Reconfigurable antennas for adaptive MIMO communication systems

The requirements for the next generation wireless systems seek to provide reliable high data rate at low cost. Unfortunately the current wireless communication infrastructure is notfully equipped to over this unprecedented quality of service. Major obstacles include: limited bandwidth availability, limited transmit power, and signal strength uctuations which are intrinsic to the multivariate wireless channel. Multiple Input Multiple Output (MIMO) antenna systems have emerged as one of the most significant technical breakthrough in modern wireless communications able to satisfy these stringent requirements. However the necessity of assuring a high data rate in a large variety of environments while reducing the antenna array space occupation on portable devices requires an improvement in current MIMO technology. To overcome these limitations, we propose in this thesis, the use of reconfigurable antennas that adaptively change, through RF switches, their radiation properties and frequency of operation according to wireless channel characteristics.The key idea of this work is to show that reconfigurable antennas, through their capability to dynamically change their electrical and radiation properties, can be used to change the propagation characteristics of the wireless channel existing between the transmitting and receiving antennas. The proposed MIMO system breaks from the conventional wisdom that the wireless propagation channel cannot be changed intentionally by the transceivers in the link.Three different novel classes of electrically multi element reconfigurable antennas are proposed as suitable candidates for reconfigurable MIMO systems: i ) a reconfigurable printeddipole antenna array that exploits inter element mutual coupling to achieve pattern reconfigurability, ii ) circular patches capable of exciting higher order modes to achieve pattern and polarization diversity, and iii ) a metamaterial leaky wave array that can be reconfigured in pattern to achieve unprecedented degrees of pattern reconfigurability.To effectively use such antennas with actual communication systems, a low power consumption method for selecting the array configuration is proposed. This technique exploits the close relationship between the environment that surrounds the antenna array and the antenna radiation characteristics in order to select optimal array radiation patterns without the need for intense channel sensing or excessive training. A complete reconfigurable antenna system composed of mutli-element reconfigurable antennas and a control unit capable of efficently driving the antennas is proposed to deliver unprecedented system performance.Analytical models of the proposed system are used to fully characterize the functionality and performance of the technology. A complete evaluation of the proposed system is conducted through electromagnetic simulations and eld measurements collected with a channel sounder speciiically designed to measure the performance of multi element antennasystems. It is demonstrated that the novel multi element reconfigurable antenna system is capable of providing i ) increased data rate compared to common non reconfigurable antennas in single link communications as well as in multi-link ad hoc networks, ii ) reduced space occupation by the antenna on the communication device exploiting the principles of pattern and polarization diversity, iii ) reduced number of radio-frequency chains needed at the receiver/transmitter and iv ) reduced amount of transmit power for achieving performancecomparable to that of standard non reconfigurable antenna systems.Ph.D., Electrical Engineering -- Drexel University, 200

Wavelet imaging of transient energy localization in nonlinear systems at thermal equilibrium: the case study of NaI crystals at high temperature

In this paper we introduce a method to resolve transient excitations in time-frequency space from molecular dynamics simulations. Our technique is based on continuous wavelet transform of velocity time series coupled to a threshold-dependent filtering procedure to isolate excitation events from background noise in a given spectral region. By following in time the center of mass of the reference frequency interval, the data can be easily exploited to investigate the statistics of the burst excitation dynamics, by computing, for instance, the distribution of the burst lifetimes, excitation times, amplitudes and energies. As an illustration of our method, we investigate transient excitations in the gap of NaI crystals at thermal equilibrium at different temperatures. Our results reveal complex ensembles of transient nonlinear bursts in the gap, whose lifetime and excitation rate increase with temperature. The method described in this paper is a powerful tool to investigate transient excitations in many-body systems at thermal equilibrium. Our procedure gives access to both the equilibrium and the kinetics of transient excitation processes, allowing one in principle to reconstruct the full picture of the dynamical process under examination.Comment: Paper to be published in Physical Review B. Talk given by FP at the VI International Symposium on Strong Nonlinear Vibronic and Electronic Interactions in Solids, Tartu (ES), 28 April - 1 May 201

