Dipartimento di Ingegneria Meccanica, Energetica e Gestionale - Tesi di Dottorato

Permanent URI for this collectionhttp://localhost:4000/handle/10955/100

Questa collezione raccoglie le Tesi di Dottorato afferenti al Dipartimento di Ingegneria Meccanica, Energetica e Gestionale dell'Università della Calabria.

Browse

Subject: search.filters.subject.Ingegneria meccanica

Search Results

Now showing 1 - 10 of 24
  • No Thumbnail Available
    Item
    Development, modeling and technical analysis of polymeric Fuel Cell propulsion systems for Hybrid Electric Vehicles
    (2015-12-16) De Luca, Domenico; Petronilla, Fragiacomo; Pagnotta, Leonardo
    Uno dei maggiori settori di consumo di petrolio e combustibili fossili è il settore dei trasporti. Questo comporta conseguenze negative per ciò che riguarda l’inquinamento ambientale ed i cambiamenti climatici. Le previsioni di un aumento mondiale del numero di veicoli a due ruote ed a quattro ruote, implicano una speciale attenzione per i combustibili alternativi e sostenibili dal punto di vista ambientale. In questo contesto l’idrogeno gioca un ruolo chiave. Le celle a combustibile, infatti, ad elettrolita polimerico si presentano come la più promettente tecnologia nel lungo periodo per produrre energia a bordo dei veicoli. Tale tecnologia trova applicazione nei veicoli ibridi in cui i flussi energetici sono ottimizzati. L’attività di ricerca svolta ha avuto come principale obiettivo l’analisi numerica di sistemi a propulsione innovativa equipaggiati con celle a combustibile. Questi studi sono stati condotti attraverso la definizione di modelli matematici di simulazione numerica in ambiente Matlab/Simulink®. I risultati consentono una dettagliata analisi delle celle a combustibile e delle configurazioni di veicoli ibridi con particolare riferimento ai flussi di potenza, al bilancio energetico, ai consumi, alla logica di controllo, all’umidificazione della membrana, al controllo termico, all’efficienza, ecc., al fine di dimensionare correttamente i vari componenti. L’utilizzo della simulazione numerica consente un’analisi più veloce ed economica rispetto alla realizzazione dei prototipi. Pertanto, essa può essere considerata come il primo passo nella progettazione e nella sperimentazione di questi veicoli. Il modello in Matlab/Simulink® consiste in un modello a blocchi dove i vari parametri operativi sono stimati in diverse condizioni operative nel rispetto di alcuni vincoli predefiniti. Le simulazioni sono svolte per diverse applicazioni per una vasta gamma di veicoli che comprendono veicoli a due ruote ed automobili di diversi segmenti per tragitti, definiti teoricamente, urbani, misti ed extra-urbani. Nel caso specifico di una veicolo a due ruote, derivato da una bicicletta elettrica con l’aggiunta di una cella a combustibile, i cicli di guida presi in considerazione non sono teorici, ma reali, in quanto ottenuti direttamente tramite misurazioni a bordo del veicolo
  • No Thumbnail Available
    Item
    Efficienza energetica e sostenibilità industriale: un prototipo di essiccatore a coclea
    (2016-12-15) Crea, Francesco; Pagnotta, Leonardo; Kaliakatsos, Dimitros
  • No Thumbnail Available
    Item
    Design and application of a novel microelectromechanical system for in situ SEM/TEM displacement controlled tensile testing of nanostructures
    (2012-11-30) Pantano, Maria; Pagnotta, Leonardo; Espinosa, Horacio; Rizzuti, Sergio
    Since the 1920s, different methodologies have been developed especially for mechanical characterization of material samples with characteristic length on the order of micro/nanometers. In the present manuscript, the main of such methodologies are presented and compared, in order to provide guidelines for mechanical characterization at the micro/nanoscale, and to identify the most versatile and effective among them. These are based on complete and miniaturized tensile testing stages, developed on proper microelectromechanical systems (MEMS). Because of their small size (they lie onto silicon wafers with area smaller than 1mm2 and thickness of only few micrometers), such testing devices are particularly suitable to handle micro/nanosized components, and can fit inside the tight chamber of scanning/ transmission electron microscopes (SEM/TEM), for real-time imaging of sample deformation. However, the effectiveness of the tests they allow to perform can be compromised by some disturbing phenomena, like onset of instability, as reported in a certain kind of tensile testing devices. In particular, these devices become unstable as soon as the sample under investigation shows stress relaxation, after some strain has been applied. Nevertheless, it is very important to be able to detect such singularities, since they may allow a deeper comprehen sion of materials’ behavior. In the present work, the above mentioned instability issue is overcome through the design of a novel device for in situ SEM/TEM tensile testing of nanostructures under true displacement control. Like other stages, also the one presented herein consists of two main components: an actuator and a sensor, which are separated