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Hydrophobicity classification of polymeric materials based on fractal dimension

THOMAZINI, Daniel; GELFUSO, Maria Virginia; ALTAFIM, Ruy Alberto Corrêa
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
26.03%
This study proposes a new method to obtain hydrophobicity classification (HC) in high voltage polymer insulators. In the method mentioned, the HC was analyzed by fractal dimension (fd) and its processing time was evaluated having as a goal the application in mobile devices. Texture images were created from spraying solutions produced of mixtures of isopropyl alcohol and distilled water in proportions, which ranged from 0 to 100% volume of alcohol (%AIA). Based on these solutions, the contact angles of the drops were measured and the textures were used as patterns for fractal dimension calculations.

Classificação da hidrofobicidade em isoladores elétricos poliméricos de alta tensão; Hydrophobicity classification in high voltage polymeric insulators

Thomazini, Daniel
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 23/01/2009 PT
Relevância na Pesquisa
46.63%
Este trabalho tem como objetivo propor uma metodologia para a classificação da hidrofobicidade (HC) em isoladores elétricos poliméricos de alta tensão. Atualmente a HC esta baseada no guia da STRI (Swedish Transmission Research Institute) elaborado em 1992. Porém neste guia a hidrofobicidade das superfícies de isoladores e classificada de acordo com o angulo de contato e/ou a quantidade de superfície molhada com água de forma subjetiva, através de um operador dependurado em uma torre de transmissão. Desta forma, este trabalho contribuiu na classificação da hidrofobicidade de forma objetiva, onde a analise foi realizada através de processamento digital de imagens. Na metodologia proposta, a HC foi determinada utilizando a analise da textura de imagens obtidas para materiais de isoladores elétricos poliméricos. Essas análises foram avaliadas com base na morfologia matemática, dimensão fractal, entropia, energia, variância e homogeneidade. Foram simuladas imagens (imagens sintéticas) da textura das superfícies dos isoladores utilizando uma placa de silicone e soluções de álcool isopropílico e água destilada (AIA) em proporções que variaram de 0 ate 100% em volume de álcool. A partir destas soluções foram obtidas imagens de gotas sobre as superfícies...

Caracterização da borracha de silicone utilizada em isoladores para rede elétrica

Coser, Eliane
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
26.23%
A borracha de silicone (SR) vem sendo utilizada em isoladores nas linhas de transmissão de energia elétrica e por esta razão, torna-se importante o estudo de sua estabilidade térmica, já que este é um dos fatores que afeta a vida útil do polímero. Este estudo tem como objetivo avaliar o(s) revestimento(s) de borracha de silicone utilizada em isoladores poliméricos que foram submetidos a diferentes tipos de envelhecimentos acelerados tais como névoa salina, temperatura a 120°C, Weatherometer e imersão em água. Os isoladores com invólucros de SR foram envelhecidos e caracterizados quanto às propriedades térmicas por Análise termogravimetrica - TGA e calorimetria diferencial de varredura - DSC, a sua morfologia (por microscopia eletrônica de varredura - MEV) e espectroscopia de infravermelho (FTIR-ATR), sendo comparados com uma amostra não envelhecida. Por estas análises se observa que quanto mais agressivo for o ambiente maior é sua degradação. Os valores de resistência à tração também se observam uma degradação maior a amostra envelhecida termicamente a 140ºC. Para investigar a cinética de degradação térmica do material polimérico foi realizado envelhecimento térmico no material não envelhecido e envelhecido a temperatura de 140ºC (durante seis meses em estufa com circulação de ar). Tal estudo foi realizado utilizando a técnica Termogravimétrica (TGA). A análise cinética foi realizada utilizando o método de Flaynn-Wall-Ozawa e foi possível observar que após o envelhecimento ocorreu uma leve degradação. Foram comparados os resultados de energia de ativação (Ea) e ordem de reação (n) das amostras novas e após o envelhecimento.; The silicone rubber (SR) has been used in insulators on the lines of transmission of electric energy and for this reason...

