Reconfigurable antenna for mobile devices

O trabalho descrito nesta dissertação de mestrado foca-se em geral na investigação de antenas impressas. São apresentados conceitos básicos, em conjunto com alguns exemplos desenvolvidos. No entanto, o principal foco prende-se com técnicas de miniaturização e reconfigurabilidade de antenas. A miniaturização de antenas é um tema de investigação de longa data, no entanto, novas técnicas e soluções são apresentadas regularmente. Nesta tese, é aplicada uma técnica recente, baseada na introdução de indutores encapsulados no elemento ressonante de uma antena, que permite miniaturizar um monopólio impresso com uma frequência de ressonância de 2.5 GHz. Outro assunto abordado neste trabalho é a reconfigurabilidade de antenas. Algumas das técnicas mais comuns na investigação actual são apresentadas e debatidas. Uma solução com recurso a díodos PIN é usada para estudar esta capacidade. Os conceitos e características deste tipo de componentes são apresentadas sendo feito o desenho e fabrico de um possível monopólio impresso reconfigurável para operação em dupla banda. Por fim, são combinadas as técnicas de miniaturização com inductor encapsulado e reconfigurabilidade através de díodos PIN, por forma a projectar uma antena reconfigurável muito pequena, para operação em duas bandas distintas. Os resultados são discutidos e com base nestes, algumas possíveis otimizações são propostas. The work reported in this dissertation is focused in the printed antenna research. Basic concepts of printed antennas are presented, along with a few examples that were developed. The main focus however, is around miniaturization and reconfigurability of antennas. Antenna miniaturization is a long time research subject, however, new techniques and solutions are presented everyday. In this thesis, a recent technique based on the introduction of chip inductors in the resonating element of a printed antenna is used in order to miniaturize a monopole with a resonating frequency at 2.5 GHz. Another issue approached in this work is antenna reconfigurability. Some common techniques used in antenna reconfiguration are presented and debated. A solution with PIN diodes is used to study this capability. The concepts and characteristics of this type of components are presented and an example of a reconfigurable printed monopole for dual-band operation is designed and fabricated. At last, miniaturization with chip inductor and reconfigurability through PIN diodes are used together to create a very small antenna for dual-band operation. The simulated and measured results are discussed and upon these, some possible optimizations are proposed

Desenho de antenas para sensores passivos em materiais não convencionais

Doutoramento em Engenharia EletrotécnicaMotivado pela larga expansão dos sistemas RFID e com o desenvolvimento do conceito de Internet das Coisas, a evolução no desenho e métodos de produção de antenas em suportes de materiais alternativos tem tido uma exploração intensiva nos últimos anos. Isto permitiu, não só o desenvolvimento de produtos no campo da interação homem-máquina, mas também tornar estes produtos mais pequenos e leves. A procura de novas técnicas e métodos para produzir eletrónica impressa e antenas em materiais alternativos e, portanto, uma porta aberta para o aparecimento de novas tecnologias. Isto aplica-se especialmente no mercado dos sensores, onde o peso, o tamanho, o consumo energético, e a adaptabilidade a diversos ambientes, têm grande relevância. Esta tese foca-se no desenvolvimento de antenas com suporte em materiais não convenvionais, como os já testados papel e têxteis, mas também na exploração de outros, desconhecidos do ponto de vista eléctrico, como a cortiça e polímeros biodegradáveis usados em impressão 3D. Estes materiais são portanto usados como substrato, ou material de suporte, para diversas antenas e, como tal, as propriedades electromagnéticas destes materiais têm de ser determinadas. Assim, e apresentado neste documento uma revisão de métodos de caracterização de materiais, bem como a proposta de um método baseado em linhas de trasmissão impressas, e a respectiva caracterização electromagnética de diversos materiais. Além disso, são propostos desenhos de antenas para diversos cenários e aplicações utilizando os materiais anteriormente mencionados. Com esta tese concluiu-se que a utilização de materiais alternativos e hoje uma realidade e os resultados obtidos são muito encorajodares para o desenvolvimento de um conjunto de sensores para aplicações RFID com uma grande capacidade de integração.The advancement of the design and fabrication of antennas using textiles or paper as substrates has rapidly grown motivated by the boom of RFID systems and the developing concept of the Internet of Things. These advancements have allowed, not only the development of products for manmachine interaction, but also to make these products smaller and lighter. The search for new techniques and methods to produce printed electronics and antennas in alternative materials is therefore an open door for new technologies to emerge. Especially in the sensors market, where weight, size, power consumption and the adaptability to the target application, are of great importance. This thesis focuses on the development of antenna design approaches with alternative materials, such as the already tested paper and textiles, but also others relatively unknown, such as cork and biodegradable polymers used in 3D printing. These materials are applied to act as substrates, or support structures for the antennas. Therefore, their electromagnetic properties need to be determined. Due to that, a review of electromagnetic characterization methods, as well as the proposal of a custom method based on printed transmission lines, is presented in this document. Besides, several antenna designs, for di erent application scenarios, using the previously mentioned materials, are proposed. With this thesis it was proved that it is possible to develop passive sensors in di erent alternative materials for RFID applications and others, which shows great promise in the use of these materials to achieve higher integration in sensing and identi cation applications

Bioenergia: desenvolvimento, pesquisa e inovação

Com 27 trabalhos produzidos por pesquisadores do Instituto de Pesquisa em Bioenergia (Bioen), da Unesp, este livro oferece uma ampla visão sobre as áreas que compõem o segmento. Seu principal objetivo é contribuir para melhorar a compreensão dos vários aspectos da bioenergia, em especial no Brasil, que figura entre os países com maior nível de desenvolvimento tecnológico no setor. Os artigos abordam uma série abrangente de questões relacionadas à bioenergia, como a construção genética das plantas de cana-de-açúcar visando ao aumento de produtividade, a disseminação de sementes para estimular a propagação de espécies com potencial energético, etapas de produção de bioenergia, usos do combustível e seus efeitos nos diversos tipos de motores. Agrupados por assunto, os textos estão distribuídos em cinco partes: Biomassa para bioenergia; Produção de biocombustíveis; Utilização de bioenergia; Biorrefinaria, alcoolquímica e oleoquímica e Sustentabilidade dos biocombustíveis

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42·4% vs 44·2%; absolute difference -1·69 [-9·58 to 6·11] p=0·67; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5-8] vs 6 [5-8] cm H2O; p=0·0011). ICU mortality was higher in MICs than in HICs (30·5% vs 19·9%; p=0·0004; adjusted effect 16·41% [95% CI 9·52-23·52]; p<0·0001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0·80 [95% CI 0·75-0·86]; p<0·0001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status