1,033 research outputs found

    Effect of soliton interaction on timing jitter in communication systems

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    Timing jitter in soliton communication systems is studied, taking into account both soliton interaction and amplifier noise, Deviations from Gordon-Haus jitter for closely spaced solitons are observed. A new analytical model for the timing jitter is proposed, The model presented considers interaction in a random sequence of solitons and the effect of the amplified spontaneous emission noise added in each amplification stage, We obtain a good agreement between the new analytical model and simulation results for practical communication systems

    Design, modeling, and control of an autonomous legged-wheeled hybrid robotic vehicle with non-rigid joints

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    This paper presents a legged-wheeled hybrid robotic vehicle that uses a combination of rigid and non-rigid joints, allowing it to be more impact-tolerant. The robot has four legs, each one with three degrees of freedom. Each leg has two non-rigid rotational joints with completely passive components for damping and accumulation of kinetic energy, one rigid rotational joint, and a driving wheel. Each leg uses three independent DC motors—one for each joint, as well as a fourth one for driving the wheel. The four legs have the same position configuration, except for the upper hip joint. The vehicle was designed to be modular, low-cost, and its parts to be interchangeable. Beyond this, the vehicle has multiple operation modes, including a low-power mode. Across this article, the design, modeling, and control stages are presented, as well as the communication strategy. A prototype platform was built to serve as a test bed, which is described throughout the article. The mechanical design and applied hardware for each leg have been improved, and these changes are described. The mechanical and hardware structure of the complete robot is also presented, as well as the software and communication approaches. Moreover, a realistic simulation is introduced, along with the obtained results.info:eu-repo/semantics/publishedVersio

    Enhancing motivation and learning in engineering courses: a challenge-based approach to teaching embedded systems

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    This paper addresses an approach to teaching embedded systems programming through a challenge-based competition involving robots. This pedagogical project distinguishes itself by incorporating international students from three international institutions through the Blended Intensive Program (BIP). The research findings indicate that this approach yields excellent results regarding student engagement and learning outcomes. The challenge-based program effectively promotes students’ creative problem-solving abilities by combining theoretical instruction with hands-on experience in a competitive setting.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES (PIDDAC) to CeDRI (UIDB/05757/2020 and UIDP/05757/2020), SusTEC (LA/P/0007/2021) and project LA/P/0063/2020. This work was supported by Blended Intensive Programme ID: 2021- 1-PT01-KA131-HED-000004268-2, Embedded Systems Applications. The authors thank CEFET/RJ, the Institute of Engineering and the Research Centre on Bio-based Economy of Hanze University of Applied Sciences, the ERASMUS program, and the Brazilian research agencies CAPES, CNPq, and FAPERJ.info:eu-repo/semantics/publishedVersio

    Lattice three-gluon vertex in extended kinematics: Planar degeneracy

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    We present novel results for the three-gluon vertex, obtained from an extensive quenched lattice simulation in the Landau gauge. The simulation evaluates the transversely projected vertex, spanned on a special tensorial basis, whose form factors are naturally parametrized in terms of individually Bose-symmetric variables. Quite interestingly, when evaluated in these kinematics, the corresponding form factors depend almost exclusively on a single kinematic variable, formed by the sum of the squares of the three incoming four-momenta, q, r, and p. Thus, all configurations lying on a given plane in the coordinate system (q2,r2,p2) share, to a high degree of accuracy, the same form factors, a property that we denominate planar degeneracy. We have confirmed the validity of this property through an exhaustive study of the set of configurations satisfying the condition q2=r2, within the range [0,5GeV]. This drastic simplification allows for a remarkably compact description of the main bulk of the data, which is particularly suitable for future numerical applications. A semi-perturbative analysis reproduces the lattice findings rather accurately, once the inclusion of a gluon mass has cured all spurious divergences.The authors thank A. C. Aguilar, G. Eichmann and C. D. Roberts for useful discussions. M.N.F. acknowledges financial support from the FAPESP projects 2017/05685-2 and 2020/12795-1, respectively. J.P. is supported by the Spanish MICINN grant PID2020-113334GB-I00 and the regional Prometeo/2019/087 from the Generalitat Va-lenciana; while F.D.S. and J.R.Q. are by the Spanish MICINN grant PID2019-107844GB-C22 and the regional Andalusian P18-FR-5057. All calculations have been performed at the UPO computing center, C3UPO

    Exploring the relative value of end of life QALYs: are the comparators important?

