Virasoro conjecture for the stable pairs descendent theory of simply connected 3-folds (with applications to the Hilbert scheme of points of a surface)

This paper concerns the recent Virasoro conjecture for the theory of stable pairs on a 3-fold proposed by Oblomkov, Okounkov, Pandharipande and the author in arXiv:2008.12514. Here we extend the conjecture to 3-folds with non-$(p,p)$-cohomology and we prove it in two specializations. For the first specialization, we let $S$ be a simply-connected surface and consider the moduli space $P_n(S\times \mathbb{P}^1, n[\mathbb{P}^1])$, which happens to be isomorphic to the Hilbert scheme $S^{[n]}$ of $n$ points on $S$. The Virasoro constraints for stable pairs, in this case, can be formulated entirely in terms of descendents in the Hilbert scheme of points. The two main ingredients of the proof are the toric case and the existence of universal formulas for integrals of descendents on $S^{[n]}$. The second specialization consists in taking the 3-fold $X$ to be a cubic and the curve class $\beta$ to be the line class. In this case we compute the full theory of stable pairs using the geometry of the Fano variety of lines.Comment: 28 pages. Comments very welcome

Light Signs, the Work of Teófilo Rego for Neolux

The subject of our paper is the work carried out by the Portuguese photographer Teófilo Rego (1913/1993), between the 1950s and the 1960s, for the manufacturing company of neon signs Neolux. Among the universes of the professional commission and the themes that, on his own initiative, explores in his personal work, the text addresses the images that may be considered as catalogue photography, reportage and architectural photography, and that remember us a time when, all over the world, the neon advertising was part of the urban landscape – from New York to Paris, Madrid, Lisbon and, in this case, Oporto. The article analyses the history, the type and the goals of the different advertising and light signage, the effect produced by their presence in city, and discusses the many images suggested and reminded by these photographs.This text was co-funded with FEDER funds by the Operational Competitiveness Programme – COMPETE and national funds by FCT – Fundação para a Ciência e Tecnologia within the project Photography, Modern Architecture and the “School of Oporto”: Interpretations Around Teófilo Rego Archive (PTDC/ ATP-AQI/4805/2012 - FCOMP-01-0124-FEDER-028054

Autonomização do circuito de recargas de cartões pré-pagos

Tese de mestado em Engenharia Informática, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2007O relatório apresenta o desenvolvimento de um projecto designado por Autonomia do Circuito de Recargas de Cartões Pré-Pagos . O projecto consistiu no isolamento do processo de recargas, dos outros processos de negócio dentro do sistema de informação de um operador de comunicações móveis. Como resultados do mesmo, tornou-se possível efectuar mais rapidamente a recarga de um cartão e foram ainda criadas condições para que o processo seja mais tolerante a faltas do sistema de base de dados

A nonlinear model for the fluid-coupled vibrations of spent nuclear racks

In the near-past we introduced a simplified linearized model for the fluid-coupled vibratory responses of nuclear fuel racks, neglecting three-dimensional flow effects and assuming small gaps between the fuel assemblies. In this paper, using the same basic approach, we generalize the above-mentioned model to account for nonlinear squeeze-film and dissipative flow effects. The proposed methodology can be automatically implemented on a symbolic computer environment. Numerical simulations highlight the significance of nonlinear flow effects at high vibration amplitudes, yielding more realistic predictions

Automata Serialization for Manipulation and Drawing

GUItar is a GPL-licensed, cross-platform, graphical user interface for automata drawing and manipulation, written in C++ and Qt5. This tool offers support for styling, automatic layouts, several format exports and interface with any foreign finite automata manipulation library that can parse the serialized XML or JSON produced. In this paper we describe a new redesign of the GUItar framework and specially the method used to interface GUItar with automata manipulation libraries

