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Real-time river level estimation based on variations of radar reflectivity—a case study of the Quitandinha River watershed, Petrópolis, rio de janeiro (Brazil)

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Bulletin of Atmospheric Science and Technology 2021年第1-4期2卷 1-20页

作者： da Silva, Fabricio Polifke Rotunno Filho, Otto Corrêa Justi da Silva, Maria Gertrudes Alvarez Sampaio, Rafael João Pires, Gisele dornelles de Araújo, Afonso Augusto Magalhães Civil Engineering Program Alberto Luiz Coimbra Institute for Postgraduate Studies and Research in Engineering – COPPE Universidade Federal do Rio de Janeiro RJ Rio de Janeiro 21945-970 Brazil Engineering and Society Group Exact Sciences and Technologies School Universidade Iguaçu UNIG Av. Abílio Augusto Távora 2134 Jardim Nova Era RJ Nova Iguaçu 26275-580 Brazil Meteorology Laboratory Science and Technology Center Universidade Estadual do Norte Fluminense Darcy Ribeiro – UENF Avenida Brenand s.n. Imboassica RJ Macaé 27925-535 Brazil Department of Water Resources and Environment Polytechnic School Universidade Federal do Rio de Janeiro – UFRJ Av. Athos da Silveira Ramos CT Escola Politécnica Cidade Universitária RJ Rio de Janeiro 21941-590 Brazil

The real-time warning for flash floods represents one of the major challenges for monitoring centers and civil defenses due to the short time frame in which such phenomena occur. That situation often takes place particularly in mountainous regions where high slope rate favors an increase in the velocity of the water flow and it might generate conditions to impact the water level due to potential for provoking erosion, landslides, and debris flow. An initial one new and unique prototype of hydrometeorological relationship for real-time, site-tunable, water level for flash flood prediction is presented. Time variations of the reflectivity measured by horizontal polarization radar are evaluated and correlated to generate the local estimate of the elevation of the Quitandinha River water level for the next hour. The proposal of this relationship is not intended to act as a simplified hydraulic model but to characterize if a critical elevation of the water level could be obtained from the radar reflectivity data and consequently whether the flash flooding event should be expected. We verified that the proposed relationship that tended to underestimate the water level peaks, however, qualitatively was initially able to indicate if a flood event could occur or not in the next hour. The expectation related to this initial relationship is to improve the obtained results in order to be used as a tool for decision-making in relation to the issuance of warnings delivered by environmental monitoring centers. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG part of Springer Nature.

关键词： Nowcasting Reflectivity River level Weather radar reflectivity

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Fast and Accurate Gpu Nodal Expansion Method

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SSRN 2022年

作者： Mendes, Jadna Mara Santos Heimlich, Adino de Lima, Alan M.M. Silva, Fernando Carvalho Comissão Nacional de Energia Nuclear ZIP 21941 Rua Hélio de Almeida 75 Ilha do Fundão RJ Rio de Janeiro-906 Brazil Universidade Federal do Rio de Janeiro Nuclear Engineering Program Ilha do Fundão POB 68509 RJ Rio de JaneiroZIP 21945-970 Brazil

The neutron flux calculation is fundamental to evaluating the power distribution in nuclear reactor core design. This calculationrequires a high computational effort. This paper presents a new parallel approach to implement a 3D, fourth-order Nodal ExpansionMethod in Graphic Processor Unit, applied to three well known benchmarks to test this approach. The results exhibit speedimprovement exceeding many times over the sequential version. The accuracy in the multiplication factor is less than 2 pcm andthe normalized assembly power density is less than 1%, when compared with the reference for the benchmarks. © 2022, The Authors. All rights reserved.

关键词： Graphics processing unit

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A Multiplier-Less Level-3 Haar Wavelet Transform Approximation Requiring Five Additions Only

A Multiplier-Less Level-3 Haar Wavelet Transform Approximati...

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Proceedings of the IEEE Dallas Circuits and systems Workshop (DCAS)

作者： Morgana M. A. Da Rosa Guilherme Paim Henrique B. Seidel Sé rgio Almeida Eduardo A. C. Da Costa Sergio Bampi Graduate Program on Electronic Engineering and Computing Universidade Cat&#x00F3 lica de Pelotas (UCPel) Brazil Graduate Program in Microelectronics (PGMICRO) Federal University of Rio Grande do Sul (UFRGS) Brazil

