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TECHNICAL UNIVERSITY - SOFIA: Recent submissions

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Title: Thermographic inspection of relays for railway safety equipment Author: Andonova, Anna Vladova; Андонова, Анна Владова; Ivanov, Emil; Иванов, Емил; Andreev, Andrew; Андреев, Андрей Date: 2008 Abstract: The following article presents results of the implementation of thermomonitoring methods followed up by processing of IR images. Field purpose is diagnostics of contacts wearing-out in the relays for railway safety equipment. Acceleration testing has been performed for contacts wearing-out in the relays under alternating current (AC). In ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Tool for synchronous communications in collaborative environment Author: Furnadziev, Ivan Haralampiev; Фурнаджиев, Иван Харалампиев; Tchoumatchenko, Vassiliy Platonovitch; Vasileva, Tania Krumova; Василева, Таня Крумова Date: 2008 Abstract: The paper outlines the design and implementation of end-user applications for networking and community building in shared collaborative environment. It covers features, architecture and user interface of the Chat tool, dedicated for synchronous communications in Shared Space. Chat tools aim to facilitate contextualized user communications ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Contactless thermal characterization method of switching mode power supply Author: Andonova, Anna Vladova; Андонова, Анна Владова; Tural, Ekrem; Andreev, Andrew Stefanov; Андреев, Андрей Стефанов Date: 2008 Abstract: This article presents results from the creation of switching mode power supply and non-contact thermal characterization of the separate elements that presents the risk of its reliability. Thermgraphics for several loads of different components are taken by infrared (IR) camera FLIR Р640. The developed non-contact method is realized on the ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Validation of anonymous surveys of educational subjects through their basic results Author: Videkov, Valentin Hristov; Видеков, Валентин Христов; Radonov, Rossen Ivanov; Радонов, Росен Иванов; Tsolov, Russy; Цолов, Руси Date: 2008 Abstract: The paper presents the development of an anonymous survey system using the Internet for the purposes of the System for Assessment and Maintenance of the Quality of Education (known as SOPKO) at the Technical University of Sofia. Some of the results processing functions and means for guaranteeing the process’ authenticity are described. Some ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Practical training in automotive electronics Author: Vasileva, Tania Krumova; Василева, Таня Крумова; Draganov, Vutko Aleksandrov; Драганов, Вътко Александров; Tzanov, Mihail Hristov; Цанов, Михаил Христов; Koparanov, Filip Todorov; Копаранов, Филип Тодоров; Tchoumatchenko, Vassiliy Platonovitch Date: 2008 Abstract: The increase in complexity of modern cars also increases the demands placed on diagnostics, maintenance and repair. The paper outlines the design and implementation of blended learning course for training in Automotive electronics and OBD diagnostic. Developed practical exercises with emphasis on engine performance test and OBDII diagnostic ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Methodology for teaching basic skills in PLC programming development Author: Iovev, Atanas Nikolov; Йовев, Атанас Николов; Yakimov, Peter Ivanov; Якимов, Петър Иванов; Tuliev, Nikolay Todorov; Тюлиев, Николай Тодоров; Ovcharov, Stefan Jordanov; Овчаров, Стефан Йорданов; Balkanska, Emiliya; Балканска, Емилия; Stoyanov, Eftim; Стоянов, Ефтим Date: 2008 Abstract: The teaching and training of the students in the field of Programmable Logic Controllers (PLC) is very important, because it determines the safety and the quality of control. This paper describes the various parts of the PLC and demonstrates some software for performing tasks using some of the next typical instructions: Bit Logic Instructions, ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Investigation and development of electronic instruments for plc programming training Author: Yakimov, Peter Ivanov; Якимов, Петър Иванов; Tuliev, Nikolay Todorov; Тюлиев, Николай Тодоров; Iovev, Atanas Nikolov; Йовев, Атанас Николов; Ovcharov, Stefan Jordanov; Овчаров, Стефан Йорданов; Balkanska, Emiliya; Балканска, Емилия; Mihov, Georgy Slavtchev; Михов, Георги Славчев Date: 2008 Abstract: Programmable logic controllers have been gaining popularity on the factory floor and nowadays are the most common choice for manufacturing controls. Because of the nature of a specific industrial object or manufacturing process it is impossible by reason of security the program adjustment to be performed in real conditions. Thus simulators ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: An electronic system for digitally program mable analog circuits study Author: Pandiev, Ivailo Milanov; Пандиев, Ивайло Миланов; Yakimov, Peter Ivanov; Якимов, Петър Иванов; Doychev, Doycho Dimitrov; Дойчев, Дойчо Димитров; Todorov, Todor; Тодоров, Тодор; Stanchev, Veselin; Станчев, Веселин Date: 2008 Abstract: In this paper we present a specific electronic system for analysis and design of digitally programmable analog circuits. The created electronic system is with module structure and envelops specific circuits such as programmable gain amplifiers(PGAs), attenuators, analog circuits with CMOS digital potentiometers, active filters, direct digital ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: A practical approach to design and modeling digitally programmable analog circuits Author: Pandiev, Ivailo Milanov; Пандиев, Ивайло Миланов; Yakimov, Peter Ivanov; Якимов, Петър Иванов; Dimitrov, Doycho Dimitrov; Димитров, Дойчо Димитров; Todorov, Todor; Тодоров, Тодор; Stanchev, Veselin; Станчев, Веселин Date: 2008 Abstract: In this paper, practical approaches to design and macromodeling digitally programmable analog circuits are described. The proposed design approaches are based on the design methods for analog circuits, the procedures for performing simulation projects and the general methodology for building Web-based client/server applications. Those methods ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Electronic portfolio built into windows