Doppler Boosting and cosmological redshift on relativistic jets

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2020, Tutor: Valentí Bosch i RamonIn this study our goal was to identify the possible effects that influence with the Spectral Energy Distribution of a blazar, which we deducted that are Doppler Boosting effect and cosmological redshift. Then we investigated how the spectral energy distribution varies by changing intrinsic parameters of the jet like its Lorentz factor, the angle of the line of sight respect to the jet orientation or the blazar redshift. The obtained results showed a strong enhancing of the Spectral Energy Distribution for nearly 0º angles and high Lorentz factors, while the increase in redshift produced the inverse effect, reducing the normalization of the distribution and moving the peak to lower energies. These two effects compete in the observations of all known blazars and our simple model confirmed the experimental results, that only those blazars with optimal characteristics, if at very high redshift, are suitable to be measured by the actual instruments, making the study of blazars with a high redshift an issue that needs very deep observations at different wavelengths to collect enough data to properly characterize the source populatio

Determinant factors in dynamics of global manufacturing virtual networks

Objeto: Demostrar la existencia de una serie de mecanismos estructurales que los actores utilizan como herramientas para poder ejercer un poder tácito en las RVFGs. Diseño/metodología: Análisis de la industria de fabricación de motores aeronáuticos mediante un enfoque cuantitativo basado en un modelo logístico binomial utilizando una función logit. Resultados: Los Original Equipment Manufacturers (OEMs) ejercen un poder tácito en la red mediante su posición centralizada en la red y la existencia de muchos agujeros estructurales. Los proveedores, sin embargo, establecen muchos lazos fuertes y directos con otros actores para fomentar la confianza; mientras que los nuevos actores establecen muchos lazos indirectos para acceder a conocimiento explícito. Limitaciones: Otros estudios similares a RVFGs de otros sectores industriales como el electrónico, químico o automoción reforzarían los resultados obtenidos en este estudio. Implicaciones prácticas: Se facilita ex ante el diseño de nuevas RVFGs aumentando sensiblemente su eficiencia Valor añadido: Clarifica el funcionamiento interno de estas organizaciones que hasta ahora no se había abordado bajo este punto de vista. Sus conclusiones pueden utilizarse como un modelo prescriptivo para otras redes de fabricación.Peer Reviewe

Un Nuevo Marco Estratégico en las Redes Virtuales de Fabricación Global

Este trabajo propone un marco teórico basado en una triple perspectiva estratégica que permite alinear de una manera coherente la estrategia de las empresas que forman parte de una Red Virtual de Fabricación Global (RVFG) bajo tres perspectivas: 1) Perspectiva Estratégica Nodal: basada en un enfoque tradicional y endogámico de búsqueda de ventajas competitivas inimitables; 2) Perspectiva Estratégica Diádica: basada en colaboraciones con otras empresas de la red para alcanzar escenarios de beneficio mutuo evitando conductas oportunistas y 3) Perspectiva Estratégica Sistémica: basada en una visión de la red como sistema homogéneo donde el elevado nivel de confianza y el encaje de actividades específicas de sus actores permitirá que ésta pueda competir eficientemente en el mercado frente a otras redes

Structure and relationships within global manufacturing virtual networks/Estructura y relaciones en las redes virtuales de fabricación global

Global Manufacturing Virtual Networks (GMVNs) are dynamically changing organizations formed by Original Equipment Manufacturers (OEMs), Contract Manufacturers (CMs), turn-key and component suppliers, R+D centres and distributors.These networks establish a new type of vertical and horizontal relations between independent companies or even competitors where it is not needed to maintain internal manufacturing resources but to manage and share the network resources.The fluid relations that exist within the GMVNs allow them a very permeable organization easy to connect and disconnect from one to each other as well as to choose a set of partners with specific attributes. The result is a highly flexible system characterized by low barriers to entry and exit, geographic flexibility, low costs, rapid technological diffusion, high diversification through contract manufacturers and exceptional economies of scale. Anyhow, there are three major drawbacks in the GMVNs that should be considered at the beginning of this type of collaborations: 1) the risk of contract manufacturers to develop their own end-products in competition with their customers; 2) the technology transfer between competitors OEMs through other members of the GMVN and 3) the lose of process expertise by the OEMs the more they outsource manufacturing processes to the network

