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Dissertations / Theses on the topic 'Pulque'
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Cúlhuac, Hernández Ernesto Carlos, and Campos Ángel Roberto Martínez. "ANALISIS DE LA CADENA PRODUCTIVA DEL PULQUE DEL ESTADO DE MÉXICO Y TLAXCALA." Tesis de Licenciatura, I. C. Agropec. y Rurales, 2013. http://ri.uaemex.mx/handle/20.500.11799/14315.
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Durante la historia de México ha existido una vasta diversidad de productos
alimenticios, algunos han desaparecido, otros lograron perdurar hasta nuestros
dias con gran dificultad, un claro ejemplo es la bebida alcohólica llamada pulque,
obtenida a partir de aguamiel extraído del maguey pulquero y sometido a un
proceso de fermentación; el consumo de esta bebida es tradicional en el centro del
país, principalmente en los Estados de Hidalgo, México, Puebla y Tlaxcala.
No obstante a pesar de ser aparentemente la misma bebida en cada uno de los
estados, existen diferencias marcadas entre ellos en los aspectos de superficie
sembrada, rendimiento de litros por hectárea, costo por litro y ganancias obtenidas
por esta actividad; a partir de estas diferencias es que se plantea el estudio de la
cadena productiva del pulque en los Estados de México y Tlaxcala, siendo el
primero el de mayor superficie plantada, pero el que recibe la menor cantidad de
ingresos en contraste con el segundo que recibe la mayor cantidad de ingresos en
una superficie cuatro veces menor (SIAP, 2010); para apoyar esta comparación se
utilizó el método Delphi que contempla la aplicación de cuestionarios a expertos
del tema (Scott, 2001) y el posterior procesamiento de los datos.
Al término del análisis de datos se identificaron las variables que determinan la
diferencia entre ambas cadenas mediante una tabla que concentra y señala los
contrastes de ambos estados y de la cual se generaron las conclusiones.
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García-Moya, Edmundo, and Park S. Nobel. "Leaf Unfolding Rates and Responses to Cuticle Damaging for Pulque Agaves in Mexico." University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/609137.
Full textAbstract:
Agave mapisaga and A. salmiana, which are widely cultivated in central Mexico for the fermented beverage pulque, have 7 to 11 leaves unfolding annually per plant. Such leaves can be 2 m in length with dry weights exceeding 1 kg, leading to estimated aboveground productivities of 25 to 26 metric tons ha⁻¹ yr⁻¹. To prevent theft of the cuticle from folded leaves of A. salmiana, which is used to wrap meat for steam cooking (termed "mixiote"), the distal one-third of the central spike of folded leaves is often intentionally cut off, which unfortunately depresses leaf unfolding for the next two years. However, making small holes in the central spike, which also renders the cuticle unusable for mixiote, does not significantly reduce the rate of leaf unfolding.
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Radilla, Rosas Norma Edith. "Impactos socioculturales de eventos y actitudes locales: "La Feria del Pulque" en Tepetlaoxtoc, México." Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2017. http://hdl.handle.net/20.500.11799/64938.
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Cortés, Beltrán Griselda, and Ramírez Saraí Martínez. "Estudio de factibilidad para una microempresa productora de helado frito con pulque de sabores." Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2013. http://hdl.handle.net/20.500.11799/99982.
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El desempleo que se vive actualmente por parte de los egresados de las universidades es un problema que se tiene que resolver; una alternativa de solución son las microempresas, como fuente de empleo.
En esta investigación se propondrán algunos puntos importantes para la idea de negocio, basada en la creación de una microempresa productora de helado frito con pulque de sabores.
Se pretende desarrollar una microempresa ya que es una forma de contribuir al desarrollo del Municipio porque se generara empleo y fuentes de ingresos; en base a los resultados que se obtendrán por medio de noticias, información del Instituto Nacional de Estadística y Geografía (INEGI), Diario Oficial de la Federación de la Secretaria de Economía y las estadísticas para el estudio de mercado del poblado del municipio de San Vicente Chicoloapán Estado de México determinaran el precio y la aceptación del helado frito con pulque de sabores así como la apertura.
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Rosas, Chávez Rodrigo. "Efecto del aguamiel-pulque y auxinas-citocininas en la inducción in vitro de PLBs en Phalaenopsis sp." Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2018. http://hdl.handle.net/20.500.11799/94271.
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Phalaenopsis es una orquídea apreciada a nivel mundial tanto en maceta como flor de corte. Sin embargo su reproducción natural es difícil debido a su lento crecimiento monopodial. Por ello, es necesario establecer nuevos protocolos de propagación in vitro para eficientar su multiplicación. El objetivo del presente trabajo fue inducir la formación de PLBs en Phalaenopsis sp. var. Dudu a partir de dos tipos de explantes: PLBs y secciones de hoja. Para los explantes de PLBs se evaluaron dos complejos orgánicos (CO): Aguamiel y Pulque en cuatro concentraciones (0, 10, 50 y 100 ml L-1), mientras que para las secciones de hoja se evaluó la combinación de dos Reguladores de Crecimiento Vegetal (RCV) en tres concentraciones (3, 4 y 5 mg L-1 de 2,4-D y 1, 2 y 3 mg L-1 de BA) y tres periodos de oscuridad (14, 21 y 28 días). Los resultados obtenidos de la inducción a partir de PLBs revelaron que el tratamiento con 10 ml L-1 del CO Pulque fue el mejor tratamiento con una media de 41.4 ± 5.7 PLBs por explante. Para el caso de los explantes de hoja, el tratamiento con 5 mg L-1 de 2,4-D y 2 mg L-1 de BA indujo la mayor media con 8.83 ± 1.29 PLBs por explante, mientras que los periodos de oscuridad no tuvieron un efecto estadísticamente significativo en la inducción de PLBs.La familia de las orquídeas está representada por aproximadamente 35 000 especies y numerosos híbridos, es considerada la más evolucionada y la más grande en el reino vegetal (Rodrigues et al., 2009). Phalaenopsis es una orquídea epífita, originaria del sureste de Asia, India, Indonesia y parte de Australia (Feria et al., 2007), se cultiva principalmente como flor de corte y como planta ornamental para decoración de interiores. En los Estados Unidos, Japón y muchos países europeos, no sólo la producción nacional, sino también su importación se incrementó rápidamente (Su y Hsu, 2003). En 2004 se estimó que en laboratorios de Alemania se produjeron de manera in vitro más de 31 millones de plantas (Sinha et al., 2010). Sin embargo, su crecimiento monopodial, es decir, a partir de una yema apical hace que se dificulte su propagación vegetativa, al tiempo que su reproducción sexual es afectada por la esterilidad en algunos de sus híbridos (Feria et al., 2007). La mayoría de las Phalaenopsis spp. cultivadas comercialmente son reproducidas por semillas, en consecuencia se expresa un amplio espectro de variabilidad fenotípica, con diferencias en la forma de crecimiento, tiempo de floración y hasta en las características florales. Se han desarrollado protocolos para la propagación in vitro tanto por embriogénesis somática como por organogénesis a partir de diferentes tejidos de la planta como hojas, ápices radiculares, ápices caulinares y secciones del escapo floral (Feria et al., 2007). 1 Muchos de estos protocolos se realizaron con el objetivo de obtener la formación de cuerpos protocórmicos a partir de los cuales se logra la regeneración de plantas, y con ello se pueden minimizar las dificultades que se presentan al emplear semillas. Los protocormos son cuerpos que se encuentran en un estado intermedio entre un embrión cigótico y un vástago, cuando estos cuerpos se forman sobre tejido reciben el nombre de cuerpos protocórmicos o Protocorm-like Bodies (PLBs por sus siglas en inglés) (Feria et al., 2007). Se sabe que el tipo de medio de cultivo, complejos orgánicos (CO) por ejemplo agua de coco, concentración y combinación de reguladores de crecimiento vegetal (RCV) y el tipo de tejido vegetal afectan de manera diferente a cada especie o hibrido de Phalaenopsis por lo cual es necesario realizar mayores ensayos para consolidar un protocolo eficiente en la clonación in vitro de esta especie.
