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the CAStOR-K Code,Recent developments and Applications

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Plasma Science and technology 2015年第2期17卷 89-96页

作者： F.NABAIS D.BORBA R.COELHO A.FIGUEIREDO J.FERREIRA N.LOUREIRO P.RODRIGUes Associao EURAtOM/ISt Instituto de Plasmas e Fuso Nuclear-Instituto Superior TcnicoUniversidade de Lisboa

the CAStOR-K code is a hybrid magnetohydrodynamic （MHD）-drift kinetic code developed for the study of MHD modes in the presence of energetic ion populations. It allows a fast assessment of the linear stability of the modes, as well as an accurate calculation of damping due to thermal species （Landau damping）. these capabilities make the code an invaluable tool for parametric studies and data analysis. In recent years, CAStOR-K has been mostly used to analyze JEt data, including the identification of mechanisms involved in the expulsion of energetic ions from the plasma. However, in order to prepare the code to be used for a wider range of tokamaks including ItER, the code is being subject to a series of important improvements. these improvements aim not only to introduce new physics in the code but also to make it capable of exchanging data with other codes through its integration in modelling infrastructures. In this paper a description of the CAStOR-K code is presented, as well as a summary of the most important results obtained with this code and a description of the new improvements being implemented.

关键词： controlled fusion tokamaks plasma instabilities magnetohydrodynamics(MHD) Alfven waves energetic particles

Modified Joint Distribution of Wave Heights and Periods

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China Ocean Engineering 2016年第3期30卷 359-374页

作者： H.D.Zhang C.Guedes Soares Centre for Marine technology and Ocean Engineering (CENtEC) Instituto Superior Técnico Universidade de Lisboa

the modified versions of the linear theoretical model of Longuet-Higgins （1983） are derived in this work and also compared with the laboratory experiments carried out in MAR1NtEK. the main feature of modifications is to replace the mean frequency in the formulation with the peak frequency of the wave spectrum. these two alternative forms of joint distributions are checked in three typical random sea states characterized by the initial wave steepness. In order to further explore the properties ＆these models, the associated marginal distributions of wave heights and wave periods are also researched with the observed statistics and some encouraging results are obtained.

关键词： Longuet-Higgins joint distribution mixed sea state nonlinear wave series wave height wave period

A European digital accelerometric database:statistical analysis of engineering parameters of small to moderate magnitude events

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Earthquake Engineering and Engineering Vibration 2014年第4期13卷 583-597页

作者： Carlos S.Oliveira Gerard Gassol Xavier Goula teresa Susagna instituto superior técnico Universidade de Lisboa Institut Cartogràfic i Geològic de Catalunya

During the NERIes Project, an accelerometric database containing European digital information was developed. Besides event and station metadata, ground motion parameters, computed in a homogeneous manner, were assembled： PGA, PGV, AI, tD, CAV, H1 and PSV（f,5%）（19,961 components, 2629 events, 547 stations）. Merging small and moderate magnitude events produced a unique database capable of providing important information such as：（i） Correlations between several ground motion parameters follow analogous trends as in previous worldwide datasets, with slight corrections. （ii） Although PGA attenuations with distance show great uncertainties, four recent GMPes recommended for Europe fit quite well the central 50% data interval for the distance range 10 〈 R 〈 200 kin; outside these distances, they do not fit. （iii） Soil amplification ratios indicate that weak motion （low magnitudes and larger distances） shows larger amplification than strong motion （short distances and large magnitudes） as represented in UBC97 for the USA, but not in EC8 for Europe. （iv） Average spectral shapes are smaller than in the EC8. （v） Differences in amplification factors for PGA, PGV and HI for EC8 soil classes B and C, and differences in spectral shapes for these soil classes, indicate that EC8, type 2 S-coefficient should be frequency dependent, as in UBC97.

