Roughest hour – approaches to ship hull fouling management

Submerged surfaces at sea are colonized by a high diversity of sessile (i.e. attached) life forms. As the merchant fleet capacity increases, responding to growth in demand for seaborne transport, so does the hull wetted surface area that is prone to colonization by these sessile organisms, i.e. marine biofouling. Such colonization leads to increased ship hull surface roughness, which results in both environmental and economic issues, namely fuel penalties and increased emissions to air. Improved maintenance of the hull would not only reduce these penalties, but also reduce emission of antifoulants and other paint components to the marine environment, as well as risks related to the transport of non-indigenous species on fouled hulls.The work presented in this thesis aimed at improving current approaches to the management of ship hull fouling, which typically rely on a combination of fouling-control coatings and an in-water cleaning scheme. Knowledge on the adhesive strength of fouling to minimize cleaning forces, on the one hand, and evaluation of the hull condition and hull roughness penalties, on the other hand, are therefore central to the aim of this thesis.The outcome of performed work supports a preventive approach to hull maintenance, e.g. gentle and frequent cleanings (hull grooming), or an alternative predictive approach, based on vessel performance and condition monitoring for detecting early forms of fouling. Tools are provided with potential to improve hull maintenance practices. These include minimizing cleaning forces applied during in-water hull cleaning through knowledge on adhesion strength of fouling (Papers I, III and IV), and more-accurate determination of the impact of fouling on vessel performance, namely by accounting for hull form effects (Papers II) or using a novel performance indicator that would be applicable in wider comparisons between vessels (Paper V). Seen as a whole, results indicate that the goal of minimizing the environmental and economic risks involved in hull fouling management can only be achieved through continued collaboration between different industry stakeholders, researchers, technology developers, authorities and policymakers, leading to an optimal path in development

Sistema Radical do sobreiro (Quercus suber L.): uma abordagem estrutural-funcional 3D

