bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Soil Modeling Strategies with Springs in Free-Span Submarine Pipelines
Authors: Matheus Amancio Miranda  , Eduardo Nobre Lages
Published: January 2025

The fatigue life of submarine pipelines is significantly influenced by structural parameters and environmental conditions to which they are exposed. Numerous studies have focused on modeling this issue using the Finite Element Method to determine frequencies and natural modes of vibration. The models consist of pipeline sections, with some segments in free spans and others supported by soils that can be represented by contact surfaces or sets of springs constituting an elastic foundation. This work aims to evaluate different strategies for representing soil stiffness using springs in a finite element model. Additionally, we investigate the incorporation of the solution for a semi-infinite beam on an elastic foundation to calculate the stiffness of the modeled endpoints. We analyze different element lengths in a free-spanning pipeline model to quantify the influence of various approaches on frequencies and natural modes of vibration. Therefore, this work emphasizes the relevance of parametric studies in modeling submarine pipelines, with particular emphasis on accounting for soil stiffness.
Design of mooring systems for offshore structures through an optimization approach
Authors: Gabriel Rocha Domingos  , Eduardo Nobre Lages  , Adeildo Soares Ramos Junior  , Alan Patrik de Abreu  , Anderson Takehiro Oshiro  , Mauro Costa de Oliveira
Published: January 2025

The design of mooring systems for offshore structures is crucial for ensuring the safe and efficient operation of floating production systems (FPS) within the oil and gas industry. This activity is renowned for its demanding resource requirements, in terms of technical challenges, design criteria, computational cost and extensive hours of work from highly skilled professionals. In this context, structural optimization emerges as a potential solution to mitigate the use of some of these resources, introducing a design approach reliant on optimization algorithms capable of translating technical criteria into mathematical functions and proposing valid and optimized solutions. However, this optimization approach presents its own set of challenges, notably the need of evaluating thousands of structural models, which directly depend on time-consuming numerical simulations. This work aims to treat the optimization challenges by proposing strategies to expedite the computation of numerical models and to support the designing professional in determining optimized designs suitable for direct industrial application.
On the collapse propagation of thick-walled dented submarine pipelines
Authors: Michele Agra de Lemos Martins  , Caroline Ferraz de Melo Netto  , Theodoro Antoun Netto
Published: January 2025

Subsea pipelines are susceptible to structural instabilities. Particularly in deep waters, where pressures are very high, collapse is the most critical instability and can be rapidly propagated, damaging kilometers of the pipeline, with catastrophic impacts. In addition to high pressures, any damage that may occur due to impact, excessive bending, corrosion, and other causes during pipeline transport, installation and operation, can dramatically reduce the collapse and propagation pressure of the structure. Static buckling of pipelines under external pressure is a well-established subject in the literature and classical theories such as Timoshenko's provide reasonable estimates of the buckling threshold under some conditions. The accuracy of these predictions is particularly good for long, thin tubes, but when it comes to damaged thick-walled pipelines, there is a gap of knowledge and a lack of information regarding the post-buckling behavior of such pipes. Thus, this work aims to present a comprehensive study on the collapse propagation of thick-walled dented submarine pipelines based on experimental analysis, numerical models and a parametric study in order to cover several scenarios of interest.
Reliability Analysis of the Collapse of Corroded Submarine Pipelines Subjected to Bending Moment
Authors: Luccas André Felix Silva  , Silvana Maria Bastos Afonso da Silva  , Renato de Siqueira Motta
Published: January 2025

With the increasing development of oil exploration in the oceans, the demand for submarine pipelines has risen considerably, which implies significant environmental risks in the event of structural failure, resulting in oil leaks and consequent billion-dollar environmental damage. The integrity of these structures is primarily compromised by external pressures and bending moments, especially in areas of high curvature between platforms and extraction points. These bending moments, as identified in the investigations of Bjørset (2000), decrease the pipelines resistance to collapse due to the progressive ovalization of the sections, reducing the moment of inertia. Additionally, corrosion defects, which decrease the thickness of the pipeline walls, are prevalent and significantly impact the resistance to collapse, requiring precise evaluation in simulations (CABRAL, 2007). For the modeling of this mechanical phenomenon, the Finite Element Method (FEM) has shown promising results, being chosen to calculate the collapse pressures by combining the effects of bending moments and corrosion defects (MOTTA, 2020). However, the simulation process faces challenges due to uncertainties associated with measurement errors, equipment calibration, and manufacturing faults. These uncertainties are generally overlooked in traditional deterministic methods but can be addressed through reliability analyses that use statistical concepts to establish failure functions and assess failure probability, resulting in a more robust and reliable analysis (MOTTA, 2020). These analyses are rarely discussed in the existing literature, suggesting a need for more well-founded and detailed approaches. The results of this study, with the application of reliability techniques, are expected to provide safer insights into the influence of bending moments on the resistance of submarine pipelines. Furthermore, it is intended to compare deterministic equations with simulation results, proposing, if possible, adjustments to these equations to optimize the accuracy of the provided results.
Analysis of human intervertebral disc fracture mechanisms, case studies
Authors: João Pedro Schmitz  , Aref Kalilo Lima Kzam
Published: January 2025

