Search

Este artigo objetiva apresentar uma proposta prática de elaboração de Roadmapping e Roadmap tecnológico para Instituições Científicas e Tecnológicas (ICT) que possuam um nível incipiente de elaboração desses documentos. O estudo ocorreu em 2016 e apresenta um modelo conceitual seguindo a abordagem Entidade-Relacionamento. O referencial teórico utiliza conceitos de Roadmappings e Roadmaps. Apresenta-se uma proposta de Roadmapping e Roadmap tecnológico para ICT, no qual são definidos os atores responsáveis por introduzir o Roadmapping tecnológico, principais níveis de arquitetura do Roadmap tecnológico, as etapas norteadoras para elaboração do Roadmap tecnológico das ICT, os dez passos norteadores do Roadmapping tecnológico para as ICT, e ao final, a Matriz de arquitetura de Roadmap tecnológico para ICT. Conclui-se que trata de uma ferramenta de acoplamento dos projetos de P&D à Visão tecnológica e que a aplicabilidade do modelo somente será viável para ICT que estejam num nível incipiente de elaboração do Roadmapping tecnológico, uma vez que, o exercício de elaboração de Roadmapping tecnológico é um processo de aprendizagem e de reestruturação de processos já relacionados, onde ICT maduras nesta prática, já possuem processos forjados para suas necessidades.

International audience; System-Theoretic Process Analysis (STPA) is a technique , based on System-Theoretic Accident Model and Process (STAMP), to identify hazardous control actions, loss scenarios, and safety requirements. STPA is considered a rather complex technique and lacks formalism, but there exists a growing interest in using STPA in certifications of safety-critical systems development. SysML is a modeling language for systems engineering. It enables representing models for analysis, design, verification, and validation of systems. In particular, the free software TTool and the model-checker UPPAAL enable formal verification of SysML models. This paper proposes a method that combines STPA and SysML modeling activities in order to allow simulation and formal verification of systems' models. An automatic door system serves as example to illustrate the effectiveness of the proposed approach.

International audience; Use case driven analysis is the corner stone of software and systems modeling in UML and SysML, respectively. Whether many books and tutorials have discussed the use of use case diagrams, students and industry practitioners regularly face methodological problems in writing good use cases. This paper defines a methodological assistant that helps designing use case diagrams relying on formalized rules and reuse of previous diagrams. The methodological assistant is implemented in Python. It is interfaced with the free SysML software TTool, and with Cameo Systems Modeler.

Made available in DSpace on 2019-10-06T15:23:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-11-01 In this work we derive and analyse cosmological scenarios coming from multi-component scalar field models. We consider a direct sum of a sine-Gordon with a Z2 model, and also a combination of those with a BNRT model. Moreover, we work with a modified version of the BNRT model, which breaks the Z2 × Z2 symmetry of the original BNRT potential, coupled with the sine-Gordon and with the standard Z2 models. We show that our approach can be straightforwardly elevated to N fields. All the computations are made analytically and some parameters restriction is put forward in order to get in touch with complete and realistic cosmological scenarios. SISSA-Scuola Internazionale Superiore di Studi Avanzati, via Bonomea, 265 Departamento de Física ITA Instituto Tecnológico de Aeronáutica, São José dos Campos UNESP Universidade Estadual Paulista UFCG Universidade Federal de Campina Grande Unidade Acadêmica de Física, Caixa Postal 10071 Departamento de Física Instituto Tecnológico de Aeronáutica-ITA, São José dos Campos UNESP Universidade Estadual Paulista

10 pages, 9 figures, 1 table. Published in Brazilian Journal of Physics; International audience; In tokamaks, modification of the plasma profiles can reduce plasma transport, improving particle confinement. However, this improvement is still not completely understood. In this work, we consider a drift wave test particle model to investigate the influence of the electric and magnetic field profiles on plasma transport. Test particle orbits subjected to ExB drift are numerically integrated and their transport coefficient is obtained. We conclude that sheared profiles reduce particle transport, even for high amplitude perturbations. In particular, nonmonotonic electric and magnetic fields produce shearless transport barriers, which are particularly resistant to perturbations and reduce even more the transport coefficient.

Nontwist area-preserving maps violate the twist condition along shearless invariant curves, which act as transport barriers in phase space. Recently, some plasma models have presented multiple shearless curves in phase space and these curves can break up independently. In this paper, we describe the different shearless curve breakup scenarios of the so-called biquadratic nontwist map, a recently proposed area-preserving map derived from a plasma model, that captures the essential behavior of systems with multiple shearless curves. Three different scenarios are found and their dependence on the system parameters is analyzed. The results indicate a relation between shearless curve breakup and periodic orbit reconnection-collision sequences. In addition, even after a shearless curve breakup, the remaining curves inhibit global transport., Comment: 12 pages, 7 figures

International audience; Stochastic linear modelling proposed in Tissot, Mémin & Cavalieri (J. Fluid Mech., vol. 912,8 2021, A51)is based on classical conservation laws subject to a stochastic transport. Once linearised around the mean flow and expressed in the Fourier domain, the model has proven its efficiency to predict the structure of the streaks of streamwise velocity in turbulent channel flows. It has been in particular demonstrated that the stochastic transport by unresolved incoherent turbulence allows us to better reproduce the streaks through lift-up mechanism. In the present paper, we focus on the study of streamwise-elongated structures, energetic in the buffer and logarithmic layers. In the buffer layer, elongated streamwise vortices, named rolls, are seen to result from coherent wave-wave non-linear interactions, which have been neglected in the stochastic linear framework. We propose a way to account for the effect of these interactions in the stochastic model by introducing a stochastic forcing, which replaces the missing non-linear terms. In addition, we propose an iterative strategy in order to ensure that the stochastic noise is decorrelated from the solution, as prescribed by the modelling hypotheses. We explore the prediction abilities of this more complete model in the buffer and logarithmic layers of channel flows at Reτ = 180, Reτ = 550 and Reτ = 1000. We show an improvement of predictions compared to resolvent analysis with eddy viscosity, especially in the logarithmic layer.

