257 research outputs found
New Area-Time Lower Bounds for the Multidimensional DFT
No full textArea-time lower bounds are derived for the VLSI computation of the (n1 x n2 x ... nd)-point multidimensional DFT (MDDFT) over different types of rings and different types of input/output protocols. First, an AT^2 = Ω((N log|R|)^2) bound is obtained for any finite ring R, where N = n1 x n2 x ... x nd, for any word-local protocol. The bound was previously known for the special case when R = Z_M, the ring of integers modulo M.
Second, an AT^2 = Ω((Nb)^2) word-local bound is derived when R is the complex field, the components of the input are fixed-point numbers of b bits, and the precision of the output components guarantees that the resulting approximate transform is injective. No area-time lower bound was previously known for the DFT over the complex field.
Third, an AT^2 = Ω((N log|R|)^2) bound is derived when R = GF(p^m) is a finite field of polynomials of degree m with coefficients in Z_p, for certain classes of non word-local protocols. This is the first area-time lower bound derived for the DFT with I/O protocols that are not word-local
Fantozzi. L'eterno ritorno
No full textL'ipotesi alla base di questo videosaggio è che Paolo Villaggio sia stato gradualmente "fagocitato" dal suo personaggio più famoso, quel ragionier Ugo Fantozzi di cui l'attore, al debutto televisivo, raccontava in terza persona le "tragiche" domeniche impiegatizie.
Passando al grande schermo, Villaggio sceglie di vestire in prima persona i panni del ragioniere. Ma lo sfruttamento intensivo cui egli si sottopone, unito al rapido esaurirsi della sua vena creativa, lo costringono, film dopo film, a una ripetizione estenuante delle medesime gag. E mentre Fantozzi perde via via le proprie caratteristiche satiriche per trasformarsi in una figura più infantile e cartoonesca, il corpo attoriale di Villaggio, al contrario, si fa visibilmente più vecchio e affaticato, incapace di reggere fisicamente il ruolo.
Seguendo le trasformazioni del personaggio e del suo creatore-interprete, il lavoro intende proporre un percorso complessivo (ma tutt'altro che definitivo) all'interno della saga fantozziana. Un saggio audiovisivo costruito come una sorta di polittico, nel quale ciascun capitolo può essere considerato in modo autonomo e, al tempo stesso, come tappa di un discorso più ampio intorno a una delle figure più popolari del cinema italiano del secondo dopoguerra.The idea behind this videoessay is that actor Paolo Villaggio has been gradually "swallowed" by his most famous character, the humble accountant Ugo Fantozzi, of which Villaggio, in his television debut, told the misadventures using third person narration.
In 1975, when Fantozzi became a movie character, Villaggio decided to assume in first person the main role. But the intensive exploitation of the character, coupled with the rapid exhaustion of his creative vein, have forced the author-actor to a draining repetition of the same gags. While Fantozzi gradually loses its satirical characteristics to become a more childish and cartoonesque figure, Villaggio's body, on the contrary, becomes visibly older and weaker, physically unable to support the role.
Following the transformations of the character and its creator-interpreter, our work intends to propose a journey through the Fantozzi's saga. An audiovisual essay built as a sort of medieval polyptych, in which each chapter can be considered autonomously and, at the same time, as a stage in a wider discourse around one of the most popular figures of postwar Italian cinema
Fantozzi. L'eterno ritorno
No full textThe idea behind this videoessay is that actor Paolo Villaggio has been gradually "swallowed" by his most famous character, the humble accountant Ugo Fantozzi, of which Villaggio, in his television debut, told the misadventures using third person narration.In 1975, when Fantozzi became a movie character, Villaggio decided to assume in first person the main role. But the intensive exploitation of the character, coupled with the rapid exhaustion of his creative vein, have forced the author-actor to a draining repetition of the same gags. While Fantozzi gradually loses its satirical characteristics to become a more childish and cartoonesque figure, Villaggio's body, on the contrary, becomes visibly older and weaker, physically unable to support the role.Following the transformations of the character and its creator-interpreter, our work intends to propose a journey through the Fantozzi's saga. An audiovisual essay built as a sort of medieval polyptych, in which each chapter can be considered autonomously and, at the same time, as a stage in a wider discourse around one of the most popular figures of postwar Italian cinema
Exploring the Potential of Ensembles of Deep Learning Networks for Image Segmentation
No full textTo identify objects in images, a complex set of skills is needed that includes understanding the context and being able to determine the borders of objects. In computer vision, this task is known as semantic segmentation and it involves categorizing each pixel in an image. It is crucial in many real-world situations: for autonomous vehicles, it enables the identification of objects in the surrounding area; in medical diagnosis, it enhances the ability to detect dangerous pathologies early, thereby reducing the risk of serious consequences. In this study, we compare the performance of various ensembles of convolutional and transformer neural networks. Ensembles can be created, e.g., by varying the loss function, the data augmentation method, or the learning rate strategy. Our proposed ensemble, which uses a simple averaging rule, demonstrates exceptional performance across multiple datasets. Notably, compared to prior state-of-the-art methods, our ensemble consistently shows improvements in the well-studied polyp segmentation problem. This problem involves the precise delineation and identification of polyps within medical images, and our approach showcases noteworthy advancements in this domain, obtaining an average Dice of 0.887, which outperforms the current SOTA with an average Dice of 0.885
Studio di un prototipo di serra bioclimatica per l’efficienza e la sostenibilità energetica
No full textLa ricerca muove dalle più recenti evoluzioni normative in tema di risparmio energetico e di più moderni sviluppi della tecnologia relativa alla progettazione e realizzazione di elementi vetrati a controllo solare ad alte prestazioni energetiche per dimostrare l’efficacia dei sistemi a serra nel migliorare i livelli di comfort interno riducendo il consumo di energia non rinnovabile per il condizionamento degli ambienti interni.
