Dissertations / Theses: 'Billetes'

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Cornejo, Renso. "Los billetes peruanos en el tiempo." Universidad Peruana de Ciencias Aplicadas (UPC), 2015. http://hdl.handle.net/10757/345936.

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Cruzate, Villavicencio Pedro Wualter. "Dispositivo electrónico detector de billetes falsos." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2016. https://hdl.handle.net/20.500.12672/5429.

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Publicación a texto completo no autorizada por el autor.
Propone y describe la existencia de un método basado en el concepto estadístico de correlación de Pearson que compara dos tipos de muestra uno almacenado en memoria flash, que consideramos bueno y verdadero y el otro un valor medido, que se compararan usando la correlación para determinar si el billete medido es casi igual que la muestra del billete patrón previamente almacenado en la eeprom (memoria de almacenamiento no volátil). De lo contrario se considera falso o que no es parte de los billetes patrones almacenados. Los sensores que permiten la captura de datos de los billetes son diodos en la banda de infrarrojos (940 nanómetros). Ocho parejas de emisores receptores que capturan la luz que atraviesa el billete en una escala de 10 bits (de 0 a 1023). Estos datos se almacenan en áreas de memorias separadas tanto para la muestra patrón previamente almacenada como para la muestra medida que se quiere determinar si es verdadera o falsa. El valor de la correlación de estas mediciones está entre los valores -1 y +1. En nuestro caso, para valores mayores a 0.9 se considera que el billete es verdadero y la denominación corresponderá con el valor más alto desde 0.9 o superior. Si el valor es menor que 0.9 el billete es rechazado como falso o que no corresponde con los billetes patrones almacenados que en este caso son billetes de circulación nacional de 10, 20, 50 y 100 soles. Se presenta el desarrollo de un prototipo práctico que funcione y que permita en el futuro un producto comercial cuyo costo sea menor a los 85 dólares para que pueda ser usado por comerciantes y tiendas pequeñas sin la pérdida de calidad y precisión que requieren este tipo de aparatos detectores de billetes falsos.
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Fuentes, F. Carlos. "Embajadores silenciosos: diseño de billetes en Chile 1925 a 2007." Tesis, Universidad de Chile, 2007. http://repositorio.uchile.cl/handle/2250/101104.

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No autorizada por el autor para ser publicada a texto completo
La investigación en torno a la evolución gráfica presente en nuestros billetes permitirá aumentar el área de conocimientos que el Diseñador como profesional debe contemplar. En el mundo entero el diseño de billetes es realizado desde su conceptualización, exclusivamente por Diseñadores Gráficos profesionales. En nuestro país, el diseño de billetes es un tema completamente

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Vera, Muñoz David. "Reconocimiento de elementos de seguridad de billetes utilizando Transfer Learning." Master's thesis, Pontificia Universidad Católica del Perú, 2020. http://hdl.handle.net/20.500.12404/19935.

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La falsificación de moneda es un problema en el país y se evidencia en informes periodísticos de incautaciones de billetes y monedas falsificadas que aparecen cada cierto tiempo a nivel nacional; por lo tanto, la necesidad de un sistema de reconocimiento de billetes y monedas es imperativo dado que a la par del crecimiento tecnológico que apoye esta tarea, también la maquinaria y tecnología utilizada para la falsificación de billetes y monedas es más accesible y costeable. La identificación de billetes y monedas falsificadas ha estado enfocada en gran medida en el procesamiento de imágenes. En el presente artículo se utiliza un modelo basado en aprendizaje por transferencia que viene teniendo buenos resultados en problemas específicos de clasificación de imágenes en la actualidad. Se ha construido un conjunto de datos con imágenes de billetes genuinos y falsificados para el entrenamiento y pruebas del modelo. Los resultados obtenidos son muy alentadores y demandan un entrenamiento más robusto con una mayor cantidad de imágenes. Asimismo con algunas mejoras en la arquitectura se podría adaptar un modelo a una aplicación móvil de manera que pueda apoyar al ciudadano de a pie en la identificación de billetes falsificados en tiempo real.

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Pérez, Rivera Maricarmen. "Necesidad de implementar una pena mínima al uso y portación de un billete falso." Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2016. http://hdl.handle.net/20.500.11799/58698.

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Se teoriza sobre la necesidad e la imposición de una pena por la portación de billetes falsificados. Esto partiendo de la situación actual y soportada por un estudio histórico sobre como en México se trata el delito de falsificación

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Reyes, Castillo Aaron Luis. "Vehículo aéreo no tripulado para la dispensación de dinero en efectivo en billetes (dron ATM)." Bachelor's thesis, Pontificia Universidad Católica del Perú, 2020. http://hdl.handle.net/20.500.12404/18249.

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El desarrollo tecnológico del sector financiero en el Perú está creciendo de manera acelerada. La competencia entre entidades financieras ya no solo se da en el campo de los productos, sino también en el uso que le dan a la tecnología para fortalecer su propuesta de valor y los servicios que ofrecen a los usuarios. Hoy todo gira en torno a la experiencia de usuario y la tendencia principal es la de la auto atención. Es así, que la innovación juega un rol crucial para lograr la diferenciación de la competencia. La tendencia de la digitalización de servicios ha llevado a que cada vez más usuarios se sumen al uso de la banca por internet y las aplicaciones. Los canales electrónicos, como es el caso de los cajeros automáticos, pasaron a verse como una transición hacia la digitalización, cuyo objetivo era incentivar la auto atención de los clientes, pero dentro de la seguridad de un entorno propio del banco. Sin embargo, se descubrió que así se logre una migración de usuarios hacia los canales digitales, estos mismos usuarios seguían utilizando los cajeros automáticos en ciertas ocasiones, debido a que su necesidad de efectivo no desaparecía al 100%. El motivo de esto principalmente es que la sociedad peruana (y latinoamericana en general) aún no está lista para la digitalización completa. La carencia de medios digitales en gran parte de establecimientos de venta recurrentes (mercados, bodegas), el posicionamiento del uso de efectivo para transacciones del día a día (como el transporte público) y la falta de confianza del usuario por utilizar canales digitales como medio de pago en un gran porcentaje de la población aún, hace que la necesidad de abastecimiento de efectivo siga latente. De este modo, la inserción de nuevas tecnologías que brinden facilidades complementarias para lograr mejorar la confianza en el público reacio a utilizar dichos medios y, del mismo modo, que permitan satisfacer sus necesidades esenciales, tales como la disposición de dinero en efectivo, van a lograr no solo fortalecer el puente hacia la digitalización total, sino satisfacer la necesidad real de los usuarios. En el presente trabajo de investigación se desarrolla una propuesta de solución que permitirá distribuir dinero en efectivo por medio de un sistema accionado por drones, los cuales transportarán el contenido en maletines especiales y serán capaces de dispensar el monto solicitado por el usuario.
Trabajo de investigación

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Sánchez, Garat César. "Acuñando la comunidad heroica de la revolución: monedas y billetes de la Unidad Popular, 1969-1973." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/152416.

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Tesis para optar al grado de Magíster en Historia
La presente tesis tiene como objetivo analizar el proceso de construcción de una comunidad heroica en la estética de monedas y billetes de la Unidad Popular, en el contexto de su proyecto y tradición cultural. Focaliza en la conformación de esta coalición política de izquierda en 1969, hasta la interrupción del gobierno de Salvador Allende con el golpe militar en 1973. Esta investigación se basa, entre otras propuestas teóricas, en la de Katya Mandoki respecto de la prosaica o estética cotidiana, y muy particularmente, en el despliegue estético que realizan los Estados nacionales a través de diferentes prácticas y objetos. A su vez, nuestro enfoque metodológico para examinar los diseños de las monedas y billetes considera algunos elementos del análisis de la retórica de la imagen propuesto por Roland Barthes. Lo anterior, nos permite sostener que las monedas y billetes emitidos durante el proyecto de la Unidad Popular representaron una “comunidad heroica” de la vía chilena al socialismo a través de la difusión de los próceres nacionales, símbolos y frases inscritas en ellos, expresando la intención del gobierno de Allende de provocar emociones en la sociedad al vincular los valores de aquellos héroes con el proyecto de la izquierda chilena. Dicha construcción del panteón heroico de la Unidad Popular estuvo motivada fundamentalmente por la tradición del nacionalismo de izquierda, la concepción de la segunda independencia nacional, y la necesaria evocación de la chilenidad en la búsqueda de una ampliación del apoyo social. Estos “monumentos del dinero”, constituyéndose en lugares de memoria, dieron cuenta sutil y silenciosamente de una “comunidad heroica” de la revolución chilena que se propagó por todo el territorio nacional, haciéndose presente en la vida cotidiana de las personas.

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Huaytalla, Usurin Bryan Juan, and Quispe Diego Oswaldo Humari. "Desarrollo de un sistema electrónico portátil orientado a la detección de billetes falsos de 50, 100 y 200 soles basado en algoritmos de procesamiento digital de imágenes." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/652400.

