• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 19
  • 12
  • 4
  • 3
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 77
  • 24
  • 21
  • 19
  • 17
  • 16
  • 15
  • 13
  • 12
  • 11
  • 11
  • 11
  • 9
  • 9
  • 8
  • 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.
71

Propuesta de mejora del comportamiento mecánico de Pavimentos Flexibles mediante la aplicación de polvo de fibra de vidrio reciclado sobre subrasante arcillosa de baja plasticidad aplicada al tramo I de la carretera Rodríguez de Mendoza, Amazonas - Perú / Proposal to improve the mechanical behavior of Flexible Pavements through the application of recycled glass powder on low plasticity clayey subgrade applied to section applied to section I of the Rodriguez de Mendoza Highway

Carhuapoma Najarro, Cynthia Sthefani Alexandra, Tito Sánchez, Jaime Belisario 23 June 2021 (has links)
En la actualidad, la funcionalidad de pavimentos flexibles se ve afectada por la deficiencia de información detallada de los parámetros de Diseño de Pavimentos. Las fallas internas, desencadenan problemas de desplazamientos y deformaciones, los cuales afectan directamente en la funcionalidad de la estructura del pavimento. En el Perú, el desarrollo del uso de materiales de construcción ha originado que se incrementen las cantidades de residuos de vidrio y se produzca un impacto ambiental negativo. Sin embargo, estos residuos, poseen un potencial para ser usados, incorporándose como agentes estabilizantes de suelos en subrasante de pavimentos, por las útiles propiedades mecánicas de resistencia a la compresión y corte que poseen. Esto permite, reducir el impacto medioambiental y contribuir a la ejecución de pavimentos eco-sostenibles. En ese contexto, la presente investigación, está orientada en desarrollar una estabilización de suelo, un diseño de pavimentos bajo la metodología AASHTO, y un posterior análisis del comportamiento mecánico del diseño de pavimentos realizado. Por un lado, la estabilización de suelo de subrasante arcillosa se realiza mediante la aplicación de polvo de residuos de vidrio. Por otro lado, se hace uso de la metodología AASHTO 1993, con el fin de diseñar el paquete estructural y obtener valores de espesores de capa en escenarios de suelo estabilizado con piedra Over propuesto por JNR y otro en el que el suelo se encuentre estabilizado con polvo de fibra de vidrio reciclado, propuesto por la presente investigación. Posteriormente, se realizó un análisis comparativo de espesores y la influencia directa del valor de CBR en muestras no estabilizadas y estabilizadas, para la determinación del número estructural en el Diseño de pavimentos. Finalmente, se realizó un modelado del comportamiento mecánico de cada capa de la estructura del pavimento, mediante el uso del software computacional 3D Move, con el fin de obtener valores de esfuerzos normales, esfuerzos cortantes y desplazamientos en cada capa del pavimento para suelos no estabilizados y estabilizados. / Currently, the functionality of flexible pavements is affected by the deficiency of detailed information in the Pavement Design parameters. Internal failures trigger displacement and deformation problems, which directly affect the functionality of the pavement structure. In Peru, the development of the use of construction materials has led to an increase in the amounts of glass waste and a negative environmental impact. However, these residues have a potential to be used, being incorporated as soil stabilizing agents in subgrade of pavements, due to the useful mechanical properties they possess. This allows reducing the environmental impact and contributing to the implementation of eco-sustainable pavements. In this context, the present research is aimed at developing soil stabilization, a pavement design under the AASHTO methodology and a subsequent analysis of the mechanical behavior of the pavement design carried out. On the one hand, clay subgrade soil stabilization is carried out by applying glass waste powder. On the other hand, the Empirical AASHTO 1993 methodology is used, in order to design the structural package and obtain layer thickness values ​​in scenarios of stabilized soil with the proposed material and another in which the soil is stabilized with other type of material. Subsequently, a comparative analysis of thicknesses and the direct influence of the CBR value in non-stabilized and stabilized samples will be carried out in the pavement design carried out to determine the structural number. Finally, a mechanical behavior modeling is carried out, applying the use of the Windepav computer software to obtain deformation and deflection values ​​in each layer of the pavement for unstabilized and stabilized soils / Tesis
72

Asfaltová souvrství s využitím sklovláknitých kompozitních materiálů / Asphalt Layers using Fibreglass Composite Materials

