On the Enhancement of the Reconstruction Accuracy obtained with a Multi-Source/Multi-Illumination Inverse Scattering Technique

This paper explores the possibility of enhancing the available information content of scattered data by means of an innovative Multi-Source strategy. The approach exploits the scattering interactions between scatterer and probing source when the investigation domain is illuminated by different (in terms of radiation patterns) illuminations. The results of a set of representative numerical simulations are shown to point out the potentialities of the inversion strategy

Learning to use melodic similarity and contrast for narrative using a Digital Tabletop Musical Interface

This thesis investigates Digital Tabletop Musical Interfaces (DTMIs) in the context of music education. Digital tabletops have emerged in recent years, surrounded by much enthusiasm, and have found applications in a diversity of fields – from museum installations to engineering applications, from information systems, to music making. In particular, their ability to create a link between the physical and virtual world makes the digital tabletop an excellent way for beginners to approach music making. By allowing users to “touch” music, and experience it through various visual representations, in addition to its aural representation, digital tabletops provide an intuitively approachable way of making music that supports both beginners and experts, and allows them to collaborate and exchange knowledge and ideas. However, we still know little about the challenges and opportunities that DTMIs present, particularly their role in supporting music education. This thesis explores the challenges and opportunities presented by a bespoke DTMI in supporting people of different levels of musical experience in learning about some fundamental musical notions, and in learning how these can be used to compose music in an intentional way. This thesis covers three exploratory studies. In the first one, the notion of melodic contour, and its role as a visual metaphor for describing music, were explored by participants. A music composition task to describe a painting with music was presented to participants, and the ways in which participants described and composed music, in relation to melodic contour, were analysed. In the second study, the notions of melodic similarity and contrast, and their role in suggesting narrative, were explored by participants. Through a series of discussions and practical exercises, participants developed their understanding of melodic similarity and contrast, and learned how to use these notions to suggest narrative in melody. The third study followed directly from the second one, exploring again melodic similarity and contrast, but this time in a group setting. Groups of participants explored the musical notions using the DTMI as a discussion mediator. In these last two studies, the ways in which participants discussed the notions, and used them to compose music that suggested a narrative, were analysed. The findings suggest that it is possible to appropriately design a DTMI that can be used by both musically experienced and inexperienced people in order to create music in a way that is graspable for the novice, yet expressive for the expert, so that the two can discuss music with equal ease, and learn more about it

Towards a practical approach to music theory on the Reactable

This paper builds upon the existing Reactable musical platform and aims at extending and improving its approach to music theory. Sections 1 and 2.2 explain the motivations that led to the development of this proposal from a musical point of view while also giving a music education perspective. In section 2 we'll see a brief survey on tabletop and tangible multi-user systems for audiovisual performance and we'll also briefly introduce the process of implicit learning, we'll formulate a hypothesis about music as a natural language, and describe how the work hereafter presented can help music education. In section 3 we'll describe the current state of the art about music theory on the Reactable, followed by an original proposal about a way to extend and improve it. Finally we'll see how people who had a chance to test the system found it interesting and playful, while also giving important feedback that can be used to improve many practical aspects of the implementation

An Iterative Procedure for Combining the Advantages of a Multi-Frequency and Multi-Resolution Inversion Algorithm

Starting from the iterative multi�]scaling approach previously studied for monochromatic illuminations, two multi�]resolution strategies for dealing with multi�]frequency inverse scattering experiments have been developed. The first procedure is based on the integration of the iterative multi�]scaling algorithm into a frequency�]hopping reconstruction scheme, while in the second one the multi�]frequency data are simultaneously processed exploiting a multi�]resolution expansion of the problem unknowns. The numerical and the experimental analysis presented in this contribution concern with a preliminary assessment of the reconstruction effectiveness of the proposed approaches in comparison with a monochromatic multi�]step process. This is the author's version of the final version available at IEEE

Probing the Scattering of Equivalent Electroweak Bosons

We analyze the kinematic conditions under which the scattering of equivalent massive spin-1 vector bosons factorizes out of the complete process. In practice, we derive the conditions for the validity of the effective W approximation, proposed long ago but never established on a firm basis. We also present a parametric estimate of the corrections to the approximation and explicitly check its validity in two examples.Comment: 36 pages, 14 figures, references adde

Full-Vectorial Three-Dimensional Microwave Imaging Through the Iterative Multi-Scaling Strategy: a Preliminary Assessment

In this paper, a multi-scaling strategy for full-vectorial three-dimensional inverse scattering problems is presented. The approach is fully iterative and it avoids solving any forward problem at each step. Thanks to the adaptive multi-resolution model, which offers considerable flexibility for the inclusion of the a-priori knowledge and of the knowledge acquired during the iterative steps of the multi-scaling process, the overall computational burden is considerably reduced. This allows to balance effectively the trade-off between computational costs and achievable resolution accuracy. The effectiveness of the proposed approach is demonstrated through a selected set of preliminary experiments using homogeneous dielectric scatterers in a noisy synthetic environment

Electroweak Precision Tests in High-Energy Diboson Processes

A promising avenue to perform precision tests of the SM at the LHC is to measure differential cross-sections at high invariant mass, exploiting in this way the growth with the energy of the corrections induced by heavy new physics. We classify the leading growing-with-energy effects in longitudinal diboson and in associated Higgs production processes, showing that they can be encapsulated in four real "high-energy primary" parameters. We assess the reach on these parameters at the LHC and at future hadronic colliders, focusing in particular on the fully leptonic $WZ$ channel that appears particularly promising. The reach is found to be superior to existing constraints by one order of magnitude, providing a test of the SM electroweak sector at the per-mille level, in competition with LEP bounds. Unlike LHC Run-1 bounds, which only apply to new physics effects that are much larger than the SM in the high-energy tail of the distributions, the probe we study applies to a wider class of new physics scenarios where such large departures are not expected.Comment: 35 pages, 8 Figures, Fig.7 correcte

A Comparison Between Deterministic and Stochastic Inversions of Phaseless Data for Microwave Imaging

The development of microwave imaging techniques and their application are strongly related to the possibility to realize fast and cheap measurement systems. On the contrary, the phase acquisition usually requires complex and expensive apparatus and it turns out to be critical especially at high frequencies. Moreover, holographic and interferometric methods, often used in optical applications [1], are usually characterized by a high computational burden because of the time‐consuming data post‐processing. Consequently, the study of efficient algorithms for the reconstruction from amplitude‐only data is necessary in several applications. Also published in: Progress In Electromagnetics Research Symposium Abstracts, Hangzhou, China, March 24-28, 200

A robust adaptive algebraic multigrid linear solver for structural mechanics

The numerical simulation of structural mechanics applications via finite elements usually requires the solution of large-size and ill-conditioned linear systems, especially when accurate results are sought for derived variables interpolated with lower order functions, like stress or deformation fields. Such task represents the most time-consuming kernel in commercial simulators; thus, it is of significant interest the development of robust and efficient linear solvers for such applications. In this context, direct solvers, which are based on LU factorization techniques, are often used due to their robustness and easy setup; however, they can reach only superlinear complexity, in the best case, thus, have limited applicability depending on the problem size. On the other hand, iterative solvers based on algebraic multigrid (AMG) preconditioners can reach up to linear complexity for sufficiently regular problems but do not always converge and require more knowledge from the user for an efficient setup. In this work, we present an adaptive AMG method specifically designed to improve its usability and efficiency in the solution of structural problems. We show numerical results for several practical applications with millions of unknowns and compare our method with two state-of-the-art linear solvers proving its efficiency and robustness.Comment: 50 pages, 16 figures, submitted to CMAM