1,721,025 research outputs found
La pseudoartrosi del pilone tibiale.Trattamento con metodica di Ilizarov
Full text linkThe results of the treatment of 18 cases of nonunion of the tibial pylon using the Ilizarov method are presented. The level of the nonunion was divided into A (epiphyseal, 2 cases), B (from 1 to 4 cm from the joint rima, 7 cases), and C (from 4 to 7 cm from the rima, 9 cases). Nonunion was atrophic in 12 cases, hypertrophic in 2, and infected in 4. Bone grafts were applied in 8 atrophic cases, while bone resection with transport or resection-shortening was performed in the 4 cases with infection, or resection-shortening and then lengthening in 2 cases. Consolidation was always achieved. Range of movement was very compromised in 9 cases, of which 5 initially presented with joint fracture, while another 4 had had septic complications after fracture
Mathematical Model for simulation Analysis of a Remotely-Piloted Lighter-than-Air Platform
No full textThis paper is focused on the dynamic modelling of an unconventional remotely-piloted Lighter-Than-Air vehicle, whose mathematical model is based on a 6 degree-of-freedom, 12 states nonlinear system, described by the basic equations of the Newtonian mechanics. Emphasis is placed on those innovative and peculiar aspects of the dynamic modelling, which allow the development of a complete low-cost-high-fidelity Flight Simulator used both for technical and commercial purposes. In particular, the availability of this tool, featuring real time simulations, is essential for the design, test and implementation of the most suitable flight control system, as well as for the pilot training of this innovative airshi
Contributo metodologico alla preventivazione dell’impianto antincendio per edifici industriali.
No full textUn’analisi condotta su un campione significativo di progetti di impianto, e il riscontro della normativa specifica, hanno portato alla definizione dei fattori tecno-strutturali di incidenza
determinante sul costo dell’impiantistica antincendio relativa a fabbricati industriali. In base a voci di costo opportunamente individuate, una procedura analitica ad hoc sviluppata ha quindi
consentito di costruire curve parametriche da cui derivare un’unica formulazione sintetica per la preventivazione di impianti a rete di idranti e impianti a pioggia ad intervento automatico. Il criterio è stato validato confrontando i costi così valutati a preventivo con quelli industrialmente
computati per la messa in opera dei progetti-tipo presi a riferimento
La gestione del livello di buffer per la programmazione operativa in processi a ciclo non definito
Full text linkViene affrontato il problema della programmazione operativa con riferimento a processi produttivi per i quali non riesce possibile disporre fin dall’inizio di tutte le informazioni al riguardo necessarie. In tali processi (a ciclo non definito) le specifiche del prodotto, non determinate a priori, possono anche mutare in corso di lavorazione, ciò che impedisce l’impiego efficace di sistemi tradizionali di planning.
In precedenza, trattando la stessa casistica, si era scelto di utilizzare un modello statistico appositamente sviluppato per determinare la configurazione probabile dei cicli di lavorazione, impiegato per calcolare un valore atteso del grado di utilizzazione delle risorse di produzione ed individuare possibili colli di bottiglia. In questa sede ci proponiamo inoltre di sincronizzare il flusso produttivo agendo sul time buffer posto a protezione della risorsa critica, come sopra individuata. La dimensione ottima del buffer è determinata attraverso il trade-off tra il vantaggio di un’idonea saturazione dell’anzidetta risorsa critica ed il costo alternativo della coda in attesa. Ciò vale a definire efficaci regole di rilascio dei job per le stazioni di lavoro a monte. Il monitoraggio del buffer è necessario inoltre per aggiornare la programmazione al variare delle condizioni operative.
L’efficacia del criterio proposto è stata verificata dagli stessi autori attraverso diretta applicazione presso un’azienda operante nel settore della revisione di motori aeronautici. I risultati ottenuti si sono rivelati più che soddisfacenti in ordine al migliore sfruttamento delle risorse produttive nonché in termini di abbattimento del work in process
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Flight control system rapid prototyping for the remotely-controlled elettra-twin-flyer airship
Full text linkNautilus S.p. A. is a small company investing in the design and development of a low-cost multipurpose multi-mission platform, known as Elettra-Twin-Flyer, which is a very innovative radio-controled airship, equipped with high precision sensors and telecommunication devices. In the prototype phase, Nautilus policy is oriented towards a massive employment of external collaborators to reduce the development costs. The crucial problem of this kind of management is the harmonious integration of all the teams involved on the project. This paper describes the integration process of the PC-104 on-board computer with the avionic devices, which are electronic systems characterized by complex communication protocols. Attention is focused on the testing, verification, validation and final translation of the embedded control software into the on-board computer, through techniques derived from the automatic code generation, such as Rapid Prototyping and Hardware-In-the-Loop. Copyright © 2006 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved
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