Ciência e Natura

XXV ENMC / XIII ECTM / 9º MCSul / IX SEMENGO

Daniela Buske — Fri, 01 Dec 2023 00:00:00 -0300

In 2022, the events XXV National Meeting of Computational Modeling (XXV ENMC) and XIII Meeting of Science and Technology of Materials (XIII ECTM) took place from October 19 to 21, 2022, with all activities of the event carried out in the webinar modality. In this particular year, together with the XXV ENMC and the XIII ECTM, the 9th Southern Conference on Computational Modeling (9th MCSul) and the IX Seminar and Workshop on Ocean Engineering (IX SEMENGO) were held, providing the opportunity to bring together researchers from related areas of knowledge.

The events included lectures from the area of Computational Modeling in Brazil and abroad; its organization was the result of a collaboration between professors from ten public teaching institutions in the country, under the coordination of researchers from universities in Rio Grande do Sul; the event had more than 250 manuscripts submitted and presented in 57 technical sessions, with emphasis on the contributions of graduate students.

The Organizing Committee selected a sample of original works presented at the event with an interdisciplinary theme. This led to the publication, in August 2023, of this special edition of the XXV ENMC / XIII ECTM / 9º MCSul / IX SEMENGO. We thank the authors who contributed to the high level of this edition.

We wish you all a pleasant reading.

Immunological memory improves the long-term cross-immunity: An influenza case study

Adriano De Cezaro, Ana Carla Ferreira Nicola Gomes, Joice Chaves Marques — Fri, 01 Dec 2023 00:00:00 -0300

In this contribution, we investigate the effects of the immunological memory in the population against the strain mutation of a disease, assuming that this memory is enhanced by the dynamics that follow a multi-order fractional SIRC model. We use weekly infection data on Influenza H1N1 in the state of Rio Grande do Sul, reported in the year of 2010, as the guide for our simulations and parameter choices. The simulated results suggest that the best scenarios, regarding the Influenza H1N1 data fit and that have a long-term prevention of reinfection for mutated strains of a circulating disease is the one in which the compartment of the population has a distinct level of immunological memory. Hence, any immunization strategy should be applied as early as possible, allowing the individual to acquire immunological memory before the strain can undergo mutations.

Computational model validation of the rolled shapes calendering process

Fri, 01 Dec 2023 00:00:00 -0300

This paper presents the validation of computational model for the numerical simulating of the 3-roll calendering process. For this, a case study was carried out, considering a rolled I-form S235 steel profile subjected to vertical loads imposed by the calender rolls. Residual stress results obtained numerically were compared with experimental results found in the literature. The computational model was developed in ANSYS® software, which relies on the Finite Element Method (FEM), considering four different types of three-dimensional finite elements: SOLID185, SOLID186, SOLID187, and SOLID285. The results indicated that the computational model with SOLID186 presented stable mesh convergence, obtaining a discrepancy of -1.61% when compared to the experimental results, thus validating the proposed computational model.

Analysis of EAHE through a coupled mathematical model solved by Laplace transform and Gaver-Stehfest algorithm

Fri, 01 Dec 2023 00:00:00 -0300

The earth-air heat exchangers (EAHEs) are devices that are shown to be a great alternative to assist in the thermal comfort of buildings, mainly due to their low energy cost. The proposed model considers the heat exchange between the soil, the duct and the air, generating coupled equations. This work seeks to employ and verify EAHE applications in two scenarios, first in a literature experiment and then in a EAHE application in Pelotas. In both scenarios, it is considered that the soil and air temperature functions are time dependent. The solution is obtained by applying the Laplace transform and for the inversion of the integral transform the numerical method known as the Gaver-Stehfest Algorithm was used. The obtained results show that the proposed model follows the behavior of the experimental data. In addition to the experimental data, the proposed model was compared with the analytical model by Nóbrega, where the results had a small variation (of 0.20 ºC between them) by considering the heat transfer process in the duct material, modeling a more close to the real situation.