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Toxqui, Garay María Aurea. ""El Recreo de los Amigos." Mexico City's Pulquerias during the Liberal Republic (1856-1911)." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194973.
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By 1909, Mexico City had a little more than 720,000 inhabitants, 250 schools, and almost 1,000 pulquerías -drinking establishments serving pulque, a fermented beverage made of the maguey plant. Today, pulquerías have almost disappeared; but just a century ago, people enjoyed gathering there. Since their beginnings in the 1530s, pulquerías became an integral part of the life of Mexico City’s inhabitants. These taverns offered pulque to take out, but far more importantly, a space where men and women drank, talked, danced, and enjoyed themselves as a part of their daily social life. These spaces represented an important place in the city’s lower-class culture and daily life. In this dissertation, I explore the social and cultural development of these businesses. I focus my discussion on the second half of the nineteenth century and the first decade of the twentieth century when there was a constant effort of making of Mexico a modern nation like England, France, or United States. Under the influence of liberalism, authorities increasingly sought to control the behavior of the population, especially in the public arena with the goal of creating hardworking and moral citizenry. They saw pulque as the core of social evils, and pulquerías, as centers where inebriated urban masses abandoned their daily routine, procrastinated, and fought. Consequently, authorities strictly regulated schedules, facilities, and all activities taking place in pulquerías. Patrons and owners resisted those regulations in different ways; especially customers, through their everyday practices, developed a vigorous and multi-faceted response to the processes of modernization. 13 Within these places, alcohol consumption fostered an environment of free interaction and gave men and women a platform in which they could demand and contest explanations about the behavior of their neighbors, partners, and coworkers. Their discussions and fights prove to be significant to the understanding of the regulation of the neighborhood dynamics as well as valves of escape during changing times. By analyzing the historical intersections of popular culture, nation building and modernization programs, and lower class responses to these reforms this dissertation contributes to the study of the cultural and social history of Mexico.
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Maher, Patrick. "The gods of pulque and their place in the histories, geography and cosmology of the Central Highlands of Mexico." Thesis, University of Essex, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336917.
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Piña, Sampedreño Arely. "Efecto de dos suplementos orgánicos y un sustrato orgánico en la respuesta de proliferación PLBs y regeneración in vitro ande plántalas de Phalaenopsis sp." Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2020. http://hdl.handle.net/20.500.11799/106089.
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Phalaenopsis son plantas con valor ornamental por sus delicadas y bellas flores de corte. La germinación de orquídeas tiene limitantes, ya que el endospermo está reducido en algunas especies, mientras que en otras se encuentra ausente. Una alternativa es utilizar la técnica in vitro para la micropropagación, en presencia de un medio de cultivo enriquecido con suplementos orgánicos que promuevan la multiplicación, el crecimiento y el desarrollo durante su cultivo in vitro. El objetivo del presente trabajo fue evaluar el efecto de dos suplementos orgánicos y un sustrato orgánico en la respuesta de proliferación de PLBs y regeneración in vitro de plántulas de Phalaenopsis sp. var. Dudu. Usando como suplementos orgánicos (SUO): agua de coco (AC) y pulque (PUL) y como sustrato orgánico (SO), heces del escarabajo del maní (Ulomoides dermestoides). Los explantes iniciales fueron PLBs obtenidos previamente in vitro a partir de semilla, los cuales, cinco PLBs sin disgregarse de Phalaenopsis sp. var. Dudu fueron considerados como un cluster con un diámetro aproximado de 5 mm, y cada cluster fue como un explante. Cinco explantes se cultivaron en cada recipiente de plástico con una capacidad de 500 ml, con 30 ml de medio de cultivo CP2 que contenía MS al 50 %, adicionado con 20 g L-1 de sacarosa, vitaminas MS, 4 g L-1 de agar, 0.5 g L-1 de carbón activado y suplementado con AC (100 ml L-1), y PUL (10 ml L-1), solos y en combinaciones con cinco concentraciones de SO (2.5, 5.0, 7.5 y 10 g L-1). Se probaron 20 tratamientos para evaluar su efecto en la tasa multiplicativa de PLBs, número de plántulas regeneradas, número y longitud de hojas, así como de raíces, en un arreglo trifactorial distribuidos al azar con tres repeticiones (20 x 3). Los resultados revelaron que el tratamiento cuatro con 100 ml L-1 de AC y 7.5 g L-1 de SO fue el mejor con un número promedio de 22.2 PLBs. Asimismo, en el tratamiento seis (testigo) se observó el mayor número de plántulas regeneradas con una media de 16.3.Orchidaceae es una de las familias más amplias de las angiospermas y taxonómicamente la más especializada de las monocotiledóneas. Comprende cerca de 700 géneros y 35,000 especies distribuidas en todo el mundo (Menezes et al., 2016). Las orquídeas tienen dos tipos básicos de crecimiento: simpodial, en las que el nuevo crecimiento se produce a partir de una yema axilar en sentido horizontal, y monopodial, en las que el nuevo crecimiento se produce a partir de una yema apical en sentido vertical, como es el caso de Phalaenopsis. Entre los principales países productores de orquídeas están: Brasil, China, Costa Rica, Estados Unidos, Filipinas, Indonesia, Países Bajos y Tailandia. Alrededor del 75 % de las orquídeas comercializadas a nivel mundial pertenecen al género Phalaenopsis (De la Cruz et al., 2017). Phalaenopsis es una orquídea epífita, sin seudobulbos, tienen raíces largas y carnosas, a menudo ramificadas, tallo corto, hojas con la capacidad de retener agua, su flor amplia de 7-10 cm de larga duración a veces perfumada (Aju 2009) originaria del sureste de Asia, India, Indonesia y parte de Australia (Rittershausen y Rittershausen, 2004). Estas representan uno de los grupos de plantas ornamentales más apreciados a nivel mundial por el colorido, forma y duración de sus flores, pero a diferencia de otros géneros de orquídeas, su sistema de reproducción es difícil ya que su crecimiento en condiciones naturales es lento, debido a la dependencia de una relación simbiótica con un hongo formador de micorriza (Murad, et al., 2010) lo cual ha dificultado su multiplicación vegetativa y la reproducción sexual se ha visto agravada por la presencia de altos índices de esterilidad en algunos de sus híbridos (Tirado et al., 2005). Varios factores son responsables en la extinción y amenaza de las orquídeas en todo el mundo, como la deforestación, fragmentación del habitad especialmente en regiones tropicales, el aumento del uso de fertilizantes, la explotación excesiva del suelo y la recolección masiva (Kaur y Bhutani, 2012). El desarrollo de técnicas de micropropagación en orquídeas ofrece múltiples ventajas como la reproducción de genotipos superiores, raros, estériles o libres de enfermedades. Particularmente el cultivo de semillas de orquídea in vitro ha permitido reducir los tiempos de producción de plántulas, ya que algunas especies pueden llegar a la madurez (producción de flores) en menos años (Menezes et al., 2016). El cultivo in vitro es una técnica que facilita la propagación de Phalaenopsis, ya que se lleva a cabo en condiciones asépticas, en presencia de una fuente de nutrimentos y en condiciones físicas controladas, lo que potencializa su capacidad de crecimiento (Flores-Hernández et al., 2017) y obtener grandes volúmenes de plantas con el fin de producir a gran escala para el comercio. No obstante, el éxito depende del tipo de explante a utilizar (Zhao et al., 2010). Estudios recientes han permitido la regeneración de plántulas a partir de tallos con yemas axilares (Feria et al., 2007), meristemos (Arditti y Ernst, 1993), segmentos nodales (Košir et al., 2004), fragmentos de hojas, botones florales (Tokuhara y Mii, 2001) y raíces (Park et al., 2003). Sin embargo, estos métodos son reportados como complicados e ineficientes (Salazar et al., 2013). Los medios y su formulación son muy importantes para maximizar el vigor de las orquídeas en condiciones de cultivo de tejidos, se requiere una disponibilidad equilibrada de nutrientes para un costo bajo, y así lograr protocolos sustentables en orquídeas (Ganasekaran et al., 2010). Desde hace algunos años los orquideólogos han desarrollado fórmulas nutricionales para la germinación aséptica de semillas de una gran variedad de orquídeas (Minea, 2004). Estas fórmulas generalmente contienen uno o más ingredientes de composición relativamente indefinida, como el agua de coco (Withner, 1959). Por otra parte, Arditti y Lawrence (1964), así como Anderson (1967), reportaron que cuando se usó agua de coco y homogeneizados de banana y tomate como suplementos para el medio de cultivo, mejoró el porcentaje de germinación de las semillas en una variedad de géneros de orquídeas. A partir de entonces se han reportado diversos estudios relacionados con la adición de suplementos orgánicos al medio de cultivo; sin embargo, la mayor parte de los autores se ha dedicado a evaluar el efecto sobre la germinación de las semillas (Minea, 2004), por lo que se tiene poca información en relación con los efectos sobre los procesos de desarrollo posteriores a la germinación, como el crecimiento o la formación de brotes y rizogénesis de las plántulas obtenidas (Arias-Hernández et al., 2006). Por lo tanto, el objetivo del presente estudio fue evaluar el efecto de dos suplementos orgánicos y un sustrato orgánico en la respuesta de proliferación de PLBs y regeneración in vitro de plántulas de Phalaenopsis sp. var. Dudu.
