This paper focuses on two experimental methods that give indicators linked to the impregnation level of the yarn / matrix interface, in the case of Textile Reinforced Concrete (TRC). These methods have been tested on three different glass yarns laid in a cementitious matrix, with three different impregnation levels resulting from the manufacturing process. The first method (comparative mercury intrusion porosity test) is based on the evaluation by mercury intrusion porosity of the pores volume associated to the porosity inside and near the yarn. The second method (flow test) consists in measuring the flow rate of water along the yarn, with imposed flow conditions. The physical parameters measured by these two methods are both related to the pore size and to the porosity of the yarn / matrix interface. The results of the two methods are discussed and drawn in parallel to a qualitative characterization of the yarn matrix interface made by scanning electron microscopy. As a result, the connection between the results of the two methods and the SEM characterization is studied. It is shown how these methods can participate to characterize the yarn impregnation. Limitations of the methods are also discussed.

SANTOS, Paulo Ricardo Alves dos. Consórcio de milho com forrageiras: atributos físicos do solo e produtividade. 2016. 84 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia Agrícola, Programa de Pós-Graduação em Engenharia Agrícola, Fortaleza, CE, 2016. / Submitted by demia Maia (demiamlm@gmail.com) on 2016-08-01T13:27:48Z No. of bitstreams: 1 2016_dis_prasantos.pdf: 1948037 bytes, checksum: e1770d22fe7e64bae84ffa607d041a49 (MD5) / Approved for entry into archive by demia Maia (demiamlm@gmail.com) on 2016-08-01T13:28:25Z (GMT) No. of bitstreams: 1 2016_dis_prasantos.pdf: 1948037 bytes, checksum: e1770d22fe7e64bae84ffa607d041a49 (MD5) / Made available in DSpace on 2016-08-01T13:28:25Z (GMT). No. of bitstreams: 1 2016_dis_prasantos.pdf: 1948037 bytes, checksum: e1770d22fe7e64bae84ffa607d041a49 (MD5) Previous issue date: 2016 / The intensification of agricultural production systems is increasing in the current agriculture. In this sense, the simultaneous planting forage to grain crops, constitutes an alternative in the intensification of the production system, which can increase or not the productivity of the main crop, and produce straw for mulching. In order to check the occurrence of changes in the physical properties of the soil and in corn yield and dry matter production due to the corn consortium / forage in two sowing dates, this study was conducted in the experimental area of the Department of Agricultural Engineering of the Federal University of Ceará. The design was used in a randomized block design in a factorial scheme (3x2) + 1 with four replications, totaling 28 experimental units. The treatments consisted of three forages: Brachiaria, Panicum maximum cv. Mombaça and Crotalaria spectabilis intercropped with maize in two of fodder sowing dates, between the lines of simultaneous sowing maize (season 1 - E1) and corn leading the V4 stage of corn (season 2 - E2), and the control. The results showed that intercropping maize / forage did not interfere in phytotechnical characteristics of corn, nor in productivity, however produced changes in soil physical properties when the day of sowing in season 1. Despite the changes that have occurred in the soil, they were not sufficient to enhance the productivity of maize, which could possibly be related assessments on only one crop cycle. But when the goal was the production of dry straw, it is concluded that fodder Brachiaria brizantha and Mombasa at the time 1 (E1) are recommended / A intensificação dos sistemas de produção agrícola é cada vez maior na atual agricultura. Nesse sentido, o plantio simultâneo de forrageiras com culturas produtoras de grãos, constitui em uma alternativa na intensificação do sistema de produção, que poderá incrementar ou não a produtividade da cultura principal, além de produzir palha para cobertura do solo. Com o objetivo de verificar a ocorrência de mudanças nas propriedades físicas do solo, bem como na produtividade do milho e produção de matéria seca em função do consórcio milho/forrageiras em duas épocas de semeadura, o presente trabalho foi conduzido na área experimental do Departamento de Engenharia Agrícola da Universidade Federal do Ceará. Foi utilizado o delineamento em blocos ao acaso, no esquema fatorial (3x2) + 1 com quatro repetições, totalizando 28 unidades experimentais. Os tratamentos foram constituídos por três forrageiras: Brachiaria brizantha, Panicum maximum cv. Mombaça e Crotalária spectabilis consorciadas com o milho em duas épocas de semeadura das forrageiras, na entrelinha do milho simultâneo a semeadura (época 1 – E1) e na entrelinha do milho no estádio V4 do milho (época 2 – E2), além da testemunha. Os resultados permitiram concluir que a consorciação milho/forrageiras não interferiram nas características fitotécnicas do milho, nem tampouco, na produtividade, porém proporcionaram modificações nas propriedades físicas do solo quando da realização da semeadura na época 1. Apesar das modificações ocorridas no solo, as mesmas não foram suficientes em incrementar a produtividade do milho, o que possivelmente pode estar relacionado as avaliações em apenas um ciclo da cultura. Já quando o objetivo foi a produção de matéria seca de palha, conclui-se que as forrageiras Brachiaria Brizantha e Mombaça na época 1 (E1) são recomendadas

