2020
Authors
Agelet, FA; Darau, VD; Camanzo, A; Luis, UG; Orgeira Crespo, P; Navarro Medina, F; Luis, UG; Ulloa, C; Botelho, V; Hallak, Y; Pires, AL; Maia, MM; Pereira, AM; Silva, J; Ribeiro, M; Machado, V; Pimenta, J; Silva, S; California, A; Leconte, B; Jamier, R; Auguste, JL; Roy, P; Robalinho, P; Frazão, O;
Publication
Proceedings of the International Astronautical Congress, IAC
Abstract
CubeSats are becoming an alternative challenge for space exploration. Research in the technology and applicability of these small platforms has received an increasing interest in the last years. They represent an emergent technological market (CAGR growth of 37.91 % in the 2017-2021 period), while a variety of fields like meteorology, climatic research, transportation safety, or navigation is resorting to this technology. As more complex CubeSats missions are defined, a natural increase in the mission power demand occurs. In a scarce-resource environment like the space, this demands the development of new ways of harvesting spacecraft electrical energy. An alternative to traditional energy harvesting systems composed of solar panels and batteries is Wireless Energy Transfer (WET). It originates in the electromagnetic transfer, proven to have two important limitations: high power efficiency decrease at distances bigger than coil size and the need of mobile parts. A new approach is proposed as a solution to these limitations: the possibility of mounting on a 3U CubeSat photo-thermoelectric generator array devices that can convert photon energy to electrical energy via thermal gradient generation. For creating the thermal gradient, a long-range laser source targets cells from each array forming the hybrid photo-thermoelectric plasmonic system (HPTP). Two possible scenarios are presented in terms of mission requirements and analysis: a controlled pulsed large-range laser source located on Earth, in the case of Earth-orbiting missions, or on a hub system, in a deep-space mission. For Earth, Mars and Jupiter, a simulation of the total energy produced by solar panels and the HPTP system is presented to illustrate the potential use of the WiPTherm technology. In each of the scenarios, key measures of effectiveness will be analysed to overcome potential CubeSat and constituent subsystems overheat, by comparison with nominal component and shield temperature profiles in both eclipse and illuminated cases when the HPTP system is not used. Pointing budget accuracy and jitter for targeting the HPTP generator cells and required laser link budget for a planned energy transfer efficiency of up to 10 % of the source power are other challenges covered in the presentation, apart from research topics from a multidisciplinary group covering nanomaterials science, optics, photonics, and CubeSats power systems engineering. Copyright
2020
Authors
Alves, CF; Silva, AL;
Publication
CORPORATE COMMUNICATIONS
Abstract
Purpose Investor relations literature reports that after an era that "the higher the stock price, the better", currently investor relations entered into a new era where "overvaluation is perhaps as bad as undervaluation" (Laskin, 2018a, p. 19). This paper searches for evidence on whether news coverage around abnormal returns indicates that corporate communication effectively seek fair value prices. Design/methodology/approach Using data of the Portuguese market, it investigates if the news coverage and the investor relations' influence on such coverage (namely as a source of the news) are symmetrical before and after extreme abnormal positive or negative returns. This paper uses event study methodology, performs content analysis and applies statistical and econometric analyses. Findings The findings are consistent with the idea that companies communicate differently in face of positive and negative abnormal returns. Particularly, before the event, companies are more frequently cited as a source of the news for positive events. This indicates that companies seek to capitalize the positive impact of the favourable subsequent disclosures. After the occurrence of abnormal returns, companies are more often a source of the news for negative cases, seeking to mitigate their impact. Additionally, after negative events companies are more frequently mentioned in the news with a positive content than they are mentioned before. Social implications The new approach of this study allows the companies' information stakeholders (namely investors and regulators) to become more informed and critical in the analysis of news coverage and its sources. Originality/value As far as the authors of the paper know, this is the first study that addresses the question of eventual asymmetric behaviour of companies' communication in face of positive and negative abnormal returns.
