Análise de proveniência das contas verdes dos Perdigões

A variscite é um mineral raro que oferece uma excelente opotunidade de estudo dos padrões de comércio e troca na Europa durante a Pré- História através da determinação da sua fonte de proveniência. No presente texto será discutida a proveniência das contas de colar verdes com base em análises de XRF e XRD, através das quais se criou uma identidade geoquímica passível de ser comparada com as das fontes de variscite conhecidasVariscite is a rare mineral that offers an excellent opportunity to study trade and exchange patterns in prehistoric Europe through proveniencing of source material. In this paper we discuss the provenance of Perdigões’ green beads by means of XRF and XRD analyses, thus creating a geochemical baseline that is compared with that of the known variscite source

Slow Light Effects in Photonic Integrated Circuits with Application to Microwave Photonics

Esta tesis doctoral tiene como objetivo el diseño y la implementación de dispositivos ópticos novedosos capaces de realizar tareas de procesado de señales de rediofrecuencia, concretamente en las bandas de microondas y milimétricas, explotando para ello efectos de luz lenta que tienen lugar sobre algunos medios físicos que presentan características especiales. Con este propósito, se han investigado estructuras basadas en tecnología de semiconductor en guiaonda, además de estructuras de naturaleza resonante sobre circuitos en silicio y compuestos híbridos fabricados con materiales activos pertenecientes a los grupos III-V sobre silicio. En concreto, se han prouestos diferentes circuitos ópticos capaces de desarrollar tareas propias de desfasador y retardadeo verdadero de banda ancha para señales de radiofrecuncia. El comportamiento de dichos circuitos ópticos bajo estudio se ha caracterizado mediante modelado teórico, quedando éstos adecuadamente validados a través de resultados experimentales. En primer lugar, se han llevado a cabo estudios concernientes a la degradación producida por ruido en estructuras desfasadores formadas por amplificadores ópticos de semiconductor. Como resultado, se ha propuesto una nueva estructura que ha revertido en un rendimiento optimizado en términos de ruido sin que ello suponga una alteración en su funcionnalidad básica como desfasador. Esta estructura desfasadora ha sido el elemento clave en el ensamblado de un filtro elimina banda sintonizable. En segundo lugar, se han utilizado diferentes configuraciones basadas en anillos de silicio con dimensiones micrométricas para el desarrollo e implementación de diferentes procesadores de señal, tales como filtros reconfigurables y sintonizables y retardadores multicanal. Concretamente, se ha introducido un nuevo concepto inspirado en la técnica conocida como SCT, cuyo beneficio redunda en un aumento considerable del ancho de banda útil de las señales de radiofrecuencia a procesar gracias aLloret Soler, JA. (2012). Slow Light Effects in Photonic Integrated Circuits with Application to Microwave Photonics [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/16472Palanci

Vertical facing panel-joint gap analysis for steel-seinforced soil walls

This paper reports the results of a numerical parametric study focused on the prediction of vertical load distribution and vertical gap compression between precast concrete facing panel units in steel-reinforced soil walls ranging in height from 6 to 24 m. The vertical compression was accommodated by polymeric bearing pads placed at the horizontal joints between panels during construction. This paper demonstrates how gap compression and magnitude of vertical load transmitted between horizontal joints are influenced by joint location along the height of the wall, joint compressibility, and backfill and foundation soil stiffness. The summary plots in this study can be used to estimate the number and type (stiffness) of the bearing pads to ensure a target minimum gap thickness at the end of construction, to demonstrate the relative influence of wall height and different material component properties on vertical load levels and gap compression, or as a benchmark to test numerical models used for project-specific design. The paper also demonstrates that although the load factor (ratio of vertical load at a horizontal joint to weight of panels above the joint) and joint compression are relatively insensitive to foundation stiffness, the total settlement at the top of the wall facing is very sensitive to foundation stiffness. This paper examines the quantitative consequences of using a simple linear compressive stress–strain model for the bearing pads versus amultilinear model that is better able to capture the response of bearing pads taken to greater compression. The study demonstrates that qualitative trends in vertical load factor are preserved when a more advanced stress-dependent stiffness soil hardening model is used for the backfill soil as compared with the simpler linear elastic Mohr–Coulomb model. Although there were differences in vertical loads and gap compressionwith the use of both soilmodels for the backfill, the differenceswere small and not of practical concern.Peer ReviewedPostprint (author's final draft

Anisotropic behaviour of compacted clayey silt subjected to hydromechanical paths

Compaction induces anisotropy on soil deformational response due to preferential straining associated with the fabrication process. An experimental insight into the stress-strain response of Barcelona clayey silt is provided here. The material was statically compacted at low dry density to induce high collapsibility upon wetting (dry density 1.48 Mg/m3, water content 12%). Two types of controlled-suction tests were carried out: a) constant suction radial paths on as-compacted samples following different stress ratios (deviator stress / mean net stress: q/p Compaction induces anisotropy on soil deformational response due to preferential straining associated with the fabrication process. An experimental insight into the stress-strain response of Barcelona clayey silt is provided here. The material was statically compacted at low dry density to induce high collapsibility upon wetting (dry density 1.48 Mg/m3, water content 12%). Two types of controlled-suction tests were carried out: a) constant suction radial paths on as-compacted samples following different stress ratios (deviator stress / mean net stress: q/p¿, including isotropic and K0 stress paths; and b) the same type of radial stress paths but performed after saturation under low confining stress. These paths were intended to define the as-compacted and saturated yield surfaces. The experimental data on as-compacted state is satisfactorily interpreted adopting an anisotropic yield surface with an inclination linked to the compaction under oedometer conditions. Development of shear strain was observed during isotropic loading of the compacted samples. This anisotropy that the soil exhibits at the end of the compaction vanishes after collapse by saturation and as plastic volumetric straining develop

