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Deep learning to develop zero-equation based turbulence model for CFD simulations of the built environment

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Building Simulation 2024年第3期17卷 399-414页

作者： giovanni Calzolari Wei Liu Division of Sustainable Buildings Department of Civil and Architectural EngineeringKTH Royal Institute of TechnologyBrinnelvägen 23Stockholm11428Sweden

This study aims to improve the accuracy and speed of predictions for thermal comfort and air quality in built environments by creating a coupled framework between computational fluid dynamics(CFD)simulations and deep learning *** coupling approach is showcased by the development of a data-driven turbulence *** new turbulence model is built using a deep learning neural network,whose mapping structure is based on a zero-equation turbulence model for built environment simulations,and is coupled with the CFD software OpenFOAM to create a hybrid *** neural network is a standard shallow multi-layer *** number of hidden layers and nodes per layer was optimized using Bayesan optimization *** framework is trained on an indoor environment case study,as well as tested on an indoor office simulation and an outdoor building array *** show that the deep learning based turbulence model is more robust and faster than traditional two-equation Reynolds average Navier-Stokes(RANS)turbulence models,while maintaining a similar level of *** model also outperforms the standard algebraic zero-equation model due to its superior ability to generalize to various flow *** some challenges,namely the mapping constraint,the limited training dataset size and the source of generation of training data,the hybrid framework demonstrates the viability of the coupling technique and serves as a starting point for future development of more reliable and advanced models.

关键词： neural networks computational fluid dynamics(CFD) turbulence model OpenFOAM

Experimental evaluation of mechanical compression of lattice trusses made with Ti6Al4V for aerospace use

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Chinese Journal of Aeronautics 2024年第5期37卷 520-532页

作者： Carlo giovanni FERRO Sara VARETTI Paolo MAGGIORE Department of Mechanical and Aerospace Engineering Politecnico di TorinoCorso Duca degli AbruzziTorino 10124Italy

Lattice structures are three-dimensional structures composed of repeated geometrical shapes with multiple interconnected nodes,providing high strength-to-weight ratios,customizable properties,and efficient use of materials.A smart use of materials leads to reduced fuel consumption and lower operating costs,making them highly desirable for aircraft ***,the customizable properties of lattice structures allow for tailoring to specific design requirements,leading to improved performance and safety for *** advantages make lattice structures an important focus for research and development in the aviation *** paper presents an experimental evaluation of the mechanical compression properties of lattice trusses made with Ti6Al4V,designed for use in an anti-ice *** truss structures were manufactured using additive manufacturing techniques and tested under compressive loads to determine mechanical *** showed that lattice trusses exhibited high levels of compressive strength,making them suitable for use in applications where mechanical resistance and durability are critical,such as in anti-ice *** also highlight the potential of additive manufacturing techniques for the fabrication of lattice trusses with tailored mechanical *** study provides valuable insights into the mechanical behavior of Ti6Al4V lattice trusses and their potential applications in anti-ice systems,as well as other areas where high strength-to-weight ratios are *** results of this research contribute to the development of lightweight,efficient,and durable anti-ice systems for use in aviation and other industries.

关键词： Additive Manufacturing(AM) Selective Laser Sintering(SLM) Anti ice systems Lattice structures Aircraft on board systems Design of Experiments(DOE)

Polymerization of 1,3-Butadiene with Catalysts Based on Cobalt Dichloride Complexes with Aminophosphines: Switching the Regioselectivity by Varying the MAO/Co Molar Ratio

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Chinese Journal of Polymer Science 2024年第4期42卷 501-510页

作者： giovanni Ricci Anna Sommazzi Francesco Masi Alessandra Forni CNR-Istituto di Scienze e Tecnologie Molecolari“Giulio Natta”(SCITEC) via A.Corti 1220133MilanoItaly Viale giovanni XXIII 34 I-28100NovaraNOItaly Via Galvani 7 I-26866Sant’Angelo LodigianoLOItaly CNR-Istituto di Scienze e Tecnologie Molecolari“Giulio Natta”(SCITEC) via C.Golgi 1920133MilanoItaly

Several novel cobalt dichloride complexes with amino-phosphine bidentate ligands were synthesized and *** some of them single crystals were obtained and their molecular structure was determined by X-ray diffraction *** the complexes were then used in combination with MAO for the polymerization of 1,3-butadiene,obtaining polymers with different structures(i.e.,predominantly 1,2 or cis-1,4)mainly depending on the type of ligand and on the MAO/Co molar *** behavior of these novel catalysts was compared with that exhibited,in the polymerization of the same monomer,by the systems CoCl_(2)(PR3)2-MAO and CoCl_(2)(PRPh2)2-MAO(R=alkyl or cycloalkyl group),and by the systems based on cobalt dichloride complexes with various bi-and tridentate ligands(e.g.,diphosphines,bis-imines,pyridyl-imines,bis-iminopyridines).The comparison between the different systems allowed us to make some clarity about the actual and effective role played by the various types of ligands in the polymerization of conjugated dienes with catalytic systems CoCl_(2)(L)-MAO,in which L=mono-,bi-,or tri-dentate ligand.

