357 research outputs found
Uniqueness and Lagrangianity for solutions with lack of integrability of the continuity equation
No full textWe deal with the uniqueness of distributional solutions to the continuity equation with a Sobolev vector field and with the property of being a Lagrangian solution, that means transported by a flow of the associated ordinary differential equation. We work in a framework of lack of local integrability of the solution, in which the classical DiPerna-Lions theory of uniqueness and Lagrangianity of distributional solutions does not apply due to the insufficient integrability of the commutator. We introduce a general principle to prove that a solution is Lagrangian: we rely on a disintegration along the unique flow and on a new directional Lipschitz extension lemma, used to construct a large class of test functions in the Lagrangian distributional formulation of the continuity equation
ASO Author Reflections: Recurrence Following Post-neoadjuvant Pancreatectomy: How Can We Do Better?
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Cultura e socializzazione nelle città europee del terzo millennio
No full textIl volume raccoglie contributi intorno al tema della riorganizzazione delle città, ispirandosi alla realtà multietnica e pluriculturale che contraddistingue le società europee contemporanee.
La capacità di accogliere le differenze, l’individuazione di valori fondativi per una convivenza nel rispetto reciproco, la ricerca di percorsi alternativi ai processi di integrazione finora sperimentati si evidenziano come problematiche che invitano a riflettere sul significato innovativo della “cultura della socializzazione”.
L’architettura e l’urbanistica, che dovranno nel prossimo millennio tradurre in “spazi” e “luoghi” queste nuove istanze, saranno chiamate a dare il loro contributo in direzione dei traguardi di civiltà che già oggi vengono prospettati da altri ambiti di espressione della cultura.
Il dialogo interreligioso e i processi evolutivi che contraddistinguono la filosofia, la sociologia, la storia, la letteratura saranno fonti insostituibili di riferimento per le scelte organizzative, formali e spaziali della città futura.
Gli scritti sono articolati in quattro sezioni tematiche: Città cultura e religione, Città socialità e progetto, Città e ospitalità, Cultura della comunicazione.
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Scritti di: Laura Balbo, Francesca Bonicalzi, Manuel Brullet i Tenas, Aurora Campus, Elena Cao, Franco Cardini, Paul Chemetov, Maria Antonietta Crippa, Gianfranco Dalmasso, Adriano De Maio, Jacques Derrida, Abdellatif El Kettani, Roberto Formigoni, Pierfranco Galliani, Giuseppe Laras, Gian Carlo Magnoli, Carlo Maria Martini, Antonio Piva, Robert Sproson, Cesare Stevan, Marzio Tremaglia, Massimo Venturi Ferriolo.
*****Contributi di Khaled Fouad Allam, Giovanni Anversa, Thar Ben Jelloun, Bice Biagi, Umberto Folena, Ricardo Franco Levi
NEMATODE COLONIZATION OF PYRITE CINDER-POLLUTED SOIL
No full textThe nematofauna was studied in the early stages of a remediation trial at an industrial site where pyrite cinders had accumulated for 40 years in a large area and were then covered with mineral soil. The cinders were contaminated with several metals and metalloids. The soil of the experimental plots was derived from the mixture of cinders with the covering soil in a 1:1 ratio. Plots were amended with manure and sown with 3 metal resistant plants: Sorghum bicolor L., Helianthus annuus L., and Arundo donax L. Samples were taken : a) at the beginning of the trial on the pyrite cinders and covering soil, separately; b) from the mixture before the application of manure; c) from cultivated plots. Nematode communities were compared by using general composition, trophic structure, biodiversity and ecology indices. Nematofauna and other soil fauna were not detected in the pyrite cinders. Nematodes were recorded in the covering soil and after mixing with the cinders. In these early stages of the
remediation process, amending and cropping increased nematode abundance and biodiversity compared to the initial situation of the pyrite cinders. The nematode community structures and all calculated indices showed an increase in the quality of the soil after the remediation process. Our results showed that phytoremediation brought about the repopulation of an extremely compromised area. Moreover, the analysis of nematofauna could be a useful tool for assessing the degree of soil disturbance and soil remediation
Classifier Level Fusion of Accelerometer and sEMG Signals for Automatic Fitness Activity Diarization
No full textThe human activity diarization using wearable technologies is one of the most important supporting techniques for ambient assisted living, sport and fitness activities, healthcare of elderly people. The activity diarization is performed in two steps: the acquisition of body signals and the classification of activities being performed. This paper presents a technique for data fusion at classifier level of accelerometer and sEMG signals acquired by using a low-cost wearable wireless system for monitoring the human activity when performing sport and fitness activities, as well as in healthcare applications. To demonstrate the capability of the system of diarizing the user’s activities, data recorded from a few subjects were used to train and test the automatic classifier for recognizing the type of exercise being performed
Machine learning regression based on particle Bernstein polynomials for nonlinear system identification
