Ottimizzazione e progettazione di un sistema di cogenerazione statica di energia elettrica tramite celle ad effetto Seebeck

La presente trattazione descrive l’ottimizzazione del prototipo di un generatore termoelettrico da integrare in caldaie a biomassa. La tecnologia termoelettrica consente di generare potenza elettrica a partire da un flusso di calore. Sebbene tale tecnologia presenti caratteristiche di elevata affidabilità e silenziosità, essa richiede ulteriori sforzi tecnologici nella ricerca dell’integrazione ottimale con un impianto termico, ed è inoltre necessaria una progettazione accurata dell’elettronica di controllo. Nella prima sezione del testo vengono descritti i principi fisici alla base di questa tecnologia e le tecniche per la conversione della potenza generata dai moduli termoelettrici (o ad effetto Seebeck) al fine di renderla fruibile da una tipica utenza domestica. Nel secondo capitolo si riporta lo stato dell’arte dell’applicazione della tecnologia termoelettrica in caldaie a biomassa e alcuni casi di implementazione recenti, sottolineando le configurazioni utilizzate, i principali problemi riscontrati nello sviluppo e nella sperimentazione, e le modifiche conseguentemente adottate per superarli. Il terzo capitolo analizza il prototipo sviluppato presso il Dipartimento di Ingegneria Industriale dell’Università di Bologna e descrive il processo di dimensionamento dei componenti meccanici e le proposte di ottimizzazione a seguito dei risultati dei primi collaudi. Viene infine sviluppato un modello matematico per confrontare, in funzione dei costi di produzione e di esercizio, le possibilità di sostituzione dei metodi di generazione di energia elettrica convenzionali con l’impianto di cogenerazione termoelettrica realizzato, considerando anche aspetti di impatto ambientale. Tali analisi e ottimizzazioni consistono in un primo miglioramento necessario a rendere la tecnologia termoelettrica applicabile alle caldaie a biomassa stand-alone e a permettere una generazione continua di energia elettrica nelle regioni in cui le infrastrutture sono poco affidabili.

Strategic Management Simulation as a Blended Learning Dimension: Campus Based Students’ Perspectives

Although business simulations are widely used in management education, there is no consensus about how to optimise their application. Our research explores the use of business simulations as a dimension of a blended learning pedagogic approach for undergraduate business education. Accepting that few best-practice prescriptive models for the design and implementation of simulations in this context have been presented, and that there is little empirical evidence for the claims made by proponents of such models, we address the lacuna by considering business student perspectives on the use of simulations. We then intersect available data with espoused positive outcomes made by the authors of a prescriptive model. We find the model to be essentially robust and offer evidence to support this position. In so doing we provide one of the few empirically based studies to support claims made by proponents of simulations in business education. The research should prove valuable for those with an academic interest in the use of simulations, either as a blended learning dimension or as a stand-alone business education activity. Further, the findings contribute to the academic debate surrounding the use and efficacy of simulation-based training [SBT] within business and management education.

Modern Portfolio Theory Applied to Electricity Resource Planning

To meet electricity demand, electric utilities develop growth strategies for generation, transmission, and distributions systems. For a long time those strategies have been developed by applying least-cost methodology, in which the cheapest stand-alone resources are simply added, instead of analyzing complete portfolios. As a consequence, least-cost methodology is biased in favor of fossil fuel-based technologies, completely ignoring the benefits of adding non-fossil fuel technologies to generation portfolios, especially renewable energies. For this reason, this thesis introduces modern portfolio theory (MPT) to gain a more profound insight into a generation portfolio’s performance using generation cost and risk metrics. We discuss all necessary assumptions and modifications to this finance technique for its application within power systems planning, and we present a real case of analysis. Finally, the results of this thesis are summarized, pointing out the main benefits and the scope of this new tool in the context of electricity generation planning.

