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Introducing sustainable gift-giving through AI-powered personalization - from launch to growth: strategies for retention, sustainability, and risk management
Full text linkThis thesis presents Giftify, an AI-driven platform transforming gift-giving with personalized,
ethical, and sustainable recommendations. Giftify leverages AI and low-code technology to
provide thoughtful suggestions aligned with recipients' preferences and values while
emphasizing sustainability. The research outlines the platform's development as a minimum
viable product (MVP), conducted within a master thesis, and covers market analysis, technical
solutions, and monetization strategies. Positioned at the intersection of personalization, e commerce, and sustainability, Giftify aims to enhance the gift-giving experience, creating
meaningful connections and promoting ethical consumer behaviors while building a scalable
and impactful business model
Removal of organic contaminants from wastewater using the electrodialytic process
Full text linkPharmaceuticals and personal care products (PPCPs) are widely used on a daily basis. After their usage they reach the wastewater treatment plants (WWTPs). These compounds have different physico-chemical characteristics, which makes them difficult to completely remove in the WWTPs, througth conventional treatments. Currently, there is no legislation regarding PPCPs thresholds in effluent discharge. But, even at vestigial concentrations, these compounds enclose environmental risks due to, e.g., endocrine disruption potential. There is a need of alternative techniques for their removal in WWTPs. The main goal of this work was to assess the use of electrodialytic (ED) process to remove PPCPs from the effluent to be discharged. A two-compartment ED cell was used testing (i) the effluent position in the cell (anode and cathode compartment); (ii) the use of anion (AEM) and cation exchange membrane (CEM); (iii) the treatment period (6, 12 and 24 hours); (iv) effluent recirculation and current steps; (v) the feasibility of sequential treatments. Phosphorus (P) removal from effluent and energetic costs associated to the process were also evaluated. Five PPCPs were studied – caffeine (CAF), bisphenol A (BPA), 17 β-estradiol (E2), ethinyl estradiol (EE2) and oxybenzone (MBPh). The ED process showed to be effective in the removal when effluent is in the anode compartment. Oxidation is suggested to be the main removal process, which was between 88 and 96%, for all the compounds, in 6 hours. Nevertheless, the presence of intermediates and/or by-products was also observed in some cases. Effluent recirculation should have a retention time in the ED cell big enough to promote removal whereas the current steps (effluent in anode compartment) slightly increased removal efficiencies (higher than 80% for all PPCPs). The sequential set of ED treatment (effluent in anode compartment) showed to be effective during both periods with a removal percentage between 80 and 95% and 73 to 88% in the case of AEM and CEM, respectively. Again, the main removal process is strongly suggested to be oxidation in the anode compartment. However, there was an increase of BOD5 and COD, which might be explained by effluent spiking, these parameters limiting the effluent discharge. From these treatments, the use of AEM, enhanced the P removal from effluent to minimize risk of eutrophication. Energetic costs of the best set-up (6 hours) are approximately 0,8€/m3 of wastewater, a value considered low, attending to the prices of other treatment processes
Plataforma de Simulação de Sistemas Distribuídos de Manufatura
Full text linkDa mesma forma que a sociedade vai progredindo, novas necessidades vão sendo criadas. Os consumidores cada vez têm maior preferência por produtos personalizados e assim sendo, as empresas tiveram que se adaptar e corresponder às necessidades e pedidos dos consumidores, na medida de poderem continuar competitivas e interessantes aos olhos quer dos consumidores, quer dos investidores. Neste ambiente global cada vez mais competitivo em que as empresas estão inseridas, onde a tecnologia se encontra em constante evolução, a otimização de processos e a prevenção de falhas torna-se cada vez mais imperiosa de forma a manter os sistemas de pro-dução atualizados e em bom funcionamento. Tendo em conta o caráter global de certas empre-sas, em que os seus diversos sistemas – produção, controlo, logística – se encontram espalhados pelo globo, é bastante importante que as falhas na cadeia de produção possam ser reduzidas o mais possível.
Para tal, tem-se vindo a recorrer a uma variedade de métodos de previsão e otimização, gestão de risco e identificação de falhas. Tais métodos podem utilizar otimização linear, previ-são estatística ou simulação.
Assim sendo, a simulação de processos de manufatura torna-se interessante na medida em que através dela é possível prever comportamentos e realizar alterações necessárias antes de se implementar o sistema.
No entanto, não existem pacotes de simulação no mercado que sejam capazes de simu-lar todos os processos presentes de uma forma abrangente num sistema de manufatura. Por ou-tro lado, o desenvolvimento de um pacote de simulação deste género tornar-se-ia moroso e dis-pendioso, devido à constante evolução dos sistemas distribuídos de manufatura.
A solução proposta passa então pela criação de uma plataforma de simulação, composta por diversas ferramentas presentes no mercado, que seja capaz de simular o comportamento agregado dos diversos intervenientes que compõem um sistema distribuído de manufatura.
Com a criação de uma ferramenta deste tipo será então possível estudar o comportamento de um sistema de manufatura moderno, podendo prever falhas e otimizar processos
Estudo Numérico da Formação de Inlet Ground Vortices num Motor de Turbina de Gás Próximo do Solo Perante um Escoamento Cruzado
Full text linkUm motor de turbina de gás a operar próximo do solo na presença de um escoamento cruzado
de ar, ao aumentar a sua potência, propicia a formação de um vórtice de entrada a partir do solo
que pode provocar uma perda de eficiência no motor e diversos danos no seu interior, devido às
distorções do escoamento e às perdas de pressão que ocorrem na entrada de ar. Estes vórtices estão
igualmente associados à ocorrência de danos por objetos externos (FOD) nos motores devido à
ingestão de detritos como pós, rochas ou outros objetos de maiores dimensões, sendo a ingestão de
pó responsável pela corrosão das pás dos compressores que reduz o seu tempo de vida útil.