ISBN: (数字)9781665498852

ISBN: (纸本)9781665498869

Approximate transform kernels have emerged as an alternative design to reduce the hardware complexity of digital signal processors by exploiting the intrinsic error resilience of many embedded consumer electronics applications such as signal, image and video processing, and computer vision. The approximate level-4 Haar wavelet transform (AxHWT-4) is the state-of-the-art approximate transform for ECG (electrocardiogram) signal processing and reduces more than nine times the energy consumption compared to the exact transform. In this work, we propose an approximate level-3 Haar wavelet transform (AxHWT-3) for increasing the hardware design efficiency with related to the AxHWT-4 while obtaining higher R-peak detection accuracy in the electrocardiogram signal. Our AxHWT-3 approximation is performed in the Haar matrix kernel to eliminate its multiplications which in the hardware design results in savings of energy consumption and VLSI hardware area. Our AxHWT3 proposal achieves an R-peak detection accuracy of more than 99% and reduces the energy consumption by 15.98 times and the VLSI area by 12.64 times compared to the exact solution (i.e., the original level-3 Haar). In addition, the proposed AxHWT3 outperforms the state-of-the-art AxHWT-4 with a savings of about 32% in power dissipation and 19.5% in VLSI area.

关键词： Wavelet transforms Energy consumption Computer architecture Very large scale integration Electrocardiography Signal processing Hardware

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An Image-Based Numerical Homogenization Strategy for the Characterization of Viscoelastic Composites

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SSRN 2022年

作者： Ferreira, Lucas Prata Lopes, Pedro Cortez Fetter Leiderman, Ricardo Aragão, Francisco Thiago Sacramento Pereira, André Maués Brabo Institute of Computing Universidade Federal Fluminense Av. Gal. Milton Tavares de Souza s/n RJ Niteroi24210-346 Brazil Department of Civil Engineering Universidade Federal do Rio de Janeiro Av. Pedro Calmon s/n RJ Rio de Janeiro21941-596 Brazil

An image-based strategy to characterize viscoelastic heterogeneous materials is introduced. The homogenized relaxation moduli are computed directly in the time domain at independent discrete instants by applying a constant strain field to a representative volume element of the heterogeneous material. Periodic boundary conditions are applied to model infinite media. The relaxation master curves are then adjusted via an optimization problem using the generalized Maxwell model represented by the Prony series. The proposed strategy takes as input digital samples depicted by image, in which every voxel corresponds to an element in the Finite Element Method (FEM) formulation, thus dramatically reducing the time-consuming task of meshing the domain. Further, the voxels’ colors are interpreted as material identifiers, so the image itself also serves as a material map. A matrix-free strategy to solve the systems of equations on-the-fly at each iteration is employed to avoid storing the whole stiffness matrix, significantly lowering the memory requirements of the computations. This enables the solution of very large problems with hundreds of millions of degrees of freedom using ordinary personal computers. Two and three-dimensional examples are analyzed to showcase the strategy’s effectiveness and to validate both the formulation as well as the implementation. The results captured well the anisotropic nature of the models and the expected variation in the relaxation behavior given different ratios of elastic to viscoelastic constituents. © 2022, The Authors. All rights reserved.

关键词： Finite element method

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Phenomenological Model of a Reactive Distillation Column Validated at Pilot-Plant Scale to Produce N-Butyl Lactate

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SSRN 2024年

作者： Cesar Augusto, Garcia Echeverry Ochoa, Silvia Gil, Iván Darío Secchi, Argimiro Resende Grupo de Procesos Químicos y Bioquímicos Departamento de Ingeniería Química y Ambiental Universidad Nacional de Colombia Sede Bogotá Cra 30 Num. 45-03 Ed. 453 Of. 318 Cundinamarca Bogotá Colombia SIDCOP Grupo de investigación Universidad de Antioquia Aranjuez Antioquia MedellínCl. 67 53-108 Colombia Chemical Engineering Program LADES—Software Development Laboratory COPPE Universidade Federal do Rio de Janeiro Cidade Universitária Rio de Janeiro Rio de Janeiro21941-914 Brazil

N-butyl lactate is a promising eco-friendly solvent with a high boiling point. However, its production via reactive distillation presents challengessuch as non-linearities and multiple steady states. This work addresses these issues by developing and validating a comprehensive phenomenological model for a pilot-plant scale reactive distillation column, incorporating reaction kinetics and thermodynamic equilibrium. The study examines three cases: 1) Isoamyl acetate production at pilot-plant scale using NRTL-HOC and a pseudo-homogeneous kinetic model with experimental batch data;2) N-butyl lactate production using lab-scale literature data with NRTL, a pseudo-homogeneous kinetic model, and continuous experimental data;3) N-butyl lactate production at pilot-plant scale without experimental data, using NRTL and a pseudo-homogeneous kinetic model. A sensitivity analysis evaluated the model’s robustness, showing that it adequately represents the experimental data on a pilot-plant scale. This research contributes to the development of accurate models for predicting the behavior of processvariables in green solvent production, such as n-butyl lactate, which is crucial for improving industrial-scale process operations. Future research will focus on implementing and evaluating control strategies. © 2024, The Authors. All rights reserved.

