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

Now showing items 341-360 of 853

Title: Моделиране и реализация на сигма-делта модулатор от трети ред Author: Ценов, Георги; Tsenov, Georgi; Терзиева, Снежана; Terzieva, Snejana; Якимов, Петър; Yakimov, Peter; Младенов, Валери; Mladenov, Valeri Date: 2007 Abstract: Sigma-Delta (∑∆) modulation has become more and more popular alternative for robust and inexpensive analog-to-digital (A/D) conversion for the past years. As a result of this, the converters based on 1-bit ∑∆ modulators are widely used in different applications. In this paper we present an experimental electronic realization of a third order ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Разпространение на солитони в кабелни линии със загуби Author: Червенкова, Тодорка; Chervenkova, Todorka Date: 2007 Abstract: The propagation of solitary waves (solitons) in communication line is investigated. The solitons are generated in the non-linear dispersion transmission line. It is presented as non-linear circuit with distribution parameters, which include non-linear capacitors. The non-linear circuit consists of multiple sections, which included inductance, ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Многоканална измервателна система за електрическа импедансна томография Author: Долапчиев, Ивайло; Dolapchiev, Ivaylo; Брандиски, Костадин; Brandisky, Kostadin Date: 2007 Abstract: This paper presents a prototype of a 16-channel Electrical Impedance Tomography System (EITS). The main characteristics of the system include: continuous frequency selection from 1 kHz to 100 kHz, 16 independent current sources and 16 independent synchronous voltmeters. The governing software which calibrates the system components and ... Library:
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Title: Aлгоритъм за определяне на закъсненията в електрически вериги с логически схеми Author: Филипова, Красимира; Filipova, Krasimira; Филипова-Петракиева, Симона; Filipova-Petrakieva, Simona Date: 2007 Abstract: Dynamical analysis of electrical circuits, based on the logical schemes, takes into consideration the delays of the output signals with respect to the input signals of the each logic schemes in the electrical circuit considered. An algorithm for synchronization the signals in the analyzed electrical circuit, takes into account the delays ... Library:
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Title: Компенсация на влиянието на крайния коефициент на усилване на операционните усилватели върху характеристиките на елиптични верижни SC филтри Author: Радев, Николай; Radev, Nikolay; Иванов, Кънчо; Ivanov, Kantcho; Станчев, Калин; Stanchev, Kalin Date: 2007 Abstract: A combined approach for reducing the effects of operational amplifiers finite DC gain A in SC elliptic leapfrog ladder filters is presented. The effectiveness of the proposed approach is demonstrated by designing a fifth-order lowpass filter. The variation of the finite gain A from its nominal value A0 is taken into account. Library:
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Title: Подход за обучение на студенти по обектно-ориентирано програмиране Author: Maleshkov, Stoyan Bogdanov; Жечев, Димитър Павлов; Jetchev, Dimitar Pavlov; Малешков, Стоян Богданов; Maleshkov, Stoyan Bogdanov Date: 2006 Abstract: Based on the experience gained in object-oriented programming (OOP) the paper proposes a practical approach for student’s training at a technical university. Studying the Java language the main attention is focused on understanding the general philosophy of OOP. This is achieved by building up a general package of classes for processing of ... Library:
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Title: An approach for determing the difficulty of test items for assessment the quality of knowledge mastering Author: Jelev, Gospodin Jelev; Желев, Господин Желев; Minkovska, Daniela Veleva; Минковска, Даниела Велева; Minkova, Yoana Mihaylova; Минкова, Йоана Михайлова Date: 2006 Abstract: The paper presents the results from research and analyses of computerized test control for students’ knowledge assessment. One of the basic test characteristic – it’s difficulty is examined and analyzed. The quality of used test items is verified and estimated through experimental data, obtained from researches on two groups of students in ... Library:
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Title: Защо най-трудно се създават инженери за вградени устройства Author: Георгиев, Веселин Gueorguiev, Vesselin; Иванов, Иван Евгениев Ivanov, Ivan Evgeniev; Георгиева, Десислава Georgieva, Desislava Date: 2006 Abstract: Programming for embedded devices and systems is modern and preferable, and there are work positions in many companies – so students and engineers are interested in it. After few months a great percent of them quit or hesitate to work in this area. As a result – we have a lot of programmers and control engineers but there is lack of people ... Library:
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Title: A new approach to conducting educational tests in a web environment Author: Videkov, Valentin Hristov; Djamiykov, Todor Stoyanov; Radonov, Rossen Ivanov Date: 2006 Abstract: This paper treats a new approach to the conduction of educational tests in different subjects in a web environment. An environment for electronic management and its functions are presented. Up to now the educational tests in that kind of environment were carried out on computers with controlled IP addresses and in the presence of a lecturer. ... Library:
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Title: Architecture of knowledge artifact tool aiming to support collaborative knowledge creation Author: Tchoumatchenko, Vassiliy Platonovitch; Scapolla, Anna Marina; Vasileva, Tania Krumova; Furnadhziev, Ivan; Poggi, A. Date: 2006 Abstract: In recent years, semantic web based applications have been developed in numerous fields, including those of knowledge management and education/training. EU project KP-Lab is intended to productively utilize emerging technologies of the semantic web infrastructure. The paper considers the functional requirements and the architecture of ... Library:
