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Chip 2023年第2期2卷 16-25页

作者： Richard Soref francesco De Leonardis Engineering Department University of Massachusetts at BostonBostonMA 02125 USA Photonics Research Group Department of Electrical and Information EngineeringPolitecnico di BariVia Orabona 4Bari 70126Italy

We present a theoretical investigation,based on the tight-binding Hamiltonian,of efficient electric-field-induced three-waves mixing(EFIm)in an undoped lattice-matched short-period superlattice(SL)that integrates quasi-phase-matched(QPm)SL straight waveguides and SL racetrack resonators on an opto-electronic *** reversed DC voltage is applied to electrode segments on each side of the strip *** spectra ofχ_(xxxx)^((3))and of the linear suscepti-bility have been simulated as a function of the number of the atomic monolayers for“non-relaxed”heterointerfaces,and by considering all the transitions between valence and conduction *** large ob-tained values ofχ_(xxxx)^((3))make the(ZnS)3/(Si2)3 short-period SL a good candidate for realizing large effective second-order nonlinearity,en-abling future high-performance of the SLOI PICs and OEICs in the 1000-nm and 2000-nm wavelengths *** have made detailed calculations of the efficiency of second-harmonic generation and of the performances of the optical parametric oscillator(OPO).The re-sults indicate that the(ZnS)N/(Si2)m QPm is competitive with present PPLN technologies and is practical for classical and quantum appli-cations.

关键词： Optical waveguides Semiconductor superlattices Racetrack resonator Nonlinear optical devices Harmonic generation optical para-metric oscillator Three wave mixing SOI technology

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中性悬浮粒子流在奇异角附近的重构

Acta mechanica Sinica 2022年第8期38卷 41-48页

作者： francesco Romanò Univ.Lille CNRSONERAArts et Métiers Institute of TechnologyCentrale LilleUMR 9014-LMFL-Laboratoire de Mécanique des Fluides de Lille-Kampéde FérietUniv.LilleCNRSONERAF-59000LilleFrance

在蠕动流动条件下,针对靠近奇异角移动的颗粒进行悬浮效应修正.一些密度不匹配的粒子轨迹被用来重建整个目标区域的中性悬浮粒子的动力学.我们建议利用密度不匹配粒子的耗散动力学来探测目标区域.然后,通过重建密度不匹配颗粒流的相空间... 详细信息

在蠕动流动条件下,针对靠近奇异角移动的颗粒进行悬浮效应修正.一些密度不匹配的粒子轨迹被用来重建整个目标区域的中性悬浮粒子的动力学.我们建议利用密度不匹配粒子的耗散动力学来探测目标区域.然后,通过重建密度不匹配颗粒流的相空间,并将颗粒与流体密度比的极限值取为1,检索整个区域的中性浮力颗粒流.这种方法的鲁棒性通过对重建算子的目标函数实行有目的抖动(ill-conditioning)来证明.事实上,我们证明即使是依赖于质量不同、密度不匹配的轨道拓扑,或者依赖于密集的轨道束,而不是均匀分布的轨道,我们的算法也能很好地执行.最后讨论了该算法在微流体领域的潜在应用和改进.

关键词：悬浮粒子中性浮力微流体极限值颗粒流粒子轨迹相空间流动条件

Atomistic fracture in bcc iron revealed by active learning of Gaussian approximation potential

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npj Computational materials 2023年第1期9卷 135-145页

作者： Lei Zhang Gábor Csányi Erik van der Giessen francesco m.resca Engineering and Technology Institute Groningen Faculty of Science and EngineeringUniversity of GroningenNijenborgh 49747 AG GroningenThe Netherlands Engineering Laboratory University of CambridgeCambridge CB21PZUK Zernike Institute for Advanced materials University of GroningenNijenborgh 49747 AG GroningenThe Netherlands

The prediction of atomistic fracture mechanisms in body-centred cubic(bcc)iron is essential for understanding its semi-brittle *** atomistic simulations of the crack-tip under mode-I loading based on empirical interatomic potentials yield contradicting predictions and artificial *** enable fracture prediction with quantum accuracy,we develop a Gaussian approximation potential(GAP)using an active learning strategy by extending a density functional theory(DFT)database of ferromagnetic bcc *** apply the active learning algorithm and obtain a Fe GAP model with a converged model uncertainty over a broad range of stress intensity factors(SIFs)and for four crack *** learning efficiency of the approach is analysed,and the predicted critical SIFs are compared with Griffith and Rice *** simulations reveal that cleavage along the original crack plane is the atomistic fracture mechanism for{100}and{110}crack planes at T=0 K,thus settling a long-standing *** work also highlights the need for a multiscale approach to predicting fracture and intrinsic ductility,whereby finite temperature,finite loading rate effects and pre-existing defects(e.g.,nanovoids,dislocations)should be taken explicitly into account.

