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p-Multilevel Preconditioners for HHO Discretizations of the Stokes Equations with Static Condensation

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Communications on Applied Mathematics and Computation 2022年第3期4卷 783-822页

作者： Lorenzo Botti daniele A.Di Pietro Department of Engineering and Applied Sciences University of BergamoBergamoItaly IMAG Univ MontpellierCNRSMontpellierFrance

We propose a p-multilevel preconditioner for hybrid high-order(HHO)discretizations of the Stokes equation,numerically assess its performance on two variants of the method,and compare with a classical discontinuous Galerkin *** efficient implementa-tion is proposed where coarse level operators are inherited using L2-orthogonal projec-tions defined over mesh faces and the restriction of the fine grid operators is performed recursively and *** h-and k-dependency are investigated tackling two-and three-dimensional problems on standard meshes and graded *** the two HHO for-mulations,featuring discontinuous or hybrid pressure,we study how the combination of p-coarsening and static condensation influences the V-cycle *** particular,two dif-ferent static condensation procedures are considered for the discontinuous pressure HHO variant,resulting in global linear systems with a different number of unknowns and matrix non-zero ***,we show that the efficiency of the solution strategy might be impacted by static condensation options in the case of graded meshes.

关键词： Stokes equations Divergence free constraint Hybrid high-order Discontinuous Galerkin p-multigrid Static condensation

ITERATIVE ILU PRECONDITIONERS FOR LINEAR SYSTEMS AND EIGENPROBLEMS

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Journal of Computational Mathematics 2021年第4期39卷 633-654页

作者： daniele Boffi Zhongjie Lu Luca F.Pavarino Computer Electrical and Mathematical Sciences and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia Dipartimento di Matematica"F.Casorati"University of Pavia Via Ferrata 5 27100 PaviaItaly Dipartimento di Matematica University a di Paviavia Ferrata 527100 PaviaItaly School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026China Dipartimento di Matematica Universita di Paviavia Ferrata 527100 PaviaItaly

Iterative ILU factorizations are constructed,analyzed and applied as preconditioners to solve both linear systems and *** computational kernels of these novel Iterative ILU factorizations are sparse matrix-matrix multiplications,which are easy and efficient to implement on both serial and parallel computer architectures and can take full advantage of existing matrix-matrix multiplication *** also introduce level-based and threshold-based algorithms in order to enhance the accuracy of the proposed Iterative ILU *** results of several numerical experiments illustrate the efficiency of the proposed preconditioners to solve both linear systems and eigenvalue problems.

关键词： Iterative ILU factorization Matrix-matrix multiplication Fill-in Eigenvalue problem Parallel preconditioner

DICE:An open-source MATLAB application for quantification and parametrization of digital outcrop model-based fracture datasets

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第5期15卷 1090-1110页

作者： Niccolò Menegoni daniele Giordan Riccardo Inama Cesare Perotti Department of Earth and Environmental Sciences University of PaviaPavia27100Italy National Research Council of Italy Research Institute for Geo-Hydrological Protection(CNR-IRPI)Torino10135Italy Signal S.r.l. Via Fratelli Cuzio 42Pavia27100Italy

An open-source MATLAB application(app)named Discontinuity Intensity Calculator and Estimator(DICE)was developed in order to quantitatively characterize the fractures,or in more general,discontinuities within a rocky outcrop in three-dimensional(3D)digital data,such as digital outcrop model(DOM).The workflow proposed for the parametrization of the discontinuities consists of the following steps:(1)Analysis and mapping of the fractures detected within the 3D DOMs;(2)Calculation of the orientation,position and dimensions of discontinuities that are represented by best-fit circular planes;(3)Determining the discontinuity parameters(dimension,distribution,spacing and intensity)by the DICE algorithm using different 3D oriented sampling techniques(3D oriented scanline,3D oriented circular scan window and spherical scan volume).Different sampling methods were bench tested with a synthetic,as well as a natural case study,and compared in order to understand the advantages and limitations of each *** 3D oriented circular scan window appears to be the most effective method for fracture intensity estimation with high accuracy(error 0.4%)and stability with variations in scan radius.

关键词： Fracture parameter Discontinuity Fault Fracture intensity Linear fracture intensity(P10) Areal fracture intensity(P21) Volumetric fracture intensity(P32)

Zooming in REE and Other Trace Elements on Conodonts:Does Taxonomy Guide Diagenesis?

