1435 research outputs found
Sort by
Tutela della salute nelle operazioni di montaggio
No full textRIASSUNTO
Questo articolo descrive il metodo per la determinazione del numero di postazioni necessarie per la linea di montaggio del nuovo motore Piaggio M648 e lo studio della cadenza di produzione: viene proposto un confronto fra diverse soluzioni fattibili.
Viene inoltre descritto il metodo Niosh applicato alle postazioni della linea di montaggio analizzata. Tale metodo consente di valutare il rischio connesso alle operazioni di movimentazione manuale di carichi, sulla base del calcolo di un indice di sollevamento.
SUMMARY
This work deals with the calculation of the number of stations needed on the assembly line, the production rate comparing between different feasible solutions for the new Piaggio M648 engine.
The NIOSH method is also describe for the application to the workstations of the assembly line analyzed. This method allows assessing the risks associated with manual handling of loads, based on the calculation of an index lifting
An implicit multishift -algorithm for Hermitian plus low rank matrices
No full textHermitian plus possibly non-Hermitian low rank matrices can be efficiently reduced into Hessenberg form. The resulting Hessenberg matrix can still be written as the sum of a Hermitian plus low rank matrix. In this paper we develop a new implicit multishift -algorithm for Hessenberg matrices, which are the sum of a Hermitian plus a possibly non-Hermitian low rank correction.The proposed algorithm exploits both the symmetry and low rank structure to obtain a -step involving only \mO{n} floating point operations instead of the standard \mO{n^2} operations needed for performing a -step on a Hessenberg matrix. The algorithm is based on a suitable\mO{n} representation of the Hessenberg matrix. The low rank parts present in both the Hermitian and low rank part of the sum are compactly stored by a sequence of Givens transformations and few vectors.Due to the new representation, we cannot apply classical deflation techniques for Hessenberg matrices. A new, efficient technique is developed to overcome this problem.Some numerical experiments based on matrices arising in applications are performed.The experiments illustrate effectiveness and accuracy of both the -algorithm and the newly developed deflation technique. <br /
Porting Decision Tree Algorithms to Multicore using FastFlow
No full textThe whole computer hardware industry embraced multicores. For these machines, the extreme optimisation of sequential algorithms is no longer sufficient to squeeze the real machine power, which can be only exploited via thread-level parallelism. Decision tree algorithms exhibit natural concurrency that makes them suitable to be parallelised. This paper presents an approach for easy-yet-efficient porting of an implementation of the C4.5 algorithm on multicores. The
parallel porting requires minimal changes to the original sequential code, and it is able to exploit up to 7X speedup on an Intel dual-quad core machine
Expansion of matter waves in static and driven periodic potentials
No full textWe study the non-equilibrium dynamics of cold atoms held in an optical
lattice potential. The expansion of an initially confined atom cloud occurs in
two phases: an initial quadratic expansion followed by a ballistic behaviour at
long times. Accounting for this gives a good description of recent experimental
results, and provides a robust method to extract the effective intersite
tunneling from time-of-flight measurements
Gli stabilimenti termali di Bagni di Lucca : Commissioni di ornato e Deputazione edilizia nella prima metà dell’Ottocento.
Get PDFThe article retraces the foundation first thermal establishments of Lucca constructed under the "Communal Commission of Ornato" and of the "Building Deputation" analyzing the first 19th-century Bylaws in order to investigate the current decline of the establishments
La cronaca, la storia, e la teoria della lotta di classe alla prova dei fatti: Luigi Einaudi e il "controllo operaio"
No full textGli editoriali che Luigi Einaudi pubblica sul «Corriere della Sera» fino al 1924 si dimostrano informa- ti a un’organica concezione della storia che trova compiuta espressione nel volume del 1933 La con- dotta economica e gli effetti sociali della guerra italiana. Affrontando tematiche teoriche (tra le quali quel- la del controllo operaio) e di politica economica (il rapporto tra Stato e mercato, il sistema fiscale), Einaudi offre un’interpretazione oggi considerata classica del drammatico scontro sociale e politico conosciuto dall’Italia dopo la Prima Guerra Mondiale, che portò il Paese sulla soglia della rivoluzio- ne socialista e provocò l’ascesa al potere del fascismo.
Abstract
The columns Luigi Einaudi published in «Corriere della Sera» until 1924 are inspired by an organic conception of history that finds his accomplished formulation in the book La condotta economica e gli effetti sociali della guerra italiana [The Economic Conduct and the Social Effects of Italian War] (1933). Einaudi deals with theoretical issues (among which the workers’ control on production) and with economic policy problems (the relationship between the State and the market, the tax system). His interpretation of the dramatic social clash in Italy after World War i – when the country was almost on the edge of socialism, until Fascism seized the power – has today become classic
Hardness of some optimal oblivious routing generalizations
No full textA generalization of the robust network design problem with oblivious routing is investigated in (Scutella', 2009), where the (uncertain) demands are served through two alternative routing templates. As indicated in that paper, it is an open issue as to whether the proposed problem, called (2-RND), is polynomially solvable or is NP-Hard. In this note we solve the issue by proving that (2-RND), as well as some generalizations, are NP-Hard. The hardness result holds true also when some routing templates are given as input data. This strengthens the results in (Scutella', 2009), where special (2-RND) cases are devised which are tractable from a computational perspective
Introduzione alla System Dynamics
No full textThis Technical Report, written in Italian, represents a short introduction to some basic concepts of System Dynamics. The focus is mainly on Causal Loop diagrams and on Flow diagrams and many examples are given of construction of such diagrams. It also contains a discussion of how differential equation of order higher than the first order can be represented and numerically solved by using Vensim models.Reports of errors and inaccuracies of any kind are appreciated and really welcome.<br /
Safer in the Clouds
No full textWe outline the design of a framework for modelling cloud computing systems.The approach is based on a declarative programming model which takes the form of a lambda-calculus enriched with suitable mechanisms to express and enforce application-level security policies governing usages of resources available in the clouds. We will focus on the server side of cloud systems, by adopting a pro-active approach, where explicit security policies regulate server's behaviour. <br /
An inverse or negative auction
No full textIn this Technical Report we describe a type of auction mechanism where the auctioneer A wants to auction an item among a certain number of bidders of a set B that submit bids in the auction with the aim of not getting that item. Owing to this feature we call this mechanism an inverse or negative auction. The main motivation of this mechanism is that both the bidders and the auctioneer give a negative value to the auctioned item (and so they see it as a bad rather than a good). The mechanism is presented in its basic simple version and with some possible extensions that account for the payment of a fee for not attending the auction, the interactions among the bidders and the presence of other supporting actors