Coupled analysis of a backfill hydration test

BACCHUS2 in situ isothermal wetting experiment has been analysed by means of a coupled flow-deformation approach. Backfill material, a mixture of Boom clay powder and high density pellets, has been extensively tested in the laboratory in order to determine its hydraulic and mechanical properties. Parameters of constitutive equations were derived from this experimental data base. Two mechanical constitutive models have been used in the simulation of the 'in situ' experiment: a state surface approach and an elastoplastic model. Calculations have shown several features of the hydration process which help to understand the behaviour of expansive clay barriers. Predictions using both models have been compared with each other and with actual measurement records. This has allowed a discussion of the comparative mertis of both approaches and the identiÞcation of some critical parameters of backfill behaviour. Overall agreement between calculations and field measurements is encouraging and shows the potential of the methods developed to model the behaviour of engineered clay barriers in the context of nuclear waste disposal

A Sociocybernetics Data Analysis Using Causality in Tourism Networks

The aim of this paper is to propose a mathematical model to determine invariant sets, set covering, orbits and, in particular, attractors in the set of tourism variables. Analysis was carried out based on a pre-designed algorithm and applying our interpretation of chaos theory developed in the context of General Systems Theory. This article sets out the causal relationships associated with tourist flows in order to enable the formulation of appropriate strategies. Our results can be applied to numerous cases. For example, in the analysis of tourist flows, these findings can be used to determine whether the behaviour of certain groups affects that of other groups and to analyse tourist behaviour in terms of the most relevant variables. Unlike statistical analyses that merely provide information on current data, our method uses orbit analysis to forecast, if attractors are found, the behaviour of tourist variables in the immediate future

Temperature effects on the hydraulic behaviour of an unsaturated clay

The influence of temperature on the hydraulic properties of unsaturated clays is of major concern in the design of engineered barriers in underground repositories for high-level radioactive waste disposal. This paper presents an experimental study centred on the investigation of the influence of temperature on soil hydraulic properties related to water retention and permeability. Laboratory tests were conducted on artificially prepared unsaturated fabrics obtained from a natural kaolinitic-illitic clay. Special attention is given to the testing procedures involving controlled suction and temperature oedometer cells and the application of the vapour equilibrium technique at high temperatures. Retention curves at different temperatures show that total suction tends to reduce with increasing temperatures at constant water content. Temperature influence on water permeability is more relevant at low matric suctions corresponding to bulk water preponderance (inter-aggregate zone). Below a degree of saturation of 75% no clear effect is detected. Experimental data show that temperature dependence on permeability at constant degree of saturation and constant void ratio is smaller than what could be expected from the thermal change in water viscosity. This behaviour suggests that phenomena such as porosity redistribution and thermo-chemical interactions, which alter clay fabric and pore fluid, can be relevant

Suction effects on a compacted clay under non-isothermal conditions

The paper presents the results of an experimental study on the effects of suction and temperature on the volumetric behaviour of an unsaturated soil. Statically compacted Boom clay samples have been used in the testing programme, which has been performed using an oedometer apparatus with simultaneous control of suction and temperature. Suctions up to 0·45 MPa and temperatures up to 80°C have been applied. Special measures have been taken to control and minimise the problems associated with phase changes and vapour migration at high temperatures. A comprehensive experimental programme has been carried out, including isothermal tests with control of vertical stress, suction and temperature, non-isothermal tests under constant suction, and isothermal swelling pressure tests. Testing samples at two compacted soil densities provides observations concerning a wide scope of behaviour ranging from collapse to swelling behaviour on wetting. Test results obtained at 80°C have been compared with those of tests performed at room temperature (22°C). Based on these comparisons, thermal effects on a variety of features of behaviour such as swelling potential, swelling pressure, collapsibility, shrinkage strains, compressibility, stress path dependence and degree of strain reversibility are presented and discussed. Although the basic behaviour is similar at high and low temperatures, various significant differences are identified concerning mainly swelling strains developed during wetting and compressibility with respect to loading. Swelling pressure test results indicate that the high-temperature samples yield at a lower stress than that observed in room-temperature samples, suggesting that the stress domain bounded by the main yield surface reduces as temperature increases—a behaviour feature shared with saturated soils

Cuentas de variscita: producción, circulación y presencia en contextos funerarios del suroeste peninsular

En este trabajo, a partir del estudio de unos casos concretos, la problemática de la presencia de las cuentas de collar de piedras verdes en los contextos funerarios del megalitismo del Suroeste peninsular duante la Prehistoria reciente en relación con los centros productores y redes de cirulación. Para ello, hemos realizado una investigación arqueométrica (XRD, XRF) de cuentas de collar procedentes de varias construcciones megalíticas de dos áreas geográficas que poseen dataciones radiocarbónicas calibradas, Cuenca Media del río Guadiana y Andévalo oriental (Huelva), y que comparamos con las fuentes de aprovisionamiento y minas de variscita de Pico Centeno (Encinasola, Huelva). El resultado provisional másd estacable, en torno al que planteamos la discusión, es que durante el III milenio ANE en el Sur peninsular se emplearon diversas materias primas (variscita, moscovita, talco y clorita) para la manufactura de elementos de adorno y su inclusión en redes de circulación de "productos exóticos" de escala regional y suprarregional.This work is focused on the relationship between green beads and the production centres during Iberian Peninsula Late Prehistory. To perform this research we have conducted scientific analyses (XRD, XRF) of beads coming from different megalithic contexts: Guadiana river middle basin and Oriental Andévalo (Huelva), that have been compared with the mineral recovered during the suvery and excavation of Pico Centeno variscite mines (Encinasola, Huelva). These results are discussed on the context of prehistoric exchange