Sadil, Dominik Unknown Date (has links)
The diploma thesis deals with using of reinforcing composite materials in asphalt layers. These geosynthetic materials are in road construction used especially to reduce spreading cracks and extend the service life of the construction. As par of this work, test specimens of different types of asphalt layers were produced. These samples were subjected to laboratory testing, where the results of different reinforced asphalt slabs were compared. Within the diploma thesis primarily deals with the testing of the shear bond strength between asphalt layers in order to determine what are the other influencing factors of the test. Another part of the thesis is the 4-point bending test, during which a special technology in the form of a DIC camera was used to monitor the behavior of the asphalt layer over time.
73

Análisis estático y frecuencial en el chasis de un camión de 8T utilizando PRFV para reducir el consumo de combustible

Cosmopolis Pol, Grecia January 2023 (has links)
Es muy probable que hoy en día cualquier objeto que esté a nuestro alrededor haya estado en algún momento de su vida en el interior de un camión de carga, ya que estos son indispensables para el transporte de cualquier tipo de elemento. Desde alimentos, prendas de vestir, muebles, materiales de construcción, hasta maquinaria pesada es transportada por estos vehículos pesados. Por este motivo son considerados parte esencial de la economía mundial, pero al ser sometidos a grandes cargas, estos producen una gran contaminación ambiental, debido al combustible que utilizan. La presente investigación tuvo como objetivo disminuir el consumo de combustible del camión mediante la implementación del material compuesto PRFV (Plástico Reforzado con Fibra de Vidrio) como material principal en el chasis en vez de los aceros comúnmente utilizados en su manufactura. La metodología utilizada inició con el dimensionamiento del chasis y se evaluó las propiedades mecánicas del PRFV, para después proceder a la simulación estáticofrecuencial del chasis; los resultados de la simulación fueron comparados con respecto al acero AISI 4135 para finalmente proceder con el cálculo del consumo de combustible del camión con el nuevo material. Con el cambio de material se logró disminuir el peso del camión en 536 Kg, generando así un ahorro de 438.4 L en el uso de combustible, lo cual da un ahorro económico de S/1995.31. / Its most likely nowadays that any object around us has been at some moment in its life inside a cargo truck, since these are indispensable for the transportation of any type of element. From food, clothing, furniture, construction materials, to heavy machinery is transported by these heavy vehicles. For this reason, they are considered an essential part of the world economy, but when subjected to heavy loads, they produce a great amount of environmental pollution, due to the fuel they use. The objective of this research is to reduce the fuel consumption of the truck by implementing GFRP (Glass Fiber Reinforced Plastic) as the main material in the chassisinstead of the Steel commo nly used in its manufacture. The methodology used started with the sizing of the chassis and the mechanical properties of the GFRP were evaluated and then proceeded to the static-frequency simulation of the chassis, the results of the simulations were compared with the Steel alloy AISI 4135, to finally proceed to calculate the fuel consumption of the truck with the new material. By changing the material, the weight of the truck was reduced by 536Kg, which generate a saving of 438.4 L in fuel consumption, resulting in a economic saving of S/.1995,31.
74

Environmental Assessment of Kayak using MFA & LCA : A case study at Melker of Sweden / Miljöbedömning av Kajak med hjälp av MFA & LCA : En fallstudie genomförd i samarbete med Melker of Sweden

Srivastav, Abhishek, Xenos, Spyridon January 2020 (has links)
Kayaking is a watersport activity that involves paddling performed within leisure purposes. Although kayaking provides pleasure to the practitioners, there are some adverse environmental issues concerning the site used to perform kayaking due to the equipment. This paper identifies and analyzes the lifecycle stages in which negative environmental impacts are generated. Melker of Sweden is an outdoor company specialized in delivering high-quality kayaks. This study aims to present an overview of the current environmental performance of Melker of Sweden’s kayaks. For this purpose, two environmental assessment tools are applied: material flow analysis and life cycle assessment. The Material Flow Analysis (MFA) results show that the transport of material to the manufacturing unit generates a considerable amount of emissions. Additionally, hull manufacturing and assembling accessories were found to be the least resource-efficient operation among all. The Life Cycle Assessment (LCA) results identify the transport of material and the manufacturing phase as the primary sources responsible for environmental impacts. On the one hand, the use of epoxy resin and gel coat is the root cause of high contribution of the manufacturing phase. On the other hand, the use of flax fiber found to be the least contributing material to adverse environmental impacts. This report also presents a list of recommendations regarding the import of material, the efficacy of the manufacturing operations, the type of raw material, and waste treatment alternatives. / Fysisk aktivitet kan innefatta olika fritidsaktiviteter, däribland friluftsliv. Kajakpaddling är en sådan friluftslivaktivitet, alltefter utövares syfte. I denna rapport är kajakpaddling en fritidsaktivitet där där utövarens naturupplevelse främjas. Oaktat fördelarna vid utövandet av denna aktivitet kan ej förbises faktum att det också kan medföras vissa negativa konsekvenser. Denna masteruppsats har som mål att identifiera och analysera den miljöpåverkan och dennes efterspel som orsakats av en kajaks tillverkning. Melker of Sweden är ett utomhusföretag specialiserat på att leverera kajaker av hög kvalitet. I linje med företagets vision syftar denna studie till att undersöka den nuvarande miljöprestandan samt kvantifiera den potentiella miljöpåverkan från en kajaks livscykel. För detta ändamål tillämpas det två miljöbedömningsverktyg, nämligen en materialflödesanalys och livscykelanalys. Materialflödesanalysen visar att mängden av utsläpp som genereras från transporten av material till tillverkningsenheten är enorm. Utöver detta var den hulltillverkning samt den montering av tillbehörsverksamheter bland de minst resurseffektiva tillverkningssteg. Livscykelanalysen identifierar import av material och tillverkningsfas som de viktigaste källorna till miljöpåverkan. Å ena sidan är användningen av epoxiharts och gelbeläggning i tillverkningen grundorsaken till huvudbidraget. Å andra sidan är användningen av linfiber det minst bidragande material då det gäller negativa miljöeffekter. I denna studie ges rekommendationer rörande import av vissa material och materialval, sätt att öka tillverkningseffektiviteten, typ av råmaterial samt avfallsbehandlingsalternativ.
75

