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Wavelength Division Multiplexing, WDM, is a technology developed for applications in telecommunications with the purpose of combining numerous wavelength signals into one single fibre. The aim of this research is the characterization of WDM systems of ring resonators with planar optical waveguides. The optical responses for different configurations, dimensions, and materials are analysed by doing a parametric study both considering analytical expressions and a Finite Element Tool. The results are from add-drop topologies with one, two and three rings. The main difference between topologies with the same parameters is the number of resonance wavelengths, which is higher due to the increase in the number of ring-shaped waveguides. It is concluded that adjusting the rings’ dimensions, the resonant wavelengths are tuned. Furthermore, the higher the rings’ radius the lower is the free spectral range, that can take values from 40 nm to 90 nm. Then, the number of resonant peaks in a wavelength range may change. Also, 1500–5000 describes the values computed for the quality factor, whereas the full width at half maximum varies within some units of nanometres. For models with different core materials, the higher transmittances decrease with lower core refractive indexes and the resonance width increases. These are new degrees of freedom to tune the response of the device that can definitely work as optical wavelength multiplexer, having losses from 20% to 40% considering the transmitted optical power.

New phenomena have been discovered at the nanoscale that allow us to manipulate light and design devices. Evanescent waves such as Surface Plasmon Polaritons are excited in dielectric–metal interfaces and propagate in the metal. If they reach other interfaces, they may be transmitted by the metal. It is a phenomenon known as Extraordinary Optical Transmission that occurs in nanostructures at the optical range. Depending on the metal it is possible to tune the wavelengths and incident angles where this phenomenon occurs. Gold, silver, aluminium and copper nanolayers are analysed on top of silicon (a-Si and c-Si) considering a sweep between 250 nm and 2500 nm. Considering a novel model based on Fresnel Coefficients in absorbing media, it is possible to improve energy harvesting in the ultraviolet–visible range, mainly due to the propagation of Surface Plasmon Polaritons. Then, the role of Surface Plasmon Polaritons in Air–Metal–Silicon nanostructures is analysed. The inclusion of the metal layer may decrease the reflectance by at least 10%, reaching values higher than 60%. The presented charts allow us to analyse the materials, wavelengths and incident angles where reflectance is decreased. There, the inclusion of metal layers brings benefits to the photodetection, since more energy is available in the absorbing layer. Considering this approach, the detection of specific wavelengths may be improved by introducing metals in the detectors.

Wind energy has become a very interesting option regarding the replacement of fossil-based energy sources by renewable options. Despite its eco-friendly character, some challenges remain across the whole lifecycle of wind turbines. These are mainly related to the use of more sustainable materials and processes in the construction phase, to lifetime extension for the structures currently installed and to waste management at the end-of-life phase, the disassembly or decommissioning phase. Following worldwide concerns about sustainability, the circular economy and decarbonization, several projects have been addressing the themes identified, proposing alternatives that are more suitable and contribute to the body of knowledge in the sector towards enhanced environmental and technical performance. This work presents the state of the art of the European wind energy sector, reflecting on the main drivers, barriers and challenges for circularity, while identifying knowledge gaps and strategic opportunities to develop new potential approaches. A compilation of key projects and main wind energy sites in Europe is shown, as well as a collection of lifecycle extension strategies and reported environmental impacts. Approaches to sustainability are highlighted, such as recyclability, eco-design and eco-efficiency of the turbine blades. Furthermore, the associated potential environmental, economic and societal impacts are put forward to support the implementation of more circular solutions, which can also contribute to reducing EU energy dependency and more integration of renewable sources. The key goal is to give an overview of the main challenges in the sector, namely, in what relates to potential circular solutions and strategies towards a higher level of sustainability.

The main aim of this article is to analyse the Si solar cell’s behaviour when it is exposed to light of different colours. An experimental work, with 100 experimental tests, was carried out, using an RGB LED. In order to obtain better fitting of the characteristic curves’ results, we used a novel discrete model, d1MxP. The obtained results showed that all experimental points of the tests were inside the two triangles that connected the three theoretical primary colours and the three experimental primary colours in the chromaticity diagram. With this diagram, the colour purity could be determined, which presented values between 20% and 60%. The primary colours of the three different LEDs of the light source presented a dominant wavelength that corresponded to the peak wavelengths of the light source spectrum, which showed high purity. However, the obtained results show that mixing colours may not lead to an increase in the cell’s output power. Additionally, an increase in the cell’s temperature was observed, due to the surplus absorbed energy, which was converted into heat, being one of the causes of the cell’s efficiency reduction.

