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L’objectiu d’aquest projecte és l’anàlisi del procés de fabricació d’un tipus de resistències domèstiques per tal de reduir la quantitat de peces defectuoses obtingudes al llarg del conjunt de fases que intervenen. La iniciativa d’aprofundir en aquest tema comença a l’hora d’analitzar les ordres de fabricació que s’entreguen diàriament, on es detecta que hi ha una gran quantitat de peces que, un cop sortides de la última fase de fabricació de la màquina, no compleixen al 100% els criteris de qualitat i no són aptes per servir al client final. Aquestes peces, o bé es poden recuperar a través d’un condicionament mecànic, afegint processos addicionals que fan encarir els costos de fabricació, o bé directament es classifiquen com a defectuoses. A partir de les dades obtingudes al llarg dels últims dos anys, l’anàlisi minuciós del procés fase a fase i mitjançant l’aplicació d’un conjunt d’eines de Lean Manufacturing, s’han trobat les principals causes que provoquen aquesta situació i s’han plantejat propostes de millora a implementar, amb la finalitat d’aconseguir millorar la disponibilitat del producte final, a través de l’augment de la quantitat de peces bones obtingudes a la primera sense haver de forçar a la màquina a fabricar més peces de les inicialment planificades, mitjançant la modificació de paràmetres. Per tal de revertir la situació actual i obtenir una millora dels indicadors de qualitat, les propostes realitzades es focalitzen en tres dels possibles defectes que es poden presentar a l’acabat del producte final: per una banda, en forma d’optimització de les condicions de les eines i màquines i del seu manteniment, i per una altra banda, implementant directament una nova fase a la màquina que executi un condicionament que actualment es realitza manualment, de manera addicional. S’ha realitzat una valoració econòmica en la qual es pressuposta el cost de les millores, la viabilitat del projecte (impacte econòmic) i rendibilitat., El objetivo de este proyecto es el análisis del proceso de fabricación de un tipo de resistencias domésticas con el fin de reducir la cantidad de piezas defectuosas obtenidas a lo largo del conjunto de fases que intervienen. La iniciativa de profundizar en este tema empieza a la hora de analizar las órdenes de fabricación que se entregan diariamente, donde se detecta que hay una gran cantidad de piezas que, una vez salidas de la última fase de fabricación de la máquina, no cumplen al 100% los criterios de calidad y no son aptos para servir al cliente final. Estas piezas, o bien se pueden recuperar a través de un acondicionamiento mecánico, añadiendo procesos adicionales que hacen encarecer los costes de fabricación, o bien directamente se clasifican como defectuosas. A partir de los datos obtenidos a lo largo de los últimos dos años, el análisis minucioso del proceso fase a fase y mediante la aplicación de un conjunto de herramientas de Lean Manufacturing, se han encontrado las principales causas que provocan esta situación y se han planteado propuestas de mejora a implementar, con el fin de conseguir mejorar la disponibilidad del producto final, a través del aumento de la cantidad de piezas buenas obtenidas a la primera sin tener que forzar a la máquina a fabricar más p iezas de las inicialmente planificadas, mediante la modificación de parámetros. Con el fin de revertir la situación actual y obtener una mejora de los indicadores de calidad, las propuestas realizadas se focalizan en tres de los posibles defectos que pueden presentar el acabado del producto final: por un lado, en forma de optimización de las condiciones de las herramientas y máquinas y de su mantenimiento y, por otro lado, implementando directamente una nueva fase a la máquina que ejecute un acondicionamiento que actualmente se realiza manualmente, de manera adicional. Se ha realizado una valoración económica en la cual se presupuesta el coste de las mejoras, la viabilidad del proyecto i rendibilid., The aim of this project is the analysis of the manufacturing process of a type of domestic resistances in order to reduce the number of defective parts obtained throughout the set of phases involved. The initiative to delve deeper into this subject begins when analyzing the manufacturing orders that are delivered daily, where it is detected that there are a large number of parts that, once they come out of the last phase of machine manufacturing, do not meet the 100% quality criteria and are not suitable to serve the end customer. These parts can either be recovered through mechanical conditioning, adding additional processes that make manufacturing costs more expensive, or they are directly classified as defective. Based on the data obtained over the last two years, the detailed analysis of the process phase by phase and through the application of a set of Lean Manufacturing tools, the main causes of this situation have been found and the main causes of this situation have been raised. improvement proposals to be implemented, in order to improve the availability of the final product, by increasing the number of good parts obtained the first time without having to force the machine to manufacture more parts of those initially planned, by modifying parameters. In order to reverse the current situation and obtain an improvement in quality indicators, the proposals made are focused on three of the possible defects that the finish of the final product may present: on the one hand, in the form of optimization of the conditions of the tools and machines and their maintenance and, on the other hand, directly implementing a new phase to the machine that performs conditioning that is currently done manually, additionally. An economic valuation has been carried out in which the cost of the improvements is budgeted, the viability of the project in the form of economic impact and the time necessary for this investment, to be profitable.

