Recently added

TECHNICAL UNIVERSITY - SOFIA: Recent submissions

Now showing items 181-200 of 899

Title: Експериментално определяне на допустимите граници на изменение на реактивната мощност на хидрогенератори в зависимост от загряването на крайните пакети на статора Author: Сотиров, Димитър Кирилов; Sotirov, Dimitar Kirilov; Михов, Михо Рачев; Mihov, Miho Rachev; Баташки, Стоян; Batashki, Stoyan Date: 2009 Abstract: In the Bulgarian electric power system are working hydro generators with total power approximately 2400 MW. They are manufactured mainly in the 60s and 70s of the past century and as a rule they don't have manufacturers P-Q diagrams which would define the reactive power work range. Modern electric power control systems require the generators ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Изследване на влиянието на асиметрично аксиално изместване на полюсите на хидрогенератори върху вибрациите Author: Сотиров, Димитър Кирилов; Sotirov, Dimitar Kirilov; Ризов, Пламен; Rizov, Plamen; Панайотов, Ивайло Димитров; Panayotov, Ivailo Dimitrov Date: 2009 Abstract: During hydro generator's repair done with whole disassembling of the rotor and the stator, followed by assembling the machine, possible axia displacement of the rotor and stator or uneven pole shift may occur. In these cases when the hydro generator is excited in idle running, unbalanced electromagnetic forces occur. They cause vibrations ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Моделиране на лабораторни изследвания на трансформатори с използване на MATLAB/SIMULINK Author: Спасов, Радослав; Spasov, Radoslav Date: 2009 Abstract: This article describes MATLAB/Simulink realization of open-circuit and short-circuit tests of Electric Machinery that are performed to identify equivalent circuit parameters. These simulation models are developed to support and enhance electric machinery education at the undergraduate level. The proposed tests have been successfully integrated ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Оптимизиране на огледални оптични системи с отчитане на многократните отражения между лампата и рефлектора Author: Василев, Христо; Vassilev, Hristo; Ангелов, Ангел; Angelov, Angel Date: 2009 Abstract: A optimization problem of specular reflectors is disused in the present paper. Comparison between different possible shapes of the reflectors got from different standard curves or combination of the standard curves. Accessible material is used for specular reflection with different reflection factors. For optimization a mathematical model ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Дифузен светодиоден осветител Author: Василев, Христо; Vasilev, Hristo; Георгиев, Вълчан Тодоров; Gueorgiev, Valchan Todorov; Ганчев, Ганчо; Ganchev, Gancho Date: 2009 Abstract: A LED luminaire with diffused light is discussed. The construction and the principle of operation of the luminaire are illustrated. The efficiency of the luminaire and the uniformity of the brightness of its illuminating surface are estimated. An influence of luminaire parameters is studied over 2d model. Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Особености при регулирането на реактивното натоварване на минивец Author: Цонева, Деница; Tsoneva, Denitza; Цолов, Ангел Белчев; Tzolov, Angel Belchev; Крумов, Андрей Христов; Krumov, Andrei Hristov Date: 2009 Abstract: The article considers an algorithm of the excitation regulator of synchronous generators by mini-hydro. The aim is to provide optimum economic parameters, consistent with dynamically changing requirements of the electric companies. Integral method is introduced to maintain the power factor. The proposed method ensures stable work of the ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Разпределение на реактивното натоварване на синхронни генератори от една електрическа централа при различни принципи на регулиране – математически модел Author: Цонева, Деница; Tsoneva, Denitza; Цолов, Ангел Белчев; Tzolov, Angel Belchev; Крумов, Андрей Христов; Krumov, Andrei Hristov Date: 2009 Abstract: The article examined a mathematical model to work as a regulator of excitation of synchronous generators from mini hydro power stations (SHPP). It is provided an opportunity for a full examination of all possible modes of synchronous generators by a power plant. Analysis of captured typical working and emergency procedures and results of ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: ’The Five Fingers of My Hand’ : Human Capital and Well-being in SMEs – Evidence from Bulgaria, Finland and Scotland Author: Gabalova, Lidiya Petrova; McKie, Linda J. Date: 2013 Abstract: This paper aims to explore the SME managers' understanding of, and attitudes towards human capital (HC) and well-being as factors impacting on the business performance of their organizations. Design/methodology/approach: The study from which this paper reports included qualitative data collected through 42 semi-structured interviews with ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Установка за контролируемо разтегляне на открити електрически дъги в контактни мрежи 25kv Author: Ангелов, Иван Колев; Angelov, Ivan Kolev; Матов, Петър Иванов; Matov, Peter Ivanov Date: 2009 Abstract: Operation of 25kV AC catenary is accompanied with emergency procedures. When in place of a short circuit there is an open electric arc, it participates in the electrical circuit with its nonlinear volt – ampere characteristic. Electric arc stretched from both high temperature and the movement of one electrode (pantograph). Installations ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Оценка на ефективността на спектралния състав на светлоизточниците в уличното осветление , Author: Костов, Красимир; Kostov, Krassimir; Василев, Николай Иванов; Vassilev, Nikolay Ivanov; Караро, Улрих; Kararo, Ulrich Date: 2009 Abstract: The reflection characteristics of different road surfaces have been studied in accordance with the spectral distribution of high pressure sodium and metal-halide lamps with power of 70W, 150W, 250W and 400W. The lens transmittance