Dans le contexte des systèmes de télécommunication, la technologie photonique est apparue pour répondre à la demande de bande passante. Elle a depuis fait l'objet de recherches croissantes et a été incorporée dans des systèmes destinés au spatial. Grâce à cette technologie, il est possible d'ajouter de nouvelles fonctionnalités aux équipements traditionnels de communication par radiofréquence ou de les utiliser dans des terminaux laser pour la communication optique en espace libre. Ce travail de recherche porte sur l'utilisation de la technologie photonique dans le sous-système de communication par satellite. Il se concentre donc sur un sous-système utilisant les communications par radiofréquence (RF) et un autre utilisant les communications optiques en espace libre (FSO) pour un satellite fonctionnant sur une orbite terrestre basse (LEO). Le modulateur vectoriel micro-ondes basé sur la technologie photonique a été présenté et discuté pour le sous-système utilisant les communications RF afin de remplacer l'étage de modulation traditionnel d'une charge utile de transmission. Ce modulateur photonique utilise un arrangement de modulateur électro-optique Mach-Zehnder (MZM) pour mettre en œuvre la modulation numérique de la porteuse micro-onde. La dérive dans le temps de la polarisation en tension continue du MZM, entraînant une dégradation de la qualité du signal modulé, une solution innovante pour un contrôle automatique de la polarisation (ABC) a été proposée. Contrairement aux méthodes rapportées jusqu'à présent dans la littérature, ce contrôle automatique de la polarisation est basé sur l'analyse des signaux I/Q afin de générer des étapes de tension pour la polarisation du modulateur photonique. En tenant compte du fait que la liaison satellite fonctionne généralement dans les bandes S et X pour la transmission (TT&C) et la transmission d'images avec des schémas de modulation QPSK, 8PSK et 16QAM, l'ABC a été évalué par une technique de co-simulation. En conséquence, l'ABC a corrigé les trois schémas en quelques étapes. Pour le système FSO, une boucle à verrouillage de phase optique (OPLL) a été étudiée pour récupérer les données d'un signal optique modulé numériquement dans un récepteur à détection cohérente. Contrairement aux OPLL analogiques traditionnelles, une OPLL entièrement numérique a été mise en œuvre et soutenue par une technique de co-simulation. La motivation première était la possibilité d'utiliser un détecteur de phase numérique à la place du détecteur analogique pour fournir une erreur de phase. De plus, la caractéristique de gain du détecteur de phase numérique, indépendante du niveau du signal d'entrée, lui permet d'être utilisé dans des régimes d'évanouissement. L'OPLL numérique a été évaluée à l'aide de taux d'échantillonnage doubles sous un bruit gaussien additif et trois scénarios de turbulence atmosphérique qui induit un évanouissement de puissance sur le signal optique transmis. De plus, la propagation d'un signal optique modulé numériquement dans une trajectoire oblique de satellite LEO a été considérée avec un débit binaire de 20 Gbits/s et un schéma de modulation QPSK. Il a été démontré que les détecteurs de phase analogiques traditionnels ne sont pas adaptés aux systèmes en régime d'évanouissement. Par conséquent, le détecteur de phase numérique s'est avéré être une alternative à la mise en œuvre d'OPLL pour le récepteur de systèmes FSO utilisant la détection cohérente. Ansi, la technologie photonique a été analysée pour améliorer les charges utiles de satellites et augmenter la bande passante de futurs liens optiques de communications. In the telecommunication systems context, photonic technology has emerged to meet the bandwidth demand and has since been increasingly researched and incorporated into systems for space use. This technology makes it possible to add new functionalities to traditional radio-frequency communication equipment and use it on laser terminals for optical communication in free space.This research work focuses on the use of photonic technology in a satellite communication subsystem. Hence, the focus was on one subsystem using radio-frequency (RF) communications and another using optical communication in free space (FSO) for a satellite operating in a low Earth orbit (LEO).The microwave vector modulator based on photonic technology was presented and discussed for the subsystem using RF communications to replace the traditional modulation stage of a transmitter payload. This photonic modulator uses an arrangement of Mach-Zehnder electro-optic modulator (MZM) to implement the digital modulation of the microwave carrier. As the MZM presents a dc bias drift over time, resulting in a poor quality of the modulated signal, a novel automatic bias control (ABC) was proposed. Unlike previous methods reported so far in the literature, this ABC is based on analyzing the I/Q signals to generate voltage steps for the photonic modulator bias. Considering that satellite link usually operates in S and X bands for (TT&C) and image transmission with QPSK, 8PSK, and 16QAM modulation schemes, the ABC was evaluated using a co-simulation technique. As a result, the ABC corrected these schemes in a few steps.For the FSO system, an optical phase-locked loop (OPLL) was discussed to retrieve the data for an optical digitally modulated signal in a coherent detection receiver. Unlike traditional analog OPLLs, an all-digital OPLL was implemented and supported through a co-simulation technique. The primary motivation was the possibility of using a digital phase detector in place of the analog one to provide phase error. Additionally, the gain characteristic of the digital phase detector, independent of the signal level input, enabled it to be used in fading regimes. The digital OPLL was evaluated using two-sample rates under additive Gaussian noise and three scenarios of turbulence atmospheric since it induces power fading on the transmitted optical signal. Moreover, the optical digitally modulated signal propagation in a LEO satellite slant path was considered with a bit rate of 20 Gbits/s and a QPSK modulation scheme. It was shown that the traditional analog phase detectors are unsuitable for systems under fading regimes. Hence, the digital phase detector proved to be an alternative to OPLL implementation for the receiver of FSO systems employing coherent detection.Therefore, the photonics technology is analyzed to improve satellite payloads and increase the bandwidth for future optical communication links.

9 pages and 6 figures; The L-H transition leads to a substantial reduction in transport levels in tokamaks and stellarators, improving the plasma confinement in such devices. After the transition, the plasma is in a high-confinement regime characterized by steep density and temperature gradients, with a large radial electric field at the plasma edge. In this paper, we show that, on using an ExB wave transport model on a test particle, such large electric fields can produce shearless transport barriers (STBs), which are related to the presence of non-monotonic sheared profiles, preventing almost all the chaotic flux at the plasma edge. The behavior of these barriers enables us to investigate the properties of the L-H transition as a function of the intensity of the electrostatic fluctuations and the depth of the typical radial electric field well-like profile, developed at plasma edge during the transition. We found that, as the radial electric field well depth increases, the shearless edge transport barrier becomes more resistant to perturbations and that, eventually, an improved plasma confinement regime is accessed. In this sense, we found results consistent with the experimental observations. In particular, the transition curve in the parameter plane associated with the STB has a fractal structure, thanks to the non-integrable nature of the associated Hamiltonian.

Made available in DSpace on 2021-06-25T11:00:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) We present a five dimensional cosmological metric that reveals a four-dimensional energy-momentum tensor. We analyse three cases for the resulting field equations: null, positive and negative cosmological constant Λ. For the case with null cosmological constant, we obtain a solution able to describe the radiation-dominated era of the universe. The positive five-dimensional cosmological constant case yields a bounce cosmological model. In the negative Λ case, the scale factor for the line element is obtained as a(t)=c5sinh([Formula presented]|Λ|t), where c5 is a constant. This solution can remarkably describe not only the late-time cosmic acceleration but also the non-accelerated stages of the cosmic expansion, namely the radiation and matter dominated epochs in a continuous form. We obtain an analytical equation of state capable of describing the different epochs of the universe and it reads as p=ω(z)ρ with ω(z)=[Formula presented][1−[Formula presented]], with p being the pressure of the universe, ρ its density and z is the redshift. In our model the constant c5 is related to the Hubble constant as H0=[Formula presented]coth[arcsinh([Formula presented])2] and this satisfactorily fits the observational data for the low redshift sample of the experimental measurements of the Hubble parameter, which results in H0=72.2−5.5+5.3 km s−1 Mpc−1 and c5=0.600−0.058+0.061. ITA - Instituto Tecnológico de Aeronáutica - Departamento de Física Universidade de São Paulo Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Rua do Matão 1226, Cidade Universitária Universidade Estadual Paulista (Unesp), Campus Experimental de Itapeva - R. Geraldo Alckmin 519 Departamento de Física Instituto de Ciências Ambientais Químicas e Farmacêuticas (ICAQF), Universidade Federal de São Paulo - UNIFESP, Rua São Nicolau no.210, Centro Universidade Estadual Paulista (Unesp), Campus Experimental de Itapeva - R. Geraldo Alckmin 519 FAPESP: 2013/26258-2 FAPESP: 2015/08476-0 FAPESP: 2017/05859-0 FAPESP: 2018/20689-7 CNPq: 313236/2018-6 CNPq: 438562/2018-6 CAPES: 88881.309870/2018-01 CAPES: 88882.446980/2019-01

