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Sample records for al desgaste deslizante

  1. Comportamiento al desgaste de fundiciones tipo “silal”

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    Blázquez, V.

    2010-12-01

    Full Text Available The tribological and mechanical properties of five cast-iron with different contents of carbon and silicon have been studied.Wear tests according ASTMG99 “Standard test method for wear testing with a pin-on-disk apparatus” and Brinell hardness measurements were carried out in every alloy. These results were related to microstructure, composition and casting processes of the cast irons.

    Es este trabajo se han estudiado las propiedades tribológicas y mecánicas de cinco fundiciones con distintos contenidos de carbono y silicio. Cada fundición ha sido sometida a ensayos de dureza Brinell, y ensayos de resistencia al desgaste, según la norma ASTMG99, “Standard test method for wear testing with a pin-on-disk apparatus”. Se han correlacionado los resultados obtenidos para estos ensayos con la microestructura, la composición y el proceso de colada de cada una de las fundiciones.

  2. Mecanismos de desgaste en refractarios de colada continua asociados al efecto Marangoni

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    Brandaleze, E.

    2005-12-01

    Full Text Available Nozzle wear during continuous casting process is caused by physical and chemical reasons and also by refractory quality. A post mortem study on a sample of Al2O3 - graphite nozzle with a ZrO2 insert allows to identify the present wear mechanisms. Different cyclic stages are carried out due to recurrent changes of interfacial tension and fluid convection. When the surface tension promote the refractory wetting by the steel, graphite of the nozzle surface is lost. Then, grains of ZrO2 and of Al2O3 are dissolved by slag contact. This type of wear is associated with the Marangoni effect. Light and electronic microscopy was used to observe the refractory structure and by a cathodoluminiscence technique phases transformations under process conditions are determined.

    Las buzas sumergidas se erosionan durante el proceso de la colada continua, debido a causas físicas, químicas y a la calidad del refractario. El estudio post mortem de una buza de Al2O3 -grafito con inserto de ZrO2 permite identificar los mecanismos de desgaste presentes, que ocurren por etapas debido a cambios cíclicos de tensión interfacial y convección de fluidos. Cuando la tensión superficial favorece la mojabilidad del refractario por el acero, la buza pierde grafito de la superficie. Luego, los granos de ZrO2 y de Al2O3 se disuelven al ser mojados por la escoria. Este desgaste está asociado al efecto Marangoni. Se observa la microestructura mediante microscopía óptica y electrónica y, por catodoluminiscencia, se determinan las transformaciones de fases ocurridas en condiciones de proceso.

  3. Resistencia al desgaste abrasivo de recubrimientos producidos por proyección térmica para aplicaciones navales

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    Gutiérrez Quintero, Wilder

    2015-01-01

    El presente trabajo estudia la resistencia al desgaste abrasivo de dos tipos de recubrimientos a base níquel. El primero, Metaceram 23075 con agregados cerámicos de carburo de tungsteno y cobalto WC/Co y el segundo, Nitec 10224 con adiciones de hierro, boro y silicio; aplicados sobre los sustratos de fundición gris y bronce fosforado, mediante la técnica de proyección térmica a la llama. En la primera etapa se muestra la construcción y puesta a punto del equipo para ensayos de desgaste abrasi...

  4. EFECTO DEL PRECALENTAMIENTO Y LA SEVERIDAD DE TEMPLE SOBRE LA RESISTENCIA AL DESGASTE ADHESIVO DEL ACERO AUSTENÍTICO AL MANGANESO

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    OSCAR FABIÁN HIGUERA COBOS

    2010-01-01

    Full Text Available En este trabajo de investigación se estudió el efecto del precalentamiento y la severidad de temple sobre la resistencia al desgaste adhesivo del acero austenítico al manganeso ASTM A 128 grado C. El material se sometió a ciclos térmicos de temple y revenido con y sin precalentamiento con el fin de evaluar su influencia sobre la resistencia al desgaste. Posteriormente el material fue sometido a prueba según norma ASTM G83 y se determinó que el acero Austenítico al manganeso, es un material que presenta una microestructura metaestable en condiciones estables y no debe ser sometido a tratamiento térmico de revenido a altas temperaturas debido que favorece la descomposición de esta a ferrita (fase blanda de los acero y por ende disminuye su resistencia al desgaste.

  5. Propiedades mecánicas bajo compresión y resistencia al desgaste abrasivo de piezas gruesas de caucho acrilonitrilo

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    Sandra Milena Velásquez-Restrepo

    2015-09-01

    Full Text Available Se estudió la variación de las propiedades mecánicas bajo compresión uniaxial y el desgaste abrasivo en la sección transversal de piezas gruesas de caucho acrilonitrilo (NBR reforzadas con negro de humo, teniendo en consideración que en este tipo de piezas las propiedades obtenidas durante la vulcanización no son homogéneas, debido a la baja difusividad térmica de los cauchos. Se realizaron ensayos de desgaste abrasivo en seco, buscando identificar la relación entre la resistencia al desgaste abrasivo y las propiedades mecánicas en compresión, como el módulo elástico y la dureza. Se evaluaron muestras en estado de entrega tras el proceso de vulcanización, luego expuestas al ambiente durante tres meses y, posteriormente, envejecidas en una cámara UV. El envejecimiento ambiental rigidiza los materiales estudiados, pero disminuye la resistencia al desgaste del material proveniente del núcleo de las piezas. El envejecimiento UV disminuyó el módulo elástico, pero su efecto sobre la resistencia al desgaste depende del estado de envejecimiento previo. La dureza no presentó una relación directa ni con el módulo elástico ni con la resistencia al desgaste, por lo cual no puede usarse como propiedad para la selección de cauchos NBR sometidos a desgaste abrasivo. La información obtenida permite generar criterios para el diseño de componentes basados en este tipo de cauchos.

  6. Aumento de la resistencia al desgaste de aperos mediante la aplicación del recargue superficial por soldadura automática

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    Elvis López B.; Ciro Iglesias C.; Amado Cruz C.; Miguel Herrera S.; Omar González C.

    2007-01-01

    En el siguiente trabajo se evalúa el aumento de la resistencia al desgaste abrasivo de las superficies de trabajo de aperos para la labranza de suelos, luego de aplicar el recargue superficial por el método de soldadura automática por arco sumergida (SAAS), utilizando para ello un fundente cerámico obtenido a partir de la reconstitución de la escoria del propio proceso. Se realizan mediciones de macrodureza, microdureza y resitencia al desgaste, se determina además el índice de desga...

  7. Resistencia al desgaste de recubrimientos Bi/NbC producidos con el sistema sputtering con magnetrón desbalanceado

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    Ardila Rodríguez, Laura Angélica

    2013-01-01

    En este trabajo se produjeron películas nano estructuradas de NbC, Bi y bicapas Bi/NbC sobre acero M2 y 316L mediante la técnica Sputtering con magnetrón desbalanceado, y se evaluó su resistencia frente al desgaste por medio del ensayo pin on disc, la adherencia con una prueba de rayado y la resistencia a la corrosión de las películas depositadas sobre los sustratos 316L mediante técnicas electroquímicas. La microestructura de los recubrimientos se analizó mediante Difracción de rayos X, M...

  8. Respuesta al Desgaste de un Material de Aluminio Reforzado con Circonia Response to wear of an Aluminum Material Reinforced with Zirconia

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    Rosalba Fuentes

    2006-01-01

    Full Text Available Se desarrolló un material compuesto aluminio-circonia por metalurgia de polvos. Los polvos de circonia fueron sintetizados por sol-gel, se mezclaron con polvo de aluminio, se compactaron y se sinterizaron. El tamaño del polvo de aluminio utilizado fue menor a 100 micras. La circonia tuvo como material precursor al n-propóxido de circonio. Se prepararon varias mezclas con ambos polvos, utilizando tres proporciones de circonia de 1%, 3% y 5% en peso. Se aplico una compactación de 58 KN y se sinterizó a 610°C. Posteriormente las piezas fueron sometidas a pruebas de desgaste con objeto de analizar su respuesta. El desgaste se realizó en una máquina de pin-en-disco, con velocidad de 320 rpm y presión de desgaste 9 KN por un período de dos horas. Las pruebas de desgaste muestran el comportamiento tribológico del material compuesto observándose un au>mento de resistencia al desgaste cuando el porcentaje en peso de circonia se incrementa.An aluminum-zirconia composite was developed using powder metallurgy. Zirconia powder was synthesized by a sol-gel method, mixed with aluminum powder, and was compacted and sinterized. The particle size of the aluminum powder utilized was less than 100 microns. The precursor material of zirconia was an n-propoxide of zirconium. Different proportions of zirconia were used in three mixtures at 1%, 3% and 5% by weight. The mixtures were compacted at 58KN and were sinterized at 610°C. Subsequently, the pieces were subjected to wear resistance tests to determine their resistance. The wear test was carried out in a pin-in-disk machine at a speed of 320 rpm and load of 9 KN for a period of two hours. The wear resistance tests showed the tribologic behavior of this composite showing an increase in wear resistance when the weight percentage of zirconia increases.

  9. Diseño de un observador y un controlador de velocidad de un motor DC por modos deslizantes

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    Jesse Mauricio Beltrán Soto

    2014-07-01

    Full Text Available En este artículo se presenta una estructura de estimación y control de estados mediante modos deslizantes para un modelo lineal. Se presenta un sistema mecánico de un Motor DC, al cual se le diseñaran un observador y un controlador deslizante de primer y segundo orden. Los resultados se comparan con un diseño de un PID. Los dos diseños se prueban ante cambios de referencia, perturbaciones y ruido.

  10. Relación microestructura resistencia al desgaste de recubrimientos duros ricos en cromo y tungsteno aplicados por soldadura electrica (SMAW)

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    Lisys Margarita León Sevilla; Juan Carlos Gutierrez Pineda; Alejandro Toro

    2004-01-01

    Se comparó la microestructura y resistencia a la abrasión de recubrimientos duros depositados por soldadura sobre placas de acero estructural ASTM A36. Se utilizaron cinco electrodos comerciales, dos de bajo cromo, dos de alto cromo aplicados en una y dos capas y uno rico en tungsteno depositado en una capa La resistencia al desgaste fue evaluada en una máquina de rueda de caucho y arena seca construida según la norma ASTM G65-80. Como material abrasivo se utilizaron partículas de...

  11. Estudio tribológico de aceros austeníticos tipo Hadfield: influencia del manganeso en su respuesta frente al desgaste

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    Camba, C.

    2010-12-01

    Full Text Available This study analyzes the wear behavior of austenitic Hadfield steels with different manganese contents (4 to 6% of manganese. The tribological analysis has been carried out by pin on disk tests according to ASTMG99-05 standard. The results have been related to the hardness and to the microstructure of every sample. The wear resistance of these steels depends on the hardness of the material and is very influenced by the type and distribution of the precipitates.

    En este estudio se analiza la respuesta frente al desgaste de aceros austeníticos tipo Hadfield, en función del contenido de manganeso, partiendo de aceros con proporciones dentro del intervalo del 4 al 6 % de manganeso. El análisis tribológico se ha realizado mediante ensayos pin on disk, según norma ASTM G99-05, y los resultados obtenidos se han relacionado con la dureza y con la microestructura de cada muestra determinándose que, para este tipo de aceros, la resistencia al desgaste no sólo depende de la dureza del material sino que se ve muy influida por el tipo y distribución de precipitados existentes.

  12. Mecanismos de desgaste en refractarios de colada continua asociados al efecto Marangoni

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    Brandaleze, E.

    2005-01-01

    Nozzle wear during continuous casting process is caused by physical and chemical reasons and also by refractory quality. A post mortem study on a sample of Al2O3 - graphite nozzle with a ZrO2 insert allows to identify the present wear mechanisms. Different cyclic stages are carried out due to recurrent changes of interfacial tension and fluid convection. When the surface tension promote the refractory wetting by the steel, g...

  13. Efecto del tratamiento térmico posterior sobre la resistencia al desgaste por deslizamiento de un recubrimiento base níquel depositado por HVOF

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    Cadenas, P.

    2007-02-01

    Full Text Available In the present research, a nickel base coating was deposited on an AISI 1020 substrate by using high velocity oxy-fuel technique (HVOF. The coating was subsequently post heat -treated by means of an oxyacetylene flame. For the conditions evaluated in the present study, it was found that the CTT coating has 1,15 better wear resistance for the smaller level of the applied load and nearly 50 times for the highest level of the applied load when compared to the STT coatings. These results have been attributed to a better distribution of the hard phases, better cohesion between particles and an increase in hardness, as consequence of the post heat treatment process. A severe wear regime was found for all the samples since the wear rates presented values which were higher than 1·10-5 mm3/m. For the CTT coatings, the wear mechanism was mainly due to the adhesion and oxidation phenomena, meanwhile for the steel counterpart mechanisms such oxidation, grooving and three body abrasion were observed.

    En el presente trabajo, se depositó un recubrimiento base níquel sobre un acero AISI 1020 por la técnica de termorrociado de alta velocidad que utiliza oxígeno como combustible (High Velocity Oxygen Fuel - HVOF y, posteriormente, fue tratado térmicamente mediante llama oxiacetilénica. Para las condiciones evaluadas en este estudio, se encontró que el recubrimiento CTT tiene desde 1,15 veces más resistencia al desgaste, para el menor nivel de carga aplicada y mayor velocidad de deslizamiento y, hasta 50 veces más resistencia al desgaste para el mayor nivel carga aplicada y mayor velocidad de deslizamiento, comparado con el recubrimiento STT. Estos resultados se atribuyeron a una mejor distribución de las fases endurecedoras, una mejor cohesión entre partículas y un aumento en la microdureza del recubrimiento, como consecuencia del tratamiento térmico posterior. El régimen de desgaste presente en todas las muestras fue severo, ya que las

  14. Resistencia al desgaste de recubrimientos de bronce al aluminio producidos con técnica de proyección térmica//Wear resistance of aluminum bronze coatings produced by thermal spray

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    Dayan Carolina Cárdenas-Feria

    2015-09-01

    Full Text Available Se estudió la resistencia al desgaste adhesivo de recubrimientos de bronce al aluminio depositados con la técnica de proyección térmica por llama sobre bronce fosforado SAE 62. Los recubrimientos fueron fabricados variando las presiones parciales de los gases de combustión, oxígeno y acetileno. El material utilizado fue caracterizado estructuralmente mediante difracción de rayosX (X-ray diffraction, XRD y el estudio morfológico mediante microscopía electrónica de barrido (Scanning electron microscopy, SEM. La resistencia al desgaste adhesivo de los recubrimientos se determinó por medio del ensayo de bola sobre disco, utilizando como bola una esférica de acero 100Cr6. Los resultados obtenidos permiten establecer que los recubrimientos proyectados con una presión de oxigeno de 78 psi y una presión de acetileno de 8 psi presentan la mejor resistencia al desgaste en comparación a los tratamientos producidos. El modo de falla de desgaste en los recubrimientos producidos es discutido en esta investigación.Palabras clave: desgaste abrasivo y adhesivo,  proyección térmica,  recubrimientos.______________________________________________________________________________AbstractWe studied the adhesive wear resistance of aluminum bronze coatings deposited by thermal spray on phosphor bronze SAE 62 substrates. The coatings were deposited by varying the partial pressures of the combustion gases: oxygen and acetylene. The structural characterization was made through X-ray diffraction (XRD and the morphological analysis was performed by scanning electron microscopy (SEM. The adhesive wear resistance of the coatings was determined by the bole on disc test using a spherical ball made of steel 100Cr6 and with a diameter of 6 mm. The results obtained show that the coating projected with an oxygen pressure of 78 psi and an acetylene pressure of 8 psi have the better wear resistance compared with the substrate and the others treatments deposited

  15. Resistencia al desgaste de recubrimientos de bronce al aluminio producidos con técnica de proyección térmica//Wear resistance of aluminum bronze coatings produced by thermal spray

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    Dayan Carolina Cárdenas-Feria; Liz Karen Herrera-Quintero; Jhon Jairo Olaya-Florez

    2015-01-01

    Se estudió la resistencia al desgaste adhesivo de recubrimientos de bronce al aluminio depositados con la técnica de proyección térmica por llama sobre bronce fosforado SAE 62. Los recubrimientos fueron fabricados variando las presiones parciales de los gases de combustión, oxígeno y acetileno. El material utilizado fue caracterizado estructuralmente mediante difracción de rayosX (X-ray diffraction, XRD) y el estudio morfológico mediante microscopía electrónica de barrido (Scanning electron m...

  16. Resistencia al desgaste de recubrimientos Fe-Nb-Cr-W, Nb, AISI 1020 y AISI 420 producidos por proyección térmica por arco eléctrico

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    López-Covaleda, E. A.

    2013-10-01

    Full Text Available The commercial materials 140MXC (with iron, tungsten, chrome, niobium, 530AS (AISI 1015 steel and 560AS (AISI 420 steel on AISI 4340 steel were deposited using thermal spray with arc. The aim of work was to evaluate the best strategy abrasive wear resistance of the system coating-substrate using the following combinations: (1 homogeneous coatings and (2 coatings depositing simultaneously 140MXC + 530AS and 140MXC + 560AS. The coatings microstructure was characterized using Optical microscopy, Scanning electron microscopy and Laser confocal microscopy. The wear resistance was evaluated through dry sand rubber wheel test (DSRW. We found that the wear resistance depends on the quantity of defects and the mechanical properties like hardness. For example, the softer coatings have the biggest wear rates and the failure mode was characterized by plastic deformation caused by particles indentation, and the other hand the failure mode at the harder materials was grooving. The details and wear mechanism of the coatings produced are described in this investigation.Mediante proyección térmica de arco eléctrico fueron depositados tres materiales comercialmente conocidos como: 140MXC (a base de hierro, wolframio, cromo y niobio, 530AS (acero AISI 1020 y 560AS (acero AISI 420, sobre acero AISI 4340. Con el objetivo de evaluar la mejor estrategia para incrementar la resistencia al desgaste abrasivo, los recubrimientos fueron depositados de dos formas: (1 monocapas homogéneas de cada material y (2 recubrimientos depositando con alambres disimiles de 140MXC + 530AS y 140MXC + 560AS. Los recubrimientos fueron caracterizados microestructuralmente mediante Difracción de rayos X, Microscopía óptica, Microscopía láser confocal y Microscopía electrónica de barrido. La evaluación de la resistencia al desgaste abrasivo se realizó mediante ensayo con arena seca y rueda de caucho (DSRW. Se encontró que la resistencia al desgaste depende entre otras de las

  17. Dinámica hamiltoniana y control por modos deslizantes del Péndulo de Furuta

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    Francisco Javier Ibargüen; Jairo Andrés Morales; John Alexander Moreno; Jaiber Evelio Cardona; Pablo Andrés Muñoz

    2009-01-01

    En este artículo se analiza la dinámica hamiltoniana para un tipo de sistema no lineal subactuado, aplicado particularmente al Péndulo de Furuta. Se aplica una estrategia de control no lineal a partir de los modos deslizantes y moldeo de energía potencial, que permite con una sola ley de control elevar y sostener el Péndulo en su posición vertical. Este experimento fue implementado en la planta mencionada, la cual fue diseñada y construida como un modelo experimental para la línea de investig...

  18. Influencia del contenido de silicio y el tratamiento térmico en la resistencia al desgaste de fundiciones blancas al cromo en condiciones de rápida solidificación

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    Goyos, L.

    2012-08-01

    Full Text Available The influence of silicon content and heat treatment on microstructure, abrasive and dry friction wear resistance of a 3 % C, 12 % Cr cast iron, under fast solidification conditions is studied. The fast solidification condition diminishes the carbide volume and the silicon content increases their dispersion and finesses. All matrixes obtained were perlitics, whit different finesses. No intermediate transformation products were noticed. Hardness had little variation. Austenization treatment show little affectivity, with tendency to increase wear in reference to as cast and maintenance treatments. Behavior under dry friction and abrasive wear were similar under test conditions applied whit more influence of carbide morphology in the abrasive wear conditions.

    Se estudia la influencia del silicio y el tratamiento térmico sobre la microestructura y la resistencia al desgaste abrasivo y por fricción seca de una fundición con 3 % C y 12 % Cr, obtenida en condiciones de rápida solidificación. La rápida solidificación disminuye el volumen de carburos, la finura y dispersión de éstos aumentan con el incremento del silicio. Todas las muestras presentaron matrices perlíticas, variando en finura con el tratamiento. No se apreciaron productos de transformación intermedios. Las durezas tuvieron poca variación. Los tratamientos de austenización mostraron poca efectividad, con tendencia a desgastes más elevados que en estado bruto de colada y con tratamiento de mantenimiento. Los comportamientos ante la abrasión y la fricción seca en las condiciones ensayadas fueron similares. Se evidenció alta influencia de la morfología de los carburos en el desgaste abrasivo.

  19. Nitruración gaseosa a elevada temperatura de la aleación Ti6Al4V para mejorar su resistencia al desgaste

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    King, Eleanor

    2000-12-01

    Full Text Available TiN coatings have been successfully produced on Ti6Al4V alloy by gas nitriding in order to modify surface properties. Several characteristics of the coatings relevant to their applications in total joint replacement have been studied. Wear resistance and hardness were improved dramatically for nitrided samples compared with those un-nitrided. Substrate adhesion of the coating was studied by means of a three point bend test system. Characterisation of the TiN layer was carried by optical microscopy, SEM and XRD. Vickers hardness values up to 700 were obtained.

    Mediante nitruración gaseosa a elevada temperatura de la aleación Ti6Al4V se han obtenido capas de nitruro de titanio que mejoran sus características superficiales. Con vistas a la aplicación como biomaterial se ha estudiado el incremento de dureza, la resistencia al desgaste y la adherencia de dichas capas al substrato. Se ha diseñado un sistema de medida de la adherencia de la capa nitrurada al metal base mediante flexión controlada en puente de carga. La caracterización de los constituyentes de las capas obtenidas se ha realizado mediante difracción de rayos X, metalografía óptica y SEM. Se ha logrado obtener unas capas de nitruro de titanio con durezas superiores a los 700 Vickers, que confieren al material una buena resistencia al desgaste.

  20. Efecto del porcentaje de refuerzo frente al desgaste en compuestos de matriz metálica sinterizados con descarga luminiscente anormal

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    Pérez-Velásquez, Sandra

    2016-03-01

    – N2 y tiempo de permanencia de 30 minutos. De acuerdo a los resultados obtenidos se concluye que la mejor condición de fabricación de los MMC, se consigue cuando la mezcla contiene 6% de TiC, alcanzando el menor tamaño de grano, la mayor dureza y el más bajo coeficiente de fricción. En este sentido, se observó que la incorporación de partículas de cerámica (TiC en matriz de acero austenítico (316 presentan mejoras significativas en la resistencia al desgaste.

  1. Fabricación y comportamiento a desgaste de recubrimientos Al/MoSi2 sobre Al fabricados por proyección térmica

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    Díaz Gómez, Miguel

    2010-01-01

    Proyecto Fin de Carrera leído en la Universidad Rey Juan Carlos en el curso académico 2009/2010. Directores del Proyecto: Belén Torres Barreiro y Mónica Campo Gómez Los materiales en la industria sufren un deterioro cuando están sometidos a fricción, lo que produce importantes pérdidas económicas en muchos sectores industriales. Este trabajo pretende contribuir a la búsqueda de recubrimientos que permitan reducir el desgaste de los equipos, alargando así su vida útil, y ahorrando ...

  2. Efecto de la adición de aluminio en la resistencia al desgaste abrasivo del hierro fundido aleado Ni-Resist

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    María Victoria Rojas-Fernández

    2015-12-01

    Full Text Available La presente investigación se planteó como objetivo incrementar la resistencia a la abrasión del hierro fundido aleado Ni-Resist por precipitación de partículas manteniendo invariable la estabilidad química a partir de la adición de aluminio como inductor de compuestos intermetálicos y que contribuye a la formación o precipitación de partículas coherentes. Se experimentó con muestras de aleaciones tipo 2 y tipo 3 de Ni-Resist fijando la variable porcentaje de níquel y moviendo el porcentaje de aluminio; para inducir partículas se aplicó un tratamiento térmico de envejecimiento. Se concluye que la adición de aluminio como elemento aleante en la aleación Ni-Resist, incrementa la resistencia al desgaste por precipitación de partículas debido a su capacidad como inductor de compuestos intermetálicos. Los mejores resultados se obtienen con la adición de 0,5% de aluminio.

  3. Relación microestructura resistencia al desgaste de recubrimientos duros ricos en cromo y tungsteno aplicados por soldadura electrica (SMAW

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    Lisys Margarita León Sevilla

    2004-01-01

    Full Text Available Se comparó la microestructura y resistencia a la abrasión de recubrimientos duros depositados por soldadura sobre placas de acero estructural ASTM A36. Se utilizaron cinco electrodos comerciales, dos de bajo cromo, dos de alto cromo aplicados en una y dos capas y uno rico en tungsteno depositado en una capa La resistencia al desgaste fue evaluada en una máquina de rueda de caucho y arena seca construida según la norma ASTM G65-80. Como material abrasivo se utilizaron partículas de sílice con índice de finura AFS 50- 70. La caracterización de las microestructuras se realizó utilizando microscopía óptica y electrónica de barrido. Los resultados mostraron que el parámetro de resistencia a la abrasión no está directamente relacionado con dureza del material pero sí con el tipo, tamaño, forma, composición química y distribución de los carburos presentes en la matriz del recubrimiento. La mejor resistencia a la abrasión se obtuvo en depósitos con microestructura compuesta por carburos primarios (del tipo M7C3 en recubrimientos ricos en Cr o del tipo MC, M6C en recubrimientos ricos en W en una matriz eutéctica.

  4. Avaliação da resistência ao desgaste de aluminas nanométricas produzidas a partir da decomposição térmica de acetato de alumínio liofilizado Evaluation of wear resistance of nanometric aluminas produced by thermal decomposition of lyophilized aluminum acetate

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    E. Fagury Neto

    2007-12-01

    Full Text Available Ensaios de resistência ao desgaste, na modalidade pino-contra-disco com pares deslizantes, foram realizados em pinos confeccionados a partir de pós de alumina proveniente do processo de decomposição térmica de acetato de alumínio liofilizado. Pós de alumina referentes às fases alfa-Al2O3 e gama-Al2O3, com e sem aditivos de sinterização (MgO e La2O3, foram usados para confeccionar pinos de desgaste. Pinos feitos também a partir de alumina comercial (A1000 SG foram analisados e os resultados foram comparados. Os ensaios foram feitos de acordo com norma ASTM e mostraram que os pinos confeccionados a partir de alfa-Al2O3 têm elevada resistência ao desgaste, comprovada pelos ensaios de perda de massa e microscopia eletrônica. Os pinos de gama-Al2O3 tiveram desempenho intermediário e os pinos de A1000 SG mostraram resultados menos expressivos.Wear resistance tests, using the pin-on-disk test method with sliding pairs, were carried out on pins produced from alumina powders prepared by thermal decomposition of lyophilized aluminum acetate. Alumina powders of alpha-Al2O3 and gamma-Al2O3 phases, with and without sintering additives (MgO and La2O3, were used to produce wear pins. In addition, pins made of commercial alumina (A1000 SG were tested and the results compared. The tests, carried out according to the ASTM standard, indicated that the pins made with alpha-Al2O3 powder showed high wear resistance, a finding corroborated by mass loss tests and scanning electron microscopy. The gamma-Al2O3 pins showed an intermediary performance while the A1000 SG pins showed less interesting results.

  5. Evaluation of austenitic alloys abrasive wear of FeMnAlC system; Avaliacao de desgaste abrasivo de ligas austeniticas do sistema FeMnAlC

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Allan Ribeiro de; Acselrad, Oscar [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Metalurgica e de Materiais. Lab. de Processamento Termomecanico e Engenharia Microestrutural]. E-mail: allariba@metalmat.ufrj.br

    2003-07-01

    Alloys of the FeMnAlC system have been studied as an alternative to stainless steels applications. Such alloys, when solubilized, are non-magnetic and present an austenitic structure that can be modified by thermal treatments. In this way, a large spectrum of mechanical and physical properties can be obtained. They are oxidation-resistant alloys, and by 15 hours aging at 550 deg C mechanical strength can be as high as conventional structural alloy steels. Information concerning the performance of these alloys under wear conditions are still limited. The possibility of application in components exposed to cavitation or abrasive loads, such as pipes, pumps and drilling systems is still a subject for fundamental research, such as the one that is now reported. Samples of a FeMnAlC alloy have been submitted to different thermal processing, leading to microstructures that have been characterized by optical, transmission and atomic force microscopy and by X-ray diffraction. They were subsequently subjected to a micro-abrasion test in which the abrasive wear resistance could be determined. The results have been used to differentiate the performance of different microstructures and allowed also a comparative analysis with the performance of an AISI M2 tool steel. (author)

  6. Influencia de los tratamientos térmicos en el comportamiento frente al desgaste por abrasión de una fundición de grafito esferoidal obtenida mediante adición de boro

    Directory of Open Access Journals (Sweden)

    Varela, A.

    2008-08-01

    Full Text Available By adding boron to the liquid metal, it is possible to obtain spheroidal graphite cast iron without any need for special inoculants. The boron may be in metallic form; alternatively, borax, ferroboron, boron carbonate or borocalcium can be used. These alloys as cast present a pearlite matrix with more or less spheroidal graphite, which is usually edged in ferrite that has markings in the shape of bull’s eye. With normalising, the ferrite edges are eliminated. Thus, a pearlite matrix is achieved. Annealing results in an entirely ferrite matrix; quenching and tempering produce a tempered martensite matrix.This study measures the behaviour under wear of this alloy as cast, normalised, annealed, quenched and tempered . A “pin on disk” test is employed; load and speed conditions, as well as the pin type, are kept constant. Moreover, wear is calculated through weighing, and the variation for the friction coefficient is determined in each case.

    Mediante la adición de boro al metal líquido, bien en forma metálica o en forma de bórax, ferroboro, carburo de boro o boruro cálcico, se pueden obtener fundiciones de grafito esferoidal sin necesidad de inoculantes especiales. Estas fundiciones en estado bruto de colada presentan una matriz perlítica con grafito más o menos esferoidal que suele estar orlado de ferrita formando ojos de buey. Por tratamiento térmico de normalizado, se consigue eliminar la orla ferrítica y tener una matriz enteramente perlítica. Por recocido, se puede obtener una matriz enteramente ferrítica y por temple y revenido una matriz de martensita revenida. En el presente trabajo se mide el comportamiento frente al desgaste abrasivo de la aleación indicada, en estado bruto de colada, normalizado, recocido y bonificado, utilizando el ensayo pin on disk, manteniendo fijas las condiciones de ensayo en cuanto a carga, velocidad y tipo de pin, calculando el desgaste producido por pesada. También, se

  7. Desarrollo y optimización de recubrimientos de superaleaciones con adición de cargas cerámicas y elementos reactivos obtenidos por proyección térmica para aplicaciones de resistencia a oxidación a alta temperatura y al desgaste

    OpenAIRE

    Cervera González, Iván

    2011-01-01

    El objetivo principal del presente trabajo es la obtención de recubrimientos con una composición optimizada para aplicaciones de elevada resistencia a alta temperatura y al desgaste, proyectados térmicamente sobre acero al carbono AISI 1110, mediante la técnica de oxifuel, basados en el sistema NiCrAlY/Al2O3. Estos recubrimientos deben ser capaces de proteger adecuadamente a un material de escasa resistencia mecánica y térmica para el rango de temperaturas analizado, que se sitúa entre 850 – ...

  8. EFECTO DEL CONTENIDO DE CARBONO SOBRE LA RESISTENCIA AL DESGASTE ABRASIVO DE RECUBRIMIENTOS DE CrC DEPOSITADOS POR PULVERIZACIÓN CATÓDICA MAGNETRÓN EFEITO DO CONTEÚDO DE CARBONO SOBRE A RESISTÊNCIA AO DESGASTE ABRASIVO DE RECOBRIMENTOS DE CrC DEPOSITADOS POR PULVERIZAÇÃO CATÓDICA MAGNETRÃO EFFECT OF THE CARBON CONTENT IN ABRASIVE WEAR RESISTANCE OF CrC COATINGS DEPOSITED BY MAGNETRON SPUTTERING

    Directory of Open Access Journals (Sweden)

    Maryory Astrid Gómez

    2012-12-01

    Full Text Available Los recubrimientos de carburo de cromo sobre acero son un buen candidato para aplicaciones de conformado y moldes de inyección. La alta resistencia mecánica, resistencia química y estabilidad a alta temperatura de la fase Cr3C2 pueden ser compatibles con el intenso desgaste abrasivo y la corrosión en tales operaciones de fabricación. En este trabajo se depositaron recubrimientos de CrC por pulverización catódica magnetrón RF, los cuales mostraron contenidos de carbono entre el 25 % y el 58 % por análisis EDS. Los valores de dureza de estos recubrimientos fueron entre 15 y 24 GPa; los más duros de las muestras tuvieron contenido de carbono en el rango de 39-53 %. El desgaste abrasivo de los recubrimientos se evaluó utilizando un equipo de disco abrasivo con polvo de diamante. El volumen de las huellas de abrasión se midió con las imágenes obtenidas en el microscopio interferométrico y además se corroboró con el cálculo del volumen geométrico basado en secciones medidas con el perfilómetro. El comportamiento al desgaste abrasivo mostró una marcada dependencia con el contenido de carbono. El desgaste abrasivo más bajo se obtuvo para los recubrimientos con el más alto contenido de carbono.Os recobrimentos de carburo de cromo sobre aço são um bom candidato para aplicações de conformado e moldes de injeção. A alta resistência mecânica, resistência química e estabilidade em alta temperatura da fase Cr3C2 podem ser compatíveis com o intenso desgaste abrasivo e a corrosão em tais operações de fabricação. Neste trabalho depositaram-se recobrimentos de CrC por pulverização catódica magnetrão RF, os quais mostraram conteúdos de carbono entre 25 % e 58 % por análise EDS. Os valores de dureza destes recobrimentos foram entre 15 e 24 GPa; os mais duros das mostras tiveram conteúdo de carbono na faixa de 39-53 %. O desgaste abrasivo dos recobrimentos avaliou-se utilizando uma equipe de disco abrasivo com pó de

  9. Implementación de un convertidor Buck de 8 fases controlado en modo deslizante con entrelazado y frecuencia de conmutación fija

    OpenAIRE

    Garcia, Pilar; Repecho del Corral, Víctor; Biel Solé, Domingo; Ramos Lara, Rafael Ramón

    2015-01-01

    Este artículo presenta el diseño y construcción de un convertidor reductor en configuración multifase, de 8 módulos, con tensión de entrada nominal de 48V, con tensión regulada en la salida, con valores nominales entre 12 y 36 V, capaz de entregar hasta 50A en continua. Para minimizar el rizado se emplea la técnica de interleaving (entrelazado). El control del convertidor se efectúa mediante control en modo deslizante, dotando al sistema de una muy buena respuesta transitoria y una gran robus...

  10. Efecto del conteo de nódulos en la resistencia al desgaste por abrasión de los hierros dúctiles austemperados

    Directory of Open Access Journals (Sweden)

    C. J. Diez Cicero

    2009-05-01

    Full Text Available Entre los materiales metálicos de mayor demanda, la producción de hierro con grafito nodular, ocupa en la actualidad, uno de los lugares más importantes entre los hierros fundidos de alta resistencia, y con la introducción del tratamiento térmico de austemperado, aplicado a estas fundiciones, se da lugar a una nueva familia de materiales, caracterizados por su alta resistencia mecánica y elevada tenacidad, que mantienen la economía y facilidad de producción de las fundiciones nodulares.Este trabajo, hace una valoración del comportamiento de hierros nodulares, con diferentes conteos de nódulos, a los que les fue aplicado el tratamiento de austemperado, y posteriormente se les sometió a ensayos de desgaste abrasivo. Con los resultados obtenidos, se hace un análisis de la influencia del conteo de nódulos en dichas propiedades, así como también, de la interrelación del conteo de nódulos, con las variables de tratamiento térmico utilizadas en las muestras ensayadas.Between the metallic materials of greater demand, the iron production with nódular graphite occupies at the present time, one of the most important places between fused irons of high resistance, and with the introduction of the austemperado heat treatment of, applied to these smeltings, gives rise to a new family of materials, characterized by its high resistance mechanical and elevated tenacity, that the economy and facility of production of the smeltings maintain nodulares. This work, makes a valuation of the iron behavior nodulares, with different counts from nodules, to which the austemperado was applied treatment to them of, and later it was put under to them tests of abrasive wearing down. Of the obtained results, an analysis takes control of the influence of the count of nodules in these properties, as well as, of the interrelation of the count of nodules, with the used variables of heat treatment in the tried samples.

  11. Comportamiento frente al desgaste y fricción de aceros empleados en líneas de manutención aérea ensayados con y sin lubricación

    Directory of Open Access Journals (Sweden)

    Castro Regal, G.

    2005-06-01

    Full Text Available The sliding friction and wear behaviour of different steel qualities were investigated with and without lubrication conditions. Steel qualities tested are normally used in the overhead conveyor system of many industrial fields, like the automotive sector. Sliding wear tests have been conducted by means of a pin-on-disk machine. A 100Cr6 steel similar to that used within the overhead conveyor trolleys has been employed as a pin. Friction coefficient values obtained under lubrication conditions were three times smaller than those obtained without lubrication. The mechanism that controls wear behaviour under lubrication conditions is an abrasive one and the wear values obtained are almost worthless. On the other hand, mechanism controlling wear during non lubrication tests, was a combination of abrasion and adhesion

    Se ha evaluado el comportamiento frente a fricción y el desgaste de distintas calidades de acero ensayadas bajo condiciones de lubricación y sin lubricación. Las calidades de acero seleccionadas son las que normalmente se emplean en los sistemas de manutención aérea de numerosos procesos de producción, como la fabricación de automóviles. Se han realizado ensayos de desgaste tipo punzón-disco mediante un punzón de acero de calidad100Cr6, empleado en los carros que circulan por las líneas de manutención aérea. Se ha observado que el valor del coeficiente de fricción obtenido bajo condiciones de lubricaciones, aproximadamente, tres veces menor que el obtenido sin lubricación. Por otro lado, el mecanismo que controla el proceso de desgaste de los aceros ensayados con lubricación es un mecanismo de desgaste abrasivo y los valores de desgaste obtenidos son prácticamente despreciables. El desgaste de los aceros ensayados sin lubricación se produjo por combinación de dos mecanismos de desgaste: abrasión y adhesión.

  12. Efecto de la temperatura de depósito sobre la resistencia al desgaste en recubrimientos de Nitec 10224 (Ní + 5% Fe,B, Si) y Metaceram 23075 (Ní + 40% WC/Co) obtenidos con la técnica de proyección térmica

    OpenAIRE

    Otálora Sánchez, Diego Fernando

    2014-01-01

    En este trabajo se presentan los resultados obtenidos en el depósito de recubrimientos a base de Níquel y a base de Niquel - Tungsteno sobre sustratos de hierro, con preparación de superficie mediante granallado por arena, utilizando la técnica de proyección térmica por llama. Básicamente, se estudió la influencia que tiene la temperatura de depósito del recubrimiento sobre las propiedades estructurales, morfológicas y en la resistencia al desgaste. Los recubrimientos fueron ca...

  13. Estudio de desgaste de recubrimientos duros en una herramienta de arado tipo cincel

    OpenAIRE

    Agudelo Giraldo, Pablo Esaú

    2013-01-01

    Se estudió la resistencia al desgaste de cuatro recubrimientos duros aplicados en una herramienta de arado tipo cincel, comparados con el desgaste de una herramienta comercial. Se planteó un diseño experimental de 1 factor, 5 tratamientos y 12 bloques aleatorizados, con pruebas a escala real, llevadas a cabo en un suelo franco arcilloso. Se usaron dos electrodos de alto cromo y alto carbono (Fe-C-Cr y Fe-C-Cr-Nb), cada uno de ellos, aplicados mediante el proceso FCAW en deposiciones de una y ...

  14. Morfología del desgaste dentario en fumadores de pipas de arcilla

    Directory of Open Access Journals (Sweden)

    Alberto Goyenechea

    2001-01-01

    Full Text Available Se describen dos casos de claro desgaste dentario como consecuencia del uso de pipas de arcilla para fumar en restos esqueléticos de cronolgía moderna. Proceden de la excavación arqueológica de la Iglesia de San Martín de Buruntza, en Gipuzkoa, y los dos casos se caracterizan por presntar un desgaste dentario doble, circular a ambos lados de los maxilares, debido a una fricción homogénea que afecta al esmalte y dentina que es compatible con el uso de pipas de fumar de arcilla.

  15. El desgaste severo en odontología: revisión narrativa de la literatura

    OpenAIRE

    Cepeda Pérez, Ángela Jimena

    2015-01-01

    El desgaste dental severo es una patología que compromete la salud del sistema estomatognático. Al igual que los síndromes de colapso de mordida posterior, de combinación o Kelly y el miofacial doloroso, el desgaste dental severo se considera como un cuadro clínico de oclusión patológica pero a diferencia de éstos, esta entidad no se considera como síndrome en la literatura. Este trabajo analiza las características propias de la patología, para evaluar en qué medida puede o no ...

  16. Las repercusiones del desempeño docente en la satisfacion y el desgaste del profesorado

    OpenAIRE

    Subaldo Suizo, Lucía

    2012-01-01

    El objetivo básico de la Tesis se centra en el estudio de las repercusiones del desempeño docente en la satisfacción y el desgaste del profesorado en tres distritos de Lima Metropolitana, Perú. La investigación toma como punto de partida la difícil realidad de la educación en la sociedad actual debido a los cambios sociales que generan nuevas demandas, insatisfacciones y desgastes en el desempeño del trabajo docente que afectan seriamente a la salud y al bienestar del profesorado. Esta si...

  17. Resistencia al desgaste abrasivo de recubrimientos comerciales metaceram 25050 y proxon 21071 producidos con el sistema de proyección térmica por llama

    OpenAIRE

    Hincapié Campos, Williams Steve

    2013-01-01

    En este trabajo se investigo como el método de preparación superficial del sustrato afecta el comportamiento mecánico de recubrimientos de Metaceram 25050 Y Proxon 21071, fabricados por medio de proyección térmica por llama, recubiertos y no recubiertos con una capa adhesión (Ni 11%Al). Los sustratos se prepararon por granallado metálico, granallado por arena y por disco abrasivo. El análisis estructural de los recubrimientos se realizo mediante difracción de rayos X (DRX); la ...

  18. Robust control decentralized by sliding ways of electrical of power multi-machines systems; Control robusto descentralizado por modos deslizantes de sistemas electricos de potencia multimaquinas

    Energy Technology Data Exchange (ETDEWEB)

    Huerta Avila, Hector

    2008-09-15

    This work deals with the problem of robust decentralized control of multimachine electric power systems. These systems are subject to different perturbations, such as short circuits, connection and/or disconnection of loads, lines generators, mechanical torque variations, etc. Then, it is necessary controllers which guarantee robustness under those perturbations to provide electrical energy to the loads with admissible stability margins. Moreover, the controller must be robust under parametric variations due to model uncertainties, and other physical reasons. The electrical power systems are modeled as complex great scale nonlinear systems. Then, the controller design is a challenging problem. Thus, the decentralized control schemes enable to avoid these problems. This work proposes three novel robust nonlinear techniques. The first one is based on the block control and integral sliding modes. The second obtains a sliding manifold from the Hamiltonian model of a nonlinear system to use this manifold in the integral sliding modes. The third technique enables to apply the sliding mode technique to a nonlinear block controllable system, by using Lyapunov function in each block. Then, four control schemes for electric power systems are designed. The four control schemes are robust under the perturbations of electric power systems mentioned above. The controllers proposed can be implemented in any electric power system with n generators, m lines and k loads. [Spanish] Este trabajo esta dedicado al diseno de esquemas de control robustos descentralizados que sean capaces de responder satisfactoriamente en sistemas electricos de potencia multimaquinas. Estos sistemas estan sujetos a perturbaciones de diferentes tipos, como cortos circuitos, entrada y salida de lineas de cargas o de generadores. Es evidente la necesidad de controladores que puedan rechazar estas perturbaciones para proveer energia de calidad y sin interrupciones a todos los usuarios conectados a la red

  19. Resistencia al desgaste y a la abrasión de polímeros técnicos y nanocomposites

    OpenAIRE

    Ojados Sánchez, Gonzalo

    2013-01-01

    Las conclusiones a las que se ha llegado con este PFC son: 1. En este trabajo se ha estudiado la posibilidad de mejorar las propiedades térmicas, mecánicas y tribológicas de polímeros de interés industrial mediante su modificación con líquidos iónicos, nanotubos de carbono o combinaciones de ambos en forma de nanofluidos o nanofases modificadas. 2. En matrices de resina epoxi, la adición de nanotubos de carbono y líquido iónico incrementa su estabilidad térmica, al mismo tiempo que actúa c...

  20. Modelamiento de la dinámica termo-mecánica presente en un par deslizante con fines de predecir desgaste

    OpenAIRE

    Rudas Florez, Juan Sebastián

    2013-01-01

    Resumen: El daño progresivo que se produce en la superficie de un componente como resultado de su movimiento relativo a las partes adyacentes de trabajo, tiene profundas consecuencias económicas que implican no sólo los costes de sustitución, sino también los gastos relacionados con la inactividad de la máquina y pérdida de producción, haciéndose necesario estudiar, analizar y modelar el proceso de deslizamiento entre sólidos. Se tiene conocimiento del desarrollado de diferentes modelos estát...

  1. Dry sliding wear of Al-Fe-Cr-Mn quasicrystalline phase former alloy obtained by spray forming; Estudo do comportamento ao desgaste de liga Al-Fe-Cr-Mn obtida por conformacao por spray

    Energy Technology Data Exchange (ETDEWEB)

    Yamasaki, S.M.T.; Rios, C.T.; Botta Filho, W.J.; Bolfarini, C.; Kiminami, C.S. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais; Gargarella, P.; Mendes, M.A.B., E-mail: marcio.andreato@gmail.co [Universidade Federal de Sao Carlos (PPG-CEMUFSCar), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2010-07-01

    Samples from different regions of a spray formed billet of Al{sub 92}Fe{sub 3}Cr{sub 2}Mn{sub 3} quasicrystalline phase former alloy were analyzed and their wear behavior has been studied. The microstructures observed depend on the cooling rate imposed to the material. The border of the billet exhibits a very fine structure with presence of quasicrystalline phase and the base showed a fine structure but without presence of quasicrystalline phase. Dry sliding wear tests were made using three loads and samples of these two different regions. The wear surfaces were analyzed by scanning electron microscopy and X-ray diffraction. Similar wear behavior was observed in the border and the base samples at the same load. The wear mechanism verified is the adhesive and the applied load increases the formation of Al{sub 2}O{sub 3}. These particles can take off the surface and act as abrasive, which can explain the large increase in the wear rate for the samples loaded at 30N.(author)

  2. Efecto del conteo de nódulos en la resistencia al desgaste por abrasión de los hierros dúctiles austemperados. // Effect of nodules count in the waste by abrasion resistance for ductile austempering irons.

    Directory of Open Access Journals (Sweden)

    C. J. Diez Cicero

    2004-05-01

    Full Text Available Entre los materiales metálicos de mayor demanda, la producción de hierro con grafito nodular, ocupa en la actualidad unode los lugares más importantes entre los hierros fundidos de alta resistencia, y con la introducción del tratamiento térmicode austemperado aplicado a estas fundiciones, se da lugar a una nueva familia de materiales, caracterizados por su altaresistencia mecánica y elevada tenacidad, que mantienen la economía y facilidad de producción de las fundicionesnodulares.Este trabajo, hace una valoración del comportamiento de hierros nodulares, con diferentes conteos de nódulos, a los que lesfue aplicado el tratamiento de austemperado y posteriormente se les sometió a ensayos de desgaste abrasivo.Con los resultados obtenidos se hace un análisis de la influencia del conteo de nódulos en dichas propiedades, así comotambién de la interrelación del conteo de nódulos con las variables de tratamiento térmico utilizadas en las muestrasensayadas.Palabras claves: Hierro nodular, conteo de nódulos, austemperado.____________________________________________________________________________Abstract.Between the metallic materials of greater demand, the iron production with nódular graphite occupies at the present time,one of the most important places between fused irons of high resistance, and with the introduction of the austempering heattreatment, applied to these meltings, brings a new family of materials, characterized by its high mechanical resistance andelevated tenacity, that maintain the economy and facility of production of the nodular smeltings.This work makes a valuation of the nodular irons behaviors, with different counts from nodules, to which the austemperingtreatment was applied, and later they were put under tests of abrasive wearing.Of the obtained results, takes control of the influence the nodules count in these properties, as well as, of the interrelation ofthe nodules count, with the used variables of heat

  3. Efecto del conteo de nódulos en la resistencia al desgaste por abrasión de los hierros dúctiles austemperados. // Effect of nodules count in the abrasive wear of austempered ductile irons.

    Directory of Open Access Journals (Sweden)

    C. J. Diez Cicero

    2009-05-01

    Full Text Available Entre los materiales metálicos de mayor demanda, la producción de hierro con grafito nodular,ocupa en la actualidad, uno de los lugares más importantes entre los hierros fundidos de altaresistencia, y con la introducción del tratamiento térmico de austemperado, aplicado a estasfundiciones, se da lugar a una nueva familia de materiales, caracterizados por su alta resistenciamecánica y elevada tenacidad, que mantienen la economía y facilidad de producción de lasfundiciones nodulares.Este trabajo, hace una valoración del comportamiento de hierros nodulares, con diferentes conteosde nódulos, a los que les fue aplicado el tratamiento de austemperado, y posteriormente se lessometió a ensayos de desgaste abrasivo.Con los resultados obtenidos, se hace un análisis de la influencia del conteo de nódulos en dichaspropiedades, así como también, de la interrelación del conteo de nódulos, con las variables detratamiento térmico utilizadas en las muestras ensayadas.Palabras claves: hierro nodular, conteo de nódulos, austemperado.__________________________________________________________________________AbstractBetween the metallic materials of greater demand, the iron production with nódular graphiteoccupies at the present time, one of the most important places between fused irons of highresistance, and with the introduction of the austemperado heat treatment of, applied to thesesmeltings, gives rise to a new family of materials, characterized by its high resistance mechanicaland elevated tenacity, that the economy and facility of production of the smeltings maintainnodulares. This work, makes a valuation of the iron behavior nodulares, with different counts fromnodules, to which the austemperado was applied treatment to them of, and later it was put underto them tests of abrasive wearing down. Of the obtained results, an analysis takes control of theinfluence of the count of nodules in these properties, as well as, of the interrelation of

  4. Plataforma virtual de péndulo sobre carro deslizante para la enseñanza del control automático

    Directory of Open Access Journals (Sweden)

    Oscar Rodriguez D

    2013-09-01

    Full Text Available En este artículo se presenta el desarrollo de un sistema de plataforma virtual para la enseñanza del control automático basado en el péndulo invertido sobre carro deslizante, el cual se desarrolla herramientas didácticas sobre un prototipo virtual, simulando el modelo no lineal en matlab y presentado en un entorno amigable basado en easy-java. Para el diseño de los controladores, se tienen en cuenta dos aspectos principales como los son el “swing up” (llevar el péndulo a posición vertical y el balanceo (mantener el péndulo en la posición vertical. La interfaz al usuario busca facilitar el aprendizaje de los conceptos básicos de un sistema de control automático para estudiantes de pregrado y posgrado, buscando minimizar costos y tiempo en la enseñanza e implementación de sistemas de control.

  5. Estudio del modelo de desgaste propuesto por Archard

    Directory of Open Access Journals (Sweden)

    FABIO ALEXANDER SUÁREZ BUSTAMANTE

    2005-01-01

    Full Text Available El comportamiento de componentes de máquinas y de materiales necesita ser optimizado para reducir los costos de operación en las plantas industriales. Este hecho ha impulsado la Tribología, un área relacionada con el estudio de la fricción, la lubricación y el desgaste. Uno de los principales objetivos de esta área del conocimiento es elaborar modelos matemáticos para expresar la variación del desgaste durante el contacto de superficies en movimiento, con el fin de predecir la vida útil de los elementos de máquinas. El modelo de Archard para desgaste por deslizamiento en seco, formulado en 1953, es un modelo clásico que plantea una variación del desgaste inversamente proporcional a la dureza del material y directamente proporcional a la carga aplicada. En el presente trabajo, se ha utilizado el método de modelamiento de problemas físicos, propuesto por Asbhy, para analizar los modelos propuestos por Archard (Modelo de contactos múltiples en superficies rugosas y modelo de desgaste mecánico. Con base en él se ha podido realizar un análisis profundo a dichos modelos, mostrando un panorama más amplio del modelo de Archard; se discuten aspectos no mostrados en los textos y artículos de tribología, donde el tratamiento dado a este modelo resulta ser superficial, desconociendo las limitaciones y la perspectiva que tuvo Archard sobre los aspectos que deberían considerarse en un modelo de desgaste.

  6. A discreet control of sliding ways of an induction motor; Control discreto de modos deslizantes de un motor de induccion

    Energy Technology Data Exchange (ETDEWEB)

    Rivera Dominguez, Jorge

    2001-12-15

    A control of sliding ways in discreet time for non-linear discreet systems is designed, also the technique of the control by histograms for non-linear discreet systems was developed, and an observer of reduced order was developed for non-linear electromechanical discreet systems. All these techniques are applied to a non-linear discreet model of an induction motor that was found here, that posses electrical and mechanical dynamics, in which the load pair is considered an unknown disturbance. With complete measurements of the states are satisfied the pursuing of the rotor velocity and the amplitude of the magnetic flux of the rotor, where the unknown load does not affect the velocity regulation. Next, an observer of reduced order is implemented where the velocity and current measurements are employed to consider the load pair and the flows that are very difficult to measure. The proposed method has a design and stability procedure of direct analyses, conserving a simple structure of the control law. The simulations predict that the system is robust with respect to several types of load pairs. The responses of velocity and amplitude of the rotor flow and the entrance references evolved very well. These references have a linear dynamics of second order with time constants that can be chosen by the motor user. The practical aspects for a future digital implementation of the control law are considered, including the velocity and currents sensors, the preparation of signals, the transformation of the current in the frame of stationary reference, PWM and inverter modules, which were seen in detail. The experimental results are left as a future work. [Spanish] Se disena un control de modos deslizantes en tiempo discreto para sistemas discretos no lineales, tambien se desarrollo la tecnica del control por bloques para sistemas discretos no lineales, y un observador de orden reducido fue desarrollado para sistemas discretos electromecanicos no lineales. Todas estas tecnicas

  7. Desgaste da equipe de enfermagem no centro de tratamento de queimados Desgaste del equipo de enfermeros en el centro de quemados Burn out of the nursing team in the burn center

    Directory of Open Access Journals (Sweden)

    Joselena Aquino Barreto Coelho

    2010-01-01

    Full Text Available OBJETIVO: Descrever como as percepções sensoriais da equipe de enfermagem apontam para compreensão do desgaste amplo dos sentidos durante os cuidados prestados. MÉTODOS: Estudo qualitativo, baseado nos princípios da sociopoética e no dispositivo do grupo pesquisador, a partir de dinâmicas de criatividade e sensibilidade. No primeiro período de 2008, participaram do estudo11 profissionais de enfermagem de um hospital municipal do Rio de Janeiro. RESULTADOS: A partir dos conceitos de desgaste mental, de Seligmann-Silva, e dos sentidos corporais de Araújo, observou-se que os efeitos da visão e da audição desgastam emocionalmente a equipe. O tato, durante o desbridamento, sinalizou cansaço físico/psíquico. O maior desgaste é gerado pela mazela social, relacionada com as causas das queimaduras. CONCLUSÕES: A equipe de enfermagem, utilizando estratégias defensivas, reduz o desgaste psíquico e o sofrimento durante o cuidado prestado. A pesquisa proporcionou repensar o cuidado através de subjetividades da equipe.OBJETIVO: Describir como las percepciones sensoriales del equipo de enfermería apuntan para la comprensión del desgaste amplio de los sentidos durante los cuidados prestados. MÉTODOS: Estudio cualitativo, basado en los principios de la socio-poética y en el dispositivo del grupo investigador, a partir de dinámicas de creatividad y sensibilidad. En el primer período de 2008, participaron del estudo11 profesionales de enfermería de un hospital municipal de Rio de Janeiro. RESULTADOS: A partir de los conceptos de desgaste mental, de Seligmann-Silva, y de los sentidos corporales de Araújo, se observó que los efectos de la visión y de la audición desgastan emocionalmente al equipo. El tacto, durante la remoción, señalizó cansancio físico y psíquico. El mayor desgaste es generado por la repercusión social, relacionada con las causas de las quemaduras. CONCLUSIONES: El equipo de enfermería, utilizando estrategias

  8. Comportamiento a desgaste de recubrimientos de WC proyectados por plasma a partir de polvos micro y nanoestructurados

    Directory of Open Access Journals (Sweden)

    Salvador, M. D.

    2008-06-01

    difracción de rayos X. La caracterización tribológica de los recubrimientos se realiza mediante ensayos pin-on-disc contra bolas cerámicas de alúmina (2.400 HV y nitruro de silicio (1.600 HV, sin lubricación, obteniéndose las tasas de desgaste y la evolución del coeficiente de rozamiento. Las pistas de desgaste y los residuos generados se caracterizaron mediante Microscopía Electrónica de Barrido, MEB. Los resultados muestran diferentes mecanismos de desgaste en cada par de material ensayado en función de la matriz y de la naturaleza de la bola empleada en el ensayo, encontrándose mayores tasas de desgaste con bola de nitruro de silicio. En una segunda fase, se obtienen recubrimientos, con dos polvos base cobalto cuyos tamaños de partícula son micrométrico y nanométrico, respectivamente, con el objetivo de estudiar la influencia del tamaño de partícula inicial sobre las propiedades a desgaste del recubrimiento. Los resultados obtenidos ponen de manifiesto una mayor resistencia al desgaste de los recubrimientos obtenidos con polvos nanoestructurados, bajo condiciones de carga elevadas, mientras que para cargas bajas ambos recubrimientos presentan un comportamiento similar a pesar de las diferencias microestructurales apreciadas.

  9. Prevalencia del síndrome de desgaste en médicos residentes costarricenses

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    Ricardo Millán-González

    2009-04-01

    Full Text Available Justificación y objetivo: determinar las características sociodemográficas del síndrome de desgaste en médicos residentes en Costa Rica durante el 2007 y validar localmente la escala de Maslach. Metodología: investigación aplicada, descriptiva y de corte transversal, en la que participaron 121 sujetos que cursaban primer y tercer año de las siguientes especialidades que imparte el CENDEISSS: anestesiología y recuperación, especialidades médicas y quirúrgicas, ginecología y obstetricia, pediatría y psiquiatría. Se aplicó el Maslach Burnout Inventory-Human Services Survey (versión validada en español y una ficha de datos sociodemográfica que incluía especialidad médica, sede de residencia, sexo, estado civil, número de hijos, edad de los participantes, frecuencia mensual de guardias y año cursado de residencia. Resultados: El análisis final detectó alto agotamiento emocional en mujeres y en residentes de pediatría; bajo agotamiento emocional en quienes realizan en promedio 4 guardias por mes y en residentes de geriatría y psiquiatría; alta despersonalización en hombres; baja despersonalización en residentes de geriatría y medicina familiar así como en personas unidas; bajos niveles de realización personal en personas unidas; el síndrome de desgaste como tal fue mayor en mujeres, que cursaban el tercer año, sujetos unidos, personas con hijos, menores de 30 años y residentes de las especialidades médicas. Adicionalmente se validó la utilización de la escala en Costa Rica. Conclusión: existen subgrupos de médicos residentes que se encuentran en riesgo de presentar el síndrome de desgaste profesional o elevadas puntuaciones en algunas de sus 3 dimensiones. Algunos de ellos podrían ser propios del personal que mantiene una carga académica y laboral al mismo tiempo. Este hecho debe ser tomado en cuenta cuando se planifican las estrategias de bienestar mental en el sector salud.

  10. Evaluación del desgaste de la banda transportadora en las minas de níquel de Moa y Nicaro

    Directory of Open Access Journals (Sweden)

    Lorenzo Velazquez

    2009-03-01

    Full Text Available Las bandas trasportadoras en las minas de níquel de las empresas Ernesto Che Guevara, de Moa y Rene Ramos Latour, de Nicaro, sufren desgaste y destrucción paulatina por la acción de los impactos de la mena al caer, y por el desplazamiento de estas partículas sobre la banda. Para evaluar el desgaste de la banda se experimentó, dejando caer sobre ella, desde diferentes alturas, partículas de diversos tamaños y formas, variando la velocidad de movimiento de la banda, con el fin de establecer el desplazamiento de las partículas de forma experimental y teórica en función de la velocidad de movimiento. Esto permite determinar la longitud del área de suministro del transportador y la resistencia al movimiento en esa zona. Como resultado se obtuvo un modelo teórico que permite evaluar la variación de la velocidad de deformación de la banda al verter el mineral desde alturas diferentes. Se concluye que el desgaste de la banda en los puntos de carga puede reducirse disminuyendo la altura de caída y se recomienda emplear velocidades de banda mayores de 3 m/s independientemente del tamaño y forma de las partículas.

  11. SISTEMA DE CONTROL EN MODO DESLIZANTE PARA REGULAR LA POSICIÓN Y LA VELOCIDAD DE UN MOTOR DE CORRIENTE DIRECTA

    Directory of Open Access Journals (Sweden)

    Cornieles, Ernesto

    2015-01-01

    Full Text Available En el presente trabajo se aplica la teoría de un Sistema de Control en Modo Deslizante, para regular la posición y velocidad de un motor de corriente directa. El desarrollo matemático que permitió diseñar un panel donde el sistema de control se ha expresado a través de instrumentos virtuales en el diagrama de bloques del software de LabView®, que permite manipular variables en tiempo real gracias a la tarjeta de adquisición de datos DAQ6024E de la National Instruments. Todos los datos ingresan y salen del computador de forma analógica a través de un convertidor A/D, vista físicamente como una señal de voltaje. Esta inserción de datos es posible a través de un tacómetro digital que interpreta los pulsos del obturador óptico diseñado como rad/seg para el caso de la velocidad o en radianes para la posición. La salida de datos se adecua a través de un circuito de amplificación y un circuito de potencia que regularán la tensión de excitación. Con la finalidad de obtener una mayor precisión en la posición del eje del motor el controlador aplicará una tensión constante cuyo valor no excede los 2 voltios en los terminales del motor. La velocidad del motor no excederá los 190 rad/seg, es decir, trabajará en un rango de tensión comprendido entre 0 y 10 voltios en terminales, con esto se garantizará el óptimo funcionamiento del circuito de potencia sin alcanzar sus límites de operación. Todos los resultados obtenidos para controlar la posición y la velocidad angular son satisfactorios para los valores deseados en radianes y radianes/seg del motor de corriente directa.

  12. El desgaste profesional (sindrome de burnout) en los trabajadores sociales

    OpenAIRE

    Lázaro Fernández, Santa

    2004-01-01

    Los escenarios actuales del Trabajo Social condicionados por el debilitamiento del Estado de Bienestar y la creciente globalización, conllevan un aumento de la presión ejercida sobre los trabajadores sociales que se ven envueltos entre las exigencias de las organizaciones, las demandas de los ciudadanos y sus valores y principios profesionales. Estas circunstancias contribuyen a la aparición del síndrome de burnout o desgaste profesional que ha sido objeto de múltiples investigaciones en el c...