sharepoint collaboration and learning environment Author: Shoikova, Elena Dikova; Шойкова, Елена Дикова Date: 2008 Abstract: This paper reports work-in-progress for a project to create an electronic portfolio for the Technical University-Sofia students. It outlines the components of the project being undertaken and the processes that students will experience. The paper presents the process of electronic portfolio development through five stages and its implementation ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Researching electronic portolios: educational and professional development through technology Author: Shoikova, Elena Dikova; Шойкова, Елена Дикова Date: 2008 Abstract: The use of ePortfolios in distributed learning in higher education and corporate training worldwide has increased over the last years. An ePortfolio is a highly personalized, customizable, web-based information management system, which allows students to demonstrate individual and collaborative growth, achievement, and learning over time. ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Spice simulation of the control system for frequency regulated transistor resonant inverter Author: Kunov, Georgi; Кънов, Георги Цв.; Gadjeva, Elissaveta Dimitrova; Гаджева, Елисавета Димитрова; Dimov, Todor; Димов, Тодор; Philipov, Borislav; Филипов, Борислав Date: 2008 Abstract: The paper subject of research is synthesis and SPICE simulation of a system for frequency control and regulation of series resonant transistor inverter. A characteristic feature of the system is the tracking of an only one synchronization signal. That is the current in the resonance loop. This approach is extremely preferable when the heat ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Application of postprocessing for objective function formulation in the statistical optimization using PSPICE Author: Gadjeva, Elissaveta Dimitrova; Гаджева, Елисавета Димитрова; Shikalanov, Dimitar; Шикаланов, Димитър Date: 2008 Abstract: An approach is proposed in the paper to automated statistical circuit optimization using the general-purpose circuit analysis program Cadence PSpice. The selection of the optimal variant is based on postprocessing in the graphical amalyzer Probe. The objective functions are formulated and calculated using corresponding macrodefinitions.They ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: An approach to passive circuit synthesis using genetic algorithms in MATLAB – band-pass filter Author: Durev, Vladislav Petrov; Дурев, Владислав Петров Date: 2008 Abstract: An approach to passive circuit synthesis in MATLAB is proposed in the present paper. The Modified Nodal Analysis is used for the construction of the admittance circuit matrix. A circuit of passive band-pass filter is used for the demonstration of the method. The algorithm is easy to implement in MATLAB environment. A methodology for the ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Electro-optical device parameters modeling Author: Asparuhova, Katya Konstantinova; Аспарухова, Катя Константинова; Djamiykov, Todor Stoyanov; Джамийков, Тодор Стоянов Date: 2008 Abstract: This paper presents electro-optical device parameters modeling for OrCad Pspice simulator. Electro-optical parameters of photodiodes, LEDs and laser diodes like total output power, spectral sensitivity, optical power vs. current are modeled using ABM method. The modeled relations are fitted using MATLAB which is resulting in good accuracy. ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Behavioral macromodeling of current feedback amplifiers and drive-R – amplifiers Author: Pandiev, Ivailo Milanov; Пандиев, Ивайло Миланов Date: 2008 Abstract: This paper presents new current feedback amplifier and drive-R – amplifier macromodels at behavioral level. They accurately models basic differentialmode electrical characteristics, the offset input voltage and current, the input voltage noise, the output voltage swing, short-circuit current and the input and output impedances. For creating ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Behavioral macromodeling of voltage feedback amplifiers Author: Pandiev, Ivailo Milanov; Пандиев, Ивайло Миланов Date: 2008 Abstract: This paper presents a new voltage feedback amplifier macromodel at behavioral level. It accurately models basic differential-mode and common-mode electrical characteristics, the input offset voltage and current, the differential-mode and common-mode amplification, the input voltage noise, the output voltage swing, short-circuit current and ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Multifunctional protection relay input module modernization Author: Tuliev, Nikolay Todorov; Тюлиев, Николай Тодоров; Ovcharov, Stefan Jordanov; Овчаров, Стефан Йорданов; Yakimov, Peter Ivanov; Якимов, Петър Иванов; Balkanska, Emiliya; Балканска, Емилия Date: 2008 Abstract: The paper describes the advantages of the modern numerical protection relays. It is proven that the accuracy depends mostly on the input module. Different approaches in design of current and voltage input transducers are mentioned. After studying the parameters and characteristics of the latest integrated circuits of operational amplifiers ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Investigation of digital phase detectors Author: Kachakov, Georgi; Качаков, Георги; Mihov, Georgy Slavtchev; Михов, Георги Славчев; Yordanov, Aleksandar; Йорданов, Александър Date: 2008 Abstract: This article deals to describe the simulation and the experimental investigation of the basic types of digital phase detectors and especially acquiring their phase-voltage response. This phase-voltage response represents the output voltage of the phase detector as a function of the phase difference between the digital input sequences. It ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Thermal processes in high power LED Author: Todorov, Dimitar; Тодоров, Димитър Date: 2008 Abstract: High Power LED’s have been around for years, primarily concentrated as the lighting source for a variety of applications. Nowadays, LED technology is the leading choice for interior and exterior automotive and lamp street lighting. Although LED light sources offer many advantages, special considerations apply to their use in the application. ... Library:
TECHNICAL UNIVERSITY - SOFIA