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Impact of different descriptions for diffusion, heat transfer, and capillary pressure on a physics-based proton-exchange membrane fuel cell model

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International Journal of Hydrogen Energy 2025年 133卷 386-401页

作者： Carneiro, Leonardo F. Costa Junior, Esly F. de P. Andrade, Samuel T. Matencio, Tulio Postgraduate Program in Chemical Engineering PPGEQ-UFMG Brazil Postgraduate Program in Mechanical Engineering PPGMEC-UFMG Brazil Department of Chemistry DEQ/ICEX-UFMG UFMG Brazil

A physics-based, two-phase, and non-isothermal proton-exchange membrane fuel cell model is developed and used to evaluate the impact of three common modeling assumptions concerning mass and heat transport in a single-cell system. Firstly, using Fick's law to describe the diffusive transport caused significant differences in the concentration profiles when compared to the Stefan-Maxwell equation, resulting in considerable deviations in the polarization curve. Moreover, the description of thermal effects is found to be crucial to obtaining accurate water molar fraction profiles for the cathode, even when heat removal is effective. Finally, while the impact related to the capillary pressure description in the polarization curve is insignificant when ohmic losses dominate, as they considerably affect the liquid water and oxygen profiles, they may be crucial to obtain precise values at high current densities when water removal is less efficient. These results should provide valuable insights for the development of better models. © 2025 Hydrogen Energy Publications LLC

关键词： Maxwell equations

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Enhanced Performance of a Graphene-Doped Silicon Sensor Incorporating a 2-D Photonic Crystal Resonator for Terahertz Light Transmission

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IEEE Sensors Journal 2025年第10期25卷 16905-16912页

作者： Tavares, Simone C. C. Barros de Sousa, Fabio Dos Reis Silva, Alan Costa, Marcos B. C. Federal University of Pará Department of the Postgraduate Program in Electrical Engineering Belém66075110 Brazil Federal University of Southern and Southeastern Pará Department of the Postgraduate Program in Electrical Engineering Marabá68507590 Brazil Federal University of Para College of Materials Engineering Department of the Postgraduate Program in Electrical Engineering Belem66075110 Brazil

This study presents the design of a graphene-doped silicon sensor that incorporates a 2-D photonic crystal (2D-PhC) nanocavity resonator integrated into a waveguide. The selection of graphene was predicated on its exceptional optical properties. Defects were introduced into the silicon substrate, and the central holes of the resonator were optimized. The graphene component was then embedded within these central holes in the silicon substrate. Through simulations, the influence of hole dimensions, designed based on wavelength and amplitude, on the transmission of light at the desired frequency was investigated, enabling the determination of the optimal hole size for this application. The results obtained from these simulations indicate that the dimensions of the cavity holes, when combined with graphene doping, significantly enhance the sensor’s birefringence. This is a characteristic that cannot be achieved with silicon alone. The incorporation of graphene as a waveguide has been found to be beneficial for the sensor’s overall performance. © 2001-2012 IEEE.

关键词： Silicon sensors

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Micro-electrode array (MEA) electrophysiological signal analysis by descriptive stochastic tests of the probability density structure

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Research on Biomedical engineering 2025年第2期41卷 1-13页

作者： Faria, Vinícius Naves Rezende Ramos, Marina Abadia Martinoia, Sérgio Destro-Filho, João-Batista Postgraduate Program in Electrical Engineering Universidade Federal de MG Uberlândia Brazil Postgraduate Program in Biomedical Sciences Universidade Federal de MG Uberlândia Brazil Division of Informatics Bioengineering Robotics and System Engineering Università Degli Studi Di Genova Genova Italy

Purpose: The primary objective of this study is to present, analyze, and quantitatively characterize the electrical signals obtained from neuronal cultures coupled to micro-electrode arrays (MEAs). Special attention is given to the temporal evolution of electrical activity across distinct geometric regions of the MEA devices. Methods: The proposed methodology involves signal acquisition, classical analysis based on spike and burst detection, and, critically, the characterization of the probability density structure of the signals. This is achieved through the quantification of Gaussianity—expressed as the percentage of segments non-Gaussian (PSNG)—and stationarity— expressed as the percentage of segments non-stationary (PSNE). Results: Initial analyses showed that first-order power spectral density quantifiers lacked the statistical robustness required to effectively describe the complex components of MEA signals. In contrast, PSNG and PSNE demonstrated strong potential in capturing the different stages of neuronal culture development. Cluster analysis further supported the discriminative capacity of these quantifiers. Conclusion: The phase corresponding to decreased neuronal activity and onset of cell death—a biologically critical stage—exhibited the strongest correlation among the studied variables. These results suggest a discernible biological organization and highlight the relevance of PSNG and PSNE as promising tools for assessing neuronal culture dynamics. © The Author(s), under exclusive licence to The Brazilian Society of Biomedical engineering 2025.