  13. Estimativa do coeficiente de reaeração da água em canal raso de fundo deslizante

    Directory of Open Access Journals (Sweden)

    Flávia Martins de Queiroz

    2015-03-01

    Full Text Available O coeficiente de reaeração, K2, é a variável de maior influência na autodepuração de corpos hídricos; portanto, estimativas confiáveis são de suma importância. As previsões de K2, por meio de equações, em condições de escoamento raso são, geralmente, superestimadas. Por isso, neste trabalho, os objetivos foram estudar a reoxigenação da água limpa em canal hidráulico de fundo deslizante, com pequenas profundidades de água e diferentes velocidades de escoamento, inferir sobre as principais variáveis hidrodinâmicas intervenientes no processo e, com base nelas, propor equação de estimativa de K2. Com a concentração de oxigênio na água ao longo do tempo, estimou-se K2. Inferiu-se, dos resultados, que as variáveis velocidade média (V e velocidade de corte (u*, profundidade (H, números de Froude (Fr e de Reynolds (R, declividade (S e fator de forma (ff afetaram K2, e a melhor equação foi a que incluiu as três últimas variáveis.

  14. Estudio del desgaste del flanco de carburos recubiertos y cermet durante el torneado de alta velocidad en seco del acero AISI 1045

    Directory of Open Access Journals (Sweden)

    Hernández-González, L. W.

    2011-06-01

    Full Text Available This work deals with the experimental study of the flank wear evolution of two coating carbide inserts and a cermet insert during the dry finishing turning of AISI 1045 steel with 400, 500 and 600 m/min cutting speeds. The results were analyzed using the variance analysis and lineal regression analysis in order to describe the relationship between the flank wear and machining time, obtaining the adjusted model equation. The investigation demonstrated a significant effect of cutting speed and machining time on the flank wear at high speed machining. The three coating layers insert showed the best performance while the two layers insert had the worst behaviour of the cutting tool wear at high cutting speeds.

    El objetivo de este trabajo es el estudio experimental de la evolución del desgaste del flanco respecto al tiempo de dos insertos de carburo recubiertos y un cermet durante el torneado de acabado en seco del acero AISI 1045 con velocidades de corte de 400, 500 y 600 m/min. Los resultados fueron comparados utilizando el análisis de varianza y el análisis de regresión lineal para describir la relación entre el desgaste del flanco y el tiempo de maquinado, obteniéndose la ecuación del modelo ajustado. La investigación demostró un efecto significativo de la velocidad de corte y del tiempo de maquinado en el desgaste del flanco en el maquinado de alta velocidad. El mejor desempeño se obtuvo para el carburo recubierto con tres capas, mientras que el carburo con dos capas sufrió el mayor desgaste a elevadas velocidades de corte.

  15. Desgaste adhesivo (scuffing) en camisas de cilindros y aros de pistón de motores diesel lentos de dos tiempos 

    OpenAIRE

    Conde Cid, Luis; Fernández Vacas, Francisco; Martínez Melgarejo, Miguel

    2002-01-01

    [ES] En este trabajo se describe el desgaste adhesivo (scuffing) que representa la más severa de las agresiones a la que se ven expuestos aros de pistón y camisas de cilindro de motores diésel lentos de dos tiempos aplicados a la generación eléctrica, al quemar combustibles de bajo contenido en azufre. Al afectar simultáneamente, a estos dos elementos básicos de la cámara de combustión, repercute negativamente tanto en la continuidad del servicio del motor, como en los costes asociados a la r...

  16. Construcción de silos con encofrados deslizantes - Santa Cruz de Tenerife – España

    Directory of Open Access Journals (Sweden)

    Barrios Martínez, M.

    1976-10-01

    Full Text Available These cereal and oil-cake silos are made up of 10 exterior cylindrical cells, with an inner diameter of 6 m and a height of 31.88 m. The cells are joined together by means of walls whereby four additional octagonal cells are created. Out of these, three are subdivided into four cells and the fourth forms the central silo. Below this unit there is a corridor for the emptying of the silos. The work has been carried out with a travelling form with the following characteristics: mixed with regard to shape and materials; stiff, since the top platforms are connected; and it has a constant cross-section as the dimensions of the silos remain the same throughout the whole height. The form was lifted by means of elevation devices, controlled by a centralized hydraulic mechanism. In view of the characteristics of the travelling form, the concrete used ¡n the work had to fulfill several very special conditions, notably different from these applying to the concrete that is normally used for fixed forms. For this reason, it was submitted to a great number of studies and tests until the requirements had been met. The construction was finished in record time: in the first place, because a detailed programme had been worked out in advance, consisting of a diagram of bars and preference network and secondly, because continuous concreting was applied with day and night shifts, whebery the foreseen two and a half months for finishing the silos were reduced to 12 days.Estos silos, destinados a almacenamiento de cereales y borujo, están formados por 10 celdas exteriores cilíndricas, de 6 m de diámetro interior y 31,88 m de altura, que se unen entre sí por medio de muros, dando lugar a cuatro celdas adicionales de forma octogonal. De éstas, tres están subdivididas en cuatro interceldas, quedando la cuarta como silo central. Debajo del conjunto se ha dispuesto una galería para el vaciado de los silos. La obra se ha realizado con un encofrado deslizante

  17. Sindrome de desgaste profesional (burnout) en médicos especialistas de un hospital universitario, de la ciudad de Santa Marta, Colombia

    OpenAIRE

    Robert Ferrel

    2013-01-01

    ResumenDiversas investigaciones han señalado una estrecha relación entre el síndrome de quemarse por el trabajo o de desgaste profesional (burnout) y los problemas de salud, relacionando al burnout como una de las causas del deterioro de las condiciones de trabajo y fuente de la accidentalidad y absentismo laboral, especialmente en profesionales de la salud y la educación. La presente investigación tuvo como objetivo establecer y describir la existencia del síndrome de burnout en médicos espe...

  18. Análisis de los factores que inciden en el desgaste de los órganos de trabajo de los aperos de labranza

    Directory of Open Access Journals (Sweden)

    Miguel Herrera Suárez

    2010-01-01

    Full Text Available En el trabajo se analizan los factores que mayor incidencia tienen en el desgaste de los órganos de trabajo de los aperos de labranza. En el mismo se recurre al método de encuesta a expertos para la definición de estos factores o causas, además de la confección de un diagrama causa-efecto que representa en forma simplificada el problema a investigar. También se emplea el método de entrevista-cuestionario para obtener la información necesaria, al personal responsabilizado con las reparaciones, mantenimiento y parqueo de estos aperos. Los resultados muestran que, según el criterio concordante de los expertos las condiciones de explotación, mantenimiento, reparación y de parqueo, así como, las características constructivas de los aperos de labranza, son las causas o factores que mayor incidencia tienen en el desgaste de sus órganos de trabajo. Finalmente el análisis del comportamiento de estos factores en la empresa objeto de estudio muestra que, la mayoría de las causas que provocan el desgaste son controlables por el hombre, pues las mismas están originadas por factores organizativos, tecnológicos y materiales, sobre los cuales se puede incidir para minimizar los daños que ocasiona esta problemática. Los resultados son la base fundamental para la posterior toma de decisiones en función de solucionar el problema investigado.

  19. Adaptive fuzzy sliding mode control of uncertain nonlinear systems Controle por modos deslizantes nebuloso adaptativo de sistemas incertos não-lineares

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    Wallace Moreira Bessa

    2010-04-01

    Full Text Available This paper presents a detailed discussion about the convergence properties of a variable structure controller for uncertain single-input-single-output nonlinear systems (SISO. The adopted approach is based on the sliding mode control strategy and enhanced by an adaptive fuzzy algorithm to cope with modeling inaccuracies and external disturbances that can arise. The boundedness of all closed-loop signals and the convergence properties of the tracking error are analytically proven using Lyapunov's direct method and Barbalat's lemma. This result corrects flawed conclusions previously reached in the literature. An application of this adaptive fuzzy sliding mode controller to a second-order nonlinear system is also presented. The obtained numerical results demonstrate the improved control system performance.Este trabalho apresenta uma discussão detalhada acerca das propriedades de convergência de um controlador à estrutura variável para sistemas incertos com uma entrada e uma saída (SISO. A abordagem adotada baseia-se na estratégia de controle por modos deslizantes e incorpora um algoritmo difuso adaptativo para compensar imprecisões de modelagem e perturbações externas que possam ocorrer. A limitação de todos os sinais do sistema em malha-fechada e as propriedades de convergência do erro de rastreamento são demonstradas analiticamente através do método direto de Liapunov e do lema de Barbalat. Este resultado corrige conclusões errôneas apresentadas anteriormente na literatura. Uma aplicação do controlador por modos deslizantes difuso adaptativo em um sistema não-linear de segunda ordem também é discutida. Os resultados obtidos numericamente confirmam o desempenho do controlador.

  20. Resistencia a la corrosión y desgaste de recubrinnientos deTiN obtenidos por PVD

    Directory of Open Access Journals (Sweden)

    Conde, A.

    2005-12-01

    Full Text Available Surface hardening techniques for metallic alloys are widely used to achieve layers of very high hardness and corrosion and wear resistance. In the present paper TiN coatings are obtained by PVD on a tool steel. The films are characterized by SEM, X-ray diffraction and XPS. Corrosion behaviour in NaCl solution showed the importance of the presence of defects on the PVD coating due to the different electrochemical behaviour of the steel base. Pin-on-disk measurements at approximately 40% RH against a corundum (Al2O3 ball showed a significant decrease in the wear rate compared with the results for the standard tool steel.

    Los tratamientos de endurecimiento superficial de aleaciones metálicas se utilizan para lograr capas de muy elevada dureza, resistencia a la corrosión y desgaste. En este trabajo, se estudia el comportamiento de recubrimientos de TiN obtenidos mediante PVD sobre aceros de herramientas. Las capas obtenidas se caracterizan mediante microscopía electrónica de barrido, difracción de rayos X y XPS. Se analiza el comportamiento frente a la corrosión de las capas protectoras, así como la influencia del substrato en su comportamiento en soluciones de NaCl. Finalmente, se realizan ensayos de desgaste por deslizamiento en seco mediante la técnica de pin-on-disk, comprobándose la mayor resistencia de estas capas.

  1. DESGASTE POR ABRASIÓN DEL ACERO API 5L X65 REVESTIDO CON NIOBIO POR ASPERSIÓN TÉRMICA A PLASMA Y CON INCONEL 625 POR SOLDADURA

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    JOSE MATOS

    2012-01-01

    Full Text Available El objetivo de este trabajo fue evaluar y caracterizar el comportamiento mecánico en desgaste del acero API 5L X65, revestido con niobio en comparación al desempeño del revestimiento de la aleación de inconel 625 empleados en la industria de petróleo y gas. El revestimiento de niobio fue obtenido por el proceso de aspersión térmica a plasma de arco no transferido y el revestimiento inconel 625 por soldadura con electrodo revestido. La resistencia al desgaste por abrasión fue evaluada según la norma Petrobras N-2568, en un tribómetro CTER, la rugosidad y el volumen de material desgastado se determinó a través de perfilometría y la dureza de los revestimientos por microscopia Vickers. Los revestimientos obtenidos fueron caracterizados respecto a su morfología por microscopia electrónica de barrido (MEB y microscopía óptica (MO. La mayor dureza del revestimiento con niobio obtenido puede haber contribuido a reducir la tasa de desgaste en comparación con el revestimiento de inconel 625.

  2. ESTUDO DO DESGASTE DE REVESTIMENTO INTERNO DE UM MOINHO DE BOLAS OPERANDO COM ROCHA FOSFÁTICA

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    André Carlos Silva

    2014-07-01

    Full Text Available O revestimento interno dos moinhos vem tomando maior proeminência devido à sua influência direta na eficiência de moagem e pelo alto custo agregado relacionado ao seu tempo de operação. Uma vez que o desgaste do revestimento não é uniforme, foi realizado o acompanhamento do desgaste do revestimento interno do moinho de bolas (SAG 4,87 x 6,09 m da empresa Vale Fertilizantes S.A. Unidade Catalão-GO. Tal moinho trabalha com rocha fosfática e o monitoramento se deu através de um dispositivo prático visando à determinação do comportamento do desgaste do revestimento ao longo de toda a extensão do moinho, desde a alimentação até a descarga, bem como a variação em um único perfil de uma placa do revestimento. Observou-se que o desgaste não é uniforme tanto ao longo do moinho quanto em um mesmo perfil, indicando que o maior desgaste ocorre nos primeiros e últimos 1,5 metros, com valores muito próximos. Na alimentação do moinho o desgaste específico foi de 0,60 g/t, na descarga de 0,63 g/t e no do centro do moinho de aproximadamente 0,55g/t.

  3. El Síndrome de "Burnout" o el desgaste profesional (II: Estudio empírico de los profesionales gallegos del área de Salud Mental.

    Directory of Open Access Journals (Sweden)

    E Álvarez Gallego

    1991-01-01

    Full Text Available Este trabajo supone una aproximación empírica al síndrome de "Burnout". Para ello se ha tomado un grupo de profesionales gallegos del área de Salud Mental. Los instrumentos utilizados para operativizar las variables han sido, el Maslach Burnout Inventory (M.B.I. de Maslach and Jackson para la medición del "desgaste profesional" y la Escala de Clima Social en el Trabajo (W.E.S. de R.H. Moos. Los resultados muestran la presencia de un considerable cansancio emocional como resultado del contexto laboral, y dentro de los factores intervinientes, es la variable presión la que de manera más clara influye en el surgimiento del stress crónico en los profesionales de Salud Mental

  4. Cirugía de rescate tras fracaso de osteosíntesis con tornillo-placa deslizante en fracturas pertrocantéreas de fémur

    OpenAIRE

    Estrems Díaz, Vicente

    2015-01-01

    Introducción: El fracaso de la osteosíntesis constituye una complicación de efectos devastadores en el paciente anciano con fractura de cadera. En el caso de los pacientes tratados mediante tornillo-placa deslizante (DHS), la migración intraarticular del tornillo cefálico o “cut-out” constituye la complicación mecánica más frecuente. Las opciones de rescate tras el cut-out incluyen la revisión de la osteosíntesis o bien el reemplazo del fémur proximal mediante artroplastia total o parcial de ...

  5. Estudio del desgaste de aceros rápidos pulvimetalúrgicos M3/2 reforzados con carburo de niobio mediante el ensayo pin-on-disk

    Directory of Open Access Journals (Sweden)

    Candela, N.

    2005-10-01

    Full Text Available In this work, composite materials M3/2 high-speed steel reinforced with 5,10 and 15 %, in volume, of niobium carbide have been obtained to improve the wear behaviour. The materials were prepared by powder metallurgy using steel and carbide powders that were mechanically ball milled in a planetary mill, and then hot isostatically pressed. The wear behaviour was determined by pin-on-disk tests. The materials present a microstructure consisting of grains with a few microns in size and fine MC and M6C particles homogeneously dispersed in its interior. In the case of reinforced materials, reinforcing carbides particles are placed mainly at the surface of the prior steel powder particle boundaries. The wear behaviour was evaluated from friction and wear coefficients, and also from weight loss. The addition of niobium carbide improves the wear properties of the tool steel in both martensitic and tempered conditions. A decrease of the weight loss and the wear coefficient is observed with increasing volume fraction of NbC

    En este trabajo se han preparado materiales compuestos de acero rápido M3/2 reforzado con un 5, un 10 y un 15 % en volumen de carburos de niobio con el objeto de mejorar sus propiedades mecánicas y resistencia al desgaste. La fabricación de los distintos materiales compuestos se realizó mediante molienda mecánica de polvo de acero rápido y carburo en un molino de alta energía, y compactación isostática en caliente. El comportamiento al desgaste se determinó a través de ensayos pin-on-disk. El material de partida presenta una microestructura con un tamaño de grano de pocas mieras y pequeños carburos MC y M6C homogéneamente dispersos en su interior. En el caso de los materiales reforzados, las partículas reforzantes de carburo se sitúan mayoritariamente sobre la superficie de las partículas originales de polvo de acero. El comportamiento al desgaste se evaluó a partir del coeficiente

  6. Análisis experimental del desgaste entre UHMWPE y acero inoxidable 316l empleados en la manufactura de prótesis coxofemorales

    Directory of Open Access Journals (Sweden)

    Ricardo Gustavo Rodríguez Cañizo

    2010-10-01

    Full Text Available Título en inglés: Experimental wear analysis of UHMWPE and stainless 316l used in the manufacturing of coxofemoral prosthesis. Resumen La causa más común de falla en prótesis coxofemorales es el aflojamiento entre los componentes que conforman el sistema, de manera específica la copa acetabular y la cabeza femoral. En esta investigación se presenta un análisis tribológico del desgaste en los componentes mencionados, ya que cuando las superficies en contacto se desgastan, la funcionalidad mecánica del sistema se compromete, debido al cambio de geometría de los mismos, dando como resultado un juego mecánico entre la copa y la cabeza. Los materiales considerados en este estudio son el polietileno de ultra elevado peso molecular (UHMWPE, por sus siglas en inglés para la copa acetabular, y acero inoxidable 316L para la cabeza femoral. Esta combinación de materiales representa hoy en día la recomendación más usual por parte de los cirujanos para pacientes de la tercera edad. La tasa anual de desgaste se determinó de manera experimental y se cuantificó la cantidad de material desprendido durante el contacto. Se establecieron las condiciones de carga de forma analítica, considerando las que actúan sobre la cabeza femoral a lo largo del área de desgaste durante la marcha humana. Posteriormente, se realizó el análisis experimental de desgaste utilizando una máquina tribológica de configuración perno-sobre-disco (pin-on-disk, diseñada de manera específica para este estudio. Las pruebas para determinar la pérdida volumétrica de los componentes se realizaron bajo tres condiciones de operación: en seco, lubricada con agua destilada y lubricada con suero bovino. El marco experimental considerado consistió en pernos de UHMWPE sobre discos de acero inoxidable 316L simulando el desgaste equivalente a diez años de uso de la prótesis. Finalmente, de los resultados obtenidos se puede establecer que el desgaste y la cantidad de part

  7. Scratch resistance of SiO{sub 2} and SiO{sub 2} - ZrO{sub 2} sol-gel coatings on glass-ceramic obtained by sintering; Resistencia al desgaste de recubrimientos sol-gel de SiO{sub 2} y SiO{sub 2} - ZrO{sub 2} sobre materiales vitroceramicos obtenidos por sinterizacion

    Energy Technology Data Exchange (ETDEWEB)

    Soares, V. O.; Soares, P.; Peitl, O.; Zanotto, E. D.; Duran, A.; Castro, Y.

    2013-10-01

    The sol-gel process is widely used to obtain coatings on glass-ceramic substrates in order to improve the scratch and abrasion resistance, also providing a bright and homogeneous appearance of a glaze avoiding expensive final polishing treatments. This paper describes the preparation of silica and silica / zirconia coatings by sol-gel method on Li{sub 2}O-Al{sub 2}O3-SiO{sub 2} (LAS) glassceramic substrates produced by sintering. The coatings were deposited by dip-coating on LAS substrates and characterized by optical microscopy and spectral ellipsometry. On the other hand, hardness and elastic modulus, coefficient of friction and abrasion and scratch resistance of the coatings were determined and compared with the substrate properties. Coatings deposited on LAS glass-ceramic confere the substrate a bright and homogeneous aspect, similar to a glaze, improving the appearance and avoiding the final polishing. However these coatings do not increase the scratch resistance of the substrate only equaling the properties of the glass-ceramic. (Author)

  8. ESTUDO DO DESGASTE DE REVESTIMENTO INTERNO DE UM MOINHO DE BOLAS OPERANDO COM ROCHA FOSFÁTICA

    OpenAIRE

    André Carlos Silva; Elenice Maria Schons Silva; Tulyo Maia Silva

    2014-01-01

    O revestimento interno dos moinhos vem tomando maior proeminência devido à sua influência direta na eficiência de moagem e pelo alto custo agregado relacionado ao seu tempo de operação. Uma vez que o desgaste do revestimento não é uniforme, foi realizado o acompanhamento do desgaste do revestimento interno do moinho de bolas (SAG 4,87 x 6,09 m) da empresa Vale Fertilizantes S.A. Unidade Catalão-GO. Tal moinho trabalha com rocha fosfática e o monitoramento se deu através de um dispositivo prát...

  9. Estudio tribológico ante condiciones de desgaste micro-abrasivo de recubriminetos duros delgados

    OpenAIRE

    Marquilles, Albert

    2007-01-01

    Muchos componentes metálicos se ven sometidos a condiciones que les producen fenómenos de degradación tales como corrosión, desgaste o fatiga. Para mitigar estos efectos se han desarrollado tratamientos y recubrimientos que se aplican sobre la superficie sometida a estas condiciones y que se desea proteger. Cuando se tiene un sistema sustrato-recubrimiento o incluso una superficie sin recubrimiento, y se quiere caracterizar desde el punto de vista tribológico, se puede em...

  10. Desempenho de filmes de diamante no desgaste de matrizes de corte em WC-Co

    OpenAIRE

    Oliveira, Francisco José Dias

    2008-01-01

    O presente trabalho consistiu fundamentalmente na optimização de ferramentas de corte e de desgaste para telas abrasivas. Para o efeito desenvolveu-se uma ferramenta de corte multi-furo que permitisse cortar e furar simultaneamente dois discos de tela abrasiva. De modo a aumentar o tempo de vida das ferramentas de corte analisouse em detalhe o desempenho de filmes de diamante em matrizes de corte em substrato de WC-Co. Face aos resultados obtidos relativos à adesão do fil...

  11. Establecimiento de condiciones óptimas de taladrado en función del desgaste de herramienta en estructuras híbridas

    OpenAIRE

    Aragón Meléndez, José María

    2015-01-01

    Se realiza un estudio en el desgaste de herramientas en una serie de herramientas que han mecanizado planchas de aluminio y fibra de carbono para poder estableces unas buenas condiciones de taladrado para estructuras híbridas.

  12. Psychological exhaustion and disorders of health in psychology students Desgaste psíquico y problemas de salud en estudiantes de psicologia Desgaste psíquico e problemas de saúde em estudantes de psicologia

    Directory of Open Access Journals (Sweden)

    Hugo Figueiredo-Ferraz

    2009-06-01

    Full Text Available El objetivo del estudio fue analizar los niveles de Desgaste psíquico y Desencanto en estudiantes de Psicología, la Sobrecarga y su relación con los Problemas de salud. Participaron 154 estudiantes universitarios de Psicología de 3º (48% y 4º (52% grado. Desgaste psíquico y Desencanto se evaluaron mediante el Cuestionario para la Evaluación del Síndrome de Quemarse por el Trabajo, Problemas de salud mediante una escala de once ítems y Sobrecarga mediante un ítem. Los estudiantes de cuarto percibían significativamente mayores niveles de Sobrecarga, Desgaste psíquico y Desencanto que los de tercero.O objectivo deste estudo foi analisar os níveis de desgaste psíquico e desencanto em estudantes de Psicología, a sobrecarga e a sua relação com os problemas de saúde. Participaram 154 estudantes universitários de Psicologia do 3º (48% e 4º (52% anos. Desgaste psíquico e desencanto foram avaliados mediante o Questionario para la Evaluación del Síndrome de Quemarse por el Trabajo, problemas de saúde mediante uma escala de onze itens e sobrecarga mediante um item. Os estudantes do quarto ano sentiam de maneira significativa maiores níveis de sobrecarga, desgaste psíquico e desencanto que os de terceiro ano.The aim of the study was to examine the levels of Psychological Exhaustion and Disillusionment in students of Psychology, the work overload and its relationship with Disorders of Health. The research participants were 154 university students of Psychology from junior (48% and senior. (52%. Psychological Exhaustion and Disillusionment were analysed with the Spanish Burnout Inventory (SBI, Disorders of Health with an eleven-item scale and Work overload with one item. The students from senior perceived higher Work overload, Psychological Exhaustion and Disillusionment than the students from junior.

  13. Mecanismos de desgaste en materiales compuestos de matriz acero rápido fabricados por técnicas pulvimetalúrgicas

    Directory of Open Access Journals (Sweden)

    Gordo, E.

    2001-04-01

    un molino de alta energía, en seco, a 200 r.p.m., durante 40 h. Después de un recocido de eliminación de tensiones, se siguieron dos vías para la consolidación de los polvos: (1 compactación en matriz y sinterización en vacío y (2 compactación isostática en caliente (HIP. El estudio del comportamiento a desgaste de los materiales se evaluó mediante el método ''pin-ondisc”. Los ensayos se realizaron utilizando como disco el material a ensayar, y como “piri” una bola de alúmina. Los resultados indican que, la consolidación del material por HIP mejora considerablemente su resistencia al desgaste, respecto a la consolidación por sinterizado.

  14. Desgaste de dressadores de ponta única fabricados com diamantes cvd nacionais

    OpenAIRE

    A. Frech Jr.; E. C. Bianchi; R. C. Canarim; P. R. de Aguiar

    2013-01-01

    Neste trabalho, buscou-se observar a atuação de três tipos de diamantes, dois naturais e um sintético, para determinar qual deles apresenta vida útil maior ou com maior desgaste em relação aos demais. A metodologia empregada nesse estudo foi o de dressar um rebolo de óxido de alumínio e, a cada vinte passadas com um avanço da profundidade de dressagem de 40 µm por passada, tirar uma imagem da ponta na posição horizontal e outra na posição vertical deste diamante num microscópio estereoscópio....

  15. Desgaste na mineração: o caso dos corpos moedores

    Directory of Open Access Journals (Sweden)

    Monica Speck Cassola

    2006-06-01

    Full Text Available Os pesquisadores do IPT desenvolveram know-how para correlacionar os resultados laboratoriais de ensaios de desgaste de corpos moedores diretamente à indústria, por meio de constantes pesquisas e trabalhos realizados em parceria com o setor mínero-metalúrgico. Os ensaios padronizados em escala-piloto, com diferentes tipos de bolas de moinho, de ferros fundidos brancos de alto cromo e de aços temperados, nos quais avaliam-se as taxas e os micromecanismos de desgaste destas, fornecem uma correlação quantitativa direta com os resultados industriais. O presente trabalho teve como objetivo a caracterização dos corpos moedores para avaliação desse insumo adquirido de diferentes fornecedores para dar subsídio técnico às unidades de moagem industriais. As principais etapas foram: Determinação das curvas de polarização (avaliação do efeito de corrosão preferencial, Caracterização metalográfica (caracterização química e metalográfica das amostras de bolas e Ensaio de desgaste (avaliação do desgaste dos corpos moedores em unidade-piloto contínua de moagem e classificação. Os resultados obtidos permitiram elaborar uma hierarquia de desempenho técnico.The Division of Metallurgy of IPT has been working for some years in studies of grinding media wear. Tests have been conducted using phosphate and iron ores, as well as quartz sand, representing the range of abrasivity usually found in practical applications.The pilot plant scale testing program was carried out testing balls made of steel and of different types of high chromium white cast irons, evaluating the wear rates and analyzing the wear micromechanisms of these balls. In that work, the objective was the validation of the wear evaluation method, comparing the results obtained in an industrial ball mill, grinding phosphate ore with those obtained running continuously the pilot-scale laboratory mill. Quantitative correlations between the perfomance of the grinding media in

  16. Desgaste abrasivo de cuchillas de arado rotativo en un suelo franco arenoso

    OpenAIRE

    PÉREZ G., WILMER; González, Hugo; Toro, Alejandro

    2010-01-01

    Se relacionó la tasa de desgaste de cuchillas de arado rotativo con la velocidad de giro de las mismas. El trabajo de campo se llevó a cabo en el Centro agropecuario Paysandú (corregimiento de Santa Elena – Medellín, en un suelo franco arenoso). Se seleccionó una velocidad del tractor de 2 km/h y profundidad de trabajo de 120 mm; el rotor se trabajó con tres velocidades de giro: 141, 177 y 251 rpm. La masa perdida promedio en campo fue de 0.67 g; 1.35 g y 2.33 g respectivamente para cad...

  17. Desgaste abrasivo de cuchillas de arado rotativos en un suelo franco arenoso

    OpenAIRE

    Pérez Galeano, Wilmer Alonso; González Sánchez, Hugo Alberto; Toro Betancur, Alejandro Octavio

    2010-01-01

    resumen: Se relacionó la tasa de desgaste de cuchillas de arado rotativo con la velocidad de giro de las mismas. El trabajo de campo se llevó a cabo en el Centr agropecuario Paysandú (corregimiento de Santa Elena – Medellín, en un suelo franco arenoso). Se seleccionó una velocidad del tractor de 2 km/h y profundidad de trabajo de 120 mm; el rotor se trabajó con tres velocidades de giro: 141, 177 y 251 rpm. La masa perdida promedio en campo fue de 0.67 g; 1.35 g y 2.33 g respectivamente ...

  18. Análise da microestrutura e da resistência ao desgaste de revestimento duro utilizado pela indústria sucroalcooleira Analysis of microstructure and wear strength of hardfacing used by the sugar and alcohol industry

    Directory of Open Access Journals (Sweden)

    Aldemi Coelho Lima

    2009-06-01

    Full Text Available O setor sucroalcooleiro tem apresentado um expressivo crescimento nos últimos anos no Brasil, entretanto, a manutenção das indústrias apresenta um elevado custo devido à perda de metal dos equipamentos por mecanismos de desgaste. O objetivo deste trabalho é avaliar a resistência ao desgaste abrasivo e a microestrutura de revestimentos duros depositados em camada única. Foram utilizados quatro tipos de consumíveis utilizados na indústria sucroalcooleira: um eletrodo revestido da liga FeCrC de 4,0 mm de diâmetro e três arames tubulares autoprotegidos de 1,6 mm de diâmetro, de ligas FeCrC, FeCrCNb, FeCrCTiMo. O metal de base utilizado foi um aço SAE 1020. As soldagens com os arames tubulares foram efetuadas no modo de transferência por curto-circuito, com mesmos valores de corrente e tensão de soldagem. Para o ensaio de desgaste utilizou-se o abrasômetro Roda de Borracha, segundo a norma ASTM G65-91. Os corpos de prova de desgaste foram retirados da região central das chapas de testes e da mesma região retirou-se dois conjuntos de amostras para análise microestrutural (microscopia ótica. Os resultados dos ensaios com a roda de borracha mostrou que a liga FeCrCNb apresenta maior resistência ao desgaste, seguida do eletrodo revestido e com pior desempenho a liga FeCrCMoTi e a liga FeCrC. A liga FeCrC (tanto para o eletrodo revestido como para o arame tubular apresentou microestrutura formada por carbonetos primários M7C3 distribuídos em uma matriz de menor dureza; a liga contendo Nb apresentou microestrutura similar além da presença de carbonetos NbC; por sua vez, a liga com adição de Ti e Mo apresentou a presença de grandes carbonetos primários de titânio.The Brazilian sugar/alcohol sector presented expressive growth in recent years. However, maintenance cost is high due to metallic losses by wear. This paper studies the application of hardfacing by flux cored arc welding on the wear resistance and microstructure of

  19. Estudio del comportamiento de los recargues multicapas de depósitos soldados de fundición blanca al cromo

    OpenAIRE

    R. Collazo-Carceller; H. López Salinas

    2009-01-01

    Se determina la influencia de los parámetros Energía introducida (Hi), Número de capas (Nc) y Ancho del depósito (Ad), en la morfología y el incremento de la resistencia al desgaste abrasivo de capas depositadas sobre acero 1020 utilizando el electrodo de fundición blanca al cromo UTP Ledurit – 61. Empleando la microscopia óptica se identificaron y cuantificaron las fases presentes, analizando su efecto en el desgaste. Siendo determinante la influencia de la inclinación de las dendritas y su...

  20. Desgaste interproximal e suas implicações clínicas Interdental stripping and it's clinical implications

    OpenAIRE

    Osmar Aparecido Cuoghi; Rodrigo Castellazzi Sella; Fernanda Azambuja Macedo; Marcos Rogério de Mendonça

    2007-01-01

    INTRODUÇÃO: o alinhamento dentário correto, bem como sua estabilidade, representam objetivos importantes do tratamento ortodôntico. O apinhamento na região anterior é uma anomalia de posição dentária comum e para obter sua correção as opções clínicas disponíveis para o ortodontista são as extrações dentárias, a expansão do arco dentário ou os desgastes interproximais. Os desgastes freqüentemente são indicados, mas existem questionamentos quanto às indicações, técnicas e condições pré e pós-tr...

  1. Construcción y puesta en funcionamiento de una máquina de cilindros cruzados para la evaluación del desgaste adhesivo

    Directory of Open Access Journals (Sweden)

    Sandro Báez P.

    2004-01-01

    Full Text Available En esta investigación se evaluó el desgaste adhesivo de cuatro metales (fundición gris, latón 60- 40, bronce fosforado y un acero AISI 1020, en un tribómetro de cilindros cruzados, bajo la norma ASTM G- 83-96. Para lograr dicho objetivo, se diseñó, construyó y puso en marcha una máquina de cilindros cruzados, la cual contiene dos probetas cilíndricas (una estática y una giratoria, que fueron maquinadas y pulidas con lijas hasta obtener una superficie con una rugosidad máxima de 0.34 mm. Con el volumen de metal perdido por cada material, se calculó su velocidad promedio de corrosión y se determinó el coeficiente de desgaste. Además, se realizaron ensayos a cada material, para determinar los perfiles de desgaste respectivos (Gramos de metal perdido vs Tiempo. En este trabajo se obtuvo un coeficiente de variación máximo, entre los cuatro metales, de 4.3%, indicando una buena correlación de los resultados obtenidos. Los coeficientes de desgaste se consideraron aceptables, puesto que sus valores corresponden y son del mismo orden a los establecidos en la literatura. Igualmente, los perfiles del desgaste mostraron las tres etapas del proceso, similares a los encontrados en otros trabajos realizados.

  2. Estudio del comportamiento de los recargues multicapas de depósitos soldados de fundición blanca al cromo // Study of the hard facing weld behavior in deposits of white chromium steels.

    OpenAIRE

    R. Collazo-Carceller; H López-Salinas

    2009-01-01

    Se determina la influencia de los parámetros Energía introducida (Hi), Número de capas (Nc) yAncho del depósito (Ad), en la morfología y el incremento de la resistencia al desgaste abrasivo decapas depositadas sobre acero 1020 utilizando el electrodo de fundición blanca al cromo UTPLedurit – 61. Empleando la microscopia óptica se identificaron y cuantificaron las fases presentes,analizando su efecto en el desgaste. Siendo determinante la influencia de la inclinación de lasdendritas y su posic...

  3. Produtivismo e precariedade subjetiva na universidade pública: o desgaste mental dos docentes

    Directory of Open Access Journals (Sweden)

    Marcia Hespanhol Bernardo

    2014-01-01

    Full Text Available Nos últimos anos, tem-se observado cada vez mais características típicas de mercado presentes na universidade pública. No Brasil, o aspecto com maior destaque nas publicações é o "produtivismo acadêmico", que tem como mote a ênfase na quantidade de produções bibliográficas. Neste artigo, busca-se discutir as características desse modelo, partindo-se do pressuposto que ele conduza a uma situação de precariedade subjetiva para os docentes. Para tal, apresenta-se o resultado de uma pesquisa qualitativa com professores de uma universidade pública, realizada por meio de entrevistas reflexivas. Os resultados indicam que a precariedade subjetiva vivenciada leva a um desgaste mental, o qual, por sua vez, pode ter como consequência o sofrimento psíquico e o adoecimento. Apesar de se mostrarem conscientes do processo que vivenciam, alguns docentes buscam adotar táticas individuais cotidianas de "sobrevivência", enquanto as estratégias coletivas com vistas à transformação são pouco enfatizadas.

  4. Desgaste de dressadores de ponta única fabricados com diamantes cvd nacionais

    Directory of Open Access Journals (Sweden)

    A. Frech Jr.

    2013-12-01

    Full Text Available Neste trabalho, buscou-se observar a atuação de três tipos de diamantes, dois naturais e um sintético, para determinar qual deles apresenta vida útil maior ou com maior desgaste em relação aos demais. A metodologia empregada nesse estudo foi o de dressar um rebolo de óxido de alumínio e, a cada vinte passadas com um avanço da profundidade de dressagem de 40 µm por passada, tirar uma imagem da ponta na posição horizontal e outra na posição vertical deste diamante num microscópio estereoscópio. Após isso, o dressador foi recolocado na retificadora para a realização de uma nova dressagem. O critério para o fim do ensaio foi o faiscamento, gerado pelo contato do rebolo com a base do dressador, que indicou o fim do contato do diamante com o rebolo. Após os ensaios, foram calculadas as áreas gastas de cada diamante de acordo com cada imagem obtida por meio do auxilio de um software gráfico. Os dados foram então dispostos em gráficos.

  5. Cargas e desgastes de trabalho vivenciados entre trabalhadores de saúde em um hospital de ensino Descripción de cargas de trabajo y el desgaste experimentado entre trabajadores de salud en un hospital universitario Description of workloads and fatigue experienced among health workers in a teaching hospital

    Directory of Open Access Journals (Sweden)

    Leni de Lima Santana

    2013-03-01

    Full Text Available Estudo exploratório, de caráter descritivo e de abordagem quantitativa, alicerçado nas categorias "processo de trabalho", "cargas de trabalho" e "desgaste" em um hospital de ensino em Curitiba, região sul do Brasil. Neste artigo, são caracterizadas as cargas e os desgastes vivenciados em um hospital universitário, captados pelo estudo prévio intitulado "Sistema de monitoramento da saúde do trabalhador de enfermagem" (SIMOSTE. Os resultados demonstram que o gênero feminino foi o mais acometido (85,9%; os profissionais mais afetados foram os auxiliares de enfermagem (53,1%. O maior número de afastamentos ocorreu por doenças do sistema osteoarticular (25,2% e, dentre as cargas apresentadas, as mais expressivas foram as mecânicas e fisiológicas, com 33,06%, cada. Estes resultados poderão subsidiar estratégias de intervenção nas políticas direcionadas à saúde do trabalhador, para assegurar uma melhor qualidade de vida a este profissional e, por consequência, promover melhorias na qualidade da assistência prestada ao usuário.Estudio exploratorio, descriptivo y cuantitativo, basado en el proceso de trabajo, las cargas de trabajo y el desgaste en un hospital universitario en Curitiba, sur de Brasil. En este artículo se caracteriza la carga y el estrés experimentado en un hospital universitario, planteada por un estudio previo titulado "Sistema de vigilancia de la salud de los trabajadores de enfermería". Los resultados muestran que las mujeres (85,9% y los auxiliares de enfermería eran los profesionales más afectados (53,1%. El mayor número de ausencia del trabajo se debieron a enfermedades del sistema musculoesquelético (25,2% y entre los cargos presentados, los más significativos fueron el mecánico y el fisiológico con el 33,06% cada uno. Estos resultados pueden apoyar las estrategias de intervención en las políticas dirigidas a la salud de los trabajadores, para garantizar una mejor calidad de vida a este trabajo y

  6. RailScan – desenvolvimento de software para a detecção e caracterização de desgaste ondulatório em ferrovias

    OpenAIRE

    Gomes, Rui Pedro de Almeida

    2010-01-01

    Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Electrotécnica e de Computadores Desgaste ondulatório é um fenómeno que está presente nos trilhos das vias-férreas, sob a forma de ondulações. Pode ser classificado como desgaste ondulatório de onda curta, apresentado ondulações que variam entre 3 e 10 centímetros, ou desgaste ondulatório de onda longa, que apresenta ondulações entre os 10 e os 10...

  7. Control activo de vibraciones en estructuras tipo edificio sometidas a sismos utilizando múltiple retroalimentación positiva de la posición y modos deslizantes

    Directory of Open Access Journals (Sweden)

    Josué Enríquez-Zárate

    2014-01-01

    Full Text Available Este trabajo considera el análisis estructural y dinámico de un a estructura tipo edificio de tres pisos con un absorbedor de v ibraciones pasivo/activo. La base de la estructura se perturba con un gene rador de vibraciones, proporcionando fuerzas de excitación y ru ido emulando transporte terrestre, trenes subterráneos y sismos, c omunes en la Ciudad de México. Se considera un registro sísmico real de magnitud 8.1Mw, conteniendo algunas frecuencias resonantes de l a estructura. La estructura mecánica se modela con la metodolog ía de Euler-Lagrange y se valida con técnicas de análisis modal exper imental. El esquema de control activo se diseña para atenuar la respuesta vibratoria del sistema, ocasionada por las fuerzas armónicas qu e actúan en la base, empleando múltiple retroalimentación posit iva de la posición y control por modos deslizantes para mejorar la robust ez del sistema en lazo cerrado y atenuar tres modos de vibració n. Resultados en simulación y experimentales describen el desempeñ o del sistema completo.

  8. Estudio del comportamiento de los recargues multicapas de depósitos soldados de fundición blanca al cromo // Study of the hard facing weld behavior in deposits of white chromium steels.

    Directory of Open Access Journals (Sweden)

    R. Collazo-Carceller

    2009-05-01

    Full Text Available Se determina la influencia de los parámetros Energía introducida (Hi, Número de capas (Nc yAncho del depósito (Ad, en la morfología y el incremento de la resistencia al desgaste abrasivo decapas depositadas sobre acero 1020 utilizando el electrodo de fundición blanca al cromo UTPLedurit – 61. Empleando la microscopia óptica se identificaron y cuantificaron las fases presentes,analizando su efecto en el desgaste. Siendo determinante la influencia de la inclinación de lasdendritas y su posición con respecto a 90° en el incremento de la resistencia al desgaste abrasivo.Se caracterizaron los posibles mecanismos de daño superficial provocado por desgaste abrasivoempleando la microscopia electrónica de barrido. Se propusieron modelos lineales paracorrelacionar la influencia de la cantidad, tamaño, dispersión de los carburos y el ángulo deinclinación de las dendritas, en el incremento de la resistencia al desgaste.Palabras claves: morfología, desgaste abrasivo, parámetros de soldadura, dendritas, modelos.__________________________________________________________________________AbstractThe influence of different parameters in layer morphology and abrasion resistance of Fe-Cr-Celectrodes UTP Ledurit – 61 on steel 1020 was studied. Introduced Energy (Hi, Number of Layers(Nc, and Deposit Width (Ad were the main parameters considered. The metallographicidentification and quantification of metal phases and the determination of their effect in abrasionresistance were made with optical microscopy. The abrasive wear test characterized by scanningelectron microscopy, defines a possible mechanism of surface damage. It was found that the angleformed between a normal line to the surface and the dendrite inclination is directly related withthe increment of wear resistance. Lineal models that correlate wear resistance with quantity, size,and carbide dispersion and dendrite angle inclination were also developed.Key words: morphology, abrasive

  9. Síndrome de desgaste profesional en médicos internos y residentes. Hospital Universitario del Valle, Cali, 2002.

    OpenAIRE

    Diana P. Henao; Julián A. Herrera; César A. Guevara

    2009-01-01

    INTRODUCCIÓN: El síndrome de desgaste profesional (SDP) es un transtorno adaptativo crónico que altera la calidad de vida de la persona y produce un efecto negativo en la calidad de la prestación de servicios de salud. OBJETIVOS: Determinar la prevalencia e intensidad del SDP, sus características y su asociación con alteraciones en la dinámica familiar en médicos internos y residentes del Hospital Universitario del Valle en Cali, Colombia. METODOLOGÍA: Estudio descriptivo transversal; mediant...

  10. CARGAS PSÍQUICAS DE TRABALHO E DESGASTE DOS TRABALHADORES DE ENFERMAGEM DE HOSPITAL DE ENSINO DO PARANÁ, BRASIL

    OpenAIRE

    Iara Aparecida de Oliveira Secco; Maria Lúcia do Carmo Cruz Robazzi; Francisco Eugênio Alves de Souza; Denise Sayuri Shimizu

    2010-01-01

    Este estudio cualitativo tuvo como objetivo analizar las cargas psíquicas de trabajo del equipo de enfermería de un hospital escuela y su relación con los desgastes de esos trabajadores. El materialismo histórico fue utilizado como referencial metodológico. Fueron realizadas entrevistas semi-estructuradas con siete gerentes de enfermería. Los hallazgos evidenciaron que las cargas psíquicas se relacionan a los problemas inherentes a la actividad, debido a la convivencia con el dolor y la muert...

  11. Análisis mecánico y tribológico de los recubrimientos fe-cr-ni-c y ni-al-mo

    Directory of Open Access Journals (Sweden)

    JORGE E. MUÑOZ

    2007-01-01

    Full Text Available En este trabajo de investigación se evaluaron dos recubrimientos aplicados por medio de la técnica de rociado térmico por combustión, la aleación: Ni=89%, Al = 5,5%, Mo=5,5% y la aleación Fe=81,8%, Cr=16%, Ni=2%, C=0,2. La preparación superficial de las probetas se realizó usando chorro de arena. Se realizaron pruebas de resistencia al cortante, adherencia, desgaste abrasivo, desgaste por deslizamiento y flexión en cuatro puntos. El recubrimiento Fe-Cr-Ni-C presentó menor pérdida de masa, tanto para desgaste abrasivo como para el desgaste por deslizamiento. La multicapa presentó una mayor porosidad en el recubrimiento Ni-Al- Mo usado como capa base y la capa exterior de Fe-Cr-Ni-C presentó mayor cantidad de partículas no fundidas y óxidos. La falla ocurrida en el ensayo de adherencia para las probetas con recubrimiento multicapa fue de característica adhesiva y cohesiva. El esfuerzo en el que se presenta la fisura por flexión en el recubrimiento multicapa disminuyó con el aumento del espesor

  12. Estudio del comportamiento de los recargues multicapas de depósitos soldados de fundición blanca al cromo

    Directory of Open Access Journals (Sweden)

    R. Collazo-Carceller

    2009-05-01

    Full Text Available Se determina la influencia de los parámetros Energía introducida (Hi, Número de capas (Nc y Ancho del depósito (Ad, en la morfología y el incremento de la resistencia al desgaste abrasivo de capas depositadas sobre acero 1020 utilizando el electrodo de fundición blanca al cromo UTP Ledurit – 61. Empleando la microscopia óptica se identificaron y cuantificaron las fases presentes, analizando su efecto en el desgaste. Siendo determinante la influencia de la inclinación de las dendritas y su posición con respecto a 90° en el incremento de la resistencia al desgaste abrasivo. Se caracterizaron los posibles mecanismos de daño superficial provocado por desgaste abrasivo empleando la microscopia electrónica de barrido. Se propusieron modelos lineales para correlacionar la influencia de la cantidad, tamaño, dispersión de los carburos y el ángulo de inclinación de las dendritas, en el incremento de la resistencia al desgaste.The influence of different parameters in layer morphology and abrasion resistance of Fe-Cr-C electrodes UTP Ledurit – 61 on steel 1020 was studied. Introduced Energy (Hi, Number of Layers (Nc, and Deposit Width (Ad were the main parameters considered. The metallographic identification and quantification of metal phases and the determination of their effect in abrasion resistance were made with optical microscopy. The abrasive wear test characterized by scanning electron microscopy, defines a possible mechanism of surface damage. It was found that the angle formed between a normal line to the surface and the dendrite inclination is directly related with the increment of wear resistance. Lineal models that correlate wear resistance with quantity, size, and carbide dispersion and dendrite angle inclination were also developed.

  13. Prevalencia del síndrome de desgaste en médicos residentes costarricenses Prevalence of Burnout Syndrome in Costarican Physician Residents

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    Ricardo Millán-González

    2009-04-01

    Full Text Available Justificación y objetivo: determinar las características sociodemográficas del síndrome de desgaste en médicos residentes en Costa Rica durante el 2007 y validar localmente la escala de Maslach. Metodología: investigación aplicada, descriptiva y de corte transversal, en la que participaron 121 sujetos que cursaban primer y tercer año de las siguientes especialidades que imparte el CENDEISSS: anestesiología y recuperación, especialidades médicas y quirúrgicas, ginecología y obstetricia, pediatría y psiquiatría. Se aplicó el Maslach Burnout Inventory-Human Services Survey (versión validada en español y una ficha de datos sociodemográfica que incluía especialidad médica, sede de residencia, sexo, estado civil, número de hijos, edad de los participantes, frecuencia mensual de guardias y año cursado de residencia. Resultados: El análisis final detectó alto agotamiento emocional en mujeres y en residentes de pediatría; bajo agotamiento emocional en quienes realizan en promedio 4 guardias por mes y en residentes de geriatría y psiquiatría; alta despersonalización en hombres; baja despersonalización en residentes de geriatría y medicina familiar así como en personas unidas; bajos niveles de realización personal en personas unidas; el síndrome de desgaste como tal fue mayor en mujeres, que cursaban el tercer año, sujetos unidos, personas con hijos, menores de 30 años y residentes de las especialidades médicas. Adicionalmente se validó la utilización de la escala en Costa Rica. Conclusión: existen subgrupos de médicos residentes que se encuentran en riesgo de presentar el síndrome de desgaste profesional o elevadas puntuaciones en algunas de sus 3 dimensiones. Algunos de ellos podrían ser propios del personal que mantiene una carga académica y laboral al mismo tiempo. Este hecho debe ser tomado en cuenta cuando se planifican las estrategias de bienestar mental en el sector salud.Background and aim: to determine

  14. Estudio comparativo in vitro de la eficacia de cinco técnicas mecanizadas de desgaste dentario interproximal. Análisis con microtopografía y microscopía electrónica de barrido

    OpenAIRE

    Braga Pereira, Pedro Jorge

    2013-01-01

    Introducción: El desgaste dentario interproximal con fines terapéuticos es un procedimiento habitual en la Ortodoncia contemporánea. En la actualidad persisten las dudas sobre la eficacia y consecuencias para el esmalte de las diferentes técnicas de desgaste dentario interproximal. Objetivo: Asumiendo la hipótesis de que a mayor rugosidad superficial del esmalte pueden aparecer mayores problemas dentales, nuestro objetivo ha sido evaluar la rugosidad superficial del esmalte tras el desga...

  15. Desgaste interproximal e suas implicações clínicas Interdental stripping and it's clinical implications

    Directory of Open Access Journals (Sweden)

    Osmar Aparecido Cuoghi

    2007-06-01

    Full Text Available INTRODUÇÃO: o alinhamento dentário correto, bem como sua estabilidade, representam objetivos importantes do tratamento ortodôntico. O apinhamento na região anterior é uma anomalia de posição dentária comum e para obter sua correção as opções clínicas disponíveis para o ortodontista são as extrações dentárias, a expansão do arco dentário ou os desgastes interproximais. Os desgastes freqüentemente são indicados, mas existem questionamentos quanto às indicações, técnicas e condições pré e pós-tratamento. OBJETIVO: o objetivo deste artigo é apresentar uma discussão, embasada na literatura pertinente, dos principais fatores envolvidos com este procedimento clínico.BACKGROUND: A dental alignment and its stability are important objectives of the orthodontic treatment. The crowding in the anterior area is a common anomaly tooth position problem and, to obtain its correction, the clinical options to the orthodontist are extractions, expansion of dental arch, and dental stripping. Stripping are usually used but it is frequently questioned for the indications, techniques and conditions pre and post-treatment. OBJECTIVE: The purpose of this article is to present a discussion, based in the pertinent literature, of the main factors related to this clinical procedure.

  16. Microcomputer based sliding regime discrete control for synchronous AC motors Control discreto por microordenador basado en regímenes deslizantes para motores de corriente alterna síncronos

    Directory of Open Access Journals (Sweden)

    Eduardo Palomar–Lever

    2007-12-01

    Full Text Available The basic ideas to design discrete algorithms used to calculate unmeasured mechanical or electrical variables, in order to control electrical motors in mechanical systems are presented. The main point of the paper is to simplify the algorithms by using a linear discrete time model without any variable limitations and to reduce the computing capacity requirements of the controller. Limited references, based on the discrete sliding mode for the exception of the influences of variable limitations, are proposed and designed. The main advantage of the controller presented in this paper is that a large control error does not bestow any problems. In such a case, the system always works in an area without the limitations. Original observation algorithms of both position and rotational velocity for exterior permanent magnet synchronous motors are designed. A computer simulation was performed and the results are presented, showing high dynamic accuracy.Se presentan las ideas básicas para diseñar algoritmos discretos para calcular las variables mecánicas o eléctricas, no medidas sino estimadas, para controlar motores eléctricos en sistemas mecánicos. El objetivo principal de este artículo es simplificar los algoritmos usando un modelo de tiempo discreto lineal sin ninguna limitación en las variables y reducir los requisitos de capacidad informática del controlador. Las referencias limitadas, basadas en el modo deslizante discreto para la excepción de las influencias de limitaciones de las variables, se proponen y diseñan. La ventaja principal del controlador presentada en este artículo es que un error de control grande no causa ningún problema. En dicho caso, el sistema trabaja siempre en un área sin limitaciones. Se diseñan los algoritmos de la observación originales de la posición y de la velocidad rotatoria para el imán permanente exterior de motores síncronos. Se llevó a cabo una simulación en computadora y se presentan los

  17. Efecto del tratamiento térmico de desestabilización en el desgaste de hierros blancos de alto cromo

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    Iván Morales

    2009-11-01

    Full Text Available La resistencia a la abrasión de hierros fundidos de alto cromo puede ser mejorada mediante la aplicación de tratamientos térmicos específicos que favorezcan tanto la transformación de austenita en martensita, como la precipitación de carburos secundarios. En esta investigación se estudió, mediante microscopia óptica, el efecto de la temperatura de desestabilización entre 900oC y 1050oC de una aleación 26Cr2.5C2Mo de hierro blanco. La resistencia a la abrasión fue medida en términos de la pérdida de masa durante un ensayo de desgaste abrasivo según la norma ASTM G65. La resistencia a la abrasión de las muestras mejoró al ser tratada térmicamente mediante un proceso de desestabilización a una temperatura determinada, para lo cual se optimizó el tamaño de los carburos secundarios y la dureza superficial. / The heat treatments used to improve abrasion resistance of High-Chromium white casted irons (WCI tend to ease the retained austenite/martensite transformation temperature and favor carbide precipitation within the metallic matrix. In this paper, the effect of four different destabilization heat treatment temperatures was examined for a 26Cr2.5C2Mo WCI under means of optical microscopy. The specimens were obtained under two different casting process, regular sand-casting and permanent molding. The abrasion resistance was measured as mass loss in a dry sand/rubber wheel abrasion test according to ASTM G65. The results show that the solidification speed has a direct effect on the abrasion resistance; manly due to both the eutectic carbide size and its distribution. As predicted, the abrasion resistance of both samples was maximized under certain destabilization temperature, for which carbide size and hardness was optimized.

  18. Programación y reprogramación energética de una micro-red aislada en una estrategia de control por horizonte deslizante

    OpenAIRE

    Marietta Sciara, Pablo Martín

    2014-01-01

    Premi al millor Projecte de Fi de Carrera presentat durant l'any 2014 en l'àmbit d'Optimització de Recursos que atorga DOW CHEMICAL IBÉRICA En este proyecto se propone el diseño y construcción de un software para el control energético de una micro-red eléctrica que opera de forma aislada de la red de distribución principal. El software propuesto se integra físicamente a un Sistema Centralizado de Gestión de la Energía (SCGE) desde el cual se administra la generación y la demanda energética...

  19. Enfoque algorítmico para el cálculo del desgaste en pares de fricción de materiales metálicos

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    Martínez Peréz, Francisco

    2000-12-01

    Full Text Available Tribological properties of since materials for friction pairs are nowadays part of the tecnological requirements they have a decisive influence on the useful life of these pairs. An essential parameter to be measured is the wear undergone by materials that is caused during their perfomance. These measures can be taken in both lab or field testing, but they can be also calculated. For this, the wear mechanism must be taken into account. In the present paper, an algorithm for the calculation of wear based on the main disperse recommendations from the specialized literature is given.

    Las propiedades tribológicas de los materiales de los pares de fricción constituyen, hoy, parte de los requerimientos tecnológicos exigidos, por tener una influencia decisiva en la vida útil de estos pares. Un parámetro esencial a medir es el desgaste que sufren los materiales en su trabajo. Estas mediciones pueden efectuarse en pruebas de campo o laboratorio, pero también puede calcularse este desgaste y para ello hay que tener en cuenta el mecanismo actuante. En el trabajo se expone el desarrollo de un algoritmo para el cálculo del desgaste, que recoge y sintetiza las recomendaciones principales que aparecen en la diversa literatura especializada.

  20. Efecto del volumen de metal cortado y de la velocidad de corte en el desgaste de la herramienta durante el torneado de alta velocidad del acero AISI 1045

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    Luis W. Hernández González

    2011-01-01

    Full Text Available En este trabajo se aborda el estudio experimental del efecto del volumen de metal cortado y de la velocidad de corte en el desgaste del flanco de dos insertos de carburos recubiertos y un cermet, durante el torneado de acabado en seco del acero AISI 1045 a velocidades de corte moderada, intermedia y alta. Los resultados fueron comparados utilizando la dimensión volumétrica de la vida útil de la herramienta, el análisis de varianza y el análisis de regresión lineal para describir la relación entre el desgaste y el volumen removido, según las ecuaciones del modelo ajustado. La investigación mostró un efecto significativo de la velocidad de corte y del volumen cortado en el desgaste del flanco, pues se logró el mejor desempeño para la alta velocidad con el carburo recubierto con tres capas y el peor funcionamiento con el carburo recubierto con dos capas.

  1. Evaluación del desgaste de prótesis cerámicas de cadera recubiertas con DLC por triboadhesión Parte I - Diseño de la máquina de deposición y desgaste

    OpenAIRE

    J. M. Rodríguez Lelis; A. Abúndez P.; Claudia Abúndez P.; S. Chinchilla G

    2006-01-01

    En este artículo se presenta el diseño de una máquina para la realización de depósitos por triboadhesión y evaluación del desgaste de prótesis de cadera. El dispositivo de deposición se diseñó con tres grados de libertad para realizar el depósito en el hemisferio superior del cótilo de la prótesis. Por otra parte, el dispositivo de desgaste, se diseñó como intercambiable con el dispositivo de depósito, y considera la Norma ISO 14-242-1, para la descripción de las trayectorias del movimiento d...

  2. Análisis mecánico y tribológico de los recubrimientos fe-cr-ni-c y ni-al-mo

    OpenAIRE

    MUÑOZ, JORGE E.; JOHN J. CORONADO

    2008-01-01

    En este trabajo de investigación se evaluaron dos recubrimientos aplicados por medio de la técnica de rociado térmico por combustión, la aleación: Ni=89%, Al = 5,5%, Mo=5,5% y la aleación Fe=81,8%, Cr=16%, Ni=2%, C=0,2. La preparación superficial de las probetas se realizó usando chorro de arena. Se realizaron pruebas de resistencia al cortante, adherencia, desgaste abrasivo, desgaste por deslizamiento y flexión en cuatro puntos. El recubrimiento Fe-Cr-Ni-C presentó menor pérdida de masa, tan...

  3. Síndrome de desgaste profesional en el personal de enfermería de hospitales oncológicos cubanos:eficacia de un programa de intervención:2004-2009

    OpenAIRE

    Chacon Roger, Margarita

    2011-01-01

    Los estudios sobre el Síndrome de Desgaste Profesional (SDP) en Enfermería identifican diversos factores que interactúan en su desarrollo. El objetivo de esta investigación fue identificar la magnitud del SDP en el personal de Enfermería de hospitales oncológicos cubanos, determinar los factores laborales y personales que intervienen en el proceso de desgaste y validar la eficacia de un programa de intervención. Se realizaron tres estudios utilizando diseños descriptivo, analítico y experimen...

  4. Estudio experimental del desgaste del flanco y de la rugosidad superficial en el torneado en seco de alta velocidad del acero AISI 316L

    OpenAIRE

    Morales Tamayo, Yoandrys

    2014-01-01

    La mejora continua de los procesos de fabricación es fundamental para alcanzar niveles óptimos de productividad, calidad y coste en la producción de componentes y productos. Para ello es necesario disponer de modelos que relacionen de forma precisa las variables que intervienen en el proceso de corte. Esta investigación tiene como objetivo determinar la influencia de la velocidad de corte y el avance en el desgaste del flanco de los insertos de carburos recubiertos GC1115 y GC2015 y en la rug...

  5. Inteligencia emocional percibida y desgaste laboral en médicos internos de pregrado Perceived emotional intelligence and burnout in undergraduate medicine interns

    OpenAIRE

    R. Ortiz-Acosta; B.E. Beltrán-Jiménez

    2011-01-01

    Objetivo: Analizar la relación entre los niveles de inteligencia emocional percibida y desgaste laboral en médicos internos de pregrado. Sujetos y métodos: Para ello se utilizó la Trait Meta-Mood Scale, que evalúa la inteligencia emocional percibida, y el inventario de burnout de Maslach, en 44 médicos internos de pregrado de tres hospitales de los Servicios de Salud de Sonora. Resultados: El factor de atención emocional se relaciona negativamente con agotamiento. Claridad correlaciona de man...

  6. Comportamiento del hierro nodular austemperizado en condiciones de corrosión y desgaste // Behavior of austempered ductile iron under wear and corrosion conditions

    Directory of Open Access Journals (Sweden)

    L. Goyos Pérez

    1999-07-01

    Full Text Available Los hierros nodulares en general y los austemperizados en particular han sido usados con cada vez mayor frecuencia debido asus relevantes propiedades mecánicas en comparación con su costo.En el presente trabajo se valora el comportamiento del hierro nodular ante el trabajo en condiciones de desgaste y corrosión,luego de ser sometido a diferentes tratamientos de austemperizado.Fueron usados un hierro nodular aleado con níquel y molibdeno y otro no aleado. Ambos hierros fueron sometidos a diferentestratamientos de austemperización con mantenimientos isotérmicos a temperaturas entre 250°C y 425°C por tiempos entre 15 y180 minutos.Las muestras tratadas fueron sometidas a ensayos de desgaste por fricción en condiciones no lubricadas determinando laspendientes de desgaste uniforme para cada caso. La resistencia a la corrosión fue determinada mediante el métodopotenciométrico usando como medio el jugo de caña sintético.A partir de los resultados obtenidos se valora la influencia de los diferentes tratamientos sobre las propiedades estudiadas y sedeterminan los más efectivos desde el punto de vista técnico económico.Palabras claves: Hierro nodular, corrosión, desgaste, austemperizado.____________________________________________________________________________AbstractNodular irons and particularly austempered ductile iron has been used more and more due to their excellent mechanicalproperties in comparison with their cost.Presently work deals on behavior of nodular iron working under wear and corrosion conditions, after being submitted todifferent austempered treatments.A nodular iron alloyed with nickel and molybdenum were used as well as a not alloyed one. Both irons were treated underdifferent austempered treatment combinations using isothermal maintenance to temperatures between 250°C and 425°C andspending times between 15 and 180 minutes.Samples were submitted to non-lubricated wear using a “pin on disk” method evaluating the

  7. Influencia del desgaste profesional en el gasto farmacéutico de los médicos de atención primaria

    OpenAIRE

    Cebrià J.; Sobrequés J.; Rodríguez C.; Segura J.

    2003-01-01

    Objetivo: Determinar la influencia sobre el gasto farmacéutico por asegurado (GFPA) en atención primaria de salud de diversos factores relacionados con las características personales y profesionales de los médicos generales, y su nivel de desgaste profesional. Método: Estudio observacional transversal de 220 médicos de atención primaria de la provincia de Barcelona a quienes, por medio de entrevista directa, se administró un cuestionario validado y estructurado en dos partes: datos generales ...

