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Pernik, Bulgaria
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Ivanova J.,European Polytechnical University | Petrova T.,European Polytechnical University | Petrova T.,Bulgarian Academy of Science | Kirilova E.,Bulgarian Academy of Science | Becker W.,TU Darmstadt
Engineering Transactions | Year: 2017

A one-dimensional shear-lag model was developed to study the high frequency, dynamic, time-harmonic mechanical behavior of the overlap zone of a piezoelastic patch attached to an elastic host layer and subjected to electric, temperature and moisture excitation. It was interesting to see that the change of the geometry of the overlap zone leads to different solutions after some frequency, which is responsible for different dynamic behavior of the considered structure. Furthermore, the model was involved in an optimization framework (genetic algorithm-GA) in order to find the optimal values of the model parameters of the patch/layer configuration. © 2017, Polish Academy of Sciences. All rights reserved.


Milenov T.I.,Bulgarian Academy of Science | Milenov T.I.,European Polytechnical University | Rafailov P.M.,Bulgarian Academy of Science | Thomsen C.,TU Berlin | And 4 more authors.
Optical Materials | Year: 2011

Crystals of BSO doped with Se in two different concentrations (BSO:Se(I) and BSO:Se(II)) were grown by the Czochralski method. It is established that doping with Se is accompanied with preferential absorption of Fe from the melt. According to the in-depth chemical analysis, it is assumed that the doping Se ions enter the tetrahedral positions by means of the substitution of 3Si 4+ by (Se6++ 2Fe3+) ions. The measured absorption spectrum of the low-concentration Se-doped crystal (BSO:Se(I)) confirms such a conclusion as the absorption coefficient is increased in a broad spectral interval (1.4-3.1 eV) - an effect typical for all Fe-doped Bi 12SiO20 crystals. The polarized Raman spectra of BSO:SeI show that the doping-induced lattice distortions are small. The IR spectrum of the BSO:SeI crystal yields indications for local lowering of the symmetry of the Fe-occupied tetrahedral positions. Doping with Se at high concentration (BSO:Se(II)) leads to occasional second phase inclusions and to a downshift of practically all modes in the Raman spectrum by 2-5.5 cm-1. It is concluded that the doping with Se at high concentrations follows the same mechanism as that at low concentrations but the introduced lattice distortions are more significant, and lead to an enlargement of the unit cell while preserving the overall cubic symmetry. © 2011 Elsevier B.V. All rights reserved.


Dezert J.,The French Aerospace Laboratory | Tchamova A.,Bulgarian Academy of Science | Konstantinova P.,European Polytechnical University
Cybernetics and Information Technologies | Year: 2015

The main purpose of this paper is to apply and to test the performance of a new method, based on belief functions, proposed by Dezert et al. in order to evaluate the quality of the individual association pairings provided in the optimal data association solution for improving the performances of multisensor-multitarget tracking systems. The advantages of its implementation in an illustrative realistic surveillance context, when some of the association decisions are unreliable and doubtful and lead to potentially critical mistake, are discussed. A comparison with the results obtained on the base of Generalized Data Association is made.


Chivarov N.,European Polytechnical University | Chikurtev D.,United Information Technologies | Yovchev K.,Code Assistance | Shivarov S.,ISER BAS
IFAC-PapersOnLine | Year: 2015

This abstract describes briefly how mobile robot assistant system for disabled persons can be cost-effective. This is done by using a widely available on the market robot parts and a web based user interface. So this system can easily be controlled even over the Internet. To be a user-friendly the robot firmware and software implements various control algorithms - like PID based motor control and collision avoidance. This results in achieving a very smooth and precise movement and a control tolerant to operator's mistakes. Different methods for sending movement commands to the mobile robot system are proposed and evaluated. The robot will be able to remind disabled persons to take medications, it will serve pre-prepared food and drinks, will turn on/off electronic devices, will alert when his/her health is getting worse and will connect to his physician, relatives or with the emergency services. © 2015, IFFCA (Internaitional Fedreation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.


Budakova D.,Technical University of Sofia | Dakovski L.,European Polytechnical University
ICAART 2012 - Proceedings of the 4th International Conference on Agents and Artificial Intelligence | Year: 2012

This paper investigates the social behaviour of an intelligent virtual agent (IVA) with PRE-ThINK architecture with the help of typical working student's life scenario modeling. The program system and the PRE-ThINK architecture, adapted for this scenario, are proposed, and their components are considered. The dynamics of the decision making process in problem situations caused by the implementation of this architecture is shown, when mixed emotions arise and the realization of what happened reflects on the agent's temper. IVA's social behavior is shown, during which in the process of communicating with the user the agent expresses learned from experience secondary emotions, which can be either in harmony or in conflict with the realized secondary emotions, resulting both from the agent's generalized condition and the events. The investigated secondary emotions are: relief, confidence, prestige, uncertainty, confirmed fear, disappointment; and also the socially expressed secondary emotions such as refrained sadness, refrained anger, businesslike manners, politeness and authoritativeness.