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Gorodi, Suzie Mei. "Pulse, pulse, somersault." AUT University, 2009. http://hdl.handle.net/10292/1006.
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This project explores notions of seeing and knowing, underpinned by performative and phenomenological fields of enquiry that relate this exploration to the sensate experience of the viewer. A specific interest considers ideas of embodied vision with an aim at generating events that vacillate in the bodies of the audience. A primary focus is on the arena of encounter as a multi-sensory experiential event, and within this context this project proposes a temporal and spatial framework for exploration. Studio methods develop a cinematic-body of video work negotiating performative practice involving video projection and temporality. Pivotal goals are to explore the significance of the ‘chiasm’ between seeing and knowing, raising questions about how humans see, and how humans make how they see matter. Therefore, this thesis project progresses along experimental approaches to video installation, particularly in relation to the phenomena of encounter, the viewer, and film experience. The central motivation of this video practice is aimed at corporeal affect in the body/s of the audience. This thesis project is constituted as 80% practice-based work accompanied by a 20% exegesis.
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Chytil, Pavel. "Detekce nemocí pomocí analýzy hlasu." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-233419.
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Tato disertační práce je zaměřena na analýzu řečového signálu za učelem detekce nemocí ovlivňujících strukturu hlasových orgánů, obzvláště těch, které mění strukturální character hlasivek. Poskytnut je přehled současných technik. Dále jsou popsány zdroje použitých nahrávek pro zdravé a nemocné mlučí. Hlavním učelem této disertační práce je popsat vypočetní postup k odhadu parametrů modelu hlasového zdroje, které umožní následnou detekci a klasifikaci nemocí hlasivek. Poskytujeme detailní popis analýzy řečových signálů, které mohou být odvozeny z parametrických modelů hlasivek.
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Ma, Jun. "Ultrafast Electron Transfer in Solutions Studied by Picosecond Pulse Radiolysis." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS023/document.
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L'interaction de particules énergétiques avec les résultats de l'eau dans l'excitation et l'ionisation des molécules d'eau. Le processus d'ionisation se rapporte à la génération de l'excès d'électrons détachés de leurs molécules parentes et laissant derrière le trou positive (notée H₂O•⁺). Cela se produit sur le calendrier d'une transition électronique ~ 10⁻¹⁵s. Les processus chimiques plus anciens de H₂O•⁺ et l'excès d'électrons vers autre question suivie de l'eau en vrac ionisants restent encore peu par rapport connu et constitue un sujet difficile dans la chimie de rayonnement. Dans ma thèse, les techniques de radiolyse d'impulsions picoseconde ont été utilisés pour observer la cinétique de la SO₄•⁻, H₂PO₄• dans de l'acide sulfurique très concentré et solutions d'acide phosphorique sur une large gamme de concentrations (de 1 mol L⁻¹ à l'acide pur). Les résultats expérimentaux montrent clairement que le radical secondaire de sulfurique (SO₄•⁻) et de l'acide phosphorique (H₂PO₄•) peuvent être formés par l'intermédiaire de deux mécanismes : détachement d'électrons direct par l'impulsion d'électrons (7 ps) et le transfert d'électrons ultra-rapide des solutés au radical cation de l'eau H₂O•⁺. La réactivité des espèces oxydantes fortes, H₂O•⁺ vers les solutés dans des solutions aqueuses très concentrées est quantitativement démontréThe interaction of energetic particles with water results in the excitation and ionization of water molecules. The ionization process refers to the generation of the excess electrons detached from their parent molecules and leaving behind the positive hole (denoted as H₂O•⁺). This occurs on the timescale of an electronic transition ~10⁻¹⁵ s. The earliest chemical processes of H₂O•⁺ and excess electron towards other matter followed water ionizing in bulk still remain relative little known and constitute a challenging subject in radiation chemistry. In my thesis, picosecond pulse radiolysis techniques were used to observe the kinetics of the SO₄•⁻, H₂PO₄• in highly concentrated sulfuric acid and phosphoric acid solutions over a large range of concentrations (from 1 mol L⁻¹ to neat acid). The experimental results showed clearly that the secondary radical of sulfuric (SO₄•⁻) and phosphoric acid (H₂PO₄•) can be formed via two mechanisms: direct electron detachment by the electron pulse (7 ps) and ultrafast electron transfer from the solutes to the radical cation of water H₂O•⁺. The reactivity of the strongest oxidizing species, H₂O•⁺ towards the solutes in highly concentrated aqueous solutions is quantitatively demonstrated
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Strayer, Jayson D. (Jayson Dee). "Underwater sound puluse generator." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40200.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 52-53).
by Jayson D. Strayer.
M.Eng.
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Dolan, John Eric. "Aspects of magnetic pulse compression and pulse sharpening." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46748.
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Pratt, Gill. "Pulse computation." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/14260.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1990.Includes bibliographical references (leaves 134-135).
by Gill Andrews Pratt.
Ph.D.
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Ferris, Morris Samuel A. "Pulse Patterns." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1398272266.
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Mercan, Hasan. "Nonuniform Pulse Repetition Interval Optimization For Pulse Doppler Radars." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12605619/index.pdf.
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In this thesis, a method of optimization of nonuniform pulse repetition interval for pulse Doppler radars is investigated. PRI jittering technique is used for the selection of inter-pulse intervals. An environment with white Gaussian noise and clutter interference is defined and applying generalized likelihood ratio test, a sufficient statistic function for the detection of the target is derived. The effect of jitter set selection on range and Doppler ambiguity resolution and clutter rejection is investigated. Jitter sets for Doppler ambiguity resolution are investigated by the minimization of the sufficient statistic function value at other estimated target velocities. Jitter sets for range ambiguity resolution are investigated by minimization of the number of ambigous hits at other estimated ranges. The clutter rejection properties of jitter sets are evaluated by defining a constraint function on zero velocity clutter rejection. The problems stated are solved using MATLAB with genetic algorithms.
It is observed that there is a trade off between Doppler ambiguity resolution and clutter rejection properties of jitter sets. Low jitter values are needed for good clutter rejection. The performance of jitter sets are optimized according to range ambiguity resolution and clutter rejection properties by defining cost functions. It is observed that good range ambiguity resolution and clutter rejection can be achieved by an optimized PRI jittering technique. Finally, the effects of quantization of Doppler filter coefficients and target returns using improvement factor as the performance criterion are evaluated.
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Wefers, Marc Michael. "Femtosecond optical pulse shaping and multiple-pulse femtosecond spectroscopy." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10597.
