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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Investigating the Effects of Mechanical Damage on the Electrical Response of Li-ion Pouch Cells

Stacy, Andrew January 2019 (has links)
Li-ion batteries (LIB) are used in many applications because of their high-power/energy density, long life cycling, and low self-discharge rate. The use of LIB continues to grow every day, and the necessity for proper safety standards grows as well. A key aspect for safe utilization of LIB is determining their safety and remaining useful life (RUL). Battery characteristics degrade over time under normal and extreme operating conditions and modeling the electrochemical processes can improve RUL estimations. Extreme operating conditions such as abnormal temperatures and charge/discharge rates are believed to exacerbate the rate of degradation. Li-ion batteries are also susceptible to mechanical damage, which may lead to an electrical short. In severe cases, mechanical damage causes a thermal run away, and possibly explosions or fires. In the event of a car accident, battery packs can be damage without an electrical short or immediate thermal run away. Currently, there is no reliable batt / Mechanical Engineering
12

Mapování a metodika zvládání somatických komplikací injekčních uživatelů drog / Mapping and metodological management of physical complications of injecting drug users

Spůrová, Nikol January 2014 (has links)
BACKGROUND: Drug abuse is a social problem with psychosocial and physical complications. The lifestyle of injection drug users (IUD) increases the risk of infectious as well as of non-infectious diseases. The workers of low-threshold programmes are often the first ones to encounter the physical complications of injection drug users, and the workers are accordingly often the ones who take the initiative in dealing with those complications. Mapping the possible solutions of injection drug users' complications by the workers of low-threshold programmes would respond to the needs for methodological approach widely available to the workers of low-threshold programmes. AIMS: The present thesis aims to describe the possible solutions to physical complications of injection drug users through mapping the solutions in the practice of the low-threshold programmes workers for drug users in Prague. SAMPLE: All the seven low-threshold programmes facilities based in Prague were appealed to participate on the research. Thirty eight respondents participated in the study (39 % outreach programs, 53 % drop-in centre, 8 % combined services) METHODS: The present research was carried out via questionnaire research. The output data was analysed through descriptive statistics. The standardized questions of the...
13

[en] VISUALIZATION OF FLUID FLOW IN POROUS MEDIA BY X-RAY MICROTOMOGRAPHY FOR OIL RECOVERY / [pt] AVALIAÇÃO POR MICROCT DE MUDANÇAS MICROESTRUTURAIS EM ROCHAS SUBMETIDAS A ESFORÇOS MECÂNICOS

FRANCISCO JOSE RODRIGUES DA SILVA JUNIOR 12 June 2019 (has links)
[pt] Na indústria do petróleo, problemas como dano mecânico causam redução da porosidade e permeabilidade de uma formação rochosa, reduzindo a produtividade e injetividade de poços de sistemas de produção de óleo e gás. Na perfuração do poço há alteração do estado de tensões no seu entorno, causando uma deformação na rocha que pode induzir a uma perda significativa da permeabilidade. Nesta dissertação foi realizado um estudo da influência do dano mecânico na porosidade de rochas do tipo arenito. Para isso, utilizou-se a técnica não-destrutiva de microtomografia de raios-x, que permite a visualização da estrutura interna de materiais, acoplada a uma célula desenvolvida para aplicação, in situ, de tensão hidrostática. Uma amostra de arenito como 8 mm de diâmetro foi tomografada em 3 condições: sem carregamento, após a aplicação de tensão hidrostática de 3300 psi e após o descarregamento. A célula permitiu que as variações de carga fossem realizadas sem retirar a amostra do tomógrafo, permitindo uma comparação quantitativa entre as imagens 3D. Nas 3 condições foram obtidos dados como porosidade total, variação da área porosa em cada camada, volume e forma dos poros. / [en] In the oil industry, problems such as mechanical damage reduce the porosity and permeability of a rock formation, reducing the productivity and injectivity of wells in oil and gas production systems. During the well drilling there is a change in the state of the stress in its surroundings, causing a deformation in the rock that can induce a significant loss of permeability. In this dissertation, it was carried out a study regarding the influence of mechanical damage on the porosity of sandstone rocks. In order to do this, the non-destructive technique of x-ray microtomography was used, which allows the visualization of the materials internal structure, coupled to a cell developed for in situ application of hydrostatic stress. A sandstone sample of 8 mm in diameter was scanned under 3 conditions: without load, after application of 3300 psi hydrostatic stress and after unloading. The cell allowed the load variations to be performed without removing the sample from the tomograph, allowing a quantitative comparison between the 3D images in the 3 conditions. Data such as total porosity, variation of the porous area in each layer, volume and shape of the pores were obtained.
14