Dinámica de las Redes Virtuales de Fabricación Global en la Industria Aeronáutica

Las redes virtuales de fabricación global (RVFGs) están formadas por empresas independientes las cuales establecen entre sí relaciones de tipo horizontal y vertical, pudiendo incluso ser competidores, donde no es necesario mantener internamente grandes recursos fabriles sino gestionar y compartir eficientemente los recursos de la red. Sin embargo, los riesgos inherentes de estas redes de colaboración, entre OEMs competidores y proveedores también son numerosos. Para evitar esto, los OEMs utilizan una serie de mecanismos estructurales como los posicionamientos centralizados en la red o el uso de los agujeros estructurales para así conseguir mantener un poder tácito en la RVFG. Este trabajo demostrará cómo se gestiona el poder en estas organizaciones y la importancia de estos mecanismos mediante un estudio cuantitativo en uno de los sectores donde más han crecido las RVFGs, la industria de fabricación de motores aeronáutico

Let others manufacture! Towards a new manufacturing framework

Global manufacturing virtual networks (GMVNs) constitute a new type of vertical and horizontal relations between independent companies or even competitors where it is not needed to maintain internal manufacturing resources but to manage and share the network resources. The fluid relations that exist within the GMVNs allow them a very permeable organization easy to connect and disconnect from one to each other as well as to choose a set of partners with specific attributes. The result is a highly flexible system characterized by low barriers to entry and exit, geographic flexibility, low costs, rapid technological diffusion, high diversification through contract manufacturers and exceptional economies of scale and specialization. This paper analyses the causes behind the formation of such networks, their strategy, structure, dynamics and culture, taking into account areas such as strategic alliances between competitors, the permeable and diffuse nature of the network actors, the inherent paradox of collaborating with competitors, cross-cultural issues or information and communication technologies at the network level. This work will clarify and put these organizations in perspective and will analyze their evolution over the next few years

Strategic positioning of global manufacturing virtual networks in the aeronautical industry

The evolution of organizations that work in multinational environments has considerably altered their production strategies. One of the consequences has been the appearance of Global Manufacturing Virtual Networks (GMVNs), which include all kinds of production centres and establish a new type of vertical and horizontal collaboration between independent companies or even competitors who establish occasional collaborations on projects they could not take on individually. This paper analyses the causes behind the formation of such networks, their strategy positioning and future evolution. For that purpose, a conceptual framework is proposed based on four network features: strategy, structure, communication systems and culture. This work will deep into the strategy network feature by applying a strategic positioning model to a practical case in the aeronautical industry to gain a better understanding of how GMVNs work, its effectiveness by clarifying and putting these organizations in perspective and how they may evolve in the future

Modelo estocástico de hueso cortical de costilla humana para la predicción de fracturas mediante emisión acústica

