust multivariable control system designed for a horizontal variable speed wind turbine is discussed. The control problem presented and the background of the design method is given. A H∞ controller based of a linear model that reduces the mechanical fatigue of the turbine is designed. The alleviation of the mechanical loads could increase the lifespan and the quality of the produced energy. The H∞ theory is used to synthesize controllers achieving robust performance and stabilization and it has the main advantage that it does not make any assumptions about the noise and external disturbances that affect the system and it minimizes the worst case estimation error. The performances obtained through this control method are discussed and presented by means of a set of simulations.

Published
2011

139. DETERMINATION OF THE PARAMETERS CHARACTERIZING A CYCLE OF THE PULSATORY VESICLE

Author

Popescu, Dumitru and Popescu, AG

Subjects
Quantitative Biology::Subcellular Processes, Condensed Matter::Soft Condensed Matter, Physics::Biological Physics, pulsatory liposome, useful parameters, dynamical parameters
Abstract

In this paper, we have obtained the parameters characterizing the first cycle of the periodical working of a pulsatory vesicle. Under certain conditions, if a unilamellar lipid vesicle filled with aqueous solution of an osmotic substance is introduced into a hypotonic aqueous medium, it becomes a periodical dynamic system. Each cycle may be characterized by some dynamical parameters and useful quantities resulting by solving analytically the differential equation describing the swelling stage of the cycle and a numerical solution of a system of three differential equations which models the periodic stage of the cycle.

Published
2011

148. Modeling and control of wind turbines

Author

Pintea, Andreea, Popescu, Dumitru, Borne, Pierre, Laboratoire d'Automatique, Génie Informatique et Signal (LAGIS), Université de Lille, Sciences et Technologies-Centrale Lille-Centre National de la Recherche Scientifique (CNRS), Automatica si Controlul Proceselor si Calculatoarelor (ACPC), and University Politehnica of Bucharest [Romania] (UPB)

Subjects
pitch control, [INFO.INFO-AU]Computer Science [cs]/Automatic Control Engineering, turbine, Wind power, renewable energy
Abstract

6 pages; International audience; As the world is currently facing an energy and climate crisis, the development and utilization of alternative sources of energy has become an important challenge. From all types of renewable energy sources, wind turbines proved to be one of the cleanest and most reliable solutions for energy production. Wind energy conversion systems have in the last decades been subject of a strong interest as they could offer a viable source of electrical energy. This is why, it is important to focus on complex algorithms that meet with multiple objectives such as speed regulation, blade load and mode stabilization with simultaneously maximizing energy capture. This paper starts with a state of the art of wind turbines and their problematic and continues with the presentation of a polynomial control method designed for the third functioning zone of a wind turbine.

Published
2010

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