La ricerca si propone l’obiettivo di verificare il contributo al comfort microclimatico offerto dalla serra solare da realizzare al piano primo dell’edificio ENEA CASACCIA.
L’analisi è stata condotta utilizzando il software opensource EnergyPlus per la simulazione termica e la diagnosi energetica in regime dinamico degli edifici, sulla base del modello geometrico 3D costruito attraverso il software GoogleSketchUp.
La simulazione ha consentito di valutare l’incremento di energia gratuita proveniente da irraggiamento solare attraverso le superfici vetrate dovuto alla realizzazione della serra e il conseguente innalzamento della temperatura operativa dell’ambiente interno durante la stagione invernale.
La simulazione è stata condotta sia in situazione standard (assenza di persone e apparecchiature) sia nella situazione reale di operatività dell’edificio, con la presenza di carichi interni associati alla funzione ufficio dell’ambiente.
A corredo dell’analisi principale, sono state condotte simulazioni variando la configurazione geometrica dell’ambiente oggetto di analisi (rimuovendo la parete di separazione tra la serra e l’ambiente interno) e modificando le caratteristiche degli elementi vetrati della serra nell’ottica di una ottimizzazione delle prestazioni anche nel periodo estivo.
Gli andamenti orari della T° hanno dimostrato un innalzamento medio della T° operativa, durante la stagione invernale di circa 0.59 °C
A General PRAM Simulation for Clustered Machines
No full textWe present a general deterministic scheme to implement a shared memory abstraction on any distributed-memory machine which exhibits a clustered structure. More specifically, we develop a memory distribution strategy and an access protocol for the Decomposable BSP (D-BSP), a generic machine model whose bandwidth/latency parameters can be instantiated to closely reflect the characteristics of machines that admit a hierarchical decomposition into independent clusters. Our scheme achieves provably optimal slowdown for those machines where delays due to latency dominate over those due to bandwidth limitations. For machines where this is not the case, the slowdown is a mere logarithmic factor away from the natural bandwidth-based lower bound
Translating Submachine Locality into Locality of Reference
No full textThe design of algorithms exhibiting a high degree of temporal and spatial locality of reference is crucial to attain good performance on current and foreseeable computing systems featuring ever deeper memory hierarchies. Previous work has demonstrated that task parallelism can be efficiently transformed into locality of reference in two-level hierarchies. Recently, we moved a step forward and showed how the more structured type of parallelism exposed by submachine locality can be efficiently turned into temporal locality on arbitrarily deep hierarchies. In this work, we complete and extend the above result by encompassing also spatial locality. Specifically, we present a scheme to simulate parallel algorithms designed for the Decomposable BSP (a BSP variant which captures submachine locality) on the Hierarchical Memory Model with Block Transfer. The simulation yields good hierarchy-conscious sequential algorithms from parallel ones, and provides evidence of the strict relation between submachine locality in parallel computation and locality of reference (both temporal and spatial) in the hierarchical memory setting
Factorized Sparse Approximate Inverses on GPUs
No full textGPUs exhibit significantly higher peak performance than conventional CPUs. However, due to their programming model and microarchitecture, only highly parallel algorithms can exploit their full potential. In this context, the FSAI preconditioner may represent – with its inherent parallelism – an optimal candidate for the conjugate gradient-like solution of sparse linear systems. While its application to a vector involves only matrix-vector products, a GPU-based implementation requires a nontrivial recasting of multiple computational steps
A GPU implementation of the Factored Sparse Approximate Inverse preconditioner for the iterative solution of SPD linear systems
No full textSeamless Integration of Parallelism and Memory Hierarchy
No full textWe prove an analogue of Brent's lemma for BSP-like parallel machines featuring a hierarchical structure for both the interconnection and the memory. Specifically, for these machines we present a uniform scheme to simulate any computation designed for v processors on a v'-processor configuration with v' ≤ v and the same overall memory size. For a wide class of computations the simulation exhibits optimal O (v/v') slowdown. The simulation strategy aims at translating communication locality into temporal locality. As an important special case (v' = 1), our simulation can be employed to obtain efficient hierarchy-conscious sequential algorithms from efficient fine-grained ones
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