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Transition Modelling Implications in the CFD Analysis of a Turbine Nozzle Vane Cascade Tested Over a Range of Mach and Reynolds Numbers

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Journal of Thermal Science 2015年第6期24卷 526-534页

作者： michele Marconcini Roberto Pacciani Andrea Arnone University of Florence Department of Industrial Engineering Via Santa Marta

The aerodynamic performance of a gas turbine nozzle vane cascade was investigated over a range of Mach and Reynolds *** work is part of a vast research project aimed at the analysis of fluid dynamics and heat transfer phenomena in cooled *** this paper computed results on the"solid vane"(without cooling devices)are presented and discussed in comparison with experimental *** measurements were provided by the University of Bergamo where the experimental campaign was carried out by means of a subsonic wind *** impact of boundary layer transition is investigated by using a novel laminar kinetic energy transport model and the widely used Langtry-Menterγ-Reθ,t *** comparison between calculations and measurements is presented in terms of blade loading distributions,total pressure loss coefficient contours downstream of the cascade,and velocity/turbulence-intensity profiles within the boundary layer at selected blade surface locations at *** will be shown how transitional calculations compare favorably with experiments.

关键词： Gas turbine CFD validation transition model secondary flows

Thermal conductivity of glasses: first-principles theory and applications

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npj Computational Materials 2023年第1期9卷 1253-1274页

作者： michele Simoncelli Francesco Mauri Nicola Marzari Theory of Condensed Matter Group of the Cavendish Laboratory University of CambridgeCambridgeUK Dipartimento di Fisica Universitàdi Roma La SapienzaRomaItaly Theory and Simulation of Materials(THEOS)and National Centre for Computational Design and Discovery of Novel Materials(MARVEL) École Polytechnique Fédérale de LausanneLausanneSwitzerland

Predicting the thermal conductivity of glasses from first principles has hitherto been a very complex *** established Allen-Feldman and Green-Kubo approaches employ approximations with limited validity—the former neglects anharmonicity,the latter misses the quantum Bose-Einstein statistics of vibrations—and require atomistic models that are very challenging for first-principles ***,we present a protocol to determine from first principles the thermal conductivityκ(T)of glasses above the plateau(i.e.,above the temperature-independent region appearing almost without exceptions in theκ(T)of all glasses at cryogenic temperatures).The protocol combines the Wigner formulation of thermal transport with convergence-acceleration techniques,and accounts comprehensively for the effects of structural disorder,anharmonicity,and Bose-Einstein *** validate this approach in vitreous silica,showing that models containing less than 200 atoms can already reproduceκ(T)in the macroscopic *** discuss the effects of anharmonicity and the mechanisms determining the trend ofκ(T)at high temperature,reproducing experiments at temperatures where radiative effects remain negligible.

关键词： glasses conductivity harmonic

Quantifying the contribution of the root system of alpine vegetation in the soil aggregate stability of moraine

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International Soil and Water Conservation Research 2017年第1期5卷 36-42页

作者： Csilla Hudek Silvia Stanchi michele D’Amico michele Freppaz University of Torino DISAFA(Department of AgriculturalForest and Food Sciences)Largo Paolo Braccini2Grugliasco 10095TOItaly Train2Move Fellowship University of TorinoDISAFA(Department of AgriculturalForest and Food Sciences)Largo Paolo Braccini2Grugliasco 10095TOItaly

One fifth of the world's population is living in mountains or in their surrounding *** anthropogenic pressure continues to grow with the increasing number of settlements,especially in areas connected to touristic activities,such as the Italian *** process of soil formation on high mountains is particularly slow and these soils are particularly vulnerable to soil *** alpine regions,extreme meteorological events are increasingly frequent due to climate change,speeding up the process of soil degradation and increasing the number of severe erosion processes,shallow landslides and debris *** cover plays a crucial role in the stabilization of mountain soils thereby reducing the risk of natural hazards effecting downslope *** aggregate stability is one of the main soil properties that can be linked to soil loss *** developed on moraines in recently deglaciated areas typically have low levels of soil aggregation,and a limited or discontinuous vegetation cover making them more susceptible to ***,soil structure can be influenced by the root system of the *** are actively involved in the formation of water-stable soil aggregation,increasing the stability of the soil and its nutrient *** the present study,we aim to quantify the effect of the root system of alpine vegetation on the soil aggregate stability of the forefield of the Lys glacier,in the Aosta Valley(NW-Italy).This proglacial area provides the opportunity to study how the root system of ten pioneer alpine species from different successional stages can contribute to soil development and soil *** quantify the aggregate stability of root permeated soils,a modified wet sieving method was *** root length per soil volume of the different species was also determined and later correlated with the aggregate stability *** results showed that soil aggregate stability was significantly increased by the presence