Técnicas de refuerzo tradicionales y modernas aplicadas a la conservación y restauración de bienes culturales

Peris Gisbert, Silvana 17 January 2022 (has links)
[ES] La investigación realizada forma parte del estudio, mucho más amplio, para la restauración de la Iglesia de los Santos Juanes de Valencia, que tiene por objeto establecer una metodología de reconstrucción para las pinturas murales de la grandioso bóveda que Antonio Palomino pintó entre 1699 y 1701, la cual fue incendiada durante la Guerra Civil. Al realizar un primer análisis sobre diferentes anclajes en la restauración, se han encontrado dos clases de técnicas de anclaje, las denominadas tradicionales y las modernas. Tras este análisis, se ha realizado un trabajo de investigación comparativa entre diversos espacios arquitectónicos, tanto de España como de Europa, concretamente de Italia, que ya habían sido restaurados, para poder identificar los materiales utilizados en sus realizaciones. Con todo este trabajo acabado, se contactó con el Profesor Vicente Amigó Borrás, investigador del laboratorio del Instituto de Tecnología de los Materiales, para estudiar otros materiales más novedosos que pudieran ayudar en nuestra labor. Para realizar el estudio, junto a él y muchos de sus compañeros, se desarrollaron un conjunto de probetas con el fin de elaborar diferentes tipos de laminados compuestos de fibra y matriz, los cuales han soportado los diferentes procesos y análisis para obtener los mejores resultados posibles. Estos análisis han permitido conocer muy a fondo cada material y la diversidad de sus propiedades, estableciendo estudios comparativos que han ayudado a escoger cuál de ellos resultará más apropiado para el trabajo de restauración y dar algunas conclusiones finales sobre ello en el proceso de intervención global en los Santos Juanes. Se puede afirmar que esta Tesis Doctoral demuestra la posible aplicación de materiales compuestos en diferentes bienes culturales, y en especial en la bóveda de la Iglesia de los Santos Juanes de Valencia. / [CA] La investigació realitzada forma part del estudi, molt més ample, realitzat per a la restauració de l'Església dels Sants Joans de València, que té per objectiu establir una metodologia de reconstrucció per a les pintures murals de la grandiosa volta que Antonio Palomino va pintar entre 1699 i 1701, la qual va ser incendiada durant la Guerra Civil. En realitzar una primera anàlisi sobre ancoratges en la restauració, ens hem trobat davant de dues classes de tècniques d'ancoratge, les denominades tradicionals i les modernes. Després d'aquesta anàlisi, s'ha realitzat un treball de recerca comparativa entre diversos espais arquitectònics, tant d'Espanya com d'Europa, concretament d'Italia, que ja havien sigut restaurats, per a poder identificar els materials utilitzats en les seues realitzacions. Amb tot aquest treball finalitzat, es va contactar amb el Profesor Vicente Amigó Borrás, investigador del laboratori de l'Institut de Tecnologia dels Materials, per a estudiar altres materials més nous que pogueren ajudar en la nostra labor. Per realitzar l'estudi, al costat d'ell i molts dels seus companys, es van desenvolupar un conjunt de provetes amb la finalitat d'elaborar diferents tipus de laminatges compostos de fibra i matriu, els quals han suportat els diferents processos i anàlisis per a obtenir els millors resultats possibles. Aquestes anàlisis han permés conéixer molt a fons cada material i la diversitat de les seues propietats, establint estudis comparatius que han ajudat a triar quin d'ells resultarà més apropiat per al treball de restauració i donar les conclusions finals sobre el procés d'intervenció. Es pot afirmar que aquesta Tesi Doctoral demostra la possible aplicació de materials compostos en diferents béns culturals, i especialment en la volta de l'Església dels Sants Joans de València. / [EN] The object of our study was to establish the methodology for the reconstruction of the painted murals of the great vault in the Santos Juanes church of Valencia which were painted by Antonio Palomino between 1699 and 1701 and which were burned during the Civil War. In conducting an initial study of the foundations we find two different types of technique, the traditional and modern. After this analysis a comparative investigation was carried out between the various architectural sites which have been restored, both in Spain and Europe, enabling a study of the materials which have been utilized. Having completed this work we were put in contact with Professor Vicente Amigo, Laboratory investigator of the Institute of Engineering of Technological Materials, to study alternative more modern materials, which could be put to use in our work. Finishing the study alongside him and his many colleagues, a series of tests have been carried out to develop different types of fibre and matrix laminate combinations, which have undergone a variety of analytical processes to obtain the best possible results. These analyses have enabled a closer and deeper understanding of each material and their individual properties, providing a comparative study to assist the selection of the most appropriate for our needs and giving final results closest to the procedure. It can be confirmed that this Doctorate Thesis demonstrates the possible usage of compounded materials in different cultural properties, especially in the vault of the Santos Juanes church of Valencia. / Peris Gisbert, S. (2021). Técnicas de refuerzo tradicionales y modernas aplicadas a la conservación y restauración de bienes culturales [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/180014
76

