1,721,511 research outputs found
Calibrating a motion detection system by means of a distributed genetic algorithm
No full textMotion detection systems for visual surveillance and monitoring purposes have aroused interest in the computer video community for many years. The main task of these applications is to identify (and track) moving targets. Usually, these applications requires that a large number of parameters is tuned in order to work properly. In the traffic monitoring application we have developed about thirty parameters concerning the detection algorithm have been considered as to be optimized. Genetic Algorithms (GAs) are an optimization technique which involves a search from a population of solutions rather than from a single point. Although they usually are very time-consuming, they owe a high intrinsic parallelism. Accordingly, this paper shows how a distributed implementation of a GA over a network of workstations can successfully accomplish the parameter optimization task within a motion detection system and achieve excellent performance within a reduced amount of time
La valutazione degli apprendimenti nella scuola primaria. Tre testi per orientarsi nel cambiamento in atto
No full textLa scuola primaria italiana sta vivendo un percorso di transizione rispetto alle pratiche valu-tative relative ai processi di apprendimento degli alunni e delle alunne. L’Ordinanza Ministeriale 172, emanata a dicembre 2020, ha segnato infatti un cambio di direzione dall’utilizzo dei voti alla formulazione di giudizi valutativi, intendendo in tal modo focalizzare l’attenzione sulla fun-zione formativa della valutazione. Ma a tale passaggio normativo non corrisponde necessaria-mente un cambiamento automatico nelle pratiche quotidianamente agite a scuola.Fra le molteplici occasioni di confronto, formazione e documentazione che hanno accom-pagnato l’introduzione di tale elemento normativo, si propongono tre testi che, affrontando tale passaggio da tre punti di vista diversi, ma fra loro integrati, possono rivelarsi utili sia per gli insegnanti in servizio alle prese con l’applicazione di tale norma di legge nelle proprie pratiche, sia per gli studenti di scienze della formazione primaria impegnati nello sviluppo delle compe-tenze valutative e di feedbac
Prevenire l’insuccesso formativo per gli studenti con fragilità educative. Il ruolo chiave della funzione di middle management dei referenti BES
No full textLa figura del referente BES risulta centrale per la realizzazione di misure preventive di tipo globale atte ad arginare il rischio di insuccesso formativo per gli studenti con fragilità educative. La sua efficacia appare però correlata alla possibilità di agire in una prospettiva di middle management. La ricerca, finalizzata a ricostruire un quadro interpretativo delle funzioni del referente BES rispetto alle dimensioni costitutive del middle management, è stata sviluppata attraverso un disegno di ricerca qualitativo sequenziale. Essa evidenzia come il ruolo e le funzioni dei referenti BES si possono configurare all’interno di un modello di leadership distribuita, nell’ambito del quale viene agita una delega progressiva
A methodological approach to parallel simulated annealing on an SMP system
No full textSimulated annealing (SA) is a stochastic optimization technique which guarantees under certain conditions to converge to a global minimum. The major disadvantage of this technique is its very slow convergence: this makes it not suitable for many complex optimization problems. Different parallel versions of the algorithm have been proposed, but none of them addresses recent 2-way symmetric multiprocessor (SMP) machines. In this paper, we present a novel approach to the parallel implementation of SA on an SMP system. In addition, we offer an adaptive method to dynamically change the program execution flow at run time, as to obtain the maximum benefit from these shared memory parallel architectures. Since we only exploit time measures for this purpose, we obtain a problem independent and a general purpose implementation. The effectiveness of the method is demonstrated by extensively analyzing the traveling salesman problem (TSP) as a target case study, on a system under different workload conditions. © 2002 Elsevier Science (USA)
Evaluation of a fully 3-D BPF method for small animal pet images on mimd architectures
No full textPositron Emission Tomography (PET) images can be reconstructed using Fourier transform methods. This paper describes the performance of a fully 3-D Backprojection-Then-Filter (BPF) algorithm on the Cray T3E machine and on a cluster of workstations. PET reconstruction of small animals is a class of problems characterized by poor counting statistics. The low-count nature of these studies necessitates 3-D reconstruction in order to improve the sensitivity of the PET system: by including axially oblique Lines Of Response (LORs), the sensitivity of the system can be significantly improved by the 3-D acquisition and reconstruction. The BPF method is widely used in clinical studies because of its speed and easy implementation. Moreover, the BPF method is suitable for on-time 3-D reconstruction as it does not need any sinogram or rearranged data. In order to investigate the possibility of on-line processing, we reconstruct a phantom using the data stored in the list-mode format by the data acquisition system. We show how the intrinsically parallel nature of the BPF method makes it suitable for on-line reconstruction on a MIMD system such as the Cray T3E. Lastly, we analyze the performance of this algorithm on a cluster of workstations
Dynamic load balancing method on a heterogeneous cluster of workstations