Handling Heterogeneity in Collaborative Networked Surgical Simulators

Stand-alone and networked surgical virtual reality based simulators have been proposed as means to train surgical skills with or without a supervisor nearby the student or trainee -- However, surgical skills teaching in medicine schools and hospitals is changing, requiring the development of new tools to focus on: (i) importance of mentors role, (ii) teamwork skills and (iii) remote training support -- For these reasons, a surgical simulator should not only allow the training involving a student and an instructor that are located remotely, but also the collaborative training of users adopting different medical roles during the training sesión -- Collaborative Networked Virtual Surgical Simulators (CNVSS) allow collaborative training of surgical procedures where remotely located users with different surgical roles can take part in the training session -- To provide successful training involving good collaborative performance, CNVSS should handle heterogeneity factors such as users’ machine capabilities and network conditions, among others -- Several systems for collaborative training of surgical procedures have been developed as research projects -- To the best of our knowledge none has focused on handling heterogeneity in CNVSS -- Handling heterogeneity in this type of collaborative sessions is important because not all remotely located users have homogeneous internet connections, nor the same interaction devices and displays, nor the same computational resources, among other factors -- Additionally, if heterogeneity is not handled properly, it will have an adverse impact on the performance of each user during the collaborative sesión -- In this document, the development of a context-aware architecture for collaborative networked virtual surgical simulators, in order to handle the heterogeneity involved in the collaboration session, is proposed -- To achieve this, the following main contributions are accomplished in this thesis: (i) Which and how infrastructure heterogeneity factors affect the collaboration of two users performing a virtual surgical procedure were determined and analyzed through a set of experiments involving users collaborating, (ii) a context-aware software architecture for a CNVSS was proposed and implemented -- The architecture handles heterogeneity factors affecting collaboration, applying various adaptation mechanisms and finally, (iii) A mechanism for handling heterogeneity factors involved in a CNVSS is described, implemented and validated in a set of testing scenarios

Detached eddy simulation of unsteady turbulent flows in the draft tube of a bulb turbine

Les aspirateurs de turbines hydrauliques jouent un rôle crucial dans l’extraction de l’énergie disponible. Dans ce projet, les écoulements dans l’aspirateur d’une turbine de basse chute ont été simulés à l’aide de différents modèles de turbulence dont le modèle DDES, un hybride LES/RANS, qui permet de résoudre une partie du spectre turbulent. Déterminer des conditions aux limites pour ce modèle à l’entrée de l’aspirateur est un défi. Des profils d’entrée 1D axisymétriques et 2D instationnaires tenant compte des sillages et vortex induits par les aubes de la roue ont notamment été testés. Une fluctuation artificielle a également été imposée, afin d’imiter la turbulence qui existe juste après la roue. Les simulations ont été effectuées pour deux configurations d’aspirateur du projet BulbT. Pour la deuxième, plusieurs comparaisons avec des données expérimentales ont été faites pour deux conditions d’opération, à charge partielle et dans la zone de baisse rapide du rendement après le point de meilleur rendement. Cela a permis d’évaluer l’efficacité et les lacunes de la modélisation turbulente et des conditions limites à travers leurs effets sur les quantités globales et locales. Les résultats ont montrés que les structures tourbillonnaires et sillages sortant de la roue sont adéquatement résolus par les simulations DDES de l’aspirateur, en appliquant les profils instationnaires bidimensionnels et un schéma de faible dissipation pour le terme convectif. En outre, les effets de la turbulence artificielle à l’entrée de l’aspirateur ont été explorés à l’aide de l’estimation de l’intermittence du décollement, de corrélations en deux points, du spectre d’énergie et du concept de structures cohérentes lagrangiennes. Ces analyses ont montré que les détails de la dynamique de l’écoulement et de la séparation sont modifiés, ainsi que les patrons des lignes de transport à divers endroits de l’aspirateur. Cependant, les quantités globales comme le coefficient de récupération de l’aspirateur ne sont pas influencées par ces spécificités locales.

