104 research outputs found
On-light: optical social network
Social networks are a recent phenomenon of communication, with a high prevalence of young users. This concept
serves as a motto for a multidisciplinary project, which aims to create a simple communication network, using
light as the transmission medium. Mixed team, composed by students from secondary and higher education
schools, are partners on the development of an optical transceiver. A LED lamp array and a small photodiode
are the optical transmitter and receiver, respectively. Using several transceivers aligned with each other, this
con guration creates a ring communication network, enabling the exchange of messages between users. Through
this project, some concepts addressed in physics classes from secondary schools (e.g. photoelectric phenomena
and the properties of light) are experimentally veri ed and used to communicate, in a classroom or a laboratory
Módulo expositivo e interactivo sobre fenómenos ópticos
As experiências interactivas são um veículo atractivo de disseminação do conhecimento, em
particular no domínio da óptica e das suas aplicações. Este artigo descreve um módulo expositivo e
interactivo, destinado a explicar os fenómenos físicos relacionados com a luz. O sistema assemelha-se a
uma máquina de jogos, que tem no topo um conjunto de seis experiências e vem equipado com um sistema com informação visual e auditiva. Permite ao utilizador escolher qual a experiência que irá
decorrer, criando um ambiente multimédia motivador para demonstrar efeitos ópticos. Pode ser utilizado
tanto em ambiente de aula, como em eventos científicos ou culturais abertos à comunidade em geral. O resultado final é um módulo didáctico fiável e robusto, que integra diversas experiências e inclui soluçõesde hardware e software numa solução integrada
Bragg grating tuning techniques for interferometry applications
Fiber bragg grating is widely used in optical fiber applications as a filter or a sensor due to its compact size and high sensitivity to physical conditions, such as temperature and strain. The purpose of this chapter is to describe the implementation and characterization of two tuning methods for optical fiber Bragg gratings, varying the temperature or the length of the fiber. Among the methods using mechanical deformation, compression of the fiber by bending a flexible sheet aggregated with the Bragg grating has shown very interesting tuning results, reaching 19.0 nm with minimum reflection bandwidth variation over the entire tuning range. Stretching the fiber has presented several drawbacks, including breaking of the fiber and a lower tuning range of 4.9 nm. Temperature tuning technique presents good linearity between tuning range and temperature variation but at the cost of a low tuning range (0.4 nm) and a permanent high current electrical source.info:eu-repo/semantics/publishedVersio
Spectrum Engineering Towards 5G: Helping to Ensure Efficient and Interference-free Wireless Communications
With the current use of mobile devices across the world, with increasing demands on bandwidth resources, solving the congestion in the radio spectrum is becoming a challenging task to spectrum regulators. Radiocommunication systems must share the resources efficiently using different
multiplexing techniques using space, frequency or time dimension. Sharing and compatibility studies are required to assess the possibilities for radio systems to coexist in the same or in adjacent frequency bands. SEAMCAT (www.seamcat.org) is a software tool based on the Monte-Carlo simulation method, which is developed within the frame of European Conference of Postal and Telecommunication administrations (CEPT). This tool permits statistical modelling of different radio interference scenarios for performing sharing and compatibility studies between radio-communications systems in the same or adjacent frequency. SEAMCAT is used by many regulatory agencies across the world for various spectrum sharing and compatibility studies such as between mobile systems and terrestrial broadcasting networks.IEEE Latvia sectioninfo:eu-repo/semantics/publishedVersio
Experimental assessment of RRM techniques in 5 GHz dense WiFi networks using REMs
“© 2018 IEEE. Personal use of this material is permitted. Permission
from IEEE must be obtained for all other uses, in any current or future
media, including reprinting/republishing this material for advertising or
promotional purposes, creating new collective works, for resale or
redistribution to servers or lists, or reuse of any copyrighted
component of this work in other works.”The increasing acceptance of WiFi has created
unprecedented levels of congestion in the unlicensed frequency
bands, especially in densely populated areas. This results mainly
because of the unmanaged interference and uncoordinated op-
eration between WiFi access points. Radio Environment Maps
(REM) have been suggested as a support for coordination
strategies that optimize the overall WiFi network performance.
In this context, the main objective of this experiment is to assess
the benefit of a coordinated management of radio resources in
dense WiFi networks at 5 GHz band, using REMs for indoor
scenarios. It was shown that REMs can detect the presence of
interfering links on the network or coverage holes, and a suitable
coordination strategy can use this information to reconfigure
Access Points (AP) channel assignment and re-establish the client
connection, at a cost of diminishing the aggregate throughput
of the network. The technique of AP hand-off was tested to
balance the load from one AP to another. Using REMs, the Radio
Resource Management (RRM) strategy could reconfigure the
network to optimize the client distribution among available APs.
Although the aggregate throughput is lower after load balancing,
the RRM could increase the throughput of the overloaded AP.info:eu-repo/semantics/publishedVersio
Desenvolvimento e teste de uma smartbox versátil para o chão de fábrica
O surgimento de várias inovações tecnológicas permitiu a digitalização e a
transformação da indústria, acompanhando o paradigma da Indústria 4.0.
