Spelling suggestions: "subject:"rra"" "subject:"rara""
41 |
Herren und HeiligeObergruber-Boerner, Carlos 08 December 2005 (has links)
Gegenstand der Arbeit sind Darstellungen, die dem Umfeld zweier Heiligenkulte in Florenz angehören und auf Bestellungen der Medici, ihrer Freunde und Verbündeten zurückzuführen sind. Den ursprünglich römischen Kult seiner Namenspatrone, der hll. Cosmas und Damian hat erst Cosimo de’ Medici in Florenz bekannt gemacht. Dabei erwies sich das Fehlen einer nennenswerten Florentinischen Tradition als maßgeblicher Faktor seiner Wirkkraft. Fra’ Angelico, Filippo Lippi und andere Künstler konnten formal neuartige Bildlösungen entwickeln, deren Inhalte sich als Projektionsflächen der politischen und geistigen Florentiner Eliten eigneten. Cosimo etablierte auf diese Weise ein Netzwerk persönlicher Repräsentation, das nicht allein die Barriere zwischen privatem und öffentlichem Raum zu durchdringen vermochte, sondern auch demonstrativ über die in Florenz herkömmliche Beschränkung auf das eigene Stadtviertel hinausgriff. Mit dem Generationswechsel nach Cosimos Tod erforderten die veränderten Machtverhältnisse auch einen Wechsel in der Strategie des Kults. In der zweiten Hälfte des 15. Jahrhunderts tritt ein anderer Kult, jener der hll. Drei Könige in den Vordergrund. Dieser besaß im Gegensatz zur Verehrung von Cosmas und Damian in Florenz eine eigenständige, spezifisch republikanische Tradition. Unter deren Schutz konnte eine kontinuierliche Politisierung althergebrachter Rituale und die Übernahme der Kontrolle durch die Medici stattfinden. Auch in diesem Fall zeigt die Analyse der erhaltenen Darstellungen, dass sie den Auftraggebern als Loyalitätsnachweis dienten und die Zugehörigkeit zum Klientel der Medici und damit der städtischen Eliten markierten. Noch in der Mitte des 16. Jahrhunderts griff Herzog Cosimo I. auf strategische Elemente und Motive des Kults zurück, nun zunehmend aus dem sakralen Kontext gelöst und Bestandteil höfischer Panegyrik. / The Images observed here are mainly of two religious cults commissioned by members, friends and allies of the Medici family. In the early 15th century Cosimo de’ Medici following the example of his father introduced his patron saints, Cosmas and Damian into his native city of Florence. Prior to this the cult of these saints was of no vital importance outside Rome. Thus there was no eminent pictorial tradition of their images which proved an important factor in the cult’s success. Fra’ Angelico, Filippo Lippi and other artists were able to develop a new imagery that allowed members of Florence’s political and humanistic circles to identify with. Cosimo established a network of personal representation which did not only penetrate the barriers between private and public space but ostentatiously reached beyond the customary boundaries of a family’s home quarter. After Cosimo’s death in 1464 political instability resulted in a change of strategy. In the second half of the 15th century a different cult, that of the Three Magi, moves into the center of medicean interest. Contrary to Saints Cosmas and Damian the cult of the Magi had an ancient and marked republican tradition in Florence. Under cover of this tradition the Medici party managed to take over control of the confraternity of the Magi and wield its influential instruments to their own benefit. As with images of Saints Cosmas and Damian those depicting the Adoration of the Magi were used as a confirmation of loyalty to the Medici and their faction. Even in the 16th century Duke Cosimo I. went back to elements and motifs of his predecessors’ strategy. Rather than reviving the cult of Saints Cosmas and Damian however they are used to give evidence of political and dynastical continuity.
