Existence, uniqueness and asymptotic behavior of the solutions to the fully parabolic Keller-Segel system in the plane

In the present article we consider several issues concerning the doubly parabolic Keller-Segel system in the plane, when the initial data belong to critical scaling-invariant Lebesgue spaces. More specifically, we analyze the global existence of integral solutions, their optimal time decay, uniqueness and positivity, together with the uniqueness of self-similar solutions. In particular, we prove that there exist integral solutions of any mass, provided that \e>0 is sufficiently large. With those results at hand, we are then able to study the large time behavior of global solutions and prove that in the absence of the degradation term the solutions behave like self-similar solutions, while in presence of the degradation term global solutions behave like the heat kernel

Impact of Geo-distribution and Mining Pools on Blockchains: A Study of Ethereum

Given the large adoption and economical impact of permissionless blockchains, the complexity of the underlying systems and the adversarial environment in which they operate, it is fundamental to properly study and understand the emergent behavior and properties of these systems. We describe our experience on a detailed, one-month study of the Ethereum network from several geographically dispersed observation points. We leverage multiple geographic vantage points to assess the key pillars of Ethereum, namely geographical dispersion, network efficiency, blockchain efficiency and security, and the impact of mining pools. Among other new findings, we identify previously undocumented forms of selfish behavior and show that the prevalence of powerful mining pools exacerbates the geographical impact on block propagation delays. Furthermore, we provide a set of open measurement and processing tools, as well as the data set of the collected measurements, in order to promote further research on understanding permissionless blockchains.Comment: To appear in 50th IEEE/IFIP International Conference on Dependable Systems and Networks (DSN), 202

Sistema de gestão de energia baseado em AI/ML para comunidades de energia renovável

The need for a reorganization of the energy market, with the goal of reducing the energy consumption from non-renewable sources, led to the creation of Renewable Energy Communities, which allow their members to share their produced and stored energy among themselves. The present work proposes a study of a management system of this community, using AI/ML techniques for the energy consumption forecast. It is predicted that, with the use of these techniques, the management system will be able to decrease the electricity bill of the community, or the reduction of energy consumption from the distri-bution grid.A necessidade de reorganização do mercado de energia, com o objetivo de re-duzir o consumo de energia de fontes não renováveis, levou à criação de Co-munidades de Energia Renovável, que permitem que os seus membros parti-lhem a sua energia produzida e armazenada entre si. O presente trabalho pro-põe um estudo sobre um sistema de gestão desta comunidade, usando técnicas de AI/ML para a previsão do consumo de eletricidade. Prevê-se que, com a uti-lização destas técnicas, o sistema de gestão conseguirá diminuir o preço da fatura de eletricidade da comunidade, ou a redução do consumo de energia pro-veniente da rede de distribuição.Mestrado em Engenharia Informátic

Effect of low pressure and medium pressure uv radiation on Atlantic salmon pathogens´ inactivation