关键词： NERIes project parametric accelerometric database European region PGA EC8 soil amplification

Experimental and numerical characterization of 3D‑printed scaffolds under monotonic compression with the aid of micro‑Ct volume reconstruction

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Bio-design and Manufacturing 2021年第2期4卷 222-242页

作者： R.Baptista M.F.C.Pereira A.Maurício D.Rechena V.Infante M.Guedes CDP2t Departamento de Engenharia MecanicaEscola Superior de Tecnologia de SetúbalInstituto Politécnico de Setúbal2910‑761 SetúbalPortugal CERENA DECivilInstituto Superior TécnicoUniversidade de LisboaAv.Rovisco Pais11049‑001 LisbonPortugal IDMEC Instituto Superior TécnicoUniversidade de LisboaAv.Rovisco Pais11049‑001 LisbonPortugal IPFN Instituto Superior TécnicoUniversidade de Lisboa1049‑001 LisbonPortugal CeFEMA Instituto Superior TécnicoUniversidade de LisboaAv.Rovisco Pais11049‑001 LisbonPortugal

Even when damaged by injury or disease bone tissue has the remarkable ability to *** this process is limited by large size bone defects,tissue engineering is responsible for restoring,maintaining or improving tissue *** are support structures,designed to be implanted in the damaged site,supporting mechanical loads and protecting the regenerating bone *** this paper,3D-printed PLA scaffolds with three different porosity values and two different geometries were experimentally and numerically ***-Ct analysis showed that fused filament fabrication can be used to produce scaffolds with the desired porosity and 100%of interconnected *** monotonical compression,scaffolds apparent compressive modulus increased from 89 to 918 MPa,while yield stress increased from 2.9 to 27.5 MPa as porosity decreased from 70 to 30%.Open porosity decreased up to 8%on aligned scaffolds and 14%on staggered scaffolds,after compression,while scaffold’s surface-to-volume ratio highest reduction(7.48 to 4.55 mm−1)was obtained with aligned low porosity ***-Ct volume reconstruction allowed for scaffold simplified numerical models to be built and *** agreement was found when predicting scaffold’s apparent compressive ***,it can be concluded that 3D printing is a viable scaffold manufacturing technique for trabecular bone replacement.

关键词： Scaffold Pore design Mechanical behavior Micro-Ct analysis Finite element method

Proposal of a fireproof design code for dwellings against the action of wildland fires

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Resilient Cities and Structures 2023年第3期2卷 104-119页

作者： M.R.t.Arruda A.R.A.Bicelli P.Cantor E.B.Assis F.Branco CERIS Instituto Superior TécnicoUniversidade de LisboaPortugal escola de Engenharia de São Carlos Universidade de São PauloBrazil instituto superior técnico Universidade de LisboaPortugal

this study proposes a concept for the development of a fireproof design code for the verification of dwellings susceptible to wildfire *** are currently structural codes for the design of buildings when subjected to indoor fires,outside fires that grow on the facade of buildings,and even fires in an accident situation due to ignitions with hydrocarbons or transportation *** of these security verification specifications are described in EC1:*** current regulation in Portugal uses safety criteria and risk categories that are for indoor fires,therefore is very conservative and may not present an economic fireproof design against the action of *** aim of this work is a straight verification based on natural temperature characteristic curves that simulate wildfire heat flow by convection,radiation,and the deposits of firebrands.

关键词： Structural safety verification Wildfires in dwellings Nominal fires vs natural fires Fireproof construction guidelines

Nonlocal material properties of single-walled carbon nanotubes

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International Journal of Smart and Nano Materials 2012年第2期3卷 141-151页

作者： J.V.Araújo dos Santos C.M.Mota Soares IDMEC Instituto Superior TécnicoUniversidade Técnica de Lisboa1049-001 LisboaPortugal

Natural frequencies of single-walled carbon nanotubes(SWCNts)obtained using a model based on Eringen’s nonlocal continuum mechanics and the timoshenko beam theory are compared with those obtained by molecular dynamics *** goal was to determine the values of the material constant,considered here as a nonlocal property,as a function of the length and the diameter of *** present approach has the advantage of eliminating the SWCNt thickness from the computations.A sensitivity analysis of natural frequencies to changes in the nonlocal material constant is also carried out and it shows that the influence of the nonlocal effects decreases with an increase in the SWCNt *** matching of natural frequencies shows that the nonlocal material constant varies with the natural frequency and the SWCNt length and diameter.