As TIC, as práticas de ensino supervisionadas, a investigação e a inovação : os blogues educativos & a segurança na internet

Presentemente, em Portugal, estima-se que a utilização das TIC (Tecnologias da Informação e da Comunicação), pelos designados nativos digitais, corresponde a cerca de 98,S°/o. Considerando que os nativos digitais correspondem aos cidadãos que nasceram somente há 15 anos atrás, significa que toda a atual população escolar vive e convive rodeada de dispositivos e de ferramentas digitais no âmbito das suas rotinas diárias. Contudo, em termos gerais, não se tem verificado a mesma realidade no espaço educativo onde a presença de computadores e de uma ligação à Internet continua a ser muito escassa e incipiente. As Práticas de Ensino Supervisionadas, no âmbito do Mestrado em Educação Pré-escolar e Ensino do 1° Ciclo do Ensino Básico, têm vindo a constituir uma «janela de oportunidades» para a realização de investigações sobre a implementação das TIC no processo de ensino aprendizagem. Apesar de todos os constrangimentos, tem sido possível promover-se uma investigação que se pode considerar inovadora e exploratória pela inexistência de investigações anteriores similares. Para o efeito, é objetivo apresentarem-se os resultados de uma investigação que envolveu a utilização de blogues, no sentido destas ferramentas digitais promoverem novos contextos de aprendizagem e, ainda, com o objetivo de serem uma «ponte» que permitiu a aproximação entre a escola e a família. Um outro exemplo de investigação a apresentar diz respeito à utilização segura da Internet. Dos resultados obtidos foi possível verificar que crianças de 7/8 anos já fazem uma utilização autónoma da internet mas, em vários casos, foi possível averiguar-se que os respetivos pais não têm noção relativamente às utilizações que os seus educandos fazem no chamado ciberespaço. Em termos globais, foi possível apurar-se que as crianças aderem muito facilmente à utilização das tecnologias digitais na sala de aula, os alunos mostraram-se sempre muito envolvidos e motivados. Para terminar, é importante referir que, apesar de todas as vantagens apuradas, quer os alunos quer os pais, continuam a afirmar que a presença dos professores é fundamental e imprescindível no processo de ensino e de aprendizagem.

A NOVEL MODELING AND STATE OF CHARGE ESTIMATION SCHEME FOR LITHIUM-ION BATTERIES

Lithium Ion (Li-Ion) batteries have got attention in recent decades because of their undisputable advantages over other types of batteries. They are used in so many our devices which we need in our daily life such as cell phones, lap top computers, cameras, and so many electronic devices. They also are being used in smart grids technology, stand-alone wind and solar systems, Hybrid Electric Vehicles (HEV), and Plug in Hybrid Electric Vehicles (PHEV). Despite the rapid increase in the use of Lit-ion batteries, the existence of limited battery models also inadequate and very complex models developed by chemists is the lack of useful models a significant matter. A battery management system (BMS) aims to optimize the use of the battery, making the whole system more reliable, durable and cost effective. Perhaps the most important function of the BMS is to provide an estimate of the State of Charge (SOC). SOC is the ratio of available ampere-hour (Ah) in the battery to the total Ah of a fully charged battery. The Open Circuit Voltage (OCV) of a fully relaxed battery has an approximate one-to-one relationship with the SOC. Therefore, if this voltage is known, the SOC can be found. However, the relaxed OCV can only be measured when the battery is relaxed and the internal battery chemistry has reached equilibrium. This thesis focuses on Li-ion battery cell modelling and SOC estimation. In particular, the thesis, introduces a simple but comprehensive model for the battery and a novel on-line, accurate and fast SOC estimation algorithm for the primary purpose of use in electric and hybrid-electric vehicles, and microgrid systems. The thesis aims to (i) form a baseline characterization for dynamic modeling; (ii) provide a tool for use in state-of-charge estimation. The proposed modelling and SOC estimation schemes are validated through comprehensive simulation and experimental results.