by a small gap for positioning of the specimen. Actuation is performed by a thermal actuator, which pulls the end of the sample attached to it. The other end of the sample is instead connected to a displacement sensor, which moves from its equilibrium position, as a consequence of the force transmitted to it by the specimen. However, the main novelty of the present design is the introduction of a feedback control loop. In particular, a controller, implemented within a software routine, receives as input the sensor output, and computes the voltage to be applied to an electrostatic actuator, in order to generate a rebalance force of electrostatic nature, thus bringing the sensor back to equilibrium. In this way, the end ofand this boundary condition removes any potential source of instability. The MEMS sensing and actuating structures were designed by the means of both analytical and numerical approaches, in order to provide sufficiently high deformation (up to about 50% strain) and forces (up to 100μN) to break a variety of material samples. Fabrication was carried out by an external foundry on the basis of the masks drawings, reported in the present manuscript. In order to guarantee a correct functioning of the device, a proper experimental apparatus was developed. This allowed electrical connection of all of the actuating and sensing parts with external instrumentation, including current pre-amplifiers, power supplies, a lock-in amplifier, and a data acquisition card, which was used as interface between the controller and the MEMS device. The effectiveness of the present experimental apparatus was proven through an application on silver nanowires, with about 70 nm diameter and 3-4 μm gage length. The corresponding results, in terms of Young modulus, fracture and yield strength, showed good agreement with data already available in the literature, obtained for samples with comparable size. Also the device ability to detect singularities in the sample characteristic was demonstrated, as emerges from a load drop recorded after yielding of a nanowire. As a conclusion, the present experimental apparatus can be considered for future in situ SEM/TEM tensile tests on other material samples, as well as for electromechanical tests, since the specimen results to be electrically isolated from the remaining of the device. Thus, very interesting properties, like piezoresistivity and piezoelectricity, could be evaluated.
  • No Thumbnail Available
    Item
    Image-Guided robotic system for precision biopsy
    (2013-11-19) Donnici, Mario; Pagnotta, Leonardo; Danieli, Guido
  • No Thumbnail Available
    Item
    Soluzioni di involucro e impiantistiche innovative per edifici a basso consumo energetico
    (2013-11-19) Reda, Francesco; Arcuri, Natale; Pagnotta, Leonardo
  • No Thumbnail Available
    Item
    Effective traceability management: the global track&trace system
    (2013-11-27) Pizzuti, Teresa; Pagnotta, Leonardo; Mirabelli, Giovanni
    The evolution of the information technologies and their impact in human life promotes an increasing demand of reliable information when security and safety plays a primary role. Nowadays, food traceability represents one of the main concerns for public authorities and industries. In particular, traceability has become a critical part of the agro-food industry. The aim of the agro-food traceability is to allow the full monitoring of a product in the supply chain and to trace the history of a good from the producer to the consumer. It is therefore a preventive instrument of quality and safety management. The proposed research study is oriented to the definition of a new Global Track and Trace (T&T) System in which the entire world’s partners of a product’s supply chain are involved. In this system the functionalities of a conventional traceability system are combined with the functionalities of a Food Ontology for the traceability domain. The Food Ontology is defined in order to solve the issue of information-systems integration and standardization. The idea is to recover and to have available in a short time period all the relevant information about a product. This is a critical issue especially in case of foodborne outbreak and food crisis. The proposed framework can be a strategic approach for information and process management, also at the farm level. The model permits the Supply Chain optimization and the food quality management. The system itself can be a valuable tool for assuring customers and promoting the liability of the production process, along with the compliance with the regulatory standards aimed at defining quality and safety requirements.
  • No Thumbnail Available
    Item
  • No Thumbnail Available
    Item
    Identation-Based fracture characterization of brittle materials
    (2008-11-21) Leonardi, Alessandro; Rizzuti, Sergio; Furgiuele, Franco; Wood, Robert J.K.; Syngellakis, Stavros
  • No Thumbnail Available
    Item
    Thermomechanical characterization of Nickel-Titanium shape memory alloys
    (2007-11-23) Falvo, Andrea; Luchi, Maria Laura; Fugiuele, Franco
  • No Thumbnail Available
    Item