关键词： approximation potential apply

A finite element analysis(FEA)approach to simulate the coefficient of friction of a brake system starting from material friction characterization

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Friction 2021年第1期9卷 191-200页

作者： Gabriele RIVA francesco VARRIALE Jens WAHLSTRÖm Brembo S.p.A. Stezzano(BG)Stezzano(BG)24040Italy KTH Royal Institute of Technology Stockholm 11428Sweden Department of mechanical Engineering Lund UniversityLund 22100Sweden

The coefficient of friction(COF)is one of the most important parameters to evaluate the performance of a brake *** design proper brake systems,it is important to know the COF when estimating the brake force and resulting *** is challenging to simulate the COF since friction in disc brakes is a complex phenomenon that depends on several parameters such as sliding velocity,contact pressure,materials,and temperatures,*** is a lack of studies found in the literature focusing on simulation of the COF for a full brake system based on tribometer material *** aim of this work is therefore to investigate the possibility to use a finite element analysis(FEA)approach combined with a COF pv-map to compute the global COF of a disc brake *** local COF is determined from a pv-map for each local sliding velocity and contact pressure determined by the *** the local COF,the braking force of the entire brake system and the global COF can be *** obtained by the simulation are compared with dyno bench test of the same brake system to investigate the validity of the simulation *** show that the simulation is perfectly in line with the experimental measurements in terms of in-stop COF development,but slightly higher with a positive offset for every braking.

关键词： disc brakes friction coefficient simulation brake performance pin-on-disc

Heterointerface of all-alkynyl-protected Au_(28) nanoclusters anchored on NiFe-LDHs boosts oxygen evolution reaction:a case to unravel ligand effect

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Rare metals 2023年第12期42卷 4029-4038页

作者： Quan-Li Shen Long-Yun Shen Le-Yi Chen Lu-Bing Qin Yong-Gang Liu Nicholas m.Bedford francesco Ciucci Zheng-Hua Tang School of Environment and Energy Guangzhou Higher Education Mega CentreNew Energy Research InstituteSouth China University of TechnologyGuangzhou 510006China Division of Emerging Interdisciplinary Areas The Hong Kong University of Science and TechnologyHong Kong 999077China Department of mechanical and Aerospace Engineering The Hong Kong University of Science and TechnologyHong Kong 999077China School of Chemical Engineering University of New South Wales SydneySydneyNSW2052Australia HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute Shenzhen 518048China Energy Institute The Hong Kong University of Science and TechnologyHong Kong 999077China

Ultrasmall Au nanoclusters have been proven to effectively enhance the catalytic performance of NiFe layered double hydroxides(NiFe-LDHs)toward oxygen evolution reaction(OER),yet the surface ligand effect of the Au nanoclusters still remains ***,a systematic study is reported to examine the OER performance of NiFe-LDHs supported atom-precise all alkynyl-protected[Au_(28)(~tBuC≡C)17]~-nanoclusters(Au_(28)-Alkynyl in short)and thiolate-protected Au_(28)(TBBT)_(20)(TBBT=4-tert-butylbenzene thiol)counterp arts(Au_(28)-Thiolate in short).The Au_(28)-Alkynyl cluster has characteristic absorbance feature,and its composition is verified by mass *** possesses a drastically different structure from the reported mixed ligand protected Au_(28)***,the NiFe-LDHs loaded with Au_(28)-Alkynyl exhibited a superior OER performance than the sample loaded with Au28-Thiolate under the same conditions,evidenced by a smaller overpotential of 205 mV at the current density of 10 mA·cm^(-2)and a lower Tafel slope value of 41.0 mV·dec^(-1)in 1 mol·L^(-1)*** excellent performance is attributed to the interfaces created between the NiFe-LDHs and the Au nanoclusters,as density functional theory calculations reveal that more significant charge transfer occurs in Au_(28)-Alkynyl/NiFeLDHs catalyst,and more importantly,the energy barrier of the potential-determining step in the OER process for Au28-Alkynyl/NiFe-LDHs is much lower than that of Au28-Thiolate/NiFe-LDHs hence favors the electrocatalytic reaction.