关键词： 1,3-Butadiene Stereospecific polymerization Cobalt catalysts Regioselectivity Aminophosphine ligands Crystal structures Chelate rings

CBE Clima Tool:A free and open-source web application for climate analysis tailored to sustainable building design

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Building Simulation 2024年第3期17卷 493-508页

作者： giovanni Betti Federico Tartarini Christine Nguyen Stefano Schiavon Center for the Built Environment University of California BerkeleyBerkeleyUSA Berkeley Education Alliance for Research in Singapore SingaporeSingapore Heat and Health Research Incubator Faculty of Medicine and HealthThe University of SydneyCamperdownAustralia College of Letters and Sciences University of California BerkeleyBerkeleyUSA

Climate-responsive building design holds immense potential for enhancing comfort,energy efficiency,and environmental ***,many social,cultural,and economic obstacles might prevent the wide adoption of designing climate-adapted *** of these obstacles can be removed by enabling practitioners to easily access,visualize and analyze local climate *** CBE Clima Tool(Clima)is a free and open-source web application that offers easy access to publicly available weather files and has been created for building energy simulation and *** provides a series of interactive visualizations of the variables contained in the EnergyPlus Weather Files and several derived ones like the UTCI or the adaptive comfort *** is aimed at students,educators,and practitioners in the architecture and engineering *** its inception,Clima’s user base has exhibited robust growth,attracting over 25,000 unique users annually from across 70 *** tool is poised to revolutionize climate-adaptive building design,transcending geographical boundaries and fostering innovation in the architecture and engineering fields.

关键词： architectural design climate analysis sustainable building design web application building energy simulation open-source software

A novel approach to the dynamic response analysis of Euler-Bernoulli beams resting on a Winkler soil model and subjected to impact loads

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 389-401页

作者： Adolfo Foriero Filippo Santucci de Magistris giovanni Fabbrocino Département de génie civil et de génie des eaux Pavillon Adrien-PouliotUniversitéLavalQuébecCanada Dipartimento di Bioscienze e Territorio Universitàdegli Studi del MoliseCampobassoItaly Construction Technologies Institute National Research CouncilITC-CNRL’AquilaItaly

This work presents a novel approach to the dynamic response analysis of a Euler-Bernoulli beam resting on a Winkler soil model and subjected to an impact *** approach considers that damping has much less importance in controlling the maximum response to impulsive loadings because the maximum response is reached in a very short time,before the damping forces can dissipate a significant portion of the energy input into the *** development of two sine series solutions,relating to different types of impulsive loadings,one involving a single concentrated force and the other a distributed line load,are *** study revealed that when a simply supported Euler-Bernoulli beam,resting on a Winkler soil model,is subject to an impact load,the resulting vertical displacements,bending moments and shear forces produced along the span of the beam are considerably *** particular,the quantification of this effect is best observed,relative to the corresponding static solution,via an amplification *** computed impact amplification factors,for the sub-grade moduli used in this study,were in magnitude greater than 2,thus confirming the multiple-degree-of-freedom nature of the problem.

关键词： beam-Winkler-soil model sub-grade moduli impact load impact distributed line load dynamic solution impact amplification factor

On the optimisation of age of the air in the breathing zone of floor heating systems:The role of ventilation design

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Energy and Built Environment 2024年第1期5卷 130-142页

作者： Aminhossein Jahanbin giovanni Semprini Department of Industrial Engineering(DIN) Alma Mater Studiorum-University of BolognaViale Risorgimento 240136 BolognaItaly CIRI-Centro Interdipartimentale di Ricerca Industriale Edilizia e Costruzioni Alma Mater Studiorum-University of BolognaVia del Lazzaretto 15/540131 BolognaItaly

For a mechanically ventilated space,the nominal age of the air can be obtained by the reciprocal of the air change ***,values of the local mean age of the air in practice may differ to some extent from the nominal one since the nominal time constant employs as reference the theoretical optimum *** discrepancy could become more prominent in spaces conditioning with both ventilation and heating system where the indoor air pattern is affected by turbulent mixed convection *** importance of knowledge on the distribution of age of the air in these spaces,the present study provides insights on how ventilation design in floor heating systems can optimise the delivery of fresh air into the breathing *** this context,by establishing a computational fluid dynamic(CFD)model validated against experimental data,the local mean age of the air as well as the indoor air quality(IAQ)indices in the breathing zone of the floor heating system are examined under different ventilation *** different ventilation scenarios are regarded in order to find the optimal ventilation design in terms of the delivery of the fresh air and ventilation effectiveness in occupied ***,the integrated effects of the floor temperature and inlet supply temperature along with the ventilation design on the distribution of local age of the air are *** obtained results indicate that the up-supply ventilation strategy is more efficient than down-supply one in the ventilation effectiveness and delivery of fresh air into the breathing ***,it is shown that the mean age of the air in the breathing zone of the up-supply ventilation increases with increment of the Ri(Richardson number),whereas an increase in Ri improves the delivery of fresh air in down-supply *** a given floor temperature,the similar trend is also observed in the variation of age of the air with the characteristic temperature of supply inlet,namely the temperature difference between

