Search results for "Mechanical engineering"
showing 10 items of 4245 documents
Vision metrology and Structure from Motion for archaeological heritage 3D reconstruction: A Case Study of various Roman mosaics
2017
<p class="Abstract">Vision metrology and computer vision can be successfully used for archaeological heritage 3D reconstruction in very high precision 3D measurement projects. Of those archaeological objects requiring very accurate measurements (&lt;1 mm), ancient mosaics comprise some of the most important. The aim of this paper is to assess the photogrammetric/computer vision approach in a vision metrology context as part of a 3D mosaics survey. In order to evaluate the optimal photogrammetric/computer vision workflow in this work, three different surveys were performed on three mosaics of different sizes and locations. Two of these are stored at the <em>Antonino Salinas&l…
Effect of high temperature annealing (T > 1650 °C) on the morphological and electrical properties of p-type implanted 4H-SiC layers
2019
This work reports on the effect of high temperature annealing on the electrical properties of p-type implanted 4H-SiC. Ion implantations of Aluminum (Al) at different energies (30-200 keV) were carried out to achieve 300 nm thick acceptor box profiles with a concentration of about 10(20) at/cm(3). The implanted samples were annealed at high temperatures (1675-1825 degrees C). Morphological analyses of the annealed samples revealed only a slight increase of the surface roughness RMS up to 1775 degrees C, while this increase becomes more significant at 1825 degrees C (RMS = 1.2 nm). Room temperature Hall measurements resulted in a hole concentration in the range 0.65-1.34 x 10(18)/cm(3) and m…
Extent and persistence of soil water repellency induced by pines in different geographic regions
2018
The extent (determined by the repellency indices RI and RIc) and persistence (determined by the water drop penetration time, WDPT) of soil water repellency (SWR) induced by pines were assessed in vastly different geographic regions. The actual SWR characteristics were estimated in situ in clay loam soil at Ciavolo, Italy (CiF), sandy soil at Culbin, United Kingdom (CuF), silty clay soil at Javea, Spain (JaF), and sandy soil at Sekule, Slovakia (SeF). For Culbin soil, the potential SWR characteristics were also determined after oven-drying at 60°C (CuD). For two of the three pine species considered, strong (Pinus pinaster at CiF) and severe (Pinus sylvestris at CuD and SeF) SWR conditions we…
Benchmarking the sustainable manufacturing paradigm via automatic analysis and clustering of scientific literature: A perspective from Italian techno…
2019
Abstract The number of scientific papers in the field of Sustainable Manufacturing (SM) shows a strong growth of interest in this topic in the last 20 years. Despite this huge number of publications, a clear statement of the profound meaning of Sustainable Manufacturing, or at least a strong theoretical support, is still missing. The 6R framework seems to be a first attempt to rationalize this issue, as it is an axiomatic identification of its true nature. Recognizing the pursuing of one or more of the Reduce-Recycle-Reuse-Recover-Redesign-Remanufacture principles allows users to identify if any manufacturing action is in the right direction of sustainability. In the paper, the authors spec…
A Multilayered Plate Theory with Transverse Shear and Normal Warping Functions
2016
A multilayered plate theory which takes into account transverse shear and normal stretching is presented. The theory is based on a seven-unknowns kinematic field with five warping functions. Four warping functions are related to the transverse shear behaviour, the fifth is related to the normal stretching. The warping functions are issued from exact three-dimensional solutions. They are related to the variations of transverse shear and normal stresses computed at specific points for a simply supported bending problem. Reddy, Cho-Parmerter and (a modified version of) Beakou-Touratier theories have been retained for comparisons. Extended versions of these theories, able to manage the normal s…
Radio environment map estimation based on communication cost modeling for heterogeneous networks
2017
Los mapas del entorno radioeléctrico pueden ser una poderosa herramienta para lograr una asignación de recursos eficiente y consciente del contexto en las redes heterogéneas 5G. En este trabajo, consideramos una red heterogénea formada por una red celular tradicional y una red de sensores inalámbricos. El papel de la red de sensores inalámbricos es estimar el mapa del entorno radioeléctrico de la célula utilizando una técnica de interpolación geoestadística denominada Kriging. En un trabajo anterior se propuso un algoritmo de agrupación distribuida de sensores para reducir la complejidad de la estimación. En nuestra contribución, el proceso de formación de clústeres se modifica para incluir…
Distributed radio map reconstruction for 5G automotive
2018
Se espera que los mapas de entorno radio sean una herramienta esencial para la optimización y gestión de recursos del 5G en vehículos. En este trabajo, consideramos el problema de la reconstrucción del mapa de entorno radio utilizando una red de sensores inalámbricos formada por nodos sensores en vehículos, nodos de acceso de una infraestructura de ciudad inteligente, etc. Debido a las limitaciones de recursos en las redes de sensores, es crucial seleccionar un pequeño número de mediciones de los sensores para reconstruir el campo. En este contexto, presentamos un novedoso algoritmo distribuido basado en el método de regresión Kriging para la reconstrucción del mapa de entorno radio en térm…
Stress-strain analysis of specimens subjected to tensile loading during moisture uptake
2015
Abstract: A robust and efficient numerical method for the calculation of the internal stress state that develops within structures subjected to mechanical and steady state or transient hygroscopic loading conditions, has been developed. The method encompasses a layer by layer approach whereby the structure is discretised into plies with different material properties corresponding to the different ply moisture content. The proposed method has been validated against finite element solutions, and results from its application on a fully characterised EDT (technical name) polymer binder are presented. The impact of the moisture induced viscoelastic behaviour on the structural response of the cas…
Synthesis and characterization of chalcogenide glasses from the system Ga-Ge-Sb-S and preparation of a single-mode fiber at 1.55 μm
2008
International audience; The aim of this work is to study different compositions in the Ga-Ge-Sb-S system for the definition of two compositions compatible with the elaboration of a single-mode fiber at the 1.55 μm telecom wavelength. The variations of the glass transition temperature (Tg), the dilatation coefficient (α) and the refractive index (n) have been studied for two glasses series: GaxGe25−xSb10S65 (series 1), Ga5Ge25−xSb10S60+x (series 2). This study has lead to the choice of the Ga4Ge21Sb10S65 composition as clad glass for the preparation of the single-mode fiber and Ga5Ge20Sb10S65 composition as the core. The discrepancies for the studied parameters between the core and clad comp…
An alternative conception of PM10 concentration changes after short-term precipitation in urban environment
2018
Abstract In the article, a linear model is presented which describes a reduction of PM10 mass concentration in relation to the type of precipitation and water vapour content in the air. The model was built using covariance analysis. In studies of PM10 concentration changes, the results of 247 observations were used, which were carried out in the urban area. Concentration changes were archived during short-term (30 min) convection and large-scale rainfalls. For the determination of PM10 mass concentration, the reference method was used. To describe changes in PM10 concentration in the air after precipitation, a series of linear models were created, in which the explanatory variables were: th…