devido à redução de novas concessões, ao aumento de casos de doenças e limitações na eficácia de fármacos. Certas doenças são tratadas e/ou prevenidas por meios como a vacinação, uso de antibióticos e peixes de limpeza, mas existe também uma estratégia diferente e complementar que passa pela desinfeção da água via ozono e/ou radiação ultravioleta (UV). Porém existe pouca informação relativamente às doses de UV necessárias para inativar vírus e bactérias que afetam a produção de salmão. Por esse motivo, este estudo teve como objetivos averiguar o impacto de UV de baixa pressão (“low pressure”, LP) e UV de média pressão (“médium pressure”, MP) nos microrganismos “infectious pancreatic necrosis virus” (IPNV), Moritella viscosa e Yersinia ruckeri. Foi determinada a dose de UV necessária para atingir 99,9 % (3 log) de inativação de cada microrganismo por LP e MP, foram encontradas as diferenças entre inativação por LP e MP e foram comparadas as reações a UV entre vírus e bactérias. Cada microrganismo foi colocado numa solução de água salgada artificial. A concentração viral/bacteriana foi quantificada, processo após o qual uma alíquota foi exposta a uma dose de UV (entre 5 doses previamente definidas) emitida por uma lâmpada LP ou MP contida dentro de um aparelho de feixe colimado (“Collimated beam apparatus”, CBA). Após exposição à luz UV, a concentração viral/bacteriana foi de novo quantificada. Os resultados indicaram que o IPNV, a M. viscosa e a Y. ruckeri sofreram uma inativação de 99,9 % por LP UV com as seguintes respetivas doses de UV: 200, 15, 10 mJ/cm2. Os mesmos patogénicos foram inativados de igual forma por MP UV pelas respetivas doses de UV: 56,4, 4,6 e 11,3 mJ/cm2. As bactérias estudadas demonstraram menos resistência do que o vírus face à radiação de LP e MP UV. Isto deve-se ao facto de terem diferentes estruturas externas, tamanhos, genomas e mecanismos de reativação. MP UV atingiu inativação do IPNV e da M. viscosa com doses de UV mais baixas do que as emitidas por LP UV e destacou-se pela capacidade de atingir certas proteínas e enzimas capazes de reativar o vírus e bactérias estudadas.years due to the reduction of new licenses, diverse pathogen outbreaks and treatment limitations. Some diseases have been treated with vaccines, antibiotics and cleaner fish but a complementary approach involves water treatment by ozonation and/or ultra-violet (UV) radiation. However, few studies have determined the UV doses necessary to inactivate Atlantic salmon pathogens. This work aimed to study the effect of low pressure (LP) UV radiation and medium pressure (MP) UV on infectious pancreatic necrosis virus (IPNV), Moritella viscosa and Yersinia ruckeri by (i) determining the UV dose necessary to achieve a 99.9% inactivation (3 log) of each pathogen, (ii) assessing inactivation differences between LP and MP UV and (iii) finding similarities and differences among viral and bacterial pathogens inactivation. Each microorganism was diluted in artificial seawater, quantified, exposed to an UV dose (out of 5 doses) emitted either by a LP or MP UV lamp inside a collimated beam apparatus (CBA) and quantified after exposure to UV. Results showed that 99.9 % inactivation of IPNV, M. viscosa and Y. ruckeri required 200, 15 and 10 mJ/cm2 respectively by LP UV. The same pathogens were 99.9 % inactivated with 56.4, 4.6 and 11.3 mJ/cm2 respectively by MP UV. Overall, bacteria species demonstrated being less resistant to LP and MP UV than IPNV. This difference resulted from their different external structures, sizes, genome compositions and repair mechanisms. MP UV was able to inactivate IPNV and M. viscosa with lower doses than LP UV, even though being less energy efficient. The main advantage of MP over LP UV was its ability to emit wavelengths that are absorbed by repair proteins and enzymes, thus avoiding pathogens reactivation

Brown bear behaviour in human-modified landscapes: the case of the endangered Cantabrian population, NW Spain

Large carnivore populations are recovering in Europe after centuries of population decline. The Cantabrian brown bear Ursus arctos population is endangered, and it is a good example of a large carnivore inhabiting a human-modified landscape. In order to study the impact of human landscape elements on bear behaviour we analysed 10 years of Cantabrian brown bear records. Human activity and structures do not appear to have an impact on the duration or appearance of vigilance behaviour. While bears avoid direct contact with humans, the mere presence of human infrastructure and activities don't not appear to impact its vigilance behaviours. The brown bear seems to be adapted to human coexistence and this should give a different perspective in future conservation efforts; Comportamento do Urso-Pardo em paisagens modificadas pelo Homem: o caso da população Cantábrica em perigo, NO Espanha Resumo: As populações de grandes carnívoros estão a recuperar por toda a Europa após séculos de declínio populacional. A população Cantábrica de urso pardo Ursus arctos encontra-se em perigo e é um bom exemplo de um grande carnívoro que habita uma paisagem modificada pelo Homem. A fim de estudar o impacto dos elementos da paisagem humanizada no comportamento do urso pardo, analisamos 10 anos de registos de comportamento de urso pardo Cantábrico. A atividade e estruturas humanas não parecem ter impacto na duração ou no aparecimento do comportamento de vigilância. O urso-pardo evita o contato direto com os seres humanos, no entanto a mera presença de infraestruturas e atividades humanas não parece ter impacto no comportamento de vigilância. O urso-pardo parece estar adaptado à coexistência humana e isso deverá dar uma perspetiva diferente a futuros esforços de conservação

Is the dimension of the proximal aponeurosis of biceps femoris long head a risk factor for a strain injury?