Caractérisation non destructive des matériaux composites en fatigue : diagnostic de l’état de santé et pronostic de la durée de vie résiduelle par réseaux de neurones / Nondestructive characterization of composite materials under fatigue loading : structural health diagnosis and remaining useful life prognostic using artificial neural networks

Duchene, Pierre 13 December 2018 (has links)
Ce travail de recherche consiste en la proposition d’une nouvelle approche de caractérisation non destructive de l’endommagement des matériaux composites (carbone/époxy) sollicités en fatigue par des essais d’auto-échauffement (blocs de chargements croissants). Cette approche est basée sur l’utilisation de plusieurs techniques non destructives appliquées in-situ, en temps réel ou différé, dont l’analyse est, soit redondante soit complémentaire. Au total, six techniques ont été utilisées (émission acoustique, thermographie infrarouge, corrélation d’images numériques, acousto-ultrasons, ultrasons C-scan et ondes de Lamb) et leurs résultats post-traités puis fusionnés à l’aide d’algorithmes basés sur les réseaux de neurones. Les résultats obtenus ont permis d’évaluer et de localiser l’endommagement du matériau et d’estimer sa durée de vie résiduelle. Ce faisant, plusieurs avancés scientifiques ont été obtenus en réalisant, par exemple, une localisation 2D des évènements acoustiques à l’aide seulement de deux capteurs avec une précision millimétrique, ou encore le développement d’une nouvelle technique imagée d’acousto-ultrasons permettant un contrôle hors contraintes de l’état d’endommagement du matériau, …et enfin, le pronostic de la durée de vie résiduelle du matériau basé sur une fusion de données par réseaux de neurones. / This research work consists in a new approach for non-destructive characterisation of damage in composite materials (carbon/epoxy) subjected to fatigue during self-heating tests (increasing load blocks). This approach is based on the use of several non-destructive techniques applied in-situ, in real time or delayed, whose analysis is either redundant or complementary. Six techniques were used (acoustic emission, infrared thermography, digital image correlation, acousto-ultrasound, C-scan ultrasound and lamb waves) and their post-processed results were merged using algorithms based on neural networks. The results obtained made it possible to assess and locate the damage of the material and to estimate its residual life. In doing so, several scientific advances have been obtained by, for example, carrying out a 2D localization of acoustic events using only two sensors with millimetric precision, or the development of a new pictorial acousto-ultrasonic technique allowing an control of the state of material damage at free stress conditions, ... and finally, the prognosis of the residual lifetime of the material based on a data fusion by neural networks.
15

Influência do sistema de trilha na qualidade física e fisiológica de sementes de soja submetidas a períodos de armazenamento / Trail system influence on the physical and physiological quality of soybean seeds submitted to storage periods