La producció mitjançant els sistemes d’addició de materials metàl·lics actualment permet l’obtenció de peces amb característiques similars a les produïdes mitjançant altres mètodes més tradicionals. En l’actualitat aquestes tecnologies tot i la seva complexitat i costos de producció presenten avantatges cada cop més valorats. Aquests són la reducció de temps en la producció de prototips,lots petits o amb la reducció de temps es poden fabricar més iteracions de la peça en qüestió. S’han patentat diferents tecnologies de fabricació additiva metàl·lica, amb diferents sistemes de producció, però el concepte és molt similar en la majoria, la fundició de material, ja sigui en format pols, fil o altres i l'edició d’aquest en capes que creixen en sentit vertical. Aquest projecte consisteix a escollir un d’aquests sistemes i materials de fabricació metàl·lica, aquesta selecció es realitza en funció de la viabilitat i adaptabilitat a màquines d’impressió tridimensionals domèstiques. Un cop escollida una de les tecnologies i material, es realitzarà un estudi dels passos per adaptar-ne l’extrusor i controlar el correcte flux de material de forma teòrica en funció a diversos paràmetres per saber quina viabilitat pot tenir. A continuació es procedirà a realitzar l’estudi de si és viable adaptar la tecnologia seleccionada, a màquines de fabricació additiva domèstiques., La producción mediante los sistemas de adición de materiales metálicos actualmente permite la obtención de piezas con características similares a las producidas mediante otros métodos más tradicionales. En la actualidad estas tecnologías todo y su complejidad y costes de producción presentan ventajas cada vez más valoradas. Estos son la reducción de tiempo en la producción de prototipos,lotes pequeños o con la reducción de tiempo se pueden fabricar más iteraciones de la pieza en cuestión. Se han patentado diferentes tecnologías de fabricación aditiva metálica, con diferentes sistemas de producción, pero el concepto es muy similar en la mayoría, la fundición de material, ya sea en formado pulso, hilo u otros y la edición de este en capas que crecen en sentido vertical. Este proyecto consiste en escoger uno de estos sistemas y materiales de fabricación metálica, esta selección se realiza en función de la viabilidad y adaptabilidad a máquinas de impresión tridimensionales domésticas. Una vez escogida una de las tecnologías y material, se realizará un estudio de los pasos para adaptar el extrusor y controlar el correcto flujo de material de forma teórica en función a varios parámetros para indagar qué viabilidad puede tener. A continuación se procederá a realizar el estudio de si es viable adaptar la tecnología seleccionada, a máquinas de fabricación aditiva domésticas., Production using metal material addition systems currently allows parts with similar characteristics to those obtained by other more traditional methods. Today, these technologies, despite their complexity and production costs, have increasingly valued advantages. These are the reduction of time in the production of prototypes, small batches, the reduction of time also ensures that more iterations of the piece in question can be manufactured. Different technologies of metal additive manufacturing have been patented, with different production systems, but the concept is very similar in most, the casting of material, either in powder, wire or other format and the addition of this in layers that grow vertically. This project consists of choosing one of these systems and materials of metal fabrication, this selection is made based on the viability and adaptability to domestic three-dimensional printing machines. Once one of the technologies and materials has been chosen, a study of the steps will be carried out to adapt the extruder and control the correct flow of material theoretically according to various parameters to find out how viable it may be. The study of whether it is viable to adapt the selected technology to domestic additive manufacturing machines will then be carried out.