No full textThe efficient usage of workstations clusters depends first of all on the distribution of the workload. The following paper introduces a method to obtain efficient load balancing for data parallel applications through dynamic data assignment and a simple priority mechanism, on a heterogeneous cluster of workstations, assuming no prior knowledge about the workload. This model improves the performance of load balancing methods in which one or more control processes remain idle for an extended period of time. In order to investigate the performance of this method we take into consideration a problem of 3D image reconstruction that arises from events detected by a data acquisition system. Studies of our load balancing model are performed under slight and heavy load condition. Experimental results demonstrate that this model yields a substantial load balance, even more if workstations are heavily loaded, from exploiting the idle time of one control process. In addition, this strategy reduces the overhead due to communication so that it could be successfully employed in other dynamic balancing approaches
Acoustic study of different sceneries at the São Carlos national theatre of Lisbon
Full text linkThe wide variety of Opera taking place inside the São Carlos theatre of Lisbon suggested the authors to study the acoustic characteristics of three specific scenarios, which are given by the empty stage and by including the sceneries of Traviata and Italiana in Algeri. The florid artistical venues occurring throughout the centuries make this building an important icon for the capital city of Portugal. As such, an acoustic survey was carried out in order to define the acoustic parameters of this historical building and a numerical digital model was realized and validated by simulating three selected scenarios, whose results have been analysed and commented
Acoustic study of the Roman theatre of Pompeii: Comparison between existing condition and future installation of two parametric acoustic shellsa)
No full text: Roman theatres have always been the subject of research that takes into account not only acoustics, but also archaeological and architectural aspects. It is difficult to draw the boundary line between these disciplines since the interrelation between the different types of expertise is necessary to allow a good production of contemporary architecture in a specific context, such as a Roman theatre. This paper deals with the acoustic analysis of three specific scenarios in the context of the Roman theatre of Pompeii. The reconstruction of the original form, which represents the first scenario, is based on the recent archaeological findings of the ancient city, which was buried for almost two millennia after the eruption of the volcano Vesuvius. The second scenario envisions a future acoustic shell in the form of a mushroom, where the ceiling is the continuation of the vertical surface. The third scenario consists of a parametric design of a shell, representing a modern style velarium; as the curve creates focusing effects, the addition of reflective panels directs the sound evenly to the audience. These latest two architectural designs are intended to make the archaeological site of Pompeii suitable for live concerts and contemporary venues. The digital model representing the current conditions was calibrated with the measured values; the calibrated model was used to study the design of two parametric shell options, proposed as alternatives to provide good acoustics to the audience. The simulated results indicate that the main acoustic parameters are closer to or within the optimal values, resulting in a significant improvement in the acoustic performance of the space
Historically informed digital reconstruction of the Roman theatre of Verona. Unveiling the acoustics of the original shape
Full text linkThe Roman theatre of Verona is one of the most beautiful open-air theatres, still in operation by keeping the artistic programs throughout the winter and summer seasons. Inaugurated during the 1st century BCE, the theatre fell in disuse caused by natural (e.g. fire, earthquake, flooding) and human (e.g. barbaric devastations, private properties) destructions. During the following centuries, many iconographies and drawings interpretations have been made in form of sketches by painters and architects (Caroto, Palladio, Guillaume), other than amateurs (Monga, Pinali) of the arts. Only recent excavations undertaken during the 20th century allowed a faithful reconstruction of the theatre owed to the critical and archaeological approach kept by scholars (i.e. Franzoni, Bolla) who compared the historical documents with the discoveries conveyed on site. On this basis, acoustics measurements have been undertaken in order to photograph the existing conditions of the incomplete ima cavea, which is what has been left by the original monument. The first digital model has been realized in order to calibrate the absorbing coefficients of the applied materials with the results obtained by the survey. Additionally, another 3D digital reconstruction has been realized, and used for the performance of acoustic simulations that allow to restoring the listening environment inside the theatre at its primordial shape. A comparison between the existing and the original volume size highlights the difference of the acoustic parameters, indicating that better listening conditions would be if attending a live performance during the ages of the Roman Empire
Pacchi, pacchetti e pacchettini. La formazione alla rianimazione di base ed avanzata negli adulti. Analisi di alcune offerte formative
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