Large thermal biasing of individual gated nanostructures

We demonstrate a novel nanoheating scheme that yields very large and uniform temperature gradients up to about 1K every 100nm, in an architecture which is compatible with the field-effect control of the nanostructure under test. The temperature gradients demonstrated largely exceed those typically obtainable with standard resistive heaters fabricated on top of the oxide layer. The nanoheating platform is demonstrated in the specific case of a short-nanowire device.Comment: 6 pages, 6 figure

Coupled simulations of the NACIE facility using RELAP5 and ANSYS FLUENT codes

This work deals with the development and preliminarily assessment of a coupling methodology between a modified version of RELAP5/Mod3.3 STH code and FLUENT commercial CFD code, applied to the NACIE (natural circulation experiment) LBE (lead bismuth eutectic) experimental loop (built and located at the ENEA Brasimone research centre). The coupling tool is used to simulate experiments representative of both natural circulation conditions and isothermal gas enhanced (assisted) circulation. Furthermore, an accidental test reproducing an Unprotected Loss of Flow (ULOF) scenario is also simulated and the outcomes are presented. A preliminary sensitivity analysis has shown that, to guarantee a suitable numerical convergence, the assisted circulation tests require a time step one order of magnitude lower compared to natural circulation ones. The comparison between the RELAP5 stand-alone simulations and RELAP5/FLUENT coupled simulations proved the capability to simulate the thermal-hydraulic behaviour of a loop experimental facility for all the examined conditions

INVESTIGATION ON VALBELLUNA AREA AND ITS OENOLOGICAL POTENTIALITY: CASE STUDY ON PROSECCO DOC

Context and purpose of the study - Valbelluna valley is an area located in the northeastern Italy. It is extended from the East-West between Feltre and Belluno, along the Piave waterway and enclosed between Cansiglio valley on the South and the Dolomites in the North. Here, the villages of Limana and Trichiana are present, which are considered for decades potentially interesting areas to aim a niche production with own particular properties.The position of this area, its sun exposition, its soil composition and the microclimate, are ideal factors to obtain vines and consequently wines with unique features especially regarding the diversity and complexity aroma. The viticulture is not new in Valbelluna valley, but nowadays the situation is deeply different. Up to the \u201860s the grape production was widely extended and it led 5,000/6,000 tons. The grape varieties produced were in particular hybrid such as Baco, Clinton and Isabella grapes. Viticulture and agriculture in Valbelluna suffered the countryside depopulation in particular after the Vajont disaster, that cancelled the majority of existent vines and in the postwar period, instead, there was an industrial increasing. The aim of this study is test and develop Glera vine in a different area it used to be, always an area presents in the Prosecco DOC area: Valbelluna. Material and methods - Some preliminary evaluations showed peculiar characteristics of Prosecco produced in this area such as marked acidity, coming from malic acid, savoury, well balanced, with a high expression and an important presence of floral aromas. Nowadays, this area is developing also the aromatic grapes production like Sauvignon, aromatic Traminer and Riesling. To have an objective evaluation about Valbelluna valley, place in which the Prosecco production is new, a study on sensorial features has carried out. It was led a comparison between Prosecco produced in Valbelluna and Prosecco coming from known DOC area in Veneto and Friuli Venezia Giulia.The sensory analysis was carried out to evaluate the Prosecco DOC position (from Valbelluna) respect the traditional one produced in DOC Veneto Friuli area and if some particular differences would have been between them. Results - The samples analyzed were statistically significant and they were tasted from a group of expert panel. The testing sections needed to define an organoleptic profile and compare the different samples. Data were analyzed with One-way Anova and Tuckey test.The results showed differences between Prosecco DOC from Valbelluna and traditional Prosecco DOC. In particular the Prosecco DOC sensory profile (from Valbelluna) differs from the other ones because of the floral wisteria taste, the olfactory intensity and pleasantness. The interesting results and differences in the organoleptic profile would allow next studies about the terroir potentiality in viticulture. Future investigations would have been regarding also viticultural aspects and, more in general, social aspects of Valbelluna area to define real potentiality in oenological production to promote a niche product as Prosecco DOC

