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SPH Particle Collisions for the Reduction of Particle Clustering, Interface Stabilisation and Wall Modelling

Journal of Applied Mathematics and Physics 2018年第9期6卷 1860-1882页

作者： Arno Kruisbrink Stan Korzilius Frazer Pearce hervé morvan Gas Turbine and Transmission Research Centre University of Nottingham Nottingham UK Centre for Analysis Scientific Computing and Applications Eindhoven University of Technology Eindhoven The Netherlands

The pair-wise forces in the SPH momentum equation guarantee the conservation of momentum, but they cannot prevent particle clustering and wall penetration. Particle clustering may occur for several reasons. A fundamental issue is the tensile instability, which is caused by negative numerical pressures. Clustering may also occur due to certain properties of the kernel gradient. Discontinuities in the pressure and its gradient, due to surface tension and gravity, may cause particle instabilities near the interface between two fluids. Wall penetration is also a form of particle clustering. In this paper the particle collision concept is introduced to suppress particle clustering. Here, the use of kinematic conditions (motion) rather than dynamic conditions (forces) is explored. These kinematic conditions are obtained from kinetic collision theory. Conservation of momentum is maintained, and under elastic conditions conservation of energy as well. The particle collision model only becomes active when needed. It may be seen as a particle shifting method, in the sense that the velocities are changed, and as a consequence of that the particle positions change. It is demonstrated in several case studies that the particle collision model allows for realistic (low) viscosities. It was also found to stabilise the interface between two fluids up to high, realistic density ratios (1000:1) in typical liquid-gas applications. As such it can be used as a multi-fluid model. The concept allows for real wave speed ratios (and far beyond), which, as well as real viscosities, are essential in the modelling of heat transfer applications. The collisions with walls allow for no-slip conditions at real viscosities while wall penetration is suppressed. In summary, the particle collision model makes SPH more robust for engineering.

关键词： SPH Particle Clustering Multiphase Flow Interface Stabilisation Wall Modelling

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Full-fat insect meals in ruminant nutrition:in vitro rumen fermentation characteristics and lipid biohydrogenation

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Journal of Animal Science and Biotechnology 2023年第3期14卷 1102-1117页

作者： Manuela Renna Mauro Coppa Carola Lussiana Aline Le morvan Laura Gasco Gaelle Maxin Department of Veterinary Sciences University of TurinLargo P.Braccini 210095 GrugliascoTOItaly Independent Researcher Universite Clermont AuvergneINRAEVetAgro SupUMR 1213 HerbivoresSaint‑Genes‑ChampanelleFrance Department of Agricultural Forest and Food SciencesUniversity of TurinLargo P.Braccini 210095 GrugliascoTOItaly Universite Clermont Auvergne INRAEVetAgro SupUMR 1213 HerbivoresSaint‑Genes‑ChampanelleFrance.

Background:The most used protein sources in ruminant nutrition are considered as having negative impacts in terms of environmental sustainability and competition with human ***,the investigation of alternative and sustainable feedstuffs is becoming a priority in ruminant production ***:This trial was designed to evaluate eight full-fat insect meals(Acheta domesticus–ACD;Alphitobius diaperinus–ALD;Blatta lateralis–BL;Gryllus bimaculatus–GB;Grylloides sygillatus–GS;Hermetia illucens–HI;Musca domestica–MD;and Tenebrio molitor–TM)as potential protein and lipid sources in ruminant *** parameters and fatty acids(FA)of rumen digesta after 24-h in vitro ruminal incubation of the tested insect meals were measured and compared with those of three plant-based meals(soybean meal,rapeseed meal and sunflower meal)and fishmeal(FM).Similarly to FM,the insect meals led to a significantly lower total gas production(on average,1.75vs.4.64 mmol/g dry matter-DM),methane production(on average,0.33 vs.0.91 mmol/g DM),volatile FA production(on average,4.12 vs.7.53 mmol/g DM),and in vitro organic matter disappearance(on average,0.32 vs.0.59 g/g)than those observed for the plant *** insect meals also led to lower ammonia of rumen fluid,when expressed as a proportion of total N(on average,0.74 vs.0.52 for the plant and insect meals,respectively),which could be an advantage provided that intestinal digestibility is *** in ruminal fermentation parameters between the insect meals could be partially explained by their chitin,crude protein and ether extract contents,as well as by their FA *** particular,high content of polyunsaturated FA,or C12:0(in HI),seems to partially inhibit the ruminal ***:The tested full-fat insect meals appear to be potentially an interesting protein and lipid source for ruminants,alternative to the less sustainable and commonly used ones of plant *** FA profile of the rum

