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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.
251

L’éthique au risque de son institutionnalisation : l’Événement est-il possible au sein des machines à guérir hospitalières ? / Ethics and the risk of institutionalisation : incidence is the event possible at the heart of the hospital curing machine?

Chvetzoff, Roland 22 June 2016 (has links)
L’éthique en santé bénéficie aujourd’hui d’un cadre réglementaire et normatif incitatif, obligeant les établissements à déployer une réflexion éthique. Mais cette éthique qui a lieu dans nos institutions de santé se prête-t-elle sans risque à son institutionnalisation ?Car en effet les institutions de santé sont devenues aujourd’hui des « thérapeutiques » qui obligent à des légitimes objectivation et nécessitent une organisation en machines à guérir hospitalières. Des machines où la question du mal est relativisée, voire déniée au profit du bien : il n’y a plus de mal, tout au plus des maux qu’il convient de gérer et de traiter avec des outils technoscientifiques et de gestion. Or « la question éthique ne se pose que par le fait que le mal existe ». Les machines à guérir déploient un arsenal de dispositifs dont l’intentionnalité est de guérir, mais également d’empêcher que ne survienne tout événement indésirable (Éi). Il s’agit bien sûr de guérir de la maladie, mais également de guérir d’un risque : celui de l’événement. Mais l’événement est récupéré par la machine hospitalière pour être requalifié en Éi. L’événement est vécu comme un Éi que le « qualéthicien » fera passer au crible du « pourquoi ? » à la recherche d’une causalité vulgaire. Ici apparaît tout l’enjeu de l’institutionnalisation de l’éthique : amener les institutions à faire de l’Éi un « événement désirable » en faisant culminer les professionnels dans l’événement, au lieu de chercher à réduire ce dernier à une causalité certaine. Car « le mal est sans pourquoi », mais nous nous devons de le combattre. Penser l’institutionnalisation de l’éthique, c’est être attentif à la dialectique de la structure et de l’événement comme synthèse ajournée. Cette non-synthèse permet de penser et la machine et l’événement comme deux concepts indissociables. Au delà de l’Ei, l’événement éthique (ÉÉ) apparaît comme la possibilité de survenue du mal. Car une éthique dont l’objectif serait d’éradiquer le mal viserait également à éradiquer la liberté. / Today, ethics with regard to health benefits from a regulatory and standardised framework incentive, obliges the establishments to deploy an ethical reflection. But do these ethics taking place in our health institutions come with no risk of institutionalisation?In effect, health institutions these days have become "therapeutics" that require legitimate objectification and necessitate organisation within the hospital curing machine. Machines where the question of evil is relativised, or even denied for the public good: there is no evil other than ailments that it needs to manage and treat with technoscience and management tools. Or "the ethical question arises just because of the fact this evil exists." The machines for curing deploy an arsenal of devices of which the intention is to heal, but equally to prevent the occurrence of adverse events. This means of course to cure the disease, but also to cure any risk: that of the event. But the event is recuperated by the hospital machine to be reclassified as adverse event. The event is experienced as an adverse event that an “ethics quality controller” will sift through to find the "why?" in the search for a common causal event. It is at this point that the challenge arises for institutionalising ethics: to lead institutions to make the adverse event a "desirable event" by culminating professionals in the event, instead of trying to reduce it to a certain causality. Because "evil has no why", but we do need to combat it.The consideration of the institutionalisation of ethics, is to be attentive to the dialectic of structure and of event as a delayed synthesis. This non-synthesis enables thinking, and the machine and the event to become two inseparable concepts. Beyond the adverse event, the ethical event (EE) appears as the possibility of the occurrence of evil. For ethics the objective of eradicating evil would equally aim at eradicating freedom.
252

Network Formation In Amine Curing Of Higher Functional Epoxy Resins

Rajakumari, P Maria Nirmal 01 1900 (has links) (PDF)
No description available.
253

Development and Engineering Properties of Construction Materials Made Using Melted Plastics Wastes as the Only Binding Phase

