11,523 research outputs found
Myogenic regulatory factor Myf5 functions in gastrulation and plays a role in the development of pharyngeal cartilage, cranial neural crest, and hindbrain of zebrafish
No full textMateriales compuestos de matriz acero inoxidable austenítico reforzado con intermetálicos : comportamiento mecánico, a corrosión y desgaste
Get PDFLa investigación que se presenta en esta Tesis Doctoral, surge como respuesta a la
necesidad de resolver una serie de problemas que están relacionados entre sí,
como son el encontrar condiciones de producción industrial de bajo costo para los
aceros inoxidables pulvimetalúrgicos, seleccionar las distintas variables de
sinterización que mejoran el comportamiento de los materiales compuestos de
matriz acero inoxidable reforzados con intermetálicos, identificar las posibles
interacciones matriz/refuerzo y determinar la posibilidad de prevención y reducción
de los fallos por corrosión ya sea intergranular, a altas temperaturas o por picaduras.
Con el fin de mejorar el comportamiento a desgaste y corrosión de los aceros
inoxidables pulvimetalúrgicos e, stos se han reforzado con partículas de AlCr2 y ? -
TiAI, y sinterizados en distintas condiciones, tales como atmósferas de amoniaco
disociado a 1120°C y vacío a 1120°C, 1200°C y 1250°C, respectivamente. Los
efectos de estas variables en los compuestos producidos se estudiaron desde el
punto de vista mecánico, comportamiento frente al desgaste y a la corrosión. Las
condiciones de procesado utilizadas permiten variar la cantidad de refuerzo que se
debe añadir y establecer criterios para la optimización de la temperatura de
sinterización que evite la formación de una porosidad que propicie el deterioro de
propiedades mecánicas, del comportamiento frente al desgaste y frente a la
resistencia a la corrosión. Los refuerzos empleados posibilitan que los aceros
inoxidables puedan ser sinterizados en condiciones industriales, disminuyendo tanto
el efecto del nitrógeno en la corrosión intergranular como en la oxidación a altas
temperaturas.
_________________________________________________The research developed in this Doctoral Thesis arises as a result of the trial to
resolve sorne problems related among them. These problems include: to find 10w
cost industrial cónditions of production of sintered stainless steels, to select the
appropriated sintering variables that improve the behaviour of stainless steel matrix
composites reinforced with intermetallics, to identify the probable ¡nteractions
between matrix and reinforcemerit, and to determine the prevention and reduction of
corrosion failures, like intergranutar corrosion, high temperature oxidation or pating
corrosion.
In order to improve the corrosion and wear behaviour of sintered stainless steels,
they have been reinforced with particles such as AICr2 and y -TiAI, and sintered in
different conditions, such as dissociated ammonia at 1120°C and vacuum at 1120°C,
1200°C y 1250°C, respectively. The effects of those elements on the composites
were evaluated from mechanical, corrosion and wear points of view. Processing
conditions allow to vary the amount of reinforcernent that can be added and to
establish criteria to optimise sintering temperature to avoid porosity formation,
negative for mechanical properties, wear behaviour and corrosion resistance.
Reinforcements used in this research allow sintering stainless steels in industrial
conditions, lowering the effect of nitrogen on intergranular corrosion, and high
temperature oxidation
Behaviour of buried pipelines subjected to external loading.
Get PDFThe research presented in this Thesis was carried out at the University of Sheffield under
the supervision of Dr I. C. Pyrah and Dr W. F. Anderson, and Mr G. Leach at British Gas
Engineering Research Station (ERS). The research was financially supported by a British
Gas Research Scholarship and by the Overseas Research Students Awards Scheme.
The Author would like to express his sincere gratitude to his supervisors for their invaluable
help, guidance and encouragement during the development of the research.
The Author is also grateful to Dr S. R. Mi for his interest and assistance throughout the
research. Special thanks also go to Dr S. J. Wheeler for his supervision during the first year
of the research and sound advice in the initial stage of the work.
The Author would like to express his gratitude to all members of the geotechnics group at
the University of Sheffield for the useful discussions and comments. Special thanks and
appreciation are extended to the staff at the ERS, particularly Mr E. Middleton for
providing the data of the field tests and constructive comments.
The laboratory tests were performed at ERS Soils Laboratory for which the Author is
thankful to the laboratory staff. The Author must also thank British Gas for providing the
computer hardware and software for performing the numerical analyses, and the printing
facilities to produce the Thesis. Thanks also go to Mr D. Reay and Mr B. Bellwood at the
Gas Research Centre of British Gas for ensuring continuous financial support throughout
the award period.
