Sistema de Posicionamento Acústico e Transmissão de Dados para Alvos Subaquáticos

With the increasing usage of unmanned underwater vehicles, the need to develop the different systems associated with them is also growing. One of the most essential systems for an unmanned vehicle is its positioning system. Due to the inherent characteristics of the medium, the most common positioning method in aquatic environments involves the use of acoustic signals that use time-of-flight measurements to locate a target, referencing it to a set of sensors. This dissertation presents an acoustic positioning system for underwater vehicles based on the measurement of arrival delays of three acoustic signals originating from emitters with known positions on the surface, providing data transmission by periodically sending a modulated signal with position information. This system includes several components. Firstly, there are three stationary emitters on the surface responsible for the periodic sending of modulated acoustic signals. Then, there is a receiver and an emitter on the target, the former being responsible for the acquisition of acoustic signals and the latter for sending an acoustic signal with the coded position. Finally, there’s a receiver on the surface responsible for capturing the signal with the coded position. The developed detection, coding and decoding algorithms are presented, as well as the hyperbolic positioning algorithm, the latter implemented with a Kalman filter for the position estimation. In addition, the development of hardware to enable the sending and reception of the acoustic signals is also analyzed. To validate the developed system, results obtained in field tests and in a simulation environment are presented.Com o crescente uso de veículos subaquáticos não tripulados, cresce também a necessidade de desenvolver os diferentes sistemas a eles associados. Um dos sistemas mais importantes para um veículo não tripulado é o seu sistema de posicionamento. Devido `as características inerentes ao meio, o método de posicionamento mais comum em ambientes aquáticos envolve o uso de sinais acústicos que usam medições de tempo de voo para localizar um alvo, referenciando-o a um conjunto de sensores. Esta dissertação apresenta um sistema de posicionamento acústico para veículos subaquáticos com base na medição das diferenças de chegada de três sinais acústicos, originários de emissores com posições conhecidas na superfície, sistema esse que possibilita também a transmissão de dados através do envio periódico de um sinal modulado com informação da última posição estimada para o alvo. Na superfície, três emissores estacionários são responsáveis pelo envio periódico de sinais acústicos modulados. O alvo possui um recetor e um emissor, sendo o recetor responsável pela aquisição dos sinais acústicos e o emissor pelo envio de um sinal acústico modulado com a posição. Por fim, um receptor na superfície é responsável por capturar o sinal com a posição codificada. São aqui apresentados os algoritmos de detecção, codificação e descodificação desenvolvidos, assim como o algoritmo de posicionamento hiperbólico usado, implementado com um filtro Kalman para possibilitar a estimação da posição. Além disso, ´e analisado o desenvolvimento de hardware para permitir o envio e a recepção dos sinais acústicos. Para validar o sistema desenvolvido, são apresentados os resultados obtidos em testes de campo e num ambiente de simulação

Cabo e radio frequência em sistemas deteção de incêndio

Novos produtos são sempre aliados a novas tecnologias, mas nem sempre aplicadas no imediato. No que se refere à radio frequência (RF), são inúmeros os obstáculos aplicados à deteção de incêndio sejam eles, o custo, o interface ou somente a falta de informação por parte da engenharia de projeto. Durante os últimos anos a comunicação sem fios esteve também aliada a equipamentos para aplicação dita “doméstica”, com pouca fiabilidade, baixa autonomia, difícil comunicação entre equipamentos e essencialmente não regulada, isto é, sem normalização. Por parte do comité europeu de normalização, no que se refere à introdução desta tecnologia pela norma que regula os equipamentos de deteção de incêndio, EN54, estão reunidas as condições para que os equipamentos certificados pelos diferentes e reconhecidos laboratórios, entre outros, a LPCB, BSI ou VdS possam ser utilizados conferindo assim à engenharia de segurança e ao utilizador a confiança necessária para a sua instalação. Sistemas de deteção de incêndio por cabo usam tecnologias e protocolos de tal forma evoluídos que são “integráveis” com os sistemas que completam a gestão técnica e de emergência de uma infraestrutura

