117,507 research outputs found
Fatigue design of hydraulic cylinder made of composite material
No full textThe object of this research is to demonstrate that the composite materials can replace the classic ones (for example steel) used to produce the structural mechanical components. The focus of this study is a double effect hydraulic cylinder installed on the excavator. Its design has been addressed using three different materials: the composite one made of carbon fiber, the classic structural steel and the aluminium alloy. The analytical sizing was verified through the FEM analysis. The next phase considers the fatigue phenomena due to pressure variation in time in the hydraulic cylinder. The results show that the hydraulic cylinder made of composite material has a very similar performance, in terms of the safety factor, to the one made of structural steel and that the weight reduction is about 87% passing from 2286 N to 314 N
The multi-parametric weight optimization of a hydraulic actuator
No full textThis research was derived from the experimental observation that hydraulic actuators are positioned on machines that are subjected to movements and whose dynamic actions, the accelerations, are very high; it is acceptable to think of an actuator for an anthropomorphic robot. From this point of view, the weight of the actuator plays a fundamental role in the performance of the machine. In order to face this problem, a real hydraulic cylinder has been designed (for use on an earth moving machine) both analytically (adopting the theories of continuous mechanics) and numerically through finite element analysis. The results obtained were then generalized by determining functions that in relation to specific values of the variables, such as working pressure, allow one to determine the minimum weight of the component and its geometric configuration. The functions also made it possible to identify the most significant contributions to the overall weight of the component and therefore the elements on which to focus the subsequent lightening process. In particular, the greatest contribution is made by obtaining relations that are completely general and therefore adaptable to different case studies
Valutazione delle caratteristiche qualitative e ambientali
No full textL’ambiente, secondo l’Organizzazione Mondiale della Sanità (OMS), può essere definito come un sistema integrato di fattori antropici e fisici, che esercitano un effetto significativo sulla salute della collettività. Tali fattori hanno infatti un ruolo fondamentale ai fini della salute dell’uomo e della relativa percezione di benessere nei confronti dello spazio che ci circonda. In particolare, si può affermare che la qualità dell’ambiente in-door influenza notevolmente il livello qualitativo di benessere fisico, so-ciale e psicologico di ciascun individuo. Secondo tale visione, le strutture Sanitarie in quanto luoghi di lavoro, cura e spesso di sofferenza e disagio richiedono una specifica attenzione progettuale e gestionale al fine di migliorare o alleviare il senso di isolamento e preoccupazione spesso su-scitato dallo stato di malattia.
Per tale motivo nel sistema di ottimizzazione e certificazione ambien-tale e prestazionale delle strutture sanitarie sono state elaborate 4 schede specificatamente orientate alla valutazione di tutti quegli aspetti proget-tuali e tecnologici che concorrono a garantire elevate prestazioni di be-nessere e di qualità percepita.
La condizione di benessere percepito, fondamentale ai fini terapeutici e lavorativi, risulta infatti condizionata da un’attenta programmazione, progettazione, realizzazione e manutenzione dell’opera edilizia
[Cystic adenoid carcinoma of the minor salivary glands; prognostic importance of various histopathologic factors]
No full textUnusual branch of the lingual artery supplies the infrahyoid muscles
No full textInfrahyoid muscles are usually supplied by muscular arteries, originating from the superior and inferior thyroid artery and the internal thoracic artery. In this work, we reported a unilateral anatomical variation of the branching pattern of the lingual artery, which was observed during dissection studies at the University of Brescia. We found an accessory branch arising from the root of the lingual artery that run down medially and supplied the infrahyoid muscles. A similar case has not yet been reported in literature. Considering the current use of the infrahyoid muscles as pedicled myocutaneous flap for reconstructing surgical defects in the head and neck, this vascular variation appears interesting to be reported for appropriate clinical and surgical consideration
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