Implementation of a Passive Acoustic Barrier for Surveillance

Dias, A. R., Santos, N. P., & Lobo, V. (2023). Implementation of a Passive Acoustic Barrier for Surveillance. In OCEANS 2023 - Limerick (pp. 1-6). IEEE Computer Society. https://doi.org/10.1109/OCEANSLimerick52467.2023.10244682With the end of the cold war, the interest in underwater warfare decreased dramatically. However, recent developments have brought underwater warfare back to center stage. Anti-submarine warfare is always one of the major concerns of a navy since it is difficult to detect an enemy submarine in the vast ocean. Conjugating the recent developments in unmanned vehicles and active and passive acoustic surveillance, we can perform better data fusion and increase our knowledge about the events occurring in our waters. The processed data originating from acoustic surveillance can potentially be an essential source of naval intelligence. An acoustic barrier can perform this detection with success. Still, these systems require highly qualified personnel to operate, present a costly infrastructure, and are hard to implement and maintain. Data fusion from multiple sources, and even from low-cost sensors with noisy measures, are a promising solution, especially if resource optimization is a priority. The implementation described in this paper is intended to be proof of concept of a low-cost implementation in shallow waters that can be easily expanded and evolved to different scenarios. The preliminary results obtained confirm that this is a viable solution.authorsversionpublishe

Qual o futuro do hidrogénio na Marinha?

Este trabalho tem como objetivo principal propor uma estratégia para o uso de sistemas de hidrogénio (produção, armazenamento e utilização) na Marinha, procurando assim uma análise de como deverá ser o futuro. Os sistemas de hidrogénio no domínio marítimo ainda se encontram em desenvolvimento, não existindo atualmente soluções e alternativas comerciais. No que respeita à produção, já existem algumas soluções a nível europeu, mas Portugal ainda se encontra numa fase exploratória. Para atingir o objetivo proposto, foi adotado um desenho de pesquisa de estudo de caso, seguindo uma metodologia de raciocínio indutivo, baseada numa estratégia qualitativa reforçada com dados quantitativos. A aquisição de dados foi efetuada através de análise documental e entrevistas com especialistas na Marinha e indústria. Através de uma análise Strengths, Weaknesses, Opportunities and Threats (SWOT), foi possível identificar como principais limitações atuais os custos associados, a falta de maturidade tecnológica e a falta de conhecimento existente na organização. A estratégia proposta a curto, médio e longo prazo deverá incidir na autonomia de produção, no uso de painéis solares e aerogeradores (aquisição de energia no arco diurno e noturno), na utilização para transporte de passageiros, reconversão de meios navais e numa última fase na aquisição de novo equipamento.This work aims to propose a strategy for using hydrogen systems (production, storage and utilization) in the Navy, thus looking for an analysis of the future. The hydrogen systems in the maritime domain are still under development, and there are currently no commercial solutions and alternatives. There are already some solutions at the European level regarding production, but Portugal is still in an exploratory phase. A case study research design was adopted, following an inductive methodology, based on a qualitative strategy reinforced with quantitative data to achieve the proposed objective. The data acquisition was made by document analysis and interviews with experts in the Navy and industry. Through a Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis, the main identified limitations are the associated costs, the lack of technological maturity, and the lack of existing knowledge in the organization. The short, medium and long term proposed strategy should focus on production autonomy, solar panels and wind turbines utilization (daytime and nighttime arc energy acquisition), passenger transport, reconversion of naval platforms, and in the last phase in the acquisition of new equipment.N/

