1,355,963 research outputs found
Valutazione della topografia superficiale di impianti macchinati ed impianti sabbiati e mordenzati.
No full textValutazione della topografia superficiale di impianti macchinati e sabbiati e mordenzati / Atomic force microscope for implant surface study
No full textScopo del lavoro Il presente studio analizza mediante l’uso di un microscopio a forza atomica (AFM) la ruvidità di superficie di impianti macchinati messi a confronto con impianti sabbiati e mordenzati per meglio comprendere le reali condizioni fisiche osservabili sulla superficie e che influenzano l’osteointegrazione. Materiali e metodi L’AFM ricostruisce l’immagine della superficie di un campione attraverso una scansione per punti di un raggi laser consentendo di ottenere una immagine tridimensionale della superficie analizzata. Sono state realizzate scansioni a 3, 30 e 60 mm; il tipo di matrice utilizzata è stato di 256x256 per un totale di 65.536 scansioni. Risultati e conclusioni La ruvidità media di superficie risulta apprezzabilmente differente tra le due superfici implantari analizzate a netto vantaggio degli impianti sabbiati e mordenzati, ma sono necessari ulteriori studi per definire le proprietà biologiche e biomeccaniche ideali.Aim In this study surface roughness of machined implants is compared to sandblasted-acid etched implants by atomic force microscope analysis in order to understand the real physical conditions that is possible to observe on surface and that influence osseointegration. AFM reconstructs the surface image of a sample by scanning per point through laser beam and achieving a three-dimensional image. A total of 3, 30 and 60 mm scans were made and a 256x256 matrix was used for a totals of 65536 scans. Results and conclusions Mean surface roughness is different between the two analyzed surfaces is in favour of sandblasted-acid etched implants. However further studies are needed to define ideal biological and biomechanical properties
Latest results from Double Chooz
No full textDouble Chooz is a short-baseline neutrino disappearance experiment. It detects ν̄e produced in the power plant of Chooz, France, where is located. The main goal of the experiment is the measurement of θ13 mixing angle and in 2011 for the first time the experiment observed an indication for a non zero value of such an oscillation parameter. The mixing angle was successively measured using only the far detector finding the best fit value of sin2(2θ13) = 0.090−0.029+0.032. The near detector is under construction and will start data taking by the middle of 2014 allowing the reduction of the systematic errors. In this paper I make a review of the Double Chooz experiment, focusing in particular on the latest results of the measurement of the mixing angle θ13 relying on the neutron absorption on Gadolinium. I also present results proving the capability of Double Chooz to identify the ortho-positronium. This has been done in an event-by-event basis for the first time in a large liquid scintillator experiments, and can be an additional handle for the electron/positron discrimination in future detectors based on such technology
Valutazione della topografia superficiale di impianti macchinati e sabbiati e mordenzati
No full textNon previst
Energy Converter with Inside Two, Three, and Five Connected H2/Air Swirling Combustor Chambers: Solar and Combustion Mode Investigations
No full textThis work reports the performance of an energy converter characterized by an emitting parallelepiped element with inside two, three, or five swirling connected combustion chambers. In particular, the idea is to adopt the heat released by H2/air combustion, occurring in the connected swirling chambers, to heat up the emitting surfaces of the thermally-conductive emitting parallelepiped brick. The final goal consists in obtaining the highest emitting surface temperature and the highest power delivered to the ambient environment, with the simultaneous fulfillment of four design constraints: dimension of the emitting surface fixed to 30 × 30 mm2, solar mode thermal efficiency greater than 20%, emitting surface peak temperature T > 1000 K, and its relative ∆T < 100 K in the combustion mode operation. The connected swirling meso-combustion chambers, inside the converter, differ only in their diameters. Combustion simulations are carried out adopting 500 W of injected chemical power, stoichiometric conditions, and detailed chemistry. All provide high chemical efficiency, η > 99.9%, and high peak temperature, but the emitting surface ∆T is strongly sensitive to the geometrical configuration. The present work is related to the “EU-FP7-HRC-Power” project, aiming at developing micro-meso hybrid sources of power, compatible with a thermal/electrical conversion by thermo-photovoltaic cells
Design Challenges in the Development of a Hydrogen-Fueled Micro Gas Turbine Unit for Energy Generation †
No full textEnvironmental and social governance targets, as well as the global transition to cleaner renewable energy sources, push for advancements in hydrogen-based solutions for energy generators due to their high energy per unit mass (energy density) and lightweight nature. Hydrogen’s energy density and lightweight nature allow it to provide an extended range of uses without adding significant weight, potentially revolutionizing many applications. Moreover, a variety of sources, including renewable energy, can produce hydrogen, making it a potentially more sustainable option for energy storage despite its main limitations in production and transportation costs. In this framework we are proposing an innovative energy generator that might merge the benefits of batteries and hydrogen. The energy generator is based on a worldwide patented solution introduced by MIEEG s.r.l. regarding the shape of the chambers. This innovative solution can be used to design a 100% H2-fed microturbine with a high power/weight/volume ratio that works as a range extender of battery packs for a comprehensive, high-efficiency hybrid powertrain. In fact, it runs at 100,000 rpm and is designed to deliver about 100 kW in about 15 L of volume and 15 kg of weight (alternator excluded). The system is highly complex due to high firing temperatures, long life requirements, corrosion protection, mechanical and vibrational stresses, sealing, couplings, bearings, and the realization of tiny blades. This paper analyzes the main design challenges to face in the development of such complex generators, focusing on the hot gas path components, which are the most critical part of gas turbines. The contribution of additive manufacturing techniques, the adoption of special materials, and coatings have been evaluated for system improvement
LES Simulation of CH4/air Microcombustor with Detailed Chemistry”, Combustion Science and Technology
No full textThe authors compare numerical simulations and experiments carried out on a swirling
methane/air cylindrical microcombustor with diameter and height 0.006m and 0.009 m,
respectively. They extend previous work, using LES and Flamelet methodology; here the
EDC finite rate model and the GRIMech 1.2 (32 species and 177 reactions) mechanism
are used. Gas temperature at the exhaust section, together with CH chemiluminescence
measurements and combustion efficiency analysis are provided. Results reproduce exhaust
temperature and combustion efficiency measurements, generally differing by less than 10%.
This work should be seen as an advance in the understanding of how to design future microcombustors,
presently under rapid development in particular for propulsion (e.g., for
UAVs) and microelectrical power generators
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