Strobel, Thiago 08 December 2015 (has links)
Submitted by Maria Beatriz Vieira (mbeatriz.vieira@gmail.com) on 2017-04-25T16:35:31Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_thiago_strobel.pdf: 495296 bytes, checksum: 891da86ed6f9b4154bb03577981bbf35 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-04-25T17:25:13Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_thiago_strobel.pdf: 495296 bytes, checksum: 891da86ed6f9b4154bb03577981bbf35 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-04-25T17:26:11Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_thiago_strobel.pdf: 495296 bytes, checksum: 891da86ed6f9b4154bb03577981bbf35 (MD5) / Made available in DSpace on 2017-04-25T17:26:21Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_thiago_strobel.pdf: 495296 bytes, checksum: 891da86ed6f9b4154bb03577981bbf35 (MD5) Previous issue date: 2015-12-08 / Sem bolsa / O objetivo do trabalho foi avaliar a qualidade física e fisiológica de sementes de soja colhidas com diferentes sistemas de trilha após a colheita e o armazenamento. A cultivar utilizada foi Syn 1059 RR (V Top), semeada sob sistema de semeadura direta na palha no dia 25/10/2014 com densidade de semeadura de 240.000 sementes por hectare e espaçamento de 0,5 m. Os tratamentos foram constituídos de diferentes sistemas de trilha, onde avaliou-se a) colhedora com sistema de trilha axial; b) colhedora com sistema de trilha axial equipada com plataforma “draper”; c) colhedora com sistema de trilha radial; d) controle - debulha manual. Foram analisados a porcentagem de “bandinhas”, a danificação mecânica pelo testes de hipoclorito, germinação, envelhecimento acelerado e emergência em campo. Os maiores valores de danos mecânicos, determinados pelo teste de hipoclorito, foram constatados para o sistema de trilha radial, seguido pelo sistema de trilha axial e axial + “draper” e os menores valores para sementes colhidas manualmente. A porcentagem de bandinha e a danificação mecânica foram maiores para o sistema de trilha radial, enquanto, sementes colhidas com este sistema atingiram menores valores de germinação, envelhecimento acelerado e emergência em campo. A germinação, envelhecimento acelerado e emergência em campo atingiram os menores valores em sementes colhidas com sistema de trilha radial, no entanto, após o armazenamento, estes resultados mantiveram-se apenas para o teste de emergência em campo. Sementes colhidas com sistemas de trilha axial e axial equipado com plataforma “draper” e trilha manual não apresentaram diferença para germinação, resultados de envelhecimento acelerado e emergência em campo. A qualidade física e fisiológica é superior quando empregadas as colhedoras com sistema axial e axial + “draper”, sem diferir de sementes colhidas manualmente. / The aim of the work was to evaluate the physical and physiological quality of soybean seeds harvested with different track system after harvest and storage. The cultivar used was Syn 1059 RR (V Top), sown under no-tillage system in straw in day 25/10/2014 with sowing rate of 240,000 seeds per hectare spacing of 0.5 m. The treatments were different track system, where was evaluated: a) harvesters with axial track system; b) harvesters with axial track system equipped with "draper" platform; c) harvesters with radial track system; d) Control - manual threshing. Were analyzed the percentage of "splits", mechanical damaging by the hypochlorite test, germination, accelerated aging and field emergence. The highest values of mechanical damage, determinated by the hypochlorite test, were seen to radial track system, followed by axial and axial track system + "draper" and the lowest values for seeds harvested manually. The percentage of splits and mechanical damage were higher for the radial track system, being that, the seeds harvested with this system reached the minor germination values, accelerated aging and field emergence. The germination, accelerated aging and field emergence reached the lowest values in seed harvested radial track system, however, after storage, these results have remained only for the field emergence test. Seeds harvested with axial and axial track systems equipped with platform "draper" and manual track also did not differ for germination, results of accelerated aging and field emergence. The physical and physiological seed quality is superior when employed harvesters with axial and axial system + "draper", without differ from seeds manually harvested.
16

Modélisation numérique de l’usinage des matériaux composites à matrice polymère et fibres longues de carbone / Numerical modelling of machining long carbon fiber reinforced polymer composites

