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Analysis of the Mechanical Properties of the Sintered Composite FeCuC in Two Different Atmospheres

Journal of Mechanics Engineering and Automation 2015年第1期5卷 33-38页

作者： Clayton Andre de Oliveira Motta Jose de Souza marcelo salvador coser Alex Fabiano Bueno Lirio Schaeffer Bernardo Poras Reis Hamudy Munir Abou Arabi Lucas Soares de Almeida Department of Mechanical Engineering UniRitter Laureate International Universities Porto Alegr 91849-440 Brasil LdTM (Laboratorio de Transformacao Meednica) Universidade Federal do Rio Grande do Sul Porto Alegre 91501-970 Brasil Programa de Pos-Graduacao em Engenharia e Tecnologia Pontificia Universidade Catolica do Rio Grande do Sul Porto Alegre90619-900 Brasil Department of Mechanical Engieering Universidade do Vale do Rio dos Sinos Sao Leopoldo 93022-000 Brasil

This study aimed to analyze the mechanical properties of the compound FeCuC when compacted at varying pressures and sintered in two different types of furnaces. Besides the different models of furnace, the working atmospheres were varied: one is being composed with argon gas and another constituted with a balancing nitrogen and hydrogen. Atmospheres vary with the amount of production and the type of equipment used. The compound generated is used in the manufacture of rings for mechanical seals and is currently manufactured by the sintering process in passing furnace. The sintering was performed in a static furnace with argon atmosphere and compared with the same compound sintered in passage furnace with hydrogen and nitrogen atmosphere. The analysis of the properties of the tested material was performed with the aid of metallography using a scanning electron microscope, which verified the particle size distribution, chemical elements and pores present. Brinell hardness and Vickers micro hardness tests were also used to analyze the properties of this material after completion of the two processes. Thus, the research carried out has shown that variations may occur in the mechanical properties when processed in different furnace types and different sintering atmospheres.

关键词：烧结过程氩气氛力学性能扫描电子显微镜复合化合物相机械性能氮气气氛

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Acute kidney injury and electrolyte disorders in COVID-19

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World Journal of Virology 2022年第5期11卷 283-292页

作者： Gabriel Martins Nogueira Noel Lucas Oliveira Rodrigues Silva Ana Flávia Moura marcelo Augusto Duarte Silveira JoséA Moura-Neto Department of Medicine Bahiana School of Medicine and Public HealthSalvador 40290-000BahiaBrazil Department of Nephrology D’Or Institute for Research and EducationHospital São RafaelSalvador 41253900BahiaBrazil

Acute kidney injury(AKI)and electrolyte disorders are important complications of hospitalized coronavirus disease 2019(COVID-19)patients.AKI is thought to occur due to multiple pathophysiological mechanisms,such as multiple organ dysfunction(mainly cardiac and respiratory),direct viral entry in the renal tubules,and cytokine release syndrome.AKI is present in approximately one in every ten hospitalized COVID-19 patients.The incidence rates of AKI increase in patients who are admitted to the intensive care unit(ICU),with levels higher than 50%.Additionally,renal replacement therapy(RRT)is used in 7%of all AKI cases,but in nearly 20%of patients admitted to an ICU.COVID-19 patients with AKI are considered moderate-to-severe cases and are managed with multiple interdisciplinary conducts.AKI acts as a risk factor for mortality in severe acute respiratory syndrome coronavirus 2 infection,especially when RRT is needed.Electrolyte disorders are also common manifestations in hospitalized COVID-19 patients,mainly hyponatremia,hypokalemia,and hypocalcemia.Hyponatremia occurs due to a combination of syndrome of inappropriate secretion of antidiuretic hormone and gastrointestinal fluid loss from vomiting and diarrhea.When it comes to hypokalemia,its mechanism is not fully understood but may derive from hyperaldosteronism due to renin angiotensin aldosterone system overstimulation and gastrointestinal fluid loss as well.The clinical features of hypokalemia in COVID-19 are similar to those in other conditions.Hypocalcemia is the most common electrolyte disorder in COVID-19 and seems to occur because of vitamin D deficiency and parathyroid imbalance.It is also highly associated with longer hospital and ICU stay.