In the world, one of the leading causes of hospitalizations and disabilities is disc herniation. Therefore, understanding the mechanisms that lead to the development of this pathology is of high medical interest. For this purpose, a 3D model of a lumbar section (L5-S1) will be analyzed using tools commonly used in civil engineering, such as the Finite Element Method (FEM). The 3D model was generated from real imaging exams, such as computed tomography and magnetic resonance imaging. Subsequently, the mechanical properties (elastic modulus E and Poisson's ratio) of the structures of interest (annulus fibrosus, nucleus pulposus, and cartilaginous endplate) were incorporated into the models. Then, the model will be subjected to vertical compression forces combined with movements such as lateral, anterior, posterior flexions, and rotations. The primary objective of this project is to understand which combinations of loads and movements lead to structural damage, primarily affecting the annulus fibrosus, resulting in decompression of the nucleus pulposus. After analyzing the failure mechanisms of the structure, the variations in mechanical properties due to different degrees of pathology (protrusion, prolapse, extrusion, and sequestration) will be examined. This stage will contribute to a better understanding of the interaction between the components of the intervertebral disc following the development of pathology and the constraints imposed by its progression.
Do gender-specific carotid plaque characteristics and stroke risk prediction suggest different biomarkers for men and women?
Authors: Catarina Rosa Santos Ferreira de Castro
Published: January 2025

There is convincing evidence for sex differences in carotid atherosclerosis although the relation between sex and plaque characteristics needs further insight accessing individual patient data characteristics to perform these analyses. The structure and composition of arterial walls can differ between genders. At every age, most women are of shorter stature and smaller size than most men. Height is related directly to arterial caliber and length as well as cardiac output through effects on stroke volume and heart rate.Statistical comparisons for gender suggest that females appeared more vulnerable to the progression of arterial stiffening [1]. Carotid plaque measurements using maximum wall thickness as 1-dimensional (1D) size, wall area as 2D size, and wall volume as 3D size are larger in men opposed to women [2]. Nevertheless, the normalized wall index, which accounts for the total vessel size, shows no significant difference between males and females. Regarding the number of calcifications, it was found that men have higher calcification volumes than women and accordingly intraplaque hemorrhage is more common in men than in women [3]. Sex differences in stroke incidence, and complication rate have been reported [4].The current study aims a review of recent publications on gender-specific differences regarding carotid plaque characteristics and stroke risk aiming different biomarkers for men and women what may benefit clinical management and specific treatment.[1] Wang Z, Li W, Liu W, Tian J. Gender is a determinant of carotid artery stiffness independent of age and blood pressure. Br J Radiol. 2021 Mar 1;94(1119):20200796. [2] van Dam-Nolen DHK, van Egmond NCM, Dilba K, Nies K, van der Kolk AG, Liem MI, Kooi ME, Hendrikse J, Nederkoorn PJ, Koudstaal PJ, et al. Sex differences in plaque composition and morphology among symptomatic patients with mild-to-moderate carotid artery stenosis. Stroke. 2022; 53:370378. [3] Scheffler M, Pellaton A, Boto J, Barnaure I, Delattre BM, Remuinan J, Sztajzel R, Lovblad KO, Vargas MI. Hemorrhagic plaques in mild carotid stenosis: the risk of stroke. Can J Neurol Sci. 2021; 48:218225. [4] Voigt S, van Os H, van Walderveen M, van der Schaaf IC, Kappelle LJ, Broersen A, Velthuis BK, de Jong PA, Kockelkoren R, Kruyt ND, et al; DUST study group. Sex differences in intracranial and extracranial atherosclerosis in patients with acute ischemic stroke. Int J Stroke. 2021;16: 385391.
A boundary element solution for free vibration of FGM beams
Authors: John Williams Ferreira de Souza  , Paulo Cavalcante Nascimento Junior  , Arthur Coutinho de Araújo Pereira  , Welky Klefson Ferreira de Brito  , Ângelo Vieira Mendonça
Published: January 2025

The main purpose in this article is to derive a new solution based on Boundary Element Method (BEM) for dynamic analysis of Euler-Bernoulli beams made of composites such as Functionally Graded Materials (FGM) that have properties that vary continuously through the thickness direction according to the volume fraction of constituents. In contrast, laminated composite materials are oriented plies bonded together, where each ply may be made of a different material. A boundary element solution for any problem is obtained using integral equations and fundamental solutions defined on continuum, and algebraic equations for the discretized problem. In this paper, original discussions on deriving both integral equations and fundamental solutions for dynamic composite beam problems are properly made. Algebraic representation is also obtained, incorporating rigid and elastic end supports into the BEM solution. Numerical results of different cases of mechanical properties and boundary conditions are considered and compared to other published works.
A formulation of the fast multipole boundary element method applied to the analysis of anisotropic materials under body forces
Authors: Éder Lima de Albuquerque  , Danilo Diego Chaves Mateus  , Jaílson França dos Santos  , Lucas Silveira Campos  , Afonso Barros Dias Jr.
Published: January 2025

