Robust and parallel scalable iterative solutions for large-scale finite cell analyses

The finite cell method is a highly flexible discretization technique for numerical analysis on domains with complex geometries. By using a non-boundary conforming computational domain that can be easily meshed, automatized computations on a wide range of geometrical models can be performed. Application of the finite cell method, and other immersed methods, to large real-life and industrial problems is often limited due to the conditioning problems associated with these methods. These conditioning problems have caused researchers to resort to direct solution methods, which signifi- cantly limit the maximum size of solvable systems. Iterative solvers are better suited for large-scale computations than their direct counterparts due to their lower memory requirements and suitability for parallel computing. These benefits can, however, only be exploited when systems are properly conditioned. In this contribution we present an Additive-Schwarz type preconditioner that enables efficient and parallel scalable iterative solutions of large-scale multi-level hp-refined finite cell analyses.Comment: 32 pages, 17 figure

The maturity of tourism neworks: an exploratory study

Networks in tourism are a growing phenomenon worldwide and tourism. Literature has devoted considerable space to networks’ policies, governance forms, competitive advantages and activities. Literature that focuses on networks’ operations generally analyzes what kind of activities are put in place without examining how they are carried out and whether they generate a competitive advantage. To fill this gap, our paper provides a notion of network maturity and introduces a taxonomy of the maturity levels of a network’s operations. The three-stage maturity model contributes to tourism literature by exploring how networks can evolve from basic to more sophisticated operations. From a managerial perspective, the paper contributes to evaluating network effectiveness and defining paths to improve it

Development of a Tourism Destination: Exploring the Role of Destination Capabilities

This article aims to identify the key elements underlying a destination capability (DC) and to examine what the genesis of these factors is and how they interact to foster the destination development. The article explores a specific development process—the creation of a new product in an alpine destination (Livigno, Italy)—making use of a theoretical framework structured around four major dimensions: DCs, coordination at the destination level, inter-destination bridge ties, and destination development. The results help clarify the genesis of a DC in the context of new product development. First, the dynamics underlying the creation of a DC show that coordination at the destination level constitutes the heart of the process, whereas the integration of scattered resources in the new product plays a more limited role. Second, from a dynamic perspective, the analysis has identified three patterns (scouting, implementation, and involvement)

Gli "archivi-museo" dell'Associazione nazionale combattenti e reduci in Puglia

In this paper were exhibited the first results of the census that in 2016-2017 involved the archives of the Puglia sections of the National Association of Fighters and Veterans, a project promoted by ANAI Puglia on the occasion of the celebrations of the Centenary of the First World War. The work aims to reconstitute, even if only virtually, the original structure of the paper archives and the book, photographic, iconographic and war memorabilia of the ANCR and highlight the current role of associations as centers of documentation and memory retention

Analisi sperimentale delle caratteristiche fluidodinamiche di flussi bi e trifase in condotti a sezione variabile