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    In the UK, life extending, end-of-life (EoL) treatments are an exception to standard cost-per-quality-adjusted life year (QALY) thresholds. This implies that greater value is placed on gaining these QALYs, than QALYs gained by the majority of other patient groups treated for anything else in the health system, even for other EoL contexts (such as quality of life (QoL) improvements alone). This paper reports a Person Trade-Off (PTO) study to test whether studies that find societal support for prioritising EoL life extensions can be explained by the severity, in terms of prospective QALYs loss, of the non-terminal comparator scenarios. Eight health scenarios were designed depicting i) QoL improvements for non-EoL temporary (T-QoL) and chronic (C-QoL) health problems and ii) QoL improvements and life extensions (LEs) for EoL health problems. Preferences were elicited from a quota sample of 901 Scottish respondents in 2016 using PTO techniques via Computer Assisted Personal Interview (CAPI). Our results indicate that there is little evidence to suggest that the severity of non-EoL comparator scenarios influence preferences for EoL treatments. Respondents do not appear to have a preference for EoL over non-EoL health gains; instead there is some indication that non-EoL health gains are preferred, particularly when compared to EoL-LE health gains. Comparing between QoL and life extending EoL scenarios, our results suggest QoL improvements are preferred to life extensions. Overall, results challenge current UK EoL policy which gives additional weight to EoL health gains, particularly EoL life extensions in the case of the National Institute for Health and Care Excellence (NICE)

    Landscape Services versus Ecosystem Services in the Mediterranean: a case study example and an invitation to reflect

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    Ecosystem Services, defined as the benefits people obtain from ecosystems, are triggering a paradigmatic shift in how we plan and implement decisions on land-use and land-cover change (Albert et al, 2014; Förster et al, 2015). However this concept is being challenged by critiques of scientific, operational and ideological nature (Norgaard, 2010; Hauck et al, 2013; Jax et al, 2013). Some of these critiques point out to the decoupling of the natural and human dimensions of land-use and land-cover that is inherent to Ecosystem Services (Schröter et al, 2014). We consider this to be especially relevant for mixed land-use mosaics in the Mediterranean region, as this is a geographical context where the cultural and perceived components of land-use and land-cover may be considered to equal, if not to prevail, in value and importance on respect to those of ecological nature (Blondel, 2006). In this paper, we argue that Landscape Services may be, in such contexts, a more adequate coneptual tool to disentangle the complex relationships between humans and nature. Landscape Services are defined as the contributions of landscapes and landscape elements to human wellbeing (Bastian et al, 2014). In contrast with ecosystems, landscapes are inarguably coupled social-ecological systems, which also embrace cultural, and perceptual aspects of landuse and land-cover (Pedroli, Pinto-Correia & Cornish, 2006). Furthermore, Landscapes are defined at scales at which coordinated decision-making for land-use change is most commonly apparent (Blaschke, 2006). Thus, we hereby will discuss if in Mediterranean rural contexts Landscape Services should directly substitute Ecosystem Services, and not just, as the aforementioned literature suggests,complement them

    A robot localization proposal for the RobotAtFactory 4.0: A novel robotics competition within the Industry 4.0 concept