关键词： Cell death

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The influence of plastic waste on the properties of lime-based mortars

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Frontiers of Structural and Civil engineering 2025年第3期19卷 477-487页

作者： Vasiliki PACHTA Angeliki-Christina VEDINOGLOU Sofia FLEVARAKI Laboratory of Building Materials School of Civil EngineeringAristotle University of ThessalonikiThessaloniki 54124Greece Interdepartmental Program of Postgraduate Studies‘Protection Conservation and Restoration of Cultural Monuments’ Aristotle University of ThessalonikiThessaloniki 54124Greece

The increasing consumption of plastics, and the threat of environmental impact of their disposal, renders the management of their waste of interest. In the present study, an effort has been made to investigate the influence of waste polyvinyl chloride (PVC) and polypropylene (PP) of various origin in lime-based mortars, applied in the restoration of traditional structures. Nine mortar compositions (based on lime and natural pozzolan) were designed, manufactured and tested, in which natural aggregates were partially substituted by waste plastics (in proportions of 12.5% and 25% v/v of aggregates). According to the research results, shrinkage deformations were reduced in the short term in all modified compositions, porosity showed slight changes, while apparent specific gravity and capillary absorption index were decreased. Mechanical properties were enhanced in the case of the PVC and the lower PP flakes addition (12.5% v/v), while compressive strength was reduced around 5%–25% in the higher proportion (25% v/v). Generally, it could be asserted that the 12.5% v/v proportion of waste plastics offered benefit, and in particular PVC addition was beneficial in terms of physico-mechanical properties, rendering the exploitation of plastic waste in lime-based systems feasible.

关键词： plastic waste lime mortars pozzolan polypropylene polyvinyl chloride

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The main contributions of digitalisation to servitisation

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International Journal of Manufacturing Technology and Management 2025年第3-5期39卷 358-389页

作者： Fronteli, Márcio Henrique Paladini, Edson Pacheco Gaspar Santa Catarina89111-009 Brazil Postgraduate Program in Production Engineering Federal University of Santa Catarina Carvoeira Florianópolis Santa Catarina88040-535 Brazil

Digital servitisation has aroused the interest of many researchers and managers. IoT, big data, and cloud computing are the most prominent technologies. This study sought to investigate the impact of other digital technologies (DTechs) on servitisation. This research is based on an exploratory-qualitative approach covering 146 published articles selected from the Scopus and Web of Science databases. We grouped the digital technologies that impacted servitisation positively. Our results were synthesised into four categories. These procedures allowed for building a framework that shows the contribution potential of digitisation as a success factor of servitisation, as well as competitive opportunities based on the combination of DTs. Digitisation is confirmed as the main driver for the development of digital-servitisation based business models. Our results aim to contribute to the industry in terms of establishing innovation strategies for business models. Copyright © 2025 Inderscience Enterprises Ltd.

关键词： Dynamic random access storage

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Application of the MPSI-CoCoSo Method to Rank OECD Member Countries Towards the Energy Transition

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Computational Economics 2025年 1-30页

作者： Wittig Vianna, Vinicius dos Santos, Marcos Francisco Simões Gomes, Carlos Lauro, Adriano Postgraduate Program in Maritime Studies Naval War College Rio de Janeiro Brazil Industrial Engineering Department Fluminense Federal University Rio de Janeiro Brazil