Made available in DSpace on 2022-04-28T19:42:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-14 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Multilayered TiO2/TiO2−x/TiO2 films, deposited by twenty periodical interruptions of O2 flow during reactive sputtering deposition were submitted to photocatalytic tests and characterized. The O2 flow interruptions lasted 10 s, 38 s, 45 s, and 70 s, while the regular flow periods lasted 540 s. The photocatalytic tests were performed using UV irradiation from a mercury lamp and a solution of methylene blue dye. The best photocatalytic response was observed in samples corresponding to 10 s interruptions. The results show that the amount of degraded dye was increased by an average of 1.67 times in the interrupted flow sample as compared to the homogeneous TiO2 film deposited under similar conditions. The results show that this relatively simple deposition procedure can produce significant improvements to the photocatalytic activity of the TiO2-based catalysts. Graphic abstract: [Figure not available: see fulltext.] School of Sciences Graduate Program in Materials Science and Technology - POSMAT Universidade Estadual Paulista – UNESP Physics Department Fundamental Sciences Division – IEF Instituto Tecnológico de Aeronáutica – ITA School of Sciences Graduate Program in Materials Science and Technology - POSMAT Universidade Estadual Paulista – UNESP FAPESP: 2017/18916-2

Some internal transport barriers in tokamaks have been related to the vicinity of extrema of the plasma equilibrium profiles. This effect is numerically investigated by considering the guiding-center trajectories of plasma particles undergoing ExB drift motion, considering that the electric field has a stationary nonmonotonic radial profile and an electrostatic fluctuation. In addition, the equilibrium configuration has a nonmonotonic safety factor profile. The numerical integration of the equations of motion yields a symplectic map with shearless barriers. By changing the parameters of the safety factor profile, the appearance, and breakup of these shearless curves are observed. The successive shearless curves breakup and recovering is explained using concepts from bifurcation theory. We also present bifurcation sequences associated to the creation of multiple shearless curves. Physical consequences of scenarios with multiple shearless curves are discussed., 18 pages, 9 figures. Replacement improved the text

Area-preserving nontwist maps are used to describe a broad range of physical systems. In those systems, the violation of the twist condition leads to nontwist characteristic phenomena, such as reconnection-collision sequences and shearless invariant curves that act as transport barriers in the phase space. Although reported in numerical investigations, the shearless bifurcation, i.e., the emergence scenario of multiple shearless curves, is not well understood. In this work, we derive an area-preserving map as a local approximation of a particle transport model for confined plasmas. Multiple shearless curves are found in this area-preserving map, with the same shearless bifurcation scenario numerically observed in the original model. Due to its symmetry properties and simple functional form, this map is proposed as a model to study shearless bifurcations., 16 pages, 10 figures

International audience

The free surface motion in moving containers is an important physical phenomenon for many engineering applications. One way to model the free surface motion is by employing shallow water equations (SWEs). The port-Hamiltonian systems formulation is a powerful tool that can be used for modeling complex systems in a modular way. In this work, we extend previous work on SWEs using the port-Hamiltonian formulation, by considering the two-dimensional equations under rigid body motions. The resulting equations consist of a mixed-port-Hamiltonian system, with finite and infinite-dimensional energy variables and ports. 2000 Math Subject Classification: 34K30, 35K57, 35Q80, 92D25

Made available in DSpace on 2020-12-12T01:13:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 To enhance the removal of vegetal oil from water, the influence of the concentration of fibers from sugarcane bagasse pretreated by the steam explosion as reinforcement in polyurethane foam was used. The composites were obtained by mass mixing the polyol with the prepolymer (1: 1) and reinforced with 5% to 20% (wt/wt) sugarcane bagasse fibers. The fibers, composites and pure polyurethane were characterized by scanning electron microscopy (SEM), X-Ray Diffraction (XRD) and Surface area measurements (BET). Sorption tests were carried out on the fibers, pure polyurethane (PU) and composites. The sorption capacity of the composites was evaluated as a function of the fiber content inserted in the matrix. When applied as the oil sorbents, it was found that the composites reinforced with pretreated fibers presented better results, due to defibrillation of the fiber and the increase of its contact area dispersed in the polymer. Efficient removal increases with increasing concentration of fibers reinforced in polyurethane. Department of Science and Aerospace Technology Instituto Tecnológico de Aeronáutica Department of Mechanical and Energy Universidade do Estado do Rio de Janeiro Department of Materials and Technology São Paulo State University (Unesp) Department of Chemistry Engineering Universidade de São Paulo Department of Materials and Technology São Paulo State University (Unesp)

Ecosystem services (ES) are all the benefits provided by ecosystems essential to subsistence, human well-being, and economic development, and, consequently, their recognition is fundamental for sustainable territorial planning. To identify the priority ES provided by the APA of the Alluvial Plains of the Paraíba do Sul and Jaguari Rivers, a region fully integrated into the urban fabric of São José dos Campos (SP), a collaborative study was developed to obtain the environmental perception of location key-actors - public agents, researchers, and APA residents. The analysis was developed from interpreting maps of use and occupation of the territory and adaptation of the Rapid Participatory Diagnosis (RPD) methodology recommended in the TEEB Regional/Local context. The results reiterated the importance of the region, already legally protected, to ensure the local environmental quality and identified the priority ES: freshwater, photosynthesis, nutrient cycle, local microclimate, and regulation of water flows. Resumen Los servicios ecosistémicos (SE) son todos los beneficios que arreglan los ecosistemas esenciales para los medios de vida, el bienestar humano y el desarrollo económico. En consecuencia, su reconocimiento es fundamental para la planificación territorial sostenible. Con el fin de identificar los SE prioritarios proporcionados por la APA de las Llanuras Aluviales del Paraíba do Sul y Jaguari Río, que son totalmente integrada con el tejido urbano de São José dos Campos (SP), se realizó un estudio colaborativo para obtener la percepción ambiental de las partes interesadas: agentes públicos, investigadores y vecinos de la APA. El análisis se desarrolló a partir de la interpretación de mapas de uso y ocupación del territorio y la adaptación de la metodología de Diagnóstico Rápido Participativo promovida en el contexto TEEB regional/local. Los resultados reiteraron la importancia de la región para asegurar la calidad ambiental local y identificaron que los tres SE prioritarios eran: agua dulce, fotosíntesis y ciclo de nutrientes. Resumo Serviços ecossistêmicos (SE) são todos os benefícios fornecidos pelos ecossistemas essenciais à subsistência, bem-estar humano e desenvolvimento econômico e, por consequência, seu reconhecimento é fundamental para o planejamento territorial sustentável. Com objetivo de identificar os SE prioritários fornecidos pela APA das Planícies Aluvionares do Rio Paraíba do Sul e Jaguari, região totalmente integrada à malha urbana de São José dos Campos (SP), realizou-se um estudo colaborativo visando obter a percepção ambiental de atores-chave locais - agentes públicos, pesquisadores e moradores da APA. A análise foi desenvolvida a partir da interpretação de mapas de uso e ocupação do território e adaptação da metodologia Diagnóstico Rápido Participativo (DRP) preconizada no contexto TEEB Regional/Local. Os resultados reiteraram a importância da região, já protegida legalmente, para assegurar a qualidade ambiental local e identificou que os SE prioritários são: água doce, fotossíntese, ciclo de nutrientes, microclima local e regulação dos fluxos d’água.