Numerical humidity assessment: analysis of the thermal performance of a residential building

Fri, 01 Dec 2023 00:00:00 -0300

The earth-air heat exchanger (EAHE) is a device where the external ambient air is blown to use the ground as a heat source, through buried ducts with the aid of low power fans, thus powering the energy consumed in the building. The air at the outlet of the ducts is heated in winter and cooled in summer, providing thermal comfort conditions for indoor environments. The goal of the extensive search in recent decades has been to find solutions that can improve a building’s thermal comfort in order to provide recommendations for the design of various devices utilized in the utilization of renewable energy sources. This work aims to evaluate the results found for humidity and air temperature in a building. The objective was to create a computational model that depicts practical operating circumstances for a building’s ground-to-ground heat exchangers. These evaluations were carried out by numerical simulation with the EnergyPlus software, for which a meteorological file was created. To examine the building’s behavior in various climates, the data are shown for two typical project days: one in the summer and one in the winter.

Numerical evaluation of the earth-air heat exchanger thermal performance in a social housing in brazilian bioclimate zones ZB 3 and ZB 4

Fri, 01 Dec 2023 00:00:00 -0300

The Earth-Air Heat Exchanger (EAHE) is a device where the external ambient air is cooled or heated when circulating inside ducts buried in the soil, which can bring benefits in the sense of reducing energy consumption and providing thermal comfort conditions. This system has been employed in several countries and different climatic contexts, however, little explored in Brazil. The use of this technology in conjunction with bioclimatic strategies favors buildings, increasing their efficiency. This study aims to evaluate the thermal performance of an EAHE together with optimization parameters of the building envelope, in two Brazilian bioclimatic zones and to propose strategies that enhance energy efficiency in buildings. The study consists of the validation and verification of a computational model and in the thermal evaluations of a Social Housing (SH), in which characteristics of solar orientation, thermal envelope, and the installation of an EAHE will be modified, combined, and investigated in proposed models. These evaluations were carried out through dynamic simulation with the EnergyPlus™ software. The results showed that the installation of an EAHE in SH brings improvements in the thermal performance of environments, thus contributing that future projects can rely on validated references and parameters.

Application of constructal theory for the construction of an arrangement of heated blocks inserted in a channel subject to flows with forced convection

Fri, 01 Dec 2023 00:00:00 -0300

This work shows an analysis of the construction of the geometric arrangement of blocks mounted on the surfaces of a channel subject to a laminar, incompressible flow, with forced convection in a two-dimensional domain. The construction is carried out through a construction function based on the system performance indicator, i.e., the heat transfer rate from the arrangement to the fluid flow. For the assembly of the arrangement, a methodology based on the principles of the Constructal Theory is used. To solve the convection problem, the mass, momentum and energy conservation equations are solved with the Finite Volume Method, more precisely using the FLUENT software. The objective of this work is to understand how the construction of the initial blocks of the array (N = 3 blocks) occurs in an area occupied by the channel in flows with forced convection and Reynolds and Prandtl numbers of Re_H = 100 and Pr = 0.71. The best and worst cases for N = 2 led to an increase of 93.21% and 28.59%, respectively, compared to the N = 1 case. Results demonstrated that the construction that led to the best thermal performance was the configuration where there is the highest momentum between blocks (intensifying the convective heat transfer coefficient) and with the lowest interaction between the thermal boundary layers, which is in agreement with the principle of optimal distribution of imperfections.