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El presente proyecto de tesis propone el desarrollo de un sistema portátil de detección de billetes falsos de 50, 100 y 200 soles de diagnóstico automático basado en procesamiento digital de imágenes e implementado en un computador de placa reducida. En la actualidad, las técnicas de falsificación de billetes que se usan en el Perú son capaces de burlar a los sistemas de detección tradicionales. El sistema propuesto se basa en una detección más eficiente ya que enfoca la adquisición y segmentación de imagen en los patrones calcográficos de marcas de alto relieve. Para optimizar este proceso, se hace uso de una cámara, una lente y un recinto portable. Al resultado se le aplican filtros de repujado, de sobel, de erosión y de dilatación sucesivamente, para resaltar las características distintivas de los billetes legítimos. Finalmente, se usan Máquinas de Soporte Vectorial para clasificar los billetes falsos y los verdaderos, de acuerdo al proceso de entrenamiento realizado para cada denominación. El resultado entregado permitirá que el algoritmo pueda discernir la legitimidad del billete e indicarlo en un display para el entendimiento de cualquier usuario. Asimismo, el computador va conectado a una base de datos para transmitir las estadísticas de billetes falsos detectados. Para la validación de la solución, se han procesado muestras de 278 billetes entre verdaderos y falsos de 50, 100 y 200 soles provistos por el BCRP, o Banco Central de Reserva del Perú. En estas pruebas se obtuvo un porcentaje precisión mayor al 97% para identificar billetes falsos.
The present thesis project proposes to design a portable system to detect 50, 100 and 200 soles counterfeit bills with automatic diagnosis based on digital image processing and implemented on a reduced plate computer. Nowadays, the current counterfeiting techniques for bills being used in Peru are capable of eluding the traditional detection systems. The system being proposed is based on a more efficient detection because the acquisition and image segmentation is being focused on the chalcographic patterns of high relief. To optimize this process, a camera, a lens and a portable enclosure are being used. Then, the system applies the embossing filter, the sobel filter, the erosion filter and the expansion filter successively, to emphasize the distinctive characteristics of the legitimate bills. Finally, Support Vector Machines are used to classify real and counterfeit bills, based on the training process performed for each denomination. The result delivered will allow the program to discern the legitimacy of the bill and show it on a display to ease the understandment by any user. Likewise, the computer is connected to a database in order to transmit the statistics of counterfeit bills detected. To validate the solution, samples of 278 bills, counterfeit and legal, of 50, 100 and 200 soles were processed. These were provided by the BCRP, the official organism of Peru in charge of coins and bills. In this tests, the results show a presicion of over 97% of counterfeited bills correctly identified.
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Espinoza, Terrones Silvia, Vargas Julio Huamán, and Tasayco Carlos Trujillo. "Propuesta de mejora en la calidad de servicio, a través de los procesos de mantenimiento y producción, en una empresa de procesamiento de billetes y monedas." Master's thesis, Universidad Peruana de Ciencias Aplicadas - UPC, 2015. http://hdl.handle.net/10757/338565.

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El presente trabajo busca contribuir en el crecimiento del nivel de servicio al cliente (producto entregado sin defectos y a tiempo) en una empresa de procesamiento de billetes y monedas, proponiendo mejoras y soluciones desde la perspectiva del mantenimiento y la producción. Se presenta a la empresa donde se realizará el estudio, los procesos involucrados, los principales síntomas y las causas que los originan. Se concluye que el nivel de servicio percibido por el cliente se ve afectado por tres factores principales, los cuales son máquina, mano de obra y material. Las propuestas de solución y mejoras se trabajan en el tercer capítulo. Éstas se construirán desde la óptica de mejora de procesos que involucran también al recurso humano, tanto como partícipe activo y como pilar que sostiene los resultados a largo plazo. Asimismo se introduce el cálculo del indicador Efectividad Global de Equipos (OEE) para medir los resultados de los esfuerzos integrados de mejora de las áreas de Producción y Mantenimiento.

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Deustua, José R. "salinas, Alejandro. Cuatros y billetes. Crisis del sistema monetario peruano (1821-1879). Lima: Banco Central de Reserva del Perú, Instituto de Estudios Peruanos, 2011, 289 pp." Pontificia Universidad Católica del Perú, 2013. http://repositorio.pucp.edu.pe/index/handle/123456789/121610.

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Pinheiro, Carlos A. M. "Mould thermal response, billet surface quality and mould-flux behaviour in the continuous casting of steel billets with powder lubrification." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq27226.pdf.

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Berenguel, Centeno Albert. "Analysis of background textures in banknotes and identity documents for counterfeit detection." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/669589.

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Les falsificacions i copies pirata son formes de rob que no han parat de créixer en el darrers anys. Una falsificació es una reproducció no autoritzada d’un objecte autèntic/ genuí. Bitllets i documents d’identitat son dos objectes comuns de falsificació. El primer es usat per grups criminals organitzats per finançar una gran varietat d’activitats il·legals o inclús per desestabilitzar països degut a l’efecte de la inflació. Generalment, per poder operar un negoci il·lícit, els falsificadors creen companyies i comptes bancaris usant documents d’identitat fraudulents. Les activitats il·legals generades per bitllets i documents d’identitat falsificats provoquen danys a negocis, l’economia i a la població en general. Per lluitar contra falsificadors, governs i autoritats en el mon cooperen i desenvolupen mesures de seguretat per protegir els seus documents de seguretat. Moltes de les mesures de seguretat en documents d’identitat també es poden trobar en bitllets. En aquesta dissertació centrem el nostre esforç en detectar les falsificacions de bitllets i documents d’identitat analitzant les mesures de seguretat del fons d’impressió. El fons de documents de seguretat conté patrons de fines línies i dissenys que son difícils de reproduir sense els moderns equips d’impressió dels fabricants. Primer presentem l’estudi més complet fins avui de mesures de seguretat en bitllets i documents d’identitat. Els algorismes i sistemes comparats estan basats en visió per computador i aprenentatge automàtic. Posteriorment presentem el dataset de falsificacions de bitllets i documents d’identitat que hem construït i que s’utilitza durant tota la tesis. A continuació, avaluem i adaptem algorismes en la literatura per l’anàlisi de fons de seguretat. Estudiem el problema des de el punt de vista de robustesa, eficiència computacional i aplicabilitat en un entorn industrial real, proposant idees clau per utilitzar aquests algorismes. Posteriorment, dintre de l’entorn industrial d’aquesta tesis, desenvolupem una completa arquitectura orientada al servei per detectar documents falsificats. L’arquitectura de l’aplicació mòbil i servidor està pensada per ser utilitzada inclús per examinadors de documents falsificats inexperts. Més tard, reformulem el problema de detecció de textures del fons de seguretat com un joc de buscar diferencies, alternant mirades entre el fons falsificat i l’autèntic utilitzant xarxes neuronals recurrents. Finalment, tractem la falta d’exemples falsificats, presentant un nou algorisme basat en detecció d’anomalies.
Las falsificaciones y copias pirata son formas de robo que no han parado de crecer en los últimos años. Una falsificación es una reproducción no autorizada de un objecto autentico/genuino. Billetes y documentos de identidad son dos objetos comunes de falsificación. El primero es usado por grupos criminales organizados para financiar una gran variedad de actividades ilegales o incluso para desestabilizar países debido al efecto de la inflación. Generalmente, para poder operar un negocio ilícito, los falsificadores crean compañías y cuentas bancarias usando documentos de identidad fraudulentos. Las actividades ilegales generadas por billetes y documentos de identidad falsificados provocan daños a negocios, la economía y a la población en general. Para luchar contra falsificadores, gobiernos y autoridades en el mundo cooperan y desarrollan medidas de seguridad para proteger sus documentos de seguridad.Muchas de las medidas de seguridad en documentos de identidad también se encuentran en billetes. En esta disertación centramos nuestro esfuerzo en detectar las falsificaciones de billetes y documentos de identidad analizando las medidas de seguridad del fondo de impresión. El fondo de documentos de seguridad contiene patrones de finas líneas y diseños que son difíciles de reproducir sin los modernos equipos de impresión de los fabricantes. Primero presentamos el estudio más completo hasta la fecha de medidas de seguridad en billetes y documentos de identidad. Los algoritmos y sistemas comparados están basados en visión por computador y aprendizaje automático. Posteriormente presentamos el dataset de falsificaciones de billetes y documentos de identidad que hemos construido y se usa durante toda tesis. A continuación, evaluamos y adaptamos algoritmos en la literatura para el análisis de fondos de seguridad. Estudiamos el problema desde el punto de vista de robustez, eficiencia computacional y aplicabilidad en un entorno industrial real, proponiendo ideas clave para utilizar estos algoritmos. Posteriormente, dentro del entorno industrial de esta tesis, desarrollamos una arquitectura orientada al servicio para detectar documentos falsificados. La arquitectura de la aplicaciónmóvil y servidor está pensada para ser usada incluso por examinadores de documentos falsificados inexpertos. Más tarde, reformulamos el problema de detección de texturas del fondo de seguridad como un juego de buscar diferencias, alternado vistazos entre el fondo falsificado y el auténtico usando redes neuronales recurrentes. Finalmente, tratamos la falta de ejemplos falsificados, presentando un nuevo algoritmo basado en detección de anomalías.
Counterfeiting and piracy are a formof theft that has been steadily growing in recent years. A counterfeit is an unauthorized reproduction of an authentic/genuine object. Banknotes and identity documents are two common objects of counterfeiting. The former is used by organized criminal groups to finance a variety of illegal activities or even to destabilize entire countries due the inflation effect. Generally, in order to run their illicit businesses, counterfeiters establish companies and bank accounts using fraudulent identity documents. The illegal activities generated by counterfeit banknotes and identity documents has a damaging effect on business, the economy and the general population. To fight against counterfeiters, governments and authorities around the globe cooperate and develop security features to protect their security documents. Many of the security features in identity documents can also be found in banknotes. In this dissertation we focus our efforts in detecting the counterfeit banknotes and identity documents by analyzing the security features at the background printing. Background areas on secure documents contain fine-line patterns and designs that are difficult to reproduce without the manufacturers cutting-edge printing equipment. Our objective is to find the loose of resolution between the genuine security document and the printed counterfeit version with a publicly available commercial printer. We first present the most complete survey to date in identity and banknote security features. The compared algorithms and systems are based on computer vision and machine learning. Then we advance to present the banknote and identity counterfeit dataset we have built and use along all this thesis. Afterwards, we evaluate and adapt algorithms in the literature for the security background texture analysis. We study this problem from the point of view of robustness, computational efficiency and applicability into a real and non-controlled industrial scenario, proposing key insights to use these algorithms. Next, within the industrial environment of this thesis, we build a complete service oriented architecture to detect counterfeit documents. The mobile application and the server framework intends to be used even by non-expert document examiners to spot counterfeits. Later, we re-frame the problem of background texture counterfeit detection as a full-reference game of spotting the differences, by alternating glimpses between a counterfeit and a genuine background using recurrent neural networks. Finally, we deal with the lack of counterfeit samples, presenting a novel approach based on anomaly detection.

