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Proceedings of the Technical university of Sofia, 1995 -: Recent submissions

Now showing items 261-280 of 853

Title: Софтуер за трансформация към главни оси с MAPLE Author: Пеева, Кети Георгиева; Peeva, Ketty Georgieva; Андреев, Любомир; Andreev, Ljubomir Date: 2008 Abstract: We develop software in MAPLE environment for transformation of the general form equation of second order curve (conic) or second order surface (quadric) to its normal form. Following analytical methods and using some of the MAPLE functions, we propose original code for computing the normal form equation of a conic or quadric, for plotting ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Изследване на характеристиките на набор сигнали с показателите на Ляпунов Author: Манев, Стойчо Велизаров; Manev, Stoitscho Velizarov Date: 2008 Abstract: Study of different types of signals has been made. Signals, generated by means of appropriate algorithms have been tested. Hystograms and graphs are presented. The obtained results have been discussed. Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Изследване на клас сигнали с помощта на модифициран алгоритъм Author: Манев, Стойчо Велизаров; Manev, Stoitscho Velizarov Date: 2008 Abstract: Study of different types of signals has been made . For achieving this aim an appropriate modified algorithm, designed for obtaining the Lyapunov’s exponents, has been used. Hystograms and graphs are presented. The obtained results have been discussed. Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Сравнителен анализ на алгоритми за изследване на клас сигнали Author: Манев, Стойчо Велизаров; Manev, Stoitscho Velizarov Date: 2008 Abstract: A comparative study of algorithms, designed for analysis of class of signals has been made. On this base an appropriate algorithm has been chosen. The effectiveness of the algorithm, by the processing of determined signals, has been shown. Тhe Lyapunov’s exponents are find and some respective conclusions have been made. Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Multiple-model wiener filter for load disturbance rejection in hydro generator local network operation Author: Puleva, Teofana Todorova; Пулева, Теофана Тодорова Date: 2008 Abstract: The problem of random load disturbance rejection for hydro generator operating in local network is formulated as an optimal controller design problem in sense of minimum mean-square error - Wiener filter design. A multiple model adaptive control approach is explored. The control signal is formed as a weighted sum of particular control ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Опростен алгоритъм за числено интегриране чрез еднокорпусен микроконролер ot фамилията PIC12XX Author: Милетиев, Росен Георгиев; Miletiev, Rossen Georgiev; Бекярски, Александър Богданов; Bekiarski, Aleksandyr Bogdanov; Бойчев, Димитър; Bojchev, Dimitar Date: 2008 Abstract: The algorithm’s realization for numerical integration using a microcontroller of the family PIC12XX is related to some technical difficulties like the small computing resource of the microcontroller and the lake of an arithmetical multiplying unit. These problems require the adaptation of the known classical algorithms in order to achieve ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Natural radioactivity in the soils of bansko-razlog region Author: Kobilarov, Roumen Georgiev; Кобиларов, Румен Георгиев Date: 2008 Abstract: The natural gamma radiation and 137Cs deposit in the soils of Bansko-Razlog region was measured, using high-resolution gamma ray spectroscopy. The resulting annual effective dose was estimated to be 0,32 mSv, that is very lower than the level of 1 mSv adopted as the upper annual dose limit for the population in Bulgaria. The study area is ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: RIGHT-LUD wide bandpass SC ladder filter with compensation for finite amplifier gain and offset voltage Author: Radev, Nikolay Asenov; Радев, Николай Асенов; Ivanov, Kantcho Panayotov; Иванов, Кънчо Панайотов Date: 2008 Abstract: A gain- and offset- compensated (GOC) modification of sixth-order right-LUD wide bandpass switched-capacitor (SC) ladder filter is presented. At first, the conventional integrators in the filter are replaced with GOC SC integrators and the unswitched capacitors are split into two capacitors. Subsequently, the nominal op amps gain value A0 ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Понижаващ преобразувател на постоянно напрежение управляван в режим на хлъзгане с широчинно импулсна модулация Author: Табахнев, Иван Нанев; Tabahnev, Ivan Nanev; Трушев, Иван Митков; Trushev, Ivan Mitkov; Владов, Симеон Стоянов; Vladov, Simeon Stoyanov Date: 2008 Abstract: Based on the sliding mode control (SMC) principle [1], [2], [3], a controller of a pulse-width modulated (PWM) buck DC/DC converter is considered [4]. Modeling and simulations of the behavior of the system is very important before the on chip realization. The converter has been simulated in SIMULINK, and its dynamic performances have been ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Atmospheric moisture monitoring using labview Author: Nikolov, Georgi; Николов, Георги; Nikolova, Boyanka Marinova; Николова, Боянка Маринова Date: 2007 Abstract: This paper is dedicated to design and implementation of a virtual system for atmospheric moisture parameters measurement, monitoring and logging. The main purpose is to demonstrate new developments made with a multifunction data acquisition (DAQ) system, integrated sensors, graphical programming environment and new generation of DAQmx ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Micropumps for medical applications Author: Denishev, Krassimir Hristov; Денишев, Красимир Христов; Trencheva, Boryana; Тренчева, Боряна Date: 2007 Abstract: Much effort is being applied to the development of autonomous Micro Electro Mechanical Systems (MEMS). In their full and total configuration, Microsystems consist of sensor part, data processing part and actuator part. One kind of actuator devices, these are Microfluidic Pumps. Nowadays, they find very large applications in