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IEEE General Meeting Power& Energy Society

作者： Lindemberg Roberto de Lima Pedro A. de Alcântara Luana C. S. Soares Camila M. V. Barros Luciano S. Barros Mathematics and Computational Modeling Graduate Program João Pessoa Brazil Electrical Engineering Graduate Program Federal University of Paraíba João Pessoa Brazil Computer Systems Department Federal University of Paraíba João Pessoa Brazil

In this paper, considering photovoltaic/battery sourced microgrids with grid-forming droop control in the load interface converter for power management, two alternative converter topologies for the battery are tested: dual boost interleaved converter and three-phase interleaved converter. These topologies are based on the conventional bidirectional buckboost converter and their employment is to allow a reduction in component sizing, improvement in power quality, and higher output voltage. Analysis of the operation of these converters in different operation modes of the microgrid is carried out, including battery normal charging, battery normal discharging, battery charging limit, and maximum state-of-charge, through simulations in MATLAB/Simulink environment. Results suggest advantages such as reduced stress on switches and battery charging current ripple for the two interleaved converters tested and the potential implementation of higher output voltage for the dual boost converter.

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computational Analysis of Anastomotic Angles by Blood Flow Conditions in Side-to-End Radio-Cephalic Fistulae Used in Hemodialysis

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Journal of Biomedical Science and Engineering 2015年第3期8卷 131-141页

作者： Janaína de Andrade Silva José Karam-Filho Carlos Cristiano H. Borges Graduate Program of Computational Modeling Federal University of Juiz de Fora Juiz de Fora Brazil CMC/National Laboratory for Scientific Computing Petrópolis Brazil PPGMC/Federal University of Juiz de Fora Juiz de Fora Brazil

Chronic renal failure is a disease that affects a considerable population percentage that requires the hemodialysis procedure which is a blood filtration. This process is extremely stressful in many cases for the patient, because there is a continuous degradation of vessels and fistulae susceptible to this process due to the alterations of the stress at the blood vessel walls and flow patterns, leading to diseases such as intimal hyperplasia and consequent stenosis. Experimental in vivo researches in this area are very difficult to perform. In this sense computational models become interesting non invasive options to understand what happens to the blood in non viscometric geometries. In this work, we analyse blood flow, through computational modeling, in arteriovenous fistulae used in hemodialysis, using geometries with dimensions close to real ones. Discretization of the governing equations was made through a finite volume technique with the PISO—Pressure Implicit with Splitting of Operators—algorithm, using as a basis the OpenFOAM software platform. Large vessel Newtonian fluid model was used to analyze six possible anastomotic angles (20。, 25。, 30。, 35。, 40。, 45。). To analyze the possibility of stenosis formation caused by hyperplasia, results for wall shear stress, oscillatory shear index (OSI), velocity and local circulation fields were obtained, showing that higher angles presented more secondary flows and larger extensions of stagnation regions near the critical areas of the junctions. Moreover, a range around 25。was identified to be the most suitable choice for clinical applications, minimizing possibility of diseases.

关键词： Hemodialysis Wall Shear Stress Stagnation Flow Finite Volume Method Blood Flow Large Vessels

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Comparative Analysis between Three-Leg Interleaved and Conventional Bidirectional Converters Applied in Battery of Wind Power-Battery Unit Supplying an Islanded Microgrid

Comparative Analysis between Three-Leg Interleaved and Conve...

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IEEE General Meeting Power& Energy Society

作者： André C. Do Nascimento Giusep M. S. Ribeiro Lindemberg R. de Lima Pedro A. de Alcântara Luana C. S. Soares Luciano S. Barros Camila M. V. Barros Electrical Engineering Graduate Program Federal Institute of Pará Belém Brazil Electrical Engineering Graduate Program Federal University of Paraíba João Pessoa Brazil Mathematics and Computational Modeling Graduate Program Federal University of Paraíba João Pessoa Brazil Computer Systems Department Federal University of Paraíba João Pessoa Brazil

