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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.
1

Étude de l’influence de la nature des granulats sur les propriétés des bétons hydrauliques : cas des granulats calcaires tunisiens / Study of the influence of the aggregates nature on the hydraulic concretes : case of the Tunisian aggregates limestones

Achour, Taoufik 15 November 2007 (has links)
Ce travail de thèse s’intéresse à la valorisation des ressources granulaires tunisiennes, de type calcaire, dans les mélanges hydrauliques. Les matériaux utilisés sont issus des carrières de Aïn Tebournouk, Nahli, Jbel Ressas, El Haoureb, Jradou et Tahent qui sont appelées à alimenter les principaux centres de consommation de la région de Tunis et de la zone côtière du Centre-Est. Les propriétés analysées sont les résistances en compression et en traction et le module d’élasticité. Les récents modèles du LCPC français ont été utilisés pour prédire ces propriétés. Ils ne donnent pas toujours des résultats satisfaisants, en particulier si les mélanges sont riches en éléments fins, comme c’est souvent le cas avec des granulats issus de carrières. Les mortiers, micro-bétons et bétons réalisés dans le cadre de ce travail ont permis de proposer une extension de ces modèles. Pour la résistance à la compression, le coefficient d’adhérence a été associé à la teneur en fillers des granulats. L’hypothèse est que la présence des éléments fins, de même nature que les granulats, améliore l’adhérence pâte-granulat, grâce au rapprochement des propriétés de rigidité des deux matériaux. Pour la résistance à la traction, un modèle décrit par une loi hyperbolique a permis d’apporter une interprétation physique au comportement à la traction des mélanges hydrauliques. Ses paramètres sont reliés à la résistance du granulat et à la cohésion dans la zone de transition pâte-granulat. Enfin pour le module d’élasticité, l’utilisation du modèle du LCPC, qui prend en compte les propriétés de la phase granulaire et de la phase liante, a permis d’atteindre le module d’élasticité de certains granulats. / This study concerns the Tunisian granular resources, of limestone type, in the hydraulic mixtures. The used materials outcoming from the careers of Aïn Tebournouk, Nahli, Jbel Ressas, El Haoureb, Jradou and Tahent which have to feed the principal centers of consumption of the area of Tunis and the coastal zone of Center-East. The analyzed properties are the compressive and the tensile strengths and the elastic modulus. The recent models of the French LCPC were used to predict these properties. They do not always give satisfactory results, in particular if the mixtures are rich in fine elements, as it is often the case of the aggregates outcoming from careers. The mortars, micro-concretes and concretes carried out within the framework of this study made it possible to propose an extension of these models. For the compressive strength, the bond coefficient was associated with the content of fillers aggregates. The assumption is that the presence of these fine elements, of comparable nature that the aggregates, improves adherence paste and aggregate, thanks to bringing together the properties of rigidity of the two materials. For the tensile strength, a model describes by a hyperbolic law made it possible to provide a physical interpretation to the tensile strength behavior of the hydraulic mixtures. Its parameters are linked to the aggregate strength and cohesion in the paste-aggregate transition zone. Finally for the elastic modulus, the use of the model of the LCPC, which takes into account the properties of the granular phase and the binding phase, made it possible to reach the modulus of elasticity of some aggregates.
2

Studies on inorganic rubber fillers with special reference to the relationships between the properties of fillers and the properties imparted to vulcanized rubber.

Flemmert, Gösta. January 1900 (has links)
Thesis--Tekniska högskolan, Stockholm. / Extra t.p., with thesis statement, inserted. Bibliography: p. 121-124.
3

A prosódia do filler este da língua espanhola: leituras pragmáticas / The prosody of Spanish filler este: pragmatic interpretations

