Buckling of circular plates with functional grading in two directions

This short note considers thin circular plates, functionally graded in both axial and transverse directions and loaded in compression on the middle plane by a uniform axisymmetric load. The functional grading is based on recent literature on the subject and we deal with a direct problem for buckling, i.e., given the geometry of the plate and its constitutive properties, the critical load multiplier and the buckling mode are determined by a usual non-triviality condition. Original expressions are found in a nearly closed form and show that suitable functional grading, actually achievable in practice, may lead to gentle solutions. Numerical examples, physical interpretations and comments are provided

FIXED BROADBAND CONNECTIONS AND ECONOMIC GROWTH: A DYNAMIC OECD PANEL ANALYSIS

Technological innovation is viewed as a major stimulus for economic growth. High-speed internet access via broadband infrastructure has been experiencing a prompt development since the end of 90s, thanks to the deployment of both fix and mobile technologies. The present study investigates on the behavior of broadband diffusion as a technological determinant of economic growth in the main OECD countries. The estimations performed allowed to control and interpret the time evolution of the phenomenon according to the achievable target of growth, as resulting from the promotion of broadband internet connections. Our main goal is to provide evidence of a relevant - in quantitative term - relation between broadband diffusion and economic dynamics in the short, medium and long run

geomatics for structural assessment and surface diagnostic of ch

Abstract The capacity to rapidly acquire large quantities of spatial data, to geo-reference information on them, to obtain detailed models that allow more and more accurate analyses and simulations, place Geoinformatics at the center of attention in many research areas. Among these, the use of these techniques for the study of existing structures is particularly interesting. Assessing the current stability of a building, monitoring the evolution over time of a failure, preventing the potential causes of damage, simulating the behavior of a building under seismic actions, are just some of the ways in which the geometric properties of a structure, acquired with the most up-to-date automated surveying systems, are used to help validate structural integrity analyse

an indirect in cylinder pressure measurement technique based on the estimation of the mechanical strength acting on an engine head screw development and assessment

Abstract The increasing application of new concepts for the combustion process in internal combustion engines, e.g. HCCI or RCCI, is mainly aimed at reducing pollutant emissions and fuel consumption. A typical drawback of these technologies is the difficulty of properly controlling the combustion process in the area of medium-high brake mean effective pressure (BMEP), where the thermodynamic conditions inside the cylinder promote a very fast combustion process. To this end, the availability of a fast real-time monitoring of the in-cylinder pressure is then becoming pivotal. This is commonly done by means of piezoelectric dynamic pressure sensors, which are indeed very accurate, but also extremely expensive and characterized by a limited durability due to the harsh working conditions. Moving from this background, the present study describes a new methodology to evaluate the in-cylinder pressure by correlating it with the mechanical stress measured by a strain washer installed on an engine head screw. The strain washer can indeed work in a much more favorable environment with respect to a dynamic pressure sensor flush-mounted on the cylinder head (with aggressive hot gasses and high pressure) with direct benefits for its durability and ease of installation. To assess the model capabilities, experimental tests have been carried out on a single-cylinder, 4-stroke engine and on a 2-stroke engine at the laboratory of internal combustion engines of the Universita degli Studi di Firenze. The results reported in the study show the direct comparison of the in-cylinder pressure, as a function of the crankshaft angular position, measured directly with a dynamic pressure sensor and indirectly by means of the strain washer. Sound agreement was found between the two, proving the effectiveness of the proposed methodology

The florence baptistery: 3-D Survey as a knowledge tool for historical and structural investigations

The Baptistery of San Giovanni is one of the most important pieces of architecture in Florence. It is an octagonal building, encrusted with marble both internally and externally (including the pyramidal roof) and covered inside by a magnificent dome with sparkling gold mosaics. During Dante’s time, it appeared much older than the other monuments, so its origins were considered as hailing straight from Florence’s most remote and mythical history. Even though we have much more data now, scholars still disagree over the interpretations on the origin and construction sequence of the monument. Survey has always been considered a main instrument for understanding historical architecture, mostly from constructional and structural points of view. During the last century, the Baptistery was surveyed using both traditional techniques and the most up-to-date instruments available at the time, such as topography, close-range photogrammetry and laser scanning. So, a review of those early applications, even if partial or isolated, can significantly attest to the state of the art and evolution of survey techniques. During recent years, the Opera di Santa Maria del Fiore promoted new research and a wide range of diagnostic investigations aimed at acquiring greater knowledge of the monument in anticipation of the cleaning and restoration of the outer wall surfaces during 2015. Among this research, GeCo Lab carried out a new systematic and complete laser scanner survey of the whole Baptistery, acquiring data for the more inaccessible parts that were given little attention during other survey campaigns. First of all, the paper analyses recent contributions given by instrumental surveys in advancing knowledge of the building, with references to the cutting-edge techniques and measurement tools used at the time. Then, it describes the new survey campaign, illustrating the approach followed in the planning, data acquisition and data elaboration phases; finally, it gives examples of some interpretations of the structure stemming from the new acquisitions

Digital workflow for the acquisition and elaboration of 3D data in a monumental complex: the fortress of Saint John the Baptist in Florence

In recent years, the GeCo Laboratory has undertaken numerous projects to digitalize vast and complex buildings; the specific nature of the different projects has resulted in a case-by-case approach, each time working on past experiences and updating not only the hardware and software tools but also the management and processing methods. This paper presents the workflow followed for the survey of the Fortress of Saint John the Baptist in Florence, an on-going interdisciplinary project. Presently Florence’s main trade fair congress centre, at the same time it hosts various buildings that bear witness to the fortress’s life-history, combining constructions from the Medici and Lorraine eras with recently built exhibition facilities. Now new research has been required due to the realization of new pavilions and the regeneration of the whole complex. This has included a critical survey, material testing, diagnostic investigations and stratigraphic analyses to define the building’s state of preservation. The working group comprises specialists from different institutions, amongst which the Italian Military Geographic Institute, the University of Florence, the National Research Council Institute for the Preservation and Enhancement of the Cultural Heritage, and the Florence City Council

HIGH-QUALITY 3D MODELS AND THEIR USE IN A CULTURAL HERITAGE CONSERVATION PROJECT

Cultural heritage digitization and 3D modelling processes are mainly based on laser scanning and digital photogrammetry techniques to produce complete, detailed and photorealistic three-dimensional surveys: geometric as well as chromatic aspects, in turn testimony of materials, work techniques, state of preservation, etc., are documented using digitization processes. The paper explores the topic of 3D documentation for conservation purposes; it analyses how geomatics contributes in different steps of a restoration process and it presents an overview of different uses of 3D models for the conservation and enhancement of the cultural heritage. The paper reports on the project to digitize the earthenware frieze of the Ospedale del Ceppo in Pistoia (Italy) for 3D documentation, restoration work support, and digital and physical reconstruction and integration purposes. The intent to design an exhibition area suggests new ways to take advantage of 3D data originally acquired for documentation and scientific purposes