1,971 research outputs found

    Avaliação de QoS-QoE no serviço de videochamada SkypeTM

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    Dissertação de mestrado integrado em Engenharia de ComunicaçõesWeb-based videotelephony services currently occupy a prominent place in the wide range of services and generated network traffic. With the growing use of such services comes also an increasing need for the evaluation of user experience. Depending on network conditions, there are relevant QoS parameters (bandwidth, delay, loss ratio, jitter, etc.) that have an impact on the quality of experience of the service. The objective of this thesis is to find out which network parameters affect videocalls quality of experience, which are the threshold values for which the quality of experience levels are affected, in what way is the quality of experience impacted and what is their relation. The quality of experience was evaluated using objective methods for all video and audio samples collected during the experimentation phase. Conclusions were made based on the results which are presented in this dissertation.Os serviços de vídeo-telefonia na rede Internet ocupam actualmente um lugar de relevo no leque de serviços e tráfego de rede gerado. Com a crescente utilização deste tipo de serviços surge também uma maior necessidade de avaliar a qualidade de experiência que o utilizador experiência. Dependendo do tipo de condições que uma rede apresenta, existem parâmetros de QoS relevantes (largura de banda, atraso, perda de pacotes, jitter, etc.) que afectam a qualidade de experiência do uso do serviço. Esta dissertação tem como objectivo descobrir quais os parâmetros de uma rede têm efeito na qualidade de experiência de uma videochamada, quais as condições limite para as quais os níveis de qualidade de experiência são afectados, de que forma é a qualidade de experiência afectada e qual a sua relação. A qualidade de experiência foi avaliada usando métodos objectivos em todas as sequências vídeo e áudio recolhidas durante a fase de testes. Foram retiradas conclusões com base nos resultados obtidos que são apresentadas nesta dissertação

    Correlates of changes in BMI of children from the Azores islands

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    Objective: To model changes in body mass index (BMI), including its stability, and to investigate the association between physical activity, 1-mile run/walk and levels of gross motor coordination and BMI during 5 consecutive years. Design: A longitudinal study of children 6 years of age at baseline followed at annual intervals over 5 years. Subjects: A total of 285 children (143 boys and 142 girls) were enrolled in grade 1 (age 6 years) and followed through grade 5 (age 10 years). Measurements: BMI was recorded and physical activity was assessed by questionnaire, aerobic fitness was evaluated with the 1-mile run/walk and gross motor coordination was measured with the KTK test battery (Korperkoordination test fur Kinder). Multilevel modelling techniques were for the primary analysis. Results: Changes in BMI showed similar curvilinear trends in boys and girls, with ample inter-individual crossing trajectories that is, low tracking. Longitudinal changes in physical activity (PA) and aerobic fitness were not significantly associated with BMI-changes during the 5 years. Children who were more proficient in their motor coordination showed lower values of BMI during the 5 years. Conclusions: BMI trajectories of both boys and girls show low tracking of BMI-values. Considerable inter-individual variation exists both in baseline BMI-values and changes (velocity and acceleration) over time. PA and fitness were not associated with BMI-changes, but gross motor function was negatively associated with BMI-changes. No gender-specific associations were found. If confirmed in other populations these observations could be translated in the promotion of physical activities that improve gross motor function in children aged 6-10 years. This seems to be of major importance for the physical education curriculum of primary school children

    Analysis of a collaborative scheduling model applied in a job shop manufacturing environment

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    Collaborative Manufacturing Scheduling (CMS) is not yet a properly explored decision making practice, although its potential for being currently explored, in the digital era, by combining efforts among a set of entities, either persons or machines, to jointly cooperate for solving some more or less complex scheduling problem, namely occurring in job shop manufacturing environments. In this paper, an interoperable scheduling system integrating a proposed scheduling model, along with varying kinds of solving algorithms, are put forward and analyzed through an industrial case study. The case study was decomposed in three application scenarios, for enabling the evaluation of the proposed scheduling model when envisioning the prioritization of internal–makespan-or external–number of tardy jobs-performance measures, along with a third scenario assigning a same importance or weight to both kinds of performance measures. The results obtained enabled us to realize that the weighted application scenario permitted reaching more balanced, thus a potentially more attractive global solution for the scheduling problem considered through the combination of different kinds of scheduling algorithms for the resolution of each underlying sub problem according to the proposed scheduling model. Besides, the decomposition of a global more complex scheduling problem into simpler sub-problems turns them easier to be solved through the different solving algorithms available, while further enabling to obtain a wider range of alternative schedules to be explored and evaluated. Thus, contributing to enriching the scheduling problem-solving process. A future exploration of the application in other types of manufacturing environments, namely occurring in the context of extended, networked, distributed or virtual production systems, integrating an increased and variable set of collaborating entities or factories, is also suggested.The project is funded by the FCT—Fundação para a Ciência e Tecnologia through the R&D Units Project Scope: UIDB/00319/2020, and EXPL/EME-SIS/1224/2021

