Analisi e simulazione di protocolli di accesso multiplo per reti IoT 6G cell-free

Lo scopo delle reti mobili è fornire ai dispositivi wireless accesso a una grande varietà di servizi dati, in un’ampia area geografica. Nonostante le reti cellulari odierne, basate sulla tecnologia Massive MIMO, possano raggiungere elevate performance in condizioni favorevoli (centro cella) esse, presentano all’interno dell’area di copertura, zone soggette a data-rate notevolmente ridotti. In questo elaborato, viene brevemente descritta la rete cell-free; una nuova architettura di rete pensata per superare i vecchi limiti delle reti cellulari tradizionali. Successivamente, vengono presentati attraverso simulazioni i due principali vantaggi che queste nuove reti cell-free offrono. Inoltre, viene analizzato uno schema random access in grado di gestire l’accesso multiplo per queste nuove architetture di rete. Questo schema rappresenta un’estensione di un protocollo già presente in letteratura e perfettamente funzionante per reti Massive MIMO, appartenente alla famiglia dei protocolli Coded Slotted ALOHA. Infine, un'analisi delle prestazioni e alcuni possibili scenari sono stati presentati, con lo scopo di valutare l'effetto che algoritmi di tipo SIC possono avere su queste reti.

Sintesi di nuovi derivati tri-componente per target photodynamic therapy della neoplasia prostatica

Therapies for the treatment of prostate cancer show several limitations, especially when the cancer metastasizes or acquires resistance to treatment. In addition, most of the therapies currently used entails the occurrence of serious side effects. A different therapeutic approach, more selective and less invasive with respect either to radio or to chemotherapy, is represented by the photodynamic therapy (PDT). The PDT is a treatment that makes use of photosensitive drugs: these agents are pharmacologically inactive until they are irradiated with light at an appropriate wavelength and in the presence of oxygen. The drug, activated by light, forms singlet oxygen, a highly reactive chemical species directly responsible for DNA damage, thus of cell death. In this thesis we present two synthetic strategies for the preparation of two new tri-component derivatives for photodynamic therapy of advanced prostate cancer, namely DRPDT1 and DRPDT2. Both derivatives are formed by three basic elements covalently bounded to each other: a specific ligand with high affinity for the androgen receptor, a suitably chosen spacer molecule and a photoactivated molecule. In particular, DRPDT2 differs from DRPDT1 from the nature of the AR ligand. In fact, in the case of DRPDT2 we used a synthetically engineered androgen receptor ligand able to photo-react even in the absence of oxygen, by delivering NO radical. The presence of this additional pharmacophore, together with the porphyrin, may ensure an additive/synergistic effect to the photo-stimulated therapy, which than may act both in the presence of oxygen and in hypoxic conditions. This approach represents the first example of multimodal photodynamic therapy for prostate cancer.

Computer aided design and finite element modeling to predict bulk mechanical properties of bone scaffolds using triply periodic minimal surfaces (progettazione assistita al calcolatore ed analisi con il metodo degli elementi finiti per predire il comportamento meccanico di scaffolds ossei creati con l'uso di superfici minime periodiche in tre direzioni)

The aim of Tissue Engineering is to develop biological substitutes that will restore lost morphological and functional features of diseased or damaged portions of organs. Recently computer-aided technology has received considerable attention in the area of tissue engineering and the advance of additive manufacture (AM) techniques has significantly improved control over the pore network architecture of tissue engineering scaffolds. To regenerate tissues more efficiently, an ideal scaffold should have appropriate porosity and pore structure. More sophisticated porous configurations with higher architectures of the pore network and scaffolding structures that mimic the intricate architecture and complexity of native organs and tissues are then required. This study adopts a macro-structural shape design approach to the production of open porous materials (Titanium foams), which utilizes spatial periodicity as a simple way to generate the models. From among various pore architectures which have been studied, this work simulated pore structure by triply-periodic minimal surfaces (TPMS) for the construction of tissue engineering scaffolds. TPMS are shown to be a versatile source of biomorphic scaffold design. A set of tissue scaffolds using the TPMS-based unit cell libraries was designed. TPMS-based Titanium foams were meant to be printed three dimensional with the relative predicted geometry, microstructure and consequently mechanical properties. Trough a finite element analysis (FEA) the mechanical properties of the designed scaffolds were determined in compression and analyzed in terms of their porosity and assemblies of unit cells. The purpose of this work was to investigate the mechanical performance of TPMS models trying to understand the best compromise between mechanical and geometrical requirements of the scaffolds. The intention was to predict the structural modulus in open porous materials via structural design of interconnected three-dimensional lattices, hence optimising geometrical properties. With the aid of FEA results, it is expected that the effective mechanical properties for the TPMS-based scaffold units can be used to design optimized scaffolds for tissue engineering applications. Regardless of the influence of fabrication method, it is desirable to calculate scaffold properties so that the effect of these properties on tissue regeneration may be better understood.