An Islanding Detection Method based on Impedance Estimation and Grid Identification for Grid-Tie Distributed Power Generation Systems

Power system policies are broadly on track to escalate the use of renewable energy resources in electric power generation. Integration of dispersed generation to the utility network not only intensifies the benefits of renewable generation but also introduces further advantages such as power quality enhancement and freedom of power generation for the consumers. However, issues arise from the integration of distributed generators to the existing utility grid are as significant as its benefits. The issues are aggravated as the number of grid-connected distributed generators increases. Therefore, power quality demands become stricter to ensure a safe and proper advancement towards the emerging smart grid. In this regard, system protection is the area that is highly affected as the grid-connected distributed generation share in electricity generation increases. Islanding detection, amongst all protection issues, is the most important concern for a power system with high penetration of distributed sources. Islanding occurs when a portion of the distribution network which includes one or more distributed generation units and local loads is disconnected from the remaining portion of the grid. Upon formation of a power island, it remains energized due to the presence of one or more distributed sources. This thesis introduces a new islanding detection technique based on an enhanced multi-layer scheme that shows superior performance over the existing techniques. It provides improved solutions for safety and protection of power systems and distributed sources that are capable of operating in grid-connected mode. The proposed active method offers negligible non-detection zone. It is applicable to micro-grids with a number of distributed generation sources without sacrificing the dynamic response of the system. In addition, the information obtained from the proposed scheme allows for smooth transition to stand-alone operation if required. The proposed technique paves the path towards a comprehensive protection solution for future power networks. The proposed method is converter-resident and all power conversion systems that are operating based on power electronics converters can benefit from this method. The theoretical analysis is presented, and extensive simulation results confirm the validity of the analytical work.

Predicting the concentration of residual methanol in industrial formalin using machine learning

In this thesis, a machine learning approach was used to develop a predictive model for residual methanol concentration in industrial formalin produced at the Akzo Nobel factory in Kristinehamn, Sweden. The MATLABTM computational environment supplemented with the Statistics and Machine LearningTM toolbox from the MathWorks were used to test various machine learning algorithms on the formalin production data from Akzo Nobel. As a result, the Gaussian Process Regression algorithm was found to provide the best results and was used to create the predictive model. The model was compiled to a stand-alone application with a graphical user interface using the MATLAB CompilerTM.

Biology and management of dogfish sharks

This book comprises 34 chapters (35 including the initial keynote paper), each written as a stand-alone scientific paper, that are grouped in functional categories. The keynote paper is followed by 11 papers addressing Distribution and Abundance, 6 papers on Age, Growth and Reproduction, 6 papers on Ecology and Physiology, and 10 papers on Fisheries, Assessment and Management, and Conservation. Some of the papers are based upon presentations that were given at the First International Symposium on the Management and Biology of Dogfish Sharks, held in Seattle, WA in 2005.

Cordectomía por sustracción pedicular en la columna dorsal y lumbar en fracturas traumáticas: experiencia en el hospital universitario mayor Mederi y revisión sistemática de la literatura

