Experimental and modeling studies on reverse electrodialysis for sustainable power generation

A potentially renewable and sustainable source of energy is the chemical energy associated with solvation of salts. Mixing of two aqueous streams with different saline concentrations is spontaneous and releases energy. The global theoretically obtainable power from salinity gradient energy due to World’s rivers discharge into the oceans has been estimated to be within the range of 1.4-2.6 TW. Reverse electrodialysis (RED) is one of the emerging, membrane-based, technologies for harvesting the salinity gradient energy. A common RED stack is composed by alternately-arranged cation- and anion-exchange membranes, stacked between two electrodes. The compartments between the membranes are alternately fed with concentrated (e.g., sea water) and dilute (e.g., river water) saline solutions. Migration of the respective counter-ions through the membranes leads to ionic current between the electrodes, where an appropriate redox pair converts the chemical salinity gradient energy into electrical energy. Given the importance of the need for new sources of energy for power generation, the present study aims at better understanding and solving current challenges, associated with the RED stack design, fluid dynamics, ionic mass transfer and long-term RED stack performance with natural saline solutions as feedwaters. Chronopotentiometry was used to determinate diffusion boundary layer (DBL) thickness from diffusion relaxation data and the flow entrance effects on mass transfer were found to avail a power generation increase in RED stacks. Increasing the linear flow velocity also leads to a decrease of DBL thickness but on the cost of a higher pressure drop. Pressure drop inside RED stacks was successfully simulated by the developed mathematical model, in which contribution of several pressure drops, that until now have not been considered, was included. The effect of each pressure drop on the RED stack performance was identified and rationalized and guidelines for planning and/or optimization of RED stacks were derived. The design of new profiled membranes, with a chevron corrugation structure, was proposed using computational fluid dynamics (CFD) modeling. The performance of the suggested corrugation geometry was compared with the already existing ones, as well as with the use of conductive and non-conductive spacers. According to the estimations, use of chevron structures grants the highest net power density values, at the best compromise between the mass transfer coefficient and the pressure drop values. Finally, long-term experiments with natural waters were performed, during which fouling was experienced. For the first time, 2D fluorescence spectroscopy was used to monitor RED stack performance, with a dedicated focus on following fouling on ion-exchange membrane surfaces. To extract relevant information from fluorescence spectra, parallel factor analysis (PARAFAC) was performed. Moreover, the information obtained was then used to predict net power density, stack electric resistance and pressure drop by multivariate statistical models based on projection to latent structures (PLS) modeling. The use in such models of 2D fluorescence data, containing hidden, but extractable by PARAFAC, information about fouling on membrane surfaces, considerably improved the models fitting to the experimental data.

An analog model for global macro investing

This study proposes a systematic model that is able to fit the Global Macro Investing universe. The Analog Model tests the possibility of capturing the likelihood of an optimal investment allocation based on similarity across different periods in history. Instead of observing Macroeconomic data, the model uses financial markets’ variables to classify unknown short-term regimes. This methodology is particularly relevant considering that asset classes and investment strategies react differently to specific macro environment shifts.

Born global companies: A case study about the internationalization behaviours of Portuguese companies

Portuguese Born Global Companies have been performing an important role in the Portuguese market, mainly due to their innovative ideas and the positive contribution to exportations. This study focuses on the international strategies of four of these companies, comparing them with four international Non-Born Global Companies, in qualitative analysis. It will be possible to see a preference by the Non-Born Global Companies over proximate cultural countries. By following opportunities instead of markets, Portuguese Born Global Companies excel at internationalization growth. The purpose of this study is to help managers of small, innovative companies understand the internationalization strategies in Portugal.

Optimization of export support systems: How to promote exports from Portugal to Germany in the area of information technology and electronics

This work project focuses on developing new approaches which enhance Portuguese exports towards a defined German industry sector within the information technology and electronics fields. Firstly and foremost, information was collected and a set of expert and top managers’ interviews were performed in order to acknowledge the demand of the German market while identifying compatible Portuguese supply capabilities. Among the main findings, Industry 4.0 presents itself as a valuable opportunity in the German market for Portuguese medium sized companies in the embedded systems area of expertise for machinery and equipment companies. In order to achieve the purpose of the work project, an embedded systems platform targeting machinery and equipment companies was suggested as well as it was developed several recommendations on how to implement it. An alternative approach for this platform was also considered within the German market namely the eHealth sector having the purpose of enhancing the current healthcare service provision.

Optimization of export support systems

The present paper is a personal reflection on a work project carried out to promote exports from Portugal to Germany in the IT area, under consideration of the deliverables required by the clients CCILA and Anetie. The project outcome approaches the fact that the majority of the Portuguese market players has disadvantages in size and does rarely coordinate activities among each other, which hinders them to export successfully on a broad scale. To bring together Portuguese delivery potential and German market demand, expert interviews were conducted. Based on the findings, a concept was developed to overcome the domestic collaboration issues in order to strengthen the national exports in the identified sector - embedded systems implementation services for machinery and equipment companies.