关键词： Reaction kinetics

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Structural validation of the “Teacher’s report form” attention problems scale in a Brazilian sample

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Measurement Instruments for the Social Sciences 2021年第1期3卷 1-9页

作者： Pires, Thiago Rocha, Marina Assis, Simone Nobre, Flavio Department of Studies on Violence and Health National School of Public Health (Fiocruz) Rio de Janeiro Brazil Postgraduate Program in Developmental Disorders Universidade Presbiteriana Mackenzie Sao Paulo Brazil Neurology Postgraduate Program University Hospital Gaffrée and Guinle (Unirio) Rio de Janeiro Brazil Biomedical Engineering Program/ COPPE Department Universidade Federal do Rio de Janeiro Rio de Janeiro Brazil

Attention deficit hyperactivity disorder is one of the most common childhood neurodevelopmental syndromes. Although clinical evaluation is considered the gold standard in diagnosing psychiatric disorders, in epidemiological studies, this evaluation is rarely used for practical and financial reasons. Instead, psychometric instruments are used to screen for the disorders. In this case, it is essential to investigate whether these instruments are suitable for measuring the proposed problem. This study aims to verify the structural validation of the Attention Problems Scale of the Teacher’s Report Form (TRF). A random sample of 445 TRF filled out by the teacher of children from São Gonçalo/RJ was selected. The confirmatory factor analysis was applied to validate some factor structures that have been raised in the literature. A second aspect analyzed was the use of structural equation models to verify the validated factorial structure’s relationship with some comorbidities. The bifactor model was the most suitable to explain the TRF child’s Attention Problems Scale’s factor structure. It presented the best-fit quality scores for confirmatory factor analysis than other tested structures. Although it presented good indicators for structural validity, some symptoms could be reassessed to have a more consistent instrument. The bifactor model as an explanatory structure in SEM was able to predict important mental health outcomes. These results are an additional validation to the bifactor model. The results suggest the validity of the TRF’s Attention Problems Scale. The instrument’s factor structure was also appropriate because it corroborated most of the association’s assumptions between subtypes of attention problems and other aspects of mental health. The existence of screening scales adapted to Brazilian Portuguese can substantially impact many children who have difficulty learning. Also, the screening scales can be a useful tool for the health sector to facilitate referra

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Hydrothermal Silicification Along Rift Border Faults in the rio do Peixe Basin, Brazil

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SSRN 2024年

作者： Maciel, Ingrid Barreto Balsamo, Fabrizio Bezerra, Francisco H.R. Nogueira, Francisco Cézar Costa Berio, Luigi Riccardo Brod, José Affonso de Souza, Zorano Sérgio Matos-Pimentel, Hannah Larissa Siqueira Carvalho, Bruno R.B.M. Souza, Jorge André Braz Post-Graduation Program on Geodynamics and Geophysics Universidade Federal do Rio Grande do Norte RN Natal59078-970 Brazil Department of Chemistry Life Sciences and Environmental Sustainability University of Parma ParmaI-43124 Italy Department of Petroleum Engineering Federal University of Campina Grande PB Campina Grande58100-000 Brazil Federal University of Goiás GO Goiânia74690-970 Brazil Petrobras Research Center—CENPES RJ Rio de Janeiro21941-915 Brazil

This study investigates hydrothermal silicification along rift border faults in the Cretaceous rio do Peixe Basin, Brazil, using field geology, petrography, mineralogy, microtexture, and fluid inclusion microthermometry. We distinguish three main diagenetic domains: (1) a non-silicified damage zone, (2) a silicified damage zone composed of deformation bands and centimeter-scale quartz veins in the hanging wall and footwall, respectively, and (3) a silicified fault core with meter-scale wide quartz veins and mosaic breccia textures. We recognize three main events of deformation and silicification in the fault zone. The first silicification event occurs after the widespread development of deformation bands in the hanging wall damage zone that may reach 200 m in width. During subsequent deformation events, multiple fracturing episodes were accompanied with precipitation of the second quartz generation in hydraulic mosaic breccias and the third quartz cement in vein stockworks. Shallow burial conditions of faulting ( © 2024, The Authors. All rights reserved.

关键词： Quartz

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DSM design of Cold-Formed Steel Columns Failing in Flexural-Torsional Modes at Elevated Temperatures

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ce/papers 2021年第2-4期4卷 1272-1281页

作者： Bicelli, Antonio Landesmann, Alexandre Camotim, Dinar Dinis, Pedro Civil Engineering Program COPPEE Universidade Federal do Rio de Janeiro Rio de Janeiro Brazil CERIS ICIST DECivil Instituto Superior Técnico Universidade de Lisboa Portugal

