Topology and Dynamics in Complex Networks: The Role of Edge Reciprocity

A key issue in complex systems regards the relationship between topology and dynamics. In this work, we use a recently introduced network property known as steering coefficient as a means to approach this issue with respect to different directed complex network systems under varying dynamics. Theoretical and real-world networks are considered, and the influences of reciprocity and average degree on the steering coefficient are quantified. A number of interesting results are reported that can assist the design of complex systems exhibiting larger or smaller relationships between topology and dynamics

Modeling and Assessing of Omni-Directional Robots with Three and Four Wheels

Non

Comunicação em Ambientes Online de Aprendizagem: a perceção de estudantes de cursos de pós-graduação

Os ambientes online e as comunidades de aprendizagem, parecem estar a modificar as estruturas institucionalizadas de criação e disseminação de conhecimento, surgindo como um complemento às formas pré-existentes de aprendizagem organizacional. Nestes ambientes e comunidades, a base do processo de construção do conhecimento assenta na interação social. Tomando como referência a nossa experiência de docência, numa instituição portuguesa de ensino superior público a distância, a Universidade Aberta, desenvolvemos um estudo exploratório, através de uma metodologia essencialmente qualitativa, com estudantes de três cursos de estudos pós-graduados com o objetivo de perceber se a organização do design do ambiente de aprendizagem e o modelo pedagógico utilizado produziram experiências educacionais relevantes, sobretudo em aspetos relacionados com as dinâmicas comunicacionais que foram emergindo no seu seio. Concluímos que as dimensões inerentes ao modelo adotado, designadamente as dimensões social e de ensino interagiram entre si e influenciaram-se mutuamente promovendo experiências educacionais relevantes

The LSTS open-source communication and autonomy software: enabling networked vehicle systems to find track, and sample dynamic features of the ocean

Peer Reviewe

Mechanistic insights into the electrochemical reduction of CO2 to CO on Ni(salphen) complexes

LA/P/0056/2020. The NMR spectrometers are part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project No 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC). FCT is acknowledged for PTDCQUI-QIN0252_2021 (PNM). The CARISMA COST action CM1205 is acknowledged. MJC thanks N. A. G. Bandeira for technical assistance. The CATSUS doctoral programme is also acknowledged. Publisher Copyright: © 2023 The Royal Society of Chemistry.Cyclic voltammetry and bulk electrolysis showed that [Ni(ii)(salphen)] [1], [Ni(ii)(tBu-salphen)] [2], and a binuclear Ni(ii) compound combining salphen and tBu-salphen [3] react with CO2 to yield a metal-carbonyl species that is stable under an oxygen free atmosphere. Upon exposure to air, a stoichiometric amount of CO is released (detected by gas chromatography) and protonation regenerates the initial complex. To shed light on the mechanism of CO2 reduction and O2-dependent CO release by [1], UV-vis, EPR and SEC-IR spectroscopy studies complemented with DFT calculations were performed. It is proposed that the mono reduced [Ni(i)(salphen)]−, 2[1]−, formed a CO2 complex, 2[1(CO2)]−, which was then further reduced to 3[1(CO2)]2−. After addition of two protons, the coordinated CO2 was reduced to CO and released, regenerating 1[1]. Alternatively, 2[1(CO2)]− is protonated and then reduced to the same intermediate as before, continuing the same way. In the second cycle, the CO released competed with CO2 and coordinated to 2[1]− much more strongly, thereby deactivating the system. The new 2[1(CO)]− was reduced to 3[1(CO)]2− which was identified by comparison of experimental spectroscopic (UV-vis, EPR, SEC-IR) data with DFT calculated parameters.publishersversionpublishe

Comunicação em ambientes online de aprendizagem : a percepção de estuantes de cursos de pós-graduação

Os ambientes online e as comunidades de aprendizagem, parecem estar a modificar as estruturas institucionalizadas de criação e disseminação de conhecimento, surgindo como um complemento às formas pré-existentes de aprendizagem organizacional. Nestes ambientes e comunidades, a base do processo de construção do conhecimento assenta na interação social. Tomando como referência a nossa experiência de docência, numa instituição portuguesa de ensino superior público a distância, a Universidade Aberta, desenvolvemos um estudo exploratório, através de uma metodologia essencialmente qualitativa, com estudantes de três cursos de estudos pós-graduados com o objetivo de perceber se a organização do design do ambiente de aprendizagem e o modelo pedagógico utilizado produziram experiências educacionais relevantes, sobretudo em aspetos relacionados com as dinâmicas comunicacionais que foram emergindo no seu seio. Concluímos que as dimensões inerentes ao modelo adotado, designadamente as dimensões social e de ensino interagiram entre si e influenciaram-se mutuamente promovendo experiências educacionais relevantes.The online environments and the learning communities are changing the institutionalized structures of creation and dissemination of knowledge, emerging as a complement to pre-existing forms of organizational learning. In these environments and communities, the process of knowledge construction is based on the social interaction.. Referring to our teaching experience in an institution of portuguese public higher education distance learning -Open University-, we developed an exploratory study, through a methodology essentially qualitative, with students from three courses of postgraduate studies with the purpose of understand if the design of the learning environment and the pedagogical model used have produced relevant educational experiences, particularly in aspects related with the creation of communicational dynamics. We conclude that the dimensions associated to the adopted model, particularly the social and teaching dimensions interacted and influenced each other, promoting relevant educational experiences

