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

Now showing items 241-260 of 853

Title: Multilead signal preprocessing by linear transformation to derive an ECG lead where the atypical beats are enhanced: MATLAB implementation Author: Levkov, Chavdar; Левков, Чавдар; Mihov, Slavy Georgiev; Михов, Слави Георгиев Date: 2008 Abstract: Suggested is an algorithm for ECG signal preprocessing for reliable detection and distinguishing of atypical beats in electrocardiograms (ECG). Derived is an optimal linear transformation from primary lead signals, which maximizes certain criterion for distinction of an atypical beat from the typical ones. This optimal transformation is ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Combined high-pass and power-line interference rejecter filter for ECG signal processing Author: Iliev, Ivo Tzvetanov; Илиев, Иво Цветанов; Tabakov, Serafim Dimitrov; Табаков, Серафим Димитров; Krasteva, Vеssela Tzvetanova; Кръстева, Весела Цветанова Date: 2008 Abstract: In this study we introduce one alternative approach for ECG high-pass filtering and interference rejection based on the simple principle for averaging of samples N with a predefined distance between them D. FilterDxN has a comb frequency characteristic with high-pass cut-off defined by the number of samples N and zeros at the integer ratio ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Биодесулфуризация на въглищата. Критическа оценка Author: Йовчев, Милко Петров; Iovchev, Milko Petrov; Гаджанов, Петьо; Gadjanov, Petyo Date: 2008 Abstract: A critical assessment of coals biodesulfurization technology is done as part of so called „Clean coals technologies”. A special attention is paid to both inorganic and organic sulfur presented in coals and also to desulfurizing bacteria which can be used to oxidize sulfur compounds to sulfates and to remove them by washing. It is underlined ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Наблюдател на скорост за „летящ” старт на асинхронен двигател управляван с честотен преобразовател Author: Рац, Емил; Ratz, Emil Date: 2008 Abstract: The paper presents an original approach for rotation speed valuation of asynchronous motors driven by frequency inverters. This method is considering the conductance properties of the asynchronous motor stator winding at supply frequencies close to the rotational frequency of the machine. The analysis of the complex conductance proves that ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Експериментално изследване на диференциален индуктивен сензор със стъпална намотка Author: Гергова, Захаринка Кирилова; Gergova, Zaharinka Kirilova Date: 2008 Abstract: The present article is a continuation of other research works of the author, related to exploring the characteristics of inductive sensors for linear displacement. Experimental study of the characteristics displacement-output voltage of differential inductive sensor has been done. The purpose of the research is confirming the qualities of ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Аналитично отчитане на реакцията на котвата при постояннотокови двигатели с постоянни магнити Author: Божилов, Ганчо Йорданов; Bojilov, Gantcho Yordanov; Иванов, Адриан Петров; Ivanov, Adrian Petrov Date: 2008 Abstract: The Current study presents a method for analytical evaluation and determining the bias point of permanent magnets for DC motors tuned on by ferrite or rare earth magnets, which is related optimal and rational use of their volume. The elaborated analytical method allows for identifying the bias point adequate precision by evaluating the ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Оптимизиране на светлоразпределението на улични осветители от тип “плосък лъч” Author: Пачаманов, Ангел Саракинов; Pachamakov, Angel Sarakinov; Пачаманова, Десислава А.; Pachamakova, Dessislava A.; Христов, Константин; Hristov, Konstantin Date: 2008 Abstract: This paper presents results of the mathematical modeling of the intensity distribution of a city street lighting fitting for a single row of lamp posts and a given height at which lighting fittings hang. The reflection indicatrix of the road corresponding to this particular setting is taken into consideration (at 40 kmph, a = 3,3 deg; at ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Оптимизиране на светлоразпределението на тунелни осветители от тип “плосък лъч” Author: Пачаманов, Ангел Саракинов; Pachamakov, Angel Sarakinov; Пачаманова, Десислава А.; Pachamakova, Dessislava A.; Петров, Стоян; Petrov, Stoyan Date: 2008 Abstract: We present results of the mathematical modeling of the lower surface of intensity distribution of an asymmetrical tunnel lighting fitting. The problem is formulated as a linear program. The objective is to minimize the lighting fitting's luminous flux so as to achieve the luminance determined by the norm for a given setting of the lighting ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Моделиране на частични разряди в съединителна кабелна муфа за средно напрежение Author: Червенкова, Тодорка Вълева; Chervenkova, Todorka Valeva; Червенков, Атанас Георгиев; Chervenkov, Atanas Georgiev Date: 2008 Abstract: Cable muff for connecting of power cable of medium voltage is considered. The cable muff must ensure linear homogeneous distribution of electrical strength in the cable. If this condition is not implemented, then in the cable insulation can be a partial discharge. The distribution of electrical strength in the cable insulation by extreme ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Моделиране и симулация на кабели в честотната и времевата област Author: Червенкова, Тодорка Вълева; Chervenkova, Todorka Valeva Date: 2008 Abstract: The switching of semiconductor devices is the main source of electromagnetic interference (EMI) in power static converters. Fast power devices generate high levels of electromagnetic emissions in the form of high-frequency currents. These high-frequency disturbances travel and spread over the power cables. To study the influence of ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Еквивалентен модел на n на брой линейни произволно магнитно свързани индуктивности – обобщен линеен трансформатор без загуби Author: Паралиев, Мартин Любенов; Paraliev, Martin Lyubenov; Димитров, Димитър Ценев; Dimitrov, Dimiter Tsenev Date: 2008 Abstract: Two coupled inductors equivalent model based on controlled voltage sources is very well known (using mutual inductance). Nevertheless, it has two disadvantages: in some cases the model elements do not have physical interpretation (negative inductance) and it does not comply with the general case of arbitrary number coupled elements. The aim ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Разпространение на солитони в предавателни линии Author: Червенкова, Тодорка Вълева; Chervenkova, Todorka Valeva; Червенков, Атанас Георгиев; Chervenkov, Atanas Georgiev Date: 2008 Abstract: The propagation of solitary waves (solitons) in transmission line is investigated. The solitons are generated in the non-linear dispersion circuit. It is presented as non-linear circuit with distribution parameters, which include non-linear capacitors. The non-linear circuit consists of multiple sections (cells), which included inductance, ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Технологична инфраструктура на учебен процес, базирана на интегриран модел за електронно обучение Author: Минковска, Даниела Велева; Minkovska, Daniela Veleva Date: 2008 Abstract: The paper presents the technological description on created integrated model for e-education. The basic methods of the creation, using and management of the teaching process and knowledge mastering are viewed, using technical and human resources and interaction between them. The conclusions are done for the proposed strategy and for her ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Модем за комуникации в аналогови самоорганизиращи се УКВ PMR радиомрежи Author: Илиев, Илия Тонев; Iliev, Ilia Tonev; Цолов, Ангел Белчев; Colov, Angel Belchev; Неделчев, Марин; Nedelchev, Marin Date: 2008 Abstract: The paper presents a proposition and research of a communication modem in the licensed band for PMR radio networks in half-duplex mode. The modem uses PSK modulation in baseband utilizing Manchester coding. In order to icrease the noise performance, it uses diversity transmitting according to schematics (2,3) or (3,5). Theoretical equations ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Подобряване на компютърно томографски изображения на основата на морфологични филтри Author: Георгиева, Веска Младенова; Georgieva, Veska Mladenova Date: 2008 Abstract: In the paper is presented an approach for computed tomography (CT) images enhancement when focusing on the area of the brain. It consists of the following basic stages for image processing: selecting the region of interest (ROI), changing the brightness of the selected ROI by equalization of the local histogram and contrast increasing by ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Проследяване на лица с адаптивен Mean-Shift алгоритъм и филтър на Калман Author: Муратовски, Красимир; Muratovski, Krasimir; Бумбаров, Огнян Любенов; Boumbarov, Ognian Lyubenov Date: 2008 Abstract: This paper presents a novel approach to face detection and tracking in video sequences. Probability distribution of the color for the human skin is used as major facial feature. A 2D histogram built from the color components of the image in YCrCb color space is used as representation of the model of the human skin. Facetracking involves the ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Сравнение на вероятностни цветни модели за отделяне на области с кожа Author: Муратовски, Красимир; Muratovski, Krasimir; Бумбаров, Огнян Любенов; Boumbarov, Ognian Lyubenov; Щилянова, Диана Йорданова; Shtilyanova, Diana Yordanova Date: 2008 Abstract: This paper presents a comparison between the possibilities of two probabilistic models to detect image areas containing human skin. The major sign used during the classification is the probability for any element to contain the color distribution of a human skin. The analyzed two probabilistic models by this paper are two- dimensional ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Изследване на преходните процеси и устойчивостта на алгоритъм заоптимална филтрация на DSSS сигнали Author: Илиев, Вася Бойков; Iliev, Vasya Boykov; Момчеджиков, Михаил Благоев; Momchedjikov, Mikhail Blagoev Date: 2008 Abstract: The results from the number modeling of the model for correlation handling of complex signals, proposed in [1] is represented. The correlation extreme system dynamics is analyzed, also the interaction of the subsystems for tracking and synchronization. The shifts, disturbing the stability of the system are analyzed, also an estimation of ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Оптимална филтрация на DSSS сигнали Author: Илиев, Вася Бойков; Iliev, Vasya Boykov; Момчеджиков, Михаил Благоев; Momchedjikov, Mikhail Blagoev Date: 2008 Abstract: A mathematical model of the algorithm for optical filtration, based on the DSSS signals according to the criteria for minimum of second central moment of the error is worked out. The algorithm is base of the method for correlation handling of complex signals proposed in [1]. The algorithm is worked out by complex using of the theorems for ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Ускоряване на навигацията в XML полуструктурирани документи с помощта нa апарата на линейната алгебра Author: Георгиев, Божидар Стефанов; Georgiev, Bozhidar Stefanov; Георгиева, Адриана Анри; Georgieva, Adriana Anri Date: 2008 Abstract: Classical formalisms( relational algebra and calculus) cannot be directly used for XML tree document as query languages due to different underlying data models. An adequate theoretical mechanism is critical for creating a query languages that handle XML documents and is extremely important for their development and standardization. In this ... Library:
TECHNICAL UNIVERSITY - SOFIA