关键词： Soil aggregate stability Root length density Pioneer alpine species Glacier forefield

Compact n-Manifolds via(n+l)-Colored Graphs:a New Approach

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Algebra Colloquium 2020年第1期27卷 95-120页

作者： Luigi Grasselli michele Mulazzani Dipartimcnto di Scicnze e Metodi dell'Ingegneria Universita di Modena e Reggio Emilia Via Giovanni Amendola2-Pad.Morselli 42122 Reggio EmiliaItaly Dipartimento di Matematica and ARCES Universita di Bologna Piazza di Porta San Donato 540126 BolognaItaly

We introduce a representation via(n+l)-colored graphs of compact n-manifolds with(possibly empty)boundary,which appears to be very convenient for computer aided study and *** construction is a generalization to arbitrary dimension of the one recently given by Cristofori and Mulazzani in dimension three,and it is dual to the one given by Pezzana in the *** this context we establish some results concerning the topology of the represented manifolds:suspensions,fundamental groups,connected sums and moves between graphs representing the same *** results of compact orientable 4-manifolds representable by graphs up to six vertices are obtained,together with some properties of the G-degree of 5-colored graphs relating this approach to tensor models theory.

关键词： compact manifolds colored graphs fundamental groups dipole moves

Sarcopenia, obesity and postoperative outcomes after hepatectomy for hepatocellular carcinoma

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Hepatobiliary Surgery and Nutrition 2020年第2期9卷 198-201页

作者： michele Molinari Department of Surgery University of Pittsburgh Medical CenterPittsburghPAUSA

Over the last few decades,we have learned that the composition of our body is directly related to our *** second and equally important lesson is that when we define a healthy body,we have to go beyond the ratio between the weight and the height of a *** third lesson is that even though a"normal"balance between body fat and muscle is associated with good health and longevity,we still do not know what a"normal body composition"*** bodies can be classified in three main phenotypes based on the work of William Sheldon(1),a constitutional psychologist who worked at Harvard University in the *** three phenotypes are:ectomorphic,mesomorphic and *** we have certain tendency toward one group or the other,the level or physical activity,diet,age,gender or the presence of diseases have a profound impact that can make us migrate from one phenotype to another over time(2).

关键词： obesity diseases migrate

SPH numerical investigation of the characteristics of an oscillating hydraulic jump at an abrupt drop

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Journal of Hydrodynamics 2018年第1期30卷 106-113页

作者： Diana De Padova michele Mossa Stefano Sibilla Department of Civil Environmental Land Building Engineering and ChemistryPolytechnic University of Bari Department of Civil Engineering and Architecture University of Pavia

This paper shows the results of the smooth particle hydrodynamics（SPH） modelling of the hydraulic jump at an abrupt drop,where the transition from supercritical to subcritical flow is characterised by several flow patterns depending upon the inflow and tailwater conditions. SPH simulations are obtained by a pseudo-compressible XSPH scheme with pressure smoothing; turbulent stresses are represented either by an algebraic mixing-length model, or by a two-equation k-ε model. The numerical model is applied to analyse the occurrence of oscillatory flow conditions between two different jump types characterised by quasi-periodic oscillation,and the results are compared with experiments performed at the hydraulics laboratory of Bari Technical University. The purpose of this paper is to obtain a deeper understanding of the physical features of a flow which is in general difficult to be reproduced numerically,owing to its unstable character： in particular, vorticity and turbulent kinetic energy fields, velocity, water depth and pressure spectra downstream of the jump, and velocity and pressure cross-correlations can be computed and analysed.