Conductional heat transfer in magmatic intrusions

Fri, 01 Dec 2023 00:00:00 -0300

The thermal effect that occurs due to the insertion of igneous intrusions in sedimentary basins has been widely investigated in different geological contexts, either to obtain more precise information about the development of the basin and or for the purpose of exploring and evaluating the mineral resources existing there. We can verify that the knowledge of the thermal gradient is fundamental in studies of heat distribution through means such as the Earth's crust or mantle, as this way, we obtain the thermal evolution of magmatic intrusions and adjacent rocks over geological time. For the present work, the determination of the temperature gradient and consequently the thermal evolution of a 13-meter-thick sill and adjacent rocks located in the Paraná Basin - Irati Formation, was obtained through the use of the one-dimensional heat dispersion model in transient regime of finite time, in which, in the spatial variable the numerical method of finite differences (FDM) is used and in the temporal variable the Euler method. Although in cases of large and thick magmatic bodies or sections that include the terrestrial lithospheric and asthenospheric mantles, the mechanism of convection and radiation has an expressive role in the energy transfer process. However, in most geological situations, conduction is the most important mechanism in the heat distribution process.

Retaining of dredging waste using geotextile tubes: analysis of the dewatering and undrained shear resistance of the sludge cake

Fri, 01 Dec 2023 00:00:00 -0300

The city of Rio Grande has its economy linked to coastal and port activities and has a port complex of high economic importance for the region. To maintain the depth of the port channels, periodic dredging operations are carried out, as occurred in the Port of Rio Grande between 2018 and 2020. Approximately 16 million m³ of sediments were removed from the channel and deposited in disposal zones. There has been an attempt to develop techniques that carry out the reuse and disposal of dredging waste more appropriately, seeking to minimize environmental impacts by avoiding inappropriate open-sea or onshore disposal. Within this context, this work aims to evaluate the potential of the retaining and dewatering process of dredging waste in geotextile tubs (linear geoforms, geobags e etc). This technique reduces the volume of dredged mud through desiccation and allows the geotextile tubs to be installed in sedimentation basins onshore or coastal protection structures. Thus, the present study evaluated the dewatering and filtration efficiency of these systems through tests of small bags. The advantages of adding flocculation polymer and the behavior of undrained shear strength over time of the retained cake were evaluated.

Selection of models and parameter estimation for monitoring the COVID-19 epidemic in Brazil via Bayesian inference

Fri, 01 Dec 2023 00:00:00 -0300

In 2019, a new strain of coronavirus led to an outbreak of disease cases named COVID-19, evolving rapidly into a pandemic. In Brazil, delayed decision making and lack of knowledge have resulted in an alarming increase in daily transmission and deaths. In this context, researchers used mathematical models to assist in determining the parameters that act in the spread of diseases, revealing containment measures. However, numerous mathematical models exist in the literature, each with specific parameters to be specified, leading to an important question about which model best represents the pandemic behavior. In this regard, this work aims to apply the Approximate Bayesian Computation method to select the best model and simultaneously estimate the parameters to resolve the abovementioned issue. The models adopted were susceptible-infected-recovered (SIR), susceptible-exposed-infected-recovered (SEIR), susceptible-infected-recovered-susceptible (SIRS), and susceptible-exposed-infected-recovered-susceptible (SEIRS). Approximate Bayesian Computation Monte Carlo Sequencing (ABC-SMC) was used to select among four competing models to represent the number of infected individuals and to estimate the model parameters based on three periods of Brazil COVID-19 data. A forecasting test was performed to test the ABC-SMC algorithm and the selected models for two months. The result was compared with the actual number of infected that were reported. Among the teste models, it was found that the ABC-SMC algorithm had a promising performance, since the data were noisy and the models could not predict all parameters.

Comparative analysis of deterministic and reliability-based structural optimization methods

Carla Simone Albuquerque, Mauro de Vasconcelos Real — Fri, 01 Dec 2023 00:00:00 -0300

Optimization is the act of obtaining the best possible result under established conditions. Usually, the optimization of a structural design is done considering the structure's dimensions, the materials' properties, and the loads as deterministic values. This way, the optimization process can lead to a more economical design without guaranteeing that this structure is safe. In practice, there are always uncertainties about the final dimensions of the built structure, material properties, and loads. Then, the need arises to use design optimization techniques based on reliability to guarantee a project that is both economical and safe. This objective is achieved by including uncertainties in the optimization process. This article evaluates the parameters that determine the global minimum of the optimization methods DDO (Deterministic Design Optimization) and RBDO (Reliability-Based Design Optimization). This work aims to compare the structural optimization methods of DDO and RBDO through an example. The results are obtained through the codes of the methods implemented in the Python language and show that when comparing the two optimization methods, the presence of uncertainties alters the optimal solution.