关键词： Ammonia Fatty acids In vitro digestibility Methane Nutritive value

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Three-and two-dimensional calculations for the interface anisotropy dependence of magnetic properties of exchange-spring Nd2Fe(14)B/α-Fe multilayers with out-of-plane easy axes

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Chinese Physics B 2020年第3期29卷 389-395页

作者： Qian Zhao Xin-Xin He Francois-Jacques morvan Guo-Ping Zhao Zhu-Bai Li Inner Mongolia Key Laboratory for Utilization of Bayan Obo Multi-Metallic Resources Elected State Key LaboratoryDepartment of Applied PhysicsCollege of ScienceInner Mongolia University of Science and TechnologyBaotou 014010China Ningbo Institute of Industrial Technology Chinese Academy of SciencesNingbo 315201China College of Physics and Electronic Engineering Sichuan Normal UniversityChengdu 610066China

Hysteresis loops,energy products and magnetic moment distributions of perpendicularly oriented Nd2Fe(14)B/α-Fe exchange-spring multilayers are studied systematically based on both three-dimensional(3D)and one-dimensional(1D)micromagnetic methods,focused on the influence of the interface *** calculated results are carefully compared with each *** interface anisotropy effect is very palpable on the nucleation,pinning and coercive fields when the soft layer is very ***,as the soft layer thickness increases,the pinning and coercive fields are almost unchanged with the increment of interface anisotropy though the nucleation field still monotonically *** interface anisotropy decreases the maximum energy products and increases slightly the angles between the magnetization and applied *** magnetic moment distributions in the thickness direction at various applied fields demonstrate a progress of three-step magnetic reversal,i.e.,nucleation,evolution and irreversible motion of the domain *** above results calculated by two models are in good agreement with each ***,the in-plane magnetic moment orientations based on two models are *** 3D calculation shows a progress of generation and disappearance of vortex state,however,the magnetization orientations within the film plane calculated by the 1D model are *** results suggest that negative interface anisotropy is necessarily avoided experimentally.

关键词： micromagnetics interface anisotropy Nd2Fe(14)B/α-Fe multilayers magnetic properties

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Effect of exchange coupling on magnetic property in Sm–Co/α-Fe layered system

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Chinese Physics B 2016年第3期25卷 380-386页

作者：桑成祥赵国平夏卫星万秀琳 F J morvan 张溪超谢林华张健杜娟闫阿儒刘平 College of Physics and Electronic Engineering Sichuan Normal University Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Material Technology and EngineeringChinese Academy of Sciences Department of Physics University of Texas at Arlington

The hysteresis loops as well as the spin distributions of Sm-Co/a-Fe bilayers have been investigated by both three- dimensional （3D） and one-dimensional （1D） micromagnetic calculations, focusing on the effect of the interface exchange coupling under various soft layer thicknesses ts. The exchange coupling coefficient Alas between the hard and soft ,layers varies from 1.8 x10-6 erg/cm to 0.45 x 10-6 erg/cm, while the soft layer thickness increases from 2 nm to 10 nm. As the exchange coupling decreases, the squareness of the loop gradually deteriorates, both pinning and coercive fields rise up monotonically, and the nucleation field goes down. On the other hand, an increment of the soft layer thickness leads to a significant drop of the nucleation field, the deterioration of the hysteresis loop squareness, and an increase of the remanence. The simulated loops based on the 3D and 1D methods are consistent with each other and in good agreement with the measured loops for Sm-Co/a-Fe multilayers.

