2,389 research outputs found

    RAVEN: a GUI and an Artificial Intelligence Engine in a Dynamic PRA Framework

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    Increases in computational power and pressure for more accurate simulations and estimations of accident scenario consequences are driving the need for Dynamic Probabilistic Risk Assessment (PRA) [1] of very complex models. While more sophisticated algorithms and computational power address the back end of this challenge, the front end is still handled by engineers that need to extract meaningful information from the large amount of data and build these complex models. Compounding this problem is the difficulty in knowledge transfer and retention, and the increasing speed of software development. The above-described issues would have negatively impacted deployment of the new high fidelity plant simulator RELAP-7 (Reactor Excursion and Leak Analysis Program) at Idaho National Laboratory. Therefore, RAVEN that was initially focused to be the plant controller for RELAP-7 will help mitigate future RELAP-7 software engineering risks. In order to accomplish such a task Reactor Analysis and V

    Calibration of the ATLAS electromagnetic calorimeter using calibration hits

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    In the present note a method to determine the electron energy from the energies measured in an electron cluster is discussed. The method is based on a detailed Monte-Carlo simulation (labeled \textit{Calibration Hits}) of electrons in the ATLAS detector in which also the energies deposited in the passive and dead materials are recorded. It allows also to compute the different contributions (energy deposited in front, in and behind the Accordion) to the total electron energy. To better understand the various contributions to the energy reconstruction three rounds of simulations have been performed: electrons hitting the middle cell centre, electrons spread uniformly over a cell in absence of magnetic field and electrons spread uniformly over a cell in presence of magnetic field. The method is applied to the Barrel calorimeter and to electrons. Its extension to the End Caps and to photons does not pose problems. In the operative ATLAS conditions an energy resolution sampling term varying from 9.9%\% at η\eta=0.3 and 16.8%\% at η\eta=1.2 is obtained. The linearity varies between 0.1%\% and 0.4%\% in the energy interval 10-100GeV over the same η\eta range

    Long-term follow-up of Philadelphia chromosome-positive (Ph+) chronic myeloid leukaemia (CML) in children and adolescents managed at a single institution over a 20-year period

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    Chronic myeloid leukaemia (CML) is rare in childhood. In our Institution we managed 30 consecutive Ph+CML patients aged <18 years, according to our adults’ guidelines. Patients with HLA-identical related donor (RD) underwent stem cell transplant (SCT). Since 1989, patients without RD were systematically treated with -interferon (IFN) (median dosage: 6 MU/day). Of 18/19 evaluable patients, 17 (94.5%) achieved haematologic response (HR), 11/17 (65%) cytogenetic response (CyR), complete (CCyR) in 4 (23.5%). Three patients remain in CCyR, 2 achieved BCR-ABL transcript disappearance. Of 13 patients without CCyR, 5 underwent SCT, 4 switched to STI571, 4 progressed. All patients receiving STI571 in chronic phase (CP) obtained sustained CCyR and 3 a persistent molecular response. 8-year survival among IFN-treated patients, censored or not for subsequent therapies, is 62% and 63%. Overall, 13/30 patients underwent SCT: 5 HLA-identical-RD, 5 matched unrelated donor, 2 mismatched-RD, 1 unrelated mismatched umbilical cord blood. Eight allotransplanted patients (6/6 in 1st CP) are in cytogenetic and molecular remission with 8-year survival of 61% from SCT and 69% from diagnosis. In our 20-year experience, the use of IFN in children without matched RD led to prolonged cytogenetic and molecular responses and long-term survival, without impairing the outcome of subsequent SCT

    Dynamic PRA: an Overview of New Algorithms to Generate, Analyze and Visualize Data

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    State of the art PRA methods, i.e. Dynamic PRA (DPRA) methodologies, largely employ system simulator codes to accurately model system dynamics. Typically, these system simulator codes (e.g., RELAP5 ) are coupled with other codes (e.g., ADAPT, RAVEN that monitor and control the simulation. The latter codes, in particular, introduce both deterministic (e.g., system control logic, operating procedures) and stochastic (e.g., component failures, variable uncertainties) elements into the simulation. A typical DPRA analysis is performed by: 1. Sampling values of a set of parameters from the uncertainty space of interest 2. Simulating the system behavior for that specific set of parameter values 3. Analyzing the set of simulation runs 4. Visualizing the correlations between parameter values and simulation outcome Step 1 is typically performed by randomly sampling from a given distribution (i.e., Monte-Carlo) or selecting such parameter values as inputs from the user (i.e., Dynamic Event Tre

    Variações climáticas na Região da Serra Gaúcha.

