Gesture based persuasive interfaces for public ambient displays

Dissertação de Mestrado em Engenharia Informática 2º Semestre, 2011/2012

Multipacket reception in LTE femtocell networks

Dissertação apresentada para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores

QoS in LEO satellite networks with multipacket reception

Dissertação apresentada para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

Business model: What should be the strategy used by Smart Galp to implement and potentiate its value proposition in the Portuguese market?

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

Potential for ORC application in the Portuguese manufacturing industry

Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente, perfil Gestão e Sistemas Ambientais

Earthen plasters: the potential of the clayey soils of barrocal region in Algarve

Due to their high adsorption capacity of water vapor, earthen plasters can act as a moisture buffer, contributing to balance the relative humidity of the indoor environment of buildings. As a consequence of this capacity earthen plasters may also contribute to the perception of thermal comfort, since a high relative humidity increases the thermal conductivity of air and restricts skin evaporation, increasing the discomfort associated with the perception of heat or cold. Simultaneously, earthen plasters may also contribute to the indoor air quality. In one hand, by mitigating health problems of the respiratory system associated with indoor environment with high relative humidity, in which increases the risk of development of microorganisms usually responsible for infections, allergies or asthma. In the other hand, by mitigating the probability of inflammation of the respiratory system airways associated to exceedingly dry indoor environments. Therefore it also becomes expectable that earthen plasters may contribute for reducing the needs for air conditioning and mechanical ventilation in buildings and, thereby, also allowing the reduction of the associated energy consumption. The «Barrocal» region, located in the sedimentary basin of Algarve, South Portugal, presents geomorphological characteristics that promote the occurrence of soils with a clay mineralogy dominated by illite, which is a clay mineral characterized by a high adsorption capacity of water vapor and low expansibility. This fact turns expectable that these soils have a high potential for interior plastering. In order to evaluate this potential four mortars were formulated with an increasing content of clayey soil extracted from a selected clay quarry from «Barrocal» region. The results from the preliminary characterization campaign confirmed the reduced linear shrinkage of these mortars, as well as their high adsorption-desorption capacity, that is positively correlated with the content of clayey soil present in mortar formulation. However, the mechanical tests showed that the mechanical resistance of these mortars should be improved, for instance through the addition of natural fibers for reinforcement, which will be investigated in future research. This research contributed to increase certainty regarding the potential of clayey soils of the «Barrocal» sub-region of Algarve to produce mortars suitable for eco-efficient interior plastering.

Sustainable urban planning: parameters to the operational process

In modern society, energy consumption and respect for the environment have become essential aspects of urban planning. The rising demand for alternative sources of energy, coupled with the decline in the construction sector and material usage, gives the idea that the thinking on modern cities, where attention is given to reduced energy consumption, savings, waste recycling and respect for the surrounding environment, is being put into practice. If we examine development of the city over recent centuries, by means of the theories of the most famous and influential urban planners, it is possible to identify the major problems caused by this type of planning. For this reason, in recent urban planning the use of systems of indicators that evaluate and certify land environmentally and energetically guides the master plan toward a more efficient city model. In addition the indicators are targeted on key factors determined by the commissioner or the opportunities the territory itself provides. Due the complexity of the environmental mechanics, the process of design and urban planning has become a challenging issue. The introduction of the indicators system has made it possible to register the life of the process, with a spiral route that allows the design itself to be refined. The aim of this study, built around the creation of a system of urban sustainability indicators that will evaluate highly eco-friendly cities, is to develop a certification system for cities or portions of them. The system will be upgradeable and objective, will employ real data and will be concerned with energy production and consumption.

Multipacket reception in the presence of in-band full-duplex communication

In-Band Full-DupleX (IB-FDX) is defined as the ability for nodes to transmit and receive signals simultaneously on the same channel. Conventional digital wireless networks do not implement it, since a node’s own transmission signal causes interference to the signal it is trying to receive. However, recent studies attempt to overcome this obstacle, since it can potentially double the spectral efficiency of current wireless networks. Different mechanisms exist today that are able to reduce a significant part of the Self- Interference (SI), although specially tuned Medium Access Control (MAC) protocols are required to optimize its use. One of IB-FDX’s biggest problems is that the nodes’ interference range is extended, meaning the unusable space for other transmissions and receptions is broader. This dissertation proposes using MultiPacket Reception (MPR) to address this issue and adapts an already existing Single-Carrier with Frequency-Domain Equalization (SC-FDE) receiver to IB-FDX. The performance analysis suggests that MPR and IB-FDX have a strong synergy and are able to achieve higher data rates, when used together. Using analytical models, the optimal transmission patterns and transmission power were identified, which maximize the channel capacity with the minimal energy consumption. This was used to define a new MAC protocol, named Full-duplex Multipacket reception Medium Access Control (FM-MAC). FM-MAC was designed for a single-hop cellular infrastructure, where the Access Point (AP) and the terminals implement both IB-FDX and MPR. It divides the coverage range of the AP into a closer Full-DupleX (FDX) zone and a farther Half-DupleX (HDX) zone and adds a tunable fairness mechanism to avoid terminal starvation. Simulation results show that this protocol provides efficient support for both HDX and FDX terminals, maximizing its capacity when more FDX terminals are used.

