Longitudinal dynamics modeling and handling qualities of a conventional jet aircraft

Un noto centro di ricerca europea ha recentemente modificato un jet convenzionale di classe CS-25 in una piattaforma scientifica. Durante il processo di certificazione delle modifiche, l’impatto delle stesse sulle prestazioni è stato studiato in modo esaustivo. Per lo studio delle qualità di volo, i piloti collaudatori hanno sviluppato una procedura di certificazione ad hoc che consiste in test qualitativi separati della stabilità longitudinale, laterale e direzionale. L’obiettivo della tesi è analizzare i dati di volo, registrati durante i test di collaudo, con l'obiettivo di estrarre informazioni di carattere quantitativo circa la stabilità longitudinale del velivolo modificato. In primo luogo sono state analizzate tre diverse modifiche apportate all’aeromobile e successivamente i risultati sono stati messi a confronto per capirne l’influenza sulle qualità di volo dell’aeromobile. Le derivate aerodinamiche sono state stimate utilizzando la cosiddetta “identificazione dei parametri”, che mira a replicare le variabili registrate durante i test di volo, variando un dato insieme di coefficienti all’interno del modello linearizzato della dinamica dell’aeromobile. L'identificazione del modo di corto periodo ha consentito l'estrazione dei suoi parametri caratteristici, quali il rapporto di smorzamento e la frequenza naturale. La procedura ha consentito inoltre di calcolare il cosiddetto “Control Anticipation Parameter” (CAP), parametro caratterizzante delle qualità di volo di un aeroplano. I risultati ottenuti sono stati messi a confronto con i requisiti prescritti dalla normativa MIL-STD-1797-A, risultando conformi al livello più alto di qualità di volo.

A maximum entropy approach to disturbed ecosystems

The current climate crisis requires a comprehensive understanding of biodiversity to acknowledge how ecosystems’ responses to anthropogenic disturbances may result in feedback that can either mitigate or exacerbate global warming. Although ecosystems are dynamic and macroecological patterns change drastically in response to disturbance, dynamic macroecology has received insufficient attention and theoretical formalisation. In this context, the maximum entropy principle (MaxEnt) could provide an effective inference procedure to study ecosystems. Since the improper usage of entropy outside its scope often leads to misconceptions, the opening chapter will clarify its meaning by following its evolution from classical thermodynamics to information theory. The second chapter introduces the study of ecosystems from a physicist’s viewpoint. In particular, the MaxEnt Theory of Ecology (METE) will be the cornerstone of the discussion. METE predicts the shapes of macroecological metrics in relatively static ecosystems using constraints imposed by static state variables. However, in disturbed ecosystems with macroscale state variables that change rapidly over time, its predictions tend to fail. In the final chapter, DynaMETE is therefore presented as an extension of METE from static to dynamic. By predicting how macroecological patterns are likely to change in response to perturbations, DynaMETE can contribute to a better understanding of disturbed ecosystems’ fate and the improvement of conservation and management of carbon sinks, like forests. Targeted strategies in ecosystem management are now indispensable to enhance the interdependence of human well-being and the health of ecosystems, thus avoiding climate change tipping points.

Design and Performance Analysis of the Electrical Power System of a Petrochemical Facility

This thesis deals with the sizing and analysis of the electrical power system of a petrochemical plant. The activity was carried out in the framework of an electrical engineering internship. The sizing and electrical calculations, as well as the study of the dynamic behavior of network quantities, are accomplished by using the ETAP (Electrical Transient Analyzer Program) software. After determining the type and size of the loads, the calculation of power flows is carried out for all possible network layout and different power supply configurations. The network is normally operated in a double radial configuration. However, the sizing must be carried out taking into account the most critical configuration, i.e., the temporary one of single radial operation, and also considering the most unfavorable power supply conditions. The calculation of shortcircuit currents is then carried out and the appropriate circuit breakers are selected. Where necessary, capacitor banks are sized in order to keep power factor at the point of common coupling within the preset limits. The grounding system is sized by using the finite element method. For loads with the highest level of criticality, UPS are sized in order to ensure their operation even in the absence of the main power supply. The main faults that can occur in the plant are examined, determining the intervention times of the protections to ensure that, in case of failure on one component, the others can still properly operate. The report concludes with the dynamic and stability analysis of the power system during island operation, in order to ensure that the two gas turbines are able to support the load even during transient conditions.