Purpose: To determine i) the reliability of a semi-automated tracking method to quantify the BFlhApo (biceps femoris long head proximal aponeurosis) size (i.e area interface, average width, volume, and length) based on MRI (magnetic resonance imaging) data; and, ii) to examine if the BFlhApo size of elite footballers with history of BFlh (biceps femoris long head) injury differed compared to matched controls without a previous BFlh injury. Methods: Forty individuals performed a MRI in both thighs (31 with no BFlh strain history and 9 with a BFlh strain history) during the preseason period. To measure more precisely the BFlhApo size, a semi-automated tracking method was built and tested (intra- and inter-rater reliability). Comparisons of the BFlhApo size between thighs with history of BFlh injury (experimental group) and non-injured thighs (control group) were set, as well as in between groups (injured vs non injured; left vs right). Results: The analysis of the reliability using the semi-automated tracking method showed a good intra-rater and inter-rater reliability (ICC between 0.75 and 0.9, at 95% confidence interval). No statistically significant differences (P <0.05) were found in the BFlhApo size regarding to all thighs comparisons. Conclusions: A reliable measurement procedure was able to better quantify BFlhApo dimensions between individuals with and without history of BFlh injury. Individuals with history of BFlh injury suggest no significant differences in their BFlhApo dimensions compared to individuals without this history. Thus, it seems inappropriate to state that a smaller BFlhApo size is an independent risk factor for developing a BFlh injury.Objetivo: Determinar: i) a fiabilidade de um método de rastreamento semiautomático para quantificar o tamanho da BFlhApo (aponevrose proximal da longa porção do bicípite femoral) com base em imagens de ressonância magnética; e, ii) examinar se o tamanho da BFlhApo (i.e. área de interface, largura média, volume e comprimento) de futebolistas de elite com história de lesão da BFlh (longa porção do bicípite femoral) difere em comparação com um grupo de controlo, sem historial de lesão da BFlh. Método: Quarenta sujeitos realizaram ressonância magnética em ambas as coxas (31 sem história de lesão da BFlh e 9 com história de lesão da BFlh) durante o período de pré-época. Para medir com mais precisão o tamanho da BFlhApo, um método de rastreamento semiautomático foi desenvolvido e testado (fiabilidade intra e inter examinador). Comparações do tamanho da BFlhApo entre as coxas com história de lesão da BFlh (grupo experimental) e coxas não lesionadas (do grupo controlo) foram estabelecidas, bem como dentro dos grupos (lesionado vs. não lesionado; esquerdo vs. direito). Resultados: A análise da fiabilidade do método de rastreamento semiautomatizado mostrou uma boa fiabilidade intra examinador e interobservador (ICC entre 0,75 e 0,9, com intervalo de confiança de 95%). Não foram encontradas diferenças estatisticamente significativas (P <0,05) no tamanho da BFlhApo em relação a todas as comparações estabelecidas. Conclusões: Um procedimento de medição fiável foi capaz de quantificar melhor as dimensões da BFlhApo entre indivíduos com e sem histórico de lesão da BFlh. Indivíduos com histórico de lesão da BFlh sugerem não apresentar diferenças significativas nas dimensões da sua BFlhApo relativamente a indivíduos sem este histórico. Assim, parece desajustado afirmar que uma menor dimensão da BFlhApo seja fator de risco independente para desenvolver uma lesão da BFlh

Multi AGV coordination tolerant to communication failures

Nowadays, in many industrial environments that use several robots, there is the problem of controlling traffic. To control traffic, it is necessary to plan safe paths, avoid deadlocks and be immune to network failures. The objective of this project is to implement a system to control this traffic, that is, plan and control one fleet of robots that have multiple tasks to fulfill. This system will be based on implementing TEA *, an algorithm based on A * but that goes with the notion of time. At the same time, the system attempts to supervise, to see if the robots are fulfilling the plan and to guard against any communication failures

Adaptive Tuned Mass Damper (ATMD) based in shape-memory alloy (SMA) elements

The unique features of shape memory alloys (SMA) gives them an unmatched ability to be implemented in several fields of engineering. Considering their phase shift capacity, when thermoelectrically driven, SMAs assume an elastic modulus variation predicated upon two key parameters - stress and temperature. Based on the above statement, the present dissertation aims to develop a new vibration control system, which makes use of SMAs in order to extend and improve its operational domain. Initially, an experimental campaign is developed in order to design a mapping of the elastic modulus of a FLEXINOL R SMA sample.This mapping seeks to explore and an optimize the inclusion of shape memory alloys in vibration control systems. In a second step, two types of ATMDs (Suppressor and TMD) are mathematically studied in order to comprise the insertion of a SMA element in the control system. Considering the main purpose of this thesis, a particular case study structure was chosen to carry out the implementation of the new vibration control system. The selected structure consists in a footbridge built over an important highway located in the Lisbon city center, Portugal. At this stage, both the design of the SMA element and the subsequent operational limits are presented. Afterwards, a numerical model computed in MATLAB (The Mathworks, 2014) is developed to simulate the behavior of a two degrees of freedom (TDOF) system. This one provides the system’s behavior (structure + ATMD) towards a predefined harmonic request, evaluating the effects of the implementation of the new vibration control system. Using the above mentioned numerical model, an influence analysis of both control systems was carried out. Several comparisons between the variants of each ATMD (Suppressor and TMD) where drawn, showing the positive and negative aspects of their action. In the end, a single numerical model, with the ability to excite the structure, read its behavior, identify the vibration frequencies and properly tune the control system in real time, performed a complete structural analysis. Finally, a concluding chapter is presented, where the obtained results are discussed. This chapter also mentions the main future development prospects, that may be considered in studies conducted by other researchers