Co-design of a Class-D Oscillator and Dedicated DC-DC Power Converter

openL'obiettivo di questa tesi è stato lo sviluppo di un oscillatore in Classe-D direttamente alimentato da un convertitore DC/DC. Inoltre, è stata esplorata la possibilità di utilizzare il segnale di uscita fornito dall'oscillatore per fornire il segnale di switching al convertitore. I vari componenti del circuito sono stati analizzati concentrandosi sulle sfide progettuali di ciascun componente, sulla loro interazione reciproca e cercando, se possibile, di ottenere un circuito completamente integrato. Alcune possibili soluzioni vengono poi fornite alla fine della tesi, compresi i risultati delle simulazioni per i circuiti presentati.This thesis analyses the design problems behind the realization of an integrated oscillator directly powered by a switching voltage regulator. Additionally, the possibility of using the oscillator itself to provide the switching frequency for the converter is explored. The building blocks constituting the circuit are analysed focusing on the different design challenges of each component, on how they interact with each other and if it is possible to obtain a fully integrated design. Some possible design solutions are then provided at the end of the thesis including simulation results for the presented circuits

L'UNUM ARGUMENTUM DI SANT'ANSELMO. ALLA RICERCA DELL'INTERPRETAZIONE AUTENTICA DELLA PROVA ANSELMIANA DELL'ESISTENZA DI DIO

Contro l’argomento anselmiano del Proslogion sono state sollevate varie obiezioni, come quelle, molto note, di Gaunilone, di san Tommaso e di Kant. In questo saggio si sostiene la tesi che tutte queste critiche si basano fondamentalmente su una interpretazione imprecisa del testo di Anselmo che, se correttamente letto, ne risulta invece al riparo. Viene quindi offerta una nuova lettura dell’unum argumentum, con la quale, ricercandone lo spirito originario e più autentico, viene messa in risalto innanzitutto la sua struttura formale di dimostrazione per assurdo, illustrando in secondo luogo l’importante rapporto di complementarità che lega questa tipologia di prova a quelle strutturate in modo diverso, che procedono cioè a posteriori per costruzione diretta.Many important Authors – as Gaunilo, Thomas Aquinas and Kant – have brought many well-known objections against the anselmian argument. This paper proposes the thesis that all these objections are based on an inaccurate interpretation of the Proslogion: in fact, an in-depth analysis of the text shows its fully validity. Therefore, it is offered a new reading of the anselmian argument, that looks for its original and authentic sense: firstly, it is enlightened its formal structure of proof by contradiction, and secondly it is showed its important complementary relationship with the other kind of a posteriori proofs

Thermal impact evaluation of an open loop heat pump system: integrated approach with project data, numerical modeling and groundwater monitoring

Open loop, geotermal system, low enthalpy, numerical simulation, FEFLOW-DHI

The effects of low enthalpy geothermal system on groundwater of the Cesine wetland

Cesine Wetland, Salento, low-enthalpy geothermal power plant, heat transport numerical model

The Compatibility of Geothermal Power Plants with Groundwater Dependent Ecosystems: The Case of the Cesine Wetland (Southern Italy)

The Cesine Wetland, located along the Adriatic coast, was recognized as a Wetland of International Interest and a National Natural Park. Managed by the "World Wide Fund for nature" (WWF), it is considered a groundwater dependent ecosystem which is affected by seawater intrusion. The site was selected to test the environmental compatibility of a low-enthalpy geothermal power plant (closed loop) operating in the aquifer saturated portion with purpose to improving the visitor centre. For this purpose, the long-lasting thermal impact on groundwater was assessed using a multi-methodological approach. The complex aquifer system was carefully studied with geological, hydrogeological and geochemical surveys, including chemical and isotopic laboratory analyses of surface water, groundwater and seawater. The isotopes δ18O, δD, δ11B, and 3H were useful to clarify the recharge contribution, the water mixing and the water age. All information was used to improve the conceptualization of the water system, including aquifers and the boundary conditions for a density driven numerical groundwater model. The purpose was to forecast anthropogenic thermal groundwater variations up to 10 years of plant working before the plant realization and to validate the solution after some working years. All results show the environmental compatibility notwithstanding the peculiar ecological environment