This study develops a hybrid ranking methodology regarding efforts towards the renewable energy transition among the Organisation for Economic Co-operation and Development (OECD) member countries. The combination of the Modified Preference Selection Index (MPSI) method with the Combined Compromise Solution (CoCoSo) method allows, in two stages, the weight calculation of the chosen criteria and the ranking of the countries according to the selected data, which intends to represent the multidimensional energy transition problem. The main findings are (i) the positioning of nations in the top tier based on their substantial endeavors to adopt renewable energy sources, particularly those with reduced reliance on fossil fuels and low greenhouse gas emissions, combined with high investments in technologies based in sustainable sources, and (ii), the classification, at the opposite end, of the countries in which such efforts could not be evidenced, which shows, through multiple hypotheses, an incipient journey towards the energy transition. The implications for theory and practice can be evidenced by the contribution to establishing a standardized benchmark among OECD members, supporting the map of well-implemented strategies, the development of improved public policies and justifying specific international agreements. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.

关键词： Fossil fuels Greenhouse gas emissions Multi-criteria analysis Renewable energies

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Analysis and Control of Ball Displacement in Air Levitation Experiment by Using a Disturbance Rejection-Based Technique

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IEEE Access 2025年 13卷 71530-71550页

作者： Zachi, Alessandro R.L. Gouvêa, Josiel A. Correia, Carlos A.M. Pinto, Milena F. Petraglia, Mariane R. Haddad, Diego B. Andrade, Fabio A.A. Rio de Janeiro20271-204 Brazil Rio de Janeiro20271-204 Brazil Program of Electrical Engineering Coordination of Postgraduate and Research in Engineering Federal University of Rio de Janeiro Rio de Janeiro21941-617 Brazil Borre3184 Norway

This work describes the application of a disturbance rejection technique for controlling ball position in an air levitation experiment. The prototype consists of a light-mass ball that moves freely inside a vertical transparent cylindrical tube. The control objective is to force the ball position to track a desired vertical trajectory by defining a voltage control law for an air blower actuator. The system’s nonlinear mathematical model is presented and discussed. To deal with model uncertainties, nonlinearities and non measurable states, the design and the analysis of a Modified-Plant Active Disturbance Rejection Controller (MP-ADRC) are performed. ADRC-based controllers have been studied for decades, and their main characteristics are the use of an extended state observer (ESO) to estimate the non-measurable signals of the plant and a state-feedback control law in standard form fed by that observer. The key advantage of the adopted variant MP-ADRC, which contrasts with the basic methodology, is that it only requires knowledge of the sign (+/−) of plant’s control coefficient, rather than its exact value. This improves the well-known robustness property of the method, allowing its application to a general class of dynamical systems with uncertain parameters. By adopting and using such a control methodology, the resulting closed-loop scheme exhibits several advantageous characteristics: (i) it is robust to parametric uncertainties;(ii) it can compensate for external disturbances and unmodeled dynamics;(iii) it can deal with plants with slowly time-varying control coefficient;(iv) even for nonlinear plants, mathematical analysis using Laplace transform can always be performed. This work also presents and discusses simulation and experimental results obtained with the proposed control strategy applied to a real air levitation prototype. ©2013 The Authors.

关键词： Disturbance rejection

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Production and characterization of polymeric nanocomposite foams based on starch and cellulose nanofibers from oil palm mesocarp fiber

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Applied Nanoscience (Switzerland) 2025年第2期15卷 1-11页

作者： Souza, Mariana Costa Gonçalves, Ana Paula Bispo da Silva Oliveira, Emanoel Igor dos Santos, Juscivaldo Passos Lazzari, Lídia Kunz Zattera, Ademir José José, Nadia Mamede Chemical Engineering Graduate Program Polytechnic School Federal University of Bahia Bahia Salvador Brazil Department of Education Federal Institute of Education Science and Technology Feira de Santana Bahia Brazil Postgraduate Program in Process Engineering and Technologies University of Caxias Do Sul Rio Grande Do Sul Caxias Do Sul Brazil

