Massive MIMO Full-Duplex Relaying with Optimal Power Allocation for Independent Multipairs

With the help of an in-band full-duplex relay station, it is possible to simultaneously transmit and receive signals from multiple users. The performance of such system can be greatly increased when the relay station is equipped with a large number of antennas on both transmitter and receiver sides. In this paper, we exploit the use of massive arrays to effectively suppress the loopback interference (LI) of a decode-and-forward relay (DF) and evaluate the performance of the end-to-end (e2e) transmission. This paper assumes imperfect channel state information is available at the relay and designs a minimum mean-square error (MMSE) filter to mitigate the interference. Subsequently, we adopt zero-forcing (ZF) filters for both detection and beamforming. The performance of such system is evaluated in terms of bit error rate (BER) at both relay and destinations, and an optimal choice for the transmission power at the relay is shown. We then propose a complexity efficient optimal power allocation (OPA) algorithm that, using the channel statistics, computes the minimum power that satisfies the rate constraints of each pair. The results obtained via simulation show that when both MMSE filtering and OPA method are used, better values for the energy efficiency are attained.Comment: Accepted to the 16th IEEE International Workshop on Signal Processing Advances in Wireless Communications - SPAWC, Stockholm, Sweden 201

CHEMICAL COMPOSITION, ANTIOXIDANT AND ANTIMICROBIAL PROPERTIES OF THREE ESSENTIAL OILS FROM PORTUGUESE FLORA

The present work reports on the evaluation of chemical composition and antioxidant and antimicrobial activities of essential oils of three aromatic herbs, growing wild in the south of Portugal, used in traditional food preparations: Foeniculum vulgare, Mentha spicata and Rosmarinus officinalis. The principal components of essential oils were anethole (41.2%) for F. vulgare, carvone (41.1%) for M. spicata and myrcene (23.7%) for R. officinalis. Essential oils showed antioxidant activity either by DPPH radical scavenging method and system β- carotene/acid linoleic method. Antimicrobial activity of essential oils was observed against pathogenic bacteria and yeasts and food spoilage fungi. F.vulgare essential oil showed bacterial activity against Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella enteritidis, Staphylococcus aureus, Aspergillus niger and Fusarium oxysporum with MICs of 0.25-0.75mg/mL. M. spicata oil was active against E.coli, S.aureus, C.albicans, A. niger and F. oxysporum with MICs ranging between 0.25 and 0.75mg/mL. R. officinalis essential oil showed activity against E.coli and C.albicans with MICs of 0.5-1.0mg/mL. Having in account the important antioxidant and antimicrobial properties observed in present work, we consider that these essential oils might be useful on pharmaceutical and food industry as natural antibiotic and food preservativ

Desperate Co‐wives. The illegality of polygamy in the new Mozambi‐can Family Law

In 2004 Mozambique approved a new Family Law. The new law substituted a law instituted still during the Portuguese colonial rule. The new law is said to be more in line with the Mozambican Constitution, several international legal instruments (particularly those regarding women's rights), while at the same time reflecting Mozambican culture and identity. Yet polygamy, which is a wide spread and generally accepted marriage practice, particularly in the rural areas, remained illegal. The present research aims to analyse the reasons that lead law makers to exclude this particular practice from the law, despite their commitment to respect cultural practices and national identity, and the implications of this decision for people currently involved in polygamous relationships.The principal reason said to be behind the outlawing of the practice is the idea that polygamy is a practice that is humiliating and diminishing to women. The main argument I intend to pursue is that the illegality of polygamy may actually play against those same women whose dignity the law is aiming at protecting; particularly since the law does not eliminate per se the mechanisms of the patriarchal system that may drive women to accept, cope with and/or be trapped in polygamous relationships. In fact the opposite may happen, with formerly legal co-wives ceasing to have social recognition, thus pushing them further down the ladder of vulnerability.To address these questions the research will focus on the relationship between the Mozambican State and its citizens involved in polygamous relationships, particularly in regards to the competing discourses between a global human rights agenda and the protection of culture.Bearing in mind all the unfolding logics, meanings and discourses surrounding polygamy within the debates on gendered culture and rights, one cannot but wonder how people who are affected by the law actually perceive it. With contradictory accounts - exacerbated by contradictory research findings showing that no woman defends polygamy on one hand, and that many of the women in the South of Mozambique have no complaints about polygamy, on the other - it seems safe to conclude that the debate is far from settled. A great deal of road is still to be walked, and new and more diversified voices should be added to the discussion. These include both mainstream and silent voices, but above all the voices of those in name of whom the State, the feminist lobbyists, the Muslim community and even the anthropologist are trying to speak for.SANT355MASV-SAD

As estrategias de aprendizagen nas diferentes abordagens ao estudo: uma investigação com alunos do ensino secundario

[Resumo] Nas duas últimas décadas, numa linha cognitivo-construtivista do ensinoa prendizagem, tem-se valorizado o papel do aluno na aprendizagem. As abordagens ao estudo (Biggs, 1990) e as estratégias de autoregulacão da aprendizagem (Zimmerman, 1990) exemplificam essa perspectiva de análise. Os alunos mais eficientes na aprendizagem adoptam estratégias de mais activas e adaptadas as diferentes exigencias dos contextos e tarefas de aprendizagem. Neste artigo, tomando urna amostra de 558 alunos do Ensino Secundário em Portugal, procura-se conhecer as estratégias de aprendizagem mais usadas e a sua correlacão com as classificaçoes escolares. As correlaçoes encontradas entre as diferentes abordagens ao estudo ou as estratégias de auto-regulac;ao da aprendizagem com as classificaçoes escolares dos alunos, mesmo que estatisticamente significativas, foram reduzida

