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Experimental study of sensing performance using hyperbolic mode resonances
No full textPublisher Copyright: © 2024 Elsevier LtdSurface plasmon resonance (SPR) and lossy mode resonance (LMR) are prominent sensing mechanisms utilized across various fields. The Kretschmann configuration is commonly employed for SPR, while LMR is favored in planar waveguides or optical fibers due to high incidence angles. Recently, hyperbolic mode resonance (HMR) has emerged as a hybrid approach, combining metallic and dielectric thin films. This study explores the impact of incidence angle on HMR using the Kretschmann configuration. Four samples with varying gold (Au) and tin dioxide (SnO2) layer thicknesses were fabricated and characterized using Atomic Force Microscopy (AFM). Experimental setups employed the Kretschmann configuration for reflectance spectrum analysis. Results indicate enhanced sensitivity and figure of merit (FoM) with an additional SnO2 layer compared to the case without SnO2. Particularly with a 36 nm Au thickness the sensitivity doubles and the FoM improves by 16 %. Numerical simulations validate these findings, confirming the optimized performance of HMR for specific layer thicknesses and incidence angles.Peer reviewe
Extended detailed balance modeling toward solar cells with cement-based radiative coolers
No full textPublisher Copyright: © 2023 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd.Reducing the temperature of a solar cell increases its efficiency and lifetime. This can be achieved by radiative cooling, a passive and simple method relying on materials that dump heat into outer space by thermal emission within the atmosphere transparency window between 8 and (Formula presented.). As most radiative coolers are expensive or possibly UV unstable, we have recently proposed cement-based solutions as a robust and cost-effective alternative. However, the assessment model used describes the cell in the radiative limit and with perfect thermal coupling to the cooler, in line with the literature. In this work, we lift these two approximations, by incorporating Auger and Shockley–Read–Hall nonradiative recombination and a finite heat transfer coefficient at the cell/cooler interface, to obtain a thermal description of the cell/cooler stack closer to reality, while preserving the universality and transparency of the detailed-balance approach. We use this model to demonstrate that the cell performance gains provided by a radiative cooler are underestimated in the radiative limit and are hence more prominent in devices with stronger nonradiative recombination. Furthermore, we quantify the relation between cell temperature and heat transfer coefficient at the cell/cooler interface and show how this can be used to define design requirements. The extended model developed, and the resulting observations provide important guidelines toward the practical realization of novel radiative coolers for solar cells, including cement-based ones.This research was supported by the European Union's Horizon 2020 Research and Innovation Program under grant agreement no. 964450. Funding informationPeer reviewe
Big Data Analysis for Industrial Activity Recognition Using Attention-Inspired Sequential Temporal Convolution Network
No full textPublisher Copyright: © 2015 IEEE.Deep-learning-based human activity recognition (HAR) methods have significantly transformed a wide range of domains over recent years. However, the adoption of Big Data techniques in industrial applications remains challenging due to issues such as generalized weight optimization, diverse viewpoints, and the complex spatiotemporal features of videos. To address these challenges, this work presents an industrial HAR framework consisting of two main phases. First, a squeeze bottleneck attention block (SBAB) is introduced to enhance the learning capabilities of the backbone model for contextual learning, which allows for the selection and refinement of an optimal feature vector. In the second phase, we propose an effective sequential temporal convolutional network (STCN), which is designed in parallel fashion to mitigate the issues of exploding and vanishing gradients associated with sequence learning. The high-dimensional spatiotemporal feature vectors from the STCN undergo further refinement through our proposed SBAB in a sequential manner, to optimize the features for HAR and enhance the overall performance. The efficacy of the proposed framework is validated through extensive experiments on six datasets, including data from industrial and general activities.Peer reviewe
Photonic Chip Breath Analyzer