LAUREA MAGISTRALEQuesto lavoro, svolto presso il laboratorio di Termofluidodinamica Multifase del Politecnico di Milano, presenta: risultati di alcune campagne sperimentali volte a caratterizzare le cadute di pressione per flussi bi e trifase in condotti ad area variabile anche al fine di verificare la possibilità di impiegarli come strumenti di misura della portata, in analogia a quanto avviene per flussi monofase. In particolare sono stati considerati venturimetri e boccagli. Sono stati presi in considerazione flussi bifase aria-acqua e acqua-olio, e flussi trifase aria-acqua-olio. Mentre per i primi le cadute di pressione nel tratto convergente sono risultate fortemente dipendenti dalla ripartizione delle fasi, per quanto riguarda i flussi acqua-olio e acqua-olio-aria, si è riscontrato un comportamento simile a quello descritto dal modello omogeneo. In particolare, per i flussi acqua-olio è stato possibile accoppiare il modello omogeneo ad un modello delle cadenti che ha permesso la determinazione della portata totale e della portata delle singole fasi con errori inferiori al 10%. Molto lavoro resta ancora da fare sulla caratterizzazione dei flussi trifase sebbene sia stato possibile correlare le cadenti alla frazione volumica di gas in un ampio intervallo di variazione delle velocità superficiali. Completa il lavoro un’ampia rassegna fotografica dei regimi di moto che potrebbe risultare molto utile anche alla validazione di simulazioni CFD dei flussi multifase.This work was carried out at the Multiphase Flow and Heat Transfer Laboratory of Politecnico di Milano and shows the results of some experimental campaigns aimed at the characterization of the pressure drop in variable area ducts for two and three phase flows. In particular, it is investigated the possibility of adopting devices like Venturi flowmeters and nozzles to measure the flow rate of water-air, water-oil and water-oil-air mixtures as it is usually done for single phase flows. Compared to the homogeneous model, the behaviour of the pressure drop in the converging length results highly dependent on the volume fractions for water-air flows. Conversely, for water-oil and water-oil-air flows deviations from the homogenous model are limited within few percent. In particular, for water-oil mixtures, the adoption of separated flow model to predict the pressure gradient in the flow upstream/downstream the variable area device, enabled calculating the flow rates of each phase with about 10% average error. On the other hand, extensive efforts are still required for the characterization of three-phase flows even though it was possible to establish an empirical correlation between the pressure gradient and the gas-to-liquid volume fraction in a wide range of superficial velocities. Eventually, a photographic collection of flow regimes completes the work, which could also be very useful for the validation of prospective CFD simulations of multiphase flows

Adozione e percezione dell’intelligenza artificiale da parte delle PMI: uno studio esplorativo del contesto italiano

Sebbene l’intelligenza artificiale sia un tema ormai oggetto di studio nella letteratura manageriale, le cause che ne spiegano l’adozione da parte delle PMI e la loro percezione nei suoi confronti rimangono ancora tematiche poco esplorate. Questo studio empirico si fonda su una survey basata sul modello TOE - uno strumento particolarmente adatto ad analizzare l'adozione organizzativa dell'innovazione tecnologica - rivolta ad un campione di PMI italiane. I risultati, oltre a mostrare un utilizzo ancora generalmente modesto dell’IA, identificano 3 diversi profili organizzativi che descrivono i comportamenti e le attitudini delle PMI italiane verso l’IA: i costretti, i prudenti e gli innovatori. Questa ricerca contribuisce alla letteratura manageriale focalizzata sulle PMI attraverso: i) un’analisi esplorativa che applica il modello TOE per comprendere la rilevanza delle dimensioni tecnologiche, organizzative e ambientali ai fini dell’adozione di strumenti di IA; ii) un’analisi della percezione dei benefici e dei rischi legati all’uso dell’IA.Although artificial intelligence is now an established topic of study in the management literature, the causes that explain the adoption of AI tools by SMEs and their perceptions towards it still remain under explored. This empirical study is based on a survey applying the TOE model - a tool particularly suited to analyze the organizational adoption of technological innovation - administered to a sample of Italian SMEs. The results show a still generally modest use of AI, and identify 3 different organizational profiles describing the behaviors and attitudes of Italian SMEs towards AI: the forced, the cautious, and the innovators. This research contributes to the management literature focused on SMEs through: i) an exploratory analysis applying the TOE model to understand the relevance of technological, organizational, and environmental dimensions to the adoption of AI tools; ii) an analysis of the perceived benefits and risks associated with the use of AI

Sinkhole hazard assessment in Lesina Marina area (Apulia, Italy).

In “Lesina Marina” area, located in the north-western part of the Apulia region (Italy), near the Adriatic coast, sinkhole phenomena are particularly widespread and constitute a risk for the built-up area. These phenomena are due to the structure of the evaporitic rocks located in the study area and to the groundwater regime, influenced by the presence of a channel that connects the sea to the lagoon. The complex sea-channel-lagoon system produces an inland flow towards the channel modulated by the tide with a variable width according to the rules of the coastal aquifer