Numerical Implementation of a Critical State Model for Soft Rocks

This paper details the basic tasks for the numerical implementation of a simple elasto-plastic critical state model for bonded materials (i.e. soft rocks-hard soils) into the finite element program SNAC developed at the University of Newcastle in Australia. The first task described focusses on the derivation of the incremental constitutive relationships used to represent the mechanical response of a bonded/cemented material under saturated conditions. The second task presents how these stress-strain relations can be numerically integrated using an explicit substepping scheme with automatic error control. The third task concentrates on the verification of the substepping algorithm proposed. The model used to represent the saturated mechanical response of a bonded material combines the modified Cam clay with the constitutive relationships for cemented materials proposed in Gens & Nova (1993), but incorporates some flexibility on the degradation law adopted. The role of suction and other relevant aspects of unsaturated behaviour are also discussed at the end of the paper

Influence of Mechanical Yielding on Predictions of Saturation: The Saturation Line

It is now well accepted that the mechanical and the water retention behaviour of a soil under unsaturated conditions are coupled and, that such coupling, should be incorporated into a constitutive model for a realistic representation of soil’s response. In existing models, the influence of the mechanical behaviour on the water retention is often represented by a shift of the main wetting retention curve to higher values of matric suction (the difference between pore air and pore water pressures) when the specific volume decreases. This means that any variation of total volumetric strains of compression (whether these are elastic or elasto-plastic) will result in a shift of the main wetting and drying curves to the right, when these curves are represented in the water retention plane. This shift of the main water retention curves, however, should not only influence the unsaturated stress states as often described in the literature, it should also have some impact on the saturated stress states and, more specifically, on the predictions of de-saturation (air-entry point) and saturation (air-exclusion point). From a modelling point of view, it is advantageous to represent this influence through the plastic component of volumetric strain of compression only because, in this way, a consistent representation of the mechanical behaviour for both unsaturated and saturated states can be naturally achieved. This and other advantages resulting from this singular approach are demonstrated in the paper in the context of the Glasgow Coupled Model (GCM)

Analysis and optimization of energy usage in Supermarkets

The thesis performed in this research is focused on a particular type of energy system, energy systems in supermarkets. As supermarkets are high-energy using buildings, their energy system optimization has been investigated in recent years, with the main focus in the refrigeration system, which can take up to 50% of the total energy of the supermarket. However, the complexity and interconnections of the different systems increase the difficulty of the task. The aim of this work is to contribute in SuperSmart project, an EU project which main objective is to reduce the impact of the supermarket sector overall Europe, through the development of an ecolabel criteria. To simulate the energy use in supermarkets, CyberMart software is bring forward. This tool is used both to determine the parameters which have a higher impact in the supermarket energy system and perform energy representation based on those parameters. Finally, the design of the most energy efficient store is also presented. According to CyberMart, some of the most determinant parameters in the supermarket energy system are refrigeration capacities, plug in cabinets used, lights power, heating system technologies used and whether the cabinets are covered or not. Using some of these parameters plus other important characteristics from the store, two energy representations are performed. The linear energy representation provides the increase or decrease of kWh per each parameter, enabling supermarkets owners to compare different parameters within the global system. These representations, which distinguish between heat recovery and floating condensing technologies, conclude that the most important parameters in the global system are the temperature inside at winter and the refrigeration capacity. However, some unreasonable events appear, like the decline of electricity demand when the height of the building increases or the drop of heat demand with the rise of opening hours. These facts occur due to the high complexity of the global system, implying different connections between the sub-systems within CyberMart. Concerning the most energy efficient store located in Stockholm, the obtained results show the most energy efficient supermarket is composed by CO2 refrigeration and heating systems, and a R410_A air conditioning system. The optimal electricity use of each establishment size from large to small area is 382, 394, 390 and 281 kWh/m2*year respectively, with the highest values obtained in Supermarkets and Discount stores, due to their higher rate of refrigeration power per store area

Security in networks of unmanned aerial vehicles for surveillance with an agent-based approach inspired by the principles of blockchain

Unmanned aerial vehicles (UAVs) can support surveillance even in areas without network infrastructure. However, UAV networks raise security challenges because of its dynamic topology. This paper proposes a technique for maintaining security in UAV networks in the context of surveillance, by corroborating information about events from different sources. In this way, UAV networks can conform peer-to-peer information inspired by the principles of blockchain, and detect compromised UAVs based on trust policies. The proposed technique uses a secure asymmetric encryption with a pre-shared list of official UAVs. Using this technique, the wrong information can be detected when an official UAV is physically hijacked. The novel agent based simulator ABS-SecurityUAV is used to validate the proposed approach. In our experiments, around 90% of UAVs were able to corroborate information about a person walking in a controlled area, while none of the UAVs corroborated fake information coming from a hijacked UAV

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

Los coeficientes ofensivos y defensivos. Una aportación al estudio práxico de los deportes de equipo

El waterpolo es un deporte acuático de equipo, sujeto a unas normas e institucionalizado, que se practica en una superficie limitada de piscina entre dos conjuntos de siete jugadores de campo (seis jugadores y portero) y con la finalidad de introducir el balón en la portería contraria. El objeto de estudio se centró en el análisis práxico de la acción de juego de 10 partidos de waterpolo de la fase preliminar y semifinales de los Juegos Olímpicos de Barcelona-1992, que nos ayudaron a confeccionar los coeficientes de valoración ofensiva y defensiva, para la cuantificación de la praxis de cualquier juego de equipo. Para ello fue necesario establecer un procedimiento que representara gráfica o textualmente las secuencias de la acción de juego efectuadas por los jugadores de un equipo deportivo, y que pudiera recoger todo el desarrollo práxico del juego -el Praxiograma-, el cual estudiará las acciones práxicas del juego portadoras de una lógica intema explícita. A consecuencia de este procedimiento pudimos establecer los coeficientes ofensivos y defensivos del juego de equipo que nos permitieron poder cuantificar las acciones técnicas y tácticas que consideramos más relevantes para nuestro trabajo. La valoración mediante coeficientes ofensivos y defensivos es un nuevo método de estudio y análisis de los deportes de cooperación y oposición que proporciona una información concreta sobre acciones específicas de juego, y que pueden ser de interés al técnico. En este sentido, los resultados de estos coeficientes en los juegos Olímpicos de Barcelona-92, podría ser un punto de partida y una aportación válida para que otros investigadores se posicionen y efectúen estudios de correlación o análisis para la mejora de dichos coeficientes o la creación de otros más relevantes en su deporte de equipo. De este estudio se deriva la posibilidad de realizar praxiogramas por métodos informáticos y conseguir un rápido tratamiento de los datos e información directa y relevante para el técnico ya que, a partir de las planillas u hojas de recogida de datos se generan las hojas de clasificación de datos y las de interacción ataque/defensa, así como los gráficos y todo el tratamiento estadístico que desee contemplarse en el partido o competición a analizar. Además de lo considerado como resultados praxiogramáticos, este trabajo se plantea como un medio al alcance de los técnicos y entrenadores de alto nivel, para optimizar el rendimiento de sus jugadores y equipos, a partir del conocimiento exhaustivo de cada una de las acciones de juego realizadas en el transcurso del partido