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Mercan, Hasan Supervisor :. Tanık Yalçın. "Nonuform pulse repetition interval optimization for pulse doppler radars." Ankara : METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12605619/index.pdf.
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Salissou, Yacoubou. "Détecteurs de radiation terahertz pulsée." Mémoire, Université de Sherbrooke, 2005. http://savoirs.usherbrooke.ca/handle/11143/4700.
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Dans ce mémoire, nous présentons une étude portant sur la détection de rayonnement terahertz (THz) à l'aide d'antennes photoconductrices et par électroabsorption dans les structures à puits quantiques. Nous présentons tout d'abord les résultats d'une étude exploratoire sur la technique de détection basée sur l'électroabsorption par effet Stark quantique. Dans cette étude, nous examinons le potentiel d'utilisation de cette technique et dégageons le type de structure à puits quantiques le plus adapté à la détection de rayonnement terahertz. Par la suite, nous présentons les résultats d'une étude de caractérisation d'une série d'antennes photoconductrices utilisées comme détecteur de rayonnement THz. Ces antennes ont été fabriquées sur substrat de GaAs semi isolant implanté. Le principe de la mesure consiste à utiliser le champ électromagnétique THz pour déplacer les photoporteurs générés par une impulsion optique sonde, et ainsi induire un photocourant qui dépend de l'amplitude instantanée de ce champ THz. Afin d'optimiser les performances de détection en termes de résolution temporelle et de sensibilité, il est important de réduire le temps de vie des photoporteurs tout en préservant une bonne mobilité électronique. La recherche du meilleur compromis nous a conduit à réaliser des études de l'effet des différents paramètres d'implantation (espèce chimique, dose et profondeur d'implantation). L'étude de l'effet de la forme géométrique de la région photosensible sur la sensibilité de détection sera également présentée. Finalement, des simulations de l'effet de la durée de vie des porteurs sur la largeur de bande de détection sont également présentées.
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Láznička, Pavel. "Laserové mikroobrábění." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231520.
Full textAbstract:
This thesis deals with lasers, their general theory and application. Then a theoretical part describes laser micromachining and engraving. Experimental part of thesis deals with several experiments performed by powered fibre laser which is not primarily intended for the field of micromachining. Experiments were mainly evaluated by several types of microscopes where the amount of removed material was appraised. By particular experiments removed material was in accordance with used working parameters of laser and a significant role plays machining material. It emerges from the experiments that for the field of laser micromachining and engraving shorter pulses are more suitable (minimal pulse duration was 1 ms in experiment) and it is connected even with a way of removing material. Applied powered laser can be used for micromachining in specific fields of production.
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Grün, Alexander. "Nonlinear pulse compression." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/284879.
Full textAbstract:
In this thesis I investigate two methods for generating ultrashort laser pulses in spectral regions which are ordinarily difficult to achieve by the existing techniques. These pulses are specially attractive in the study of ultrafast (few femtosecond) atomic and molecular dynamics.
The first involves Optical Parametric Amplification (OPA) mediated by four-wave-mixing in gas and supports the generation of ultrashort pulses in the Near-InfraRed (NIR) to the Mid-InfraRed (MIR) spectral region. By combining pulses at a centre wavelength of 800 nm and their second harmonic in an argon-filled hollow-core fibre, we demonstrate near-infrared pulses, peaked at 1.4 µm, with 5 µJ energy and 45 fs duration at the fibre output. The four-wave-mixing process involved in the OPA is expected to lead carrier-envelope phase stable pulses which is of great importance for applications in extreme nonlinear optics. These NIR to MIR pulses can be used directly for nonlinear light-matter interactions making use of its long-wavelength characteristics.
The second method allows the compression of intense femtosecond pulses in the ultraviolet (UV) region by sum-frequency mixing two bandwidth limited NIR pulses in a noncollinear phasematching geometry under particular conditions of group-velocity mismatch. Specifically, the crystal has to be chosen such that the group velocities of the NIR pump pulses, v1 and v2 , and of the sum-frequency generated pulse, vSF, meet the following condition, v1 < vSF < v2. In case of strong energy exchange and an appropriate pre-delay between the pump waves, the leading edge of the faster pump pulse and the trailing edge of the slower one are depleted. This way the temporal overlap region of the pump pulses remains narrow resulting in the shortening of the upconverted pulse. The noncollinear beam geometry allows to control the relative group velocities while maintaining the phasematching condition. To ensure parallel wavefronts inside the crystal and that the sum-frequency generated pulses emerge untilted, pre-compensation of the NIR pulse-front tilts is essential. I show that these pulse-front tilts can be achieved using a very compact setup based on transmission gratings and a more complex setup based on prisms combined with telescopes. UV pulses as short as 32 fs (25 fs) have been generated by noncollinear nonlinear pulse compression in a type II phasematching BBO crystal, starting with NIR pulses of 74 fs (46 fs) duration. This is of interest, because there is no crystal that can be used for nonlinear pulse compression at wavelengths near 800 nm in a collinear geometry. Compared to state-of-the-art compression techniques based on self-phase modulation, pulse compression by sum-frequency generation is free of aperture limitation, and thus scalable in energy. Such femtosecond pulses in the visible and in the ultraviolet are strongly desired for studying ultrafast dynamics of a variety of (bio)molecular systems.En esta tesis he investigado dos métodos para generar pulsos láser ultracortos en regiones espectrales que son típicamente difíciles de lograr con las técnicas existentes. Estos pulsos son especialmente atractivos en el estudio de la dinámica ultrarrápida (pocos femtosegundos) en átomos y moléculas. La primera técnica implica Amplificación Paramétrica Óptica (OPA) mediante mezcla de cuatro ondas en fase gaseosa y soporta la generación de pulsos ultracortos desde el Infrarrojo-Cercano (NIR) hasta la región espectral del Infrarrojo-Medio (MIR). Mediante la combinación de pulsos centrados a una longitud de onda de 800 nm y su segundo armónico en una fibra hueca rellena de argón, hemos demostrado a la salida de la fibra la generación de pulsos en el NIR, centrados a 1.4 µm, con 5 µJ de energía y 45 fs de duración. Se espera que el proceso de mezcla de cuatro ondas involucrado en el OPA lleve a pulsos con fase de la envolvente de la portadora estables, ya que es de gran importancia para aplicaciones en óptica extrema no lineal. Estos pulsos desde el NIR hasta el MIR se pueden utilizar directamente en interacciones no-lineales materia-radiación, haciendo uso de sus características de longitud de onda largas. El segundo método permite la compresión de pulsos intensos de femtosegundos en la región del ultravioleta (UV) mediante la mezcla de suma de frecuencias de dos pulsos en el NIR limitados en el ancho de banda en una geometría de ajuste de fases no-colineal bajo condiciones particulares de discrepancia de velocidades de grupo. Específicamente, el cristal debe ser elegido de tal manera que las velocidades de grupo de los pulsos de bombeo del NIR, v1 y v2, y la del pulso suma-de-frecuencias generado, vSF, cumplan la siguiente condición, v1 < vSF < v2. En el caso de un fuerte intercambio de energía y un pre-retardo adecuado entre las ondas de bombeo, el borde delantero del pulso de bombeo más rápido y el borde trasero del más lento se agotan. De esta manera la región de solapamiento temporal de los impulsos de bombeo permanece estrecha, resultando en el acortamiento del impulso generado. La geometría de haces no-colineales permite controlar las velocidades de grupo relativas mientras mantiene la condición de ajuste de fase. Para asegurar frentes de onda paralelos dentro del cristal y que los pulsos generados por suma de frecuencias se generen sin inclinación, es esencial la pre-compensación de la inclinación de los frente de onda de los pulsos NIR. En esta tesis se muestra que estas inclinaciones de los frentes de onda se pueden lograr utilizando una configuración muy compacta basada en rejillas de transmisión y una configuración más compleja basada en prismas combinados con telescopios. Pulsos en el UV tan cortos como 32 fs (25 fs) se han generado mediante compresión de pulsos no-lineal no-colineal en un cristal BBO de ajuste de fase tipo II, comenzando con pulsos en el NIR de 74 fs (46 fs) de duración. El interés de este método radica en la inexistencia de cristales que se puedan utilizar para la compresión de impulsos no-lineal a longitudes de onda entorno a 800 nm en una geometría colineal. En comparación con las técnicas de última generación de compresión basadas en la automodulación de fase, la compresión de pulsos por suma de frecuencias esta libre de restricciones en la apertura de los pulsos, y por lo tanto es expandible en energía. Tales pulsos de femtosegundos en el visible y en el ultravioleta son fuertemente deseados en el estudio de dinámica ultrarrápida de una gran variedad de sistemas (bio)moleculares.