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Journal of Earth Science 2021年第3期32卷 501-511页

作者： Luca Medici Martina Savioli Annalisa Ferretti daniele Malferrari National Research Council of Italy Institute of Methodologies for Environmental AnalysisC.da S.Loja-Zona Industriale85050 Tito ScaloPotenzaItaly Department of Chemical and Geological Sciences University of Modena and Reggio EmiliaVia Campi 10341125 ModenaItaly

Conodont elements are calcium phosphate(apatite structure)mineralized remains of the cephalic feeding apparatus of an extinct marine *** to the high affinity of apatite for rare earth elements(REE)and other high field strength elements(HFSE),conodont elements were frequently assumed to be a reliable archive of sea-water composition and changes that had occurred during ***,the crystallinity index of bioapatite,i.e.,the rate of crystallinity of biologically mediated apatite,should be generally linearly dependent on diagenetic alteration as the greater(and longer)the pressure and temperature to which a crystal is exposed,the greater the resulting *** this study,we detected the uptake of HFSE in conodont elements recovered from a single stratigraphic horizon in the Upper Ordovician of Normandy(France).Assuming therefore that all the specimens have undergone an identical diagenetic history,we have assessed whether conodont taxonomy(and morphology)impacts HFSE uptake and crystallinity *** found that all conodont elements are characterized by a clear diagenetic signature,with minor but significant differences among *** distinctions are evidenced also by the crystallinity index values which show positive correlations with some elements and,accordingly,with diagenesis;however,correlations with the crystallinity index strongly depend on the method adopted for its calculation.

关键词： bioapatite crystallinity index HFSE laser ablation mass spectrometry microdiffraction Normandy Ordovician

Efficient GW calculations in two dimensional materials through a stochastic integration of the screened potential

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npj Computational Materials 2023年第1期9卷 1912-1919页

作者： Alberto Guandalini Pino D’Amico Andrea Ferretti daniele Varsano S3 Centre Istituto NanoscienzeCNRVia Campi 213/aModenaItaly Present address:Dipartimento di Fisica Universitàdi Roma La SapienzaPiazzale Aldo Moro 5I-00185 RomaItaly

Many-body perturbation theory methods,such as the G0W0 approximation,are able to accurately predict quasiparticle(QP)properties of several classes of ***,the calculation of the QP band structure of two-dimensional(2D)semiconductors is known to require a very dense BZ sampling,due to the sharp q-dependence of the dielectric matrix in the long-wavelength limit(q→0).In this work,we show how the convergence of the QP corrections of 2D semiconductors with respect to the BZ sampling can be drastically improved,by combining a Monte Carlo integration with an interpolation scheme able to represent the screened potential between the calculated grid *** method has been validated by computing the band gap of three different prototype monolayer materials:a transition metal dichalcogenide(MoS2),a wide band gap insulator(hBN)and an anisotropic semiconductor(phosphorene).The proposed scheme shows that the convergence of the gap for these three materials up to 50meV is achieved by using k-point grids comparable to those needed by DFT calculations,while keeping the grid uniform.

关键词： materials integration potential

Testicular ultrasound inhomogeneity is an informative parameter for fertility evaluation

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Asian Journal of Andrology 2020年第3期22卷 302-308页

作者： Giorgia Spaggiari Antonio R M Granata daniele Santi Unit of Endocrinology Department of BiomedicalMetabolic and Neural SciencesUniversity of Modena and Reggio EmiliaModena 41126Italy Unit of Endocrinology Department of Medical SpecialtiesAzienda Ospedaliero-Universitaria of ModenaOspedale Civile of BaggiovaraModena 41126Italy.

Testicular volume(TV)is proposed to be a positive predictor of male fertility status,because of the relation known between the TV and the seminiferous tubule *** of the measurement methodology,the role of TV and testicular ultrasound(US)assessments is still debated in andrological clinical *** this retrospective cohort study,we evaluated TV and testis US role in the diagnostic workup of andrological *** consecutive outpatients undergoing single-operator testis US(Modena,Italy)from March 2012 to March 2018 were enrolled,matching sonographic,hormonal,and seminal data.A total of 302 men were referred and evaluated for gynecomastia,suspected hypogonadism,couple infertility(Cl),or sexual *** the hypogonadal group,TV was lower compared to that in other groups(P<0.001),and a significant,direct correlation between TV and testosterone level was observed in nonandrogen-treated patients(R=0.911,P<0.001),suggesting that testicular size could be related to the testosterone-secreting *** the Cl group,normozoospermic patients showed higher TV compared to men with impaired semen quality(P=0.003)and azoospermia(P=0.003).However,TV was not able to discriminate between patients presenting normal and altered semen *** the contrary,testis US inhomogeneity was more frequent in patients with impaired sperm quality(55.0%;P=0.007)and azoospermia(40.0%;P=0.012),compared to patients with normozoospermia(5%),identifying thereby the sonographic pattern as an informative parameter of the fertility ***,in the Cl workup,US evaluation seems to be more informative than the TV assessment alone.

