Tesi: Riqualifcazione energetica e ambientale dei rifugi alpini. Supporto al processo decisionale del progetto di riqualifcazione e ottimizzazione degli edifci ricettivi isolati ad uso discontinuo in contesto climatico alpino, scollegati da reti di fornitura servizi.

Alpine huts are facilities for tourists placed in apart settings, usually subjected to a strong wear due to environmental factors and to the massive human presence while their opening. Their working is infuenced by the optimized management of the resources and by the extreme reduction of economic and environmental costs. With the analysis of needs and requirements which allow the building use, have been identifed renovation works on the existing huts which give an improvement either in technological integration and optimization or in building energy performance (also considering the use of renewable energy sources) or in gaining an indoor environmental comfort that enables a better living in it. A procedure has been defned which allow both their evaluation and application

Prediction of the Propulsive Performance of an Atmosphere-Breathing Electric Propulsion System on Cathode-Less Plasma Thruster

Atmosphere-breathing electric propulsion (ABEP) is a type of electric propulsion system that uses the atmosphere as a propellant source instead of a stored reservoir. This technology is still in its early stages, but holds the promise of providing a clean, efficient, and sustainable propulsion system for spacecraft, enabling very low Earth orbit (VLEO) mission scenarios. To optimise the ABEP technology, accurately simulating air-based plasma chemistry plays a crucial role. In this paper, an air-based global model (GM) is presented that includes a detailed chemistry model for the various reactions that are involved in ABEP applications. The model’s goal is to forecast the performance of a cathode-less RF plasma thruster under various pressure levels and species concentrations that are typical of VLEO missions. The GM was exploited to map the performance of a fictitious ABEP based on a cathode-less RF thruster in order to assess its feasibility in VLEO. The numerical model is promising as a tool for the design of ABEP systems and for the preliminary optimization of mission scenarios

homeland in the poetry of nik oloz baratasvili and giacomo leopardi

In 1839, the 22-year-old Nik'oloz Baratašvili composed the long poem Bedi Kartlisa (The Fate of Georgia), in which he tackled one of the issues of modern Georgia: whether the choice made in 1783 by King Erek'le II to draw up a treaty of friendship with the Russian Empire had been beneficial for Kartl-K'axeti. In the course of the poem Baratašvili maintains a stiff attitude, never siding for or against the choice of Erek'le II. Much more instinctive and impetuous is the attitude of the 20-year-old Giacomo Leopardi, who, faced with Italy in chains, is overwhelmed by an individualistic romantic impulse. In his songs, he desires greatness for his homeland and the glory of ancient times when people ran to die for it, he states his aversion to foreign rule and his hopes for Italy's resurrection

La conquista del Caucaso nella letteratura russa dell’Ottocento

The author addresses the issue of the conquest of Caucasus at the hand of the Tsarist army, investigating the attitude held towards this event by three of the major authors of nineteenth-century Russian literature: Aleksandr Puškin (1799-1837), Mikhail Lermontov (1814-1841) and Leo Tolstoy (1828-1910), expressed through some of their most famous works. As for Puškin, the analysis touches the three main Southern Poems, as well as the account of his trip to Arzrum in 1829 on the Russian-Turkish war theatre, and the drama Boris Godunov, dedicated above all to the matter of power, in which however the will to create an empire imposes itself. The analysis of Lermontov’s works, in addition to the poem The novice, set in Georgia, is also about the short story Bela, which is part of the 'novel' A hero of our time. The short story was chosen for its clear display of the Russian officers’ attitude of contempt towards the indigenous Caucasians. The analysis of Tolstoy starts with the young author’s position in the 1850s, when he was a voluntary fighter in the Caucasus, as shown in the story The raid. Then, the analysis moves to the position of the 'mature' Tolstoy, a pacifist and anti-militarist, who expresses his ideas in the long story Hadji Murat

Analysis of the plasma transport in numerical simulations of helicon plasma thrusters