This work presents a formulation of the boundary element method with fast multipole expansion (MECMP) applied to the analysis of anisotropic elastic materials subject to body forces. Integral equations are obtained using the Somigliana identity. Integrals are divided into near field and far field. Near field, when the source points and integration elements are close, are treated as in the standard boundary element method, that is, integrating along the element and considering the interaction between source points (nodes) and the elements. On the other hand, in the far field, when the source points and integration elements are far away, the fast multipole method is applied. In this case, the fundamental solution is expanded in a Laurent series and the node-to-node interaction is replaced by a cell-to-cell interaction. Cells are generated by a hierarchical decomposition of the domain using the quad-tree algorithm. Different fast multipole operations are used to take advantage of the hierarchical domain decomposition and expansions of the fundamental solutions. Influence matrices are never explicitly obtained and the matrix-vector product are carried out with linear complexity. The linear system is solved by an iterative method. A preconditioning matrix is used to reduce the number of iterations to obtain a result with an specified accuracy. Effectiveness and efficiency in solving large-scale problems are discussed. The treatment of problems involving body forces are taken into account by the utilization of the modified boundary condition method. This approach entails augmenting the boundary condition with a specific solution tailored to the problem. Following the solution of the linear system, the particular solution is subsequently subtracted from both displacements and tractions. Importantly, this procedural step obviates the need for generating additional vectors or matrices within the matrix equation. The formulation presented in this article is based on a representation of complex variables of the integrands, similar to the formulation previously developed for potential (scalar) problems. Validation is carried out by comparing the results obtained by the two formulations: the standard boundary element method and the boundary element method with fast multipole expansion. The influence of the number of terms of the series expansion in the calculation of fundamental solutions and influence matrices is analyzed. Numerical examples are presented to demonstrate the efficiency, accuracy, and potential of the boundary element method with fast multipole expansion to solve large-scale problems, i.e., with tens of thousands of degrees of freedom.
Implementation of a Fatigue Analysis Program Based on the Dual Formulation of the Boundary Element Method
Authors: Beatriz Borges Faria Fonseca  , Rodrigo Guerra Peixoto
Published: January 2025

The study and analysis of fatigue are extremely important, given the countless financial and social losses caused by this damage process. For this reason, a complete computational program is implemented for two-dimensional fatigue analysis in cracked components, coded in Fortran 95 language. The Dual Boundary Element Method (DBEM) is used to evaluate the elastic fields of displacement and traction, through the placement of Boundary Integral Equations (BIE) of different natures on each of the crack faces. Stresses and strains at boundary points are evaluated through the hypersingular BIE. Once the variables of interest are obtained in the boundary, the fatigue subcritical propagation of cracks is evaluated based on the concepts of Linear Elastic Fracture Mechanics (LEFM). J-Integral is used to measure the stress intensity factors at the crack tip, due to its effectiveness, precision and excellent coupling with the dual formulation of the Boundary Element Method (BEM). The direction of crack propagation is defined by the Maximum Circumferential Stress criterion. Finally, the lifespan of the cracked component is determined using an adapted Paris Equation, in order to correctly evaluate mixed mode fracture and non-zero mean stresses. Furthermore, using the Rainflow Cycle Counting algorithm, the program is capable of evaluating components under the action of cyclic loads of variable amplitude. In order to evaluate the implemented computational program, two examples are presented. The first considers a Compact Mixed Mode (CMM) specimen under mixed mode fracture. The second example evaluates the driven wheel of an iron ore pelletizing furnace under cyclic loading of variable amplitude. According to the results presented, it is proved the effectiveness and reliability of the developed computational program, which allows to accurately analyze real situations of components under mode I, II or mixed mode fatigue.
Continuous-discontinuous modeling of failure in micromorphic media
Authors: Pamela Daniela Nogueira Reges  , Roque Luiz da Silva Pitangueira  , Leandro Lopes da Silva  , Lapo Gori
Published: January 2025