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Bressler, Iric Brooke. "Civilianization of Marine Corps billets: a methodology." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/26913.

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Dubec, Isabelle. "L'interbancarité et la tarification des retraits automatiques de billets." Toulouse 1, 1994. http://www.theses.fr/1994TOU10010.

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Cette thèse propose une étude du choix de compatibilité des réseaux de distributeurs automatiques de billets et de la tarification des retraits dans ces automates. Le premier chapitre décrit la formation d'un réseau commun aux banques françaises, la tarification des retraits automatiques ainsi que les controverses au sujet de l'équilibre entre la coopération et la concurrence inter-bancaire. Le deuxième chapitre examine la littérature sur la décision des firmes concurrentes à rendre leurs produits compatibles. En particulier, des firmes verticalement intégrées sont assimilables à des banques proposant la gestion d'un compte courant et le retrait automatique. Elles ont alors souvent intérêt à rendre leurs réseaux de distributeurs compatibles, même en l'absence d'externalité liée à la consommation. Ces applications aux cadres de retrait n'expliquent cependant pas le choix de la taille des réseaux par les banques. Le troisième chapitre montre que cette question est essentielle et pour cela, modéliste le rôle d'une commission inter-bancaire sur l'incitation des banques à ouvrir des distributeurs et à les rendre compatibles. Nous proposons aussi d'analyser l'influence d'une telle tarification du retrait sur la concurrence au niveau des services bancaires
This thesis studies the decisions of banks on compatibility of their automated teller machines and pricing cash withdrawals in these machines. The first chapter describes the creation and the development of the French shared atm network. It also presents the main controversial topics like the trade off between cooperation and competition among banks. The second chapter is a survey of the literature on compatibility decisions of competing firms. In particular, some firms that are vertically integrated can be seen as banks managing demand deposits and proposing automatic cash withdrawals. In this case, banks generally prefer to make their networks compatible even without the existence of consumption externalities. The models in the existing literature do not consider the size of atm networks as a strategic variable for the banks. The third chapter proves that this variable has a significant effect on the atm networks degree of compatibility this result is obtained with a model that studies the effect of interchange fees among banks in order to incline therm to increase the size of their networks and make them compatible. We analyse the effect of such a cash withdrawals pricing on the competition between banks to attract depositors

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Billet, Arnaud. "Relations structure-fonction du CFTR : étude de l'influence de l'extrémité C-terminale du NBD1 et de son environnement moléculaire sur l'adressage, l'activité et la pharmacologie des canaux." Poitiers, 2010. http://theses.edel.univ-poitiers.fr/theses/2010/Billet-Arnaud/2010-Billet-Arnaud-These.pdf.

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La protéine transmembranaire CFTR (Cystic Fibrosis Transmembrane conductance Regulator), impliquée dans la mucoviscidose est un canal chlorure régulée par l'ATP et l'AMPc. Les mécanismes de régulation des processus d'ouverture/fermeture du canal ne sont pas encore clairement démontrés mais depuis quelques années, les nouvelles données sur la structure moléculaire de la protéine ont permis des avancés dans ce domaine. Les objectifs de ce travail de recherche ont été de caractériser, par une étude de relation structure/fonction, le rôle de l'extrémité C-terminale du NBD1 et de son environnement moléculaire dans la régulation de la maturation ou de l'activité du canal ainsi que dans sa pharmacologie. Certains résidus déterminés par l'exploration des modèles moléculaires ont été mutés par mutagenèse dirigée puis les conséquences de ces mutations ont été analysées par les techniques de western blot, de patch clamp et d'efflux d’iodure. Nos travaux ont permis de mettre en évidence l'importance de l'intégrité de la structure en épingle à cheveux de l'extrémité C-terminale du NBD1 ainsi que de ses différentes liaisons, dans la maturation et l'activité du canal. Concernant le mécanisme d'action des composés MPB, composés à double action (activateur et correcteur de CFTR), nous avons montré que la perturbation directe de la structure de la β-hairpin rendait l'action des composés impossible alors que la perturbation de la liaison avec le Walker A du NBD2 induisait une meilleure action des MPB. Nos travaux ont donc permis de mettre en évidence un rôle important de l'extrémité C-terminale du NBD1 dans la régulation de l'adressage, de l'activité et de la pharmacologie du canal CFTR
Cystic fibrosis (CF) is caused by mutations of the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR). CFTR is a chloride channel regulated by ATP and cAMP. The regulation of the CFTR gating remains unclear. In this study we have investigated the role of the last β hairpin of NBD1 and its direct environment in the maturation, the activation and the pharmacology of the channel. We also performed a molecular dissection of CFTR by examining several CFTR mutants (constructed by site directed mutagenesis and tested by western blot, patch clamp recording and iodide efflux) located in the last β hairpin of NBD1 or in contact with it. Our results indicated that the integrity of the beta hairpin (and in particular the orientation of the two latest β strands) and its links with other domains is important for the maturation, the activity but also the pharmacology of the channel. All these results suggest an important influence of the C-terminus of the NBD1 for the control of CFTR channel gating and protein trafficking

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Germain, Lionel. "Contribution à l'étude des hétérogénéités de texture des billettes d'IMI 834." Metz, 2005. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2005/Germain.Lionel.SMZ0518.pdf.

