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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

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SmEARED CRACKING FEm SImULATION OF ALKALI SILICA EXPANSION USING A NEW mACROSCOPIC COUPLED mODEL

SMEARED CRACKING FEM SIMULATION OF ALKALI SILICA EXPANSION U...

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第十二届国际混凝土碱集料反应会议

作者： Eduardo m.R.Fairbairn Fernando L.B.Ribeiro Romildo D.Toledo-Filho Luciana E.Lopes marcos m.Silvoso marcia F.F.guas Quintiliano m.guedes COPPE/The post-Graduate Engineering Institute Universidade Federal do Rio de JaneiroC.P.68506CEP 21945-970-Rio de Janeiro-RJ-Brasil COPPE/The post-Graduate Engineering Institute Universidade Federal do Rio de JaneiroC.P.68506CEP 21945-970-Rio de Janeiro-RJ-Brasil COPPE/The post-Graduate Engineering Institute Universidade Federal do Rio de JaneiroC.P.68506CEP 21945-970-Rio de Janeiro-RJ-Brasil COPPE/The post-Graduate Engineering Institute Universidade Federal do Rio de JaneiroC.P.68506CEP 21945-970-Rio de Janeiro-RJ-Brasil COPPE/The post-Graduate Engineering Institute Universidade Federal do Rio de JaneiroC.P.68506CEP 21945-970-Rio de Janeiro-RJ-Brasil FURNAS Centrais Elétricas SA-DEC)-Rua Real Grandeza 219 CEP 22281-031-Rio de Janeiro-RJ-Brasil FURNAS Centrais Elétricas SA-DEC)-Rua Real Grandeza 219 CEP 22281-031-Rio de Janeiro-RJ-Brasil

＜正＞ We present an ASR thermo-chemo-mechanical expansion model recently developed, whose main feature is the representation of the stress-induced anisotropy, which is taken into account by means of a classical smeared cracking model that was implemented in a 3D Finite Element code. This model considers the influence of temperature and humidity in the development of ASR. Since cracking occurs generally at the beginning of the swelling process, it is suggested that the assessment of the reaction characteristics in free expansion tests could be attained considering a cracked specimen. Hence, an inverse analysis is used to determine ASR parameters. Besides the validation of the model by the simulation of laboratory tests, it was applied to the simulation of alkali-silica expansion in a real gravity dam. We computed the displacements at the crest of the block comparing it with measures taken in the field for the last 25 years. The good correlation between experimental and numerical data displayed the accuracy of the model indicating its potentialities to engineering applications.

关键词： Alkali-silica reaction numerical modeling coupled model cracking

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Joint Return Value Estimation of Significant Wave Heights and Wind Speeds with Bivariate Copulas

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Journal of Ocean University of China 2023年第5期22卷 1181-1192页

作者： TAO Shanshan DONG Sheng LIN Yifan guedes SOARES Carlos College of Engineering Ocean University of ChinaQingdao 266100China Huadian Heavy Industries Co. Ltd.Beijing 100070China Instituto Superior Técnico Universidade de LisboaLisboa 1049-001Portugal

The joint design criteria of significant wave heights and wind speeds are quite important for the structural reliability of fixed offshore ***,the design method that regards different ocean environmental variables as independent is *** the present study,we introduce a bivariate sample consisting of the maximum wave heights and concomitant wind speeds of the threshold by using the peak-over-threshold and declustering *** selecting the appropriate bivariate copulas and univariate distributions and blocking the sample into years,the bivariate compound distribution of annual extreme wave heights and concomitant wind speeds is *** joint design criteria,namely,the joint probability density method and the conditional probability method,are applied to obtain the joint return values of significant wave heights and wind *** show that(28.5±0.5)m s^(-1)is the frequently obtained wind speed based on the Atlantic dataset,and these joint design values are more appropriate than those calculated by univariate analysis in the fatigue design.

关键词： joint design wave height wind speed compound distribution copula

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国际海事组织船舶能效提案及其影响综述

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哈尔滨工程大学学报（英文版） 2023年第4期22卷 662-680页

作者： m.Tadros m.Ventura C.guedes Soares Centre for marine Technology and Ocean Engineering(CENTEC) Instituto Superior TécnicoUniversidade de LisboaAv.Rovisco Pais 11049-001 LisboaPortugal Department of Naval Architecture and marine Engineering Faculty of EngineeringAlexandria UniversityAlexandria 21544Egypt

This paper presents a review of the different International maritime Organization(ImO)initiatives to improve the ship energy efficiency of new and existing ships,which is considered one of the essential tasks to reduce Greenhouse Gas(GHG)in the maritime ***,the ImO effort and initiatives and the different indices suggested by the ImO are presented till the last version of the marine Environment Protection Committee(mEPC),showing the effect of different technologies on reducing the level of indices and the suggested improvement of the terms of indices in the next ***,the short-and long-term strategies suggested by the ImO are presented,showing that the effect of indices will be noticed in the short term,while the new fuels will show a significant improvement in the long ***,several examples of cooperation between the different organizations are presented,showing that transferring knowledge and experience will significantly impact the maritime industry and thus lead to the concept of green ships in the near *** paper shows that the combination of different solutions,the cooperation between stakeholders and the sharing of the data and information are important to achieve the required goal.