Valorization of grape pomace through hot compressed water extraction/hydrolysis

The world energy consumption is expected to increase strongly in coming years, because of the emerging economies. Biomass is the only renewable carbon resource that is abundant enough to be used as a source of energy Grape pomace is one of the most abundant agro-industrial residues in the world, being a good biomass resource. The aim of this work is the valorization of grape pomace from white grapes (WWGP) and from red grapes (RWGP), through the extraction of phenolic compounds with antioxidant activity, as well as through the extraction/hydrolysis of carbohydrates, using subcritical water, or hot compressed water (HCW). The main focus of this work is the optimization of the process for WWGP, while for RWGP only one set of parameters were tested. The temperatures used were 170, 190 and 210 °C for WWGP, and 180 °C for RWGP. The water flow rates were 5 and 10 mL/min, and the pressure was always kept at 100 bar. Before performing HCW assays, both residues were characterized, revealing that WWGP is very rich in free sugars (around 40%) essentially glucose and fructose, while RWGP has higher contents of structural sugars, lignin, lipids and protein. For WWGP the best results were achieved at 210 °C and 10 mL/min: higher yield in water soluble compounds (69 wt.%), phenolics extraction (26.2 mg/g) and carbohydrates recovery (49.3 wt.% relative to the existing 57.8%). For RWGP the conditions were not optimized (180 °C and 5 mL/min), and the values of the yield in water soluble compounds (25 wt.%), phenolics extraction (19.5 mg/g) and carbohydrates recovery (11.4 wt.% relative to the existing 33.5%) were much lower. The antioxidant activity of the HCW extracts from each assay was determined, the best result being obtained for WWGP, namely for extracts obtained at 210 °C (EC50=20.8 μg/mL; EC50 = half maximum effective concentration; EC50 = 22.1 μg/mL for RWGP, at 180 ºC).

Distributed solar micro generation

Taking into account the fact that the sun’s radiation is estimated to be enough to cover 10.000 times the world’s total energy needs (BRAKMANN & ARINGHOFF, 2003), it is difficult to understand how solar photovoltaic systems (PV) are still such a small part of the energy source matrix across the globe. Though there is an ongoing debate as to whether energy consumption leads to economic growth or whether it is the other way around, the two variables appear correlated and it is clear that ensuring the availability of energy to match a country’s growth targets is one of the prime concerns for any government. The topic of centralized vs distributed electricity generation is also approached, especially in what regards the latter fit to developing countries needs, namely the lack of investment capabilities and infrastructure, scattered population, and other factors. Finally, Brazil’s case is reviewed, showing that the current cost of electricity from the grid versus the cost from PV solutions still places an investment of this nature with 9 to 16 years to reach breakeven (from a 25 year panel lifespan), which is too high compared to the required 4 years for most Brazilians. Still, recently passed legislation opened the door, even if unknowingly, to the development of co-owned solar farms, which could reduce the implementation costs by as much as 20% and hence reduce the number of years to breakeven by 3 years.

Electric vehicle assistant based in driver profile

This paper presents the outcomes of a research work consisting in the development of an Electric Vehicle Assistant (EVA), which creates and stores a driver profile where are contained the driving behaviours related with the EV energy consumption, the EV battery charging information, and the performed routes. This is an application for mobile devices that is able to passively track the driver behaviour and to access several information related with the EV in real time. It is also proposed a range prediction approach based on probability to take into account unpredictable effects of personal driving style, traffic or weather.