Deformation and failure are typically developed at multiple scales for the majority of engineering materials. At the macroscopic level of observation, structural rupture is triggered by a localized failure that corresponds to a loss in the material continuity within a specific region of the body. This localized failure is preceded by microcrack coalescence that can be observed at lower observation levels. This study investigates the propagation of a discrete fracture within a continuum damage process zone within the framework of micromorphic media. The adopted generalized continuum theory is well suited for modeling microstructured materials and also recognized in the relevant literature for its regularization properties due to its non-local formulation. Microcracking prior to coalescence is represented by continuum damage models based on a recently proposed formulation for elastic degradation in micromorphic media. The propagation of a discrete fracture is based on the analysis of a generalized micromorphic acoustic tensor, which is here derived considering the concepts of acceleration waves. When instability is detected, a discontinuity is introduced by the Extended/Generalized Finite Element Method. The required implementations for the numerical investigation of the proposed model are conducted in the open-source software INSANE.
Numerical Analysis and Validation of Fracture Toughness Factors using BEMCRACKER2D through Boundary Element Method
Authors: Iuri Augusto Alves Lustosa  , Gilberto Gomes  , Alvaro Martins Delgado Neto
Published: January 2025

Fracture Mechanics (MF) represents a complex domain in the study of materials and structures that exhibit flaws, known as cracks. Over the last century, we have witnessed progress in the development of studies related to MF, consolidating it with practical applications in the field of structural engineering, particularly in prominent sectors such as the naval and aerospace industries, where crack prediction is of paramount importance. However, given the inherent complexity of these challenges, there is an increasing reliance on the application of numerical methods, particularly the Boundary Element Method (BEM), to perform computational analyses of crack propagation, based on the principles of Linear Elastic Fracture Mechanics (LEFM). In this scenario, the present study conducts an analysis of fracture toughness factors, k1 and k2 comparing numerical curves derived from models found in the literature with those obtained through the implementation of crack propagation prediction criteria (such as Maximum Circumferential Stress, Maximum Potential Energy Release Rate, and Minimum Strain Energy Density), using BEM. To generate these curves, the software BEMLAB2D and BEMCRACKER2D were used, developed for modeling and analysis via BEM, respectively. The results obtained confirm the efficacy of numerical methods, demonstrating good convergence between the numerical curves from the literature and those generated by the applications. Among the prediction criteria, the Maximum Circumferential Stress method stands out as having the greatest correspondence with experimental results.
Effect of spatial variability of soil properties on slopes stability under rapid water drawdown conditions
Authors: Mário Vargas Ceron  , Diogo Lira Cecílio  , Renato Vaz Linn  , Samir Maghous
Published: January 2025

Stability analysis of slopes is a fundamental problem of Soil Mechanics. Its main objective consists of evaluating the potential failure of the slope structure under a prescribed loading mode. A major component of the latter refers to the seepage forces induced by pore-pressure gradient, which is known to be responsible of destabilizing effects. This contribution employs a kinematic approach of limit analysis theory to obtain upper-bounds solutions to the stability problem of saturated slopes submitted to rapid water level drawdown. Random fields are used to model the uncertainty surrounding the spatial distribution of soil cohesion, friction angle, and permeability. In the context of effective stress governing the strength capacities of the soil material, it is shown that the seepage forces related to the water flow regime can be considered as external volumetric loads in the assessment of stability. The hydraulic problem governing the water filtration velocity is evaluated by resorting to an analytical variational approach, whose results are validated by comparisons with finite element solutions. The impact of hydraulic-related parameters on stability is first investigated for slopes within a deterministic framework. Subsequently, random fields are considered to take into account the variability related to the spatial distribution of the material properties, which are discretized using the Karhunen-Loève expansion with numerically computed eigenfunctions. The failure probability of slopes is assessed through Monte Carlo simulations. Several analyses have been performed to discuss the influence of the spatial variability of relevant problem parameters.
Finite element analysis of rock deformation in deep twin tunnels
Authors: Felipe Pinto da Motta Quevedo  , Carlos Alberto Magnus Maciel Colombo  , Bianca Milena Girardi  , Denise Bernaud  , Samir Maghous
Published: January 2025

Relying upon a three-dimensional finite element analysis, this contribution investigates the instantaneous irreversivel response induced by the constitutive behavior of the rock mass in the convergence profile of twin tunnels. At the rock material level, elastoplastic state equations based on a Drucker-Prager yield surface with an associated flow rule are adopted in the modeling. As regards the tunnel support, the formulation accounts for the presence of an elastic shotcrete-like lining. From a computational point of view, the deactivation-activation method is used to simulate the excavation process and the installation of the lining. The accuracy of the finite element predictions is assessed through comparisons with the available analytical solutions formulated in a simplified scenario for the twin tunnel configuration. A parametric study investigates the mutual interaction induced by the proximity of the tunnels.
A Multi-Objective Ant Colony Optimization for Routing in Printed Circuit Boards
Authors: Heitor Teixeira de Azambuja  , Luiza de Macedo Mourelle  , Nadia Nedjah
Published: January 2025