The accurate simulation of the plasma transport in helicon sources is a key aspect to improve the design of Helicon Plasma Thrusters (HPTs). Specifically, the 3D-VIRTUS code was proven to provide satisfactory estimations of the propulsive performance of realistic HPTs (difference between measures and numerical estimations of the thrust <30%). Nonetheless, further investigations are needed to deepen the influence that the plasma chemistry model, the formulation of the energy equation, and the definition of the diffusion coefficients have on the results of the simulation. First, a quantitative analysis has been conducted on a simplified configuration of HPT to study each phenomenon separately. Second, the generalized fluid model has been benchmarked against measures of plasma density performed on a helicon source. The radiative decay reactions affect the estimation of the performance (e.g., thrust) up to 40%. The quasi-isotherm formulation of the energy equation affects results (e.g., electron density) up to 30%. Accounting for anomalous transport or defining diffusion coefficients classically does not have a major effect on the simulation (e.g., thrust varies less than 20%). The generalized formulation of the fluid model provides estimations of the plasma density, which are within the uncertainty band of the measures (i.e., differences <20%)

Fully kinetic study of facility pressure effects on RF-source magnetic nozzles

A fully kinetic 2D axisymmetric Particle-in-Cell (PIC) model is used to examine the effects of background facility pressure on the plasma transport and propulsive efficiency of magnetic nozzles. Simulations are performed for a low-power (150 W class) cathode-less radio-frequency (RF) plasma thruster, operating with xenon, between background pressures up to 10$^{-2}$ Pa and average electron discharge temperatures of 4 - 16 eV. When the electron temperature within the near-plume region reaches 8 eV, a decisive reduction in performance occurs: at 10$^{-2}$ Pa, in-plume power losses surpass 25% of the discharge energy flux. Given that the ionization energy for Xe is 12 eV, the 8 eV threshold indicates that a consistent percentage of electrons has energy enough to trigger ionization. On the other hand, when the temperature is below such threshold, the primary collisions are charge-exchange and inelastic ion scattering, and the power loss remains less than 10%. It is established that losses in the considered HPT are significant if the facility pressure is greater than 10$^{-3}$ Pa, at absorbed powers larger than 130 W. At the nominal 150 W, this results in a 15% thrust reduction. When facility pressure is taken into consideration over ideal vacuum simulations, numerical error is reduced to <30% when compared to experimental thrust measurements at 10$^{-3}$ Pa.Comment: 45 pages, 10 figures, 5 tables. Submitted to Acta Astronautic

Necessidade, oportunidade e ilegalidade em habitação – alojamento local e tendências contemporâneas

O arrendamento de curta duração de habitação está num processo rápido de mudança para um novo paradigma setorial onde as plataformas online (como o Airbnb) têm um papel preponderante. A imposição de restrições à atividade faz parte da agenda social e política da maioria dos países europeus. Contudo, conforme demonstram as primeiras tentativas, regulamentar não é suficiente, visto os promotores ignorarem muitas vezes as regras impostas. A monitorização e a fiscalização acarretam grandes dificuldades para a administração pública. Este artigo foca-se nas regras desenhadas para o alojamento local e no alcance das medidas implementadas em Portugal. Traça um esboço da ilegalidade urbanística nesta área na era da economia partilhada, abordando as estratégias de regulação e os resultados alcançados. A conclusão aponta para o facto de a verificação do cumprimento das obrigações legais de registo ou fiscais ser uma questão de justiça e responsabilidade social.Short-term housing rentals are in a rapid shift to a new sectorial paradigm where online platforms (such as Airbnb) play a significant role. The restrictions on the rentals of entire apartments are on the social and political agenda of most European countries. However, as the first attempts demonstrate, regulation is not enough, as owners often ignore it. The monitoring and enforcement of such rules entails great difficulties for public administrations. This article focuses on the rules designed and measures for short-term rentals implemented in Portugal. It outlines the urbanistic illegalities in this field in the age of shared economy, addressing the regulatory strategies adopted and the results achieved. The conclusions point out that the compliance with registration and taxation rules is a matter of justice and social responsibility