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L'IMI 834 est un alliage de titane pseudo-[alpha] utilisé pour la fabrication de compresseurs haute pression de moteurs d'avions. La microstructure des pièces en service, est formée de grains [alpha]p primaires équiaxes dans une matrice de colonies lamellaires [alpha]s (ou de Widmanstätten). Cette microstructure bimodale a été optimisée pour obtenir un bon compromis de comportements du matériau en fluage et en fatigue. Toutefois, les pièces forgées peuvent renfermer des zones de tailles millimétriques (appelées 'macrozones'), caractérisées par de très fortes textures locales, qui semblent avoir une influence significative sur la réduction de la tenue en fatigue du matériau, notamment lors du maintien de la charge (dwell fatigue). Ce travail propose une étude détaillée des hétérogénéités de texture et microstructure locales présentes dans les billettes d'IMI 384 de structure bimodale et dommageables pour la tenue en fatigue. Les microstructures observées contiennent des indications importantes sur la formation de ces hétérogénéités au cours de l'élaboration de la billette. Leur analyse nous a permis une meilleure compréhension de la genèse de ces hétérogénéités et à termes nous guide vers des traitements thermomécaniques additionnels conduisant à leur réduction. L'étude s'appuie sur les données de cartographies d'orientations obtenues par la technique EBSD et sur des outils spécifiques spécifiquement développés pour cette étude. Nous avons tout d'abord élaboré une méthode qui permet de distinguer automatiquement sur les cartographies d'orientations, les orientations des grains [alpha]p des orientations des colonies [alpha]s. La contribution de chaque population de grains, à la formation des hétérogénéités de texture a pu ainsi être déterminée par nos soins. Par ailleurs, nous avons utilisé les cartographies partielles de la phase [alpha]s pour recalculer les microtextures [bêta] parentes et déduire la microstructure à haute température formée par l'enchevêtrement des phases [alpha]p et [bêta]. Nous avons ainsi examiné l'incidence de ces microstructures complexes sur la formation des macrozones. Parallèlement, nous avons tiré parti de différents essais de compression dans les domaines[bêta] et [alpha]/[bêta], pour suivre le développement des macrozones et suggérer des chemins de déformation réduisant leur présence. Nos travaux montrent que les macrozones correspondent à des zones fortement allongées dans la direction axiale de la billette, dans lesquelles les grains [alpha]p présentent une composante de texture unique mais dispersée, telle que les axes c soient principalement dans une direction radiale. Les colonies[alpha]s sont orientées autour de plusieurs composantes de texture mais avec une composante majoritaire proche de l'orientation des grains [alpha]p. Dans ces zones, la texture locale de la phase [bêta]parente est peu marquée. Par conséquent, les macrozones ne correspondent pas directement à la trace de larges grains [bêta] fortement allongés selon la direction axiale, suite aux étapes de forge en [bêta]. La forte texture de la phase [alpha]p est le résultat d'une déformation / globularisation hétérogène de la phase[alpha] se présentant initialement sous forme de lamelles regroupées en large colonies, en relation de Burgers avec la phase [bêta] environnante. La texture marquée de la phase[alpha]s est héritée de la transformation de la phase [bêta] par un mécanisme de sélection de variantes lors de la transformation [bêta] [vers] [alpha]s, en présence des grains [alpha]p. Nous avons mis en évidence, pour cette sélection de variantes, le rôle de certains joints spécifiques [alpha]p/bêta, permettant le développement de colonies [alpha]s minimisant les désorientations [alpha]p/[alpha]s. Par ailleurs, la modélisation montre également que l'anisotropie élastique liée aux fortes textures locales de la phase [alpha]p tend à privilégier les orientations [alpha]s proches de l'orientation des grains [alpha]p. L'examen de ces différents résultats nous a conduit à réaliser des essais additionnels de compression de la billette pour tester la possibilité de réduire les macrozones par des déformations complémentaires adaptées. Ce travail ouvre des perspectives pour l'optimisation des traitements thermomécaniques pour la réalisation des pièces industrielles en IMI 834
The IMI 834 is a quasi-[alpha] titanium alloy used to design high pressure compressors for aero-engines. The microstructure of the final parts is composed of equiaxed primary [alpha]p grains in a lamellar matrix of secondary [alpha]s colonies (also called Widmanstätten microstructure). This bimodal microstructure was optimised to provide a good behaviour of the material in both creep and fatigue. However, the forged parts can contain millimetre long regions called macrozones, characterised by very sharp local textures which seem to significantly reduce the fatigue resistance of the material, in particular in dwell fatigue testing. This work is a detailed study of the texture heterogeneities and local microstructures that are damageable for the fatigue resistance of bimodal IMI 834 billets. The observed microstructures contain important indications on the formation of these heterogeneities during the billet elaboration. Their analyses allow for a better understanding of the genesis of the heterogeneities and further, guide us toward additional thermomechanical heat treatments that could lead to their reduction. The study is based on orientation maps obtained by the EBSD technique and on specifically developed tools. We first elaborated a method to distinguish the [alpha]p grains from the [alpha]s colonies, automatically on orientation maps. Thus, we determined the contribution of each population of grains to the formation of the heterogeneities. Moreover, we used the partial orientation map of the [alpha]s phase to calculate the parent [bêta] microtextures and deduced the high temperature microstructure formed by the combination of the [alpha]p and the [bêta] phases. Thus, we analysed the influence of this complex microstructure on the formation of the macrozones. In parallel, we took advantage of various compression tests to follow the development of the macrozones and suggest a deformation route that can reduce their intensity. Our work shows that the macrozones correspond to regions elongated in the axial direction of the billet, in which [alpha]p grains have an unique but dispersed texture component, so that the c axes mainly point in the radial direction. The [alpha]p colonies are oriented around several texture components but have their main component matching the unique component of the [alpha]p grains. In these zones, the local texture of the parent [bêta] phase is relatively smooth. Consequently, the macrozones cannot correspond directly to the traces of the large [bêta] grains strongly elongated in the axial direction after the forging in the [beta] field. The sharp [alpha]p texture results from an heterogeneous deformation / globularisation of the [alpha] phase that initially corresponded to the colonies of lamellae that were in Burgers orientation relation with the [bêta] matrix. The sharp texture of the [alpha]s phase is inherited from the transformation of the [bêta] phase through a variant selection mechanism occurring during the [bêta] [to] [alpha]s phase transformation in the presence of [alpha]p grains. In this variant selection, we have highlighted the role of certain [alpha]p/[bêta] phase interfaces which promote certain [alpha]s variants that minimise the [alpha]p/[alpha]s misorientations. Moreover, modelling showed that the elastic anisotropy due to the strong local textures of the [alpha]p phase tends to favour the [alpha]s orientations close to [alpha]p orientation. The analysis of the different results led us to make further compression tests to evaluate the possibility of reducing the macrozones. This work offers some new perspectives in the production of industrial parts in IMI 834

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17

Chatzikos, Nikolaos. "Influence of fluxing agent on the quality of recycled Aluminium billets." Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231166.

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The quality of aluminium cast billets is highly dependent on the cleanliness of the material. Hydro Extruded Solutions are casting billets in Sjunnen that are delivered for extrusion within the same company. In order to produce extruded profiles of high quality and also maintain the pressing tools, it is a good method to keep the billets as free from inclusions as possible. A fluxing agent in form of salt compounds is used to purify the material during melting, but also to protect it from further oxidation. Another task of fluxing agents is to minimize the aluminium amount in the dross phase. The purpose of this project was to investigate if the fluxing agent that is used by the cast house is having any impact on the quality of the billets. Therefore, for that purpose, samples with a variating amount of fluxing agent were processed by the cast house in order to be investigated. These samples were investigated with the Optical Microscopy-method in order to determine the area fraction of non-metallic inclusions inside them. The results did not reveal any significant difference in the quality of the different samples since most samples obtained a low OM-index after the investigation. That can be explained by the type of scrap that was used since new scrap is usually very clean and contains smaller amounts of inclusions.
Kvaliteten hos aluminiumgöt är starkt beroende av renheten i materialet. Hydro Extruded Solutions gjuter rundgöt i Sjunnen, som sedan levereras för strängpressning inom samma företag. För att producera strängpressade profiler av hög kvalitet och även upprätthålla pressverktygen, är en bra metod att hålla göten så fria från inneslutningar som möjligt. Ett flussmedel, i form av saltföreningar, används för att rena materialet under smältningen, men också för att skydda den från vidare oxidation. En annan uppgift som flussmedel har är att minimera mängden aluminium i slaggfasen. Syftet med detta projekt var att undersöka om flussmedelet som används av omsmältverket har någon inverkan på götkvaliteten. Därför, för detta ändamål har prover med en varierande mängd av flussmedel tillverkats i omsmältverket för att bli undersökta. Dessa prover undersöktes med den Optiskt Mikroskopiska-metoden för att bestämma areafraktionen av icke-metalliska inneslutningar inuti dem. Resultaten avslöjade inte någon signifikant skillnad i kvaliteten hos de olika proverna eftersom de flesta prover erhöll ett lågt OM-index efter undersökningen. Detta kan förklaras av vilken typ av skrot som användes, då process-skrot oftast är väldigt rent och består av mindre mängder innseslutningar.

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Padgett, Cynthia A. "The Officer Billet Cost Model." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23336.

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The purpose of this thesis is to present a military manpower costing model which is appropriation oriented to be used for budget planning purposes. The purpose of the model is to arrive at a more refined cost estimate for individual officers or groups of officers based on their area of specialization and qualifications. This model is intended for use by program sponsors in the planning and budgeting of billets for their programs and personnel for the billets. The Officer Billet Cost Model is constructed showing variation in officer costs by paygrade. Pay components of the Military Personnel, Navy(MPN)account that could not be assigned to individual groups of officers were incorporated in a basic cost model. Pay components of the MPN account that could be assigned by designator were incorporated into individual submodels. Keywords: Cost estimates; Naval personnel; Cost effectiveness; Naval training; Recruiting. (kr)

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19

Kennedy, Mark William. "Magnetic Fields and Induced Power in the Induction Heating of Aluminium Billets." Licentiate thesis, KTH, Materialens processvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-123783.

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Induction heating is a common industrial process used for the reheating of billets before extrusion or forging. In this work the influence of the coil and work piece geometry, the effect of the electrical properties of the work piece, and the coil current and frequency, on the magnetic flux density and resulting work piece heating rates were studied. A combination of 1D analytical solutions, 2D axial symmetric finite element modelling and precise measurements has been used. Dozens of heating and magnetic field experiments have been conducted, with steadily increasing sophistication and measurement accuracy. The development of the experimental techniques will be described in the ‘cover’ and related to the later results published in the supplements. Experimental results are compared to predictions obtained from analytical and numerical models. The published measurements obtained for the billet heating experiments consisted of: billet electrical conductivity with <0.5% error, applied currents with <1% error, magnetic flux densities with 1-2% error, calorifically determined heating rates with <2% error and electrical reactive power with <~2% error. 2 D axial symmetric finite element models were obtained, which describe the measured results with less than a 2% difference (i.e. an ‘error’ of the same magnitude as the measurement uncertainty). Heating and reactive power results predicted by the FEM model are in excellent agreement with analytical solutions from 50 Hz to 500 kHz (differences from <1% to 6%). A modified 1D short coil correction factor is presented which accounts for the interaction of the coil and work piece geometry, electrical properties and operating frequency, on the average magnetic flux density of the coil/work piece air-gap and the resulting heating rate. Using this factor, the average magnetic flux density in the air-gap can be estimated analytically within 2-3% and the heating rates of billets of known electrical properties can be estimated, with typical errors on the order of 5%.