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This paper focuses on two experimental methods that give indicators linked to the impregnation level of the yarn / matrix interface, in the case of Textile Reinforced Concrete (TRC). These methods have been tested on three different glass yarns laid in a cementitious matrix, with three different impregnation levels resulting from the manufacturing process. The first method (comparative mercury intrusion porosity test) is based on the evaluation by mercury intrusion porosity of the pores volume associated to the porosity inside and near the yarn. The second method (flow test) consists in measuring the flow rate of water along the yarn, with imposed flow conditions. The physical parameters measured by these two methods are both related to the pore size and to the porosity of the yarn / matrix interface. The results of the two methods are discussed and drawn in parallel to a qualitative characterization of the yarn matrix interface made by scanning electron microscopy. As a result, the connection between the results of the two methods and the SEM characterization is studied. It is shown how these methods can participate to characterize the yarn impregnation. Limitations of the methods are also discussed.

Powder metallurgy (PM) is usually used in manufacturing parts with complex geometries, such as gears and structural parts. The main attractions of PM are the high rate of material utilization, environmental friendliness of production, economic advantages (especially for complex geometries), and possibility of obtaining lighter components. To find a wide range of applications and compete with regular steel gears, PM gear transmissions should have good transmission efficiency and wear properties. Furthermore, they should have low contact noise and adequate surface fatigue properties. Because of the porosity structure of PM gears both on gear flanks and in the body, the friction and wear properties of PM gear flank contacts differ somewhat from those of regular steel gears.    This doctoral thesis examines the efficiency and wear properties of PM gears. Paper A compares the wear, friction, and damage mechanism properties of two sintered gear materials with those of a standard gear material. Paper B deals with the gear mesh torque loss mechanism of PM and regular steel gears by combining both pin-on-disc frictional and FZG efficiency tests. Paper C comparatively examines the efficiency of PM and regular steel gears by conducting FZG gear efficiency tests. Paper D focuses on the wear and friction properties of PM and regular steel gear materials treated using the triboconditioning process. Paper E studies the friction and wear properties attributable to different pore sizes in PM gear materials.    The results indicate that regular steel meshed with PM gear material and PM meshed with PM gear material are good candidate combinations for gear transmissions. This is because the porosities of PM material can lower the friction coefficient while the wear rate can be the same as or even better than that of regular steel contacts. The triboconditioning process enhances the wear resistance and reduces the friction coefficient of the PM gear material. The friction and wear coefficients of PM meshed with PM gear material display increasing trends with increasing pore size. The friction and wear coefficients of regular steel meshed with PM gear material display decreasing trends with increasing pore size. / <p>QC 20160523</p>

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006. / Inclusion and porosity properties of the following supramolecular solid-state hosts were investigated: • 2,7-dimethylocta-3,5-diyne-2,7-diol • 2-methyl-6-phenylhexa-3,5-diyn-2-ol • Dianin’s compound • p-tert-butyl-calix[4]arene • 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetramethoxy-2,8,14,20- tetrathiacalix[4]arene • Two discrete coordination metallocycles, [Ag2IMID2](BF4)2 and [Cu2(BITMB)2(Cl)4] All of these compounds form well-defined crystalline host structures. Inclusion phenomena involving encapsulation of liquids were studied using single-crystal x-ray diffraction methods. Several guest-free host structures (α phases) were structurally elucidated and their gas sorption properties were investigated. Studies of the sorption properties of seemingly nonporous materials were carried out to provide insight into this rare phenomenon. Water and iodine sorption by a polymorph of 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetramethoxy-2,8,14,20- tetrathiacalix[4]arene shows that the conventional perception of sorption through the solid-state requires reassessment. Gas sorption studies were carried out using apparatus devised and presented here. These include sorption apparatus and a device to determine single-crystal structures under controlled gas atmospheres.