Abstract This research work aims to study photovoltaic systems that generate energy for self-consumption using different traditional technologies, such as silicon, and emerging technologies, like nanowires and quantum. The photovoltaic system without batteries was implemented in a residential property in three different places, in Portugal. According to Portuguese Law, the sale of surplus energy to the grid is possible but the respective value for its selling is not defined. To evaluate the project viability, two different analyses are considered: with and without the sale of surplus energy to the grid. Results show that if there is no sale of excess energy produced to the grid, the project is not economically viable considering the four different technologies. Otherwise, using traditional technologies, the project is economically viable, presenting a payback time lower than 10 years. This shows that the introduction of nanostructures in solar cells is not yet a good solution in the application of solar systems namely with the current law. Furthermore, independently of the used technology, the current Portuguese law seems to difficult the investment return, which should not be the way to encourage the use of renewable sources.

Posterior chamber phakic intraocular lens implantation is a refractive technique for the correction of myopia. This study aimed to identify those factors contributing to variability in postoperative refraction. Methods: This retrospective study evaluated 73 eyes (one eye per patient) implanted with myopic implantable collamer lenses (ICL). Eyes were divided into two groups, the low myopic group (LMG) (ICL > −9.5 DS) and the high myopic group (HMG) (ICL ≤ −9.5 DS), to compare the predictability, efficacy index, and postoperative refraction between groups. The association of postoperative refraction with anatomical, demographic, and optical features was assessed through correlation analysis and investigated using ray-tracing. Results: Postoperative refraction at 3 months for the whole group was close to emmetropia at −0.02 ± 0.37 DS, the LMG tended toward myopia and the HMG, toward hyperopia. The results showed that 65% and 54% of the eyes had postoperative refraction of within ±0.25 DS, respectively, in the LMG and HMG, and in both groups, 100% were within ±1.00 DS. ICL implantation had a higher efficacy index in the HMG (1.13 ± 0.15) than in the LMG (1.04 ± 0.15). Postoperative refraction was positively associated with the vault (R = 0.408) and negatively correlated with ICL power (R = −0.382). Conclusion: The predictability and effectiveness of ICL implantation is high in a wide range of myopias. Considering the expected vault and including accurate vertex measurements would contribute to improving the predictability of the results.

Renewable resources for producing energy for self-consumption are growing, namely solar energy. This work focuses on the comparison of photovoltaic systems for energy production for self-consumption on a property in three different regions of Portugal using traditional and emerging technologies, without batteries’ implementation. According to Portuguese law, there is no stipulated value for selling surplus energy produced by a self consumption unit, to the public grid. In order to analyse the economic viability of the project, two scenarios are studied: the delivery, at zero cost of the surplus energy produced to the grid, and its sale. Furthermore, the same analysis is carried out considering partial shading on the photovoltaic generator. The results show that if there is no surplus production sale to the grid, the project becomes economically unviable for the four PV technologies. Otherwise, for the traditional technologies, the project is economically viable, presenting a payback time lower than 10 years. Using emerging technologies, the project becomes economically unviable. When applying partial shading on the generator, the project becomes, in all the scenarios under study, economically unviable. It can be concluded that introducing nanostructures in solar cells to power an infrastructure is not, for now, the best solution from an economic point of view, considering the current legislation. In addition, the shading makes the projects under study unviable, as it is a factor that cannot be controlled in its entirety.

This article presents the results of a documentary research regarding the current state of Organization and Representation of Musical Information (ORMI) in Portugal. Many authors describe the national scene of ORMI as very shortcoming, due to the usual difficulties: time vs. detail in the description and lack of knowledge of musical language by the technicians Information professionals. A survey of the monographs and articles as of 2011 that make a critical revision to the works of ORMI of several institutions was made, aiming to: 1) perceive their current state and 2) understand its strengths and weaknesses. We identified in these studies the analytic categories to create afterwards a classification structure by disciplinary areas, which shows semantic, structural and quality heterogeneity. The majority of Finding Aids are being produced by musicology projects with structures that respond to their information representation needs.