Heat exchange modeling in a multilayered karst aquifer affected by seawater intrusion

A Feflow thermohaline model has been implemented in order to study borehole heat exchangers (BHEs) activity in a coastal aquifer in the South of Italy (Province of Lecce, Puglia Region). The modeled closed-loop system consists of two double u-pipe heat exchangers, installed in 200 meters deep boreholes. The main purpose of numerical modeling was to forecast thermal plume extension in groundwater after a long period of heat exchange, calculating temperature trends in observation points during a 10 years transport simulation. The complex geological structure, including calcarenites, fractured limestones and a deep karst aquifer, has been translated into a multilayered model, with a depth-related parameter distribution, assigning different values of hydraulic, thermal and chemical properties to each layer. In particular saltwater concentration has been taken into account, considering the influence of seawater intrusion on the heat transport density-dependent model. Parameters assignment was based on experimental datasets collected during initial field investigations, including thermal characterization of soil samples and GRTs, together with historical hydrogeological and hydrochemical measures and previous groundwater surveys. After model structure configuration and aquifers parameterization, a sensitivity analysis on porosity and heat dispersivity has been conducted, to evaluate their influence on thermal transport phenomena with a multiple scenarios approach, considering in particular the uncertainty related to secondary porosity in karst systems. Feflow simulation represented the first step in environmental compatibility evaluation for the BHE plant, waiting for the necessary model calibration with groundwater temperature monitoring trends

Hydrogeological Modelling and Water Safety Plans: Basic Knowledge for the Protection of the Resource

Recent regulatory developments (DM 14.06.2017) have introduced the concept of Water Safety Plans (WSP) into the Italian legislative framework, a new, challenging paradigm of risk assessment, prevention, and control covering the entire drinking water supply chain. When applied to the water abstraction step, it requires complex data collection and processing, field survey, monitoring, and research in order to develop a robust and scientifically sound hydrogeological conceptual model, being the core of groundwater flow models and vulnerability assessments. A successful experience in identifying and characterizing the wellhead protection areas, as well as the vulnerability pattern, has been achieved for the wide and complex hydrogeological system belonging to the Vicenza water production area

A multi-scale methods comparison to provide granitoid rocks thermal conductivity

none9noranitoid rocks are frequently used in modern construction and restoration, hence the importance of knowing their petrophysical properties. These rocks find several applications in various types of surfaces, from flooring to walls, coupled to radiant devices for indoor air conditioning or as geological target in hot dry rock geothermal systems. In order to support the thermophysical characterization, the thermal conductivity of seven granitoid rocks belonging to five different lithologies (granodiorite, tonalite, granite, gabbro, and syenite) has been analysed, as main property which must to be assessed, by comparison between traditional measurement methods and a new analytical approach. In detail, the thermal conductivity was measured directly on the bulk rock samples, evaluated by applying Quantitative Phase Analysis starting from the Digital Imaging Analysis (DIA) and Rietveld refinement associating thermal parameters to each phase, and analysed by thermal modelling. Thermal simulation obtained by the 2D modelling highlights on the dependence of the thermo-physical properties of considered rocks from the minerals content, according to the abundance of quartz, as well as to the mineral's grain size and the geometrical grain distribution. This procedure provides a reliable estimation of the rock's thermal behaviour considering concurrently different mineralogical and textural parameters. The comparison between different approaches to thermal conductivity evaluation of granitoids allowed to consider the validity of the predictive approach, based on thermal modelling. The methodologies here developed and compared considering the thermal properties of granitic rocks can be extended and optimized for other types of rocks. © 2021 The AuthorsnoneChiara Coletti, Alessandro Borghi, Roberto Cossio, Maria Chiara Dalconi, Giorgia Dalla Santa, Luca Peruzzo, Raffaele Sassi, Arianna Vettorello, Antonio GalgaroColetti, Chiara; Borghi, Alessandro; Cossio, Roberto; Dalconi, MARIA CHIARA; DALLA SANTA, Giorgia; Peruzzo, Luca; Sassi, Raffaele; Vettorello, Arianna; Galgaro, Antoni