Vegetable Garden at School

This project began in 2018/2019 due to the interests shown by three classes of the 5th year. Through a brainstorm, we realized that the concern about the lack of green spaces was common to several students of the school. Thus, the vegetable garden would make the school greener and more open to the community. The space for construction was chosen and partnerships were created with the department of environmental management and transport of Odivelas (CMO), and the school parents association. We have privileged collaborative and interdisciplinary work to streamline various activities throughout the school year. The study ofsoil, seeds, autochthonous plants and pollinating insects was done with the help of class teachers and librarian teachers. The days of the native forest and the tree were celebrated with the planting of trees and the holding of a plant fair. At school and throughout the year students disseminated their project through informative posters, school radio and the school's website

The effectiveness of e-word-of-mouth communication about smartphones purchase intention: digital influencer

This study aims to compare the effectiveness of eWOM on Facebook, Instagram and YouTube for smartphone buying decision, provided by digital influencers. For such, a quantitative methodology was adopted using three online questionnaires (one for each social media platform), to be answered by Portuguese adults who use them. This comparison has foundation on the IACM, a model introduced by Erkan and Evans to explore the influence of eWOM on consumer's buying intentions. The results show that, while the eWOM information from digital influencers about smartphones has a global consumer receptivity in the three social media platforms considered, that is not happening in a very assertive way for some items [average not greater than 3 (Likert scale 1-5)], in a significant statistically way. The research also demonstrate that YouTube or Instagram are more effective than Facebook in the IACM variables 'information quality', 'information credibility', 'information usefulness', 'positive buying intention with digital influencer positive information' and 'negative buying intention with digital influencer negative information'.info:eu-repo/semantics/acceptedVersio

Catalyst accessibility and acidity in the hydrocracking of HDPE: a comparative study of H-USY, H-ZSM-5, and MCM-41 modified with Ga and Al

Plastic pollution is a critical environmental issue due to the widespread use of plastic materials and their long degradation time. Hydrocracking (HDC) offers a promising solution to manage plastic waste by converting it into valuable products, namely chemicals or fuels. This work aims to investigates the effect of catalyst accessibility and acidity on the HDC reaction of high density polyethylene (HDPE). Therefore, a variety of materials with significant differences in both textural and acidic properties were tested as catalysts. These include H-USY and H-ZSM.5 zeolites with various Si/Al molar ratios (H-USY: Si/Al = 2.9, 15, 30 and 40; H-ZSM-5: Si/Al = 11.5, 40, 500) and mesostructured MCM-41 materials modified with Ga and Al, also with different Si/metal ratios (Si/Al = 16 and 30; Si/Ga = 63 and 82). Thermogravimetric analysis under hydrogen atmosphere was used as a preliminary screening tool to evaluate the potential of the various catalysts for this application in terms of energy requirements. In addition, batch autoclave reactor experiments (T = 300 °C, PH2 = 20 bar, t = 60 min) were conducted to obtain further information on conversion, product yields and product distribution for the most promising systems. The results show that the catalytic performance in HDPE hydrocracking is determined by a balance between the acidity of the catalyst and its structural accessibility. Accordingly, for catalyst series where the structural and textural properties do not vary with the Si/Al ratio, there is a clear correlation of the HDPE degradation temperature and of the HDPE conversion with the Si/metal ratio (which relates to the acidic properties). In contrast, for catalyst series where the structural and textural properties vary with the Si/Al ratio, no consistent trend is observed and the catalytic performance is determined by a balance between the acidic and textural properties. The product distribution was also found to be influenced by the physical and chemical properties of the catalyst. Catalysts with strong acidity and smaller pores were observed to favor the formation of lighter hydrocarbons. In addition to the textural and acidic properties of the catalyst, the role of coke formation should not be neglected to ensure a comprehensive analysis of the catalytic performance.info:eu-repo/semantics/publishedVersio

Homoclinic and periodic solutions for a class of second order differential equations

In this paper we are concerned with the existence of positive homoclinic solutions of the second order equation …info:eu-repo/semantics/publishedVersio

Fouling by aqueous suspensions of magnetite particles: the effect of pH and ionic strength

Particles adhesion Is one of the fundamental steps in heat exchanger fouling. Surface Interactions are affected by a con siderable number of factors related to the nature of the surfaces Involved. and to the composition and dynamics of the fouling fluid. Although quantitative predictions of U1e rate of adhesion are still not feasible !n practical situations. the evaluation of the potential energy of Interaction between two surfaces "in each vicinity" can be a valuable tool for the qualitative assessment of the fouling tendencies. For that purpose experimental determination of the parameters characterizing the physico-chemical properties of the Interacting surfaces are required. The present paper reports studies on particulate fouling caused by aqueous suspensions of magnetite on copper surfaces. A series of experiments were carried out at different pH values in the range of 7.5 - 9.5. For each pH two distinct types of experiments were performed: In one case the pH was controlled wlth NaOH and In the other the pH controlling medium was Na2co3. Each run lasted 20 days and at the end the thi ckness of the deposits was measured by means of a micrometer coupled to an electrical circuit. The zeta potentials and surface tensions of the solids were measured and used !n the Interpretation of the results. which was carried out In terms of the DLVO Theory

The use of hot wire techniques in fouling tests: a word of awareness

Hot metal wires have been used in fouling tests, mainly when corrosion or chemical reaction is present. Most authors who have reported data obtained with hot wire techniques make no refence about the phenomenon related to the increase In surface area due to the accumulation of fouling layers. Yet this can cause problems of reverse insulation (critical radius), affecting the conclusions taken directly from the readouts. The aim of this paper is to discuss this problem and show through a few selected tases the Importance of this aspect in fouling resistance determinations using hot wire techniques