Made available in DSpace on 2022-05-01T12:09:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 This note is concerned with conditions on a set of non-singular matrices (Formula presented.), (Formula presented.), so that any convex combination of these matrices is also non-singular. The first part of the note points out that Theorem 2.3 in a previous paper [Beteto et al. (2021). Less conservative conditions for robust LQR-state derivative controller design: An LMI approach. International Journal of Systems Science] provides only necessary conditions, which are not sufficient in the general case. In the second part, some stability results based on Linear Matrix Inequalities (LMIs) for a class of fractional order systems are used to establish new sufficient conditions. Numerical examples are presented for illustration. The results suggest that the new LMI conditions may be less conservative compared to a test proposed in the literature on P-matrices, and also to a positive-definiteness test based on matrix cross-products. Electronic Engineering Division Instituto Tecnológico de Aeronáutica (ITA), SP Department of Electrical Engineering São Paulo State University (UNESP) School of Engineering, SP Faculty of Mathematics and Computer Science Adam Mickiewicz University Department of Electrical Engineering São Paulo State University (UNESP) School of Engineering, SP

Made available in DSpace on 2022-04-28T19:47:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 The influence of the oxygen gas supply on the stoichiometry, structure, and orientation texture of polycrystalline cobalt oxide films was investigated in this study. The films were grown by direct current reactive magnetron sputtering using a metallic Co target and different O2 inlet flow rates (0.5-5.0 SCCM). The deposition power (80 W), the argon gas flow (40 SCCM), and the total working pressure (0.67 Pa) were kept constant during depositions. The results evidence a strong influence of the oxygen flow over the film's stoichiometry and structure, where low oxygen flows (2.5 SCCM) favor the spinel Co3O4 phase formation. The coexistence of monoxide and tetraoxide phases is only observed for the 2.5 SCCM oxygen flow condition. Strain effects related to the oxygen partial pressure are also observed and discussed. Computer simulations of the reactive sputtering growth supported the analysis of the film properties and its correlation to the oxygen partial pressure. Faculdade de Ciências Universidade Estadual Paulista, São Paulo Laboratório de Plasmas e Processos - LPP Instituto Tecnológico de AeronáUtica, São Paulo Faculdade de Ciências Universidade Estadual Paulista, São Paulo

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:48:28Z No. of bitstreams: 1 S0100-40422002000200009.pdf: 450827 bytes, checksum: 142dd0faa1c95824440dc412d3101681 (MD5) Made available in DSpace on 2013-08-22T18:48:28Z (GMT). No. of bitstreams: 1 S0100-40422002000200009.pdf: 450827 bytes, checksum: 142dd0faa1c95824440dc412d3101681 (MD5) Previous issue date: 2002-05-01 Made available in DSpace on 2013-09-30T19:38:24Z (GMT). No. of bitstreams: 2 S0100-40422002000200009.pdf: 450827 bytes, checksum: 142dd0faa1c95824440dc412d3101681 (MD5) S0100-40422002000200009.pdf.txt: 20892 bytes, checksum: 4377c87276e5a06915bf001d087704f2 (MD5) Previous issue date: 2002-05-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T14:18:51Z No. of bitstreams: 2 S0100-40422002000200009.pdf: 450827 bytes, checksum: 142dd0faa1c95824440dc412d3101681 (MD5) S0100-40422002000200009.pdf.txt: 20892 bytes, checksum: 4377c87276e5a06915bf001d087704f2 (MD5) Made available in DSpace on 2014-05-20T14:18:51Z (GMT). No. of bitstreams: 2 S0100-40422002000200009.pdf: 450827 bytes, checksum: 142dd0faa1c95824440dc412d3101681 (MD5) S0100-40422002000200009.pdf.txt: 20892 bytes, checksum: 4377c87276e5a06915bf001d087704f2 (MD5) Previous issue date: 2002-05-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The reaction between hydroxy-terminated polybutadiene and isophorone diisocyanate constitutes the base of the curing process of the most composite solid propellant used in the propulsion of solid rocket propellant. In this work, differential scanning calorimetry and viscosity measurements were used to evaluate the effect of the ferric acetylacetonate catalyst concentration on the reaction between HTBR and IPDI. These analyses show one exotherm, which shifts to lower temperatures as the catalyst concentration increases. The viscosity analyses show that the increase of temperature causes, at first, a reduction in the mixture viscosity, reaching a minimum range called gelification region (increasing the crosslinking density). Universidade Estadual Paulista Instituto de Química Centro Técnico Aeroespacial Instituto Tecnológico de Aeronáutica Departamento de Física Centro Técnico Aeroespacial Instituto Tecnológico de Aeronáutica Divisão de Química Centro Técnico Aeroespacial Instituto de Aeronáutica e Espaço Divisão de Materiais Universidade Estadual Paulista Instituto de Química

Made available in DSpace on 2022-05-01T08:44:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-09-01 In this work, an optical fiber was coated by a thin-film metal layer to work as a fiber optical phase modulator based on thermal effect. This device was assembled in one of the arms of an all-fiber Michelson interferometer stabilized by a nonlinear control system based on variable structure and sliding modes. The frequency response reached 200 Hz, which can be considered high for a device based on the thermal effect. Compared with a fiber optical phase modulator based on the piezoelectric effect, the thermal modulator presented a higher scale factor per meter of optical fiber, showing the potential to work as a simple, low-cost, small-sized, short length, lightweight, and low-voltage fiber optical phase modulator. Aeronautics Institute of Technology [Instituto Tecnológico de Aeronáutica-ITA], Praça Mal. Eduardo Gomes 50, SP Division of Photonics Institute for Advanced Studies [Instituto de Estudos Avançados-IEAv], Trevo Cel. Av. José A. A. do Amarante 1, SP Universidade Federal de São Paulo (UNIFESP), Av. Cesare Mansueto Giulio Lattes 1201, SP Department of Electrical Engineering São Paulo State University (UNESP), José Carlos Rossi Avenue 1370, SP Department of Electrical Engineering São Paulo State University (UNESP), José Carlos Rossi Avenue 1370, SP

Made available in DSpace on 2022-04-28T19:45:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-25 We investigate spanwise-coherent structures in the turbulent flow around airfoils, motivated by their connection with trailing-edge noise. We analyse well-resolved large-eddy simulations (LES) of the flow around NACA 0012 and NACA 4412 airfoils, both at a Reynolds number of 400 000 based on the chord length. Spectral proper orthogonal decomposition performed on the data reveals that the most energetic coherent structures are hydrodynamic waves, extending over the turbulent boundary layers around the airfoils with significant amplitudes near the trailing edge. Resolvent analysis was used to model such structures, using the mean field as a base flow. We then focus on evaluating the dependence of such structures on the domain size, to ensure that they are not an artefact of periodic boundary conditions in small computational boxes. To this end, we performed incompressible LES of a zero-pressure-gradient turbulent boundary layer, for three different spanwise sizes, with the momentum-thickness Reynolds number matching those near the airfoils trailing edge. The same coherent hydrodynamic waves were observed for the three domains. Such waves are accurately modelled as the most amplified flow response from resolvent analysis. The signature of such wide structures is seen in non-premultiplied spanwise wavenumber spectra, which collapse for the three computational domains. These results suggest that the spanwise-elongated structures are not domain-size dependent for the studied simulations, indicating thus the presence of very wide structures in wall-bounded turbulent flows. São Paulo State University (UNESP) Campus of São João da Boa Vista, SP Divisão de Engenharia Aeronáutica Instituto Tecnológico de Aeronáutica, SP Flow Kth Engineering Mechanics Royal Institute of Technology São Paulo State University (UNESP) Campus of São João da Boa Vista, SP