关键词： Energy efficiency ImO Decarbonization Design index Operational index Classification societies

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某散货船单桨、双桨推进系统燃油消耗分析

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哈尔滨工程大学学报（英文版） 2023年第4期22卷 741-750页

This paper presents a comparative analysis between single and twin-screw propulsion systems of a bulk carrier to evaluate the ship and propeller performance in terms of fuel consumption as well as to discuss the cavitation and noise *** optimization model is developed to select the optimum propeller geometry and operational point along the engine load diagram for the selected engines of each *** engines are selected from the same series due to the same behaviour along the engine load *** propellers are selected from the B-series as fixed-pitch *** has been concluded that while the components of the single-screw propulsion system are larger than the twin-screw,the single-screw propulsion system shows a reduction in fuel consumption than the twin screw by around 19%,thus affecting the amount of exhaust emissions from the *** model helps the ship designers to select a suitable propeller to improve the energy efficiency of the ships.

关键词： Propeller performance Exhaust emissions Energy efficiency ImO Decarbonization Fuel consumption Single and twin-screw

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Review of Ultimate Strength Assessment of Ageing and Damaged Ship Structures

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Journal of marine Science and Application 2020年第4期19卷 512-533页

作者： m.Tekgoz Y.Garbatov C.guedes Soares Centre for marine Technology and Ocean Engineering(CENTEC) Instituto Superior TécnicoUniversidade de LisboaAv.Rovisco Pais1049-001 LisbonPortugal

The objective of this work is to provide an overview of the ultimate strength assessment of ageing and damaged ship structures in the last *** attention is paid to the ultimate strength of plates,stiffened panels,box girders,and entire ship hull structures subjected to corrosion degradation,fatigue cracking,and mechanical damage caused by accidental loading or impact.A discussion on the effect of the cyclic load on the plate rigidity,re-yielding,and ultimate load capacity on the ship hull girder is also part of the present ***,some conclusions and discussions about potential future work are provided,identifying that more studies about the impact of corrosion degradation on the structural behaviour of the stiffened panels and the overall hull girders are *** related to the dynamic collapse behaviour of corroded and damaged ship structures under time-variant load also requires additional attention.

关键词： marine corrosion Damage Ultimate strength Finite element method

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Influence of Support Conditions on the Hydroelastic Behaviour of Floating Thick Elastic Plate

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Journal of marine Science and Application 2019年第3期18卷 295-313页

作者： K.m.Praveen D.Karmakar C.guedes Soares Department of Applied mechanics and Hydraulics National Institute of Technology KarnatakaSurathkalMangalore 575025India Centre for marine Technology and Ocean Engineering (CENTEC) Instituto Superior TécnicoUniversidade de LisboaAv. Rovisco Pais1049 001 LisbonPortugal

The hydroelastic response of very large floating structures (VLFS) under the action of ocean waves is analysed considering the small amplitude wave theory. The very large floating structure is modelled as a floating thick elastic plate based on Timoshenko- mindlin plate theory, and the analysis for the hydroelastic response is performed considering different edge boundary conditions. The numerical study is performed to analyse the wave reflection and transmission characteristics of the floating plate under the influence of different support conditions using eigenfunction expansion method along with the orthogonal mode-coupling relation in the case of finite water depth. Further, the analysis is extended for shallow water depth, and the continuity of energy and mass flux is applied along the edges of the plate to obtain the solution for the problem. The hydroelastic behaviour in terms of reflection and transmission coefficients, plate deflection, strain, bending moment and shear force of the floating thick elastic plate with support conditions is analysed and compared for finite and shallow water depth. The study reveals an interesting aspect in the analysis of thick floating elastic plate with support condition due to the presence of the rotary inertia and transverse shear deformation. The present study will be helpful for the design and analysis of the VLFS in the case of finite and shallow water depth.