QC 20130618

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20

Alston, Thomas Porter. "A prototype expert system which assigns aviation maintenance personnel to squadron billets." Thesis, Monterey, California: U.S. Naval Postgraduate School, 1987. http://hdl.handle.net/10945/22440.

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The technical feasibility of developing an expert system to support the assignment of squadron maintenance personnel to authorized billets is examined by building a prototype system. The rules used by an assistant maintenance officer to assign personnel are analyzed, and a database derived from the OPNAV 1000/2 and EDVR is designed. The prototype is developed for a micro-computer system using an expert system shell, Insight 2+, and is fully integrated with dBase III files

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21

Kholmatov, Shavkat. "On some positive effects of swirling flow for the continuous cast mould billets." Licentiate thesis, Stockholm : Division of Applied Process Metallurgy, School of Industrial Engineering and Management, Royal Institute of Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4453.

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22

Mevel, Bruno. "Comportement dynamique des roulements à billes." Lyon, INSA, 1992. http://www.theses.fr/1992ISAL0079.

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Le comportement dynamique d'un roulement à billes est étudié grâce à un modèle théorique et à une série d'expériences. Une des conclusions attendues, de cette étude, concernait l' influence des défauts sur les vibrations engendrées par le roulement. Mais le problème n'est pas simple puisqu'il fait appel à la dynamique des systèmes fortement non-linéaires et qu'il a été nécessaire d'utiliser des outils de la physique des phénomènes chaotiques pour comprendre les mouvements. On a décrit les routes vers le chaos, qui apparaissent en fonction de la vitesse de rotation et des caractéristiques de jeux et d'amortissement, soit par cascade de sous-harmoniques ou par mouvements quasi-périodiques. Une expérimentation a permis de visualiser certaines des bifurcations prévues par la théorie. Un logiciel de simulation des vibrations de roulements à billes avec défauts géométriques des constituants a résulté de l'analyse, la confrontation à l' expérimentation s'est avérée excellente. L'étude a permis de montrer les effets de masque de certains défauts par rapport à d'autres et donc au stade industriel d'agir sur le procédé de fabrication induisant le défaut à effet dominant
The dynamical behaviour of a ball bearing is studied through a theoretical model and some experiments. One of the expected issues was the evaluation of the vibration generated by the geometrical imperfections of bearings. But the problem is not easy because the bearing is a highly non-linear system and the techniques of the chaotic physics were used to describe the motions. The routes to chaos were described as functions of the rotational speed, the damping factor and the internal clearance of the bearing, they are the cascade of sub-harmonic and the quasi-periodic routes. An experiment was carried out and showed some of the bifurcations scheduled by theory. A program was achieved to simulate the vibration of bearing including its geometrical imperfections and the comparison with experiments was excellent. Our study showed that some of the defects are masked by predominant imperfections and therefore the fabrication process to be improved

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23

Barbier, Damien. "Étude de la sensibilité aux gradients thermiques de billettes lors des opérations de réchauffage." Thesis, Valenciennes, 2013. http://www.theses.fr/2013VALE0040/document.

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Dans le cadre des opérations de perçage, les billettes en acier subissent un réchauffage de la température ambiante à une température d’environ 1250°C. Au cours de ce réchauffage, le gradient de température dans les billettes entraîne la détérioration de la santé axiale de celles-ci et est à l’origine de l’apparition de défauts sur le tube formé. Une méthodologie d’analyse des mécanismes à l’origine de ces défauts a été mise en place. Elle se base sur la caractérisation de la santé axiale par essais rhéologiques permettant d’établir des indicateurs de ductilité et par des examens métallurgiques identifiant les défauts internes.L'étude de la sollicitation thermomécanique induite par le réchauffage du produit est analysée à l’aide de simulations numériques par éléments finis et les zones de sollicitations critiques associées au procédé sont identifiées. La caractérisation des anomalies observées sur les billettes est ensuite faite à partir d’essais de fissuration et de simulations numériques X-FeM. L’implémentation d’un critère de rupture en contrainte dans la simulation du cycle de chauffe a permis de définir les valeurs de gradient thermique limite et les courbes de chauffe optimales. Les analyses montrent que les conditions de chauffe en début de cycle thermique ont une forte influence sur la santé axiale des billettes. Les résultats de ces travaux conduisent à des solutions concrètes pour l’amélioration de la productivité
As part of the piercing operations, billets undergo a reheating process from room temperature to a temperature of about 1250°C. During this heating, the thermal gradient in the billet leads to a deterioration of the axial health and is responsible of the initiation ofdefects on the formed tube.A methodology for the analysis of the mechanisms at the origin of these defects has been established. It is based on first, the characterization of the axial health with hot rheological tests to establish some indicators of ductility and second, on metallurgical analyses to identify the internal defects.Then finite element simulations have been performed to study the thermo-mechanical loadings induced by heating. Critical solicitation zones of the product during the processes have been identified.Finally a characterization of the observed defects into the billets has been led coupling cracks growth tests and X-FeM numerical simulations. The implementation of the experimental stress failure criterion, in the simulation of the heating cycle allows to obtain good values of thermal gradient boundary curves and leads to optimal heating curves.The analysis shows that the conditions at the beginning of the reheating process have a strong influence on the axial health of the billets. The results of these studies lead to friendly industrial solutions for improving productivity

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MIETTE, VERONIQUE. "Retournement temporel des ondes ultrasonores application au controle non destructif des billettes de titane." Paris 6, 1998. http://www.theses.fr/1998PA066240.

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Les pieces en titane utilisees dans les turboreacteurs peuvent contenir des defauts de microstructure appeles hard-alpha qui sont susceptibles d'engendrer des fissures. L'objectif de ce travail est d'ameliorer les criteres de detection de ces defauts par l'emploi du retournement temporel (rt), methode fondee sur l'utilisation des informations de phases et d'amplitude contenues dans une onde ultrasonore retrodiffusee par le milieu. Nous presentons tout d'abord la theorie du rt ainsi que les limitations rencontrees par les methodes de controle non destructif classiques. En effet, les alliages de titane constitues d'une multitude de grains generent un bruit ultrasonore qui peut dissimuler l'echo provenant du defaut. De plus, la propagation a travers une forte epaisseur de microstructure induit des aberrations de phases qui degradent la qualite du faisceau incident et les performances de detection. Nous appliquons ensuite le rt a la detection de defauts etalons dans des billettes de titane. Les reseaux de transducteurs a surface de fermat, concus pour eviter les aberrations dues a l'interface cylindrique, ainsi que les traitement des signaux bases sur les proprietes du rt sont developpes pour maximiser les rapports signal sur bruit. Un nouveau procede de prefocalisation electronique basee sur le rt permet de determiner la loi de retards ideale necessaire pour focaliser au coeur des billettes. Le processus de detection par rt est ensuite modelise afin de determiner les parametres critiques lors des inspections tels que la duree du rt et le nombre d'iterations. Pour completer cette etude, la rugosite des interfaces des billettes est caracterisee a l'aide du rt et son influence sur la detection d'un defaut est discutee. A travers ces differentes etudes, nous demontrons l'efficacite du rt applique au cnd du titane.

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25

Mohammadiha, Nasser. "Measuring the geometrical parameters of steel billets during the molding process by image processing." Thesis, Sharif University of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-42595.

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In this project we present a machine vision system to measure the geometrical parametersand dimensional defects of steel billets (blooms/slabs). Geometrical parameters includewidth, height and length and dimensional defects include camber, rhomboid difference andtorsion. The system has been equipped with a color camera, an industrial computer andother peripheral equipments such as lens, Ethernet Cat-5 cable and camera housing. Digitalimage processing techniques have been used to analyze the single view images. To do so,the image is enhanced first and then it is reregistered with a constant background. Afterthat the billet’s motion is calculated and the image is segmented. The billet boundary linesare then estimated using billets geometrical features. Then the Hough transform isfollowed by the canny edge detector to detect and link the exact sides of billets. Twocalibration methods have been used to transform the measured values in pixel to wordreference values in centimeter. These techniques result in removing the necessity of multicameras that have been used in the same projects by keeping the accuracy.
در اين پروژه سيستمي را براي اندازه گيري ابعاد هندسي و نقصهاي ابعادي شمشهاي فولادي ارائهميدهيم. براي اندارهگيري عرض، ارتفاع و طول شمش در كنار اندازهگيري خميدگي، لوزيشدگي وو IPC پيچش شمش از سيستم ماشين بينايي استفاده ميكنيم كه از يك دوربين رنگي ، كامپيوتر صنعتيساير تجهيزات جانبي مثل لنز ,كابل شبكه و محفظه دوربين تشكيل شده است. تصاوير يكنمايي برداشتهشده مورد آناليز قرار ميگيرند و با تكنيكهاي پردازش تصوير اضلاع شمش در آنها پيدا مي شوند. براياين منظور ابتدا كيفيت تصوير بهبود يافته وسپس نسبت به يك مرجع ثابتي ثبت ميشود سپس مقدارحركت شمش در بين دو تصوير متوالي محاسبه ميشود. در ادامه تصوير بخشبندي شده و اضلاعدر اطراف اين اضلاع تقريبي Canny تقريبي شمش از روي مشخصات كلي شمش پيدا مي شوند. روشبه كار گرفته ميشود تا لبه هاي شمش تشخيص داده شوند. براي حذف اثر نويز وگسستگي لبهها ازاستفاده ميشود تا محتملترين خطوط را در تصوير به عنوان اضلاع شمش در نظر بگيرد. Hough تبديلبراي تبديل ابعاد پيكسلي محاسبه شده به مقادير واقعي كه بر حسب سانتيمتر هستند از دو تكنيككاليبراسيون به طور همزمان استفاده ميشود تا ضمن حفظ دقت، نياز به دوربينهاي بيشتر كه در پروژهاي مشابه مورداستفاده قرار ميگيرند از بين برود.