We describe here partial outcomes of a study in which we seek to unveil the historical-sociocultural influences that permeated the technical-scientific work of James Prescott Joule and show his contributions to the physics teachers training. We tried to answer the following question: What were the theoretical, social and cultural elements that influenced Joule's work? In this sense, we present a brief history of the development of science in the period of the Industrial Revolution, as well as the industrial development of Greater Manchester, in which Salford is part of its metropolitan region, city where Joule was born and grew up. Next we show the importance and the cultural influence of the social and academic environment of Joule and of theoretical elements that influenced, mainly, the works on Joule effect and the mechanical equivalent of the heat. From the study carried out, we organized some notes aimed at contributing to the teachers’ training., Descrevemos aqui resultados parciais de um estudo no qual procuramos desvelar as influências histórico-socioculturais que permearam o trabalho técnico-científico de James Prescott Joule e mostrar suas contribuições para a formação de professores de Física. Procuraremos responder a seguinte questão: Quais foram os elementos teóricos, sociais e culturais que influenciaram o trabalho de Joule? Nesse sentido, apresentamos um breve histórico do desenvolvimento da ciência no período da revolução industrial, bem como o desenvolvimento industrial da grande Manchester, em que Salford faz parte de sua região metropolitana cidade onde Joule nasceu e cresceu. Em seguida mostramos a importância e a influência cultural do entorno social e acadêmico de Joule e de elementos teóricos que influenciaram, sobretudo, os trabalhos sobre efeito Joule e o Equivalente Mecânico do Calor. A partir do estudo realizado, organizamos alguns apontamentos visando contribuir para a formação de professores.

We describe here partial outcomes of a study in which we seek to unveil the historical-sociocultural influences that permeated the technical-scientific work of James Prescott Joule and show his contributions to the physics teachers training. We tried to answer the following question: What were the theoretical, social and cultural elements that influenced Joule's work? In this sense, we present a brief history of the development of science in the period of the Industrial Revolution, as well as the industrial development of Greater Manchester, in which Salford is part of its metropolitan region, city where Joule was born and grew up. Next we show the importance and the cultural influence of the social and academic environment of Joule and of theoretical elements that influenced, mainly, the works on Joule effect and the mechanical equivalent of the heat. From the study carried out, we organized some notes aimed at contributing to the teachers’ training., Descrevemos aqui resultados parciais de um estudo no qual procuramos desvelar as influências histórico-socioculturais que permearam o trabalho técnico-científico de James Prescott Joule e mostrar suas contribuições para a formação de professores de Física. Procuraremos responder a seguinte questão: Quais foram os elementos teóricos, sociais e culturais que influenciaram o trabalho de Joule? Nesse sentido, apresentamos um breve histórico do desenvolvimento da ciência no período da revolução industrial, bem como o desenvolvimento industrial da grande Manchester, em que Salford faz parte de sua região metropolitana cidade onde Joule nasceu e cresceu. Em seguida mostramos a importância e a influência cultural do entorno social e acadêmico de Joule e de elementos teóricos que influenciaram, sobretudo, os trabalhos sobre efeito Joule e o Equivalente Mecânico do Calor. A partir do estudo realizado, organizamos alguns apontamentos visando contribuir para a formação de professores.

Es descriu una experiència per a calcular l'equivalent elèctric de la calor.

Es descriu una experiència per a calcular l'equivalent elèctric de la calor.