Thiam, Moussa 07 September 2021 (has links)
Modernization has brought about steady increase in the consumption of goods and services by human societies across the globe, which mostly driven by both population growth and the change of individual living standards. This, of course, leads to an ever-increasing waste production that ends up in landfills and very often as a source of pollution on natural ecosystems, especially in the low and middle-income countries where waste management is almost inexistent. The management of waste streams is a huge challenge for developed countries as well, where societal and environmental impacts are visible despite massive investments in waste management. One of the most problematic waste materials is plastic, which can remain in nature for over 100 years without degradation, leading to serious environmental concerns. As one of the most significant innovations of the 20th century, plastic is a widely used and cost-effective material for many applications. After their useful lifetimes, their management is problematic. Thus, robust and innovative approaches of managing such waste material are needed in order to mitigate the problem. One of the innovative approaches of tackling the menace cause by plastic waste is through its incorporation into the construction materials. This thesis seeks to address this problem by exploring the use of melted plastic wastes (High Density Poly Ethylene, HDPE and Low Density Poly Ethylene, LDPE) as binder in developing new construction materials (mortar with melted plastic as the only binder, MPB and Plastic Waste Crete, PWC) as an alternative to partially replace traditional concrete and mortar, or finding other engineering uses for this type of waste. Worldwide, about 190 m3 of concrete is poured every second, which translates to 6 billion m3 per year and making it, one of the most widely used manufactured materials. However, the production of concrete requires water and cement. Cement is expensive, and its production contributes to the emission of environmentally polluting gases. Replacing this binding element with recycled plastic derivatives would have significant economic and environmental benefits. In addition to the elimination of cement cost, this will result in water savings, which is especially important for areas without fresh water scarcity. Some researchers have used plastics in concrete and mortars as additives and/or replacement for fine and coarse aggregates. In addition, different types of plastics have been used in bitumen as an additive to reduce construction cost and improve sustainability by adding value to wastes materials. However, there is paucity of technical information about the use of the melted HDPE and LDPE plastic wastes as the only binding phase in concrete- or mortar-like materials. Moreover, many parameters such as preparation conditions, field variables, constituent elements, and final applications have impacts on the performance of construction materials Thus, the key objective of this PhD research is to develop the mortar with plastic binder (MPB) and PlasticWasteCrete (PWC) by using molten HDPE and LDPE plastic wastes as the only binder as well as to investigate the engineering properties of these new types of construction materials. The plastic contents of 45%, 50%, 60% and 65% and HDPE to LDPE ratios of 40/60, 50/50, and 60/40 were selected for the experimental tests. Clean river sand was used as the only aggregate for the MPB, while both sand and gravel were used for the PWC. Various tests were then performed on prepared MPB and PWC samples at different curing times from early to advanced ages to assess their engineering properties. These tests were conducted in accordance with the ASTM standards to evaluate the mechanical properties (compressive strength and splitting tensile strength), permeability and density of the MPB and PWC materials. Additional tests were carried out to analyze the products at the microstructural level (optical microscope, SEM, MIP and thermogravimetric analysis) to gain an insight into the microstructural properties of the developed materials and how that affect their engineering properties. The compressive strength tests revealed the optimal plastic content for the MPB and PWC with the best strength performance. The average compressive strength values for various optimal formulations after 28 days were found to be in the range of 9 to 18 MPa. The splitting tensile strength for the new materials from 1 to 28 days of curing time, were found to be between 1 and 5 MPa. The average hardened density of the MPB and PWC is about 2 g/cm3, which makes them lightweight material according to RILEM classification. In addition, various absorption tests (capillary and immersion) were performed on different MPB and PWC samples, and the obtained results showed that they are porous materials having lower rate of absorption than the traditional cementitious materials (mortar, concrete). This observation was supported by the results from both MIP and SEM analyses. Finally, thermogravimetric analysis provided interesting details on the thermal decomposition of the new materials, with significant changes or mass loss for these products being observed only at temperatures higher than 300°C. The findings from this study suggest MPB and PWC made with melted plastic waste as the only binder have a promising potentials for use in construction. The research conducted in this PhD study offers a good understanding of the engineering properties of the materials as well as the optimal formulations that yield best performance in terms of strength and durability. In summary, it provides useful technical information and tools on the MPB and PWC that will contribute in setting guidelines on the optimal applications of these products in the field of construction in order to have safe, durable and cost-effective structures. Résumé Avec la modernisation de nos sociétés, les habitudes ont considérablement changé, ainsi, on observe une forte consommation des biens et services, due à l’augmentation de la population et l’amélioration de leurs conditions de vie. Ce qui conduit à une augmentation considérable des quantités des déchets qui terminent leurs cycles au niveau des