|
42 |
An?lise de uma proposta construtivista de ensino de fra??es por meio da resolu??o de problemasPolese, Felipe Oneda 26 August 2011 (has links)
Made available in DSpace on 2015-04-14T14:12:48Z (GMT). No. of bitstreams: 1
435408.pdf: 2285195 bytes, checksum: 438734075763734b6936a1797d7118ec (MD5)
Previous issue date: 2011-08-26 / This dissertation presents the analysis of work with a class of basic education students from 5th grade in a private school in the city of Anta Gorda, in Rio Grande do Sul. The aim of the research was to evaluate students learning about fractions from problem solving in a constructivist perspective. The methodological approach was qualitative. The research instruments consisted of two questionnaires. The first, involving knowledge of fractions was applied before starting the activities and reapplied a semester after their conclusion, in the classroom. The second questionnaire allowed the assessment of pupils about their work. Other research instruments were the exercises performed by students and the daily lesson with systematic records made by the teacher. All data were subjected to a Discoursive Textual Analysis. Before explaining the analysis, the text reports on activities of the fractions which were developed from previous knowledge of students.The results indicate limited initial knowledge about fractions, interested and enthusiastic participation of students in class, good performance in school evaluation on the topic and persistence on the topic of learning after a semester of performing activities. On the analysis of students about their work, they stressed the interactivity and practical aspects related to the theory, consistent with the resolution of problems through a constructivist approach. Most students said they did not find related difficulties and the importance of sharing the work that must have with other people as well as helping others and solidarity. The results of the evaluation made by students are consistent with the philosophy of the school. / Esta disserta??o apresenta a an?lise de um trabalho realizado em sala de aula, com uma turma de 5? s?rie do Ensino Fundamental, em uma escola particular no munic?pio de Anta Gorda, no Rio Grande do Sul. O objetivo geral da pesquisa foi avaliar a aprendizagem dos alunos sobre fra??es a partir da resolu??o de problemas numa perspectiva construtivista. A abordagem metodol?gica foi predominantemente qualitativa. Os instrumentos de pesquisa consistiram em dois question?rios. O primeiro, envolvendo conhecimentos sobre fra??es, foi aplicado antes de iniciar as atividades e reaplicado um semestre ap?s a conclus?o das mesmas, em sala de aula. O segundo question?rio possibilitou a avalia??o dos alunos sobre o trabalho desenvolvido. Outros instrumentos de pesquisa foram os exerc?cios realizados pelos alunos e o di?rio de aula com registros sistem?ticos feitos pelo professor. Todos os dados obtidos foram submetidos a uma An?lise Textual Discursiva. Antes de explicitar a an?lise, o texto apresenta o relato das atividades sobre fra??es, que foram desenvolvidas a partir dos conhecimentos pr?vios dos alunos.Os resultados obtidos indicam escassos conhecimentos iniciais sobre fra??es, participa??o interessada e entusiasmada dos alunos nas aulas, bom desempenho na avalia??o escolar sobre o tema e persist?ncia da aprendizagem depois de decorrido um semestre da realiza??o das atividades. Quanto ? avalia??o dos alunos sobre o trabalho desenvolvido, eles destacaram a interatividade e aspectos pr?ticos relacionados ? teoria, coerentes com a resolu??o de problemas mediante um enfoque construtivista. A maioria dos alunos declarou n?o ter encontrado dificuldades e relacionou a import?ncia desse trabalho ? partilha que se deve ter com as outras pessoas, bem como a ajuda ao pr?ximo e a solidariedade. Os resultados da avalia??o feita pelos alunos s?o coerentes com a filosofia da escola.
|
43 |
Avalia??o de Pennisetum purpureum Schum na fitorremedia??o de zinco e c?dmio em solo enriquecido com res?duo / Evaluation of Pennisetum purpureum Schum. in the phytoremediation of zinc and cadmium in soil enriched with wasteNASCIMENTO, Vinicius Sampaio do 25 February 2008 (has links)
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / To meet growing demand for goods and services of modern society there is an increase in industrial activity, is highlighting the versatility of steel for use of its products. Meanwhile, as well as all human activity there is the generation of waste that may contain contaminants, among these heavy metals, which are arranged in an inappropriate manner pose a risk to humans and other living organisms. In soil heavy metals can exist in different chemical forms, presented each of them a degree of availability, and the total content of an indication of soil contamination. The phytoremediation is a technique of bioremediation, which uses the cultivation of plants to remediate contaminated soil and water, either by the extraction (phytoextraction) or stabilization (phytostabilization) of the contaminant in the environment. The objective was to evaluate the effect of the culture of Pennisetum purpurem Schum., the distribution of chemical fractions of zinc and cadmium in the soil, in three of pH values, after contamination with industrial waste containing high levels of these elements, and their possible influence germination and development of the plant. It was conducted in a completely randomized experiment 2x2x3 factorial