关键词： Hydraulic jumps smoothed particle hydrodynamics(SPH) models oscillating characteristics

Experimental and Numerical Simulations of Flow and Heat Transfer in Heat Exchanger Elements Using Liquid Crystal Thermography

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Journal of Thermal Science 2004年第2期13卷 133-137页

作者： Jan STASIEK michele CIOFALO Maciej WIERZBOWSKI Heat Technology Dept. Gdansk Univ. of Technology Narutowicza 11/12 80-952 Gdansk PolandUniversity of Palermo Dipartimento Ingeneria Nucleare Viale delle Scienze I-90128 Palermo ItalyHeat Technology Dept. Gdansk Univ. of Technology Narutowicza 11/12 80-952 Gdansk Poland

Experimental and numerical investigation of heat transfer and fluid flow were conducted for classic heat exchanger elements (flat plate with fin-tubes in-line, staggered and with vortex generators) and corrugated-undulated ducts under transitional and weakly turbulent *** dependence of average heat transfer and pressure drop on Reynolds number and geometrical parameters was investigated. Distributions of local heat transfer coefficient were obtained by using liquid crystal thermography and surface-averaged values were computed. Three-dimensional numerical simulations were conducted by a finite-volume method using a low-Reynolds number k-e model under the assumption of fully developed flow. Computed flow fields provided otherwise inaccessible information on the flow patterns and the mechanisms of heat transfer enhancement.

关键词： liquid crystal thermography heat transfer enhancement.

Tight-binding models for ultracold atoms in optical lattices：general formulation and applications

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Science China(Physics,Mechanics & Astronomy) 2016年第6期59卷 1-23页

作者： michele Modugno Julen Ibanez-Azpiroz Giulio Pettini Departamento de Fisica Teorica e Historia de la Ciencia Universidad del Pais Vasco UPV/EHU Bilbao 48080 Spain IKERBASQUE Basque Foundation for Science Bilbao 48011 Spain Peter Griinberg Institute and Institute for Advanced Simulation Forschungszentrum Jiilich & JARA Jiilich D-52425 Germany Dipartimento di Fisica e Astronomia Universita di Firenze and INFN Sesto Fiorentino 50019 Italy

Tight-binding models for ultracold atoms in optical lattices can be properly defined by using the concept of maximally localized Wannier functions for composite bands. The basic principles of this approach are reviewed here, along with different applications to lattice potentials with two minima per unit cell, in one and two spatial dimensions. Two independent methods for computing the tight-binding coefficients—one ab initio, based on the maximally localized Wannier functions, the other through analytic expressions in terms of the energy spectrum—are considered. In the one dimensional case, where the tight-binding coefficients can be obtained by designing a specific gauge transformation, we consider both the case of quasi resonance between the two lowest bands, and that between s and p orbitals. In the latter case, the role of the Wannier functions in the derivation of an effective Dirac equation is also reviewed. Then, we consider the case of a two dimensional honeycomb potential, with particular emphasis on the Haldane model, its phase diagram, and the breakdown of the Peierls substitution. Tunable honeycomb lattices, characterized by movable Dirac points, are also considered. Finally, general considerations for dealing with the interaction terms are presented.

关键词： ultracold atoms optical lattices tight-binding models Wannier functions effective Dirac equation honeycomb lattices

Covariation between plant biodiversity and soil systems in a European beech forest and a black pine plantation:the case of Mount Faito,(Campania,Southern Italy)

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Journal of Forestry Research 2022年第1期33卷 239-252页

作者： Tiziana Danise michele Innangi Elena Curcio Antonietta Fioretto Department of Environmental Biological and Pharmaceutical Sciences and TechnologiesUniversity of Campania“Luigi Vanvitelli”Via Vivaldi 4381100 CasertaItaly

Both climate and land-use changes,including the introduction and spread of allochthonous species,are forecast to affect forest ***,forests will be affected in terms of species composition as well as their soil chemical and biological *** possible changes in both tree cover and soil system might impact the amount of carbon that is stored in living plants and dead biomass and within the soil ***,such alterations can have a strong impact on the detrital food web that is linked to litter *** there are studies on the infuence of plant diversity on soil physical and chemical characteristics,the effects on soil biological activity and carbon storage processes remain largely *** aim of this study was to investigate and compare chemical and biological variables in covariation with plant communities in an autochthonous beech forest(Fagus sylvatica L.)and a black pine plantation(Pinus nigra *** ***).Our results confirmed that the two communities were considerably different,with the old-growth beech community having a lower number of plant species and the pine community was in development as a consequence of anthropogenic *** aspects of the two communities were also refected in the soil,with the beech soil having higher nitrogen levels and a more specialized microbial community compared to the pine soil,with most extracellular enzymes(such as peroxidase and chitinase)showing lower activity in the pine soil.

关键词： 2B-PLS Plant and soil Vegetation Soil enzymes