ISBN: (数字)9798350381832

ISBN: (纸本)9798350381849

Battery energy storage systems (BESS) are crucial for microgrids, enhancing dynamic performance and mitigating uncertainties inherent to isolated environments characterized by intermittent power generation. When microgrid is supplied by wind power in connection with BESS, the bidirectional DC-DC converter associated with BESS assumes a critical responsibility—ensuring the control of a wind power supplied DC-link. This permits the Voltage Source Inverter (VSI) to synthesize consistent voltages for the connected AC load. However, challenges emerge, particularly in arduous stress on switches of the bidirectional converter attributed to elevated current ripple. This stress does not only prejudice the overall system’s functioning but can also potentially leading it to shutdown in case of switch failure. Traditionally, the conventional buck-boost converter topology has been the go-to choice for this application, nevertheless, exploring novel converter topologies, such as interleaved bidirectional DC-DC converter (IBDC) has garnered attention, promising enhanced performance. This paper’s goal is to conduct a comparative analysis of the operation of these converters in an islanded microgrid supplied by a single Permanent Magnet Synchronous Generators (PMSG) small-scale wind turbine with a BESS system. Load variation with Maximum Power Point Tracking (MPPT) operation of the PMSG is performed during MATLAB/Simulink environment simulations. The results suggest significant advantages for the interleaved three-phase converter, such as reduced battery charging current ripple, switch disturbance, and voltage ripple in the DC-link.

关键词： Maximum power point trackers Magnetic separation Microgrids DC-DC power converters Wind power generation Permanent magnets Batteries Topology Wind turbines Stress

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School dropout in the Federal Network Education of Brazil: is it an inherent individual attribute or it lies on setting conditions?

School dropout in the Federal Network Education of Brazil: i...

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International Symposium on Computers in Education (SIIE)

作者： Jabson Cavalcante Dias Tadeu Lucena Da Silva Marco Antônio Juliatto Adriano Nascimento Da Paixão David Nadler Prata Federal University of Tocantins Palmas TO Brazil Statistic Department Federal University of Paraíba Paraíba PB Brazil Institute of Regional Development Graduate Program of Computational Modeling Federal University of Tocantins Palmas TO Brazil

Studies shown that school dropout among young people in Brazil corresponds to 3% of the annual GDP and is equivalent to all state and municipal spending on basic education per year. The expectation is that, each year, the country has approximately 575,000 young people without basic education due to school dropout. Many aspects can lead to greater or lesser school dropouts. An important issue that can help to understand this school phenomenon is to disentangle which attributes are inherent to the individual and which are attributed to the setting, so that public policies could be developed in favor of reducing schools’ dropouts. In this work, logistic regression methods were applied to the 2019 Nilo Peçanha Platform databases (approximately 250 thousand records). Results shown that demographic, geographic, economic, and school setting variables can be measured to understand their impacts in projecting schools’ dropouts, enabling the elaboration and carrying out of preventive and corrective actions in schools.

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A Finite Element Approach for modeling Micro-structural Discontinuities in the Heart

A Finite Element Approach for Modeling Micro-structural Disc...

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Annual International Conference of the IEEE Engineering in Medicine and Biology Society

作者： Caroline Mendonca Costa Fernando O. Campos Anton J. Prassl Rodrigo Weber dos Santos Damian Sanchez-Quintana Ernst Hofer Gernot Plank Graduate Program on Computational Modeling Universidade Federal de Juiz de Fora Institute of Biophysics Medical University of Graz Departamento de Anatomia Biologia Celular y Zoologia Universidad de Extremadura Avenida de la Universidad

ISBN: (纸本)9781424441211

The presence of connective tissue as well as interstitial clefts forms a natural barrier to the electrical propagation in the heart. At a microscopic scale, such uncoupling structures change the pattern of the electrical conduction from uniform towards complex and may play a role in the genesis of cardiac arrhythmias. The anatomical diversity of conduction structures and their topology at a microscopic size scale is overwhelming for experimental techniques. Mathematical models have been often employed to study the behavior of the electrical propagation at a sub-cellular level. However, very fine and computationally expensive meshes are required to capture all microscopic details found in the cardiac tissue. In this work, we present a numerical technique based on the finite element method which allows to reproduce the effects of microscopic conduction barriers caused by the presence of uncoupling structures without actually resolving these structures in a high resolution mesh, thereby reducing the computational costs significantly.

关键词： Heart Finite element method Numerical methods heart tissues Electrical conduction discontinuities genesis Connective Tissue topology NATURAL BARRIERS

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A simulator for underwater unmanned vehicles and cable-like flexible structures

A simulator for underwater unmanned vehicles and cable-like ...