Com vista a identificar as necessidades, expectativas e grau de satisfação dos usuários com base nos serviços e produtos oferecidos por um sistema de informação, os estudos de usuários se configuram como ferramentas muito úteis na vida destes sistemas. A prática dos estudos de usuários vem sendo implementada em bibliotecas públicas desde a década de 1930. O presente estudo foi elaborado com o intuito de propor um modelo de estudos de usuários para a Biblioteca Nacional de Angola, sendo orientado pela seguinte pergunta de investigação: como conhecer as necessidades e o grau de satisfação dos usuários diante dos produtos e serviços de informação oferecidos pela Biblioteca Nacional de Angola? A metodologia que caracteriza esta investigação possui o enfoque misto, sendo a pesquisa classificada como descritiva e exploratória, que surge, inicialmente através da revisão bibliográfica. Contou com uma população de 200 usuários tendo sido determinada uma amostra de 73 usuários, que responderam ao inquérito de modo a caracterizar o usuário e determinar a sua satisfação. Como resultado, apresenta-se um modelo de estudos de usuários para a Biblioteca Nacional de Angola, elaborado a partir da análise das etapas apresentadas na metodologia UserServiqual elaborada por Garcia e Dorado para o Arquivo Nacional de Angola.

In the last decade, the development and progress of nanotechnology has enabled a better understanding of the light–matter interaction at the nanoscale. Its unique capability to fabricate new structures at atomic scale has already produced novel materials and devices with great potential applications in a wide range of fields. In this context, nanotechnology allows the development of models, such as nanometric optical antennas, with dimensions smaller than the wavelength of the incident electromagnetic wave. In this article, the behavior of optical aperture nanoantennas, a metal sheet with apertures of dimensions smaller than the wavelength, combined with photovoltaic solar panels is studied. This technique emerged as a potential renewable energy solution, by increasing the efficiency of solar cells, while reducing their manufacturing and electricity production costs. The objective of this article is to perform a performance analysis, using COMSOL Multiphysics software, with different materials and designs of nanoantennas and choosing the most suitable one for use on a solar photovoltaic panel.

At the end of the XX century, a new phenomenon was discovered by Ebbesen, the extraordinary optical transmission. He reported that metallic arrays composed of nano holes, also called nanoantennas, can support resonant optical transmissions responsible by the amplification and concentration of electromagnetic radiation. Classical diffraction theories do not predict this extraordinary phenomenon. This article shows the timeline of theories that try to model the interaction between light and metal planes with slits, holes, grooves or apertures. The comparison between theories is done. Furthermore, as the optical response of these nanoantennas is dependent on the complex dielectric function, there is a high probability of successfully using these structures as sensors. This article aimed to verify how the structure parameters (periodicity, hole diameter, nanoantenna thickness and substrate thickness) can influence the optical response in order to tune the spectrum. Using a Finite Element Tool, several 3D simulations aim to conclude about the parameters influence on air–gold–quartz and air–aluminum–quartz structures, being the nanoantenna made with gold and aluminum. Moreover, all the simulations allow us to verify a resonant spectral response and the existence of great values of amplification near the metal surface. This is a clear evidence of a energy exchange due to the generation and propagation of surface plasmon polaritons. Based on the spectra taken from the parameter analysis, a specific structure was chosen to test two different sensors. A temperature sensor and a tissue detection sensor were tested and the simulations are presented. It is concluded that a nanostructure based on a nanoantenna can be used as a sensor for several applications.

Currently, huge opportunities for the inclusion of new optical devices in our lives have been appearing. There are evident and irrefutable examples for nanoantenna applications. They can be used to improve already developed devices or even be used as the device. In both cases, they can be applied in diverse areas, such as medicine, environment, energy, defense, and communications. A square arrayed metallic nanoantenna composed of circular holes is studied by performing simulations using COMSOL Multiphysics. This article aims to study the influence of the nanoantenna’s metal, silver, gold, copper and aluminum, but also the optical response dependence on the nanoantenna’s periodicity, its thickness, the hole diameter, and the number of holes. It is evidenced that the optical response can be tuned using the structure parameters and by choosing an appropriate material. This tuning will allow developers to fulfil the specifications, since it is proven that the response peak can be deliberately shifted, amplified, or attenuated.