In this document, a non-linear constitutive model with micro-cracking and irreversibility is proposed for cortical bone of the human rib, extended with a stochastic fracture model, based on acoustic emission. Both models are innovative and describe the behavior of the human rib from the zero-load to macroscopic fracture. Experimentally, the models have shown to describe adequately the mechanical behavior of the rib, even in the non-elastic zone, where irreversible processes have been mainly associated with the propagation of micro-cracks through the material. Furthermore, the constitutive model is thermodynamically consistent, showing a notable increase in entropy as cracking process goes on, a region in which, in turn, a notable asymptotic increase in the released energy by the material has been observed in the form of waves, detected by the acoustic emission technique. In addition, the constitutive parameters of the model show significant correlation both with anthropometric variables and with micro-structural parameters, such as density, fractal dimension or mineral content, pointing to a clear importance of micro-structure in the behavior of cortical bone. Thus, the quenched disorder parameter, which represents the micro-structural damage previous to failure and which has been introduced into the model by means of the Statistical Mechanics, has shown to have a great influence of age. Likewise, a relationship has also been found between the mineralization of the sample and the possible paths that the main crack can take in its progression through the osteon network. The number of paths has been determined by means of combinatorics. On the other hand, the stochastic fracture model adequately and quantitatively predicts the occurrence of acoustic signals or hits associated with the stress level introduced into the sample, being one of the first models developed for bone.En esta memoria se propone un modelo constitutivo no lineal con microfisuración e irreversibilidad para hueso cortical de costilla humana, ampliado con un modelo estocástico de fractura, basado en emisión acústica. Ambos modelos son innovadores y describen el comportamiento de la costilla humana desde el inicio de la solicitación hasta la fractura macroscópica. Experimentalmente los modelos han mostrado modelizar adecuadamente el comportamiento mecánico de la costilla, incluso en la zona no elástica, donde los procesos irreversibles han sido asociados principalmente a la propagación de microfisuras a través del material. Además, el modelo constitutivo es termodinámicamente consistente, mostrando un incremento notable en la entropía a medida que se promueve la fisuración, región en la que, a su vez, se ha observado un notable incremento asintótico de la energía liberada por el material en forma de ondas, detectadas por la técnica de emisión acústica. Además, los parámetros constitutivos del modelo exhiben correlaciones significativas tanto con variables antropométricas, como con parámetros microestructurales, tales como la densidad, la dimensión fractal o el contenido mineral, denotando una clara importancia de la microestructura en el comportamiento del hueso cortical. En este contexto, el parámetro de atemperación del desorden, que representa el daño microestructural previo a la solicitación y que ha sido introducido en el modelo por medio de la mecánica estadística, ha mostrado tener una gran influencia con la edad. Así mismo, también se ha encontrado una relación de la mineralización de la muestra con los caminos posibles que la fisura puede tomar en el avance a través de la red de osteonas. El número de caminos ha sido determinado mediante la combinatoria. Por otro lado, el modelo estocástico de fractura predice adecuadamente y de manera cuantitativa la aparición de señales acústicas o hits asociados al nivel de tensión introducido en la muestra, siendo uno de los primeros modelos desarrollados en hueso.Enginyeria mecànica, fluids i aeronàutic

Dinámica de las Redes Virtuales de Fabricación Global en la Industria Aeronáutica.

Global manufacturing virtual networks (GMVNs) constitute a new type of organization based on vertical and horizontal relations between independent companies or even competitors where it is not needed to maintain internal manufacturing resources but to manage and share the network resources. The result is a highly flexible system characterized by low barriers to entry and exit, geographic flexibility, low costs, rapid technological diffusion, high diversification through contract manufacturers and exceptional economies of scale and specialization. Within GMVNs, relations are established among Original Equipment Manufacturers (OEMs), component suppliers performing at the same level as the OEMs under formulas such as Risk and Revenue Sharing Partnership (RRSP), or even manufacturers from another industrial sectors. However, the inherent risk of working with competitors is also very relevant. In order to avoid these problems, the OEMs use a variety of structural mechanisms like the utilization of central network positioning, structural holes or indirect links with peripheral actors, in order to be able to maintain a tacit power over other GMVN actors. This work will demonstrate how power is managed in these organizations and the importance of these mechanisms through a quantitative study in one of the sectors where GMVNs have more intensively grown, the manufacturing industry of aircraft engines. This study will permit to know, in a clear manner, how these networks work, to give perspective to one of the organization types that have grown to a great extend over the past years.Global Manufacturing Virtual Networks; structural holes; aeronautical industry