Es descriu una experiència per a calcular l'equivalent elèctric de la calor.

The events of September 11, 2001, seemed to many to presage the end of the skyscraper as an urban form. Some 15 years later, the skyscraper is more prevalent than ever before, owing to its unique advantages over other building forms in an urban, environmental, and sociological context. Skyscrapers are rising ever higher, pushing the limits of architecture and engineering. In 2001 there were 23 buildings over 1,000 feet in height. As of this writing there are 173 buildings over 1,000 feet completed or under construction, with 300 more in various phases of proposal. Despite their enormous initial cost in both capital and energy, the skyscraper maximizes the use of constricted urban space and provides enormous opportunities for technological and sociological innovation which, despite more that 100 years of skyscraper construction, are only just beginning to be realized. This thesis will explore a number of as-yet unrealized possibilities for skyscraper development to prognosticate and articulate future typologies designed to address increasing problems of energy efficiency, population density and disaster preparedness. As the human population grows, and more people move to the cities, larger and larger buildings will be necessary to house them at densities sufficient to ensure energy efficiency and minimize sprawl. The skyscraper is uniquely suited to meet these demands.

This paper presents a numerical study on the influence of pulsed electric signals applied to the overcooling of thermoelectric devices. To this end, an experimental setup taken from the literature and a commercial cell are simulated using a complete, specially developed research finite element code. The electro-thermal coupling is extended to include the elastic field, demonstrating that the increment of cooling can produce mechanical failure. Numerical results are developed and the variation of overcooling versus pulse gain and versus duration is validated towards a new analytical expression and the experimental data. The issue of optimal intensity at steady-state is also newly developed. Thermal and mechanical trends are presented using constant and variable (with temperature) material properties for a single thermoelement. While some of the first trends are similar to those of published works, others are different or directly new, all closer to those of the experiments. The mechanical results have not been thoroughly studied until recently. The three-dimensional finite element mesh includes non-thermoelectric materials that are fundamental for the current study. Distribution of stresses during steady and transient states are shown inside the thermoelement, for five components and for the combined Tresca stress. Concentrations at corners of the lower side appear close to the cold face. Due to these concentrations, 27-node isoparametric, quadratic brick elements are used. It is shown that the mechanical field is an important factor in the design of pulsed thermoelectrics, since for practical applications the stress levels are close or slightly above the admissible limits.

The events of September 11, 2001, seemed to many to presage the end of the skyscraper as an urban form. Some 15 years later, the skyscraper is more prevalent than ever before, owing to its unique advantages over other building forms in an urban, environmental, and sociological context. Skyscrapers are rising ever higher, pushing the limits of architecture and engineering. In 2001 there were 23 buildings over 1,000 feet in height. As of this writing there are 173 buildings over 1,000 feet completed or under construction, with 300 more in various phases of proposal. Despite their enormous initial cost in both capital and energy, the skyscraper maximizes the use of constricted urban space and provides enormous opportunities for technological and sociological innovation which, despite more that 100 years of skyscraper construction, are only just beginning to be realized. This thesis will explore a number of as-yet unrealized possibilities for skyscraper development to prognosticate and articulate future typologies designed to address increasing problems of energy efficiency, population density and disaster preparedness. As the human population grows, and more people move to the cities, larger and larger buildings will be necessary to house them at densities sufficient to ensure energy efficiency and minimize sprawl. The skyscraper is uniquely suited to meet these demands.