关键词： Timoshenko-mindlin plate theory Very large floating structure Support condition Rotary inertia Transverse shear deformation

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Electrochemical response of Ti joints vacuum brazed with TiCuNi, AgCu, and Ag fillers

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Transactions of Nonferrous metals Society of China 2021年第4期31卷 999-1011页

作者： C.mARINHO F.TOPTAN A.guedes A.C.ALVES CmEmS-Uminho Center of MicroElectroMechanical SystemsUniversity of MinhoGuimarãesPortugal IBTN/Euro European Branch of the Institute of BiomaterialsTribocorrosion and NanomedicineDepartment of Mechanical EngineeringUniversity of MinhoGuimarãesPortugal Department of mechanical Engineering University of MinhoGuimarãesPortugal

The properties of the joints are dictated by the nature, distribution, and morphology of the phases formed at the interface. The mechanical properties of brazed joints are well documented in the literature, contrarily to their electrochemical behaviour. Thus, the main objective of this study was to understand the influence of the phases formed at the interface on the corrosion behaviour of commercially pure Ti brazed joints, produced by using TiCuNi, eutectic Ag Cu, and Ag filler foils. The electrochemical behaviour of the Ti joints was accessed by open circuit potential and potentiodynamic polarization tests in phosphate buffer saline solution electrolyte at body temperature. Results showed that Ag-based fillers induced susceptibility to micro-galvanic corrosion between the Ag-rich and Ti phases formed at the interface and commercially pure Ti base metal. However, no significant differences were observed between the joint system and the base material when brazing with TiCuNi filler.

关键词： biomaterial titanium joining brazing alloys interface microstructure corrosion

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Species richness and density evaluation for plants with aggregated distributions:fixed *** area methods

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Journal of Plant Ecology 2017年第5期10卷 765-770页

作者： Rita de Cássia Quitete Portela Alexandra dos Santos Pires maria Isabel guedes Braz Eduardo Arcoverde de mattos Departamento de Ecologia Instituto de BiologiaUniversidade Federal do Rio de JaneiroCaixa Postal 68020Ilha do FundãoRio de JaneiroRJ 21941-590Brasil Departamento de Ciências Ambientais Instituto de FlorestasUniversidade Federal Rural do Rio de JaneiroRod.BR 465Km 07Cidade UniversitáriaSeropédicaRio de JaneiroRJ 23890-000Brasil

Aims Knowledge of species richness is of prime importance to both basic and applied aspects of ecological ***,quantifying plant species richness in the tropics is potentially time-consuming because of high species *** species richness estimates are also frequently biased,because many rare species are not *** address these problems,the use of a variable area method has been proposed as an alternative to fixed area methods,but its appli-cability to plants with aggregated distributions has been questioned based on simulation *** use empirical data to compare the efficiency and accuracy of a variable area method and a fixed area method for estimating species richness,density and basal area for plants with aggregated distributions,using palms as a model *** Adult palms were sampled in twenty 10×30 m transects in an Atlantic Forest in Rio de Janeiro state,*** individuals were considered in the fixed area method,while in the variable area method only the first six adults in each transect were sampled;in this case,transect length was defined according to the distance of the sixth adult from the beginning of the *** fewer than six individuals were observed in a given transect,transect length was extended up to 50 m to search for additional *** efficiency of both methods was compared based on species rarefaction curves,using the chao 1 statistic(for abundance data).For each species we calculated mean density per transect and basal area,according to each sampling *** effort in terms of the number of individual plants and the area necessary to characterize maximum species richness in each sampling method,as well as mean time taken to sample a single transect,were compared as measures of *** findings An accurate estimate of species richness was achieved using both methods,but in the variable area method,a quarter of the number of individuals and half the area was sufficient

关键词： basal area biodiversity inventory palms taxon sampling

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Analysis of the Correlation between the Level of Contact Degradation and the Dynamic Resistance Curve in Circuit Breakers

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Journal of Energy and Power Engineering 2014年第6期8卷 1104-1111页

作者： Ronimack Trajano de Souza Edson guedes da Costa Department of Electrical Engineering Campina Grande Federal University Campina Grande 58429-900 Brazil

The DRm （dynamic contact resistance measurement） in high voltage circuit breakers is a manner of evaluating the internal ageing condition of the chamber. DRm is similar to static contact resistance measurement testing, but instead of measuring a single value when the breaker contacts are closed （static value）, the ohmic resistance is measured at various contact positions, from the beginning of the contact opening until a complete separation of the contacts. The relationship between the contact resistances of the new circuit breaker and the ageing circuit breaker in operation provides subsidy for the evaluation of both the main and arcing contact conditions. This research aims to analyze the correlation between the various levels of degradation of the contacts and the configuration of the DRm curve. This work considers curve samples from new acceleration tests. breaker chamber contacts and different levels of degradation by

关键词： DRm (dynamic contact resistance measurement) circuit breaker dynamic resistance contact resistance resistance curve.

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