Association of radio polar cap brightening with bright patches and coronal holes

Radio-bright regions near the solar poles are frequently observed in Nobeyama Radioheliograph (NoRH) maps at 17 GHz, and often in association with coronal holes. However, the origin of these polar brightening has not been established yet. We propose that small magnetic loops are the source of these bright patches, and present modeling results that reproduce the main observational characteristics of the polar brightening within coronal holes at 17 GHz. The simulations were carried out by calculating the radio emission of the small loops, with several temperature and density profiles, within a 2D coronal hole atmospheric model. If located at high latitudes, the size of the simulated bright patches are much smaller than the beam size and they present the instrument beam size when observed. The larger bright patches can be generated by a great number of small magnetic loops unresolved by the NoRH beam. Loop models that reproduce bright patches contain denser and hotter plasma near the upper chromosphere and lower corona. On the other hand, loops with increased plasma density and temperature only in the corona do not contribute to the emission at 17 GHz. This could explain the absence of a one-to-one association between the 17 GHz bright patches and those observed in extreme ultraviolet. Moreover, the emission arising from small magnetic loops located close to the limb may merge with the usual limb brightening profile, increasing its brightness temperature and width.Comment: 8 pages, 6 figures, 1 table. Accepted for publication in The Astrophysical Journa

A pixel-based complexity model to estimate energy consumption in video decoders

The increasing use of HEVC video streams in diverse multimedia applications is driving the need for higher user control and management of energy consumption in battery-powered devices. This paper presents a contribution for the lack of adequate solutions by proposing a pixel-based complexity model that is capable of estimating the energy consumption of an arbitrary software-based HEVC decoder, running on different hardware platforms and devices. In the proposed model, the computational complexity is defined as a linear function of the number of pixels processed by the main decoding functions, using weighting coefficients which represent the average computational effort that each decoding function requires per pixel. The results shows that the cross-correlation of frame-based complexity estimation with energy consumption is greater than 0.86. The energy consumption of video decoding is estimated with the proposed model within an average deviation range of about 6.9%, for different test sequences.info:eu-repo/semantics/publishedVersio

Performance as a classification criterion of tourist origins and destinations

The definition of performance variables, which can be used as indicators of the results obtained/to be obtained, is a fundamental prerequisite in the carrying out of any evaluation process. Portfolio analysis has been used as a tool for the study of market segments, namely of tourist destinations. However, a review of the literature did not identify a single case where the performance variable is adjusted to the nature of the object. In fact, contrary to many other situations, the use of performance variables in absolute terms does not appear to be the most recommendable solution given that the total volume is conditioned by the size of the territory and, above all, by the number of inhabitants. In other words, for a certain level of socio-economic development, larger countries (in terms of size and number of inhabitants) will tend to have higher absolute values. Besides this, the empirical studies reviewed contain little, or no, information about competition, being temporally static. Although in some cases growth rate is used as a variable, thus presupposing the consideration of two magnitudes in two different moments in time, more than one register per object is never considered, meaning that evolutive analyses are not viable. Consequently, a performance proxy was developed which enables a direct comparison between generating countries (origins) and between destinations, regardless of the number of inhabitants. The selection of the performance proxy can depend on the object of study. In any case, it should always permit the evaluation, in general terms, of the results obtained by the destination for the set of origins under analysis and the results generated by the origin for the set of destinations under study. The proposed tool is a component of a model for the identification of priority market segments, and is constituted by a system of orthogonal axes which produces four quadrants that are distinct in terms of intensity (axis OY) and growth (axis OX) of tourist flows. The tool, like the model, can be applied to any type of destination (city, region or country) and to any market segmentation criterion (geographic, demographic, behavioural, psychographic or other). In the study reported here, the instrument is applied to the 15 Member States of the European Union (before its expansion on May 1st 2004), for the period from 1996 to 2001. Eurostat was the sole source of data for the study. The UK and Ireland are the countries classified as ‘Progressing Origins’. With 16.8% of the population, they increased their contribution from 17.7% to 21.9% and are responsible for 38.7% of the growth that occurred between 1996 and 2001. Spain, Greece and Ireland are the countries classified as ‘Progressing Destinations’. With 14.4% of the population, they increased their share of the market from 21.5% to 24.2%, capturing 35.1% of the growth that occurred between 1996 and 2001