Lisbon public parks: Development of real-world user scenarios

A população mundial está a aumentar. Até 2030, a população mundial poderá atingir 8,6 mil milhões de pessoas. Nos dias que correm, cerca de 53,9% da população mundial reside em cidades. Até 2050 a previsão é que este número aumente para 68,4%. Ao mesmo tempo, prevê-se que a percentagem de pessoas com mais de 60 anos aumente de 12% para 22%, e que em países este número atinja 33%. Diversos estudos referem a importância que parques públicos e espaços verdes têm na contribuição para uma maior qualidade de vida e bem-estar. O principal objetivo desta Tese é compreender que tipo de problemas existem nos parques públicos de Lisboa e perceber como o design pode melhorar a experiência do utilizador nos parques públicos de Lisboa. Esta Tese está dividida em seis capítulos: Introdução, Estado da arte, Metodologia de investigação, Discussão, Cenários reais de utilizador e Conclusão. Os resultados deste trabalho reforçam a importância da utilização de metodologias de Design Thinking e Design participativo na reflexão e/ou reformulação de parques públicos. Além disso, este trabalho destaca a importância de entender o verdadeiro utilizador, visto que soluções não são universais e precisam ser pensadas de acordo com a localização de cada parque. Esta Tese pretende inspirar novas ideias de investigação, através da identificação de lacunas no conhecimento. Questões abertas e desafiantes sobre novas soluções para parques públicos são propostas e identificadas para trabalhos futuros, abrindo espaço para pensar em novas soluções que possam contribuir para futuros parques públicos “inteligentes”.The global population is growing. By 2030, the world population will reach 8.6 billion people. Nowadays, about 53.9% of the world's population resides in cities, and by 2050, the percentage is expected to rise to 68.4%. At the same time, the percentage of people over 60 is expected to rise from 12% to 22%, and 33% residing in developed countries. Studies have shown that public parks and green spaces can contribute to a higher quality of life and well being. The main purpose of this study is to understand the type of problems exist in Lisbon public parks and to speculate how design and technology could improve the user experience at Lisbon public parks. The thesis is divided into six chapters: Introduction, State of the Art, Research Methodology, Discussion, Real-world user scenarios, and Conclusion. The findings of this study underscore the significance of incorporating Design Thinking and participatory Design approaches when conceptualizing or revitalizing public parks. Additionally, this research underscores the necessity of comprehending the specific park user demographic, as solutions cannot be one-size-fits-all and must be tailored to the park's unique context. The thesis aims to stimulate fresh avenues of research by pinpointing knowledge gaps. It presents forward-looking and formidable challenges in the realm of innovative public park solutions for future exploration. This paves the way for contemplating novel approaches that can contribute to the evolution of “smart” public parks in the future

ADDITIVE MANUFACTURING OF COMPONENTS FOR IN-DIE CAVITY USE, SUITABLE TO WITHSTAND ALUMINIUM HIGH PRESSURE DIE CASTING (HPDC) PROCESS CONDITIONS

Thesis (M. Tech. (Engineering: Mechanical)) -- Central University of Technology, Free State, 2013This research examines the suitability of Additive Manufacturing (AM) for manufacturing dies used in aluminium high pressure die casting. The study was guided by the following objectives: • The reviews of applicable literature sources that outline technical and application aspects of AM in plastic injection moulds and the possibilities of applying it to high pressure casting die. • To introduce AM grown die components in die manufacture. Further, to develop a methodology that will allow industry to apply AM technology to die manufacture. • Revolutionise the way die manufacture is done. The potential for AM technologies is to deliver faster die manufacture turnaround time by requiring a drastically reduced amount of high level machining accuracy. It also reduces the number of complex mechanical material removal operations. Fewer critical steps required by suitable AM technology platforms able to grow fully dense metal components on die casting tools able to produce production runs. • Furthermore, promising competitive advantages are anticipated on savings to be attained on the casting processing side. AM technology allows incorporation of features in a die cavity not possible to machine with current machining approaches and technology. One such example is conformal cooling or heating of die cavities. This approach was successfully used in plastic injection mould cavities resulting in savings on both the part quality as well as the reduction on cycle time required to produce it (LaserCUSING®, 2007). AM technology has evolved to a point where as a medium for fast creation of an object, it has surpassed traditional manufacturing processes allowing for rapidly bridging the gap between ideas to part in hand. The suitability of the AM approach in accelerating the die manufacturing process sometime in the near future cannot be dismissed or ignored. The research showed that there is promise for application of the technology in the not too distant future. In the South African context, the current number and affordability of suitable AM platforms is one of the main stumbling blocks in effecting more widespread applied research aimed at introduction of the technology to die manufacture