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Lindblom, Adam. "Inductive Pulse Generation." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6699.
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Cihangir, Salih. "Powder pulse plating." Thesis, University of Leicester, 2018. http://hdl.handle.net/2381/40974.
Full textAbstract:
Electroplating is a common method of obtaining metallic coatings on a surface. Generally, the metal salt is introduced into solution and a direct current is applied to the material that is to be coated. In this thesis, an alternative approach is investigated, namely the metal is introduced onto the metal surface as a powder and a pulsed current is applied to firstly dissolve some of the powder and the polarity is reversed so that the metal is then deposited. This fuses the powder to itself and to the substrate. In the current study, deep eutectic solvents were used as the electrolytes and two metals were chosen; zinc and copper. Initially the dissolution and deposition of the pure metals were investigated. It was found that far from being simple dissolution and deposition processes insoluble films were formed on the electrode surface during both deposition and dissolution for zinc and during dissolution for copper. Powder pulse plating was successfully demonstrated if the current pulse characteristics were kept within a window of size and duration which avoided these insoluble films. It was found that large metallic particles could be used when the substrate was held in a horizontal orientation and small particles were best when the electrode was held vertically. For both metals it was demonstrated that super-efficient deposition could be obtained (Faradaic current efficiency in the cathodic pulse > 100%). It was also shown that composite materials could be produced by mixing inert particles with the metallic powder.
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McCormick, Martin (Martin Steven). "Digital pulse processing." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78468.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 71-74).
This thesis develops an exact approach for processing pulse signals from an integrate-and-fire system directly in the time-domain. Processing is deterministic and built from simple asynchronous finite-state machines that can perform general piecewise-linear operations. The pulses can then be converted back into an analog or fixed-point digital representation through a filter-based reconstruction. Integrate-and-fire is shown to be equivalent to the first-order sigma-delta modulation used in oversampled noise-shaping converters. The encoder circuits are well known and have simple construction using both current and next-generation technologies. Processing in the pulse-domain provides many benefits including: lower area and power consumption, error tolerance, signal serialization and simple conversion for mixed-signal applications. To study these systems, discrete-event simulation software and an FPGA hardware platform are developed. Many applications of pulse-processing are explored including filtering and signal processing, solving differential equations, optimization, the minsum / Viterbi algorithm, and the decoding of low-density parity-check codes (LDPC). These applications often match the performance of ideal continuous-time analog systems but only require simple digital hardware. Keywords: time-encoding, spike processing, neuromorphic engineering, bit-stream, delta-sigma, sigma-delta converters, binary-valued continuous-time, relaxation-oscillators.
by Martin McCormick.
S.M.
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Nighthill, Abigail Stokes. "Taking nature's pulse." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/104026.
Full textAbstract:
Thesis: S.M. in Comparative Media Studies, Writing, Massachusetts Institute of Technology, Department of Humanities, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (page 22 ).
People have taken delight in nature throughout human history, but more recently the work of the natural historian has become more like that of the scientist. Using methods and tools of science, today's naturalists can record nature with precision-and through this, learn more about it. Ecologists now pay heed to the often-forgotten sense of hearing. The Tropical Ecology Lab at University of Puerto Rico, San Piedras, blurs the lines between natural history and science. An array of remote microphones collects sounds from the forests and wetlands, and researchers use computers to analyze the soundscapes themselves.
by Abigail Stokes Nighthill.
S.M. in Comparative Media Studies, Writing
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Tomás, Bruno Manuel Coelho. "Magnetic pulse welding." Master's thesis, Faculdade de Ciências e Tecnologia, 2010. http://hdl.handle.net/10362/4890.
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Hall, William L. "The In Pulse." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1225066283.
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Nguyen, Dat. "Dynamic feedback pulse shaping for high power chirped pulse amplification system." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5826.
Full textAbstract:
The topic of this proposal is the development of high peak power laser sources with a focus on linearly chirped pulse laser sources. In the past decade chirped optical pulses have found a plethora of applications such as photonic analog-to-digital conversion, optical coherence tomography, laser ranging, etc. This dissertation analyzes the aforementioned applications of linearly chirped pulses and their technical requirements, as well as the performance of previously demonstrated parabolic pulse shaping approaches. The experimental research addresses the topic of parabolic pulse generation in two distinct ways. First, pulse shaping technique involving a time domain approach is presented, that results in stretched pulses with parabolic profiles with temporal duration of 15 ns. After pulse is shaped into a parabolic intensity profile, the pulse is compressed with DCF fiber spool by 100 times to 80 ps duration at FWHM. A different approach of pulse shaping in frequency domain is performed, in which a spectral processor based on Liquid Crystal on Silicon technology is used. The pulse is stretched to 1.5 ns before intensity mask is applied, resulting in a parabolic intensity profile. Due to frequency to time mapping, its temporal profile is also parabolic. After pulse shaping, the pulse is compressed with a bulk compressor, and subsequently analyzed with a Frequency Resolved Optical Gating (FROG). The spectral content of the compressed pulse is feedback to the spectral processor and used to adjust the spectral phase mask applied on the pulse. The resultant pulse after pulse shaping with feedback mechanism is a Fourier transform, sub-picosecond ultrashort pulse with 5 times increase in peak power. The appendices in this dissertation provide additional material used for the realization of the main research focus of the dissertation. Specification and characterization of major components of equipment and devices used in the experiment are present. The description of Matlab algorithms that was used to calculate required signals for pulse shaping are shown. A brief description of the Labview code used to control the spectral processor will also be illustrated.Ph.D.
Doctorate
Physics
Sciences
Physics
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Tan, Tuan Choon. "Multi-pulse coding of speech signals using adaptive pulse allocation technique." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47682.
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Arrizon, Javier. "Etude de la structure des fructanes d'Agave tequilana et de nouvelles fructanases d'origine microbienne." Thesis, Toulouse, INSA, 2011. http://www.theses.fr/2011ISAT0022/document.