2020
Authors
Sá Correia, L; Correia, ME; Cruz Correia, R;
Publication
PROCEEDINGS OF THE 13TH INTERNATIONAL JOINT CONFERENCE ON BIOMEDICAL ENGINEERING SYSTEMS AND TECHNOLOGIES, VOL 5: HEALTHINF
Abstract
Complex data management on healthcare institutions makes very hard to identify illegitimate accesses which is a serious issue. We propose to develop a system to detect accesses with suspicious behavior for further investigation. We modeled use cases (UC) and sequence diagrams (SD) showing the data flow between users and systems. The algorithms represented by activity diagrams apply rules based on professionals' routines, use data from an audit trail (AT) and classify accesses as suspicious or normal. The algorithms were evaluated between 23rd and 31st July 2019. The results were analyzed using absolute and relative frequencies and dispersion measures. Access classification was in accordance to rules applied. "Check time of activity" UC had 64,78% of suspicious classifications, being 55% of activity period shorter and 9,78% longer than expected, "Check days of activity" presented 2,27% of suspicious access and "EHR read access" 79%, the highest percentage of suspicious accesses. The results show the first picture of HIS accesses. Deeper analysis to evaluate algorithms sensibility and specificity should be done. Lack of more detailed information about professionals' routines and systems. and low quality of systems logs are some limitations. Although we believe this is an important step in this field.
2020
Authors
Massignan, JAD; London, JBA; Miranda, V;
Publication
JOURNAL OF MODERN POWER SYSTEMS AND CLEAN ENERGY
Abstract
This paper develops a novel approach to track power system state evolution based on the maximum correntropy criterion, due to its robustness against non-Gaussian errors. It includes the temporal aspects on the estimation process within a maximum-correntropy-based extended Kalman filter (MCEKF), which is able to deal with both nonlinear supervisory control and data acquisition (SCADA) and phasor measurement unit (PMU) measurement models. By representing the behavior of the state variables with a nonparametric model within the kernel density estimation, it is possible to include abrupt state transitions as part of the process noise with non-Gaussian characteristics. Also, a novel strategy to update the size of Parzen windows in the kernel estimation is proposed to suppress the effects of suspect samples. By properly adjusting the kernel bandwidth, the proposed MCEKF keeps its accuracy during sudden load changes and contingencies, or in the presence of bad data. Simulations with IEEE test systems and the Brazilian interconnected system are carried out. The results show that the method deals with non-Gaussian noises in both the process and measurement, and provides accurate estimates of the system state under normal and abnormal conditions.
2020
Authors
Lemos, AM; Machado, N; Egea Cortines, M; Barros, AI;
Publication
FOOD CHEMISTRY
Abstract
The present study evaluated the ability of Attenuated Total Reflectance - Mid-Infrared (ATR-MIR) spectroscopy combined with Partial Least Squares Discriminant Analysis (PLS-DA) to discriminate the origin and harvest year of 'Tempranillo' grape clones and with Partial Least Squares (PLS) regressions to predict its contents in soluble solids (SS), pH and titratable acidity (TA). Normalized spectra of grape homogenates and normalized plus 1st Derivative spectra of grape skins allowed an overall percentage of correct classifications of 99.6% and 96.7% in validation, according to origin, and 98.3% and 90.0% in validation, according to harvest year, respectively. The normalized spectra of grape homogenates allowed a calibration and validation determination coefficients (R-2) of 0.92 and 0.90 for SS, 0.90 and 0.84 for pH, 0.88 and 0.84 for TA, respectively. The ATR-MIR combined with multivariate analysis showed to be an appropriate tool to assist the clonal selection process of 'Tempranillo'.
2020
Authors
Szmigin, IT; O'Loughlin, DM; McEachern, M; Karantinou, K; Barbosa, B; Lamprinakos, G; Fernandez Moya, ME;
Publication
EUROPEAN JOURNAL OF MARKETING
Abstract
Purpose In the context of European consumers' experiences of austerity, this study aims to advance current resilience theory in marketing through developing persistent resilience from a context of austerity influenced consumption. Design/methodology/approach Following an interpretivist approach, 38 face to face, in-depth interviews were conducted with European consumers from Ireland, UK, Spain, Portugal, Italy and Greece who were affected in some way by the global financial crisis. Findings Building upon limited conceptual and empirical investigations in social geography, the analysis identifies the themes of persistent stressors and temporal orientation as constants, alongside day-to-day coping, relating and pragmatism, consumer adjustment, repertoires of resistance and transformation as key elements of persistent resilience within the consumption context of austerity. Research limitations/implications The study addresses the limited theoretical and empirical focus on persistent resilience and austerity and directly contributes to consumer behaviour and marketing theory in understanding persistent resilience and its implications. Practical implications Changes to behaviours as a result of persistent resilience included reducing and stopping consumption, discount shopping, alternative consumption in the form of growing or making and mindful consumption through wastage reduction and re-use. Social implications The study highlights the significant social impact of austerity while also identifying positive outcomes for social relations among family, friends and the wider community. Originality/value This study develops and extends Golubchikov's (2011) theory of persistent resilience through exploring European consumer responses to austerity, identifying key consumption characteristics relevant for marketing theory and practice.
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