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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.
121

Valorisation de résidus agroindustriels comme matériaux pour l'habitat et la construction : utilisation de la bagasse dans les liants composés minéraux et les composites / Valorization agroindustrial wastes as housing and building materials : use of bagasse in composed binders and composite materials

Ratiarisoa, Rijaniaina 15 June 2018 (has links)
La présente étude vise à valoriser des résidus agroindustriels comme matériaux pour l’habitat et la construction. Dans ce contexte, les travaux de recherche s’articulent autour de deux axes majeurs : le développement d’un liant alternatif et l’élaboration de matériaux composites à partir de ce liant alternatif et des matériaux végétaux. Deux liants composés utilisant des cendres de bagasse, nommés cendres de bagasse-chaux et ciment-cendres de bagasse ont été étudiés. A partir de ces liants composés, deux types de matériaux composites incluant des matériaux végétaux ont été élaborés : un composite incorporant des granulats de bagasse et de coco et un autre renforcé par des pulpes d’eucalyptus. Les propriétés physiques, chimiques, mécaniques et hydriques de ces matériaux ont été déterminées. Les résultats obtenus montrent que la calcination des cendres de bagasse à 600°C et la sélection des particules de taille inférieure à un diamètre seuil compris entre 45 et 63µm augmentent sa réactivité. Le liant composé cendres de bagasse-chaux est susceptible de développer une résistance à la compression de l’ordre de 39MPa à 28 jours, une valeur supérieure à celle des liants composés matériaux pouzzolaniques-chaux étudiés dans la littérature. Grace à sa faible alcalinité, ce liant composé préserve mieux les matériaux végétaux vis à vis de leur minéralisation et leur fragilisation comparativement au liant à base de ciment. L’incorporation de pulpes cellulosiques dans le liant composé cendres de bagasse-chaux permet d’obtenir des matériaux composites ayant des propriétés à la flexion comparables à celles d’un composite ciment-pulpes cellulosiques. / The present study aims to add value to agroindustrial residues as housing and building materials. In this context, the research works revolve around two main lines: the development of an alternative binder using agroindustrial residues and the production of composite materials from this alternative binder and plant resources. Two composed binder using bagasse ash, named bagasse ash lime and cement-bagasse ash, were optimised and produced. Using these composed binder, two kinds of composite materials including plant resources were produced: one composite developed with vegetable aggregates and another one reinforced with eucalyptus pulps. The physical, chemical, mechanical and hydric properties of these materials were investigated. The results show that the bagasse ash recalcination at 600 °C and the selection of the particles under a diameter limit (between 45 and 63 µm) improve its reactivity. Blended with slaked lime, the composed binder obtained with these parameters is likely to develop a compressive strength higher than 39 MPa at 28 days; this value is higher than the compressive strength of pouzzolanic material and lime based binder studied in the literature. In addition, due to the lower alkalinity of the interstitial solution of this composed binder, related to the lime consumption by the pouzzolanic material, it better protects vegetable materials from mineralization than the binders based on Portland cement. The incorporation of the cellulosic pulps in the composed binder lime-bagasse ash produces composite materials with a similar flexural behaviour as a composite made with cement and cellulosic pulp.
122

Aplikace metamastku v anorganických materiálech / Meta-talc Application in Inorganic Materials

Bednárek, Jan January 2019 (has links)
This thesis is focused at possibilities of preparation and characterization of XRD-amorphous delaminated and dehydroxylated talc phase – meta-talc, which can have its potential application and a starter material for a preparation of magnesium-silicate analogues of geopolymers. Changes in structure and morphology of talc ore were observed during this work. For the purposes of this research, two various talc ores – chloritic and dolomitic were examined. Whole process of meta-talc preparation was examined with whole scale of instrumental techniques such as X-ray diffraction, simultaneous thermogravimetric a differential thermal analysis, infrared spectroscopy, scanning electron microscopy or laser analysis of particle size. Meta-talc can be obtained via mechanochemical activation of talc ore with subsequent calcination. Mechanochemical treatment lead to destruction of original crystal structure and breaking of original bonds, i.e. the product of this treatment was almost amorphous and delaminated. Most of hydroxyl groups were converted to molecules of water which remained adsorbed or coordinated in ore structure. These molecules were removed during calcination step.
123