  8. Aplicação de cavacos de titânio para produção de revestimentos resistentes ao desgaste

    OpenAIRE

    José Gedael Fagundes Júnior; Rodolfo da Silva Manera; Ruís Camargo Tokimatsu; Vicente Afonso Ventrella; Juno Gallego

    2014-01-01

    Equipamentos usados nas usinas sucroalcooleiras e de extração mineral são submetidos a condições severas de desgaste abrasivo. Revestimentos duros são usualmente aplicados para reparar este tipo de dano, sendo bastante empregados consumíveis de soldagem contendo altos teores de cromo e carbono. No presente trabalho visa investigar a microestrutura de revestimentos duros formados com a fusão de cavacos de titânio puro ASTM F67 grau 4, material usado na fabricação de implantes odontológicos. Mi...

  9. Determinación del desgaste del componente acetabular en prótesis totales de cadera. // Wear determination of acetabular component in total hip prosthesis.

    OpenAIRE

    G. García del Pino; Gonçalves, E; R. Gonzáles Lima; R. Dantas Queiroz; J. L. Valín Rivera

    2002-01-01

    En este trabajo se realiza un estudio a través del Método de los Elementos Finitos “MEF” sobre el desgaste del componenteacetabular durante el ciclo de marcha y considerando algunos casos extremos de cargas como subir y bajar escaleras,levantarse de una silla, etc. Utilizando el MEF fueron modelados independientemente los componentes acetabular yfemoral de la prótesis total de cadera y puestos en contacto posteriormente. Fueron estudiadas varias posiciones delacetábulo así como diferentes cas...

  10. Sindrome de desgaste profesional (burnout en médicos especialistas de un hospital universitario, de la ciudad de Santa Marta, Colombia

    Directory of Open Access Journals (Sweden)

    Robert Ferrel

    2013-10-01

    Full Text Available ResumenDiversas investigaciones han señalado una estrecha relación entre el síndrome de quemarse por el trabajo o de desgaste profesional (burnout y los problemas de salud, relacionando al burnout como una de las causas del deterioro de las condiciones de trabajo y fuente de la accidentalidad y absentismo laboral, especialmente en profesionales de la salud y la educación. La presente investigación tuvo como objetivo establecer y describir la existencia del síndrome de burnout en médicos especialistas que laboran en un Hospital Universitario de tercer nivel de la Ciudad de Santa Marta, Colombia. La población estuvo conformada por 56 médicos especialistas vinculados a dicha Institución, a los cuales se les aplicó el Maslach Burnout Inventory (MBI, teniendo en cuenta la edad, especialización y tiempo de vinculación. Los datos fueron procesados por el Software SPSS, 15.0v, haciendo uso de la estadística descriptiva para establecer el nivel de burnout en esta población. Se encontró un alto nivel de agotamiento emocional (94,6% en comparación con las otras dos variables, estando la despersonalización (53,6% y la falta de realización personal (53,6 en un nivel medio, estableciéndose la presencia del síndrome de burnout en un nivel medio en los médicos especialistas del Hospital Universitario. Estos resultados concuerdan con otros estudios similares. Los autores recomiendan continuar con otros estudios incluyendo nuevas variables, así como acciones organizacionales y personales para prevenir el estrés laboral fuente del burnout y mejorar la calidad de los servicios de salud en el Distrito de Santa Marta. (DUAZARY 2010, 29 - 40Abstract Various studies have indicated a close relationship between the syndrome of burnout or burnout (burnout and health problems, relating to the syndrome as a cause of deteriorating working conditions and the source of accidents and absenteeism workforce, especially in healthcare and education. This

  11. Tamaño dental, desgaste oclusal y microestriación en primates Hominoidea

    OpenAIRE

    Galbany i Casals, Jordi; Martínez Pérez-Pérez, Alejandro

    2006-01-01

    El patrón de microestriación dentaria depende no solo de la composición de los alimentos ingeridos, sino también de la presencia en ellos de polvo, cenizas u otras partículas abrasivas de origen externo, generalmente incorporadas al alimento durante su preparación. El presente estudio analiza cómo se ve afectado el patrón de microestriación de la superficie vestibular de los dientes por factores independientes a la estructura y composición alimentaria, como son el tamaño de la pieza dentaria ...

  12. Factores de transcripción en el desgaste muscular asociado a la caquexia

    OpenAIRE

    Moore Carrasco, Rodrigo Ernesto

    2004-01-01

    La caquexia es un síndrome frecuentemente asociado al crecimiento tumoral, así como también a otros estados patológicos como son sepsis, SIDA (síndrome de inmunodeficiencia adquirida), diabetes, etc. La caquexia se caracteriza por una importante y progresiva pérdida de peso corporal debida principalmente a la desaparición de las reservas de grasa y a la disminución de masa muscular. Está acompañada también de anorexia, náuseas, astenia, debilidad, alteración de la homeostasis hormonal e inmun...

  13. Effect of the blades and seals system wear on steam turbine efficiency and power; Efecto del desgaste del sistema de alabes y sellos sobre la eficiencia y potencia de las turbinas de vapor

    Energy Technology Data Exchange (ETDEWEB)

    Campos Amezcua, Alfonso; Kubiak Szyszka, Janusz [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1997-12-31

    The implementation of a method for steam turbine evaluation through the measured geometry in the flow channel and its operating conditions, is presented. This method, previously developed, allows the identification and quantification of the power and efficiency loss due to the wear of its elements (worn or bent blades, worn seals, deposits, etc.); the benefit that is obtained is a more precise knowledge on the turbine behavior and a basis is acquired to give priority to the maintenance work, from the stand point of energy utilization. In this paper, the power and efficiency loss of a 300 MW steam turbine is located and evaluated, a sensibility analysis is presented for the typical elements that cause the deterioration of the efficiency in this type of turbines. [Espanol] Se presenta la implementacion de un metodo de evaluacion de turbinas de vapor a partir de la geometria medida del canal de flujo y sus condiciones de operacion. Este metodo, previamente desarrollado, permite identificar y cuantificar las perdidas de potencia y eficiencia debido al desgaste de sus elementos (alabes desgastados o doblados, sellos desgastados, depositos, etcetera); el beneficio que se obtiene es un conocimiento mas preciso del comportamiento de la turbina y que se tiene una base para dar prioridad a los trabajos de mantenimiento desde el punto de vista de aprovechamiento de la energia. En este articulo se localizan y evaluan las perdidas de potencia y eficiencia de una turbina de vapor de 300 MW, ademas, se presenta un analisis de sensibilidad para los elementos tipicos que originan el deterioro de la eficiencia en este tipo de turbinas.

  14. Determinación del desgaste del componente acetabular en prótesis totales de cadera. // Wear determination of acetabular component in total hip prosthesis.

    Directory of Open Access Journals (Sweden)

    G. García del Pino

    2002-01-01

    Full Text Available En este trabajo se realiza un estudio a través del Método de los Elementos Finitos “MEF” sobre el desgaste del componenteacetabular durante el ciclo de marcha y considerando algunos casos extremos de cargas como subir y bajar escaleras,levantarse de una silla, etc. Utilizando el MEF fueron modelados independientemente los componentes acetabular yfemoral de la prótesis total de cadera y puestos en contacto posteriormente. Fueron estudiadas varias posiciones delacetábulo así como diferentes casos de carga simulando pacientes con diferente peso corporal y actividades físicas. Paraevaluar los resultados se crearon rutinas en lenguaje C que organizaron los mismos para un tratamiento estadísticoposterior.Palabras claves: biomecánica, ortopedia, elementos finitos, modelación, desgaste, prótesis de cadera.___________________________________________________________________________Abstract.A wear study of acetabular component during the marching cycle, considering some extreme loads cases as: ascend anddescend stairways, get up from a seat, etc , by means of Finite Elements Method ( FEM , is carried out. The acetabular andfemoral component of the total hip prosthesis were independently modeled and placed in contact lastly. Several acetabulpositions were studied as well as different load cases, simulating patients with different body weight and different physicalactivities. To evaluate the results routines in C language were created in order to organized the same ones for a laterstatistical treatment.Key words. biomechanics, ortophedy, finite elements, modelation, wear, hip bone prosthesis.

  15. Psychic workloads and strain processes in nursing workers of brazilian university hospitals Cargas psíquicas y procesos de desgaste en trabajadores de enfermería de hospitales universitarios brasileños Cargas psíquicas e processos de desgaste em trabalhadores de enfermagem de hospitais universitários brasileiros

    Directory of Open Access Journals (Sweden)

    Vivian Aline Mininel

    2011-04-01

    Full Text Available Objective: to identify the work process, the psychic workloads and the strains generated in nursing workers. Method: the study was developed in five Brazilian university hospitals. The sample was composed by 62 nursing workers and the data collection was done by focal group technique, followed by the application of a collective inquire. The data were quantitatively described and systematized according to a thematic analysis. Results: the study population represented 35,37% of the hospital workforce in national setting. The workers mentioned are exposure to several kinds of psychic workload and link them to with others workloads, highlighting the strain processes resulting from this kind of workload, such stress, fatigue, complaints of gastritis and headaches. Conclusions: nursing workers are exposed to several workloads in the hospital environment, especially psychic workloads. This exposure starts strain processes that compromise the health and quality of life, signaling the necessity of interventions in this reality.El objetivo de este estudio fue identificar el proceso de trabajo, las cargas psíquicas y los desgastes generados en trabajadores de enfermería. Se trata de un estudio desarrollado en cinco hospitales universitarios brasileños. La muestra fue compuesta por 62 trabajadores de enfermería; la recolección fue realizada por medio de la técnica de grupo focal, seguida de la aplicación de encuesta colectiva. Los datos fueron descritos numéricamente y sistematizados según análisis temático. La población de estudio representó 35,37% de la fuerza de trabajo hospitalario en el escenario nacional. Los trabajadores refirieron exposición a diversos tipos de cargas psíquicas y las relacionaron con otras cargas de trabajo, destacando los desgastes provenientes de este tipo de carga, como estrés, fatiga, gastritis y cefalea. Los trabajadores de enfermería están expuestos a las diversas cargas de trabajo en el ambiente hospitalario

  16. Características sólido-fluido en el crisol del horno alto según el modelo de desgaste nodal (MDN

    Directory of Open Access Journals (Sweden)

    Martín, R.

    2009-08-01

    Full Text Available The coke porosity is one of the most important variables that can affect the pig iron production and the lining corrosion. Up to now, the existing bibliography about lining corrosion always connects a deeper wear to an increase in the fluid flow (pig iron at the blast furnace hearth. However, there is no evidence of any deterministic model that could link, from the theoretical point of view, the following variables: lining corrosion, porosity of dead coke and flow of pig iron at the hearth. Besides justifying the lining corrosion profiles, the Nodal Wear Model (NWM can be an effective instrument to interpret the coke porosity and the pig iron speed rates that are generated inside the hearth.

    La porosidad del coque aparece como unas de las variables que más pueden afectar a la producción de arrabio y a la correspondiente corrosión de los revestimientos. Hasta el momento, en la bibliografía existente sobre la corrosión de los revestimientos, siempre se asocia un mayor desgaste con el correspondiente incremento del flujo del fluido (arrabio en el crisol. No obstante, no se tiene referencia de ningún modelo determinístico que pudiera relacionar, desde el punto de vista teórico, las siguientes variables: corrosión de los revestimientos, porosidad del coque inactivo y flujo del arrabio en el crisol. El Modelo de Desgaste Nodal (MDN, además de justificar los perfiles de corrosión de los revestimientos a lo largo de la campaña, puede ser un instrumento eficaz para interpretar la porosidad del coque y los gradientes de velocidad del arrabio que se generan dentro del crisol.

  17. UN MÉTODO DE MONITOREO DEL DESGASTE DE UNA HERRAMIENTA DE CORTE BASADO EN UN SENSOR DE PROXIMIDAD DE FIBRA ÓPTICA A METHOD FOR CUTTING TOOL WEAR MONITORING BASED ON AN OPTICAL FIBER PROXIMITY PROBE

    Directory of Open Access Journals (Sweden)

    G de Anda-Rodriguez

    2006-08-01

    Full Text Available Este documento presenta una técnica novedosa para el monitoreo en línea del desgaste de una herramienta de fresado. El desgaste es estimado directamente a partir de un sensor de proximidad de fibra óptica (SPFO con características de alta resolución y alto ancho de banda. El SPFO proporciona una medida de la distancia entre su extremo y el perfil de la herramienta. La principal contribución de este trabajo es la aplicación del SPFO para monitorear en línea el desgaste de una herramienta de fresado. Puesto que la luz emitida por el SPFO proviene de un fotodiodo, esta no produce daño a los ojos, lo que la hace más segura que los sensores de desplazamiento de tipo láser. Esta técnica permite monitorear el desgaste de la herramienta en tiempo real, mientras la herramienta gira, con una precisión inferior a 1 micra. Se presentan resultados experimentales para una herramienta de fresado vertical de cuatro filos que gira a 300 rpm.A novel technique for on-line wear monitoring of a milling tool is presented. The tool wear is estimated directly from a fiber optic proximity sensor (FOPS with high resolution and high bandwidth characteristics. The FOPS provides a distance measurement between its probe and the tool profile. The main contribution of this work is the application of FOPS to sense on-line the wear of a milling tool. Since the light emitted by this sensor comes from a photodiode, it does not produce eye damage; this is safer than laser displacement sensors. This technique senses the tool wear in real time, while the tool is rotating, with an accuracy of less than 1 micron. Experimental results are also presented for a four-flank cutting tool rotating at 300 rpm.

  18. Desarrollo y caracterización de un material compuesto (Ce, Y)-TZP/Al2O3

    OpenAIRE

    Lallemand, Simon

    2014-01-01

    La circona como biomaterial ha sido muy estudiada y utilizada por sus excelentes propiedades mecánicas y su biocompatibilidad. Se utiliza generalmente bajo su forma estabilizada con itria (3Y-TZP) que le proporciona una gran tenacidad y resistencia al desgaste. Dichas propiedades hacen de la circona 3Y-TZP un material de elección para prótesis de dientes o de cadera. Sin embargo, tiene una gran tendencia a la degradación in vivo. Este problema, también denominado envejecimiento o degradaci...

  19. Aplicação de cavacos de titânio para produção de revestimentos resistentes ao desgaste

    Directory of Open Access Journals (Sweden)

    José Gedael Fagundes Júnior

    2014-09-01

    Full Text Available Equipamentos usados nas usinas sucroalcooleiras e de extração mineral são submetidos a condições severas de desgaste abrasivo. Revestimentos duros são usualmente aplicados para reparar este tipo de dano, sendo bastante empregados consumíveis de soldagem contendo altos teores de cromo e carbono. No presente trabalho visa investigar a microestrutura de revestimentos duros formados com a fusão de cavacos de titânio puro ASTM F67 grau 4, material usado na fabricação de implantes odontológicos. Misturas com diferentes formadores de carbonetos (Fe-Cr e Fe-Nb como aditivos também foram testadas. Revestimentos feitos com duas camadas de cavacos "puros" (Ti, cavacos com Fe-Cr (Ti-Cr e cavacos com Fe-Nb (Ti-Nb foram depositadas sobre peças de aço-carbono por soldagem TIG/GTAW. A microestrutura das camadas foi observada com microscópio óptico e por microscópio eletrônico de varredura equipado com microanálise. A caracterização microestrutural revelou que a distribuição de carbonetos varia significativamente com a natureza química dos aditivos usados. A microanálise mostrou que houve a formação de carbonetos com composição química complexa no seio do metal de solda, cuja estequiometria foi determinada com análise por difração de raios-X. Carbonetos mistos do tipo MC e cementita foram identificados. Os resultados apresentados indicam que a aplicação de cavacos de titânio ASTM F67, como insumo para formação de carbonetos, pode contribuir para melhorar a resistência ao desgaste em comparação aos tradicionais revestimentos duros com carbonetos de cromo.

  20. Cervical shaping in curved root canals: comparison of the efficiency of two endodontic instruments Desgaste cervical em canais curvos: comparação entre a eficiência de dois instrumentos endodônticos

    Directory of Open Access Journals (Sweden)

    Sandra Soares Kühne Busquim

    2002-12-01

    Full Text Available The aim of this study was to determine the removal of dentin produced by number 25 (0.08 Flare files (Quantec Flare Series, Analytic Endodontics, Glendora, California, USA and number 1 e 2 Gates-Glidden burs (Dentsply - Maillefer, Ballaigues, Switzerland, in the mesio-buccal and mesio-lingual root canals, respectively, of extracted human permanent inferior molars, by means of measuring the width of dentinal walls prior and after instrumentation. The obtained values were compared. Due to the multiple analyses of data, a nonparametric test was used, and the Kruskal-Wallis test was chosen. There was no significant difference between the instruments as to the removal of dentin in the 1st and 2nd millimeters. However, when comparing the performances of the instruments in the 3rd millimeter, Flare files promoted a greater removal than Gates-Glidden drills (p > 0.05. The analysis revealed no significant differences as to mesial wear, which demonstrates the similar behavior of both instruments. Gates-Glidden drills produced an expressive mesial detour in the 2nd and 3rd millimeters, which was detected trough a statistically significant difference in the wear of this region (p > 0.05. There was no statistically significant difference between mesial and lateral wear when Flare instruments were employed.O propósito do presente trabalho foi determinar o desgaste promovido em dentina pelas limas Flare número 25 (0,08 (Quantec Flare Series, Analytic Endodontics, Glendora, Califórnia, EUA e pelas brocas Gates-Glidden números 1 e 2 (Dentsply-Maillefer, Ballaigues, Suíça, nos canais mesiovestibular e mesiolingual, respectivamente, de molares inferiores permanentes humanos extraídos, através da medição, em milímetros, da espessura das paredes dentinárias antes e posteriormente à instrumentação. Os valores dos desgastes obtidos foram comparados entre si. A análise dos resultados, baseada no teste estatístico não-paramétrico de Kruskal

  1. Efecto del tratamiento térmico posterior sobre la resistencia al desgaste por deslizamiento de un recubrimiento base níquel depositado por HVOF

    OpenAIRE

    Cadenas, P.; Rodriguez, M.; Staia, M.H.

    2007-01-01

    In the present research, a nickel base coating was deposited on an AISI 1020 substrate by using high velocity oxy-fuel technique (HVOF). The coating was subsequently post heat -treated by means of an oxyacetylene flame. For the conditions evaluated in the present study, it was found that the CTT coating has 1,15 better wear resistance for the smaller level of the applied load and nearly 50 times for the highest level of the applied load when compared to the STT coatings. These results have be...

  2. Efecto de la adición de aluminio en la resistencia al desgaste abrasivo del hierro fundido aleado Ni-Resist

    OpenAIRE

    María Victoria Rojas-Fernández; Alberto Velázquez-Del Rosario; Isnel Rodríguez-González

    2015-01-01

    La presente investigación se planteó como objetivo incrementar la resistencia a la abrasión del hierro fundido aleado Ni-Resist por precipitación de partículas manteniendo invariable la estabilidad química a partir de la adición de aluminio como inductor de compuestos intermetálicos y que contribuye a la formación o precipitación de partículas coherentes. Se experimentó con muestras de aleaciones tipo 2 y tipo 3 de Ni-Resist fijando la variable porcentaje de níquel y moviendo el porcentaje de...

  3. Propuesta para la recuperación de los machetes Zuazaga de los centrales azucareros con electrodos de acero al cromo. // Proposal for Recuperation of Sugar Mill Cut Cane by Using Chromium Steel Electrodes.

    OpenAIRE

    R. Collazo-Carceller; H López-Salinas; A. Días-Romero.

    2009-01-01

    El trabajo resume el estudio y análisis desarrollado, para la presentación de una propuestatecnológica de recuperación de los machetes Zuazaga, en nuestros centrales azucareros. Sedeterminó la influencia de los parámetros, energía introducida (Hi), número de capas (Nc) y anchodel depósito (Ad), en la morfología y el incremento de la resistencia al desgaste abrasivo, utilizandoel electrodo de acero al cromo DUR 600. Se realizó una valoración económica de la propuestatecnológica.Palabras claves...

  4. Aceites lubricantes próticos derivados de ácido oleico : estudio de su capacidad para interaccionar con aleaciones de Al – Cu

    OpenAIRE

    Torrecillas Tormo, Antonio

    2012-01-01

    Con este PFC se ha llegao a las siguientes conclusiones: 1. Se ha utilizado el triéster sintético derivado de trioleato como aceite base, dado que es uno de los lubricantes utilizados industrialmente para aleaciones de aluminio. Se han seleccionado como aditivos dos líquidos iónicos próticos que contienen el anión oleato y, por tanto, son compatibles con el aceite base. 2. Se han llevado a cabo ensayos de fricción y desgaste de la aleación aluminiocobre Al 2011, modificando el ...

  5. Avaliação do desgaste abrasivo causado pelas cerâmicas Duceram e Vita em resinas compostas pelo método do disco retificado Evaluation of the abrasive wear caused by the ceramics Duceram and Vita in composite resins by the method of the ground disk

    OpenAIRE

    T. V. França; E. C. Bianchi; P. R. de Aguiar; R. Y. Fusse; R. E. Catai; C. A. de Freitas

    2004-01-01

    O presente trabalho apresenta uma metodologia confiável e de execução rápida para a avaliação do desgaste abrasivo entre as cerâmicas Duceram e Vita nas resinas compostas Z-100 e Charisma. Estes materiais são amplamente utilizados nos consultórios e clínicas dentais para restaurações funcionais e estéticas dos dentes. Para avaliar o desgaste abrasivo entre os materiais, um disco dinâmico revestido com porcelana foi utilizado sobre um disco estático revestido com resina. Os resultados indicara...

  6. Síndrome de desgaste laboral (Burnout) en los médicos residentes de especialidades medico quirúrgicas de la Universidad Nacional de Colombia, sede Bogotá

    OpenAIRE

    Berdejo Pacheco, Harold Leonid

    2014-01-01

    INTRODUCCIÓN: Síndrome de Burnout: estado de agotamiento físico, mental y emocional, generado por involucrarse en el trabajo en situaciones emocionalmente demandantes. Así, los residentes, sometidos a estrés crónico por la gran responsabilidad con el paciente, carga asistencial, falta de descanso, constituyen grupo de riesgo para desarrollar el mismo. OBJETIVO: Establecer la prevalencia del síndrome de desgaste laboral en los médicos residentes de especialidades médico quirúrgicas de la Un...

  7. Estudio del desgaste a nivel microcópico de los dientes anteriores de los homínidos del yacimiento pleistocénico de sima de los huesos (sierra de atapuerca, Burgos)

    OpenAIRE

    Lozano Ruiz, Marina

    2005-01-01

    TESIS: MARINA LOZANO RUIZ"ESTUDIO DEL DESGASTE A NIVEL MICROSCÓPICO DE LOS DIENTES ANTERIORES DE LOS HOMÍNIDOS DEL YACIMIENTO PLEISTOCÉNICO DE SIMA DE LOS HUESOS (SIERRA DE ATAPUERCA, BURGOS)." La dentición es, junto con las manos, una de las partes del cuerpo humano que interactúa directamente con el exterior. El uso simultáneo de manos y dientes permite llevar a cabo una amplia diversidad de tareas en las que se procesan y modifican diversos materiales. Desde los primeros momentos de la evo...

  8. Estudio de líquidos iónicos y nanotubos de carbono en la reducción de la fricción y el desgaste de poliestireno, policarbonato y polimetilmetacrilato

    OpenAIRE

    Espejo Conesa, Cayetano

    2012-01-01

    [SPA] La obtención de nanocomposites poliméricos a partir de nanofases tales como nanotubos de carbono constituye una de las más importantes estrategias en estudio para la mejora de las propiedades mecánicas de los termoplásticos. En este trabajo en particular, se han utilizado para disminuir el coeficiente de fricción y la tasa de desgaste de los materiales termoplásticos poliestireno, policarbonato y polimetilmetacrilato. Se han obtenido y caracterizado nuevos nanofluidos a partir del líqui...

  9. Caracterização in Situ de Propriedades Mecânicas de Materiais Resistentes ao Desgaste Abrasivo Usando o Método da Indentação

    OpenAIRE

    Berns Hans; Franco Sinésio D.

    1997-01-01

    O desempenho de materiais polifásicos em sistemas tribológicos envolvendo desgaste abrasivo é função de uma série de fatores, a saber: condições de operação, características de projeto e das propriedades do abrasivo e dos microconstituintes do material utilizado. Neste trabalho são apresentados resultados de ensaios de indentação em diferentes microconstituintes e partículas duras, através dos quais as propriedades mais importantes para o fenômeno abrasivo são determinadas in situ. Dentre ess...

  10. Avaliação da resistência ao desgaste erosivo gerado por cavitação em aços inoxidáveis austeníticos com alto teor de nitrogênio: estudo dos mecanismos de desgaste Assessment of the cavitation erosion resistance in high nitrogen austenitic stainless steels: study of the wear mechanisms

    Directory of Open Access Journals (Sweden)

    Dairo Hernán Mesa

    2010-03-01

    Full Text Available Amostras do aço inoxidável UNS S31803, nitretadas em alta temperatura, com 0,9 % de nitrogênio em solução sólida foram submetidas a ensaios de cavitação vibratória em água destilada. As amostras foram, previamente, caracterizadas por meio de difração de elétrons retroespalhados, EBSD, num microscópio eletrônico de varredura (MEV. Posteriormente, durante os ensaios de cavitação, o dano superficial das amostras foi, periodicamente, avaliado por observação no MEV das superfícies desgastadas. O aço austenítico convencional UNS S30403 foi usado como material de comparação. Nas primeiras etapas dos ensaios de cavitação, ocorreu deformação plástica da superfície, que pôde ser caracterizada como altamente heterogênea na escala do tamanho de grão. Em etapas posteriores, ocorreu perda de massa por desprendimento de partículas de desgaste (debris, como conseqüência de fadiga de baixo ciclo. O início do dano ocorreu tanto no interior dos grãos como nos contornos de grão; os contornos de macla mostraram as regiões mais suscetíveis. Os grãos com planos (101 orientados aproximadamente paralelos à superfície das amostras apresentaram maior resistência ao desgaste que os grãos com outras orientações cristalográficas. A maior resistência ao desgaste dos grãos com textura (101 || superfície foi atribuída a uma menor tensão projetada para deformar, plasticamente, esses grãos. A diminuição da referida tensão se dá em função das tensões impostas na superfície cavitada pela implosão de bolhas de vapor.Specimens of a UNS S31803 steel were submitted to high temperature gas nitriding and then to vibratory pitting wear tests. Nitrided samples displayed fully austenitic microstructures and 0.9 wt. % nitrogen contents. Prior to pitting tests, sample texture was characterized by electron backscattering diffraction, EBSD. Later on, the samples were tested in a vibratory pit testing equipment using distilled water

  11. Wear analysis by applying a pin-disc configuration to phemoral head and acetabular cup Análisis del desgaste de la articulación cabeza femoral–copa acetabular mediante simulación experimental con máquina perno-disco

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    Beltrán-Fernandez Juan Alfonso

    2008-07-01

    Full Text Available This work determines a prosthetic hip system’s life-span, focusing on a Mexican phenotype. The total sliding equivalent distance for the system was determined, as well as the loading regime under which the femoral component and the acetabular cup were subjected in normal operating conditions. An experimental tribology essay was then performed to simulate the wearing of the components in a Pin over Disc machine. This assay (for which the test specimens were manufactured in medical grade stainless steel AISI-ASTM 316L for the femoral component and high density polyethylene for the acetabular cup was aimed at simulating wear conditions involved in 10 years of continuous operation. A numerical simulation of operational conditions (using the finite element method was performedIn for establishing assay loading conditions to accurately determine where the loads should be applied. The tribology assay led to quantifying the volumetric loss of materials for the system being analysed. It can be concluded that the methodology proposed in this work for estimating the life-span of a prosthetic hip system was valid and accurate by comparing the results with those found in the literature. A statistical validation of the proposed method is plaaned for the future. Key words: Design life; femoral component; acetabular cup; Mexican phenotype; pin-disc configuration.Este trabajo presenta un estudio que permite establecer la vida útil esperada de un sistema prostético de cadera para el caso del fenotipo mexicano. En primera instancia se determinó la distancia total equivalente de deslizamiento y las condiciones de carga entre el componente femoral y la copa acetabular bajo condiciones normales de carga. Posteriormente, se desarrolló una simulación experimental para la realización de un ensayo tribológico en una máquina de desgaste del tipo Perno sobre Disco (Pin on Disk, POD. Este ensayo sometió al conjunto fabricado en acero inoxidable AISI

  12. Desgaste físico e mental de auxiliares de enfermagem: uma análise sob o enfoque gerencial Desgaste físico y mental de auxiliares de enfermería: un análisis bajo el enfoque gerencial Mental and physical stress of auxiliary nurses: analysis of management

    Directory of Open Access Journals (Sweden)

    Moema Miranda de Siqueira

    1995-01-01

    Full Text Available Buscando melhor compreender o trabalho em organizações de saúde. Foi realizada uma pesquisa em hospitais gerais contemplando alguns grupos ocupacionais. Supõe-se que a atividade de lidar com dor, sofrimento e morte interfere na organização, gestão, condições de trabalho e que de maneira geral, expõe os trabalhadores dessas organizações a um desgaste físico e mental intenso. Percebeu-se, no entanto, que tanto as organizações quanto os próprios grupos ocupacionais têm ainda pouca consciência sobre estes problemas, desenvolvendo poucas formas de regulação ou atenuação dos conflitos daí decorrentes. O artigo apresenta uma análise específica sobre o grupo de auxiliares de enfermagem e sugere, a título de conclusivo, algumas medidas que podem melhorar essa situação.Buscando comprender mejor el trabajo en organizaciones de salud, fue realizada una investigación en hospitales generales contemplando algunos grupos ocupacionales. Se supone que una actividad ligada a dolor, sufrimiento y muerte interfiere en la organización, gestión, condiciones de trabajo y que de manera general, expone a los trabajadores de esas organizaciones a un desgaste físico y mental intenso. Se notó también, que tanto las organizaciones como los propios grupos ocupacionales aún tienen escasa conciencia sobre estos problemas, desenvolviendo pocas formas de regulación o atenuación de los conflictos decorrentes. El artículo presenta un análisis específico sobre el grupo de auxiliares de enfermería y sugiere, a título de conclusión medidas que pueden mejorar esa situación.Seeking a better understanding of job stress, auxiliary nurses were evaluated in General Hospitals Belo Horizonte. The emotional stress which accompanies auxiliary nurses caring for the sick and easing physical and mental suffering affects their own mental state and physical health. Elements that cause suffering and diseases can be attenuated or intensified depending on

  13. Comportamiento tribológico del acero AISI W112 con endurecimiento lineal mediante laser de ND:YAG.L. // Tribological behavior of AISI W112 steel with lineal hardening by means of ND:YAG laser.

    Directory of Open Access Journals (Sweden)

    R. Sagaró

    2001-07-01

    Full Text Available Para disminuir el desgaste en los sistemas tribológicos frecuentemente se acostumbra a endurecer localmente aquellaszonas sometidas a desgaste. En el presente trabajo, para incrementar la dureza y la resistencia al desgaste del acero AISIW112 se empleó un láser de Nd:YAG. Las características de fricción y desgaste del acero AISI W112 en condiciones decontacto deslizante en fricción seca con el acero 65MN4 fueron evaluadas para tratamientos convencionales luego de suirradiación con láser. En el trabajo se presentan además las transformaciones que ocurren durante el tratamiento con láser,así como la influencia de los parámetros operacionales del láser en la profundidad de la capa endurecida y lascaracterísticas tribológicas. El trabajo experimental corroboró que la resistencia al desgaste del acero AISI W112 es variasveces superior en comparación con los tratamientos convencionales.Palabras claves: Comportamiento tribológico, endurecimiento lineal, tratamiento superficial con láser._______________________________________________________________________________Abstract.Diminishing wear in tribological systems is usually done by locally hardening those areas subject to wear. In this paper ispresented the increasing of hardness and resistance to wear of AISI W112 steel by means of a Nd:YAG laser. Thecharacteristics of friction and wear of AISI W112 steel under sliding contact in dry friction conditions with the 65MN4steel were evaluated for conventional treatments and after laser irradiation. In the work are presented the transformationsthat take place during the laser treatment, as well as the influence of the laser operational parameters in the depth of thehardened layer and the tribological characteristics. The experimental work corroborated that the resistance to wear of AISIW112 steel is several times superior in comparison with conventional treatments.Key words: Tribological behavior , lineal hardening, laser superficial

  14. Atrito e desgaste de recobrimentos de PET, politeraftalato de etileno, pós-consumo processados por aspersão térmica Friction and wear of a thermal sprayed PET - poly(ethylene teraphthalate coating

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    Rogério A. X. Nunes

    2007-09-01

    Full Text Available A aspersão térmica envolve processos de recobrimentos que podem utilizar materiais cerâmicos, poliméricos, metálicos ou misturas destes. O material a ser depositado é fundido total ou parcialmente. As partículas aquecidas são aceleradas e projetadas em direção a uma superfície devidamente preparada, onde se formam camadas com estrutura lamelar. Os efeitos das variáveis do processo de aspersão, pressão dos gases de combustão, taxa de alimentação e gás de arraste no transporte do material, sobre a resistência ao desgaste e atrito de filmes PET foram investigados. Os recobrimentos de PET foram caracterizados através do desgaste micro-abrasivo, utilizando o ensaio de caloteste, e da medida dos coeficientes de atrito, com o ensaio de pino-sobre-disco. Os valores do coeficiente de desgaste abrasivo e do coeficiente de atrito dos recobrimentos são comparados com os valores da garrafa PET utilizada como referência. Os coeficientes de desgaste encontrados foram similares aos valores de garrafas PET da ordem de 10-5. As análises estatísticas dos resultados deste trabalho indicam que os efeitos das interações das três variáveis, pressão dos gases de combustão, taxa de alimentação e gás de arraste foram significativos para o coeficiente de desgaste e não significativos para o coeficiente de atrito.The thermal spray technique involves coating processes that can use ceramic, polymers, metallic materials or a blend of these. The material to be deposited is melted totally or partially, where the heated particles are accelerated and projected toward a prepared surface forming layers with a lamellar structure. The effect of the spray process parameters such as, combustion pressure, feed rate and carrier gas, on the wear resistance and friction of PET films was evaluated. The PET coatings were characterized by measuring the wear coefficient through the calowear type testing and the friction coefficients using pin-on-disk testing

  15. Desgaste de bicos de pulverização pelo uso de formulações cúpricas Abrasive action of the spray mixture on some spray nozzles

    Directory of Open Access Journals (Sweden)

    Hermes Geraldo Corrêa

    1976-07-01

    Full Text Available O desgaste dos bicos de pulverização afeta, entre outras características, principalmente a vazão. Ensaio realizado com bicos de cone vazio tipo disco mostrou, em certos casos, aumentos superiores a 100% sobre a vazão inicial, já nas primeiras 50 horas de operação. Evidentemente, isto também conduz a um aumento de mais de 100% na quantidade de defensivos aplicados, caso o usuário não se aperceba do problema. Observou-se menor influência do aumento do orifício do disco sobre a vazão. Por outro lado, os helicóides apresentaram pronunciado desgaste, afetando diretamente a vazão. Esse desgaste ainda alterou a característica do cone de pulverização do bico, preenchendo o seu centro. Foi notada também redução do ângulo do cone, bem como aumento do tamanho das gotículas.In this paper it was studied the abrasive action of a copper oxichloride spray mixture on some disc type hollow cone spray nozzles under usual pressures. Changes in spray nozzles characteristics were noticed during the work as increasing in the flow-rate, decreasing in the spraying angle, and filling of the hollow cone with high density of spray droplets. The flow rate change is of main importance because if neglected it may contribute to excessive deposition of pesticides on the plants. Beyond the pesticides wastage it implies in great hazzard to environmental contamination and phyto-toxicity. Among the nozzles components tested the core showed higher wearing. The one made of brass was more sensitive to abrasive action of spray mixture than nylon ones, while that of stainless steel showed to be the strengthest. The influence of the nozzles wearing on the flow-rate, angle cone, and cone spray pattern was analyzed in function of the time of operation. To determine the droplet parameters, droplet analyses of new spray nozzles and after 100 hours of use were made.

  16. Wear and superficial roughness of glass ionomer cements used as sealants, after simulated toothbrushing Desgaste e rugosidade superficial de cimentos de ionômero de vidro utilizados como selantes, após escovação simulada

    Directory of Open Access Journals (Sweden)

    Daniela Rios

    2002-12-01

    Full Text Available The purpose of this study was to evaluate, in vitro, the properties (wear and roughness of glass ionomer cements that could influence their indication as pit and fissure sealants. The utilized materials were Fuji Plus, Ketac-Molar and Vitremer (in two different proportions: 1:1 and ¼:1. The resin-based sealant Delton was used as control. By means of an electronic balance (precision of 10-4 g, wear was measured in function of weight loss after simulated toothbrushing. Superficial roughness was determined by means of a surface roughness-measuring apparatus. The results revealed that diluted Vitremer and Fuji Plus were less resistant to toothbrushing abrasion and had the greatest increase in superficial roughness.Although in clinical situations luting or diluted ionomer cements are often utilized as alternatives to resin-based sealants, the resultsof this study revealed that the properties of those cements are worse than those of restorative ionomers, whichpresented results similar to those of the evaluated resin sealant.O presente estudo foi conduzido in vitro com o intuito de constatar as propriedades (desgaste e rugosidade dos CIV, as quais influenciam na sua indicação como material selador de fossas e fissuras. Os materiais empregados foram Fuji Plus, Ketac-Molar e Vitremer (duas proporções: 1:1 e ¼:1. O selante Delton foi controle. A determinação do desgaste foi obtida através da quantidade de massa perdida após a escovação e a rugosidade através da análise quantitativa da superfície. Os resultados mostraram que o Vitremer diluído e o Fuji Plus apresentaram maior grau de desgaste e maior aumento de rugosidade. Apesar de clinicamente se encontrar um maior uso dos ionômeros de vidro cimentantes ou diluídos como forma alternativa para material selador; este trabalho permitiu concluir que estes possuem propriedades bastante inferiores quando comparados aos ionômeros restauradores que, por sua vez, possuem resultados semelhantes

  17. Comparação dos valores de desgaste abrasivo e de microdureza de 13 resinas compostas usadas em odontologia através do método do disco retificado Comparing abrasive wear and microhardness of 13 dental composite resins

    Directory of Open Access Journals (Sweden)

    Eduardo C. Bianchi

    2007-06-01

    Full Text Available Atualmente tem-se buscado simplificar a tarefa de caracterização da vida útil de restaurações dentárias realizadas por resinas compostas através de métodos laboratoriais, que são mais rápidos e não sofrem influência de variáveis pessoais inerentes às análises clínicas. Com este propósito, este trabalho apresenta uma nova metodologia de ensaio laboratorial para a avaliação do desgaste abrasivo de resinas compostas através do método do disco retificado. Realizaram-se ensaios de resistência ao desgaste abrasivo com 13 resinas compostas odontológicas e buscou-se analisar o comportamento da resistência ao desgaste abrasivo em relação à microdureza dessas resinas. Com a análise dos resultados concluiu-se que o método de discos retificados é eficiente para a obtenção da resistência ao desgaste abrasivo. Notou-se também ser extremamente pequeno o nível de correlação entre microdureza e desgaste abrasivo o que indica que cada resina composta tem características próprias e que o desgaste é dependente também de outros fatores.It is now commonplace to search for methods to assess the useful lifetime of dental restorations made of resins, which are quicker and less subjective than clinical analyses. With this purpose, this work presents a new methodology based on the grinding disk for evaluating the abrasive wear of composed resins. Resistance tests to the abrasive wear were made with 13 composed resins used as dental material, and a comparison was done with the hardness of those resins. From the data analysis, we concluded that the method of rectified disks is efficient for obtaining the resistance to the abrasive wear. Furthermore, the correlation between hardness and abrasive wear was very small, which indicates that each composed resin has its own characteristics and that the wear also depends on other factors.

  18. Influencia del contenido de silicio y el tratamiento térmico en la resistencia al desgaste de fundiciones blancas al cromo en condiciones de rápida solidificación

    OpenAIRE

    Goyos, L.; Varela, A; Verhaege, M.; García, A.; van Mier, J.; Moors, M

    2012-01-01

    The influence of silicon content and heat treatment on microstructure, abrasive and dry friction wear resistance of a 3 % C, 12 % Cr cast iron, under fast solidification conditions is studied. The fast solidification condition diminishes the carbide volume and the silicon content increases their dispersion and finesses. All matrixes obtained were perlitics, whit different finesses. No intermediate transformation products were noticed. Hardness had little variation. Austenization treatment sho...

  19. ALS Association

    Science.gov (United States)

    ... toward a world without ALS! Walk to Defeat ALS® Walk to Defeat ALS® draws people of all ... We need your help. I Will Advocate National ALS Registry The National ALS Registry is a congressionally ...

  20. Estudo comparativo da resistência ao desgaste abrasivo do revestimento de três ligas metálicas utilizadas na indústria, aplicadas por soldagem com arames tubulares Comparative study of the wear resistance of three metal cored wire welded coatings used in industry

    OpenAIRE

    Ricardo Vinícius de Melo Leite; Paulo Villani Marques

    2009-01-01

    As ligas metálicas aplicadas por soldagem em superfícies, objetivando a proteção contra o desgaste e o conseqüente aumento da vida útil de peças e equipamentos, têm sido utilizadas em larga escala nas indústrias de bens de consumo e nos setores de mineração e sucroalcooleiro. O desgaste abrasivo em peças e equipamentos representa, nestas industriais, um dos principais fatores de depreciação de capital e uma importante fonte de despesas com manutenção. Para a aplicação do revestimento por sold...

  1. Propuesta para la recuperación de los machetes Zuazaga de los centrales azucareros con electrodos de acero al cromo. // Proposal for Recuperation of Sugar Mill Cut Cane by Using Chromium Steel Electrodes.

    Directory of Open Access Journals (Sweden)

    R. Collazo-Carceller

    2009-09-01

    Full Text Available El trabajo resume el estudio y análisis desarrollado, para la presentación de una propuestatecnológica de recuperación de los machetes Zuazaga, en nuestros centrales azucareros. Sedeterminó la influencia de los parámetros, energía introducida (Hi, número de capas (Nc y anchodel depósito (Ad, en la morfología y el incremento de la resistencia al desgaste abrasivo, utilizandoel electrodo de acero al cromo DUR 600. Se realizó una valoración económica de la propuestatecnológica.Palabras claves: morfología, desgaste abrasivo, parámetro de soldadura, dendrites._____________________________________________________________________________AbstractThis work, sumarises the study and the analisys developed, to prupose the Zuazaga cut canethecnology recuperation, in aur sugar mills. The parameters influency was determinated, Heatinput (Hi, Number of layers (Nc and the Cord whith (Ad, in the mofology and the abrasive wearresistance increase, using the cromiun steel UTP DUR - 600. The economical calculation of thethecnology was done.Key words: morphology abrasive wear, welding parameters. dendrites, modeling

  2. Caracterización de las propiedades de resistencia a la oxidación y desgaste de recubrimientos de proyección térmica de alta velocidad para la protección de incineradoras de residuos sólidos urbanos

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    Guilermany, J. M.

    2008-08-01

    Full Text Available High Velocity Oxy Fuel (HVOF Thermal Spray Technology produces coatings with high erosion and corrosion resistance. These E-C processes are the most usual problems of municipal solid waste incinerators plants. This work shows the characterisation of the optimal coatings obtained and a further study of their behaviour under wear, erosion, corrosion and E-C tests. These tests reproduce the process that takes place inside this kind of plants. A Ni-based powder alloy was used as a feedstock material for this study. The results show that spraying gas (Hydrogen or Propylene and different spray parameters give better corrosion or erosion properties. The coatings sprayed by Hydrogen shows better corrosion behaviour. The coatings sprayed by Propylene shows better mechanical and tribological properties. In both cases the Ni based HVOF coatings show good protection behaviour for the exchangers on the MSWI.

    En el presente trabajo se muestra la obtención, mediante la proyección térmica de alta velocidad (HVOF, de recubrimientos que presentan buenas prestaciones para la protección contra los procesos de erosión y oxidación que ocurren en el interior de las plantas incineradoras de residuos sólidos urbanos (IRSU. El artículo presenta la caracterización de recubrimientos HVOF optimizados para esta aplicación, así como un estudio detallado de su comportamiento bajo distintos ensayos de desgaste y corrosión que reproducen estos procesos. A través de la variación del gas combustible y las condiciones de proyección se han obtenido, sobre sustrato de acero al carbono, distintos recubrimientos a partir de un polvo del mismo material base níquel como materia prima. Se demuestra que con la variación de las relaciones de gas y las condiciones de proyección se obtienen pequeñas diferencias de comportamiento a la oxidación y a la erosión, de los recubrimientos. Los recubrimientos obtenidos a través de propileno como gas combustible muestran

  3. Avaliação do desgaste abrasivo causado pelas cerâmicas Duceram e Vita em resinas compostas pelo método do disco retificado Evaluation of the abrasive wear caused by the ceramics Duceram and Vita in composite resins by the method of the ground disk

    Directory of Open Access Journals (Sweden)

    T. V. França

    2004-06-01

    Full Text Available O presente trabalho apresenta uma metodologia confiável e de execução rápida para a avaliação do desgaste abrasivo entre as cerâmicas Duceram e Vita nas resinas compostas Z-100 e Charisma. Estes materiais são amplamente utilizados nos consultórios e clínicas dentais para restaurações funcionais e estéticas dos dentes. Para avaliar o desgaste abrasivo entre os materiais, um disco dinâmico revestido com porcelana foi utilizado sobre um disco estático revestido com resina. Os resultados indicaram que a cerâmica Vita apresenta desgaste inferior a Duceram nas resinas analisadas.This work presents a fast and trustworthy methodology for the evaluation of the abrasive wear between the ceramics Duceram and Vita and the composites resins Z-100 and Charisma. These materials are widely used in dental clinics to restoration of function and aesthetics of the teeth. To evaluate the abrasive wear between the materials, a dynamic disk covered with ceramic was used contrary to a static disk covered with resin. The results showed that Vita presents an inferior wear against Duceram in the resins tested.

  4. Propuesta para la recuperación de los machetes Zuazaga de los centrales azucareros con electrodos de acero al cromo.

    OpenAIRE

    R. Collazo Carceller; H. López Salinas; A. Días Romero

    2009-01-01

    El trabajo resume el estudio y análisis desarrollado, para la presentación de una propuesta tecnológica de recuperación de los machetes Zuazaga, en nuestros centrales azucareros. Se determinó la influencia de los parámetros, energía introducida (Hi), número de capas (Nc) y ancho del depósito (Ad), en la morfología y el incremento de la resistencia al desgaste abrasivo, utilizando el electrodo de acero al cromo DUR 600. Se realizó una valoración económica de la propuesta tecnológicaThis work, ...

  5. Avaliação da resistência ao desgaste de aços inoxidáveis endurecíveis por precipitação nitretados Wear resistance evaluation of nitrided precipitation hardening stainless steels

    Directory of Open Access Journals (Sweden)

    Luiz Carlos Casteletti

    2010-03-01

    Full Text Available A nitretação por plasma consiste num tratamento efetivo para o aumento das durezas superficiais dos aços inoxidáveis, podendo ser realizada em temperaturas inferiores às usadas nos processos convencionais, evitando-se assim, a formação de nitretos de cromo, que prejudicariam a resistência à corrosão do material. Os aços inoxidáveis endurecíveis por precipitação foram desenvolvidos após a Segunda Guerra Mundial em decorrência das necessidades da indústria aeroespacial, que necessitava de materiais resistentes à corrosão em temperaturas mais elevadas. Nesse trabalho, foi produzido um aço inoxidável endurecível por precipitação com uso de Nb e um aço comercial PH 13-8Mo endurecível por precipitados à base de Cu, para fins de comparação em termos de produção de camadas nitretadas e de resistências ao desgaste abrasivo. O Nb mostrou-se um eficiente formador de precipitados endurecedores do aço, com o pico de dureza ocorrendo em poucos minutos de tratamento. Nos dois aços, obtiveram-se camadas nitretadas com boa uniformidade. A resistência ao desgaste do aço com Nb nitretado foi muito superior à do aço PH 13-8Mo também nitretado.Plasma nitriding is an effective treatment to increase the surface hardness of stainless steel and may be performed in temperatures below those used in conventional nitriding procedures, thereby avoiding the formation of chromium nitrides that would deteriorate the corrosion resistance of the material. The precipitation hardened stainless steels were developed after the Second World War as a result of the needs of the aerospace industry, which needed materials resistant to corrosion at higher temperatures. In this research, a precipitation hardening Nb stainless steel and a PH 13-8Mo precipitation hardened stainless steels with Cu were produced, for purposes of comparison in terms of the production of nitrided layers and abrasive wear resistances. Nb proved to be an effective hardening

  6. Estudo comparativo da resistência ao desgaste abrasivo do revestimento de três ligas metálicas utilizadas na indústria, aplicadas por soldagem com arames tubulares Comparative study of the wear resistance of three metal cored wire welded coatings used in industry

    Directory of Open Access Journals (Sweden)

    Ricardo Vinícius de Melo Leite

    2009-12-01

    Full Text Available As ligas metálicas aplicadas por soldagem em superfícies, objetivando a proteção contra o desgaste e o conseqüente aumento da vida útil de peças e equipamentos, têm sido utilizadas em larga escala nas indústrias de bens de consumo e nos setores de mineração e sucroalcooleiro. O desgaste abrasivo em peças e equipamentos representa, nestas industriais, um dos principais fatores de depreciação de capital e uma importante fonte de despesas com manutenção. Para a aplicação do revestimento por soldagem, os arames tubulares têm sido uma alternativa cada vez mais viável, devido à sua alta produtividade e qualidade de solda, substituindo, em parte, o uso do eletrodo revestido. O objetivo deste trabalho é fazer um estudo comparativo da resistência ao desgaste abrasivo do revestimento aplicado por soldagem com arames tubulares autoprotegidos de três ligas metálicas utilizadas na indústria, uma do tipo Fe-Cr-C, outra do tipo Fe-Cr-C com adição de nióbio e boro e a terceira, do tipo Fe-Cr-C com adição de nióbio. Os revestimentos anti-desgaste, conhecidos como revestimento duro, foram aplicados em chapas de aço carbono, com os mesmos parâmetros e procedimentos de soldagem. Os corpos de prova foram obtidos por corte e retificação e foram submetidos a ensaios de desgaste abrasivo, em um abrasômero Roda de Borracha, conforme procedimento estabelecido pela norma ASTM G65-91. Os resultados obtidos demonstraram que a liga Fe-Cr-C com adição de Nióbio e Boro apresentou desempenho superior em relação ao desgaste abrasivo.The metal alloys deposited by welding on the components surface, with the objective of protection against wear and the consequent increase in the lifetime of parts and equipments, have been used extensively in the consumer products industry and sectors of Mining and Sugar & alcohol. The abrasive wear on parts and equipments represents one of the main depreciation factors of capital and the major source of

  7. Estudo comparativo da reabsorção radicular apical em pacientes bruxônomos e pacientes sem sinais clínicos de desgaste dentário Comparative study of apical root resorption in patients whith bruxism and without clinical signs of dental wearing

    OpenAIRE

    Rebeca Odebrech; Graziela L. Canto; Adriana C. Bortolon

    2004-01-01

    A reabsorção radicular, assim como o bruxismo, são temas amplamente abordados na literatura, contudo, a associação dos mesmos ainda permanece pouco documentada. Desse modo, esta pesquisa objetiva comparar pacientes portadores de bruxismo e pacientes sem sinais clínicos de desgaste dentário em relação à quantidade de reabsorção radicular apical nos incisivos superiores. Para tanto foram avaliados clínica e radiograficamente 64 pacientes, perfazendo um total de 256 incisivos acompanhados. Os re...

  8. Caracterização in Situ de Propriedades Mecânicas de Materiais Resistentes ao Desgaste Abrasivo Usando o Método da Indentação In Situ Determination of Mechanical Properties of Abrasive Wear Resistant Materials Using the Indentation Method

    OpenAIRE

    Hans Berns; Sinésio D. Franco

    1997-01-01

    O desempenho de materiais polifásicos em sistemas tribológicos envolvendo desgaste abrasivo é função de uma série de fatores, a saber: condições de operação, características de projeto e das propriedades do abrasivo e dos microconstituintes do material utilizado. Neste trabalho são apresentados resultados de ensaios de indentação em diferentes microconstituintes e partículas duras, através dos quais as propriedades mais importantes para o fenômeno abrasivo são determinadas in situ. Dentre ess...

  9. Los procesos de estrés laboral y desgaste profesional (burnout): diferenciación, actualización y líneas de intervención Stress and burnout at work: differences, updates and lines of intervention

    OpenAIRE

    Raquel Rodríguez Carvajal; Sara de Rivas Hermosilla

    2011-01-01

    El escenario laboral actual marcado por la globalidad y la inestabilidad genera unas condiciones que hace que muchos profesionales experimenten frustración y un alto nivel de tensión emocional, que conlleva un aumento de los niveles de estrés laboral y del desgaste profesional. La importancia del estudio del estrés laboral y el burnout ha incrementado en los últimos años la productividad científica en estos temas. Se ha realizado por ello una revisión de la literatura para ofrecer una visión ...

  10. Prevalencia del síndrome de desgaste profesional (burnout en odontólogos mexicanos del sector educativo y privado Prevalence of the syndrome of professional exhaustion (burnout in mexican dentists of the education sector and private

    Directory of Open Access Journals (Sweden)

    Enrique Castañeda Aguilera

    2012-09-01

    Full Text Available Objetivo: Determinar la prevalencia del síndrome de desgaste profesional (burnout en odontólogos del sector educativo y privado. Material y métodos: Estudio observacional, descriptivo y transversal, mediante el censo del personal odontológico de la Zona Metropolitana de Guadalajara, México de la Universidad de Guadalajara y los que ejercen la práctica privada, donde participaron 135 de ellos aplicándoseles una ficha de identificación y el Maslach Burnout Inventory-Human Services Survey en forma auto-administrada. Las estadísticas descriptivas y el análisis inferencial se realizaron con apoyo del SPSS 15.0 y Epi-infoV6.1. Resultados: Se logró el 90,0 % de respuesta. Se detectó una frecuencia del síndrome de desgaste profesional (burnout en el 50,3 % de ellos. Se obtuvieron diferencias significativas en función a ser menor de 40 años de edad. Se observó la correlación negativa entre las subescalas agotamiento emocional y despersonalización y positiva entre la falta de realización personal en el trabajo. Conclusiones: El síndrome de desgaste profesional (burnout es frecuente (50,3 % en los odontólogos, sus principales factores de riesgo: laborar en la práctica privada, el ser mujer, menor de 40 años de edad, sin pareja estable y con más de 15 años con pareja, el no trabajar la pareja, sin hijos, ser especialista, con menos de 10 años de antigüedad laboral y en el puesto actual de trabajo más de 10 años, laborar en el turno matutino, contratación definitiva y el tener otro trabajo. La afectación del agotamiento emocional y la despersonalización se comporta como el síndrome. Los niveles medios de las subescalas se encuentran en general cerca de la normalidad. Se encontró una correlación negativa entre las subescalas agotamiento emocional y despersonalización y positiva entre la falta de realización personal en el trabajo con la presencia del síndrome. Es necesario establecer medidas preventivas o de intervenci

  11. Behaviour of alloys by abrasive erosion and carbide formation by welding; Comportamiento frente al desgaste abrasivo de las aleaciones con tendencias a la formacion de carburos aplicadas por soldadura

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    The abrasion of the mechanic elements for cut and extraction of minerals implies high cost because the replacement of the damaged elements and shutdown of the machines high cost because the replacement of the damaged elements and shutdown of the machines. The present article abstracts the results obtained in a project of investigation where the variables determining the quality of antiabrasive recharges have been obtained, and a method of evaluation of the different products of this type of recharges existing in the market have been evaluated. (Author) 9 refs.

  12. Influencia de la degradación hidrotérmica en la resistencia mecánica y en el comportamiento al desgaste de 3Y-TZP

    OpenAIRE

    Mestra Rodríguez, Álvaro Miguel; García Marro, Fernando; Kiran Chitapalli, Ravi; Armas Sancho, Zamir de; Anglada Gomila, Marcos Juan

    2012-01-01

    En este trabajo se realiza un estudio comparativo de la influencia de la degradación hidrotérmica a baja temperatura de circona tetragonal estabilizada con el 3% molar de Itria (3Y-TZP) en la resistencia mecánica a flexión y en el comportamiento bajo cargas de indentación esférica. Se presentan resultados de resistencia mecánica a flexión y de indentación esférica monotónica así como de ensayos de rayado en probetas artificialmente degradadas durante diferentes períodos de tiempo. Se pone ...

  13. Efecto del conteo de nódulos en la resistencia al desgaste por abrasión de los hierros dúctiles austemperados. // Effect of nodules count in the abrasive wear of austempered ductile irons.

    OpenAIRE

    C. J. Diez Cicero; G. R. Fernández López; U. Ordóñez Hernández; C. R. Figueroa Hernández; F. Mondelo

    2009-01-01

    Entre los materiales metálicos de mayor demanda, la producción de hierro con grafito nodular,ocupa en la actualidad, uno de los lugares más importantes entre los hierros fundidos de altaresistencia, y con la introducción del tratamiento térmico de austemperado, aplicado a estasfundiciones, se da lugar a una nueva familia de materiales, caracterizados por su alta resistenciamecánica y elevada tenacidad, que mantienen la economía y facilidad de producción de lasfundiciones nodulares.Este trabaj...

  14. Efecto del conteo de nódulos en la resistencia al desgaste por abrasión de los hierros dúctiles austemperados. // Effect of nodules count in the waste by abrasion resistance for ductile austempering irons.

    OpenAIRE

    C. J. Diez Cicero; G. R. Fernández López; U. Ordóñez Hernández

    2004-01-01

    Entre los materiales metálicos de mayor demanda, la producción de hierro con grafito nodular, ocupa en la actualidad unode los lugares más importantes entre los hierros fundidos de alta resistencia, y con la introducción del tratamiento térmicode austemperado aplicado a estas fundiciones, se da lugar a una nueva familia de materiales, caracterizados por su altaresistencia mecánica y elevada tenacidad, que mantienen la economía y facilidad de producción de las fundicionesnodulares.Este trabajo...

  15. Comportamiento frente al desgaste y fricción de aceros empleados en líneas de manutención aérea ensayados con y sin lubricación

    OpenAIRE

    Castro Regal, G.; Fernández-Vicente, A.; Martínez, M A

    2005-01-01

    The sliding friction and wear behaviour of different steel qualities were investigated with and without lubrication conditions. Steel qualities tested are normally used in the overhead conveyor system of many industrial fields, like the automotive sector. Sliding wear tests have been conducted by means of a pin-on-disk machine. A 100Cr6 steel similar to that used within the overhead conveyor trolleys has been employed as a pin. Friction coefficient values obtained under lubrication conditions...

  16. Influencia de los tratamientos térmicos en el comportamiento frente al desgaste por abrasión de una fundición de grafito esferoidal obtenida mediante adición de boro

    OpenAIRE

    Varela, A; García, A.; Zaragoza, S.; Mier, J. L.; Barbadillo, F.; García, L.

    2008-01-01

    By adding boron to the liquid metal, it is possible to obtain spheroidal graphite cast iron without any need for special inoculants. The boron may be in metallic form; alternatively, borax, ferroboron, boron carbonate or borocalcium can be used. These alloys as cast present a pearlite matrix with more or less spheroidal graphite, which is usually edged in ferrite that has markings in the shape of bull’s eye. With normalising, the ferrite edges are eliminated. Thus, a pearlite matrix is achiev...

  17. Resistencia al desgaste de recubrimientos Fe-Nb-Cr-W, Nb, AISI 1020 y AISI 420 producidos por proyección térmica por arco eléctrico

    OpenAIRE

    López-Covaleda, E. A.; Mercado-Velandia, J. L.; Olaya-Flórez, J. J.

    2013-01-01

    The commercial materials 140MXC (with iron, tungsten, chrome, niobium), 530AS (AISI 1015 steel) and 560AS (AISI 420 steel) on AISI 4340 steel were deposited using thermal spray with arc. The aim of work was to evaluate the best strategy abrasive wear resistance of the system coating-substrate using the following combinations: (1) homogeneous coatings and (2) coatings depositing simultaneously 140MXC + 530AS and 140MXC + 560AS. The coatings microstructure was characterized using Optical micros...

  18. Effect of the percentage of reinforcement on the wear in the metal matrix composites sintered with abnormal glow discharge; Efecto del porcentaje de refuerzo frente al desgaste en compuestos de matriz metalica sinterizados con descarga luminiscente anormal

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Velasquez, S.; Pineda-Triana, Y.; Aguilar-Castro, Y.; Vera-Lopez, E.

    2016-05-01

    In this study an analysis of the behavior of dry wear coefficient of a Metal Matrix Composite (MMC) in 316 stainless steel reinforced with particles of titanium carbide (TiC) according to ASTM G 99 standards, in a pin-on-disk test. In this research it is tested the effect of the percentage of reinforcement in the MMC manufactured with 3, 6 y 9% (vol.) of TiC, in samples compacted at 800 MPa, generating different values of grain size, hardness and density, they are sintered with abnormal glow discharge, at a temperature of 1200 degree centigrade ±5 degree centigrade, with a protection atmosphere H{sub 2} - N{sub 2} and a permanence time of 30 minutes. According to the results obtained it is concluded that the best condition for the MMC manufacturing, in relation to the reinforcement percentage, is the one obtained when the mixture contains 6% of TiC compacted at 800 MPa. In these conditions, it was obtained: achieving smaller grain size, the greater hardness and the lowest coefficient of friction. In this respect, it was observed that the incorporation of the ceramic particles (TiC) in a matrix of austenitic steel (316) shows significant improvements in the resistance to the wear. (Author)

  19. Comparative study of the wear resistance of Al2O3-coated MA956 superalloy

    Directory of Open Access Journals (Sweden)

    Canahua Loza, Hugo

    2000-10-01

    Full Text Available Preoxidation of the MA956 superalloy, proposed as a prosthetic biomaterial, generates a compact and inert a-alumina surface layer. The aim of this study is to assess the wear resistance provided by this alumina layer on the MA956 alloy in comparison with the same coated alloy and versus high density polyethylene. Comparative wear tests were carried out in both dry and wet conditions using the couples MA956/MA956, MA956/UHMWPE (ultra high molecular weight polyethylene and 316LVM/UHMWPE. The results corresponding to the couples MA956/MA956, with and without alumina layer, show that the load has more significant effect than the rotation speed on the weight loss and on the roughness. On the other hand the alumina surface layer provides a clear wear protection. The weight losses of the MA956 specimen in this couple are ten times lower when testing under wet conditions than under dry conditions. The MA956/UHMWPE couple behaves much better than the 316LVM/UHMWPE, as it presents the lowest values of friction coefíicient and weight losses of the MA956 specimen. These are only detectable after 70,000 cycles under a 70 MPa contact pressure. This couple offers the best guarantee of a prolonged service life for articulated parts in a prosthesis.