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Le Mexique se caractérise par la présence sur son territoire de nombreuses espèces d’agave qui peuvent être cultivées ou non. En particulier l’Agave tequilana Weber var. azul a une grande importance économique, car elle constitue la principale matière première pour l’élaboration de la tequila. Les agaves durant leur développement, qui dure plusieurs années, accumulent des réserves de sucres constitués par des fructanes. Actuellement, l’optimisation de l’hydrolyse des fructanes d’agave est surtout importante pour l’industrie de la tequila. Elle permettra d’améliorer les rendements d’extraction des sucres. La méthode classique d’hydrolyse des fructanes est constituée principalement d’un procédé de cuisson des agaves crus. L’utilisation d’enzymes spécifiques pour réaliser ce même procédé d’hydrolyse suscite un récent intérêt industriel, parce qu’il permettrait une réduction de la consommation d’énergie. Les fructanes d’agave présentent des structures complexes, les résidus de fructose sont reliés par des liaisons osidiques de type β (2→1) et β (2→6), et la structure est fortement branchée. Il est nécessaire de comprendre les changements de structure des fructanes en fonction de l’étape de croissance des plantes, pour connaître la variabilité naturelle du substrat utilisé pour l’hydrolyse. D’autre part, il est important de découvrir de nouvelles enzymes susceptibles d’hydrolyser de manière spécifique les fructanes d’agave, et les caractériser biochimiquement, pour arriver à une meilleure connaissance de l’intéraction enzyme-substrat qui permettra le développement de nouvelles applications industrielles possibles pour les fructanes d’Agave tequilana. Dans ce travail, la première partie est consacrée à la détermination de la composition en sucres solubles et à la caractérisation de la structure des fructanes d’Agave tequilana présents dans des plantes d’âges différents. Puis, dans la deuxième partie, la purification et la caractérisation biochimique d’une fructanase isolée d’une souche de levure Kluyveromyces marxianus obtenue à partir du procédé de fermentation du mezcal (boisson d’agave distillée) a été étudiée. L’activité de cette enzyme a été comparée à un cocktail enzymatique commercial le fructozyme®. Finalement, dans une troisième partie, des levures isolées de la fermentation de différents types de mezcal ont été criblées et ont permis la sélection de souches capables de dégrader spécifiquement les fructanes d’AgaveMexico has a high diversity of Agave plants, which could be cultivated or not. The most economically important is Agave tequilana Weber var. azul, because it is the raw material for the tequila elaboration process. As agaves grow, they accumulate reserve sugars as fructans. Actually, optimizing the A. tequilana fructans hydrolysis, in order to increase the sugar yield, is important to the tequila industry. Traditionally, agaves are cooked to hydrolyze the fructans. However, using enzymes for hydrolysis may reduce energy consumption and increase sugar yields.The fructans of A. tequilana have a complex structure, composed of fructose chains with β (2→1) and β (2→6) linkages with branching points. It is important to understand how the structure of these molecules changes as a function of plant growth, in order to know the natural variability of the substrate that must be hydrolysed. It is also necessary to find new enzymes for the efficient hydrolysis of A. tequilana fructans, and to characterize them biochemically for a better understanding of the enzyme-substrate interaction.The present work has three parts that focuses separately on each of these needs: First, characterizing the water soluble carbohydrates and the structure of the A. tequilana fructans as a function of the plant’s growth (age). Second, purifying and biochemically characterizing a fructanase from Kluyveromyces marxianus yeast isolated from the fermentation of mezcal, and comparing it to a commercial cocktail (Fructozyme®). Third, a screening of enzymes from yeasts used to ferment mezcal, in order to determine their ability to hydrolyze A. tequilana fructans
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El, Omar Abdel Karim. "Études des réactions primaires en solutions par la radiolyse pulsée picoseconde." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00931405.
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Après la découverte des rayonnements ionisants et leurs effets chimiques, il était important d'étudier et de comprendre les mécanismes de formations des radicaux libres et des produits moléculaires caractérisés par leurs courtes durées de vie. Ceci a encouragé les groupes de recherches à développer leurs outils pour qu'ils puissent réaliser ces études. De nos jours la radiolyse impulsionnelle se manifeste comme un outil fondamental permettant de sonder les effets chimiques ainsi que les mécanismes réactionnels dans le milieu étudié.Le laboratoire de Chimie Physique d'Orsay " LCP " est un laboratoire interdisciplinaire abritant la plateforme " ELYSE " qui est un centre de cinétiques rapides. Grâce au laser femtoseconde et à l'accélérateur d'électrons picoseconde, nous avons eu la possibilité, dans le domaine de la radiolyse, de remonter en temps, en étudiant les effets chimiques dans un milieu réactionnel, jusqu'à ~ 5 ps.Nous nous sommes intéressés par les réactions primaires induites par les rayonnements ionisants en solution et ELYSE représentait l'outil principal pour ces études. Les résultats obtenus concernent :- La détermination directe du rendement radiolytique du radical hydroxyle " HO* " en fonction du temps à l'échelle de la picoseconde ;- Etude de l'effet direct du rayonnement ionisant sur les solutions aqueuses concentrées ainsi que la vérification de la réaction de transfert d'électron ultrarapide entre le soluté et le trou positif " H2O*+ " issu lors de la radiolyse de l'eau ;- Etude à température ambiante de la réaction de transfert d'électron entre un électron solvaté (donneur d'électron) et un soluté organique (accepteur d'électron) en milieu visqueux ;- Etude à température ambiante de la solvatation de l'électron dans l'éthylène glycol et dans le propan-2-ol.
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McClelland, Robert S. "Spacecraft attitude control system performance using pulse-width pulse-frequency modulated thrusters." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA291803.
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Laurain, Alexandre, Declan Marah, Robert Rockmore, John G. McInerney, Jorg Hader, Perez Antje Ruiz, Stephan W. Koch, Wolfgang Stolz, and Jerome V. Moloney. "High power sub-200fs pulse generation from a colliding pulse modelocked VECSEL." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/625500.
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We present a passive and robust mode-locking scheme for a Vertical External Cavity Surface Emitting Laser (VECSEL). We placed the semiconductor gain medium and the semiconductor saturable absorber mirror (SESAM) strategically in a ring cavity to provide a stable colliding pulse operation. With this cavity geometry, the two counter propagating pulses synchronize on the SESAM to saturate the absorber together. This minimizes the energy lost and creates a transient carrier grating due to the interference of the two beams. The interaction of the two counter-propagating pulses in the SESAM is shown to extend the range of the modelocking regime and to enable higher output power when compared to the conventional VECSEL cavity geometry. In this configuration, we demonstrate a pulse duration of 195fs with an average power of 225mW per output beam at a repetition rate of 2.2GHz, giving a peak power of 460W per beam. The remarkable robustness of the modelocking regime is discussed and a rigorous pulse characterization is presented.
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Matuszek, Martin. "Měření pulzu z videa." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2014. http://www.nusl.cz/ntk/nusl-236098.
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The aim of the Master's thesis was to study contemporary methods for human pulse detection from standard video and suggest a method, which can be used to detect the pulse. Approaches of detecting miniature changes between frames of a video are presented. Position changes of the feature points or changes in colour of some part of an image are detected. It capitalize on the fact that those changes are caused by the pulse of blood. The method for color changes magnification is selected as a base for pulse detector. Face regions of interest are analyzed to detect frequency of changes of intensity between frames. 1D signal is gained and its analysis leads to heart rate. Approach to create heat map of frequency changes is also presented.
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Deconda, Keerthi. "Fault tolerant pulse synchronization." Thesis, [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2331.
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East, Christine Elizabeth. "Fetal intrapartum pulse oximetry /." [St. Lucia, Qld.], 2006. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19387.pdf.
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Conrad, Theodore Judson. "Miniaturized pulse tube refrigerators." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41108.
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Pulse tube refrigerators (PTR) are robust, rugged cryocoolers that do not have a moving component at their cold ends. They are often employed for cryogenic cooling of high performance electronics in space applications where reliability is paramount. Miniaturizing these refrigerators has been a subject of intense research interest because of the benefits of minimal size and weight for airborne operation and because miniature coolers would be an enabling technology for other applications. Despite much effort, the extent of possible PTR miniaturization is still uncertain.
To partially remedy this, an investigation of the miniaturization of pulse tube refrigerators has been undertaken using several numerical modeling techniques. In support of these models, experiments were performed to determine directional hydrodynamic parameters characteristic of stacked screens of #635 stainless steel and #325 phosphor bronze wire mesh, two fine-mesh porous materials suitable for use in the regenerator and heat exchanger components of miniature PTRs. Complete system level and pulse tube component level CFD models incorporating these parameters were then employed to quantitatively estimate the effects of several phenomena expected to impact the performance of miniature PTRs. These included the presence of preferential flow paths in an annular region near the regenerator wall and increased viscous and thermal boundary layer thicknesses relative to the pulse tube diameter. The effects of tapering or chamfering the junctions between components of dissimilar diameters were also investigated.
The results of these models were subsequently applied to produce successively smaller micro-scale PTR models having total volumes as small as 0.141 cc for which sufficient net cooling was predicted to make operation at cryogenic temperatures feasible.
The results of this investigation provide design criteria for miniaturized PTRs and establish the feasibility of their operation at frequencies up to 1000 Hz with dimensions roughly an order of magnitude smaller than those that have recently been demonstrated, provided that challenges related to their regenerator fillers and compressors can be addressed.