Effect of artificial aging on polymeric surge arresters and polymer insulators for electricity distribution networks

Ferreira, Carlos Arthur; Coser, Eliane; Angelini, Joceli Maria Giacomini; Rossi, José Antonio Donizete; Martinez, Manuel Luis Barreira
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
46.72%
A study was conducted to evaluate new and laboratory-aged samples of surge arresters and anchorage polymeric insulators, for 12 and 24 kV networks, which are used by the Rio Grande Energia (RGE). Power Utility Polymeric compounds were analyzed by Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TG), Dynamic-Mechanic Analysis (DMA), Fourier Transformed Infrared Spectroscopy (FTIR) and Scanning Electronic Microscopy (SEM) to verify changes in the insulator properties due to degradation occurred during the experiments. The analyses were carried out before and after 6 months of aging in laboratory devices (weatherometer, 120 °C, salt spray, immersion in water). After the aging experiments, high-voltage electrical tests were also conducted: a radio interference voltage test and, simultaneously, the total and the internal leakage currents were measured to verify the surface degradation of the polymeric material used in the housing. The impulse current test was applied with current values close to 5, 10 and 30 kA, in order to force an internal degradation. Results showed that only surface degradation is detected at the polymer. The main properties of the parts were not affected by the aging. It confirms that polymer insulator and surge arrestor are appropriate for use in electricity distribution networks.

Caracterização do efeito corona em isoladores poliméricos do tipo bastão submetidos à poluição salínica

Gianelli, Bruno Fernando
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Dissertação de Mestrado Formato: 73 f. : il.
POR
Relevância na Pesquisa
26.34%
Pós-graduação em Ciência e Tecnologia de Materiais - FC; O acúmulo de sais na superfície de isoladores acarreta a formação de arcos sobre os mesmos, aumentando o processo de corrosão por ácido nítrico. Essa corrosão pode iniciar uma falha da cadeia de isoladores. Atualmente o principal método para análise da corrosão em isoladores, baseia-se em câmaras térmicas e não se tem mostrado adequado para a detecção de defeitos por poluição salínica em seus estágios iniciais. Esse projeto propõe, a adoção de câmeras corona que operam em um comprimento de onda variando entre 240 - 280 nm, filtrando totalmente os raios solares UVA e UVB e permitindo a detecção do ponto aonde se encontra presente a anomalia. Embora as câmeras corona tenham sido amplamente utilizadas, principalmente em linhas de 135 kV até 500 kV, poucos experimentos foram realizados com as mesmas em tensões de 69 kV, tensão padrão da empresa patrocinadora do projeto. Nossa proposta é a de apresentar uma nova metodologia de inspeção utilizando esses equipamentos e possibilitando à empresa incrementar as suas atividades de inspeção.; The accumulation of salt on the surface of insulators causes the formation of arcs, increasing the corrosion process by nitric acid. This corrosion can start a fault of the insulators chain. Presently the main method for corrosion analysis of insulators is based on thermal cameras and is not adequated to detect defects caused by salt pollution on initial stages. This project proposes the adoption of corona cameras operating in wavelengths ranging from 240 to 280 nm...

Silicone insulators of power transmission lines with a variable inorganic load concentration: Electrical and physiochemical analyses

Cardoso, Rodolfo; Balestro, Ana Claudia; Dellallibera, Adriano; Costa, Eduardo Coelho M.; Angelini, Joceli Maria G.; Innocentini Mei, Lucia Helena
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 63-73
ENG
Relevância na Pesquisa
36.63%
Polymeric insulation is an increasing tendency in projects and maintenance of electrical networks for power distribution and transmission. Electrical power devices (e. g., insulators and surge arresters) developed by using polymeric insulation presents many advantages compared to the prior power components using ceramic insulation, such as: a better performance under high pollution environment; high hydrophobicity; high resistance to mechanical, electrical and chemical stresses. The practice with silicone insulators in polluted environments has shown that the ideal performance is directly related to insulator design and polymer formulation. One of the most common misunderstandings in the design of silicone compounds for insulators is the amount of inorganic load used in their formulation. This paper attempts to clarify how the variation of the inorganic load amount affects physicochemical characteristics of different silicone compounds. The physicochemical evaluation is performed from several measurements, such as: density, hardness, elongation, tensile strength. In addition, the evaluation of the physicochemical structure is carried out using infrared test and scanning electronic microscopy (SEM). The electrical analysis is performed from the electric tracking wheel and erosion test...

