Studio ed analisi di sistemi radar passivi DVB-T

I sistemi radar passivi (o Passive Coherent Location) sono una classe di sistemi radar che rivelano bersagli sfruttando i segnali provenienti da trasmettitori non cooperanti, come emittenti radio, TV, GSM, UMTS ecc. Il Digital Video Broadcasting – Terrestrial (DVB-T) è lo standard del consorzio europeo DVB per una modalità di trasmissione televisiva digitale terrestre. Nella sua parte iniziale, questo elaborato illustra il principio di funzionamento dei sistemi radar passivi esistenti, per poi passare ad un’analisi dettagliata delle caratteristiche dei segnali DVB-T e della loro funzione di ambiguità. L’ultima sezione, infine, è dedicata all’esame degli aspetti realizzativi di un sistema radar passivo DVB-T attraverso l’utilizzo della Universal Software Radio Peripheral (USRP), un’implementazione low-cost e high-speed dell’hardware che permette di costruire e implementare rapidamente un potente e flessibile sistema radio supportato dal free software sviluppato dal progetto GNU Radio

Numerical simulation of Nitinol peripheral stents: from laser-cutting to deployment in a patient specific anatomy

The current clinical trend is to use percutaneous techniques, exploiting Nitinol self-expanding stents, to treat peripheral occluded vessels such as carotid or superficial femoral arteries. Although this class of stents addresses the biomechanical requirements (i.e. flexibility, kink resistance, etc.), it has been observed that many of these stents implanted in peripheral vessels are fractured. Numerical simulations have shown to be very useful in the investigation and optimization of stents and also to provide novel insights into fatigue/fracture mechanics. To date most finite element based stent simulations are performed in a straight simplified anatomy and neglect the actual deployment process; consequently there is a need for more realistic simulations taking into account the different stages of the stent design process and the insertion in the target anatomy into account. This study proposes a virtual framework to analyze numerically Nitinol stents from the laser-cutting stage to the deployment in a (patient specific) tortuous anatomy

Management of Distal Radius Fractures in the Elderly Patients

Distal radius fractures are one of the most common injuries treated by the orthopedic surgeons representing almost 1/6 of the fractures that are treated in the emergency departments and the 75% of all fractures of the upper limb and are second only to hip fractures in elderly population. The age distribution of this kind of injury is typically bimodal with peaks in the young patients (6-25) and in the elderly patients older than 65. In the first case the mechanism of injury is usually a high energy trauma, such as a car accident, whilst in the second one is usually a low energy trauma like a domestic fall. Various classification systems have been proposed for these fractures. The classic eponymy-based classification, which divides the fractures in “Colles, Smith, Hutchinson, etc” is always useful but we think that the best system could be a combination with the classic eponymy-based classification with the one proposed by the AO Trauma. Distal radius fractures are frequent in elderly active patients and are usually treated with closed reduction and cast immobilization for 5-6 weeks. Decision for surgical treatment in osteoporotic and elderly patients is difficult as there are no significant differences of functional outcome after non surgical and surgical treatment, patient’s comfort, pre- injury activity level, life style requirement, stage of osteoporosis, fracture stability, joint congruency, loss of previous reduction and bilateral fractures should be considered in decision making. Of different kinds of surgical treatment we prefer k-wires fixation, epibloc or ORIF with locking plate