Evaluation of chloride deposition using the wet candle method: a study in the city of Cabo Frio, RJ

Fri, 01 Dec 2023 00:00:00 -0300

In a context of durability design of reinforced concrete structures, it is necessary to establish the divisions of the aggressiveness classes of the different maritime and coastal environments, in order to contribute to the study of the classification of environmental aggressiveness. In this paper, the deposition of aggressive ions
and the general climatic aspects of the coastal region of the city of Cabo Frio, RJ are evaluated. For the analysis, the wet candle method (Brazilian NBR 6211:2001) was adopted. The exhibitions were held at five different points throughout the city, each with three wet candles. To quantify the chloride content, the conductimetry method was used, which is done by measuring the electrical conductivity of an electrolyte solution, due to
ion migration. The results point to a high level of chlorides in the initial range of distance from the sea and a considerable decrease from approximately 900 meters from the seashore. In this way, it was possible to verify that the city, in its interior, is under moderate to minimal aggressiveness. In the initial distances of the
seashore, there is high aggressiveness. These results show the importance of considering micro exposure environments during the design phase of reinforced concrete structures.

Analysis of the calibration and validation of hydrodynamic simulations with TELEMAC-3D model of the Patos Lagoon

Fri, 01 Dec 2023 00:00:00 -0300

This work presents the analysis of the calibration and validation of the computational model for two configurations of the Jetties of the Rio Grande Barra for hydrodynamic studies of the Patos Lagoon and the continental shelf of southern Brazil. The model used was TELEMAC-3D, which solves the three-dimensional Navier-Stokes equations, considering the hydrostatic hypothesis, to describe the dynamics of free surface geophysical fluids. We developed two finite element triangular meshes, with about 75.000 elements and seven sigma levels. The numerical domain reaches depths up to 2.427 m, with fluvial and oceanic liquid boundaries. The horizontal turbulence model adopted was Smagorinsky and the vertical model of mixing length. Current velocity data obtained from December 2005 were used for calibration, varying the coefficient of wind friction, horizontal and vertical velocity diffusion, and the salinity tracer. The coefficient of wind influence was the factor that most influenced the model results. The calculated Relative Mean Absolute Error was 0.383 dn. for surface and 0.167 dn. for depth, rated good and excellent, respectively. For validation, we evaluated the model performance on reproducing the salinity behavior, related to the depth of the environment, in January 2017. The calculated Root Mean Square Error was 7.37 dn. and the Relative Mean Absolute Error was 0.228 dn., rating the model performance as good. These variances between metrics is uniformly acceptable for real models. Salt transport is a complex phenomenon and depends on both advective and diffusive transport. Thus, it is possible to conclude that he proposed computational model is able to reproduce a complex phenomenon reliably.

Fractional calculus applied to the Cournot-type adjustment model

Adriano De Cezaro, Matheus Madeira Correa — Fri, 01 Dec 2023 00:00:00 -0300

In this contribution, we propose the incorporation of memory in a Cournot-type model for the process of adjusting the production of firms in a duopoly market, through the calculation of fractional order. Under the simplifying assumption that the inverse demand and costs of firms are affine functions of the quantities produced, we show numerically some conditions on memory (fractional derivative order) and on the speed of the adjustment process, so that the model proposed converges to Cournot's generalized stationary points. Under these assumptions, we show that the firm that has more memory obtains greater profit.

Engineering system design using the vibrating particles system algorithm

Fran Sérgio Lobato, Jéssica Cristiane Andrade — Fri, 01 Dec 2023 00:00:00 -0300

This contribution aims to apply the Vibrating Particles System Algorithm (VPSA) in engineering system design. In general, this optimization strategy is based on free vibration simulation of a sub-damped system constituted by particles that gradually tend to equilibrium positions. In order to evaluate the capacity of this optimization strategy, three classical problems in engineering context (welded beam design, pressure vessel design and tension/compression spring design) are studied. The obtained results demonstrate that the VPSA configures an interesting alternative to engineering system design compared with other heuristic approaches.