STH-CFD codes coupled calculations applied to HLM loop and pool systems

This work describes the coupling methodology between a modified version of RELAP5/Mod3.3 and ANSYS Fluent CFD code developed at the University of Pisa. The described coupling procedure can be classified as "two-way," nonoverlapping, "online" coupling. In this work, a semi-implicit numerical scheme has been implemented, giving greater stability to the simulations. A MATLAB script manages both the codes, oversees the reading and writing of the boundary conditions at the interfaces, and handles the exchange of data. A new tool was used to control the Fluent session, allowing a reduction of the time required for the exchange of data. The coupling tool was used to simulate a loop system (NACIE facility) and a pool system (CIRCE facility), both working with Lead Bismuth Eutectic and located at ENEA Brasimone Research Centre. Some modifications in the coupling procedure turned out to be necessary to apply the methodology in the pool system. In this paper, the comparison between the obtained coupled numerical results and the experimental data is presented. The good agreement between experiments and calculations evinces the capability of the coupled calculation to model correctly the involved phenomena

HLMC Fuel Pin Bundle characterization in CIRCE-ICE pool facility

Abstract. This work, carried out at the DICI of Pisa University, in collaboration with ENEA Brasimone R.C., deals with the analysis and a preliminary discussion of the experimental tests performed in the Integral Circulation Experiment (ICE) configuration of the Circulation Eutectic (CIRCE) facility aiming to investigate the heat transfer in fuel rod bundle. The facility test section basically consists of an electrical bundle (FPS) made up of 37 pins arranged in a hexagonal wrapped lattice with a pitch to diameter ratio of 1.8. Along the FPS active length, two sections were instrumented to monitor the heat transfer coefficient along the bundle as well as the cladding temperatures at different ranks of the sub-channels. In particular, forced circulation condition tests were performed imposing a temperature difference through the FPS and a LBE mass flow rate through the FPS. Nusselt number in the sub-channels was calculated as function of the Peclet number and obtained results were compared to Nusselt numbers computed from correlations available in Heavy Liquid Metals (HLM) literature. Results shown that the Nu is slightly lower in the middle section (section 1) if compared with the ones into the upper section (section 3), and that behaviour is probably due to the turbulence of the flow which seems to be fully developed only in the upper part of the fuel pin bundle. Anyway the Nu number, calculated as function of the Pe number in the range Pe~1500÷3000 (forced circulation condition), matches well the numerical correlation available for HLM fuel pin bundle, (i.e. Ushakov and Mikityuk)

Ecosistemi per la ricerca Atti Convegno ACNP/NILDE. Trieste, 22-23 maggio 2014

Il secondo convegno congiunto ACNP / NILDE: ecosistemi per la ricerca è stato ospitato dal 22 al 23 maggio 2014 dall’Università di Trieste. Sono stati affrontati in un’ottica internazionale i temi del rapporto tra cataloghi collettivi e servizi interbibliotecari, e il più generale ambito dei servizi bibliografici per la ricerca scientifica. ACNP e NILDE possono essere considerati un vero e proprio ecosistema. Le biblioteche e i bibliotecari collaborano tra di loro in maniera reciproca e secondo modalità interconnesse, offrendo agli utenti servizi sempre più evoluti e dinamici. Questo ecosistema, essendo aperto, mette i propri servizi a disposizione della ricerca scientifica in senso generale. Il convegno di Trieste ha offerto l’occasione di investigare e proporre soluzioni innovative, interconnessioni e relazioni nuove e più proficue

A Pipeline for the Implementation of Immersive Experience in Cultural Heritage Sites in Sicily

Modern digital technologies allow potentially to explore Cultural Heritage sites in immersive virtual environments. This is surely an advantage for the users that can better experiment and understand a specific site, also before a real visit. This specific approach has gained increasing attention during the extreme conditions of the recent COVID-19 pandemic. In this work, we present the processes that lead to the implementation of an immersive app for different kinds of low and highcost devices, which have been attained in the context of the 3DLab-Sicilia project. 3DLab-Sicilia’s main objective is to sponsor the creation, development, and validation of a sustainable infrastructure that interconnects three main Sicilian centers specialized in augmented and virtual reality. The project gives great importance to the cultural heritage, as well as to the tourism related areas. Despite the presentation of the case study of the Santa Maria La Vetere church, the process of the final app implementation guided by the general pipeline here presented is general and can be applied to other cultural heritage sites