Automatic routing for Very Large-Scale Integration (VLSI) and Printed Circuit Board (PCB) design is an important tool to facilitate and optimize the work of engineers. Such a tool is typically provided by popular Computer-Aided Design (CAD) software and is a long-running research field. As electronics technology evolves and both discrete and integrated components get smaller and faster, the constraints to design circuits become more complex and new challenges arise. To deal with these difficulties, strategies using computational intelligence algorithms are employed to provide viable routing solutions in a timely manner. Within these strategies, multi-agent and swarm algorithms are highly relevant, being frequently applied alongside other approaches or by themselves. In this paper, we introduce a variation of the typical Ant Colony Optimization (ACO) algorithm modified to perform PCB routing, focusing on length matching between traces. The PCB area is divided into a grid that represents the search space for the algorithm. For each trace, the initial and final positions are known and contained within a cell of the grid. The routing of each trace is performed by an individual ant colony. The ants of a colony must travel from the initial to the final position of a trace to find the route that better fits the constraints of a multi-objective function. An ant in a cell can only move to neighboring cells. The number of movements it makes represents the length of the route. The algorithm consists of three steps. First, colonies and data structures are initialized. In the second step, one iteration is performed; the ants of each colony find a route to a trace. In the third step, the results found by the ants are evaluated, and the pheromone trails for the colonies are updated. The pheromone trails are updated based on a function that simultaneously minimizes three objectives: trace length, the number of times that traces cross with each other, and the length difference between traces. In other words, the ants try to find the shortest possible trace that has the same length as the other traces without crossing with them. Steps two and three are repeated until the maximum number of iterations is reached. We tested our algorithm in five fundamental scenarios and performed a statistical analysis on multiple executions of each scenario. The results obtained show that our algorithm is a viable approach to perform PCB trace routing with length matching.
Access Control with Facial Recognition: A Systematic Literature Review
Authors: Thalita Ribeiro Esser da Silva  , Rogério Alves dos Santos Antoniassi  , Alex Fernando de Araujo
Published: January 2025

Counting people or even identifying individuals present in a given place is a fundamental task for public and private sectors and/or institutions that need to manage the access and permanence of individuals in certain places. This is not different at the Federal Institute of Education, Science and Technology of Mato Grosso do Sul - Campus Três Lagoas, which has a large physical space and only a few employees to control and supervise these facilities, which are shared by high school and college students, requiring more strict access control, especially in research laboratories. Several tools and methodologies have been proposed to meet this demand, including the use of DeepLearning, convolutional networks and a wide variety of facial recognition algorithms, which show great potential, as they are present in several solutions in the literature. The aim of this paper is to carry out a systematic review of the literature, broadly investigating best practices and success cases in using facial recognition to control people's access to environments. The review makes a significant contribution to those who intend to develop or research in this field, as it presents an overview and discusses what has already been tested and returned a good outcome and what did not generate a satisfactory result, as well as presenting the results of tests and proofs of concept carried out at the IFMS - Campus Três Lagoas.
Predicting Blockchain Application Performance with Machine Learning Techniques
Authors: Willian Macedo Rodrigues  , Silvia das Dores Rissino  , Karin Satie Komati
Published: January 2025

Blockchain technology is a distributed ledger designed to record all transactions within its network, characterized by its decentralized nature, resistance to tampering, and attributes such as consistency, anonymity, and traceability. However, evaluating blockchain applications' performance can be complex due to their intricate and distributed infrastructure. This research employs machine learning model-based methods to predict blockchain systems' performance using predetermined configuration parameters. The data used in this study is derived from a blockchain simulator, generating blockchain data to facilitate performance predictions. The simulation process involves using simulated data and configuration settings for each run, including parameters such as the number of nodes, the number of miners, consensus algorithm, maximum block size, and transaction quantities, among others. Output metrics such as the total number of blocks, transaction rate, block propagation time, and latency are utilized to assess network performance. The simulator was run 184 times with various configurations. Our findings indicate that the Random Forest model outperformed other models used in the experiments, achieving the highest R² scores for multiple metrics, such as 0.987 for total number of transactions and 0.765 for average block propagation time, while also demonstrating lower RMSE values, indicating more accurate predictions.
Tomato Detection and Classification by Color, Size, and Imperfections using Computer Vision
Authors: Alexander Gegeski Dias  , Gustavo Maia
Published: January 2025

Tomatoes stand out in agribusiness, as they are one of the most consumed vegetables in the world. There is a growing search for healthier foods and tomatoes are an important source of vitamins A, C and B1. Its production, handling and transportation are complex due to its sensitivity to the environment, pest attack, road conditions, among others. Consumer markets are increasingly demanding, with its quality as a decisive factor for purchases. The price is also one of the primary factors for the purchase by the customer, both the prices and the quality of the tomato take into account the size, color and quantity of imperfections that the fruit presents. The classification by size nowadays is done using a mat with holes of small, medium and large sizes and as the tomato fits in the mouth whose size best adapts it will fall into boxes with tomatoes of its respective size, however, on these mats it is not possible to check neither the color nor the imperfections. Another form of classification is by electronic equipment that is capable of verifying the size and color, but they are imported machines and extremely expensive, in addition to not detecting imperfections. The most common form nowadays is the manual one, where a trained person separates the tomato according to its size, color and imperfections, however, this form of analysis makes the classification process slow and subject to subjectivity. In view of this scenario and taking into account the numerous applications of Computer Vision in agribusiness, this work proposes to create a tomato classifier by color, size and imperfection, using computer vision.
Effect of Soil-Conductor Gap Formation on the Fatigue of Subsea Wellheads
Authors: Rafael Dias  , Anderson Pereira
Published: January 2025