Možnosti využití odkalů po vypírce vápence / The possibilities of use of sludges from limestone wash

Švec, Jiří January 2011 (has links)
In modern point of view of waste management is desirable to effectively process the grates possible amount of wastes. Sediments from cleaning of mined lime stones contains a lot of clay components, but there is also indispensable share of soft calcite. This composition makes these sediments a promising material for preparation of hydraulic binders. Production of common hydraulic binders, especially Portland cement, is very energy-intensive plus loads environment with considerable amount of combustion gases, therefore it is necessary to explore possibilities of alternative low - energy binders production and usage.
124

Vývoj tepelně izolačních a sanačních omítek pro památkovou péči / Development of thermal and sanitation plasters for historical buildings

Rajchot, Václav January 2013 (has links)
This thesis addressed the development renders the optimal ratio of thermal insulation and mechanical properties. In developing these materials were used alternative latent hydraulic binders. Research was conducted plasters and renders the requirements of technical standards in the Czech Republic. Work dealt with the general composition of plaster, including the use of secondary raw materials in dry plaster mixtures and thermal insulation properties and remediation plaster. Furthermore, the measured values of physical and mechanical properties of the test formulations. The best recipes were compared with plaster on the Czech market.
125

Studium pojivových systémů pro technologii Warm box / The study of binder systems for technology Warm box

Lenghardová, Romana January 2008 (has links)
The project elaborated in frame of engineering studies branch M2332-00. The project is submitting the study of binder systems for technology Warm box. Pursuant to the literary pursuit a problem of the technology Warm box these binders was tested: binder systems based of the Na-silicates, biogenous binders – proteins, polysacharides and fenol resins. Fenol resins and biogenous binders (K2 and Hide glue) showed to be optimal for core making technology Warm box. Biogenous binders are ecologically unexceptionable.
126

Optimierung der Pelletproduktion: Untersuchungen zum Einfluss von Pelletqualität und Feuerraumdesign

Lehmann, Bastian 06 September 2007 (has links)
Um bei der Herstellung der Holzpellets den Energieaufwand zu minimieren und gleichzeitig die Qualitätsanforderungen der DINplus zu erfüllen, werden häufig Presshilfsmittel beim Pelletieren eingesetzt, bisher vor allem Mais- und Weizenstärke. Um flexibler auf veränderte Markt- und Rohstoffbedingungen reagieren zu können, besteht von Seiten der Hersteller Bedarf an alternativen Presshilfsmitteln. Allerdings ist deren Einfluss auf das Verbrennungs-, Emissions- und Ascheerweichungsverhalten nur unzureichend erforscht. Im Rahmen eines Forschungsprojektes zur Optimierung der Pelletproduktion wurden in dieser Diplomarbeit Versuche durchgeführt, um den Einfluss verschiedener natürlicher Presshilfsmittel, der Pelletqualität (Feinanteil, Stückigkeit) und der Feuerungsart (Unterschub- und Abwurffeuerung mit Brennerschale) auf das Emissionsverhalten (Kohlenmonoxid-, Stickoxid-, Gesamtkohlenstoff und Staubgehalt im Abgas), den Anlagenbetrieb (Brennstoffförderraten, Abgasverluste, Luftüberschuss) und das Ascheerweichungsverhalten beim Betrieb von zwei Kleinfeuerungsanlagen mit DINplus-konformen Holzpellets, zu untersuchen.
127