Lean Management numa linha de produção de pegadeiras na IETA - Indústria de Estofos e Transformação de Automóveis

Orient. na IETA Eng. Joaquim SoaresTese de mestrado integrado. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 201

Banco BiG - international expansion to Italy

This paper aimsat studying if BiG’s international expansion to Italy is the right move for the bank. After,analysis was conducted to identify if the bank has distinct resources or capabilities thats tan doutin the destination market. Its howed that despite strong competition, Italy is averylarge market and the reisreceptivity to the digital areas where BiG excels. Based on the seresults ,it is recommended that the bank follow sthe expansion path, by phasing the introduction of its disruptive products

Impact of Gamification on Subject Engagement and Data Quality in Health-care Surveys on Mobile Applications

Gamification can be described as using video-game mechanics and elements in non-game contexts to improve user engagement by using not only playfulness and fun, but also pride and competi- tiveness. The usage of gamification is not limited to a particular discipline; it is applicable in fields related to education, workplace, business, sport, software and health care. Health-care studies may rely on surveys to collect data from subjects. The traditional methods have been phone interviews or paper surveys. These have the disadvantages of being very time and staff consuming, alongside with the afterwards digitalisation burden. With the ongoing easier and cheaper access to mobile computing and wireless communica- tions, new approaches arise based on this paradigm. The surveys can be delivered inside mobile apps to be filled out by the subjects more conveniently. This alternative overcomes all the previ- ously mentioned method's disadvantages and brings easiness and practicability in filling out the survey. In pain-related surveys specifically, this is even more prominent because the survey filling out moment isn't bound with a medical consultation or a pre-determined phone call. Instead, it's done when the user feels more suitable. This can lead to registers being made temporarily close to the facts, increasing data quality and accuracy. On the other hand, the users are left to participate in the study at their own leisure, and there's no pressure to fill out and finish the survey. Applying gamification features to health-care surveys can increase subject engagement. This will improve the data quality and, therefore, helps establish this mobile-based survey design with more confidence. This could lead to a speeding-up of the studies' preparation phase and to a mitigation of the data handling burden, which can increase the number of studies published and knowledge produced. The "Instituto de Saúde Pública da Universidade do Porto" (ISPUP), is developing a health- care cohort study about chronic pain in adolescents. The data will be collected in a mobile appli- cation, and gamification features will be added to engage users and assure data quality. To measure the impact of the gamification techniques, the mobile application will be made available in a pilot survey to a restricted number of users, without any gamification elements. Then the selected gamification elements will be implemented, and the resulting mobile application will be used to collect data in the ISPUP project to measure chronic pain. The usability metrics for these two moments will be measured and compared. The results to be analysed will be the login behaviour, the time taken to finish each section of a questionnaire and the whole questionnaire, and the subject interaction with the gamification elements

Measuring valley polarization in two-dimensional materials with second-harmonic spectroscopy

A population imbalance at different valleys of an electronic system lowers its effective rotational symmetry. We introduce a technique to measure such imbalance - a valley polarization - that exploits the unique fingerprints of this symmetry reduction in the polarization-dependent second-harmonic generation (SHG). We present the principle and detection scheme in the context of hexagonal two-dimensional crystals, which include graphene-based systems and the family of transition metal dichalcogenides, and provide a direct experimental demonstration using a 2H-MoSe$_{2}$ monolayer at room temperature. We deliberately use the simplest possible setup, where a single pulsed laser beam simultaneously controls the valley imbalance and tracks the SHG process. We further developed a model of the transient population dynamics which analytically describes the valley-induced SHG rotation in very good agreement with the experiment. In addition to providing the first experimental demonstration of the effect, this work establishes a conceptually simple, com-pact and transferable way of measuring instantaneous valley polarization, with direct applicability in the nascent field of valleytronics