关键词： COVID-19 SARS-CoV-2 Acute kidney injury Electrolyte disorders Renal dialysis

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Numerical Simulation of a Liquid Propellant Rocket Motor

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Journal of Thermal Science 2001年第1期10卷 83-86页

作者： Nicolas M.C. salvador, marcelo M. Morales, Carlos E.S.S. Migueis, Demetrio Bastos-Netto (INPE - National Institute for Space Research, Rod. Presidente Dutra km 40, Cachoeira Paulista, SP, Brazil 12630-000., e-mail:demetrio@yabae,cptec.inpe.br) INPE - National Institute for Space Research Cachoeira Paulista SP Brazil

This work presents a numerical simulation of the flow field in a liquid propellant rocket engine chamber and exit nozzle using techniques to allow the results to be taken as starting points for designing those propulsive systems. This was done using a Finite Volume method simulating the different flow regimes which usually take place in those systems. As the flow field has regions ranging from the low subsonic to the supersonic regimes, the numerical code used, initially developed for commpressible flows only, was modified to work proficiently in the whole velocity range. It is well known that codes have been developed in CFD, for either compressible or incompressible flows, the joint treatment of both together being complex even today, given the small number of. references available in this area. Here an existing code for compressible flow was used and primitive variables, the pressure, the Cartesian components of the velocity and the temperature instead of the conserved variables were introduced in the Euler and Navier-Stokes equations. This was done to penult the treatment at any Mach number. Unstructured meshes with adaptive refinements were employed here. The convective terms were treated with upwind first and second order methods. The numerical stability was kept with artificial dissipation and in the spatial coverage one used a five stage Runge-Kutta scheme for the Fluid Mechanics and the VODE (Value of Ordinary Differential Equations) scheme along with the Chemkin II in the chemical reacting solution. During the development of this code simulating the flow in a rocket engine, comparison tests were made with several different types of internal and external flows, at different velocities, seeking to establish the confidence level of the techniques being used. These comparisons were done with existing theortical results and with other codes already validated and well acceptal by the CFD community.

关键词：喷管数字模拟液体燃料火箭发动机

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Effect of Titanium on the Martensitic Transformation Temperature of Cu-14Al-4Ni Shape Memory Alloy Rapidly Solidified

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材料科学与工程（中英文A版） 2020年第3期10卷 81-88页

作者： Nicole Araujo Marília Bortolotto Marlon Silva marcelo Nava Pedro Lima Emmanuel Lima DATM Federal Institute of EducationScience and Technology of Bahia(IFBA)Salvador-BA40301-015Brazil Federal Institute of Education Science and Technology of Bahia–IFBABarreiras-BA47808-006Brazil Faculdade do Gama(FGA) Universityof Brasília(UnB)Gama-DF72444-240Brazil

The present research aimed to analyze the influence that different contents of titanium(x=0.5,0.6 and 0.7 wt.%)have on the martensitic transformation temperature of a Cu-14Al-4Ni(wt.%)SMA(shape memory alloy).The Cu-14Al-4Ni-xTi samples were casted in an arc-melting furnace and rapidly solidified.All samples underwent heat treatment in a tubular furnace at a temperature of 1,100°C for 30 min and water quenched at 25°C.Subsequently,samples were analyzed by SEM(scanning electron microscopy)with EDS(energy dispersive spectroscopy),XRD(X-ray diffraction)and DSC(differential scanning calorimeter).SEM images and XRD patterns showed that the presence of titanium modified the alloy’s microstructure,induced the formation of three titanium rich phases called“X”phase(CuNi2Ti,Cu3Ti and AlCu2Ti)and reduced the presence of the brittle phaseγ2(Cu9Al4)for samples with 0.6 and 0.7 wt.%Ti.The titanium added to the copper based SMA also functioned as a refiner,reducing GS(grain size)up to approximately 80%with the increase of Ti content.DSC results exhibited low enthalpy levels,hysteresis,as well as low start martensitic transformation temperatures.

关键词： Cu-14Al-4Ni titanium SMA martensitic transformation temperature “X”phase.

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Influence of Cu9Al4 Phase on Nanomechanical Behavior of Cu-14Al-4Ni-xTi Shape Memory Alloy Rapidly Solidified

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材料科学与工程（中英文A版） 2020年第3期10卷 96-102页

作者： Marlon Silva Igor Santos Marília Bortolotto Nicole Araújo Pedro Lima marcelo Nava Emmanuel Lima DATM Federal Institute of EducationScience and Technology of Bahia—IFBASalvador-BA 40301-015Brazil Faculdade do Gama—FGA Universityof Brasília—UnBGama-DF 72444-240Brazil