关键词： NiFe layered double hydroxides Au_(28)nanoclusters Alkynyl ligand Oxygen evolution reaction Density functional theory calculations

A superconducting wireless energiser based on electromechanical energy conversion

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Superconductivity 2023年第3期7卷 53-64页

作者： Hongye Zhang Tianhui Yang francesco Grilli Wenxin Li Paul m.Tuohy Ying Xin Department of Electrical and Electronic Engineering The University of ManchesterManchester M139PLUnited Kingdom School of Electrical and Information Engineering Tianjin UniversityTianjin 300072China Institute for Technical Physics Karlsruhe Institute of TechnologyKarlsruhe 76131Germany

A superconducting magnet(Sm)can produce high magnetic fields up to a dozen times stronger than those generated by an electromagnet made of normal conductors or a permanent magnet(Pm),and thus has attracted increasing research efforts in many domains including medical devices,large scientific equipment,transport,energy storage,power systems,and electric *** energisers,e.g.,high temperature superconducting(HTS)flux pumps,can eliminate the thermal load from current leads and arc erosion of slip rings,and are thus considered a promising energisation tool for ***,the time‐averaged DC output voltage in existing HTS flux pumps is generated by dynamic resistance:the dynamic loss is unavoidable,and the total AC loss will become significant at high *** study introduces a highly efficient superconducting wireless energizer(SWE)designed specifically for *** SWE takes advantage of the inherent properties of a superconducting loop,including flux conservation and zero DC *** theoretical analysis,numerical modelling exploiting the H‐ϕformulation,and experimental measurements were conducted to demonstrate the efficiency and efficacy of the novel SWE *** electromechanical performance and loss characteristics of the SWE system have also been *** to conventional HTS flux pumps,the proposed SWE has lower excitation loss,in the order of 10−1 mW,and thus can achieve a high system efficiency of no less than 95%.Furthermore,it has a simpler structure with higher reliability,considered ready for further industrial *** addition to deepening the understating of the intricate electromechanical dynamics between magnetic dipoles and superconducting circuits,this article provides a novel wireless energisation technique for Sms and opens the way to step changes in future electric transport and energy sectors.

关键词： Wireless energisation Superconducting magnet High temperature superconductor Electromechanical energy conversion Electric transport

THE ONE-DImENSIONAL HUGHES mODEL FOR PEDESTRIAN FLOW:RIEmANN-TYPE SOLUTIONS

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Acta mathematica Scientia 2012年第1期32卷 259-280页

作者： Debora Amadori m.Di francesco Dipartimento di matematica Pura e Applicata Universita degli Studi dell'Aquila Departament de matematiques Universitat Autonoma de Barcelona

This paper deals with a coupled system consisting of a scalar conservation law and an eikonal equation, called the Hughes model. Introduced in [24], this model attempts to describe the motion of pedestrians in a densely crowded region, in which they are seen as a ＇thinking＇（continuum） fluid. The main mathematical difficulty is the discontinuous gradient of the solution to the eikonal equation appearing in the flux of the conservation law. On a one dimensional interval with zero Dirichlet conditions （the two edges of the interval are interpreted as ＇targets＇）, the model can be decoupled in a way to consider two classical conservation laws on two sub-domains separated by a turning point at which the pedestrians change their direction. We shall consider solutions with a possible jump discontinuity around the turning point. For simplicity, we shall assume they are locally constant on both sides of the discontinuity. We provide a detailed description of the local- in-time behavior of the solution in terms of a ＇global＇ qualitative property of the pedestrian density （that we call ＇relative evacuation rate＇）, which can be interpreted as the attitude of the pedestrians to direct towards the left or the right target. We complement our result with explicitly computable examples.

关键词： pedestrian flow nonlocal conservation law eikonal equation

Designs andmethodologies to recreate in vitro human gutmicrobiota models

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Bio-Design and manufacturing 2023年第3期6卷 298-318页

作者： francesco Biagini Costanza Daddi marco Calvigioni Carmelo De maria Yu Shrike Zhang Emilia Ghelardi Giovanni Vozzi Research Center(E.Piaggio) University of PisaPisaItaly Department of Information Engineering University of PisaPisaItaly Department of Translational Research and New Technologies in medicine and Surgery University of PisaPisaItaly Division of Engineering in medicine Department of MedicineBrigham and Women’s HospitalHarvard Medical SchoolCambridgeMAUSA