Objetivo: Presentar la experiencia con la técnica de corpectomia por sustracción pedicular en fracturas traumática a nivel de la columna dorsal y Lumbar en el Hospital Universitario Mayor en Bogotá y hacer una revisión sistemática de la literatura de esta técnica quirúrgica. Material y métodos: Se realizó un análisis retrospectivo de las historias clínicas de pacientes que consultaron al servicio de neurocirugía entre los años 2013 y 2015 con fracturas traumáticas a nivel de la columna dorsal y lumbosacra. Se realizó un análisis de déficit neurológico pre y posoperatorio por medio de la Clasificación neurológica estándar de lesión medular (ASIA), al igual que tiempos de cirugía, sangrado intraoperatorio y complicaciones. A su vez se realiza una revisión sistemática de la literatura sobre esta técnica quirúrgica. Resultados: El total de pacientes que se sometieron a cirugía fue de 32, de los cuales el tiempo quirúrgico promedio fue de 396 min, se obtuvo un ASIA prequirúrgico B: 50% C: 47% y E: 3%. El ASIA post operatorio fue de B: 9% C: 47% D: 38% E: 6%. Se obtuvo una mejoría del déficit neurológico en el 75% los pacientes intervenidos. El promedio de sangrado fue de 1,223 cc. Se tuvieron 4 complicaciones, 2 hematomas en lecho quirúrgico que requirió re intervención y dos fistulas de líquido cefalorraquídeo las cuales se manejaron con vendaje compresivo y reposo absoluto. Conclusiones: La corpectomia por sustracción pedicular requiere de un adecuado entrenamiento y un grupo multidisciplinario dentro de los que se incluye neuroanestesiologo, a su vez de neurocirujanos entrenados en columna. Este abordaje presenta grandes beneficios como disminución de tiempos quirúrgicos, disminución de sangrado intraoperatorio y disminución de morbilidad entre otras.

Management Perspectives on Industrial Heritage: an Exploratory Research

The current research project focuses on the analysis of the critical issues of industrial heritage management in Italy and the preservation of organizational history within the reuse projects of former industrial sites. The organizational and managerial perspective is crucial on two levels. Firstly, it is important in the analysis of the original significance of the site, and in particular its organizational history, and its conservation within the new regeneration strategy. Secondly, it is crucial at the phase of management of reuse projects and its feasibility and sustainability analysis. Based on the analysis of the literature, a unique classification of the reuse strategies that can be implemented in order to regenerate former industrial sites has been formulated. The exploratory research thus adapts a multiple case study design. Eight Italian case studies have been chosen, one for each type of regeneration strategy. Each case study is explored as a stand-alone entity through the analysis of the local differences and idiosyncrasies of the specific context, the factors that stood behind the choice of the reuse strategy and the way the reuse project evolved through the years. Then, the current management of each reuse project is analysed. The narration and musealization of the organizational history is investigated through the spatial dimension, the level of content and the level of expression. Secondly, the case studies are compared through a cross-case analysis from three different perspectives: issues on the phase of preparation and implementation of the reuse projects, critical issues behind the current management of new projects and issues on the ways of preservation and narration of organizational history within the new project. The research shows that all regeneration strategies are affected by the conflict between preservation and change, by the issue of materiality and selectivity.

Lo studio del microclima indoor per la conservazione preventiva del Patrimonio storico artistico e culturale

La conservazione preventiva degli edifici storici e dei beni custoditi al loro interno rappresenta una sfida ad oggi condivisa a livello internazionale. Tale conservazione dipende da numerose variabili, tra le quali il microclima indoor gioca un ruolo decisivo. Il fine di questa tesi è verificare come lo studio del microclima indoor, supportato dalla simulazione virtuale e dalla conoscenza storica delle evoluzioni dell’edificio stesso (legate a modifiche impiantistiche; architettoniche; d’uso; ecc., nel corso degli anni), costituiscano una base conoscitiva fondamentale, da cui architetti e restauratori possono partire per definire strategie specifiche, volte alla conservazione preventiva del Patrimonio. Per fare questo, l’autore presenta le indagini svolte per tre casi-studio: la Sala 33 della Reggia di Venaria Reale, in provincia di Torino, Italia; la Biblioteca Generale Storica dell’Università di Salamanca, in Spagna; il Portico della Gloria, nartece della Cattedrale di Santiago de Compostela, in Spagna. La metodologia definita e adottata per l’analisi e l’interpretazione dei dati di ciascun caso-studio ha previsto la comprensione e la messa in relazione tra: scelte costruttive; vicende evolutive delle singole architetture; fattori che ne determinano il microclima, letti (o ipotizzati) nelle relative modifiche diacroniche; degrado delle architetture e dei beni che sono custoditi in esse. Infine, uno degli esiti più innovativi della ricerca è stata la definizione di due indici di rischio: sono stati infatti definiti due nuovi indici (Heritage Microclimate Risk -HMR- e Predicted Risk of Damage -PRD-) legati al microclima degli edifici che ospitano beni e manufatti che costituiscono il patrimonio storico artistico e culturale. Tali indici sono stati definiti tenendo conto di tutte le variabili da cui il microclima dipende e dei fattori che ne determinano l’evolversi nel tempo e nello spazio.