décharges ou dans les océans/fleuves devenant ainsi une source de source de pollution des écosystèmes naturels, surtout dans les pays à revenu faible et intermédiaire avec des systèmes défaillants ou moins performants de gestion des déchets. La gestion des flux de déchets est aussi un défi pour certains pays développés, où les impacts sociaux et environnementaux sont visibles en dépit des investissements massifs dans ce secteur. Parmi ces déchets, nous avons les plastiques, l’une des innovations du 20e siècle avec des qualités versatiles et coût faible, se trouve partout dans nos vies quotidiennes. Après leur utilisation, les plastiques deviennent des déchets qui peuvent rester dans la nature plus de 100 ans sans aucune dégradation, avec des conséquences néfastes sur l’Homme et l’environnement. Ainsi, une approche robuste et innovante de gestion de ces déchets est nécessaire afin d'atténuer leurs impacts. L'une des approches innovantes pour réduire l’impact causé par les déchets plastiques consiste à les incorporer dans les matériaux de construction. Ainsi, le problème est abordé dans cette thèse en développant des technologies permettant de recycler les plastiques fondus comme liant dans les nouveaux matériaux de construction (MPB et PWC), afin d’offrir une alternative pour remplacer partiellement le béton / mortier traditionnel. Le béton est l’un des matériaux les plus utilisés au monde, avec environ 190 m3 coulés chaque seconde, correspondant à 6 milliards de m3 par an. Cependant, la production de béton nécessite de l'eau et du ciment. Le ciment coûte cher et sa production contribue à l'émission de gaz polluants l'environnement. Le remplacement d'une partie du béton traditionnel par un matériau à base des déchets plastique aura des avantages économiques, sociaux et environnementaux importants. Allant dans ce sens, certains chercheurs ont utilisé les plastiques dans le béton et le mortier comme additifs et / ou substituts des matériaux granulaires tels que le sable et le gravier. Aussi, différents types de plastiques ont été utilisé dans le bitume comme additif pour réduire les coûts de construction et améliorer la durabilité, ainsi contribuer à donner de la valeur aux déchets. Cependant, jusqu'à présent, il existe peu d’informations techniques sur l'utilisation de déchets plastiques (HDPE et LDPE) fondus comme seuls liants pour développer de nouveaux types de matériaux de construction. En plus, plusieurs facteurs (les conditions de préparation, les éléments constitutifs, les applications finales, etc.) ont un impact sur les caractéristiques des matériaux de construction. Ainsi, l'objectif de cette recherche doctorale est de développer des nouveaux matériaux de construction (MPB et PWC) en utilisant les déchets plastiques fondus (HDPE et LDPE) comme seul liant, puis déterminer les propriétés caractéristiques de ces matériaux afin de trouver la formulation optimale conduisant à la meilleure résistance. En plus de l'élimination du coût du ciment, cette technologie permet aussi de faire des économies d'eau, bénéfique surtout pour les zones avec des difficultés d'accès à l’eau potable. Cela contribuera à la réduction des coûts de la construction en utilisant les produits innovants comme alternative au béton / mortier conventionnel. Un vaste programme expérimental, comprenant des tests à petite et grande échelle, a été développé afin d'atteindre les objectifs de cette étude de doctorat. La campagne expérimentale a comporté différentes étapes comprenant la sélection des matériaux, la détermination de la formulation optimale et les conditions appropriées pour la préparation des matériaux susmentionnés. Par la suite, pour une meilleure compréhension du comportement technique et des propriétés du produit final, divers tests ont été effectué sur les matériaux préparés à différents temps de durcissement. Ces tests ont été menés conformément aux normes ASTM pour évaluer les propriétés mécaniques (résistance à la compression et à la traction), la perméabilité et la densité des nouveaux matériaux. Les expériences ont été approfondies en analysant les produits au niveau microstructural (microscope optique, SEM, MIP et analyse thermique) pour avoir un aperçu des propriétés microstructurales des matériaux développés et essayer de comprendre les relations avec leur comportement mécanique. Les essais de compression ont permis de trouver la teneur en plastique optimale pour les matériaux (MPB et PWC) avec les meilleures valeurs de résistance. Les résistances moyennes à la compression à 28 jours pour diverses formulations étaient comprises entre 9 et 18 MPa. La résistance à la traction par fendage des nouveaux matériaux entre 1 et 28 jours se situait entre 1 et 5 MPa. La densité moyenne du béton et mortier écologique est proche de 2 g / cm3, ils peuvent donc être considérés comme des matériaux légers selon la classification RILEM. De plus, divers tests d'absorption (capillaire et par immersion) ont été réalisé sur différents échantillons de MPB et PWC, les résultats obtenus ont montré qu'il s'agit de matériaux poreux ayant un taux d'absorption plus faible que les matériaux traditionnels contenant du ciment. Plusieurs analyses microstructurales ont été réalisées sur différents échantillons des nouveaux produits (MPB et PWC) et les matériaux cimentaires traditionnels ont été utilisés pour renforcer notre compréhension. Enfin, l'analyse thermique a fourni des détails intéressants sur la décomposition thermique de ces nouveaux matériaux ; des changements significatifs avec une perte de masse considérable ont été observés seulement pour des températures supérieures à 300 ° C. Les résultats de ces essais permettent d'acquérir une bonne compréhension des propriétés techniques des nouveaux matériaux (MPB et PWC) ainsi que de déterminer les teneurs optimales en plastique conduisant aux meilleures performances en termes de résistance et de durabilité. Ainsi, les recherches menées dans cette étude de doctorat fournissent des informations techniques et des outils utiles sur le MPB et le PWC; et contribueront à installer des bases pour guider les applications optimales de ces nouveaux produits dans le domaine de la construction afin d'avoir des structures sûres, durables et rentables.
254