Zenia, Sofiane 11 July 2017 (has links)
La mise en œuvre des matériaux composites, fait souvent appel à des procédés d’usinage conventionnel, comme l’opération de perçage utilisée lors de l’assemblage de structures par rivetage. Ces opérations peuvent générer dans la pièce usinée différents types d’endommagement: arrachement des fibres, rupture de la matrice, délaminage intralaminaire et interlaminaire, dégradation thermique de la matrice, ce qui peut provoquer une baisse des performances mécaniques de la structure. L’objectif de la thèse est de mettre en place un modèle numérique scientifiquement rigoureux pour analyser l’usinage des composites CFRP et prédire les mécanismes d’endommagement induits par l’outil coupant. Ce modèle basé sur une loi constitutive mésomécanique combine l’effet de la chute de rigidité dans le comportement du matériau, la plasticité, l’initiation et l’évolution de l’endommagement durant le processus d’usinage. Ensuite, deux modèles 2D et 3D adoptant un schéma explicite ont été implémentés via la sub-routine VUMAT dans Abaqus. Le délaminage interplis a été pris en considération à l’aide des éléments cohésifs disponibles dans le code ABAQUS/Explicit. Ce travail a permis de reproduire de manière réaliste les opérations de coupe orthogonale et de perçage des composites CFRP en termes de processus de formation du copeau, la prédiction des forces de coupe et celle de l’endommagement induit. Ces études ont montré que l’orientation des fibres et la profondeur de coupe sont les paramètres les plus influents en coupe orthogonale tandis que pour le perçage se sont les vitesses d’avance et la géométrie des outils / The machining of composite materials is often necessary for material removal operations by cutting tools such as drilling. These operations can generate a lot of damage in the machined workpiece (fiber fracture, matrix craking, intralaminar and interlaminar delamination and thermal degradation of the matrix), which can cause a decrease of mechanical performance of the structure. The PhD thesis objective is to set up a reliable accurate model to analyze the machining of CFRP composites and to predict the different damage modes induced by the cutting tool. This model is based on a mesomechanical constitutive law combining the stiffness degradation concept into the material behavior, the plasticity, the initiation and the evolution of the damage during the machining process. Two 2D and 3D models adopting an explicit scheme were implemented in Abaqus/Explicit analysis code through the user subroutine VUMAT. Furthermore, interlaminar delamination is taken into account using the cohesive elements available in the ABAQUS / Explicit code. This work allowed to realistic numerical simulation of orthogonal cutting and drilling operations of CFRP composites in terms of chip formation process, cutting forces prediction and induced damage. These studies have shown that the fiber orientation and the depth of cut were the most influential parameters in orthogonal cutting while for the drilling process, the feed rate and the tool geometry are the most important parameters
17

Qualidade fisiológica e desempenho agronômico de soja em função do tamanho das sementes /

