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Sofia, Bulgaria

The Technical University , based in Sofia, is the largest technical university in Bulgaria. Founded on 15 October 1945 as part of the Higher Technical School , it is an independent institution since 1953, when the Polytechnic was divided into four separate technical institutes. It has had its present name and university status since 21 July 1995 and has 14 main faculties based in Sofia, Plovdiv and Sliven, as well as 3 additional ones with education only in foreign languages — German, English and French. Wikipedia.

Agency: Cordis | Branch: FP7 | Program: CSA-CA | Phase: Fission-2013-2.1.2 | Award Amount: 4.04M | Year: 2013

The Fukushima nuclear accident in Japan resulted from the combination of two correlated extreme external events (earthquake and tsunami). The consequences (flooding in particular) went beyond what was considered in the initial NPP design. Such situations can be identified using PSA methodology that complements the deterministic approach for beyond design accidents. If the performance of a Level 1-Level 2 PSA concludes that such a low probability event can lead to extreme consequences, the industry (system suppliers and utilities) or the Safety Authorities may take appropriate decisions to reinforce the defence-in-depth of the plant. The project ASAMPSA_E aims at identifying good practices for the identification of such situations with the help of Level 1-Level 2 PSA and for the definition of appropriate criteria for decision making in the European context. It offers a new framework to discuss, at a technical level, how extended PSA can be developed efficiently and be used to verify if the robustness of NPPs in their environment is sufficient. It will allow exchanges on the feasibility of extended PSAs able to quantify risks induced by NPPs site (multi-units reactors and spent fuel pools, modelling impact of internal initiating events, internal and external hazards on equipment and human recovery actions ).

Gyulchev G.N.,Sofia University | Stefanov I.Z.,Technical University of Sofia
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

In some models dark energy is described by phantom scalar fields (scalar fields with the "wrong" sign of the kinetic term in the Lagrangian). In the current paper we study the effect of phantom scalar field and/or phantom electromagnetic field on gravitational lensing by black holes in the strong deflection regime. The black-hole solutions that we have studied have been obtained in the frame of the Einstein-(anti-)Maxwell-(anti)dilaton theory. The numerical analysis shows a considerable effect of the phantom scalar and electromagnetic fields on the angular position, brightness, and separation of the relativistic images. © 2013 American Physical Society.

Popov D.,Technical University of Sofia
Applied Thermal Engineering | Year: 2014

The objective of this paper is to offer a concept for innovative hybridization of gas turbine combined cycle plant and solar power system. This conceptual plant is named as Solar Assisted Combined Cycle, as the solar energy is indirectly involved in power generation. The proposed solar hybridization can be accomplished in two ways. The first solar assisted option introduces mechanical chiller for a complete cooling of gas turbine inlet air. Such of cooling is commonly used to increase the power output of gas turbines during hot days of the year. This mechanical chiller is powered with electricity generated by a dedicated photovoltaic plant. The next solar assisted option does the same but with an absorption chiller. The steam for this chiller is generated in a solar field equipped with Linear Fresnel Reflectors. The efficiency and the total additional costs for development of these two configurations are estimated with relevant software packages. Similar power augmentation can be achieved with traditional Integrated Solar Combined Cycle plant. All main additional costs for construction of this alternative plant are also estimated. As a result, the specific costs for solar augmentation of a basic GTCC plant are obtained and compared. The configuration with an absorption chiller has lower specific incremental plant capital costs and requires smaller land area than the others. The proposed solar assisted plant concept offers an effective way for further implementation of compact linear Fresnel reflector technology. © 2013 Elsevier Ltd. All rights reserved.

Dishlieva K.G.,Technical University of Sofia
Nonlinear Analysis: Real World Applications | Year: 2011

The nonlinear impulsive differential equations with fixed moments of impulsive perturbation are the main object of investigation in this paper. Sufficient conditions for these types of equations are obtained, under which their solutions are continuously dependent and differentiable with respect to the initial conditions and the impulsive perturbations. The results are applied to a mathematical model of population dynamics. © 2011 Elsevier Ltd. All rights reserved.

Peeva K.,Technical University of Sofia
Information Sciences | Year: 2013

Analytical methods and algorithms for inverse problem resolution of fuzzy linear systems of equations in some BL-algebras (Gödel algebra in case of max-min and min-max compositions, and Goguen algebra in case of max-product composition) are presented. Algorithms with software realization for solving fuzzy linear systems of equations are proposed. Applications include fuzzy optimization with fuzzy linear systems of equation constraint, fuzzy machines and covering problem. © 2011 Elsevier Inc. All rights reserved.

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