Marine propeller optimisation tools for scenario-based design

The marine propulsion system is one of the most important components of a ship in order to cover the demanding operating needs of propulsion nowadays and to increase performance in a wide range of operating conditions. Marine propellers are designed with the purpose of matching the hull and machinery system, create the required thrust for the entire operational profile, and fulfil the techno-economical requirements that depend on the decision-making of several stakeholders. The final product must represent a unique propeller, designed for a specific vessel, and is a trade-off between all requirements. In an industrial framework, the marine propeller design process should therefore be straightforward and well-developed. The limited time under which the design process must be performed, plays a decisive role in the methods utilised to carry it out, as for example in the selection of the analysis tools, which must be fast and they usually involve semi-empirical evaluations. Since blade design is a multi-objective and multidisciplinary problem, automated optimisation has been used with the aim to search good solutions in the design space efficiently. However, automated optimisation has failed to be used in industrial applications due to obtaining solutions with high performance but with infeasible geometries, and as a method it proved to be inferior to the manual design process, something that shows the importance of the designer\u27s expertise. The main research question of this thesis is therefore related to incorporating optimisation in a systematic way in order to improve the propeller design process and assist the blade designers to obtain feasible and high-performing propellers in strict time constraints. A methodology is proposed that combines interactive optimisation with machine learning and in parallel new objectives are implemented for more complex scenarios. The designer is enabled to manually evaluate cavitation nuisance during the optimisation and guide the algorithm towards areas of the design space with satisfactory cavitation characteristics. Several scenario-based situations have been investigated by using the proposed methodology, that involve different propeller types, design and off-design conditions, several objectives and constraints, cavitation nuisance on the suction and the pressure side of the blade, and applications within conventional and wind propulsion. The results have shown that by involving the blade designer\u27s expertise in the design and optimisation process systematically, competitive propeller designs with feasible geometries can be obtained efficiently

Il «vivo lume» della prospettiva nella poesia di Alessandro Parronchi

Giovanna Ioli propone un discorso critico dell’opera poetica di Alessandro Parronchi, mettendo in risalto il tema della «prospettiva», che rappresenta la matrice della storia in versi dell”autore fiorentino. Studioso dei fenomeni della visione, dello specchio, Parronchi ha grande competenza della storia e della fenomenologia di questo tema, documentata da una serie di saggi teorici d’arte e di letteratura. Tali interventi, a partire dagli Study sulla ‘dolce’ prospettiva del 1964, che comprendono anche un capitolo importante sulla Commedia di Dante, rappresentano un discorso di metodo e si riflettono a tutto campo sull’opera di Parronchi, fino a diventare uno strumento fondamentale di lettura per le sue Poesie.Giovanna Ioli suggests a critical analysis of the poetical work of Alessandro Parronchi. She underlines the theme of the «perspective», which represents the poetical background of the Florentine author. Parronchi, who has investigated thephenomena of the vision, the mirror, is an expert of the history and phenomenology of this subject and his authority is proved by a series of the theorical essays on art and literature. These speeches, starting from the Study sulla ‘dolce’ prospettiva of 1964, include also an important chapter on the Commedia by Dante. They represent a treatise of method and have an all round reflection on Parronchi’s work so to become an essential instrument to understand his Poesie

Routes et logements des voyageurs dans la region de la Thrace (XVIe-XIXe siècles)

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Interactive Optimisation in Marine Propeller Design

Marine propeller design is a complex engineering problem that depends on the collaboration of several scientific disciplines. During the design process, the blade designers need to consider contradicting requirements and come up with one optimal propeller design as a solution to the specific problem. This solution is usually the trade-o between the stakeholders\u27 requirements and the objectives and constraints of the problem.The significant amount of design variables related to blade design problems requires a systematic search in a large design space. Automated optimisation has been utilised for a number of blade design applications, as it has the advantage of creating a large set of design alternatives in a short period of time. However, automated optimisation has failed to be used in industrial applications, due to its complex set-up and the fact that in more complex scenarios the majority of the non-dominated design alternatives are infeasible. This necessitates a way of enabling the blade designers to interact with the algorithm during the optimisation process.The purpose of this thesis is to develop a methodology that supports the blade designers during the design process and to enable them to interact with the design tools and assess design characteristics during the optimisation. The overall aim is to improve the design performance and speed. According to the proposed methodology, blade designers are called during intermediate stages of the optimisation to provide information about the designs, and then this information is input in the algorithm. The goal is to steer the optimisation to an area of the design space with feasible Pareto designs, based on the designer\u27s preference. Since there are objectives and constraints that cannot be quantified with the available computational tools, keeping the "human in the loop" is essential, as a means to obtain feasible designs and quickly eliminate designs that are impractical or unrealistic.The results of this research suggest that through the proposed methodology the designers have more control over the whole optimisation procedure and they obtain detailed Pareto frontiers that involve designs that are characterised by high performance and follow the user preference

Between Eleatics and Atomists: Gorgias’ Argument against Motion

The aim of my paper is to investigate Gorgias’ argument against motion, which is found in his Peri tou me ontos and preserved only in MXG 980a18. I tried to shed new light both on this specific reflection and on the reliability of Pseudo-Aristotle’s version. By exploring the so called “change argument” and the “argument from divisibility”, I focused on the particular strategy used by the Sophist in his synthetike apodeixis, which should be investigated in relation to the dispute between monistic and pluralistic ontology. In this regard, the puzzle from “divisibility everywhere” and its connection with the void as not-being can provide new elements to grasp the philosophical background in which the Sophist moves. On the one hand, Gorgias’ argument against motion is part of a broader dispute on the divisibility/indivisibility of being; on the other, his original elaboration of this puzzle seems to be perfectly understandable within the controversy between Eleatics and Atomists, and coherent with the argumentative style of the Sophist.The aim of my paper is to investigate Gorgias’ argument against motion, which is found in his Peri tou meontos and preserved only in MXG 980a18. I tried to shed new light both on this specific reflection and on the reliability of Pseudo-Aristotle’s version. By exploring the so called “change argument” and the “argument from divisibility”, I focused on the particular strategy used by the Sophist in his synthetike apodeixis, which should be investigated in relation to the dispute between monistic and pluralistic ontology. In this regard, the puzzle from “divisibility everywhere” and its connection with the void as not-being can provide new elements to grasp the philosophical background in which the Sophist moves. On the one hand, Gorgias’ argument against motion is part of a broader dispute on the divisibility/indivisibility of being; on the other, his original elaboration of this puzzle seems to be perfectly understandable within the controversy between Eleatics and Atomists, and coherent with the argumentative style of the Sophist

Dante on the hills

Dante sulle collineIl saggio percorre gran parte della produzione in prosa di Cesare Pavese (Paesi tuoi, Feria d’agosto, La luna e i falò, Il mestiere di vivere) alla ricerca della traccia dantesca nella creazione letteraria dello scrittore italiano. Tanto l’espressività dei migliori testi di Pavese quanto la ricchezza ermeneutica della sua opera sono in parte dovute alla forza simbolica ed allegorica di alcuni dei suoi più memorabili passaggi tragici, la cui prima «fonte» originaria italiana ci conduce fino a Dante Alighieri.The essay deals with most of the prose of Cesare Pavese (Paesi tuoi, Feria d’agosto, La luna e i falò, Il mestiere di vivere) trying to find the dantian trace in the Italian writer’s literature. Both the expressiveness of the best texts of Pavese and the hermeneutic richness of his work are in part indebted to the allegoric and symbolic tragic passages, whose original «source» leads to Dante Alighieri