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Experimental and numerical study of the ultimate capacity of intact and damaged steel CHS X-joints submitted to compressive loads

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Marine systems and Ocean Technology 2025年第1期20卷 1-15页

作者： Coelho, J.C. Cyrino, J.C.R. Vaz, M.A. de Paula, G.G. Ocean Engineering Program Universidade Federal do Rio de Janeiro Rio de Janeiro Brazil PETROBRAS/CENPES Rio de Janeiro Brazil

This paper presents a numerical and experimental investigation of the ultimate capacity of X-shaped circular hollow section (CHS) steel joints, when the brace members are submitted to axial compression. Three joints are manufactured and tested, one intact and the other two with symmetrical central circular perforation damage in the chord. The results obtained from the numerical and experimental simulations proved to be consistent in terms of the axial load versus displacement curve and strains measured in 5 locations in the chord. It was observed that the damage reduces the tubular joint strength and the greater the damage the lower the joint load bearing capacity. The results obtained from the experimental test and numerical model are compared with the intact joint strength equations proposed by CIdeCT design guide and Eurocode 3 and show the conservatism of the design standards. © The Author(s), under exclusive licence to Sociedade Brasileira de Engenharia Naval 2024.

关键词： Tubular steel structures

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Microvolt T-Wave and Ventricular Repolarization Duration Alternans 9th

Microvolt T-Wave and Ventricular Repolarization Duration Alt...

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9th Latin American Congress on Biomedical engineering, CLAIB 2022 and 28th Brazilian Congress on Biomedical engineering, CBEB 2022

作者： Winkert, Thaís Nadal, Jurandir Benchimol-Barbosa, Paulo Roberto Biomedical Engineering Program COPPE Institute Universidade Federal do Rio de Janeiro Rio de Janeiro Brazil Hospital Universitário Pedro Ernesto Universidade do Estado do Rio de Janeiro Rio de Janeiro Brazil

ISBN: (纸本)9783031494031

The ventricular tachyarrhythmia is an important cause of sudden cardiac death, impacting economic, social, and health systems. Microvolt T-wave alternans (MTWA) represent transmural gradient alternation in phase-3 ventricular action potential duration, leading to T-wave amplitude shortening in every other beat. The T-peak T-end interval (TpTe) represents the terminal ventricular repolarization duration and is explained by differences in phase-3 repolarization times from ventricular epicardial to endocardial fibers. Whether TpTe alternation occurs in patients with MTWA is unknown. This work investigated whether terminal ventricular repolarization duration alternation is present in MTWA patients. Seven 12-lead ECG records from Physionet T-wave Alternans Database were analyzed. The TpTe alternans was assessed in even and odds beats, in a series of 128 consecutive beats. In even and odd beats, TpTe intervals were ensembled and averaged, and the magnitude of TpTe alternans was defined as the difference between averages (ΔTpTe). The MTWA was quantified by the difference between the average peak of the T-wave in even and odd beats. ΔTpTe and MTWA were compared by Pearson’s coefficient. Even and odd beats on TpTe alternans and MTWA were compared with non-paired Student t-tests. ΔTpTe positively correlated with MTWA (r = 0.5;p © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.

关键词： Electrocardiograms

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Prototyping a Flowmeter for a Continuous Positive Airway Pressure device 9th

Prototyping a Flowmeter for a Continuous Positive Airway ...

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9th Latin American Congress on Biomedical engineering, CLAIB 2022 and 28th Brazilian Congress on Biomedical engineering, CBEB 2022

作者： Motta-Ribeiro, Gabriel C. Giannella-Neto, Antonio Programa Doutor Empreendedor Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro Rio de Janeiro Brazil Biomedical Engineering Program Universidade Federal do Rio de Janeiro Rio de Janeiro Brazil

