Pathway to a Compact SASE FEL Device

Newly developed high peak power lasers have opened the possibilities of driving coherent light sources operating with laser plasma accelerated beams and wave undulators. We speculate on the combination of these two concepts and show that the merging of the underlying technologies could lead to new and interesting possibilities to achieve truly compact, coherent radiator devices

A Robust Tucker3 Model for Compositional Data

Double counting is inherent to the output concept, therefore it is preferable to use manufacturing value added (MVA) instead to measure the manufacturing production. While the issue of double counting in production statistics is successfully addressed by using MVA, commodity exchange in trade data is still measured as output. The relevance of value added has increased in the recent years due to the unbundling of the production process, where different stages of value chain take place in different countries. We want to represent the export statistics through value added to output ratio using data from international statistical databases. The data sets considered are organized by country, commodity or activity and year (activities are classified according to the International Standard Industrial Classification of all economic activities (ISIC)) and thus they are three-way compositional data.\ud Different methods exist for analysis of multi-way data and we choose Tucker3 because it provides a compromise between parsimonious and flexible models. The Tucker3 method as most of the N-way methods is based on alternating least squares (ALS) which makes it vulnerable to the presence of outliers in the data. Even a single outliying data point can\ud strongly influence the resulting model and the conclusions based on it. A robust version of Tucker3 was presented by Pravdova et al. (2001) but it suffers from two main deficiencies. First of all the robust initialization of the algorithm is based on MCD which will not work in high dimensions. And secondly, the method is not suitable for applying on compositional data. We propose to select the initial subset using robust PCA and to transform the compositional data applying ilr transformation (Egozcue et al., 2003). Furthermore, since to our knowledge there is no readily available software for computing robust Tucker3 models, we provide\ud implementation of the proposed algorithm in R. The method is compared to its competitors both in terms of its efficiency and the computational effort needed

Joint Biplots for CoDa

Compositional data (CoDa) consist of vectors of positive values summing to a unit, or in general, to some fixed constant for all vectors. They appear as proportions, percentages, concentrations, absolute and relative frequencies. Sometimes, compositions arise from non-negative data (such as counts, area, weights, volume) that have been scaled by the total of the components because the analyst is not interested in the total sum of the vector. The multidimensional analysis of this kind of data requires a careful consideration because the sample space for CoDa is the simplex. The first consistent methodological proposal to deal with CoDa was proposed by Aitchison (1986) when he introduced the log-ratio approach. Basically, the idea that this approach conveys is to move from the simplex space to the real space by using log.ratio transformations, applying standard statistical methods, and finally, by means of an inverse log-ratio transformation, to interpret the results in the simplex space. Starting from this paper, pairwise, centered, additive and isometric log-ratio transformations, in short plr, clr, alr (Aitchison, 1986) and ilr respectively, are proposed in literature (Egozucue et al., 2003). In the context of dimension-reducing techniques, Aitchison (1983) proposed applying principal component analysis (PCA) after having applied a centered log-ratio (clr) transformation to CoDa. Aitchison and Greenacre (2002) suggested an adaptation of the biplot to CoDa. The biplot is a well established graphical aid in other branches of statistical analysis and can prove to be a useful exploratory and expository tool for compositions. In literature many papers on dimensional-reduction techniques for CoDa are proposed. Based on log-ratio strategy, Gallo (2012a, 2012b, 2013) recently proposed to use three-mode analysis of compositional data.\ud Starting from Gallo (2012b), we propose using of plr and clr joint biplots. Where in some cases the plr joint biplot is the only ones that show clearly the correlations

Three–way compositional data: a multi–stage trilinear decomposition algorithm

The CANDECOMP/PARAFAC model is an extension of bilinear PCA and has been designed to model three-way data by preserving their multidimensional configuration. The Alternating Least Squares (ALS) procedure is the preferred estimating algorithm for this model because it guarantees stable results. It can, however, be slow at converging and sensitive to collinearity and over-factoring. Dealing with these issues is even more pressing when data are compositional and thus collinear by definition. In this talk the solution proposed is based on a multistage approach. Here parameters are optimized with procedures that work better for collinearity and over-factoring, namely ATLD and SWATLD, and then results are refined with ALS