关键词： male hypogonadism male infertility testicular diseases testis

On the calibration of rotational augmentation models for wind turbine load estimation by means of CFD simulations

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Acta Mechanica Sinica 2020年第2期36卷 306-319页

作者： Belen Soledad Burgos Tafur Elia daniele Bernhard Stoevesandt Philipp Thomas Fraunhofer IWES Am Seedeich 4527572 BremerhavenGermany Flensburg University of Applied Sciences Wind Energy Technology InstituteNordstraße224943 FlensburgGermany

In this work the improved version of an engineering model which accounts for rotational augmentation effects by means of computational fluid dynamics(CFD)calibration is explored and *** on an analysis of the NREL Phase VI wind turbine,the novel modeling is presented,which uses as base line the formulation proposed by Chaviaropoulos and *** model is calibrated based on CFD simulations using *** corresponding correction of the two dimensional polars is straightforward implemented within MoWiT,an in-house software for load *** novel formulation results in improved lift and drag coefficients prediction in all considered cases,reducing the deviation with respect to the rotating CFD cases down to few *** optimal configuration including the correction for tip effects of Shen shows better agreements at the very tip of the *** the range of applicability for large wind turbine rotor blades based on a virtual 10MW rotor model is discussed.

关键词： calculation. rotational correction

New treatments for chronic hepatitis C:an overview for paediatricians

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World Journal of Gastroenterology 2014年第43期20卷 15965-15974页

作者： daniele Serranti Giuseppe Indolfi Massimo Resti Department of Health Sciences University of Florence Paediatric and Liver Unit Meyer Children’s University Hospital of Florence

Pegylated interferon (IFN) α-2a or 2b in combination with ribavirin for children aged 3 years and older is the standard treatment for paediatric chronic hepatitis C. This treatment regimen was developed firstly in adults. In recent years, a number of direct-acting antiviral agents (DAAs) are under development for treatment of chronic hepatitis C virus (HCV) infection. These agents block viral replication inhibiting directly one of the several steps of HCV lifecycle. DAAs are classified into several categories based on their molecular target: HCV NS3/4A protease inhibitors, HCV NS5B polymerase inhibitors and HCV NS5A inhibitors. Other promising compounds are cyclophilin A inhibitors, mi-RNA122 and IFN-λ. Several new drugs associations will be developed in the near future starting from the actual standard of care. IFN-based and IFN-free regimens are being studied in adults. In this constantly evolving scenario new drug regimens targeted and suitable for children would be possible in the next future. Especially for children, it is crucial to identify the right combination of drugs with the highest potency, barrier to resistance and the best safety profile.

关键词： Hepatitis C virus Children Treatment Interferon Ribavirin Daclatasvir Sofosbuvir Efficacy Safety

Large Eddy Simulation of the By-pass Transition Process under Different Inlet Turbulence Conditions

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Journal of Thermal Science 2021年第6期30卷 2112-2121页

作者： BARSI Dario COSTA Carlo LENGANI Davide SIMONI daniele UBALDI Marina DIME-University of Genova Via Montallegro 11-16145 GenovaItaly

The transition process of the boundary layer developing over a flat plate with elevated inlet Free Stream Turbulence Intensity(FSTI)has been studied by means of Large Eddy Simulation(LES).To this purpose,four cases with different inflow disturbances have been tested varying the magnitude and the length scale of *** has been performed by using the finite-volume ANSYS Fluent *** computational domain,which was constituted by a rectangular domain with a zero thickness plate,was based on an ERCOFTAC test case in order to provide a validation with a well-known set of data by comparing the boundary layer integral parameters and mean and fluctuating streamwise velocity *** four cases were discussed within the paper by looking at classical statistical properties as well as advanced post-processing *** was shown that the decrease in the free stream turbulence level postpones the transition location,whereas the variation of the integral length scale has a very low influence on the distribution of the time-mean flow *** Orthogonal Decomposition(POD)has been applied to the instantaneous LES flow fields in order to provide a statistical representation of the structures responsible for transition and their response to free-stream turbulence intensity and length *** presence of vortical filaments parallel to the wall,typically referred as boundary layer streaks,is clearly identified;their characteristic dimensions and how they change as a function of FSTI properties were analyzed within the paper.

关键词： by-pass transition Large Eddy Simulation(LES) Proper Orthogonal Decomposition(POD) boundary layer streaks