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OCEANS

作者： Marcos Vinicius Scholl Sebastião C. P. Gomes Carlos Rodrigues Rocha Graduate Program in Computational Modeling Federal University of Rio Grande - FURG Rio Grande-RS Brazil Federal Institute of Education Science and Technology of Rio Grande do Sul Rio Grande Campus Rio Grande-RS Brazil

A graphical tool to qualitative analysis of underwater unmanned vehicles and cable-like flexible structures is presented. The software provides a realistic virtual environment where the dynamic behavior of different u... 详细信息

ISBN: (纸本)9781509064298;9780692946909

关键词： Vehicle dynamics Underwater cables Dynamics Mathematical model Software Unmanned vehicles Numerical simulation

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An information theoretic framework for eukaryotic gradient sensing 06

An information theoretic framework for eukaryotic gradient s...

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Proceedings of the 20th International Conference on Neural Information Processing Systems

作者： Joseph M. Kimmel Richard M. Salter Peter J. Thomas Computer Science Program Oberlin College Oberlin Ohio and Computational Neuroscience Graduate Program The University of Chicago Computer Science Program Oberlin College Oberlin Ohio and Oberlin Center for Computation and Modeling Departments of Mathematics Biology and Cognitive Science Case Western Reserve University Cleveland Ohio and Oberlin College Research Associate

Chemical reaction networks by which individual cells gather and process information about their chemical environments have been dubbed "signal transduction" networks. Despite this suggestive terminology, there have been few attempts to analyze chemical signaling systems with the quantitative tools of information theory. Gradient sensing in the social amoeba Dictyostelium discoideum is a well characterized signal transduction system in which a cell estimates the direction of a source of diffusing chemoattractant molecules based on the spatiotemporal sequence of ligand-receptor binding events at the cell membrane. Using Monte Carlo techniques (MCell) we construct a simulation in which a collection of individual ligand particles undergoing Brownian diffusion in a three-dimensional volume interact with receptors on the surface of a static amoeboid cell. Adapting a method for estimation of spike train entropies described by Victor (originally due to Kozachenko and Leonenko), we estimate lower bounds on the mutual information between the transmitted signal (direction of ligand source) and the received signal (spatiotemporal pattern of receptor binding/unbinding events). Hence we provide a quantitative framework for addressing the question: how much could the cell know, and when could it know it? We show that the time course of the mutual information between the cell's surface receptors and the (unknown) gradient direction is consistent with experimentally measured cellular response times. We find that the acquisition of directional information depends strongly on the time constant at which the intracellular response is filtered.

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A Population Size Dynamic Reduction Criterion in PSO Algorithms

A Population Size Dynamic Reduction Criterion in PSO Algorit...

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Congress on Evolutionary Computation

作者： Samuel C.A. Basílio Afonso C. C. Lemonge Érica C.R. Carvalho Federal Center for Technological Education of Minas Gerais Leopoldina Brazil Federal University of Juiz de Fora Juiz de Fora Brazil Graduate Program of Computational Modeling Federal University of Juiz de Fora Juiz de Fora Brazil

The size of the population is extremely important when executing a population-based algorithm. Its portioning impacts how much the algorithm will have for exploration and exploitation. An excessively large population can benefit exploration as opposed to exploitation. With a population below ideal, exploration may be impaired, and the algorithm may quickly converge to a local optimum. Unfortunately, the choice of population size is often made empirically, where the user experiences different values, several times, for different problems, without any well-defined criteria, often drawing only on his experience. This type of approach can under-use the algorithm, generating waste in both computational cost and results. In this work, we improve and study an approximation metamodel as a particle reduction criterion for particle swarm algorithms. This metamodel considers that if two particles are relatively close and with similar velocitys, they will tend to the same solution, allowing one of these to be eliminated. Five traditional benchmark problems in the literature in the field of engineering applications were performed and the results analyzed.