The construction of offshore oil wells in deepwater typically involve the use of floating rigs. These rigs transmit their motion through the drilling riser to the wellhead and casings, which can result in fatigue damage. In our research, we verified a hypothesis suggesting that high loads (e.g., a storm or a rig drift-off) can cause plastic deformation in the soil, causing the opening of a gap between the conductor and soil. This would result in change of the dynamic behavior of system, and consequently on the cumulative damage. We modelled numerically the problem using Finite Element Method. Wave and current loads were simulated stochastically. Soil was implemented as nonlinear springs that obey a bounding surface plasticity model. The results compare displacements, bending moments and fatigue damage across several scenarios, as well as the likelihood of VIV onset.
Local remesh procedure to model reaming in vertical oil wells drilled through salt rocks
Authors: Luis Philipe Ribeiro Almeida  , Catarina Nogueira de Araújo Fernandes  , João Paulo Lima Santos  , Antônio Paulo Amâncio Ferro  , Themisson dos Santos Vasconcelos  , João Fyllipy de Lima Nunes  , Rafael Dias  , Bruno Sergio Pimentel de Souza  , Fabio Sawada Cutrim
Published: January 2025

This paper presents an alternative methodology, based on cutting and adjusting finite elements, to model reaming of salt rocks during vertical wells drilling. The developed strategy ensures that the stress, deformation, and displacement fields are maintained after the remesh. To reach the pre-salt hydrocarbon reservoirs it is necessary to pass through thick layers of salt rocks. The mobility of these salt rocks can cause serious operational problems, such as the imprisonment of the drill string, casing collapse and annular entrapment of columns, compromising the casing integrity. Therefore, adequate monitoring of the well diameter must be done constantly throughout the entire drilling process. Thus, reaming procedures may be required to recondition the diameter of the well to its original state. The reaming strategy presented in this work is based on removing and adjusting mesh elements reestablishing the initial radius of the well in specific regions. This procedure improves the precision and realism of the simulations, avoiding the appearance of a gap between the mesh and drill bit passage. Stress graphs along the wellbore and comparisons with real wells data are used to enhance the phenomena understanding and validate the proposed methodology
On the accuracy of prediction models for the collapse strength of worn casing
Authors: Lucas Pereira de Gouveia  , Rafael Nunes da Cunha  , Eduardo Toledo Lima Junior  , João Paulo Lima Santos  , William Wagner Matos Lira  , Charlton Okama de Souza  , Emilio Cesar Cavalcante Melo da Silva
Published: January 2025

Oil and gas wells are typically built in highly complex and harsh environments. Casing is a crucial part of the well structure, undergoing a wide range of loads during the well life cycle, such as internal and external pressures, and axial force. After installation, these tubulars may develop wear grooves on their inner wall, caused by contact with the tool joints of the drill string. This reduction in wall thickness, combined with initial geometric imperfections, such as ovality and eccentricity, as well as residual stresses, may cause a significant reduction in tubular resistance, especially under external pressure (collapse). Thus, models that can estimate accurate collapse pressure, validated with realistic data, are extremely relevant. In this context, some collapse prediction models of worn casing are proposed in the literature, based on experimental, analytical, or numerical approaches. However, in several cases, the data used in deriving the models are limited in quantity and variety of cases. The present study aims to investigate and propose improvements in the equations for the collapse pressure of worn casing by using a large database of numerical simulations. Several Finite Element (FE) simulations are performed to generate a large database of collapsed pipes. Then, the accuracy of collapse prediction models from the literature is evaluated, while calibrating new model parameters to enhance precision. The study is carried out adopting material and geometric configurations that are commonly observed in worn casing tubulars of oil and gas wells. Two subsets of the large databases were generated: one is used for fitting the models and the other for testing them. The exploratory analysis of the FE database provides insights into the collapse strength deration in relation to relevant parameters, such as damage depth, tool joint radius and tube slenderness. The results compare the accuracy of the models, and a discussion about features influence is carried out in parallel.
Assessment of reactive surface and kinetic parameters of basaltic rocks during CO2 storage
Authors: Karin Kauss  , Ronald Beyner Mejia Sanchez  , Deane Roehl
Published: January 2025