Submitted by arlindo kohlrausch (ajfk@uepg.br) on 2022-05-18T23:02:11Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Leticia Falcão Starck.pdf: 10046088 bytes, checksum: d5a6f9d3b91addd9670180ebec331cc1 (MD5) Made available in DSpace on 2022-05-18T23:02:11Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Leticia Falcão Starck.pdf: 10046088 bytes, checksum: d5a6f9d3b91addd9670180ebec331cc1 (MD5) Previous issue date: 2021-08-26 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Corpos de prova do aço inoxidável austenítico AISI 316L foram fabricados pela técnica de manufatura aditiva (MA). O comportamento mecânico e microestrutural foi investigado por meio de ensaios de tração com difração de raios X in situ utilizandose um simulador termomecânico situado na estação XTMS do LNLS, localizado no CNPEM. Foram estudadas três condições: 316L MA como fabricado, 316L MA após tratamento térmico de recozimento e 316L laminado (para comparação). Estudou-se o efeito do hidrogênio e de temperaturas negativas durante ensaio de tração uniaxial. Estas são condições as quais esse material é submetido em diversos setores da indústria. Destaca-se o uso desse aço na indústria de petróleo e gás natural. Uma vez que a microestrutura obtida em peças produzidas por MA é mais refinada e com diferentes morfologias em relação aos processamentos convencionais, o estudo do desempenho de peças produzidas por MA é de grande importância para sua correta implementação na indústria e substituição da manufatura subtrativa. O hidrogênio gera fragilização em componentes fabricados por processos convencionais. Para peças produzidas por MA, pode não haver a fragilização, dependendo dos parâmetros utilizados, devido ao refino microestrutural e transformações de fase. Neste trabalho, foram encontrados resultados em que não houve fragilização nas amostras fabricadas por MA. Observou-se mesmo nível de LRT para a amostra MA como fabricada e aumento de 17,9% no LRT para a condição tratada termicamente. Houve aumento de 40,7% e 55,1% na deformação para as condições MA como fabricada e tratada termicamente, respectivamente. Para as amostras de aço laminado, observou-se pouco efeito da hidrogenação. Em temperaturas criogênicas, ocorre aumento da tenacidade do material devido à ativação de outros mecanismos de deformação, supressão parcial de recuperação dinâmica (devido à baixa temperatura) e a transformações de fase, o que pode ser observado tanto em peças laminadas como fabricadas por MA Test specimens of AISI 316L austenitic stainless steel were fabricated by Additive Manufacturing (AM). Mechanical and microstructural behavior were investigated by tensile tests with in situ X-ray diffraction accomplished in a thermomechanical simulator situated in the XTMS station of LNLS, located in CNPEM. Three conditions were studied: 316L AM as-built, 316L AM after annealing heat treatment, and 316L asrolled (for comparison). The effect of hydrogen and negative temperatures were studied during uniaxial tensile tests. These conditions are applied to this type of material in several industry sectors. The use of this steel in the oil and natural gas industry stands out. Once the microstructure obtained by AM is more refined and has different morphologies when compared to conventional processes, the study of the performance presented by parts made by AM is very important for its correct implementation and substitution of the subtractive manufacturing. Hydrogen leads to the embrittlement of components produced by the conventional process. For parts built by AM, it may not occur, depending on the parameters used, due to the microstructural refinement and phase transformation. In this work, the results showed that there was no hydrogen embrittlement in the AM samples. It was observed similar levels of UTS for the AM as-built condition and an increase of 17.9% of UTS for the heat-treated condition. There was an increase of 40.7% and 55.1% in strain for the AM as-built and AM heat-treated conditions, respectively. For the as-rolled condition, it was observed a low influence of hydrogen in the mechanical behavior. In cryogenic temperatures, an increase of toughness occurs owing to activation of other deformation mechanisms, partial suppression of dynamic recovery (due to low temperature), and phase transformations, which can be observed in rolled specimens as well as in AM parts.

Barriers have been identified in magnetically confined plasmas reducing the particle transport and improving the confinement. One of them, the primary shearless barriers are associated to extrema of non-monotonic plasma profiles. Previously, we identified these barriers in a model described by a map that allows the integration of charged particles motion in drift waves for a long time scale. In this work, we show how the existence of these robust barriers depends on the fluctuation amplitude and on the electric shear. Moreover, we also find control parameter intervals for which these primary barriers onset and break-up are recurrent. Another noticeable feature, in these transitions, is the appearance of a layer of particle trajectory stickiness after the shearless barrier break-up or before its onset. Besides the mentioned primary barriers, we also observe sequences of secondary shearless barriers, not reported before, created and destroyed by a sequence of bifurcations as the main control parameters, the fluctuation amplitude and electric shear, are varied. Furthermore, in these bifurcations, we also find hitherto unknown double and triple secondary shearless barriers which constitute a noticeable obstacle to the chaotic transport., 12 pages, 28 figures. This article has been accepted by the Journal Physics of Plasmas. It can be found at: https://doi.org/10.1063/5.0056428

International audience; In shock wave/boundary layer interactions, two mechanisms have been recognized to drive the low-frequency unsteadiness of the reflected shock: upstream boundary layer forcing and downstream feedback. The current work presents a quantitative analysis of the causal mechanisms underlying such flow unsteadiness. The analysis is based on a large-eddy simulation database covering approximately 300 cycles of the low-frequency shock fluctuations in a Mach 2 turbulent boundary layer. This time span enables the accurate application of frequency-domain system identification methods targeting such low frequencies. The evaluation of the spectrum in the interaction zone indicates that the broadband low-frequency unsteadiness is predominantly two-dimensional and can be isolated via spanwise averaging. Empirically derived transfer functions are computed using the averaged flow field and indicate the occurrence of a feedback between the locations downstream of the flow separation and the shock fluctuations. The results indicate that this mechanism dominates over the upstream forcing of the interaction region. Accordingly, the computed transfer functions are also used as an estimation tool to predict the shock motion accurately; for the largest streamwise separation between input and output signals, correlations above 0.6 are observed between predictions and raw data. Computation of spectral proper orthogonal decomposition modes reveals the existence of upstream traveling waves in the leading spectral mode at the main shock frequency; higher frequencies do not exhibit this trend. Furthermore, the spectral modes obtained using selected flow regions downstream of the shock enable the reconstruction of a significant portion of the energy in the interaction zone. Finally, a linear stability analysis is conducted using the mean turbulent flow, showing the existence of upstream traveling waves. Evaluation of a vortex sheet model indicates that these upstream traveling modes are of acoustic nature. The predicted modes from this local analysis present a compelling match against the spectral modes, both in terms of the shape and phase speed of the fluctuations. The combined analysis of the techniques indicates that downstream disturbances are the dominant cause of shock oscillations in the present configuration, leading to shock motion by upstream traveling acoustic modes.

