1,720,988 research outputs found
Solid thermal storage with PCM materials. Numerical investigations
No full textThermal energy storage systems in solid state are the next generation of solar power plants which bring a substantial optimization in the energy production; they compensate for the gap between the availability of solar irradiation and the electricity demand by an endowed heat storage. The proposed research is aimed to analyse the coupled behaviour of concrete including PCM (Phase Change Materials) particles employed as solid energy storage media, even emphasizing the relevance of analyses at the mesoscale level. A study on the increased thermal capacity in Thermal Energy Storage (TES) concrete solids with inclusions of PCM is developed within this paper. Particularly, the change in thermal behaviour of such composites by varying the inclusions percentage is assessed. Transient thermal analyses are conducted by considering a homogenized composite; a uniform distribution of PCM, obtained during mixing of fresh concrete, is assumed within the cementitious matrix. Additionally, the change in mechanical strength of such a material is analytically and numerically investigated, both at room temperature and during heating. 3D mechanical FE models are also developed at the meso-scale level to explicitly represent the main concrete components such as cement paste, coarse aggregates, and PCM to better describe the evolutionary process of thermal damage - if occurring - during plant functioning. © 2017 Elsevier Lt
IC.IDO as a tool for displaying machining processes. The logic interface between computer-aided-manufacturing and virtual reality
Full text linkThis scientific communication investigates the logic interface of a CAM solver, i.e., MasterCAM, into a Virtual Reality (VR) environment. This integration helps in displaying machining operations in virtual reality. Currently, to partially visualize the results of a simulation in an immersive environment, an import/export procedure must be done manually. Here, a software plugin integrated into IC.IDO (by ESI Group) has been realized and fully described. This application allows the complete integration of CAM solver into the VR environment. In particular, the VERICUT solver has been integrated into VR. This kind of integration has never been done yet
Thermal characterization methodology for dry finishing turning of SAF 2507 stainless steel based on finite element simulations and surrogate models
Full text linkThis paper addresses the numerical thermal characterization of a 3D turning process of a SAF 2507 stainless steel. A thermographic test campaign was conducted to measure the temperature distribution at the tool-workpiece interface. The campaign was accommodated by means of a L18 fractional factorial design of experiment. The 3D turning process was simulated using the software TWS Advantedge. The heat transfer numerical coefficients were calibrated against experimental measures to obtain temperature values as accurate as possible. A statistical methodology framework was adopted to study the dependence of the coefficients from the machining parameters. A heat transfer surrogate model was then built and next experimentally validated
Innovative heat storage concrete systems for solar power plants under medium and high temperatures
No full textExperimental thermographic investigation for dry finish turning of SAF 2507 steel
No full textThe Oil&Gas Industry widely uses Super-Duplex Stainless Steels (S-DSS) since their combination of high mechanical characteristics and corrosion resistance. Among them, the SAF 2507 is one of the renowned. The challenges associated with the machining of these steels are directly related to the high temperature that influences the tool-life and the quality of the finished products. This phenomenon is induced by the low thermal conductivity which leads to a high concentration of heat. In order to properly understand their thermal behavior, the distribution of the temperature varying the cutting parameters should be investigated. During dry finish turning, the evolution of the temperature can be captured through a thermographic test campaign, for instance following a L18 - 2 · 37-5 fractional factorial design with no replications. The data acquired can be deeply studied with a statistical methodology framework, the relationship between the response of the experiment and the machining parameters can be established, and a surrogate model for predicting the temperature can be built and validated. The results show that, for the SAF 2507 steel, the cutting temperature for dry finishing turning is mostly influenced by the deep of cut, the feed rate and slightly by the cutting speed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Statistical evidence and DNA in the criminal procedure
No full textJudicial statistics is generally referred to as the detection of data on crimes and trial outcomes, with subsequent analysis of the data thus detected. Statistics applied to the evaluation of evidence is increasingly being recognized as an important part of the modern criminal justice system. This paper is about the use of DNA test for identification and judicial purposes – the greatest revolution in criminal investigation –, also in reference to a concrete case of statistics applied to forensic genetics. Forensic science is the application of scientific methodologies to traditional investigative techniques in relation to the detection of a crime: its scope is wide, ranging from biology to psychology, chemistry, computer science, physics, medicine and engineering. Forensic genetics is a specialized branch of forensic science, which analyzes the DNA to prove suspicious responsibility for a crime. Science and law walk together in the process of determining the procedural truth, from the preliminary investigation phase to the final judgement. Statistical evidence is not always considered reliable in the criminal procedure, as it is based on a subjective probability concept. On the other hand, a rational evidence that can claim criminal liability “beyond any reasonable doubt” is necessary. In this regard, in this paper we analyze how the DNA test can be considered a scientific, reliable and valid evidence when contextualized and evaluated together with the other elements found during the criminal procedure: scientific investigation and traditional investigation tools must go hand in hand towards determining the procedural truth. The scientificity of identifying the individual by typing the DNA profile detected on the crime scene is thus validated, until constituting scientific evidence in the criminal procedure, supported by the statistical calculation of the rarity of the probability that the typed genetic profile could be casually attributed to another individual in the world population
Validation of TiAlN functional coatings through cryo-tribological characterization using a pin-on-disk experiment
Full text linkThe purpose of this study has been to investigate the effects of TiAlN functional coatings in cryo-tribological pin-on-disk experiments. Nowadays, the introduction of new machining technologies for chip removal, both at high speed and in cryogenic conditions, is posing new challenges and opening new horizons to research. As a matter of fact, that in this technology needs to focus on the choice of workpiece materials to be machining and tools coatings used. For the latter, the wear phenomenon has been studied employing pins-on-disk (made by nickel-based alloys) under a liquid nitrogen jet flows simulating cryogenic machining. The coatings used have been of two different types: the coating C1 is a ZrTiAlN quaternary, while the coating C2 is a TiAlN/ZrN. The films were deposited with processes developed by the ENEA Brindisi laboratory using a dual magnetron sputtering and HiPPMS physical deposition technique. The wear measures were acquired employing a full factorial design with two factors: i.e., the test conditions (DRY or CRYO) and the pin coatings (not coated NC, coating C1 or C2). The number of tests was 12 since 2 were the replications. Based on preliminary experimental results, it can be stated that there is a type of coating, i.e., TiAlN/ZrN, that allows for high processing speed, high material removal, and a considerable increase in tool life
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