Ccori, Telma Aparecida Félix da Matta 07 August 2018 (has links)
A palavra morfofonológica este da língua espanhola é submetida a análise acústica no presente trabalho com o objetivo de verificar-se padrões prosódicos para seus diferentes usos: referencial (adjetivo/pronome) e metadiscursivo. Os valores dos parâmetros acústicos mensurados para a ocorrência de este referencial são comparados aos das ocorrências de este metadiscursivo com a finalidade de reconhecer-se uma subcategorização do uso metadiscursivo: filler e marcador discursivo. São utilizados dados de fala espontânea do espanhol do México, coletados no website YouTube. Verificamos que, do ponto de vista prosódico, as tendências de comportamento de este referencial metadiscursivo apresentam divergências ou convergências a depender da interpretação pragmática relacionada ao último uso. / The word este of Spanish is acoustically analyzed in the present work in order to verify prosodic patterns for its different uses: referential (adjective / pronoun) and metadiscoursive. The measured values of acoustic parameters for each type of occurrence are compared with the purpose of proposing two different classes inside metadiscoursive use: a filler and a discourse marker. We use spontaneous speech data from Mexican Spanish, collected on the YouTube website.From the prosodic point of view, the behavioral tendencies of metadiscursive and referential este have divergences or convergences depending on the pragmatic interpretation related to the last use.
4

A prosódia do filler este da língua espanhola: leituras pragmáticas / The prosody of Spanish filler este: pragmatic interpretations

Telma Aparecida Félix da Matta Ccori 07 August 2018 (has links)
A palavra morfofonológica este da língua espanhola é submetida a análise acústica no presente trabalho com o objetivo de verificar-se padrões prosódicos para seus diferentes usos: referencial (adjetivo/pronome) e metadiscursivo. Os valores dos parâmetros acústicos mensurados para a ocorrência de este referencial são comparados aos das ocorrências de este metadiscursivo com a finalidade de reconhecer-se uma subcategorização do uso metadiscursivo: filler e marcador discursivo. São utilizados dados de fala espontânea do espanhol do México, coletados no website YouTube. Verificamos que, do ponto de vista prosódico, as tendências de comportamento de este referencial metadiscursivo apresentam divergências ou convergências a depender da interpretação pragmática relacionada ao último uso. / The word este of Spanish is acoustically analyzed in the present work in order to verify prosodic patterns for its different uses: referential (adjective / pronoun) and metadiscoursive. The measured values of acoustic parameters for each type of occurrence are compared with the purpose of proposing two different classes inside metadiscoursive use: a filler and a discourse marker. We use spontaneous speech data from Mexican Spanish, collected on the YouTube website.From the prosodic point of view, the behavioral tendencies of metadiscursive and referential este have divergences or convergences depending on the pragmatic interpretation related to the last use.
5

Time-temperature effects on the mechanical behavior of talc filled polypropylene

Kempinski, Robert Mark 08 1900 (has links)
No description available.
6

The geometric modification of high temperature adhesives

Miles, A. L. January 2000 (has links)
No description available.
7

Determination of the compressibility of excipients used for formulation of tablets with theophylline.

Kousoulidou, Viktoria January 2015 (has links)
1 Abstract Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical Technology Consultant: Assoc. Prof. PharmDr. Zdenka Sklubalova, Ph.D. Student: Viktoria Kousoulidou Title of Thesis: Determination of the compressibility of excipients used for formulation of tablets with theophylline The current thesis is focused on the compressibility properties of five powders used in tablet formulation: Comprecel, Spherolac, DI-CAFOS D160, DI-CAFOS A150 as excipients and Theophylline as the active substance. The particle size, moisture content, bulk density and flowability of the powders are determined. The powders are compressed and the results are evaluated by means of the parameters of the compaction equation and the force-displacement method (compression under 5, 10, 15 kN). Then, the crushing strength of tablets prepared from each powder by the force-displacement method is measured. The average values of the crushing strength are used to calculate the tensile strength of the tablets. Best compressibility is found in Comprecel and Theophylline with tensile strength values of 1.31 MPa under 5 kN, 3.31 MPa under 10 kN, 4.75 MPa under 15 kN and 1.02 MPa under 5 kN, 2.27 MPa under 10 kN, 3.09 MPa under 15 kN, respectively.
8

Polymer derived ceramic composites as environmental barrier coatings on steel /

Torrey, Jessica D. January 2006 (has links)
Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (p. 127-142).
9

Improved filler retention by co-flocculation of fines and filler particles.