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The aim of the work presented in this thesis was to design ionic organic framework materials based on carboxylate salts with the intention of engineering interesting properties, such as porosity, into these framework materials. The first section focuses on the characterisation and porosity studies of an ionic framework material, 3,4-lutidinium pamoate hemihydrate, with THF-filled channels in the solid state. It was shown that this framework is able to exchange the THF in the channels for a wide variety of compounds, with many of these exchanges occurring in a single-crystal to single-crystal fashion. Competition experiments conducted with the framework, both by immersing crystals of the framework in solvent mixtures, as well as by exposing crystals of the framework to mixtures of solvent vapours, indicated that it is able to selectively exchange for one guest over another. The kinetics of exchange of this framework were studied, and it was possible to identify a kinetic model describing this process. A second novel framework-type material, 4-phenylpyridinium pamoate, was identified during the course of this study, as well as five isostructural frameworks containing different guest molecules. In this case the framework consists of discrete units that close-pack in such a way that guest molecules are included in constricted cavities in the solid state. Although this framework-type material is not porous, it is thermally quite stable and also highly selective. It is able to selectively encapsulate 1,4-dioxane when crystallised from various solvent combinations including 1,4-dioxane. In addition, eight novel structures with pamoic acid in combination with various pyridyl derivatives were obtained. A third novel framework material was obtained with N,N'-bis(glycinyl)pyromellitic diimide in which, due to the extended hydrogen-bonded network formed between the constituents of the framework, DMF molecules are aligned in channels. It was found that this framework material can also be formed by mechanochemical synthesis, and investigation of the thermal behaviour of this framework showed that it has the potential to be porous, since the framework appears to remain intact after desolvation. Furthermore, six novel structures with N,N'- bis(glycinyl)pyromellitic diimide in combination with various N-heterocycles were obtained. All structures obtained in this study were also further analysed to determine whether there are particular structural features that are required for framework formation. Insights gained from these investigations, in terms of degree of ionisation of the anion, packing arrangements and hydrogen bonding patterns as well as the molecular shape of the components are discussed. / AFRIKAANSE OPSOMMING: Die doel van die werk wat in hierdie tesis voorgelê word is om ioniese organiese raamwerkmateriale gebaseer op karboksilaatione te ontwerp, met die voorneme om interessante eienskappe in hierdie materiale te bewerkstellig. Die eerste afdeling fokus op die karakterisering en porositeit van ‘n ioniese organiese raamwerkmateriaal, 3,4-lutidiniumpamoaathemihidraat, wat kanale gevul met tetrahidrofuraan (THF) besit. Dit is aangetoon dat dit moontlik is vir hierdie raamwerkmateriaal om die THF in die kanale te verruil vir ‘n wye verskeidenheid stowwe, waarvan baie van hierdie uitruilings geskied as ‘n enkelkristal tot enkelkristal transformasie. Kompetisie-eksperimente is met hierdie raamwerkmateriaal uitgevoer deur die kristalle in mengsels van oplosmiddels te onderdompel, sowel as deur die kristalle aan mengsels van die oplosmiddeldampe bloot te stel. Die resultate het aangedui dat dit moontlik is vir hierdie raamwerkmateriaal om een gasstof selektief teenoor ‘n ander te verruil vir die THF in die kanale. Die kinetika van die uitruilingsproses van hierdie materiaal is ook bestudeer en dit was moontlik om ‘n kinetiese model te identifiseer wat die uitruilingsproses beskryf. ‘n Tweede nuwe raamwerk-tipe materiaal, 4-fenielpiridiniumpamoaat, is deur die loop van hierdie studie geïdentifiseer, sowel as vyf isostrukturele raamwerkmateriale waarvan net die gasstof verskil. In hierdie geval bestaan die raamwerk uit diskrete eenhede wat op so ‘n wyse saampak dat die gasstowwe in vernoude porieë ingesluit word. Alhoewel hierdie raamwerk-tipe materiaal nie poreus is nie, is dit termies stabiel en ook hoogs selektief. Die raamwerkmateriaal kan selektief 1,4-dioksaan enkapsuleer wanneer dit gekristalliseer word vanuit ‘n verskeidenheid oplosmiddel kombinasies met 1,4-dioksaan. Verder is agt nuwe strukture verkry met die pamoaat ioon in kombinasie met ‘n verskeidenheid piridien-derivate. ‘n Derde nuwe raamwerkmateriaal is verkry met N,N'-bis(glisiniel)piromellitiese diïmied waarin, danksy die uitgebreide waterstofgebinde