Pollutant dispersion model in landfills by GILTT technique

Fri, 01 Dec 2023 00:00:00 -0300

The expansion of urban centers leads to an increase in the generation of municipal solid waste (MSW). In this way, due to the exorbitant amount of MSW produced annually, studies on the form of disposal of this waste are necessary, so that they are properly disposed of, due to environmental safety and reduction of risks to human health. Therefore, mathematical modeling is an essential tool in the study about the dispersion of pollutants in the porous medium, in this case, in relation to how the water table can be reached by these pollutants. Thus, this work intends to carry out a study of a two-dimensional model of the dispersion of pollutants in sanitary landfills, considering the governing equation in the dimensionless form. In the problem under study, a continuous and uniform leakage from a MSW storage cell is considered. The adopted model is solved by the Generalized Integral Laplace Transform Technique (GILTT) method, whose solution is analytical, except for the truncation error in the infinite series. The results obtained show that the proposed method is effective with the physical characteristics of the problem.

Computational model verification and numerical analysis of plate buckling due to combined loading

Fri, 01 Dec 2023 00:00:00 -0300

Thin plates are structures widely used in different industries, due to their mechanical properties. They are often subjected to combined loading, which can cause an undesired phenomenon called buckling. In this sense, the present work analyzes the elasto-plastic buckling behavior of thin steel plates that are simply supported and subjected to in-plane uniaxial or biaxial compression combined with lateral pressure. To obtain the ultimate stress of the plates, a computational model was developed using the finite element method. Initially, the computational model was verified through previous numerical results from the literature. Then, a case study was carried out considering a rectangular plate geometry with an aspect ratio of b/a = 0.5 (where a and b are the length and width of the plate, respectively), under biaxial compression and varying the lateral loading from 0 to 0.152 MPa, aiming to analyze its elasto-plastic buckling behavior. The results indicated that the computational model was adequately verified. From the case study, it was inferred that the load step plays an important role in the numerical prediction accuracy of the elasto-plastic buckling mechanical behavior of plates In addition, the application of initial imperfection for small lateral pressures has little influence on ultimate stress, while for larger lateral pressures it does not generate influence.

Verification of structural reliability of a highway bridge in the state of Rio Grande do Sul

Vinicius Heidtmann Avila, Mauro Vasconcellos Real — Fri, 01 Dec 2023 00:00:00 -0300

This study deals with the evaluation of the reliability index of prestressed girders members of road bridges in relation to the ultimate limit state (ULS) of bending failure. In a wide bibliographic review of scientific works that deal with structural reliability, prestressed structural elements and road bridges, it is observed that few of these deals specifically with the reliability of girders considering the codes NBR 7188 of 2013 and NBR 7187 of 2021. A mechanical model was developed for the calculation of the beam resistant moment and the Monte Carlo Method was used to obtain a data set that represents the statistics of the structure in the ULS. To obtain the reliability index B, the first order reliability method (FORM) was used. The values obtained by the analytical method are validated using the Monte Carlo simulation method. For all evaluated cases, the value of the reliability index was higher than 4.0, which is higher than the minimum required value of 3.5, showing that the national normative recommendations for the design of beam members guarantee a very conservative level of safety.