The last decades have witnessed the decline and sudden death of the cork oak (Quercus suber L.) in Montado. The complexity of this production system management has lead to a large set of solutions which have been absent by scientific based research findings (such as those related with the cork oak root system) deriving mainly from empirical knowledge application. The present integrated research approach permits a better understanding of the production system vulnerabilities that can result in management modification proposals which will be useful in a near future. To contribute to a more realistic and integrated forest management and planning, a study relying on a morphological evaluation of cork oak root system in a Cambissoil soil, using a 3D digitizing method was performed. Cork oak showed a dimorphic root system with a relative high quantity of sinkers distributed all over the soil profile, one root subsystem at a superficial level until 40 cm depth and another at a deeper level, around 1.20 m depth. Tree biomass allocation was similarly distributed between aerial and root systems. Previously, a study on methodologies for roots excavation - profile washing with water and excavation through high pressure air jet – was carried out. Results showed that for sandy soils the most suitable method is the excavation by high pressure air jet. Both methods showed to be inadequate for clayed soils. Following the evidence that soil compaction could be an important factor for root growth, a study was conducted, in a greenhouse, with cork oak seedlings. Results showed that tap root length and total root biomass (coarse and fine roots) are negatively affected by soil compaction in depth. In regard to the low survival rate of cork oaks regeneration that has been observed in Montado, another complementary study was conducted in a greenhouse where fertilisation, inoculation with mycorrhizal fungi and aminoacids supply were tested. It was concluded that seedlings subjected to fertilisation and inoculation had a more equilibrated growth between shoot and root components. It is expected that the research developed in the present thesis can provide an essential tool for future forest planning and management and for the natural and artificial regeneration processes in cork oak stands, ensuring the maintenance of the typical Montado landscape; Sistema Radical do Sobreiro (Quercus suber L.): Uma Abordagem Estrutural Funcional 3D Resumo: Desde as últimas décadas que se tem vindo a testemunhar o declínio e a morte súbita do sobreiro (Quercus suber L.) no Montado. A complexidade da gestão deste sistema de produção engloba um grande conjunto de soluções que, por terem sido ausentes de validação científica (tal como a relacionada com o sistema radical do sobreiro), tem vindo a ser suportado, principalmente, pela aplicação do conhecimento empírico. A presente abordagem integrada permite uma melhor compreensão das vulnerabilidades deste sistema que pode resultar em propostas de alteração de gestão que serão úteis num futuro próximo. De forma a contribuir para uma gestão e planeamento florestal mais realistas e integrados, foi realizado um estudo acerca da avaliação morfológica do sistema radical do sobreiro num cambissolo, usando o método de digitalização 3D. O sobreiro mostrou um sistema radicular dimórfico com uma elevada quantidade relativa de sinkers distribuídos por todo o perfil do solo. Foi observado um subsistema à superfície, até aos 40 cm de profundidade e outro mais profundo, a cerca de 1.20 m. Observou-se também que a biomassa da árvore foi distribuída de forma similar entre os sistemas aéreo e radical. Anteriormente foi conduzido um estudo sobre as metodologias de escavação de raízes - lavagem de perfil com água e escavação por meio de jato de ar de alta pressão. Os resultados mostraram que para solos arenosos, o método mais adequado é o método por meio de jato de ar de alta pressão e, que ambos os métodos mostraram ser inadequados para os solos argilosos. Após a observação de que a compactação do solo pode ser um fator importante para o crescimento das raízes, um estudo foi realizado em ambiente de estufa com plântulas de sobreiro. Os resultados mostraram que o comprimento da raiz principal e a biomassa total de raízes (raízes grossas e finas) foram negativamente afetados pela compactação do solo em profundidade. No que diz respeito à baixa taxa de sobrevivência da regeneração dos sobreiros, outro estudo complementar foi realizado em ambiente de estufa onde a fertilização, a inoculação com fungos micorrizos e o suplemento de aminoácidos foram testados. Concluiu-se que as plântulas submetidas à fertilização e inoculação tiveram um crescimento mais equilibrado entre as componentes aéreas e radicais. Espera-se que a investigação apresentada nesta tese possa proporcionar uma ferramenta essencial para o planeamento e gestão florestal futuros e, contribuir para o sucesso da regeneração natural e artificial dos povoamentos de sobreiro, garantindo a manutenção da paisagem típica do Montado

Oxidative and Non-Oxidative Metabolomics of Ethanol

Background: It is well known that ethanol can cause significant morbidity and mortality, and much of the related toxic effects can be explained by its metabolic profile. Objective: This work performs a complete review of the metabolism of ethanol focusing on both major and minor metabolites. Method: An exhaustive literature search was carried out using textual and structural queries for ethanol and related known metabolizing enzymes and metabolites. Results: The main pathway of metabolism is catalyzed by cytosolic alcohol dehydrogenase, which exhibits multiple isoenzymes and genetic polymorphisms with clinical and forensic implications. Another two oxidative routes, the highly inducible CYP2E1 system and peroxisomal catalase may acquire relevance under specific circumstances. In addition to oxidative metabolism, ethanol also originates minor metabolites such as ethyl glucuronide, ethyl sulfate, ethyl phosphate, ethyl nitrite, phosphatidylethanol and fatty acid ethyl esters. These metabolites represent alternative biomarkers since they can be detected several hours or days after ethanol exposure. Conclusion: It is expected that knowing the metabolomics of ethanol may provide additional insights to better understand the toxicological effects and the variability of dose response

Ship hull in-water cleaning and its effects on fouling-control coatings

Today, ship hull fouling is managed through fouling-control coatings, complemented with inwater cleaning. During cleaning, coating damage and wear must be avoided, for maximum coating lifetime and reduced antifoulant release. When possible, cleaning should target early stages of fouling, using minimal forces. However, such forces, and their effects on coatings, have not yet been fully quantified. In this one-year study, minimal cleaning forces were determined using a newly-designed immersed waterjet. The results show that bi-monthly/monthly cleaning, with maximum wall shear stress up to 1.3 kPa and jet stagnation pressure 0.17 MPa, did not appear to cause damage or wear on either the biocidal antifouling (AF) or the biocide-free foul-release (FR) coatings. The AF coating required bi-monthly cleanings to keep fouling to incipient slime (time-averaged results), while the FR coating had a similar fouling level even without cleaning. The reported forces may be used in matching cleaning parameters to the adhesion strength of the early stages of fouling