Thermal Cycling Fatigue Investigation of Surface Mounted Components with Eutectic Tin-Lead Solder Joints

Bonner, J. K. "Kirk", de Silveira, Carl 10 1900 (has links)
International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / Eutectic (63% tin-37% lead) or near-eutectic (40% tin-60% lead) tin-lead solder is widely used for creating electrical interconnections between the printed wiring board (PWB) and the components mounted on the board surface. For components mounted directly on the PWB mounting pads, that is, surface mounted components, the tin-lead solder also constitutes the mechanical interconnection. Eutectic solder has a melting point of 183°C (361°F). It is important to realize that its homologous temperature, defined as the temperature in degrees Kelvin over its melting point temperature (T(m)), also in degrees Kelvin, is defined as T/T(m). At room temperature (25°C = 298K), eutectic solder's homologous temperature is 0.65. It is widely acknowledged that materials having a homologous temperature ≥ 0.5 are readily subject to creep, and the solder joints of printed wiring assemblies are routinely exposed to temperatures above room temperature. Hence, solder joints tend to be subject to both thermal fatigue and creep. This can lead to premature failures during service conditions. The geometry, that is, the lead configuration, of the joints can also affect failure. Various geometries are better suited to withstand failure than others. The purpose of this paper is to explore solder joint failures of dual in-line (DIP) integrated circuit components, leadless ceramic chip carriers (LCCCs), and gull wing and J-lead surface mount components mounted on PWBs.
77

Katedrála / Cathedral

Kliment, Jakub January 2016 (has links)
The statue called The Cathedral is a natural extension of my work, which deals with organic morphology of the landscape, both the details and grand compositions, which in the countryside vyskytují.Stejně like most authors is my creative work reflection of my surroundings, both personal so near in geographical terms. Integrating these aspects arise impetus to creation. In the case of sculptures entitled The Cathedral is a rendering of the very strong impression of verticality, which dominates the landscape. Regularly clashing with seemingly ordinary natural objects such as trees, soil, hills or reliefs and reliefs such as landscapes, I got into an imaginary dialogue, which I decided to answer this statue and also portray already mentioned impressed. This feeling is for me identically comparable to a situation where the viewer stands in front of the high Gothic building and trying to accommodate the shape of a giant who stands before him. Its peak, it seems so distant, as if no end, and the broad base is a kind of sign of confidence in the form of stability. Parallels between these seemingly different topics I could not miss, so I decided to call the statue Cathedral. In this work, as in previous ones, I try to get into organic sculptures character with the help of the deformation of materials, or basically draping. Compacting elastic materials to try to create the statues of the tension that fascinates me in nature and creates the impression of growth, which is in the countryside of one of the strongest motives. Shape diversity, which is in the landscape, in my inexhaustible source of inspiration and has become lately a space that fills me. When I release the perception of various aspects of your imagination and build imaginary composition, which would then be identical expression perceived impressions.

Page generated in 0.0473 seconds