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Dynamics of Droplets of Biological Fluids on Smooth Superhydrophobic Surfaces under Electrostatic Actuation

Journal of Bionic Engineering 2016年第2期13卷 220-234页

作者： Ana Sofia Moita Catarina Laurencia Joana Anastacio Ramos Duarte Miguel Franca Prazeres Antonio Luis Nobre Moreira IN+ - Center for Innovation Technology and Policy Research Instituto Superior Tecnico Universidade de Lisboa Av. Rovisco Pais 1049-001 Lisboa Portugal iBB - Institute for Bioengineering and Biosciences Department of Bioengineering Instituto Superior Tecnico Universidade de Lisboa Av. Rovisco Pais 1049-001 Lisboa Portugal

This study describes the dynamic behav.our of droplets of biological liquids on hydrophobic surfaces under electrostatic actuation, to devise sample handling in lab-on-chip diagnostic tools. Bovine Serum Albumin （BSA） is taken as a representative biomolecule, since it is often used in adsorption studies. Green Fluorescence Protein （GFP） is also considered, given its natural fluorescence. Several effects such as sample concentration and pH are discussed. The results show negligible effects of proteins concentration in electrowetting, although increased concentrations endorse passive adsorption mechanisms, which alter the local wettability of the substrates precluding droplet motion. Bioinspired surfaces promote the largest spreading diameter, which is beneficial for droplet motion. However, surface roughness promotes energy dissipation limiting the receding droplet motion. Hence, the most effective approach is altering the surface chemistry. The coating is applied to a surface with a mean roughness smaller than 20 nm and does not alter significantly the topography, thus leading to the so-called smooth superhydrophobic surface. This coating also reduces passive proteins adsorption, as confirmed by Confocal Microscopy （CM）, which is beneficial for droplet motion. Evaluating absorption spectra of protein solutions evidences an increase in protein concentration ascribed to droplet evaporation as confirmed by theoretical analysis and time resolved infrared visualization.

关键词： bioinspired surfaces biofluids electrostatic actuation hydrophobicity adsorption evaporation

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Optimization of high-speed railway pantographs for improving pantograph-catenary contact

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Theoretical & Applied Mechanics Letters 2013年第1期3卷 51-57页

作者： Jorge Ambrósio Joo Pombo Manuel Pereira IDMEC-IST Technical Univ. of Lisbon av. rovisco pais

A crucial system for the operation of high-speed trains is the pantograph catenary interface as it is the sole responsible to deliver electrical power to the train. Being the catenary a stationary system with a long lifespan it is also less likely to be redesigned and upgraded than the pantographs that fit the train vehicles. This letter proposes an optimization procedure for the improvement of the contact quality between the pantograph and the catenary solely based on the redesign of the pantograph head suspension characteristics. A pantograph model is defined and validated against experimental dynamic characteristics of existing pantographs. An optimization strategy based on the use of a global optimization method, to find the vicinity of the optimal solution, followed by the use of a deterministic optimization algorithm, to fine tune the optimal solution, is applied here. The spring stiffness, damping characteristics and bow mass are the design variables used for the pantograph optimization. The objective of the optimal problem is the minimization of the standard deviation of the contact force history, which is the most important quantity to define the contact quality. The pantograph head suspension characteristics are allowed to vary within technological realistic limits. It is found that current high-speed railway pantographs hav. a limited potential for mechanical improvements, not exceeding 10% 15% on the decrease of the standard deviation of the contact force. C 2013 The Chinese Society of Theoretical and Applied Mechanics. [doi：10.1063/2.1301306]

关键词： high-speed railway pantograph

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Characterization of the Topography and Wettability of English Weed Leav.s and Biomimetic Replicas

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Journal of Bionic Engineering 2014年第3期11卷 346-359页

作者： Pedro Miguel Matos Pereira Ana Sofia Moita Gabriel Amaro Monteiro Duarte Miguel Franca Prazeres IBB - Institute for Biotechnology and Bioengineering Centre for Biological and Chemical Engineering Department of Bioengineering Instituto Superior Tecnico Universidade de Lisboa Av. Rovisco Pals 1049-001 Lisboa Portugal IN+ - Center for Innovation Technology and Policy Research Instituto Superior T~cnico Universidade de Lisboa Av. Rovisco Pais 1049-001 Lisboa Portugal