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Bommaraju, Ramaprasad V. "Mold behavior, heat transfer and quality of billets cast with in-mold electromagnetic stirring." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28628.

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Mold behavior, mold-related quality and the columnar-to-equiaxed transition influenced by in-mold EMS were examined by performing trials at two steel companies, metallurgical examination of the billet samples and mathematical modelling. The thermal fields in the walls of billet molds (102 X 102mm and 127 X 178mm) and in the cooling water were monitored by a system of thermocouples as the EMS was switched on and off during the continuous casting of several heats. The effect of electro-magnetic stirring on mold heat extraction was found to be negligible. The mold temperatures and cooling water temperatures are strongly dependent on the mold/billet gap which is affected by dynamic distortion of the mold tube. In the case of the square mold, the time-dependent mold distortion resulted from boiling adjacent to the cold face due to low water velocity and poor water quality. In the rectangular mold, differential expansion of the wide and narrow faces of the mold led to periodic wall movement at the midface causing cycling in the mold and water temperature. Both effects completely dominated any potential influence of EMS on mold heat extraction. Cooling water velocities measured in separate experiments and the mold temperature profiles were input to a two-dimensional heat-flow model to establish mold heat-flux profiles. A steep taper of 2.6 %/m in the upper regions of the mold increased heat extraction compared to previously published heat-flux data in 0.8 %/m tapered-molds. However, due to the periodic wall movement in the rectangular mold, the heat flux declines to lower values periodically. The calculated heat flux profiles were employed in a one-dimensional transient heat flow model to predict superheat removal from the liquid pool under a variety of assumed fluid flow conditions. The major heat flow effect of EMS was inferred to be one of increasing the convective heat flow at the solidification front leading to earlier superheat extraction from the liquid steel. Solidification structures in billet samples collected during the trials were examined. The columnar-to-equiaxed transition in continuous casting takes place provided all the superheat is removed from the melt and there is a sufficient density of nuclei present in the pool. At superheats of <20° C in the tundish, high heat extraction in the mold and remelting of the mold generated nuclei facilitate the removal of the superheat well within the mold and the columnar-equiaxed transition is triggered after 10-15 mm of shell growth on both the inside and outside radius faces. At higher superheat in the tundish, the liquid pool leaves the mold with residual superheat which takes longer to remove because of the declining fluid flow. Even though all the superheat is removed lower in the machine, the columnar-equiaxed transition occurs only if dendrite debris generated in the vicinity of the mold has survived in their descent through the superheated liquid. The effect of carbon on the columnar-to-equiaxed transition appears to stem from its influence on facilitating dendrite arm remelting and the survival of the dendrite fragments till the pool reaches sub-liquidus temperature. EMS extracts more superheat by maintaining a steep temperature gradient in the thermal boundary ahead of the solidification front and achieves an earlier columnar-equiaxed transition. Electro-magnetic stirring appears not to affect either the average depth or the variation of depth of oscillation marks across a given face. However, the electro-magnetically driven flow dominates the turbulance at the meniscus due to the input stream and stabilizes a meniscus shape with the result that the oscillation marks are also of a well-defined shape unlike the unstirred billets. No influence of EMS was found on the formation of "hooks" or the fine equiaxed crystal zone near the surface. The influence of EMS on inclining the growing dendrites appears to not come into effect until about 1 mm of shell has formed. It appears that the existence of the momentum boundary layer where the velocity of the rotating steel falls to zero at the surface is the reason for the absence of the influence of EMS on the subsurface solidification. Rhomboidity and off-corner crack formation were found to depend, as reported by previous researchers, on mold distortion and its dynamic nature. The absence of any effect of EMS on these defects is due to its lack of effect on mold heat transfer and thus mold distortion.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate

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Onipede, Bolarinwa O. "Design of a cross section reduction extrusion tool for square bars." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4880.

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The objective of this project is to design a tool for moderate cross section reduction of bars that are deformed within a channel slider tool that is used for equal channel angular extrusion (ECAE). The bars that are deformed via ECAE have an initial square cross section with a nominal value of 1.00 in2 and aspect ratios (length/width) ranging between 4 and 6. A systems engineering design methodology is used to generate a topbottom approach in the development of the tool's design. This includes defining a need statement, which is the "Need for an area reduction extrusion tool to replace the current practices of machining ECAE processed billets". The system functions and requirements are defined next and used to generate three concepts that are compared to select the winning concept for further refinement. Major components of the selected tool are: a container, ram, base plate, punch plate, four die-inserts, four wedges and four flange locks. For materials, such as copper (C10100) and aluminum (Al6061-T6), that can be processed by this tool, the upper bound extrusion pressure, which is derived by limit analysis, is set at 192 ksi. The upper bound extrusion pressure is constrained by the buckling limit of the ram, which is 202 ksi. The maximum wall stress experienced by the container is 113 ksi. For materials with the same cross section and dimensions, fixed end conditions of the Ram support larger bucking loads when compared to other end conditions such as rounded ends or rounded-fixed ends. With the application of the upper bound method, an increase in the extrusion ratio of the tool causes a corresponding rise in the optimal cone angle of the die further translating to a rise in the extrusion pressure.

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Brendzy, J. Lorraine. "The detection of mould-strand interaction employing load cells in the continuous casting of billets." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/32741.

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Instrumentation of the mould with load cells and linear variable displacement transducers was completed to evaluate mould-strand interaction in a continuous casting machine for steel billets. A plant trial was conducted in which several lubricants were tested at four rates. Three carbon grades were cast under similar mould lubricating conditions. In the analysis of the accumulated data, correlation between the mould loading as determined by the load cell signals and the oscillation cycle as indicated by the linear variable displacement transducers was achieved. The load cell data indicated that there are two modes of strand-mould interaction occurring during each oscillation cycle. During the positive-strip period, lubrication conditions and carbon content were observed to affect the loading of the mould but during the negative-strip period, the effects of lubrication and carbon are masked due to the mould bearing down on the strand. During the period which the mould travels downward faster than the strand, the load cell response indicated a smooth decrease in mould loading. It is also shown that the minimum load reached is related with changes in casting speed: as casting speed decreases, the mould attempts to overtake the strand to a greater extent than when the casting speed is higher. The result is a greater decompression of the load cell when casting speeds are slower. This finding supports a proposed mechanism for the formation of oscillation marks in billets. It is shown that different lubricants produce different loading responses and that a reduction in flow rate causes increases in load on the mould during upstroke. A theoretical analysis employing a fluid flow model has also been undertaken to determine the presence of lubricant at the meniscus during an oscillation cycle. The results from this analysis indicates that lubricant reaches the meniscus generally during the downstroke and that replenishment of lubricant at the meniscus does not occur during the upstroke leaving only residual lubricant to provide lubrication at the mould-strand interlace. This finding suggests that two modes of lubrication may operate: hydrodynamic lubrication occurring when lubricant is present at the meniscus and boundary layer or solid layer lubrication operating when bulk lubricant does not reach the meniscus region. From the load cell response, binding was evident which was correlated with the presence of depressions found on the surface of examined billets.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate

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GROSSHANS, DANIEL. "Proprietes mecaniques d'un assemblage de billes de gel." Université Louis Pasteur (Strasbourg) (1971-2008), 1993. http://www.theses.fr/1993STR13180.