A numerical investigation on the wind-induced response of a high-rise building considering the soil-structure interaction

Michael Renê Mix Visintainer, Alexandre Luis Braun — Fri, 01 Dec 2023 00:00:00 -0300

In the present work, a numerical investigation is carried out to evaluate the wind-induced response of a standard tall building model resting on a deformable soil. The numerical model is developed in this work from a partitioned coupling scheme, in which the physical media involved are solved sequentially, and may present independent discretization and solution methods. The problem is spatially discretized using eight-node hexahedral isoparametric elements with underintegration techniques. The fundamental flow equations are kinematically described using an arbitrary lagrangian-eulerian (ALE) formulation and numerically solved using the explicit two-step Taylor-Galerkin scheme. Structure and soil are considered as deformable elastoplastic media, using a corotational approach to deal with physical and geometric nonlinearities. A three-dimensional contact formulation based on the penalty method is used to perform the load transfer between soil and foundation. A hybrid parallelization model based on CUDA-OpenMP techniques is employed to improve the processing performance. Numerical results obtained from aeroelastic analyses are compared with numerical and wind tunnel measurements reported by other authors. Results demonstrated that the soil-structure interaction affected the building response to the wind action and the aeroelastic instability due to vortex shedding can be considerably reduced with the soil presence.

Parameter estimation in the pollutant dispersion problem with physics-informed neural networks

Fri, 01 Dec 2023 00:00:00 -0300

In this work, the inverse problem of parameter estimation in the advection-dispersion-reaction equation, modelling the pollutant dispersion in a river, is studied with a Neural Network approach. In the direct problem, the dispersion, velocity and reaction parameters are known and then the initial and boundary value problem is solved by classical numerical methods, where it is used as input dataset for the inverse problem and formulation. In the inverse problem, we know the dispersion and the velocity parameters and also the information about the pollutant concentration from the synthetic experimental data, and then the aim is to estimate the reaction parameter in the advection-dispersion-reaction equation. This inverse problem is solved by an usual Artificial Neural Network (ANN) and by a Physics-Informed Neural Network (PINN), which is a special type of neural networks that includes in its formulation the physical laws that describe the phenomena involved. Numerical experiments with both the ANN and PINN are presented, demonstrating the feasibility of the approach considered.

Forecast modelling of vegetable oil spill events at Paranaguá port, Brazil

Luiz Gustavo Schmidt, Eduardo de Paula Kirinus — Fri, 01 Dec 2023 00:00:00 -0300

The Port of Paranaguá serves as Brazil's primary outlet for soy oil exports, accounting for nearly 70\% of all shipments in 2021. While less common than mineral oil spills, vegetable oil spills can have similarly devastating environmental effects. This risk underscores the need for effective planning and management of activities involving vegetable oil handling in the region. To address this need, this study developed results based on a forecasting setup focused on describing the behaviour of soy oil spills in the estuarine complex of Paranaguá. The system uses the open TELEMAC-MASCARET three-dimensional numerical modelling system to solve oil movement equations, coupling the hydrodynamic module (Telemac-3d) with the oil module (ECOS). The system is automated through computational routines written in Python and the bash command language, enabling users to initiate simulations and generate dispersion maps to track soybean oil in hypothetical spill scenarios. The processing results were satisfactory, demonstrating the potential for this tool to contribute to minimising the impacts of soybean oil spills in the Bay of Paranaguá. This system can support better decision-making in response efforts, reduce environmental damage, and enhance the protection of local ecosystems.

Performance of the ADF test in stationary series within structural breaks

Fri, 01 Dec 2023 00:00:00 -0300

The study of time series has been developed constantly, given the large volume of observed and measured data over the years. An important characteristic of time series is stationarity, which is mostly analyzed by unit root tests. It is a consensus in the literature that structural breaks, when present in the data series, can bias the result of the Augmented Dickey Fuller Test (ADF), the best known and most widely used method of stationarity investigation. So far, however, there is no consensus regarding the intensity that structural breaks can affect the power of the ADF Test, making the decision about using it difficult and possibly leading researchers to errors under those changes. Thus, this article analyzed the influence of level shift (LS) structural breaks in the stationarity analysis in annual time series using the ADF test through the rejection proportion of the null hypothesis. It was observed that this procedure tends to reject the null hypothesis in the presence of structural breaks in a possible confusion with the presence of a unit root. Furthermore, it was noted that, as the initial perturbation ω, increased, the power of the test was rapidly reduced, mainly with level change breaks imputed in positions closer to the origin of the data series.

