Search results for " Opera"
showing 10 items of 3606 documents
Handling the epistemic uncertainty in the selective maintenance problem
2020
Abstract Nowadays, both continuous and discontinuous operating systems require higher and higher reliability levels in order to avoid the occurrence of dangerous or even disastrous consequences. Accordingly, the definition of appropriate maintenance policies and the identification of components to be maintained during the planned system’s downtimes are fundamental to ensure the reliability maximization. Therefore, the present paper proposes a mathematical programming formulation of the selective maintenance problem with the aim to maximize the system’s reliability under an uncertain environment. Specifically, the aleatory model related to the components’ failure process is well known, where…
Experimental P-T-ro Measurements of Supercritical Mixtures of Carbon Dioxide, Carbon Monoxide, and Hydrogen and Semiquantitative Estimation of Their …
2007
The P-T-ρ behavior of the CO2-CO-H2 system was studied in the supercritical region under operative conditions close to those adopted to perform hydrogenation and hydroformylation reactions in dense CO 2, thus providing new interesting information on this fluid mixture. Experiments were performed in a fixed volume reactor in the temperature range from 298 K to 343 K changing the density and the composition of the fluid phase. The one-component (Hildebrand) solubility parameter of the mixture was estimated from experimentally measured P vs T profiles, and its dependence on the density and composition of the system was analyzed to study the antisolvent effect of the permanent gases. We have fo…
Evolutionary Game Dynamics for Collective Decision Making in Structured and Unstructured Environments
2017
Abstract For a large population of players we consider a collective decision making process with three possible choices: option A or B or no option. The more popular option is more likely to be chosen by uncommitted players and cross-inhibitory signals can be sent to attract players committed to a different option. This model originates in the context of honeybees swarms, and we generalise it to accommodate other applications such as duopolistic competition and opinion dynamics. The first contribution is an evolutionary game model and a corresponding new game dynamics called expected gain pairwise comparison dynamics explaining how the strategic behaviour of the players may lead to deadlock…
L'ergonomia e la sicurezza delle macchine operatrici nelle aziende agricole siciliane
2002
The agricultural machines available in a meaningful sample of farms in the Eastern and Central Sicily were surveyed with particular reference to the laws concerning with ergonomics and safety. The agricultural machines examined showed poor ergonomics and safety conditions. These results are caused by an insufficient maintenance or lack of protection and safety devices, depending also on the year of manufacture of the agricultural machines.
Health & safety 4.0: A digital twin reference model to support the smart operator at the workplace
2020
In the Industry 4.0 era, Cyber-Physical Systems (CPS) and the Internet of Things are the enabling technologies for a new tool, the Digital Twin, that allows a streamlined communication, automation and interoperability among all the production assets. Even if there has been a great deal of efforts toward digital twin engineering, little attention has been paid to the correct integration of humans in the emerging context of smart factories and, in particular, to the potential contribution of digital twins for supporting a health and safety 4.0 at the workplace. This paper sets the stage for a discussion over health and safety aspects for the Smart Operator and proposes a renewed approach to t…
La opinión de los graduados europeos sobre la universidad cinco años después de haber finalizado sus estudios
2011
In today¿s knowledge society, in which university graduates are required to obtain new abilities to adjust to the demands of the labour market, the figure of the ¿flexible professional¿ has emerged. Universities are not immune to these changes and are proposing modifications to the curricula. In this paper, we attempt to depict the views of university graduates regarding their university five years after completing their studies. Information about graduates¿ educational experience is crucial to educational managers in charge of designing curricula and educational policies. The data used in this paper are obtained from the REFLEX Survey.
Crítica musical y pensamiento estético en la España de la Restauración: José María Esperanza y Sola (1834-1905)
2015
One of the most outstanding figures of music criticism in the Spanish Restoration was José María Esperanza y Sola (1834-1905), active for thirty years, from the late 1860s until the end of the century. During this period, Esperanza collaborated in different periodical publications and, particularly, “La Ilustración Española y Americana”, from whose pages he informed about the most important musical events celebrated in Madrid, judged according to a conservative aesthetic criterion, opposed to any novelty that infringe the traditional music system. On the basis of Esperanza´s thought, our study analyzes the different subjects that constitute his journalistic production.La crítica musical en …
Proposal of Isobutyl Alcohol as Entrainer To Separate Mixtures Formed by Ethanol and Water and 1-Propanol and Water
2017
Isobutyl alcohol (IBA) has been proposed as a solvent to carry out the dehydration of ethanol and 1-propanol by means of a nonconventional distillation process. In this way, isobaric vapor–liquid equilibrium (VLE) and vapor–liquid–liquid equilibrium (VLLE) data at atmospheric pressure have been obtained for the ternary systems ethanol (1a) + water (2) + IBA (3) and 1-propanol (1b) + water (2) + IBA (3). Then, these data have been correlated to obtain a set of parameters capable of estimating VLE and VLLE. According to the results achieved, distillation sequences to separate water and ethanol or 1-propanol have been proposed. Finally, a study about the minimum amount of entrainer required to…
Thermodynamic Analysis and Process Simulation of Ethanol Dehydration via Heterogeneous Azeotropic Distillation
2014
The heterogeneous azeotropic distillation process is widely used to separate nonideal binary mixtures into their constituent pure components. This method uses the addition of a third component, called an entrainer, to cause liquid–liquid phase separation over a broad range of compositions in the ternary phase diagram. Ethanol dehydration was used as a case study and diisopropyl ether and isobutyl alcohol were analyzed as possible entrainers in a heterogeneous azeotropic distillation. In this way, isobaric vapor–liquid–liquid equilibrium was measured for the ethanol + water + diisopropyl ether or + isobutyl alcohol ternary mixtures at 101.3 kPa. The data were correlated by the NRTL and UNIQU…
Influence of temperature on the hydration products of low pH cements
2012
International audience; The chemical evolution of two hydrated "low pH" binders prepared from binary (60% Portland cement + 40% silica fume) or ternary (37.5% Portland cement +32.5% silica fume + 30% fly-ash) mixtures was characterized over one year at 20 degrees C. 50 degrees C, and 80 degrees C. The main hydrates were Al-substituted C-S-H. Raising the temperature from 20 to 80 degrees C caused a lengthening and cross-linking of their silicate chains. Ettringite that formed in pastes stored at 20 degrees C was destabilized. Only traces of calcium sulfate (gypsum and/or anhydrite) reprecipitated after one year in some materials cured at 50 degrees C and 80 degrees C. The sulfates released w…