    La superaleación MA956, que se ha propuesto como biomaterial para prótesis osteoarticulares genera, mediante un adecuado tratamiento de preoxidación, una capa superficial, compacta e inerte, de alúmina alfa. El objetivo del presente trabajo es el estudio de la resistencia al desgaste de esta capa de alúmina, cuando se encuentra en contacto con la propia aleación recubierta y con polietileno de alta densidad. Se realizaron ensayos comparativos de desgaste, tanto en seco como en húmedo, con los pares MA956/MA956, MA956/UHMWPE (polietileno de muy elevado peso molecular y 316LVM/UHMWPE. Los resultados obtenidos con el par MA956/MA956, con y sin capa de alúmina, indican que la carga es el factor de mayor

  20. Fricción y desgaste en elementos circulares empleados en pasadores // Friction and waste in elements circular employees in pins.

    Directory of Open Access Journals (Sweden)

    D. Alcántara-Borges

    2009-05-01

    Full Text Available El presente trabajo tiene como objetivo establecer el comportamiento de los pasadores fabricadosde acero 45 empleados en las esteras de los equipos de laboreo minero, los cuales por su condiciónde trabajo, se desgastan prematuramente producto de la fricción por rodadura, pero que a la vez,este fenómeno trae consigo el endurecimiento superficial de las capas tratadas térmicamente. Paradar cumplimiento al objetivo se utilizaron probetas de los elementos antes de su puesta en marchay retirado después de su función. Fueron preparadas probetas de 30 x 30 mm cortadas conabundante refrigeración para comprobar su composición química con el empleo del espectrómetrocuántico de masa y su dureza inicial y final, así como probetas de 15 x 15 mm para el análisismicroestructural. Se establece el comportamiento de la estructura cristalográfica del pasadortratado térmicamente antes de ser sometido a carga y la estructura después del período de vidaútil. También con el trabajo se demuestra el endurecimiento del acero por acritud cuando elmaterial es sometido a la fricción por rodadura.Palabras claves: pasadores, fricción, rodadura, análisis microestructural, endurecimiento superficial.______________________________________________________________________________AbstractThe present work has as objective to establish the behaviour of the fabricated pins of steel grade 45used in the mats of mining equipment. Due to its working condition, these pieces prematurely wearaway because of the rolling friction. At the same time, this phenomenon produce a superficialhardening of the outside layers thermally heat treated. To accomplish this aim some samples ofnon-used tubes and some used for a period of time were compared. Samples of 30 x 30 mm, cutwith abundant refrigeration, were used for chemical analysis with the employment of a massquantum spectrometer. The initial and final hardness of the different samples were also measured.Samples of 15 x 15 mm

  1. AL Amyloidosis

    Directory of Open Access Journals (Sweden)

    Desport Estelle

    2012-08-01

    Full Text Available Abstract Definition of the disease AL amyloidosis results from extra-cellular deposition of fibril-forming monoclonal immunoglobulin (Ig light chains (LC (most commonly of lambda isotype usually secreted by a small plasma cell clone. Most patients have evidence of isolated monoclonal gammopathy or smoldering myeloma, and the occurrence of AL amyloidosis in patients with symptomatic multiple myeloma or other B-cell lymphoproliferative disorders is unusual. The key event in the development of AL amyloidosis is the change in the secondary or tertiary structure of an abnormal monoclonal LC, which results in instable conformation. This conformational change is responsible for abnormal folding of the LC, rich in β leaves, which assemble into monomers that stack together to form amyloid fibrils. Epidemiology AL amyloidosis is the most common type of systemic amyloidois in developed countries with an estimated incidence of 9 cases/million inhabitant/year. The average age of diagnosed patients is 65 years and less than 10% of patients are under 50. Clinical description The clinical presentation is protean, because of the wide number of tissues or organs that may be affected. The most common presenting symptoms are asthenia and dyspnoea, which are poorly specific and may account for delayed diagnosis. Renal manifestations are the most frequent, affecting two thirds of patients at presentation. They are characterized by heavy proteinuria, with nephrotic syndrome and impaired renal function in half of the patients. Heart involvement, which is present at diagnosis in more than 50% of patients, leading to restrictive cardiopathy, is the most serious complication and engages prognosis. Diagnostic methods The diagnosis relies on pathological examination of an involved site showing Congo red-positive amyloid deposits, with typical apple-green birefringence under polarized light, that stain positive with an anti-LC antibody by immunohistochemistry and

  2. Análisis numérico sobre esfuerzos y áreas de contacto en una PTR Scorpio II® Stryker®. Base para el diseño de PTR personalizada al fenotipo Mexicano

    Directory of Open Access Journals (Sweden)

    Rafael Rodríguez-Martínez

    2013-06-01

    Full Text Available Título en ingles: Numerical analysis on effort and contact areas in a TKR Scorpio II® of Stryker®. Basis for the design of customized TKR in accordance with the Mexican PhenotypeTítulo corto: Análisis numérico sobre esfuerzos y áreas de contacto en una PTRResumen: El desgaste de los insertos de Polietileno de Ultra-Alto Peso Molecular (UHMWPE pos sus siglas en inglés continúa afectando la longevidad de las prótesis totales de rodilla (PTR junto con el aflojamiento aséptico, y ambos constituyen las dos principales causas de falla de las prótesis. Considerando esto, es necesario encontrar soluciones adecuadas para evitar el desgaste excesivo y hasta la ruptura de los insertos de polietileno. En este trabajo se realizó el estudio mediante simulación numérica de una PTR Scorpio II® Stryker®, la cual se retiró por desgaste del inserto de UHMWPE en el Hospital 1° de Octubre del ISSSTE en México. Se utilizaron las hipótesis de Bartel et al. (1995 y Chillag et al. (1991 para la validación del método numérico utilizado, las cuales establecen que el desgaste del polietileno puede reducirse utilizando insertos tibiales de mayor espesor, lo cual disminuye las presiones de contacto. Los análisis se realizaron mediante MEF variando el espesor del inserto de 6, 8, 10, 12 y 14 mm, suponiendo cargas axiales de tipo cuasi-estático en la articulación a cero grados de flexión, para 1.33 veces el peso de un individuo de 75 kg (736 N empleando el ciclo normalizado de marcha. Los resultados obtenidos muestran similitud con los reportados por Bei et al. (2004 y Deen et al. (2006. Después de validar el método, se desarrolló el modelo de MEF de la PTR y se determinaron las curvas de esfuerzo y de áreas de contacto del inserto de UHMWPE, con lo que se obtuvo información importante para modificar el diseño y obtener una prótesis de geometría conforme en los planos coronal y sagital del inserto femoral y el inserto de polietileno, de

  3. Propuesta para la recuperación de los machetes Zuazaga de los centrales azucareros con electrodos de acero al cromo.

    Directory of Open Access Journals (Sweden)

    R. Collazo Carceller

    2009-09-01

    Full Text Available El trabajo resume el estudio y análisis desarrollado, para la presentación de una propuesta tecnológica de recuperación de los machetes Zuazaga, en nuestros centrales azucareros. Se determinó la influencia de los parámetros, energía introducida (Hi, número de capas (Nc y ancho del depósito (Ad, en la morfología y el incremento de la resistencia al desgaste abrasivo, utilizando el electrodo de acero al cromo DUR 600. Se realizó una valoración económica de la propuesta tecnológicaThis work, sumarises the study and the analisys developed, to prupose the Zuazaga cut cane thecnology recuperation, in aur sugar mills. The parameters influency was determinated, Heat input (Hi, Number of layers (Nc and the Cord whith (Ad, in the mofology and the abrasive wear resistance increase, using the cromiun steel UTP DUR - 600. The economical calculation of the thecnology was done.

  4. All About ALS

    Science.gov (United States)

    ... please review our exit disclaimer . Subscribe All About ALS Understanding a Devastating Disorder In the summer of ... of research dollars—for a fatal disease called ALS. ALS stands for amyotrophic lateral sclerosis. It’s also ...

  5. ESTUDIO DEL DESGASTE EROSIVO POR CAVITACIÓN DE UN ACERO AUSTENÍTICO DE ALTO NITRÓGENO APOYADO EN EL USO DE LA DIFRACCIÓN DE ELECTRONES RETROPROYECTADOS-EBSD ASSESSMENT OF CAVITATION-EROSION WEAR OF A HIGH NITROGEN AUSTENITIC STAINLESS STEEL FROM ELECTRON BACKSCATTERING DIFFRACTION-EBSD

    Directory of Open Access Journals (Sweden)

    Dairo Hernán Mesa Grajales

    2010-08-01

    Full Text Available Muestras de acero inoxidable con estructura austenítica y contenido aproximado de nitrógeno de 0,9% en peso en solución sólida fueron sometidas a ensayos de cavitación vibratoria en agua destilada, con el fin de estudiar la evolución del desgaste erosivo por cavitación (EC a escala del tamaño de grano (mesoescala. Las muestras fueron obtenidas por medio de nitruración gaseosa a alta temperatura (HTGN del acero inoxidable dúplex UNS S31803, las cuales fueron caracterizadas por difracción de electrones retroproyectados (EBSD, a fin de obtener información de la orientación cristalina de los granos en la superficie a ser cavitada. La técnica de microscopía electrónica de barrido (SEM, fue usada para acompañar el proceso de desgaste para diferentes tiempos de ensayo. Como resultados de los ensayos de cavitación se determinó la pérdida de masa y se hizo un estudio secuencial de la apariencia superficial de las muestras para determinar los mecanismos de desgaste operantes en cada etapa. Los resultados fueron analizados a la luz de la caracterización cristalográfica previa. Para propósitos de comparación, fue usado el acero austenítico convencional UNS S30403. A partir de los resultados se observó que tanto la nucleación del daño como su evolución se dan de forma heterogénea a escala del tamaño de grano, resultado atribuido a la anisotropía en la deformación plástica. El carácter heterogéneo del daño por cavitación fue atribuido principalmente a las características de los límites de grano y a la microtextura dentro de los granos.Stainless steel samples with 100% austenitic microstructure and alloyed with 0.9 wt-% of nitrogen in solid solution were tested under vibratory cavitation experiments in distilled water to study the cavitation-erosion wear (EC at grain size level (mesoscale. Fully austenitic samples were obtained by high temperature gas nitriding (HTGN a commercially available dúplex stainless steel, UNS

  6. Caracterização in Situ de Propriedades Mecânicas de Materiais Resistentes ao Desgaste Abrasivo Usando o Método da Indentação In Situ Determination of Mechanical Properties of Abrasive Wear Resistant Materials Using the Indentation Method

    Directory of Open Access Journals (Sweden)

    Hans Berns

    1997-08-01

    Full Text Available O desempenho de materiais polifásicos em sistemas tribológicos envolvendo desgaste abrasivo é função de uma série de fatores, a saber: condições de operação, características de projeto e das propriedades do abrasivo e dos microconstituintes do material utilizado. Neste trabalho são apresentados resultados de ensaios de indentação em diferentes microconstituintes e partículas duras, através dos quais as propriedades mais importantes para o fenômeno abrasivo são determinadas in situ. Dentre essas destacam-se a dureza H, a tenacidade à fratura K IC, o módulo de elasticidade E, a relação trabalho plástico / trabalho elástico Wp / We e a relação de durezas entre o microconstituinte e o agente abrasivo. Em muitas situações práticas esses sistemas encontram-se em temperaturas elevadas. Assim, neste trabalho, é também apresentada a influência da temperatura sobre algumas dessas propriedades. Os resultados obtidos mostram a grande potencialidade dessa técnica no processo de seleção e desenvolvimento de materiais resistentes ao desgaste.The wear resistance is not an intrinsic property of materials but depends on the operating conditions, design properties, type of abrasive and material properties. In this work the results of microindentation tests in different hard particles of wear resistant alloys and composites, as well as in bulk materials are presented. Continuous monitoring the load and the indenter penetration depth it is possible to obtain in situ important properties in the wear process of the alloy microconstituents. With this technique it was possible to determine the hardness H, the fracture toughness K IC, the Young modulus E and the relationship between the plastic and elastic work of deformation Wp / We. Since in many practical situations the process temperature is an important parameter, its influence on some of these properties is also considered. The results show that this technique may constitute a

  7. Control en modo deslizante aplicado a sistemas de acondicionamiento de potencia de satélites

    OpenAIRE

    Calvente Calvo, Francisco Javier

    2001-01-01

    El sistema de acondicionamiento de potencia es clave para el funcionamiento correcto del resto de sistemas eléctricos de un satélite. Los reguladores conmutados continua - continua son las piezas que enlazan los paneles solares y las baterías con el bus principal de alimentación. La estabilidad, precisión y robustez del sistema de control son fundamentales en el diseño de esos convertidores.Desde el punto de vista de los especialistas en control, los convertidores conmutados son sistemas de e...

  8. Estudo comparativo da reabsorção radicular apical em pacientes bruxônomos e pacientes sem sinais clínicos de desgaste dentário Comparative study of apical root resorption in patients whith bruxism and without clinical signs of dental wearing

    Directory of Open Access Journals (Sweden)

    Rebeca Odebrech

    2004-05-01

    Full Text Available A reabsorção radicular, assim como o bruxismo, são temas amplamente abordados na literatura, contudo, a associação dos mesmos ainda permanece pouco documentada. Desse modo, esta pesquisa objetiva comparar pacientes portadores de bruxismo e pacientes sem sinais clínicos de desgaste dentário em relação à quantidade de reabsorção radicular apical nos incisivos superiores. Para tanto foram avaliados clínica e radiograficamente 64 pacientes, perfazendo um total de 256 incisivos acompanhados. Os resultados demonstram que há uma correlação positiva entre bruxismo e reabsorção radicular.Root resorption and bruxism are largely study in literature. However their association still remains few documented. The aim of this study is compare the quantity of apical root resorption in upper permanent incisors in patients with bruxism and without clinical signs of dental wearing. 64 patients (256 incisors were evaluated clinical and radiografically. The results shows the correlation between bruxism and root resorption.

  9. Influence of silicon content and heat treatment on wear resistance of white chromium cast irons under high speed solidification conditions; Influencia del contenido de silicio y el tratamiento termico en la resistencia al desgaste de fundiciones blancas al cromo en condiciones de rapida solidificacion

    Energy Technology Data Exchange (ETDEWEB)

    Goyo, L.; Varela, A.; Verhaege, M.; Garcia, A.; Mier, J.; Moors, M.

    2012-11-01

    The influence of silicon content and heat treatment on microstructure, abrasive and dry friction wear resistance of a 3 % C, 12 % Cr cast iron, under fast solidification conditions is studied. The fast solidification condition diminishes the carbide volume and the silicon content increases their dispersion and finesses. All matrixes obtained were perlitics, whit different finesses. No intermediate transformation products were noticed. Hardness had little variation. Austenization treatment show little effectivity, with tendency to increase wear in reference to as cast and maintenance treatments. Behavior under dry friction and abrasive wear were similar under test conditions applied whit more influence of carbide morphology in the abrasive wear conditions. (Author) 32 refs.

  10. Aussprache als motorische Fertigkeit

    DEFF Research Database (Denmark)

    Bonner, Maria

    2013-01-01

    Authentische Aussprache gilt im Fremdsprachenunterricht als schwer erreichbares Ziel, fremdsprachlicher Akzent wird als nahezu unvermeidbar gesehen. Weder die Hypothese einer kritischen Periode für den Erwerb einer authentischen Aussprache noch das Konzept der Fossilierung im Sprachlernprozess...

  11. Amyotrophic Lateral Sclerosis (ALS)

    Science.gov (United States)

    ... benefit of 16 months before onset of severe respiratory failure. Other treatments are designed to relieve symptoms and ... of ALS. Most people with ALS die from respiratory failure, usually within 3 to 5 years from the ...

  12. Initial Symptoms of ALS

    Science.gov (United States)

    ... Chapters Certified Centers and Clinics Support Groups About ALS About Us Our Research In Your Community Advocate ... Diagnosis En español Symptoms The initial symptoms of ALS can be quite varied in different people. One ...

  13. Desbordamientos culturales en torno al 15-M The 15-M movement in its cultural context

    Directory of Open Access Journals (Sweden)

    Luis Moreno-Caballud

    2013-03-01

    Full Text Available Este artículo es una exploración del contexto cultural amplio del movimiento 15-M en el estado español. Comienza por proponer que el 15-M es un síntoma más de un generalizado desgaste de la hegemónica “Cultura de la transición”, que estableció una serie de acuerdos tácitos en torno a la necesidad de una sociedad vertical y de expertos basada en el sistema de partidos políticos y el capitalismo financiero. Este desgaste ha sido facilitado por la emergencia de las nuevas tecnologías digitales de comunicación, que han permitido la propagación de formas de colaboración horizontales y empoderadoras. Frente a una esfera pública habitualmente marcada por las opiniones de individuos “expertos”, en la Red emergen prácticas de creación y circulación de dispositivos inacabados que forman “comunidades de conocimiento” en las que nadie sabe todo, pero todos comparten aquello que saben. En estas culturas del compartir florecen en ocasiones proyectos capaces de gestionar de forma sostenible recursos por parte de las comunidades que los disfrutan: los llamados procomunes. En los intentos de hacerse cargo de la sostenibilidad de la vida común que el 15-M desarrolló en plazas y acampadas se hace evidente la especial sensibilidad de este movimiento hacia las formas de cooperación cotidiana y el procomún. No en vano el 15-M, como el resto de los movimientos internacionales de las plazas que emergieron en 2011, es una respuesta al expolio de la riqueza común por parte de las élites del neoliberalismo global.This essay is an exploration of the wide cultural context of the “indignados” or 15-M movement in the Spanish state. It starts by proposing that 15-M is one of the symptoms of a widespread erosion of the hegemonic “Culture of the transition”, which established a series of tacit agreements around the necessity of a vertical and expert society, based in the political parties system and financial capitalism. This erosion

  14. An electrochemical investigation of the corrosion behavior of Al-Si-Cu hypereutectic alloys in alcoholic environments

    Directory of Open Access Journals (Sweden)

    Traldi, S. M.

    2003-12-01

    Full Text Available Al-Si-Cu hypereutetic alloys produced by spray forming are mostly used in the automotive industry, especially for cylinder liners. They have the advantage of low weight associated with low coefficient of thermal expansion and excellent mechanical properties - mainly wear resistance at high temperatures. The corrosion resistance of these alloys in fuels, particularly alcoholic media, however is not yet known. In this investigation, electrochemical impedance spectroscopy (EIS and potentiodynamic polarisation have been used to evaluate the corrosion resistance of a hypereutectic Al-Si-Cu alloy in alcoholic environments. The EIS tests were carried out in pure ethanol, and ethanol with small additions (1 mM of acid and chloride, to investigate the effect of these contaminants on corrosion resistance. The corrosion resistance of a grey cast iron has also been evaluated in pure ethanol for comparison. The Al-Si-Cu alloy showed high corrosion resistance in pure ethanol, far superior to that of grey cast iron in the same medium.

    Aleaciones hipereutécticas producidas por conformación por spray son muy empleadas en la industria automovilística, especialmente en los revestimientos de los cilindros. Tienen la ventaja de añadir menos peso con bajo coeficiente de expansión térmica y excelentes propiedades mecánicas, sobre todo resistencia al desgaste en altas temperaturas. Todavía, la resistencia a la corrosión de estas aleaciones en combustibles no es conocida. En este estudio fueron utilizadas las técnicas de espectroscopia de impedancia electroquímica y polarización potenciodinámica, para evaluar la resistencia a la corrosión de una aleación hipereutéctica Al-Si-Cu en medio alcohólico. Las pruebas fueron conducidas en etanol puro y etanol con pequeñas adiciones (1 mM de ácido y cloruro, con la finalidad de investigar el efecto de estos contaminantes en la resistencia a la corrosión. Hierro fundido gris, también fue

  15. Los procesos de estrés laboral y desgaste profesional (burnout: diferenciación, actualización y líneas de intervención Stress and burnout at work: differences, updates and lines of intervention

    Directory of Open Access Journals (Sweden)

    Raquel Rodríguez Carvajal

    2011-01-01

    Full Text Available El escenario laboral actual marcado por la globalidad y la inestabilidad genera unas condiciones que hace que muchos profesionales experimenten frustración y un alto nivel de tensión emocional, que conlleva un aumento de los niveles de estrés laboral y del desgaste profesional. La importancia del estudio del estrés laboral y el burnout ha incrementado en los últimos años la productividad científica en estos temas. Se ha realizado por ello una revisión de la literatura para ofrecer una visión global y actualizada de ambos procesos. Se muestran los principales modelos y las variables de estudio vigentes así como las principales líneas más actuales de intervención que se vienen desarrollando hasta la fecha.Today´s workplace is constantly changing. Organizations are confronted with multiple challenges, brought by globalization and instability. This situation causes many professionals to experience frustration and a high level of emotional tension, which may easily lead to increased levels of occupational stress and burnout. The importance of studying occupational stress and burnout has led to an increase in the scientific productivity in these areas during the last years. The present literature review provides an overview and update of both occupational stress and burnout processes. The main models are presented as well as the current variables in study. The main lines of intervention that have been developed to date are also reviewed.

  16. Volver al desarrollo

    Directory of Open Access Journals (Sweden)

    Jaime Ornelas Delgado

    2012-01-01

    Full Text Available El desarrollo, categoría empleada para expresar el crecimiento económico, surge durante la "guerra fría" y si bien fue propuesta por teóricos metropolitanos, se asumió en Latinoamérica como parte de los instrumentos disponibles para lograr el crecimiento y alternativa al socialismo. El desarrollo mantuvo su vigencia entre 1945 y 1975, cuando al advenimiento del neoliberalismo fue paulatinamente retirado de la agenda de las preocupaciones nacionales e internacionales. Al iniciarse el siglo xxi, el fracaso del mercado autorregulado trajo de nueva cuenta al debate los problemas del desarrollo, lo que obliga a revisarlo críticamente, tanto como al concepto mismo para mostrar su carácter colonial, si se quiere construir caminos ajenos al neoliberal y superar los problemas que han hecho de Latinoamérica una de las regiones más desiguales del mundo.

  17. Jalta als Heterotopie

    OpenAIRE

    Schmid, Ulrich

    2013-01-01

    Jalta ist ein Ort, der sich im europäischen Kulturgedächtnis sowohl historisch als auch literarisch als "radikal anderer Ort" - als " Heterotopie" - festgesetzt hat. An der Konferenz von Jalta wurde 1945 eine neue Weltordnung geschaffen in der Hoffnung auf eine bessere Welt. Auch in den Werken von Anton ?echov, vor allem in denjenigen, die in Jalta entstanden sind, wird von einer anderen und besseren Welt geträumt.

  18. Pornographie als Metapher

    Directory of Open Access Journals (Sweden)

    Caroline Schubarth

    2010-02-01

    Full Text Available In diesem Artikel werden unterschiedliche metaphorische Verwendungen des Pornografiebegriffs und deren Implikationen untersucht. Während die Existenz von Pornografie der feministischen Anti-Porno-Bewegung als Erklärung für die anhaltende Diskriminierung von Frauen in westlichen Gesellschaften dient, nutzen rechtskonservative Kräfte den Pornografievorwurf als Rechtfertigung für die Zensur von als deviant empfundenen Identitäten und sexuellen Praktiken.

  19. Pornographie als Metapher

    OpenAIRE

    Caroline Schubarth

    2010-01-01

    In diesem Artikel werden unterschiedliche metaphorische Verwendungen des Pornografiebegriffs und deren Implikationen untersucht. Während die Existenz von Pornografie der feministischen Anti-Porno-Bewegung als Erklärung für die anhaltende Diskriminierung von Frauen in westlichen Gesellschaften dient, nutzen rechtskonservative Kräfte den Pornografievorwurf als Rechtfertigung für die Zensur von als deviant empfundenen Identitäten und sexuellen Praktiken.This article...

  20. Efeito do consumo excessivo de oxigênio após exercício e da taxa metabólica de repouso no gasto energético Efecto del consumo excesivo de oxígeno después del ejercicio y de la tasa metabólica de reposo en el desgaste energético Effects of excess post-exercise oxygen consumption and resting metabolic rate in energetic cost

    Directory of Open Access Journals (Sweden)

    Giselle Foureaux

    2006-12-01

    Full Text Available A crescente prevalência de obesidade e sobrepeso ressalta a necessidade de intervenções para reverter esse quadro. Nesse contexto, a atividade física pode contribuir com um efeito duplo, por meio de mudanças fisiológicas agudas e crônicas: na primeira condição encontra-se o gasto energético do exercício e recuperação (EPOC - consumo excessivo de oxigênio após o exercício, e na segunda encontra-se a taxa metabólica de repouso (TMR. Dessa forma, o objetivo deste trabalho de revisão foi investigar o efeito do EPOC e da TMR como coadjuvantes nos programas de emagrecimento, buscando discutir os divergentes resultados encontrados na literatura, no que diz respeito à magnitude e duração do EPOC, bem como discutir o efeito do exercício na TMR. Os estudos demonstram, de forma geral, que o exercício de maior intensidade é capaz de promover maior EPOC, se comparado com um exercício de intensidade menor e, quando comparam o exercício resistido com o aeróbio, verifica-se maior EPOC no primeiro. Em relação às alterações da TMR, os resultados agudos mostram aumento significativo, porém os resultados em longo prazo são mais discrepantes, devido à dificuldade de mensurar essa variável, sem superestimá-la. Concluindo, a literatura aponta que a periodização de um treinamento que possa maximizar tanto o EPOC quanto a TMR podem ser importantes fatores para o emagrecimento e, embora, o custo energético dessas variáveis em uma sessão de exercício se mostre pequeno, em longo prazo poderá ser bastante significativo. No entanto, novos estudos deverão ser realizados com o intuito de confirmar essas evidências.La creciente prevalencia de la obesidad y el sobrepeso resalta la necesidad de intervenciones para reverter ese cuadro. En ese contexto, la actividad física puede contribuir con un doble efecto, por medio de cambios fisiológicos agudos y crónicos: en la primera condición se encuentra desgaste energético del ejercicio

  1. "Estudio tribologico de aceros para moldes. Aplicacion al moldeo por inyeccion de polibutilentereftalato reforzado con fibra de vidrio"

    Science.gov (United States)

    Martinez Mateo, Isidoro Jose

    fabricacion del molde, tienen una gran influencia sobre su comportamiento en servicio a lo largo de la vida util del molde. En la primera parte del presente estudio, a partir de ensayos punzon sobre disco, se ha determinado la relacion entre la resistencia al desgaste y la dureza de aceros para moldes obtenidos a partir de bloques de gran espesor, estudiando los principales mecanismos de desgaste que tienen lugar. A continuacion, con el fin de determinar el dano superficial que sufren los aceros para moldes en condiciones reales de inyeccion, se han estudiado distintos tipos de aceros utilizados comercialmente en moldes de inyeccion de polimeros y materiales compuestos, seleccionando las condiciones de operacion para determinar la variacion de la rugosidad superficial del acero en funcion del material inyectado, del numero de operaciones sucesivas de inyeccion y de la orientacion del flujo de inyeccion, mediante tecnicas de perfilometria optica y microscopia electronica de barrido. Ademas del dano superficial sufrido por el acero con el numero de piezas inyectadas, tambien se ha determinado la evolucion de la rugosidad superficial de los materiales inyectados, polibutilentereftalato (PBT) puro y materiales compuestos derivados de PBT por adicion de un 20 o un 50% en peso de fibra de vidrio. En el caso de las piezas inyectadas, se ha caracterizado su microestructura en funcion del flujo de inyeccion y de la densidad de fibra, se han determinado sus propiedades termicas y dinamico-mecanicas, asi como la variacion de la rugosidad superficial de las piezas inyectadas con el numero de operaciones de inyeccion y con la geometria de las distintas secciones de las piezas. Finalmente, se ha evaluado la resistencia a la abrasion de PBT reforzado con un 50% de fibra, en funcion del numero de piezas inyectadas y de la direccion de rayado con respecto a la orientacion del flujo de inyeccion.

  2. Sobre Al-Qarmuniyya

    OpenAIRE

    Fierro Bello, María Isabel

    1990-01-01

    [ES] En dos tradiciones escatológicas relativas a al-Andalus y recogidas por 'Abd al-Malik h Haha en su Ta'rg se hace referencia a Carmona. La mención de esta ciudad en dichas tradiciones debe ser puesta en relación con dos episodios de la historia de al-Andalus que tuvieron lugar antes de la muerte de Ibn Habib: la batalla de Carmona en época de 'Abd al-Rahman y la concentración de tropas omeyas en el mismo lugar durante el ataque normando en los años 229-30/844-5.

  3. Al-Anon/Alateen

    Science.gov (United States)

    Find an Al-Anon meeting Español | Français 2018 Int'l Convention Home About Group Meetings What If I'm not ready ... a meeting? What can I expect at an Al-Anon meeting? What was my first meeting like? ...

  4. Al - BASED CAST COMPOSITES

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Yadav

    2011-08-01

    Full Text Available The economy is very important feature nowadays in themarket. The researches are playing an important role inengineering field to increase the life of machine parts /components and decrease the cost. The compositematerials have the potential to replace widely used steeland aluminium due to their good characteristics withbetter performance. The Al-based composites have foundextensive applications in automobile industries andaerospace industries due to their increased stiffness,strength, thermal conductivity and wear resistanceproperties. A number of particulate phases have beenemployed in the Al-alloy matrix. The cast aluminiumceramicparticulate composites are finding applications inpistons, connecting rods, cylinder liner, engine cylinderblock, electrical contacts etc.The present investigation isbased on study of the effect of particulate phase on theSEM study, micro-hardness, elastic modulus, tensilestrength and the wear behaviour of Al-5 % SiC-7 % Fe,Al-10 % SiC-6 % Fe and Al-15 % SiC-5 % Fe composites.

  5. [Environmental factors in ALS].

    Science.gov (United States)

    Juntas-Morales, Raul; Pageot, Nicolas; Corcia, Philippe; Camu, William

    2014-05-01

    ALS is likely to be a disorder of multifactorial origin. Among all the factors that may increase the risk of ALS, environmental ones are being studied for many years, but in the recent years, several advances have pointed to a new interest in their potential involvement in the disease process, especially for the cyanotoxin BMAA. Food containing BMAA has been found on Guam, a well-known focus of ALS/parkinsonism/dementia and high levels of BMAA have been identified into the brain of these patients. The BMAA cyanotoxin is potentially ubiquitous and have also been found into the food of patients who died from ALS both in Europe and USA. BMAA can be wrongly integrated into the protein structure during mRNA traduction, competing with serine. This may induce abnormal protein folding and a subsequent cell death. Heavy metals, such as lead or mercury may be directly toxic for neuronal cells. Several works have suggested an increased risk of ALS in individuals chronically exposed to these metals. Exposure to pesticides has been suggested to be linked to an increased risk of developing ALS. The mechanism of their toxicity is likely to be mediated by paraoxonases. These proteins are in charge of detoxifying the organism from toxins, and particularly organophosphates. To date, there are insufficient scientific data to suggest that exposure to electromagnetic fields may increase the risk of having ALS. We are particularly missing longitudinal cohorts to demonstrate that risk. PMID:24703731

  6. Sociale media als leermiddel

    NARCIS (Netherlands)

    Rubens, Wilfred

    2012-01-01

    Rubens, W. (2012, 5 juni). Sociale media als leermiddel. Presentatie over het gebruik van sociale media binnen het onderwijs, verzorgd tijdens een ouderraadbijeenkomst van de Katholieke Scholengemeenschap Etten-Leur, Etten-Leur, Nederland.

  7. MDA ALS Caregiver's Guide

    Science.gov (United States)

    ... R.D., C.N.S.D., L.D.N. Nutritionist MDA/ALS Center at Vanderbilt University Medical Center ... neurologists, physiatrists, therapists (physical, occupa- tional, speech, respiratory), nutritionists, social work- ers, pulmonologists, gastroenterologists and medical equipment ...

  8. Regionale Herkunft als Bonus

    OpenAIRE

    Kratochvil, Dr. Ruth

    2004-01-01

    Der Bio-Sektor durchlebt bewegte Zeiten. Die biologische Landwirtschaft hat sich aus der Nische herausbewegt und dafür an „Besonderheiten“ eingebüßt. Diese müssen als Zusatznutzen wiedergefunden werden.

  9. Factores asociados al bajo peso al nacer

    OpenAIRE

    Georgina J Peraza Roque; Silvia de la C Pérez Delgado; Zoe de los A Figueroa Barreto

    2001-01-01

    El bajo peso al nacer (BPN) ha constituido un enigma en la ciencia a través de los tiempos. Múltiples son las investigaciones realizadas acerca de las causas que lo producen y las consecuencias que provoca. Su importancia no solo radica en lo que significa en la morbilidad y la mortalidad infantil, sino que estos niños tienen habitualmente múltiples problemas posteriores. El Programa para la Reducción del BPN señala que los niños nacidos con un peso inferior a los 2 500 g presentan riesgo de ...

  10. Partizipation als Ausnahmezustand

    OpenAIRE

    Korf, Benedikt

    2009-01-01

    In «Die Erfindung des Politischen» (1993) beschreibt Ulrich Beck Subpolitik als den Ort, an dem die Grenze zwischen Politik und Nichtpolitik verschwindet. Aus der zunehmenden Wirkkraft von Subpolitik erwächst die grundlegende Frage, mit welcher Legitimation diese Art von Subpolitik in die Sphäre der institutionalisierten Politik eindringt. Beck’s Subpolitik soll im Anschluss an theoretische Arbeiten von Chantal Mouffe und Giorgio Agamben als post-politische Aspiration bezeichnet werden, die e...

  11. Der Preis als Kaufbarriere?

    DEFF Research Database (Denmark)

    Mueller Loose, Simone

    2012-01-01

    Die Preispolitik hat eine herausragende Stellung im Marketing. Der Preis eines Produktes ist für Verbraucher ein direkter Kostenfaktor und für Unternehmen die Stellgröße im Mar-ketingmix, die den Umsatz am stärksten beeinflusst (vgl. Nieschlag et al. 2002). Wenn die Akzeptanz und der regelmäßige...... Verzehr gesunder Lebensmittel erhöht werden soll, ist es sowohl für die Verbraucherpolitik als auch für Lebensmittelproduzenten wichtig, den Ein-fluss des Preises auf die Kaufentscheidung zu verstehen. Aus Verbrauchersicht ist der Preis neben dem Geschmack die wichtigste Produkteigen-schaft beim Kauf von...... Lebensmitteln (vgl. Brunsø/Grunert 1998) und stellt eine Kaufbarrie-re für Lebensmittel mit gesundheitsfördernden Eigenschaften dar. Studien in den USA (vgl. Cassady et al. 2007), Frankreich (vgl. Drewnowski et al. 2004; Andrieu et al. 2005) und Deutschland (vgl. Karg et al. 2008) kommen übereinstimmend zu dem...

  12. Molibdenizado-aluminizado de sustratos de titanio y de TI6AL4V pulvimetalúrgico y laminado mediante pack cementación

    OpenAIRE

    Martín de Hijas Iglesias, Beatriz

    2011-01-01

    En la actualidad tanto el desgaste como la oxidación pueden suponer graves problemas para muchos de los metales y piezas fabricadas con ellos, hasta el punto de acortar la vida útil de multitud de piezas. Tanto es así, que se puede afirmar que el desgaste y la oxidación constituyen dos de las causas más importantes de degradación de piezas metálicas, elementos mecánicos y equipos industriales. Esto supone grandes pérdidas económicas y de producción en infinidad de sistemas productivos así com...

  13. Modification of residual stress in Al-[AlBO]w/Al compound plate

    Institute of Scientific and Technical Information of China (English)

    姜传海; 吴建生; 王德尊

    2001-01-01

    The application of compound parts of Al-[AlBO]w/Al not only reduces the cost of the parts but also improves its properties. However, there is a large thermal residual stress between Al and [AlBO]w/Al, and it is harmful for practical application. From the theoretical analyses and experimental results, it was found that by the compressive pre-plastic deformation perpendicular to the interface between Al and [AlBO]w/Al, the interlayer residual stress of compound parts can be reduced, while the mechanical properties of compound parts can be improved.

  14. La interacción de materiales del sistema sílice-alúmina con productos fluorados aluminosos

    Directory of Open Access Journals (Sweden)

    Verdeja, L. F.

    1998-05-01

    Full Text Available The aim of this paper is to get a first approximation of the systematic study of the corrosion mechanisms of the silica-alumina, alumina and rich-alumina refractory by fluoride compounds and molten aluminum. The thermodynamic results support the main role of the chemical attack and the erosive mechanisms in the wear of the silica-alumina materials. The influence of the composition of the crystalline phases in the degree of the ceramic lining attack is also studied. The results suggest not to use either oxide or nitride high-value materials for the lining of furnaces and transport recipients containing molten aluminum, because of the chemical corrosion by compounds such as cryolite or aluminum fluoride and also, because of the avidity of aluminum towards oxygen. The study of corundum-based materials like the best refractory used in order to react with fluoride compounds and molten aluminum is an alternative to be considered. The study of the crusts adhesion like a protection mechanism of the refractory lining is also a possible approach.

    Este trabajo pretende contribuir al estudio sistemático de los mecanismos de corrosión que experimentan los refractarios sílico-aluminosos, aluminosos y de alta alúmina con productos fluorados y aluminio en estado líquido. Se aportan datos termodinámicos que confirman el papel preponderante del ataque químico y de los mecanismos erosivos en el desgaste de materiales del sistema sílice-alúmina. Se discute, asimismo, la influencia de la composición de las fases cristalinas encontradas en el grado de agresión a los revestimientos cerámicos. Se propone, ante la agresividad de agentes químicamente activos, como la criolita o el fluoruro de aluminio, y la gran afinidad del aluminio por el oxígeno, no aconsejar la utilización de materiales oxídicos y nitrurados de alto valor para el revestimiento de hornos y bolsas de transporte de aluminio. Se propone, como línea de trabajo a seguir, la

  15. Altern als Widerstand

    Directory of Open Access Journals (Sweden)

    Roberta Maierhofer

    2005-07-01

    Full Text Available Gullettes kulturwissenschaftliche Untersuchung Aged by Culture ist wie bereits ihre zwei vorangehenden Werke, die sich mit Altern beschäftigen – Safe at Last in the Middle Years: The Invention of the Midlife Progress Novel (1988 und Declining to Decline. Cultural Combat and the Politics of the Middle (1997 –, von großem persönlichen Engagement und durch ein politisches Anliegen motiviert. Sowohl die Dringlichkeit als auch der Widerstand, den Gullette, die sich als „age critic“ definiert, als moralische und politische Notwendigkeit postuliert, werden in der Zweiteilung der Abhandlung angesprochen: „Cultural Urgencies“ und „Theorizing Age Resistantly“. Während Gullette den Begriff „aged by culture“ bereits in Declining to Decline einführt, stellt sie ihn nun in den Mittelpunkt ihrer Untersuchung. Das Buch ist einerseits einer gesellschaftspolitischen Analyse der USA gewidmet, andererseits wird eine Theorie des Widerstands gegenüber Altersdiskriminierung entwickelt.

  16. Pornographie als Metapher

    Directory of Open Access Journals (Sweden)

    Caroline Schubarth

    2010-03-01

    Full Text Available In diesem Artikel werden unterschiedliche metaphorische Verwendungen des Pornografiebegriffs und deren Implikationen untersucht. Während die Existenz von Pornografie der feministischen Anti-Porno-Bewegung als Erklärung für die anhaltende Diskriminierung von Frauen in westlichen Gesellschaften dient, nutzen rechtskonservative Kräfte den Pornografievorwurf als Rechtfertigung für die Zensur von als deviant empfundenen Identitäten und sexuellen Praktiken.This article examines different metaphorical uses of the term pornography and the resulting implications. While the existence of pornography for the feminist anti-porno movement serves as factor in the continuing discrimination of women in western societies, conservative powers on the right use the allegation of pornography as a justification for censorship of those identities and sexual practices deemed deviant.

  17. Wikipedia als Referenzorgan

    OpenAIRE

    Voß, Jakob

    2006-01-01

    Wikipedia wird inzwischen von vielen Nutzern regelmäßig als Nachschlagewerk genutzt. Aufgrund des offenen Charakters der Online-Enzyklopädie, bei der sich jeder direkt beteiligen kann, ist jedoch zusätzliche Medienkompetenz notwendig, um die Qualität einzelner Wikipedia-Artikel einschätzen zu können. Im Vortrag sollen Methoden zur Beurteilung von Wikipedia-Artikeln dargestellt und die Frage beleuchtet werden, unter welchen Umständen Wikipedia als Referenzorgan geeignet ist.

  18. BERKELEY: ALS ring

    International Nuclear Information System (INIS)

    Everybody at Lawrence Berkeley Laboratory's Center for Beam Physics is pleased with the rapid progress in commissioning LBL's Advanced Light Source (ALS) electron storage ring, the foundation for this third-generation synchrotron radiation facility. Designed for a maximum current of 400 mA, the ALS storage ring reached 407 mA just 24 days after storing the first beam on 16 March. ALS construction as a US Department of Energy (DOE) national user facility to provide high-brightness vacuum ultra-violet and soft x-ray radiation began in October 1987. One technical requirement marking project completion was to accumulate a 50-mA current in the storage ring. The ALS passed this milestone on 24 March, a week ahead of the official deadline. Once injected, the electron beam decays quasi-exponentially primarily because of interactions with residual gas molecules in the storage-ring vacuum chamber. Eventually, when the pressure in the vacuum chamber with beam decreases toward the expected operating level of 1 nano Torr, it will only be necessary to refill the storage ring at intervals of four to eight hours. At present the vacuum is improving rapidly as surfaces are irradiated (scrubbed) by the synchrotron radiation itself. At 100 mA, beam lifetime was about one hour (9 April)

  19. Al Shanker Remembers.

    Science.gov (United States)

    American Educator, 2000

    2000-01-01

    In a 1996 interview shortly before his death, Al Shanker, longtime president of the American Federation of Teachers, discussed such topics as: his own educational experiences; how he learned about political fighting in the Boy Scouts; the appeal of socialism; multinational corporations and the nation state; teaching tough students; and John Dewey…

  20. Application of a TiAIN coating for the increase wear resistance of a passage floodgate manufactured in steel T9; Aplicacion de un recubrimiento de TiAIN para el incremento de la resistencia al desgaste de una compuerta de paso fabricada en acero T9

    Energy Technology Data Exchange (ETDEWEB)

    Montes de Oca, J.; Gonzalez, H. J. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, IPN, Unidad Altamira, Km. 14.5 Carretera Tampico-Puerto industrial Altamira, 89600 Altamira, Tamaulipas (Mexico); Solis, E. [Hy-Teck Fluid Power, Blvd. A. Lopez Mateos No. 310, Col. Nuevo Aeropuerto, 89337 Tampico, Tamaulipas (Mexico); Moreno, J. [Departamento de Ingenieria Metalurgica, Escuela Superior de Ingenieria Quimica e Industrias Extractivas, IPN, UPALM Unidad Zacatenco, 07730 Mexico D. F. (Mexico); Munoz S, J. [Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Fracc. Real de Juriquilla, 76230 Santiago de Queretaro, Queretaro (Mexico)], e-mail: jmontedeocav@ipn.mx

    2009-07-01

    The present work reports a study to increase wear resistance of a ball passage floodgate (steel type T9) trough the application of a thick film (coating). This study have included a material and process selection, synthesis of the coating on steel plates as substrates and spherical device, assembling of the coated floodgate on the ball valves, and finally an evaluation of the valves in the process of a thermoelectric power station. Taking into account the different requirements, a TiAIN coating prepared by cathodic arc evaporation was finally retained. The crystal structure, morphology and chemical composition of the coating were evaluated by x-ray diffraction (XRD) and scanning electron microscopy equipped with an energy dispersive spectrometer (SEM-EDS). Finally, mechanical properties such as hardness and Young modulus were determined by nano indentation. (Author)

  1. Wear resistance of Fe-Nb-Cr-W, Nb, AISI 1020 and AISI 420 coatings produced by thermal spray wire arc; Resistencia al desgaste de recubrimientos Fe-Nb-Cr-W, Nb, AISI 1020 y AISI 420 producidos por proyeccion termica por arco electrico

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Covaleda, E. A.; Mercado-Veladia, J. L.; Olaya-Florez, J. J.

    2013-07-01

    The commercial materials 140MXC (with iron, tungsten, chrome, niobium), 530AS (AISI 1015 steel) and 560AS (AISI 420 steel) on AISI 4340 steel were deposited using thermal spray with arc. The aim of work was to evaluate the best strategy abrasive wear resistance of the system coating-substrate using the following combinations: (1) homogeneous coatings and (2) coatings depositing simultaneously 140MXC + 530AS and 140MXC + 560AS. The coatings microstructure was characterized using Optical microscopy, Scanning electron microscopy and Laser con focal microscopy. The wear resistance was evaluated through dry sand rubber wheel test (DSRW). We found that the wear resistance depends on the quantity of defects and the mechanical properties like hardness. For example, the softer coatings have the biggest wear rates and the failure mode was characterized by plastic deformation caused by particles indentation, and the other hand the failure mode at the harder materials was grooving. The details and wear mechanism of the coatings produced are described in this investigation. (Author)

  2. Metal-ceramic composite coatings obtained by new thermal spray technologies: Cold Gas Spray (CGS) and its wear resistance; Recubrimientos de materiales compuestos metal-ceramico obtenidos por nuevas tecnologias de proyeccion termica: Proyeccion fria (CGS) y su resistencia al desgaste

    Energy Technology Data Exchange (ETDEWEB)

    Miguel, J. M.; Vizcaino, S.; Dosta, S.; Cinca, N.; Lorenzana, C.; Guilemany, J. M.

    2011-07-01

    In this paper, composite coatings composed by an aluminum bronze metal matrix and a hard ceramic alumina phase obtained by cold spray technique were obtained in order to increase the tribological properties of the pure bronze coatings. The different processes that occur during the coating formation (hardening of the metal particles, fragmentation of the ceramic particles, shot peening on the metal substrate, etc) are described and their effects on the coating properties are studied. Wear tests consisting on Ball-on-Disk tests, abrasion Rubber Wheel tests and erosion tests as well as microhardness and adhesion tests are carried out and the results are correlated with the ceramic phase content of the coatings. It can be concluded that the hard ceramic phase increases the tribological properties with relation of the initial bronze coating. Finally, main wear mechanisms during the tribological tests are described. (Author) 21 refs.

  3. Evaluación de la resistencia al desgaste en recubrimientos de Carburos de Niobio NbC, Carburos de Vanadio VC y Carburos ternarios de Niobio y Vanadio NbVC, producidos mediante la técnica de Deposición Difusión Termo-Reactiva (TRD)

    OpenAIRE

    Ramírez Ramos, Marco Antonio

    2013-01-01

    Resumen: Con el objetivo de mejorar las propiedades tribológicas de los aceros AISI H13 y AISI D2, en este trabajo se fabricaron recubrimientos de NbC, de VC y de carburos complejos Nb-V sobre estos dos tipos de acero utilizando el proceso de difusión termo-reactiva (TRD, thermo-reactive diffusion). Los recubrimientos fueron producidos utilizando tres niveles de temperatura (900, 950 y 1000 °C) y tres tiempos de tratamiento (1.5, 2.5 y 3.5 horas). Para determinar las fases presentes en todos ...

  4. Effect of microstructure and microhardness on the wear resistance of zirconia-alumina, zirconia-yttria and zirconia-ceria coatings manufactured by atmospheric plasma spraying; fecto de la microestructura y de la microdureza sobre la resistencia al desgaste de recubrimientos elaborados por proyeccion termica por plasma atmosferico a partir de circona-alumina, circona-itria y circona-ceria

    Energy Technology Data Exchange (ETDEWEB)

    Giovanni Gonzalez, A.; Ageorges, H.; Rojas, O.; Lopez, E.; Milena Hurtado, F.; Vargas, F.

    2015-10-01

    The effect of the structure and microhardness on the wear resistance of zirconia-alumina (ATZ), zirconia-yttria (YSZ) and zirconia-ceria (CSZ) coatings manufactured by atmospheric plasma spraying was studied. The microstructure and the fracture on the cross section of the coatings were analyzed using Scanning Electron Microscopy, the phases were identified using X-Ray Diffraction, the microhardness was measured by Vickers indentation and the wear resistance was evaluated by ball on disc test. The results showed that zirconia-alumina coating exhibits the best performance in the wear test. This behavior is closely related to their microstructure and higher microhardness, despite of its significant quantity of the monoclinic zirconia phase, which has lower mechanical properties than tetragonal zirconia phase. Tetragonal zirconia phase was predominant in the zirconia-yttria and zirconia-ceria coatings and despite this behavior; they did not have a good performance in the wear tests. This low wear resistance was mainly influenced by the columnar structure within their lamellae, which caused a greater detachment of particles in the contact surface during the ball-disc tests, increasing its wear. (Author)

  5. ALS insertion devices

    International Nuclear Information System (INIS)

    The Advanced Light Source (ALS), the first US third generation synchrotron radiation source, is currently under construction at the Lawrence Berkeley Laboratory. The low-emittance, 1.5 GeV electron storage ring and the insertion devices are specifically designed to produce high brightness beams in the UV to soft X-Ray range. The planned initial complement of insertion devices includes four 4.6 m long undulators, with period lengths of 3.9 cm, 5.0 cm (2) and 8.0 cm, and a 2.9 m long wiggler of 16 cm period length. Undulator design is well advanced and fabrication has begun on the 5.0 cm and 8.0 cm period length undulators. This paper discusses ALS insertion device requirements; general design philosophy; and design of the magnetic structure, support structure/drive systems, control system and vacuum system. 18 refs., 9 figs., 5 tabs

  6. De GPS al mapa

    Directory of Open Access Journals (Sweden)

    Esteban Dörries

    2016-03-01

    Full Text Available Las coordenadas Lambert obtenidas a partir de mediciones con equipos GPS de mano, llamados a veces navegadores, en ciertos casos confunden al usuario, por diferir claramente de su posición real al ser graficadas en un mapa del Instituto Geográfico Nacional (IGN: Esto puede resolverse con suficiente exactitud mediante una transformación de Molodensky, seguida de la correspondiente proyección cartográfica. Sin embargo, los tres parámetros necesarios para la transformación, supuestamente válidos para Costa Rica, se encuentran en muchas variantes y producen obviamente resultados diferentes. En este trabajo se analizan los fundamentos del problema y sus posibles soluciones, culminando con un estudio comparativo de ocho casos, que permite seleccionar los valores más adecuados para los parámetros.

  7. Acarbose als Carbophor

    OpenAIRE

    Merettig, Nadine

    2014-01-01

    Das Pseudotetrasaccharid Acarbose ist seit 1990 als kompetitiver Inhibitor intestinaler α-Glucosidasen (GlucobayTM/PrecoseTM) in der medizinischen Anwendung bei der Therapie von Diabetes mellitus Typ-2. Charakteristisch für die Struktur der Acarbose ist die Acarviosyleinheit, bei der Valinamin und Desoxyglucose N-glycosidisch verknüpft sind; des Weiteren ist an die Acarviosyleinheit ein Maltosylrest gebunden. Der Inhibitoreffekt beruht auf der irreversiblen Bindung zwischen ...

  8. Augmented Reality als Bildungsenhancement?

    OpenAIRE

    Damberger, Thomas

    2015-01-01

    Die Realität, die sich mithilfe von Datenbrillen und Smartphone Applikationen in die virtuelle Welt hinein ausdehnt, erfährt eine Form des Enhancements. Ein solches Enhancement kann unter bestimmten Voraussetzungen als Bildungsenhancement verstanden werden. Der Text befasst sich mit Formen der erweiterten Realität, ferner mit dem, um was es wesentlich bei der Bildung geht und zuletzt mit den Bedingungen, die erforderlich sind, um diesem Wesentlichen mit Hilfe von augmented reality besser zum ...

  9. Carta al editor

    OpenAIRE

    Harry Pachajoa

    2012-01-01

    Recently, Valencia et al., published a very interesting article called «Lipid profile in a group of patients with Turner’s syndrome at Clínica Universitaria Bolivariana in the city of Medellín between 2000 and 2009". An article which evaluated lipid levels in patients withTurner syndrome in a Colombian clinic, the study associated results of lipid profile with karyotype and other risk factors for coronary heart disease.

  10. AL-USRCRN Station Information

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Documentation of United States Alabama Regional Climate Reference Network (AL-USRCRN) installations in 2006. Installations documented are for AL-USRCRN pilot...

  11. Derivados vinculados al seguro.

    Directory of Open Access Journals (Sweden)

    De Paz Cobo, Sonia

    2003-01-01

    Full Text Available El presente trabajo tiene como objetivo la presentación de los derivados financieros como instrumentos de cobertura de los riesgos del seguro, así como de los principales proyectos que se desarrollan a través de los mismos, como por ejemplo los derivados sobre el clima. Hay que tener presente las pérdidas multimillonarias ocasionadas en casos como el de la banca Baring’s, o el de Orange County, por citar algunas, que si bien ciertos autores afirman que están en relación directa con el uso de estos productos, no podemos olvidar que los instrumentos derivados se desarrollaron con el objetivo principal de proteger al usuario de la posible volatilidad del activo subyacente. Ya en la industria aseguradora los derivados vinculados a tal actividad son instrumentos donde el pago se condiciona a la ocurrencia de su suceso de siniestro, o serie de sucesos múltiples que disparen las pérdidas. Tras el repaso efectuado y la descripción que este tipo de instrumentos puede tener en la gestión del riesgo por parte de la industria aseguradora, concluiremos con la exposición de las relaciones con el reaseguro tradicional así como una breve referencia al futuro de este tipo de instrumentos

  12. Gliricidia sepium al establecimiento

    Directory of Open Access Journals (Sweden)

    J. L. Valle

    2004-01-01

    Full Text Available Se asoció Cenchrus ciliaris (Cc y Gliricidia sepium (Gs para evaluar la producción de biomasa y la composición química de los forrajes en la fase de establecimiento, en el estado de Morelos, México, en condiciones de trópico seco. Se empleó un análisis de varianza con diseño en bloques al azar, en donde T1 fue pasto solo, T2 Cc más Gs con 5,000 plantas ha-1 y el T3 Cs más Gs con 14,285 plantas ha-1. Se midió la producción de forraje individual y asociado con materia seca (t MS/Ha, la altura (A en cm, la proteína cruda (PC%, las fracciones de fibra (FDN% y FDA% y la digestibilidad in vitro de la materia seca (DIVMS%. El T3 tuvo una mejor producción de biomasa (P0.05. La asociación de 14,285 plantas ha-1 de G. sepium con pasto Cenchrus ciliaris mejoró la producción de biomasa y la disponibilidad total de nutrientes por superficie cultivada al establecimiento

  13. Toxic waste treatment with sliding centrifugal plasma reactor; Tratamiento de residuos toxicos con reactores de plasma centrifugo deslizante (PCD)

    Energy Technology Data Exchange (ETDEWEB)

    Pacheco, J.; Pacheco, M.; Valdivia, R.; Ramos, F.; Duran, M.; Hidalgo, M.; Cruz, A.; Martinez, J. C.; Martinez, R.; De la Cruz, S.; Flores, T.; Vidal, E.; Escobar, S. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico); Garduno, M.; Garcia, M.; Portillo, J.; Torres, C.; Estrada, N.; Velazquez, S.; Vasquez, C. [Instituto Tecnologico de Toluca, Av. Instituto Tecnologico s/n, Ex-Rancho la Virgen, Metepec 52140, Estado de Mexico (Mexico)

    2008-07-01

    The aim is to develop technology for hazardous waste treatment, including the building and putting into operation of a prototype based on a sliding centrifugal plasma technology to demonstrate its ability to degradation taking in account the existing environmental standards. (Author)

  14. Epitaxial growth of Al/Al2O3 multilayer structures

    International Nuclear Information System (INIS)

    In order to obtain Al-Al2O3 quantum effect devices, it is necessary to deposit epitaxially Al on Al2O3 and Al2O3 on Al. We have already obtained an epitaxial Al/Al2O3/Al structures on Si(111). In this paper, we have deposit Al/Al2O3/Al structures on Si(111), and investigated the crystallinity by using RBS. (author)

  15. Doppelthydrophile Blockcopolymere als Mineralisationstemplate

    Science.gov (United States)

    Kasparova, Pavla

    2002-07-01

    Die vorliegende Arbeit beschäftigt sich mit der Synthese und den Eigenschaften von doppelthydrophilen Blockcopolymeren und ihrer Anwendung in einem biomimetischen Mineralisationsprozeß von Calciumcarbonat und Bariumsulfat. Doppelthydrophile Blockcopolymere bestehen aus einem hydrophilen Block, der nicht mit Mineralien wechselwirkt und einem zweiten Polyelektrolyt-Block, der stark mit Mineraloberflächen wechselwirkt. Diese Blockcopolymere wurden durch ringöffnende Polymerisation von N-carboxyanhydriden (NCA's) und a-methoxy-ω-amino[poly(ethylene glycol)] PEG-NH2 als Initiator hergestellt. Die hergestellten Blockcopolymere wurden als effektive Wachstumsmodifikatoren für die Kristallisation von Calciumcarbonat und Bariumsulfat Mineralien eingesetzt. Die so erhaltenen Mineralpartikel (Kugeln, Hantel, eiförmige Partikel) wurden durch Lichtmikroskopie in Lösung, SEM und TEM charakterisiert. Röntgenweitwinkelstreuung (WAXS) wurde verwendet, um die Modifikation von Calciumcarbonat zu ermitteln und die Größe der Calciumcarbonat- und Bariumsulfat-Nanopartikel zu ermitteln. This work describes the synthesis and characterization of double hydrophilic block copolymers and their use in a biomimetic mineralization process of Calcium Carbonate and Barium Sulfate. Double hydrophilic block copolymers consist of a hydrophilic block that does not interact with minerals and another hydrophilic polyelectrolyte block that strongly interacts with mineral surfaces. These polymers were synthesised via ring opening polymerisation of N-carboxyanhydride (NCA), and the first hydrophilic block a-methoxy-ω-amino[poly(ethylene glycol)] PEG-NH2 was used as an initiator. The prepared block copolymers were used as effective crystal growth modifiers to control the crystallization of Calcium Carbonate and Barium Sulfate minerals. The resulting mineral particles (spheres, dumbbells, egg-like particles) were characterised by light microscopy in solution, by SEM, and by TEM. X-Ray scattering

  16. Fretting wear performances of multilayered PVD TiAlZrN/TiAlN/TiAl on AISI 4140 steel

    OpenAIRE

    Tlili, Brahim; NASRI, Mustapha; F. Ayari; Nouveau, Corinne

    2008-01-01

    Nowadays, most surface treatments are realized through vapor deposition techniques as thin hard coatings to guarantee; high surface hardness, low friction coefficient and improve wear resistance. Several experimental investigations have let to the development of a (TiAlCN/TiAlN/TiAl) and (TiAlZrN/TiAlN/TiAl) coatings in preference to the traditional TiN coating. In the current paper research conducted on fretting wear of a (TiAlCN/TiAlN/TiAl) and a (TiAlZrN/TiAlN/TiAl) multilayer coatings de...

  17. Malamih al-Ashwat al-'Arabiyyah wa Makharijaha

    Directory of Open Access Journals (Sweden)

    Amrah Muhammad Kasim

    2015-12-01

    Full Text Available This writing discusses on al-ashwat al-‘arabiyyah that is known with “phonetic” term. It talks and interprets makharij al-huruf or place for producing sounds and also processing production of sounds by parts of mouth in Arabic language. The problems of sounds and its systems in Arabic language have been conducted by the scholars of al-ashwat al-‘arabiyyah attractively, neatly, and detail and gotten ahead the phonetic western scholars. Part of their analysis results formulate the study about al-ashwat al-sakinah (al-Shamit is known with vocal and consonant sounds in research questions shawait – shawamit. Ibnu Jinni has formulated “harakat”(wowel in Arabic language and dimension of letter  mad and liyn on alif  letter - waw - ya’ (ا و ي, from these letters create  harakat fathah, dammah, and kasrah. Moreover, in this writing also exist the description of hija’i letters and its makhraj that are correct from parts of mouth and the unity of coordinative sounds that produce sounds in morphemes arrangement, in one word that produces meaning. The result of phonological study has divided al-ashwat to be kinds of sound like the pronounced sounds, produced sounds from mouth, and heard sound.

  18. Editorial: Cartas al Editor

    Directory of Open Access Journals (Sweden)

    Guillermo Llanos

    2006-06-01

    Full Text Available En todas las revistas biomédicas del mundo existe una sección habitual denominada como el título de este editorial y que en Colombia Médica la llamamos correspondencia. Este espacio tiene como objetivo fundamental que los lectores escriban a los autores (investigadores comentando los artículos que se han publicado en números anteriores de la revista. Las cartas son, entonces, breves comentarios de desacuerdo o acuerdo (conceptual, metodológico, interpretativo sobre falencias ubicadas por un lector alerta al tema debatido en cualquiera de las secciones como en los artículos originales, editoriales, revisiones, presentación de casos, etc. publicados previamente en la revista. Las cartas deben permitir el intercambio de opiniones y formas de pensar y analizar los problemas planteados entre los autores y los lectores. En ocasiones una serie de cartas motivadas por un artículo original puede ser tan o más interesante como el artículo que generó la correspondencia. Las cartas son también un formato adecuado para comunicar un hecho novedoso de una observación clínica juiciosa no descrita antes. Un ejemplo de ello es la carta de un gineco-obstetra australiano cuando informó a Lancet los primeros efectos adversos informados de la talidomida. Colombia Médica, a pesar de mantener vigente esta sección, no ha sido muy afortunada en establecer una buena cultura del envío de cartas al editor. Pero últimamente han llegado juiciosas observaciones a las cuales se les ha dado prioridad en su publicación. Toda carta que comenta los hallazgos de un artículo es enviada a los autores para su respuesta, porque ello genera el debate académico buscado, y luego se publican, tanto la carta como su respuesta. El Estilo Vancouver recomienda que la carta y su respuesta deban ser breve, no pasar de dos o tres párrafos y contener sólo cuatro o cinco referencias. En lo posible (a menos que sea indispensable no presentar ni cuadros ni gráficos. El t

  19. Alexandria (Al Iskandariya), Egypt

    Science.gov (United States)

    2002-01-01

    This image of Alexandria was taken by astronauts on board the International Space Station in December 2000 using an Electronic Still Camera. A wider-angle view (STS088-739-90) taken from the Space Shuttle in December 1998 is available for context. Alexandria (Al Iskandariya) occupies a T-shaped peninsula and strip of land separating the Mediterranean from Lake Mariout. Originally the town was built upon a mole (stone breakwater) called Heptastadium, which joined the island of Pharos (see referenced website, below) to the mainland. Since then sedimentary deposits have widened the mole. Since 1905, when the 370,000 Alexandrians lived in an area of about 4 sq km between the two harbors, the city (population 4 million; see referenced website, below) has grown beyond its medieval walls and now occupies an area of about 300 sq km. The Mahmudiya Canal, connecting Alexandria with the Nile, runs to the south of the city and, by a series of locks, enters the harbor of the principal port of Egypt (note ships). The reddish and ochre polygons west of Lake Mariout are salt-evaporation, chemical-storage, and water-treatment ponds within the coastal lagoon. Reference Youssef Halim and Fatma Abou Shouk, 2000, Human impacts on Alexandria's marine environment: UNESCO, Coastal Regions and Small Islands Unit (CSI), Coastal Management Sourcebooks 2 (accessed December 20, 2000) Additional photographs taken by astronauts can be viewed at NASA-JSC's Gateway to Astronaut Photography of Earth. Image ISS001-ESC-5025 provided by the Earth Sciences and Image Analysis Laboratory, Johnson Space Center.