Optimizing rearing and welfare in Senegalese sole (Solea senegalesensis) broodstock: effect of ambient light intensity and handling time on stress response

Broodstock rearing conditions and handling procedures should be optimized in aquaculture species in order to benefit fish welfare and guarantee optimal conditions for spawning. In teleosts, basal cortisol levels display daily rhythms, oscillating along the 24 h of the day. In this sense, handling fish at different moments of the day may lead to different stress responses. The present study aimed at investigating the optimal rearing conditions for Senegalese sole broodstock, considering ambient light intensity and handling time. The optimal light intensity (50, 100 or 200 lx) was investigated by measuring fish cortisol levels and monitoring locomotor activity rhythms under each intensity tested. Results showed a significant increase in cortisol levels of fish exposed to 200 lx, when compared to values obtained under 100 lx, accompanied by changes in locomotor activity rhythms in both tanks under study. These results suggested that 200 lx may be too high as light intensity for this species, whereas 100 lx seems to be more adequate. Also, daily rhythms of stress response were investigated in breeders from different origins (Wild and first generation, G1). Basal cortisol levels and cortisol stress response after an acute stressor (air exposure) were monitored at two distinct moments of the day (Mid-Light and Mid-Dark). Basal levels were higher during the day in the wild group, while G1 fish seemed to have lost the daily fluctuations in basal cortisol plasma levels, as well as their daily rhythms of locomotor activity. Both groups showed lower stress responses during night-time, an indication that this is an adequate period of the day to handle this species. Senegalese sole breeders born in captivity presented more pronounced stress responses when compared to wild fish, reflecting their different life history in terms of stress challenges.FP7/SME/2008/1; UID/Multi/04326/2019; DL 57/2016/CP1361/CT0007; DL 57/2016/CP1361/CT0033info:eu-repo/semantics/publishedVersio

Impact and compensation of carrier synchronization errors in OFDM signals with very large QAM constellations

Publisher Copyright: © 2023 The Authors. IET Communications published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology.Low cost video sensors used for streaming video signals to help firefighters, require high bit rate due to uncompressed images. To increase spectral efficiency given a limited bandwidth, very high order constellations in high signal to noise ratio regimes can be used. However, noise is not the only factor effecting the high order constellations. These constellations are also sensitive to hardware impairments and system non-linearities. Therefore, in this paper, the effect of carrier frequency offset (CFO) on the performance of an orthogonal frequency division multiplexing (OFDM) system with high order quadrature amplitude modulation (QAM) is studied. A closed form expression is derived for the maximum normalized residual CFO that an OFDM system with M-QAM constellation can resist to have an error free symbol detection. Finally, the suitability of common previous CFO estimation techniques such as the cyclic prefix based technique and the Moose technique in these systems are investigate. The results show that the maximum residual CFO that an OFDM system with M-QAM constellation can resist is proportional to the inverse of (Formula presented.). The results also show that very large order QAM constellations such as 4096-QAM are very sensitive to even small residual CFO values and their performance degrades, significantly. However, the bit error rate analysis indicate that the Moose CFO estimation technique can be used in these systems to compensate the CFO effect, accurately.publishersversionpublishe

Unsupervised anomaly detection of retail stores using predictive analysis library on SAP HANa XS advanced

The retail industry is quite exposed to fraudulent situations. Daily, thousands of transactions are processed, which may include some frauds difficult to detect, mainly when the perpetrators are the own employees at the retail stores. Large retailers with several stores across different locations may have considerable difficulty in detecting frauds involving their cashiers since they have to take into account different contexts of operation. To reduce fraud losses, retailers get an overview of the transactions in each store to filter the ones that look suspicious deviating from what would be normal. Data mining algorithms can be useful to detect anomalies, differentiating the normal from the abnormal. This study adopted the k-Means clustering algorithm for anomaly detection on a sample of 90 stores in a large food retail chain, revealing the existence of some outliers in the data. The anomaly detection process was fully implemented in SAP HANA XS Advanced using the Predictive Analysis Library (PAL). In the end, it was possible to identify the stores with abnormal behavior and conclude for the usefulness and ease of use of such a library, despite some lack of documentation to use it.This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020