The topography and wettability of the underside of English weed （Oxalis pes-caprae） leav.s and of their biomimetic replicas are investigated. Polyvinyl siloxane molds were cast from the leav.s and then filled with an epoxy pre-polymer to produce replicas. The particular topographical structures of leav.s and replicas were evaluated by optical microscopy and Scanning Electron Microscopy （SEM） analysis. The static wettability of leav.s and replicas was assessed by contact angle measurements, while the dynamic wettability was characterized by estimating contact angle hysteresis and studying the dynamic behav.or of impacting water droplets. A smooth glass slip and its replica were used as control surfaces. The replica moulding method used was able to transfer the characteristic pattern of irregular 100 μm - 200 μm × 60 μm convex papillae interspersed with stomata of the original leaf to the epoxy replicas. The static contact angle of 143°± 3° and the contact angle hysteresis of 2~ indicate that the underside of the English weed leaf is close to superhydrophobic. The lower contact angles （130° ± 4°） and higher hysteresis （31°） observed for the replica when compared with the original leav.s were associated to an inaccurate replication of the chemistry and structures of the three-dimensional wax projections covering the plant surface. Also, trichomes in the original leav.s could not be accurately reproduced due to their flexibility and fragility. Differences in wetting behav.or were also evident from droplet impact experiments, with rebound regimes prevailing in the original leav.s and regimes characterized by higher adhesion and larger dissipation predominating in the replicas. Nevertheless, the morphological features of the leaf transferred to the replica were sufficient to promote a clear hydrophobic behav.or of the replica when compared with the smooth epoxy reference surface.

关键词： biomimetic surfaces oxalis pes-caprae English weed replica molding wettability micro-topography

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A Stochastic Variational Approach to Viscous Burgers Equations

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Acta Mathematica Sinica,English Series 2016年第9期32卷 1027-1034页

作者： Ana Bela CRUZEIRO Guo Ping LIU GFMUL and Dep. de Matematica Instituto Superior Tecnico (Universidade de Lisboa) Av. Rovisco Pais 1049-001 Lisboa Portugal GFMUL and Dep. de Matematica Instituto Superior Tecnico (Universidade de Lisboa) Av. Rovisco Pais 1049-001 Lisboa Portugal Academy of Mathematics and Systems Science Chinese Academy of Sciences 100190 Beijing P. R. China

We consider viscous Burgers equations in one dimension of space and derive their solutions from stochastic variational principles on the corresponding group of homeomorphisms. The metrics considered on this group are Lp metrics. The velocity corresponds to the drift of some stochastic Lagrangian processes. Existence of minima is proved in some cases by direct methods. We also give a representation of the solutions of viscous Burgers equations in terms of stochastic forward-backward systems.

关键词： Burgers equations stochastic variational principles Lagrangian diffusions

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Optimizing building retrofit through data analytics:A study of multi-objective optimization and surrogate models derived from energy performance certificates

Energy and Built Environment

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Energy and Built Environment 2024年第6期5卷 889-899页

作者： G.R.Araújo Ricardo Gomes Paulo Ferrão M.Glória Gomes IN+ DEMTécnico LisboaUniversidade de lisboaAv Rovisco PaisLisboa1049-001Portugal CERIS DECivilTécnico LisboaUniversidade de LisboaAv Rovisco PaisLisboa1049-001Portugal

The building stock is responsible for a large share of global energy consumption and greenhouse gas emissions,therefore,it is critical to promote building retrofit to achieve the proposed carbon and energy neutrality *** of the policies implemented in recent years was the Energy Performance Certificate(EPC)policy,which proposes building stock benchmarking to identify buildings that require ***,research shows that these mechanisms fail to engage stakeholders in the retrofit process because it is widely seen as a mandatory and complex *** study makes use of an EPC database to integrate machine learning techniques with multi-objective optimization and develop an interface capable of(1)predicting a building’s,or household’s,energy needs;and(2)providing the user with optimum retrofit solutions,costs,and return on *** goal is to provide an open-source,easy-to-use interface that guides the user in the building retrofit *** energy and EPC prediction models show a coefficient of determination(R2)of 0.84 and 0.79,and the optimization results for one case study EPC with a 2000€budget limit inÉvora,Portugal,show decreases of up to 60%in energy needs and return on investments of up to 7 in 3 years.