Feasibility study and development of a full digital passive radar demonstrator

In the past few years we have witnessed a growing interest in Passive Radars which exploit electromagnetic emissions coming from non-cooperative transmitters for example TV/Radio stations. The main feature of these systems is the absence of a transmitter. This feature, in addition to reduced system costs, makes this kind of equipment hard to intercept. Many demonstrators have been developed in the past decade by Universities, research facilities and private companies, however, we can’t say we have found a solution to fully satisfy the performance and cost requirements. This thesis focuses on the development of a low cost passive radar demonstrator with the aim of achieving a high range resolution exploiting the DVB-T signal as illuminator of opportunity (IO), which should satisfy both cost and performance needs. The study and design of the above mentioned radar demonstrator lead to three main innovative aspects. The first aspect is the realisation of a low cost passive radar demonstrator based on Software Defined Radio (SDR) technologies. In particular the Universal Software Radio Peripherals (USRPs) seems to be a good solution which meets the requirements of scalability and modularity which our system must have, for example the possibility to receive different signals by using the same hardware configured via software. The second aspect is the development of the whole processing chain. A theoretical analysis and experimental validation for every algorithm have been done. In particular, all algorithms developed are independent from the type of illuminator of opportunity chosen. This advantage, in conjunction with the use of a hardware which can be reconfigured via software, makes the entire radar system adaptive to the signal used. The third and final point focuses on the way to obtain a passive radar system which offers high range resolution. Specifically, in this thesis, the possibility of obtaining a high range resolution using adjacent DVB-T channels has been studied. A theoretical analysis, followed by a validation on real data will highlight that the resolution enhancement is proportional to the number of exploited DVB-T channels. The radar’s functionality is tested on different scenarios: maritime and aerial. The experimental results obtained with the demonstrator in both scenarios for different types of targets is proved both the feasibility of our radar system and the actual improvement of range resolution resulting from using multiple DVB-T adjacent channel

A non-intrusive proper generalized decomposition scheme with application in biomechanics

This is the peer reviewed version of the following article: Zou, X., Conti, M., Diez, P., Auricchio, F. A non-intrusive proper generalized decomposition scheme with application in biomechanics. "International journal for numerical methods in engineering", 7 Setembre 2017., which has been published in final form at http://dx.doi.org/10.1002/nme.5610. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Proper generalized decomposition (PGD) is often used for multiquery and fast-response simulations. It is a powerful tool alleviating the curse of dimensionality affecting multiparametric partial differential equations. Most implementations of PGD are intrusive extensions based on in-house developed FE solvers. In this work, we propose a nonintrusive PGD scheme using off-the-shelf FE codes (such as certified commercial software) as an external solver. The scheme is implemented and monitored by in-house flow-control codes. A typical implementation is provided with downloadable codes. Moreover, a novel parametric separation strategy for the PGD resolution is presented. The parametric space is split into two- or three-dimensional subspaces, to allow PGD technique solving problems with constrained parametric spaces, achieving higher convergence ratio. Numerical examples are provided. In particular, a practical example in biomechanics is included, with potential application to patient-specific simulation.Peer ReviewedPostprint (author's final draft

Principles of wide bandwidth acoustic detectors and the single-mass DUAL detector

We apply the standard theory of the elastic body to obtain a set of equations describing the behavior of an acoustic Gravitational Wave detector, fully taking into account the 3-dimensional properties of the mass, the readout and the signal. We show that the advantages given by a Dual detector made by two nested oscillators can also be obtained by monitoring two different acoustic modes of the same oscillator, thus easing the detector realization. We apply these concepts and by means of an optimization process we derive the main figures of such a single-mass Dual detector designed specifically for the frequency interval 2-5kHz. Finally we calculate the SQL sensitivity of this detector.Comment: 29 pages, 10 figure

Simple and Rapid Non-Enzymatic Procedure Allows the Isolation of Structurally Preserved Connective Tissue Micro-Fragments Enriched with SVF

The stromal vascular fraction (SVF) consists of a heterogeneous population of stem and stromal cells, generally obtained from adipose tissue by enzymatic digestion. For human cell-based therapies, mechanical process methods to obtain SVF represent an advantageous approach because they have fewer regulatory restrictions for their clinical use. The aim of this study was to characterize a novel commercial system for obtaining SVF from adipose tissue by a mechanical approach without substantial manipulations. Lipoaspirate samples collected from 27 informed patients were processed by a simple and fast mechanical system (by means of Hy-Tissue SVF). The Hy-Tissue SVF product contained a free cell fraction and micro-fragments of stromal connective tissue. The enzymatic digestion of the micro-fragments increased the yield of free cells (3.2 times) and CFU-F (2.4 times). Additionally, 10% of free cells from SVF were positive for CD34+, suggesting the presence of endothelial cells, pericytes, and potential adipose-derived stem cells (ADSC). Moreover, the SVF cells were able to proliferate and differentiate in vitro toward adipocytes, osteocytes, and chondrocytes. The immunophenotypic analysis of expanded cells showed positivity for typical mesenchymal stem cell markers. The Hy-Tissue SVF system allows the isolation of stromal vascular fraction, making this product of potential interest in regenerative medicine