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    bitstream/CNPUV/8808/1/cot070.pd

    BASILICA DI SAN GIACOMO IN COMO (ITALY): DRAWINGS AND HBIM TO MANAGE ARCHEOLOGICAL, CONSERVATIVE AND STRUCTURAL ACTIVITIES

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    This paper aims at presenting the recording and modelling work developed in the framework of restoration and conservation activities for the Basilica di San Giacomo in Como, Italy, whose construction started in the 11th century. The project started in 2022 and involved the application of the Historical Building Information Model (HBIM) methodology through a Scan-to-BIM approach was assessed. High-detailed 3D survey techniques were used to acquire the specific shape of the church and annexed buildings. Then, through different modelling strategies, the HBIM environment allowed the representation of all the architectural elements. The purpose of this model is to have essential support to plan the restoration activities and to give the different experts involved a single three-dimensional tool for managing all the information during the development of the construction works. The possibility to update the model over time with geometric and non-geometric information will provide a powerful tool also for other future activities, such as the installation of a monitoring system that could reveal the displacements of bearing elements of the church

    Emergent D6 symmetry in fully relaxed magic-angle twisted bilayer graphene

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    We present a tight-binding calculation of a twisted bilayer graphene at magic angle \u3b8 3c1.08, allowing for full, in- and out-of-plane, relaxation of the atomic positions. The resulting band structure displays, as usual, four narrow minibands around the neutrality point, well separated from all other bands after the lattice relaxation. A thorough analysis of the miniband Bloch functions reveals an emergent D6 symmetry, despite the lack of any manifest point-group symmetry in the relaxed lattice. The Bloch functions at the \u393 point are degenerate in pairs, reflecting the so-called valley degeneracy. Moreover, each of them is invariant under C3z, i.e., transforming like a one-dimensional, in-plane symmetric irreducible representation of an "emergent" D6 group. Out of plane, the lower doublet is even under C2x, while the upper doublet is odd, which implies that at least eight Wannier orbitals, two s-like and two pz-like ones for each of the supercell sublattices AB and BA, are necessary but probably not sufficient to describe the four minibands. This unexpected one-electron complexity is likely to play an important role in the still unexplained metal-insulator-superconductor phenomenology of this system

    Ossidazione ciclica ad alta temperatura di rivestimenti per pale di turbina a gas: codice di previsione di vita e sua convalida mediante dati sperimentali relativi a componenti

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    Lo studio qui presentato tratta i rivestimenti che formano una scaglia superficiale aderente di allumina, in grado di proteggere il materiale del componente; a questa categoria appartengono i rivestimenti per pale di turbine a gas, che subiscono degrado in esercizio sia per l’ossidazione della superficie esterna sia a seguito dei fenomeni interdiffusivi col substrato; inoltre la condizione di esercizio cui vengono sottoposti comprende numerosi cicli termici che tendono a far sgretolare la scaglia protettiva esterna (degrado per ossidazione ciclica). Il parametro utilizzato per stimare la vita residua del rivestimento metallico è la percentuale di alluminio ancora presente; infatti quando il contenuto di alluminio raggiunge il valore minimo critico, la capacità protettiva del rivestimento si esaurisce e la sua vita utile termina. In questa memoria viene descritto un codice di previsione, messo a punto sulla base dei risultati di un’ampia campagna sperimentale, in grado di calcolare la vita residua dei rivestimenti a partire dalle condizioni di esercizio. Ne viene mostrata dapprima l’applicazione ad un caso reale di componente esercito, effettuata per convalidare la capacità predittiva del codice. Vengono poi discussi i risultati delle valutazioni di vita ottenibili per due tipi diversi di rivestimento: AMDRY 995 e duplex, cioè con alluminizzazione superficiale. L’aspetto più innovativo del lavoro sta nella possibilità di tenere conto della minima temperatura del ciclo e quindi di riuscire a suggerire le condizioni di prova più efficaci perchè le prove di laboratorio simulino correttamente le condizioni di esercizio
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