Matyumza, Ntombozuko C. 04 1900 (has links)
Thesis (MScFor)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: The retention of filler particles and drainage are important aspects of papermaking. A number of important paper properties depend in the quality and quantity of filler retained in the paper. Fines, fillers and pulp fibres all have a negative charge and are kept apart by electrostatic forces. This causes a decrease in the effectiveness of cationic retention aids thereby causing a high cationic demand. This in turn implies that the retention of fines and filler particles in a formed sheet is not efficient, especially in the presence of anionic trash. In order to improve printability, print quality and dimensional stability, a large percentage of mineral pigments / fillers either in the form of internal loading or external coating should be added. It was found that coflocculation of fines and filler particles resulted in an even distribution of filler particles in the form of miero-flocs and the filler retention was maintained. Opacity was improved without much reduction in paper strength. An increased filler content without coflocculation of fines reduced sheet strength properties. The filler particles interfered with the development of fibre-to-fibre bonds and occupied spaces that otherwise might have contained fibres. This study showed that the most beneficial effect of coflocculation of filler with fines was obtained, with regards to paper strength, opacity, filler retention and printability, when the charge of the fibre furnish was maintained at -0.1 leu with the 0.1% addition of cationic PAM retention aid. / AFRIKAANSE OPSOMMING: Twee belangrike aspekte van papiervervaardiging is die retensie van vulstowwe en ontwatering. 'n Aantal belangrike papiereienskappe is afhanklik van die hoeveelheid en kwaliteit van vulstowwe wat in papier voorkom. Veselpuin, vulstowwe en pulp-vesels is almal negatief gelaai, gevolglik verseker elektrostatiese kragte dat hierdie deeltjies los van mekaar bly. Laasgenoemde verminder die doeltreffendheid van kationiese retensiemiddels en dit gee aanleiding tot 'n hoë kationiese aanvraag. Die retensie van veselpuin en vulstof deeletjies in papier is gewoonlik nie voldoende in die teenwoordigheid van anioniese afvalkomponente nie. Om aan papier verbeterde drukeienskappe, drukkwaliteit en dimensionele stabiliteit te gee, moet 'n groot persentasie minerale pigmente en/of vulstowwe as 'n interne lading of eksterne bestryking voorsien word. Daar is bevind dat kot1okkulasie van fynstowwe en vulstofdeeltjies, 'n egalige verspreiding van vulstof-partikels as mikro-t1okke tot gevolg het en dat vulstof-retensie op aanvaarbare vlakke behou is. Ook is ondeurskynendheid verbeter sonder 'n beduidende verswakking in die papiersterkte. 'n Toename in vulstofinhoud, sonder kot1okkulasie van fynstowwe, het die papier sterkte-eienskappe verlaag. Vulstofdeeltjies bëinvloed die ontwikkeling van vesel-tot-vesel binding. Hierdie deeltjies beset ruimtes wat andersins deur vesels benut sou word. Hierdie studie het getoon dat die voordeligste effek van kot1okkulasie van vulstowwe met fynstowwe verkry is, ten opsigte van papiersterkte, ondeurskynendheid, vulstof retensie en drukeienskappe, wanneer die lading van die pulpsuspensie by -0.1 leu gehou was met 'n byvoeging van 0.1% kationiese PAM retensie-hulpmiddel.
10

Development and evaluation of dispersing agents for carbon black filled natural rubber compounds

Gunewardena, J. Anoma G. S. G. January 1999 (has links)
Various additions are used in rubber compounds to accelerate mixing with particulate fillers and to improve behaviour in subsequent processing operations. Cationic surfactants of general structure [RNH2(CH2)3NH3]2+ 2[R'COO] can be used in rubber processing as multifunctional additives (MFA) which act as processing aids, accelerators and mould releasing agents. However, with all these beneficial properties an adverse effect of decreased scorch time was observed when N–tallow–1,3 diaminopropane dioleate (EN444) was used in the filled natural rubber compound.

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