GME versus OLS - Which is the best to estimate utility functions?

This paper estimates von Neumann andMorgenstern utility functions comparing the generalized maximum entropy (GME) with OLS, using data obtained by utility elicitation methods. Thus, it provides a comparison of the performance of the two estimators in a real data small sample setup. The results confirm the ones obtained for small samples through Monte Carlo simulations. The difference between the two estimators is small and it decreases as the width of the parameter support vector increases. Moreover the GME estimator is more precise than the OLS one. Overall the results suggest that GME is an interesting alternative to OLS in the estimation of utility functions when data is generated by utility elicitation methods.Generalized maximum entropy; Maximum entropy principle; von Neumann and Morgenstern utility; Utility elicitation.

Towards a flexible and dynamic replication control for distributed real-time embedded systems with QoS interdependencies

Replication is a proven concept for increasing the availability of distributed systems. However, actively replicating every software component in distributed embedded systems may not be a feasible approach. Not only the available resources are often limited, but also the imposed overhead could significantly degrade the system's performance. The paper proposes heuristics to dynamically determine which components to replicate based on their significance to the system as a whole, its consequent number of passive replicas, and where to place those replicas in the network. The results show that the proposed heuristics achieve a reasonably higher system's availability than static offline decisions when lower replication ratios are imposed due to resource or cost limitations. The paper introduces a novel approach to coordinate the activation of passive replicas in interdependent distributed environments. The proposed distributed coordination model reduces the complexity of the needed interactions among nodes and is faster to converge to a globally acceptable solution than a traditional centralised approach

A feedback-based decentralised coordination model for distributed open real-time systems

Moving towards autonomous operation and management of increasingly complex open distributed real-time systems poses very significant challenges. This is particularly true when reaction to events must be done in a timely and predictable manner while guaranteeing Quality of Service (QoS) constraints imposed by users, the environment, or applications. In these scenarios, the system should be able to maintain a global feasible QoS level while allowing individual nodes to autonomously adapt under different constraints of resource availability and input quality. This paper shows how decentralised coordination of a group of autonomous interdependent nodes can emerge with little communication, based on the robust self-organising principles of feedback. Positive feedback is used to reinforce the selection of the new desired global service solution, while negative feedback discourages nodes to act in a greedy fashion as this adversely impacts on the provided service levels at neighbouring nodes. The proposed protocol is general enough to be used in a wide range of scenarios characterised by a high degree of openness and dynamism where coordination tasks need to be time dependent. As the reported results demonstrate, it requires less messages to be exchanged and it is faster to achieve a globally acceptable near-optimal solution than other available approaches

The intraindustry effects of going concern audit reports

This paper investigates the effect of a going concern opinion (GCO) on the equity value of the announcing firm’s competitors. On average, GCOs increase the value of a value-weighted portfolio of rivals by 0.37% at the event date. This positive effect is significantly larger when the announcing firm is relatively more profitable, the industry is more concentrated, and when rivals and event firms have distinct assets in place and growth opportunities. Additional tests reveal that such competitive effect is not a mere short-term phenomenon as investors can earn up to 1.54% on a risk-adjusted basis over the first postGCO month. This finding is especially interesting as we show that for the industry rivals the one-year and six-month preGCO riskadjusted equity returns are, on average, strongly negative. Our results highlight the impact of mandatory accounting information on market prices at both the firm and industry levels.Audit reports; Going concern; Competitive effect; Contagion effect.

Descoberta de padrões sequenciais utilizando árvores orientadas

Hoje em dia, a descoberta de padrões sequenciais em grandes bases de dados é um assunto de grande interesse. A maior parte dos algoritmos de padrões sequenciais usam estruturas de memória muito grandes no espaço de soluções e geram um número enorme de regras. Com a utilização do modelo das cadeias de Markov é possível ter uma visão global, já que todos os itens são tomados em consideração. Contudo, para grandes matrizes nas cadeias de Markov, a complexidade do problema cresce muito rapidamente. Neste artigo pretendemos manter a visão global dos itens e evitar tempos computacionais não-polinomiais. Usando heurísticas baseadas no algoritmo de Prim, árvores e poli-árvores podem ser encontradas em redes cíclicas. Os resultados computacionais são apresentados para grandes bases de dados, criadas com um conhecido gerador artificial de dados de teste.Abstract: The present study concerns the utilization of the Two-Step incremental clustering procedure to identify homogenous clusters of retail points that support the distribution network of frozen food products. The work is aimed to segment the retail points’ universe, in order to support the marketing and sales’ decision making. The segmentation is based on information stored in a data warehouse that includes stores characteristics and sales performances of each retail point. The results obtained allowed the identification of 4 clusters which profile was identified and evaluated using hypothesis tests.peerreviewe

The motivational factors of college students to engage in a physical activity program

Physical activity is considered an excellent option to achieve an optimum health condition. However, college students are usually linked to a sedentary life style, compromising health and life quality. Previous studies stated that men are usually linked to exercise due to challenge and fitness, while women look for appearance and stress management

Estrutura e funcionamento de Entidade Bancária. Banco do Brasil

Pretende-se que o presente relatório descreva sumariamente a história da Instituição Banco do Brasil, no Brasil e em Portugal, contextualizando-a no espaço e no tempo e que, em simultâneo, dê a conhecer a estrutura e o funcionamento de uma entidade bancária a operar em território nacional. Em termos teóricos, procuraremos cruzar o conceito de CRM (Customer Relationship Management) com a sua possibilidade de implementação numa Entidade Bancária e com a operacionalização que o estágio permitiu observar. Numa breve conclusão, serão abordadas algumas críticas ao estágio e as implicações que o mesmo poderá trazer no futuro profissional e nas relações laborais a desenvolver ao longo do mesmo