The human gut microbiota is widely considered to be a metabolic organ hidden within our bodies,playing a crucial role in the host’s *** factors affect its composition,so a wide variety of microbes residing in the gut are present in the world *** excessive imbalances in microbial composition are often associated with human disorders and pathologies,and new investigative strategies to gain insight into these pathologies and define pharmaceutical therapies for their treatment are *** vitro models of the human gut microbiota are commonly used to study microbial fermentation patterns,community composition,and host-microbe *** and microfluidic devices have been designed to culture microorganisms from the human gut microbiota in a dynamic environment in the presence or absence of eukaryotic cells to interact *** this review,we will describe the overall elements required to create a functioning,reproducible,and accurate in vitro culture of the human gut *** addition,we will analyze some of the devices currently used to study fermentation processes and relationships between the human gut microbiota and host eukaryotic cells.

关键词： Gut microbiota In vitro models Bioreactors Host-microbiome Fermentation

Plot investigation on rill flow resistance due to path tortuosity

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International Soil and Water Conservation Research 2023年第4期11卷 602-609页

作者： francesco G.Carollo Costanza Di Stefano Alessio Nicosia Vincenzo Palmeri Vincenzo Pampalone Vito Ferro Department of Agricultural Food and Forest SciencesUniversity of PalermoViale delle ScienzeBuilding 490128PalermoItaly NBFC National Biodiversity Future Center90133PalermoItaly

The path tortuosity t is an indicator of rill morphology accounting for the deviation of the thalweg from a straight *** effect of t on flow resistance has been little investigated for *** paper reports the results of a plot investigation aimed to establish the suitable accuracy of the rill thalweg measurement to determine the tortuosity parameter and to test the reliability of a theoretical flow resistance *** rills were incised in clay soil(CS)and clay-loam soil(LS)and shaped by a clear flow *** three-dimensional Digital Terrain models were created by the Structure from motion *** rills on LS,an approximate thalweg was tracked by photo-interpretation,and a specific calculation routine was applied to identify the cross sections with a constant spacing *** actual rill thalweg was obtained as the line joining the lowest points of these *** the different tested d values,d=0.075 m was chosen to determine *** both CS and LS,the Darcy-Weisbach friction factorffeatured a non-monotonic relation with t,which was explained as the result of three additive components due to bed roughness,sediment transport,and localized energy losses due to *** effect of the former two components onff contrasts that of the third,resulting in a linearly decreasing f-t relationship and constant flow velocity for the three lowest tortuosity values,and an increased friction factor and reduced flow velocity for the highest tortuosity *** flow resistance law was positively tested,and the predicted friction factor was dependent on t.

关键词： Rill erosion Tortuosity Rill morphology Friction factor Rill flow resistance

Phase diagram of a distorted kagome antiferromagnet and application to Y-kapellasite

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npj Computational materials 2022年第1期8卷 79-88页

作者： max Hering francesco Ferrari Aleksandar Razpopov Igor I.mazin Roser Valentí Harald O.Jeschke Johannes Reuther Helmholtz-Zentrum Berlin für materialien und Energie Hahn-Meitner Platz 114109BerlinGermany Dahlem Center for Complex Quantum Systems and Fachbereich Physik Freie Universität Berlin14195BerlinGermany Institute for Theoretical Physics Goethe University FrankfurtMax-von-Laue-Straße 160438Frankfurt am MainGermany Department of Physics and Astronomy and Quantum Science and Engineering CenterGeorge Mason UniversityFairfaxVA22030USA Research Institute for Interdisciplinary Science Okayama UniversityOkayama700-8530Japan

We investigate the magnetism of a previously unexplored distorted spin-1/2 kagome model consisting of three symmetry-inequivalent nearest-neighbor antiferromagnetic Heisenberg couplings J_(■),J,and J′,and uncover a rich ground state phase diagram even at the classical *** analytical arguments and numerical techniques we identify a collinear Q^(→)=0 magnetic phase,two unusual non-collinear coplanar Q^(→)=(1/3,1/3)phases and a classical spin liquid phase with a degenerate manifold of non-coplanar ground states,resembling the jammed spin liquid phase found in the context of a bond-disordered kagome *** further show with density functional theory calculations that the recently synthesized Y-kapellasite Y_(3)Cu_(9)(OH)_(19)C_(l8) is a realization of this model and predict its ground state to lie in the region of Q^(→)=(1/3,1/3)order,which remains stable even after the inclusion of quantum fluctuation effects within variational monte Carlo and pseudofermion functional renormalization *** presented model opens a new direction in the study of kagome antiferromagnets.

关键词： group distorted diagram