The demand for sustainable and eco-friendly materials has promoted studies over the years to explore different polymeric materials that meet requirements such as biodegradability and sustainability. In this context, biopolymer materials based on cellulose nanoparticles and starch from different botanical sources have been investigated, aiming to achieve satisfactory performance. The present study aims to develop and characterize cassava starch foams based on density, scanning electron microscopy (SEM), and three-point flexure tests, and to evaluate the effect of cellulose nanofibers obtained from palm mesocarp fibers using the ultrafine friction grinding method after different processing times, characterized by X-ray diffractometry (XRD), microscopy, and chemical composition, as a reinforcing filler. The chemical composition and scanning electron microscopy revealed the effectiveness of the cellulose isolation process, with the analysis of the chemical composition revealing a cellulose content of 55.70% in the fibers after pulping and bleaching, in addition to changes in the visual characteristics of the material after the process aimed at isolating the cellulose. After grinding, XRD showed an increase in crystallinity (76.1% at the maximum grinding time), along with typical microscopy images of cellulose nanofibers. The analysis of the obtained nanocomposites provided insights into the role of these nanostructures in the thermo-expanded starch matrix, indicating that the nanofibers promoted changes such as an increase in mechanical properties and crystallinity, which contributed to improving overall mechanical performance. A 67.48% increase in flexural strength was achieved for the formulation with cellulose nanofibers that underwent 150 min of grinding, without causing major variations in density. © King Abdulaziz City for Science and Technology 2025.

关键词： Starch

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A Systematic Evaluation of Clustering Algorithms Against Expert-Derived Clustering

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Operations Research Forum 2025年第2期6卷 1-24页

作者： Mikrou, Ioannis Sapidis, Nickolas S. Department of Mechanical Engineering University of Western Macedonia ZEP Kozani 50100 Greece Postgraduate Masters Program “Quality Management and Technology” Hellenic Open University Par. Aristotelous 18 Patras 26335 Greece

Clustering algorithms have long sought to replicate human expertise in data clustering. This research utilizes six mechatronic products and a team of domain experts to assess how closely the results of six clustering algorithms align with expert-generated outcomes. This comparison of clustering results includes validation indices, the analysis of component migrations between the generated clusters, and optical inspection. The mechatronic products were selected for their complex nature, which provides a challenging context for the clustering analysis. The algorithms used in this research are Ward’s method (WARD), partitioning around medoids (PAM), K-means (K-MEANS), divisive analysis (DIANA), density-based spatial clustering of applications with noise (DBSCAN), and clustering by fast search and find of density peaks (DPC), and the validation indices employed to evaluate the clustering results are the silhouette coefficient (SC) and the composed density between and within clusters (CDbw). © The Author(s) 2025.

关键词： Clustering performance DSM models Human expert benchmarks Machine learning Mechatronics

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Sustainable optimization of acetone-water distillation: Balancing cost, flexibility, and environmental impact with heat pump integration

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Chemical engineering Research and Design 2025年 218卷 361-375页

作者： Wu, Ssu-Hsien Lin, Chih-Yao Silviana, S. Adi, Vincentius Surya Kurnia Department of Chemical Engineering College of Engineering National Chung Hsing University Taichung40227 Taiwan Department of Chemical and Materials Engineering College of Engineering Tunghai University Taichung407224 Taiwan Department of Chemical Engineering Faculty of Engineering Universitas Diponegoro Tembalang Semarang50275 Indonesia Master Program of Energy School of Postgraduate Studies Universitas Diponegoro Pleburan Semarang50241 Indonesia

Acetone is extensively used in industrial applications due to its high polarity and miscibility. However, its separation from water becomes increasingly energy-intensive at high concentrations beyond a mass fraction of 0.8, where the relative volatility significantly decreases. This study introduces an innovative heat pump-assisted distillation system (HPADS) coupled with a novel bi-objective optimization framework that simultaneously considers economic efficiency and operational flexibility—an aspect often neglected in prior studies. Leveraging the integration of Aspen Plus® and MATLAB®, the proposed system enables automated, parallelized optimization using a genetic algorithm (GA), with a custom objective function that includes both total annual cost (TAC) and a flexibility index (FI). This approach ensures not only minimum cost but also robust performance under feed disturbances. The optimized HPADS achieves up to 16.25 % flexibility in feed variation tolerance, reduces operating costs by 57.78 %, and cuts annual CO₂ emissions by 3.83 × 10⁶ kg compared to conventional systems. The results demonstrate that embedding flexibility into process design enhances both sustainability and resilience, positioning the proposed HPADS framework as a significant advancement toward practical, energy-efficient, and disturbance-tolerant distillation systems. © 2025 Institution of Chemical Engineers

关键词： Distillation

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