The pseudophakic eye lacks the ability to produce a refractive change in response to object proximity. Thus, individual anatomical features such as the pupil size play an important role in achieving functional vision levels. In this work, the range of pupil sizes at varying object distance was measured in pseudophakic participants. Furthermore, the impact of the measured values on eye optical quality was investigated using a computer simulation model. A binocular eye-tracker was used to measure the participants’ pupil sizes at six object distances, ranging from 0.33 m (i.e., vergence of 3.00 D) to 3.00 m (i.e., vergence of 0.33 D), while observing a Maltese cross with a constant angular size of 1 ∘ . In total, 58 pseudophakic participants were enrolled in this study (age mean ± standard deviation: 70.5 ± 11.3 years). The effects of object distance and age on pupil size variation were investigated using linear mixed effects regression models. Age was found to have a small contribution to individual variability. The mean infinite distance pupil size (intercept) was 4.45 ( 95 % CI: 2.74, 6.17) mm and the mean proximal miosis (slope) was − 0.23 ( 95 % CI: −0.53, 0.08) mm/D. The visual acuity (VA) estimation for a distant object ranged from − 0.1 logMAR (smallest pupil) to 0.04 logMAR (largest pupil) and the near VA ( 0.33 m) when mean proximal miosis was considered ranged from 0.28 logMAR (smallest pupil) to 0.42 logMAR (largest pupil). When mean distance pupil was considered, proximal miosis individual variability produced a variation of 0.04 logMAR for the near object and negligible variation for the distant object. These results support the importance of distance pupil size measurement for the prediction of visual performance in pseudophakia, while suggesting that proximal miosis has a negligible impact in VA variability.

In the present paper, a smart planar electrically steerable passive array radiator (ESPAR) antenna was developed and tested at the frequency of 1.33 GHz with the main goal to control the main radiation lobe direction, ensuring precise communication between the antenna that is implemented in an unmanned aerial vehicle (UAV) and the base station. A control system was also developed and integrated into the communication system: an antenna coupled to the control system. The control system consists of an Arduino, a digital potentiometer, and an improved algorithm that allows defining the radiation-lobe direction as a function of the UAV flight needs. The ESPAR antenna was tested in an anechoic chamber with the control system coupled to it so that all previously established requirements were validated.

Relato do 1.º CIHEL, o primeiro Congresso Internacional Habitação no Espaço Lusófono, decorreu em Lisboa, entre os dias 22 e 24 de Setembro, numa excelente parceria entre o Grupo Habitar e o Departamento de Arquitectura e Urbanismo do ISCTE

Neste artigo sustenta-se que a democraticidade é o fundamento da legitimidade da representação. Assim, debater normativamente o problema da representação passa pela elucidação e defesa prévias de um modelo de democracia. Defende-se a democracia como o ideal (processual) da igualdade política (isocracia). Analisam-se e rejeitam-se as objecções às concepções processuais de democracia e expõem-se as debilidades das concepções substantivas rivais. Finalmente, à luz do ideal da isocracia, demonstra-se a superioridade democrática da democracia directa e sustenta-se que os sistemas eleitorais proporcionais são os que melhor se coadunam com a representação fidedigna das preferências dos cidadãos, isto é, a representação democrática.In this article, democracy is conceived as the source of legitimacy of political representation. Thus, in order to debate representation, one must previously clarify and uphold a specific model of democracy. Democracy here is understood as the procedural ideal of political equality (isocracy). Arguments contrary to procedural concepts of democracy are analyzed and rejected, and the weaknesses of rival substantive concepts are explored. Finally, in accordance with isocracy’s ideal, direct democracy is considered democratically superior, and proportional electoral systems are held to be those most compatible with a democratic sort of representation: the accurate representation of citizens’ preferences.

Yeast recycling, which is a common practice in sugarcane ethanol plants, could be expanded if it could be successfully implemented in corn-based ethanol production. However, the process of recycling the yeast remaining after fermentation is hampered by contaminating microorganisms that reduce the fermentation efficiency and compete with the yeast for the fermentable sugars. Currently, antibiotics are used to control microbial contamination. This study proposes chlorine dioxide and electron beam irradiation as alternative control methods for completely inactivating contaminants and minimizing their effect on recycled yeast. For that, wort sterilization using electron radiation (20 kGy) and treatment with a chemical biocide, namely chlorine dioxide (125 mg kg−1), were compared with non-treated wort. Five fermentation cycles were performed using fed-batch systems with 300 g L−1 of fermentable sugars. The results obtained in this study showed the inactivation of contaminants under the effect of electron beam irradiation, which led to an increase in the productivity, yield, and efficiency of fermentation by 0.21 g L−1h−1, 2.6%, and 4.7%, respectively. However, ClO2 did not show promising results in reducing contamination or improving fermentative parameters. Thus, electron beam irradiation of contaminated wort may be a suitable alternative to chemical biocides and would allow the use of recycled yeast in corn-based ethanol plants.