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Chin, Roger S. "Femtosecond laser pulse compression." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/29799.
Full textAbstract:
Once the Spectra-Physics Femtosecond Laser System had arrived, it had to be characterized.
For further pulse compression, various techniques had to be considered. The best of these were chosen considering our needs and limitations.
First, the Spectra-Physics Femtosecond Laser System is described and its 616 nm laser pulses are characterized. By using an autocorrelation technique based on the nonlinear optical characteristics of a potassium dihydrogen phosphate (KDP) crystal and assuming a particular intensity pulse shape (such as that described by a symmetric exponential decay), the pulse width (full width at half maximum) could be obtained. Assuming a pulse shape described by a symmetric exponential decay function, the "exponential" pulse width was measured to be 338 ± 6 fs. The nominal average power of the 82-MHz modelocked pulse train was 225 mW. The "exponential" pulse energy was 2.7 nJ with a peak pulse power of 2.8 kW.
Theoretical calculations for fibre grating pulse compression are presented. Experimentally,
I was able to produce 68 ± 1 fs (exponential) pulses at 616 nm. The average power was 55 mW. The "exponential" pulse energy was 0.67 nJ with a peak power of 3.4 kW. The pulse compressor consisted of a 30.8 ±0.5 cm fibre and a grating compressor with the effective grating pair distance of 103.8 ± 1 cm.
Various techniques were considered for further pulse compression. Fibre-grating pulse compression and hybrid mode locking appeared to be the most convenient and least expensive options while yielding moderate results.
The theory of hybrid mode locking is presented. Experimentally, it was determined that with the current laser system tuned to 616 nm, DODCI is better than DQOCI based
on pulse shape, power, stability and expense. The recommended DODCI concentration is 2-3 mmol/l. The shortest "exponential" pulse width was 250 fs. The average power was 185 mW. The exponential pulse energy was 2.3 nJ with a peak pulse power of 2.6 kW.
An attempt to increase the bandwidth of the laser pulse by replacing the one-plate birefringent plate with a pellicle severely limited the tunability of the dye laser and introduces copious noise.
Attempts to reduce group velocity dispersion (responsible for pulse broadening) with a grating compressor was indeterminate, but did result in a slightly better pulse shape. Interferometric autocorrelation is recommended for such a study.
An increase or decrease from the nominal power output of the pulse compressor showed a decrease in pulse compression.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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劉藹欣 and Oi-yan Elizabeth Lau. "Wrist pulse contour analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B35273525.
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Collins, Timothy. "Active sonar pulse design." Thesis, University of Birmingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311535.
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Millasseau, Sandrine. "Arterial pulse wave analysis." Thesis, King's College London (University of London), 2003. https://kclpure.kcl.ac.uk/portal/en/theses/arterial-pulse-wave-analysis(5002b38b-53de-4c76-af89-db21c08fea68).html.
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Radnor, Samuel Benjamin Philip. "The ultra-wideband pulse." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/1312.
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Since the birth of mode-locking the temporal duration of optical pulses has radically diminished. In parallel to this, bandwidths have grown so large that almost entire frequency octaves are present in today’s few-cycle pulses. This thesis investigates the character of ultra-wideband pulses in nonlinear environments. Because of the growth in optical bandwidths, traditional definitions and propagation models break down, requiring newer more accurate numerical techniques. A novel approach capturing the uni-directionality of pulses is presented in the form of Gvariables by combining the electric and magnetic field descriptions. These G-variables have the advantage of both an accurate spectral representation and a reduced computational overhead, making them significantly more efficient than existing direct Maxwell solvers. Such approaches are particularly important where large propagation distances and/or transverse dimensions are concerned. Pseudo-spectral techniques play a key role in the success of these wideband models enabling sub-cycle dynamics to be studied. One such phenomenon is Carrier Wave Shocking (CWS), where the optical carrier undergoes self-steepening in the presence of third-order nonlinearity. This process is carefully studied, focussing on the effect of dispersion and the feasibility of its physical realisation. The process is then generalised to arbitrary nonlinear order, where the quadratic form finds potential applications in High Harmonic Generation (HHG). Shock detection schemes are also developed, and agree with analytical solutions in the dispersionless regime. To fully characterise few-cycle pulses, the absolute Carrier Envelope Phase (CEP) must be known. A novel 0 − f self-referencing scheme relying on wideband interference is investigated. By applying robust frequency domain definitions a proposal is made to convert this scheme into one that determines absolute CEP. The scheme maps the level of spectral interference to absolute CEP using numerical simulations.
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Bosman, Gurthwin Wendell. "Ultrashort optical pulse characterization." Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/764.
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Lau, Oi-yan Elizabeth. "Wrist pulse contour analysis." Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25085463.
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Lotti, Antonio. "Pulse shaping and ultrashort laser pulse filamentation for applications in extreme nonlinear optics." Palaiseau, Ecole polytechnique, 2012. http://pastel.archives-ouvertes.fr/docs/00/66/56/70/PDF/tesi.pdf.
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Cette thèse traite de l'étude numérique des propriétés et des applications des impulsions spatio-temporellement couplées, paquets d'ondes coniques et filaments laser, dans les processus fortement non-linéaires, comme la génération d'harmoniques d'ordre élevé. Nous étudions la redistribution de l'énergie au sein de ces paquets d'ondes en propagation linéaire et non-linéaire. Le flux d'énergie constitue un diagnostic des couplages spatio-temporels que nous avons appliqué à des résultats expérimentaux réels. Nous analysons l'évolution spectrale des filaments dans un gaz et nous obtenons les conditions pour la génération d'impulsions de quelques cycles dans le spectre UV. Nous étudions la génération d'harmoniques d'ordre élevé par des ondes coniques ultra-courtes. En particulier, nous montrons comment leurs propriétés de propagation influencent le champ généré dans la région X-UV. Nous étudions aussi l'interférence des différents chemins quantiques correspondant aux trajectoires électroniques. Enfin, nous obtenons la forme des faisceaux d'Airy stationnaires dans le régime non-linéaire. Pour chaque sujet, nous présentons des résultats expérimentaux qui ont motivé nos travaux ou ont été motivés par nos simulationsThis thesis deals with numerical studies of the properties and applications of spatio-temporally coupled pulses, conical wavepackets and laser filaments, in strongly nonlinear processes, such as harmonic generation and pulse reshaping. We study the energy redistribution inside these wavepackets propagating in gases and condensed media, in the linear and nonlinear regime. The energy flux constitutes a diagnostic for space-time couplings that we applied to actual experimental results. We analyze the spectral evolution of filaments in gases and derive the conditions for the generation of ultrashort pulses in the UV range. We study high harmonic generation in a gas from ultrashort conical wavepackets. In particular, we show how their propagation properties influence the harmonic output. We also study the interference of different electron trajectories. Finally, we derive the shape of stationary Airy beams in the nonlinear regime. For each topic, we present experimental results that motivated our works or were motivated by our simulations
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Jarrahi, Khameneh Mojtaba. "Intensification du mélange par advection chaotique pulsée." Nantes, 2010. https://archive.bu.univ-nantes.fr/pollux/show/show?id=33a6dbf5-3e54-4105-a044-5387a8986d1b.