Fonseca, Nara Rosseti, 1977- January 2007 (has links)
Orientador: Cláudio Cavariani / Banca: João Nakagawa / Banca: Marco Eustáquio de Sá / Banca: Elza Alves / Banca: Divania de Lima / Resumo: A separação de sementes por classes de tamanho em soja é uma prática recentemente adotada no Brasil. Essa classificação favorece a precisão da semeadura, a obtenção de população adequada, a eqüidistância de plantas e, ainda, redução da demanda de sementes por área. O objetivo do estudo foi avaliar a influência do tamanho das sementes na qualidade fisiológica, durante o armazenamento, e no desempenho agronômico de duas cultivares de soja, produzidas em três localidades distintas do Estado do Paraná, de acordo com a classificação do tamanho proposto pela Comissão Estadual de Sementes e Mudas - CESM/PR. O trabalho foi conduzido em duas etapas, nos anos de 2005 e 2006. A primeira etapa foi realizada no Laboratório de Análise de Sementes do Departamento de Produção Vegetal - Setor Agricultura (DPV-A), e a segunda na área experimental da Fazenda Lageado, ambas as dependências pertencentes à Faculdade de Ciências Agronômicas (FCA), da Universidade Estadual Paulista (UNESP), em Botucatu-SP. Foi utilizado dois cultivares de ciclo semiprecoce, produzidas e classificadas em dois tamanhos (5,5 e 6,5 mm) em Faxinal, Mauá-da-Serra e Ponta Grossa, todas localizadas no Estado do Paraná. Após classificação mediante emprego de peneiras de crivos circulares, as sementes foram transportadas para o DPV-A da FCA onde foram armazenadas sob condições de ambiente natural (sem controle de temperatura e umidade relativa do ar) por um período de seis meses. Nas avaliações de laboratório ao início do armazenamento foram utilizados os seguintes testes: massa de 100 sementes, retenção de peneiras, dano mecânico (hipoclorito de sódio), porcentagem de sementes verdes, e a cada dois meses do período de armazenamento: teor de água das sementes, teste de germinação, primeira contagem de germinação, comprimento... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: Separation of soybean seeds considering its size class is a recently technique adopted in Brazil. This kind of classification favors sowing precision, obtaining of adequate population and equidistance among plants and, yet, reduction in seed requirement per area. The objective of this research was to evaluate physiological quality of seeds during storage and agronomic performance of two soybean varieties, produced in three different localities from the State of Paraná, according to the size classification suggested by Comissão Estadual de Sementes e Mudas - CESM/PR. The research was carried out in two stages, in the years of 2005 and 2006. The first was carried out in the Laboratório de Análise de Sementes, Departamento de Produção Vegetal - Setor Agricultura (DPV-A), and the second at an experimental area in the Fazenda Lageado, both belonging to the Faculdade de Ciências Agronômicas (FCA), Universidade Estadual Paulista (UNESP), in Botucatu-SP. Two varieties were used, classified as semi-early growth cycle, produced the classification in two sieves (5,5 and 6,5 mm) in Faxinal, Mauá-da-Serra and Ponta Grossa, all located in the State of Paraná. After the classification through the use of screens with round sieves, the seeds were transported to the DPV-A - FCA, where they were stored in environmental conditions (without control of the temperature and relative humidity) for six months. For the laboratorial evaluations before the storage, the following tests were used: weight of 100 seeds, screen retention, mechanical damage (sodium hypochlorite) and percentage of green seeds. During the storage, the seed moisture content, germination, first count of the germination, seed length, seedling dry matter, accelerated aging, electrical conductivity, tetrazolium test, seedling emergence in field and speed of emergence-index were... (Complete abstract, click electronic address below). / Doutor
18

Qualidade fisiológica de semente de soja em função do tamanho da semente e da cultivar / Soybean seed quality in relation to seed size and cultivar

Vendrame, Ronaldo João 17 October 2012 (has links)
Made available in DSpace on 2014-08-20T13:44:29Z (GMT). No. of bitstreams: 1 dissertacao_ronaldo_joao_vendrame.pdf: 206490 bytes, checksum: 8d8cd3ea0bba575c008d09b380c19b64 (MD5) Previous issue date: 2012-10-17 / This study aimed to evaluate the relationship among seed size and their physical and physiological attributes in three soybean cultivars (NK 7059 RR, SYN 3358 RR and BMX POTÊNCIA RR). Samples were collected from the Seed Processing Unit C.Vale in Abelardo Luz-SC, and the following analyzes were performed: seed germination , seed vigor, mechanical damage, screen retention and weight of 1000 seeds. The analyzes were performed at the Laboratory of Seeds Analysis C.Vale- Cooperativa Agroindustrial in Palotina-PR, and the following cultivars and screens were used: NK 7059 RR (5.75 and 6.75 mm), SYN 3358 RR (5.5 and 6.5mm) and BMX POTÊNCIA RR (5.75 and 6.75mm). The analysis of seed germination was performed according to the Brazilian Rules for Seed Analysis; the seed vigor test was based on the accelerated aging and the test with sodium hypochlorite was used for the evaluation of mechanical damage. Two replicates of 100 seeds were used for the screen retention test, which was determined by retention in specified screen and in screen without perforations. The weight of 1000 seeds was measured in eight replications of 100 seeds. The following conclusions were obtained: 1-Physiological seed quality is independent of seed size 2-There is higher seed retention on the superior screen, reaching more than 10%, and 3-Large seeds tend to have higher mechanical damage. / O presente trabalho teve como objetivo avaliar a relação do tamanho das sementes de soja em três cultivares (NK 7059 RR, SYN 3358 RR e BMX POTÊNCIA RR), sobre os atributos físicos e fisiológicos da semente na qualidade das sementes. As amostras foram coletadas da Unidade de Beneficiamento Sementes da C.Vale, em Abelardo Luz-SC, sendo feito as seguintes análises: Germinação, Vigor, Dano mecânico, Retenção de peneiras e peso de mil sementes. As análises foram conduzidas no Laboratório de Análise de Sementes da C.Vale-Cooperativa Agroindustrial, em Palotina-PR, para os seguintes cultivares e peneiras: NK 7059 RR(5,75 e 6,75), SYN 3358 RR(5,5 e 6,5) e BMX POTÊNCIA RR(5,75 e 6,75). A análise de germinação seguiu as normas da Regra de Análise de Sementes; A análise de vigor foi feita com base no Teste de Envelhecimento Acelerado e a avaliação do dano mecânico foi feita aplicando-se o teste com hipoclorito de sódio. A retenção de peneiras foi determinada através da retenção na peneira especificada em duas repetições de 100 sementes e outra peneira com um fundo cego. Por último, foi determinado o peso de 1000 sementes com oito repetições com 100 sementes de cada. As seguintes conclusões foram obtidas: 1 A qualidade fisiológica independe do tamanho das sementes; 2 Há uma maior retenção de sementes na peneira superior, podendo alcançar mais de 10%; e 3 As sementes grandes tendem a apresentar maior danificação mecânica.
19