O objetivo desta dissertação consiste no estudo das condições em que ocorre a formação de
vórtices de solo para diferentes razões de velocidade de admissão (푈푖/푈∞) e alturas adimensionais
(ℎ/퐷푖) de um modelo à escala real de um motor na presença de vento cruzado. Recorrendo ao
software comercial ANSYS Fluent 2019 R2, foram analisados os regimes em que ocorre este
fenómeno para diferentes velocidades do ar à entrada do motor e para dois modelos de turbulência
(푘 − 휀 Realizable e 푘 − 휔 SST), mantendo constantes os restantes parâmetros nas primeiras
simulações. Posteriormente, procedeu-se a uma análise análoga para alturas adimensionais distintas
das primeiras.
Neste trabalho, verificou-se o surgimento de uma região de baixa pressão a montante da
entrada de ar do motor para diferentes combinações dos parâmetros 푈푖/푈∞ e ℎ/퐷푖
, permitindo a
identificação do núcleo do vórtice de solo nos casos em que este surgiu e observou-se adicionalmente
o surgimento de vórtices secundários, nomeadamente os trailing vortices.When a gas turbine engine increases its thrust while operating near the ground with a crosswind,
it tends to form an inlet ground vortex that can lead to an engine’s efficiency loss and cause damages
in its interior due to airflow distortions and pressure loss that occurs near the intake. These vortices
are equally associated with the occurrence of foreign objects damage (FOD) in the engines due to
the ingestion of debris such as dust, rocks or bigger objects, being the ingestion of dust responsible
for fan corrosion in compressors which reduces its useful life.
The goal of this dissertation consists in studying in which conditions inlet ground vortices
occur for several velocity ratios (푈푖/푈∞) and dimensionless heights (ℎ/퐷푖) of a real scale model
of a jet engine under crosswind. Using the commercial software ANSYS Fluent 2019 R2, it
was analyzed the regimes in which this phenomenon occurs for distinct velocity values at the
intake for two turbulence models (푘 − 휀 Realizable and 푘 − 휔 SST), while keeping the remaining
parameters unchanged in the first simulations. Subsequently, a similar analysis was done for other
dimensionless heights.
In this work, it was verified the appearance of a low-pressure region upstream of the engines
air intake for different combinations of 푈푖/푈∞ and ℎ/퐷푖
, allowing the identification of the vortex
core in the ground in the cases in which it appeared and the appearance of secondary vortices were
observed, namely trailing vortices
A afirmação do direito de águas
Full text linkThis thesis aims at demonstrating the dogmatic autonomy of Water Law. It also intends to clarify that this branch of law must not be confused with other similar subjects of law. To accomplish this task, the thesis justifies the dogmatic autonomy of Water Law beginning by discussing the emergence of this branch of law both at international and regional levels.
The thesis analyses the emergence of International Water Law, discussing the reasons of its existence, its subject and importance. It also explains the relationship between international watercourses and the need to regulate them, considering that rules related to the use and management of such resources, although created at international level, are meant to be applied at regional and local levels.
The thesis demonstrates that the fact that some waters are international, because they cross different states or serve as border between two or more states, justifies the existence of international water law rules aplicable to the region and to the watercourse they are supposed to regulate.
For this reason, this thesis considers not only international water law in relation with the aplicable regional water law, but also the regional law in relation with the rules aplicable to the water basins and particularly with the concerned water basin states. This relationship between rules leads us to discuss how these three spectrums of rules are conciliated, namely international or universal, regional and water basin rules. To demonstrate how all this works we chose SADC for our case study.
The thesis also studies the States who benefit from rules of international water law, and all other subjects who directly use water from international watercourses, and the conclusion we reach is that who really benefits are the population of such states whose rights of access, use and management are regulated by international, regional and basin rules
As we can imagine, it is not easy to concile so many different rules, applicable to a scarce resource to which many subjects in many states compete for. And the interaction of the different interests, which is done under different spectrum of rules, is what guided our study, in which we analyse how all this process functions. And the main reason of all the discussion is to conclude that there is, in fact, a dogmatic autonomy of water law.
To reach such a conclusion, the thesis begins by studying how international water law is applied at local level. Considering that international watercourses usually have different regimes adopted by the basin states, which difference may cause conflicts, the thesis discusses how water law may contribute to solve possible conflicts. To do this, the thesis studies and compares rules of international water law with rules of water law applicable to SADC states, and figures out the level of interaction between such rules.
Considering that basin states have to obey to local rules, first of all, and after that to international and basin level rules, the thesis studies how the differents interests at stake are managed by riparian states, who act on behalf of their population. SADC appeared to provide an excellent case study to reach this goal. And the thesis discusses all these matters, the rules and principles applicable, and provides solutions where applicable, always considering water as subject of our study.
Accordingly, we discuss the right to water, its nature and how it functions, considering the facts mentioned previously. And, as we conclude, all these legal discussions over water are a clear sign of the dogmatic autonomy of wate