This paper presents a numerical study on the influence of pulsed electric signals applied to the overcooling of thermoelectric devices. To this end, an experimental setup taken from the literature and a commercial cell are simulated using a complete, specially developed research finite element code. The electro-thermal coupling is extended to include the elastic field, demonstrating that the increment of cooling can produce mechanical failure. Numerical results are developed and the variation of overcooling versus pulse gain and versus duration is validated towards a new analytical expression and the experimental data. The issue of optimal intensity at steady-state is also newly developed. Thermal and mechanical trends are presented using constant and variable (with temperature) material properties for a single thermoelement. While some of the first trends are similar to those of published works, others are different or directly new, all closer to those of the experiments. The mechanical results have not been thoroughly studied until recently. The three-dimensional finite element mesh includes non-thermoelectric materials that are fundamental for the current study. Distribution of stresses during steady and transient states are shown inside the thermoelement, for five components and for the combined Tresca stress. Concentrations at corners of the lower side appear close to the cold face. Due to these concentrations, 27-node isoparametric, quadratic brick elements are used. It is shown that the mechanical field is an important factor in the design of pulsed thermoelectrics, since for practical applications the stress levels are close or slightly above the admissible limits.

Highly oriented nylon and polyethylene fibres shrink in length when heated and expand in diameter. By twisting and then coiling monofilaments of these materials to form helical springs, the anisotropic thermal expansion has recently been shown to enable tensile actuation of up to 49% upon heating. Joule heating, by passing a current through a conductive coating on the surface of the filament, is a convenient method of controlling actuation. In previously reported work this has been done using highly flexible carbon nanotube sheets or commercially available silver coated fibres. In this work silver paint is used as the Joule heating element at the surface of the muscle. Up to 29% linear actuation is observed with energy and power densities reaching 840 kJ m-3 (528 J kg-1) and 1.1 kW kg-1 (operating at 0.1 Hz, 4% strain, 1.4 kg load). This simple coating method is readily accessible and can be applied to any polymer filament. Effective use of this technique relies on uniform coating to avoid temperature gradients.

Highly oriented nylon and polyethylene fibres shrink in length when heated and expand in diameter. By twisting and then coiling monofilaments of these materials to form helical springs, the anisotropic thermal expansion has recently been shown to enable tensile actuation of up to 49% upon heating. Joule heating, by passing a current through a conductive coating on the surface of the filament, is a convenient method of controlling actuation. In previously reported work this has been done using highly flexible carbon nanotube sheets or commercially available silver coated fibres. In this work silver paint is used as the Joule heating element at the surface of the muscle. Up to 29% linear actuation is observed with energy and power densities reaching 840 kJ m-3 (528 J kg-1) and 1.1 kW kg-1 (operating at 0.1 Hz, 4% strain, 1.4 kg load). This simple coating method is readily accessible and can be applied to any polymer filament. Effective use of this technique relies on uniform coating to avoid temperature gradients.

Highly oriented nylon and polyethylene fibres shrink in length when heated and expand in diameter. By twisting and then coiling monofilaments of these materials to form helical springs, the anisotropic thermal expansion has recently been shown to enable tensile actuation of up to 49% upon heating. Joule heating, by passing a current through a conductive coating on the surface of the filament, is a convenient method of controlling actuation. In previously reported work this has been done using highly flexible carbon nanotube sheets or commercially available silver coated fibres. In this work silver paint is used as the Joule heating element at the surface of the muscle. Up to 29% linear actuation is observed with energy and power densities reaching 840 kJ m-3 (528 J kg-1) and 1.1 kW kg-1 (operating at 0.1 Hz, 4% strain, 1.4 kg load). This simple coating method is readily accessible and can be applied to any polymer filament. Effective use of this technique relies on uniform coating to avoid temperature gradients.

Highly oriented nylon and polyethylene fibres shrink in length when heated and expand in diameter. By twisting and then coiling monofilaments of these materials to form helical springs, the anisotropic thermal expansion has recently been shown to enable tensile actuation of up to 49% upon heating. Joule heating, by passing a current through a conductive coating on the surface of the filament, is a convenient method of controlling actuation. In previously reported work this has been done using highly flexible carbon nanotube sheets or commercially available silver coated fibres. In this work silver paint is used as the Joule heating element at the surface of the muscle. Up to 29% linear actuation is observed with energy and power densities reaching 840 kJ m-3 (528 J kg-1) and 1.1 kW kg-1 (operating at 0.1 Hz, 4% strain, 1.4 kg load). This simple coating method is readily accessible and can be applied to any polymer filament. Effective use of this technique relies on uniform coating to avoid temperature gradients.