No full textPolynomials have shown to be useful basis functions in the identification of nonlinear systems. However estimation of the unknown coefficients requires expensive algorithms, as for instance it occurs by applying an optimal least square approach. Bernstein polynomials have the property that the coefficients are the values of the function to be approximated at points in a fixed grid, thus avoiding a time-consuming training stage. This paper presents a novel machine learning approach to regression, based on new functions named particle-Bernstein polynomials, which is particularly suitable to solve multivariate regression problems. Several experimental results show the validity of the technique for the identification of nonlinear systems and the better performance achieved with respect to the standard techniques
A Driving Technique for AC-AC Direct Matrix Converters Based on Sigma-Delta Modulation
No full textDirect conversion of AC power between three-phase systems operating at different frequencies can be achieved using solid-state circuits known as matrix converters. These converters do not need energy storage elements, but they require sophisticated control algorithms to operate the switches. In this work we propose and evaluate the use of a sigma-delta modulation approach to control the operation of a direct matrix converter, together with a revised line filter topology suited to better handle the peculiarities of the switching noise produced by the sigma-delta modulation. Simulation results show the feasibility of such an approach, which is able to generate arbitrary output waveforms and adjust its input reactive power. Comparison with a space vector modulation implementation shows also better performance about total harmonic distortion, i.e., less harmonics in the input and output
Between scientific communication, document science and information science: Ranganathan and documentation in the 1950s and 1960s
No full textThe post-World War II years represent a moment of international reflection on the concept of Documentation, due to the technological-scientific impulse and the constantly growing informational phenomena. Already in 1934, the discussion was outlined by Otlet, giving rise to reflections destined to channel the interests of librarianship and the nascent science of information. An analysis of the process of Ranganathan’s elaboration of the concept of Document and Documentation is proposed in order to understand how the author positions himself, in the rich dialogue involving eminent voices in the field of documentation, from Otlet (1934), Briet (1951) to neo-documentation theorists, in an attempt to better historicize his contribution to the development of Information Science
A Comparative Study of Computational Methods for Compressed Sensing Reconstruction of EMG Signal
No full textWearable devices offer a convenient means to monitor biosignals in real time at relatively low cost, and provide continuous monitoring without causing any discomfort. Among signals that contain critical information about human body status, electromyography (EMG) signal is particular useful in monitoring muscle functionality and activity during sport, fitness, or daily life. In particular surface electromyography (sEMG) has proven to be a suitable technique in several health monitoring applications, thanks to its non-invasiveness and ease to use. However, recording EMG signals from multiple channels yields a large amount of data that increases the power consumption of wireless transmission thus reducing the sensor lifetime. Compressed sensing (CS) is a promising data acquisition solution that takes advantage of the signal sparseness in a particular basis to significantly reduce the number of samples needed to reconstruct the signal. As a large variety of algorithms have been developed in recent years with this technique, it is of paramount importance to assess their performance in order to meet the stringent energy constraints imposed in the design of low-power wireless body area networks (WBANs) for sEMG monitoring. The aim of this paper is to present a comprehensive comparative study of computational methods for CS reconstruction of EMG signals, giving some useful guidelines in the design of efficient low-power WBANs. For this purpose, four of the most common reconstruction algorithms used in practical applications have been deeply analyzed and compared both in terms of accuracy and speed, and the sparseness of the signal has been estimated in three different bases. A wide range of experiments are performed on real-world EMG biosignals coming from two different datasets, giving rise to two different independent case studies
Discrete Bessel Functions for Representing the Class of Finite Duration Decaying Sequences
No full textBessel functions have shown to be particularly suitable for representing certain classes of signals, since using these basis functions may results in fewer components than using sinusoids. However, as there are no closed form expressions available for such functions, approximations and numerical methods have been adopted for their computation. In this paper the functions called discrete Bessel functions that are expressed as a finite expansion are defined. It is shown that in a finite interval a finite number of such functions that perfectly match Bessel functions of integer order exist. For finite duration sequences it is proven that the subspace spanned by a set of these functions is able to represent the class of finite duration decaying sequences
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