Milenov T.I.,Bulgarian Academy of Science | Milenov T.I.,European Polytechnical University | Rafailov P.M.,Bulgarian Academy of Science | Urcelay-Olabarria I.,Laue Langevin Institute | And 4 more authors.
Materials Research Bulletin | Year: 2012

La 2CoMnO 6-δ crystal doped with Pb and Pt was successfully grown. The lattice parameters were determined by X-ray diffractometry, while polarized Raman spectroscopy and magnetic measurements were used to probe the Co/Mn positional order, and to suggest the most likely crystal and magnetic structures. The magnetic response of the crystal to ac- and dc-magnetic fields is discussed in terms of possible occupation of the crystallographic positions by the constituent ions and valence state disproportion in the Mn/Co ions. The results are explained within a framework of statistically random distributed Mn 3+OMn 4+ and Co 2+OPt 4+ chains within the predominantly ordered Co 2+/Mn 4+ double perovskite structure. © 2012 Elsevier Ltd. All rights reserved.


Dezert J.,ONERA | Tchamova A.,Bulgarian Academy of Science | Konstantinova P.,European Polytechnical University
FUSION 2016 - 19th International Conference on Information Fusion, Proceedings | Year: 2016

The main objective of this paper is to present, to apply, and to test the effectiveness of the new method, based on belief functions, proposed by Dezert et al. in order to evaluate the quality of the individual association pairings provided in the classical optimal data association solution for improving the performances of multitarget tracking systems in clutter, when some of the association decisions given in the optimal assignment solution are unreliable and doubtful and lead to potentially critical mistake. This evaluation is based on a Monte Carlo simulation for particular difficult maneuvering and non-maneuvering MTT problems in clutter. A comparison with the results obtained on the base of Kinematic only Data Association and Generalized Data Association is made. © 2016 ISIF.


Stoyanov V.,Bulgarian Academy of Science | Stoyanov V.,European Polytechnical University | Kostova B.,New Bulgarian University | Petkova V.,Bulgarian Academy of Science | Pelovski Y.,University of Chemical Technology and Metallurgy of Sofia
Journal of Thermal Analysis and Calorimetry | Year: 2012

In this study, three types of cementitious composites based on (i) white Portland cement and sand (cement-to-aggregate 1:3, and water-to-cement 0.50), (ii) white Portland cement and marble powder (cement-to-aggregate 1:2, and water-to-cement 0.60), and (iii) white Portland cement and marble powder with polycarboxylate-based admixture (HRWR) (cement-to-aggregate 1:2, and water-to-cement 0.40 + HRWR) were studied. Their states after 28 and 120 days of water curing were evaluated by measurement of physical-mechanical properties, such as density, compressive strength and porosity. Thermal analysis, X-ray diffraction analysis and scanning electron microscopy were used to identify the crystal phases and their morphology. The experimental data show that the white cement mortars with higher water content exhibit larder variety of newly formed phases, like hydration products of the C-S-H type. The structure of mortars with polycarboxylate-based admixture is so dense that there is no possibility of crystal hydrates development at late curing ages. The use of marble as filler leads to a partial inclusion of carbonate ions in the newly formed hydrated phases (carbo-aluminates). © 2012 Akadémiai Kiadó, Budapest, Hungary.


Petkova V.,Bulgarian Academy of Science | Stoyanov V.,Bulgarian Academy of Science | Stoyanov V.,European Polytechnical University | Pelovski Y.,University of Chemical Technology and Metallurgy of Sofia
Journal of Thermal Analysis and Calorimetry | Year: 2012

Self-compacting cement mortars and concretes are characterizedwith an excellent workability and with high early strengths, which makes them suitable for elements in pre-cast concrete. Both the dense structure and the nondefected surface of self-compacting mixes are achieved by the incorporation of relatively large amounts of fine mineral additives and use of polycarboxylate admixtures. All these advantages determine the great potential for manufacturing of architectural elements and details. However, there exist many features in the structure-formation and the hardening of these systems. The authors investigate in this study the evolution of the process of curing and the crystal formation up to the 120th days of water-curing. Moreover, the effects of replacement of 10 wt% white cement with natural zeolite are studied. Special attention is paid to the thermal analysis through which one determines the effects of dehydration of the new-formed crystal hydrates, de-carbonization of carbonate-containing phases, and zeolite incorporation. Differences in the thermal behaviour of self-compacting mortars are compared with two types of referent samples. The thermal experiments were complemented with physical-mechanical and structural measurements, including mercury intrusion porosimetry, powder X-ray diffraction and scanning electron microscopy. Experiments and analysis, both determining the development of the microstructure, indicate the formation of a dense structure of white selfcompacting mortars. This is achieved at the early age impeding the growth of new crystals. The incorporation of zeolite increases the early strengths of samples, thus making the structure denser, and completely blocking the water permeability. As the zeolite is a soft and ductile mineral, it can be expected that the volume deformations of microstructure of the zeolite-containing mortars, are reduced. © Akadémiai Kiadó, Budapest, Hungary 2011.


European Polytechnical University | Entity website

European Polytechnical University has the pleasure to invite you to the Fifth Annual International Scientific Conference ESI 2015 "Education, Science, Innovations " 10-11 June, 2015, In Pernik, Bulgaria Conference Topics: Innovations in Architecture; Innovations in Civil Engineering; Innovations in Natural Sciences; Innovations in Education; Innovations in Computer Systems and Informatics; Networks and Telecommunications; Innovations in Psychology; Humanities in the Modern World; Economy and Innovations; Policies and Innovations; Green Energy and Sustainable Development; Student Session; Location of the conference The conference will be held at the European Polytechnical University, "Sv. sv Kiril and Metodiy " 23 str ...

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