Sustainable mortars with incorporation of microencapsulated phase change materials

The construction industry is responsible for high energy and raw materials consumption. Thus, it is important to minimize the high energy consumption by taking advantage of renewable energy sources and reusing industrial waste, decreasing the extraction of natural materials. The mortars with incorporation of phase change materials (PCM) have the ability to regulate the temperature inside buildings, contributing to the thermal comfort and reduction of the use of heating and cooling equipment, using only the energy supplied by the sun. The simultaneous incorporation of PCM and fly ash (FA) can reduce the energy consumption and the amount of materials landfilled. However, the addition of these materials in mortars modifies its characteristics. The main purpose of this study was the production and characterization in the fresh and hardened state of mortars with incorporation of different contents of PCM and FA. The binders studied were aerial lime, hydraulic lime, gypsum and cement. The proportion of PCM studied was 0%, 20%, 40% and 60% of the mass of the sand. The content of fly ash added to the mortars was 0%, 20%, 40% and 60% of the mass of the binder. It was possible to observe that the incorporation of PCM and fly ash in mortars caused differences in properties such as workability, microstructure, water absorption, compressive strength, flexural strength and adhesion.

Development of foam one-part geopolymers with enhanced thermal insulation performance and low carbon dioxide emissions

Buildings are responsible for more than 40% of the energy consumption and greenhouse gas emissions. Thus, increasing building energy efficiency is one the most cost-effective ways to reduce emissions. The use of thermal insulation materials could constitute the most effective way of reducing heat losses in buildings by minimising heat energy needs. These materials have a thermal conductivity factor, k (W/m.K) lower than 0.065 while other insulation materials such as aerated concrete can go up to 0.11. Current insulation materials are associated with negative impacts in terms of toxicity. Polystyrene, for example contains anti-oxidant additives and ignition retardants. In addition, its production involves the generation of benzene and chlorofluorocarbons. Polyurethane is obtained from isocyanates, which are widely known for their tragic association with the Bhopal disaster. Besides current insulation materials releases toxic fumes when subjected to fire. This paper presents experimental results on one-part geopolymers. It also includes global warming potential assessment and cost analysis. The results show that only the use of aluminium powder allows the production mixtures with a high compressive strength however its high cost means they are commercially useless when facing the competition of commercial cellular concrete. The results also show that one-part geopolymer mixtures based on 26%OPC +58.3%FA +8%CS +7.7%CH and 3.5% hydrogen peroxide constitute a promising cost efficient (67 euro/m3), thermal insulation solution for floor heating systems with low global warming potential of 443 KgCO2eq/m3.

Comparative environmental life-cycle analysis of concretes using biomass and coal fly ashes as partial cement replacement material

Nowadays, the concrete production sector is challenged by attempts to minimize the usage of raw materials and energy consumption, as well as by environmental concerns. Therefore, it is necessary to choose better options, e.g. new technologies or materials with improved life-cycle performance. One solution for using resources in an efficient manner is to close the materials' loop through the recycling of materials that result either from the end-of-life of products or from being the by-product of an industrial process. It is well known that the production of Portland cement, one of the materials most used in the construction sector, has a significant contribution to the environmental impacts, mainly related with carbon dioxide emission. Therefore, the study and utilization of by-products or wastes usable as cement replacement in concrete can supply more sustainable options, provided that these type of concrete produced has same durability and equivalent quality properties as standard concrete. This work studied the environmental benefits of incorporating different percentages of two types of fly ashes that can be used in concrete as cement replacement. These ashes are waste products of power and heat production sectors using coal or biomass as fuels. The results showed that both ashes provide a benefit for the concrete production both in terms of environmental impact minimization and a better environmental performance through an increase in cement replacement. It is possible to verify that the incorporation of fly ashes is a sustainable option for cement substitution and a possible path to improve the environmental performance of the concrete industry.

Evaluation of the performance of recycled textile fibres in the mechanical behaviour of a gypsum and cork composite material

Given the need for using more sustainable constructive solutions, an innovative composite material based on a combination of distinct industrial by-products is proposed aiming to reduce waste and energy consumption in the production of construction materials. The raw materials are thermal activated flue-gas desulphurization (FGD) gypsum, which acts as a binder, granulated cork as the aggregate and recycled textile fibres from used tyres intended to reinforce the material. This paper presents the results of the design of the composite mortar mixes, the characterization of the key physical properties (density, porosity and ultrasonic pulse velocity) and the mechanical validation based on uniaxial compressive tests and fracture energy tests. In the experimental campaign, the influence of the percentage of the raw materials in terms of gypsum mass, on the mechanical properties of the composite material was assessed. It was observed that the percentage of granulated cork decreases the compressive strength of the composite material but contributes to the increase in the compressive fracture energy. Besides, the recycled textile fibres play an important role in the mode I fracture process and in the fracture energy of the composite material, resulting in a considerable increase in the mode I fracture energy.