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Doctoral Thesis
DOI
https://doi.org/10.11606/T.76.2000.tde-09042008-135129
Document
Author
Full name
Sandra Cristina Costa
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2000
Supervisor
Committee
Ferreira, Guilherme Fontes Leal (President)
Alfaro, Renê Armando Moreno
Faria, Roberto Mendonça
Lepienski, Carlos Mauricio
Studart Filho, Nelson
Title in Portuguese
Condutividade e movimento de carga espacial em amostras desordenadas
Keywords in Portuguese
Meios dispersivos
Método de Widder
Respostas dielétricas
Substituição funcional
Transformadas inversas de Laplace
Abstract in Portuguese
Na condução por saltos dispersiva, os portadores de carga são caracterizados por tempos de residência não exponenciais. Como uma conseqüência, efeitos hereditários aparecem e o problema deve ser conduzido no espaçõ de Laplace. Distribuições dielétricas conhecidas e algumas outras foram usadas como possíveis funções capazes de descrever o meio desordenado. Um estudo cuidadoso de seus espectros de freqüência foi realizado. O método de inversão de Widder truncado foi desenvolvido para possibilitar a volta do espaço de Laplace para o do tempo real. Dois tipos de problemas práticos foram abordados: condução dispersiva na qual o campo elétrico das cargas móveis pode ser desprezado e o caso de carga espacial para o qual essa aproximação não pode ser feita. Duas configurações de interesse foram escolhidas: decaimento do potencial de superfície de amostras carregadas por descarga corona e a subida do potencial no carregamento por corrente constante.
Title in English
Conductivity and charge displacement in disordered samples
Keywords in English
Dielectric response
Dispersive media
Inverse Laplace transform
Widder method
Abstract in English
Dispersive conductive process are characterized by non-exponential residence times of the hopping carrier. As a consequence, hereditary effects appear and the problem must be conducted in the Laplace space. A bunch of known dielectric distributions functions and others were used as possible functions describing the disordered medium. A careful study of their frequency spectrum was carried out. The truncate Widder inversion was developed in order to allow returning from the Lapace to the real time space. Two kind of practical problems were studied: dispersive conduction in which the electric field of the mobile charge may be neglected and the space charge ones when that approximation cannot be made. Two configurations of interest were selected: the corona discharge potential decay and the constant current potentinal build-up.
 
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SandraCosta_D.pdf (2.17 Mbytes)
Publishing Date
2008-04-17
 
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