system, in a sample of Bt horizon of a Argisol Yellow, contaminated and not contaminated with residue from Cia Mercantile and Industrial Ing?, with and without cultivation of Pennisetum purpurem Schum., and receiving the application of three doses of CaCO3. The soil used was collected in the municipality of Pinheiral - RJ, being part of the sample contaminated with waste (66.67 g kg-1) to raise the level pseudo-Zn total of the values above 1500 mg kg-1. The sample was contaminated and not contaminated divided into three groups each received a different dose of CaCO3 (0.00, 0,75; 1,5 mg kg-1). After being incubated for 40 days to 80% of the field capacity, there were planted three Seedpieces of Pennisetum purpurem Schum., genotype Cameroon, in each unit cultivated. At 18 days after planting and germination were evaluated at the average height of the seedlings. At 135 days after planting were collected to shoot and root plants. The substrates were sampled after hatching and at the end of the experiment. In substrates was determined the pH in water and, for the treatments that received waste, the levels of Zn and Cd in the following fractions: soluble (F1), exchangeable (F2), precipitated (F3), absorbed more strongly (F4) and residual (F5). The extractors used to determine the fractions were: deionized water, MgCl2, acetic acid, DTPA and aqua regia. The results showed that the germination and development of Pennisetum purpurem Schum. were limited by the content of Cd and mainly in fractions of Zn more bioavailable (F1, F2). The levels of Zn in the soluble fraction (F1) exceeding 125 mg kg-1, caused a reduction in the germination and the initial development of culture. The cultivation of Pennisetum purpureum Schum. promoted reduction of soil pH of all treatments, and favored the solubility of Zn of contaminated substrates. Leaf contents of Zn greater than 1380 mg kg-1 caused sharp reduction in growth and phytotoxicity symptoms. The Pennisetum purpureum Schum did not show a behavior as plants hyperaccumulative of Zn and Cd, but they showed Zn accumulation and they were efficient in the remediation of Zn and Cd. / Para atender a demanda crescente por bens e servi?os da sociedade moderna houve um incremento da atividade industrial, se destacando a siderurgia pela versatilidade de emprego dos seus produtos. Entretanto, assim como toda atividade humana h? a gera??o de res?duos que podem conter contaminantes, dentre estes os metais pesados, que se dispostos de forma inadequada representam um risco a o homem e outros organismos vivos. Em solos os metais pesados podem existir em diferentes formas qu?micas, apresentando cada uma delas um grau de disponibilidade, sendo o teor total um indicativo de contamina??o do solo. A fitorremedia??o ? uma t?cnica da bioremedia??o, que utiliza o cultivo de plantas para remediar solos e ?guas contaminadas, seja pela extra??o (fitoextra??o) ou estabiliza??o (fitoestabiliza??o) do contaminante no ambiente. O objetivo do trabalho foi avaliar o efeito do cultivo de Pennisetum purpurem Schum., na distribui??o das fra??es qu?micas de zinco e c?dmio no solo, em tr?s valores de pH, ap?s a contamina??o com res?duo industrial contendo altos teores destes elementos, e a sua poss?vel influ?ncia na germina??o e desenvolvimento da planta. Foi conduzido um experimento inteiramente casualizado no sistema fatorial 2x2x3, em amostra de horizonte Bt de um Argissolo Amarelo, contaminado e n?o contaminado, com res?duo da Cia Mercantil e Industrial Ing?, com e sem cultivo de Pennisetum purpurem Schum., e recebendo a aplica??o de tr?s doses de CaCO3. O solo utilizado foi coletado no munic?pio de Pinheiral ? RJ, sendo parte da amostra contaminada com res?duo (66,67 g kg-1), para elevar o teor pseudo-total de Zn a valores superiores a 1500 mg kg-1. A amostra contaminada e n?o contaminada foi dividida em tr?s grupos cada um recebeu uma dose diferente de CaCO3 (0,00; 0,75; 1,5 mg kg-1). Posteriormente sendo incubadas por 40 dias a 80% da capacidade de campo. Ap?s a incuba??o foram plantados tr?s toletes de Pennisetum purpurem Schum., gen?tipo Cameroon, em cada unidade cultivada. Aos 18 dias ap?s o plantio foram avaliadas a germina??o e a altura m?dia das pl?ntulas. Aos 135 dias ap?s o plantio foram coletadas a parte a?rea e raiz das plantas. Os substratos foram amostrados ap?s a incuba??o e no final do experimento. Nestes substratos foi determinado o pH em ?gua e, para os tratamentos que receberam res?duo, os teores de Zn e Cd nas seguintes fra??es: sol?vel (F1), troc?vel (F2), precipitada (F3), adsorvida mais fortemente (F4) e residual (F5). Os extratores utilizados para a determina??o das fra??es foram: ?gua deionizada, MgCl2, ?cido ac?tico, DTPA e ?gua r?gia. Os resultados mostraram que a germina??o e o desenvolvimento de Pennisetum purpurem Schum. foram limitados pelo teor de Cd e principalmente de Zn nas fra??es mais biodispon?veis (F1 e F2). Os teores de Zn na fra??o sol?vel (F1) superiores a 125 mg kg-1, provocaram redu??o na germina??o e no desenvolvimento inicial da cultura. O cultivo de Pennisetum purpureum Schum. promoveu redu??o do pH do solo de todos os tratamentos, tendo favorecido a solubilidade de Zn dos substratos contaminados. Teores foliares de Zn superiores a 1380 mg kg-1 provocaram acentuada redu??o no crescimento e sintomas de fitotoxidez. O Pennisetum purpureum Schum. n?o se comportou como hiperacumulador de Zn e Cd, mas apresentou acumula??o de Zn e efici?ncia na remedia??o de Zn e Cd.