  20. Undulators at the ALS

    International Nuclear Information System (INIS)

    At Lawrence Berkeley Laboratory's (LBL) Advanced Light Source (ALS), three 4.6 m long undulators have been completed, tested and installed. A fourth is under construction. The completed undulators include two 5.0 cm period length, 89 period devices (U5.0s) which achieve a 0.85 T effective field at a 14 mm minimum gap and a 8.0 cm period length, 55 period device (U8.0) that reaches a 1.2 T effective field at a 14 mm minimum gap. The undulator under construction is a 10.0 cm period length, 43 period device (U10.0) that is designed to achieve 0.98 T at a 23 mm gap. Undulator magnetic gap variation (rms) is within 25 microns over the periodic structure length. Reproducibility of the adjustable magnetic gap has been measured to be within +/- 5 microns. Gap adjusting range is from 14 mm to 210 mm, which can be scanned in one minute. The 5.1 m long vacuum chambers are flat in the vertical direction to within 0.74 mm and straight in the horizontal direction to within 0.08 mm over the 4.6 m magnetic structure sections. Vacuum chamber base pressures after UHV beam conditioning are. in the mid 10-11 Torr range and storage ring operating pressures with full current are in the low 10-10 Torr range. Measurements show that the uncorrelated magnetic field errors are 0.23%, and 0.20% for the two U5.Os and the U8.0 respectively and that the field integrals are small over the 1 cm by 6 cm beam aperture. Device description, fabrication, and measurements are presented

  1. Epistemologi Sufi : Perspektif Al-Hakim Al-Tirmidzi

    Directory of Open Access Journals (Sweden)

    Ainul Abidin Shah

    2012-06-01

    Full Text Available Abstract : This article deals with some epistemological terms and theoretical postulates in the thought of a well known sufi  from the 9th century AD., Abu `Abdu’lLah Muhammad b. `Ali al-Hakim al-Tirmidzi, in order to describe the path (sulūk of a sufi towards the Ultimate Reality. In his own style thought about the sufis, placing an emphasis upon the strong relations between the walāyah (sufi  sainthood and the ma`rifa (sufi knowledge in the one side, and between the two a philosophy of Sufi Ethics. So, it is nothing out of the ordinary to fi nd his ethical inclinations as a dominant feature in every aspect of his epistemological thoughts. In addition, sufi epistemology in the perspective of philosophers focuses on enforcing the inner positive potents of the Self more so than to eliminate “the satanic influences” to the heart, because – in al-Tirmidzi’s argument is that the former would greatly improve the immunity of the self, and encourage it to tread consistently on the right path as well.Keywords :  Dhawq, eros, heart, exoteric, esoteric, al-Haqq, al-`Adl, al-Shidq Abstrak : Artikel ini membahas istilah-istilah epistemologi dan beberapa postulat dari seorang sufi terkenal abad ke-9, Abu `Abdu’lLahMuh ammad b.`Ali al-Hakim al-Tirmidzi, dalam upaya menggambarkan perjalanan suluk seorang sufi menuju Realitas Mutlak. Dalam gaya pemikirannya tentang sufi, kita menemukan bahwa figur ini cenderung  menekankan hubungan-hubungan yang kuat antara wal āyah (kewalian sufi dan ma‘rifa (pengetahuan sufi di satu sisi, dan antara keduanya dengan filsafat moral sufi.  Jadi, tidak aneh jika kita menemukan kecenderungan - kecenderungan etis yang dominan dalam setiap aspek  pemikiran epistemologinya. Dan epistemologi sufi dalam perspektif para filsuf lebih menekankan potensi inner Diri yang positif daripada menghapuskan “cara-cara syaitan” dalam hati, karena - menurut pendapat al-Tirmidzi – ia akan meningkatkan

  2. Estudio de la resistencia al rayado de nuevos nanocomposites de nanotubos de carbono en polimetilmetacrilato

    OpenAIRE

    López Cegarra, Manuel

    2012-01-01

    Las conclusiones a las que se ha llegado con este PFC son las siguientes:1. Se ha obtenido y caracterizado un nuevo nanocomposite de matriz PMMA por dispersión de un 1% en peso de nanotubos de carbono de pared simple. 2. Se ha estudiado el comportamiento tribológico del nuevo material frente a desgaste abrasivo evaluando la resistencia a la abrasión por múltiples rayados y comparándolo con los valores obtenidos para el polimetilmetacrilato puro. En todos los casos se han det...

  3. Rehabilitar en psiquiatría ¿quema al personal de enfermería?

    OpenAIRE

    Leal Docampo, Purificación; De Pablo Jarque, Isabel

    2014-01-01

    El objetivo de este estudio fue analizar el desgaste profesional en el personal de enfermería dedicado a la rehabilitación psiquiátrica hospitalaria. Para ello se tuvieron en cuenta tanto las tres dimensiones específicas de este síndrome, es decir, agotamiento emocional, despersonalización y falta de realización profesional, además de otras variables organizacionales como posibles fuentes de estrés y las consecuencias para la salud física, psicológica, sociofamiliar y laboral;...

  4. El miedo al rey

    Directory of Open Access Journals (Sweden)

    François FORONDA

    2007-01-01

    Full Text Available La peur du roi. Sources et premières réflexions à propos d’une émotion aristocratique dans la Castille du XIVe siècleFace à un roi qui à présent pousse les effets de son ire jusqu’au meurtre pour faire le vide autour de lui et imposer sa différence souveraine, ses parents et les riches hommes, soit les principaux visés par cette politique de l’arbitraire qui enfreint les règles du jeu autant qu’elle contribue à les redéfinir, disent la peur (metus qu’ils ressentent, qu’ils utilisent aussi afin de donner à leur stratégie de pouvoir un fondement légitime. Et l’expression de cette émotion politique, qui tend à se muer en un stéréotype d’un discours aristocratique d’opposition, surtout présente dans les chroniques, mises ici en relation ici avec d’autres sources, notamment des correspondances, marque profondément l’histoire des relations souvent conflictuelles au sein de cette compagnie en définitive très étroite pendant un siècle, de la fin du XIIIe siècle à la fin du XIVe siècle. Cet article se propose d’ébaucher une première réflexion sur le sujet et d’en présenter les principales sources.El miedo al rey. Fuentes y primeras reflexiones acerca de una emoción aristocrática en la Castilla del siglo XIVFrente a un rey que ahora lleva hasta la muerte los efectos de su ira para hacer el vacío entorno a su persona e imponer su soberana, sus parientes y ricos hombres, o sea los principales afectados por esta política de la arbitrariedad que rompe las reglas del juego a la vez que contribuye a redefinirlas, dicen el miedo (metus que sienten, que utilizan también para darle a su estrategia de poder un fundamento legítimo. Y la expresión de esta emoción política, que tiende a convertirse en un estereotipo de un discurso aristocrático de oposición, sobre todo presente en la crónicas, aquí puestas en relación con otras fuentes, en particular cartas, marca profundamente la historia de

  5. El pensamiento frente al arte

    OpenAIRE

    Bergmann, Antonio

    2012-01-01

    Es un hecho histórico de gran importancia el que el hombre haya creado arte antes de haberse dedicado a la filosofía. Al mencionar esto no pienso en las pinturas pre-históricas que se encuentran en las cuevas de España y en el Sur de Francia, sino ante todo, en el arte egipcio y mesopotámico.  En Egipto y Mesopotamia --y Mesopotamia parece ser la región más importante -no nació sino que se creó al hombre humano, al hombre como ser arquitectónico.

  6. Consoer et al PFOS dataset

    Data.gov (United States)

    U.S. Environmental Protection Agency — This ScienceHub entry was developed for the published paper: Consoer et al., 2016, Toxicokinetics of perfluorooctane sulfonate in rainow trout (Oncorhynchus...

  7. DESAFÍOS AL ORDEN

    Directory of Open Access Journals (Sweden)

    Evangelina De los Rios

    2012-03-01

    Full Text Available Fradkin, Raúl y Gelman, Jorge (Compiladores, Desafíos al Orden. Política y sociedades rurales durante la Revolución de Independencia, Prohistoria ediciones, Rosario, 2008, 157 pp.

  8. Seltzer_et_al_2016

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset supports the modeling study of Seltzer et al. (2016) published in Atmospheric Environment. In this study, techniques typically used for future air...

  9. Note intorno al Teatro Vagante

    OpenAIRE

    Scabia, Giuliano

    2013-01-01

    In questo testo-intervista Scabia traccia, alternando racconto e riflessione, un percorso che abbracciatutta l'attività del suo Teatro Vagante: dalle azioni nelle scuole degli inizi degli anni '70 - agli alboridell'Animazione Teatrale, che anche da qui prese le mosse - al lavoro all'Università di Bologna,organica continuazione di quei primi esperimenti. Dalla poesia alle azioni teatrali in strada;dall'architettura della pagina al respiro della parola detta in presenza ; dalle aule ...

  10. Information als Gegenstand von Informationskompetenz

    OpenAIRE

    Ingold, Marianne

    2011-01-01

    Der Informationsbegriff als zentraler Gegenstand von Informationskompetenz wird in der bibliothekarischen Diskussion in der Regel nicht explizit thematisiert, sondern lässt sich aus Fachliteratur und Bibliothekspraxis nur implizit erschließen. Eine theoretische Beschäftigung mit dem Informationsbegriff ist jedoch unabdingbar, soll das Konzept "Informationskompetenz" auch außerhalb des bibliothekarischen Kontextes verständlich und nutzbar gemacht werden. Im vorliegenden Text, der sich als Beit...

  11. Response to Brosch et al.

    OpenAIRE

    Pihlajamäki, Jussi; Lerin, Carles; Kaminska, Dorota; Venesmaa, Sari; Itkonen, Paula; Boes, Tanner; Floss, Thomas; Schroeder, Joshua; Dearie, Farrell; Crunkhorn, Sarah; Burak, Furkan; Jimenez-Chillaron, Josep C.; Kuulasmaa, Tiina; Miettinen, Pekka; Park, Peter J.

    2012-01-01

    We would like to respond to Brosch et al. regarding our manuscript “Expression of the Splicing Factor Gene SFRS10 Is Reduced in Human Obesity and Contributes to Enhanced Lipogenesis” (Pihlajamäki et al., 2011b). Brosch performed RT-PCR in liver samples from 13 lean and 34 obese individuals, finding no differences in SFRS10 or LPIN1 expression. We wish to address points raised by Brosch, including experimental strategy and analysis of human SFRS10 expression.

  12. D’al-Ẓāhir Baybars à ʿAlī al-Zaybaq

    OpenAIRE

    Dorlian, Georges

    2014-01-01

    « Toi par le courage, moi par la filouterie » aimait répéter Baṭṭāl à la princesse Ḏāt al-Himma, comme pour délimiter les espaces d’action revenant à chacun. Et d’ajouter, pour mieux dépeindre son rôle : « Mon métier n’est pas celui de la guerre, des armes et des exploits, mais celui de la ruse et de la fourberie dans un château fort ou une forteresse. » Baṭṭāl était un ʿayyār adjoint à la princesse Ḏāt al-Himma et à ʿAbd al-Wahhāb pour servir leur cause sublime et leur idéal chevaleresque. E...

  13. Strain sensing with sub-micron sized Al-AlOx-Al tunnel junctions

    OpenAIRE

    Koppinen, P. J.; Lievonen, J. T.; Ahlskog, M.; Maasilta, I. J.

    2009-01-01

    We demonstrate a local strain sensing method for nanostructures based on metallic Al tunnel junctions with AlOx barriers. The junctions were fabricated on top of a thin silicon nitride membrane, which was actuated with an AFM tip attached to a stiff cantilever. A large relative change in the tunneling resistance in response to the applied strain (gauge factor) was observed, up to a value 37. This facilitates local static strain variation measurements down to ~10^{-7}.

  14. Epistemologi Sufi : Perspektif Al-Hakim Al-Tirmidzi

    OpenAIRE

    Ainul Abidin Shah

    2012-01-01

    Abstract : This article deals with some epistemological terms and theoretical postulates in the thought of a well known sufi  from the 9th century AD., Abu `Abdu’lLah Muhammad b. `Ali al-Hakim al-Tirmidzi, in order to describe the path (sulūk) of a sufi towards the Ultimate Reality. In his own style thought about the sufis, placing an emphasis upon the strong relations between the walāyah (sufi  sainthood) and the ma`rifa (sufi knowledge) in the one side, and between the two a philosophy of Sufi Et...

  15. Al clamor de les vuvuzeles

    Directory of Open Access Journals (Sweden)

    Javier Olivera Betrán

    2010-09-01

    Full Text Available El Mundial de Futbol de Sud-àfrica ha situat l’Àfrica al mapa mundial i ha mostrat al món el triomf de l’estil de futbol d’Espanya basat en la col·lectivitat, l’esperit d’equip, la humilitat, la cohesió interna i el joc bonic. L’organització africana, seriosa i eficaç, ha sabut mobilitzar i il·lusionar la població del país que ha participat en el mundial des de l’orgull de ser africà, amb l’esperit alegre, festiu i també reivindicatiu de la gent de l’Àfrica. Aquest esdeveniment suposa el llançament de la marca “Sud-àfrica” al món amb un avís clar d’optar a l’organització d’uns primers Jocs Olímpics a Àfrica (potser els de 2020. S’obre una finestra d’esperança al segle xxi per al continent perdut de la mà de l’esport espectacle tan universal, massiu, emocional i mercantil que també es juga a la canxa de la política i de l’economia.

  16. A united refinement technology for commercial pure Al by Al-10Ti and Al-Ti-C master alloys

    International Nuclear Information System (INIS)

    Because flake-like TiAl3 particles in Al-Ti-C master alloys prepared in a melt reaction method dissolve slowly when they are added into Al melt at 720 deg. C, Ti atoms cannot be released rapidly to play the assistant role of grain refinement, leading to a poor refinement efficiency of Al-Ti-C master alloys. A united refinement technology by Al-10Ti and Al-Ti-C master alloys was put forward in this paper. The rational combination of fine blocky TiAl3 particles in Al-10Ti and TiC particles in Al-Ti-C can improve the nucleation rate of α-Al. It not only improves the grain refinement efficiency of Al-Ti-C master alloys, but also reduces the consumption

  17. Modeling of the ALS linac

    International Nuclear Information System (INIS)

    The ALS injector linac is used for the Beam Test Facility (BTF) and the Damping Experiments when it is available in between the ALS filings. These experiments usually require higher quality beams and a better characterization than is normally required for ALS operations. This paper focuses on the beam emittance, energy tilt, and especially the longitudinal variation of the beam parameters. For instance, the authors want to avoid longitudinal variations at the low beta section of the BTF. On the other hand, a large energy tilt is required for post-acceleration compression of the bunch using an alpha magnet. The PARMELA code was modified to calculate and display longitudinal variations of the emittance ellipse. Using the Microsoft Development Studio under Windows NT environment the code can handle a much larger number of particles than was previously possible

  18. Conjuntivitis alérgica

    Directory of Open Access Journals (Sweden)

    Alejandro Tello Hernández

    2008-07-01

    Full Text Available La conjuntivitis alérgica es una de las causas más comunesde consulta externa en oftalmología y tiene una muy altarelación con las reacciones alérgicas sistémicas. Lafisiopatología de las reacciones de hipersensibilidad noshace entender los cuadros clínicos característicos de estapatología y sus diferentes grados de severidad. Eldiagnostico diferencial es amplio, sin embargo hay clavesdiagnosticas que nos orientan rápidamente al diagnosticocorrecto. El tratamiento se enfoca en las medidasfarmacológicas y no farmacológicas, utilizándolas enconjunto para disminuir la recurrencia del cuadro y prevenirsecuelas visuales.

  19. ALS:A SAIRASTAVAN TOIMINTATERAPIA

    OpenAIRE

    Vuorinen, Johanna

    2013-01-01

    Amyotrofinen lateraali skleroosi on harvinainen, etenevä sairaus. Sairaus surkastuttaa edetessään potilaan tahdonalaisen lihaksiston. Sairauden oireet näkyvät yleensä ensin raajoissa, mutta myös nielun lihaksista alkava bulbaarinen taudinmuoto on mahdollinen. ALS voi myös aiheuttaa frontotemporaalista dementiaa. Sairaus etenee yksilöllisesti, mutta sen kesto on yleensä noin 3-5 vuotta. Keski-Suomen keskussairaalassa ALS:n sairastuneen kuntoutukseen osallistuu moniammatillinen työryhmä, j...

  20. Generation and evolution of nanoscale AlP and Al13Fe4 particles in Al-Fe-P system

    International Nuclear Information System (INIS)

    Highlights: • Diffusion and gradual solid reactions between Al and FexP phases in Al-Fe-P alloy were investigated. • Nanoscale AlP clusters are in-situ generated and evolve during the whole process. • This novel Al-Fe-P alloy has an excellent low-temperature refining performance on hypereutectic Al-Si alloy. - Abstract: In this paper, the gradual solid reactions between Al and FexP phases in Al-Fe-P alloy were investigated. The results show that the whole reaction process undergoes four main stages: the diffusion of Al atom, the generation of (Al, Fe, P) intermediate compound, the precipitation of nano AlP and Al13Fe4 clusters and their growth to submicron particles. The microstructure of Fe-P particles evolves from the “egg-type”, the “sponge-type” to the “sesame-cake” structure. AlP and Al13Fe4 nano phases have in-situ generated and evolved during the whole process. The gradual reaction mechanism has been discussed. Furthermore, a novel Al-Fe-P alloy which contains (Al, Fe, P) intermediate compounds and nano AlP particles has been synthesized and its low-temperature refining performance on A390 alloy has also been investigated

  1. Dynamic Modeling of ALS Systems

    Science.gov (United States)

    Jones, Harry

    2002-01-01

    The purpose of dynamic modeling and simulation of Advanced Life Support (ALS) systems is to help design them. Static steady state systems analysis provides basic information and is necessary to guide dynamic modeling, but static analysis is not sufficient to design and compare systems. ALS systems must respond to external input variations and internal off-nominal behavior. Buffer sizing, resupply scheduling, failure response, and control system design are aspects of dynamic system design. We develop two dynamic mass flow models and use them in simulations to evaluate systems issues, optimize designs, and make system design trades. One model is of nitrogen leakage in the space station, the other is of a waste processor failure in a regenerative life support system. Most systems analyses are concerned with optimizing the cost/benefit of a system at its nominal steady-state operating point. ALS analysis must go beyond the static steady state to include dynamic system design. All life support systems exhibit behavior that varies over time. ALS systems must respond to equipment operating cycles, repair schedules, and occasional off-nominal behavior or malfunctions. Biological components, such as bioreactors, composters, and food plant growth chambers, usually have operating cycles or other complex time behavior. Buffer sizes, material stocks, and resupply rates determine dynamic system behavior and directly affect system mass and cost. Dynamic simulation is needed to avoid the extremes of costly over-design of buffers and material reserves or system failure due to insufficient buffers and lack of stored material.

  2. Cathodic electrochemiluminescence at double barrier Al/Al2O3/Al/Al2O3 tunnel emission electrodes

    International Nuclear Information System (INIS)

    Double insulating barrier tunnel emission electrodes were fabricated by adding a new pure aluminum layer upon oxidized aluminum electrodes by vacuum evaporation and thermally oxidizing the new aluminum layer in air at room temperature. Resulting Al/Al2O3/Al/Al2O3 electrodes allow the use of various aluminum alloys in the electrode body necessary for hardness or shaping ability of the electrode while obtaining the luminescence properties of pure aluminum oxide. During electrical excitation of luminescent labels by cathodic hot electron injection into aqueous electrolyte solution, the background noise is mainly based on high-field-induced solid-state electroluminescence and F-center luminescence of the outer aluminum oxide film. The more defect states and/or impurity centers the outer oxide film contains, the higher is the background emission intensity. The present electrode fabrication method provides a considerable improvement in signal-to-noise ratio for time-resolved electrochemiluminescence (TR-ECL) measurements when the original native oxide film of the electrode body contains luminescence centers displaying long-lived luminescence. The excellent performance of the present electrodes is demonstrated by extremely low-level detection of Tb(III) chelates, luminol, Pt(II) coproporphyrin and Tb(III) labels in an immunometric immunoassay by time-resolved electrochemiluminescence

  3. Derecho humano al agua y al saneamiento: derechos estrechamente vinculados al derecho a la vida

    OpenAIRE

    Fernández Aller, Maria Celia; Luis Romero, Elena de; Guzmán Acha, Cristina

    2013-01-01

    Los derechos humanos al agua y al saneamiento están íntimamente relacionados con otros derechos esenciales para la vida, como la alimentación o la salud. Su reconocimiento como derechos humanos en 2010 marca un hito importante en el respeto, protección y realización de estos derechos, que se encuentran seriamente vulnerados para una mayoría de población más vulnerable y empobrecida, sobre todo en el ámbito rural. Mucho camino queda aún para conseguir no sólo la disponibilidad de agua y saneam...

  4. Personalidad y tolerancia al dolor

    Directory of Open Access Journals (Sweden)

    JESÚS M.ª CARRILLO

    2005-01-01

    Full Text Available Se examina la relación de algunas variables de personalidad -EPQ-A (Eysenck y Eysenck, 1975, NEO-PI (McCrae y Costa, 1988 y STA -personalidad esquizotípica- y STB -personalidad límite-, de Claridge y Broks (1984, con la tolerancia al dolor experimental inducido mediante agua fría (cold pressor test, según el procedimiento de Staats, Heckmat y Staats (1998 en una muestra filtrada mediante un cuestionario sobre dolor crónico, dolores de cabeza, de espalda, artritis, síndrome de Raynaud, y personas bajo medicación. La tolerancia al dolor experimental se evaluó mediante el Umbral del dolor (tiempo en segundos desde la introducción de la mano en el agua hasta el primer informe de dolor, Mantenimiento del dolor (duración en segundos de la inmersión de la mano desde la aparición del umbral hasta su retirada y Tolerancia al dolor (duración total en segundos de la inmersión de la mano desde su introducción hasta su retirada. Un análisis correlacional, factorial y de regresión por pasos mostraron un efecto cruzado entre medidas de ansiedad (tolerancia negativa al dolor y psicoticismo, siendo psicoticismo junto con control emocional predictores de tolerancia positiva al dolor. En cuanto a psicoticismo, parece que son sus elementos de naturaleza paranoide y de "dureza" los que afectan a una percepción atenuada del dolor.

  5. 75 FR 62858 - United States, et al.

    Science.gov (United States)

    2010-10-13

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Antitrust Division United States, et al. v. American Express Company, et al.; Proposed Final Judgment and... of America, et al. v. American Express Company, et al., Civil Action No. CV-10-4496. On October...

  6. 76 FR 38700 - United States, et al.

    Science.gov (United States)

    2011-07-01

    ... published in the Federal Register on October 13, 2010 (75 FR 62858); and (3) published summaries of the... Antitrust Division United States, et al. v. American Express Company, et al.; Public Comments and Response... Final Judgment in United States, et al. v. American Express Company, et al., Civil Action No....

  7. Al/Au/n-Si/Al surface barrier detector

    International Nuclear Information System (INIS)

    Charged-particle detectors are required to be operated sometimes in ambient light for applications like alpha counting and range finding. Detectors like Al/p-Si surface barrier with aluminium on the front side are found quite suitable. Gold/n-Si surface barrier detectors are not usable because of their excessive background photo current. These detectors, we fabricate for use in nuclear experiments, were given an aluminium coating on their gold side for use in room light. The Au/n-Si/Al surface barrier diodes were characterized for their electrical properties and performance as alpha detectors. Detectors showing good energy resolution (∼ 50 KeV) were selected and provided with another thin reflecting coat of aluminium on their front sides

  8. Electrowinning Al from Al2S3 in Molten Salt

    OpenAIRE

    Xiao, Y; Van der Plas, D.W.; Bohte, J.; Lans, S.C.; Van Sandwijk, A.; Reuter, M.A.

    2007-01-01

    In order to investigate an alternative process for the production of primary aluminum via a sulfide intermediate, the electrochemical behavior of Al2S3 in molten salt has been studied on a laboratory scale. The effects of electrolyte composition, temperature, and cell design on the cell performance have been investigated. Temperature and cryolite addition have positive effects on the current density. Increasing the anode-to-cathode surface area (closer to unity) and shortening the interelectr...

  9. Thermal conductance of a pressed Al-Al contact

    Science.gov (United States)

    Wanner, M.

    1981-01-01

    Thermal conductance of a screw-fastened joint between two blocks of Al-alloys has been measured. An AlMg4.5Mn-block, the end of which is cooled by liquid helium, constitutes the upper part of the sample and the contact is formed at the face surface of a cylindrical extension of that block onto which a cylinder, made of AlMgSi1, is pressed by means of a copper-nickel screw. Pressing of the contact was carried out at room temperature by applying a defined torque, M, to the fastening screw. Three samples of the same shape but with differently treated surfaces of contact (machined flat, electro-chemically polished, with gold plated contacts) were studied. The results showed that the machined flat surfaces yield the best contact and that the contact conductance (measured in the range 4.2 K to 1.8 K) of all samples increased with increasing torque. In addition to thermal measurements, a study of the electrical conductance would be very interesting to determine the different contributions of phonon and electron heat conduction by means of the Wiedemann-Franz law. The work is useful for the GIRL (German Infra-Red Laboratory) space experiment.

  10. Type idéal

    OpenAIRE

    Paugam, Serge

    2014-01-01

    L’usage de types idéaux constitue pour Max Weber une démarche sociologique fondamentale. Le type idéal est pour lui un moyen de comprendre le sens que les individus donnent à leurs expériences vécues, ce qui conduit à mettre ces dernières en relation avec l’organisation de la société à un moment historique de son évolution. Définir un type idéal ne signifie pas repérer sa forme majoritaire d’un point de vue statistique, mais discerner à partir des formes historiques des sociétés contemporaine...

  11. Al-Hadith Text Classifier

    Directory of Open Access Journals (Sweden)

    Mohammed Naji Al-Kabi

    2005-01-01

    Full Text Available This study explore the implementation of a text classification method to classify the prophet Mohammed (PBUH hadiths (sayings using Sahih Al-Bukhari classification. The sayings explain the Holy Qur`an, which considered by Muslims to be the direct word of Allah. Present method adopts TF/IDF (Term Frequency-Inverse Document Frequency which is used usually for text search. TF/IDF was used for term weighting, in which document weights for the selected terms are computed, to classify non-vocalized sayings, after their terms (keywords have been transformed to the corresponding canonical form (i.e., roots, to one of eight Books (classes, according to Al-Bukhari classification. A term would have a higher weight if it were a good descriptor for a particular book, i.e., it appears frequently in the book but is infrequent in the entire corpus.

  12. The effect of Si in Al-alloy on electromigration performance in Al filled vias

    Science.gov (United States)

    Kageyama, Makiko; Hashimoto, Keiichi; Onoda, Hiroshi

    1998-01-01

    Electromigration performance of vias filled with Al-Si-Cu alloys on Ti glue layers was investigated in comparison with W-stud vias. In Al-Si-Cu filled vias, voids were formed at only a few locations in the test structure, while voids were formed at every via in W-stud via chains. It is supposed that Al moves through the Al-Si-Cu via during electromigration in spite of the existence of a glue layer at the via bottom. This phenomenon was observed only in the vias filled with Al-Si-Cu alloy. Al movement was prohibited in Al-Cu filled vias. In Al-Si-Cu filled vias, an Al-Ti-Si alloy was formed at the via bottom while Al3Ti was formed at Al-Cu filled vias. Al is speculated to move through this Al-Ti-Si alloy during electromigration.

  13. Lernhabitus als Grundlage lebenslanger Lernprozesse

    OpenAIRE

    Herzberg, Heidrun

    2005-01-01

    'In diesem Artikel wird die These vertreten, dass das Habitus-Konzept von Bourdieu, wenn es bei der Analyse von lebenslangen (biographischen) Lern- und Bildungsprozessen angewandt wird, einer biographietheoretischen Reformulierung bedarf. Vor diesem Hintergrund wird das eigene Konzept des biographischen Lernhabitus vorgestellt. Als Ergebnis einer Zwei-Generationen-Studie im Rostocker Werftarbeitermilieu können zwei deutlich voneinander zu entscheidende Lernhabitusmuster präsentiert werden. In...

  14. Utilitarismus als Methode der Ethik

    OpenAIRE

    Daniels, Malte Cornelius

    2011-01-01

    In diesem Buch schlage ich eine radikal neuartige Sicht auf den Utilitarismus vor. Meine Hauptthese ist, dass der Utilitarismus selbst keine vollständige normative Theorie ist, aus der sich per se Handlungsbewertungen ableiten ließen, sondern normativ untersättigt und neutral ist. Sein normativer Gehalt ist vollständig abhängig von angenommenen Nutzenfunktionen. Jede konsistente Menge von moralischen Regeln (Moralsystem) kann, wie ich im Anhang beweise, als ein Spezialfall des Utilitarismus i...

  15. Vormundschaftsrecht als Grundlage politischer Herrschaft

    Directory of Open Access Journals (Sweden)

    Arne Duncker

    2006-07-01

    Full Text Available In ihrer beachtlichen und sehr gewissenhaft dokumentierten Arbeit über vormundschaftliche Regentschaften im 16. und 17. Jahrhundert beschreibt Pauline Puppel unter ausführlichem Bezug auf zeitgenössische Literatur und Archivalien sowohl die allgemeine Rechtslage im damaligen Reich als auch die Anwendungsfälle in Hessen, wo zwischen 1500 und 1700 insgesamt viermal eine Landgräfin als Vormünderin des Fürsten zur Regentin ihres Landes wurde. Dies steht exemplarisch für eine bereits in der Frühen Neuzeit mögliche und nicht einmal ganz seltene Form politischer Frauenherrschaft, die bisher oft nicht hinreichend gewürdigt wurde. Puppels Untersuchung ist in zwei Hauptteile gegliedert. Der erste Teil (Das juristische Regelwerk“, S. 34-143 behandelt die zeitgenössischen Rahmenbedingungen der durch Frauen ausgeübten Vormundschaft und Regentschaft. Der zweite Abschnitt („Die Landgräfinnen von Hessen als Regentinnen“, S. 144-307 befasst sich mit der Ausfüllung dieser Regeln durch konkrete Fallbeispiele in Gestalt von Leben und Regentschaft der regierenden Landgräfinnen von Hessen.

  16. Un acercamiento comparativo al pensamiento utópico y su relación con el 15M

    OpenAIRE

    Noemí Morejón Llamas

    2015-01-01

    El movimiento de Indignados que surge en España en mayo de 2011 con el fenómeno 15M supone el revivir de la utopía política en el siglo XXI. En el actual contexto de crisis económica y desgaste político los ciudadanos deciden reagruparse para exponer un discurso utópico y emocional. A través de la utopía política que proponen reavivan discursos pasados que defienden la libertad, la igualdad, la fraternidad y la esperanza en la bondad del ser humano. 

  17. Un acercamiento comparativo al pensamiento utópico y su relación con el 15M

    Directory of Open Access Journals (Sweden)

    Noemí Morejón Llamas

    2015-08-01

    Full Text Available El movimiento de Indignados que surge en España en mayo de 2011 con el fenómeno 15M supone el revivir de la utopía política en el siglo XXI. En el actual contexto de crisis económica y desgaste político los ciudadanos deciden reagruparse para exponer un discurso utópico y emocional. A través de la utopía política que proponen reavivan discursos pasados que defienden la libertad, la igualdad, la fraternidad y la esperanza en la bondad del ser humano. 

  18. Microstructure of interaction interface between Al-Si, Zn-Al alloys and Al2O3p/6061Al composite

    Institute of Scientific and Technical Information of China (English)

    许志武; 闫久春; 吕世雄; 杨士勤

    2004-01-01

    Interaction behaviors between Al-Si, Zn-AI alloys and Al2O3p/6061AI composite at different heating temperatures were investigated. It is found that Al2O3p/6061Al composite can be wetted well by AlSi-1, AlSi-4 and Zn-Al alloys and an interaction layer forms between the alloy and composite during interaction. Little Al-Si alloys remain on the surface when they fully wet the composite and Si element in Al-Si alloy diffuses into composite entirely and assembles in the composite near the interface of Al-Si alloy/composite to form a Si-rich zone. The microstructure in interaction layer with Si penetration is still dense. Much more residual Zn-Al alloy exists on the surface of composite when it wets the composite, and porosities appear at the interface of Zn-Al alloy/composite. The penetration of elements Zn, Cu of Zn-Al alloy into composite leads to the generation of shrinkage cavities in the interaction layer and makes the microstructure of Al2 O3p/6061A1 composite loose.

  19. The Structure and Main Issues of “al-Tasdid” of Husam al-Din al-Syghnaqi

    Directory of Open Access Journals (Sweden)

    Daniyar B. Shalkarov

    2015-07-01

    Full Text Available The study of the theological maturidia in the Central Asia was developed by the majority of outstanding scientists in the Turkic area and was known from generation to generation with manuscripts. One of these famous scientists was Abu al-Mu‘in al-Nasafi. In Central Asia, in the branch of the Islamic kalam theology there were the works “Tabsira al-Adilla”, “Bahr al-Kalam”, “al-Tamheed li qawa‘id al-Tawheed”, which considered the issues of maturidia theological study. In the XIV century the great scientist from Syghanaq Husam al-din al-Syghnaqi made a detailed research of the work “al-Tamheed li qawa‘id al-Tawheed” of Abu al-Mu‘in al-Nasafi and wrote the work “al-Tasdeed fi sharh al-Tamheed” by giving a full explanation of all questions relating to the issue. This article considers the content and the kept versions in the World libraries and the importance of this work for today. There is a different information about the original version of the manuscript. The first, the manuscript is by Amca Zade Huseyn 309 number, written by Husam al-din al-Syghnaqi personally and kept in the turkic library. This information is written in the work “Syghanaq Sanlagi/ The star of the Syghanaq” of Shamshaddin Kerim, the second manuscript is kept in the Egypt Arabic Republic, in the library “Dar al-Kutub Misrya”. It is written in this manuscript, that the manuscript was published in 1125 according hizhra calendar. Therefore the article gives an explanation of the main maturidia kalam principles, which cover five chapters of the work. 

  20. Armaflex in Burj al Arab; Armaflex im Burj al Arab

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, B.

    2003-07-01

    This article describes the Burj al Arab in Dubai, the unique seven-star high-rise hotel. The construction of the hotel, that is built on 250 piles driven into the sand of an artificial island in the Persian Gulf, is described. In particular, various special materials used in the building are described, as are the luxurious fittings and furnishings of the hotel. The cooling and air-conditioning installations that are necessary as a result of the desert climate of Dubai are described and the use of 'Armaflex' elastomer insulating material for the insulation of refrigeration machines and cold-water piping is discussed.

  1. De los derechos humanos al derecho al aborto

    OpenAIRE

    Zúñiga Fajuri, Alejandra

    2013-01-01

    Ninguna otra persona, en ninguna situación, es obligada a realizar el acto supererogatorio que se exige a la mujer embarazada. Aun cuando una adecuada aplicación de la teoría general de los derechos humanos permite reconocer el derecho al aborto durante los dos primeros trimestres del embarazo sobre la base de que los derechos sólo pueden restringirse por mor de los propios derechos. En esa línea, se intenta responder a quienes sostienen que el problema del aborto no puede resolverse pues no ...

  2. Friction Stir Welding of Al 5052 with Al 6061 Alloys

    OpenAIRE

    Kumbhar, N. T.; Bhanumurthy, K.

    2012-01-01

    Friction stir welding (FSW), a solid-state joining technique, is being extensively used in similar as well as dissimilar joining of Al, Mg, Cu, Ti, and their alloys. In the present study, friction stir welding of two aluminium alloys—AA6061 and AA5052—was carried out at various combinations of tool rotation speeds and tool traverse speeds. The transverse cross-section of the weld was used for optical as well as electron microscopy observations. The microstructural studies were used to get an ...

  3. Memahami Tasawuf Ibnuu Arabi dan Ibnuu al Farid: Konsep al Hubb Illahi, Wahdat al Wujud, Wahdah al Syuhud dan Wahdat al Adyan

    Directory of Open Access Journals (Sweden)

    Muhammad Robith Fuadi

    2013-12-01

    Full Text Available Kaum sufi menapaki jalan yang berbeda untuk menuju hakikat, mereka tidak menggunakan akal dan rasio untuk sampai pada hakikat. Akan tetapi, akal bukan satu-satunya jalan untuk menuju hakikat. Karena kita sering melihat sesuatu yang di luar jangkauan akal dalam hidup ini. Jalan yang ditempuh kaum sufi untuk menuju hakikat seperti kasyf, dzauq, 'iyan, musyahadah dan sebagainya dinilai sebagai sesuatu yang samar, tidak mempunyai batasan dan kaidah pasti, bahkan sering kali bercampur dengan igauan, mimpi, khayalan dan angan-angan. Tapi yang perlu kita ingat adalah bahwa media-media tersebut telah mampu menuntun manusia untuk memecahkan sesuatu yang tidak bisa dipecahkan oleh akal dan hukum-hukum fisika. Tulisan ini akan mengkaji gagasan-gagasan dua tokoh tasawuf besar yaitu Ibnu Arabi dan Ibnu al-Farid yang hidup  pada abad keenam dan ketujuh Hijriah. Tulisan ini secara spesifik akan mengkaji tiga gagasan penting ke dua tokoh tersebut. Yaitu al hubb al Ilahi, wahdat al Wujud dan wahdat al adyan.

  4. The Eminent Turkish Logician al-Abhari and "al-Risalah fî al-Kavâid al-Mantıqiyyah"

    OpenAIRE

    el-EBHERÎ, Esîrüddîn Mufaddal b. Ömer es-Semerkandî

    2014-01-01

    Athar al-Din al-Abhari is an important figure whose works had been textbooks in the Ottoman schools for centuries al-Abhari who wrote so many books in such areas as philosophy, mathematics, astronomy and logic is especially known for his books Hidayat al-Hikmat and İsaghuji He took logic into account in all of his works of philosophy. He also wrote some books and treatises specially concerning logical problems. Here, we are going to present the Turkish translation of his al-Risâlah fi al-Kava...

  5. United modification of Al-24Si alloy by Al-P and Al-Ti-C master alloys

    Institute of Scientific and Technical Information of China (English)

    韩延峰; 刘相法; 王海梅; 王振卿; 边秀房; 张均艳

    2003-01-01

    The modification effect of a new type of Al-P master alloy on Al-24Si alloys was investigated. It is foundthat excellent modification effect can be obtained by the addition of this new type of A1-P master alloy into Al-24Simelt and the average primary Si grain size is decreased below 47 μm from original 225 μm. It is also found that theTiC particles in the melt coming from Al8Ti2C can improve the modification effect of the Al-P master alloy. Whenthe content of TiC particles in the Al-24Si melt is 0.03 %, the improvement reaches the maximum and keeps steadywith increasing content of TiC particles. Modification effect occurs at 50 min after the addition of the Al-P master al-loy and TiC particles, and keeps stable with prolonging holding time.

  6. The Al-Al3Ni Eutectic Reaction: Crystallography and Mechanism of Formation

    Science.gov (United States)

    Fan, Yangyang; Makhlouf, Makhlouf M.

    2015-09-01

    The characteristics of the Al-Al3Ni eutectic structure are examined with emphasis on its morphology and crystallography. Based on these examinations, the mechanism of formation of this technologically important eutectic is postulated. It is found that a thin shell of α-Al forms coherently around each Al3Ni fiber. The excellent thermal stability of the Al-Al3Ni eutectic may be attributed to the presence of this coherent layer.

  7. Reply to Pachai et al.

    Science.gov (United States)

    Harrison, William J; Bex, Peter J

    2016-05-01

    Peripheral vision is fundamentally limited by the spacing between objects. When asked to report a target's identity, observers make erroneous reports that sometimes match the identity of a nearby distractor and sometimes match a combination of target and distractor features. The classification of these errors has previously been used to support competing 'substitution' [1] or 'averaging' [2] models of the phenomenon known as 'visual crowding'. We recently proposed a single model in which both classes of error occur because observers make their reports by sampling from a biologically-plausible population of weighted responses within a region of space around the target [3]. It is critical to note that there is no probabilistic substitution or averaging process in our model; instead, we argue that neither substitution nor averaging occur, but that these are misclassifications of the distribution of reports that emerge when a population response distribution is sampled. This is a fundamentally different way of thinking about crowding, and on this basis we claim to have provided a mechanism unifying categorically distinct perceptual errors. Our goal was not to model all crowding phenomena, such as the release from crowding when target and flanks differ in color or depth [4]. Pachai et al.[5] have suggested that our model is not unifying because it inaccurately predicts perceptual performance for a particular stimulus. Although we agree that our model does not predict their data, this specific demonstration overlooks the critical aspect of the model: perceptual reports are drawn from a weighted population code. We show that Pachai et al.'s [5] own data actually provide evidence for the population code we have described [3], and we suggest a biologically-plausible analysis of their stimuli that provides a computational basis for their 'grouping' account of crowding. PMID:27166690

  8. Al-Hadith Text Classifier

    OpenAIRE

    Mohammed Naji Al-Kabi; Ghassan Kanaan; Riyad Al-Shalabi; Saja I. Al- Sinjilawi; Ronza S. Al- Mustafa

    2005-01-01

    This study explore the implementation of a text classification method to classify the prophet Mohammed (PBUH) hadiths (sayings) using Sahih Al-Bukhari classification. The sayings explain the Holy Qur`an, which considered by Muslims to be the direct word of Allah. Present method adopts TF/IDF (Term Frequency-Inverse Document Frequency) which is used usually for text search. TF/IDF was used for term weighting, in which document weights for the selected terms are computed, to classify non-vocali...

  9. The ALS Gun Electronics system

    International Nuclear Information System (INIS)

    The ALS Gun Electronics system has been designed to accommodate gun with a custom made socket and high speed electronics circuit which is capable of producing single and multiple electron bunches with time jitters measured at better than 50 PS. The system generates the gated RF signal at ground level before sending it up to the 120 KV-biased gun deck via a fiber optic cable. The current pulse width as a function of grid bias, using an Eimac 8847A planar triode simulating an electron gun, was measured to show the relationship between the two parameters

  10. The ALS project: lessons learned

    Science.gov (United States)

    Monckton, Simon; Collier, Jack; Giesbrecht, Jared; Broten, Greg; MacKay, David; Erickson, David; Verret, Sean; Digney, Bruce

    2006-05-01

    In support of Canadian Forces transformation, Defence R&D Canada (DRDC) has established an ongoing program to develop machine intelligence for semi-autonomous vehicles and systems. Focussing on mine clearance and remote scouting for over a decade, DRDC Suffield has developed numerous UGVs controlled remotely over point-to-point radio links. Though this strategy removes personnel from potential danger, DRDC recognized that human factors and communications bandwidth limit teleoperation and that only networked, autonomous unmanned systems can conserve these valuable resources. This paper describes the outcome of the first autonomy project, Autonomous Land Systems (ALS), designed to demonstrate basic autonomous multivehicle land capabilities.

  11. Grainreifnementlimit of commercialpureAl inoculatedbyAl-Ti-C(B)masteralloys

    Institute of Scientific and Technical Information of China (English)

    En-zhao Wang; Xiang-fa Liu

    2015-01-01

    The grain reifnement limits of commercial pure Al inoculated by Al-5Ti-1B, Al-5Ti-0.25C and Al-5Ti-0.3C-0.2B master al oys were studied, and the inlfuence of melting temperature on the grain reifning performance of these three master al oys was investigated using a high scope video microscope (HSVM), a ifeld-emission scanning electron microscope (FESEM), an electron probe micro-analyzer (EPMA) and X–ray diffraction (XRD) method. Results show that there is a grain reifnement limit of commercial pure Al reifned by these three master al oys; with the same addition level of 1.5% under the present experimental conditions, the grain reifnement limits (smal est average grain size) of commercial pure Al reifned by Al-5Ti-1B, Al-5Ti-0.25C and Al-5Ti-0.3C-0.2B master al oys are 50 µm, 80 µm and 80 µm, respectively. In addition, with an increase in the melting temperature of the pure Al, the grain reifning performance of Al-5Ti-1B and Al-5Ti-0.25C master al oys decreases, but the grain reifning performance of Al-5Ti-0.3C-0.2B changes little.

  12. Analisis Salasilah Tarekat Shaykh Shams al-Din al-Sumatra’i

    OpenAIRE

    ROHAIMI RASTAM; MOHD SYUKRI YEOH ABDULLAH; YUSRI MOHAMAD RAMLI

    2015-01-01

    This article examines the spiritual chain (silsilah tariqah) of Shaykh Shams al-Din al-Sumatra’i (alt. al-Sumatrani), Qadi al-Malik al-‘Adil (Prime Minister and Mufti) of Aceh during the reign of Sultan Iskandar Muda in 1607 to 1627. The study is primarily based on his manuscript of Mir’at al-Muhaqqiqin as well as Shaykh Abdul Haqq Muhaddith Dahlawi’s Zad al-Muttaqin. By mapping the lineage of all data available, this study features al-Sumatra’is spiritual chain that consist of Qadiriyyah, Sh...

  13. Formaline of alternatieven als ontsmettingsmiddel voor broedeieren

    OpenAIRE

    Meijerhof, R.; Dijk, D. van

    1997-01-01

    Formaline wordt algemeen gezien als een goed middel om broedeieren te ontsmetten. Toch geeft ontsmetting met middelen als ozon en waterstofperoxyde vaak een iets beter broedresultaat. Een eventuele verklaring hiervoor is momenteel nog niet te geven.

  14. Benefits for Military Veterans with ALS

    Science.gov (United States)

    ... Chapters Certified Centers and Clinics Support Groups About ALS About Us Our Research In Your Community Advocate ... Veterans Resources for Military Veterans, Families & Survivors The ALS Association is working everyday to support people with ...

  15. AlON-SiAlON复合材料的制备及特性%Preparation and properties of AlON-SiAlON composites

    Institute of Scientific and Technical Information of China (English)

    山下敬; 山口明良

    2003-01-01

    为提高AlON陶瓷材料的抗氧化性能,制备了AlON-SiAl7O2N7复相材料.在1750℃、0.5 MPa的N2气氛中,保温2 h烧成不同Al2O3/AlN/Si3N4配比的原料得到不同AlON/SiAl7O2N7比的复相材料.因为在烧结SiAl7O2N7的过程中,蒸发-凝聚的同时伴随着SiO气体的挥发,因此很难得到致密的AlON-SiAl7O2N7复相材料.研究了AlON-SiAl7O2N7复相材料在1300℃、空气中的抗氧化性能,同时作为比较,研究了相同条件下单相的AlON材料的抗氧化性能.结果表明,AlON-SiAl7O2N7复相材料显示了较之单相的AlON陶瓷材料更好的抗氧化性能,这是因为氧化过程中所形成的含玻璃相的表面氧化层抑制了氧的向内扩散所致.

  16. Betaalde arbeid als verdringer van vrijwilligerswerk? Overbelasting als mogelijke verklaring

    Directory of Open Access Journals (Sweden)

    Angela Kok-Van Meer

    2014-06-01

    Full Text Available Do paid work activities displace volunteering? A potential explanation from role overload theoryRecent changes in Dutch society might lead to a shortage of volunteers. On the one hand, the demand for volunteers is increasing: in the social welfare domain because of governmental austerity policies and in other domains such as sports because of the higher supervision intensity of activities. On the other hand, the supply of volunteers is likely to decrease as more and more women and older workers are active in the labor market, which reduces the time that is available for volunteering. Role overload theory would suggest that the increasing labor participation rate of certain categories of workers goes along with a decline of participation in voluntary work. The secondary data analysis shows that various role loads (work, care for children living at home are associated with differences in participation in voluntary work. However, while a higher number of contractual work hours and hours spent on work-related training are negatively associated with volunteer work, care for children living at home is positively associated with volunteering. These results provide only limited support for role overload theory.Betaalde arbeid als verdringer van vrijwilligerswerk? Overbelasting als mogelijke verklaringDe afgelopen jaren hebben zich enkele maatschappelijke veranderingen voorgedaan, die wellicht tot schaarste op de Nederlandse vrijwilligersmarkt zouden kunnen leiden. Enerzijds neemt de vraag naar vrijwilligers toe doordat subsidieregelingen versoberen (bijvoorbeeld in zorg en welzijn en de begeleidingsintensiteit in bepaalde organisaties stijgt (bijvoorbeeld in sport. Anderzijds neemt het aanbod van vrijwilligers af doordat vrouwen en ouderen meer en langer op de arbeidsmarkt actief zijn, waardoor minder tijd beschikbaar is voor vrijwilligerswerk. In dit artikel wordt aan de hand van de role overload theorie nagegaan of het al dan niet deelnemen aan

  17. Influencia de la microestructura en el comportamiento a desgaste abrasivo evaluado bajo norma ASTM G 65 de depósitos de soldadura antidesgaste aplicados sobre sustratos de acero de baja aleación y bajo carbono / Influence of microstructure on the behavior abrasive wear tested under ASTM G 65 weld deposits on substrates used wear low alloy steel and low carbon

    OpenAIRE

    Pérez Cepeda, Jaime Andrés

    2011-01-01

    En la reconstrucción de piezas de maquinarias es esencial el poder determinar la mejor opción en cuanto a material depositado por soldadura para recuperación de geometrías perdidas se refiere. El presente trabajo se desarrolló para mejorar las aplicaciones de recubrimientos duros y material de relleno para la reconstrucción de “sprockets”, pero que se pueda extrapolar al uso en industrias de diferente tipo. Se tomaron en cuenta tres (3) factores, material depositado, temperatur...

  18. Thermoluminescence properties of AlN ceramics

    DEFF Research Database (Denmark)

    Trinkler, L.; Christensen, P.; Agersnap Larsen, N.; Berzina, B.

    The paper describes thermoluminescence (TL) properties of AlN:Y2O3 ceramics irradiated with ionising radiation. A high TL sensitivity of AlN:Y2O3 ceramics to radiation encouraged a study of the AlN ceramics for application as a dosimetric material. The paper presents experimental data on: glow...

  19. Electroplating Zn-Al Alloy Technology

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The method of controlling separating anode and separating power source was used to perform orthogonal optimization for the parameters in electroplating Zn-Al alloy.The electroplating Zn-Al alloy technology was decided, in which the content of Al is about 12%-15%.

  20. The fabrication of 26Al targets

    International Nuclear Information System (INIS)

    Targets with up to 1.4x101626Al atoms have been fabricated. The artificial production of the 26Al nuclei via the reaction 26Mg(p, n)26Al was carried out at the cyclotrons in Juelich and Muenchen. The experimental procedures in the fabrication of these targets as well as some test measurements are described. (orig.)

  1. Nonstoichiometry of Al-Zr intermetallic phases

    Energy Technology Data Exchange (ETDEWEB)

    Radmilovic, V.; Thomas, G.

    1994-06-01

    Nonstoichiometry of metastable cubic {beta}{prime} and equilibrium tetragonal {beta} Al-Zr intermetallic phases of the nominal composition Al{sub 3}Zr in Al-rich alloys has been extensively studied. It is proposed that the ``dark contrast`` of {beta}{prime} core in {beta}{prime}/{sigma}{prime} complex precipitates, in Al-Li-Zr based alloys, is caused by incorporation of Al and Li atoms into the {beta}{prime} phase on Zr sublattice sites, forming nonstoichiometric Al-Zr intermetallic phases, rather than by Li partitioning only. {beta}{prime} particles contain very small amounts of Zr, approximately 5 at.%, much less than the stoichiometric 25 at.% in the Al{sub 3}Zr metastable phase. These particles are, according to simulation of high resolution images, of the Al{sub 3}(Al{sub 0.4}Li{sub 0.4}Zr{sub 0.2}) type. Nonstoichiometric particles of average composition Al{sub 4}Zr and Al{sub 6}Zr are observed also in the binary Al-Zr alloy, even after annealing for several hours at 600{degree}C.

  2. Topiramat als Phasenprophylaktikum - ein Fallbericht

    Directory of Open Access Journals (Sweden)

    Letmaier M

    2001-01-01

    Full Text Available Topiramat ist ein neues Antiepileptikum mit einem breiten Wirkspektrum. Aktuelle klinische Studien geben Hinweise darauf, daß Topiramat stimmungsstabilisierende Eigenschaften besitzt und somit effizient in der Behandlung der bipolaren affektiven Störung sein könnte. Vor dem Hintergrund dieser Studienberichte, behandelten wir eine 41jährige, erstmals vor 10 Jahren erkrankte Patientin mit der Diagnose einer therapierefraktären, bipolaren affektiven Störung (Rapid-Cycling mit Topiramat. Im Rahmen ihrer Erkrankung wurde die Patientin insgesamt 12mal stationär aufgenommen und meist aufgrund von akuten manischen Episoden behandelt. Dabei kamen seit 1991 folgende Phasenprophylaktika zur Anwendung: Carbamazepin, Valproat und Lamotrigin ? zuletzt nur mit mäßigem Erfolg. Daraufhin wurde zu Beginn einer neuerlichen manischen Episode ambulant eine Therapie mit Topiramat begonnen. Acht Wochen nach Therapiestart kam die Patientin in stationäre Behandlung. Der Aufenthalt dauerte weniger als drei Wochen; Topiramat wurde von der Patientin gut vertragen. Infolge eines belastenden Lebensereignisses kam es unter kontinuierlicher Therapie mit Topiramat zu einer Destabilisierung des psychischen Zustandsbildes (manische Symptome. Durch eine ambulante Erhöhung der Topiramatdosis bei gleichzeitiger Gabe von Risperidon und Clonazepam konnte jedoch eine neuerliche manische Episode erstmals ambulant behandelt werden. Die Patientin erhält derzeit 200 mg Topiramat pro Tag und ist seit mehr als 20 Monaten nahezu beschwerdefrei.

  3. Systems Engineering Techniques for ALS Decision Making

    Science.gov (United States)

    Rodriquez, Luis F.; Drysdale, Alan E.; Jones, Harry; Levri, Julie A.

    2004-01-01

    The Advanced Life Support (ALS) Metric is the predominant tool for predicting the cost of ALS systems. Metric goals for the ALS Program are daunting, requiring a threefold increase in the ALS Metric by 2010. Confounding the problem, the rate new ALS technologies reach the maturity required for consideration in the ALS Metric and the rate at which new configurations are developed is slow, limiting the search space and potentially giving the perspective of a ALS technology, the ALS Metric may remain elusive. This paper is a sequel to a paper published in the proceedings of the 2003 ICES conference entitled, "Managing to the metric: an approach to optimizing life support costs." The conclusions of that paper state that the largest contributors to the ALS Metric should be targeted by ALS researchers and management for maximum metric reductions. Certainly, these areas potentially offer large potential benefits to future ALS missions; however, the ALS Metric is not the only decision-making tool available to the community. To facilitate decision-making within the ALS community a combination of metrics should be utilized, such as the Equivalent System Mass (ESM)-based ALS metric, but also those available through techniques such as life cycle costing and faithful consideration of the sensitivity of the assumed models and data. Often a lack of data is cited as the reason why these techniques are not considered for utilization. An existing database development effort within the ALS community, known as OPIS, may provide the opportunity to collect the necessary information to enable the proposed systems analyses. A review of these additional analysis techniques is provided, focusing on the data necessary to enable these. The discussion is concluded by proposing how the data may be utilized by analysts in the future.

  4. Polythermal cutting of Al-Si-YAl2 system

    International Nuclear Information System (INIS)

    Given the out come of the research of the Al-Si-YAl2 system with studies of polythermal cutting. It was found out that the most cutting of Al-YSi2Al2, Al-YSiAl2, Al-Y5SiAl14, YSiAl2-YSi2Al2, Y5SiAl14-YSiAl2 and Y5SiAl14-YAl2, Si-YSiAl2 has the nature of quasibinary eutectics

  5. Progresses in analyzing 26Al with SMCAMS

    International Nuclear Information System (INIS)

    Shanghai Mini-Cyclotron based Accelerator Mass Spectrometer (SMCAMS) was especially designed for analyzing 14C. In order to accelerate and analyze 26Al the accelerated orbit and beam optics in injection system were calculated and harmonic number and acceleration turns was optimized. Preliminary experiment was carried out. In which a beam current of 1.15 x 10-9A for 27Al- and 0.038 CPS background for 26Al were measured. The limited sensitivity of 26Al/27Al is 5.25 x 10-12. (authors)

  6. AlON粉体的合成

    Institute of Scientific and Technical Information of China (English)

    赵小军; 茹红强; 张宁; 孙有政

    2009-01-01

    以α-Al2O3和AlN为原料,利用高温固相反应在氮气气氛下常压合成了AlON粉体。研究了成分配比、合成温度、保温时间对合成AlON粉体含量的影响,并通过热分析测试了合成过程热流和质量的变化。结果表明,当原料Al2O3和AlN的质量比为81:18、合成工艺为1750℃,2h时,得到AlON相的含量达到95%以上。

  7. Mecanismes associats al desenvolupament de la caquèxia en estats patològics

    OpenAIRE

    Figueras Polo, Maria Teresa

    2005-01-01

    [cat] Durant certes situacions catabòliques, com el càncer o la sèpsia entre d'altres, es dóna un fet comú que és la pèrdua de massa muscular. En el nostre grup d'investigació s'ha estudiat en profunditat el desgast muscular associat a la síndrome de la caquèxia. Així, s'ha identificat el sistema proteolític dependent d'ATP i ubiquitina com a mecanisme que participa en l'activació de la proteòlisi muscular. A més, s'han identificat determinades citocines, particularment el TNF-alfa, elements ...

  8. Trato verbal paterno al adolescente

    Directory of Open Access Journals (Sweden)

    Rodríguez Juan Carlos

    1995-06-01

    Full Text Available

    En alguna ocasión se ha escuchado una palabra, que causa un sentimiento y a la vez un recuerdo, que lleva a evocar la adolescencia o la infancia, se recuerda quien la pronunciaba y en que ocasión la decía. Este es el poder que tiene una palabra y más aún si es dicha por el padre, puesto que este es la figura significativa que se lleva en la memoria. De aquí nace el interés de realizar un estudio, en donde se describe y analice la percepción y el sentimiento del adolescente, quien en esta etapa es vulnerable al cambio, ya que está buscando su propia identidad; que con el trato verbal paterno la encontrara sin ninguna dificultad o por el contrario nunca la encontrará.

     

  9. Orientation of Al3Ti platelets in Al-Al3Ti functionally graded material manufactured by centrifugal method

    International Nuclear Information System (INIS)

    Al-Al3Ti functionally graded materials (FGMs) were manufactured by the centrifugal method with a commercial ingot of Al-5 mass% Ti master alloy. The alloy was melted at a liquid/solid coexisting temperature, at which Al3Ti remains as a solid, and then it was cast into a thick-walled ring. It was found that the Al-Al3Ti functionally graded material can be successfully fabricated by the centrifugal method. It was also found that the volume fraction of the Al3Ti can be increased by repetition of the centrifugal method. Since the shape of Al3Ti particles in a commercial alloy ingot is that of a platelet, the Al3Ti particles are arranged with their platelet planes nearly perpendicular to the radial direction. The orientation effects become stronger when the G number becomes larger. Although the final centrifugal casting was conducted under a very large centrifugal force for the specimen cast three times, the orientation effects were weaker than those in the specimen cast one time. From these observations, it is concluded that the origin of orientation of Al3Ti platelets can be attributed to the angular velocity gradient of the melt along the radial direction produced by the difference in the viscosity. (orig.)

  10. TEM characterization of Al-C-Cu-Al2O3 composites produced by mechanical milling

    International Nuclear Information System (INIS)

    Novel Al-based composites (Al-C-Cu-Al2O3) obtained by mechanical milling (MM), were characterized by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). Analyses of composites were carried out in both, the as-milled and the as-sintered conditions. C nanoparticles were found in the as-milled condition and Al2O3 nanofibers were found in as-sintered products, as determined by EELS. C and Cu react with Al to crystallize in Al3C4 and Al2Cu structures, respectively

  11. MARTENSITIC TRANSFORMATION AND THERMAL STABILITY IN Cu-Al-Co AND Cu-Al-Zr ALLOYS

    Institute of Scientific and Technical Information of China (English)

    Y. Q. Ma; C.B. Jiang; H.B. Xu

    2003-01-01

    Cu-Al-Co and Cu-Al-Zr alloys were explored with Co or Zr additions in Cu-Al alloys for high temperature shape memory alloys. Samples were quenched after homogenized at 850℃ for 48h. It was found that both Cu-Al-Co and Cu-Al-Zr show AlCu3 martensitic phase at room temperature and exhibit martensitic transformation temperatures higher than 200℃, showing the potentials for developing as high temperature shape memory alloys. Thermal cycles were performed by DSC instrument on both Cu-Al-Co and Cu-Al-Zr alloys. The results show that Cu-Al-Co loses its martensitic transformation after five thermal cycles, and Cu-Al-Zr exhibits no martensitic transformation in the second thermal cycle.

  12. Influences of Al particles on the microstructure and property of electrodeposited Ni-Al composite coatings

    Science.gov (United States)

    Cai, Fei; Jiang, Chuanhai

    2014-02-01

    Ni-Al composite coatings with different contents of Al microparticles were prepared from a conventional Watt bath. The influences of Al particle loadings in the bath on the surface morphology, composition, texture, grain size, microstrain, residual stress and anti-corrosion of the Ni-Al composite coating were investigated. The friction coefficients of the coatings at 200 °C were also evaluated by a pin-on-disctribometer. The results showed that the surface morphology of the coatings changed from pyramid + colonied structure to colonied structure with increasing Al particle loadings. The (2 0 0) preferred orientation for pure Ni coating evolved to random orientation with increasing Al particle loadings. The grain size obtained the minimum value of 72.28 nm at Al particle loading of 100 g/L and the microstrain of the coating increased with increasing the Al particle loadings. The incorporation of Al particles decreased the residual stress of the electro-deposited coating and all the coatings deposited at different Al particle loadings possessed low residual stress. As the Al particle loading increased, the anti-corrosion of the Ni-Al coatings increased owing to the combined effect of increasing Al content in the coatings and the texture evolution from (2 0 0) plane to (1 1 1) plane. The wear result suggested that the increasing Al particle content did not improve the wear performance of the Ni-Al composite coatings.