Role of structure of the Pp/magnetite nanocomposites on their thermal properties

The thermal degradation behaviour of polypropylene and its magnetite composites have been investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Distribution of magnetite nanoparticles in a polymer matrix has been studied by scanning and transmission electron microscopy and also atomic force microscopy. The thermal and mechanical properties of nanocomposites based on polypropylene and magnetite nanoparticles have also been investigated. It has shown that, the introduction of Fe3O4 nanoparticles in polypropylene increases its thermal stability of about 1000C. The maximum increase in the thermal stability of PP was observed in the case of a 20% weight content of Fe3O4 nanoparticles in polypropylene

SASE FEL Storage Ring

We explore the possibility of operating a SASE FEL with a Storage Ring. We use a semi-analytical model to obtain the evolution inside the undulator by taking into account the interplay on the laser dynamics due to the induced energy spread and to the radiation damping. We obtain the Renieri's limit for the stationary output power and discuss the possibility of including in our model the effect of the beam instabilities.Comment: 5 page

Didattica e Pedagogia Speciale. Percorsi educativi e formativi per BES e DSA

Gli aspetti didattici, educativi e della formazione degli studenti, gli approcci pedagogici speciali, le principali tecniche e metodologie didattiche innovative e gli ambiti dell’educazione motoria e sportiva, sono approfonditi con chiarezza ed efficacia all’interno di questo volume che si identifica quale valido strumento didattico e di sostegno per la ricerca nel campo delle scienze didattiche, pedagogiche, motorie e sportive

Crashworthiness of a composite bladder fuel tank for a tilt rotor aircraft

The fulfilment of the crash is a demanding requirement for a Tiltrotor. Indeed, such a kind of aircraft, being a hybrid between an airplane and a helicopter, inherits the requirements mainly from helicopters (EASA CS 29) due to its hovering ability. In particular, the fuel storage system must be designed in such a manner that it is crash resistant, under prescribed airworthiness requirements, in order to avoid the fuel leakage during such an event, preventing fire and, thus, increasing the survival chances of the crew and the passengers. The present work deals with the evaluation of crashworthiness of the fuel storage system of a Tiltrotor (bladder tank), and, in particular, it aims at describing the adopted numerical approach and some specific results. Crash resistance requirements are considered from the earliest design stages, and for this reason they are mainly addressed from a numerical point of view and by simulations that treat both single components and small/medium size assemblies. The developed numerical models include all the main parts needed for simulating the structural behavior of the investigated wing section: the tank, the structural components of the wing, the fuel sub-systems (fuel lines, probes, etc.) and the fuel itself. During the crash event there are several parts inside the tanks that can come into contact with the tank structure; therefore, it is necessary to evaluate which of these parts can be a damage source for the tank itself and could generate fuel loss. The SPH approach has been adopted to discretise fuel and to estimate the interaction forces with respect to the tank structure. Experimental data were used to calibrate the fuel tank and foam material models and to define the acceleration time-history to be applied. Thanks to the optimized foam’s configuration, the amount of dissipated impact energy is remarkable, and the evaluation of tanks/fuel system stress distribution allows estimating any undesired failure due to a survivable crash event

Quality improvement of medical records in a teaching hospital

Introduction. The aim of this study was to evaluate the quality of the MR compilation in some Operative Units of the ?Azienda Ospedaliera Universitaria - II Università di Napoli? (AOU- SUN) - Italy, before and after an intervention of quality improve- ment, underlining the potential differences in the behaviour of dif- ferent specialists (physicians vs. surgeons). Methods. Two random samples of 660 MRs were reviewed. A four-step program was developed: 1) first assessment of the MR; 2) implementation of the MR quality, sending a letter with the purpose of the study, the results obtained in the first step from that ward, the guidelines to correctly fill out the MR; 3) follow-up step four months later; 4) comparison of the data before and after the distribution of the guidelines using indicators of completeness of all sections of MR, clarity of handwriting and presence and clar- ity of signature. Results. The main concerns were related to the signature of the duty physician (present in 2.0% and legible in only 15.4%), the presence of the letter of discharge (18.0%) and the clarity of the days of hospital stay (32.0%). After the intervention the improvement of the quality of compilation was modest and regarded mainly medical rather than surgical wards. Discussion and conclusions. The improvement was not satisfying since from a medical and a legal point of view the indicators should reach 100% of clarity and completeness. A further study is being carried out to improve the involvement of health care professional, so that such requirements will be perceived as a common goal, not as mere bureaucratic initiatives