关键词： Building energy performance Building optimization Multi-Objective surrogate models Building retrofitting

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Fatigue Reliability Assessment of Correlated Welded Web-frame Joints

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Journal of Marine Science and Application 2014年第1期13卷 23-31页

作者： W.Huang Y.Garbatov C.Guedes Soares Centre for Marine Technology and Engineering (CENTEC) Instituto Superior Técnico Universidade de Lisboa Av. Rovisco Pais 1049-001 Lisboa Portugal Centre for Marine Technology and Engineering (CENTEC) Instituto Superior Técnico Universidade de Lisboa Av. Rovisco Pais 1049-001 Lisboa Portuga

The objective of this work is to analyze the fatigue reliability of complex welded structures composed of multiple web-frame joints, accounting for correlation effects. A three-dimensional finite element model using the 20-node solid elements is generated. A linear elastic finite element analysis was performed, hotspot stresses in a web-frame joint were analyzed and fatigue damage was quantified employing the S-N approach. The statistical descriptors of the fatigue life of a non-correlated web-frame joint containing several critical hotspots were estimated. The fatigue reliability of a web-frame joint wasmodeled as a series system of correlated components using the Ditlevsen bounds. The fatigue reliability of the entire welded structure with multiple web-frame joints, modeled as a parallel system of non-correlated web-frame joints was also calculated.

关键词： fatigue reliability hotspot stress S-N approach finite element analysis web-frame joints

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Application of Bioinspired Superhydrophobic Surfaces in Two-phase Heat Transfer Experiments

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Journal of Bionic Engineering 2017年第3期14卷 506-519页

作者： Emanuele Teodori Ana Sofia Moita Miguel Moura Pedro Pontes Antonio Moreira Yuan Bai Xinlin Li Yan Liu IN+- Center for Innovation Technology and Policy Research Instituto Superior T~enico Universidade de Lisboa Av. Rovisco Pais 1049-001 Lisboa Portuga Key Laboratory of Bionic Engineering (Ministry of Education) Jilin University Changchun 130022 China

This paper addresses the potential to use Lotus leafbioinspired surfaces in applications involving heat transfer with phase change, namely pool boiling and spray impingement. Besides describing the role of bioinspired topographical features, using an innovative technique combining high-speed visualization and time-resolved infrared thermography, surface durability is also addressed. Water is used for pool boiling and for spray impingement systems （simplified as single droplet impact）, while HFE7000 is used in a pool boiling cooler for electronic components. Results show that surface durability is quickly compro- mised for water pool boiling applications, as the chemical treatment does not withstand high temperatures （T 〉 100 ℃） during long time intervals （3 h - 4 h）. For HFE7000 pool boiling （depicting lower saturation temperature - 34 ℃）, heat transfer en- hancement is governed by the topography. The regular hierarchical pattern of the bioinspired surfaces promotes the heat transfer coefficient to increase up to 22.2%, when compared to smooth surfaces, while allowing good control of the interaction mechanisms until a distance between micro-structures of 300 gm- 400 Ixm. Droplet impingement was studied for surface temperatures ranging between 60 ℃ - 100 ℃. The results do not support the use of superhydrophobic surfaces for cooling applications, but reveal great potential for other applications involving droplet impact on heated surfaces （e.g. metallurgy in- dustry）.