关键词： hysteresis loops exchange coupling micromagnetics hard/soft bilayers

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Laser sources for microwave to millimeter-wave applications [Invited]

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Photonics Research 2014年第4期2卷 70-79页

作者： Gaël Kervella Jeremy Maxin Mickael Faugeron Perrine Berger Hadrien Lanctuit Gregoire Pillet Loïc morvan Frédéric van Dijk Daniel Dolfi III-V Lab a Joint Laboratory of Alcatel Lucent Bell LabsThales Research&Technologyand CEA-LETICampus Polytechnique1Av.A.Fresnel91767 PalaiseauFrance Thales Research and Technology Campus Polytechnique1Av.A.Fresnel91767 PalaiseauFrance

We present several laser sources dedicated to advanced microwave photonic applications.A quantum-dash mode-locked laser delivering a high-power,ultra-stable pulse train is first *** measure a linewidth below 300 kHz at a 4.3 GHz repetition rate for an output power above 300 mW and a pulse duration of 1.1 ps after compression,making this source ideal for microwave signal sampling applications.A widely tunable(5–110 GHz),monolithic millimeter-wave transceiver based on the integration of two semiconductor distributed feedback lasers,four amplifiers,and two high-speed uni-traveling carrier photodiodes is then presented,together with its application to the wireless transmission of data at 200 Mb∕s.A frequency-agile laser source dedicated to microwave signal processing is then *** delivers arbitrary frequency sweeps over 20 GHz with high precision and high speed(above 400 GHz∕ms).Finally,we report on a low-noise(below 1 kHz linewidth),solid-state,dual-frequency laser *** allows independent tuning of the two frequencies in the perspective of the implementation of a tunable optoelectronic oscillator based on a high-Q optical resonator.

关键词： millimeter tunable tuning

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交换弹簧和交换偏置反转机制的理论研究

交换弹簧和交换偏置反转机制的理论研究

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作者： Francois Jacques morvan（李文瀚）四川师范大学

学位级别：硕士

磁性材料在日常生活中变得越来越重要,广泛地运用在车、手机和电脑中。其中,交换偏置和交换弹簧是纳米复合磁体中出现的两个有趣的物理现象,有着很重要的应用前景。前者出现在交换耦合的铁磁/反铁磁体系,而后者出现在硬磁/软磁复合体系... 详细信息

磁性材料在日常生活中变得越来越重要,广泛地运用在车、手机和电脑中。其中,交换偏置和交换弹簧是纳米复合磁体中出现的两个有趣的物理现象,有着很重要的应用前景。前者出现在交换耦合的铁磁/反铁磁体系,而后者出现在硬磁/软磁复合体系。因为硬磁相提供的较大矫顽力(Hc)与软磁相提供的较大剩磁(Mr),所以交换弹簧体系的主要特性是其具有较高的最大磁能积((BH)max)。由于交换偏置里面的铁磁/反铁磁耦合作用,该体系的磁滞回线从起始点发生偏移。本论文基于微磁学计算方法,运用OOMMF软件和Fortran程序来研究Nd2Fel4B/Fe65Co35和Nd2Fe14B/α-Fe交换弹簧体系的磁特性。对NiFe/FeMn交换偏置体系的研究基于一个总自由能量方程,根据合理的边界条件可得出其磁滞回线和其它磁特性。主要研究如下：***2Fe14B/Fe65Co35体系的软磁相厚度影响的研究,以及Nd2Fe14B/α-Fe体系的易轴分布和界面扩散影响的研究。我们发现软磁相越厚,饱和磁化强度越高,而矫顽力和剩磁越低。在交换弹簧体系,我们发现易轴分布和界面扩散是不可避免的现象,因此在计算最大磁能积时要考虑到它们的影响。2.两个基于能量极小值原理的交换偏置理论模型(Mauri模型和HIDW模型)的计算模拟,由此可得出NiFe/FeMn体系的磁滞回线以及与实验值的比较。我们也比较了这两个模型的能量极小值曲线。在HIDW模型里面,清晰地表示出了铁磁相畴壁的厚度随外场强度的变化情况。

关键词：交换弹簧交换偏置磁滞回线微磁学计算

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A 13-parameter model for unsaturated soil based on bounding surface plasticity

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Journal of Rock Mechanics and Geotechnical Engineering 2010年第2期2卷 135-142页

作者： H.Wong M.morvan D.Branque Département Génie Civil et Batiment Université de LyonEcole Nationale des Travaux Publics de L'Etat

A few constitutive models for unsaturated soils have already been proposed,however,many classic models such as the Barcelona basic model can simulate neither complex volumetric soil behaviour（without forgetting its supreme merit of being the first consistently and rigorously formulated model） nor post-peak softening,and most advanced models generally comprise a large number of parameters making them more difficult to be applied to practical *** this paper,we present a new model for unsaturated soils based on an existing model developed originally for saturated *** comprises a minimum number of constitutive *** extension to unsaturated state is achieved by following a general methodology previously developed in our *** capacities of this simple model are *** only 13 parameters,it can reproduce the basic behaviour of unsaturated soils such as rebound or collapse upon wetting,depending on the stress *** can also reproduce post-peak softening and transition from contractant to dilatant volumetric behaviour during undrained ***,the first tentative of validation gives a good correlation between simulations and experimental data,and shows encouraging signs for future developments.