Carbon capture and storage (CCS) is a novel technology that aims to reduce the presence of carbon dioxide from the atmosphere. This technology involves capturing CO2 from industrial sources or directly from the air, treating, transporting, and storing it in long-term safe rock formations. Basaltic rock comprises reactive minerals and glassy phases, which trap CO2 permanently through the mineralization mechanism. However, this method is complex mainly due to the rapid interaction between solid and liquid phases. The mineralization occurs at the interface between the reactive fluid and the basaltic rock surface, converting the dissolved CO2 into solid carbonate mineral that precipitates in the pores and fractures of the rock matrix. The reaction rate of a basaltic rock depends significantly on the CO2 wettability and rock-fluid interfacial interactions. However, there is limited information about the influence of the reactive surface on the reaction rate of minerals present in basalt formations. This work investigates the influence of kinetics parameters such as pH, temperature, and reactive surface area in the reaction rate of basaltic rocks. Basaltic rock dissolution and precipitation is assessed using the geochemical software PHREEQC. The proposed numerical model solves the reactive transport problem and provides feedback on the influence of the kinetics reaction parameters. The dynamics of the reactive surface during the reaction of basalt rocks is evaluated. The numerical results show the potential of basaltic rock for CO2 mineral storage as solid carbonates and identify the main factors that limit the mineralization process. Finally, this work provides a deeper understanding of CO2 mineralization that can provide valuable findings to guide Brazilian CCS projects.
A Preliminary Numerical Thermal Analysis of an Endometrial Ablation Procedure Based on Foleys Catheter
Authors: Bruna Rafaella Loiola  , Francesco Scofano Neto  , Rodrigo Otávio de Castro Guedes
Published: January 2025

Dysfunctional uterine bleeding (DUB) is an ailment affecting a substantial number of women during a significant part of their reproductive years. This condition usually leads to discomfort, mild or severe pain, or, in some extreme cases, anemia. It may be caused by diverse factors such as hormonal issues, structural abnormalities, or even cancer in a womans reproductive tract. A typical DUB treatment requires a pharmacological approach through the prescription of drugs. Nonetheless, some patients require a more involved treatment calling for surgical procedures. In order to avoid hysterectomy, which is the complete removal of the uterus, the medical community has devised, over the years, alternative surgical schemes to handle DUB issues. One such treatment is the endometrial ablation technique where the inner lining of the uterus is subjected to a controlled destruction by using a hot, approximately constant-temperature fluid inside a balloon, which is placed in contact with the uterine wall of the patient. As a means to avoid the high costs associated with such devices, the medical community has proposed a similar treatment in which the fluid inside the balloon is no longer held at a high constant temperature but rather diminishes as the treatment progresses. The main purpose of this contribution is to critically assess the effectiveness of this second, low-cost endometrial ablation treatment. Consequently, a mathematical model is devised in which Pennes bioheat equation is employed to predict the transient temperature field of the uterine wall together with an energy balance that yields the temperature of the saline solution inside the thermal balloon, throughout the duration of the treatment. These equations aresolved by utilizing the finite volume method and the numerical predictions are verified by comparing the present results with similar cases from the literature. Once the verification phase is authenticated, the uterine wall and fluid balloon transient temperature fields are obtained for typical situations reported in the medical literature. On general grounds, the simulations indicate that the extent of the affected tissue is strongly dependent on the volume,on the type of fluid inside the thermal balloon, and on the magnitude of the perfusion of the uterus. Moreover, it was found that the proposed low-cost treatment can indeed be a successful alternative to the standard endometrial ablation process under some viable circumstances that are described in the contribution.
Comparison between a stabilized mixed finite element formulation for Hershel-Bulkley fluid and regularized models
Authors: Daiana Soares Barreiro  , José Karam-Filho  , Abimael Loula
Published: January 2025

In this work, a mixed stabilized finite element formulation with continuous interpolations for velocity and descontinuous formulation for pressure is used to approach pseudoplastic materials with yield stress, that is, non linear viscoplastics. Here, Herschel-Bulkley model, [1], and regularized ones for the apparent viscosity are considered. This formulation is based on two well succeeded stabilized methods, separately, one for pseudoplastic problems (non linear) without yield stress [2], and the other for linear problems with yield stress (ideal plastic), [3],which are modeled by linear constitutive equations with inequality restriction.Firstly it is presented the difficulties encountered by classical formulations in solving the problems separately, as well as solutions proposed before for each of those problems.Regularized generalized alternatives (based on simple, Papanastasiou [4] and Bercovier-Engelman [5] schemes) are presented to deal with the discontinuity of the constitutive relations for the materials with yield stress and results are presented showing their limitations. They are compared with the proposed stabilized formulation which allows obtaining stable results without the necessity of regularizations, applied directly to the Herschel-Bulkley constitutive relation. References[1] A.H.P. Skelland. Non-Newtonian Flow and Heat Transfer. John Wiley & Sons, Oxford, 1967.[2] Bortoloti, M. A. A. and Karam F., J. A Stabilized Finite Element Analysis for a Power-Law Pseudoplastic Stokes Problem, Applicable Analysis, V. 95, n.2, pp. 467-482, 2016.[3] Faria, C. O. ; Karam F., J. . A Regularized Stabilized Mixed Finite Element Formulation for Viscoplasticity of Bingham Type, Computers and Mathematics with Applications, 2013. V66, no.6, pp. 975-995, 2013.[4] T. C. Papanastasiou e A. G. Boudouvis. Flows of viscoplastic materials: Models and Computations. Computers & Structures, 64(1-4):677694, 1997.[5] M. Bercovier e M. Engleman. A Finite-element method for incompressible non-Newtonian flows. Journal of Computational Physics, 36:313326, 1980.
A co-rotational finite element for nonlinear analysis of hollow section steel frames accounting for local buckling via lumped damage mechanics
Authors: Sérgio Gustavo Ferreira Cordeiro  , Deborah Cristina Nardi  , David Leonardo Nascimento de Figueiredo Amorim
Published: January 2025