  13. Efficiency droop in high-Al-content AlGaN/AlGaN quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Tamulaitis, G.; Mickevicius, J.; Kazlauskas, K.; Zukauskas, A. [Institute of Applied Research and Department of Semiconductor Physics, Vilnius University, Sauletekio 9-III, 10222 Vilnius (Lithuania); Shur, M.S. [Department of ECE and CIE, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY 12180 (United States); Yang, J.; Gaska, R. [Sensor Electronic Technology Inc., 1195 Atlas Road, Columbia, SC 29209 (United States)

    2011-07-15

    Excitation power density dependence of photoluminescence (PL) efficiency is studied in the temperature range from 8 to 300 K for AlGaN multiple quantum well structures containing quantum wells of different width. PL efficiency droop is observed and dependence of the droop effect on the well width and lattice temperature is discussed. Photoluminescence band shape reveals strong carrier heating. It is shown that the heating effect has a substantial influence on the photoluminescence efficiency droop, especially at low lattice temperatures. Fitting of the temperature dependence of the PL band width with that obtained by the Monte Carlo simulation of carrier (exciton) hopping via localized states shows that (i) the potential fluctuations can be fairly accurately described using a double-scaled potential profile model, (ii) the localization becomes stronger in narrower quantum wells. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Al-Si/Al2O3 in situ composite prepared by displacement reaction of CuO/Al system

    Directory of Open Access Journals (Sweden)

    Zhang Jing

    2010-02-01

    Full Text Available Al2O3 particle-reinforced ZL109 composite was prepared by in situ reaction between CuO and Al. The microstructure was observed by means of OM, SEM and TEM. The Al2O3 particles in sub-micron sizes distribute uniformly in the matrix, and the Cu displaced from the in situ reaction forms net-like alloy phases with other alloy elements. The hardness and the tensile strength of the composites at room temperature have a slight increase as compared to that of the matrix. However, the tensile strength at 350 ℃ has reached 90.23 MPa, or 16.92 MPa higher than that of the matrix. The mechanism of the reaction in the CuO/Al system was studied by using of differential scanning calorimetry(DSC and thermodynamic calculation. The reaction between CuO and Al involves two steps. First, CuO reacts with Al to form Cu2O and Al2O3 at the melting temperature of the matrix alloy, and second, Cu2O reacts with Al to form Cu and Al2O3 at a higher temperature. At ZL109 casting temperature of 750–780 ℃, the second step can also take place because of the effect of exothermic reaction of the first step.

  15. Fabrication of TiAl3 coating on TiAl-based alloy by Al electrodeposition from dimethylsulfone bath and subsequent annealing

    OpenAIRE

    Miyake, Masao; Tajikara, Seiya; Hirato, Tetsuji

    2011-01-01

    TiAl3 coating was formed on TiAl alloy by Al electrodeposition from a dimethylsulfone (DMSO2) bath and subsequent annealing. Before the Al electrodeposition, anodic dissolution of TiAl substrate in the DMSO2 bath was conducted to remove the surface oxide layer of the TiAl substrate. By performing the Al electrodeposition immediately after the anodic dissolution, uniform Al films adherent to the TiAl substrate could be obtained. Annealing at 650–1000 °C yielded a single TiAl3 layer or two laye...

  16. Orientation relationship of eutectoid FeAl and FeAl2

    Science.gov (United States)

    Scherf, A.; Kauffmann, A.; Kauffmann-Weiss, S.; Scherer, T.; Li, X.; Stein, F.; Heilmaier, M.

    2016-01-01

    Fe–Al alloys in the aluminium range of 55–65 at.% exhibit a lamellar microstructure of B2-ordered FeAl and triclinic FeAl2, which is caused by a eutectoid decomposition of the high-temperature Fe5Al8 phase, the so-called ∊ phase. The orientation relationship of FeAl and FeAl2 has previously been studied by Bastin et al. [J. Cryst. Growth (1978 ▸), 43, 745] and Hirata et al. [Philos. Mag. Lett. (2008 ▸), 88, 491]. Since both results are based on different crystallographic data regarding FeAl2, the data are re-evaluated with respect to a recent re-determination of the FeAl2 phase provided by Chumak et al. [Acta Cryst. (2010 ▸), C66, i87]. It is found that both orientation relationships match subsequent to a rotation operation of 180° about a 〈112〉 crystallographic axis of FeAl or by applying the inversion symmetry of the FeAl2 crystal structure as suggested by the Chumak data set. Experimental evidence for the validity of the previously determined orientation relationships was found in as-cast fully lamellar material (random texture) as well as directionally solidified material (∼〈110〉FeAl || solidification direction) by means of orientation imaging microscopy and global texture measurements. In addition, a preferential interface between FeAl and FeAl2 was identified by means of trace analyses using cross sectioning with a focused ion beam. On the basis of these habit planes the orientation relationship between the two phases can be described by (01)FeAl || (114) and [111]FeAl || [10]. There is no evidence for twinning within FeAl lamellae or alternating orientations of FeAl lamellae. Based on the determined orientation and interface data, an atomistic model of the structure relationship of Fe5Al8, FeAl and FeAl2 in the vicinity of the eutectoid decomposition is derived. This model is analysed with respect to the strain which has to be accommodated at the interface of FeAl and FeAl2. PMID:27047304

  17. Electron channelling enhanced microanalysis on Ni-Al-Mn and Al-Mn-Si

    International Nuclear Information System (INIS)

    Atom location by channelling enhanced microanalysis (ALCHEMI) was performed for Ni-Al-Mn compounds and Al-Mn-Si quasicrystals. For Ni75Al25-xMnx (x=5,9) with the L12-type structure, an occupation fraction of Mn atoms at the Ni site was quantitatively determined using planar channelling conditions. The occupation fraction increases with the Mn concentration or by quenching the compound from high temperature. In quasicrystals of Al74Mn20Si6 and Al68Mn20Ru8Si4, axial channelling conditions were used to locate Si and Ru, respectively. It was shown that Si atoms occupy the Al site in Al74Mn20Si6 whereas Ru atoms occupy the site different from that of Al in Al68Mn20Ru8Si4. (author)

  18. Microstructure and mechanical properties of Ti2AlC-reinforced TiAl composites

    International Nuclear Information System (INIS)

    Ti2AlC/TiAl composites were successfully in-situ synthesized by reaction hot pressing using Ti, Al, TiC and CNTs as starting materials. The results indicate that the as-sintered composites mainly consist of Ti2AlC and TiAl phases. The mechanical properties of the 23 wt.% Ti2AlC/TiAl composite exhibit the highest values, with a flexural strength and fracture toughness of 652.5 ± 76.8 MPa and 6.6 ± 0.5 MPa m1/2, respectively. The complex structure coupled with dispersed Ti2AlC micro-particulates is responsible for the enhancement in the strength. Toughening of the composite is mainly attributed to crack deflection, crack bridging, crack branching and pull-out of the Ti2AlC particles, as well as transgranular cracking.

  19. High pressure studies of UFe5Al7 and UFe7Al5 actinide compounds

    International Nuclear Information System (INIS)

    The ternary inter-metallic compounds, UFe5Al7 and UFe7Al5, crystallize in a tetragonal ThMn12 type structure. In the as-cast samples a residual phase of FeAl (∼2%wt) was identified in the grain boundaries. The amount of the residual cubic phase of FeAl was determined by Rietveld analysis and reduced by the annealing process. UFe5Al7 and UFe7Al5 maintain the tetragonal symmetry as a function of pressure, while FeAl keeps the cubic structure as was determined by the Rietveld analysis. The volume-pressure curve calculated from the X-ray analysis gives V/V0=0.87 for UFe5Al7 at 26.0 GPa and 0.89 at 24.6 GPa for UFe7Al5. (author)

  20. Chemical mixing at "Al on Fe" and "Fe on Al" interfaces

    Science.gov (United States)

    Süle, P.; Kaptás, D.; Bujdosó, L.; Horváth, Z. E.; Nakanishi, A.; Balogh, J.

    2015-10-01

    The chemical mixing at the "Al on Fe" and "Fe on Al" interfaces was studied by molecular dynamics simulations of the layer growth and by 57Fe Mössbauer spectroscopy. The concentration distribution along the layer growth direction was calculated for different crystallographic orientations, and atomically sharp "Al on Fe" interfaces were found when Al grows over (001) and (110) oriented Fe layers. The Al/Fe(111) interface is also narrow as compared to the intermixing found at the "Fe on Al" interfaces for any orientation. Conversion electron Mössbauer measurements of trilayers—Al/57Fe/Al and Al/57Fe/Ag grown simultaneously over Si(111) substrate by vacuum evaporation—support the results of the molecular dynamics calculations.

  1. Fabrication of /sup 26/Al targets

    Energy Technology Data Exchange (ETDEWEB)

    Buchmann, L.; Baumeister, H.; Rolfs, C.

    1984-06-01

    Targets with up to 1.4x10/sup 16/ /sup 26/Al atoms have been fabricated. The artificial production of the /sup 26/Al nuclei via the reaction /sup 26/Mg(p, n)/sup 26/Al was carried out at the cyclotrons in Juelich and Muenchen. The experimental procedures in the fabrication of these targets as well as some test measurements are described.

  2. The wobbler mouse, an ALS animal model

    OpenAIRE

    Moser, Jakob Maximilian; Bigini, Paolo; Schmitt-John, Thomas

    2013-01-01

    This review article is focused on the research progress made utilizing the wobbler mouse as animal model for human motor neuron diseases, especially the amyotrophic lateral sclerosis (ALS). The wobbler mouse develops progressive degeneration of upper and lower motor neurons and shows striking similarities to ALS. The cellular effects of the wobbler mutation, cellular transport defects, neurofilament aggregation, neuronal hyperexcitability and neuroinflammation closely resemble human ALS. Now,...

  3. A New Phase in ALS Research.

    Science.gov (United States)

    Chong, P Andrew; Forman-Kay, Julie D

    2016-09-01

    In this issue of Structure, Conicella et al. (2016) present evidence that the low complexity C-terminal region of TDP-43 undergoes liquid-liquid phase separation. ALS-associated mutations alter this phase separation process, providing a possible mechanism for the pathology caused by these TDP-43 mutations. The work is strongly supportive of toxic loss of RNA processing function in ALS. PMID:27602988

  4. Growth of CdTe: Al films

    International Nuclear Information System (INIS)

    CdTe: AI films were grown by the close space vapor transport technique combined with free evaporation (CSVT-FE). The Aluminum (Al) evaporation was made by two kinds of sources: one made of graphite and the other of tantalum. The films were deposited on glass substrates. The Al source temperature was varied maintaining the CdTe source temperature fixed as well as the substrate temperature. The films were characterized by x-ray energy dispersive analysis (EDAX), x-ray diffraction and optical transmission. The results showed for the films grown with the graphite source for Al evaporation, the Al did not incorporate in the CdTe matrix, at least to the level of EDAX sensitivity; they maintained the same crystal structure and band gap. For the samples grown with the tantalum source, we were able to incorporate the Al. The x-ray diffraction patterns show that the films have a crystal structure that depends on Al concentration. They were cubic up to 2.16 at. % Al concentration; for 19.65 at. % we found a mixed phase; for Al concentration higher than 21 at. % the films were amorphous. For samples with cubic structure it was found that the lattice parameter decreases and the band gap increases with Al concentration. (Author)

  5. Genetics of Familial and Sporadic ALS

    Science.gov (United States)

    2016-03-21

    Amyotrophic Lateral Sclerosis (ALS); Familial Amyotrophic Lateral Sclerosis; Amyotrophic Lateral Sclerosis With Frontotemporal Dementia; Lou Gehrig's Disease; Motor Neuron Disease; Primary Lateral Sclerosis

  6. 关于w-al-CL空间%On w-al-CL Spaces

    Institute of Scientific and Technical Information of China (English)

    林丽琼; 张云南

    2011-01-01

    给出w-al-CL空间的定义,比较几种CL性的关系,讨论w-al-CL空间的c0和与l1和的稳定性,并讨论C(K,X)空间的w-al-CL性.%Gives the definition of w-al-CL spaces, compare the relationship of some properties of CL, discusses the stability of c0 -sums and l1 -sums of w-al-CL spaces, and discusses the property of w-al-CL of C(K,X) spaces.

  7. Interfacial strength of Al/Al and Al/Zr/Du-10wt%Mo subject to different loading modes

    International Nuclear Information System (INIS)

    Compact tension (CT) experiments were conducted with fixtures that allowed mode-I (tensile opening mode), mode-Il (shearing mode), and mixed-mode loading to measure the interfacial strength between HIP-clad Al and Al, and Al and Zr/DU-10wt%Mo. Specimens were made with the same HIP process used for making thin composite foils, but instead used 25 mm thick Al-6061 cladding that allowed specimens to be gripped without adhesives. Three configurations of specimens were tested: (1) Al/Al specimens with a pre-crack along the seam; (2) specimens containing both a Zr/DU-10wt%Mo layer and an Al/Al seam along part of the interface; and (3) specimens containing only a Zr/DU-10wt%Mo layer at the interface, but with a pre notch along part of the interface. Digital image correlation (DIC) was used to measure full-field deformations during the test. The results show that mode-I loaded interfaces exhibit the weakest strength and the widest scatter. The strength increases when more shearing component is introduced

  8. Untersuchung der Nitridierung V/Al-intermetallischer Phasen

    OpenAIRE

    Lewalter, Hartmut Berthold

    2004-01-01

    Schichten V/Al-Intermetallischer Phasen und Schichten aus V(Al) (Schichtdicken 150- 300 nm) wurden durch Interdiffusion von V/Al- und V5Al8/V-Mehrfachschichten bei 400-800°C im Vakuum bei 3 x 10-8 mbar hergestellt. Des Weiteren wurden V5Al8-Schichten durch Sputtern einer V5Al8-Legierung erzeugt. Die Gesamtstöchiometrie der Schichten lag zwischen Al0,86V0,14 und Al0,19V0,81. Als Substrat dienten einkristalline (012) Saphirwafer. Die V/Al-Intermetallischen Phasen und V(Al) wurden im RTP-System ...

  9. Response to Signorovitch et al.

    Science.gov (United States)

    Flot, Jean-François; Debortoli, Nicolas; Hallet, Bernard; Van Doninck, Karine

    2016-08-22

    Signorovitch et al.[1] comment that an Oenothera-like meiosis [2] could produce a pattern similar to what we observed in our study of natural isolates of the bdelloid rotifer Adineta vaga, which we attributed to horizontal gene transfers (HGTs) [3]. Indeed, our HGT hypothesis appears at first sight difficult to conciliate with their observation of a congruent pattern of allele sharing at four large loci possibly located on different chromosomes [4]. However, one might imagine conditions under which massive horizontal gene transfer between bdelloid individuals could produce such a pattern, notably if the individuals involved had previously lost most of their heterozygosity because of their exposure to frequent desiccation (which produces DNA double-strand breaks [5]). In the published A. vaga genome the loss of heterozygosity due to large-scale gene conversion events or break-induced replication covers only about 10% of the genome [6], but this percentage may be much higher in environmental isolates that often experience dessication. Besides, if an Oenothera-like mode of meiosis occurs in bdelloids frequently enough to be detected in a single sampling of 29 individuals (as in [4]), one would expect males and meiosis to be observed at least occasionally, and instances of congruent allele sharing across loci should turn up frequently in genetic surveys. This was not the case in [3]: among the 82 A. vaga individuals sequenced for four nuclear markers, no trio of individuals presented congruent patterns of shared sequences at different loci. For these reasons, and in the absence of any direct evidence for an Oenothera-like meiosis in bdelloids, we still consider inter-bdelloid HGTs a more parsimonious explanation for our results. PMID:27554651

  10. Atomic structure and oxygen deficiency of the ultrathin aluminium oxide barrier in Al/AlOx/Al Josephson junctions.

    Science.gov (United States)

    Zeng, Lunjie; Tran, Dung Trung; Tai, Cheuk-Wai; Svensson, Gunnar; Olsson, Eva

    2016-01-01

    Al/AlOx/Al Josephson junctions are the building blocks of a wide range of superconducting quantum devices that are key elements for quantum computers, extremely sensitive magnetometers and radiation detectors. The properties of the junctions and the superconducting quantum devices are determined by the atomic structure of the tunnel barrier. The nanoscale dimension and disordered nature of the barrier oxide have been challenges for the direct experimental investigation of the atomic structure of the tunnel barrier. Here we show that the miniaturized dimension of the barrier and the interfacial interaction between crystalline Al and amorphous AlOx give rise to oxygen deficiency at the metal/oxide interfaces. In the interior of the barrier, the oxide resembles the atomic structure of bulk aluminium oxide. Atomic defects such as oxygen vacancies at the interfaces can be the origin of the two-level systems and contribute to decoherence and noise in superconducting quantum circuits. PMID:27403611

  11. Band edge modulation and interband optical transition in AlN:MgAl-ON nanotubes

    International Nuclear Information System (INIS)

    AlN nanotubes (NTs) have many novel characteristics and great potential applications in electronic and optoelectronic nanodevices. However, little is known about the influence of MgAl-ON co-doping effects on their optical properties. Here, we focus on investigating the electronic structures, clarify the interband optical transition mechanism and give a clear atomic picture for the important electron/hole localization centre in AlN:MgAl-ON NTs using the GGA-1/2 method. We find that the MgAl doping efficiency can be improved effectively due to ON doping in AlN NTs. The MgAl and ON form MgAl-ON defect complex easily along the AlN NT axis (C-axis). The MgAl-ON defect complex can result in a remarkable charge transfer around it and modify the valence band maximum and conduction band minimum significantly. Meanwhile, the MgAl-ON defect complex also forms the important exciton localization centre and effectively enhances the interband radiative recombination rate. Moreover, the light emission/absorption sensitively depends on its polarization. The parallel polarized light (E∥C) is much stronger than the perpendicular one (E⊥C). The MgAl-ON co-doping thus paves a new way for improving the performance of electronic and optoelectronic nanodevices based on AlN NTs. (papers)

  12. Efecto del amperaje en las propiedades de recubrimientos duros resistentes a la abrasión aplicados por soldadura

    OpenAIRE

    Héctor Iván Monsalve Gil; David Alejandro Mena Herrera; Jorge Enrique Giraldo Barrada

    2004-01-01

    Se estudió el efecto del amperaje en la microestructura, la dureza y la resistencia al desgaste abrasivo de dos aleaciones para recubrimientos duros con base hierro, alto Cr y C. Se aplicaron dos y tres capas de cada electrodo mediante el proceso SMAW sobre platinas de acero ASTM A36. La resistencia al desgaste abrasivo se calculó midiendo la masa perdida después de un ensayo de acuerdo al estándar internacional ASTM G65. La microestructura fue analizada usando microscopio óptico ...

  13. Efecto del calor aportado en recargues nanoestructurados base hierro

    OpenAIRE

    Agustín Gualco; Hernán G. Svoboda; Estela S. Surian

    2013-01-01

    En los últimos años se han desarrollado consumibles de soldadura que depositan recubrimientos duros de aleaciones base hierro nanoestructuradas de gran resistencia al desgaste abrasivo. Las resistencias al desgaste erosivo y abrasivo están controladas principalmente por la composición química y la microestructura. A su vez, la microestructura del metal depositado puede presentar variaciones con el procedimiento de soldadura empleado, especialmente en relación al aporte térmico. Los parámetros...

  14. Optimización de parámetros en la fabricación de cuchillas trozadoras para la casecha de caña de azúcar

    OpenAIRE

    León Sevilla, Lisys Margarita

    2010-01-01

    El siguiente trabajo evaluó dos aceros AISI 15B30 y AISI 5160 en la aplicación específica de fabricación de cuchillas trozadoras para cosecha de caña de azúcar. Se seleccionaron tratamientos térmicos para cada acero de acuerdo a una amplia revisión bibliográfica, las propiedades evaluadas posteriores a los tratamientos térmicos fueron resistencia al desgaste, resistencia al impacto y dureza. Se hicieron pruebas de laboratorio y pruebas en campo. La resistencia al desgaste abrasivo y resisten...

  15. The theory of the moon in the al-Zij al-Kamil fi-l-taalim of Ibn al-Ha'im

    OpenAIRE

    Puig i Tàrrech, Roser

    2000-01-01

    Al the beginning of Ihe thirteenth cenrury (60tH I 1204-1205) Abli Muhammad Abd al-Haqq al-Ghafiqi al-lshbiIi known as Ibn al-Ha'im composed his work entitled al-Zi] al-Kamil fi-l-Taalim in honour of the Caliph Abu Abd Allah Muhammad al-Nasir (who reigned from 1199- 1213). All we know of lbn al-Ha'im's live is that he came from Seville and that he appears to have worked in North Africa.

  16. Effect of Al coating conditions on laser weldability of Al coated steel sheet

    Institute of Scientific and Technical Information of China (English)

    Jung-Han LEE; Jong-Do KIM; Jin-Seok OH; Seo-Jeong PARK

    2009-01-01

    Al coated steel sheets with excellent heat resistance, thermal reflection, and corrosion resistance are widely used in various applications. The laser weldability of the Al coated steel sheet for full penetration welding was reported. The phenomenon caused by intermixed aluminum and behavior of aluminum in the weld were investigated. Al coated steel sheets that have various thickness and coating mass were prepared for laser welding. The effects of parameters such as welding conditions and Al coating conditions were investigated. Al content mixed in the weld after laser welding was evaluated, and then a correlation between the mixed Al and mechanical properties was investigated. The results show that the Al-rich zones which have Fe-Al intermetallic compounds are found in the weld. The intermetallic compounds cause the decreased strength of the weld.

  17. Studies on SiC(p) reinforced Al-Al sub 3 Ni eutectic matrix composites

    International Nuclear Information System (INIS)

    An investigation on processing of Al-5.69wt% Ni eutectic with SiC particulate composites is reported. The intermetallic composites are prepared by elemental powder metallurgy route and sintered at two different temperatures, i.e., 600 degree C and 620 degree C. Results show that the metal matrix was Al-Al sub 3 Ni eutectic. The phase analysis by XRD identified the presence of Al sub 3 Ni and Al as dominant phases together with silicon and Al sub 4 C sub 3 phase as minor phases. The Al sub 4 C sub 3 and Si phases are formed during sintering due to SiC-Al interface reaction. SEM micrographs also reveal the formation of microvoid surrounding the SiC particle

  18. Diana Al-Hadid: Identity and Heritage

    Science.gov (United States)

    Jungerberg, Tom; Smith, Anna; Borsh, Colleen

    2012-01-01

    Diana Al-Hadid's sculptures reflect the many locations, cultures, histories, and mythologies that have shaped her as an artist. In large-scale works which have the appearance of architectural ruins, Al-Hadid employs imagery drawn from many diverse interests including science and technology, history, and literature. She also incorporates images and…

  19. Kus on al-Zarqawi? / Aadu Hiietamm

    Index Scriptorium Estoniae

    Hiietamm, Aadu, 1954-

    2005-01-01

    Suurbritannia nädalalehe Sunday Times andmetel on Iraagi tagaotsituim mässaja, terrorivõrgustiku al Qaeda liitlane Abu-Musab al-Zarqawi pärast USA raketirünnakus haavatasaamist riigist põgenenud

  20. Als je vrienden hebt dan win je

    NARCIS (Netherlands)

    Effing, R. (Robin); Huibers, T. (Theo); Krosse, de L. (Luc)

    2010-01-01

    Als je wint, heb je vrienden’ is een Nederlandse klassieker van Herman Brood en Henny Vrienten. Hiermee werd de gevoelige snaar bloot gelegd dat pas als je hebt gewonnen je vrienden hebt. Rijen dik, echte vrienden. In de politiek werkt het andersom; je moet vrienden (stemmen) hebben, ve

  1. MOSQUE ARCHITECTURE AS A SUSTAINABLE BUILDING IN URBAN (Case Study: Al Markas Al Islamic Mosque Makassar)

    OpenAIRE

    Imriyanti Imriyanti

    2014-01-01

    Abstract Mosque Architecture is a part of Islamic architecture. Mosque should be fused with elements of nature because its function as a place to pray to God who created the universe. Al Markas Al Islamic Makassar mosque is used as a center of Islamic aspirations of the people and the government to accommodate all the activities of moslems in Makassar. Through this function, the provision of Al Markas Al Islamic mosque began from the desire of Islamic societies in Makassar, which want...

  2. High temperature creep behaviour of Al-rich Ti-Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sturm, D; Heilmaier, M; Saage, H [Otto von Guericke University Magdeburg, Institute for Materials and Joining Technology, PO Box 4120, D-39016 Magdeburg (Germany); Aguilar, J; Schmitz, G J; Drevermann, A [ACCESS e.V., Intzestrasse 5, D-52072 Aachen (Germany); Palm, M; Stein, F; Engberding, N [Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Str. 1, D-40237 Duesseldorf (Germany); Kelm, K; Irsen, S, E-mail: daniel.sturm@ovgu.d [Stiftung caesar, Electron Microscopy, Ludwig-Erhard-Allee 2, D-53175 Bonn (Germany)

    2010-07-01

    Compared to Ti-rich {gamma}-TiAl-based alloys Al-rich Ti-Al alloys offer an additional reduction of in density and a better oxidation resistance which are both due to the increased Al content. Polycrystalline material was manufactured by centrifugal casting. Microstructural characterization was carried out employing light-optical, scanning and transmission electron microscopy and XRD analyses. The high temperature creep of two binary alloys, namely Al{sub 60}Ti{sub 40} and Al{sub 62}Ti{sub 38} was comparatively assessed with compression tests at constant true stress in a temperature range between 1173 and 1323 K in air. The alloys were tested in the cast condition (containing various amounts of the metastable phases Al{sub 5}Ti{sub 3} and h-Al{sub 2}Ti) and after annealing at 1223 K for 200 h which produced (thermodynamically stable) lamellar {gamma}-TiAl + r-Al{sub 2}Ti microstructures. In general, already the as-cast alloys exhibit a reasonable creep resistance at 1173 K. Compared with Al{sub 60}Ti{sub 40}, both, the as-cast and the annealed Al{sub 62}Ti{sub 38} alloy exhibit better creep resistance up to 1323 K which can be rationalized by the reduced lamella spacing. The assessment of creep tests conducted at identical stress levels and varying temperatures yielded apparent activation energies for creep of Q = 430 kJ/mol for the annealed Al{sub 60}Ti{sub 40} alloy and of Q = 383 kJ/mol for the annealed Al{sub 62}Ti{sub 38} material. The latter coincides well with that of Al diffusion in {gamma}-TiAl, whereas the former can be rationalized by the instability of the microstructure containing metastable phases.

  3. Corrosion Studies of 2195 Al-Li Alloy and 2219 Al Alloy with Differing Surface Treatments

    Science.gov (United States)

    Danford, M. D.; Mendrek, M. J.

    1998-01-01

    Corrosion studies of 2195 Al-Li and 2219 Al alloys have been conducted using the scanning reference electrode technique (SRET) and the polarization resistance (PR) technique. The SRET was used to study corrosion mechanisms, while corrosion rate measurements were studied with the PR technique. Plates of Al203 blasted, soda blasted and conversion coated 2219 Al were coated with Deft primer and the corrosion rates studied with the EIS technique. Results from all of these studies are presented.

  4. Assessment of the al corner of the ternary Al-Fe-Si system

    OpenAIRE

    Eleno, Luiz; Vezelý, Josef; Sundman, Bo; Cieslar, Miroslav; Lacaze, Jacques

    2010-01-01

    The present work provides a review of the information available on the Al-rich corner of the Al-Fe-Si system as well as a CALPHAD type assessment making use of the COST 507 database as a starting point. The description of the intermetallic compounds has been modified to account for substitution of Al and Si in the ternary Al-Fe-Si system and to take new experimental information into account.

  5. The annealing behaviour of hydrogen implanted into Al metal and Al-Si alloy

    International Nuclear Information System (INIS)

    In the present experiment, we have investigated how defects and elements as additive play a role as trap site by observing the annealing behaviour of hydrogen implanted into Al and Al-Si alloy. It was found that hydrogen is trapped as molecules in grain boundaries of Si in Al. (author)

  6. O estresse na pesquisa epidemiológica: o desgaste dos modelos de explicação coletiva do processo saúde-doença Stress in epidemilogical research: the wear of collecive models of explanation of the health-illness process

    Directory of Open Access Journals (Sweden)

    Luis David Castiel

    2005-01-01

    Full Text Available São enfocadas as dificuldades do instrumento epidemiológico em lidar com as questões postas pelos problemas contemporâneos de saúde, nos quais o conceito de estresse encontrará ampla difusão. Assim, apresenta-se uma discussão sobre o arcabouço teórico-conceitual da teoria do estresse e seus desdobramentos. Além disso, são assinaladas as limitações do método e dos modelos epidemiológicos disponíveis, ao abordarem: 1 manifestações cuja previsibilidade não é delimitável; 2 fenômenos que se encontram em níveis hierárquicos distintos. Nesses casos, a teorização subjacente à noção de risco, utilizada para explicar o adoecer referido ao nível individual, mostra-se insuficiente. A complexidade do processo saúde-doença demanda outro paradigma epistêmico que permita ao sujeito da ciência epidemiológica desenvolver outras formas de demarcar e compreender seu objeto.The article focuses on the difficulties the epidemiological instrument faces when dealing wih questions posed by contemporary health problems, in which the concept of stress finds broad diffusion. Thus there is a discussion about the theoretical-concepual framework of the theory of stress and its developments. Besides, the text points out the limitation of the method and of the available epidemiological models when they talk about: 1 manifestations whose predicability cannot be delimited; 2 phenomena placed in different hierarchic levels. In such cases, the theorization underlying the notion of risk, used to explain sickliness at the individual level proves to be insufficient. The complexity of the health-illness process demands another epistemological paradigm which allows the subject of the epidemiological research develop other ways of demarcating and understanding its object.

  7. Shadow evaporation of epitaxial Al/Al2O3/Al tunnel junctions on sapphire utilizing an inorganic bilayer mask

    OpenAIRE

    Welander, Paul B.; Bolkhovsky, Vladimir; Weir, Terence J.; Gouker, Mark A.; Oliver, William D.

    2012-01-01

    This letter describes a new inorganic shadow mask that has been employed for the evaporation of all-epitaxial Al/Al2O3/Al superconducting tunnel junctions. Organic resists that are commonly used for shadow masks and other lift-off processes are not compatible with ultra-high vacuum deposition systems, and they can break down at even moderately elevated temperatures. The inorganic mask described herein does not suffer these same shortcomings. It was fabricated from a Ge/Nb bilayer, comprising ...

  8. Japanese version of the ALS-FTD-Questionnaire (ALS-FTD-Q-J).

    Science.gov (United States)

    Watanabe, Yasuhiro; Beeldman, Emma; Raaphorst, Joost; Izumi, Yuishin; Yoshino, Hiide; Masuda, Michihito; Atsuta, Naoki; Ito, Satoru; Adachi, Tadashi; Adachi, Yoshiki; Yokota, Osamu; Oda, Masaya; Hanashima, Ritsuko; Ogino, Mieko; Ichikawa, Hiroo; Hasegawa, Kazuko; Kimura, Hideki; Shimizu, Toshio; Aiba, Ikuko; Yabe, Hayato; Kanba, Makoto; Kusumi, Kimiyoshi; Aoki, Tetsuya; Hiroe, Yu; Watanabe, Hirohisa; Nishiyama, Kazutoshi; Nomoto, Masahiro; Sobue, Gen; Nakashima, Kenji

    2016-08-15

    Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) share common clinical, genetic and neuropathological features. Some ALS patients have behavioral/personality changes, which could result in significant obstacles in the care provided by family members and caregivers. An easy screening tool would contribute greatly to the evaluation of these symptoms. We translated the ALS-FTD-Questionnaire, developed in the Netherlands, into Japanese (ALS-FTD-Q-J) and examined the clinimetric properties (internal consistency, construct and clinical validity). Patients with ALS and/or behavioral variant FTD (bvFTD) were evaluated alongside healthy controls in this multicenter study. All ALS patients, regardless of bvFTD status, were further evaluated by the frontal behavioral inventory (FBI) and for frontal/executive function, cognition, anxiety/depression, and motor functions. Data from 146 subjects were analyzed: ALS (92), ALS-bvFTD (6), bvFTD (16), and healthy controls (32). The internal consistency of the ALS-FTD-Q-J was good (Cronbach α=0.92). The ALS-FTD-Q-J showed construct validity as it exhibited a high correlation with the FBI (r=0.79). However, correlations were moderate with anxiety/depression and low with cognitive scales, in contrast to the original report, i.e. a moderate correlation with cognition and a low correlation with anxiety/depression. The ALS-FTD-Q-J discriminated ALS patients from (ALS-)bvFTD patients and controls. Thus, the ALS-FTD-Q-J is useful for evaluating Japanese ALS/FTD patients. PMID:27423564

  9. DISTINGSI DAN DIASPORA TASAWUF ABÛ AL-HASAN AL-SHÂDHILÎ

    OpenAIRE

    Saifulah Saifulah

    2015-01-01

    This article discusses Shâdhilîyah, one of the most recognized sufi orders, which possesses quite distinct aspects in the conception of its mystical teachings. This sufi order was founded by Abû al-H}asan al-Shâdhilî, a sufi who has moderate and open view of the worldly life. Al-Shâdhilî explained about how a sufi should behave towards and deal with worldly matters. Although al-Shâdhilî asserted that a person who practice tasawwuf should not pay more adoration on the worldly matters (hubb al-...

  10. The influence of Al content on the Zener relaxation of Fe-Al alloys

    International Nuclear Information System (INIS)

    The effect of Al content on the Zener relaxation peak of annealed Fe-Al alloys has been investigated using a computer-controlled automatic inverted torsion pendulum through the method of free decay and forced vibration. It has been shown that alloys with medium Al contents show strong relaxation while lower or higher Al contents lead to relatively weak Zener relaxation peaks. The Zener relaxation in Fe-Al alloys originates from the next-nearest-neighbour atom pairs and their interaction rather than the nearest-neighbour atom pairs. The latter may not produce Zener relaxation because of the ordered structure, which suppresses Zener relaxation

  11. Magnetism in bcc Fe-Al alloy

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M.E. [Sultan Qaboos Univ., Al-Khod (Oman). Dept. of Phys.; Yousif, A.A. [Sultan Qaboos Univ., Al-Khod (Oman). Dept. of Phys.

    1994-11-01

    The magnetic moment {mu}, hyperfine field B{sub hf} and isomer shift IS at the Fe site in bcc Fe-Al alloys were calculated from first principle. Contrary to the belief that Al atoms reside in the iron lattice as magnetic holes, it was found that the local magnetic moment of Fe is decreased when Al is at a nearest neighbour site (NN), while it increases if Al is at a next-nearest neighbour site (NNN). Consequently, the average {mu} per Fe atom was found to be, initially, independent of Al content. Assuming a linear dependence of {mu}{sub Fe} on the number of Al atoms at NN and NNN sites, we calculated the average {mu}, which was found to agree with experimental results of cold worked alloys for disordered Fe-Al alloy. On the other hand, antiferromagnetic coupling appears in the CsCl ordered structures. The average B{sub hf} was also calculated and compared to experimental data and the trends in the IS are considered. (orig.)

  12. Comparative study on interface and bulk charges in AlGaN/GaN metal-insulator-semiconductor heterostructures with Al2O3, AlN, and Al2O3/AlN laminated dielectrics

    Science.gov (United States)

    Zhu, Jie-Jie; Ma, Xiao-Hua; Chen, Wei-Wei; Hou, Bin; Xie, Yong; Hao, Yue

    2016-05-01

    In this paper, the interface and bulk charges in AlGaN/GaN metal-insulator-semiconductor (MIS) heterostructures with AlN, Al2O3, and Al2O3/AlN laminated dielectrics were studied. In situ plasma pretreatment resulted negligible interface trap states and voltage hysteresis. The fixed charge density at Al2O3/AlN (or Al2O3/barrier) interface was estimated to be 1.66 × 1013 cm-2 by using flat-band voltage shift, and the oxide bulk charge concentration was 2.86 × 1017 cm-3. The interface charge density at other interfaces were at the order of 1011 cm-2. Simulation results using the above charge density/concentration indicated that Al2O3/AlN interface fixed charges dominated the dielectric-related voltage shift in AlGaN/GaN MIS heterostructures, which caused a large voltage shift of -3 V with 10 nm Al2O3 thickness, while the flat-band voltage variety resulting from other types of charges was within 0.1 V.

  13. Fuel consumption of a tractor in function of wear, of ballasting and tire inflation pressure Consumo de combustível de um trator em função do desgaste, da lastragem e pressão de inflação dos pneus

    Directory of Open Access Journals (Sweden)

    Roger T. Spagnolo

    2012-02-01

    Full Text Available When using appropriate inflation pressures and load capacity (ballast, it may obtain a higher yield and prolongation of the life of the tire, besides it may minimize the problems of loss of traction, increased slippage and fuel consumption. This study aimed to evaluate the fuel consumption of a tractor operating with new and worn tires in three conditions of ballasting and three inflation pressures, when driving on compacted soil with vegetation cover. The experiment was conducted at the experimental unit from the Department of Animal Science, Federal University of Lavras, state of Minas Gerais, Brazil, in an agricultural soil compacted by cattle trampling and with vegetation cover. It was used a tractor 4x2 with front wheel assist, of a 65.62 kW engine power. The tires were of R1 type, diagonal (front: 12.4 to 24; and rear: 18.4 to 30, the average height of the clutches of the new tires were 0.3 and 0.35 m for front and rear tires, respectively, and for the worn tires were 0.018 and 0.0045 m, for the front and the rear tires, respectively. The results showed advantages for the tractor equipped with new tires.Ao se utilizar pressão de inflação e a capacidade de carga (lastro adequadas, pode-se obter um rendimento maior e um prolongamento da vida útil do pneu; além disso, minimizam-se os problemas de perda de tração, aumento de patinhagem e consumo de combustível. O presente trabalho teve como objetivo avaliar o consumo de combustível de um trator agrícola operando com pneus novos e desgastados, em três condições de lastragem e três pressões de inflação, ao trafegar sobre solo compactado com cobertura vegetal. O experimento foi realizado na unidade experimental do Departamento de Zootecnia da Universidade Federal de Lavras, Lavras-MG, em um solo compactado pelo pisoteio de bovinos e com cobertura vegetal. Utilizou-se um trator 4x2 TDA, com potência de 65,62 kW no motor. Os pneus foram do tipo R1, diagonal (dianteiros: 12

  14. Tracing Al Shabaab’s Decision to Cooperate with Al Qaeda in Somalia (2008

    Directory of Open Access Journals (Sweden)

    Adlini Ilma Ghaisany Sjah

    2014-02-01

    Full Text Available 'Al Shabaab, a Somali insurgent with predominantly nationalistic causes (alongside transnational [global Jihad] and Islamic goals made the choice to fight on behalf of Al Qaeda in 2008. The decision to do so contrasted with Al Shabaab’s previous behaviour of actively denying cooperation and distancing itself from Al Qaeda. This study aims to uncover factors that contributed to Al Shabaab’s decision through the use of process-tracing. The results show that Al Shabaab’s declaration of cooperation with Al Qaeda in August 2008 was brought about by a series of events that traced back to four factors: public reactions to the implementation of a Salafi ideology, the shift to a radical leadership, Al Shabaab’s inability to maintain stability in areas under its control and its increasing attacks by Al Shabaab on the Somali public. Al Shabaab pursued cooperation with Al Qaeda after realizing that their nationalistic preference was no longer achievable in the near future.' ' '

  15. Optical characterization of Al- and N-polar AlN waveguides for integrated optics

    Science.gov (United States)

    Rigler, Martin; Buh, Jože; Hoffmann, Marc P.; Kirste, Ronny; Bobea, Milena; Mita, Seiji; Gerhold, Michael D.; Collazo, Ramon; Sitar, Zlatko; Zgonik, Marko

    2015-04-01

    Dispersion of the extraordinary and ordinary refractive indices of Al- and N-polar AlN waveguides is measured by multiple angle-of-incidence and spectroscopic ellipsometry techniques. The polarity-controlled AlN layers are grown by metal-organic chemical vapor deposition on (0001)-sapphire substrates. Taking into consideration the different surface morphologies of the Al- and N-polar AlN waveguides, we propose two optical models to describe the measured ellipsometry data. The results indicate that there is no difference between the refractive indices of the AlN grown in opposite directions, which confirms the potential of the AlN lateral polar structures for use in nonlinear optical applications based on quasi phase matching.

  16. Oxidation of Al2O3 continuous fiber-reinforced/NiAl composites

    Science.gov (United States)

    Doychak, J.; Nesbitt, J. A.; Noebe, R. D.; Bowman, R. R.

    1992-01-01

    The 1200 C and 1300 C isothermal and cyclic oxidation behavior of Al2O3 continuous fiber-reinforced/NiAl composites were studied. Oxidation resulted in formation of Al2O3 external scales in a similar manner as scales formed on monolithic NiAl. The isothermal oxidation of an Al2O3/NiAl composite resulted in oxidation of the matrix along the fiber/matrix interface near the fiber ends. This oxide acted as a wedge between the fiber and the matrix, and, under cyclic oxidation conditions, led to further oxidation along the fiber lengths and eventual cracking of the composite. The oxidation behavior of composites in which the Al2O3 fibers were sputter coated with nickel prior to processing was much more severe. This was attributed to open channels around the fibers which formed during processing, most likely as a result of the diffusion of the nickel coating into the matrix.

  17. A Rechargeable Al/S Battery with an Ionic-Liquid Electrolyte.

    Science.gov (United States)

    Gao, Tao; Li, Xiaogang; Wang, Xiwen; Hu, Junkai; Han, Fudong; Fan, Xiulin; Suo, Liumin; Pearse, Alex J; Lee, Sang Bok; Rubloff, Gary W; Gaskell, Karen J; Noked, Malachi; Wang, Chunsheng

    2016-08-16

    Aluminum metal is a promising anode material for next generation rechargeable batteries owing to its abundance, potentially dendrite-free deposition, and high capacity. The rechargeable aluminum/sulfur (Al/S) battery is of great interest owing to its high energy density (1340 Wh kg(-1) ) and low cost. However, Al/S chemistry suffers poor reversibility owing to the difficulty of oxidizing AlSx . Herein, we demonstrate the first reversible Al/S battery in ionic-liquid electrolyte with an activated carbon cloth/sulfur composite cathode. Electrochemical, spectroscopic, and microscopic results suggest that sulfur undergoes a solid-state conversion reaction in the electrolyte. Kinetics analysis identifies that the slow solid-state sulfur conversion reaction causes large voltage hysteresis and limits the energy efficiency of the system. PMID:27417442

  18. Magnetic properties and crystal structure of HoNiAl and UNiAl hydrides

    International Nuclear Information System (INIS)

    The effect of hydrogenation on the magnetic properties and crystal structure of 4f and 5f intermetallics was studied on HoNiAlH2.0, UNiAlH2.3 and UNiAlD2.1. The incorporation of hydrogen into HoNiAl leads to a decrease of the magnetic ordering temperature from 13 to 6 K, while it increases from 19 K to values in the range 90-100 K in the UNiAl-H system. The crystal lattices of all compounds are anisotropically expanded. Moreover, the crystal symmetry is lowered to orthorhombic in HoNiAlH2.0, but remains hexagonal for UNiAlH(D)x. Three different deuterium positions were found for both compounds. (c) 2000 American Institute of Physics

  19. AlON粉体的合成%Synthesis of AlON Powder

    Institute of Scientific and Technical Information of China (English)

    赵小军; 茹红强; 张宁; 孙有政

    2009-01-01

    以α-Al_2O_3和AlN为原料,利用高温固相反应在氮气气氛下常压合成了AlON粉体.研究了成分配比、合成温度、保温时间对合成AlON粉体含量的影响,并通过热分析测试了合成过程热流和质量的变化.结果表明,当原料Al_2O_3和AlN的质量比为81:18、合成工艺为1750 ℃, 2 h时,得到AlON相的含量达到95%以上.

  20. Adherencia al tratamiento en la esquizofrenia

    OpenAIRE

    Ruiz Manrique, Olatz

    2015-01-01

    [Es]La adherencia al tratamiento es un problema real en los pacientes esquizofrénicos, que dificulta su inserción en la sociedad y puede ocasionarles graves repercusiones médicas. Por ello, el objetivo de esta revisión es valorar la eficacia de las intervenciones psicoeducacionales con la ayuda del personal sanitario y/o familiares, en la adherencia al tratamiento de los pacientes esquizofrénicos. Se realizó una revisión sistemática para dar respuesta al objetivo planteado, analizando las res...

  1. Amyotrofinen lateraaliskleroosi (ALS) ja potilaan ohjaus

    OpenAIRE

    Korkeaniemi, Lotta; Kaakinen, Leena

    2009-01-01

    Saimme opinnäytetyömme toimeksiantona Hyvinkään sairaalan sisätautien vuodeosastolta. Tavoitteena oli luoda ALS potilaille potilasopas trakeostomiasta ja sen kanssa elämisestä. Oppaan tarkoituksena on auttaa ALS potilaita päättämään, kuinka pitkälle he haluavat viedä heidän hengitystukihoitonsa. Samalla hoitajat saavat tuki materiaalia, jonka avulla he voivat käydä läpi hengitystukihoitoja ja erityisesti trakeostomiaan liittyviä asioita. ALS eli amyotrofinen lateraaliskleroosi on tahdona...

  2. Suspected variables among Al Sufi stars.

    Science.gov (United States)

    Hoffleit, D.

    In the tenth century Al Sufi compiled a catalogue of some 1100 stars. J.E. Gore, around 1900, wrote extensively on the magnitudes of these stars. On intercomparing them with a few other catalogues, Gore surmised that some 38 stars appeared to show secular variations. Here all the Al Sufi magnitudes have been compared with numerous additional sources, but smooth secular variations are not substantiated although some stars seem to have undergone comparatively sudden changes after about 1600. About 70 Al Sufi stars are now named or suscpected variable stars, but nearly all with amplitudes under 0.3 V.

  3. TAFSIR SEMANTIK TERHADAP SURAT AL-KAFIRUN

    Directory of Open Access Journals (Sweden)

    Imam Muslimin

    2011-10-01

    Full Text Available The problems about the reading of al-Qur’an is always interesting to be discussed, in which the use of Arabic includes sound or ‘nash’ is acrucial factor to understand the implicit meaning of the Arabic-written texts. Al-Qur’an discusses problem based on the society’s culture. Al-Kafirun discusses not only about the normative theology but more about sociological contexts in which it tends to show transparency, fight against fanaticism and regionalism. And all of the will bring to the first process of the making of the text meaning to the situational context that creates them.

  4. Linija za transport Al-polizdelkov

    OpenAIRE

    Capl, Žiga

    2012-01-01

    V diplomski nalogi je predstavljena linija za transport Al-polizdelkov, ki je sestavljena iz dveh verižnih transporterjev in dveh manipulatorjev. Omenjeni transporterji morajo transportirati Al-polizdelke od sprejemnega mesta do poti v stiskalnico. V okviru diplomskega dela smo opravili analizo obstoječega ogrodja z naklonom, linije za transport Al-polizdelkov in podali možne rešitve za novo učinkovitejšo izvedbo. Na podlagi tehnično-tehnoloških zahtev smo izbrali najprimernejšo rešitev i...

  5. Characterization of AlInN/AlN/GaN Heterostructures with Different AlN Buffer Thickness

    Science.gov (United States)

    Çörekçi, S.; Dugan, S.; Öztürk, M. K.; Çetin, S. Ş.; Çakmak, M.; Özçelik, S.; Özbay, E.

    2016-07-01

    Two AlInN/AlN/GaN heterostructures with 280-nm- and 400-nm-thick AlN buffer grown on sapphire substrates by metal-organic chemical vapor deposition (MOCVD) have been investigated by x-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) and Hall-effect measurements. The symmetric (0002) plane with respect to the asymmetric (10bar{1}2) plane in the 280-nm-thick AlN buffer has a higher crystal quality, as opposed to the 400-nm-thick buffer. The thinner buffer improves the crystallinity of both (0002) and (10bar{1}2) planes in the GaN layers, it also provides a sizeable reduction in dislocation density of GaN. Furthermore, the lower buffer thickness leads to a good quality surface with an rms roughness of 0.30 nm and a dark spot density of 4.0 × 108 cm-2. The optical and transport properties of the AlInN/AlN/GaN structure with the relatively thin buffer are compatible with the enhancement in its structural quality, as verified by XRD and AFM results.

  6. Evolution of ConAl clusters and chemisorption of hydrogen on ConAl clusters

    International Nuclear Information System (INIS)

    The growth behavior of ConAl (n = 1–15) and the chemisorptions of hydrogen on the ground state geometries have been studied using the density functional theory (DFT) within the generalized gradient approximation (GGA). The growth pattern for ConAl is Al-substituted Con+1 clusters, and it keeps the similar frameworks of the most stable Con+1 clusters except for n = 2, 3, and 6. The Al atom substitutes the surface atom of the Con+1 clusters for n ≤ 13. Starting from n = 14, the Al atom completely falls into the center of the Co-frame. The dissociation energy, the second-order energy differences, and the HOMO–LUMO gaps indicate that the magic numbers of the calculated ConAl clusters are 7, 9, and 13, corresponding to the high symmetrical structures. To my knowledge, this is the first time that a systematic study of chemisorption of hydrogen on cobalt aluminum clusters. The twofold bridge site is identified to be the most favorable chemisorptions site for one hydrogen adsorption on ConAl (n = 1–6, 8, 10), and two hydrogen adsorption on ConAl (n = 1–7), while threefold hollow site is preferred for one hydrogen adsorption on ConAl (n = 7, 9, 11–15) and two hydrogen adsorption on ConAl (n = 8–10, 12–15) clusters. The ground state structure of two hydrogen adsorption on Co11Al is exceptional. In general, the binding energy of both H and 2H of ConAl (n = 1–12) is found to increase with the cluster size. And the result shows that large binding energies of the hydrogen atoms and large fragmentation energies for Co11AlH and Co12AlH make these species behaving like magic clusters.

  7. Wali Allah menurut al-Hakim al-Tirmidzi dan Ibnu Taimiyyah

    Directory of Open Access Journals (Sweden)

    Lilik Mursito

    2015-12-01

    Full Text Available The discussion about wali presented in the early time on the hand of al-Hakim al Tirmidzi, which reaps number of responses from Muslim scholar because of his misleading. One of them is Ibn Taimiyyah. Al-Hakim and Ibn Taymiyyah have their own view about wali with several distinctions. In the definition of wali, al-Hakim al-Tirmidzi used more general language than Ibn Taimiyyah, as well as characteristics, how to be wali, the classification, concept of karamah, and the concept of khatm al-awliya’. According to writer, al-Hakim al-Tirmidzi’s view about wali able to deepen our understanding about Sufism, meanwhile Ibn Taimiyyah’s view will led us to comprehend Sufism from modernist point of view. This paper conclude that: both of figures seen that wali of Allah are the servants submissive and obedient in running His command; according to al-Hakim al Tirmidzi, degree of wali can be reached purely from Allah’s bounty and the effort of servants themselves, while Ibn Taimiyyah seen that the degree could be reached in the way of faith and piety of the servant; al-Hakim al-Tirmidzi seen that karamah is the most urgent for wali, while Ibn Taimiyyah did not; al-Hakim al-Tirmidzi utilized the quality of deeds to measure the best people and purity of heart to measure the best wali, while Ibn Taymiyyah utilized the quality of deeds as the assessment standard to measure best people and wali.

  8. In Situ Fabrication of AlN Coating by Reactive Plasma Spraying of Al/AlN Powder

    Directory of Open Access Journals (Sweden)

    Mohammed Shahien

    2011-10-01

    Full Text Available Reactive plasma spraying is a promising technology for the in situ formation of aluminum nitride (AlN coatings. Recently, it became possible to fabricate cubic-AlN-(c-AlN based coatings through reactive plasma spraying of Al powder in an ambient atmosphere. However, it was difficult to fabricate a coating with high AlN content and suitable thickness due to the coalescence of the Al particles. In this study, the influence of using AlN additive (h-AlN to increase the AlN content of the coating and improve the reaction process was investigated. The simple mixing of Al and AlN powders was not suitable for fabricating AlN coatings through reactive plasma spraying. However, it was possible to prepare a homogenously mixed, agglomerated and dispersed Al/AlN mixture (which enabled in-flight interaction between the powder and the surrounding plasma by wet-mixing in a planetary mill. Increasing the AlN content in the mixture prevented coalescence and increased the nitride content gradually. Using 30 to 40 wt% AlN was sufficient to fabricate a thick (more than 200 µm AlN coating with high hardness (approximately 1000 Hv. The AlN additive prevented the coalescence of Al metal and enhanced post-deposition nitriding through N2 plasma irradiation by allowing the nitriding species in the plasma to impinge on a larger Al surface area. Using AlN as a feedstock additive was found to be a suitable method for fabricating AlN coatings by reactive plasma spraying. Moreover, the fabricated coatings consist of hexagonal (h-AlN, c-AlN (rock-salt and zinc-blend phases and certain oxides: aluminum oxynitride (Al5O6N, cubic sphalerite Al23O27N5 (ALON and Al2O3. The zinc-blend c-AlN and ALON phases were attributed to the transformation of the h-AlN feedstock during the reactive plasma spraying. Thus, the zinc-blend c-Al

  9. PEMBARUAN MASLA╩AH DALAM MAQĀ╤ID AL- SHARĪ‘AH: TELAAH HUMANISTIS TENTANG AL-KULLIYYĀT AL-KHAMSAH

    Directory of Open Access Journals (Sweden)

    Zaenuddin Mansyur

    2015-03-01

    Full Text Available Abstract:   In order to answer a variety of issues faced by human being in the current era, such as human rights abuses, social disintegration, and terrorism, the renewal of Islamic law in the level of theoretical and practical aspects is very urgent. This paper aims to examine one of the Islamic legal reform efforts, namely to build a more technical understanding of the concept of ma╣la╪ah contained in the maqā╣īd sharī‘ah, called the al-kulliyat al-khamsah. Therefore, the concept of ma╣la╪ah in ╪if╬ al-dīn is technically defined as al-╪urriyah al-i‘tiqād (freedom of religion and schools; in ╪if╬ al-nafs as al-karamat al-insān (human being breeding; in ╪if╬ al-nasl as ╪if╬ al-usrah (wholeness and harmony of the family; in ╪if╬ al-māl as al-ta╨ammun al-insān (social solidarity , and in ╪if╬ al-‘aql as al-╪uqūq as al-tarbiyāt (increasing human resources quality.Abstrak: Demi menjawab aneka persoalan zaman yang dihadapi manusia era sekarang, seperti penyelewengan terhadap HAM, disintegrasi sosial, dan terorisme, maka pembaharuan hukum Islam dalam tataran teoretis dan praktis urgen dilakukan. Tulisan ini bertujuan untuk mengkaji salah satu upaya pembaruan hukum Islam, yaitu membangun pemahaman yang lebih teknis terhadap konsep ma╣la╪ah yang terkandung dalam maqā╣īd sharī‘ah, yang disebut dengan al-kulliyāt al-khamsah. Oleh karena itu, konsep ma╣la╪ah dalam ╪if╬u al-dīn secara teknis dimaknai sebagai ╪urriyah al-i‘tiqād (kebebasan untuk beragama dan beraliran; dalam ╪if╬u al-nafs sebagai al-karāmāt al-insān (pemuliaan kemanusiaan; dalam ╪if╬u al-nasl sebagai ╪if╬u al-usrah (keutuhan dan keharmonisan keluarga; dalam ╪if╬u al-māl sebagai al-ta╨ammun al-insān (solidaritas sosial; dan dalam ╪if╬u al-‘aql sebagai al-╪uqūq al-tarbiyāt (peningkatan sumber daya manusia.

  10. Pesticides Linked to Raised Risk of ALS

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_158737.html Pesticides Linked to Raised Risk of ALS One toxin ... MONDAY, May 9, 2016 (HealthDay News) -- Exposure to pesticides and other chemicals may increase the risk for ...

  11. Pesticides Linked to Raised Risk of ALS

    Science.gov (United States)

    ... nlm.nih.gov/medlineplus/news/fullstory_158737.html Pesticides Linked to Raised Risk of ALS One toxin ... MONDAY, May 9, 2016 (HealthDay News) -- Exposure to pesticides and other chemicals may increase the risk for ...

  12. Stem Cells Deemed Safe for ALS Patients

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_159627.html Stem Cells Deemed Safe for ALS Patients But further research needed to see if injections into spine would provide any benefit, researchers say To use the sharing features on ...

  13. ALS: Recent Developments from Genetics Studies.

    Science.gov (United States)

    Therrien, Martine; Dion, Patrick A; Rouleau, Guy A

    2016-06-01

    Amyotrophic lateral sclerosis (ALS) is a fatal disorder that is characterized by a progressive degeneration of the upper and lower motor neurons. Most cases appear to be sporadic, but 5-10 % of cases have a family history of the disease. High-throughput DNA sequencing and related genomic capture tools are methodological advances which have rapidly contributed to an acceleration in the discovery of genetic risk factors for both familial and sporadic ALS. It is interesting to note that as the number of ALS genes grows, many of the proteins they encode are in shared intracellular processes. This review will summarize some of the recent advances and gene discovery made in ALS. PMID:27113253

  14. Het Nederlandse bos als vorm van bodemgebruik

    NARCIS (Netherlands)

    Slangen, L.H.G.; Boven, van B.

    1983-01-01

    Behandeling van de oppervlakte en verdeling van het bos en de veranderingen die hierin zijn opgetreden, met de bedrijfsgrootte-struktuur als belangrijke invalshoek daarbij; de rol van de overheid: doeleinden, instrumenten en effekten van het beleid

  15. INTEGRACION DE UNA CELULA FLEXIBLE DE MECANIZADO, DE TIPO DOCENTE INTEGRATION OF A EDUCATIONAL FLEXIBLE MANUFACTURING CELL

    OpenAIRE

    Abraham Farias F; Luis Moraga G; Ambrosio Martinich L

    2007-01-01

    Este trabajo trata sobre la integración de una célula flexible de mecanizado de tipo docente, compuesta por una fresadora didáctica CNC, marca Denford, un brazo robótico articulado de seis ejes, modelo Scorbot -ER Vplus  y un riel deslizante; todos pertenecientes al Laboratorio de Manufactura Integrada por Computador, de la Escuela de Ingeniería Mecánica de la Universidad de Talca. Las tareas que realiza esta célula flexible son controladas por un PC director  a través de un  programa, utiliz...

  16. In situ (Al3Zr + Al2O3np)/2024Al metal matrix composite with novel reinforcement distributions fabricated by reaction hot pressing

    International Nuclear Information System (INIS)

    Highlights: •(Al3Zr + Al2O3np)/2024Al MMC with a novel network distribution was tailored. •Al3Zr and Al2O3np were in situ synthesized at 740 °C using the 2024Al–ZrO2 system. •The effect of sintering parameters on Al3Zr morphology was investigated. •Influence of Al3Zr morphology on tensile properties of the composite was studied. -- Abstract: In situ hybrid (Al3Zr + Al2O3np)/2024Al metal matrix composites with unique controlled reinforcement distributions were fabricated using low energy ball milling and reactive hot pressing. The reaction system between 2024Al and ZrO2 was studied using differential thermal analysis (DTA). In situ formed aluminium oxide (Al2O3) and zirconium tri-aluminide (Al3Zr) with varying morphology and sizes were produced under different fabricating conditions. Al3Zr with varying morphologies such as particle, plate and flakes were observed. With a total 10 vol.% of reinforcements, the composite containing a three-dimensional network of closely spaced in situ synthesized Al3Zr and Al2O3 particles had a YS of 175 MPa and a UTS of 261 MPa, effectively strengthening the 2024Al matrix. The effect of different sintering conditions on the microstructure and tensile properties of the composite was systematically investigated

  17. Hans Freudenthal als docent en collega

    OpenAIRE

    Verhulst, Ferdinand; Verhoef, Nellie

    2010-01-01

    Hans Freudenthal heeft een belangrijke invloed gehad op de ontwikkeling van het basiswiskundeonderwijs. Niet minder belangrijk was zijn activiteit als docent en onderzoeker gedurende tientallen jaren op het Mathematisch Instituut van de Universiteit Utrecht. Hoe waren toen zijn ideeën over onderwijs, hoe was hij als collega en hoe waren zijn colleges? Nellie Verhoef en Ferdinand Verhulst interviewden voormalige collega’s en studenten van Freudenthal.

  18. Effects of Al substitution on goethite formation

    OpenAIRE

    Premoli, Alessandra Maria; Melis, Pietro; Gessa, Carlo Emanuele; Deiana, Salvatore Andrea

    1984-01-01

    Goethites containing up to 32.7 mole % Al were synthesized and characterized through diffractometry, spectrometry, DSC and chemical techniques. Results indicate that crystal growth was favoured or hindered depending on the percentage of aluminum incorporated into the structure. Goethites to which 5-10 mole % Al were initially added crystallized best, as shown by the highest crystallite dimensions calculated from X-ray and Mössbauer analyses, and by the lowest surface areas values. Over suc...

  19. Anerkennung als Voraussetzung gesellschaftlicher und unternehmerischer Teilhabe

    OpenAIRE

    Eurich, Johannes; Brink, Alexander

    2003-01-01

    Angesichts des neuen Phänomens der sozialen Exklusion wird soziale Gerechtigkeit nicht mehr nur über die Verteilung von Gütern hergestellt, vielmehr spielt auch die Ebene der Partizipation eine Rolle. Anerkennung ist eine Grundvoraussetzung für Partizipation. Die Verfasser diskutieren Fragen der Unternehmensethik auf der Dimension der Anerkennung. Sie votieren für ein normatives Stakeholder-Management als freiwillige Verpflichtung, das auch strategischen Anforderungen gerecht werden kann. Als...

  20. Information als Gegenstand von Informationskompetenz. Eine Begriffsanalyse

    OpenAIRE

    Ingold, Marianne

    2011-01-01

    Der Informationsbegriff als zentraler Gegenstand von Informationskompetenz wird in der bibliothekarischen Diskussion in der Regel nicht explizit thematisiert, sondern lässt sich aus Fachliteratur und Bibliothekspraxis nur implizit erschließen. Eine theoretische Beschäftigung mit dem Informationsbegriff ist jedoch unabdingbar, soll das Konzept "Informationskompetenz" auch außerhalb des bibliothekarischen Kontextes verständlich und nutzbar gemacht werden. Im vorliegenden Text, der sich als B...

  1. Plasma nitriding of Al 99.5

    OpenAIRE

    Chen, H. -Y; Stock, H.-R.; Mayr, P.

    1993-01-01

    Aluminium nitride (AlN) is a very interesting ceramic because of its combination of properties such as high thermal stability, high hardness and an unusual combination of high thermal and low electrical conductivity. But it is very difficulty to obtain an AlN layer on the aluminium substrates by thermochemical nitriding process. Since a thin film of aluminium oxide existing on the surface of every aluminium substrate prevents the nitrogen atoms from diffusing into the aluminium lattice. Howev...

  2. Communication Support for People with ALS

    OpenAIRE

    David Beukelman; Susan Fager; Amy Nordness

    2011-01-01

    Almost all people with amyotrophic lateral sclerosis (ALS) experience a motor speech disorder, such as dysarthria, as the disease progresses. At some point, 80 to 9 5 % of people with ALS are unable to meet their daily communication needs using natural speech. Unfortunately, once intelligibility begins to decrease, speech performance often deteriorates so rapidly that there is little time to implement an appropriate augmentative and alternative communication (AAC) intervention; therefore, app...

  3. Performance of the ALS injection system

    International Nuclear Information System (INIS)

    The authors started commissioning the Advanced Light Source (ALS) storage ring on January 11, 1993. The stored beam reached 60 mA on March 24, 1993 and 407 mA on April 9, 1993. The fast pace of storage ring commissioning can be attributed partially to the robust injection system. In this paper they describe the operating characteristics of the ALS injection system

  4. Del latín al rumano

    Directory of Open Access Journals (Sweden)

    Montes Giraldo José Joaquín

    2003-06-01

    Full Text Available

    Marius Sala, Del latín al rumano. Versión española de Valeria Neagu, París, Unión Latina - Bucarest, Univers enciclopedic, 2002. El texto se dirige al lector corriente, no especialista, y por eso el aparato técnico-bibliográfico no se presenta en el curso de la exposición.