netwerk tussen die komponente van die raamwerk, die DMF molekules in kanale aangetref word. Hierdie raamwerkmateriaal kan deur meganochemiese sintese berei word en verdere ondersoek na die termiese gedrag van hierdie raamwerkmateriaal dui aan dat dit die potensiaal het om porositeit te toon, aangesien die raamwerk behoue bly nadat die DMF molekules verwyder is. Ses nuwe strukture is ook met N,N'-bis(glisiniel)piromellitiese diïmied in kombinasie met ‘n wye verskeidenheid stikstof-bevattende heterosikliese verbindings verkry. Alle strukture wat tydens hierdie studie verkry is, is verder ondersoek om te bepaal of daar spesifieke strukturele kenmerke is wat benodig word vir die vorming van raamwerkmateriale. Insigte wat verkry is vanuit hierdie ondersoeke, in terme van die graad van ionisasie van die anioon, die rangskikking van molekules in die struktuur en waterstofbindingspatrone, sowel as die molekulêre vorm van die komponente, word bespreek.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The aim of this thesis was to study structure-property relationships in porous materials using various adapted analytical techniques and in-house instruments. The thesis is divided into two sections, and the first section of work constitutes the majority of the thesis. The first section of work deals with the theoretical versus experimental classification of sorption selectivity in porous compounds. A transiently porous metallocycle that can adsorb acetylene and carbon dioxide served as a model host for this experiment. A volumetric sorption instrument had to be constructed to carry out sorption with acetylene. Even though the metallocycle should theoretically be selective for acetylene over carbon dioxide based on single-gas sorption isotherms, this was not the case during the sorption of a mixture of the two gases. Furthermore, high-pressure single-crystal diffraction was carried out utilising an in-house environmental gas cell, and structural elucidation indicated that both acetylene and carbon dioxide coexist in a single cavity of the host. Additional complementary techniques are discussed that were used to confirm that both gases are present in a single host cavity. The techniques included infrared spectroscopy as well as high-pressure florescence and Raman spectroscopy, which had to be conducted with a specially designed pressure vessel and with adapted instrumentation. Finally, density functional theory calculations were employed to explain how host-guest and guest-guest interactions lead to the change in adsorption selectivity. It is concluded that researchers need to show experimentally that a compound is selective for the adsorption of a specific gas, because theoretical models are not always accurate. The second part of this work focuses on a fundamental study of the structure-property relationships in a porous hydrogen-bonded organic framework. The section starts off by exploring the activation conditions and thermal stability of the framework. This is followed by an exploration of a possible phase transformation or thermal expansion in the framework, but neither of these occurred. Thereafter, an extended study of the framework’s sorption behaviour with various gases is discussed. Then, a structural study of its solvated phase is used to explain the framework’s stability. Finally, a novel analytical method is introduced, and two examples are used to demonstrate why the instrument is useful in the field of supramolecular chemistry. The chapter is concluded by stating the importance these fundamental studies, as well the development of new analytical techniques. / AFRIKAANSE OPSOMMING: Die doel van hierdie tesis was om die struktuur-afhanklike eienskappe van poreuse materiale te ondersoek. Die studie het gebruik gemaak van verskeie aangepasde analitiese metodes asook instrumente wat spesifiek vir die studie gebou was. Die werk word in twee dele verdeel, en die meerderheid van die tesis word in die eerste deel bevat. In die eerste deel van die tesis word die validiteit van teoretiese- teen eksperimentele adsorpsie selektiwiteit opgeweeg. ʼn Gasheer wat bestaan uit ringvormige koördinasie-verbindings en wat asetileen asook koolstof dioksied kan adsorbeer, dien as ʼn model gasheer vir die studie. ʼn Volumetriese sorpsie instrument was spesiaal vir die studie gebou sodat asetileen sorpsie gedoen kon word. Volgens asetileen en koolstof dioksied se enkel-gas adsorpsie isoterme moet asetileen teoreties met voorkeur geadsorbeer word gedurende ʼn adsorpsie eksperiment waarin beide gasse teenwoordig is, maar eksperimenteel was dit bepaal dat dit nie so is nie, dus is daar ʼn verandering in die gasheer se adsorpsie selektiwiteit. Hierna word strukturele data van die gasheer, onder ʼn hoë druk van die gas mengsel, versamel deur gebruik te maak van enkel-kristal