ISBN: (纸本)9783031494062

Continuous positive airway pressure (CPAP) is an effective therapy for obstructive sleep apnea. Although the controlled variable in CPAP devices is pressure, flow measurement can supplement monitoring of therapy effectiveness. Here, we describe desired sensor characteristics, application constraints and a theoretical framework for designing a differential pressure flowmeter for a CPAP device. Our aim is to validate this framework through experimental verification of the permanent pressure loss and flow-pressure curve of a 3D-printed prototype. Pressure at patient interface was less than 5% lower than that measured before the restrictive element, despite pressure drop in such element being always above that threshold. The predicted quadratic flow-pressure relationship was achieved with a 97% approximation. These findings indicate that the type of restrictive element chosen for the prototype, a Venturi tube, is suitable for the application, and the used framework is adequate for sensor design. However, refinements to the current geometry are needed to adjust flow sensibility and the fitting to other CPAP device’s components. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Flowmeters

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Supporting the Automated Generation of Acceptance Tests of Process-Aware Information systems 19

Supporting the Automated Generation of Acceptance Tests of P...

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19th International Conference on Web Information systems and Technologies, WEBIST 2023

作者： Paiva, Tales M. Oliveira, Toacy C. Pillat, Raquel M. Alencar, Paulo S.C. Computer and Systems Engineering Program Universidade Federal do Rio de Janeiro Rio de Janeiro Brazil Software Engineering Program Universidade Federal do Pampa Alegrete Brazil Cheriton School of Computer Science University of Waterloo Waterloo Canada

ISBN: (纸本)9789897586729

Software quality assurance is a crucial process that ensures software products meet specified requirements and quality standards. Achieving an exhaustive test coverage is essential for quality assurance, particularly in complex and dynamic Process-Aware Information systems (PAIS) built upon the Business Process Model and Notation (BPMN). Manual testing in such systems is challenging due to many execution paths, dependencies, and external interfaces. This paper proposes a model-based testing strategy that uses BPMN models and build specifications as input to generate a Robotic Process Automation (RPA) script that automates a comprehensive User Acceptance Test procedure. Leveraging on Robotic Process Automation (RPA) to automate user interactions allows for reducing the need for testers to manually input PAIS-related information when handling user forms. We also present a Case Study to demonstrate the feasibility of our approach. Copyright © 2023 by SCITEPRESS - Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

关键词： Acceptance tests

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Baseline Drifting Correction for Automated MTWA Measurements 50

Baseline Drifting Correction for Automated MTWA Measurements

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50th computing in Cardiology, CinC 2023

作者： Winkert, T. Benchimol-Barbosal, P.R. Nadal, J. Coppe Institute Universidade Federal Do Rio de Janeiro Biomedical Engineering Program Rio de Janeiro Brazil Universidade Do Estado Do Rio de Janeiro Hospital Universitário Pedro Ernesto Rio de Janeiro Brazil

ISBN: (纸本)9798350382525

To reduce the incidence of sudden cardiac death (SCD), risk stratification markers have a relevant role. Microvolt T-wave alternans (MTWA) is a marker of SCD risk, defined as T-wave amplitude variation in the ECG. Usually, MTWA tests are carried out in noisy environments when interferences are expected. Baseline drifting correction methods may distort ECG signals, compromising MTWA analysis. This work assesses the impact of baseline drifting removal (BLDR) by two approaches. Signals with controlled baseline drifting, respiratory fluctuations and MTWA were analyzed. The classical BLDR approach (CA) estimates baseline signals using ECG fiducial points. The time-space cancellation approach (TSC) uses only T-wave information to assemble a vector with T-wave amplitudes, calculated by the difference between the maximum T-wave value and its endpoint. The squared coherence between the spectrum from each approach and the spectrum of the ECG without baseline drifting was calculated. At the alternation frequency (0.5 cycles-per-beat) a higher coherence occurred with TSC (0.57) as compared to CA (0.19). Results indicate that CA adds a distortion to the ECG, compromising MTWA. Conversely, the TSC approach preserves MTWA oscillations and has the potential to improve MTWA quantification. © 2023 CinC.

关键词： Electrocardiograms

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Effect of Fine Aggregates and Test Settings on the Self-sensing Response of Cement-Based Composites with Carbon Nanotubes as Conductive Filler

Effect of Fine Aggregates and Test Settings on the Self-sens...

