5,459 research outputs found

    On the time dependence of the hh-index

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    The time dependence of the hh-index is analyzed by considering the average behaviour of hh as a function of the academic age AAA_A for about 1400 Italian physicists, with career lengths spanning from 3 to 46 years. The individual hh-index is strongly correlated with the square root of the total citations NCN_C: h≈0.53NCh \approx 0.53 \sqrt{N_C}. For academic ages ranging from 12 to 24 years, the distribution of the time scaled index h/AAh/\sqrt{A_A} is approximately time-independent and it is well described by the Gompertz function. The time scaled index h/AAh/\sqrt{A_A} has an average approximately equal to 3.8 and a standard deviation approximately equal to 1.6. Finally, the time scaled index h/AAh/\sqrt{A_A} appears to be strongly correlated with the contemporary hh-index hch_c

    Smart Grid for the Smart City

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    Modern cities are embracing cutting-edge technologies to improve the services they offer to the citizens from traffic control to the reduction of greenhouse gases and energy provisioning. In this chapter, we look at the energy sector advocating how Information and Communication Technologies (ICT) and signal processing techniques can be integrated into next generation power grids for an increased effectiveness in terms of: electrical stability, distribution, improved communication security, energy production, and utilization. In particular, we deliberate about the use of these techniques within new demand response paradigms, where communities of prosumers (e.g., households, generating part of their electricity consumption) contribute to the satisfaction of the energy demand through load balancing and peak shaving. Our discussion also covers the use of big data analytics for demand response and serious games as a tool to promote energy-efficient behaviors from end users

    Three embedded techniques for finite element heat flow problem with embedded discontinuities

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    The final publication is available at Springer via http://dx.doi.org/10.1007/s00466-017-1382-7The present paper explores the solution of a heat conduction problem considering discontinuities embedded within the mesh and aligned at arbitrary angles with respect to the mesh edges. Three alternative approaches are proposed as solutions to the problem. The difference between these approaches compared to alternatives, such as the eXtended Finite Element Method (X-FEM), is that the current proposal attempts to preserve the global matrix graph in order to improve performance. The first two alternatives comprise an enrichment of the Finite Element (FE) space obtained through the addition of some new local degrees of freedom to allow capturing discontinuities within the element. The new degrees of freedom are statically condensed prior to assembly, so that the graph of the final system is not changed. The third approach is based on the use of modified FE-shape functions that substitute the standard ones on the cut elements. The imposition of both Neumann and Dirichlet boundary conditions is considered at the embedded interface. The results of all the proposed methods are then compared with a reference solution obtained using the standard FE on a mesh containing the actual discontinuity.Peer ReviewedPostprint (author's final draft


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    La combustione HCCI (homogeneous charge compression ignition) avviene per accensione spontanea in miscele omogenee diluite ed ha un andamento graduale grazie ad opportuni accorgimenti. È considerata una soluzione molto promettente per ridurre le emissioni inquinanti dei motori a combustione interna, rispetto ai valori tipici sia dei motori ad accensione comandata (A.C.) che di quelli ad accensione spontanea (A.S.). Ad oggi, il funzionamento in combustione HCCI non è ancora in grado di coprire l’intero campo di funzionamento del motore, che deve perciò essere costruito per funzionare anche in modo tradizionale, ad A.C. o ad A.S., in conformità con il combustibile che viene utilizzato. È stata studiata una soluzione innovativa nella quale il controllo della combustione è affidato alla progressiva immissione di una carica omogenea all’interno del cilindro durante la fase di combustione. Questa tipologia di combustione,per la quale si prevede l’uso di un combustibile per motori ad A.S., rappresenta una combinazione tra una combustione progressiva ed una HCCI tradizionale, e pertanto è stata definita HCPC (Homogeneus Charge Progressive Combustion). Mediante simulazioni CFD (Computational Fluid Dynamics), è stata analizzata un’applicazione della soluzione proposta ad un motore diesel funzionante con ciclo 2T. Sono stati valutati i valori di potenza indicata, rendimento indicato ed emissioni inquinanti al variare di alcuni parametri motoristici

    Joint Optimal Pricing and Electrical Efficiency Enforcement for Rational Agents in Micro Grids

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    In electrical distribution grids, the constantly increasing number of power generation devices based on renewables demands a transition from a centralized to a distributed generation paradigm. In fact, power injection from Distributed Energy Resources (DERs) can be selectively controlled to achieve other objectives beyond supporting loads, such as the minimization of the power losses along the distribution lines and the subsequent increase of the grid hosting capacity. However, these technical achievements are only possible if alongside electrical optimization schemes, a suitable market model is set up to promote cooperation from the end users. In contrast with the existing literature, where energy trading and electrical optimization of the grid are often treated separately or the trading strategy is tailored to a specific electrical optimization objective, in this work we consider their joint optimization. Specifically, we present a multi-objective optimization problem accounting for energy trading, where: 1) DERs try to maximize their profit, resulting from selling their surplus energy, 2) the loads try to minimize their expense, and 3) the main power supplier aims at maximizing the electrical grid efficiency through a suitable discount policy. This optimization problem is proved to be non convex, and an equivalent convex formulation is derived. Centralized solutions are discussed first, and are subsequently distributed. Numerical results to demonstrate the effectiveness of the so obtained optimal policies are then presented
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