|
44 |
THE FORESTRY RECLAMATION APPROACH: MEASURING SEDIMENT MASS ACCUMULATION RATES IN RECLAIMED MINE LANDS AND NATURALLY REGENERATED LOGGED FORESTS OF EASTERN KENTUCKYBond, William E. 01 January 2019 (has links)
The spread of surface coal mining has resulted in loss of forests in the Appalachian region. The Forestry Reclamation Approach (FRA) was developed to provide guidance for restoring forests on reclaimed mined land. This study hypothesizes that the FRA will result in larger magnitude of sediment accumulation rates in reclaimed mine sites compared to those reclaimed using grassland reclamation. Three sediment cores and six trenches were sampled within four reclaimed mined and three previously logged sites in eastern Kentucky. Samples were processed for radionuclides, grain-size, stable isotopes (δ13C), and POC. LIDAR data were used to identify valley fills, while historical aerial photography was used to identify changes in vegetative cover from 1994 to 2016. Radionuclide dating was used to determine sediment accumulation rates over the previous 100 years. Results from logged sites are inconclusive. δ13C data for all sites fall within the range expected for forested landscapes (C3), and do not show any transitions from grassland to forests. POC data indicates that inventories and fluxes were the same for mined and logged sites. Sediment accumulation rates for reclaimed mined lands show elevated values after the implementation of the FRA, compared to grassland reclamation, thus supporting the hypothesis for previously mined sites.
|
45 |
There is Someone in This Dress, GeorgeRoyce, Michael S 01 January 2018 (has links)
Questions surrounding queer subjectivity—including shame, the closet, and celebration—are at the core of my interests as a painter and image maker. Mining the history of religious iconography, including annunciation paintings, scenes of the crucifixion, and other notable works of this ilk, my paintings seek to explore the intricacies of sexuality and the workings of shame and celebration at play in the life of the queer-identified.
|
46 |
The Choir Books of Santa Maria in Aracoeli and Patronage Strategies of Pope Alexander VICox, Maureen Elizabeth 01 January 2013 (has links)
This study examines painted leaves and fragments that were extracted from a set of choir books created in the last decade of the fifteenth century for the basilica of Santa Maria in Aracoeli in Rome. These remnants are currently housed within various library and museum collections throughout Europe and the United States. The set is agreed upon generally by scholars to have been commissioned by Alexander VI (Rodrigo Borgia, 1431-1503), who was pope from 1492 to 1503, as a gift to the church during his time as pontiff. The choir books for Santa Maria in Aracoeli contain the bulk of the known body of work by the enigmatic illuminator Fra Antonio da Monza. The best known items from this set of choir books are a complete gradual (or book of chants for the Mass) currently housed in the Getty Museum, called the Ludwig Aracoeli Manuscript, and a montage of cuttings in the Albertina Museum, Vienna, that features a miniature of the Pentecost. These are studied in the context of the artistic patronage of Alexander VI, and political and diplomatic gift cultures in papal Rome during the last decade of the Quattrocento.
