Reparación de muros de construcciones históricas de tierra mediante el sellado de fisuras y refuerzos estructurales adicionales

Se propone una técnica dual de reparación y reforzamiento para proteger las construcciones patrimoniales de adobe frente al efecto destructivo de los terremotos. La técnica consiste en la reparación de las grietas sísmicas mediante inyección de barro líquido, combinada con el reforzamiento de los muros con mallas formadas por cuerdas sintéticas (drizas). Para comprobar la efectividad de esta técnica, se efectuaron ensayos de simulación sísmica en el Laboratorio de Estructuras de la Pontificia Universidad Católica del Perú (PUCP). Se construyó un espécimen modelo de cuatro muros de adobe a escala natural que se ensayó en el simulador sísmico hasta generar grietas en los muros. Las grietas resultantes fueron reparadas mediante la inyección de barro líquido para intentar restituir la resistencia original de la estructura. Luego, los muros del modelo fueron reforzados con drizas. Después del periodo de secado, el modelo fue ensayado nuevamente en el simulador sísmico. El comportamiento del modelo ante movimientos de gran intensidad fue satisfactorio: se mantuvo la integridad estructural ante la excitación sísmica simulada, de gran severidad, y se evitó el colapso parcial de los muros. Para entender el comportamiento de las drizas en los muros del modelo reforzado, se estudió un procedimiento de análisis de movimiento de bloque rígido sometido a fuerzas de excitación sísmica y de interacción de drizas. Finalmente, se presenta un análisis preliminar para calcular las fuerzas en las drizas. Estos resultados permitirán desarrollar un método de diseño de la malla de drizas. Esta publicación consta de dos artículos publicados en conferencias internacionales. En ellos se compila la técnica propuesta y ensayada tal como se menciona en los párrafos superiores. El primer artículo se presentó en Turquía en setiembre de 2013 y el segundo se publicará en la ciudad de México en octubre de 2014.Tesi

The Electron Emission Characteristics of Aluminum, Molybdenum and Carbon Nanotubes Studied by Field Emission and Photoemission.

The electron emission characteristics of aluminum, molybdenum and carbon nanotubes were studied. The experiments were setup to study the emission behavior as a function of temperature and exposure to oxygen. Changes in the surface work function as a result of thermal annealing were monitored with low energy ultra-violet photoelectron spectroscopy for flat samples while field emission energy distributions were used on tip samples. The change in the field emission from fabricated single tips exposed to oxygen while in operation was measured using simultaneous Fowler-Nordheim plots and electron energy distributions. From the results a mechanism for the degradation in the emission was concluded. Thermal experiments on molybdenum and aluminum showed that these two materials can be reduced at elevated temperatures, while carbon nanotubes on the other hand show effects of oxidation. To purely reduce molybdenum a temperature in excess of 750 ºC is required. This temperature exceeds that allowed by current display device technology. Aluminum on the other hand shows reduction at a much lower temperature of at least 125 ºC; however, its extreme reactivity towards oxygen containing species produces re-oxidation. It is believed that this reduction is due to the outward diffusion of aluminum atoms through the oxide. Carbon nanotubes on the other hand show signs of oxidation as they are heated above 700 ºC. In this case the elevated temperatures cause the opening of the end caps allowing the uptake of water. Oxygen exposure experiments indicate that degradation in field emission is two-fold and is ultimately dependent on the emission current at which the tip is operated. At low emission currents the degradation is exclusively due to oxidation. At high emission currents ion bombardment results in the degradation of the emitter. In between the two extremes, molybdenum tips are capable of stable emission

Multifunctional Nanocomposite with Healing and Health Monitoring Capabilities

No abstract availabl

Carbon Nanotube Material Quality Assessment

The nanomaterial activities at NASA Johnson Space Center focus on carbon nanotube production, characterization and their applications for aerospace systems. Single wall carbon nanotubes are produced by arc and laser methods. Characterization of the nanotube material is performed using the NASA JSC protocol developed by combining analytical techniques of SEM, TEM, UV-VIS-NIR absorption, Raman, and TGA. A possible addition of other techniques such as XPS, and ICP to the existing protocol will be discussed. Changes in the quality of the material collected in different regions of the arc and laser production chambers is assessed using the original JSC protocol. The observed variations indicate different growth conditions in different regions of the production chambers

