1,721,093 research outputs found
Genitori in divenire: affiancare la crescita dei bambini e delle bambine
No full textViviamo un momento di passaggio nell’educazione dei bambini e delle bambine: la rapidità dei cambiamenti a tutti i livelli della società non ha avuto pari in alcun altro momento della storia dell’umanità, i modelli tradizionali di famiglia si vanno aprendo e diversificando in nuove forme, i flussi di persone da un capo all’altro del mondo assumono dimensioni mai viste in precedenza, i sistemi di comunicazione aumentano le possibilità di scambio e le nuove tecnologie offrono potenzialità inimmaginabili fino a solo qualche anno fa.
In tanta rapida trasformazione, l’educazione fa fatica ad appellarsi ai tradizionali modelli di interazione tra genitori e figli. La normale conseguenza è un certo disorientamento degli adulti nel rapportarsi con i bambini in modi efficaci e funzionali a far crescere le nuove generazioni. L’educazione è sospesa tra un non più e un non ancora, rendendo difficile alle madri e ai padri trovare esempi stabili a cui riferirsi e di conseguenza spesso inducendo un ondeggiamento tra modalità differenti, talvolta trasportati da mode del momento che spesso offrono proposte contraddittorie e prive di fondamento.
Questo libro è perciò rivolto a tutti quanti si occupano di educazione, genitori e educatori, intendendo costruire ponti sia tra le più aggiornate teorie scientifiche che riguardano lo sviluppo nei primi anni di vita e il loro agire quotidiano con i bambini, sia con alcuni prodotti culturali come giochi e filastrocche appartenenti alle precedenti generazioni. In questa saldatura intendiamo offrire una riflessione sui principi ai quali attenersi, per riportare l'educazione al ruolo di guida e di orientamento che le compete nei confronti dei più piccoli
Placement of Chains of Real-Time Tasks on Heterogeneous Platforms under EDF Scheduling
Full text linkDetecting Adversarial Examples by Input Transformations, Defense Perturbations, and Voting
No full textOver the past few years, convolutional neural networks (CNNs) have proved to reach superhuman performance in visual recognition tasks. However, CNNs can easily be fooled by adversarial examples (AEs), i.e., maliciously crafted images that force the networks to predict an incorrect output while being extremely similar to those for which a correct output is predicted. Regular AEs are not robust to input image transformations, which can then be used to detect whether an AE is presented to the network. Nevertheless, it is still possible to generate AEs that are robust to such transformations. This article extensively explores the detection of AEs via image transformations and proposes a novel methodology, called defense perturbation, to detect robust AEs with the same input transformations the AEs are robust to. Such a defense perturbation is shown to be an effective counter-measure to robust AEs. Furthermore, multinetwork AEs are introduced. This kind of AEs can be used to simultaneously fool multiple networks, which is critical in systems that use network redundancy, such as those based on architectures with majority voting over multiple CNNs. An extensive set of experiments based on state-of-the-art CNNs trained on the Imagenet dataset is finally reported
Hierarchical scheduling of real-time tasks over Linux-based virtual machines
No full textVirtualization has made feasible the full isolation of virtual machines (VMs) among each other. When applications running within VMs have real-time constraints, threads implementing the virtual cores must be scheduled in a predictable manner over the physical cores. In this paper, we propose a possible implementation of such a predictable VM scheduling based on Linux and kvm (a hosted hypervisor). The proposed implementation is based on vanilla Linux kernels and standard qemu/kvm, and does not require to apply any patch or to use custom software. We also show that previous work makes some assumptions that are unrealistic in practical situations. Motivated by these considerations, we finally propose a principled methodology to practically implement hierarchical scheduling with Linux. Finally, an extensive set of experiments based on Linux and kvm illustrates how the VMs and host scheduler can be set-up to match theoretical results with experiments
Handling Transients of Dynamic Real-Time Workload Under EDF Scheduling
No full textReal-time dynamic workload consists of tasks that can arbitrarily join and leave the system at run-time. To avoid incurring deadline misses, tasks that request to join the system must pass an admission test, which has to cope with potential scheduling transients originated by the residual effect of the tasks that previously left the system. This phenomenon may require some tasks to suffer an admission delay before being accepted for execution. This paper focuses on uniprocessor earliest-deadline first (EDF) scheduling with constrained deadlines and explicitly considers methods for handling scheduling transients in the presence of dynamic real-time workload. A generalized analysis framework is first presented to overcome several limitations of the existing approaches (including the support for overlapping transients), and is then used to derive methods for computing bounds on the admission delays incurred by tasks. Building on such results, an on-line protocol is proposed to handle the admission control of dynamic workload, which also comes with a variant that can execute in polynomial time to favor its practical application. Furthermore, the paper shows how the presented analysis can be used off-line for analyzing mode-changes among static task sets. Experimental results are finally presented to evaluate the proposed algorithms
The SRP Resource Sharing Protocol for Self-Suspending Tasks
No full textMotivated by the increasingly wide adoption of realtime workload with self-suspending behaviors, and the relevance of mechanisms to handle mutually-exclusive shared resources, this paper takes a new look at locking protocols for self-suspending tasks under uniprocessor fixed-priority scheduling. Pitfalls when integrating the widely-adopted Stack Resource Policy (SRP) with self-suspending tasks are firstly illustrated, and then a new finegrained SRP analysis is presented. Next, a new locking protocol, named SRP-SS, is proposed to overcome the limitations of the original SRP. The SRP-SS is a generalization of the SRP to cope with the specificities of self-suspending tasks. It therefore reduces to the SRP under some configurations and hence theoretically dominates the SRP. It also ensures backward compatibility for applications developed specifically for the SRP. The SRP-SS comes with its own schedulability analysis and configuration algorithm. The performances of the SRP and SRP-SS are finally studied by means of large-scale schedulability experiments
Task Splitting and Load Balancing of Dynamic Real-Time Workloads for Semi-Partitioned EDF
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