different areas ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Accelerometer design Author: Denishev, Krassimir Hristov; Денишев, Красимир Христов; Petrova, Mihaela; Петрова, Михаела Date: 2007 Abstract: Much effort is being applied to the development of intelligent, autonomous Micro Electro Mechanical Systems (MEMS). One kind of such devices, these are Accelerometers. Nowadays, they find very large applications in different areas of life, science and techniques. Contemporary microelectronics and microelectronic technologies give the ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Microstructure and optical properties of ito thin films investigated for heat mirrors in solar collectors Author: Dobrikov, Georgy Hristov; Добриков, Георги Христов; Rassovska, Milka Markova; Расовска, Милка Маркова; Boiadjiev, Stefan Ivanov; Бояджиев, Стефан Иванов; Gesheva, Kostadinka A..; Гешева, Костадинка А.; Sharlandjiev, Peter Stoyanov; Шарланджиев, Петър Стоянов; Koserkova, Albena; Косеркова, Албена Date: 2007 Abstract: The aim of this work is preparation of RF sputtered ITO thin films for application as heat mirrors in solar thermal collectors. The alteration of optical properties and behavior in IR spectra of additionally treated films was investigated. The films were deposited on silicon and glass substrates by RF sputtering on vacuum installation A-400 ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: “Tailored” conductivity of segmented polydiphenylacetylene thin films for microelectronc application Author: Jivkov, Ivaylo Cankov; Живков, Ивайло; Alexandrova, Maria Petrova; Александрова, Мария Петрова; Kalinova, Radostina; Калинова, Радостина; Jossifov, Christo Petkov; Йосифов, Христо Петков; Runenkina, Elena Sotirova; Руненкина, Елена Сотирова; Dobrikov, Georgi Hristov; Добриков, Георги Христов; Rassovska, Milka Markova; Расовска, Милка Маркова Date: 2007 Abstract: New types of segmented polymers based on polydiphenylacetylene (PDPA) were synthesized and characterized. Measurement of current-voltage (I-V) characteristics of a representative samples show that bulk charge carrier injection dominate the conductive process rather than contact limited transport. Comparing the I-V characteristics measured ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: WO 3 thin films deposition on quartz crystal resonators for applications in gas sensors Author: Boyadjiev, Stefan Ivanov; Бояджиев, Стефан Иванов; Rassovska, Milka Markova; Расовска, Милка Маркова Date: 2007 Abstract: The present research is focused on the preparation and properties of sputtered transition metal oxides thin films. WO3 films of various thickness were deposited on quartz resonators in order to use the quartz crystal microbalance method for studying heir gas sensing properties. The influence of oxygen partial pressure and substrate temperature ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Nano semiconductor devices, including molecular semiconductors Author: Rusev, Rostislav Pavlov; Русев, Ростислав Павлов; Atanasov, Boris; Атанасов, Борис; Takov, Tihomir Borisov; Таков, Тихомир Борисов; Hristov, Marin Hristov; Христов, Марин Христов Date: 2007 Abstract: New types of semiconductors for microelectronics needs are proposed. In the first part of the article single electron transistors, their physical characteristics, constructive features and problems related to its V-PADOX technology construction are described. In the second part colloidal semiconductors in photo-conversion devices are ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Design and production of precise thick film circuits using photolithographic technology Author: Partinova, Simona Peneva; Партинова, Симона Пенева; Takov, Tihomir Borisov; Таков, Тихомир Борисов Date: 2007 Abstract: Fodel® Photoprintable Thick Film Pastes made by DuPont guarantee that printed circuits made by using these pastes benefit from both the recognized reliability of ceramic materials and the higher image density that is common for the thin film circuits by increasing the density in the X-Y plane by 400-500% compared to the conventional screen ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: The influence of fabrication steps on selected properties of power dmos transistor Author: Ivanova, Malinka Spasova; Иванова, Малинка Спасова; Donoval, Daniel; Доновал, Даниел; Marek, Juraj; Марек, Журай; Vrbicky, Andrej Date: 2007 Abstract: The high-voltage power DMOS transistors are widely used for various power electronic applications as motor controls and power switching supplies. Research and optimization of their characteristics is one of the challenges of power MOS transistor design. The Technology CAD (TCAD) tools support process and device simulation and help to predict ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Modified compact model of mosfet working under ESD stress Author: Andonova, Anna Vladova; Андонова, Анна Владова; Gadjeva, Elisaveta Dimitrova; Гаджева, Елисавета Димитрова; Draganska, Polya Georgieva; Драганска, Поля Георгиева; Pavlov, Galin; Павлов, Галин; Marinov, Ivan Yotov; Маринов, Иван Йотов Date: 2007 Abstract: A modified compact model to simulate the high current characteristics of a MOSFET working under ESD stress is developed. The model realized with current source is used to demonstrate the better accuracy of simulated I-V characteristics for the snapback region. The variation of the simulated output I-V characteristics from gate voltage values ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Investigation of the thermal interaction between an isothermal cylinder and its isothermal enclosure of an electric junction Author: Kafadarova, Nadezhda Miteva; Кафадарова, Надежда Митева; Andonova, Anna Vladova; Андонова, Анна Владова; Georgiev, Georgi; Георгиев, Георги Date: 2007 Abstract: This article deals with numerical simulation of air flow and heat transfer in an electric junction box comprising conductive metal wire rods each having a cylinder shape in cross section. Results obtained by a commercial CFD package widely used for electronic system temperature predictions. The paper gives considerable insight into the ... Library:
TECHNICAL UNIVERSITY - SOFIA