Single Wall Nanotube Type-Specific Functionalization and Separation

Metallic single-wall carbon nanotubes were selectively solubilized in THF and separated from semiconducting nanotubes. Once separated, the functionalized metallic tubes were de-functionalized to restore their metallic band structure. Absorption and Raman spectroscopy of the enriched samples support conclusions of the enrichment of nanotube samples by metallic type. A scalable method for enriching nanotube conductive type has been developed. Raman and UV-Vis data indicate SWCNT reaction with dodecylbenzenediazonium results in metallic enrichment. It is expected that further refinement of this techniques will lead to more dramatic separations of types and diameters

ANÁLISIS GEOTÉCNICO APLICADO AL DISEÑO DE CIMENTACIONES SUPERFICIALES EN VIVIENDAS UNIFAMILIARES EN LA ZONA ALTA DEL CENTRO POBLADO DE JANCAO DEL DISTRITO DE AMARILIS, HUÁNUCO 2020

La investigación tiene como objetivo realizar un análisis geotécnico aplicado al diseño de cimentaciones superficiales en viviendas unifamiliares en la zona alta del Centro Poblado de Jancao, distrito de Amarilis, Huánuco. La metodología utilizada en la presente tesis fue de tipo aplicada, de nivel Descriptivo y de diseño no experimental. La población estuvo constituida por la zona alta del centro poblado de Jancao con un área superficial de 148,746.35 m2 (14ha 8,746.35 m2) y como muestra se analizó a la Urb. Cristo Rey con una extensión de 12,791.63 m2 (1 ha 2791.63m2). Para llevar a cabo la investigación, inicialmente se realizó la exploración del área de estudio empleando la técnica de Observación directa con la finalidad de llevar a cabo la excavación de cuatro (04) calicatas ubicadas estratégicamente a 3.00m de profundidad. Posteriormente las muestras extraídas en campo fueron analizadas por medio de los ensayos en el laboratorio de suelos a fin de conocer las propiedades físico- mecánicas del terreno, identificar el tipo de suelo y sus parámetros de resistencia, todo ello a fin de determinar la capacidad portante, siendo este último determinante para diseñar correctamente la cimentación y también se determinaron los asentamientos admisibles que se producen en el suelo, todo ello con la finalidad de proponer un tipo de cimentación estándar para el área de estudio, elaborando así dos propuestas de diseño de la cimentación superficial utilizando el software ETABS v.16 para modelar estructuralmente la edificación y también el software SAFE v.16 para verificar el diseño de la cimentación propuesta, la primera una edificación de muros portantes de albañilería confinada con cimiento corrido en toda su sección y la segunda una edificación aporticada con zapatas cuadradas. Finalmente se obtuvo como resultado que el tipo de suelo preponderante en la zona es arena arcillosa (SC) y tiene una capacidad portante admisible de 2.37 Kg/cm2, proponiendo cimentar sobre zapatas cuadradas de 1.50mx1.50m a una profundidad de 1.50m, el cual cumple con las verificaciones de diseño por capacidad de carga y por asentamiento, resultando estructuralmente segura.Tesi

Estudio para la implementación de una empresa de ventas de pizza en la ciudad de Guayaquil

PDFEl presente proyecto hace referencia a la creación de una empresa dedicada a la producción y comercialización de pizzas en la ciudad de Guayaquil, se presentará las mejores formas y destrezas en la producción, distribución comercialización del producto, además se determinará la rentabilidad que tendrá el proyecto, el cual promoverá al desarrollo de la actividad empresarial, generando a la vez fuentes de trabajo y alternativas para la inversión. La modalidad de la investigación que se realizará es tanto cuantitativa como cualitativa, para entender el comportamiento y las distintas reacciones que han tenido los consumidores de pizza en la ciudad de Guayaquil, se partirá de hechos particulares para realizar conclusiones generales poniendo énfasis en la situación actual del negocio de las pizzerías en el área de desarrollo poblacional que rodea a Guayaquil en la vía Pascuales-La AuroraThis project refers to the creation of a company dedicated to the production and marketing of pizzas in the city of Guayaquil, will present the best forms and skills in the production, marketing of the product, and determine the profitability of the project , which will promote the development of business activity, generating both sources of work and alternatives for investment. The modality of the investigation that will be carried out is both quantitative and qualitative, to understand the behavior and the different reactions that have had the consumers of pizza in the city of Guayaquil, will start from particular facts to make general conclusions emphasizing in the current situation of the business of the pizzerias in the area of population development that surrounds Guayaquil on the Pascuales-La Aurora road Sugerir una edición Google Traductor para empresas:Translator ToolkitTraductor de sitios web Acerca de Google TraductorComunidadCelulares Acerca de GooglePrivacidad y condicionesAyudaEnviar comentario