No full textPublisher Copyright: © The Author(s) 2025.This work introduces a novel single-package optical sensing device for multiple gas sensing, which is suitable for breath analysis applications. It is fabricated on a coverslip substrate via a sputtering technique and uses a planar waveguide configuration with lateral incidence of light. It features three sequentially ordered strips of different materials, which serve to increase the multivariate nature of the response of the device to different gases. For the proof-of-concept, the selected materials are indium tin oxide (ITO), tin oxide (SnO2), and chromium oxide III (Cr2O3), while the selected gases are nitric oxide (NO), acetylene (C2H2), and ammonia (NH3). The sensing mechanism is based on the hyperbolic mode resonance (HMR) effect, with the first-order resonance obtained for each strip located in the near infrared region. The multivariate response of the resonances and the correlation with the concentration of each gas allow training a machine learning (ML) model based on a nonlinear autoregressive neural network, enabling the accurate prediction of the concentration of each gas. The obtained limit of detection for all the gases was in the order of a few parts per billion. This innovative approach coined as the multivariate optical resonances spectroscopy demonstrates the potential of HMR-based optical sensors in combination with ML techniques for ultra-sensitive multi-gas detection applications using a single device.Peer reviewe
Low-dose computed tomography perceptual image quality assessment
No full textPublisher Copyright: © 2024In computed tomography (CT) imaging, optimizing the balance between radiation dose and image quality is crucial due to the potentially harmful effects of radiation on patients. Although subjective assessments by radiologists are considered the gold standard in medical imaging, these evaluations can be time-consuming and costly. Thus, objective methods, such as the peak signal-to-noise ratio and structural similarity index measure, are often employed as alternatives. However, these metrics, initially developed for natural images, may not fully encapsulate the radiologists’ assessment process. Consequently, interest in developing deep learning-based image quality assessment (IQA) methods that more closely align with radiologists’ perceptions is growing. A significant barrier to this development has been the absence of open-source datasets and benchmark models specific to CT IQA. Addressing these challenges, we organized the Low-dose Computed Tomography Perceptual Image Quality Assessment Challenge in conjunction with the Medical Image Computing and Computer Assisted Intervention 2023. This event introduced the first open-source CT IQA dataset, consisting of 1,000 CT images of various quality, annotated with radiologists’ assessment scores. As a benchmark, this challenge offers a comprehensive analysis of six submitted methods, providing valuable insight into their performance. This paper presents a summary of these methods and insights. This challenge underscores the potential for developing no-reference IQA methods that could exceed the capabilities of full-reference IQA methods, making a significant contribution to the research community with this novel dataset. The dataset is accessible at https://zenodo.org/records/7833096.Peer reviewe
Impact of Pavement Material Properties on Radiant Heat Exchanges with the Built Environment
Get PDFPublisher Copyright: © 2025 University of Split, FESB.There is a need for developing innovative pavement solutions for urban heat mitigation. This work presents the development of a model and a subsequent parametric study determining the impact of the material properties of pavements (thermal conductivity, heat capacity, solar absorptivity, infrared emissivity) over the surface temperatures of the ground and the boundary temperatures experienced by nearby buildings and people. The model explicitly considers dynamic heat storage effects, wind-dependent convective exchanges with the ambient, and the impact of solar and long-wave radiation exchanges. The parametric study compares the performance of a reference asphalt pavement to modifications (20% reduction) over each of its key material properties. Results indicate that the most relevant parameter is the solar absorptivity, followed by the emissivity. Changes in thermal conductivity or heat capacity have very limited effect. An interesting outcome is that reflective pavements with low solar absorption result in lower surface temperatures in the pavement, yet increased peak temperatures in neighbouring vertical surfaces (+2.5 °C) due to solar reflection and infrared radiative exchanges. In contrast, low-emissivity ground surfaces seem to achieve an opposite effect, increasing heat storage in the ground while reducing peak temperatures of nearby vertical surfaces (-1.2 °C).Peer reviewe
Human-Centric Robotic Solution for Motor and Gearbox Assembly: An Industry 5.0 Pilot Study
Get PDFPublisher Copyright: © 2025 by the authors.The automotive industry is one of the most automatized industries, employing more than one million robots worldwide. Although several steps in car production are completely automated, many steps are still carried out by operators, especially in tasks requiring high dexterity. Additionally, customization and deployability are still pending issues in this industry, where a real collaboration between robots and operators would increase the reconfigurability of the assembly lines. This paper presents an innovative robotic cell focused on the motor and gearbox assembly, including collaborative industrial robots and autonomous mobile manipulators along the different assembly stations. The design also incorporates a human-centered approach, with an enhanced human interface to facilitate the interaction with operators with the complete robotic cell. The proposed approach has been deployed and validated on a real automotive industrial scenario, obtaining promising metrics and results.Peer reviewe