  5. Next-generation sequencing of 28 ALS-related genes in a Japanese ALS cohort.

    Science.gov (United States)

    Nakamura, Ryoichi; Sone, Jun; Atsuta, Naoki; Tohnai, Genki; Watanabe, Hazuki; Yokoi, Daichi; Nakatochi, Masahiro; Watanabe, Hirohisa; Ito, Mizuki; Senda, Jo; Katsuno, Masahisa; Tanaka, Fumiaki; Li, Yuanzhe; Izumi, Yuishin; Morita, Mitsuya; Taniguchi, Akira; Kano, Osamu; Oda, Masaya; Kuwabara, Satoshi; Abe, Koji; Aiba, Ikuko; Okamoto, Koichi; Mizoguchi, Kouichi; Hasegawa, Kazuko; Aoki, Masashi; Hattori, Nobutaka; Tsuji, Shoji; Nakashima, Kenji; Kaji, Ryuji; Sobue, Gen

    2016-03-01

    We investigated the frequency and contribution of variants of the 28 known amyotrophic lateral sclerosis (ALS)-related genes in Japanese ALS patients. We designed a multiplex, polymerase chain reaction-based primer panel to amplify the coding regions of the 28 ALS-related genes and sequenced DNA samples from 257 Japanese ALS patients using an Ion Torrent PGM sequencer. We also performed exome sequencing and identified variants of the 28 genes in an additional 251 ALS patients using an Illumina HiSeq 2000 platform. We identified the known ALS pathogenic variants and predicted the functional properties of novel nonsynonymous variants in silico. These variants were confirmed by Sanger sequencing. Known pathogenic variants were identified in 19 (48.7%) of the 39 familial ALS patients and 14 (3.0%) of the 469 sporadic ALS patients. Thirty-two sporadic ALS patients (6.8%) harbored 1 or 2 novel nonsynonymous variants of ALS-related genes that might be deleterious. This study reports the first extensive genetic screening of Japanese ALS patients. These findings are useful for developing genetic screening and counseling strategies for such patients. PMID:26742954

  6. Heterogeneous nucleation of solid Al from the melt by Al 3 Ti : Molecular dynamics simulations

    KAUST Repository

    Wang, Junsheng

    2010-10-27

    It has been known experimentally for some time that Al3 Ti is a powerful nucleant for the solidification of aluminum from the melt; however, a full microscopic understanding is still lacking. To develop this understanding, we have performed molecular dynamics simulations of the nucleation and early stages of growth using published embedded atom method potentials for Al-Ti, but modified by us to stabilize the D 022 structure. We discover that Al3 Ti can indeed be very effective in promoting the growth of solid Al but the manner in which growth takes place depends sensitively on the surface on which the Al nucleates. In particular, complete growth of solid Al from the liquid on the (001) and (110) surfaces of Al3 Ti occurs at a lower temperature than on the (112) surface. This anisotropy agrees with observations in previous experiments. We explain this observation in terms of interfacial energies. On the preferential (111) surface of Al the solid-liquid interfacial energy is highest while the solid-vacuum energy is lowest. Our simulations also show that the extent of ordering taking place in liquid Al close to the Al 3 Ti substrate above the melting point correlates well with the effectiveness of the substrate as a nucleant below the melting temperature: this could provide a computationally efficient scheme to identify good nucleants. © 2010 The American Physical Society.

  7. Al4C3 Hydration Thermochemical Analysis for Burned Carbon-containing Refractories with Al

    Institute of Scientific and Technical Information of China (English)

    YANG Ding'ao; YU Zhiming; FAN Liuwu

    2003-01-01

    In this paper, X-ray diffractogram analysis and SEM observation of Al4 C3 formed at high temperature from carbon-containing refractories with Al have been carried out.Aluminum added to carbon-containing refractories reacts with C(s)to form Al4 C3(s) gradually during heating from 600 ℃ to 1200℃.It is considered that the interlocked structure of Al4 C3 plate crystals promotes the outstanding increase of hot modulus of rupture of carbon-containing refractories with Al. The HMOR of carbon-containing refractories added with Al additive from 0 to 5wt% increases by 2.8 times being from 6.5MPa to 18.2MPa.After a thermochemical calculation for hydration reaction processes of Al4 C3 and H2O(g), the equilibrium partial pressure chart of H2O(g)in H2O-Al4C3-Al(OH)3 system vs various temperatures has been attained . The H2O (g) partial pressure in the air needed for the Al4 C3 hydration reaction is no more than 10~18 atm at the temperature below 120℃.It is considered that the burned carbon-containing refractories with Al is extremely easy to hydrate and the cracking of burned carbon-containing refractories is generated because that the hydration expansion is 2.11 times during transforming from Al4 C3 to Al(OH)3.The fundamental measure against hydration of the refractories is to insulate the refractories from H2O(g)by various means such as pitch impregnation or other sealing materials.

  8. DISTINGSI DAN DIASPORA TASAWUF ABÛ AL-HASAN AL-SHÂDHILÎ

    Directory of Open Access Journals (Sweden)

    Saifulah Saifulah

    2015-09-01

    Full Text Available This article discusses Shâdhilîyah, one of the most recognized sufi orders, which possesses quite distinct aspects in the conception of its mystical teachings. This sufi order was founded by Abû al-H}asan al-Shâdhilî, a sufi who has moderate and open view of the worldly life. Al-Shâdhilî explained about how a sufi should behave towards and deal with worldly matters. Although al-Shâdhilî asserted that a person who practice tasawwuf should not pay more adoration on the worldly matters (hubb al-dunyâ, the person does not have to abhor and leave such lively aspects as wealth and position behind. The most important thing to a sufi, according to al-Shadhili, is how he obeys the requirements of shar‘ by avoiding away from immoral deeds and at the same time recognizing God in his heart (ma‘rifat Allâh. Al-Shâdhilî initiated tasawuf ‘amalî which is affiliated to the Ahl al-Sunnah wa al-Jamâ‘ah school, an Islamic mystical thought that adheres to the principles of sharî‘ah based on the foundation of al-Qur’ân dan H}adîth. The concept of al-Shâdhilî’s tasawuf has been subsequently revealed into the great sufi order spectrum, namely al-Shâdhilîyah, where during its historical development this sufi order has led to the emergence of many branches with different names.Keywords: Shâdhilîyah, open view, hubb al-dunyâ, ma‘rifat Allâh.

  9. Clinical trials for neuroprotection in ALS.

    Science.gov (United States)

    Siciliano, G; Carlesi, C; Pasquali, L; Piazza, S; Pietracupa, S; Fornai, F; Ruggieri, S; Murri, L

    2010-07-01

    Owing to uncertainty on the pathogenic mechanisms underlying motor neuron degeneration in amyotrophic lateral sclerosis (ALS) riluzole remains the only available therapy, with only marginal effects on disease survival. Here we review some of the recent advances in the search for disease-modifying drugs for ALS based on their putative neuroprotective effetcs. A number of more or less established agents have recently been investigated also in ALS for their potential role in neuroprotection and relying on antiglutamatergic, antioxidant or antiapoptotic strategies. Among them Talampanel, beta-lactam antibiotics, Coenzyme Q10, and minocycline have been investigated. Progress has also been made in exploiting growth factors for the treatment of ALS, partly due to advances in developing effective delivery systems to the central nervous system. A number of new therapies have also been identified, including a novel class of compounds, such as heat-shock protein co-inducers, which upregulate cell stress responses, and agents promoting autophagy and mitochondriogenesis, such as lithium and rapamycin. More recently, alterations of mRNA processing were described as a pathogenic mechanism in genetically defined forms of ALS, as those related to TDP-43 and FUS-TLS gene mutations. This knowledge is expected to improve our understanding of the pathogenetic mechanism in ALS and developing more effective therapies. PMID:20406180

  10. Modificación superficial de titanio pulvimetalúrgico mediante recubrimientos aplicados por técnicas coloidales y difusión

    OpenAIRE

    Ureña Alcázar, Julia María; Mendoza, Carlos; Ferrari, Begoña; Castro, Yolanda; Tsipas, Sophia Alexandra; Morales, Alfredo José; Gordo Odériz, Elena

    2015-01-01

    El titanio y sus aleaciones son materiales conocidos por su atractiva combinación de propiedades. A pesar de ser los metales preferidos para aplicaciones biomédicas tales como prótesis o implantes para sustitución de tejido óseo, aún presentan aspectos mejorables para estas aplicaciones, como la baja resistencia al desgaste o el elevado módulo elástico. Otras potenciales aplicaciones como en automoción también requieren la mejora de la resistencia al desgaste de estas aleaciones. En este trab...

  11. superficial por soldadura automática

    Directory of Open Access Journals (Sweden)

    Elvis López B.

    2007-01-01

    Full Text Available En el siguiente trabajo se evalúa el aumento de la resistencia al desgaste abrasivo de las superficies de trabajo de aperos para la labranza de suelos, luego de aplicar el recargue superficial por el método de soldadura automática por arco sumergida (SAAS, utilizando para ello un fundente cerámico obtenido a partir de la reconstitución de la escoria del propio proceso. Se realizan mediciones de macrodureza, microdureza y resitencia al desgaste, se determina además el índice de desgate en condiciones de campo, utilizando medios reales de labranza de suelos.

  12. Disordered crystal structure of 20H-AlON, Al10O3N8

    International Nuclear Information System (INIS)

    The disordered crystal structure of 20H-AlON (Al10O3N8) was determined by combined use of X-ray powder diffraction and transmission electron microscopy. The title compound is hexagonal with space group P63/mmc (Z=2) and the unit-cell dimensions are a=0.307082(5) nm, c=5.29447(8) nm and V=0.432376(12) nm3. The structural model showed the positional disordering of three of the six Al sites in the unit cell. The reliability indices calculated from the Rietveld method were Rwp=6.97%, S (=Rwp/Re)=1.68, Rp=5.45%, RB=5.13% and RF=4.56%. We interpreted the disordered structure of 20H-AlON as a statistical average of six different types of ordered structural configurations, which are composed of an octahedral [Al(O, N)6] layer and tetrahedral [Al(O, N)4] layers. We demonstrated the high correlations between the hexagonal unit-cell dimensions and the octahedral layer concentrations for AlON and SiAlON polytypoids. - Graphical abstract: Variations of a and c/(nO+nT) with nO/(nO+nT). The a and c are the hexagonal unit-cell dimensions of AlON, SiAlON and AlN. The nO and nT are, respectively, the numbers of octahedral and tetrahedral layers in the unit cells. The unit-cell dimensions in literature are plotted in black plus for AlON and black cross for SiAlON. The unit-cell dimensions of AlN are a=0.3110 nm and c=0.4980 nm. - Highlights: • Crystal structure of Al10O3N8 is determined by laboratory X-ray powder diffraction. • The atom arrangements are represented by the split-atom model. • Six types of ordered atom arrangements are derived from the disordered structure. • Hexagonal unit-cell dimensions changed systematically for AlON and SiAlON compounds

  13. Prinsip Pendidikan Karakter dalam Islam: Studi Komparasi Pemikiran Al-Ghazali dan Burhanuddin Al-Zarnuji

    Directory of Open Access Journals (Sweden)

    Agus Setiawan

    2014-06-01

    Full Text Available The impelemtantion of character education that is done by the Indonesian government recently has been provoked by al-Ghazali and Burhanuddin al-Zarnuji long ago. It was proven by some written thoughts of al-Ghazali and Burhanuddin al-Zarnuji. They were very famous scientists in their era and widely welknown as educational experts who produced some phenomenal thoughts many people use today. Al-Ghazali and Burhanuddin al-Zarnuji lived in the era of Bani Abbasiyah monarchy, but Both of them lived in different era. Al-Ghazali was born first, then Burhanuddin al-Zarnuji. They had different mazhab, al-Ghazali went to the traditional principle of mazhab Syafi’I and Burhanuddin al-Zarnuji went to the modern principle of mazhab Hanafi. The differences, of course, would create a different thought. Still, they might have a similar principle of Islamic character education. The thoughts of character education of al-Ghazali have been poured in the “Ayyuha Walad” focusing to the students’ character building characterized by religiously obedient, skillfull of general and religious knowledge, socially helpful, affectionate, generous, good citizen, and coloring the society. Some applicable thoughts of character education of Ayyuha al-Walad of al-Gazhali to the contemporary education are: the balance of the happiness purposes of the recent life and the life after death, qana’ah and tawakal, affectionate, caring other, patience, honesty, philanthrophy, social works, generousity, democratic, peace makers, and patriotic. Those characters are also directed in the islamic character education nowdays. So that, the thoughts of al-Ghazali positively and responsively are absorbed by the Indonesian government to build the national character widely implementing in the national curriculum based on the local wisdom and the Islamic values. In the end, the students are able to live happily based on the Islamic rules by implementing the good behavior. Similar to the al

  14. Morphology of phase separation in AlN-Al2OC and SiC-AlN ceramics

    International Nuclear Information System (INIS)

    Solid solutions in the AIN-Al2OC and SiC-AlN systems were fabricated by hot-pressing powder mixtures in graphite dies. X-ray diffraction showed the samples to be single phases of 2H structure. The samples were annealed between 1600 degrees and 1900 degrees C for up to 1000 h. In the SiC-AlN system, optical microscopy and X-ray diffraction failed to reveal microstructural or phase changes. However, electron microscopy showed that samples had decomposed. Streaking of diffraction spots occurred along directions orthogonal to [012] planes (∼43 degrees off the c axis), which is approximately the direction along which the elastic energy function is a minimum. The orientation-dependent Young's modulus was also a minimum along this direction. In AlN-Al2OC, optical microscopy and X-ray diffraction indicated the occurrence of decomposition. The precipitates were disk-shaped with [001] orthogonal to the disks. The occurrence of decomposition along the [001] direction suggests that it is the elastically soft direction

  15. Nanocrack-induced leakage current in AlInN/AlN/GaN

    International Nuclear Information System (INIS)

    Here we report on the study of nano-crack formation in Al1−xInxN/AlN/GaN heterostructures, on its association with composition fluctuation and on its local electrical properties. It is shown here that indium segregation at nano-cracks and threading dislocations originating from the non-pseudomorphic AlN interlayer could be the cause of the high reverse-bias gate leakage current of Ni/Au Schottky contacts on Al1−xInxN/AlN/GaN heterostructures and significantly affects the contact rectifying behavior. Segregation of indium around crack tips in Al1−xInxN acting as conductive paths was assessed with conductive atomic force microscopy.

  16. Scattering induced by Al segregation in AlGaN/GaN heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiwen; Lu, Yanwu, E-mail: ywlu@bjtu.edu.cn [Department of Physics, Beijing Jiaotong University, Beijing 100044 (China); Ji, Dong [School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85281 (United States)

    2015-08-17

    The effect of Al segregation near dislocations on the mobility of two-dimensional electron gas in AlGaN/GaN heterostructure-based high-electron-mobility transistors was investigated. Exponentially varied composition fluctuation was effective in describing Al segregation near dislocations when calculating scattering behavior. Mobility, which was limited by Al segregation surrounding dislocation lines, was calculated to be in the order of 10{sup 3} cm{sup 2}/Vs to 10{sup 6} cm{sup 2}/Vs. Results indicated that the mobility in AlGaN/GaN heterojunction was enhanced upon the reduction of dislocation density at low temperature. This study contributes to generating higher electron mobility in AlGaN/GaN heterojunctions.

  17. Scattering induced by Al segregation in AlGaN/GaN heterostructures

    International Nuclear Information System (INIS)

    The effect of Al segregation near dislocations on the mobility of two-dimensional electron gas in AlGaN/GaN heterostructure-based high-electron-mobility transistors was investigated. Exponentially varied composition fluctuation was effective in describing Al segregation near dislocations when calculating scattering behavior. Mobility, which was limited by Al segregation surrounding dislocation lines, was calculated to be in the order of 103 cm2/Vs to 106 cm2/Vs. Results indicated that the mobility in AlGaN/GaN heterojunction was enhanced upon the reduction of dislocation density at low temperature. This study contributes to generating higher electron mobility in AlGaN/GaN heterojunctions

  18. 60Co gamma radiation effect on AlGaN//AlN/GaN HEMT devices

    International Nuclear Information System (INIS)

    The testing techniques and experimental methods of the 60Co gamma irradiation effect on AlGaN/AlN/GaN high electron mobility transistors (HEMTs) are established. The degradation of the electrical properties of the device under the actual radiation environment are analyzed theoretically, and studies of the total dose effects of gamma radiation on AlGaN/AlN/GaN HEMTs at three different radiation bias conditions are carried out. The degradation patterns of the main parameters of the AlGaN/AlN/GaN HEMTs at different doses are then investigated, and the device parameters that were sensitive to the gamma radiation induced damage and the total dose level induced device damage are obtained. (authors)

  19. 60Co gamma radiation effect on AlGaN/AlN/GaN HEMT devices

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-Ping; LUO Yin-Hong; WANG Wei; ZHANG Ke-Ying; GUO Hong-Xia; GUO Xiao-Qiang; WANG Yuan-Ming

    2013-01-01

    The testing techniques and experimental methods of the 60Co gamma irradiation effect on AlGaN/AlN/GaN high electron mobility transistors (HEMTs) are established.The degradation of the electrical properties of the device under the actual radiation environment are analyzed theoretically,and studies of the total dose effects of gamma radiation on AlGaN/AlN/GaN HEMTs at three different radiation bias conditions are carried out.The degradation patterns of the main parameters of the AlGaN/AlN/GaN HEMTs at different doses are then investigated,and the device parameters that were sensitive to the gamma radiation induced damage and the total dose level induced device damage are obtained.

  20. Al-based precipitate evolution during high temperature annealing of Al implanted in Si

    International Nuclear Information System (INIS)

    Al-based precipitate evolution for 80 keV Al ions implanted in Si has been investigated. Precipitates are formed during high temperature annealings of 1 x 1015/cm2 implanted samples. They are located at two depths where Al concentration peaks are detected. Al atoms are gettered into the extended defects present in the crystal and/or precipitate when their concentration is higher than the solid solubility value at the annealing temperature. Increasing annealing time, precipitates dissolve out and only a small fraction of atoms diffuses into the sample, meanwhile the greater part evaporates from the sample. At 1 x 1013/cm2 dose Al concentration is below the solid solubility limit. The secondary defects are not detected and the dopant profile does not display anomalous peaks. Moreover, all the implanted Al is electrically active and remains in the sample during the first instant of annealing. At higher annealing times it diffuses out of the sample reducing the residual dose

  1. Microscopic Properties of Long-Period Ordering in Al-Rich TiAl Alloys

    Science.gov (United States)

    Hata, S.; Nakano, T.; Kuwano, N.; Itakura, M.; Matsumura, S.; Umakoshi, Y.

    2008-07-01

    The ordering mechanism of long-period superstructures (LPSs) in Al-rich TiAl alloys has been investigated by high-resolution transmission electron microscopy (HRTEM). The LPSs are classified in terms of arrangements of base clusters with different shapes and compositions formed in Ti-rich (002) layers of L10-TiAl matrix: square Ti4Al, fat rhombus Ti3Al, and lean rhombus Ti2Al type clusters. The HRTEM observations revealed that antiphase boundaries of long-range-ordered LPS domains and short-range-ordered microdomains are constructed by various space-filling arrangements of the base clusters. Such a microscopic property characterized by the base clusters and their arrangements is markedly analogous to that of the {left< {{text{1,1/2,0}}} rightrangle } * special-point ordering alloys such as Ni-Mo.

  2. Observation of Electronic Shells and Characteristic Products from Mass Abundance Spectra of Al Cluster and Al-C Cluster Anions

    Institute of Scientific and Technical Information of China (English)

    LIU Bing-Chen; ZHAI Hua-Jin; ZHOU Ru-Fang; NI Guo-Quan; XU Zhi-Zhan

    2000-01-01

    Using a laser vaporization/pulsed molecular beam cluster source, Al cluster anions and Al-C mixed cluster anions are produced and recorded by a time of flight mass spectrometer. Mass abundance spectra of the Al cluster anions in the size range from Al2 to Al42 show that Al-13, Al23, Al35, and slightly, Al37 are local maxima, as predicted by the electronic jellium model. Mixed clusters Aln C- and Aln C2 are also shown, among which the most abundant species are Al3 C2 , Al6 C2 , Al7 C- and Al7 C2 in the small size range. The formation mechanism of these products is discussed.

  3. Grain refinement of hypoeutectic Al-Si alloy prepared with ELTA by Al-4B master alloy

    Institute of Scientific and Technical Information of China (English)

    WANG Ming-xing; MENG Xiang-yong; LIU Zhi-yong; LIU Zhong-xia; WENG Yong-gang; SONG Tian-fu; YANG Sheng

    2006-01-01

    Electrolytic low-titanium aluminum (ELTA) was produced by adding TiO2 powder to an industrial aluminum electrolyzer.The grain refining effect of Al-4B master alloy in the hypoeutectic Al-Si alloy prepared by using ELTA was investigated, and compared with those of Al-5Ti, Al-5Ti-1B and Al-4B master alloys in the similar alloy prepared by using pure Al. The results indicate that when Al-4B is added to the melt of the alloy prepared by using ELTA in terms of the Ti/B mass ratio of 5:1, the grain refining effect is better than those of Al-5Ti, Al-5Ti-1B and Al-4B master alloys. Thus, using Al-4B to refine the grain of Al-Si alloys prepared by using ELTA will possibly become a feasible way of obtaining Al-Si alloy with homogeneous and fine microstructure.

  4. In-Situ Synthesis of AlN Powders and Composite AlN Powders with Yttrium Addition

    Institute of Scientific and Technical Information of China (English)

    郑新和; 王群; 林志浪; 李春国; 周美玲

    2002-01-01

    Using Al-Mg and Al-Mg-Y alloys as raw materials and nitrogen as gas reactants, AlN powders and composite AlN powders by in-situ synthesis method were prepared. AlN lumps prepared by the nitriding of Al-Mg and Al-Mg-Y alloys have porous microstructure, which is favorable for pulverization. They have high purity, containing 1.23%(mass fraction) oxygen impurity, and consisted of AlN single phase. The average particle size of AlN powders is 6.78 μm. Composite AlN powders consist of AlN phases and rare earth oxide Y2O3 phase. The distribution of particle size of AlN powders shows two peaks. In view of packing factor, AlN powders with such size distribution can easily be sintered to high density.

  5. Generation and evolution of nanoscale AlP and Al{sub 13}Fe{sub 4} particles in Al-Fe-P system

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Huan; Gao, Tong; Zhu, Xiangzhen; Wu, Yuying; Qian, Zhao; Liu, Xiangfa, E-mail: xfliu@sdu.edu.cn

    2015-02-15

    Highlights: • Diffusion and gradual solid reactions between Al and Fe{sub x}P phases in Al-Fe-P alloy were investigated. • Nanoscale AlP clusters are in-situ generated and evolve during the whole process. • This novel Al-Fe-P alloy has an excellent low-temperature refining performance on hypereutectic Al-Si alloy. - Abstract: In this paper, the gradual solid reactions between Al and Fe{sub x}P phases in Al-Fe-P alloy were investigated. The results show that the whole reaction process undergoes four main stages: the diffusion of Al atom, the generation of (Al, Fe, P) intermediate compound, the precipitation of nano AlP and Al{sub 13}Fe{sub 4} clusters and their growth to submicron particles. The microstructure of Fe-P particles evolves from the “egg-type”, the “sponge-type” to the “sesame-cake” structure. AlP and Al{sub 13}Fe{sub 4} nano phases have in-situ generated and evolved during the whole process. The gradual reaction mechanism has been discussed. Furthermore, a novel Al-Fe-P alloy which contains (Al, Fe, P) intermediate compounds and nano AlP particles has been synthesized and its low-temperature refining performance on A390 alloy has also been investigated.

  6. TEM characterization of oxidized AlGaAs/AlAs nonlinear optical waveguides

    OpenAIRE

    Guillotel, E; Langlois, C.; Ghiglieno, F.; Leo, G.; Ricolleau, C.

    2010-01-01

    Abstract The internal interfaces of multilayer Al x Ga 1-x As/AlAs nonlinear optical waveguides are investigated by high-angle annular-dark-field and energy-filtered scanning transmission electron microscopy, before and after partial wet oxidation of AlAs layers. Via a simple phenomenological model, the corresponding roughness parameters allow predicting the scattering-induced waveguide optical losses, which are in reasonable agreement with the experimental value of 0.5 cm -1. We also find...

  7. Modified Mechanism of Eutectic Silicon in Al2O3/Al-Si Alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Al2O3/Al-Si alloy composite was manufactured by squeeze casting. The morphology of the eutectic silicon in the composite was observed by scanning electronic microscope (SEM), and the modified mechanism of eutectic silicon in the composite was approached. The alumina fiber in the composite can trigger twin during the growth of Al-Si eutectic and lead to the modification of eutectic silicon near the fiber.

  8. Two-Phase (TiAl+TiCrAl) Coating Alloys for Titanium Aluminides

    Science.gov (United States)

    Brady, Michael P. (Inventor); Smialek, James L. (Inventor); Brindley, William J. (Inventor)

    1998-01-01

    A coating for protecting titanium aluminide alloys, including the TiAl gamma + Ti3Al (alpha(sub 2)) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000 C. is disclosed. This protective coating consists essentially of titanium, aluminum. and chromium in the following approximate atomic ratio: Ti(41.5-34.5)Al(49-53)Cr(9.5-12.5)

  9. Effect of the interface in laminated composites of Al-1100 and Al-2024

    International Nuclear Information System (INIS)

    Laminated composites consisting of alternating layers of Al-1100 and Al-2024 were produced by hot rolling, with 45% Al-2024 volume fraction. These composites were subjected to cyclic thermal treatment (various numbers of cycles) and to isothermal treatment (various numbers of cycles) and to isothermal treatment (at peak temperature and for times equivalent to those of the thermal cycles. Microhardness, tensile and fatigue crack arrester modes) were studied in the initial state and after treatments. (E.G.)

  10. Another Security Improvement over the Lin et al.'s E-voting Scheme

    Science.gov (United States)

    Asaar, Maryam Rajabzadeh; Mohajeri, Javad; Salmasizadeh, Mahmoud

    In 2003, Lin et al. have proposed an electronic voting scheme which can be utilized in large-scale elections, and claimed it detects double voting. But in this paper, by presenting an attack, we show that voters can successfully vote more than once without being detected. Hence, we propose a new modified scheme based on the Lin et al.'s scheme with the same efficiency to solve this weakness and analyze its security.

  11. Melt Processing and Characterization of Al-SiC Nanocomposite, Al, and Mg Foam Materials

    OpenAIRE

    Ahmed M. Nabawy; Khalil Abdelrazek Khalil; Al-Ahmari, Abdulrahman M.; Sherif, El-Sayed M.

    2016-01-01

    In the present work, metallic foams of Al, Mg and an Al-SiC nanocomposite (MMNC) have been fabricated using a new manufacturing technique by employing melt infiltration assisted with an electromagnetic force. The aim of this investigation was to study and to develop a reliable manufacturing technique consisting of different types of metallic foams. In this technique, an electromagnetic force was used to assist the infiltration of Al-SiC slurry and of pure liquid metal into a leachable pattern...

  12. Fabrication, phase transformation studies, and characterization of SiC-AlN-Al2OC ceramics

    International Nuclear Information System (INIS)

    Principal focus was on phase transformation, microstructure development, and elevated temperature creep, with some effort on room- temperature mechanical properties of selected materials. Fabrication was largely hot pressing, although many of the compositions can be densified by pressureless sintering; hot pressing was to ensure full attainment of density with fine microstructure. Most of the work was on SiC-AlN and AlN-Al2OC pseudobinaries

  13. Synthesis of core–shell AlOOH hollow nanospheres by reacting Al nanoparticles with water

    Science.gov (United States)

    Lozhkomoev, A. S.; Glazkova, E. A.; Bakina, O. V.; Lerner, M. I.; Gotman, I.; Gutmanas, E. Y.; Kazantsev, S. O.; Psakhie, S. G.

    2016-05-01

    A novel route for the synthesis of boehmite nanospheres with a hollow core and the shell composed of highly crumpled AlOOH nanosheets by oxidizing Al nanopowder in pure water under mild processing conditions is described. The stepwise events of Al transformation into boehmite are followed by monitoring the pH in the reaction medium. A mechanism of formation of hollow AlOOH nanospheres with a well-defined shape and crystallinity is proposed which includes the hydration of the Al oxide passivation layer, local corrosion of metallic Al accompanied by hydrogen evolution, the rupture of the protective layer, the dissolution of Al from the particle interior and the deposition of AlOOH nanosheets on the outer surface. In contrast to previously reported methods of boehmite nanoparticle synthesis, the proposed method is simple, and environmentally friendly and allows the generation of hydrogen gas as a by-product. Due to their high surface area and high, slit-shaped nanoporosity, the synthesized AlOOH nanostructures hold promise for the development of more effective catalysts, adsorbents, vaccines and drug carriers.

  14. Strain Rates and Grain Growth in Al 5754 and Al 6061 Friction Stir Spot Welds

    Science.gov (United States)

    Gerlich, A.; Yamamoto, M.; North, T. H.

    2007-06-01

    The stir zone temperature and microstructures are compared in friction stir spot welds produced in Al 5754 and Al 6061 alloys. Electron backscattered diffraction was used to determine the relationship between tool rotation speed during welding and final stir zone grain size. Comparison of the grain sizes in rapidly quenched welds with those in air-cooled joints confirmed that grain growth occurred only in Al 6061 spot welds. There was no evidence of abnormal grain growth in the stir zones of Al 6061 welds; the final grain size could be represented using an Arrhenius equation. The strain rates during welding were determined by incorporating the stir zone temperature and average subgrain sizes in quenched spot welds in the Zener-Hollomon relation. When the tool rotation speed increased from 750 to 3000 RPM, the strain rate values ranged from 180 to 497 s-1 in Al 5754 spot welds and from 55 to 395 s-1 in Al 6061 spot welds. It is suggested that a no-slip boundary condition may be appropriate during numerical modeling of Al 5754 and 6061 friction stir spot welding. This is not the case during Al 7075, Al 2024, and Mg-alloy AZ91 spot welding because spontaneous melting facilitates slippage at the tool contact interface.

  15. Study on Mg/Al Weld Seam Based on Zn–Mg–Al Ternary Alloy

    Directory of Open Access Journals (Sweden)

    Liming Liu

    2014-02-01

    Full Text Available Based on the idea of alloying welding seams, a series of Zn–xAl filler metals was calculated and designed for joining Mg/Al dissimilar metals by gas tungsten arc (GTA welding. An infrared thermography system was used to measure the temperature of the welding pool during the welding process to investigate the solidification process. It was found that the mechanical properties of the welded joints were improved with the increasing of the Al content in the Zn–xAl filler metals, and when Zn–30Al was used as the filler metal, the ultimate tensile strength could reach a maximum of 120 MPa. The reason for the average tensile strength of the joint increasing was that the weak zone of the joint using Zn–30Al filler metal was generated primarily by α-Al instead of MgZn2. When Zn–40Al was used as the filler metal, a new transition zone, about 20 μm-wide, appeared in the edge of the fusion zone near the Mg base metal. Due to the transition zones consisting of MgZn2- and Al-based solid solution, the mechanical property of the joints was deteriorated.

  16. Tetragonal phase in Al-rich region of U-Fe-Al system

    Energy Technology Data Exchange (ETDEWEB)

    Meshi, L. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Zenou, V. [Nuclear Research Center-Negev, P.O. Box 9001, Beer-Sheva (Israel); Ezersky, V. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Munitz, A. [Nuclear Research Center-Negev, P.O. Box 9001, Beer-Sheva (Israel); Talianker, M. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)]. E-mail: mital@bgumail.bgu.ac.il

    2005-10-27

    A new ternary aluminide U{sub 2}FeAl{sub 20} with the approximate composition Al-4.2at% Fe-8.5at% U was observed in the Al-rich corner of the U-Al-Fe system. Transmission electron microscopy and electron microdiffraction technique were used for characterization of the structure of this phase. It has a tetragonal unit cell with the parameters a=12.4A and c=10.3A and can be described by the space group I4-bar 2m.

  17. Tetragonal phase in Al-rich region of U-Fe-Al system

    International Nuclear Information System (INIS)

    A new ternary aluminide U2FeAl20 with the approximate composition Al-4.2at% Fe-8.5at% U was observed in the Al-rich corner of the U-Al-Fe system. Transmission electron microscopy and electron microdiffraction technique were used for characterization of the structure of this phase. It has a tetragonal unit cell with the parameters a=12.4A and c=10.3A and can be described by the space group I4-bar 2m

  18. AlN/IDT/AlN/Sapphire SAW Heterostructure for High-Temperature Applications.

    Science.gov (United States)

    Legrani, Ouarda; Aubert, Thierry; Elmazria, Omar; Bartasyte, Ausrine; Nicolay, Pascal; Talbi, Abdelkrim; Boulet, Pascal; Ghanbaja, Jaafar; Mangin, Denis

    2016-06-01

    Recent studies have evidenced that Pt/AlN/Sapphire surface acoustic wave (SAW) devices are promising for high-temperature high-frequency applications. However, they cannot be used above 700°C in air atmosphere as the Pt interdigital transducers (IDTs) agglomerate and the AlN layer oxidizes in such conditions. In this paper, we explore the possibility to use an AlN protective overlayer to concurrently hinder these phenomena. To do so, AlN/IDT/AlN/Sapphire heterostructures undergo successive annealing steps from 800°C to 1000°C in air atmosphere. The impact of each step on the morphology, microstructure, and phase composition of AlN and Pt films is evaluated using optical microscopy, scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), and secondary ion mass spectroscopy (SIMS). Finally, acoustical performance at room temperature of both protected and unprotected SAW devices are compared, as well as the effects of annealing on these performance. These investigations show that the use of an overlayer is one possible solution to strongly hinder the Pt IDTs agglomeration up to 1000°C. Moreover, AlN/IDT/AlN/Sapphire SAW heterostructures show promising performances in terms of stability up to 800°C. At higher temperatures, the oxidation of AlN is more intense and makes it inappropriate to be used as a protective layer. PMID:27076407

  19. Sintering Behavior of CNT Reinforced Al6061 and Al2124 Nanocomposites

    OpenAIRE

    2014-01-01

    Ball milling and spark plasma sintering were successfully used to produce carbon nanotube reinforced Al6061 and Al2124 nanocomposites which have potential applications in the fields of aerospace, automotive, electronics, and high precision instrumentation. Al2124 and Al6061 nanocomposite powders containing 0.5 to 2 wt.% CNTs prepared through sonication and wet ball milling were spark plasma sintered at 400, 450, and 500°C for 20 minutes under a pressure of 35 MPa. CNTs were better dispersed, ...

  20. Microstructure and mechanical properties of Al2O3/TiAl composite

    Institute of Scientific and Technical Information of China (English)

    AI Tao-tao; WANG Fen; ZHU Jian-feng

    2006-01-01

    Al2O3/TiAl composites were fabricated by PAXD (pressure-assisted exothermic dispersion) method. The effects of Nb2O5 content on the microstructure and mechanical properties of the composites were investigated. The results show that the ultimate phases of the composite consist of TiAl, Ti3Al, Al2O3 and a small amount of NbAl3. SEM reveals that a submicron γ+(α2/γ) dual phases structure can be presented after sintered at 1 200 ℃. Furthermore, with the increase of Nb2O5 content, the ratio of TiAl to Ti3Al phase decreases correspondingly, the grains of the composites are remarkably refined, and the produced Al2O3 particles are uniformly dispersed. When 6% Nb2O5 is added, the composite has the best comprehensive properties. It exhibits a Vickers hardness of 4.77 GPa and a bending strength of 642 MPa. Grain-refinement and dispersion-strengthening are the main strengthening mechanisms.

  1. Production of AlN-Si-Al Ceramic-Metal Composites via Pressurless Infiltration Method

    OpenAIRE

    KALEMTAŞ, Ayşe; ARSLAN, Gürsoy; KARA, Ferhat

    2014-01-01

    In this work, the production of light (∼2,9 g/cm3) and dense (> 99 %) AlN based ceramic metal composites was conducted by the pressureless melt infiltration method. These composites contain a high ceramic volume fraction (> 50 vol %) which is the result of the reaction between Si3N4 and Al in the Si3N4-Al system. The production of the ceramic-metal composites was achieved via infiltrating 2024 Al alloys at different temperatures and holding times into the porous pellets which were prepared us...

  2. Coating of a layer of Au on Al13 : The findings of icosahedral Al@Al12Au20- and Al12Au202- fullerenes using ab initio pseudopotential calculations

    Science.gov (United States)

    Kumar, Vijay

    2009-02-01

    We report results of ab initio pseudopotential calculations on the nanocoating of gold on an icosahedral Al13 cluster and the findings of icosahedrally symmetric endohedral Al@Al12Au20- and empty cage Al12Au202- compound fullerenes formed of metal atoms. Twelve Al atoms cap the pentagonal faces of a dodecahedral Au20 cage in which each Au atom has three Al atoms and three Au atoms as nearest neighbors. Mixing of Al13 and Au20 magic clusters leads to a large heat of formation of 0.55 eV/atom and high stability of the Al@Al12Au20 compound fullerene. The binding energies of Al12Au20 and Al@Al12Au20 are 3.017 and 3.007 eV/atom, respectively, which are much larger than 2.457 eV/atom for Au32 fullerene, leading to the possibility of their high abundance.

  3. Deletion of ALS5, ALS6 or ALS7 increases adhesion of Candida albicans to human vascular endothelial and buccal epithelial cells

    OpenAIRE

    Zhao, Xiaomin; Oh, Soon-Hwan; Hoyer, Lois L.

    2007-01-01

    C. albicans yeast forms deleted for ALS5, ALS6 or ALS7 are more adherent than a relevant control strain to human vascular endothelial cell monolayers and buccal epithelial cells. In the buccal and vaginal reconstituted human epithelium (RHE) disease models, however, mutant and control strains caused a similar degree of tissue destruction. Deletion of ALS5 or ALS6 significantly slowed growth of the mutant strain; this phenotype was not affected by addition of excess uridine to the culture medi...

  4. Melting Transition of Small Aluminium Clusters Al11-20

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; ZHANG Feng-Shou; ZHU Zhi-Yuan

    2007-01-01

    Heat capacities of small aluminium clusters Al11-20 are investigated using MD simulation with empirical manybody Gupta potential. The heat capacities of some clusters Al11, Al12, Al13 and Al19 show well-defined peaks while the heat capacities of Al15-18 indicate a gradual melting transition. The spectra of isomers obtained by quenches along the MD trajectory give good interpretation for those results.

  5. Kerja Perspektif Al-Qur'an

    Directory of Open Access Journals (Sweden)

    Ahmad Munir

    2011-05-01

    Full Text Available The moslem ethics of life is based on movement as ex­pressed in certain terms like al-sharī’ah, al-tarīqah, al-sirāt, al-sabīl and al-manhaj, that make sense of way and teachings to achieve good life. Islam obliges and gives appreciation of the achievements of Mus­lims. The Qur’an uses several terms to refer to such work; ‘charity, kasb, juhd, ibtighâ’, sa ’yu and su ’âl. From this concept, the Qur’an considers work as nob­le, while begging is despicable. Work means thankful to God for the potential He bestows. The Qur’an promotes work not only because it is the way to achieve the wealth, but also because it possesses the its sacred value for the benefit of fulfilling livelihood. Therefore the work should also be done based on ethical values .

  6. 26Al in the interstellar medium

    International Nuclear Information System (INIS)

    Several different lines of physical reasoning have converged on the importance of the radioactive nucleus 26Al. The sciences of meteoritics, nucleosynthesis, gamma-ray astronomy, galactic chemical evolution, solar system formation, and interstellar chemistry all place this nucleus in a central position with possible profound implications. Perhaps more importantly the study of this radioactivity can unite these diverse fields in a complicated framework which will benefit all of them. This review traces the evolution of ideas concerning 26Al in the context of these disciplines. 26Al was first discussed for the possibility that its decay energy could melt meteorite parent bodies, and its daughter, 26Mg, was later found in meteorites with enhanced abundance. It was also among the first radioactivities expected to be synthesized in interestingly large quantities in nulceosynthetic events. The first definitive detection of gamma-rays from an interstellar radioactivity is that of 1.809 MeV gamma-rays from 26Al. This discovery has many implications, some of which are outlined here. The whole problem of isotopic anomalies in meteorites is greatly influenced by the specific issues surrounding excess 26Mg, whether it represents in situ decay of 26Al or memory of conditions of the ISM. The relationships among these ideas and their implications are examined. (orig.)

  7. Cd ion implantation in AlN

    International Nuclear Information System (INIS)

    Highlights: ► Cd ion implanted in AlN thin films. ► XRD shows damage produced during implantation. ► Annealing recovers damage in low fluence sample. ► RBS/C measurements show that Cd occupies substitutional sites. ► Cd can be a good candidate for p-type doping. - Abstract: AlN thin films were implanted with cadmium, to fluences of 1 × 1013 and 8 × 1014 at/cm2. The implanted samples were annealed at 950 °C under flowing nitrogen. Although implantation damage in AlN is known to be extremely stable the crystal could be fully recovered at low fluences. At high fluences the implantation damage was only partially removed. Implantation defects cause an expansion of the c-lattice parameter. For the high fluence sample the lattice site location of the ions was studied by Rutherford Backscattering/Channelling Spectrometry. Cd ions are found to be incorporated in substitutional Al sites in the crystal and no significant diffusion is seen upon thermal annealing. The observed high solubility limit and site stability are prerequisite for using Cd as p-type dopant in AlN.

  8. Survey and alignment at the ALS

    International Nuclear Information System (INIS)

    This paper describes survey and alignment at the Lawrence Berkeley National Laboratory's Advanced Light Source (ALS) accelerators from 1993 to 1995. The ALS is a 1.0 - 1.9 GeV electron accelerator producing extremely bright synchrotron light in the UV and soft-X-ray wavelengths. At the ALS, electrons are accelerated in a LINAC to 50 MeV, injected into a booster ring for further acceleration and finally injected into the storage ring. This is shown schematically in Figure 1. The storage ring, some 200 m in circumference, has been run with electron currents above 400 mA with lifetimes as high as 24 hours. The ALS is a third generation light source and requires for efficient storage ring operation, magnets aligned to within 150 mm of their ideal position. To accomplish this a network of monuments was established and their positions measured with respect to one another. The data was reduced using GEONET'' and STAR*NET'' software. Using the monuments as reference points, magnet positions were measured and alignment confirmed using the Kem Electronic Coordinate Determination System (ECDS''). A number of other papers dealing with survey and alignment (S ampersand A) at the ALS have been written that may further elucidate some details of the methods and systems described in this paper

  9. Direct laser cooling Al+ ions optical clocks

    CERN Document Server

    Zhang, J; Luo, J; Lu, Z H

    2016-01-01

    Al$^+$ ions optical clock is a very promising optical frequency standard candidate due to its extremely small blackbody radiation shift. It has been successfully demonstrated with indirect cooled, quantum-logic-based spectroscopy technique. Its accuracy is limited by second-order Doppler shift, and its stability is limited by the number of ions that can be probed in quantum logic processing. We propose a direct laser cooling scheme of Al$^+$ ions optical clocks where both the stability and accuracy of the clocks are greatly improved. In the proposed scheme, two Al$^+$ ions traps are utilized. The first trap is used to trap a large number of Al$^+$ ions to improve the stability of the clock laser, while the second trap is used to trap a single Al$^+$ ions to provide the ultimate accuracy. Both traps are cooled with a continuous wave 167 nm laser. The expected clock laser stability can reach $9.0\\times10^{-17}/\\sqrt{\\tau}$. For the second trap, in addition to 167 nm laser Doppler cooling, a second stage pulsed ...

  10. Epistemologi Penafsiran Ilmiah al-Qur’an

    Directory of Open Access Journals (Sweden)

    Sujiat Zubaidi Saleh

    2011-04-01

    Full Text Available The main objective in interpretating al-Qur’an is to explain the will of God and the operationalization of the will in the field of faith, laws, or ethics. At the phase of Islamic civilization, when the linguistic and philosophy science codified, raises the various method (manhaj, and interpretation streams (ittijahat, exegesis school (madzhab of al-Qur’an. In addition, also found in various shades of interpretation such as: fiqhi, kalami, balaghi, and isyari/ sufi, even philosophical. It was also discovered methods of tafsir ‘ilmi oriented to the utilization of the discovering science in order to prove the truth of scientific fact. The last pattern was ignited pro and contra among scholars and mufassir. As we know that alQur’an was not descended in the condition of cultural vacuum but it is a form of dialectics and the response to the condition and social situation, politic, and religion. This is relevant to the characteristics of al-Qur’an which can be applied throughout the periods. As we understood that interpretation is one of reflections of thought and civilization products. It always developed and influenced by the dynamics of human civilization, so in its development, science and al-Qur’an can be brought together in dialogue, although with some prerequisites specified interpretation.

  11. MOSQUE ARCHITECTURE AS A SUSTAINABLE BUILDING IN URBAN (Case Study: Al Markas Al Islamic Mosque Makassar

    Directory of Open Access Journals (Sweden)

    Imriyanti Imriyanti

    2014-02-01

    Full Text Available Abstract Mosque Architecture is a part of Islamic architecture. Mosque should be fused with elements of nature because its function as a place to pray to God who created the universe. Al Markas Al Islamic Makassar mosque is used as a center of Islamic aspirations of the people and the government to accommodate all the activities of moslems in Makassar. Through this function, the provision of Al Markas Al Islamic mosque began from the desire of Islamic societies in Makassar, which wants the Islamic center to be equipped with facilities and infrastructure as well as architectural, monumental buildings and structures that can be last for hundreds of years (continuous, blend with the environment, and also can be used by the public. Having regard to the function of a mosque especially at the Al Markas Al Islamic Makassar mosque, then the problem that arise is how the Al Markas Al Islamic mosque can be survived/sustainable  in order  to function  as a place  of worship  and  as a center  of Islam.  This research  is a descriptive qualitative research that is trying to generate data in the form of systematic and accurate picture of the object of study. The sustaiprophetlity  of Al Markas AL Islamic mosque can be known through the concept of Islam  in accordance with the view of Islam as well as the sustaiprophetlity of the buildings that seen in the spatial pattern of the mosque, appearance, natural lighting, natural ventilation, and user behavior of the mosque. Keywords: mosque architecture, sustaiprophetlity, view of Islam     Abstrak Arsitektur masjid merupakan bagian dari arsitektur Islam. Bangunan masjid sebaiknya dapat menyatu dengan unsur alam karena masjid difungsikan sebagai wadah dalam bersujud/sembahyang  kepada Allah SWT yang menciptakan alam semesta ini. Masjid Al Markas Al Islamic Makassar merupakan kompleks kegiatan Islam yang digunakan sebagai pusat aspirasi masyarakat  dan pemerintahan  yang dapat menampung

  12. Instability of TiC and TiAl3 compounds in Al-10Mg and Al-5Cu alloys by addition of Al-Ti-C master alloy

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The performance of Al-Ti-C master alloy in refining Al-10Mg and A1-5Cu alloys was studied by using electron probe micro-analyzer (EPMA) and X-ray diffractometer (XRD) analysis.The results indicate that there are obvious fading phenomena in both Al-10Mg and Al-5Cu alloys with the addition of Al-5Ti-0.4C refiner which contains TiC and TiAl3 compounds.Mg element has no influence on the stability of TiC and TiAl3, while TiC particles in Al-10Mg alloy react with Al to form Al4C3 particles, resulting in the refinement fading.However, TiC particles are relatively stable in Al-5Cu alloy, while TiAl3 phase reacts with Al2Cu to produce a new phase Ti(Al, Cu)2, which is responsible for the refinement fading in Al-5Cu alloy.These indicate that the refinement fading will not occur only when both the TiC particles and TiAl3 compound of Al-Ti-C refiner are stable in Al alloys.

  13. Study of corrosion inhibition of coupled Al2Cu–Al and Al3Fe–Al by cerium cinnamate using scanning vibrating electrode technique and scanning ion-selective electrode technique

    International Nuclear Information System (INIS)

    Highlights: • The corrosion inhibition of coupled Al2Cu–Al and Al3Fe–Al by cerium cinnamate was studied. • SVET and SIET were used to study the distribution of current densities and pH. • The corrosion inhibition mechanisms were analyzed. - Abstract: The galvanic corrosion of the coupled Al2Cu and Al as well as Al3Fe and Al in 0.005 M NaCl in and without the presence of cerium cinnamate was studied. Scanning vibrating electrode technique and scanning ion-selective electrode technique were used to measure the distribution of current densities and pH. The results indicate that cerium cinnamate played inhibiting effect on the coupling corrosion of Al2Cu–Al and Al3Fe–Al. For Al2Cu–Al, the inhibition was mainly influenced by the production of cerium oxide/hydroxide on Al2Cu surface. However, for Al3Fe–Al, the inhibition was mainly influenced by the adsorbed cerium cinnamate on the Al3Fe surface

  14. MgAl2O4–-Al2O3 solid solution interaction: mathematical framework and phase separation of -Al2O3 at high temperature

    Indian Academy of Sciences (India)

    Soumen Pal; A K Bandyopadhyay; S Mukherjee; B N Samaddar; P G Pal

    2011-07-01

    Although existence of MgAl2O4–-Al2O3 solid solution has been reported in the past, the detailed interactions have not been explored completely. For the first time, we report here a mathematical framework for the detailed solid solution interactions of -Al2O3 in MgAl2O4 (spinel). To investigate the solid solubility of -Al2O3 in MgAl2O4, Mg–Al spinel (MgO–Al2O3; = 1, 1.5, 3, 4.5 and an arbitrary high value 30) precursors have been heat treated at 1000°C. Presence of only non-stoichiometric MgAl2O4 phase up to = 4.5 at 1000°C indicates that alumina (as -Al2O3) present beyond stoichiometry gets completely accommodated in MgAl2O4 in the form of solid solution. → alumina phase transformation and its subsequent separation from MgAl2O4 has been observed in the Mg–Al spinel powders ( > 1) when the 1000°C heat treated materials are calcined at 1200°C. In the mathematical framework, unit cell of MgAl2O4 (Mg8Al16O32) has been considered for the solid solution interactions (substitution of Mg2+ ions by Al3+ ions) with -Al2O3. It is suggested that combination of unit cells of MgAl2O4 takes part in the interactions when > 5 (MgO–Al2O3).

  15. Al- Khwarizmi and axiomatic foundation of algebra

    International Nuclear Information System (INIS)

    This paper intends to investigate the axiomatic foundations of algebra, as they were presented in the book of algebra of al-Khwarizmi (9 th century), and as they were developed in many subsequent Arabic works. The paper gives also a description of algebra evolution towards a discipline independent ofgeometry and arithmetic: the two disciplines whosemarriage had led to its birth.By an in depth reading of some details in the text of al Khwarizmi , we concluded that this mathematician intended to lay down the axiomatic foundations of that new discipline. His resort to arithmetical and geometrical means was a way of making his theory more accessible. He used them to justify the axioms: those that were not explicitly introduced per se, and those that were remained implicit. The paper also relies on some unedited writingsof al-Khwarizmi's successors, which could shedlight on the ways they used to consolidate the foundations of algebra and improve its methods. (author)

  16. Moessbauer studies on Al-Co ferrites

    International Nuclear Information System (INIS)

    Moessbauer spectroscopy studies have been performed on the spinel CoAlxFe2-xO4 (.2≤x≤1.7) in the temperature range 77-750 K using either a liquid nitrogen bath cryostat or a furnace. The samples are magnetic at 77 K giving spectra that have magnetic sextets coexisting with a central line which increases in population with the Al-content indicating relaxation effects. The data shows that Al possesses no preference to either tetrahedral or octahedral sites of the ferrite over the whole range of concentration. The Moessbauer hyperfine interaction parameters and magnetic transition temperatures were determined. As expected the hyperfine field and Curie temperature decrease when the Al-content increases. (orig.)

  17. Magnetic Properties of NdAl2

    DEFF Research Database (Denmark)

    Bak, P.

    1974-01-01

    The magnetic properties of NdAl2 are calculated using a Hamiltonian including crystal-field and isotropic exchange interaction terms. A two-dimensional mean-field theory is evaluated to calculate single-crystal magnetization curves. It is shown that the magnetic properties can be understood using...... the crystal-field parameters derived from the magnetic exciton spectrum measured by Houmann et al. by means of inelastic neutron scattering. The combined lambda -Schottky anomaly in the heat capacity is explained. No additional parameters are introduced.......The magnetic properties of NdAl2 are calculated using a Hamiltonian including crystal-field and isotropic exchange interaction terms. A two-dimensional mean-field theory is evaluated to calculate single-crystal magnetization curves. It is shown that the magnetic properties can be understood using...

  18. Autologous Stem Cell Transplant for AL Amyloidosis

    Directory of Open Access Journals (Sweden)

    Vivek Roy

    2012-01-01

    Full Text Available AL amyloidosis is caused by clonal plasma cells that produce immunoglobulin light chains which misfold and get deposited as amyloid fibrils. Therapy directed against the plasma cell clone leads to clinical benefit. Melphalan and corticosteroids have been the mainstay of treatment for a number of years and the recent availability of other effective agents (IMiDs and proteasome inhibitors has increased treatment options. Autologous stem cell transplant (ASCT has been used in the treatment of AL amyloidosis for many years. It is associated with high rates of hematologic response and improvement in organ function. However, transplant carries considerable risks. Careful patient selection is important to minimize transplant related morbidity and mortality and ensure optimal patient outcomes. As newer more affective therapies become available the role and timing of ASCT in the overall treatment strategy of AL amyloidosis will need to be continually reassessed.

  19. Thermal Properties of Al-50%Si Alloys

    Institute of Scientific and Technical Information of China (English)

    Akio Nishimoto; Katsuya Akamatsu; Kazuyoshi Nakao; Kazuo Ichii

    2004-01-01

    In order to prepare a hypereutectic Al-Si alloy with low coefficients of thermal expansion (CTE), Al-50was produced by powder metallurgy (P/M) and ingot metallurgy (I/M). P/M specimen was prepared by mechanical alloying(MA) and pulsed electric-current sintering (PECS). The microstructures of specimens were characterized by optical microscopy and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). Vickers microhardness and CTE measurements were performed. The grains in the P/M specimen were refined with increasing MA time. Primary Si and eutectic Si in the I/M specimen were remarkably refined by adding minute amounts of Sr. The CTE of P/M and I/M specimens were estimated as 7.8×10-6 and 10.7×10-6, respectively. These values were as same as a CTE of Al2O3 ceramics.

  20. Kritik Terhadap Pemikiran Tasawuf Al-Raniri

    Directory of Open Access Journals (Sweden)

    Syaifan Nur

    2013-12-01

    Full Text Available Abstract : Al-Raniri is often positioned by some scholars as “superior” figure, which is contrasted to Hamzah Fansuri and Syamsuddin Sumaterani, and that is why they predicate him as one of pioneer of Islamic reformer in Malay- Indonesian archipelago. Anti-wujūdiyyah Sufism campaign by al-Raniri quite successful to some extent to amputate the rate of development of philosophical Sufism was brought by Fansuri and Sumaterani in the one hand, and strike off the nature of moral Sufism in the other, redeemed by bloodshed. This article discussed the “superiority” of al-Raniri’s thought of Sufism, viewed from a broader spectrum, either in relation to problems of faith or theology and politics surrounding the circumstance of his time.Keywords : Philosophical tasawuf, neo-sufism, panteism, tajalli, God’s attributeAbstrak : Al-Raniri oleh banyak kalangan seringkali diposisikan sebagai tokoh “superior” yang diperlawankan dengan Hamzah Fansuri dan Syamsuddin Sumaterani, dan itu sebabnya para ahli memberinya predikat sebagai seorang pelopor pembaru (mujaddid Islam di Nusantara. Anti tasawuf wujūdiyyah yang dikampanyekan oleh al-Raniri cukup berhasil mengamputasi laju perkembangan tasawuf falsafi yang dibawa oleh Fansuri dan Sumaterani di satu sisi, dan melancarkan laju corak tasawuf akhlaki di sisi lain, yang ditebus dengan cara pertumpahan darah. Tulisan ini mendiskusikan “superioritas” pemikiran tasawuf al-Raniri tersebut, dilihat dari spektrum yang lebih luas, baik menyangkut persoalan keyakinan atau teologi maupun politik yang mengitari situasi zamannya.Kata kunci : Tasawuf falsafi , neo-sufisme, panteisme, tajalli, sifat Tuhan

  1. Fabrication of Al-Al3Ti/Ti3Al Functionally Graded Materials under a Centrifugal Force

    Directory of Open Access Journals (Sweden)

    Yoshimi Watanabe

    2010-09-01

    Full Text Available Fabrication of Al-Al3Ti functionally graded materials (FGMs under the centrifugal force has recently attracted some attention. The controlled compositional gradient of the fabricated FGMs, the low cost of the process, and the good mold filling, are the main advantages of the centrifugal method (CM. Using the conventional CM techniques such as the centrifugal solid-particle method and centrifugal in-situ method, FGMs rings with gradually distributed properties could be achieved. As a more practical choice, the centrifugal mixed-powder method (CMPM was recently proposed to obtain FGMs containing nano-particles selectively dispersed in the outer surface of the fabricated parts. However, if a control of the particles morphology, compound formulas or sizes, is desired, another CM technique is favored. As a development of CMPM, our novel reaction centrifugal mixed-powder method (RCMPM has been presented. Using RCMPM, Al‑Al3Ti/Ti3Al FGMs with good surface properties and temperature controlled compositional gradient could be achieved. In this short review, this novel method will be discussed in detail and the effect of RCMPM processing temperature on the reinforcement particles morphology, size and distribution through the fabricated samples, will be reviewed.

  2. Total energy, equation of state and bulk modulus of AlP, AlAs and AlSb semiconductors

    Indian Academy of Sciences (India)

    A R Jivani; H J Trivedi; P J Gajjar; A R Jani

    2005-01-01

    Recently proposed model potential which combines both linear and quadratic types of interactions is employed for the investigation of some properties like the total energy, equation of state and bulk modulus of AlP, AlAs and AlSb semiconductor compounds using higher-order perturbation theory. The model potential parameter is determined using zero pressure condition. The ratio of the covalent bonding term E cov to the second-order term 2 is 6.77% to 11.85% which shows that contribution from higher order terms are important for zinc-blende-type crystals. The calculated numerical results of the total energy, energy band gap at Jones-zone face and bulk modulus of these compounds are in good agreement with the experimental data and found much better than other such theoretical findings. We have also studied pressure–volume relations of these compounds. The present study is carried out using six different screening functions along with latest screening function proposed by Sarkar et al. It is found from the present study that effect of exchange and correlation is clearly distinguishable.

  3. Diffusion AlSi-MeCrAlY coatings obtained on intermetallic γ-TiAl phase

    Directory of Open Access Journals (Sweden)

    M. Góral

    2012-12-01

    Full Text Available Purpose: The development of new protective coatings for TiAl intermetallics was conducted. The MeCrAlYAlSi slurry was used with different amount of aluminium-silicon powder in the binder.Design/methodology/approach: The slurry consisting of aluminium and silicon powder with the addition of MeCrAlY powder were used during the procedure. The inorganic solution made from chromic and phosphoric acid was applied as a binder. The preliminary research of microstructure of obtained coatings was conducted.Findings: The obtained coating consisting of 3 or 4 zones (depending on chemical composition of the slurry was obtained during the annealing process (950°C/4h.Research limitations/implications: The research results revealed the possibility of obtaining coatings with complex phase and chemical composition.Practical implications: Many problems connected with sedimentation of heavier MeCrAlY powder were observed.Originality/value: The copletele new technologies was described in article

  4. Melting, Processing, and Properties of Disordered Fe-Al and Fe-Al-C Based Alloys

    Science.gov (United States)

    Satya Prasad, V. V.; Khaple, Shivkumar; Baligidad, R. G.

    2014-09-01

    This article presents a part of the research work conducted in our laboratory to develop lightweight steels based on Fe-Al alloys containing 7 wt.% and 9 wt.% aluminum for construction of advanced lightweight ground transportation systems, such as automotive vehicles and heavy-haul truck, and for civil engineering construction, such as bridges, tunnels, and buildings. The melting and casting of sound, porosity-free ingots of Fe-Al-based alloys was accomplished by a newly developed cost-effective technique. The technique consists of using a special flux cover and proprietary charging schedule during air induction melting. These alloys were also produced using a vacuum induction melting (VIM) process for comparison purposes. The effect of aluminum (7 wt.% and 9 wt.%) on melting, processing, and properties of disordered solid solution Fe-Al alloys has been studied in detail. Fe-7 wt.% Al alloy could be produced using air induction melting with a flux cover with the properties comparable to the alloy produced through the VIM route. This material could be further processed through hot and cold working to produce sheets and thin foils. The cold-rolled and annealed sheet exhibited excellent room-temperature ductility. The role of carbon in Fe-7 wt.% Al alloys has also been examined. The results indicate that Fe-Al and Fe-Al-C alloys containing about 7 wt.% Al are potential lightweight steels.

  5. Adhesion of metal carbide/nitride interfaces: Al/TiC and Al/TiN

    Science.gov (United States)

    Liu, L. M.; Wang, S. Q.; Ye, H. Q.

    2003-12-01

    We employ density functional theory to investigate and compare Al/TiC and Al/TiN interfaces by electronic structures, relaxed atomic geometries and adhesions. The results show that the preferred bonding site is the interfacial Al atoms above the ceramic's metalloid atoms for both systems. The calculated adhesion energies are quantitatively in agreement with other calculated and experimental results of Al on the carbide and nitride. A detailed comparison of the adhesion energies and relaxed structures shows weaker bonding and less relaxation in the Al/nitride case, which is correlated with the lower surface energy of the ceramic. We have thoroughly characterized the electronic structure and determined that the polar covalent Al3sp-C(N)2s bonds constitute the primary interfacial bonding interaction. The larger overlapping bonding states at the Al/TiC interface reveal the reason why it exhibits relatively larger adhesion energy. Cleavage may take place preferentially at the interface, especially for the Al/TiN, which is in agreement with experimental results.

  6. Adhesion of metal-carbide/nitride interfaces: Al/TiC and Al/TiN

    International Nuclear Information System (INIS)

    We employ density functional theory to investigate and compare Al/TiC and Al/TiN interfaces by electronic structures, relaxed atomic geometries and adhesions. The results show that the preferred bonding site is the interfacial Al atoms above the ceramic's metalloid atoms for both systems. The calculated adhesion energies are quantitatively in agreement with other calculated and experimental results of Al on the carbide and nitride. A detailed comparison of the adhesion energies and relaxed structures shows weaker bonding and less relaxation in the Al/nitride case, which is correlated with the lower surface energy of the ceramic. We have thoroughly characterized the electronic structure and determined that the polar covalent Al3sp-C(N)2s bonds constitute the primary interfacial bonding interaction. The larger overlapping bonding states at the Al/TiC interface reveal the reason why it exhibits relatively larger adhesion energy. Cleavage may take place preferentially at the interface, especially for the Al/TiN, which is in agreement with experimental results

  7. InAlGaAs/AlGaAs quantum wells: line widths, transition energies and segregation

    DEFF Research Database (Denmark)

    Jensen, Jacob Riis; Hvam, Jørn Märcher; Langbein, Wolfgang

    2000-01-01

    We investigate the optical properties of InAlCaAs/AlGaAs quantum wells pseudomorphically grown on GaAs using molecular beam epitaxy (MBE). The transition energies, measured with photoluminescence (PL), are modelled solving the Schrodinger equation, and taking into account segregation in the group...