Made available in DSpace on 2022-04-28T19:41:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-07-01 When plasma instabilities arise in the post-sunset time, the so-called ionospheric plasma bubbles may develop, causing amplitude fades and phase oscillations, decreasing the availability and quality of transionospheric communication systems. In the regions where these bubbles appear, deep signal fading may occasionally reach the lowest levels and with loss of signal received for a certain period. In this work, a characterization of deep power fades is performed supported by a dataset covering 5 months of high-rate monitoring data collected at four different locations in Brazil in distinct S4 scenarios for the three available frequencies. Two aspects of the deep fading events were evaluated, the deepest fading attained per minute and the fading events deeper than −15 dB. The inter-frequency analysis showed that as S4 increases, the number of −15 dB fading occurrences increases for all bands and stations. The average number of occurrences reached approximately 7 and 9 cases per minute, respectively, for Presidente Prudente and São José dos Campos. Statistical analysis for fading events deeper than −15 dB obtained probabilities of 1.61%, 2.87% and 3.97%, respectively, for L1, L2C and L5 at Presidente Prudente. Regarding the value of the deepest fading event per minute, the larger difference between L1, L2C and L5 exhibits values around −11 dB at Presidente Prudente. For this station, the average deepest fading values achieved in L2C and L5 bands were nearly twice that of the L1. The results regarding the probability of a deepest fading less than −20 dB per minute for L5 signal present a probability of 1.38% in Fortaleza, while for Presidente Prudente and São José dos Campos, these values were 5.62% and 3.34%. Instituto Tecnológico de Aeronáutica–ITA Instituto de Aeronáutica e Espaço–IAE, SP Ciência e Tecnologia de São Paulo Instituto Federal de Educação EMBRAER, SP Universidade Estadual Paulista Júlio de Mesquita Filho–UNESP Universidade Estadual Paulista Júlio de Mesquita Filho–UNESP

Made available in DSpace on 2021-06-25T11:01:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) In this study, the potential antimicrobial activity of plasma-activated tap water (PAW) was evaluated against Staphylococcus aureus, Escherichia coli, and Candida albicans. For this, PAW was prepared in a gliding arc plasma system using two treatment conditions: stagnant water and water stirring by a magnetic stirrer, called moving water. Subsequently, their oxidation-reduction potential (ORP), pH, electrical conductivity (σ), and total dissolved solids (TDS) were monitored in different areas of the sample divided according to the depth of the beaker. It was observed that PAW obtained in dynamic conditions showed a more uniform acidity among the evaluated areas with pH 3.53 and ORP of 215 mV. Finally, standardized suspensions of Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 10799), and Candida albicans (SC 5314) were treated with PAW, and the reduction of viable cells determined the antimicrobial effect. Our results indicate that the tap water, activated by plasma treatment using gliding arc, is an excellent inactivation agent in the case of Staphylococcus aureus and Escherichia coli. On the other hand, no significant antimicrobial activity was achieved for Candida albicans. Laboratório de Plasmas e Processos Instituto Tecnológico de Aeronáutica, Praça Marechal Eduardo Gomes 50 Oral Biopathology Graduate Program São José dos Campos Institute of Science & Technology São Paulo State University UNESP Instituto de Ciência e Tecnologia Universidade Federal de São Paulo, Rua Talim 330 Faculty of Engineering (FEG) São Paulo State University (UNESP) Department of Environment Engineering São José dos Campos Institute of Science & Technology São Paulo State University UNESP Oral Biopathology Graduate Program São José dos Campos Institute of Science & Technology São Paulo State University UNESP Faculty of Engineering (FEG) São Paulo State University (UNESP) Department of Environment Engineering São José dos Campos Institute of Science & Technology São Paulo State University UNESP FAPESP: 18/01265-1 FAPESP: 19/05856-7 FAPESP: 19/25652-7 FAPESP: 20/10450-7 CNPq: 308127/2018-8 CNPq: 437921/2018-2 CNPq: 446545/2014-7

One common parameter of many clustering algorithms is the number k of clusters required to partition the data. This is the case of k-means, one of the most popular clustering algorithms from the Machine Learning literature, and its variants. Indeed, when clustering a dataset, the right number k of clusters to use is often not obvious, and choosing k automatically is a hard algorithmic problem. In this context, one popular procedure used to estimate the number of clusters present in a dataset is to run the clustering algorithm multiple times varying the number of clusters and one of the solutions obtained is chosen based on a given internal clustering validation measure (e.g., silhouette coefficient). This process can be very time consuming as the clustering algorithm must be run several times. In this paper we present some strategies that can be integrated to constrained clustering methods so as to recover automatically the number k of clusters. The idea is that constrained clustering algorithms allow one to incorporate prior information such as if some pairs of instances from the dataset must be placed in the same cluster or not. Still in the context of constrained clustering algorithms, in order to improve the quality of the pairwise constraints given as input to the algorithm, there are approaches that use active methods for pairwise constraint selection. In our proposed strategies we make use of the prior information provided by the pairwise constraints and the concept of neighborhood from active methods not only to build a partition, but also to identify automatically the number k of clusters in the data. Based on nine datasets, we show experimentally that our strategies, besides automatically recovering the number of clusters in the data, lead to the generation of partitions having high quality when evaluated by indicators of clustering performance such as the adjusted Rand index.

Variations of N,H and C-atoms density have been determined along the reduced pressure flowing afterglows of microwave R/N2-H2 and R/N2-CH4 discharges with R=N2, He and Ar. Density of H and C-atoms and other nitrogen active species such as N2(A), N2(X,v>13), N2+,NH, N(2D), CN were obtained from that of N-atoms calibrated by NO titration , using the method of band intensity ratios in several conditions (between early and late afterglows). It has been obtained in addition the density of O-atoms and NO molecules coming from air impurity. It has been deduced the wall destruction probability of H, O and C-atoms on the quartz afterglow tube: ?HR,N2 = (1-3) 10-3 , ?OR,N2 =(0.4-1) 10-3 and ?CN2=(0.7) 10-3. The effects of H and C –atoms on N-atoms inclusion inside TiO2 surfaces are reported.

[EN] Studies on reactivity of sugarcane bagasse ash (SCBA), obtained by an autogenous combustion process, with low loss on ignition and three different particle sizes were carried out (SCBA-1, SCBA-2 and SCBA-3). The ashes were characterized by their particle size distribution, chemical composition, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM). The ash with lowest particle size was SCBA-3, followed by SCBA-2, which both were finer than SCBA-1. Calcium hydroxide/SCBA blends were assessed by means of loss of electrical conductivity (Lc), TGA and FESEM. Portland cement/SCBA pastes were analyzed through isothermal calorimetry, TGA, FESEM and compressive strength. Results showed that SCBA with lowest particle size (SCBA-3) presented highest reactivity, which resulted in statically significant better compressive strength than that of control paste (with only Portland cement) after 28 days of curing. The improvement on compressive strength by employing SCBA-3 respect to control and SCBA-1 were 17.9 and 14.1%, respectively, after 180 days of curing., This study was financed in part by the Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ).

International audience; The presence of elongated streaks of high and low streamwise velocity in the shear layer of circular jets breaks the axisymmetry of their steady-state solution. If the streaks are considered to be part of the base flow, for the purpose of linear instability analysis, the instability eigenmodes are thus affected by their presence. The resulting changes of growth rate and spatial shapes of eigenmodes, related to the shear instability in jets, are investigated here for parallel base flows. Optimal streamwise vortices (rolls) with prescribed azimuthal periodicity are computed, such that the transient temporal growth of the streaks that they produce is maximal. The presence of nite-amplitude streaks requires the formulation of eigenvalue problems in a two-dimensional cross-plane. Sinuous rolls and streaks are found to have a stabilising effect on Kelvin-Helmholtz instability, whereas the varicose rolls and streaks have a destabilising effect. Absolute instability is not found to occur. This work shows that the effects of rolls and streaks need to be taken into account for more precise modelling of jet instability.