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Le systeme etudie est un assemblage de billes de gel de polyelectrolytes. Il peut etre considere comme un assemblage amorphe et compact de spheres elastiques en contact, proche d'un metal amorphe au zero absolu. Le but de cette these est d'etudier le comportement mecanique macroscopique d'un tel assemblage. Des experiences de porosite au cours du gonflement ont montre l'existence d'un seuil de percolation que nous avons prevu theoriquement par un modele simple: il y a des canaux de solvants dans l'assemblage au-dela de ce seuil. Des experiences d'ecrasements a bords libres que nous avons comparees a une simulation numerique montrent les cristallisations partielles entre deux plans sur quatre couches de billes. A l'equilibre de gonflement, les mesures d'ecoulement avec des plans lisses revelent le comportement d'un fluide a seuil. En fait, on observe un glissement du plan superieur sur le lit de billes par l'intermediaire d'un film d'eau. Le regime d'ecoulement a pu etre modelise: la contrainte seuil resulte d'un couplage elasto-hydrodynamique. Cisaille dans la masse, l'assemblage se comporte comme un fluide plastique. L'ecoulement de l'assemblage a lieu au-dela d'une deformation critique, universelle pour les systemes cellulaires amorphes, et peut etre compris en terme de reorganisations de billes. La rheologie d'alliages de billes dures dans des billes molles a montre l'importance du role des contacts

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30

Jasper, Jean. ""Seditious Billes" : Treacherous Correspondence on the Renaissance Stage." Thesis, Birmingham City University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517149.

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This study has two primary purposes; to examine the evolution of the concepts and statutes of Tudor treason legislation as reactions to unprecedented political, religious and social changes, and to develop the relationship between this thesis of treason and the Renaissance stage. An analysis of a broad and relatively un-researched body of historical and legal material accounts for the conditions in which writing, particularly the personal letter, aroused anxiety and suspicion. It is argued that this political and religious tension inspired the inclusion of writing as treason in the 1534 treason act, a statute drawing upon the concept of imagining the king's death of the Great Statute of Treason of Edward III. The letter is identified as the primary document of proof of "imagination" or intent in Tudor judicial opinion. A close study of treason trials of the period, in which the generic significance is the use of letters as evidence of intent against the alleged traitors, presages a substantive and novel reading of the chosen plays of this study, which foregrounds the discernable political and cultural anxieties of these judicial events. Differing, both in substance and approach, from traditional analyses, the treatment of each play (and other primary texts) evaluates and locates dramatic representations of treacherous correspondence within Tudor concepts of treason, while incorporating gender theory and post-structural reassessments of spoken and written language. In resituating Renaissance plays in the debate on treason, this study addresses the regulation of language, not merely within the Tudor law of treason by words, but also the play text, both complex, and, yet, mutable expressions of containment. It is, perhaps, the deliberate ambiguity of both statute and stage that allows continuing critique, such as that undertaken here.

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31

Peng, Xuan. "Co-deformation and bonding of multi-component billets with application to Nb-Sn based superconductor processing." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1127096847.

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Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xix, 182 p.; also includes graphics (some col.). Includes bibliographical references (p. 177-182). Available online via OhioLINK's ETD Center

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Bonderup, Gerda. ""Cholera-Morbro'er" og Danmark : billeder til det 19. århundredes samfunds- og kulturhistorie /." Aarhus : Aarhus universitetsforlag, 1994. http://catalogue.bnf.fr/ark:/12148/cb36180664x.

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Jones, Terrence L. "A qualitative analysis evaluating of the assignment of Human Resource Officer (HRO) subspecialty codes to HR billets." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Sep%5FJones_Terrence.pdf.

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Thesis (M.S. in Business Administration)--Naval Postgraduate School, September 2006.
Thesis Advisor(s): William Hatch, Cary Simon. "September 2006." Includes bibliographical references (p. 69-70). Also available in print.

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Sperring, T. P. "An experimental and numerical investigation of the heat transfer and thermal history of spray deposited tubular billets." Thesis, Swansea University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639094.

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This thesis is concerned with heat transfer phenomena in the spray deposition process. It is concerned with the deposition process as developed by Osprey Metals, Neath, UK. It focuses on the thermal history of tubular preform production. A former was constructed using the same dimensions as the tubular billet produced at Osprey Metals, and this was instrumented to measure heat transfer coefficients all over its surface. This heat transfer was measured using especially designed heat transfer meters which fitted into the former. The results from the experimental programme show that the heat transfer around the preform varies in a smooth curve suggesting that there is a Coanda effect present. Heat transfer was also highest closest to the preform substrate and the freshly deposited metal. FLUENT, a commercial computational fluid dynamics program, was used to model the fluid flow in the chamber. Both two and three dimensional models were built using body fitted coordinates. Discussion on the theory behind the package as well as details on the individual models used are presented. Results from this work are examined and compared to the results from the experimental programme. Good correlation was found between the three dimensional computation fluid dynamics and the results from the experimental programme with regard to the fluid flow in the process. Heat transfer trends were also well predicted in both two and three dimensional cases. Finally, two thermal network programs were written to describe the thermal history in the preform during deposition. These were used to calculate the thermal history of the entire tubular billet by looking at two dimensional planes perpendicular to each other. The experimental and CFD data was incorporated into this model through heat transfer coefficients. Results from this work give a thermal history of the billet from initialisation to a fully deposited tubular billet and this work showed the relative sensitivity of the thermal history with different physical parameters. It was shown that the substrate preheating and preparation were of prime importance in this respect.

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35

Moser, Martin. "Analyse und Dokumentation der umsatz- und qualitätsrelevanten Prozesse von Bern Billett /." Bern : [s.n.], 2006. http://www.wirtschaft.bfh.ch/uploads/tx_frppublikationen/mosemart2146.pdf.

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36

Durukan, Ilker. "Effects Of Induction Heating Parameters On Forging Billet Temperature." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608879/index.pdf.

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Induction heating is one of the efficient and modern technique for heating raw materials for hot forging process. The induction heating furnaces use electro-magnetic field to transfer energy to the metal workpiece and heat is generated inside the material. The magnetic field can be provided by using induction coil. The power supplied to induction coil, the moving speed of the billet that is called conveyor speed and the coil box hole diameter are the factors affecting the resultant temperature of the heated billet. In this study, AISI 1045 type steel billets with a diameter of Ø
30 mm and length of 100 mm have been heated in a particular induction heater. During heating, effects of different levels of power, conveyor speed and the coil boxes with different hole diameters are investigated. The 125 KW 3000 Hz induction heater which is available in METU-BILTIR Research and Application Center Forging Laboratory is used in experiments. The heating experiments are designed according to 23 Factorial Design of Experiment Method. Multiple linear regression technique is used to derive a mathematical formula to predict the temperature of the heated billet. A good correlation between the measured temperatures that are the results of different sets of induction heating parameters and the predicted temperatures that are calculated by using temperature prediction formula has been observed.

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37

Mogan, Jon Louis. "Transient billet heating model for a steel reheat furnace." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0007/MQ42668.pdf.

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38

Sondor, Anantha Shayana. "Analytical and numerical investigation of billet augmented hydrostatic extrusion." Ohio : Ohio University, 1989. http://www.ohiolink.edu/etd/view.cgi?ohiou1182520017.

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39

Kratz, Elizabeth A. "A qualitative analysis of the Navy's HSI billet structure." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://bosun.nps.edu/uhtbin/hyperion-image.exe/08Jun%5FKratz.pdf.

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Thesis (M.S. in Human Systems Integration)--Naval Postgraduate School, June 2008.
Thesis Advisor(s): Hatch, William D. "June 2008." Description based on title screen as viewed on August 25, 2008. Includes bibliographical references (p. 75-76). Also available in print.

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40

Bellamy, La Toya. "Initial billet assignments and the performance of Naval officers." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28292.

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41

Vesvrotte, Martine Guillemin. "Le Billet de loterie analyse du marché, politique marketing." Lille : A.N.R.T, 1985. http://catalogue.bnf.fr/ark:/12148/cb36105818v.

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42

Pouly, François. "Modélisation thermo mécanique d’un roulement à billes grande vitesse." Lyon, INSA, 2010. http://theses.insa-lyon.fr/publication/2010ISAL0105/these.pdf.

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La chaleur dégagée dans un palier à roulement fonctionnant à grande vitesse nécessite un refroidissement externe afin d’éviter la dégradation du lubrifiant et du mécanisme. La technologie actuelle consiste ainsi à injecter dans celui-ci un jet d’huile qui permet à la fois la lubrification des surfaces en contact mais également l’évacuation de la chaleur. La compréhension des mécanismes de lubrification nécessite donc de mener des investigations conjointes sur les pertes de puissance au sein du roulement et sur les échauffements correspondants. La perte de puissance associée à la traînée aérodynamique exercée par le brouillard d’huile sur les éléments roulants est extrêmement délicate à estimer du fait de la complexité des écoulements. Il existe ainsi un degré de liberté sur la manière d’aborder cette perte, qui historiquement a toujours été ajustée de manière à égaliser les pertes de puissance globales calculée et mesurée. Ce phénomène a permis de masquer la divergence d’opinions concernant la prise en compte ou non de la force de roulement hydrodynamique au contact bille/bague. Une méthode originale permettant de discriminer les différentes sources de chaleur est proposée, combinant les approches mécanique, thermique et aérodynamique. Il est ainsi démontré que les forces de roulement hydrodynamique et de traînée aérodynamique ne peuvent pas être négligées dans un roulement à billes grande vitesse. L’outil numérique développé s’avère performant et rapide pour modéliser le comportement thermo mécanique d’un roulement en régime stationnaire et transitoire. Des investigations sur un scénario d’interruption de la lubrification sont ainsi également réalisées. Ces aspects représentent une avancée technique dans la compréhension du rôle de l’huile tant comme lubrifiant que comme fluide caloporteur
Heat generation in high speed rolling element bearings needs external cooling in order to avoid the deterioration of the lubricant and the seizure of the mechanism. Current technology is to inject oil which lubricates contacting surfaces but also evacuates the generated heat. Then the understanding of lubrication mechanism deals with both power losses and thermal analyses. The power loss due to aerodynamic drag force acting on the rolling elements remains difficult to estimate due to the complex oil mist flow into the bearing. Historically it has been adjusted so that computed global power losses fit with experimental ones. It explains why nowadays there is still a discrepancy about taking into account or not hydrodynamic rolling traction forces at ball/race contacts. An original method is presented to discriminate the different heat sources by considering simultaneously mechanical, thermal and aerodynamical approaches. It is demonstrated that both aerodynamic drag forces and ball/race hydrodynamic rolling traction force cannot be neglected for high speed applications. The developed numerical tool appears to be fast and powerful to predict the steady state and unsteady state thermo mechanical behaviour of a rolling element bearing. Numerical investigations on oil shut-off are also presented. This work aims to provide a better comprehension of one of the most important aspects of tribology: the thermal effects in high speed rolling element bearings

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43

Adde, Alain. "Origine et développement du billet à ordre en France." Paris 2, 1990. http://www.theses.fr/1990PA020120.