Qualidade fisiológica de sementes de soja em função da danificação mecânica / Physiological quality of soybean seeds due to the mechanical damage

Rigo, Geliandro Anhaia 27 February 2013 (has links)
Made available in DSpace on 2014-08-20T13:44:33Z (GMT). No. of bitstreams: 1 dissertacao_geliandro_anhaia_rigo.pdf: 867122 bytes, checksum: 9eddb4aa6b75043fdee2c817430e86c6 (MD5) Previous issue date: 2013-02-27 / This study aimed to evaluate the physiological quality of soybean seeds damaged at different levels as well as the effect of seed treatment with fungicide after 150 days of storage. Used - if seeds of the cultivar Turbo. These seeds were harvested and threshed manually to ensure that there were no initial mechanical damage. Damage to seeds used a mechanical damaging, "Impact Test". Seeds were individually exposed on a counter seed round hole for receiving the impact through a 100 g weight at different heights (A1 = A2 = 10 cm and 20 cm), adding three levels of damage without damage, moderately damaged and highly damaged. Done that seeds were packaged in paper bags Derosal Plus fungicide treated and stored in BOD with temperature 22 ° C ± 3 ° C, for further evaluation of vigor at 30, 60, 90, 120 and 150 days of storage. The tests were performed, germination, first count of germination and accelerated aging. Results were subjected to analysis of variance and mean comparison by Scott Knott test at 5% using the statistical program Assistat. Highly damaged soybean seeds by 50% reduces your potential germination in 150 days of storage under controlled conditions of 22 ° C ± 3 ° C and relative humidity of 60%.The fungal treatment with Derosal Plus in soybean seeds reduces the process of deterioration during storage. / O presente trabalho teve como objetivo avaliar a qualidade fisiológica de sementes de soja danificadas em diferentes níveis, assim como o efeito do tratamento de sementes com fungicida até 150 dias de armazenamento. Foram utilizadas sementes de soja da cultivar Turbo. Estas sementes foram colhidas e trilhadas manualmente a fim de garantir que não houvesse nenhum dano mecânico inicial. Para danificação das sementes utilizou-se um danificador mecânico, teste do impacto . As sementes foram expostas individualmente sobre um contador de sementes de furo redondo, para receberem o impacto através de um peso 100 g sob diferentes alturas (A1 = 10 cm e A2 = 20 cm), somando-se três níveis de danos: sem dano, mediamente danificadas e altamente danificadas. Feito isso, as sementes foram acondicionadas em sacos de papel tratadas com fungicida Derosal Plus e armazenadas em BOD com temperatura de 22°C ± 3 °C, para posterior avaliação da qualidade fisiológica aos 30, 60, 90, 120 e 150 dias após o armazenamento. Os testes realizados foram germinação, primeira contagem de germinação e envelhecimento acelerado. Os resultados foram submetidos à análise de variância e comparações de média pelo teste de Scott Knott a 5% utilizando o programa estatístico Assistat. Sementes de soja altamente danificadas reduzem em 50% o seu potencial de germinação em 150 dias de armazenamento sob condições controladas de 22 °C ± 3 °C e umidade relativa de 60%. O tratamento fúngico com Derosal Plus em sementes de soja reduz o processo de deterioração das sementes durante o armazenamento.
20