Comparison of polymers and ceramics in new and discarded electrical insulators: reuse and recycling possibilities

Mantovani, Vanessa Alves; Franco, Camila Silva; Mancini, Sandro Donnini; Haseagawa, Haroldo L.; Gianelli, Bruno Fernando; Batista, Vladimir Xavier; Rodrigues, Luciane Lopes
Fonte: Univ Fed Rio De Janeiro, Lab Hidrogenio Publicador: Univ Fed Rio De Janeiro, Lab Hidrogenio
Tipo: Artigo de Revista Científica Formato: 1549-1562
ENG
Relevância na Pesquisa
36.63%
The expansion and maintenance of electricity distribution networks generates large amounts of waste, much of it in the form of discarded insulators that are not reused or recycled. This paper describes the results of tests on used and new ceramic and polymeric insulators to verify if their exposure to weathering justifies their replacement. In new and used ceramic insulators, properties such as contact angle, relative density, porosimetry, dilatometry and X-ray diffraction patterns showed no differences or the differences that were found could not be related to their use. The discarded ceramic material showed high thermal stability, an interesting characteristic for application as chamotte. It can also be reused to replace gravel used in substations. In polymeric insulators, thermogravimetry, differential scanning calorimetry and relative density test results suggest degradation of used material compared to new. This would justify their replacement and discard as waste, but they show little recycling potential.

Desenvolvimento de requisitos de desempenho para elastomeros de isoladores da rede de energia eletrica; Development of performance requirements for elastomers insulators of electricity network

Fabio Noronha
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 22/02/2010 PT
Relevância na Pesquisa
46.79%
Atualmente, os materiais utilizados como isoladores elétricos vêm sendo substituídos por materiais poliméricos por apresentarem vantagens em relação aos isoladores cerâmicos. Dentre estas vantagens, podem-se citar maior desempenho, melhor resistência ao vandalismo e menor peso. O objetivo desta dissertação foi o estabelecimento de desenvolver requisitos de desempenho para os Isoladores Poliméricos (EPDM- Monômero Dieno/Etileno/Propileno e Silicone) usados na rede elétrica, através de resultados obtidos em ensaios de envelhecimento natural e artificial, tendo como enfoque as linhas de transmissão de 69 kV e 138 kV. Foi realizado um estudo do estado da arte em Isoladores Poliméricos e do estado atual de aplicação e desempenho dos mesmos em campo. Estudos experimentais foram desenvolvidos em produtos retirados de campo e produtos novos, envelhecidos artificialmente em laboratório, segundo metodologias aplicáveis a polímeros. Em paralelo foram estudadas mantas elastoméricas de Silicone e EPDM para elaboração de critérios comparativos. Através dos resultados obtidos, foram sugeridos alguns requisitos de desempenho que poderão ser utilizados em especificações dos mesmos. Nesta dissertação, são apresentados...

Triboeletrização : evidências da participação de reações mecanoquimicas; Triboelectrification : evidences for the participation of mechanochemical reactions

Lia Beraldo da Silveira Balestrin
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 12/02/2015 PT
Relevância na Pesquisa
26.42%
Quando dois materiais isolantes são atritados, ocorre a triboeletrização de suas superfícies, isto é, a formação de cargas estáticas, distribuídas em padrões fractais. Uma das hipóteses para explicar a eletrização de isolantes é a ocorrência de reações mecanoquímicas seguidas da transferência mútua de massa. Esta dissertação apresenta mapas de potencial elétrico de superfícies atritadas, que também foram examinadas por microscopia eletrônica de varredura (SEI, BEI) e microanálise EDX. Os resultados verificam a hipótese mecanoquímica associada à transferência de fragmentos poliméricos iônicos, sendo as reações iniciadas pela quebra de cadeias seguida da formação de várias espécies de alta energia e produtos de oxidação. Microanálises também detectaram a fixação de N2 nestas superfícies, evidenciando a participação da atmosfera e a formação de triboplasma. As imagens BEI revelam uma distribuição fractal de composição química consistente com a distribuição de fragmentos limitada por difusão, mas superior à dimensão fractal de distribuição de cargas. Esta diferença é atribuída à supressão de cargas devido a microdescargas elétricas desencadeadas por gradientes superiores à rigidez dielétrica do sólido ou do ar. As microdescargas diminuem os gradientes elétricos...