Asymptotic homogenization with finite elements for an orthotropic radially microperiodic sphere

Fri, 01 Dec 2023 00:00:00 -0300

This paper proposes a semi-analytical methodology that combines the asymptotic homogenization method (AHM) with the finite elements method (FEM) to solve boundary-value problems with rapidly oscillating coefficients. This approach is motivated by the convergence difficulties observed when this type of problem is addressed directly via FEM, whereas the AHM has shown to be efficacious for obtaining good generic approximations of the exact solution. Illustratively, this AHM-FEM methodology is developed for the mechanical equilibrium problem of a radially microperiodic orthotropic sphere under hydrostatic pressure, which allows its validation by comparing with the AHM analytical solution. Specifically, the effective coefficients and the homogenized and local problems are calculated via AHM, and then their analytical and FEM solutions are obtained. Finally, to validate the semianalytical methodology, the generic solutions are applied in an example and, from the obtained results, a comparison is made between the analytical AHM solution and the semi-analytical AHM-FEM solution.

Assessment of 3DVAR assimilation on the Yakecan subtropical cyclone

Fri, 01 Dec 2023 00:00:00 -0300

In the present work, the impact of the assimilation of AMSU-A satellite data, performed through the three-dimensional variational system of the WRF weather forecast model, is evaluated. The Yakecan cyclone, system that have caused socioeconomic damage in southern Brazil on May 17th 2022, was emulated. Extratropical systems are quite common in the region, however systems such as the Yakecan, which have hibrid characteristics are specially interesting for research purposes. The simulations performed by the WRF model capture the propagation and development of the system. However, the initial condition generated by variational technique showed a more accurate positioning of the system than the simulation without data assimilation. This difference is fundamental for weather forecasting in southern Brazil, since the correct positioning of the system defines whether the consequences of the cyclone affect densely populated areas on the coast of the country or are limited to the adjacent ocean.

Optimization of reinforced concrete structures using population-based metaheuristic algorithms

Rodrigo Reis Amaral, Lamartini Fontana Barazzutti, Herbert Martins Gomes — Fri, 01 Dec 2023 00:00:00 -0300

For many industrial activities, ideal projects are achieved by comparing the solution of alternative projects with those already executed. The feasibility of solutions plays an important role in these activities. For example, the underlying objective (cost, profit, etc.) estimated for each project solution is calculated and the best solution is adopted. This is the usual procedure followed by many constructors due to time and resource limitations. However, in many cases, this method is followed simply by a lack of knowledge of existing optimization procedures. In this context, a comparative study of population-based metaheuristic algorithms applied to a case study of a reinforced concrete beam design reinforced with a polymer matrix with carbon fibers will be presented. Evolutionary algorithms have the ability to determine the optimal values of the design variables without disregarding the restrictions on ACI-318 and ACI-440 standards while minimizing the reinforcement area for each beam (cost). The comparative study shows that not all presented algorithms violated design constraints. In addition, it can be said that the values found for the design variables present a low dispersion around the mean value of the objective function.

A preliminary study on the application of the two-space nonperiodic asymptotic homogenization method to the EEG forward problem with continuously differentiable coefficient

Fri, 01 Dec 2023 00:00:00 -0300

The knowledge on the Electroencephalogram (EEG) forward problem is important to improve the imaging of the neural activity, that is an inverse problem. This paper introduces the study of the EEG forward problem via a nonperiodic homogenization technique: the two-space method. Considering a concentric spheres head model for the brain-skull-scalp medium as an micro-heterogeneous medium, a simplification consisting of a 1D problem in spherical coordinates with continuously differentiable coefficient is considered. The two-space method is applied successfully, and a numerical example shows the convergence of the micro-heterogeneous solution to the one obtained by the two-space method, as was expected. The preliminary conclusion is that this approach for the EEG forward problem with homogenization techniques shows itself as very promising. More experiments should be executed, considering more realistic models for the head.