关键词： suction effective stress equivalent pore pressure hardening experimental validation

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实现高效的运营转型

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网络电信 2006年第12期8卷 34-36页

作者： G．morvan J．Mayer

由于网络发展并转型到IP和日渐渗透的宽带接入，业务提供商有时只得四处寻找出路支持这种增长，并提供足够的客户服务，他们面临高速增长经济里的一系列挑战：

关键词：转型运营宽带接入客户服务提供商

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M型返波管在远距离通信中的应用

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真空电子技术 1972年第1期 47-50页

作者： J. Ninerailles et E. morvan

随着电子管的发展,远距离通信系统目前已发展到完善的程度。通信量大幅地增加,传输工具日渐变得更加重要,而种类也越来越多。为了解决许许多多更复杂的问题,工程人员正在考虑尽量运用有关元件工业,特别是电子管工业提供的一切可能手段... 详细信息

随着电子管的发展,远距离通信系统目前已发展到完善的程度。通信量大幅地增加,传输工具日渐变得更加重要,而种类也越来越多。为了解决许许多多更复杂的问题,工程人员正在考虑尽量运用有关元件工业,特别是电子管工业提供的一切可能手段。这就需要对元件制造用的材料的性能加以控制,特别是在短波长更是如此。实际上,在微波范围。

关键词：返波管波束负载效应电话栅控微波管电信信息通路信道调制频带

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Graphene Thin Layers Formation on Monocrystalline Ni(111)/MgO(111) by Carbon Implantation and Annealing

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Graphene 2015年第2期4卷 21-37页

作者： F. Le Normand M. Benyahia C. Speisser D. Muller F. Aweke G. Gutierrez J. Arabski G. morvan ICube—Laboratoire des Sciences de l’Ingénieur de l’Informatique et de l’Imagerie Université de Strasbourg Strasbourg Cedex France IPCMS—Institut de Physique et de Chimie des Matériaux de Strasbourg Strasbourg Cedex France LHyGeS—Laboratoire d’Hydrologie et de Géochimie de Strasbourg Strasbourg Cedex France

The objectives of this study are the elaboration of graphene by 1) carbon implantation at moderate temperature (873 K) into a monodomain epitaxially-grown Ni(111) film deposited on a reusable MgO(111) substrate, followed by 2) carbon surface precipitation by thermal treatment. The growth of the nickel film by molecular beam epitaxy has been monitored by Reflection High Energy Electron Diffraction. The film morphology has been studied by Electron Back-Scattered Diffraction, Atomic Force Microscopy and Rutherford Backscattering Spectroscopy in the tunneling mode. In the optimized conditions corresponding to a germination step at 633 K followed by a step growth at 873 K and a post-annealing treatment at 1023 K monocrystalline Ni(111) //MgO(111) films are prepared, exhibiting monodomain swith high structural and orientation qualities. 13C implantation into these nickel films is subsequently achieved at 873 K with energy within 20 - 50 keV and a carbon dose equivalent to 4 monolayers of graphene (1.4 × 1016 at/cm2). Carbon diffuses mainly towards the surface, forming thin layers graphene. Compared to a Ni polycrystalline film the graphene fragments are larger and better facetted. The carbon amounts inside the nickel films at different steps, as well as the carbon amount at the surface, have been measured by Nuclear Reaction Analysis and X-ray Photoelectron Spectroscopy, respectively. The results show that, in addition to implanted 13C, some amounts of 12C is incorporated at different steps of the process and is involved in the formation of the graphene monolayers, as shown by 13C/12C Raman mappings. We finally discuss different mechanisms for carbon diffusion and surface segregation, considering the size and thickness distributions of the thin-layers graphene.

关键词： Graphene Nickel Monocrystalline Films Ion Implantation Raman Spectroscopy

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