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Influence of solutioning on microstructure and hardness of hot isostatically pressed Astroloy
No full textThe influence of solutioning treatment on Astroloy fabricated via Hot Isostatic Pressing has been investigated. Both sub- and super-solvus solutioning treatments were performed, gradually increasing the test temperature from 1115 to 1200 °C in order to cross the ɣ′ solvus. The effects of the solutioning temperature and of the following cooling step were studied in terms of amount of reinforcing precipitate ɣ′, of γ-grain coarsening and of alloy hardness. Grain boundaries morphology was observed to be clearly modified by the solutioning conditions moving from the "smooth" to the "serrated" type. It was also possible to draw a clear correlation between cooling rates and Astroloy hardness
Investigations on the use of thin adhesion layers in top-illumination AFM tip-enhanced Raman spectroscopy
No full textTip-enhanced Raman spectroscopy (TERS) is known to work in different configurations, modes and combinations of tip materials and excitation laser wavelengths. Although very promising, atomic force microscopy (AFM)-based TERS is not yet at the level of other competitive techniques like scanning tunneling microscopy or shear force based TERS, for instance, in terms of imaging resolution or tips control and usability. However, AFM TERS has several structural advantages over others, such as the versatility in the characterization of both electrical conducting and non-conducting samples or the abundance of collateral information provided, which make it ideal for future routine analyses and market applications. One of the main issues in AFM TERS concerns the fabrication processes of tips, which generally make use of commercial silicon cantilevers as starting supports for the plasmonic materials, like silver or gold, required in TERS. These can be chemically deposited or vacuum evaporated directly on the pristine silicon tips, but they can easily peel off due to dynamics of measurements and mechanical interaction with the sample surface. In particular, gold has a bad adhesion with silicon oxide surfaces, and commercial tips have a native oxide layer which is difficult to remove, without dulling the tip apex, with other than wet chemical etching methods.In the present contribution, we explore with TERS, in the top-illumination geometry, the possibility to use thin adhesion layers to avoid metal detachment without severely affecting, like in other plasmonic applications, the sensing performances
Consumo, trasformazione e rigenerazione del suolo nella prospettiva del metabolismo urbano
No full textSurface tension-driven self-alignment of double-surface radio-frequency integrated circuits for a low cost and high throughput assembly process of passive RFID tags
No full textThermo-Piezo-Elastic Analysis of Complex Structures Using a Node Dependent Kinematic One-Dimensional Model
No full textAerospace structures can be subject to complex stress fields that are originated by different external loads. The classical structural analysis considers the mechanical loads and aims to evaluate the stress fields due to these external forces. When complex structures are subject to a strong temperature variation they may present a large deformation that may produce complex stress fields. The evaluation of these deformations is mandatory in order to avoid the failure of the structure, that is, a thermo-mechanical analysis should be performed. Moreover, the use of advanced materials, such as piezo-electric materials, allows the displacement filed to be evaluated, if they are used as sensors, or, the deformations to be reduced, if they are used as actuators. Multi-field analyses are mandatory in these cases and accurate thermo-piezo-elastic models must be used to predict the response of the structure. Complex stress fields cannot be investigated using classical structural models, beams and plates, because their kinematic assumptions, e.g. rigid cross-section for the beam of constant thickness for the plates. The use of three-dimensional models may achieve accurate results but it may require a huge computational cost. The present work extends the use of a refined node-dependent kinematic one-dimensional model to the thermo-piezo-mechanical analysis. Node-dependent kinematic one-dimensional models allow refined kinematic models to be used only in the area of the structure where complex phenomena are expected, that is, these models are able to reduce the computational cost preserving the accuracy of the results only where is required. The fully coupled thermo-piezo-elastic model has been derived in the framework of the Carrera unified Formulation that allows the structural matrices to be written in a general and compact form. Static and dynamic analysis have been performed in order to assess the present model. The results have been compared with those from literature and with those from refined models with a constant kinematic. The outcome of this research show that node-dependent kinematic one-dimensional models may preserve the accuracy of a three-dimensional solution with a lower computational cost if compared with the refined models with a constant kinematic
MATISSE: A Low power front-end electronics for MAPS characterization
No full textIn recent years Monolithic Active Pixel Sensors are becoming increasingly attractive for High Energy Physics experiments. Several R&D activities are ongoing worldwide to improve the per- formance of conventional monolithic pixels in terms of speed and radiation tolerance. These improvements come both from the optimization of the substrate material and the design of the front-end electronics. In the framework of an R&D project on CMOS monolithic sensors, a versatile readout electronics has been developed. The purpose is to have a flexible system to test different sensor geometries and substrates, allowing a detailed analog characterization and the study of effects that arise in complex mixed signal chips such as digital induced noise. The ASIC prototype, MATISSE, has been fabricated in 0.11 μm CMOS technology with a die area of 2×2 mm2 and a low voltage operation of 1.2 V. Hereafter, the front-end electronics are described and the first results from the characterization are reported
Disasters and earthquakes in Western Liguria. The "earthquake of Diano Marina, 1887"
No full textLiguria and in particular the Western Liguria has been repeatedly, over the centuries, upset by earthquakes that have heavily influenced the life of the inhabitants, on building, on landscape and urban planning. A violent earthquake shook the Western Liguria the Christmas Day 1222, this catastrophic event remain limited information because of past centuries. Liguria Western trembled at length between March and July of 1564, the chronicles tell that the people slept outdoors for months because of the repetition of earthquake. In the nineteenth century have been registered numerous earthquakes since 1802, the most disastrous of 23 February 1887. To better understand the building codes it is essential to analyze the damage caused by the earthquake that occurred in Liguria during the course of the nineteenth century. The integration of written documentary sources and graphics, drawings and early photographs allow a complete picture of the damage and reconstruction interventions. The integrated interpretation allows us to understand the transformations of Liguria, the drafting of zoning and building regulations. The research in the future aims to analyze and integrate the documentary sources with the reading of the territory and being enshrined with the rules of the redevelopment plans and master plans up to current regulations through the analysis of data and sources using geographic information systems and multirelational database