This paper aims to verify the Cu9Al4 phase influence on the nanomechanical behavior of the Cu-14Al-4Ni-xTi alloy obtained by rapid solidification with addition of different amounts of Ti.Using the Scanning Electron Microscopy(SEM),Atomic Force Microscopy(AFM),Energy Dispersion Spectroscopy(EDS)and X-Ray Diffraction(XRD),it was possible to perform the samples’microstructural characterization.In addition,the reduction of the Cu9Al4 phase precipitation and the X-phase appearance were verified according to the increase of the titanium percentage added.The nanomechanical behavior was evaluated by nanoindentation tests,which showed a significant decrease of the elastic modules and an increase of the Poisson coefficient’s according to the titanium amount.This research establishes that the reduction of Cu9Al4 phase implies on the increase of the capacity to dissipate energy.Therefore,the high damping capacity combined with the X-phase presence increases the super elasticity and the alloy ductility.

关键词： Cu-14Al-4Ni-xTi shape memory effect microstructure nanoindentation superelasticity.

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Identification of Artificial Neural Network Models for Three-Dimensional Simulation of a Vibration-Acoustic Dynamic System

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Open Journal of Acoustics 2013年第1期3卷 14-24页

作者： Robson S.Magalhaes Cristiano H.O.Fontes Luiz A.L.de Almeida marcelo Embirucu Programa de Pos-Graduacao em Engenharia Industrial Escola PolitecnicaUniversidade Federal da BahiaSalvadorBrasil

Industrial noise can be successfully mitigated with the combined use of passive and Active Noise Control (ANC) strategies. In a noisy area, a practical solution for noise attenuation may include both the use of baffles and ANC. When the operator is required to stay in movement in a delimited spatial area, conventional ANC is usually not able to adequately cancel the noise over the whole area. New control strategies need to be devised to achieve acceptable spatial coverage. A three-dimensional actuator model is proposed in this paper. Active Noise Control (ANC) usually requires a feedback noise measurement for the proper response of the loop controller. In some situations, especially where the real-time tridimensional positioning of a feedback transducer is unfeasible, the availability of a 3D precise noise level estimator is indispensable. In our previous works [1,2], using a vibrating signal of the primary source of noise as an input reference for spatial noise level prediction proved to be a very good choice. Another interesting aspect observed in those previous works was the need for a variable-structure linear model, which is equivalent to a sort of a nonlinear model, with unknown analytical equivalence until now. To overcome this in this paper we propose a model structure based on an Artificial Neural Network (ANN) as a nonlinear black-box model to capture the dynamic nonlinear behaveior of the investigated process. This can be used in a future closed loop noise cancelling strategy. We devise an ANN architecture and a corresponding training methodology to cope with the problem, and a MISO (Multi-Input Single-Output) model structure is used in the identification of the system dynamics. A metric is established to compare the obtained results with other works elsewhere. The results show that the obtained model is consistent and it adequately describes the main dynamics of the studied phenomenon, showing that the MISO approach using an ANN is appropriate for the simulation of the investigated process. A clear co

关键词： Neural Networks Nonlinear Identification Dynamic Models Distributed Parameter Systems Vibrate-Acoustic Systems

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Flexible Bronchoscopy as a Diagnostic and Therapeutic Method in Patients with Tracheobronchial Foreign Body

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International Journal of Clinical Medicine 2014年第12期5卷 704-710页

作者： marcelo Fouad Rabahi Luísa Oliveira de Paiva Mariana Almeida de Castro Orlando Roberto da Silva Neto Medical Clinic Department Medical School Federal University of Goias Goiania (GO) Brasil Medicine School Federal University of Goias Goiania (GO) Brasil

Objective: To analyze bronchoscopy as a diagnostic and therapeutic method in patients with tracheobronchial foreign body. Methods: We analyzed reports of flexible bronchoscopy with diagnose of tracheobronchial foreign body performed from 2003 to 2013 in São salvador Hospital, in Goiania, capital of Goiás. The analysis was based on: sex and age of the patients, airways and foreign body characteristics, foreign body localization, success rate and rate of bleeding. We calculated the frequencies after analyzing the data. Results: We analyzed 26 reports of the studied period and found that 57.7% of the patients were male with median age of 58.83 years old (+—13.79). The airways characteristics were normal in most of the cases. Sputum wasn’t found in 57.69% of the cases. Foreign bodies were located in right bronchus in 88.46% of the cases, and the extraction of them was successful in 80.76% of the cases. The absence of bleeding was reported in 96.15% of the cases. Conclusions: Flexible bronchoscopy is a notably successful method in management of tracheobronchial foreign bodies. Airways characteristics aren’t good indicatives of FB’s presence, once they are normal in most of the times.