Miniaturization of a colorimetric cellulase activity assay on a microfluidic sensor platform
Get PDFPublisher Copyright: This journal is © The Royal Society of Chemistry, 2025Enzymes are important commercial products with widespread uses as industrial catalysts, processing aids and analytical reagents. Biological activity is the major critical quality attribute monitored during the enzyme production. Assaying the enzyme activity often requires laborious procedures that are challenging to implement on microfluidic chips for facile on-site use in hand-held mobile devices. Here, we show the integration of a colorimetric assay of cellulase activity into a prototype microfluidic sensor platform on cyclic olefin copolymer foil obtained by roll-to-roll processing. The activity assay was based on resorufin dye release from the corresponding β-cellobioside substrate. Low water solubility of the substrate necessitated a concentration co-optimization for substrate and dimethylsulfoxide co-solvent used in the assay, considering that the co-solvent caused substantial activity loss of the enzyme. A flexible, chip-amenable read-out method was developed based on CIELAB colour space image analysis to quantify both dye release for enzyme activity determination and substrate solubilization at the same time. Information on the substrate solubilization kinetics on chip was crucial to establish the activity assay on the microfluidic platform designed to contain the substrate as a spotted array of resorufin β-cellobioside droplets. We compared the assay conducted in the microfluidic chip with that in conventional microwell plate and found that both formats of analytical measurement could be used with the colour-based read-out method. Overall, we demonstrate cellulase activity monitoring on chip based on identification and optimization of critical parameters of microfluidic assay integration. The analytical approach shown for cellulase may be broadly applicable to the assay of enzyme activity.Peer reviewe
Antibacterial Activity of Bis(4-aminopyridinium) Compounds for Their Potential Use as Disinfectants
No full textThe following study presents the initial evaluation (solubility, thermal stability, antibacterial activity, and cytotoxicity) of a series of previously described organic salts, derived from the bis(4-aminopyridinium) cation with different chain lengths, for their potential use as hospital disinfectants. Of the salts studied, those with chain lengths between 2 and 10 carbon atoms (C2-C10) showed high solubility in water, methanol, and DMSO. All salts exhibited high thermal stability, showing a thermal decomposition temperature (T5%) above 330 °C. Antibiotic susceptibility testing of the studied E. coli, S. aureus, and S. typhimurium strains confirmed their resistance to different classes of commonly used clinical antibiotics, validating their selection. During the determination of antibacterial activity, the long-chain salts (C10 and C12) showed the greatest activity, with minimum inhibitory concentrations (MICs) from 31.2 μg/mL to 62.5 μg/mL in all the strains studied. Given the high activity of C10 and C12, their cytotoxicity was assessed in HeLa cells. They exhibited no cytotoxic effects after 12 h and only about 5% cytotoxicity after 24 h. Furthermore, the cell viability assay of the most active and water-soluble salt, C10, showed that this salt can interact with the bacterial cytoplasmic membrane, increasing its permeability in both Gram-positive and Gram-negative bacteria. However, these results cannot rule out the possibility that this salt may have more than one site of action within the bacterial cell.Peer reviewe
Building envelope thermal performance testing dataset (Co-heating, QUB, ISO-9869 U-values) from a retrofitted heritage building (unoccupied dwelling)
Get PDFPublisher Copyright: © 2025 The Author(s).A mobile Monitoring and Control System (MCS) was implemented to conduct several tests aimed at characterizing the thermal envelope of unoccupied dwellings and estimating its Heat Transfer Coefficient (HTC). These tests included U-value Tests (according to ISO 9869), QUB Tests, and Co-Heating Tests. In the Co-Heating Test, the dwelling was heated during different periods using both electric heaters and the installed aerothermal heat pump system. The two studied dwellings are living labs of a heritage building in Vitoria-Gasteiz (Spain), retrofitted in 2019 as part of the European project ENERPAT-SUDOE: Experimentation in the Eco-Renovation of Old Built Heritage . Specific ISO 9869 U-value or Thermal Transmittance Tests were conducted on the building envelope using 37 sensors strategically installed across two dwellings. In an unoccupied dwelling, the QUB Tests and Co-Heating Tests, were also performed. In total, the dataset includes 138 sensors measuring 200 physical variables to perform the test in different periods from October 26, 2019, at 15:53:00 to November 05, 2024, at 23:59:00 at 1-minute resolution.This dataset contributes to advancing the estimation of the Heat Transfer Coefficient (HTC) and the overall heat loss (UA-value) of the thermal envelope in retrofitted buildings, supporting improved energy performance evaluation. Companion dataset: multi-year in-use monitoring from the same building using a fixed MCS (Data in Brief DOI: 10.1016/j.dib.2025.112121).Peer reviewe