关键词： nonlocal mechanics molecular dynamics simulation single-walled carbon nanotube timoshenko beam

Fracture Loci in Sheet Metal Forming: A Review

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Acta Metallurgica Sinica(English Letters) 2015年第12期28卷 1415-1425页

作者： M.Beatriz Silva Kerim Isik A.Erman tekkaya Paulo A.F.Martins IDMEC Instituto Superior Técnico Universidade de Lisboa Institute of Forming technology and Lightweight Construction Technical University of Dortmund

Fracture in sheet metal forming usually occurs as ductile fracture, rarely as brittle fracture, at the operating temperatures and rates of loading that are typical of real processes in two different modes：（1） tensile and（2） in-plane shear（respectively, the same as modes I and II of fracture mechanics）. the circumstances under which each mode will occur are identified in terms of plastic flow and ductile damage by means of an analytical approach to characterize fracture loci under plane stress conditions that takes anisotropy into consideration. Fracture loci was characterized by means of the fracture forming limit line and by the shear fracture forming limit line in the fracture forming limit diagram. Experiments were performed with single point incremental forming and double-notched test specimens loaded in tension, torsion and in-plane shear give support to the presentation and allow determining the fracture loci of AA1050-H111 aluminium sheets with1 mm thickness. the relation between fracture toughness and the fracture forming limits was also investigated by comparing experimental values of the strains at fracture obtained from a truncated conical part produced by single point incremental forming and from double-notched test specimens loaded in tension.

关键词： Sheet forming Fracture Fracture forming limit diagram

Experimental and numerical analysis of multi-chamber oscillating water column devices

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Journal of Hydrodynamics 2024年第3期36卷 492-503页

作者： Jorge Gadelho Kourosh Rezanejad C.Guedes Soares Centre for Marine technology and Ocean Engineering(CENtEC) Instituto Superior TécnicoUniversidade de LisboaAvenida Rovisco PaisLisboaPortugal

A review of multi-chamber oscillating water column(OWC)device designs is *** significant variations of these devices are discussed,onshore OWC(OOWC)and a floating OWC(FOWC).the efficiency results of several theoretical studies based on low-and high-fidelity numerical models are presented and compared with the model scale ***,low-fidelity numerical models are very fast to run,but their accuracy is limited compared with high-fidelity numerical *** model experiments usually give results much more accurate than numerical models,but they need adequate facilities and are very *** the case of the OOWC,all models show a similar trend of total efficiency,but while the analytical model shows a maximum value of around 90%efficiency,the CFD model shows 60%,and the experiments only go up to 40%.the main reason is connected with the mathematical simplifications and assumptions that do not represent all the hydrodynamic and aerodynamic processes between the water,air,and *** the case of the FOWC,interestingly,the experimental results show a maximum efficiency of almost 100%,while the analytical model only predicts a maximum of 80%.the efficiency seems highly dependent on the heave motion resonance of the entire device,where the analytical model fails to predict this natural frequency.

关键词： Wave energy converters oscillating water column(OWC) multi-chambers experimental modelling numerical modelling

Liouvillian and Analytic Integrability of the Quadratic Vector Fields Having an Invariant Ellipse

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Acta Mathematica Sinica,English Series 2014年第3期30卷 453-466页

作者： Jaume LLIBRE Claudia VALLS departament de Matemàtiques Universitat Autònoma de Barcelona departamento de Matemtica Instituto Superior TcnicoUniversidade Tcnica de Lisboa

We characterize the Liouvillian and analytic integrability of the quadratic polynomial vector fields in R2 having an invariant *** precisely,a quadratic system having an invariant ellipse can be written into the form x=x2＋y2-1＋y（ax＋by＋c）,y=x（ax＋by＋c）,and the ellipse becomes x2＋y2=*** prove that（i） this quadratic system is analytic integrable if and only if a=0;（ii） if x2＋y2=1 is a periodic orbit,then this quadratic system is Liouvillian integrable if and only if x2＋y2=1 is not a limit cycle;and（iii） if x2＋y2=1 is not a periodic orbit,then this quadratic system is Liouvilian integrable if and only if a=0.

关键词： Liouvillian integrability quadratic planar polynomial vector fields invariant ellipse