关键词： Flexible Bronchoscopy Foreign Bodies Airway Management

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Correlation between Transport and Occurrence of Dengue Cases in Bahia

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通讯和计算机：中英文版 2014年第3期11卷 217-221页

作者： Hugo Saba Pereira Cardoso Jose Garcia Vivas Miranda Eduardo Manuel de Freitas Jorge marcelo A.Moret Department of Exact Sciences and Earth University of the State of Bahia Salvador 40000-000 Brazil Institute of Physics Federal University of Bahia Salvador 40000-000 Brazil Modelagem Computacional SENAI Cimatec Salvador 40000-000 Brazil

Dengue is a public health problem that presents complexity in its dissemination. The physical means of spreading and the dynamics of the spread between the municipalities need to be analyzed to guide effective public policies to combat this problem. This study shows a correlation between the exponent of criticality present in SOC (self-organized criticality) and the number of buses per week, identifying municipalities that exert important roles in the spread of dengue in Bahia, confirming transport as a physical means for the diffusion of dengue.

关键词：登革热运输亚州自组织临界性病例公共卫生问题物理方法公共政策

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Contextualized Analysis of Social Networks:Collaboration in Scientific Communities

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Social Networking 2014年第2期3卷 71-79页

作者： Maria Teresinha Tamanini Andrade Patrícia Braga Tereza Kelly Gomes Carneiro Núbia Moura Ribeiro marcelo A.Moret Hernane Borges de Barros Pereira Instituto Federal de Educacao Ciencia e Tecnologia Simoes FilhoBrazil Programa de Modelagem Computacional SENAI CimatecSalvadorBrazil Universidade Estadual de Ciencias da Saúde de Alagoas MaceioBrazil Universidade Estadual de Feira de Santana Feira de SantanaBrazil Universidade do Estado da Bahia SalvadorBrazil

Currently, the collaboration in scientific communities has been studied in order to explain, among other things, the knowledge diffusion. The quality of Graduate Programmes is often associated with the scientific collaboration. This paper discusses how scientific collaboration processes can be identified and characterized through social and complex networks. For this purpose, collaboration networks of bibliographic production, research projects, and committees of PhD theses and Masters’ dissertations by researchers from a graduate program in computational modeling were studied. The data were obtained from CAPES’ reports of the period from 2001 to 2009. Among the studied indices, centrality indices indicate the presence of prominent researchers who influence others and promptly interact with other researchers in the network. The indices of complex networks reveal the presence of the small-world (i.e. these networks are favorable to increase coordination between researchers) phenomenon and indicate a behavior of scale-free degree distribution (i.e. some researchers promote clustering more than others) for one of the studied networks.

关键词： Knowledge Production and Dissemination Collaboration Scientific Communities Network Theory Social Networks Complex Networks

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Tree-Fall Gaps Effects on Spider(Araneae)Assemblages in an Atlantic Forest Landscape in Northeastern Brazil

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Open Journal of Animal Sciences 2014年第3期4卷 118-133页

作者： marcelo Cesar Lima Peres Katia Regina Benati Alessandra Rodrigues S.de Andrade Marcos Vinicius Alvim Guimaraes Tercio da Silva Melo Antonio Domingo Brescovit Jacques Hubert Charles Delabie Territorial Planning and Social Development Catholic University of SalvadorSalvadorBrazil Ecology Center and Animal Conservation Universidade Catolica do SalvadorSalvadorBrazil Federal University of Bahia SalvadorBrazil Butantan Institute Collections Zoological LaboratorySao PauloBrazil Laboratory of Myrmecology UESC/CEPLACCentre for Cocoa ResearchIlheusBrazil

The study investigates the effect of spatial and temporal tree-fall gaps structure on spiders’ assemblage in an Atlantic forest fragmented area in Brazil. It was conducted in the Michelin Ecological Preserve-REM (Bahia), 190 ha forest remnant. Samples were collected on leaf-litter (50 × 50 cm) at five tree-fall gaps formations (2), within five adjacent primary forest and five inner edge parcels. During 16 months (between May 2009 and October 2012), 480 m2 leaf-litter samples were collected, from which spiders were extracted using mini-Winkler traps. The observed and estimated richness of spider’s species was higher at the edge

关键词： Atlantic Forest Edge Effect Habitat Selection Spatiotemporal Effect Neotropical Fauna

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