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Nanotechnology in construction, including deep advances in cement chemistry, nanotechnology, artificial intelligence, robotics, concrete technology, and extreme engineering (blast, impact and fire)

作者： dos Santos, T.C. Carísio, P.A. Martins, A.P.S. Paiva, M.D.M. Gomes, F.M.P. Reales, O.A.M. Toledo Filho, R.D. Civil Engineering Program Universidade Federal do Rio de Janeiro Rio de Janeiro Brazil Research Center Eletrobras Furnas Rio de Janeiro Brazil

ISBN: (纸本)9789819933297

Cement-based self-sensing composites with carbon nanotubes (CNT) have attracted attention due to their multifunctional properties and great potential for their application in the smart monitoring of concrete structures. In this study, the self-sensing properties of one paste and three mortars containing 0.50 and 0.75 wt% of CNT, and 1.5 and 1.0 sand/cement ratio were investigated, aiming to evaluate their impact on the piezoresistive response of the composites. The inclusion of sand in the cement paste with CNT led to a reduced gauge factor and a higher electrical noise response. The inert aggregates modified the compressive loading mechanical response of the composites and possibly acted as barriers to electronic mobility, by increasing the CNT conductive paths’ tortuosity or even interrupting them. The mortar containing 0.50% of CNT showed a higher electrical resistivity and, at the same time, greater sensitivity and a more linear self-sensing response than the one with 0.75% CNT, which can be explained by the CNT content being closer to its percolation threshold in the first. In this way, a lower CNT concentration generated a conductive network with a higher capacity to be rearranged under loading, generating significant changes in resistivity, but a higher CNT concentration presented a more stable and conductive network. The results suggested that both the conductive and non-conductive phases affect the detection performance of the composites and, therefore, must be dosed appropriately. Additionally, the test setup modifications positively affected the self-sensing response signal, which is particularly useful to reduce the deleterious effects of the sand additions in the matrix. This overall approach can make the use of self-sensing mortars in structural monitoring a viable option. © 2023, The Author(s).

关键词： Carbon nanotubes

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Aerobiology, post COVID-19, within the emerging Industrial Revolution 5.0 and Society 5.0

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Discover Environment 2025年第1期3卷 1-13页

作者： Macrae, Andrew Lopes, Rafaela Nascimento Allil, Regina Célia da Silva Barros Werneck, Marcelo Programa de Pós-Graduação Em Biotecnologia Vegetal E Bioprocessos Decania CSS Universidade Federal Do Rio de Janeiro Rio de Janeiro Brazil Nanotechnology Engineering Program COPPE Universidade Federal Do Rio de Janeiro Rio de Janeiro Brazil Electrical Engineering Program COPPE Universidade Federal Do Rio de Janeiro Rio de Janeiro Brazil

In this perspective, aerobiology includes microbes, dust, insects, birds and airplanes and the importance of aerial ecosystems in modern society. In 2020, the SARS-CoV-2 virus opened the World’s eyes to the global spread of a virus, the fast global spread caused by people travelling on planes. Billions of people were quarantined, studying moved online and most nonessential work was done at home via the internet. The “stay at home” policy, saved millions of lives, slowed transmission rates but also had a huge negative impact on industrial, economic, and social wellbeing. The pandemic arrived at a time when climate changes were being felt in different ways at different locations globally. A new global sustainable society (Society 5.0) was and is emerging that requires the new industrial revolution (Industry 5.0) to meet societal needs for a safer, healthier and sustainable existence. In 2022, as the pandemic receded, ChatGPT and AlphaFold became publicly available and again the World changed and with them Industry 5.0 arrived for the masses. In this perspective, all life in the air, its interactions, vectors, pathogens, and their impact on a global scale are presented confirming the importance of aerobiology in Society 5.0. Climate change, birds, insects, humans, microbiomes, viromes, airborne soil, dust and role of aviation are presented. Human impacts on aerobiology and vice versa are questioned and discussed. Technological advances to detect and control biological entities in the air are presented. Aerobiology is more than dust, microbes, filters, and detection technologies, it is all life in the air and its links to terrestrial and aquatic biology. This perspective provides a holistic understanding of the air ecosystem and its importance for Society 5.0.

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Output Modifier Adaption based on Gaussian Process: Simultaneous use in Real-Time Optimization and Hammerstein NMPC

Output Modifier Adaption based on Gaussian Process: Simultan...