Electrical ageing studies of polymeric insulation for power cables (estudo do envelhecimento eléctrico do isolante polimérico de cabos eléctricos

Lança, Maria do Carmo Henriques
Fonte: Faculdade de Ciências e Tecnologia Publicador: Faculdade de Ciências e Tecnologia
Tipo: Tese de Doutorado
Publicado em //2002 ENG
Relevância na Pesquisa
26.23%
Dissertação apresentada para obtenção do Grau de Doutor em Engenharia Física - Física Aplicada pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia; Polymers have been widely used as electrical insulators in power cables. Polyethylene, initially low density and more recently crosslinked, are one of the more commonly used insulators in medium and high voltage power cables. They suffer electrical ageing in different forms, such as water treeing, electrical treeing and finally dielectric breakdown. The last one leading to costly cable failure. Many research works have been developed on this subject despite of the progress made up to now, results are still sometimes contradictory and difficult to reproduce. Any new insight into this problem is a step further in preventing failure of the cables and increasing their useful lifetime. The aim of this thesis was to relate ageing in two different aspects of electrical ageing: localised damage and changes in bulk properties of the polyethylene. For this different experimental techniques were used. Localised damage was water treeing and breakdown channels since no electrical trees were observed. The methods used for this study were FTIR,estimation of fractal dimension of water trees and statistics of dielectric breakdown. The changes of electric and dielectric bulk properties were accessed using mostly DRS...

Effect of artificial aging on polymeric surge arresters and polymer insulators for electricity distribution networks

Ferreira,Carlos A.; Coser,E.; Angelini,Joceli M. G.; Rossi,José A. D.; Martinez,Manuel L. B.
Fonte: Associação Brasileira de Polímeros Publicador: Associação Brasileira de Polímeros
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
Relevância na Pesquisa
46.72%
A study was conducted to evaluate new and laboratory-aged samples of surge arresters and anchorage polymeric insulators, for 12 and 24 kV networks, which are used by the Rio Grande Energia (RGE). Power Utility Polymeric compounds were analyzed by Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TG), Dynamic-Mechanic Analysis (DMA), Fourier Transformed Infrared Spectroscopy (FTIR) and Scanning Electronic Microscopy (SEM) to verify changes in the insulator properties due to degradation occurred during the experiments. The analyses were carried out before and after 6 months of aging in laboratory devices (weatherometer, 120 °C, salt spray, immersion in water). After the aging experiments, high-voltage electrical tests were also conducted: a radio interference voltage test and, simultaneously, the total and the internal leakage currents were measured to verify the surface degradation of the polymeric material used in the housing. The impulse current test was applied with current values close to 5, 10 and 30 kA, in order to force an internal degradation. Results showed that only surface degradation is detected at the polymer. The main properties of the parts were not affected by the aging. It confirms that polymer insulator and surge arrestor are appropriate for use in electricity distribution networks.

The effects of fillers on polyurethane resin-based electrical insulators

Altafim,Ruy Alberto Corrêa; Murakami,Cacilda Ribeiro; Claro Neto,Salvador; Araújo,Luiz Carlos Ribeiro; Chierice,Gilberto Orivaldo
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2003 EN
Relevância na Pesquisa
46.63%
The increasingly widespread use of polymeric insulators in vehicle distributors and transmission systems has led to an ongoing quest for quality and low costs. This quest has, in turn, resulted in improved performance and cost benefits, brought about by the use of new polymeric and composite resins. Occasionally, however, while some properties are improved, others may show a loss of optimal performance. Therefore, to understand the behavior of fillers, such as carbon black, silica and mica added to castor oil-derived polyurethane resins, several thermal, mechanical and electrical tests were conducted on samples and insulators produced specifically for this purpose, using these new materials. The results of these tests clearly demonstrated that this type of resin and its composites can be used to manufacture indoor electrical insulators and that the fillers analyzed in this study improve or maintain the characteristics of the pure resins.

Hydrophobicity classification of polymeric materials based on fractal dimension

Thomazini,Daniel; Gelfuso,Maria Virginia; Altafim,Ruy Alberto Corrêa
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
Relevância na Pesquisa
26.03%
This study proposes a new method to obtain hydrophobicity classification (HC) in high voltage polymer insulators. In the method mentioned, the HC was analyzed by fractal dimension (fd) and its processing time was evaluated having as a goal the application in mobile devices. Texture images were created from spraying solutions produced of mixtures of isopropyl alcohol and distilled water in proportions, which ranged from 0 to 100% volume of alcohol (%AIA). Based on these solutions, the contact angles of the drops were measured and the textures were used as patterns for fractal dimension calculations.