Mission Planner for Solar Powered Unmanned Aerial Vehicles

Unmanned aerial vehicles (UAV’s), initially used for military applications, have become increasingly attractive for civilian purposes. The use of this type of aircraft has grown exponentially in recent years, both for professional and recreational purposes, due to the numerous advantages they present. The increasingly demand of UAV led to an increase in investment, namely in the development of solar powered UAVs. Nowadays, with the arising of this type of UAV’s, the mission planners have to start to be updated with new features considering UAV’s with photovoltaic solar panels. This way, the present work describes the development and validation of a mission planner for solar powered UAV’s, capable of planning and optimizing a mission given a initial guess of waypoints parameters (latitude, longitude, altitude and airspeed), considering real weather forecast and terrain elevation data. For this, the mission planner considers several mathematical models, required for the calculation of the mission performance, and a sequential quadratic programming algorithm to optimize the initial mission. After it describes the theoretical models, a practical application of the mission planner is done in order to verify its performance. Regarding its validation, several results divided by topics of interest are presented and discussed, concluding that the mission planner works efficiently, regarding the mission planning, even though, it has some aspects to be improved.Os veículos aéreos não tripulados (UAV’s), inicialmente utilizados para aplicações militares, tornaram-se cada vez mais atraentes para fins civis. A utilização deste tipo de aeronave tem crescido exponencialmente nos últimos anos, tanto para fins profissionais como recreativos, devido às inúmeras vantagens que apresentam. Este aumento da procura levou a um crescente investimento no setor, nomeadamente nos UAVs movidos a energia solar, que hoje em dia já ocupam uma pequena fatia do mercado. No entanto, com o aparecimento deste tipo de UAV’s, os softwares de planeamento de missões precisam de ser atualizados de forma a terem em conta a energia fornecida pelo sol. Desta forma, o presente trabalho descreve o desenvolvimento e validação de um planeador de missões para UAV’s movidos a energia solar, capaz de planear e otimizar uma missão, considerando uma estimativa inicial dos parâmetros de cada waypoint (latitude, longitude, altitude e velocidade), e ainda considerando dados reais de previsão meteorologica e elevação de terreno. Para isso, o planeador de missões considera vários modelos matemáticos, necessários para o cálculo do desempenho da missão, e um algoritmo quadrático sequencial de forma a otimizar a missão inicial. Depois de descrever os modelos teóricos, uma aplicação prática do planeador de missão é feita com o objetivo de verificar o seu desempenho. Em relação à validação, vários resultados divididos por tópicos de interesse são apresentados e discutidos, concluindo: é eficiente em relação ao planeamento de missões, ainda assim, tendo alguns aspetos a serem melhorados

Digital Collections Service for the ROSSIO Infrastructure

Nowadays, especially during these challenging pandemic times, the need to have valuable cultural assets preserved online and available for current and future generations has grown exponentially. Cultural and educational sectors faced unprecedented obstacles as a result of the pandemic’s containment measures since many physical places such as schools, libraries, and museums had little choice but to close temporarily. Digital media has played a vital role in people’s daily interactions and was essential for the affected sectors to continue their work remotely. The pandemic has given an opportunity for cultural heritage organizations to show the benefits of digital collections and resources. By increasing access to a multitude of resources, spotlighting "hidden gems", preserving content, giving students digital materials to learn from, and providing users a different view on cultural heritage, the digital libraries and their digital collections have demonstrated how much they can enable a rich and diverse public domain. This Master’s dissertation was developed in collaboration with the ROSSIO infrastruc- ture, intending to create a service for their platform that allows the creation of digital collections made up of cultural heritage resources gathered by ROSSIO and its partner institutions. The developed service aims to give authenticated users access to an intuitive interface that includes the tools they need to create, edit, and share collections with the public, showcasing the best of Portugal’s cultural heritage in thematic collections that anyone can explore, enjoy and share.Hoje em dia, especialmente durante estes tempos difíceis de pandemia, a necessidade de ter artigos culturais valiosos preservados online e disponíveis, tanto para gerações atuais como futuras, tem aumentado exponencialmente. Devido às medidas de confinamento impostas durante a pandemia, tanto o sector cultural como o educacional teve de enfrentar desafios sem precedentes, uma vez que muitos locais físicos como escolas, bibliotecas e museus não tiveram outra opção que não fosse fechar temporariamente. Os meios digitais têm sido sem dúvida importantes para as interacções diárias entre as pessoas e foram essenciais para que os sectores afectados pudessem continuar o seu trabalho remotamente. A pandemia deu uma oportunidade para as organizações de património cultural mostrarem os benefícios de coleções e recursos digitais. Ao aumentar o acesso a uma infinidade de recursos, destacando "gemas escondidas", preservando o conteúdo, dando aos alunos materiais digitais para estudar e fornecendo aos utilizadores uma visão diferente sobre o património cultural, as bibliotecas digitais e suas coleções digitais demonstraram o quanto podem contribuir para um domínio público rico e diversificado. Esta dissertação de Mestrado foi desenvolvida em colaboração com a infraestrutura ROSSIO, com o objetivo de desenvolver um serviço na sua plataforma que permita a criação de coleções digitais, compostas por recursos patrimoniais culturais recolhidos pela ROSSIO e suas instituições parceiras. O serviço destina-se a ser usado por utilizadores autenticados, oferecendo-lhes um serviço com interface intuitiva que contém as ferramentas necessárias para criar, editar e partilhar coleções com o público, trazendo ao de cima o melhor que o património cultural português tem para oferecer, em coleções temáticas que qualquer um pode explorar, desfrutar e compartilhar com outras pessoas