Finally, the Author wishes to thank his family and friends for their endless support and
encouragement throughout the period of study in the UK. Without them, this Thesis may
never have been completed
Fiber-Reinforced High-Performance Concretes Exposed to High Temperature: Materials Behavior and Structural Implications
Get PDFThe many studies devoted in the last twenty years to high strength/high performance concrete (HSC/HPC) demonstrate its very interesting properties in terms of stiffness, strength and durability. These pluses, however, arepartly counterbalanced by a few minuses(such as greater brittleness at room temperature and greater heat sensitivity), that can be reduced – and even zeroed – by introducing fibers, which improve concrete toughnessat any temperature (steel fibers)and durability at hightemperature (mainly polymeric fibers). Since many are the parameters affecting concrete properties at high temperature,keeping constant the volumetric fraction of the cementitious matrix (as done in this research project) is a must whenever different fibrous mixes are to be compared. To have further information on the role of steel and polymeric fibers on HSC/HPC behavior at high temperature, seven mixes have been investigated in terms of thermal diffusivity, stress-strain curves in compression and elastic modulus (fc = 60 MPa; T = 20-750°C, hot and residual conditions).Among polypropylene fibers, fibrillated fibers have an edge over monofilament fibers in residual conditions, while steel fibers are the most effective in both hot and residual conditions. A structural application is presented as well, concerning two R/C columns (with/without steel fibers) subjected to standard fire, where the structural behavior at any fire duration is enhanced thanks to the extra ductility provided by the fibers
The Europeanization of Interest Representation: A Strategic Decision-Making Analysis of UK Business and Environmental Interests
Get PDFThe point of departure for this paper is that the European Union (EU) has affected national politics, policies and polities. This process, labelled Europeanization, has led to changes in two interconnected political dimensions. First, it has led to modifications in the relationships between state and non-state actors within the national arena. Second, it has changed the interactions between the sub-national, national and supranational actors (state and non-state). To explore these propositions the paper conducts an analysis of the interest representation patterns exhibited by non-state actors. The paper compares firms (in the telecommunications, gas and electricity sectors) and environmental groups (focused on nature conservation or biodiversity policy), both based in the United Kingdom (UK), in order to determine how, to what extent and why Europeanization has affected their interest representation behaviour. The activities displayed by the two sets of interests are compared and contrasted in terms of chosen lobbying targets (i.e. national government departments and EU institutions), routes and allies (i.e. direct contact or via intermediaries such as Euro-groups) and the timing and character of the contact. Ideas and tools drawn from management science (i.e. strategic decision making analyses) are employed to assist in deriving the causal explanations for the Europeanized patterns of behaviour. It is argued that a combination of the three strategic decision making factors (i.e. internal organizational resources, objectives (and perceived rewards) and external political environments explain the contrasting behaviour of the firms and environmental groups
Escapist policy rules
Get PDFWe study a simple, microfounded macroeconomic system in which the monetary authority employs a Taylor-type policy rule. We analyze situations in which the self-confirming equilibrium is unique and learnable according to Bullard and Mitra (2002). We explore the prospects for the use of 'large deviation' theory in this context, as employed by Sargent (1999) and Cho, Williams, and Sargent (2002). We show that our system can sometimes depart from the self-confirming equilibrium towards a non-equilibrium outcome characterized by persistently low nominal interest rates and persistently low inflation. Thus we generate events that have some of the properties of "liquidity traps" observed in the data, even though the policymaker remains committed to a Taylor-type policy rule which otherwise has desirable stabilization properties
Strategic Forecasting on the FOMC
Get PDFThe Federal Open Market Committee (FOMC) of the Federal Reserve consists of voting- and non-voting members. Apart from deciding about interest rate policy, members individually formulate regular inflation forecasts. This paper uncovers systematic differences in individual inflation forecasts submitted by voting and non-voting members. Based on a data set with individual forecasts recently made available it is shown that non-voters systematically overpredict inflation relative to the consensus forecast if they favor tighter policy and underpredict inflation if the favor looser policy. These findings are consistent with non-voting member following strategic motives in forecasting, i.e. non-voting members use their forecast to influence policy deliberation.inflation forecast, forecast errors, monetary policy, monetary committee, Federal Reserve
Jet energy resolution in proton-proton collisions at root s=7 TeV recorded in 2010 with the ATLAS detector
Get PDFAtlas Collaboration contributor: Paul Douglas Jackson of SLAC National Accelerator Laboratory, Stanford CA, United States of America. Extent: 27p.The measurement of the jet energy resolution is presented using data recorded with the ATLAS detector in proton-proton collisions at √s=7 TeV . The sample corresponds to an integrated luminosity of 35 pb⁻¹. Jets are reconstructed from energy deposits measured by the calorimeters and calibrated using different jet calibration schemes. The jet energy resolution is measured with two different in situ methods which are found to be in agreement within uncertainties. The total uncertainties on these measurements range from 20 % to 10 % for jets within |y|<2.8 and with transverse momenta increasing from 30 GeV to 500 GeV. Overall, the Monte Carlo simulation of the jet energy resolution agrees with the data within 10 %.The ATLAS Collaboratio