关键词： Heuristic algorithms Sociology Benchmark testing Approximation algorithms computational efficiency Statistics Particle swarm optimization

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SARS-CoV-2 surveillance of wastewater in small rural communities identifies lack of vaccine coverage as influence of omicron outbreak

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Water Research 2025年 283卷 123818页

作者： Solana Narum Thibault Stalder Benjamin Ridenhour Erik R. Coats Bioinformatics and Computational Biology Graduate Program (BCB) University of Idaho 875 Perimeter Drive MS 1103 Moscow ID 83844 United States Institute for Modeling Collaboration and Innovation (IMCI) University of Idaho 875 Perimeter Drive MS 1122 Moscow ID 83844 United States Department of Biological Sciences University of Idaho 875 Perimeter Drive MS 3051 Moscow ID 83844 United States Institute for Interdisciplinary Data Sciences (IIDS) University of Idaho 875 Perimeter Drive MS 3051 Moscow ID 83844 United States Department of Mathematics and Statistical Science University of Idaho 875 Perimeter Drive MS 1103 Moscow ID 83844 United States Department of Civil and Environmental Engineering University of Idaho 875 Perimeter Drive MS 1022 Moscow ID 83844 United States

Wastewater-based epidemiology (WBE) can provide critical early warnings to aid public health, which can be particularly beneficial in rural communities with limited access to health care. Spikes of SARS-CoV-2 RNA concentration in wastewater have been used to represent infections in a community, but wastewater holds a wealth of information that has not been explored yet. The objectives of this research were to expand the use of WBE to 1) determine the dynamic of SARS-CoV-2 variants in rural communities, and 2) evaluate the relationship between community vaccination status and the outbreak of a variant. We quantified the concentration of SARS-CoV-2 RNA, as well as specific mutations that are consistent with Delta and Omicron in influent raw wastewater samples collected from wastewater treatment facilities (WWTFs) for five populations with <1000 residents and one larger population in Latah County, ID. A binomial generalized linear model using the percent of the population with protection against Omicron from the initial vaccines and the booster shot was able to predict the probability of an uptick in Omicron concentration in wastewater with an accuracy of 0.96. Evaluation of vaccination data indicate that the spike in Omicron infections in December 2021 in the studied towns was linked to low levels of population protection from the initial shots of the COVID-19 vaccine against Omicron infection and limited uptake of booster shots in these communities. Despite difficulties with applying WBE in rural regions, this study shows that beyond evaluating spikes of viral infections, WBE can be used to evaluate the effect of a population’s vaccine coverage on SARS-CoV-2 variant dynamics.

关键词： COVID-19 Delta modeling Omicron Population coverage Prediction

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Geometric Optimization of a Rectangular Heated Block Inside a Lid-Driven Cavity Under Mixed Convection Heat Transfer: A Perspective Motivated by Bejan’s Theory

SSRN

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SSRN 2022年

作者： da Silveira Borahel, Rafael Franceschini Zinani, Flávia Schwarz Oliveira Rocha, Luiz Alberto dos Santos, Elizaldo Domingues André Isoldi, Liércio Biserni, Cesare Mechanical Engineering Graduate Program Universidade do Vale do Rio dos Sinos São Leopoldo93022-750 Brazil Mechanical Engineering Graduate Program Universidade Federal do Rio Grande do Sul Porto Alegre90040-001 Brazil Computational Modeling Graduate Program Universidade Federal do Rio Grande Rio Grande96203-900 Brazil Graduate Program of Ocean Engineering School of Engineering Federal University of Rio Grande –FURG Italia Avenue km 8 Rio Grande96201-900 Brazil Alma Mater Studiorum - University of Bologna Viale Risorgimento 2 Bologna40136 Italy

The present work applies the Constructal Design method to analyze the performance of a rectangular heated block inside a lid-driven cavity submitted to mixed convection heat transfer with unstable stratification. The effect of HB configuration on heat transfer performance is investigated via numerical simulation of heat and flow dynamics. Such phenomena are analyzed to understand how geometric evolution improves system performance. The modeling for numerical simulations involves steady, laminar, and incompressible flow in a two-dimensional domain. Equations of mass, momentum, and energy balance are solved using numerical simulations based on the finite volume method. The main purpose of employing the Constructal Design method is to maximize the dimensionless heat transfer rate ( q *) between the HB and the surrounding fluid. The constraint is the HB/cavity area fraction (1/4, 1/8, 1/16, and 1/32), while the HB aspect ratio and its horizontal position are the degrees of freedom (DOF). The behavior of the system is investigated for different operational conditions given by the Richardson Number ( Ri = 0.1, 1.0, and 10), for fixed Grashof and Prandtl ( Pr = 0.71) numbers. Considering all possible combinations of the analyzed parameters, 162 different geometric configurations were tested (54 for each Ri ). © 2022, The Authors. All rights reserved.

关键词： Incompressible flow

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