Tecnologias ligadas à robótica, aos sensores inteligentes, ao fabrico assistido por
computador, à Internet das Coisas ou à Inteligência Artificial permitem a interligação
entre os mundos físicos e virtuais. A interoperação entre todos estes domínios do
saber é o princípio para transformar o processo de produção e criar uma fábrica
inteligente.
O foco deste artigo centra-se no desenvolvimento e teste de uma smartBox, capaz
de comunicar eficientemente com os equipamentos no chão de fábrica e integrá-los
em plataformas de IIOT (Industrial Internet of Things). À smartBox estão acopladas
cartas e módulos de sensores e atuadores adequados às especificidades de cada
máquina. esta tem de ser capaz de operar em tempo-real, ter uma boa performance
e escalabilidade e bons canais de comunicação. O hardware da smartBox tem, por
isso, de ser robusto, flexível, escalável, funcional, suportar diferentes tecnologias e
permitir atualizações futuras, características essenciais a uma disseminação do
conceito de Indústria 4.0 no chão de fábrica.
Atualmente, existe no mercado uma diversidade de plataformas de hardware capazes
de suportar o desenvolvimento da smartBox e servir de Gateway com qualquer
equipamento no chão de fábrica. Por sua vez, os controladores lógicos programáveis
e as suas plataformas de programação atuais são cada vez mais versáteis e intuitivos
de programar, facilitando o processo de desenvolvimento, no sentido em que cada
equipamento do chão de fábrica tem a sua especificidade, processo e tecnologia.
Dado que muitas instalações industriais têm alguns anos de existência, por vezes as
linhas de comunicação andam a par com as linhas de potência e é necessário prestar
atenção às questões das interferências e formas de as minimizar. Nesse caso, os
protocolos de comunicação a utilizar devem corresponder aos requisitos necessários
em comunicações industriais, tal como a redundância, tolerância a interferências,
reduzida latência, e minimizar as retransmissões e a perda de pacotes de dados.
Nesse âmbito, apresentamos um caso de estudo em que é analisada a vibração de
um motor elétrico; testamos duas soluções distintas para a smartBox: uma é baseada
num sistema de aquisição de dados da National Instruments, onde o software
LabVIEW é usado para adquirir, processar e armazenar os dados num servidor OPC
(Object Linking and Embedding for Process Control). A outra solução incorpora as
plataformas Arduino e EtherCAT. As características de ambas as propostas são
analisadas e comparadas.info:eu-repo/semantics/publishedVersio
Design-With-IoT and Design-For-Automation: A Proposal for Product Development Oriented for Excellence
This paper presents two methodologies for the design and development of new products called Design-with-
IoT (DwIoT) that aims to integrate IoT technology into products, focusing on a set of guidelines for its
implementation, and the concept of Design-for-Automation (DFA), important in the development of new automation oriented products in an industry 4.0 context.info:eu-repo/semantics/publishedVersio
Distributed sensing network using ultra low-power lora nodes: a case study in intensive almond groves
The digitization of various agricultural processes is a growing reality in Portugal and in the world.
Some of the application areas use sensor networks to monitor several parameters, including monitoring plant
growth, atmospheric conditions or optimizing the irrigation process. However, in the agricultural environment
where energy sources may be scarce, the implementation of an autonomous sensor network must consider the
limitations imposed by the energy consumption of sensor nodes, powered by batteries. Moreover, spatial
distribution models must be tested to optimize the number of sensors and their placement in the field.
This paper presents an ongoing work, being developed in partnership with a company, owner of an extensive
almond grove in the region of Idanha-a-Nova and Fundão, Portugal. The objective is to implement a sensor
network, making use of a LoRa technology and battery-powered nodes, and collect information on various
parameters associated with intensive almond trees groves.
The proposed sensor network is part of an IoT middleware framework that captures multiple data from
different sources. Through smart farming, precision agriculture, real time monitoring and business intelligence
solutions, the expected results are productivity increase and optimization of the use of resources in the almond
cultivation process and a significative reduction of the environmental impact.N/
Bragg Grating Tuning Techniques for Interferometry Applications
Fiber Bragg grating is widely used in optical fiber applications as a filter or a sensor due to its compact size and high sensitivity to physical conditions, such as temperature and strain. The purpose of this chapter is to describe the implementation and characterization of two tuning methods for optical fiber Bragg gratings, varying the temperature or the length of the fiber. Among the methods using mechanical deformation, compression of the fiber by bending a flexible sheet aggregated with the Bragg grating has shown very interesting tuning results, reaching 19.0 nm with minimum reflection bandwidth variation over the entire tuning range. Stretching the fiber has presented several drawbacks, including breaking of the fiber and a lower tuning range of 4.9 nm. Temperature tuning technique presents good linearity between tuning range and temperature variation but at the cost of a low tuning range (0.4 nm) and a permanent high current electrical source
MOVELETUR - Turismo sustentável e mobilidade elétrica em espaços naturais
Programa de Financiamento: Programa EP INTERREG V A España-Portugal (POCTEP).MOVELETUR - Turismo Sustentável e Mobilidade Elétrica em Espaços Naturais.info:eu-repo/semantics/publishedVersio
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