Alexander VI's gift to Santa Maria in Aracoeli served multiple functions. It advanced church music, but is also an example of a pontiff using custom luxury books for cultural diplomacy. The intent of the choir books was to build social relationships and augment the prestige of Alexander VI's regime with a local audience. Alexander VI sought to acknowledge the symbolic resonance of Santa Maria in Aracoeli and attempted to recuperate the site's importance for his reign through the gift. This study argues that the choir books were commissioned by the pontiff to promote his cultural and religious authority through abbellimento or "embellishment", the practice of commissioning ostentatious liturgical objects and additions to religious ceremonies for the purpose of developing esteem for an ecclesiastical office. This thesis argues that another purpose of the bestowment was to appease the Observant Franciscans in charge of the basilica in anticipation of Alexander VI's reforms of the Franciscan order.
|
47 |
H. Ibsen:" Paní z moře" - komplexní scénografické řešení / H. Ibsen:"Lady from the sea"Hotmarová, Lenka January 2016 (has links)
The thesis is based on scene designs for the play Lady from the sea. I focused on the concept of the game from the perspective of the actual playwright, Henrik Ibsen. To get a wider range of designs I decided to choose a modern staging by Robert Wilson and Luboš Hrůza. My goal was to accommodate the production as a source of inspiration and guidance on how to dispose the scene in my own design.
|
48 |
Altera??es micrometeorol?gicas causadas pelas mudan?as de uso do solo no Serid? PotiguarLima, Jeane Galdino Faustino 30 May 2017 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-10-04T23:59:19Z
No. of bitstreams: 1
JeaneGaldinoFaustinoLima_DISSERT.pdf: 1417447 bytes, checksum: 45a8559a124d8412550202f77b1f9a42 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-10-16T20:53:48Z (GMT) No. of bitstreams: 1
JeaneGaldinoFaustinoLima_DISSERT.pdf: 1417447 bytes, checksum: 45a8559a124d8412550202f77b1f9a42 (MD5) / Made available in DSpace on 2017-10-16T20:53:48Z (GMT). No. of bitstreams: 1
JeaneGaldinoFaustinoLima_DISSERT.pdf: 1417447 bytes, checksum: 45a8559a124d8412550202f77b1f9a42 (MD5)
Previous issue date: 2017-05-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A mudan?a na cobertura do solo provoca altera??es no balan?o de energia e no balan?o h?drico ? superf?cie. O uso inadequado do solo pode levar a uma condi??o de degrada??o avan?ada, a qual ? denominada de processo de desertifica??o. No Brasil, existem v?rios N?cleos de Desertifica??o, dentre os quais o N?cleo de Desertifica??o do Serid? (RN-PB). Assim, o presente trabalho partiu da premissa de que o processo de desertifica??o na regi?o do Serid? Potiguar (RN), possivelmente, tem causado variabilidades na temperatura da superf?cie, no albedo e nos fluxos de energia e massa (evapotranspira??o/fra??o evaporativa). Para comprovar as mudan?as decorrentes deste processo foi realizada uma an?lise descritiva/comparativa entre dados de ?rea degradada e ?rea com Caatinga preservada (Esta??o Ecol?gica do Serid?-ESEC). Para tanto, utilizou-se de um algoritmo h?brido, o qual ? composto de parametriza??es de v?rios algoritmos tais como: o Surface Energy Balance Algorithms for Land/SEBAL, Simplified Surface Energy Balance/SSEB, Simplified Energy Balance Index/S-SEBI, e de imagens TM ? Landsat 5, das ?rbitas-ponto: 215/65, adquiridas gratuitamente junto ao INPE ? Instituto Nacional de Pesquisas Espaciais ? sob a condi??o de c?u claro, para datas dos anos de 1990, 1995, 1998, 1999, 2001, 2003, 2005, 2007. Comparando os resultados obtidos em ?rea degradada e vegetada, foi observado a exist?ncia de diferen?as entre os valores m?dios do albedo, saldo de radia??o e fra??o evaporativa. Esta diferen?a tamb?m foi comprovada de forma significativa por meio de teste estat?stico (teste t de student), o que corrobora a hip?tese de que o processo de desertifica??o derivado do mau uso do solo e das condi??es clim?ticas da regi?o est? causando altera??es nas vari?veis constituintes do balan?o de energia. / The change in soil cover causes changes in the energy balance and surface water balance. Inadequate soil use can lead to an advanced degradation condition, which is called a desertification process. In Brazil, there are several Desertification Nuclei, among which the Serid? Desertification Nucleus (RN-PB). Thus, the present work started from the premise that the desertification process in the Serid? Potiguar (RN) region has possibly caused variability in surface temperature, albedo, and energy and mass fluxes (evapotranspiration / evaporative fraction). To verify the changes resulting from this process, a descriptive / comparative analysis was carried out between degraded area data and preserved Caatinga area (Serid?-ESEC Ecological Station). For this, a hybrid algorithm was used, which is composed of parametrizations of several algorithms such as: Surface Energy Balance Algorithms for Land / SEBAL, Simplified Surface Energy Balance / SSEB, and S-SEBI, and Of images - Landsat 5, of orbits-point: 215/65, acquired free of charge from INPE - National Space Research Institute - under the condition of clear sky, for dates of 1990, 1995, 1998, 1999, 2001, 2003, 2005, 2007. Comparing the results obtained in degraded and vegetated areas, it was observed the existence of differences between the average values of albedo, radiation balance and evaporative fraction. This difference was also significantly demonstrated by means of a statistical test (student's t test), which corroborates the hypothesis that the desertification process derived from the misuse of the soil and the climatic conditions of the region is causing changes in the constituent variables of the Energy balance.