Development and characterization of composite materials for production of composite risers by filament winding

Sobrinho,Ledjane Lima; Calado,Verônica Maria de Araújo; Bastian,Fernando Luiz
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2011 EN
Relevância na Pesquisa
16.37%
Industry has been challenged to provide riser systems which are more cost effective and which can fill the technology gaps with respect to water depth, riser diameter and high temperatures left open by flexibles, steel catenary risers (SCRs) and hybrid risers. Composite materials present advantages over conventional steel risers because composite materials are lighter, more fatigue and corrosion resistant, better thermal insulators and can be designed for improving the structural and mechanical response. This paper contains a study of the toughening mechanism of an epoxy resin under rubber addition by means of fractographic analysis and its relation with the fracture process and increase of strength of a composite riser employing this polymeric matrix. Initially, an epoxy resin system was toughened by rubber CTBN addition (10 wt. (%)) as a way of improving the flexibility of future risers. Mechanical and thermal analyses were carried out for characterizing the polymeric systems. Later, composite tubes were prepared and mechanically characterized. The influence of matrix toughening on the mechanical behavior of the tubes was also studied. Split-disk tests were used to determine the hoop tensile strength of these specimens. The results indicate that the matrix plays an important role in composite fracture processes. The adding rubber to the polymeric matrix promoted a simultaneous increase of stress and elongation at fracture of the tubes manufactured herein...

Comparison of polymers and ceramics in new and discarded electrical insulators: reuse and recycling possibilities

Mantovani,Vanessa Alves; Franco,Camila Silva; Mancini,Sandro Donnini; Haseagawa,Haroldo L; Gianelli,Bruno Fernando; Batista,Vladimir Xavier; Rodrigues,Luciane Lopes
Fonte: Rede Latino-Americana de Materiais Publicador: Rede Latino-Americana de Materiais
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 EN
Relevância na Pesquisa
36.63%
The expansion and maintenance of electricity distribution networks generates large amounts of waste, much of it in the form of discarded insulators that are not reused or recycled. This paper describes the results of tests on used and new ceramic and polymeric insulators to verify if their exposure to weathering justifies their replacement. In new and used ceramic insulators, properties such as contact angle, relative density, porosimetry, dilatometry and X-ray diffraction patterns showed no differences or the differences that were found could not be related to their use. The discarded ceramic material showed high thermal stability, an interesting characteristic for application as chamotte. It can also be reused to replace gravel used in substations. In polymeric insulators, thermogravimetry, differential scanning calorimetry and relative density test results suggest degradation of used material compared to new. This would justify their replacement and discard as waste, but they show little recycling potential.

Desenvolvimento de metodologia para análise de arborescências em materiais dielétricos por contraste de fase de raios X

Ribeiro Júnior, Sebastião
Fonte: Curitiba Publicador: Curitiba
Tipo: Tese de Doutorado
POR
Relevância na Pesquisa
26.03%
The water tree or electrical tree occurrence is identified as the main phenomena in the degradation in solid isolations of the electric energy distribution cables. The water tree evolution can lead to dielectric breakdown of the isolation layer and, consequently, to the failure this equipment and the interruption of the electric energy supply. The understanding this phenomenon is necessary for the development analysis methods and to prevent collapse in the polymeric insulation. This work demonstrates the application of X-ray phase contrast technique as a methodology for the study of the water tree and electrical tree in Ethylene propylene rubber (EPR) and crosslinked polyethylene (XLPE).; A ocorrência de arborescências em água (water tree) ou elétrica (electrical tree) é apontada como o principal fenômeno de degradação em isolações sólidas de cabos de distribuição de energia elétrica. A evolução destas arborescências pode levar a camada de isolação à ruptura dielétrica e, como conseqüência, à falha destes equipamentos, com a interrupção do fornecimento de energia elétrica. O entendimento deste fenômeno é necessário para desenvolver métodos de análise e prevenção da ruptura de materiais isolantes. Este trabalho mostra a aplicação da técnica contraste de fase por raios X como metodologia para o estudo das arborescências formadas em materiais isolantes de borracha de propileno etileno (EPR) e polietileno reticulado (XLPE).

