1,721,517 research outputs found
"Open" Lab? Studying the Implementation of Open Innovation Practices in a University Laboratory
Full text linkSensitivity based selection of inputs and delays for nonlinear ARX models
No full textIn this paper, an extension of sensitivity based pruning (SBP) method for Nonlinear AutoRegressive models with eXogenous inputs (NARX) model is presented. Besides the in- puts, input and output delays are simultaneously pruned in terms of the backward elimination. The concept is based on replacement of some regressors by their mean value, which corresponds to the removal of inuence of the particular regressors from the network. The method is demonstrated on two datasets. Firstly, one artificial generator is used to test if the method is able to find an optimal set of inputs and delays. Further, the method is used for prediction of gas consumption of a simulated heating for an office building. It is shown that the SBP significantly reduces the complexity of the NARX network without any significant performance degradation. Moreover, it is hypothesized than SBP can be more important for NARX than for simple feedforward neural network, because NARX is more prone to overfitting and has problems with stability. © 2016 ICST
Symmetries of the Electromagnetic Turbulence in a Tokamak Edge
Full text linkWe construct the low-frequency formulation of the turbulence characterizing the plasma in a Tokamak edge. Under rather natural assumptions, we demonstrate that, even in the presence of poloidal magnetic fluctuations, it is possible to deal with a reduced model for turbulence dynamics. This model relies on a single equation for the electric potential from which all the physical turbulent properties can be calculated. The main result of the present analysis concerns the existence of a specific Fourier branch for the dynamics which demonstrate the attractive character of the two-dimensional turbulence with respect to non-axisymmetric fluctuations. The peculiar nature of this instability, affecting the non-axially symmetric modes, is discussed in some detail by recovering two different physical regimes
Model predictive control for building active demand response systems
No full textThe Active Demand Response (ADR), integrated with the distributed energy generation and storage systems, is the most common strategy for the optimization of energy consumption and indoor comfort in buildings, considering the energy availability and the balancing of the energy production from renewable sources. In the paper an overview of basic requirements and applications of ADR management is presented. Specifically, the model predictive control (MPC) adopted in several applications as optimal control strategy in the ADR buildings context is analysed. Finally the research experience of the authors in this context is described. © 2015 The Authors.Published by Elsevier Ltd
Indoor lighting fault detection and diagnosis using a data fusion approach
No full textIn this paper, an innovative and automated fault detection and diagnosis (FDD) approach based on high-level correlation rules in order to improve reliability, safety and efficiency of a supervised building is presented. The proposed method is based on the data fusion of different measurements, using their fuzzification and aggregation through suitable operators, in order to get dimensionless severity indicators able to diagnose faults and to identify the possible causes (ranked according their severity) generating them. Thus, a set of possible anomalies that can occur in a building and the correlation with measured physical quantities were identified. Experimentation of this FDD technique was applied to indoor lighting of a real office building. The proposed method was validated over a onemonth period with the aim of detecting anomalous consumption events, considering when and in which circumstances they occurred. After this stage, the FDD system was performed in real time operation. © 2014 WIT Press
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
Addressing the accuracy quantification issue for CFD simulation of in-vessel flows
No full textThe presentation was devoted to accuracy quantification in the CFD investigation of in vessel
flows. An example of the multi-dimensional information that needs to be captured is
represented by the time and space distribution of coolant properties (e.g. temperature, boron
concentration) at the reactor core inlet, a topic relevant to reactor safety as local perturbations,
because of the potential to induce power excursions. An attempt was made to tackle the accuracy
quantification issue for this class of data in a somewhat empirical way by proposing a set of
parameters that can be used, after a qualitative analysis of measured data and code simulation
results, to characterise the “perturbation” of tvessel flowhe target variable time and space distributions, and to
quantify the deviation of the simulation from the experimental data. The advantage of using
many parameters relies on the ability to cover all relevant features of the chosen target
variables, and thus provide a more complete assessment and regarding overall agreement
Accuracy quantification metrics for CFD simulation of in-vessel flows
No full texttWithin more general frameworks dealing with uncertainty evaluation and code assessment, well assessedmethodologies exist for the accuracy evaluation of system thermal hydraulic analysis results. As longas multi-dimensional transient data is involved, such as space and time distributions obtained fromCFD calculations and experiments, the task of quantifying the accuracy and defining acceptance criteriabecomes harder, and there seems to be a lack of systematic approaches available to that purpose.An example of such multi-dimensional data is represented by the time and space distribution of coolantproperties (e.g. temperature, boron concentration) at the reactor core inlet, which is relevant to reactorsafety as local perturbations potentially induce power excursions. An attempt is made here to tackle theaccuracy quantification issue for that class of data, in a somewhat empirical way, i.e. by proposing a setof parameters that can be used, after proper qualitative analysis of measured data and code simulationresults, to characterize the target variable time and space distributions, and to quantify the deviation ofthe simulation from the experimental data. The advantage of using such kind of metrics based on manyparameters relies in the ability to cover different relevant features of the target variables and thus providea more complete assessment and allow statements about the overall agreemen
Il settore della componentistica auto nel Mezzogiorno. Un’analisi esplorativa degli indotti locali degli stabilimenti centro-meridionali di assemblaggio finale di FCA
No full textIl capitolo ha per oggetto un’analisi qualitativa degli indotti locali degli stabilimenti FCA di Melfi, Pomigliano, Cassino e Atessa (SEVEL). L’analisi si basa su materiali già disponibili pubblicati dall’autore e su dati rilevati per l’occasione dallo stesso. A corredo di questi abbiamo fatto riferimento a quelli dell’indagine campionaria oggetto di questa pubblicazione, ma con specifico riferimento alle sole imprese con sede operativa in una regione del Mezzogiorno (Lazio incluso). L’idea di supportare i dati della rilevazione campionaria con altri di natura qualitativa e di osservazione diretta sul campo ha come finalità quella di offrire un quadro più dettagliato dell’indotto di primo livello, e più in generale degli indotti locali, degli stabilimenti FCA di assemblaggio auto e veicoli commerciali localizzati nel Mezzogiorno
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