In this work, a finite element simulation of a commercial thermoelectric cell, working as a cooling heat pump, is presented. The specially developed finite element is three-dimensional, non-linear in its formulation (using quadratic temperature-dependence on material properties) and fully coupled, including the Seebeck, Peltier, Thomson and Joule effects. Another special interface finite element is developed to prescribe the electric intensity, taking advantage of repetitions and symmetries. A thorough study of the distributions of voltage, temperature and the corresponding fluxes is presented, and the performance of the cell is compared with that of the manufacturer and with simplified analytical formulations, showing a good agreement. Combining the finite element model with the Monte Carlo technique, a sensitivity analysis is presented to take into account the performance dependence on the material properties, geometrical parameters and prescribed values. This analysis, which can be considered a first step to optimize these devices, concludes that the temperature-dependence of the material properties of electric conductivity and Seebeck coefficient is very relevant on cell performance.

In this work, a finite element simulation of a commercial thermoelectric cell, working as a cooling heat pump, is presented. The specially developed finite element is three-dimensional, non-linear in its formulation (using quadratic temperature-dependence on material properties) and fully coupled, including the Seebeck, Peltier, Thomson and Joule effects. Another special interface finite element is developed to prescribe the electric intensity, taking advantage of repetitions and symmetries. A thorough study of the distributions of voltage, temperature and the corresponding fluxes is presented, and the performance of the cell is compared with that of the manufacturer and with simplified analytical formulations, showing a good agreement. Combining the finite element model with the Monte Carlo technique, a sensitivity analysis is presented to take into account the performance dependence on the material properties, geometrical parameters and prescribed values. This analysis, which can be considered a first step to optimize these devices, concludes that the temperature-dependence of the material properties of electric conductivity and Seebeck coefficient is very relevant on cell performance.

L'objectif général de cette thèse de doctorat est de développer des modèles mathématiques permettant d'évaluer l'énergie requise pour le dégivrage thermique par effet Joule des conducteurs aériens de transport de courant et ainsi prévenir la formation de glace dans des conditions météorologiques et de transmission électrique variées. Les prédictions de ces modèles analytiques ont été validées expérimentalement dans le but d'évaluer la puissance prédictive de ces modèles. Premièrement, un modèle a été établi pour calculer l'intensité de courant minimum nécessaire pour empêcher la formation de glace sur un conducteur de ligne à haute tension. Des coefficients de correction, tenant compte de d'eau de ruissellement sur la surface du conducteur, de même que la dérivation du film d'eau à partir de l'état d'équilibre thermique, ont été introduits pour trois conducteurs spécifiques. Les résultats des modèles s'accordent bien avec les observations effectuées dans des conditions correspondantes simulées dans une soufflerie réfrigérée. Afin de compléter le modèle, il était nécessaire d'évaluer le coefficient moyen de transfert de chaleur pour les conducteurs toronnés. Ce coefficient a été obtenu pour des conducteurs nus de lignes aériennes avec différentes géométries de surface, en utilisant des mesures et des simulations numériques. Deuxièmement, un modèle basé sur le principe des différences finies a été développé pour calculer le courant et l'énergie requis pour le dégivrage des conducteurs partiellement couverts de glace. Deux types de chauffage thermique par effet Joule ont été analysés, le courant alternatif et le courant d'impulsion, et ce, pour un grand nombre de paramètres atmosphériques. On a trouvé que ceux deux techniques de chauffage peuvent être utilisées selon des stratégies différentes dépendamment du temps d'interaction nécessaire au cours du processus d'accumulation de glace. Afin de compléter le modèle, il a fallu évaluer la conductivité thermique radiale éq

An introduction to the forms and changes in energy. This lesson discusses potential and kinetic energy as well as introducing the 1st and 2nd law of thermodynamics. Educational levels: High school, Undergraduate lower division