To reduce engineering costs, the search for more efficient materials and design concepts leads to slender structures. Consequently, the need for geometrically nonlinear analysis is becoming increasingly important. Besides, the phenomenon of local instability becomes more evident when dealing with structural components with hollow cross-sections composed of slender plates and shells. It is usual to employ elastoplastic shell finite element models for dealing with such problems, which leads to analyses with high computational costs. Therefore, this paper proposes a geometrical nonlinear beam finite element, developed for the nonlinear analysis of hollow section steel frames, accounting for local buckling. The finite element is locally formulated as the traditional linear Euler-Bernoulli beam element. A co-rotational description of motion is then employed to account for large displacements and rotations. The local buckling phenomenon is taken into account by a lumped damage model, which concentrates the effects at inelastic hinges. The inelastic hinge´s yield functions are defined in terms of the co-rotational nodal axial forces and bending moments, as well as in terms of damage variables. The local buckling of the hollow sections is accounted by the adopted damage evolution law. The inelastic rotations are governed by the normality rule and the evolution laws of the internal variables. A predictor-corrector algorithm is employed at element level, whereas the Newton-Raphson method solves the global nonlinear equilibrium equations. To assess the accuracy of the proposed model, the numerical results obtained in this study are compared against available numerical and experimental responses. The numerical results show good accuracy, which corroborates that the proposed model might be used in practical applications.
Reinforced concrete plates: cracking and ultimate load through Lumped Damage Mechanics
Authors: Rafael Nunes da Cunha  , David Leonardo Nascimento de Figueiredo Amorim  , Sergio Persival Baroncini Proença  , Julio Flórez-López
Published: January 2025

In structural analysis, it is crucial to accurately characterize the nonlinear behavior of structures. This behavior may result on strain localization phenomena, that may lead to collapse processes. Lumped Damage Mechanics (LDM), one of the more recent nonlinear theories, has shown promise for a variety of applications. It is applied to frame elements, for static and dynamic analysis, in reinforced concrete, plain concrete or steel structures, or in continuous media, with plate elements for plain concrete or bending plate elements, for reinforced concrete slabs. This paper presents the study of reinforced concrete slabs using LDM. Damage and plastic rotations are the internal variables of the problem that characterize concrete cracking and reinforcement yielding, respectively. The results numerically obtained were confronted with experimental ones. It was observed that the model is highly accurate in describing the initiation and propagation of cracks, as well as identifying the collapse mechanism, in addition to precise Load vs. Deflection results, close to the experimental values.
NEUROPSICOLOGIA CLÍNICA: INTERVENÇÕES EM REABILITAÇÃO COGNITIVA
Authors: Capita Zaika
Published: January 2025

Objetivo: Revisar a literatura recente sobre intervenções em reabilitação cognitiva, destacando técnicas, populações-alvo e resultados obtidos. Método: Estudo de revisão integrativa, utilizando bases de dados eletrônicas (PubMed, Scopus, Web of Science e SciELO), com critérios de inclusão como artigos publicados entre 2013 e 2023, em português, inglês ou espanhol, abordando intervenções neuropsicológicas baseadas em evidências. Resultados: Estratégias como treinamentos cognitivos, uso de realidade virtual e abordagens multidisciplinares demonstraram eficácia em condições como Transtorno do Espectro Autista e depressão, enquanto populações com doenças neurodegenerativas, como Alzheimer, apresentaram resultados mais modestos. Avanços tecnológicos mostraram potencial para melhorar a eficiência cognitiva e funcionalidade. Conclusão: A reabilitação cognitiva apresenta resultados promissores em diversas condições clínicas, especialmente quando integradas tecnologias emergentes e abordagens interdisciplinares. São necessários mais estudos para superar desafios como padronização de protocolos e limitações logísticas, ampliando a acessibilidade e eficácia das intervenções.