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Le billet a ordre remonte aux dernieres annees du xviie siecle mais ses origines sont tres lointaines. Son origine proche demeure incertaine. Trois schemas de creation sont possibles. Le plus probable est aussi le moins juridique. Il semble tirer son droit de celui de la lettre de change mais si l'on considere qu'il est le successeur de la reconnaissance de dette sous seing prive entre commercants, il puisse en fait dans un patrimoine commun. Le rigueur de la loi sur les protets, l'informatique et les formes nouvelles des moyens de credit et de paiement conduisent a un deploiement des types d'effets de commerce mais cela se fait au detriment des garanties
The promissory note is born during the last years of the xviith century but it has very remote roots. Its near origin is still uncertain. Three patterns are possible for its creation, the most suitable has also the less juridical background. Its regulations seems to come from these which are ruling the bill of exchange, but as the promissory note is the successor of the ancient private acknowledgement of debt beetwen traders we try to show that their laws are common. The harshness of the law on protest and the new forms taken by the various means of credit and payment bring to a deployment of several kinds of promissory note but with reduced securities

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44

FitzPatrick, Eric L. "A study of the feasibility and benefits of converting certain fleet support community billets from military to civilian." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA346471.

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Thesis (M.S. in Management) Naval Postgraduate School, March 1998.
Thesis advisor(s): John E. Mutty, William R. Gates. "March 1998." Includes bibliographical references (p. 57). Also available online.

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45

Duren, Dennis Lee. "Cost/benefit analysis and job design for Naval Construction Force liaison officer billets on Marine Expeditionary Force staffs." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23598.

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Approved for public release; distribution is unlimited.
This thesis provides a cost/benefit analysis and job design for the placement of Naval Construction Force (NCF) Liaison Officer billets on each Marine Expeditionary Force (MEF) staff. The three NEFs are the largest, most capable form of a Marine Air-Ground Task Force (MAGTF). Each NEF has been authorized a billet for a Navy Civil Engineer Corps (CEC) Lieutenant as the NCF Liaison Officer. The NCF (or Seabees) have supported the Marine Corps with a wide range of advanced-base construction from the origin of the Seabees during World War II through the Persian Gulf War. Discussion of this support role and the organizational/command relationships between the NCF and the Marine Corps is provided. Discussion of the benefits and costs expected to be realized from those billets will lead to a proposed job design. This design of responsibilities attempts to optimize results from the billets. Job characteristics for work motivation for the officers assigned are also considered.

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46

Ziemba, David. "Application of an interactive computer model to analyze the distribution of U.S. Navy warfare specialists among generalist billets." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/43759.

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This thesis demonstrates the application of a user-interactive personnel flow forecasting model, FORECASTER, in analyzing the distribution (billet-fill requirements) of U.S. Navy warfare specialists among generalist billets. The development and implementation of the model as used to analyze multiple communities is outlined in detail. Three basic scenarios are utilized to demonstrate the model's flexibility and sensitivity: (1) The 'Status-quo', or present, distribution: (2) alternative policies with regards to adjustments to tour length; and (3) alternative guidance pertaining to transition probabilities. The results of these analyses demonstrate FORECASTER as a viable tool by which the complexities of multiple personnel community management can be investigated and alternatives considered.

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47

Lachhab, Touria. "Études des propriétés mécaniques d'empilements désordonnés de billes de gel." Phd thesis, Ecole Nationale des Ponts et Chaussées, 1994. http://tel.archives-ouvertes.fr/tel-00529715.

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Notre principale contribution à l'étude du matériau gel a été la mise au point d'un dispositif original de mesure directe de la pression osmotique dans les gels. Des expériences effectuées sur des gels cylindriques d'acide polyacrylique partiellement ionisés ont montré que la pression osmotique varie linéairement avec la concentration en contre ions en dessous du seuil de condensation. Ce résultat est conforme aux théories existantes. Le comportement, sous compression oedométrique, d'empilements lâches de billes de gel gonflées dans une solution de salinité donnée est non linéaire, et la caractéristique force-déformation peut être décrite par morceaux par une loi de puissance. Celle-ci présente trois régimes : un régime de consolidation décrit par un exposant de l'ordre de 1.6, comparable à l'exposant donné par la loi de Hertz. Dans le régime consolidé, le nombre de contacts augmente avec la déformation. Le comportement est alors gouverné par un exposant de l'ordre de 2.5, plus grand que l'exposant de Hertz. Enfin, apparaît un comportement fortement non linéaire décrit par un exposant de l'ordre de 3.5 : tous les contacts sont établis et le comportement est dominé par la contribution des particules fortement déformées. Lors des cycles de compression, l'hystérésis est principalement due à la dissipation visqueuse dans les billes sans expulsion de solvant. Sous compression isotrope générée au sein de l'empilement, contraint à occuper un volume constant, par variation de la taille des particules obtenue en faisant varier la salinité de la solution, le comportement de l'empilement est encore non linéaire avec le paramètre de contrôle de l'expérience. Le comportement observé s'apparente à un régime consolidé, décrit par un exposant supérieur à celui obtenu dans le même régime en compression oedométrique.

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Méallet-Renault, Rachel. "Caractérisation de billes de latex fluorescentes pour l'élaboration de nanocapteurs." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2000. http://tel.archives-ouvertes.fr/tel-00371478.

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Nous avons montré la faisabilité d 'une approche de capteur où les fonctions de détection et de signalisation sont séparées. Nous avons choisi comme supports lumineux des nanosphères fluorescentes. Elles servent de transducteurs. Nous avons exploré la modularité du capteur en essayant plusieurs molécules sondes adsorbées à la surface des billes. Nous avons montré que l'information entre la détection (sonde) et la signalisation (bille) est relayée par transfert d'énergie.

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Newell, Mark S. "Meeting contracting officer billet requirements in the United States Navy." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283559.

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50

Huguet, Marie Laure. "Étude de billes d'alginate de calcium recouvertes de polymère polycationique." Vandoeuvre-les-Nancy, INPL, 1994. http://www.theses.fr/1994INPL105N.

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L'encapsulation des produits biologiques est particulièrement intéressante pour préserver leur intégrité et permettre leur relargage de façon contrôlée. L'alginate, polysaccharide anionique, est souvent utilisé pour la microencapsulation. Il présente des propriétés de gélification en présence de cations divalents (Ca++, Mg++). La microencapsulation de molécules biologiques et de cellules dans des billes d'alginate de calcium présente l'avantage d'être très douce et de maintenir ainsi l'activité de ces produits. Cependant pour limiter le relargage du matériel encapsulé, il est parfois nécessaire d'établir une membrane à la surface de la bille par formation d'un complexe polyélectrolyte avec un polymère polycationique. Le chitosane, polysaccharide cationique naturel, ou le diéthylaminoethyl-dextrane peuvent donc être utilisés pour l'élaboration d'une membrane autour de la bille d'alginate de calcium. Deux techniques de production de billes d'alginate ont été testées, la méthode à l'extrusion et celle à l'émulsion, qui ont permis d'obtenir des billes d'alginate de calcium de diamètre moyen différent soit respectivement de 1mm et 70m. Nous avons étudié les propriétés de rétention de ces billes recouvertes d'une membrane polyélectrolyte vis à vis de différentes molécules, des protéines (hémoglobine, albumine de sérum bovin), des dextranes de masses molaires différentes, le benzène tetracarboxylate. Les conditions de formation de la membrane, pH et concentration de la solution de polymère polycationique et la nature du polycation ont une influence sur les propriétés de rétention de ces billes recouvertes d'une membrane. La nature des produits encapsulés à également une grande influence sur leur rétention. Leur taux de libération varie en fonction de leur masse molaire, leur conformation tridimensionnelle ainsi que de leur composition chimique

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Dissertations / Theses on the topic 'Billetes'

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