  8. Introducción al derecho

    OpenAIRE

    Collado Luis, Santiago

    2012-01-01

    Manual de la asignatura introducción al derecho. Nivel educativo: Grado El origen de este texto –materiales docentes- que lleva por título “Introducción al Derecho” ha sido escrito respondiendo a una estricta necesidad docente y por tanto necesariamente pedagógica. En efecto, era totalmente necesario que los alumnos, del Grado de Administración y Dirección de Empresas y otras titulaciones no jurídicas, contasen con un texto para facilitar el estudio de las principales categorías conceptual...

  9. Quadrupole scattering in PrAl2

    Science.gov (United States)

    Sablik, M. J.; Pureur, P.; Creuzet, G.; Fert, A.; Levy, P. M.

    1983-10-01

    We derive the spontaneous anisotropy of the resistivity of the ferromagnetic compound PrAl2 from magnetoresistance measurements on a single crystal of PrAl2. We ascribe this spontaneous anisotropy of the resistivity to scattering of the conduction electrons by the thermal quadrupole disorder and we account for our experimental results by using the theoretical model previously developed by us. We find that quadrupole scattering gives a very important contribution to the total magnetic disorder (spin and quadrupole) resistivity but that only a small part of this quadrupole contribution is anisotropic.

  10. Amyotrofisen lateraaliskleroosin (ALS) fysioterapia : Systemaattinen kirjallisuuskatsaus

    OpenAIRE

    Finne, Ida

    2015-01-01

    Amyotrofinen lateraaliskleroosi eli ALS on harvinainen motoneuronisairaus, jonka ominaispiirteenä on selkäytimen, aivorungon ja aivokuoren motoneuroneiden etenevä degeneraatio ja tuhoutuminen. Tähän parantumattomaan sairauteen sairastuu Suomessa vuosittain noin 120–150 henkilöä. Keskimääräinen sairastumisikä on noin 60 vuotta ja elinikä diagnoosin saamisen jälkeen on noin 3 - 5 vuotta. Fysioterapia on tärkeä osa ALS-potilaan hoitoa ja kuntoutusta. Fysioterapian vaikutut-tavuutta on tästä ...

  11. Aspectos biopsicosociales asociados al embarazo adolescente

    OpenAIRE

    Regina Cogollo Jiménez

    2012-01-01

    Introducción: El embarazo en la adolescencia, es un evento inesperado, sorpresivo. Este artículo establece la importancia de identificar los aspectos biopsicosociales asociados al embarazo adolescente en las embarazadas asistentes al programa de Control Prenatal de una Empresa Social del Estado de nivel 1 en Montería en 2009, para comprender las actitudes y los comportamientos asociados a esta etapa tan temprana. Materiales y Métodos: Es un estudio descriptivo, cuantitativo, de corte transver...

  12. Recent research highlights from the ALS OML

    OpenAIRE

    Yashchuk, Valeriy V.

    2013-01-01

    The main mission of the Optical Metrology Laboratory (OML) at the Advanced Light Source (ALS) is to ensure state-of-the-art performance of beamline optics. New beamlines and instruments laid out in the ALS strategic plan as well as the plan for New Generation Light Source (NGLS) facility all involve increasingly complex optical systems that need ultra-high precision optics to achieve the specifications and goals of their state-of-the art research programs. In order to manufacture, measure, tu...

  13. The wobbler mouse, an ALS animal model

    DEFF Research Database (Denmark)

    Moser, Jakob Maximilian; Bigini, Paolo; Schmitt-John, Thomas

    2013-01-01

    This review article is focused on the research progress made utilizing the wobbler mouse as animal model for human motor neuron diseases, especially the amyotrophic lateral sclerosis (ALS). The wobbler mouse develops progressive degeneration of upper and lower motor neurons and shows striking...... disease mechanism and testing various therapeutic approaches and discuss the relevance of these advances for human ALS. The identification of the causative mutation linking the wobbler mutation to a vesicle transport factor and the research focussed on the cellular basis and the therapeutic treatment of...

  14. The ALS Storage Ring RF System

    International Nuclear Information System (INIS)

    The ALS Storage Ring RF System is characterized by the use of the following features: (1) High power loading of two single cell cavities. (2) The use of a tubular ceramic input window employing aperture coupling. (3) The use of waveguide filters and matchers designed for HOM absorption. (4) A comprehensive HOM monitoring system. (5) The use of waveguide water-wedge loads for the magic tee and circulator loads. The results of cavity measurements and high power tests are reported together with the performance of the system during the commissioning and operation phases of the ALS project. Plans for future window development are discussed

  15. Al-Yawahir Al-Saniyya Fi Sarh-Al-Yarrumiyya, de Al-Ta c Alibi (s.VII-XIV)

    OpenAIRE

    Bellachehab, Ahmed

    1994-01-01

    Edición critica, realizada sobre varios manuscritos, de una interesante fuente gramatical magrebi, del siglo VIII de la hégira XIV de nuestra era. Estudio sobre el autor, at-ta alibi, típico gramático tardío del norte de África, y estudio sobre su producción escrita, en general y en concreto sobre este al-yawahir al-saniyya que es un interesante comentario de la celebre yarrumiyya, comentario hasta hoy inédito que representa un hito en la tradición de estudios gramaticales del occidente islám...

  16. Metamagnetism in Ce(Ga,Al)2

    Indian Academy of Sciences (India)

    K G Suresh; S Radha; A K Nigam

    2002-05-01

    Effect of Al substitution on the magnetic properties of Ce(Ga1-Al)2 ( = 0, 0.1 and 0.5) system has been studied. The magnetic state of CeGa2 is found to be FM with a C of 8 K, whereas the compounds with =0.1 and 0.5 are AFM and possess N of about 9 K. These two compounds undergo metamagnetic transition and the critical fields are about 1.2 T and 0.5 T, respectively at 2 K. These variations are explained on the basis of helical spin structure in these compounds.

  17. Periodistas: el acceso al mercado laboral

    OpenAIRE

    2006-01-01

    El presente estudio analiza la situación profesional de los Licenciados en Periodismo en España. Para ello esta investigación sigue la lógica del proceso de acceso al mercado laboral, es decir, se estudia, en primer lugar, la oferta de egresados y las demandas del sector; a continuación, se analiza la forma en la que un titulado en la Licenciatura de Periodismo accede al mercado laboral y el tiempo que tarda en hacerlo; y por último, se examinan los medios de comunicación en lo...

  18. Surface phonon polariton characteristics of In(0.04)Al(0.06)Ga(0.90)N/AlN/Al(2)O(3) heterostructure.

    Science.gov (United States)

    Ng, S S; Lee, S C; Bakhori, S K Mohd; Hassan, Z; Abu Hassan, H; Yakovlev, V A; Novikova, N N; Vinogradov, E A

    2010-05-10

    Surface phonon polariton (SPP) characteristics of In(0.04)Al(0.06)Ga(0.90)N/AlN/Al(2)O(3) heterostructure are investigated by means of p-polarized infrared (IR) attenuated total reflection spectroscopy. Two absorption dips corresponding to In(0.04)Al(0.06)Ga(0.90)N SPP modes are observed. In addition, two prominent dips and one relatively weak and broad dip corresponding to the Al(2)O(3) SPP mode, In(0.04)Al(0.06)Ga(0.90)N/Al(2)O(3) interface mode, and Al(2)O(3) bulk polariton mode, respectively, are clearly seen. No surface mode feature originating from the AlN layer is observed because it is too thin. Overall, the observations are in good agreement with the theoretical predictions. PMID:20588890

  19. Microstructural defects modeling in the Al-Mo system

    International Nuclear Information System (INIS)

    In this work we have utilized computer simulation techniques to study microstructural defects, such as point defects and interfaces, in the Al-Mo alloy. Such alloy is taken as a model to study the Al(fcc)/U-Mo(bcc) interface. The EAM interatomic potential used has been fitted to the formation energy and lattice constant of the AlMo3 intermetallic. Formation of vacancies for both components Al and Mo and anti-sites, AlMo and MoAl, as well as vacancy migration was studied in this structure. We found that the lowest energy defect complex that preserves stoichiometry is the antisite pair AlMo+MoAl, in correspondence with other intermetallics of the same structure. Our results also suggest that the structure of the Al(fcc)/Mo(bcc) interface is unstable, while that of the Al(fcc)/Al5Mo interface is stable, as observed experimentally. (author)

  20. Liquidus temperatures of Na3AlF6-AlF3-CaF2-KF-LiF-Al2O3 melts

    Directory of Open Access Journals (Sweden)

    Peng J.P.

    2014-01-01

    Full Text Available Temperatures for the primary crystallization of Na3AlF6-AlF3-CaF2-KF-LiF-Al2O3 system adopted in aluminum electrolysis process were determined by thermal analysis. An empirical equation was derived to describe the liquidus temperatures for the primary crystallization of this multicomponent electrolyte system: t/℃=1011 + 0.7w(AlF3 - 0.232w(AlF32 - 7.65w(Al2O3 + 0.523w(Al2O32 - 8.96w(LiF + 0.043w(LiF2 - 3.32w(KF - 0.12w(KF2 - 3.28w(CaF2 +0.037w(CaF22 + 0.091w(AlF3w(LiF + 0.074w(AlF3w(KF + 0.084w(AlF3w(CaF2 - 0.27w(Al2O3w(LiF, where w(AlF3 denotes the mass fraction of excess aluminum fluoride with respect to cryolite. While w(Al2O3 ranges from 2% to 4%, w(LiF, w(KF and w(CaF2 from 0 to 7%, and the molar ratio of NaF/AlF3 from 2.2 to 3.

  1. An impedance study of complex Al/Cu-Al{sub 2}O{sub 3} electrode

    Energy Technology Data Exchange (ETDEWEB)

    Denisova, J; Katkevics, J; Viksna, A [Faculty of Chemistry, University of Latvia, Kr. Valdemara Str. 48, Riga, LV-1013 (Latvia); Erts, D, E-mail: arturs.viksna@lu.lv [Institute of Chemical Physics, University of Latvia, Kronvalda blvd. 4, Riga, LV-1586 (Latvia)

    2011-06-23

    Electrochemical impedance spectroscopy (EIS) was used to investigate different Cu deposition regimes on Al surface obtained by internal electrolysis and to characterize properties of fabricated electrodes. EIS experimental data confirmed that Cu deposition by internal electrolysis is realized and the complex electrode system is obtained. The main difficulty in preparation of Al/Cu electrodes is to prevent aluminium oxidation before and during electrochemical deposition of Cu particles. In this work NaCl, CH{sub 3}COONa, K{sub 2}SO{sub 4}, mono- and diammonium citrate electrolytes were examined to determine their suitability for impedance measurements. Al/Cu-Al{sub 2}O{sub 3} electrode composition was approved by equivalent circuit analysis, optical and scanning electron microscope methods. The most optimal Cu deposition mode using internal electrolysis was determined. The obtained results are promising for future electrochemical fabrication of nanostructures directly on Al surfaces by internal electrolysis.

  2. FABRICATION OF Al/Al2O3 FGM ROTATING DISC

    Directory of Open Access Journals (Sweden)

    A. B. Sanuddin

    2012-06-01

    Full Text Available This study presents a method of fabricating a disc made of Al/Al2O3 functionally graded materials (FGM, using a powder metallurgy manufacturing process. The aim is to develop a processing method for a rotating disc made of FGM, by stacking the slurry, layer by layer in a radial direction. A three-layer functionally graded material of Al/Al2O3 is fabricated with compositions of 10, 20, 30 vol.% Al2O3. The ceramic composition increases from the discs inner (centre to the outer. The combination of these materials can offer the ability to withstand high temperature conditions whilst maintaining strength in extreme environments.

  3. In situ microscopy of rapidly heated nano-Al and nano-Al/WO3 thermites

    Science.gov (United States)

    Sullivan, Kyle T.; Chiou, Wen-An; Fiore, Richard; Zachariah, Michael R.

    2010-09-01

    The initiation and reaction mechanism of nano-Al and nano-Al thermites in rapid heating environments is investigated in this work. A semiconductor-based grid/stage was used, capable of in situ heating of a sample from room temperature to 1473 K, and at a rate of 106 K/s, inside an electron microscope. Nano-Al was rapidly heated in a transmission electron microscope, and before and after images indicate that the aluminum migrates through the shell, consistent with a diffusion-based mechanism. A nano-Al/WO3 composite was then heated in a scanning electron microscope. The results indicate that a reactive sintering mechanism is occurring for the nano-Al/WO3 thermite, as the products are found to be in surface contact and significantly deformed after the heating pulse.

  4. Serious Flaws in Korf et al.'s Analysis on Time Complexity of A*

    CERN Document Server

    Dinh, Hang

    2008-01-01

    Understanding the effect of a heuristic on the time complexity of the well-known A* search algorithm has been a subject of a large research body in AI. Among those researches is Korf et al.'s analysis (Korf & Reid, 1998; Korf et al., 2001; Korf, 2000a; Korf, 2000b), which concluded that the effect of a heuristic is to reduce the effective depth rather than effective branching factor. Since this conclusion conflicts with both previous analysis and recent analysis by other authors, we try to investigate the causes of such contradictions and finally find out that Korf et al.'s analysis has many serious flaws from which their main conclusion was drawn.

  5. Tensile deformation behavior of a sub-micrometer Al2O3/6061Al composite

    International Nuclear Information System (INIS)

    A 0.3 μm Al2O3/6061Al composite with 33% volume fraction of Al2O3 was fabricated by the patented squeeze-casting technology. The tensile properties were studied, and the dynamic tensile deformation behavior was investigated by an in situ TEM tensile technique. The as-cast composite exhibits excellent tensile properties with a fracture strength of 504 MPa, and the strength increases to 579 MPa after a T6 treatment. The high strength is mainly attributed to the dispersion strengthening effect of the finer sub-micrometer Al2O3 particles. Dynamic transmission electron microscopy indicates that micro-cracks initiate and propagate mainly in the matrix. The Al2O3 particles can hinder the growth and deflect the cracks, but the resistance of the particles to crack propagation is small. The propagation stage is accordingly short, leading to the fracture of the composite

  6. Different magnetic behaviour of the Kondo compounds Al3Ce and Al11Ce3

    International Nuclear Information System (INIS)

    Neutron diffraction experiments on the Al3Ce and Al11Ce3 compounds have been performed on the multidetector of the I.L.L. high flux reactor. No magnetic structure has been detected on the Al3Ce compound down to 20 mK. This confirms the non magnetic ground state of Al3Ce. For Al11Ce3, two magnetic structures have been observed: a ferromagnetic one at 4.2 K and an antiferromagnetic one at 2 K. The antiferromagnetic structure, which corresponds to a propagation vector (0,0,1/3), implies a strong reduction of the magnetic moment of determined sites; this reflects the Kondo character of the compounds

  7. InAlGaAs/AlGaAs quantum wells: line widths, transition energies and segregation

    DEFF Research Database (Denmark)

    Jensen, Jacob Riis; Hvam, Jørn Märcher; Langbein, Wolfgang

    We investigate the optical properties of InAlCaAs/AlGaAs quantum wells pseudomorphically grown on GaAs using molecular beam epitaxy (MBE). The transition energies, measured with photoluminescence (PL), are modelled solving the Schrodinger equation, and taking into account segregation in the group...... III sublattice. From a fit to the transition energies, an empirical band gap relation for InAlGaAs is found, in the composition range relevant for growth on GaAs. The PL lines at low temperature (T = 10 K) are broadened due to random alloy fluctuations and an interface roughness of 1.1 monolayers....... Finally, the use of InAlGaAs/AlGaAs quantum wells for making strained T-shaped quantum wires is demonstrated. (C) 2000 Elsevier Science B.V. All rights reserved....

  8. Effect of stress on the Al composition evolution in AlGaN grown using metal organic vapor phase epitaxy

    Science.gov (United States)

    He, Chenguang; Qin, Zhixin; Xu, Fujun; Zhang, Lisheng; Wang, Jiaming; Hou, Mengjun; Zhang, Shan; Wang, Xinqiang; Ge, Weikun; Shen, Bo

    2016-05-01

    Two series of AlGaN samples with different stresses were designed to investigate the effect of stress on the Al composition. X-ray diffraction reciprocal space mapping (XRD RSM) demonstrated that the AlGaN epilayers with different stresses have large Al composition differences despite the same growth conditions. The largest Al composition difference reached up to 21.3%, which was also confirmed using secondary ion mass spectroscopy (SIMS). This result is attributed to a large stress discrepancy in the AlGaN epilayers. Finally, the dependences of the solid-phase Al composition on the gas-phase Al composition under different stresses were systematically analyzed.

  9. The constitution of alloys in the Al-rich corner of the Al-Si-Sm ternary system

    International Nuclear Information System (INIS)

    The constitution of alloys and the liquidus surface in the Al-rich corner of the Al-Si-Sm ternary system were determined by the examination of controlled heated and cooled specimens, as well as heat-treated specimens by means of optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, differential thermal analysis and X-ray diffraction. The Al-rich corner of the Al-Si-Sm ternary system comprises five regions of primary crystallisation (αAl, βSi, Al3Sm, Al2Si2Sm and AlSiSm) with following characteristic invariant reaction sequences: ternary eutectic reaction L → αAl + βSi + Al2Si2Sm, and two liquidus transition reactions, i. e., L + Al3Sm → αAl + AlSiSm, and L + AlSiSm → αAl + Al2Si2Sm. Along with the position of ternary eutectic and both interstitial points in the Al-rich corner of the Al-Si-Sm ternary system, the temperatures for each reaction were determined. (orig.)

  10. Microscopic phase field study of the antisite defect of Ni3 Al in binary Ni-Al alloys

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The temporal evolution feature of a microscopic phase field model is utilized to study the antisite defects of L1 2-Ni 3 Al;this is quite different from other physicist’ interests.There are mainly two points in brief.Firstly,antisite defects Ni Al and Al Ni ,which are caused by the deviation from the stoichiometric Ni 3 Al,coexist in the Ni 3 Al phase.The surplus Ni atom in the Ni-rich side is prone to substitute Al thus producing the antisite defect Ni Al that maintains the stability of the L1 2 structure.In other case,the surplus Al atom in the Al-rich side is accommodated by a Ni sublattice consequently giving rise to antisite defect Al Ni .The calculated equilibrium occupancy probability of Ni Al is much higher than that of Al Ni .This point is generally in line with other theoretical and experimental works.Additionally,both Ni Al and Al Ni have a strong negative correlation to time step during the disorder-order transformation.Since the initial value of Ni Al and Al Ni on each site of the matrix is right at the concentration that we set,we can observe the decrease process of Ni Al and Al Ni from the initial disordered high anti-structure state to their respective equilibrium state,i.e.to the result of the ordering process further coarsening.

  11. The modulation structure induced changes in mechanical properties of TiAlN/Al2O3 multilayers

    International Nuclear Information System (INIS)

    TiAlN/Al2O3 multilayers which had different separate layer thickness of TiAlN or Al2O3 were synthesized by sputtering Ti3Al and Al2O3 targets with N2 and Ar gases. The influence of modulation periods and modulation ratios on structure and properties of TiAlN/Al2O3 multilayers was investigated using scanning electron microscopy, X-ray diffraction, X-ray Photoelectron Spectroscopy, surface profiler, and nanoindenter. Compared to TiAlN layer with only (2 0 0) preferred orientation, TiAlN/Al2O3 multilayers were crystallized with orientations in the TiAlN (1 1 1), TiAlN (2 2 2) and AlN (1 0 0). Besides, weak Al2O3 (0 2 2) orientation is observed, when modulation period is 8.9 nm. The maximum hardness about 36.6 GPa was obtained at modulation period of 10.4 nm and modulation ratio of 10:1. The hardness and the toughness of TiAlN/Al2O3 multilayers increase as individual TiAlN layer thickness increases

  12. Wear characteristics of Al-AlN composites produced in-situ by nitrogenation

    Science.gov (United States)

    Pradhan, S.; Jena, S. K.; Patnaik, S. C.; Swain, P. K.; Majhi, J.

    2015-02-01

    In the present scenario most of the parts used in automobile and aerospace industries are made of composites. Aluminium metal has a very high strength to weight ratio. Al-AlN metal matrix composites have excellent mechanical properties like good wear resistance, high hardness and high strength to weight ratio which are obtained from low density of aluminium and high hardness and wear resistance of AlN. Therefore, use of Al-AlN MMC leads to advantages in automobile industries as it reduces fuel consumption and gives better structural strength. The composites can be produced ex-situ by introducing AlN as reinforcement into the metal matrix and in- situ by nitrogenation process. In the present process Al-AlN composites were fabricated by treating molten aluminium with a mixture of CaO and NH4Cl and held at temperature range at 750-930°C and then cast into a metal mould. Addition of CaO to NH4Cl is found to have a more pronounced effect as a nitrogenation agent in comparison with NH4Cl in the molten aluminium in the temperature range of 700- 1000°C. Castings of aluminium and Al-AlN composites were prepared by mixing different ratios of aluminium and NH4Cl, at different casting temperatures and holding time. Wear resistance and hardness of the samples were determined, and microstructure studies were carried out. The composite formed using higher amount of NH4Cl had higher hardness and wear resistance.

  13. AlON的合成工艺%Synthesis technology of AlON

    Institute of Scientific and Technical Information of China (English)

    王习东; 李文超

    2001-01-01

    分析了合成AlON的各种方法。 用模式识别结 合神经网络对碳热还原氮化合成AlON工艺 进行了优化, 利用模式逆映射得到了理想的合成工艺参数。 对AlON体系进行了热力学初步 分析, 计算了温度为2  073  K时合成AlON的热力学参数状态图。 根据热力学参数状态图所确定的条件, 热压合成了AlON陶瓷。 对所合成的AlON试样进行了 X 射线衍射标定及部分物理性能的测定。 其密度为3.63  g/cm3, 约为其理论 密度的97.8%。%The synthesis technolog y of AlON ceramics was investigated. The program o f pattern recognition was used to optimize the parameters of AlON synthesi s process, and the proper parameters were obtained by inverse projection. The th ermodynamic properties of AlON were preliminary analyzed and estimate d, phase stability diagrams at 2  073  K were calculated. A lON ceramics was synthesized by hot-press sintering under the conditions given by phase stability diagram. The density of AlON is 3.63  g/cm3, about 97.8% of its th eoretic d ensity.

  14. Microstructure of Ni-Al powder and Ni-Al composite coatings prepared by twin-wire arc spraying

    Science.gov (United States)

    Wang, Ji-xiao; Wang, Gui-xian; Liu, Jing-shun; Zhang, Lun-yong; Wang, Wei; Li, Ze; Wang, Qi-xiang; Sun, Jian-fei

    2016-07-01

    Ni-Al powder and Ni-Al composite coatings were fabricated by twin-wire arc spraying (TWAS). The microstructures of Ni-5wt%Al powder and Ni-20wt%Al powder were characterized by scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the obtained particle size ranged from 5 to 50 μm. The morphology of the Ni-Al powder showed that molten particles were composed of Ni solid solution, NiAl, Ni3Al, Al2O3, and NiO. The Ni-Al phase and a small amount of Al2O3 particles changed the composition of the coating. The microstructures of the twin-wire-arc-sprayed Ni-Al composite coatings were characterized by SEM, EDS, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that the main phase of the Ni-5wt%Al coating consisted of Ni solid solution and NiAl in addition to a small amount of Al2O3. The main phase of the Ni-20wt%Al coating mainly consisted of Ni solid solution, NiAl, and Ni3Al in addition to a small amount of Al and Al2O3, and NiAl and Ni3Al intermetallic compounds effectively further improved the final wear property of the coatings. TEM analysis indicated that fine spherical NiAl3 precipitates and a Ni-Al-O amorphous phase formed in the matrix of the Ni solid solution in the original state.

  15. Study of the 27Al(n,2,)26Al reaction via accelerator mass spectrometry

    International Nuclear Information System (INIS)

    The excitation function for the 27Al(n,2n)26Al reaction is expected to show a strongly non-linear behavior in the neutron-energy region around 14 MeV, the neutron energy in D-T plasmas; thus the production rate of 26Al (t1/2=7.2*105 a) in D-T fusion environments can in principle be used to measure the temperature of such plasmas. Existing measurements, however, are strongly discordant. Therefore, a new accurate measurement of the 27Al(n,2n)26Al cross sections in the near threshold region (En=13.5-14.8 MeV) was performed with the goal to achieve relative cross sections with the highest accuracy possible. In addition, the measurements were also designed to provide good absolute cross-section values, as absolute cross sections are important for radioactive waste predictions. Samples of Al metal were irradiated with neutrons in the energy range near threshold (Eth=13.55 MeV) at the Radiuminstitutes of both Vienna and St. Petersburg, and in Tokai-mura, Japan. In Tuebingen irradiations with neutrons of higher energies (17 and 19 MeV) were performed. The amount of 26Al produced during the irradiations was measured via accelerator mass spectrometry (AMS) at the Vienna Environmental Research Accelerator (VERA). This work represents the first 26Al measurements for this new facility. With this system, a background as low as 3*10-15 for 26Al/27Al isotope ratios was obtained, corresponding to a (n,2n) cross section of 0.04 mb. Utilizing AMS, cross sections with much higher precision and considerably closer to the threshold than in previous investigations could be measured. The prerequisite for its application as a temperature monitor, namely a very well known shape of the excitation function was met. A quantitative prediction of the sensitivity of this method for monitoring the temperature in a D-T fusion plasma was therefore possible. For thermal plasmas temperature changes in the order of 5 to 15 % should be detectable. An even higher sensitivity was found for non

  16. Management of respiratory symptoms in ALS.

    LENUS (Irish Health Repository)

    Hardiman, Orla

    2011-03-01

    Respiratory insufficiency is a frequent feature of ALS and is present in almost all cases at some stage of the illness. It is the commonest cause of death in ALS. FVC is used as important endpoint in many clinical trials, and in decision-making events for patients with ALS, although there are limitations to its predictive utility. There are multiple causes of respiratory muscle failure, all of which act to produce a progressive decline in pulmonary function. Diaphragmatic fatigue and weakness, coupled with respiratory muscle weakness, lead to reduced lung compliance and atelectasis. Increased secretions increase the risk of aspiration pneumonia, which further compromises respiratory function. Bulbar dysfunction can lead to nutritional deficiency, which in turn increases the fatigue of respiratory muscles. Early recognition of respiratory decline and symptomatic intervention, including non-invasive ventilation can significantly enhance both quality of life and life expectancy in ALS. Patients with respiratory failure should be advised to consider an advance directive to avoid emergency mechanical ventilation.

  17. Al/Cl2 molten salt battery

    Science.gov (United States)

    Giner, J.

    1972-01-01

    Molten salt battery has been developed with theoretical energy density of 5.2 j/kg (650 W-h/lb). Battery, which operates at 150 C, can be used in primary mode or as rechargeable battery. Battery has aluminum anode and chlorine cathode. Electrolyte is mixture of AlCl3, NaCl, and some alkali metal halide such as KCl.

  18. 75 FR 1420 - Alabama Disaster # AL-00025

    Science.gov (United States)

    2010-01-11

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00025 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Alabama dated...

  19. 76 FR 29810 - Alabama Disaster #AL-00037

    Science.gov (United States)

    2011-05-23

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00037 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  20. 75 FR 26813 - Alabama Disaster #AL-00029

    Science.gov (United States)

    2010-05-12

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00029 AGENCY: Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Alabama...

  1. 78 FR 4967 - Alabama Disaster #AL-00046

    Science.gov (United States)

    2013-01-23

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00046 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of ALABAMA dated...

  2. 76 FR 62481 - Incapital LLC, et al.

    Science.gov (United States)

    2011-10-07

    ... From the Federal Register Online via the Government Publishing Office SECURITIES AND EXCHANGE COMMISSION Incapital LLC, et al.; Notice of Application September 30, 2011. AGENCY: Securities and Exchange Commission (``Commission''). ACTION: Notice of application for an order under section 12(d)(1)(J) of...

  3. 78 FR 22361 - Alabama Disaster #AL-00049

    Science.gov (United States)

    2013-04-15

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00049 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Alabama dated...

  4. 78 FR 26100 - Alabama Disaster #AL-00050

    Science.gov (United States)

    2013-05-03

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00050 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Alabama dated...

  5. 75 FR 3895 - Yale University, et al.;

    Science.gov (United States)

    2010-01-25

    ... notice at 74 FR 67851, December 21, 2009. Docket Number: 09-065. Applicant: U.S. Department of Homeland..., Quanta 200 FEG. Manufacturer: FEI Company, Czech Republic. Intended Use: See notice at 74 FR 67851... International Trade Administration Yale University, et al.; Notice of Consolidated Decision on Applications...

  6. 77 FR 7227 - Alabama Disaster #AL-00040

    Science.gov (United States)

    2012-02-10

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00040 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Alabama...

  7. 75 FR 474 - Alabama Disaster #AL-00026

    Science.gov (United States)

    2010-01-05

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00026 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  8. 76 FR 27141 - Alabama Disaster # AL-00036

    Science.gov (United States)

    2011-05-10

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00036 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Alabama...

  9. 77 FR 60003 - Alabama Disaster #AL-00044

    Science.gov (United States)

    2012-10-01

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00044 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  10. 75 FR 26814 - Alabama Disaster #AL-00031

    Science.gov (United States)

    2010-05-12

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00031 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  11. Casting of particulate Al-base composites

    Energy Technology Data Exchange (ETDEWEB)

    Moustafa, S.F. [CMRDI, Cairo (Egypt)

    1997-03-01

    A molten Al-4 wt.% Cu as well as a Al-13 wt.% Si alloy have been mixed mechanically with particulate of SiC, Al{sub 2}O{sub 3}, or graphite. After the completion of mixing, each mixture was poured into a permanent mould to solidify. To overcome the problem of non-wettability that exists between the investigated particulate and the molten aluminum alloys the particulate was chemically treated by impregnation in a solution containing Na{sup +} ions. The loading of SiC or Al{sub 2}O{sub 3} particulate in the produced composites can be as high as 40 wt.%, and for graphite particles it can be 20 wt.%. The mixing time required to introduce and distribute the investigated particles into the molten matrix was as low as five minutes to recluce chemical reactions at the interfaces between them. Processing details and parameters controlling this technique are described. Metallographic examinations as well as tensile tests were carried out to characterize the microstructure, the distribution of the particles and the strength of these composites. The results display that the composites made by this technique have good microstructure and tensile properties. (orig.)

  12. Synthesis of Ti-Al porous perform

    Directory of Open Access Journals (Sweden)

    K. Naplocha

    2008-02-01

    Full Text Available Purpose: Article describes production method of intermetallic porous perform for reinforcing of composite materials. Usefulness of the high temperature self-propagating synthesis (SHS, with appropriate modification, to produce perform for production of composite was evaluated.Design/methodology/approach: Mixture of aluminum and titanium powder was cold isostatically pressed (CIPed and produced cylindrical pill was ignited in microwave field. Obtained structure usually have open porosity what enables for pressure infiltration with molten metal. The investigations of the structure of preforms on the scanning electron microscope (SEM were made.Findings: The produced performs in most cases reveal open porosity, uniform morphology and are suitable for infiltration process. After reaction Al-Ti compounds form partly globular structure with microhardness much higher than substratesResearch limitations/implications: In the actual stages of this work proposed method can be used for manufacturing of porous performs, which mainly contain Al3Ti. During reaction, mixture compacts with the molar ratio of Al/Ti=1 were transformed into inhomogeneous structure.Practical implications: Obtained perform can be widely used as the reinforcement to produce hybrid composite materials by the infiltration method. Aluminum casting alloys can be locally reinforced to improve hardness and resistance to oxidization at high temperature.Originality/value: Article is valuable for persons engaged in production of casting composite materials reinforced with porous perform. Proposed method allows to incorporate hard structures from Al-Ti compounds into aluminum casting.

  13. Cathodic electrochemiluminescence at double barrier Al/Al{sub 2}O{sub 3}/Al/Al{sub 2}O{sub 3} tunnel emission electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Hakansson, Markus [Laboratory of Analytical and Inorganic Chemistry, Helsinki University of Technology, P.O. Box 6100, FIN-02015 HUT (Finland); Jiang, Qinghong [Laboratory of Analytical and Inorganic Chemistry, Helsinki University of Technology, P.O. Box 6100, FIN-02015 HUT (Finland); Suomi, Johanna [Laboratory of Analytical and Inorganic Chemistry, Helsinki University of Technology, P.O. Box 6100, FIN-02015 HUT (Finland); Loikas, Kari [Workshop, Department of Chemistry, University of Turku, FIN-20014 (Finland); Nauma, Mauri [Workshop, Department of Chemistry, University of Turku, FIN-20014 (Finland); Ala-Kleme, Timo [Laboratory of Analytical Chemistry, Department of Chemistry, University of Turku, FIN-20014 (Finland); Kankare, Jouko [Laboratory of Analytical Chemistry, Department of Chemistry, University of Turku, FIN-20014 (Finland); Juhala, Pentti [Laboratory of Analytical Chemistry, Department of Chemistry, University of Turku, FIN-20014 (Finland); Eskola, Jarkko U. [Labmaster Oy, P.O. Box 71, FIN-20521 Turku (Finland); Kulmala, Sakari [Laboratory of Analytical and Inorganic Chemistry, Helsinki University of Technology, P.O. Box 6100, FIN-02015 HUT (Finland)

    2006-01-25

    Double insulating barrier tunnel emission electrodes were fabricated by adding a new pure aluminum layer upon oxidized aluminum electrodes by vacuum evaporation and thermally oxidizing the new aluminum layer in air at room temperature. Resulting Al/Al{sub 2}O{sub 3}/Al/Al{sub 2}O{sub 3} electrodes allow the use of various aluminum alloys in the electrode body necessary for hardness or shaping ability of the electrode while obtaining the luminescence properties of pure aluminum oxide. During electrical excitation of luminescent labels by cathodic hot electron injection into aqueous electrolyte solution, the background noise is mainly based on high-field-induced solid-state electroluminescence and F-center luminescence of the outer aluminum oxide film. The more defect states and/or impurity centers the outer oxide film contains, the higher is the background emission intensity. The present electrode fabrication method provides a considerable improvement in signal-to-noise ratio for time-resolved electrochemiluminescence (TR-ECL) measurements when the original native oxide film of the electrode body contains luminescence centers displaying long-lived luminescence. The excellent performance of the present electrodes is demonstrated by extremely low-level detection of Tb(III) chelates, luminol, Pt(II) coproporphyrin and Tb(III) labels in an immunometric immunoassay by time-resolved electrochemiluminescence.

  14. CALCULUL CINETOSTATIC AL MECANISMELOR PLANETARE CILINDRICE

    Directory of Open Access Journals (Sweden)

    Păun ANTONESCU

    2012-05-01

    Full Text Available În lucrare se prezintă o metodă analitică pentru calculul cinetostatic al mecanismului planetarmonomobil cu două roţi dinţate centrale. Se consideră mai întâi cazul general al schemelor cinematice cu douăroţi dinţate solidare tip satelit, în două variante practice (multiplicator şi reductor de turaţie. Este menţionatcazul particular al mecanismelor planetare cu o singură roată satelit cu angrenare dublă (exterioară şiinterioară. Pe baza modelului de analiză cinetostatică a mecanismului planetar monomobil cu două roţi dinţatecentrale, în finalul lucrării se abordează o problemă practică de calcul cinetostatic al unui mecanism planetarcilindric simplu folosit la capul de frezat pentru prelucrarea roţilor dinţate cilindrice cu dinţi curbi înhipocicloidă.

  15. Cryptanalysis on Cheng et al. protocol

    Science.gov (United States)

    Thakur, Tejeshwari

    2016-06-01

    Deployment of new node in any wireless sensor network is a sensitive task. This is the reason why, an Access Control Protocol is required in WSN. In this paper, we demonstrate that Access Control Protocol proposed by Cheng et al.[1] for Wireless Sensor Network is insecure. The reason is that this protocol fails to resist the active attack.

  16. Del desarrollo rural al desarrollo territorial

    OpenAIRE

    Moyano Estrada, Eduardo

    2010-01-01

    5 páginas.-- Trabajo presentado al Seminario Ruraland celebrado en Antequera (Málaga) el 26 de mayo de 2010.-- Presentado como ponencia a la Jornada de debate "El desarrollo rural en la U.E. despues de 2013" celebrado en Aracena (Huelva) el 10 de junio de 2010 (adjuntado Pdf).

  17. Electron impact exctation of Al X

    Science.gov (United States)

    Aggarwal, Kanti; Keenan, Francis

    2013-05-01

    Emission lines of Al ions, including Al X, are important for the modeling and diagnostics of lasing, fusion and astrophysical plasmas, for which atomic data are required for a variety of parameters, such as energy levels, radiative rates (A- values), and excitation rates or equivalently the effective collision strengths (Υ), which are obtained from the electron impact collision strengths (Ω). Experimentally, energy levels are available for Al X on the NIST website, but there is paucity for accurate collisional atomic data. Therefore, here we report a complete set of results (namely energy levels, radiative rates, and effective collision strengths) for all transitions among the lowest 98 levels of Al X. These levels belong to the (1s2) 2s2, 2s2p, 2p2, 2s3 l, 2p3 l, 2s4 l, and 2p4 l configurations. Finally, we also report the A- values for four types of transitions, namely electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2), because these are also required for plasma modeling. For our calculations of wavefunctions, we have adopted the fully relativistic GRASP code, and for the calculations of Ω, the Dirac atomic R-matrix code (DARC) of PH Norrington and IP Grant. Additionally, parallel ca

  18. The Science of al-Biruni

    OpenAIRE

    Sparavigna, Amelia Carolina

    2013-01-01

    Al-Biruni (973-1048) was one of the greatest scientists of all times. He was an astronomer, mathematician and philosopher, and studied physics and natural sciences. In this paper, we will discuss some of his experimental methods and some instruments he used.

  19. Thermoluminescence of LaAlO3

    International Nuclear Information System (INIS)

    In this paper the thermoluminescent properties of doped lanthanum aluminate (LaAlO3) with dysprosium ion (Dy) were studied. The thermoluminescence characteristics in the samples were obtained using an ultraviolet radiation of 220 nm. The LaAlO3:Dy samples were prepared by the modified Pechini method (Spray Dryer). The structural and morphological characterization was obtained by X-ray diffraction (XRD) and scanning electron microscopy (Sem) techniques respectively. The size particle composing the agglomerate was determined by Sem, agglomerated particles composed size of 2μm were observed. The thermoluminescence response of LaAlO3:Dy was compared with that obtained with the undoped sample. Thermoluminescence brightness curves of LaAlO3:Dy showed a peak centered at 185 grades C. Sensitivity of doped sample was greater, about 100 times compared with the undoped sample. Thermoluminescence response in function of the wavelength showed a maximum at 220 nm. Also the fading in thermoluminescence response was studied. (Author)

  20. Management of respiratory symptoms in ALS.

    LENUS (Irish Health Repository)

    Hardiman, Orla

    2012-02-01

    Respiratory insufficiency is a frequent feature of ALS and is present in almost all cases at some stage of the illness. It is the commonest cause of death in ALS. FVC is used as important endpoint in many clinical trials, and in decision-making events for patients with ALS, although there are limitations to its predictive utility. There are multiple causes of respiratory muscle failure, all of which act to produce a progressive decline in pulmonary function. Diaphragmatic fatigue and weakness, coupled with respiratory muscle weakness, lead to reduced lung compliance and atelectasis. Increased secretions increase the risk of aspiration pneumonia, which further compromises respiratory function. Bulbar dysfunction can lead to nutritional deficiency, which in turn increases the fatigue of respiratory muscles. Early recognition of respiratory decline and symptomatic intervention, including non-invasive ventilation can significantly enhance both quality of life and life expectancy in ALS. Patients with respiratory failure should be advised to consider an advance directive to avoid emergency mechanical ventilation.

  1. Al-Ghazali on Moral Education

    Science.gov (United States)

    Alavi, Hamid Reza

    2007-01-01

    Al-Ghazali (1058-1111 CE) is probably the most influential scholar, philosopher, theologian, legal expert, religious reformer and mystic in the history of Islam. Although he wrote extensively about education, and particularly about moral education, this writing is scattered through a number of different works and has received less scholarly…

  2. Aluminum matrix texture in Al-Al3Ti functionally graded materials analyzed by electron back-scattering diffraction

    Science.gov (United States)

    Watanabe, Yoshimi; Sequeira, Paulo D.; Sato, Hisashi; Inamura, Tomonari; Hosoda, Hideki

    2016-01-01

    Al matrix functionally graded materials (FGMs) with oriented Al3Ti platelets were fabricated by a centrifugal solid-particle method. The applied centrifugal forces were 30, 60, and 120G (units of gravity). The orientation and volume fraction gradients of the Al3Ti platelets within the samples were measured. Since a good lattice correspondence was reported for the close-packed directions and the close-packed planes between Al and Al3Ti, the Al matrix in the Al-Al3Ti FGMs fabricated by the centrifugal solid-particle method should have some texture. Al matrix texture was, therefore, analyzed by electron back-scattering diffraction (EBSD). Analysis of the resulting pole figures indicates a preferred orientation along the (200) plane for the Al matrix crystals. Furthermore, increasing the applied centrifugal force enhances the orientation effect. A correlation appears to exist between platelet orientation and the preferred texture of the Al matrix.

  3. Investigation Of Water Assisted Phase Transformation Process From AlPO4-5 to AlPO4-tridymite

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Suochang; Zhao, Zhenchao; Hu, Mary Y.; Han, Xiuwen; Hu, Jian Z.; Bao, Xinhe

    2016-03-15

    Water assisted phase transformation process from crystalized AlPO4-5 to AlPO4-tridymite was studied by the combination of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and in situ multinuclear MAS NMR. It is found that water first activates the residue amorphous aluminophosphate in crystalized AlPO4-5 sample through hydrolysis and condensation reactions. Then the activated aluminophosphate species reassemble into AlPO4-tridymite crystalline. Meanwhile, AlPO4-5 transforms into orthorhombic phase during heating process. With further crystallization of AlPO4-tridymite, the amorphous phase is gradually consumed, and mass transportation between AlPO4-5 and AlPO4-tridymite is established through gradually amorphization of AlPO4-5. Finally, most of the AlPO4-5 transforms into the thermodynamically stable dense phase AlPO4-tridymite.

  4. Desgaste profesional por empatía y manejo de emociones

    OpenAIRE

    Galfaso de Habib, Alicia Susana

    2016-01-01

    Los Equipos PAE. Formación y caracteristicas El cuidado y el autocuidado del profesional de emergencias La comunicación interna, dinámica y modalidad efectiva para la prevención del estrés ( modos, tiempos, lenguaje, etc) Técnicas de descarga emocional breves y focalizadas de rápida y sencilla implementación Detección y gestión del estrés crónico y agudo. Indicadores claves. El Autocuidado individual y grupal Universidad de Málaga. Campus de Excelencia Internacional Andaluc...

  5. Estudo do desgaste abrasivo das resinas compostas disponíveis no mercado brasileiro

    Directory of Open Access Journals (Sweden)

    Eduardo Carlos Bianchi

    2003-06-01

    Full Text Available This work presents a proposal to assess the abrasive wear of composite resins available in the national market, which are materials largely used in dental clinics for functional and aesthetic tooth restorations. This was achieved by utilizing an experimental set-up on which a dynamic disc covered with proper porcelain (representing hardness close to the human teeth wears a static disc covered with the resin tested under a constant and pre-determined load. Thus, by means of this set-up and keeping a behavioral status needed to the calculus for all tests, the aggressiveness (referred as to letter k for all tests was analyzed. Due to the fact that resin characteristic revels how weary the material has become to the abrasion process with other harder material, the strength to wear for such resins was observed. Therefore, a real classification for these materials with their strength to the abrasion wear was made, which is a very important factor in the influence on their lifetime in dental restorations. The classification in descending order for those resins is presented as following: HELIOMOLAR RO, DURAFILL, FILTEK A110, HELIO FILL, POINT 4, FLOW IT; NATURAL FLOW, SUPRAFILL, FILTEK P60, FILTEK Z250, TETRIC FLOW, REVOLUTION, PRODIGY, TETRIC CERAM, HERCULITE, FILLMAGIC, TPH, CHARISMA, Z100.

  6. Estudo do desgaste abrasivo das resinas compostas disponíveis no mercado brasileiro

    OpenAIRE

    Bianchi Eduardo Carlos; Aguiar Paulo Roberto de; Poggi Márcio Rodrigo; Salgado Manoel Henrique; Freitas César Antunes de; Bianchi Ana Rita Rodrigues

    2003-01-01

    This work presents a proposal to assess the abrasive wear of composite resins available in the national market, which are materials largely used in dental clinics for functional and aesthetic tooth restorations. This was achieved by utilizing an experimental set-up on which a dynamic disc covered with proper porcelain (representing hardness close to the human teeth) wears a static disc covered with the resin tested under a constant and pre-determined load. Thus, by means of this set-up and ke...

  7. Wallada Bint al Mustakfi entre dos culturas

    Directory of Open Access Journals (Sweden)

    shreen Mahmoud Al Refai

    2013-10-01

    Full Text Available La princesa cordobesa Wallada Bint al Mustakfi bil-lah, hija del califa al Mustakfi Muhammad Ibn Abdel Rahman Ibn Obaidil-lah Ibn Al Nasir lidin Al-lah era una poetisa estimable, a quien los grandes poetas no podían superar. Era una mujer única, guapa y decente. Mantenía una relación sentimental con el  poeta y visir Ibn Zaydún. Dicha pasión, narrada por los poemas escritos por ambos amantes, se terminó por la separación debida a los celos, también de ambos;  al poeta le gustó la voz de una esclava de la princesa. Eso dio rabia a la última. Movido también por los celos, Ibn Zaydún dedicó una epístola satírica al visir Ibn Abdús, que estaba enamorado de Wallada. Tal hecho también irritó a la princesa. A pesar de tener amantes y admiradores, Wallada murió sin casarse al  día 2 de safar de 480 (o 484 de la Híjira pasando los ochenta años Me han llamado la atención el carácter tan culto, independiente y liberal de aquella mujer, su relación amorosa con Ibn Zaydún que no acabó felizmente y los muchos años que vivió sin casasre. Parece que la vida de la princesa hispano-musulmana llamó también la atención de muchos escritores árabes y españoles. Prueba de ello son varias obras literarias escritas en árabe y en español sobre Wallada e Ibn Zaydún. Por consiguiente, me resulta muy interesante realizar un estudio comparativo sobre este tema averiguando si, o no, la diferencia de culturas influiría en las opiniones  de los autores sobre la vida sentimental de aquella poetisa cordobesa.

  8. A high degree of enhancement of strength of sputter deposited Al/Al2O3 multilayers upon post annealing

    International Nuclear Information System (INIS)

    We report here an order of magnitude enhancement of strength of sputter deposited Al/Al2O3 multilayers after annealing. The increase in strength is shown to be mostly associated with the precipitation of extremely fine γ-Al2O3, 5–10 nm in diameter, in Al layers. This provides a new method of achieving high strength in Al/Al2O3 multilayers that cannot be explained by the Koehler effect or modified Hall–Petch, which will lead to the growth and development of new generation of Al/Al2O3 multilayers. We also examine the fracture behavior of the post annealed Al/Al2O3 multilayered composites with TEM and density functional theory (DFT) simulations. DFT showed that the multilayers are not likely to delaminate at the Al/Al2O3 interface, consistent with the experimental observations. The simulations are also used to determine elastic constants for the γ-Al2O3 phase and to calculate a driving force for O transport from the γ-Al2O3 to the Al layers. The formation of these precipitates is consistent with DFT calculations, which predict an energetic driving force for the dissolution of O atoms from the γ-Al2O3 layers into the Al layers

  9. ELECTROLYSIS OF SWINE MANURE EFFLUENTS USING THREE DIFFERENT ELECTRODES Fe-Fe, Al-Al AND Fe-Al

    Directory of Open Access Journals (Sweden)

    S. Rahman

    2014-01-01

    Full Text Available Swine effluent with high organic strength need to be treated to make it suitable for applying to crop/pasture fields, or discharging to any waterways. Electrocoagulation is a relatively simpler and cheaper technique over biological and chemical treatment methods currently used to treat high-strength industrial and municipal wastewater. The performance of an electrocoagulation system mainly depends on the pH, Electrical Conductivity (EC of the medium, Chemical Oxygen Demand (COD loading rates and catalytic activity of the electrodes used. In this research, a study was conducted to compare the pollutant removal efficiencies of three electrodes (Fe-Fe, Al-Al and Fe-Al with three electric current levels (500, 1000 and 2000 mA while treating swine manure effluents. The electrochemical cell consisted of two parallel rectangular plates (90×25×1.5 mm of Iron (Fe-Fe, Aluminum (Al-Al and Iron-Aluminum (Fe-Al, later on described as hybrid electrodes; immersed in a beaker with 550 mL swine effluents and powered by a Direct Current (DC supply. All studies were conducted in batches at room temperature. In general, removal efficiencies were increased with increasing current densities and electrolysis times for electrodes evaluated. Aluminum electrodes outperformed iron and hybrid (iron-aluminum electrodes in removing Total Phosphorus (TP at all current density levels tested. Overall, use of hybrid electrodes resulted in better COD removal. For the same treatment times (1200 s at higher current density (21 mA cm-2, hybrid electrodes removed about 100% COD, which are about 1.9 and 1.3 times higher than those of aluminum and iron electrodes, respectively. Iron electrodes showed the highest removal efficiency (85% for Total Organic Carbon (TOC at 21 mA cm-2 current density and 1200 s treatment time. Overall, lower Specific Electrical Energy Consumptions (SEECs per kg of Pollutants (TP, COD and TOC were estimated for the aluminum

  10. Medien als Lernform und die Trimediale Redaktion

    Directory of Open Access Journals (Sweden)

    Wolf Hilzensauer

    2015-01-01

    Full Text Available Der vorliegende Artikel beschreibt ein Konzept für eine handlungsorientierte Medienpädagogik im Bildungsbereich. Im Mittelpunkt steht dabei die SO!-Campusredaktion, die als Methode für expansives Lernen die Möglichkeit bietet, unabhängig von Thema oder Medium die Verantwortung für den Lernprozess in die Hände der Lernenden zu legen. Der Dokumentation von Reflexion über den Lernprozess wird dabei eine besondere Bedeutung zugesprochen. Gleichzeitig werden unterschiedliche mediale Gestaltungsmöglichkeiten (Audio/Radio, Video/Fernsehen und Zeitung – sowohl als Print- als auch als Onlinemedium vorgestellt, die durch das Konzept BYOD – bring your own device – auch einfach und niederschwellig im Bildungskontext umsetzbar sind. Dadurch ergeben sich innovative Möglichkeiten, einen Lernprozess sichtbar zu machen und gleichzeitig eine Grundlage für eine alternative Leistungsbeurteilung anzubieten. Die SO!-Campusredaktion wird derzeit an der Pädagogischen Hochschule Salzburg in Kooperation mit dem Communitysender FS1 und der Radiofabrik entwickelt und erprobt. Community Medien nehmen als MedienpartnerInnen eine bedeutende Stellung ein: Durch ihren offenen Zugang zu Know How und Equipment sowie durch die Möglichkeit, Medienproduktionen über die verfügbaren Distibutionskanäle (Radiofrequenz oder Sendeplatz einer breiten Bevölkerung zugänglich zu machen, gewinnt die Medienpädagogik einen wichtigen Mehrwert in ihrer schulischen und außerschulischen Arbeit. (Dieser Artikel knüpft an den Artikel "BYOD, Smartphonefilme und webbasierte Videoschnittprogramme" der Medienimpulse, Ausgabe 2/2014, an.

  11. Microstructure of Ni-Al powder and Ni-Al composite coatings prepared by twin-wire arc spraying

    Institute of Scientific and Technical Information of China (English)

    Ji-xiao Wang; Gui-xian Wang; Jing-shun Liu; Lun-yong Zhang; Wei Wang; Ze Li; Qi-xiang Wang; Jian-fei Sun

    2016-01-01

    Ni–Al powder and Ni–Al composite coatings were fabricated by twin-wire arc spraying (TWAS). The microstructures of Ni-5wt%Al powder and Ni-20wt%Al powder were characterized by scanning electronic microscopy (SEM) and energy dispersive spec-troscopy (EDS). The results showed that the obtained particle size ranged from 5 to 50μm. The morphology of the Ni–Al powder showed that molten particles were composed of Ni solid solution, NiAl, Ni3Al, Al2O3, and NiO. The Ni–Al phase and a small amount of Al2O3 parti-cles changed the composition of the coating. The microstructures of the twin-wire-arc-sprayed Ni–Al composite coatings were characterized by SEM, EDS, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that the main phase of the Ni-5wt%Al coating consisted of Ni solid solution and NiAl in addition to a small amount of Al2O3. The main phase of the Ni-20wt%Al coating mainly consisted of Ni solid solution, NiAl, and Ni3Al in addition to a small amount of Al and Al2O3, and NiAl and Ni3Al intermet-allic compounds effectively further improved the final wear property of the coatings. TEM analysis indicated that fine spherical NiAl3 pre-cipitates and a Ni–Al–O amorphous phase formed in the matrix of the Ni solid solution in the original state.

  12. Structure of oxides prepared by decomposition of layered double Mg–Al and Ni–Al hydroxides

    International Nuclear Information System (INIS)

    Abstracts: Thermal decomposition of Mg–Al and Ni–Al layered double hydroxides LDH at temperatures lower than 800 °C leads to the formation of oxides with different structures. Mg–Al oxide has a very defective structure and consists of octahedral layers as in periclase MgO and mixed octahedral–tetrahedral layers as in spinel MgAl2O4. Mixed Ni–Al oxide has a sandwich-like structure, consisting of a core with Al-doped NiO-like structure and some surface layers with spinel NiAl2O4 structure epitaxial connected with the core. Suggested models were verified by simulation of X-ray diffraction patterns using DIFFaX code, as well as HRTEM, IR-, UV-spectroscopies, and XPS. - Graphical abstract: In the Mg–Al layered double hydroxide Al3+ ions migrate into interlayers during decomposition. The Mg–Al oxide represents sequence of octahedral and octahedral–tetrahedral spinel layers with vacancies. The Ni–Al oxide has a sandwich-like structure with NiO-like core and surface spinel layers as a result of migration of Al3+ ions on the surface. The models explain the presence and absence of “memory effect” for the Mg–Al and Ni–Al oxides, respectively. - Highlights: • We study products of Mg(Ni)–Al LDH decomposition by calcination at 500(400)–800 °C. • In Mg–Al/Ni–Al LDH Al ions migrate into interlayers/on the surface during decomposition. • Mg–Al oxide represents sequence of periclase- and spinel-like layers with vacancies. • Ni–Al oxide has a sandwich-like structure with NiO-like core and surface spinel layers. • The models explain the presence/absence of “memory effect” for Mg–Al/Ni–Al oxides

  13. High noise suppression using magnetically isotropic (CoFe-AlN)/(AlN) multilayer films

    Science.gov (United States)

    Kijima, Hanae; Ohnuma, Shigehiro; Masumoto, Hiroshi; Shimada, Yutaka; Endo, Yasushi; Yamaguchi, Masahiro

    2015-05-01

    Magnetically isotropic (CoFe-AlN)n/(AlN)n+1 multilayer films, in which the number of CoFe-AlN magnetic layers n ranged from 1 to 27, were prepared by radio frequency sputtering to achieve noise suppression at gigahertz frequencies. The soft CoFe-AlN magnetic layers consisted of nanometer-sized CoFe ferromagnetic grains embedded in an insulating AlN amorphous matrix, while the insulating AlN layers comprised AlN columnar crystals. All films showed a similar frequency dependence of permeability and ferromagnetic resonance of 1.7 GHz. Noise suppression was evaluated using a microstrip line as a noise source by determining the in-line conductive loss and the near-field intensity picked up by magnetic field detective probes. High noise suppression effects were observed in every direction in the film plane. Maximum noise suppression values amounted to 60% for the in-line conductive loss and -20 dB for the magnetic near-field intensity at around 1.7 GHz in the 27-layer film. These high-frequency noise suppression levels may be attributed to eddy current losses and ferromagnetic resonance.

  14. Fabrication and Mechanical Properties of Al_2O_3/TiAl Composites

    Institute of Scientific and Technical Information of China (English)

    AI Taotao

    2009-01-01

    Al_2O_3/TiAl composites were successfully fabricated by hot-press-assisted exother-mic dispersion method with elemental powder mixtures of Ti,Al TiO_2 and Nb_2O_5,and the micro-structure and mechanical properties were investigated.The results indicate the fine Al_2O_3 particles tend to disperse on the grain boundaries.The grain size of TiAl matrix decreases and the hardness increases with increasing Nb_2O_5 content.The bending strength and fracture toughness reach to a maximum when Nb_2O_5 content is 6 wt%,under 642 Mpa and 6.69 Mpa·m ~(1/2) ,respectively.Based on the fractography and the observation of crack propagation path,it is concluded that the strengthening and toughening of such composites at room temperature can be attributed to the refinement of the TiAl matrix,the de-flection behavior in the crack propagation and the dispersion of Al_2O_3 particles.

  15. Neutronic comparison of the nuclear fuels U3Si2/Al and U-Mo/Al

    International Nuclear Information System (INIS)

    The search for materials that allow the fabrication of nuclear fuels with higher uranium densities comes from the mid 50s. Today, a high density and low enriched nuclear fuel based on γ-UMo alloys is the most promising fuel to replace the U3Si2/Al dispersion fuel used worldwide in research and material test reactors. Alloys of uranium-molybdenum are prepared with 6 to 10% Mo addition and can be manufactured as dispersion or monolithic fuels. The aim of this paper is to compare the infinite multiplication factor (K∞), obtained through neutronic calculation with the code Scale 6, for aluminum coated plates reflected in all directions containing U3Si2/Al and U-Mo/Al dispersion fuels. The U3Si2/Al dispersion fuel used in the calculation has an uranium density of 4 gU/cm3 and the U-Mo-Al dispersion fuels have densities ranging from 4 to 7.52 gU/cm3 and 7 and 10% Mo addition. The results show that the K∞ calculated for U-Mo/Al fuels is lower than that for U3Si2/Al fuel and increases between the uranium densities of 4 and 5 gU/cm3 and decreases for higher uranium densities. (author)

  16. Electrical defects in AlGaN and InAlN

    Science.gov (United States)

    Johnstone, D.; Leach, Jacob H.; Kovalskii, Vladimir A.; Fan, Qian; Xie, Jingqiao; Morkoç, Hadis

    2009-02-01

    Compound semiconductors based on GaN have multiple functional applications. Useful compositions include GaN, and ternary and quaternary compositions of (AlGaIn)N. Defects arising from lattice mismatch, point defects, or impurities may act as electrical trapping centers and degrade device efficiency. Current-voltage, capacitance-voltage, thermal admittance spectroscopy (TAS), and deep level transient spectroscopy (DLTS) measurements are applied to characterize the defects in Al0.40Ga0.80N and In0.18Al0.82N in this report. Broad peaks with a shoulder at high temperature dominate the DLTS spectra in each of the materials. An acceptor trap associated with a dislocation appears at 340 K in AlGaN. The defect has an energy of 0.2 eV and capture cross section of 10-21 cm2. A second trap at 0.35 eV, 10-14 cm2 appears in the TAS measurements in addition to the trap at 0.2 eV. Defects in InAlN are dominated by a peak near 150 K. Two traps appear in the TAS measurements. Both traps in the InAlN are acceptors, based on a lack of field dependent emission rates using double pulse DLTS (DDLTS). The two energy levels in InAlN appear to be coupled, with only one state occupied at a time.

  17. Mechanical Properties and Microstructure of Neutron Irradiated Cold-worked Al-1050 and Al-6063 Alloys

    International Nuclear Information System (INIS)

    The impact of neutron irradiation on the internal microstructure, mechanical properties and fracture morphology of cold-worked Al-1050 and Al-6063 alloys was studied, using scanning and transmission electron microscopy, and tensile measurements. Specimens consisting of 50 mm long and 6 mm wide gauge sections, were punched out from Al-1050 and Al-6063 23% cold-worked tubes. They were exposed to prolonged neutron irradiation of up to 4.5x1025 and 8x1025 thermal neutrons/m2 (E -3 s-1. In general, the uniform and total elongation, the yield stress, and the ultimate tensile strength increase as functions of fluence. However, for Al-1050 a decrease in the ultimate tensile strength and yield stress was observed up to a fluence of 1x1025 thermal neutrons/m2 which then increase with thermal neutrons fluence. Metallographic examination and fractography for Al-6063 revealed a decrease in the local area reduction of the final fracture necking. This reduction is accompanied by a morphology transition from ductile transgranular shear rupture to a combination of transgranular shear with intergranular dimpled rupture. The intergranular rupture area increases with fluence. In contrast, for Al-1050, fracture morphology remains ductile transgranular shear rupture and the final local area reduction remains almost constant No voids could be observed in either alloy up to the maximum fluence. The dislocation density of cold-worked Al was found to decrease with the thermal neutron fluence. Prolonged annealing of unirradiated cold-worked Al-6063 at 52 degree led to similar results. Thus, it appears that, under our irradiation conditions, whereby the temperature encompassing the samples increases the exposure to this thermal field is the major factor influencing the mechanical properties and microstructure of aluminum alloys

  18. Oxidation Behaviour of Sputtered Ni-3Cr-20Al Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The oxidation behavior of sputtered Ni-3Cr-20Al coating at 900°C in air was investigated. A dense Al2O3 layer was formed on the sputtered Ni-3Cr-20Al coating after 200 h oxidation.However, owing to the segregation of Ni3Al during oxidation Focess at high temperature, the spinel NiAl2O4 was also formed in the Al2O3 layer. It was found that the formation of NiAl2O4had no detrimental effect on the oxidation resistance of the sputtered Ni-3Cr-20Al coating due to the excellent adhesion shown by the Al2O3 and NiAl2O4 complex oxide scale.

  19. Al-rich region of Al−Pt

    International Nuclear Information System (INIS)

    Highlights: •The constitution of Al−Pt above 65 at.% Al is specified. •The previously reported Al4Pt, Al21Pt8 and Al2Pt phases are confirmed. •A new stable orthorhombic phase was revealed at ∼75–76 at.% Al and 801–915 °C. -- Abstract: The constitution of the Al-rich part of the Al−Pt alloy system is revised. Apart from the previously reported equilibrium Al4Pt, Al21Pt8 and Al2Pt phases, a complex intermetallic was revealed at 75-76 at.% Al between 801 and 915 °C. Its structure determined by electron diffraction is orthorhombic (Bmmb, a = 1.983, b = 1.636 and c = 1.422 nm)

  20. Questioning of Authentication and Epistemology in Tafsir al-Jilani

    Directory of Open Access Journals (Sweden)

    Irwan Masduqi

    2012-06-01

    Full Text Available In this research, the author critically analyzes a biography of Shaikh ‘Abd al-Qadir al-Jilani containing sacred myths. The analyst of sacred myth about ‘Abd al-Qadir al-Jilani is based on the approach of applied anthropology to distinguish between the myths that have  positive and negative values for Muslim society. This research then analyzes the authenticity of Tafsir al-Jilani and the epistemology of his inter- pretation. ‘Abd al-Qadir al-Jilani is the founder of Qadiriyah. Qadiriyah doctrines has been widely accepted by traditional Muslim groups in Muslim world, so that the study of Tafsir al-Jilani is very meaningful for the followers of Qadiriyah in particu- lar and the lovers of Quranic studies in general to increase their knowledge about the teachings of ‘Abd al-Qadir al-Jilani.