    Influência das condições climáticas na fenologia do pessegueiro cv. 'Royal Time'

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    A fenologia estuda a morfologia dos diferentes estados do desenvolvimento das plantas e permite entender e datar o seu desenvolvimento, sendo particularmente importante nas espécies frutícolas, designadamente para o posicionamento das técnicas culturais a realizar ao longo do ciclo anual. Nas prunóideas de clima temperado, nas quais se inclui o pessegueiro, a cerejeira, a ameixeira e a amendoeira, o ciclo anual inicia-se com o desabrochamento dos gomos florais, que se vão desenvolvendo até atingir a plena floração. A chegada de pólen compatível ao estigma da flor pode conduzir à sua fertilização culminando no vingamento dos frutos. Este período de floração é condicionado pelo clima e é utilizado como indicador das alterações climáticas, sendo fundamental para entender como as plantas respondem a estas alterações, preocupação crescente por parte dos produtores devido ao aumento da frequência e intensidade de eventos climáticos extremos. Com o objetivo de estudar a influência das condições meteorológicas no período de floração em pessegueiros da Região da Beira Interior, foi observada a fenologia da cultivar Royal Time, num mesmo pomar, nos ciclos 2015, 2016 e 2018. Paralelamente, foi recolhida informação das variáveis climáticas temperatura e precipitação. Os resultados permitiram observar que, no ciclo 2015, o período de floração, desde o estado C ao estado G foi muito curto, de aproximadamente 17 dias, com a plena floração a ocorrer em 12 de março. Em 2016 o período de floração teve a duração de 36 dias, com a plena floração em 24 de março e em 2018 o período de floração estendeu-se por 35 dias, com a plena floração em 29 de março. Este estudo visa não só evidenciar a irregularidade climática que se observou nos últimos anos, como também contribuir para fornecer aos produtores informação quantificada sobre o efeito da irregularidade dos fatores climáticos na fenologiainfo:eu-repo/semantics/publishedVersio

    Novel insights into biomass delignification with acidic deep eutectic solvents: a mechanistic study of β-O-4 ether bond cleavage and the role of the halide counterion in the catalytic performance

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    The development of innovative technologies for an efficient, yet eco-friendly, biomass delignification is required to achieve higher sustainability than traditional processes. In this context, the use of deep eutectic solvents (DES) for the delignification process could fulfil these requirements and stands today as a promising alternative. This work focus on understanding the fundamental chemistry behind the cleavage of B-O-4 ether bond present in 2-phenoxy-1-phenylethanol (PPE), a lignin model compound, with three acidic DES, including Propionic acid/Urea (PA:U), Lactic acid/Choline Chloride (LA:ChCl) and p-Toluenesulphonic acid/Choline chloride (pTSA:ChCl). The acidic nature of each DES influenced the efficiency of PPE cleavage and determined the extent of further side reactions of cleavage products. Although PA:U (2:1) demonstrated ability to dissolve lignin, it is unable to cleave B-O-4 ether linkage in PPE. On the other hand, LA:ChCl (10:1) allowed PPE cleavage, but an esterification between the PPE and lactic acid as well as oligomerization of lactic acid were detected. Among examined solvents, pTSA:ChCl (1:1) demonstrated the highest performance on the PPE cleavage, although the high acidity of this system lead to condensation of cleavage products at prolonged time. The presence of water decreases the ability of DES for the cleavage, but the extension of undesired side reactions was also reduced. Finally, the analysis of intermediates and products of the reactions allowed the identification of a chlorinated species of PPE that precedes the cleavage reaction. A kinetic study using pTSA:ChCl (1:1) and pTSA:ChBr (1:1) was performed to unveil the role of the halide counterion present in DES on the cleavage of <2=2 ether bond and a new reaction mechanism was herein proposed and supported by density functional theory (DFT) calculations.Altri ñ Celbi, Buckman, Crown Van Gelder, CTP, DS Smith Paper, ESKA, Essity, Holmen, ISPT, Mayr-Melnhof Eerbeek, Mets‰ Fibre, Mid Sweden University, Mondi, Omya, The Navigator Company, Sappi, Essity, Smurfit Kappa, Stora Enso, Eindhoven University of Technology, University of Aveiro, University of Twente, UPM, Valmet Technologies Oy, Voith Paper, VTT Technical Research Centre of Finland Ltd, WEPA and Zellstoff Pols.in publicatio