Progetto di una scheda a circuito stampato per il collaudo di un circuito integrato per Energy Harvesting da sorgenti eterogenee

Questo elaborato tratta la realizzazione di una scheda a circuito stampato. Essa è stata pensata con il compito di testare un circuito integrato per l'Energy Harvesting, progettato dall'Univesità di Bologna. La scheda implementerà numerose sorgenti alternative eterogenee Low-Power, cosicché il circuito integrato riuscirà ad estrapolarne una carica elettrica fino ad un massimo di alcuni milliwatt. Questa potenza sarà sufficiente ad alimentare qualsiasi dispositivo Low-Power.

Modelli e Strumenti di Classifciazione Automatica per il Controllo dell'Accesso su Piattaforme Big Data

Dall'analisi dei big data si possono trarre degli enormi benefici in svariati ambiti applicativi. Uno dei fattori principali che contribuisce alla ricchezza dei big data, consiste nell'uso non previsto a priori di dati immagazzinati in precedenza, anche in congiunzione con altri dataset eterogenei: questo permette di trovare correlazioni significative e inaspettate tra i dati. Proprio per questo, il Valore, che il dato potenzialmente porta con sè, stimola le organizzazioni a raccogliere e immagazzinare sempre più dati e a ricercare approcci innovativi e originali per effettuare analisi su di essi. L’uso fortemente innovativo che viene fatto dei big data in questo senso e i requisiti tecnologici richiesti per gestirli hanno aperto importanti problematiche in materia di sicurezza e privacy, tali da rendere inadeguati o difficilmente gestibili, gli strumenti di sicurezza utilizzati finora nei sistemi tradizionali. Con questo lavoro di tesi si intende analizzare molteplici aspetti della sicurezza in ambito big data e offrire un possibile approccio alla sicurezza dei dati. In primo luogo, la tesi si occupa di comprendere quali sono le principali minacce introdotte dai big data in ambito di privacy, valutando la fattibilità delle contromisure presenti all’attuale stato dell’arte. Tra queste anche il controllo dell’accesso ha riscontrato notevoli sfide causate dalle necessità richieste dai big data: questo elaborato analizza pregi e difetti del controllo dell’accesso basato su attributi (ABAC), un modello attualmente oggetto di discussione nel dibattito inerente sicurezza e privacy nei big data. Per rendere attuabile ABAC in un contesto big data, risulta necessario l’ausilio di un supporto per assegnare gli attributi di visibilità alle informazioni da proteggere. L’obiettivo di questa tesi consiste nel valutare fattibilità, caratteristiche significative e limiti del machine learning come possibile approccio di utilizzo.

Materiali ceramici a struttura Aurivillius per la produzione di solar fuels

Solar fuels from CO2 is a topic of current large scientific and industrial interest. In particular, photo-electrochemical cells (PECs) represent today one of the most promising technology for storing sun energy as chemical bonds exploiting carbon dioxide as starting reagent. In this thesis, the possibility of using Aurivillius-type compounds for the production of solar fuels was deeply investigated. Aurivillius-type perovskites, with general formula Bi(n+1)Fe(n-3)Ti3O(3n+3), were synthesized and fully characterized to study the influence of the number of perovskite layers as well as of the synthesis parameters onto their final properties. In particular, 8 different systems were considered increasing the amount of iron and, as a consequence, the number of perovskite layers. These compounds were synthesized through a standard solid-state reaction method as well as via a sol-gel technique and characterized by XRD, SEM and BET analyses. The band gap value and the photocatalytic activity towards Rhodamine B decomposition were assessed as well. For each system, a screen-printing ink was formulated to be deposited as photo-electrodes onto transparent conducting supports. The photo-electrodes were morphologically characterized by XRD and SEM analysis, and their electrochemical properties (cyclic and linear voltammetry, EIS, Mott-Schottky analysis) were determined. Finally, the most promising materials were tested as photo-cathode inside PEC cell under different illumination conditions, to quantify their ability to convert CO2. The obtained results show the potentiality of Aurivillius-type compounds as innovative material for carbon dioxide photo-electrochemical reduction.

