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High Voltage 2021年第1期6卷 82-94页

作者： johnatan m.rodríguez‐serna Ricardo Albarracín‐Sánchez Department of Electrical and Electronic Engineering Automatic Controland Applied PhysicsSchool of Industrial Design and Engineering(ETSIDI)Universidad Politécnica de Madrid(UPM)MadridSpain Department of Electrical Engineering Universidad de AntioquiaMedellínColombia

Electrical trees are defects originated and driven by partial discharges(PD)activity and this is the reason why their modelling and simulation are fundamental for the ageing mechanisms comprehension and diagnosis analyses of insulation systems compound by solid dielectrics.This study presents a brief review of the different models implemented to simulate PD in electrical trees inside solid dielectrics.In addition,an improved deterministic model as well as a stochastic model are presented,which allow predicting adequately the PD pulses distribution,in magnitudes and phase,for non‐conducting electrical trees of different shape and length.Two case studies were simulated and their results exhibit good agreement when compared with measurements presented in the literature.It is concluded that the main parameters that state the PD behaviour in trees are the inception and extinction voltage mag-nitudes,including their probability distributions,and the tree geometry.The models can be used for prognosis analysis based on on‐line measurements.

关键词： solid conducting electrical

Finite-element-analysis models for numerical simulation of partial discharges in spherical cavities within solid dielectrics:a review and a novel method

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High Voltage 2020年第5期5卷 556-568页

作者： johnatan m.rodríguez-serna Ricardo Albarracín-Sánchez Abdullahi A.mas'ud Department of Electrical and Electronic Engineering Automatic Controland Applied PhysicsSchool of Industrial Design and Engineering(ETSIDI)Universidad Politécnica de Madrid(UPM)Ronda de Valencia 328012MadridSpain 2Department of Electrical EngineeringUniversidad de AntioquiaCalle 67 No.53-108MedellínColombia 3Department of Electrical and Electronic Engineering TechnologyJubail Industrial College31961JubailSaudi Arabia

During the last two decades,partial discharges(PDs)modelling methods have been used as a complement of insulation diagnosis systems of electrical assets.Finite-element-analysis models for simulating PDs in cavities within solid dielectric materials are reviewed and a novel model is presented,which combines the main advantages of electrostatic and electric current models.The theoretical background is presented and some limitations and restrictions are discussed.A case of study was implemented for three different ageing conditions and simulation results exhibit good agreement with reported values by other authors in the literature.An analysis of variations of PD behaviour with ageing as a function of temperature and pressure is briefly presented.It is concluded that more research is needed to include physical and chemical interactions on the void surface and that the cavity surface conductivity plays a fundamental role in the PD simulations at advanced ageing conditions.

关键词： element analysis solid

Where Are the Bromeliads? A Study on Different Trails in the Ecological Reserve of Guapiaçu, RJ

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Agricultural Sciences 2023年第2期14卷 196-201页

作者： johnatan Jair de Paula marchiori Vinicius de Souza Oliveira Gilcéa Teixeira Fontana Boone Luan Luciano dos Santos Pereira Natália Cristina Barbosa moura Ana Beatriz mamedes Piffer Anderson mathias Holtz Lusiane de Sousa Ferreira Raquel Cetto Sampaio Federal Rural University of Rio de Janeiro Seropédica Brazil Center for Agricultural Sciences and Engineering Federal University of Espírito Santo Alegre Brazil Campus Itapina Federal Institute of Espírito Santo Colatina Brazil State University Paulista “Júlio de mesquita Filho” Botucatu Brazil

Bromeliaceae are important in ecological restoration, showing easy adaptation to different environments, and constantly interacting with each other through ecological relationships, whose effects may or may not benefit the species involved. The hypothesis tested whether the population density of Hohenbergia augusta is higher in areas at a more advanced successional stage (brown trail), since the species is typical of more structured forest environments, occurring especially in the lower strata of the forest. Six plots of 10 meters (6 × 10 m) were installed, parallel to the brown and yellow trails, and with a distance of 5 m from the edge. Plots were allocated alternately between the two sides of the trail, 10 meters apart from each other when on the same side. In each plot, all H. augusta (Vell.) E. morren bromeliads were sampled, without a minimum inclusion criterion, provided they were epiphytic phorophytes. The logarithm of the value was used for data normalization and later, the data were tested in a student’s t-test. The study pointed out that the highest population density of H. augusta occurred in the brown trail because the area is in a more advanced successional stage.

关键词： Bromeliads Atlantic Forest Ecological Restoration

What Do Seedlings Like? The Relationship between Seedling Richness and Abundance with Abiotic Factors

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Agricultural Sciences 2023年第6期14卷 767-774页

作者： johnatan Jair de Paula marchiori Vinicius de Souza Oliveira Eduarda Carriço Ana Clara Bayer Bernabé Anderson mathias Holtz Ronilda Lana Aguiar Ana Beatriz mamedes Piffer Gilcéa Teixeira Fontana Boone Ricardo Amaro de Sales Lusiane de Sousa Ferreira Department of Environmental Sciences/Phytotechnics Department Federal University Rural of Rio de Janeiro-Seropédica Rio de Janeiro Brazil Center for Agricultural Sciences and Engineering Federal University of Espírito Santo Alegre Espírito Santo Brazil Laboratory of Entomology and Acarology Federal Institute of Espírito Santo Campus Itapina Colatina Espírito Santo Brazil Agriculture Department State University Paulista “Júlio de Mesquita Filho” Botucatu S&#227o Paulo Brazil

Natural regeneration is the interaction of natural processes to restore the forest ecosystem. Its dynamics are influenced by the intensity and extent of a series of abiotic and biotic factors, which may be intrinsic or extrinsic. Knowing the importance of establishing natural regeneration within forest ecosystems, this work aimed to evaluate whether litter depth and trail distance influenced seedling abundance and richness in a forest fragment undergoing natural restoration. The hypothesis tested in this research was that abiotic factors influence the natural regeneration of this forest since they are factors that are directly linked to seed germination and seedling establishment. 30 plots of 1 m2 were randomly analyzed within the forest located on the brown trail. A millimeter ruler was used to diagnose the litter depth and a measuring tape to measure the distance from the plot to the edge. In each plot the seedlings were morpho-specified and each morphospecies had the number of individuals counted. Linear regression tests were performed to assess the relationships between species richness and trail distance and litter depth. The same was done for species abundance. All results showed that there is no relationship pattern between any of the variables. Other factors also influence the regeneration of a forest, such as luminosity and seed bank. Furthermore, litter depth is related to the successional stage of the forest. It was concluded that the abiotic factors tested do not influence the regeneration of the study area.

关键词： Abiotic Factors Natural Regeneration Forest Ecosystem