of the luminous flux for people at the age of 25 and 60 has also been determined. Determined by the quantity ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Минимизиране на светлиния поток на улични осветителни уредби за обслужваща, събирателна и главна улица нормирани по видимост Author: Стефанов, Станимир; Stefanov, Stanimir Date: 2009 Abstract: In this report is present the research for minimizing lighting flux of street luminaries for some class streets. The clime of the research is to define the minimal lighting flux of street luminaries necessary for reach lightings criterions. In this way, minimizing lighting flux we have a possibility to decrease power consumption by lighting ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Енергийноефективни светлоразпределения от тип «плосък лъч» за събирателни и обслужващи улици , Author: Пачаманов, Ангел Саракинов; Pachamakov, Angel Sarakinov; Христов, Константин; Hristov, Konstantin; Енева, Петя; Eneva, Petia Date: 2009 Abstract: This paper presents results of the mathematical modeling of the intensity distribution of a lighting fitting with the “flat beam” technology. The objective is to minimize the lighting fitting's luminous flux while at the same time achieving the qualitative and quantitative norms for the considered type of lighting installation. The intensity ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Оптимизиране на светлоразпределението на осветители за пешеходни зони Author: Пачаманов, Ангел Саракинов; Pachamanov, Angel Sarakinov; Христов, Константин; Hristov, Konstantin Date: 2009 Abstract: This paper presents results of the mathematical modeling of the intensity distribution of a lighting fittings for a single row of lamp posts and a given height at which lighting fittings hang. The objective is to minimize the lighting fitting's luminous flux so as to achieve the average iluminance determined by the norm for a given setting ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Компютърно симулиране на разпространението на високочестотни сигнали в силови кабели за средно напрежение Author: Червенкова, Тодорка Вълева; Chervenkova, Todorka Valeva; Червенков, Атанас Георгиев; Chervenkov, Atanas Georgiev; Божков, Стоян Х.; Bozhkov, Stoyan H. Date: 2009 Abstract: An advanced model of the power medium voltage cable for high frequency is created. Simulations of the cable model in frequency domain are made. The distributions of the impedance in frequency of the power cable by different length in border mode - opening circuit and short circuit are obtained. The change of the impedance in frequency domain ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Определяне на механичните загуби на синхронна машина по метода на самоспиране Author: Михов, Михо Рачев; Mihov, Miho Rachev; Сотиров, Димитър Кирилов; Sotirov, Dimitar Kirilov; Баташки, Стоян; Batashki, Stojan Date: 2009 Abstract: An implementation of selfstopping method for determining the mechanical losses of synchronous machine is presented. The survey is conducted in WEC "Krichim". With the obtained results for mechanical losses and reported data for the operating parameters of the machine in compensation regime are also defined steel losses. Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Заместваща схема на синхронна машина и еквивалентност на основните формули Author: Божилов, Ганчо Йорданов; Bojilov, Gantcho Yordanov Date: 2009 Abstract: In this paper an equivalent circuit of a synchronous machine for adequate description of all processes and quantity by stationary function of the machine are proposed. He corresponds of the fundamental equations of the synchronous machines of all types (salient poles, smooth poles or with variable reluctance, generators, motors, compensators) ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Към определянето на ефективната стойност на тока на еднофазните колекторни двигатели с наситена магнитна система, Author: Божилов, Ганчо Йорданов; Bojilov, Gantcho Yordanov; Иванов, Адриан Петров; Ivanov, Adrian Petrov Date: 2009 Abstract: In the paper a method for determining of the R.M.S. value and the first three odd harmonics of the current of single-phase commutator motors with saturated magnetic system is presented which the shape is non-sinusoidal. For this purpose a approximation of the magnetic characteristic of the motor by two parametric exponential function is ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Моделни изследвания за определяне характеристиките н въглищни потоци от складовото стопанство на ТЕЦ „Марица Изток 3” Author: Бонев, Бончо И.; Bonev, Boncho I. Date: 2009 Abstract: The operations in the fuel depot of TPS “Maritza East 3” are directed towards equalizing of the characteristics of the coal receipted from the opencast mine. It is possible, the realization of two strategies in this relation – a strategy purposed total “equalizing” and a strategy purposed dividing of the coal into two quality categories and ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Определяне качеството на въглищата на изхода от рудник в енергийния комплекс „Марица Изток” Author: Бонев, Бончо И.; Bonev, Boncho I. Date: 2009 Abstract: The preliminary information about quality of the coal entering in the fuel depot is of exceptional importance for the operation of the thermal power plant. Between mine “Troyanovo 3” and TPS “Maritza East 3”, it exist direct belt transport connection. In that case, it means, it is necessary the coal characteristics on the outlet of mine to ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Методи за научни визуализации – част 2 Author: Георгиев, Веселин; Gueorguiev, Vesselin; Георгиева, Десислава В.; Georgieva, Desislava V. Date: 2009 Abstract: In the last two decades, growth in volume and quantity of information is so great that new methods are needed for processing and extracting information from these 'raw' data. One of the most promising directions is the computer visualization. This survey aims to present the basic methods for the visualization of scientific information - is ... Library:
TECHNICAL UNIVERSITY - SOFIA