    Ceriantharia (Cnidaria) of the World: An annotated catalogue and key to species

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    The diversity of Ceriantharia is known from studies formally describing species from the late 18th Century onwards. However, no nomenclators including a list and discussion of all valid species have been produced since a list discussed by Carlgren in 1912. The present nomenclator presents a complete list of adult species of Ceriantharia of the World, including a discussion on each species. It includes the three families (Arachnactidae, Botrucnidiferidae, Cerianthidae) and the currently accepted 54 species based on their adult form. This study serves as a presentation of the “state-of-the-art” list of species of Ceriantharia, and includes a species identification key to support taxonomic identification. Additional in-depth species-byspecies investigations for almost all cerianthid species is still needed, as the information available for most of these species is quite superficial.Fil: Stampar, Sergio. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Reimer, James D.. University of The Ryukyus; JapónFil: Maronna, Maximiliano. Universidade de Sao Paulo; BrasilFil: Lopes, Celine S.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Ceriello, Helen. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Santos, Thais B.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Acuña, Fabian Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Morandini, André C.. Universidade de Sao Paulo; Brasi

    4,4′-Di-tert-butyl-2,2′-bipyridine

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    In the title compound, C18H24N2, the mol­ecular unit adopts a trans conformation around the central C—C bond [N—C—C—N torsion angle of 179.2 (3)°], with the two aromatic rings almost coplanar [dihedral angle of only 0.70 (4)°]. The crystal packing is driven by co-operative contacts involving weak C—H⋯N and C—H⋯π inter­actions, and also the need to fill effectively the available space

    Smart monitoring of constructed wetlands to improve efficiency and water quality

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    The Smart monitoring of constructed wetlands to improve efficiency and water quality (SmarterCW) project aims to monitor biological wastewater treatment processes by gathering continuous data from remote water and environmental sensors. The acquired data can be processed and analysed through data science tools to better understand the complex and coupled phenomena underneath wastewater treatment, as well as, to monitor and optimize the system performance. The results will improve the efficiency and control of nature-based wastewater treatment technologies. The methodology comprises the following tasks and activities: Implementation of a set of electrochemical sensors in the input and output flow streams of pilot-scale constructed wetlands; Acquisition of water quality parameters such as pH, electrical conductivity, temperature, and ionic compounds; Acquisition of environmental parameters, such as temperature and humidity; Application of data analysis tools to design and optimize conceptual models to correlate pollutants removal with operative parameters in green technologies for wastewater treatment. This methodology was applied to a patent-protected pilot-scale modular constructed wetland in which filling media consists of a mixture of solid waste. The system is complemented by a high-level IoT communication layer structure to support remote real-time water and environmental monitoring, system performance, and data dissemination. The project contributes to: Water and Environment through the efficient management and use of water resources and waste reduction, management, treatment, and valorisation; Materials and raw-materials through efficient, secure, and sustainable use of resources; and Environmental Education promoting environmental awareness and best environmental practices through the dissemination of scientific data and results using Information and Communication Technologies (ICT) tools and IoT platforms. The project also contributes to giving response to Societal Challenges, such as Environment protection, sustainable management of natural resources, water, biodiversity, and ecosystems; Enabling the transition to a green society and economy through eco-innovation.info:eu-repo/semantics/submittedVersio
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