The purpose of this work is to extend the scope of the previous studies, by considering fixed-ended columns under elevated temperatures (up to 800° C) with three cross-section shapes (lipped channels, racks and stiffened lipped channels), various cross-section dimensions (five per shape) and different lengths. The results presented and discussed consist of column FT post-buckling equilibrium paths and failure loads, which are obtained through geometrically and materially non-linear Ansys SFEA. In order to cover a wide FT slenderness range, several room-temperature yield stresses are considered. The model prescribed in EC3-1.2, for cold-formed steel, is adopted to describe the temperature-dependence of the steel material properties. Finally, the numerical failure loads obtained by the authors, together with numerical and experimental ones collected from the literature are used to propose a modification of the DSM-based FT strength curves developed previously by authors and assess the merits of the new design curves. It is shown that the proposed modification improves visibly the failure load prediction quality, thus providing encouragement to continue the search for an efficient and reliable DSM-based design approach for columns failing in FT modes at elevated temperatures. © 2021 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

关键词： Numerical methods

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Hydration kinetics of Portland cement pastes blended with C-S-H seeds and low initial reactivity supplementary cementitious materials

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Materials Today: Proceedings 2023年

作者： Guilherme Durigon Cocco Amanda Pereira Vieira Eduardo de Moraes Rego Fairbairn Oscar Aurelio Mendoza Reales Civil Engineering Program – COPPE Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941909 Brazil

Extensive research has focused on using supplementary cementitious materials (SCM) as substitutes for Portland cement to reduce the carbon footprint of composites. The combination of clinker dilution and low initial reactivity of certain SCM results in slower hydration kinetics and reduced formation of hydrated minerals during early hydration stages. However, the introduction of calcium silicate hydrate (C-S-H) seeds has been found to accelerate the precipitation of C-S-H, acting as additional nucleation sites and leading to composites with enhanced early-age strength . This study aimed to evaluate the potential of C-S-H seeds in compensating for the hydration kinetics delays caused by high levels of cement substitution with low-reactivity SCM. Three replacement levels of Portland cement (10%, 20%, and 30% by weight) by metakaolin and rice husk ash were examined, both with and without the addition of C-S-H seeds, in pastes with a water/binder ratio of 0.5. Inert #325 silica was used as a reference material. Isothermal calorimetry and ultrasonic pulse velocity tests were conducted over the initial three days of hydration to assess the effects of C-S-H seeds and SCM substitution on the hydration kinetics of the reference Portland cement paste . The results demonstrated that while SCM induced a delay in the hydration reaction , the addition of 3% C-S-H seeds effectively reduced the final time and duration of the induction period for all mixtures, irrespective of the SCM type or replacement level. Moreover, the presence of the nano-additive promoted higher heat release during the induction period and shortened the time to reach maximum heat release. Furthermore, C-S-H seeds increased the cumulative heat of the mixtures, with a more pronounced impact in the early stages of hydration. In conclusion, the utilization of C-S-H seeds shows promising potential in compensating for the issues arising from the hydration kinetics of low-reactivity SCM.

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Evaluation of adhesion of epoxy resin sealant to improve the corrosion resistance of thermal sprayed coatings

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Applied Adhesion Science 2020年第1期8卷 1-14页

作者： Carneiro, Mateus R. D. Freitas, Bruno C. de Barros, Iuri B. de Campos, José B. Bastos, Ivan N. Costa, Hector R. M. Graduate Program in Mechanical Engineering and Materials Technology Centro Federal de Educação Tecnológica Celso Suckow da Fonseca Av. Maracanã 229 Rio de Janeiro 20.271-110 RJ Brazil Instituto Politécnico Universidade do Estado do Rio de Janeiro Rua Bonfim 25 Nova Friburgo Rio de Janeiro 28.625-570 RJ Brazil Departamento de Engenharia Mecânica Universidade do Estado do Rio de Janeiro Rua Fonseca Teles 121 São Cristóvão Rio de Janeiro 20.940-903 RJ Brazil

The adhesion of coatings on a given substrate has fundamental importance on a coating/substrate system's functionality. The current paper presents the adhesion strength results of FeCr and CoCr-based deposits produced by the electric arc thermal spray process on carbon steel, with an intermediate layer of 95Ni5Al. Three chemical compositions were tested for coating deposition and were characterized using plate and tube specimens made of carbon steel UNS G10200 to result in a screening of performance. Microstructural evaluation by optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) were performed. Coating strength was measured using the standard pull-off test method. The corrosion resistance was analyzed with salt spray exposure, electrochemical polarization, and impedance spectroscopy (EIS) tests. The adhesion strength of FeCr and CoCr alloy coatings shows an overall average tensile strength of 27.2 MPa. All sealed conditions presented low corrosion and the samples with epoxy sealant exhibited a high resistance against corrosion. The X-ray diffraction results have revealed alpha and gamma FeCr alloys and chromite as deposited phases after the coating process. © 2020, The Author(s).

关键词： Adhesion test CoCr coatings FeCr Salt spray test Sealants Thermal spray

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