Hotel industry: An answer to the emerging trends on the global demand side of tourism

This dissertation studies essentially how Millennials are changing the hotel industry, in the sense that new trends are emerging with this generation and hotels need to respond accordingly, in order to survive within their competitive industry. Emphasis is also given to Asian travellers, as the enlargement of these countries’ middle class populations is predicted, therefore making Asian travellers a valuable target for the hotel industry. To successfully target this segment, hoteliers need also to consider the cultural differences and aspirations that come together with the Asian travellers, and appropriately adapt their offer to them. I will then redirect this study to the city of Lisbon, the Portuguese capital, to analyse if Lisbon’s four and five-star hotel managers are aware of the new market trends, and to understand how they are changing their hotels in order to make them more attractive to Millennials and Asian travellers. Using a sample of 12 hotels (four and five-stars ratings), I have concluded that, although there is a notable undergoing process of adaptation to these guests, there is a long way ahead in order for Lisbon’s hotels to entirely please and retain millennial guests.

Shrinking shrinkage:How and why is fruit shrinkage being caused in Sonaemc's convenience stores? Finding opportunities of improvement envisioning its optimization

This work project regards a challenge presented by a Portuguese organization on the retail sector, SONAEMC, which is a case study of how and why fruit shrinkage occurs in the fruit supply chain within their convenience stores. A qualitative research methodology enabled to infer in which stages throughout the chain shrinkage’s causes occur and, to conclude that internal rules for procedures and processes are not always followed and whose compliance would be enough to reduce fruit shrinkage. The key conclusion is that if fruit stock loss is reduced by as much as 15% the category’s profitability could increase about 8%.

A saúde mental global, a depressão, a ansiedade e os comportamentos de risco nos estudantes do ensino superior : estudo de prevalência e correlação

RESUMO: A saúde mental é influenciada pelos comportamentos tanto como estes são influenciados pela saúde mental. Por isso é importante compreender quer a saúde mental quer os comportamentos adoptados pelo indivíduo em qualquer momento do seu ciclo vital para melhor poder actuar quando e sempre que necessário. Nos estudantes universitários, não sendo uma população de risco, a saúde mental e os comportamentos de risco afectam não só o próprio estudante e quem com ele convive mas também as próprias instituições que o acolhem. O presente estudo teve como objectivos: nos estudantes universitários 1) caracterizar a saúde mental global; 2) caracterizar os níveis de sintomatologia depressiva e ansiosa; 3) identificar os padrões de comportamentos de risco; 4) analisar a relação entre saúde mental global, depressão, ansiedade e comportamentos de risco. Para tal realizou-se um estudo quantitativo, descritivo, correlacional, transversal e exploratório com 1968 estudantes do 1º ciclo da Universidade da Beira Interior e dos Institutos Politécnicos da Guarda, Castelo Branco e Portalegre. Foram utilizados como instrumentos de investigação uma ficha de Caracterização Socio-Demográfica; o Mental Health Inventory-5; o Patient Health Questionnaire-9; Generalized Anxiety Disorder-7; e o Questionário de Comportamentos de Risco em Estudantes Universitários. Os principais resultados mostraram que 18,3% (n=360) apresentavam saúde mental negativa; 17,7% sintomatologia depressiva moderada a severa; 15,6% sintomatologia ansiosa moderada a severa; e que apenas 15% dos que apresentavam saúde mental global negativa recorreu a ajuda profissional. As mulheres, os alunos de 1ª e 4º ano, e os alunos dos cursos de Artes e Letras apresentavam níveis de saúde mental global inferiores. O Consumo de álcool foi superior nos homens, nos estudantes das áreas de Ciências e Ciências da Saúde e nos estudantes deslocados. Os estudantes com mais de 3 unidades curriculares em atraso apresentavam maior sintomatologia depressiva e ansiosa. Os resultados mostraram ainda que quanto mais positiva a saúde mental global maior o consumo de bebidas alcoólicas e menor a sintomatologia depressiva e ansiosa. As variáveis Curso e Sexo influenciam significativamente a saúde mental global, a depressão e a ansiedade. Apesar de a maioria dos estudantes inquiridos não revelar problemas de saúde mental nem apresentar comportamentos de risco, as principais conclusões apontam para a necessidade de programas de educação para a saúde assim como de programas de literacia de saúde mental para as instituições poderem identificar precocemente as situações problemáticas e ajudar os próprios estudantes a reconhecer em si o sofrimento psicológico e a necessidade de procurar apoio profissional.---------------------------------- ABSTRACT: Mental health is influenced by behaviours as much as behaviours are influenced by mental health. Thus, it is important to understand not only the mental health but also the behaviours adopted by an individual at any stage of its vital cycle in order to accurately intervene whenever and always deemed necessary. Regarding college students, despite not being deemed as a population at risk, mental health and risk behaviours affect not only the student itself and whoever interacts with him but also the institutions that host them. The main purposes of this study were regarding college students 1) characterize the overall mental health; 2) characterize the levels of depression and anxiety symptoms; 3) identify the risk behaviours patterns; and 4) analyse the relation between overall mental health, depression, anxiety and risk behaviours. With that scope a quantitative, descriptive, correlated, transversal and exploratory study has been conducted with 1968 students of the 1st cycle of the University of Beira Interior and of the Polytechnic Institutions of Guarda, Castelo Branco and Portalegre. The investigation instruments used were a chart of Socio-Demographic Characterization; the Mental Health Inventory-5; the Patient Health Questionnaire-9; the Generalized Anxiety Disorder-7; and one Questionnaire of Risk Behaviours in College Students. The main results showed that 18.3% (n=360) revealed negative mental health; 17.7% moderated to severe depression symptoms; 15.6% moderated to severe anxiety symptoms; and that only 15% of those revealing negative overall mental health have seek for professional help. Females, students of the 1st and 4th years and students of the Artes and Letras courses revealed inferior levels of overall mental health. Alcohol consumption is higher in males, in the Sciences and Health Sciences’ students and on displaced students. Students with more than 3 curricular units in delay revealed higher depression and anxiety symptoms. The results also showed that the more positive overall mental health the higher alcohol consumption and the lower depression and anxiety symptoms. The Course and Sex variations significantly influence the overall mental health, the depression and the anxiety. Although the majority of the enquired students did not reveal mental health issues or present risk behaviours, the main conclusions indicate the need to implement health education and mental health literacy programmes in order to enable the institutions to prematurely identify problematic situations and help students to recognize the psychological suffering and the need to seek for professional help.