Studie vlivu složení a ošetřování cementových litých potěrů na jejich vlastnosti v rané fázi zrání / Study of the influence of composition and curing of self-leveling cement screeds on their properties in the early stage of maturation

Powetz, Dominik January 2021 (has links)
The diploma thesis deals with the study of the influence of composition and curing of self-leveling cement screeds on their properties in the early stage of maturation. Within this work, various concepts of ensuring the volume stability of cement self-leveling screeds were verified. An anti-shrink additive based on neopentyl glycol and an expansion additive based on hard-burnt lime were used as modifiers. The reduction of plastic and overall shrinkage using various types of liquid membrane-forming compounds was verified on the most volume-stable screed using the optical dilatometry method. The effectiveness of the individual solutions was monitored by continuous measurement of the intensity of evaporation from the screed surface. Subsequently, the effect of membrane-forming compounds on the residual moisture of the cured treated cement self-leveling screed was measured by the carbide method and also the effect of this curing on the adhesion of bonded ceramic tiles.
255

Fosfátová pojiva / Phosphate binders

Kalina, Lukáš January 2008 (has links)
The work deals with the preparation and study of polyphosphate composites. Aluminum phosphates provide some unusual properties like high-heat resistance in terms of inorganic binders. The addition of chromium in the form of Cr2O3 or directly the bond with the aluminum-chromium-phosphate can improve the properties of this binder. Highly viscous Al2Cr(H2PO4)9 and Al3Cr(H2PO4)12 binders were prepared by dissolving Al(OH)3 and CrO3 in 85% phosphoric acid, and mixed with Al2O3 and Cr2O3 fillers. The composites were cured in the furnace at 150 °C for 24 h under pressure of 10 MPa. During the annealing at temperatures up to 1 500 °C changes in chemical structure of the cured composites were observed, leading to the understanding of the creation of crystalline phases and their eventual changes. The characterization of binders was mainly based on FT-IR, EDAX, TG-DTA and optical microscopy analyses.
256

Vliv podmínek ošetřování na vlastnosti alkalicky aktivované strusky / Effect of curing conditions on the properties of alkali activated slag