diffraksie en ʼn spesiaal-gemaakde gas sel. Die strukturele data toon dat beide asetileen en koolstof dioksied teenwoordig is binne elke porie van die gasheer. Daar word dan van addisionele analitiese metodes gebruik te maak om die observasie te bevestig. Die analitiese metodes sluit in infrarooi spektroskopie asook hoë-druk fluoressensie en Raman spektroskopie wat geëis het dat ʼn spesiale druk-bestande monster houer gebou moes word en dat analitiese instrumente gemodifiseer moet word. Ten slotte was daar van “density functional theory” gebruik gemaak om te verduidelik dat die interaksie tussen die gasheer en gas sowel as die interaksie tussen twee gasse lei tot die verandering in adsorpsie selektiwiteit. Uit hierdie bevinding word die gevolgtrekking gemaak dat navorsers met meer eksperimentele data vorendag sal moet kom voordat ʼn gevolgtrekking gemaak kan word dat ʼn raamwerk selektief een gas adsorbeer. Die tweede afdeling van die werk fokus op ʼn fundamentele studie van die struktuur-afhanklike eienskappe van ʼn poreuse waterstof-verbinde organies raamwerk. Die afdeling begin deur ʼn ondersoek van die aktivering kondisies sowel as die temperatuur-afhanklike stabiliteit van die raamwerk. Dit word gevolg deur te soek na moontlike fase veranderings of temperatuur-afhanklike uitsetting van die raamwerk, maar nie een van die twee eienskappe word waargeneem nie. Daarna word die deeglike ondersoek van die raamwerk se adsorpsie vermoë met verskeie gasse bespreek. Dit word gevolg deur ʼn strukturele studie van die solvaat van die raamwerk, wat dan gebruik word om die stabiliteit van die raamwerk te verduidelik. Ten slotte word ʼn analitiese metode bekend gestel, en twee voorbeelde word gebruik om te wys hoe nuttig die metode is om ʼn kombinasie van resultate te bekom. Die hoofstuk word saamgevat deur te verduidelik hoekom dit belangrik is om hierdie tipe fundamentele studies te doen asook waarom nuwe analitiese metodes ontwerp moet word.

Within industrial product development processes there is an increasing demand towards reliable predictions of the material behavior, which aims to promote a property driven development that can reduce the lead times. The implementation of simulation based product development with integrated casting simulation may enable the design engineers to gain an early understanding of the products with relation to castability, and orient the subsequent design refinement so as to achieve the desired mechanical properties. This work investigates the suitability of three commercial casting simulation softwares –MAGMA 5.2, NovaFlow &amp; Solid 4.7.5 (NFS) and Click2Cast 3.0 (C2C)–, with respect to the needs of design engineers, such as prediction of shrinkage porosity and mechanical properties with relation to the design. Simplified solidification simulations suitable for this stage were thus performed for three high pressure die cast components with different geometrical constraints. The comparability between the solidification and cooling behaviour predicted by the three softwares was studied, and showed that a reasonably good agreement between predicted solidification times by MAGMA and NFS could be obtained, albeit not between predictions by MAGMA and C2C. Predictions by the three softwares of the hot spot/porosity areas showed to have a good agreement. The calculation times by each software were compared, and MAGMA was seen to have the best performance, yielding significantly shorter times than NFS and C2C. The results obtained were also compared to experimental investigations of porosity, microstructural coarseness, and mechanical properties. There was a good agreement between the predicted hot spot areas –i.e. areas in the geometry that solidify last– and the findings of porosities in the actual castings, meaning that solidification simulations might be able to provide important information for the prediction of most of shrinkage related porosity locations that are related to the casting geometry. However, the lack of a detailed knowledge at the design stage of the casting process limits the possibilities to predict all porosities. The predicted microstructure and mechanical properties by MAGMA non-ferrous were seen to have a good agreement in trend with the experimental data, albeit the predicted values showed large differences in magnitude with the experimental data. Although, the MAGMA non-ferrous module was not developed for HPDC components, it was interesting to study if it could be applied in this context. However, the models seem to need adoption to the HPDC process and alloys. In conclusion, with a limited knowledge of the manufacturing parameters, simplified solidification simulations may still be able to provide reasonably reliable and useful information during early development stages in order to optimise the design of castings.