Caractérisation de l’endommagement thermique et mécanique dans le mortier par les ondes acoustiques non linéaires / Characterization of heat and mechanical damage in the mortar by nonlinear acoustic waves

Yousfi, Ismail 29 May 2015 (has links)
L'objectif de ce travail est la caractérisation de l’endommagement thermique et mécanique dans le mortier par les ondes acoustiques non linéaires. La corrélation entre les paramètres acoustiques linéaires et non-linéaires étudiée est basée sur les essais expérimentaux et la modélisation. Pour l’endommagement thermique, des éprouvettes cylindriques ont été préparées et caractérisées par l'étude de la porosité et la saturation. Ensuite, l'acoustique linéaire et l’acoustique non linéaire (génération d'harmoniques) ont été appliquées afin de quantifier l’endommagement. Les essais acoustiques linéaires ont prouvé que les vitesses transversales, longitudinales et le module d'Young du mortier diminue en fonction de la température. Les essais acoustiques non linéaires ont montré l'augmentation du bêta fonction de la température. Pour l’endommagement mécanique, le phénomène d'autocicatrisation est suivi par la perméabilité et les essais acoustiques. Les essais de perméabilité ont montré que le débit d'air et la taille de la fissure diminue rapidement au cours du premier mois, puis lentement durant le reste du processus d'autocicatrisation. D'autre part, les tests acoustiques non linéaires ont montré que « alpha » et « bêta » diminuent durant le processus de l’autocicatrisation qui signifie que les paramètres non linéaires sont un bon indicateur pour caractériser ce phénomène. A partir des résultats expérimentaux, une corrélation polynomiale de 2ème degré a été établie entre les paramètres non linéaires et l’index d’endommagement. Les résultats de ce travail représentent un bon départ pour étudier le phénomène de l'autocicatrisation par les ondes acoustiques non linéaires / The objective of this work is the characterization of heat and mechanical damage in the mortar by the nonlinear acoustic waves. The correlation between non-linear/linear acoustic parameters and damage in mortar is studied based on experiments and modelling. For the heat damage, cylindrical specimens were prepared and were characterized by studying the porosity and saturation. Indeed, the linear acoustic (UPV) and non-linear acoustic (Higher harmonic generation) were applied to characterize the damage. The linear acoustic tests have shown that velocities and modulus of Young of the mortar decreases in function of the temperature. The non-linear acoustic tests have shown that beta increases in function of the temperature.For the mechanical damage. The self-healing phenomenon was characterized by the permeability and the acoustic tests. Indeed, the permeability tests have shown that the airflow and the crack size decreases quickly in the first month then slowly for the rest of the self-healing process. On the other hand, the non-linear acoustic tests shown that the alpha and beta decreases according to the self healing process which means that the nonlinear parameters are a good indicators to characterize the self-healing. Moreover, the analysis of the experimental results indicates that the frequency resonant technique is more efficient to characterize the defects in the mortar than the higher harmonic generation. A polynomial correlations of a 2nd degree was established between the nonlinear parameters and the index damage. The findings of this work should be most appropriate as a foundation for the study of the self healing by the nonlinear acoustic waves

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