Marcio Mesquita

Three‐dimensional finite element analysis of stress distribution in peri‐implant bone with relined dentures and different heights of healing caps

The purpose of this study was to evaluate the influence of height of healing caps and the use of soft liner materials on the stress distribution in peri-implant bone during masticatory function in conventional complete dentures during the healing period by using finite element analysis. Three-dimensional models of a severely resorbed mandible with two recently placed implants in the anterior region were created and divided into the following situations: (i) submerged implants, (ii) healing cap at gingival level and (iii) 1·5-mm supragingival. All these situations were also analysed for a conventional complete denture and a denture relined with a 3-mm-thick layer of soft liner material. The models were exported to mechanical simulation software that presented two simulations, one with load in the inferior right canine (35 N) and the other in the inferior right first molar (50 N). Data were evaluated using Maximum Principal Stress provided by the software. All models showed a stress concentration in the cortical bone corresponding to the cervical part of the implant. The simulations with non-submerged implants showed higher values of stress concentration than those that were submerged. Likewise, soft liner materials presented better results than when the denture base was not relined. The height of the healing caps seems to have a direct influence on the stress distribution in the peri-implant bone during the healing period. Considering the values obtained in this study, the use of soft liners with submerged implants seems to be the most suitable method to use during the period of osseointegration.

Processo da retrolavagem em filtros de areia usados na irrigação localizada

O processo da retrolavagem consiste na passagem da agua atraves do filtro em sentido contrario ao fluxo de filtragem com o objetivo de remover particulas orgânicas e inorgânicas retidas no meio filtrante. O projeto de filtros de areia com configuracoes ineficientes e a ocorrencia de condicoes operacionais inadequadas contribuem para limitar o desempenho desse processo, causando deficiencias na limpeza dos meios filtrantes e comprometendo o funcionamento dos sistemas de irrigacao localizada. O objetivo do presente trabalho e proporcionar uma revisao sobre os conceitos associados ao processo da retrolavagem nos filtros de areia, relacionando informacoes existentes na literatura com experiencias de laboratorio. Foi gerado um texto basico com informacoes tecnico-cientificas sobre o tema, visando a criar um momento de reflexao sobre o processo de retrolavagem e a contribuir para a melhoria do desempenho desses equipamentos na irrigacao localizada.

Aplicação de túnel de vento na avaliação de linhas de fluxo geradas por crepinas de filtros de areia

Looking for technical information to improve the hydraulic efficiency in sand filters during the filtering and backwash processes, this project had the objective to evaluate a teaching wind tunnel as a reliable method to visualize and characterize flow lines distribution generated by the interaction of a specific model of underdrain with different flow velocities. The experiment was performed by installing a commercial underdrain model, cylinder type, in an experimental section specially constructed to be coupled to a vertical wind tunnel. Three flow rate values were simulated in the tunnel, obtaining high-speed photographs. The obtained images were treated to highlight the flow lines distribution and preferred flow pathways for the filtration and backwash processes. The wind tunnel operating range was correlated by similarity with values of water flow rate in filtration processes carried out in commercial sand filters with diameters of 40, 60 and 100 cm. The obtained results validated the proposed methodology, allowing the visualization and analysis of the underdrain geometry effects on the generated flow lines, for both filtration and backwash processes.

Contribuição da estrutura interna na perda de carga de filtros de areia utilizados na irrigação

A dinâmica de operacao dos filtros de areia afeta o desempenho hidraulico do sistema de irrigacao, elevando a perda de carga e alterando a altura manometrica total do sistema. Buscando entender parte dessa dinâmica, o objetivo deste trabalho foi determinar o efeito da estrutura interna de filtros de areia na perda de carga de tres modelos de equipamentos fabricados no Brasil, sem a presenca do elemento filtrante e utilizando agua limpa. Adicionalmente, com o ajuste do modelo matematico exponencial aos dados experimentais, procurou-se estabelecer comparacoes entre os tipos de estrutura dos filtros avaliados. Os ensaios foram realizados em um modulo experimental construido no Laboratorio de Hidraulica e Irrigacao da FEAGRI/UNICAMP. Os resultados mostraram que a estrutura hidraulica interna dos filtros determinou comportamentos hidraulicos diferenciados e que os tipos de estruturas (placa difusora e drenos) alteraram o padrao de operacao dos modelos ensaiados. A funcao matematica proposta representou, significativamente, o fenomeno fisico de perda de carga para as condicoes do experimento.

Efeito das dimensões da placa difusora no comportamento hidráulico de um modelo comercial de filtro de areia

O objetivo deste trabalho foi avaliar o efeito da mudanca da forma e das dimensoes da placa difusora de um filtro de areia comercial sobre a perda de carga gerada pelo equipamento, quando submetido ao escoamento no sentido de filtracao, sob as condicoes de filtro vazio e na presenca da camada filtrante. Comparou-se o comportamento hidraulico da placa difusora original do equipamento com placas do tipo plano, com bordas com diferentes dimensoes. Os ensaios foram conduzidos em um modulo experimental construido no Laboratorio de Hidraulica e Irrigacao da FEAGRI/UNICAMP, utilizando quatro combinacoes de dimensoes de placa difusora e para taxas de filtracao com valores de 40; 60; 80 e 100 m3 h-1 m-2. Os resultados mostraram que as placas difusoras propostas nao modificaram estatisticamente os valores de perda de carga na faixa recomendada de operacao de filtros de areia (ate 60 m3 m-2 h-1), mas proporcionaram menores deformacoes na camada superficial de areia, fato que contribui para a diminuicao dos caminhos preferenciais da agua, podendo melhorar a eficiencia de remocao do equipamento. A pesquisa demonstrou a existencia de interacao entre o modelo de placa difusora utilizada em filtros de areia e o revolvimento da superficie da camada de areia.

Influência do tempo de uso sobre as características hidráulicas do microaspersor do grupo modular

The development of new irrigation equipments and the improvement of the already existent, as the microsprinkler, demand to evaluate the hydraulic characteristics as well as the appropriate installation in the field conditions to obtain higher indexes of the water distribution uniformity. This work had the objective to obtain the discharge x pressure equation, the manufacturing variation coefficient - CVf and the discharge variation coefficient - CVq, water distribution uniformity for different overlap degrees of the microsprinkler of the modulate group, orange nozzle, new and used, installed in the upside-down at 1.20 m above laboratory ground. The increase of the spacing among microsprinkler and lateral reduced the uniformity indexes for all of the pressures for the new and the used microsprinkler. The high jet concentration occurred in the range from 0.0 to 1.0 m of the support rod of the new and used microsprinkler. The wetted area by the used microsprinkler was smaller than the new one.

Performance of leak-preventing device and microsprinkler

In the last years new models of devices were introduced for greenhouse cultivation, as the leak-preventing device and microsprinkler, it is needed to evaluate their performance. So the objective of this work was to evaluate the hydraulic performance of new and used leak-preventing device, under low and high pressure in microsprinkler of modular group and Hadar model. The CVf and CVq of the microsprinkler and the leak-preventing device of low pressure only the microsprinkler of modular group were classified as bad or unacceptable and the new high pressure as unacceptable. The leak-preventing device Hadar presented the best performance for all the performances. The leak-preventing device opened in low pressures as indicated by their manufacturers. The long time using interfered in the performance of the leak-preventing device of low pressure modular group, being the new model which presented smaller values of CVf for the opening and closing pressure.