Rypák, Peter January 2015 (has links)
Combination of fine ground granulated slag with proper alkaline activator gives alkali-activated slag – a material with remarkable properties. Theoretical part of the thesis deals with summarizing basic informations about alkali-activated slag, its properties, production and utilization. It also follows research devoted to effects of curing of alkali activated slag and shrinkage-reducing admixtures on its properties. Objective of the experimental part is to determine the influence of curing conditions on the mechanical properties and microstructure of alkali-activated slag. These properties are also monitored in alkali-activated slag with carbon nanotubes and hydroxypropylmethylcellulose as an shrinkage-reducing admixtures.
257

Vliv způsobu vypalování na kvalitu laku / Influence of the burn method on varnish quality

Svačina, Roman January 2015 (has links)
The thesis deals with the influence of the curing process on varnish quality of paint powder coating. The thesis includes a literary study focused on the issue of powder coating. In the experimental part of the work will be done curing of two different materials in three technically different kilns and compare the effect of firing.
258

Studium účinnosti polymerní přísady EVA v závislosti na ošetřovacích podmínkách malty / Study of the Effectiveness of Copolymer EVA Depending on Storage Conditions of Mortar

Hlawiczka, Jakub January 2016 (has links)
The Diploma thesis is adressing the issue of polymer-modified mortars (PMM) and theirs properties in dependence on curing conditions. The reasons of using polymer additives and some selected applications of PMM are described in theoretical part of this work. Cementitious composite (mortar) hardening is especially focused on mechanism of formation co-matrix system based on cement hydration products and polymer film in dependence on curing conditions. The knowledge of interaction of cement and ethylene-vinyl acetate (EVA) copolymer is presented in the latest paragraphs of theoretical work. Following practical part presents influence of EVA to physical and mechanic properties of PMM in dependence of dosage polymer additive and exogenous factors. The study of microstructure was investigated by scanning electron microscope and high-pressure mercury porosimetry. Tests and investigations are described and evaluated.
259

Effect of temperature on the sustainability of eco-engineered cementitious composites: curing, extreme conditions and service life