Do Mito à Realidade

Com a queda do muro de Berlim e o desmoronar do bloco soviético, a expectativa era a de um grande período de paz mundial, ao contrário do expectável surgiu uma época de instabilidade internacional, caracterizada pelo emergir, a nível global, de novos actores e o desenvolvimento de ameaças difusas com alcance e capacidades até à data desconhecidas. O actual contexto das ameaças e de segurança, obriga a que os Estados e as organizações internacionais, sentindo-se ameaçadas, desenvolvam políticas de segurança e defesa cooperativa no sentido de estabelecerem novas alianças e estratégias geopolíticas. O novo ambiente conflitual, motiva a preparação e participação de forças armadas (FFAA) na prevenção e gestão de crises. Esta participção revela-se fulcral atendendo ao número de vezes em que tem sido empregues em teatros operacionais longínquos e imprevisíveis. Com estas acções as FFAA assumem cada vez mais um papel preponderante na defesa da credibilização da política externa dos Estados. Podemos dizer que neste contexto os Estados não podem ficar indiferentes e esta realidade. Portugal, tal como outros Estados tem enviado forças para as mais variadas missões, de forma a demonstrar o seu empenho em cumprir as suas obrigações enquanto membro das principais Organizações Internacionais. Este facto exige que as forças empregues apresentem sempre um elevado grau de prontidão. No âmbito da utilização de forças militares em palcos longínquos e recheados de incerteza é imperativo que essas forças sejam projectáveis e flexíveis. Para que seja cumprido este desiderato é necessário a existência de um vector de transporte estratégico. Neste enquadramento, este trabalho tem como objectivo identificar analisar tipos de necessidades de transporte estratégico para que a capacidade expedicionária portuguesa deixe de ser um mito e passe a ser uma realidade. Abstract: With the belief that the fall of the Berlin Wall and the collapse of the Soviet Bloc would lead to a considerable period of world peace, as opposed to the expected, a time of international insecurity came, characterized by the existence of new worldwide players and diffuse threats with dimensions and capacities hitherto unknown. The current reality is guided by the fact that nations and international organizations feel threatened and are, hereby, compelled to develop joint security policies and defensive measures; establishing new geopolítical alliances and strategies. In light of this new conflicting environment and due to their increasingly consistent use in distant and unpredictable operational theaters, the preparation and participation of the Armed Forces for the prevention and management of crises has proven to be crucial. These military forces are progressively taking a leading role in the defense of the credibility of the States’ foreign policy. Within the above mentioned context, the States cannot remain indifferent to the new realities. Portugal, as other States, has deployed forces in several missions as to demonstrate its ability to meet the obligations required of a member of major International Organizations. These actions have been widely recognized by the international community. As for the use of military forces in distant scenarios, where uncertainty reigns, it is imperative that these be deployable and flexible. In order to support this need, a strategic means of transportation is mandatory. Based on this framework, this paper aims to identify and analyze types of strategic means of transportation so the Portuguese expeditionary capability is no longer considered a myth but a reality

Diferenças na intensidade de alteração química de sedimentos Pliocénicos a norte e sul do Mondego

Procede-se a uma análise comparativa de características mineralógicas e geoquímicas (elementos maiores), usadas na definição de intensidade de altyeração química, de sedimentos pliocénicos colhidos na margem Atlântica a norte e sul do rio Mondego. Ainda que se note alguma influência da granulometria dos sedimentos nas características composicionais, as unidades a norte do Mondego revelam sempre alteração química menos intensa que as unidades a sul do Mondego. Estas diferenças justificam-se por proveniência distinta e não devem ter qualquer significado climático