An approach to estimate the spatial curvature $\Omega_k$ from data independently of dynamical models is suggested, through kinematic parameterizations of the comoving distance ($D_{C}(z)$) with third degree polynomial, of the Hubble parameter ($H(z)$) with a second degree polynomial and of the deceleration parameter ($q(z)$) with first order polynomial. All these parameterizations were done as function of redshift $z$. We used SNe Ia dataset from Pantheon compilation with 1048 distance moduli estimated in the range $0.01, Comment: 9 pages, 8 figures. Text rewritten, references added and H(z) data have been replaced with cosmic chronometers in order to favour model independence

Self-similarity of wall-attached coherent structures in a turbulent channel at $Re_\tau=543$ is explored by means of resolvent analysis. In this modelling framework, coherent structures are understood to arise as a response of the linearised mean-flow operator to generalised, frequency-dependent Reynolds stresses, considered to act as an endogenous forcing. We assess the self-similarity of both the wall-attached flow structures and the associated forcing. The former are educed from direct numerical simulation data by finding the flow field correlated with the wall shear, whereas the latter is identified using a frequency space version of Extended Proper Orthogonal Decomposition (Bor\'{e}e, J. 2003 Extended proper orthogonal decomposition: a tool to analyse correlated events in turbulent flows. Experiments in fluids 35 (2), 188-192). The forcing structures identified are compared to those obtained using the resolvent-based estimation introduced by Towne \emph{et al}. (Towne, A., Lozano-Dur\'{a}n, A. & Yang, X. 2020 Resolvent-based estimation of space-time flow statistics. Journal of Fluid Mechanics 883, A17). The analysis reveals self-similarity of both wall-attached structures$-$in quantitative agreement with Townsend's hypothesis of self-similar attached eddies$-$and the underlying forcing, at least in certain components., Comment: 30 pages, 18 figures

Made available in DSpace on 2022-04-29T08:29:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-12-28 A comparative analysis of the breakup cross-sections, using continuum discretized coupled-channel approach, is presented for the weakly bound p-wave neutron-Li7 and nucleon-Be7 projectiles on the Pb208 target, by investigating the role of interaction effects between the core (Li7, Be7) with the target. The extra charge in the B8 has the effect to increase the Coulomb contribution in the breakup reaction channel. By fixing both projectile ground-state binding energies at 0.137 MeV (B8 experimental one), with incident energies at the Coulomb barrier and above, we found that the charge difference accounts for over 30% of the neutron-Be7 breakup cross sections, substantially larger than the corresponding one for proton-Be7. The large enhancement of the neutron-halo breakup cross-section with respect to the proton-halo case shown in this work is associated to dynamical effects coming from the excitation of the projectile internal continuum due to the nucleon-target and core-target interactions, together with the widely accepted static effects coming from the long wave-function tail of the weakly bound neutron. The interplay between these dynamical and static effects in the energy spectrum of the B8 fragments is visible, revealed by the peak of the energy distribution pushed to higher relative energies. This follows from the two-body final state interactions between the charged fragments distorted by the three-body reaction environment. Department of Physics University of South Africa, P.O. Box 392 Instituto Tecnológico de Aeronáutica Instituto de Física Teórica Universidade Estadual Paulista Instituto de Física Teórica Universidade Estadual Paulista

Made available in DSpace on 2021-06-25T10:13:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-12-25 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The demand for the development of more efficient, low emission, and high-performance aircraft have required new methods to obtain lighter materials, with higher temperature resistance and chemical stability. For these purposes, Environmental Barrier Coatings (EBC) are largely studied. EBC's are commonly obtained through Atmospheric Plasma Spray, where the process parameters, as well as the precursor characteristics, and its interaction with the plasma jet influence the properties of the deposited material. In this context, this work aims to deposit EBC on C/C composites through the high-velocity plasma spray (HVPS) using a new concept of hybrid SiO2 + ZrO2 precursor. For this, a solid load of 7% yttria-stabilized zirconia (7YSZ) is mixed in a Si(OH4) solution with concentrations of 10, 20, and 30 g/L. From Raman and XRD analyses, ZrSiO4 and SiC were identified, its formations occur due to the reactions of SiO2 with ZrO2 (7YSZ) and the SiO2 precursor with C/C substrate. Finally, we demonstrate the versatility of the HVPS process using a hybrid precursor, capable of producing micro/nanostructured EBC coatings. Laboratório de Plasmas e Processos - LPP Instituto Tecnológico de Aeronáutica – ITA/DCTA São Paulo State University - Unesp Instituto de Ciência e Tecnologia Center for Thermal spray Research at Stony Brook University São Paulo State University - Unesp Instituto de Ciência e Tecnologia CAPES: 88887.360983/2019-00

Linearisation of the Navier-Stokes equations about the mean of a turbulent flow forms the foundation of popular models for energy amplification and coherent structures, including resolvent analysis. While the Navier-Stokes equations can be equivalently written using many different sets of dependent variables, we show that the properties of the linear operator obtained via linearisation about the mean depend on the variables in which the equations are written prior to linearisation. For example, we show that using primitive and conservative variables leads to differences in the singular values and modes of the resolvent operator for turbulent jets, and that the differences become more severe as variable-density effects increase. This lack of uniqueness of mean-flow-based linear analysis provides new opportunities for optimizing models by specific choice of variables while also highlighting the importance of carefully accounting for the nonlinear terms that act as a forcing on the resolvent operator., 11 pages, 3 figures, accepted manuscript

Made available in DSpace on 2020-12-12T01:35:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Turbulent channel flow was analysed using direct numerical simulations at friction Reynolds numbers Reτ=180 and 550. The databases were studied using spectral proper orthogonal decomposition (SPOD) to identify dominant near-wall coherent structures, most of which turn out to be streaks and streamwise vortices. Resolvent analysis was used as a theoretical approach to model such structures, as it allows the identification of the optimal forcing and most amplified flow response; the latter may be related to the observed relevant structures obtained by SPOD, especially if the gain between forcing and response is much larger than what is found for suboptimal forcings or if the non-linear forcing is white noise. Results from SPOD and resolvent analysis were compared for several combinations of frequencies and wavenumbers. For both Reynolds numbers, the best agreement between SPOD and resolvent modes was observed for the cases where the lift-up mechanism from resolvent analysis is present, which are also the cases where the optimal resolvent gain is dominant. These results confirm the outcomes in our previous studies (Abreu et al., 2019; Abreu et al., 2020), where we used a DNS database of a pipe flow for the same Reynolds numbers. São Paulo State University (UNESP), Campus of São João da Boa Vista Divisão de Engenharia Aeronáutica Instituto Tecnológico de Aeronáutica FLOW Engineering Mechanics KTH Royal Institute of Technology São Paulo State University (UNESP), Campus of São João da Boa Vista