Vito Francioso (12419578) 14 April 2022 (has links)
<p>With over 30 billion tons of global annual production, concrete is the most used construction material in the world. Its manufacturing is associated with a strong environmental impact due to the high natural resources’ consumption, energy consumption, and a large generation of wastes and pollutants with significant global consequences. There are many different approaches to reduce the environmental impact of cementitious materials. Two examples are: (i) the use of recycled aggregate (RA) such as recycled concrete aggregate (RCA) and recycled plastics, or supplementary cementitious materials (SCMs) such as biomass ashes to reduce the use of natural aggregates and cement, respectively, and (ii) using nano-additives (for instance, nano-TiO2) to enhance material’s performance and to provide the material new properties that may have a positive proactive effect during its service life (i.e., photocatalytic properties that may reduce different pollutants concentrations from the environment). These approaches have been widely studied in standard conditions. However, boundary conditions such as temperature or moisture can be critical factors that directly or indirectly affect the effect of these approaches on the sustainability of cementitious composites in all stages of their life, from curing to service conditions.</p> <p>It is known that curing temperature influences the effect of using recycled materials (such as RCA or SCMs) on the mechanical properties of cementitious materials. However, there were no studies concerning the influence of curing temperature on the nano-TiO2 addition effect on mechanical properties of cementitious composites. A potential change will affect composites’ sustainability; if curing temperature influences the effect of nano-TiO2 on strength, the cement content needed to achieve a given performance will variate. This study concluded that curing temperature is a key factor that changes the effect of TiO2 nanoparticles on mechanical properties and pore structure of Portland cement mortars; the lower the curing temperature, the higher the positive effect of TiO2 on compressive strength.</p> <p>Besides the use of nano-TiO2, the substitution of NA with RCA might significantly benefit the sustainability of cementitious composites. However, the use of RCA may lead to a reduction in strength. On the other hand, the addition of nano-TiO2 mixtures containing RCA might offset this reduction in strength. Nevertheless, studying their effects on the composites’ performance under extreme conditions is critical to assess the actual environmental impact since durability is one of the main pillars of cementitious materials sustainability. This study concluded that even though RCA may be beneficial to increase sustainability aspects in terms of net waste generation and natural abiotic depletion, its potential negative effects on high-temperature resistance should be considered to not lead to structural problems during its lifetime, especially if used in combination with nano-TiO2. The addition of low percentages of nano-TiO2 has a negative effect on the high-temperature resistance of mortar containing 100% RCA. Differences in thermal properties between old aggregate, old cement paste, and new cement paste with nano-TiO2 may induce internal stresses at high temperatures that can produce a failure at lower strength due to the weaker interfacial transition zone (ITZ) between the stronger new cement paste (with nano-TiO2) and the old cement paste. To the same extent, it is important to understand how extreme temperatures impact the effect of other recycled materials in cementitious composite performance. This study found that recycled polypropylene (re-PP) fibers may mitigate the strength loss caused by high-temperature exposure, enhance the residual flexural strength, and increase the energy absorption capability. The changes in the fiber-matrix ITZ after cooling observed through an optical microscope suggested that the mechanical improvements are related to an enhancement of the fiber-matrix ITZ after high-temperature exposure and cooling.</p> <p>The next part of the dissertation focused on studying the thermal conductivity susceptibility to ambient conditions variation and how RCA substitution can affect this susceptibility. Understanding the effect of RCA on the thermal conductivity of cementitious composites would be crucial to assess their effects on the environmental impact during service life as part of a building component. Results showed that the higher percentage of porosity (due to RCA utilization) increases the susceptibility of thermal conductivity to moisture. Thus, actual moisture content and temperature should be considered when assessing the effect of RCA on thermal conductivity and its influence on sustainability in terms of energy savings when used as part of building envelops.</p> <p>Finally, the last part of this dissertation focused on assessing the impact of curing temperature on the sustainability of sugarcane bagasse ash (SCBA) as a partial replacement of cement in mortars. An experimental campaign was performed to evaluate the effect of partial replacement of cement with SCBA on compressive strength as a function of curing temperature. Hence, a life cycle assessment (LCA) was performed from the extraction of the raw materials to the material production part of the life cycle, using as a functional unit 1 m3 of mortar with the same compressive strength as the reference mixture (plain Portland cement mortar without SCBA) cured at the same temperature. Results showed that a replacement of 97 kg of cement by SCBA (per m3 of mortar) may produce a reduction of the environmental impacts two times higher when the curing temperature was 45°C than when the temperature was 21°C. Results clearly indicate that the sustainability of SCBA utilization as a partial replacement for cement will be higher when mortar is poured in hot regions or during days with higher temperatures. Therefore, external curing temperature is an important factor that should be considered when assessing the sustainability of cementitious composites containing sugarcane biomass ashes.</p>
260

Short wavelength UV–LED photoinitiated radical polymerization of acrylate–based coating systems—A comparison with conventional UV curing.

Torfgård, Olof January 2021 (has links)
The present work was performed at Sherwin–Williams Sweden group AB with the objective of comparing short-wavelength light emitting diodes (UVB/UVC) with the conventional mercury arc lamp as a curing method of acrylate-based, UV-paint undergoing free-radical polymerization when exposed to UV-radiation. Due to environmental and health risks, mercury-doped radiation sources will be phased out in the near future, according to the United Nations Minamata convention, hence new alternatives are needed. Light-emitting diodes differ from the mercury arc lamp as they provide semi-discrete output intensity lines within the UV spectrum instead of a broad output distribution with several main intensity lines. The power output is also considerably lower compared to the conventional method which limits the irradiance and dose that are key parameters in activating and propagating free-radical polymerization of UV-paint. Seven different light-emitting diodes between 260–320 nm was examinedand compared to the conventional mercury arc lamp. Cured coatings were evaluated by measuring the relative extent of acrylate conversion with ATR-FTIR and micro-hardness indentation test. Both methods correlate to the relative cross-linking density and qualitatively describe the curing process for each radiant source at a specific irradiance and dose. Three different paint formulations with widely different properties were used in the experiments. All three paints were able to cure with one or several light emitting diodes at comparable doses and 10 to 20 times lower irradiance to the conventional mercury arc lamp, resulting in similar acrylate conversion and hardness.

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