Sistema de visão para aterragem automática de UAV

Dissertação para obtenção do grau de Mestre em Engenharia Electrotécnica Ramo de Automação e Electrónica IndustrialNeste estudo é proposto um sistema de visão para aterrar automaticamente um avião não tripulado (Unmanned Aerial Vehicle - UAV) comercialmente existente chamado AR4 num navio, sendo este sistema composto por uma simples câmara RGB (espectro visível). A aplicação prevê a sua colocação no convés de um navio para estimar a pose do UAV (posição 3D e orientação) durante o processo de aterragem. Ao utilizar um sistema de visão localizado no navio permite a utilização de um UAV com menos poder de processamento, reduzindo assim o seu tamanho e peso. O método proposto utiliza uma abordagem baseada no modelo 3D do objeto em que é necessária a utilização do modelo CAD 3D do UAV. A pose é estimada utilizando uma arquitetura baseada num filtro de partículas. A implementação utilizada é baseada nas estratégias de evolução presentes nos algoritmos genéticos, evitando assim perda de diversidade nas possibilidades criadas. Também é implementada filtragem temporal entre frames - filtro de Kalman unscented - por forma a obter uma melhor estimativa de pose. Os resultados mostram erros angulares e de posição compatíveis com o sistema de aterragem automática. O algoritmo é apropriado para aplicações em tempo real em standard workstations, com unidades de processamento gráfico. O UAV vai operar de um navio patrulha pertencente à Marinha de Guerra Portuguesa, o que implica a capacidade de aterrar num navio de 27 metros de comprimento, 5,9 metros de boca, com uma zona de aterragem pequena e irregular de 5x6 metros localizada na proa do navio. A implementação de um sistema completamente autónomo é muito importante em cenários reais, uma vez que estes navios têm uma guarnição limitada e os pilotos de UAV nem sempre se encontram disponíveis. Além disso, um sistema de visão é mais robusto em ambientes onde pode ocorrer empastelamento ao sinal GPS.Abstract: In this study a vision system for autonomous landing of an existing commercial aerial vehicle (UAV) named AR4 aboard a ship, based on a single standard RGB digital camera is proposed. The envisaged application is of ground-based automatic landing, where the vision system is located on the ship’s deck and is used to estimate the UAV pose (3D position and orientation) during the landing process. Using a vision system located on the ship makes it possible to use an UAV with less processing power, decreasing its size and weight. The proposed method uses a 3D model based pose estimation approach that requires the 3D CAD model of the UAV. Pose is estimated using a particle filtering framework. The implemented particle filter is inspired in the evolution strategies present in the genetic algorithms avoiding sample impoverishment. Temporal filtering is also implemented between frames – unscented Kalman filter – in order to get a better pose estimation. Results show that position and angular errors are compatible with automatic landing system requirements. The algorithm is suitable for real time implementation in standard workstations with graphical processing units. The UAV will operate from the Portuguese Navy fast patrol boats (FPB), which implies the capability of landing in 27 m length, 5.9 m breadth vessels, with a 5x6 m small and irregular landing zone located at the boat´s stern. The implementation of a completely autonomous system is very important in real scenarios,since this ships have only a small crew and UAV pilots are not usually available. Moreover a vision based system is more robust in an environment where GPS jamming can occur

SARS-CoV-2 introductions and early dynamics of the epidemic in Portugal

Genomic surveillance of SARS-CoV-2 in Portugal was rapidly implemented by the National Institute of Health in the early stages of the COVID-19 epidemic, in collaboration with more than 50 laboratories distributed nationwide. Methods By applying recent phylodynamic models that allow integration of individual-based travel history, we reconstructed and characterized the spatio-temporal dynamics of SARSCoV-2 introductions and early dissemination in Portugal. Results We detected at least 277 independent SARS-CoV-2 introductions, mostly from European countries (namely the United Kingdom, Spain, France, Italy, and Switzerland), which were consistent with the countries with the highest connectivity with Portugal. Although most introductions were estimated to have occurred during early March 2020, it is likely that SARS-CoV-2 was silently circulating in Portugal throughout February, before the first cases were confirmed. Conclusions Here we conclude that the earlier implementation of measures could have minimized the number of introductions and subsequent virus expansion in Portugal. This study lays the foundation for genomic epidemiology of SARS-CoV-2 in Portugal, and highlights the need for systematic and geographically-representative genomic surveillance.We gratefully acknowledge to Sara Hill and Nuno Faria (University of Oxford) and Joshua Quick and Nick Loman (University of Birmingham) for kindly providing us with the initial sets of Artic Network primers for NGS; Rafael Mamede (MRamirez team, IMM, Lisbon) for developing and sharing a bioinformatics script for sequence curation (https://github.com/rfm-targa/BioinfUtils); Philippe Lemey (KU Leuven) for providing guidance on the implementation of the phylodynamic models; Joshua L. Cherry (National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health) for providing guidance with the subsampling strategies; and all authors, originating and submitting laboratories who have contributed genome data on GISAID (https://www.gisaid.org/) on which part of this research is based. The opinions expressed in this article are those of the authors and do not reflect the view of the National Institutes of Health, the Department of Health and Human Services, or the United States government. This study is co-funded by Fundação para a Ciência e Tecnologia and Agência de Investigação Clínica e Inovação Biomédica (234_596874175) on behalf of the Research 4 COVID-19 call. Some infrastructural resources used in this study come from the GenomePT project (POCI-01-0145-FEDER-022184), supported by COMPETE 2020 - Operational Programme for Competitiveness and Internationalisation (POCI), Lisboa Portugal Regional Operational Programme (Lisboa2020), Algarve Portugal Regional Operational Programme (CRESC Algarve2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), and by Fundação para a Ciência e a Tecnologia (FCT).info:eu-repo/semantics/publishedVersio

