Libro de ruta para un ingeniero de turno de una tuneladora EPB

El túnel es un tipo de infraestructura que se adapta bien a las necesidades actuales de comunicación y medio ambiente requeridas por la sociedad. Ambos conceptos hacen del túnel un elemento de presente y de futuro; cada vez se hacen más túneles, más largos y en condiciones más adversas, en los que las tuneladoras juegan un papel importante. Esta realidad se puede constatar en todos los países desarrollados, entre los que España y Cataluña no son una excepción sino todo lo contrario: nuestra orografía, geología y uso del suelo nos obliga a la construcción de túneles con mayor intensidad que en otros muchos países. Sobra decir, que en estos momentos se encuentran operativas 14 tuneladoras sólo en el área metropolitana de Barcelona. De esta forma surge la presente tesina como necesidad de formar a los ingenieros de turno de una tuneladora tipo EPB, facilitando las herramientas y conocimientos básicos para que puedan opinar y evaluar, con criterio, la validez de los diferentes parámetros de control de este tipo de tuneladoras. No se pretende, en modo alguno, explicar exhaustivamente estos procesos dado que son complejos y de gran envergadura requiriendo una amplia experiencia que sólo con el tiempo y formación constante serán plenamente alcanzados. La metodología de trabajo se dividió básicamente en dos partes: Primero en una recopilación bibliográfica de libros, revistas, noticias periodísticas y tesinas relacionadas con el campo de los túneles. Y en una segunda parte, en una recopilación de experiencias de profesionales que han actuado en diversos proyectos de construcción de túneles mediante tuneladoras tipo EPB. Con toda la información recopilada, se identificaron los tres parámetros básicos influyentes en la generación de asientos que el ingeniero de turno debe controlar: presión en el frente, material extraído y mortero inyectado. Se relacionaron otros parámetros de control importantes para el mantenimiento de las diferentes herramientas de corte y se terminó con el estudio de algunos casos prácticos. Por último, en la presente tesina, se han extraído una serie de conclusiones y recomendaciones para concienciar al ingeniero de turno de la importancia de su labor y posición, teniendo una herramienta de aproximación que permita desarrollar correctamente sus tareas habitúales

Low cost vacuum web coating system

A low cost solution for a mini roll to roll web coating system is presented. The design is very simple and involves only three active rolls, two winding/unwinding rolls and a cooling drum. No extra load cells are used to control the web winding mechanism operation. To reach such result it has been necessary to develop an adequate control solution which acts on the two winding roll torques to make the web moving properly. The effect of the control mechanism is to increase electronically the total mechanical inertia of the roll to roll system. In such manner the stick-slip motion of the web, induced by the dry friction affecting the rotation of the rolls, is avoided. The effectiveness of this strategy has been corroborated: a first test showed that the web moves continuously while it is kept tense; in a second experiment a-Si material has been deposited by hot-wire chemical vapor deposition technique. For that material the optical transmission measurements at several points over the deposited area indicate a satisfactory uniformity. The presented tests validate the goodness of the new control method

Degradation of thin tungsten filaments at high temperature in HWCVD

The degradation of the filaments is usually studied by checking the silicidation or carbonization status of the refractory metal used as catalysts, and their effects on the structural stability of the filaments. In this paper, it will be shown that the catalytic stability of a filament heated at high temperature is much shorter than its structural lifetime. The electrical resistance of a thin tungsten filament and the deposition rate of the deposited thin film have been monitored during the filament aging. It has been found that the deposition rate drops drastically once the quantity of dissolved silicon in the tungsten reaches the solubility limit and the silicides start precipitating. This manuscript concludes that the catalytic stability is only guaranteed for a short time and that for sufficiently thick filaments it does not depend on the filament radius

Un museu per a la festa de Moros i Cristians a Oliva. Una proposta de dinamització del Centre Històric d'Oliva

Aquest treball consisteix en l'obertura d'un museu de Moros i Cristians a Oliva. Per a comprovar la viabilitat d'aquest projecte, s'ha estudiat la història de la festa (fonts secundàries: revisió documental

The role of hydrogen in the formation of microcrystalline silicon

The growth mechanisms of microcrystalline silicon thin films at low temperatures (100-250°C) by plasma CVD are still a matter of debate. We have shown that ue-Si:H formation proceeds through four phases (incubation, nucleation, growth and steady state) and that hydrogen plays a key role in this process, particularly during the incubation phase in which hydrogen modifies the amorphous silicon network and forms a highly porous phase where nucleation takes place. In this study we combine in-situ ellipsometry and dark conductivity measurements with ex-situ high resolution transmission electron microscopy to improve our understanding of microcrystalline silicon formation

Yttrium oxide passivation of porous silicon for improved photoluminescence and optoelectronic properties

This paper reports on the effect of yttrium oxide as a novel treatment to improve the photoluminescence intensity and stability of porous silicon (PS). Yttrium oxide (Y2O3) was incorporated into the PS layers by impregnation method using a saturated aqueous solution. The penetration of Yttrium into the PS microstructure was examined using the Energy Dispersive X-ray spectrometry (EDS) and the Backscattered Electron Detector (BED-C) for composition imaging and analysis. The morphology of the front surface was studied using a Field Emission Scanning Electron Microscope (FESEM). The deposited yttrium oxide onto the PS layers was thermally activated to passivate efficiently the silicon dangling bonds, and prevent the porous silicon from huge oxidation. The photoluminescence (PL) peak intensity of impregnated PS was increased noticeably compared to the as-prepared untreated PS. Unlike the as-prepared PS photoluminescence dependence with aging, the yttrium-passivated PS layers PL peak shows no shifts during aging allowing a high stability. Furthermore, we obtained a significant improvement of the effective minority lifetime (Teff) after a short anneal at 600 °C, while increasing the temperature reduces noticeably the passivation properties. The improved surface passivation experienced after the thermal annealing can be ascribed to yttrium diffusion into the PS layer, with a resulting redistribution of yttrium oxide and subsequent passivation of silicon dangling bonds in the sub-interface region, this was confirmed by EDS analysis. The internal quantum efficiency (IQE) measurements were performed to study the optoelectronic properties of the processed monocrystalline silicon substrates

Investigations on doping of amorphous and nano-crystalline silicon films deposited by catalytic chemical vapour deposition

Hydrogenated amorphous and nanocrystalline silicon, deposited by catalytic chemical vapour deposition, have been doped during deposition by the addition of diborane and phosphine in the feed gas, with concentrations in the region of 1%. The crystalline fraction, dopant concentration and electrical properties of the films are studied. The nanocrystalline films exhibited a high doping efficiency, both for n and p doping, and electrical characteristics similar to those of plasma-deposited films. The doping efficiency of n-type amorphous silicon is similar to that obtained for plasma-deposited electronic-grade amorphous silicon, whereas p-type layers show a doping efficiency of one order of magnitude lower. A higher deposition temperature of 450°C was required to achieve p-type films with electrical characteristics similar to those of plasma-deposited films