1435 research outputs found
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The wandering token: Congestion avoidance of a shared resource
No full textIn a distributed system where scalability is an issue, the problem of enforcing mutual exclusion often arises in a soft form: the infrequent failure of the mutual exclusion predicate is tolerated, without compromising the consistent operation of the overall system. For instance this occurs when the operation subject to mutual exclusion requires massive use of a shared resource. We introduce a scalable soft mutual exclusion algorithm, based on previous termtokennext term passing: one distinguished feature of our algorithm is that instead of introducing an overlay topology we adopt a random walk approach. The consistency of our proposal is evaluated by simulation, and we exemplify its use in the coordination of large data transfers in a backbone based network. This algorithm is studied in the frame of the CoreGRID Institute of Grid Information, Resource and Workflow Monitoring Services, in cooperation with the FORTH Institute, in Greece
Lo scheduling di un mix di prodotti: il caso di un'azienda metalmeccanica
No full textRIASSUNTO: Automazione della pianificazione della produzione tramite un software di scheduling: definizioni e applicazione. A partire da una classificazione dell’architettura delle linee produttive, viene proposto un caso applicativo per mostrare le potenzialità degli algoritmi di simulazione delle sequenze di operazioni su un determinato parco macchine. SUMMARY: Production planning automation by a scheduling software. Overview of the architecture of production lines, case study and potential of simulation algorithms for the sequence of operations on a given set of machines
Ispezione di tubofiale tramite visione artificiale
No full textRIASSUNTO: Questo articolo descrive il metodo di controllo di tubofiale presso l’azienda Eli Lilly nella sede italiana di Sesto Fiorentino (FI). Il progetto è stato svolto anche presso la sede francese di Fegershaim (Francia) e in collaborazione con l’Università di Pisa. In particolare, sono state affrontate e risolte varie problematiche legate all’uso della visione artificiale per il controllo di qualità di cartucce di insulina attraverso una macchina ispezionatrice automatica ed una ispezionatrice semiautomatica fornite dalla società Seidenader.
SUMMARY: The scope of this paper is the inspection of cartridges using visual inspection machine. This project has been developed in part in the Sesto Fiorentino branch and in part in the Fegershaim branch of Eli Lilly, in collaboration with Università di Pisa.
The aim of this paper is to describe how the quality control problem for insulin cartridges has been tackled using visual inspection.
The automatic machine and the semiautomatic machine to execute this task has been bought from Seidenader
On some systems controlled by the structure of their memory
No full textSUMMARY We consider an optimal control problem governed by an ODE with memory playing
the role of a control. We show the existence of an optimal solution and derive
some necessary optimality conditions. Some examples are then discussed
Non abelian Bianchi identities, monopoles and gauge invariance
No full textSUMMARY A direct connection is proved between the Non-Abelian Bianchi Identities and
the Abelian Bianchi identities for the 't Hooft tensor in a generic gauge; the
existence of a magnetic current is related to the violation of NABI's. Using
this relation it is shown that not all gauges are equivalent to detect
monopoles on the lattice, that e.g. the Maximal Abelian Gauge is a legitimate
choice while the Landau gauge is not. Nevertheless monopole condensation is
found to be a gauge invariant property
Group Theory of Non-Abelian Vortices
No full textWe investigate the structure of the moduli space of multiple BPS non-Abelian
vortices in U(N) gauge theory with N fundamental Higgs fields, focusing our
attention on the action of the exact global (color-flavor diagonal) SU(N)
symmetry on it. The moduli space of a single non-Abelian vortex, CP(N-1), is
spanned by a vector in the fundamental representation of the global SU(N)
symmetry. The moduli space of winding-number k vortices is instead spanned by
vectors in the direct-product representation: they decompose into the sum of
irreducible representations each of which is associated with a Young tableau
made of k boxes, in a way somewhat similar to the standard group composition
rule of SU(N) multiplets. The K\"ahler potential is exactly determined in each
moduli subspace, corresponding to an irreducible SU(N) orbit of the
highest-weight configuration
Lower Bounds on the Rotation Distance of Binary Trees
No full textThe rotation distance d(S,T) between two binary trees S, T of n vertices is the minimum number of rotations to transform S into T. While it is known that d(S,T) = 11. We are unable to prove the conjecture, but we give here some simple criteria for lower bound evaluation, leading for example to individuate some ``regular'' tree structures for which d(S,T) = 3n/2-O(1), or d(S,T) = 5n/3-O(1)
A unification of unitary similarity transforms to compressed representations
No full textIn this paper a new framework for transforming arbitrary matrices to compressed representations is presented. The framework provides a generic way of transforming a matrix via unitary similarity transformations to e.g.\ Hessenberg, Hessenberg\-/like and combinations of both. The new algorithms are deduced, based on the -factorization of the original matrix. Based on manipulations with Givens transformations, all the algorithms consists of eliminating the correct set of Givens transformations, resulting in a matrix obeying the desired structural constraints. Based on this new reduction procedure we investigate further correspondences such as irreducibility, unicity of the reduction procedure and the link with (rational) Krylov methods. The unitary similarity transform to Hessenberg\-/like form as presented here, differssignificantly from the one presented in earlier work. Not only does it use less Givens transformations to obtain the desired structure, also the convergence to rational Ritz values is not observed in the standard way
Secure token passing at application level
No full textSUMMARY We introduce an application level implementation of a token passing operation. After an introduction that explains the conceptual principles, we describe exhaustively the state machines that implement our solution. The security requirements are carefully considered, since the token is a sensitive resource, but without introducing scalability limit
SULLE TRACCE DEL MA. Riflessioni sulla conservazione dell’architettura in Giappone.
No full textThe paper represents a trip through the world of the art, of the architecture and of the Japanese landscape to the discovery of the values and the methods that are at the base of the maintenance of the patrimonies architectural and historical-artistic