Escapist Policy Rules
Get PDFWe study a simple, microfounded macroeconomic system in which the monetary authority employs a Taylor-type policy rule. We analyze situations in which the self-confirming equilibrium is unique and learnable according to Bullard and Mitra (2002). We explore the prospects for the use of ‘large deviation’ theory in this context, as employed by Sargent (1999) and Cho, Williams, and Sargent (2002). We show that our system can sometimes depart from the self-confirming equilibrium towards a non-equilibrium outcome characterized by persistently low nominal interest rates and persistently low inflation. Thus we generate events that have some of the properties of “liquidity traps” observed in the data, even though the policymaker remains committed to a Taylor-type policy rule which otherwise has desirable stabilization properties.Learning, monetary policy rules, escape dynamics
La secuencialidad del intersticio, límite sinuoso y continuo para conformar espacialidades fluidas entre lo natural y lo construido
No full textEl trabajo de grado presentado a continuación busca plantear desde la arquitectura el desarrollo del anteproyecto del Centro de Ciencia con el fin de consolidar el tramo centro del borde urbano de la actual Franja de Adecuación de Bogotá, bajo el concepto de la secuencialidad intersticial como una estrategia para dar fluidez a la forma y permitir la articulación del espacio residual entre la ciudad y los cerros orientales, los cuales se encuentran actualmente separados por límites físico- espaciales y simbólicos. Esto se ve reflejado en la concepción actual de la Franja de Adecuación como un espacio residual o como lo denomina Rem Koolhaas espacio basura del crecimiento urbano. Mediante el desarrollo del proyecto también se busca Incorporar actividades de uso mixto acordes con los diferentes flujos peatonales para generar convergencias en el proyecto que logren integrar los capitales diversos del sector de la candelaria y también contempla extender zonas de áreas verdes acordes al importante componente ambiental del lugar por la presencia de reservas naturales para de esta manera brindar continuidad a la estructura ecológica principal de Bogotá y generar mediante una apertura formal que se genera desde el proyecto a través de los principios que lo ordenan un punto de encuentro entre estas dos lecturas de ciudad. Finalmente la propuesta arquitectónica permitirá plantea diferentes usos, bajo un modelo de ciudad abierta para contribuir al aumento de zonas de espacio público y de áreas verdes en el lugar y propiciar más flujo peatonal, incentivando la percepción de seguridad y logrando así la articulación físico-espacial del borde urbano Oriental de Bogotá buscando una mejora en la calidad de vida de la población flotante y local del sector, para generar cohesión social y propiciar un correcto intercambio cultural y académico, haciendo posible hacer una reinterpretación de los conceptos de lo fluido y lo dinámico bajo el concepto de la secuencialidad intersticial para diseñar una habitabilidad que permite que el proyecto se incorpore en el lugar y logre adaptarse a las formas de recorrer y permanecer tan atípicas de un sector como La Candelaria.#SecuencialidadDelIntersticioLímiteSinuosoContinuoParaConformarEspacialidadesFluidasEntreLoNaturalYLoConstruido#SecuencialidadDelIntersticioLímiteSinuosoContinuoParaConformarEspacialidadesFluidas#SecuencialidadDelIntersticioLímiteSinuosoContinuoEntreLoNaturalYLoConstruidoRequerimientos de
sistema: Adobe Acrobat
ReaderThe degree work presented below seeks to raise from the architecture the development of the preliminary project of the Science Center in order to consolidate the central section of the urban edge of the current “Franja de Adecuación” de Bogotá, under the concept of interstitial sequentiality as a strategy to give fluidity to the form and allow the articulation of the residual space between the city and the eastern hills, which are currently separated by physical-spatial and symbolic limits. This is reflected in the current conception of the “Franja de Adecuación” as a residual space or as Rem Koolhaas calls it the junk space of urban growth. Through the development of the project, it is also sought to incorporate mixed-use activities in accordance with the different pedestrian flows to generate convergences in the project that manage to integrate the diverse capitals of the candelaria sector and also contemplates expanding green areas according to the important environmental component of the place due to the presence of natural reserves in order to provide continuity to the main ecological structure of Bogotá and generate through a formal opening that is generated from the project through the principles that order it a meeting point between these two readings of the city . Finally, the architectural proposal will allow different uses, under an open city model to contribute to the increase of areas of public space and green areas in the place and promote more pedestrian flow, encouraging the perception of safety and thus achieving physical-spatial articulation. of the eastern urban edge of Bogotá seeking an improvement in the quality of life of the floating and local population of the sector, to generate social cohesion and promote a correct cultural and academic exchange, making it possible to reinterpret the concepts of fluidity and dynamic under the concept of interstitial sequentiality to design a habitability that allows the project to be incorporated into the place and manage to adapt to the ways of traveling and remaining so atypical of a sector like La Candelaria
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