|
49 |
Politiken bakom FRA-Lagen : Analys ur ett rationellt perspektiv / The Policy Process Behind the FRA-law : A Rational Choice AnalysisThorelius, Daniel, Lidbom, Niklas January 2010 (has links)
Politiken bakom FRA-lagen - Analys ur ett rationellt perspektiv
|
50 |
Construction Of Equivalent Circuit Of A Single Isolated Transformer Winding From Frequency ResponseMukherjee, Pritam 07 1900 (has links) (PDF)
Frequency response analysis (FRA) of transformers is universally accepted as a highly sensitive tool to detect deformations in its windings. This is evident from the fact that customized commercial equipment (popularly called FRA or SFRA instruments) are used and recently the IEEE has issued a draft trial-use guide. Nevertheless, use of FRA is still limited to only detection and there is little progress towards its use for localization of winding deformation. Toward this end, a possible approach would be to compare the healthy and deformed systems in a suitable domain, e.g., their respective models could be compared. In this context, the mutually-coupled ladder network is ideally suited because not only does it map the length of the winding to sections of the ladder network, but, also inherently captures all subtle intricacies of winding behaviour under lightning impulse excitations insofar as the terminal response, internal oscillations and voltage distributions are concerned. The task of constructing a ladder network from frequency response is not trivial, and so exploration of newer methods is imperative.
A system can comprehensively be characterized by its frequency response. With this as the starting point, many approaches exist to construct the corresponding rational function (in s-domain). But, the subsequent step of converting this rational function into a physically-realizable mutually-coupled ladder network has, as yet, remained elusive. A critical analysis of the circuit synthesis literature reveals that there exists no analytical procedure to achieve this task, a fact unequivocally stated by Guillemin in his seminal book "Synthesis of Passive Networks". In recent years, use of iterative methods to synthesize such ladder networks has also been attempted with some degree of success. However, there exists a lot of scope for improvement. Based on this summary, the objectives of this thesis are as follows-
_ Development of an analytical procedure, if possible, to synthesize a mutually-coupled ladder network starting from the s-domain representation of the frequency response
_ Construction of a nearly-unique, mutually-coupled ladder network employing
constrained optimization technique and using frequency response as input, with
time-efficiency, physical realizability and repeatability as its features
In Chapter 2, analytical solution is presented to convert a given driving-point impedance function (in s-domain) into a physically-realizable ladder network with inductive couplings (between any two sections) and losses considered. The number of sections in the ladder network can vary, but, its topology is assumed fixed. A study of the coefficients of the numerator and denominator polynomials of the driving-point impedance function of the ladder network, for increasing number of sections, led to the identification of certain coefficients, which exhibit very special properties. Generalized expressions for these specific coefficients have also been derived. Exploiting their properties, it is demonstrated that the synthesis method essentially turns out to be an exercise of solving a set of linear, simultaneous, algebraic equations, whose solution directly yields the ladder network elements. The proposed solution is novel, simple, and guarantees a unique network. Presently, the formulation can synthesize a unique
ladder network up to 6-sections. Although it is an analytical solution, there are issues which prevent its implementation with actual FRA data.
Keeping the above aspect in mind, the second part of the thesis presents results
of employing an artificial bee colony search algorithm for synthesizing a mutuallycoupled lumped-parameter ladder network representation of a transformer winding, starting from its measured magnitude frequency response. The bee colony algorithm is modified by defining constraints and bounds to restrict the search-space and thus ensure synthesis of a nearly-unique ladder network, corresponding to each frequency response. Ensuring near-uniqueness while constructing the reference circuit (i.e., a uniform healthy winding) is the objective. The proposed method is easy to implement, time-efficient, ensures physical realizability and problem associated with supply of initial guess in existing methods is circumvented. Experiments were performed on two types of actual, single, isolated transformer windings (continuous-disc and interleaveddisc) and the results are encouraging.
Further details are presented in the thesis.
|
Page generated in 0.0782 seconds