关键词： bioinspired surfaces surface micro-patterning two-phase heat transfer time resolved infrared thermography

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Improving Linked-Lists Using Tree Search Algorithms for Neighbor Finding in Variable-Resolution Smoothed Particle Hydrodynamics

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Communications in Computational Physics 2019年第6期26卷 57-86页

作者： Shahab Khorasanizade J.M.M.Sousa IDMEC Instituto Superior T́ecnicoUniversidade de LisboaAv.Rovisco Pais1049-001 LisboaPortugal

Improving linked-lists for neighbor finding with the use of tree search algorithms is proposed here,aiming to cope with highly non-uniform resolution simulations employing a meshless *** new procedure,coined Quadtree Cells Grid,has been implemented in Smoothed Particle Hydrodynamics(SPH).The SPH scheme employed is adaptive,thus allowing for particle refinement in desired regions of the *** to the wide range of coexisting particle mass levels,standard linked-list neighbor search algorithms become ***,an alternative is found based on the use of hierarchical data structures,using quadtrees(in 2D problems).The present algorithm exploits the advantages of both linked-lists and quadtree meth-ods with the goal of increasing computational efficiency,when dealing with highly non-uniform particle *** cases involving two distinct flow problems hav. demonstrated that the computational cost of the current adaptive neighbor finding algorithm scales linearly with the total number of particles,thus retrieving this characteristic of linkedlists in uniform grid ***,the memory usage increased as a result of the more complex data structure.

关键词： Smoothed particle hydrodynamics linked-list quadtree neighbor finding variable resolution

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Syntheses, Crystal Structures and Magnetic Properties of Cobalt(Ⅱ) and Manganese(Ⅱ) Coordination Polymers Constructed from 5-(Pyridin-4-yl)Isophthalate Ligands

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Chinese Journal of Structural Chemistry 2014年第4期33卷 626-634页

作者：高竹青李红晋 M.Kirillov Alexander 顾金忠 School of Chemical and Biological Engineering Taiyuan University of Science and Technology Centro de Química Estrutural Complexo I Instituto Superior TécnicoThe University of Lisbon Av. Rovisco Pais1049-001 Lisbon Portugal College of Chemistry and Chemical Engineering Lanzhou University

Two coordination polymers, namely {[Co（L）（H2O）]·H2O}n （1） and [Mn（L）（phen）]n （2, H2L = 5-（pyridin-4-yl）isophthalic acid, phen = 1,10-phenanthroline）, hav. been hydrothermally synthesized and characterized by elemental analysis, IR, TG, magnetic properties, and single-crystal X-ray diffraction. 1 belongs to the triclinic system, space group Pī with α = 7.2188（7）, b = 10.0835（8）, c = 10.2069（7）？, α = 113.713（7）, β = 99.490（7）, γ = 104.516（8）o, V = 628.24（9）？3, C13H11NCoO6, Mr = 336.16, Z = 2, Dc = 1.777 Mg/m3, μ（MoKα） = 1.395 mm–1, F（000） = 342, S = 1.041, the final R = 0.0381 and wR = 0.0819 for 3744 observed reflections （I 〉 2σ（I）） and R = 0.0448 and wR = 0.0874 for all data. 2 belongs to the monoclinic system, space group P2/c with α = 12.9185（3）, b = 10.4343（2）, c = 31.7650（6）？, β = 101.282（2）o, V = 4199.08（13）？3, C50H30N6Mn2O8, Mr = 952.68, Z = 4, Dc = 1.507 Mg/m3, μ（MoKα） = 5.447 mm–1, F（000） = 1944, S = 1.128, the final R = 0.1003 and wR = 0.1052 for 8247 observed reflections （I 〉 2σ（I）） and R = 0.2595 and wR = 0.2625 for all data. Single-crystal X-ray diffraction studies show that compound 1 features a 2D sheet structure based on a dicobalt（II） subunit, which is further extended into a 3D metal-organic supramolecular framework by O–H… hydrogen bond. Compound 2 also possesses a 2D sheet, which is held together into a 3D supramolecular architecture via C–H… hydrogen bond and π-π stacking interactions. Magnetic studies for compound 2 show antiferromagnetic coupling between the adjacent metal centers, with J = –11.8 cm–1 and g = 2.12 for 2.

关键词： coordination polymer crystal structrue magnetic properties

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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 behav.or Micro-CT analysis Finite element method

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