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Title: Web based software for semiconductor devices lab measurement system Author: Furnadziev, Ivan Haralampiev; Tchoumatchenko, Vassiliy Platonovitch; Vasileva, Tania Krumova; Tenev, Dimitar Date: 2006 Abstract: The advance of the technologies nowadays allows putting many laboratory measurement instruments in a single desktop box. This desktop box combined with a personal computer and Internet connection, gives a perfect opportunity for a laboratory which is accessible at any time and place. Many companies have created different measurement boxes ... Library:
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Title: Computer based measurement systems for semiconductor devices labs Author: Tchoumatchenko, Vassiliy Platonovitch; Furnadziev, Ivan Haralampiev; Vasileva, Tania Krumova; Tenev, Dimitar Date: 2006 Abstract: The paper describes the developed software architecture of computer based measurement system for semiconductor devices labs. The architecture is specifically targeted towards Web based Java applications, where the browser becomes the platform for a lightweight hypertext-based user interface. An overview of some data acquisition (DAQ) devices is performed. Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Алгоритъм за анализ на схема на Чуа Author: Манев, Стойчо; Георгиев, Владимир; Илиев, Илия рец.; Manev, Stoycho; Georgev, Vladimir; Ilieb, Iliya rev. Date: 2006 Abstract: An algorithm for analysis of Chua’s circuit has been proposed. The effectiveness of the algorithm, used by the analysis of the circuit for a fixed set of values of the parameters of the differential equations, has been shown. Тhe Lyapunov’s exponents are find and some respective conclusions have been made. Library:
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Title: Експериментално и числено изследване на баластен дросел Author: Михов, Михо Рачев; Mihov, Miho Rachev; Рац, Нели Симеонова; Rats, Neli Simeonova; Агапиев, Васил Минчев рец.; Agapiev, Vasil Mihchev reviewer Date: 2006 Abstract: The present work represents experimental and numerical investigations of ballast choke for discharge lamps. Purpose of the investigation is to define the non-linear relationship between the choke inductance and the current flowing trough it. The investigated object is НВИ 250/220-Bulgarian and BSN 250 L300 – made in Poland. The numerical ... Library:
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Title: Влияние на скоростта върху изходния сигнал на електромагнитен преобразувател с отместени правоъгълни намотки Author: Иванов, Валери С.; Ivanov, Valeri S.; Daskalov, Zhivko rev.; Даскалов, Живко; Гунински, Стефчо Георгиев; Guninski, Stefcho Georgiev Date: 2006 Abstract: The influence of the relative velocity between transformer electromagnetic transducer with parallel displaced coils and conductive flat ferromagnetic object is presented in this paper. Three designs of transducer with rectangular coils are investigated. The plan diagrams at different displacements are given and the influence of the velocity ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Получаване на солитони в нелинейна предавателна линия Author: Grigorov, Grigori; Григоров, Григори; Червенков, Атанас; Chervenkov, Atanas; Младенов, Валери Марков; Mladenov, Valeri Markov; Chervenkova, Todorka; Червенкова, Тодорка; Папазов, Сава; Papazov, Sava; Тошев, Георги рец.; Toshev, Georgi rev. Date: 2006 Abstract: The generation of solitary waves (solitons) in communication line is investigated. Fundamental equations for describing of electromagnetic processes, which give the solitons solution are considered. The solitons solution of Korteweg de Vries equation is solved numerical. The comparison of finding solutions with numerical solution of circuit’s ... Library:
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Title: Нелинеен динамичен модел на индуктивни баласти Author: Рац, Нели Симеонова; Rats, Neli Simeonova; Agapiev, Vasil rev.; Агапиев, Васил рец. Date: 2006 Abstract: The modeling of the illumination devices with discharge lamps at dimming requires adequate model of the discharge lamps and of the inductive ballast. The nonlinear dynamical model in the present work is described in Matlab environment. The model represents the electromagnetic behavior of the ballast, as well as the electrical and the ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Експериментално и симулационни изследване на натриева лампа с високо налягане с мощност 1000W Author: Рац, Нели Симеонова; Rats, Neli Simeonova; Агапиев, Васил рец.; Agapiev, Vasil rev. Date: 2006 Abstract: The purpose of the present study is to investigate and validate of the developed in analytical description and models of high pressure sodium lamps (HPSL). Experimental and simulation results of HPSL investigation of power 1000W “Ceramalux Alto” produced by PHILIPS, are covered in the present work. The analysis of the received results proves ... Library:
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Title: Изразяване на светлинния поток на НЛВН чрез електрическите й величини и параметри Author: Рац, Нели Симеонова; Rats, Neli Simeonova; Agapiev, Vasil rev.; Агапиев, Васил рец. Date: 2006 Abstract: Own experience results, targeting analytical and quantitative expression of the luminous flux of high pressure sodium lamps (HPSL) dependable on the HPSL electrical values; power, voltage, current, conductance, for nominal conditions and at dimming are generalized in the present paper. The analytical models are verified by experimental ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Nb-addition and cold deformation effects on corrosion resistance of type 304L austenitic stainless steel Author: Shenawy, Eman; El-Shenawy, Eman; Tabakova, Bozhana; Табакова, Божана рец.; Шенауи, Еман; Ел-Шенауи, Еман Date: 2005 Abstract: The effects of Nb addition and cold deformation (CD) on the electrochemical behavior of austenitic stainless steel were studied in 3.5% NaCl solution. Electrochemical impedance spectroscopy (EIS) measurements have been used to investigate the corrosion behavior after two weeks of the steel immersion in 3.5% NaCl solution. The occurrence ... Library:
TECHNICAL UNIVERSITY - SOFIA