Sintesi e caratterizzazione di CaCu3Ti4O12 (CCTO) per applicazioni in fotoelettrocatalisi

A promising strategy to mitigate both the energy crisis and global warming is the development of solar fuels and chemicals using as feedstock CO2 in combination with simple molecules such as water. This process stores the solar energy into chemical bonds, leading to a carbon-neutral approach of fuels and chemicals production. Aim of this thesis was the synthesis and characterization of CaCu3Ti4O12 (CCTO)- based compounds to be used as visible light photocatalyst for CO2 to chemical conversion. Different compositions were produced doping CCTO with increasing concentration of iron into the perovskite’s A site in order to identify the materials with the highest photo- and photoelectrocatalytic properties. The most promising compositions were used to produce photoelectrodes by screen printing that were characterized by linear and cyclic voltammetry, impedance spectroscopy and Mott-Schottky analysis to evaluate the electrical conductivity and calculate the flat band potential and the number of charge carriers in the samples. The photoelectrodes were then tested in a photoelectrochemical (PEC) cell for the conversion of CO2 into fuel and chemicals. The results obtained confirm that CCTO-based materials can be considered promising materials for carbon dioxide photo-electrochemical reduction.

Ossidazione elettrocatalitica di glucosio su schiume di nickel per la produzione selettiva di acido gluconico e acido glucarico

The selective electro-oxidation of D-glucose represents a promising way for the synthesis of many platform molecules, currently produced from non-renewable fossil fuels. Electrocatalysis is gaining considerable interest as an alternative to the thermochemical process, since it allows the process to be sustainable by operating at room temperature and pressure as well as using green solvents and electricity produced from renewable sources. In this work, the activity of three electrocatalysts, based on open cell Ni foams, towards the electrochemical oxidation of glucose to gluconic acid and glucaric acid was initially compared: a Ni bare foam, and Ni foams calcined at 500 °C for one hour and electrodeposited with Ni NP nanoparticles. The calcined foam turned out to be the most efficient. Then, the performance of this Ni calcined electrocatalyst was studied varying the reaction conditions, such as the potential applied (from 0,5V to 1,0V vs SCE), D-glucose concentration (0,01M, 0,05M and 0,10M) and NaOH concentration (0,10M and 1,0M). The activity of the electrocatalysts was evaluated in terms of glucose conversion, gluconic and gluconic acid selectivity and faradic efficiency. The best results were obtained over a Ni calcined foam with a 0,05M solution of D-glucose and 0,10M of NaOH at a 0,80V vs SCE potential.

Vettore energetico idrogeno: specificità per un'adeguata sperimentazione

L'elaborato analizza, in maniera generica, come avviene la produzione, lo stoccaggio ed il trasporto dell'idrogeno e valuta i mezzi che sfruttano l'idrogeno come combustibile: i veicoli a fuel cell e i veicoli con motori a combustione interna alimentati a idrogeno (H2ICE). Poiché le proprietà dell'idrogeno sono molto diverse rispetto a quelle dei combustibili convenzionali, queste nuove tecnologie necessitano di celle di prova appositamente progettate e dimensionate. L'elaborato, pertanto, descrive nel dettaglio quali sono le normative, le strumentazioni e gli standard da rispettare per garantire che, all'interno della sala, i test possano essere eseguiti in totale sicurezza. Inoltre, vengono esaminati i sistemi di consegna e dosaggio dell'idrogeno, passando poi al sistema di ventilazione che gioca un ruolo fondamentale nel funzionamento dei test. Infine, sono riportati esempi di specifici set-up sperimentali volti allo studio delle problematiche riscontrate nei motori a combustione interna alimentati a idrogeno. Nel primo set-up, vengono descritti i sistemi di controllo, il tipo di motore e tutti i sensori utilizzati per analizzare l'impatto che ha l'EGR sui motori H2ICE; mentre, nel secondo, vengono esaminati i fattori che inducono la detonazione e la relativa frequenza.