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2022 European Control Conference, ECC 2022

作者： delou, Pedro A. Curvelo, Rodrigo demuner, Rafael B. de Souza, Maurício B. Secchi, Argimiro Resende Chemical Engineering Program COPPE Universidade Federal Do Rio de Janeiro Rio de Janeiro Brazil Chemical Engineering Department School of Chemistry Universidade Federal Do Rio de Janeiro Rio de Janeiro Brazil

ISBN: (纸本)9783907144077

Real-time optimization (RTO) is a model-based technique to drive process operation towards its optimal con-dition according to an objective function while respecting con-straints. However, whenever the used model presents structural uncertainty, the classic two-step approach fails to find the true optimum condition. Recently, a Modifier Adaption (MA) that uses Gaussian Process (G P) and trust-region concepts has been proposed in order to overcome plant-model mismatch without the need to estimate plant gradients. Based on these premises, this paper extends the methodology by proposing an Output MA (MAy) based on GP. The benefit of using output modifiers is its versatility to be applied in other model-based techniques, since it corrects the model instead of correcting a specific optimization problem. Therefore, we also propose a Hammerstein Nonlinear Model Predictive Control (NMPC) that incorporates the MAy-GP correction term into the predictive controller. The results showed that the performance of MAy-GP is similar to the MA-G P, also showing the ability to drive the plant towards its optimum even in the presence of structural uncertainty. In addition, the proposed NMPC with MAy-GP correction terms was successful, due to the correction in the static term of the Hammerstein model. © 2022 EUCA.

关键词： Gaussian distribution

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The future of AI in government services and global risks: insights from design fictions

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European Journal of Futures Research 2025年第1期13卷 1-29页

作者： Nascimento, Pedro Vitor Marques de Siqueira, Paloma Beatriz Belchior Chrispim, Nathalia Chaves, Ramon Miranda Barbosa, Carlos Eduardo de Souza, Jano Moreira Program of Systems and Computer Engineering Universidade Federal do Rio de Janeiro Rio de Janeiro - RJ Brazil Centro de Análises de Sistemas Navais (CASNAV) – Marinha do Brasil Rio de Janeiro Brazil

The evolution of government services in the context of Artificial Intelligence (AI) and its long-term implications are relevant topics impacting society. developments in this area are surrounded by controversies about what is technically possible, what is feasible in terms of implementation, and what is desirable. In addition, AI’s ambiguous capacity to mitigate and accentuate global risks is remarkable. This research explores AI’s long-term implications through a literature-based design fiction approach, constructing speculative scenarios to examine the potential consequences of AI adoption in governance. The findings highlight three critical dilemmas: (1) AI’s dual role in enhancing efficiency while exacerbating algorithmic bias and surveillance concerns; (2) the potential displacement of human roles in public services, raising questions about accountability and transparency; and (3) the ethical trade-offs in AI-driven decision-making, particularly in law enforcement, healthcare, and education. These scenarios provide insights into the governance challenges AI may introduce, emphasizing the need for ethical guidelines, policy frameworks, and stakeholder engagement. By leveraging speculative narratives, this work contributes to Futures Research on AI in the public sector by offering a creative yet critical lens through which to explore its socio-technical impacts and global risks. These fictional stories will play a fundamental role in stimulating broader dialogues, exploring how AI may influence and redesign the roles played by professionals in government services and the citizens who use them.

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Efficient Methods to Calculate the Reliability of Energy systems with Correlated Renewable Sources 8

Efficient Methods to Calculate the Reliability of Energy Sys...

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8th IEEE International Smart Cities Conference, ISC2 2022

作者： Tebexreni, Ivo S. L. Borges, Carmen L. T. Universidade Federal Do Rio de Janeiro Electrical Engineering Program Brazil

ISBN: (数字)9781665485616

ISBN: (纸本)9781665485616

This article proposes methods that use nonsequential Monte Carlo Simulation (MCS) to calculate reliability indices of power systems with correlated energy sources. The methods apply Principal Correlated Analysis (PCA), covariance matrix, random variable transformation and correlation mapping. Good results were found in cases with linear correlations and high failure state frequency. The processing time was consistent with that observed in classical nonsequential Monte Carlo simulation, and with PCA, it was possible to reduce the dimensionality of the system. © 2022 IEEE.

关键词： Reliability

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