Flexible Graphene Composites for Human Space Flight Applications

Graphene oxide allows for better dispersion stability in aqueous and organic solvents. Stabilizers provide dispersion of pristine graphene. Roll coating provide the best coverage of polyurethane sheets. Graphene and GO coated polyurethane used to fabricate flexible laminate composite. Permeation testing indicates that pristine graphene acts as a better gas barrier material. Continuous graphene films are expected to provide even better gas barrier properties

Measurement Challenges for Carbon Nanotube Material

The advances in large scale applications of carbon nanotubes demand a reliable supply of raw and processed materials. It is imperative to have a consistent quality control of these nanomaterials to distinguish material inconsistency from the modifications induced by processing of nanotubes for any application. NASA Johnson Space Center realized this need five years back and started a program to standardize the characterization methods. The JSC team conducted two workshops (2003 and 2005) in collaboration with NIST focusing on purity and dispersion measurement issues of carbon nanotubes [1]. In 2004, the NASA-JSC protocol was developed by combining analytical techniques of SEM, TEM, UV-VIS-NIR absorption, Raman, and TGA [2]. This protocol is routinely used by several researchers across the world as a first step in characterizing raw and purified carbon nanotubes. A suggested practice guide consisting of detailed chapters on TGA, Raman, electron microscopy and NIR absorption is in the final stages and is undergoing revisions with input from the nanotube community [3]. The possible addition of other techniques such as XPS, and ICP to the existing protocol will be presented. Recent activities at ANSI and ISO towards implementing these protocols as nanotube characterization standards will be discussed

Sox10 contributes to the balance of fate choice in dorsal root ganglion progenitors

The development of functional peripheral ganglia requires a balance of specification of both neuronal and glial components. In the developing dorsal root ganglia (DRGs), these compo- nents form from partially-restricted bipotent neuroglial precursors derived from the neural crest. Work in mouse and chick has identified several factors, including Delta/Notch signal- ing, required for specification of a balance of these components. We have previously shown in zebrafish that the Sry-related HMG domain transcription factor, Sox10, plays an unex- pected, but crucial, role in sensory neuron fate specification in vivo. In the same study we described a novel Sox10 mutant allele, sox10baz1, in which sensory neuron numbers are elevated above those of wild-types. Here we investigate the origin of this neurogenic pheno- type. We demonstrate that the supernumerary neurons are sensory neurons, and that enteric and sympathetic neurons are almost absent just as in classical sox10 null alleles; peripheral glial development is also severely abrogated in a manner similar to other sox10 mutant alleles. Examination of proliferation and apoptosis in the developing DRG reveals very low levels of both processes in wild-type and sox10baz1, excluding changes in the bal- ance of these as an explanation for the overproduction of sensory neurons. Using chemical inhibition of Delta-Notch-Notch signaling we demonstrate that in embryonic zebrafish, as in mouse and chick, lateral inhibition during the phase of trunk DRG development is required to achieve a balance between glial and neuronal numbers. Importantly, however, we show that this mechanism is insufficient to explain quantitative aspects of the baz1 phenotype. The Sox10(baz1) protein shows a single amino acid substitution in the DNA binding HMG domain; structural analysis indicates that this change is likely to result in reduced flexibility in the HMG domain, consistent with sequence-specific modification of Sox10 binding to DNA. Unlike other Sox10 mutant proteins, Sox10(baz1) retains an ability to drive neurogenin1 transcription. We show that overexpression of neurogenin1 is sufficient to produce supernu- merary DRG sensory neurons in a wild-type background, and can rescue the sensory neu- ron phenotype of sox10 morphants in a manner closely resembling the baz1 phenotype. We conclude that an imbalance of neuronal and glial fate specification results from the Sox10 (baz1) protein\u2019s unique ability to drive sensory neuron specification whilst failing to drive glial development. The sox10baz1 phenotype reveals for the first time that a Notch-dependent lat- eral inhibition mechanism is not sufficient to fully explain the balance of neurons and glia in the developing DRGs, and that a second Sox10-dependent mechanism is necessary. Sox10 is thus a key transcription factor in achieving the balance of sensory neuronal and glial fates