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Le but de cette étude est d'étudier l'amélioration du mélange par superposition d'une dépendance temporelle, sous la forme d'une pulsation, à un écoulement de Dean alterné où les trajectoires des particules fluides sont spatialement chaotiques. La dépendance temporelle de l'écoulement dans les conduites courbes peut générer des écoulements secondaires - composées de deux cellules contra-rotatives (cellules Dean) dans un régime stationnaire - plus complexe. Cette modification de l'écoulement secondaire qui se traduit par des gradients de vitesse plus forts, augmente les étirements et les repliements; et donc le mélange. La configuration chaotique étudiée dans ce travail est composée d’une série de six coudes alternés de 90°. Lors du passage d’un écoulement pulsé (stationnaire+sinusoïdal) dans cette géométrie, les champs de vitesse de l'écoulement secondaire sont mesuré en utilisant la vélocimétrie par images de particules (PIV) pour différentes conditions de pulsation. Pour éviter les effets de réfraction de lumière lors des mesures de PIV, un canal en forme de T est installé en aval du coude d’étude. Les expériences sont réalisées pour une large gamme de nombres de Reynolds stationnaire 420≤Rest≤1000, de rapports d’amplitude de vitesse 1≤(β=Umax,sin/Ust)≤4 et de paramètres de fréquence 8,37≤(α=r0(ω/ν)0,5)≤24,5. Les effets de chaque paramètre (Rest, β et α) sur le mélange transversal sont discutés en comparant les valeurs de vorticité adimensionnelles (|ζP|/|ζS|) et les taux de déformation transversale adimensionnels (|εP|/|εS|) au cours d’une période d’oscillation complète. Les résultats montrent que β≥2 et α≤15 sont les conditions favorables de pulsation pour l'amélioration du mélange. En plus, dans certaines conditions de pulsation, les centres de cellules visitent une zone (dans la section du canal) 9 fois plus grande que celle d’un cas stationnaireThe purpose of this study is to investigate mixing enhancement by superposition of a temporal dependence, in the form of a pulsation, on a twisted pipe flow where the trajectories of fluid particles are spatially chaotic. In the steady case, the secondary flow in a curved tube is composed of two counter-rotating cells (Dean cells), however, the temporal dependence of the flow can make this structure more complex. This modification of the secondary flow which results in stronger velocity gradients enhances stretching and folding (the main mechanism of mixing). Here, the chaotic configuration is composed of six alternating 90° curved pipes. When a pulsating (steady+sinusoidal) flow passes through this geometry, the velocity field is measured by particle image velocimetry (PIV) for different pulsating conditions. To obviate light-refraction effects during PIV measurements, a T-shaped end channel is installed at the exit of the curved pipe. Experiments are carried out for the steady Reynolds numbers range 420≤Rest≤1000, velocity component ratios 1≤ (β = Umax,sin / Ust) ≤ 4 and frequency parameters 8. 37≤(α=r0(ω/ν)0. 5)≤24. 5. The effects of each parameter (Rest, β and α) on transverse mixing are discussed by comparing the dimensionless vorticity (|ζP|/|ζS|) and dimensionless transverse strain rates (|εP|/|εS|) during a complete oscillation period. The results show that β ≥ 2 and α ≤ 15 are favorable pulsating conditions for mixing enhancement. Moreover, in some pulsation conditions, the cells’ centers visit a zone (in the flow cross-section) 9 times larger that that of the steady case
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Kathuria, Amit D. "Optical pulse generation at high pulse rates for electro-optical analog to digital converters /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426072.
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Buck, Nicholas V. "Minimum vibration maneuvers using input shaping and pulse-width, pulse frequency modulated thruster control." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA325615.
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Thesis (Degree of Aeronautical and Astronautical Engineer) Naval Postgraduate School, December 1996.Thesis advisor(s): B.N. Agrawal. "December 1996." Includes bibliographical references (p. 149-150). Also available online.
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Souron, Jean-Baptiste. "Régénération de la pulpe dentaire par ingénierie tissulaire : mise au point d’une «pulpe équivalente»." Thesis, Paris 5, 2013. http://www.theses.fr/2013PA05T059/document.
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La pulpe dentaire est sujette à des lésions sévères faisant suite à une carie dentaire ou à un traumatisme. La thérapeutique conventionnelle préconisée alors est le traitement endodontique, qui consiste en l’exérèse de la totalité de la pulpe dentaire et le comblement de l’espace pulpaire par un matériau inerte. Ce traitement induit une fragilisation de la dent et une plus grande susceptibilité aux infections. Au cours de ce travail, nous avons mis au point une solution alternative, en proposant le remplacement de la pulpe dentaire lésée par une « pulpe équivalente » constituée de cellules souches mésenchymateuses de la pulpe ensemencées dans une matrice de collagène. Nous avons testé ce substitut pulpaire au travers d’un modèle de pulpotomie de la molaire chez le rat, à savoir l’exérèse de la totalité du parenchyme de la chambre pulpaire et conservation du réseau vasculaire radiculaire, où nous avons implanté des « pulpes équivalentes ». Notre objectif étant notamment de déterminer le devenir des cellules souches pulpaires implantées dans la dent grâce à l’imagerie nucléaire, dans ce contexte de développement d’une thérapie cellulaire. Les cellules ont été marquées à l’111Indium-oxine préalablement à leur implantation. Nous avons montré que le marquage n'avait pas d'incidence sur la viabilité et la prolifération des cellules pulpaires. Le suivi du signal s’est fait par tomographie d'émission monophotonique, couplée à un scanner spécifique du petit animal (NanoSPECT/CT, Bioscan), hebdomadairement pendant 3 semaines. Nous avons mis en évidence que l'intensité du signal SPECT était directement liée à l'intégrité des cellules, puisque que les matrices implantées avec des cellules marquées puis lysées par choc isotonique présentaient une diminution rapide de l’intensité du marquage. Grâce à la sensibilité de la méthode d’imagerie choisie, nous avons montré l’absence de diffusion majeure des cellules dans la circulation sanguine à partir du site d'implantation, ce qui pourrait constituer un risque de minéralisation ectopique lié à l’implantation de cellules souches mésenchymateuses. Par ailleurs, l’étude par histologie des processus de réparation et régénération de la pulpe dans les dents de rat a mis en évidence une prolifération abondante de cellules de type fibroblastique au sein des matrices, ainsi que la présence de nombreux vaisseaux et de nerfs dans la matrice cellularisée et à proximité. Ces résultats, non observés dans les matrices implantées avec des cellules lysées, suggéraient donc une fonctionnalité du tissu reconstruit et suggéraient que les cellules pulpaires implantées favorisaient une néovascularisation rapide de la pulpe équivalente, vraisemblablement en induisant un recrutement de cellules endothéliales à partir du réseau vasculaire radiculaire résiduelThe dental pulp is prone to severe injuries following a tooth decay or trauma. Conventional recommended therapy is the endodontic treatment, which consists in the removal of all of the dental pulp and filling of the pulp space with an inert material. This treatment leads to a weakening of the tooth and a greater susceptibility to infection.In this work, we have developed an alternative solution, proposing the replacement of the injuried dental pulp by an " pulp equivalent " consisting of mesenchymal stem cells from the pulp seeded in a collagen matrix . We tested this pulp substitut through a model of the molar pulpotomy in rats, ie. the removal of the entire parenchyma of the pulp chamber and preservation of the root vascular network and implantation of the pulp equivalent. Our aim was to determine the fate of pulp stem cells implanted in the tooth by nuclear imaging in the context of developing a cell therapy. The cells were labeled with 111Indium - oxine prior to their implantation. We have shown that the labelling had no effect on the viability and proliferation of pulp cells. The signal tracking was done by single photon emission tomography , coupled with a specific small animal scanner ( NanoSPECT / CT , Bioscan ) weekly for 3 weeks. We demonstrated that the intensity of SPECT signal was directly related to the integrity of the cells, since the lysed labeled cells by isotonic shock showed a rapid decrease in the intensity of labeling . Due to the sensitivity of the chosen imaging method , we have shown the absence of major diffusion cells into the bloodstream from the site of implantation, which could result in a risk of ectopic mineralization related to the implementation of mesenchymal stem cells.Furthermore, the study by histology repair processes and regeneration of the pulp in teeth rat showed abundant proliferation of fibroblast-like cells within the matrix , and the presence of numerous vessels and nerves in matrix cellularized. These results , not observed in the matrices implanted with lysed cells, thus suggesting a feature of the reconstructed tissue and suggested that the pulp cells implanted favored a rapid neovascularization equivalent pulp, presumably by inducing the recruitment of endothelial cells from the residual root vascular network
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Qian, Xin. "Flow field investigation in pulse 1 motor of a two-pulse solid rocket motor." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03122009-040826/.
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