Made available in DSpace on 2018-12-11T17:23:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-01-13 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) We present a new version of the Brazilian developments on the Regional Atmospheric Modeling System (BRAMS), in which different previous versions for weather, chemistry, and carbon cycle were unified in a single integrated modeling system software. This new version also has a new set of state-of-the-art physical parameterizations and greater computational parallel and memory usage efficiency. The description of the main model features includes several examples illustrating the quality of the transport scheme for scalars, radiative fluxes on surface, and model simulation of rainfall systems over South America at different spatial resolutions using a scale aware convective parameterization. Additionally, the simulation of the diurnal cycle of the convection and carbon dioxide concentration over the Amazon Basin, as well as carbon dioxide fluxes from biogenic processes over a large portion of South America, are shown. Atmospheric chemistry examples show the model performance in simulating near-surface carbon monoxide and ozone in the Amazon Basin and the megacity of Rio de Janeiro. For tracer transport and dispersion, the model capabilities to simulate the volcanic ash 3-D redistribution associated with the eruption of a Chilean volcano are demonstrated. The gain of computational efficiency is described in some detail. BRAMS has been applied for research and operational forecasting mainly in South America. Model results from the operational weather forecast of BRAMS on 5km grid spacing in the Center for Weather Forecasting and Climate Studies, INPE/Brazil, since 2013 are used to quantify the model skill of near-surface variables and rainfall. The scores show the reliability of BRAMS for the tropical and subtropical areas of South America. Requirements for keeping this modeling system competitive regarding both its functionalities and skills are discussed. Finally, we highlight the relevant contribution of this work to building a South American community of model developers. Centro de Previsão de Tempo e Estudos Climáticos Instituto Nacional de Pesquisas Espaciais Divisão de Ciência da Computação Instituto Tecnológico de AeronáUtica Universidade Estadual Paulista (Unesp) Faculdade de Ciências Centro de Meteorologia de Bauru (IPMet) Departamento de Ciências Ambientais Universidade Federal de São Paulo Instituto de Astronomia Geofísica e Ciências Atmosféricas Universidade de São Paulo Departamento de Ciências Atmosféricas Universidade Federal de Campina Grande Embrapa Informática Agropecuária Instituto de Ciência e Tecnologia Universidade Federal de São Paulo Departamento de Ciências Atmosféricas e Climáticas Programa de Pós Graduação em Ciências Climáticas Universidade Federal Do Rio Grande Do Norte Centro de Ciências Do Sistema Terrestre Instituto Nacional de Pesquisas Espaciais Departamento de Geociências Universidade Federal de São João Del-Rei Laboratório Associado de Computação e Matemática Aplicada Instituto Nacional de Pesquisas Espaciais Instituto de Ciências Agrárias e Ambientais Mediterrânicas Universidade de Évora Centro Interdisciplinar de Desenvolvimento em Ambiente Gestão Aplicada e Espaço Universidade Lusófona de Humanidades e Tecnologia Campo Grande Faculdade de Meteorologia Universidade Federal de Pelotas Universidade Tecnológica Federal Do Paraná Universities Space Research Association Goddard Earth Sciences Technology and Research at the Global Modeling and Assimilation Office NASA Goddard Space Flight Center Universidade Estadual Paulista (Unesp) Faculdade de Ciências FAPESP: 2014/01563-1 FAPESP: 2014/01564-8 FAPESP: 2015/10206-0 CNPq: 306340/2011-9

International audience; The propagation of acoustic waves in a 2D geometrical domain under mixed boundary control is here described by means of the port-Hamiltonian (pH) formalism. A finite element based method is employed to obtain a consistently discretized model. To construct a model with mixed boundary control, two different methodologies are detailed: one employs Lagrange multipliers, the other relies on a virtual domain decomposition to interconnect models with different causalities. The two approaches are assessed numerically, by comparing the Hamiltonian and the state variables norm for progressively refined meshes.

International audience; The core part of the program system COLUMBUS allows highly efficient calculations using variational multireference (MR) methods in the framework of configuration interaction with single and double excitations (MR-CISD) and averaged quadratic coupled-cluster calculations (MR-AQCC), based on uncontracted sets of configurations and the graphical unitary group approach (GUGA). The availability of analytic MR-CISD and MR-AQCC energy gradients and analytic nonadiabatic couplings for MR-CISD enables exciting applications including, e.g., investigations of π-conjugated biradicaloid compounds, calculations of multitudes of excited states, development of diabatization procedures, and furnishing the electronic structure information for on-the-fly surface nonadiabatic dynamics. With fully variational uncontracted spin-orbit MRCI, COLUMBUS provides a unique possibility of performing high-level calculations on compounds containing heavy atoms up to lanthanides and actinides. Crucial for carrying out all of these calculations effectively is the availability of an efficient parallel code for the CI step. Configuration spaces of several billion in size now can be treated quite routinely on standard parallel computer clusters. Emerging developments in COLUMBUS, including the all configuration mean energy multiconfiguration self-consistent field method and the graphically contracted function method, promise to allow practically unlimited configuration space dimensions. Spin density based on the GUGA approach, analytic spin-orbit energy gradients, possibilities for local electron correlation MR calculations, development of general interfaces for nonadiabatic dynamics, and MRCI linear vibronic coupling models conclude this overview.

A three-atom molecule AAB, formed by two identical bosons A and a distinct one B, is studied by considering coupled channels close to a Feshbach resonance. It is assumed that the subsystems AB and AA have, respectively, one and two channels, where, in this case, AA has open and closed channels separated by an energy gap. The induced three-body interaction appearing in the single channel description is derived using the Feshbach projection operators for the open and closed channels. An effective three-body interaction is revealed in the limit where the trap setup is tuned to vanishing scattering lengths . The corresponding homogeneous coupled Faddeev integral equations are derived in the unitarity limit. The s-wave transition matrix for the AA subsystem is obtained with a zero-range potential by a subtractive renormalization scheme with the introduction of two finite parameters, besides the energy gap. The effect of the coupling between the channels in the coupled equations is identified with the energy gap, which essentially provides an ultraviolet scale that competes with the van der Waals radius - this sets the short-range physics of the system in the open channel. The competition occurring at short distances exemplifies the violation of the ``van der Waals universality" for narrow Feshbach resonances in cold atomic setups. In this sense, the active role of the energy gap drives the short-range three-body physics., Comment: 22 pages, preprint

International audience; We extend the resolvent-based estimation approach recently introduced by Towne etal. (J. Fluid Mech., vol. 883, 2020, A17) to obtain optimal, non-causal estimates of time-varying flow quantities from low-rank measurements. We derive optimal transfer functions between the measurements and certain nonlinear terms that act as a forcing on the linearised Navier–Stokes equations, and show that the resulting transfer function to the flow state is equivalent to a multiple-input, multiple-output Wiener filter if the colour of the forcing statistics is known. A matrix-free implementation is developed based on integration of the direct and adjoint linearised Navier–Stokes operators, enabling application to the large systems encountered for transitional and turbulent flows without the need for a priori model reduction. Using a linearised Ginzburg–Landau problem, we show that the non-casual resolvent-based method outperforms a casual Kalman filter for general sensor configurations and recovers the Kalman filter transfer function in specific cases, leading to causal estimates at a significantly reduced computational cost. Additionally, our method is shown to be more accurate and robust than popular approaches based on truncation of the resolvent operator to its leading modes. The applicability of the method to transitional and turbulent flows is demonstrated via application to a (linearised) transitional boundary layer and a (nonlinear) turbulent channel flow. Errors on the order of 2 % are achieved for the boundary layer, and the channel flow case highlights the need to account for the forcing colour to achieve accurate flow estimates. In practice, our method can be used as a post-processing tool to reconstruct unmeasured quantities from limited experimental data, and, in cases where the transfer function can be accurately truncated to its causal components, as a low-cost estimator for flow control.