关键词： Age of the air Indoor air quality Ventilation Floor heating CFD

Predicting the activity of single atom catalysts

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Science China Chemistry 2024年第9期67卷 2792-2793页

作者： giovanni Di Liberto Gianfranco Pacchioni Dipartimento di Scienza dei Materiali Università di Milano–Bicocca

For a long time, the existence of single-atom catalysts (SACs), consisting of isolated atoms stabilized in a specific support, was not detected due to limitations in available characterization techniques. Over the past two decades,however, the ability to synthesize and characterize these systems has opened the way toward designing and testing a new class of potential catalysts [1]. The possibility of using minimal quantities of precious metals is particularly interesting, given the problem of critical raw materials;

关键词： COMPLEXES

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The potential for an old-growth forest to store carbon in the topsoil:A case study at Sasso Fratino,Italy

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Journal of Forestry Research 2024年第2期35卷 23-32页

作者： Tommaso Chiti Nicola Benilli giovanni Mastrolonardo Giacomo Certini Dipartimento per la Innovazione nei Sistemi Biologici Agroalimentari e Forestali(DIBAF)Universitàdella TusciaVia San C.de Lellis Snc01100 ViterboItaly Dipartimento di Scienze e Tecnologie Agrarie AlimentariAmbientali e Forestali(DAGRI)Universitàdegli Studi di FirenzeP.le delle Cascine 1850144 FirenzeItaly

There is considerable interest devoted to oldgrowth forests and their capacity to store carbon(C)in biomass and *** of C stocks in old-growth forests are carried out worldwide,although there is a lack of information on their actual potential for C *** further understand this,soil organic carbon(SOC)was measured in one of Italy's best-preserved old-growth forests,the Sasso Fratino Integral Nature *** reserve is on the World Heritage List along with other ancient beech forests of Europe,and it is virtually untouched due to the steepness of the terrain,even before legal constraints were *** the sandstone-derived soils are often shallow,they are rich in organic ***,no quantification had been carried *** systematically sampling the topsoil across the forest,we accurately determined the average amount of SOC(62.0±16.9 Mg ha^(–1))and nitrogen(4.0±1.2 Mg ha^(–1))in the top 20 *** the CENTURY model,future dynamics of SOC stocks were predicted to 2050 according to two climate scenarios,A1F1 and B2,the first of high concern and the second more *** model projected an increase of 0.2 and 0.3 Mg ha^(–1)a^(–1)by 2030 under the A1F1 and B2 scenarios,respectively,suggesting that the topsoil in old-growth forests does not reach equilibrium but continues accumulating ***,from 2030 to 2050,a decline in SOC accumulation is predicted,indicating SOC net loss at high altitudes under the worst-case *** study confirms that soils in oldgrowth forests play a significant role in carbon *** also suggests that climate change may affect the potential of these forests to store SOC not only in the long term but also in the coming years.

关键词： Carbon sequestration CENTURY model Climate change Forest soil Soil nitrogen

Optimal orbit transfer of single-tether E-sail with inertially fixed spin axis

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Astrodynamics 2024年第2期8卷 285-295页

作者： Alessandro A.Quarta Marco Bassetto giovanni Mengali Department of Civil and Industrial Engineering University of PisaPisa I-56122Italy

This study analyzes the optimal transfer trajectory of a spacecraft propelled by a spinstabilized electric solar wind sail(E-sail)with a single conducting tether and a spin axis with a fixed direction in an inertial(heliocentric)reference *** approach proposed in this study is useful for rapidly analyzing the optimal transfer trajectories of the current generation of small spacecraft designed to obtain in-situ evidence of the E-sail propulsion *** this context,starting with the recently proposed thrust model for a single-tether E-sail,this study discusses the optimal control law and performance in a typical two-dimensional interplanetary transfer by considering the(binary)state of the onboard electron emitter as the single control *** resulting spacecraft heliocentric trajectory is a succession of Keplerian arcs alternated with propelled arcs,that is,the phases in which the electron emitter is switched *** particular,numerical simulations demonstrated that a single-tether E-sail with an inertially fixed spin axis can perform a classical mission scenario as a circle-to-circle two-dimensional transfer by suitably varying a single control parameter.

关键词： electric solar wind sail(E-sail) single conducting tether fixed inertial spin axis trajectory optimization circle-to-circle coplanar transfer