Responsible research and innovation: a global perspective

Based on the paper presented at the Doctorate Conference on Technologogy Assessment in July 2013 at the University Nova Lisboa, Caparica campus

Technical optimization of the synthesis of flavours

The goal of this thesis is the investigation and optimization of the synthesis of potential fragrances. This work is projected as collaboration between the University of Applied Sciences in Merseburg and the company Miltitz Aromatics GmbH in Bitterfeld‐Wolfen (Germany). Flavoured compounds can be synthesized in different ways and by various methods. In this work, methods like the phase transfer catalysis and the Cope‐rearrangement were investigated and applied, for getting a high yield and quantity of the desired substances and without any by‐products or side reactions. This involved the study of syntheses with different process parameters such as temperature, solvent, pressure and reaction time. The main focus was on Cope‐rearrangement, which is a common method in the synthesis of new potential fragrance compounds. The substances synthesized in this work have a hepta‐1,5‐diene‐structure and that is why they can easily undergo this [3,3]‐sigma tropic rearrangement. The lead compound of all research was 2,5‐dimethyl‐2‐vinyl‐4‐hexenenitrile (Neronil). Neronil is synthesized by an alkylation of 2‐methyl‐3‐butenenitrile with prenylchloride under basic conditions in a phase‐transfer system. In this work the yield of isolated Neronil is improved from about 35% to 46% by according to the execution conditions of the reaction. Additionally the amount of side product was decreased. This synthesized hexenenitrile involved not only the aforementioned 1,5‐diene‐structure, but also a cyano group, that makes this structure a suitable base for the synthesis of new potential fragrance compounds. It was observed that Neronil can be transferred into 2,5‐dimethyl‐2‐vinyl‐4‐hexenoic acid by a hydrolysis under basic conditions. After five hours the acid can be obtained with a yield of 96%. The following esterification is realized with isobutanol to produce 2,5‐dimethyl‐2‐vinyl‐4‐hexenoic acid isobutyl ester with quantitative conversion. It was observed that the Neronil and the corresponding ester can be converted into the corresponding Cope‐product, with a conversion of 30 % and 80%. Implementing the Cope‐rearrangement, the acid was heated and an unexpected decarboxylated product is formed. To achieve the best verification of reaction development and structure, scrupulous analyses were done using GC‐MS, 1H‐NMR and 13C‐ NMR.

The born global phenomenon- The Portuguese case

The growing significance of companies that conduct international business at or near their funding has been critically challenging previous incremental models of international expansion. This thesis aims to cross-compare, by means of a multiple-case study, eight Portuguese start-ups among themselves and with the theoretical concept of born global firms versus traditional ones. This work project finds that: (1) active entrepreneurs with global vision from inception are essential for the implementation of international strategies; (2) only formal network plays a key role for successful internationalization and (3) inimitable sources of value creation, niche-focused strategies and unique intangible assets are also crucial.

Responsible research and innovation: a global perspective

Based on the paper presented at the Doctorate Conference on Technologogy Assessment in July 2013 at the University Nova Lisboa, Caparica campus