Percutaneous Cement Discoplasty: Biomechanical and clinical assessment of a minimally invasive treatment of lumbar intervertebral disc disease

With population ageing, spine diseases have an increasing prevalence and induce high economic and social costs. The development of minimally invasive surgeries allows reducing the surgery-associated risks in elderly and polymorbid patients, and save costs by treating more patients in shorter time and reducing the complications. Percutaneous Cement Discoplasty (PCD) is a minimally invasive technique developed to treat highly degenerated intervertebral discs exhibiting a vacuum phenomenon. Filling the disc with bone cement creates a stand-alone spacer which partially restores the disc height and re-opens the foraminal space. PCD has recently been introduced to clinical use. However, the spine biomechanics following this treatment remained unravelled. The aim of this PhD thesis is to bridge the clinical experience with in vitro methodologies, to provide a multilateral evaluation of PCD outcome and a better understanding of its impact on the spine biomechanics, and of its possible contraindications. Firstly, a suitable in vitro porcine model to test the biomechanics of discoplasty by comparing specimens in the preoperative and postoperative conditions was developed. The methodology was then applied to investigate the biomechanics of discoplasty in cadaveric human segments. The in vitro specimens were mechanically investigated in flexion and extension, while a DIC system quantified the range of motion, disc height, and strains on the disc surface. Then, a versatile tool to measure the impact of discoplasty on the foramen space was developed and applied both to clinical and experimental work. The vertebrae reconstructed from CT scans were registered to match the loading configuration, using ex vivo DIC measurements under loading. The foramen volumetric changes caused by PCD was measured using a 3D geometrical method clinically developed by the research group. In conclusion, this project significantly extended the understanding of PCD biomechanics, highlighting its benefits in the treatment of advanced cases of intervertebral disc degeneration.

Deep space orbit determination and guidance of the LICIACube microsatellite mission

Recently, the JPL's MarCO mission demonstrated that these probes are also mature enough to be employed in the deep space, even though with the limitations related to the employed commercial components. Currently, other deep space CubeSats are planned either as stand-alone missions or as companions of a traditional large probe. Therefore, developing a dedicated navigation suite is crucial to reaching the mission's goals, considering the limitations of the onboard components compared to typical deep space missions. In this framework, the LICIACube mission represents an ideal candidate test-bench, as it performs a flyby of the Didymos asteroid system subject to a strong position, epochs, and pointing requirements. This mission will also allow us to infer the capabilities of such microsatellites and highlight their limitations compared with the benefits of a lighter design and tailoring efforts. In this work, the OD and guidance methods and tools adopted for classical deep space missions have been tailored for the CubeSat applications and validated through extensive analyses. In addition, navigation procedures and interfaces have been designed in view of the operations foreseen in late 2022. The pre-launch covariance analysis has been performed to assess the mission's feasibility for the nominal trajectory and its associated uncertainties, based on conservative assumptions on the main parameters. Extensive sensitivity analyses have been carried out to understand the main mission parameters affecting the performance and to demonstrate the robustness of the designed trajectory and operation schedule in fulfilling the mission requirements. The developed system was also stressed by tuning the models to access different reconstruction methods for the maneuvers. The analysis demonstrated the feasibility of the LICIACube mission navigation in compliance with the mission requirements, compatible with the limited resources available, both in space and on the ground.