Classification of polymers insulators hydrophobicity basead on digital image processing

Thomazini, Daniel; Gelfuso, Maria Virginia; Altafim, Ruy Alberto Corrêa
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.41%
Although the hydrophobicity is usually an arduous parameter to be determined in the field, it has been pointed out as a good option to monitor aging of polymeric outdoor insulators. Concerning this purpose, digital image processing of photos taken from wet insulators has been the main technique nowadays. However, important challenges on this technique still remain to be overcome, such as; images from non-controlled illumination conditions can interfere on analyses and no existence of standard surfaces with different levels of hydrophobicity. In this paper, the photo image samples were digitally filtered to reduce the illumination influence, and hydrophobic surface samples were prepared from wetting silicon surfaces with solution of water-alcohol. Furthermore norevious studies triying to quantify and relate these properties in a mathematical function were found, that could be used in the field by the electrical companies. Based on such considerations, high quality images of countless hydrophobic surfaces were obtained and three different image processing methodologies, the fractal dimension and two Haralick textures descriptors, entropy and homogeneity, associated with several digital filters, were compared. The entropy parameter Haralick's descriptors filtered with the White Top-Hat filter presented the best result to classify the hydrophobicity.

Classification of polymers insulators hydrophobicity basead on digital image processing

Thomazini,Daniel; Gelfuso,Maria Virginia; Altafim,Ruy Alberto Corrêa
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2012 EN
Relevância na Pesquisa
36.41%
Although the hydrophobicity is usually an arduous parameter to be determined in the field, it has been pointed out as a good option to monitor aging of polymeric outdoor insulators. Concerning this purpose, digital image processing of photos taken from wet insulators has been the main technique nowadays. However, important challenges on this technique still remain to be overcome, such as; images from non-controlled illumination conditions can interfere on analyses and no existence of standard surfaces with different levels of hydrophobicity. In this paper, the photo image samples were digitally filtered to reduce the illumination influence, and hydrophobic surface samples were prepared from wetting silicon surfaces with solution of water-alcohol. Furthermore norevious studies triying to quantify and relate these properties in a mathematical function were found, that could be used in the field by the electrical companies. Based on such considerations, high quality images of countless hydrophobic surfaces were obtained and three different image processing methodologies, the fractal dimension and two Haralick textures descriptors, entropy and homogeneity, associated with several digital filters, were compared. The entropy parameter Haralick's descriptors filtered with the White Top-Hat filter presented the best result to classify the hydrophobicity.

Hydrophobicity Classification of Polymeric Insulators Based on Embedded Methods

Dong,Zhengcheng; Fang,Yanjun; Wang,Xianpei; Zhao,Yu; Wang,Quande
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2015 EN
Relevância na Pesquisa
46.42%
Hydrophobicity is an important parameter to characterize electrical properties of insulated materials. Therefore, it is an urgent task to develop on-line instruments to identify the hydrophobicity of insulated material's surface conveniently, quickly and accurately. For this purpose, a novel evaluation system with image processing and decision tree is proposed which is based on embedded platform. For obtaining satisfactory results, we first propose a mixed image segmentation method to overcome the complex conditions outside, concerning non-controlled illumination, nonstandard surfaces and unfixed shooting angle. Then we adopt four new characteristic parameters to describe the image of each sample. Finally, a classification method based on MultiBoost decision tree is conducted which synthesizes the merits of both AdaBoost and Wagging algorithm. Results indicate the procedures can be applied in the DSP (Digital Signal Processor) platform perfectly and better results can be obtained than those did in our previous study or that of some other research.

Use of electron paramagnetic resonance to evaluate the behavior of free radicals in irradiated polyolefins

Silva,Pedro; Albano,Carmen; Perera,Rosestela
Fonte: Universidad Simón Bolívar; ; Publicador: Universidad Simón Bolívar; ;
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
Relevância na Pesquisa
16.37%
The Electron Paramagnetic Resonance (EPR) had its most important development at the end of World War II. It is a non destructive technique of characterization and is the technique used for excellence to detect and characterize free radicals. It is well known that the presence of free radicals in polymeric materials is responsible for the appearance of a variety of effects in the polymer chains. There are, fundamentally, two ways for the generation of free radicals in a polymeric chain: chemical methods and irradiation with electromagnetic waves of medium and high energy. Gamma and x-rays produce ionization in all solids. In insulators and polymers chemical reactions may be promoted, some of which cannot be induced by other means. These last methods have the advantage that they do not leave polluting agents into the polymer. EPR has been used to interpret quantitatively and qualitatively the free radicals generated by the irradiation of polymeric materials. EPR results from different polymers and polymeric blends irradiated with gamma irradiation at low dose rates will be presented in this article. The behavior of allyl, alkyl, peroxide and polyenyl radicals, among others, is studied using a decay model.