Fixed-Wing Unmanned Aerial Vehicle 3D-Model-Based Tracking for Autonomous Landing

The vast increase in the available computational capability has allowed the application of Particle-Filter (PF)-based approaches for monocular 3D-model-based tracking. These filters depend on the computation of a likelihood function that is usually unavailable and can be approximated using a similarity metric. We can use temporal filtering techniques between filter iterations to achieve better results when dealing with this suboptimal approximation, which is particularly important when dealing with the Unmanned Aerial Vehicle (UAV) model symmetry. The similarity metric evaluation time is another critical concern since we usually want a real-time implementation. We explored, tested, and compared with the same dataset two different types of PFs, (i) an Unscented Bingham Filter (UBiF) and (ii) an Unscented Bingham–Gauss Filter (UBiGaF), using pose optimization in both implementations. Using optimization steps between iterations increases the convergence capability of the filter and decreases the obtained error. A new tree-based similarity metric approach is also explored based on the Distance Transform (DT), allowing a faster evaluation of the possibilities without losing accuracy. The results showed that the obtained pose estimation error is compatible with the automatic landing requirements

Long-term In Situ Eulerian Sea Surface Temperature Records along the Portuguese Coast

Monitoring ocean surface temperature is critical to infer the variability of the upper layers of the ocean, from short temporal scales to climatic change scales. Analysis of the climatological trends and anomalies is fundamental to comprehend the long-term effects of climate change on marine ecosystems and coastal regions. The original data for the dataset presented was collected by the Portuguese Hydrographic Institute (Instituto Hidrográfico) using seven Ondograph and Meteo-oceanography buoys anchored offshore along the Portuguese coast to acquire ocean surface temperatures. The original raw data was pre-processed to provide averages over 3-hour periods and daily averages, and this cleaned data constitutes the provided dataset. The 3-hour temperature averages were obtained mainly between 2011 and 2015, and the daily temperature averages were obtained in intervals that vary with the considered buoy, having an average interval of 14 years per buoy. The data gathered provides a considerable temporal window, enabling the creation of data series and the implementation of data mining algorithms to develop decision support systems. Collecting data in situ makes it possible to validate simulated results obtained using approximation models. This allows for more accurate temperature readings and facilitates testing and correcting created models.</p

Georeferenced dataset of maritime piracy in the Gulf of Guinea from 2010 to 2021

Abstract Piracy has been a global concern and a threat to the safety of people performing maritime trade around the globe. Since ancient times maritime piracy has been a common practice that, unfortunately, has not ended in the current days. A georeferenced dataset providing the position, meteorologic conditions, and a description of the occurrence can provide essential information for analyzing this global phenomenon. The dataset focuses on the Gulf of Guinea (GoG) as an area dominated by corruption and weak supervision capacity by the local authorities. The time interval considered in this paper is between 2010 and 2021. Using this simple dataset, it is possible to analyze attributes such as when the piracy occurred or if the illegal activity involved deaths or kidnapping. The accuracy of the data was guaranteed by cross-referencing data sources, so we have 595 pirate attacks accurately described. This dataset can easily be used for data mining, allowing further analysis of the patterns and trends of pirate attacks in the GoG over time

The National Student Survey: validation in Portuguese medical students

The UK National Student Survey (NSS) is a sound and widely used instrument for assessing students’ academic experiences. We aimed to translate the NSS for Portuguese students and to validate the instrument in a sample of medical undergraduates. The research team translated and adapted the NSS for Portuguese students (NSS-P). The survey was administered on an online platform to 1,256 final-year students at eight Portuguese medical schools. A total of 329 medical students (69.9% female) replied to the NSS-P, a response rate of 26.2%. Confirmatory factor analysis showed that the original six-factor structure had an adequate fit to the data. Adequate internal consistency was observed for all the subscales. Medium to large correlations were found among all the subscale scores and between the subscale scores and the students’ overall satisfaction. Multiple regression showed that the scores on the Teaching, Organization and Management and Personal Development subscales significantly predicted the students’ overall satisfaction. Approximately 64% of the students reported being satisfied with the quality of their courses. Significant differences among the medical schools in their NSS-P scores were found. The NSS-P is a valid and reliable measure for assessing medical students’ perceptions of academic quality