STUDIUM BIOGENNÍCH POJIV / STUDY OF BIOGENOUS BINDERS

Cupák, Petr January 2011 (has links)
oundry production, which forms an integral part of the engineering industry, is a source of waste with a negative impact on the working and living environment. The pressure on greening the production in all production branches of industry does not dodge the foundry industry and technical engineers seek out possibilities of decreasing the negative impact of the production of casting on the environment. An important source of environmentally dangerous waste in foundry operation is the use of organic compounds during the preparation of shaping and core mixtures. Their substitution with materials that would ensure similar technological features of the shaping and core mixtures as the organic materials used hitherto and at the same time decrease the amount of solid, liquid and gaseous ecologically undesirable compounds used in or arising during the preparation and use of shaping and core mixtures, would be significant for decreasing the ecological burden connected to casting production. A promising group of materials usable as components of shaping and core mixtures are the biopolymer materials which can substitute the organic connective systems used in the production of foundry cores by the means of the so-called hot processes – Hot-Box and Warm-Box. This work focuses on the exploration of the technological and ecological features of several biopolymer materials available on the domestic market which have the potential to become a full alternative of the binders used so far on the basis of urea-formaldehyde, melamine-formaldehyde, phenol-formaldehyde and furan resins.
128

Využití R-materiálu v asfaltových směsích s vysoce modifikovaným pojivem (HiMA) / Use of R-material in asphalt mixtures with highly modified binder (HiMA)

Christ, Roman Unknown Date (has links)
The subject of this diploma thesis is paid attention to the influence of different dosing of R-material containing unmodified asphalt on the properties of asphalt concrete for abrasive layers (AC011 +) bonded with polymer highly modified asphalt (binder type HiMA). The properties of asphalt mixtures will be evaluated by means of the stiffness modulus test and the test of low-temperature properties by a uniaxial tensile test.
129

DESIGNING SUSTAINABLE AND SAFER ADVANCED BATTERIES THROUGH POLYMER TAILORING

Daniel A Gribble (16632606) 01 August 2023 (has links)
<p>As the future of energy looks increasingly electrified, the development of safe and sustainable battery technologies has never been more relevant. This is particularly critical for applications in stationary energy storage and transportation, where batteries must be produced and stored at large scale. Sustainability is necessary to meet the volume of demand at reasonable cost without straining resources. Safety is also paramount since fires can easily spread from one cell to the next and result in catastrophe when batteries are stored in proximity for large power banks or EVs. The focus of this thesis is thus to design and engineer materials for rechargeable batteries, which improve safety and sustainability while still enhancing the electrochemical performance. Towards this end, polymers play a central role throughout this thesis work due to their tunable chemical and physical properties.</p>
130

Design and Evaluation of Peptide Binders : In silico evaluation and comparison of generative AI for de novo peptide binder design

Brokmar, Linde January 2023 (has links)
Peptide binders are short proteins that bind to larger proteins. Due to peptide binders having high specificity and being cheap to synthesize, they are a prime candidate for drug design. Creating new proteins in silico can be divided into three steps: protein backbone generation, sequence design, and computational filtering. With the release of AlphaFold2 (AF2), protein structure prediction is possible with atomic accuracy, even for peptide-protein complexes. Structure predictions enables some important computational filtering, which saves time and resources before doing experimental validation. After the release of AF2 together with the advancements in generative AI, new computational methods for the first two design steps have been developed. In this report, three different methods for backbone generation and sequence design were evaluated and compared: EvoBind, RFdiffusion, and ProteinMPNN. The latter two were developed solely for protein design. However, their broad application capabilities allowed for peptide development, which was implemented in this report. In total, 5500 peptides for 55 different protein targets were designed by each method, with the purpose to evaluate the performance and identify advantages of the methods. Combining the three methods in unexplored ways allowed for additional evaluation as well as gaining deeper understanding of how the methods worked. Whilst not being one-shot design approaches, all methods used in the report showed potential of being able to design de novo peptide binders with varying degree of in silico success. The methods’ peptide design success rate ranged from 16% to 2.6%. The direct evolution approach applied with EvoBind generated most peptide binder backbones with close binding to the specified interfaces. Using the message passing neural network (MPNN) in ProteinMPNN, the sequences designed were optimized for binding affinity and resulted in sequences that were easier for AF2 to predict. The methods allow for the potential development of peptide binder therapeutics to become more cost- and time efficient, on the basis that AF2’s predictions are aligned with the expressed peptides’ bindings and structures.

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