Optimal and Robust Control of Atmospheric Reentry Trajectories

Reentering the Earth’s atmosphere is one of the most difficult phases of any spaceship’s mission. During reentry, following an optimal trajectory in terms of minimal heating rate, dynamic pressure, and maximum deceleration is vital to the mission’s success. This dissertation proposes a novel design for a controller based on H8 control methods, with the goal of achieving optimal and robust control for a Reentry Lifting Vehicle. This dissertation begins by summarizing the theory and history behind the Shuttle Space Program, including the planning of its trajectories and descriptions of the Reentry Flight Dynamics Model. The analysis of the obtained reference trajectory will follow and the comparison of it to a real shuttle trajectory will be made. The design and configuration of the H8 controller comes after, beginning with the linearization of the obtained system in the previous step and ending with the recalculation of vehicle state variables after its application. The disturbance is then applied and the results of the actuation of the controller are displayed. The H8 controller for Reentry Lifting Vehicle proves itself to be a useful application presenting satisfying and significant results in this critical phase of flight.A reentrada na atmosfera terrestre é uma das fases mais difíceis da missão de qualquer nave espacial. Durante a reentrada, seguir uma trajectória óptima em termos de taxa mínima de aquecimento, pressão dinâmica e maáxima desaceleração é vital para o sucesso da missão. Esta dissertação propõe o design de um controlador baseado em métodos de H8, com o objectivo de alcançar um controlo óptimo e robusto para um Veículo de Reentrada na atmosfera capaz de produzir sustentação. Esta dissertação começa com um resumo da teoria e história por detrás do Programa Espacial do Vaivém, incluindo o planeamento de trajectórias e descrições do Modelo de Dinâmica de Voo de Reentrada. A análise da trajectória de referência obtida seguir­se­á e será feita a sua comparação com uma trajectória real do vaivém. A concepção e configuração do controlador H8 virá depois, começando com a linearização do sistema obtida no passo anterior e terminando com o recálculo das variáveis de estado do veículo após a sua aplicação. A perturbação é então aplicada e os resultados do accionamento do controlador são exibidos. O controlador H8 para Veículo de Reentrada capaz de produzir Sustentação mostrou ser uma aplicação útil apresentando resultados satisfatórios e significativos nesta fase crítica de voo

Increasing the gap : how Nescafé Dolce Gusto strived in a hostile competitive environment

As part of the Nestlé Group, Nescafé Dolce Gusto was launched in Portugal in 2007 aiming to democratize an entire market segment exclusively owned by Nespresso until then: coffee capsules. Five years of successes later, António Sousa, the brand’s marketing manager, was faced with a few challenging circumstances which inevitably he had to address. He was witnessing an industry that never stopped growing year after year. Unfortunately, Nescafé Dolce Gusto was not alone driving this growth, as other players began surfacing and claiming their spot. The business environment had become aggressively competitive and resorting to sales promotions was revealing itself as a quick way to stay relevant, yet at the cost of profitability. Nonetheless, recovering market share lost to the main competitors was the key objective for 2012. Recent tax policy changes due to the economic crisis caused Nescafé Dolce Gusto to become the only brand selling a standard capsules pack at a price point above €5. António knew he had to start from there if he was to achieve the proposed targets. Surprisingly, he found out the solution could in fact be to develop a new promotional pack, differently sized and priced than the regular 16 capsules pack offered. At the end of the day, he had to choose between going for a 12 capsules pack or a 30 capsules pack, and this decision could be the most important he made in years.Como parte do Grupo Nestlé, a Nescafé Dolce Gusto foi lançada em Portugal em 2007 com o intuito de democratizar um segmento de mercado detido na totalidade pela Nespresso até então: o café em cápsulas. Cinco anos de sucessos depois, António Sousa, o gestor de marketing da marca, foi confrontado com algumas circunstâncias desafiantes, as quais ele teria inevitavelmente de abordar. Assistia a uma indústria que não parava de crescer ano após ano. Infelizmente, a Nescafé Dolce Gusto não estava sozinha neste crescimento à medida que outros players começavam a surgir e a tomar o seu lugar. O enquadramento empresarial tinha-se tornado agressivamente competitivo e recorrer à promoção de vendas era uma maneira rápida de tornar as marcas relevantes, a custo da rentabilidade. No entanto, recuperar a quota de mercado perdida para os principais concorrentes era o grande objetivo para 2012. Uma mudança recente na política de impostos devido à crise económica fez com que a Nescafé Dolce Gusto se tornasse na única marca com um pacote standard de cápsulas acima da barreira dos €5. António sabia que teria de começar por aí se ia cumprir as metas propostas. Surpreendentemente, descobriu que a solução poderia estar no desenvolvimento de um novo pacote promocional, de dimensão e preço diferentes em comparação com o pacote de 16 cápsulas regular. A decisão final era escolher entre um pacote de 12 cápsulas ou um de 30 cápsulas, e essa decisão poderia ser a mais importante que ele iria tomar nos últimos anos