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    Robotic competitions are an excellent way to promote innovative solutions for the current industries’ challenges and entrepreneurial spirit, acquire technical and transversal skills through active teaching, and promote this area to the public. In other words, since robotics is a multidisciplinary field, its competitions address several knowledge topics, especially in the STEM (Science, Technology, Engineering, and Mathematics) category, that are shared among the students and researchers, driving further technology and science. A new competition encompassed in the Portuguese Robotics Open was created according to the Industry 4.0 concept in the production chain. In this competition, RobotAtFactory 4.0, a shop floor, is used to mimic a fully automated industrial logistics warehouse and the challenges it brings. Autonomous Mobile Robots (AMRs) must be used to operate without supervision and perform the tasks that the warehouse requests. There are different types of boxes which dictate their partial and definitive destinations. In this reasoning, AMRs should identify each and transport them to their destinations. This paper describes an approach to the indoor localization system for the competition based on the Extended Kalman Filter (EKF) and ArUco markers. Different innovation methods for the obtained observations were tested and compared in the EKF. A real robot was designed and assembled to act as a test bed for the localization system’s validation. Thus, the approach was validated in the real scenario using a factory floor with the official specifications provided by the competition organization.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES (PIDDAC) to CeDRI (UIDB/ 05757/2020 and UIDP/05757/2020) and SusTEC (LA/P/0007/ 2021). The project that gave rise to these results received the support of a fellowship from “la Caixa” Foundation (ID 100010434). The fellowship code is LCF/BQ/DI20/11780028. The authors also acknowledge the R&D Unit SYSTEC-Base (UIDB/00147/2020), Programmatic (UIDP/00147/2020) and Project Warehouse of the Future (WoF), with reference POCI-01-0247-FEDER-072638, co-funded by FEDER, through COMPETE 2020info:eu-repo/semantics/publishedVersio

    A reflexão como um instrumento de formação no PFCM

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    O Programa de Formação Contínua em Matemática para Professores dos 1.º e 2.º Ciclos do Ensino Básico (PFCM), com o objectivo de melhorar o ensino e as aprendizagens em Matemática e desenvolver atitudes mais positivas face a esta área do saber, pretende responder às necessidades dos professores participantes, partindo de questões relativas à concretização do currículo de Matemática na sala de aula e tendo um carácter continuado ao longo do ano lectivo. O PFCM constitui, assim, um instrumento de apoio e ajuda aos professores participantes na sua prática lectiva (planificação do trabalho, condução da aula, reflexão sobre o que foi feito) de modo a melhorar as suas actuações profissionais e, consequentemente, as aprendizagens matemáticas dos seus alunos. No anterior ano lectivo, o plano de formação desenvolvido pela Escola Superior de Educação de Bragança (ESEB), embora possibilitasse a abordagem de qualquer conteúdo de formação previsto, centrou-se em alguns domínios, nomeadamente, na clarificação ou aprofundamento de temas matemáticos, na discussão dos tipos e natureza das tarefas (exercícios, explorações, problemas, investigações; jogos, projectos), em aspectos da comunicação matemática, na utilização de materiais curriculares, e na construção dos portefólios, valorizando os registos escritos e reflexão. Nesta comunicação pretendemos discutir, com base na observação participante e na análise documental, situações e episódios ocorridos nas salas de aula que fundamentem aspectos do ensino e aprendizagem da Matemática destacados pelo plano de formação da ESEB e evidenciados quer pelos formadores quer pelos professores participantes, dando especial relevância à reflexão (pessoal e partilhada) sobre as experiências profissionais

    Genetic divergence in popcorn genotypes using microsatellites in bulk genomic DNA

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    The genetic diversity of 25 popcorn genotypes was estimated based on DNA bulks from 78 plants of eachvariety. The procedure involved 23 microsatellite loci distributed on 9 maize chromosomes. Clustering analysis according tothe Tocher method and the hierarchical clustering procedures (nearest neighbor, furthest neighbor and Unweighted Pair-Group Method Using Arithmetic Averages - UPGMA) were performed. The cophenetic correlation coefficients indicated theUPGMA method as adequate to distinguish the varieties. The clusters suggested by the molecular analysis generally groupedgenotypes with the same genealogy together. The genetic dissimilarity of the varieties Argentina, Chile, PA-091 and PR-023was higher than of the others. Therefore, higher heterozygosity is expected in progenies from crosses with the other genotypes
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