Istituto Nazionale di Ricerca Metrologica
METRICA Archivio istituzionale della ricerca - INRIMNot a member yet
8322 research outputs found
Sort by
Modeling of daytime radiative cooling enhanced vapor-compression refrigeration systems
No full textDaytime Radiative Cooling (DRC) technologies use surfaces with tailored spectral properties to dissipate heat through the atmospheric transparency window toward outer space, even under direct sunlight. This study develops a transient simulation model to assess the energy-saving potential of integrating DRC materials into a typical vapor-compression refrigeration system (VCRS) for a residential building. The system employs flat-plate radiative panels coated with DRC material to cool a heat transfer fluid in a closed-loop circuit. This cooled liquid then reduces the temperature of the VCRS refrigerant via a supplementary heat exchanger located downstream of the air-cooled condenser, thereby enhancing the seasonal energy efficiency ratio (SEER) and reducing energy consumption. A parametric analysis examines key parameters, including radiative panel area, subcooler size, and panel fluid flow rate. The system is simulated for Las Vegas, Riyadh, Madrid, and Turin using experimental hourly meteorological data to capture the spectrally varying effects of atmospheric radiation. Moreover, the performance of different DRC materials is evaluated by comparing spectral selective and broadband emitters with two commercial options. Results show significant energy savings in hot, arid climates—46.1 kWh m−2 in Riyadh and 37.5 kWh m−2 DRC in Las Vegas—and up to a 10.1 % reduction in electric energy consumption
Data of electrical signalling in tomato for the detection of powdery mildew
No full textHere we present the data used to analyse the electrical signals acquired in tomato plants grown in peat and water substrates that were infected with the fungal pathogen Oidium neolycopersici, the causative agent of powdery mildew, along with the statistical analyses used to detect the differences in electrical responses between healthy and infected plants, as reported in [1]. Voltages were acquired periodically, scanning repeatedly in sequence all lines in use, with acquisitions separated from each other by approximately 200 s. They were recorded by means of a dedicated custom Python program run by a Raspberry Pi board. Data are made available here both in raw text form, covering the whole monitoring period (15 days, including values for inoculated and healthy plants), and as Excel files with calculations for statistical analyses [2]. More details about the experimental background can be found in the related research article
Optimization of wavelength-selective metasurfaces for thermal management of photovoltaic modules
No full textPassive radiative cooling materials emit heat to space, reducing solar cell temperatures. We optimize numerically a polymer pattern coating to enhance heat dissipation, improving on thermal management and efficiency while rejecting sub-bandgap solar radiation
Experimental determination of sensitivity coefficients of some influence parameters in Rockwell B, C, 15N, 30N and 45N
No full textThe impact of key variables on hardness measurements, including indenter velocity, geometry, dwell times, forces, and temperature, has been extensively studied in recent decades. The recent adoption of international Rockwell hardness scale definitions has intensified this interest. While these definitions and relevant standards consider parameter ranges, the Rockwell hardness equation lacks explicit incorporation of these variables, requiring an empirical determination of their sensitivity coefficients. This study focuses on the determination of sensitivity coefficients associated with two main influential parameters − the velocity of the final load application and the time interval for the force variation from the preliminary force value to the total force value − across Rockwell B, C, 45N, 30N, and 15N hardness scales at various hardness levels, using a Monte Carlo method and multiple linear regression. The results align with findings in existing literature, enhancing the robustness and reliability of the study
Safety Assessment of Microwave Breast Imaging: Heating Analysis on Digital Breast Phantoms
Full text linkFeatured Application: Devices for microwave mammography could soon appear in clinical practice. The significant result of this study is the demonstration of the high safety of a microwave imaging system in terms of heating induced in biological tissues. The impact of breast cancer on public health is serious, and due to risk/benefit assessment, screening programs are usually restricted to women older than 49 years. Microwave imaging devices offer advantages such as non-ionizing radiation, low cost, and the ability to distinguish between cancerous and healthy tissues due to their electrical properties. Ensuring the safety of this technology is vital for its potential clinical application. To estimate the temperature increase in breast tissues from a microwave imaging scanner, cases of healthy, benign, and malignant breast tissues were analyzed using three digital models and adding two healthy breast models with varying densities. Virtual experiments were conducted using the Sim4Life software (version 7.2) with a system consisting of a horn antenna in transmission and a Vivaldi antenna in reception. Temperature increases were estimated based on the Specific Absorption Rate distributions computed for different configurations and frequencies. The highest temperature increase obtained in this analysis is lower than 60 μK in fibroglandular tissue or skin, depending on the frequency and breast density. The presence of a receiving antenna acting as a scatterer modifies the temperature increase, which is almost negligible. Microwave examination can be performed without harmful thermal effects due to electromagnetic field exposure
Characterization of plant pathogenic bacteria at subspecies level using a dielectrophoresis device combined with Raman spectroscopy
No full textTimely diagnosis of plant diseases and correct identification of etiological agents are fundamental to guarantee quality and quantity of agricultural products and food. Phytopathogenic bacteria induce devastating effects on crops. Their diagnosis and identification, mainly based on serological and molecular tools, are time consuming and expensive processes and require trained personnel. Among the innovative methods providing rapid, accurate, and reliable diagnosis at reduced costs, Raman spectroscopy (RS) is gathering considerable attention. RS provides a direct and non-destructive platform to gather information on the chemical and biochemical components of a sample, such as microorganism cultures, revealing their biological role. Due to the weak signals of bacterial cells in RS, a dielectrophoresis (DEP) approach was adopted to amplify the bacterial signals. Using Raman-DEP analysis, a dataset of spectra from different harmful phytopathogenic bacteria belonging to the genera Pseudomonas spp., Xanthomonas spp., and Erwinia spp. was obtained. Machine learning approaches were employed to discriminate isolates at the genus, species, and unprecedentedly at the pathovar level, reaching accuracies, precisions, recalls, and F1 scores of 94–100%. This approach offers important advancements in the non-destructive and rapid classification of microorganisms and is suitable to be readily extended to environmental and food diagnostics
Influence of cobalt redox couple concentration on the characteristics of liquid and quasi-solid electrolytes and on the photovoltaic parameters of dye-sensitised solar cells
No full textDye-sensitised solar cell (DSSC) is a next-generation solar energy conversion device. The electrolyte, which is one of the key components of a DSSC, greatly affects its short-circuit current density (Jsc) and open-circuit voltage (Voc) and hence, its overall performance. In this work, bis(trifluoromethane)sulfonimide (TFSI) cobalt complex was used for the first time as redox couple in DSSC, and an effort was carried out to study the effects of the varying concentration of cobalt complex redox ions on the characteristics of the prepared liquid electrolytes (LEs) and quasi-solid electrolytes (QEs), and on the photovoltaic parameters of DSSCs. Specifically, the electrolyte characteristics include the viscosity and electrical conductivity, while the photovoltaic parameters of DSSCs include Jsc, Voc, fill factor (FF) and power conversion efficiency (PCE). The viscosity of electrolytes was found to increase with increasing molar concentrations and then further increased with the addition of polyethylene oxide (PEO); the highest viscosity of 2.49 cP was obtained at 44 rpm for QE-50. The highest conductivity measured by electrochemical impedance spectroscopy was 83 mS cm− 1 for LE-50. Finally, zinc oxide-based DSSCs with platinum counter electrodes were fabricated for current-voltage measurements. Among the synthesised electrolytes, QE-35-based DSSC showed a better combination of Jsc and Voc, resulting in a PCE of 0.48%
Surface slope measurement of steep silicon V-grooves using high NA Linnik interferometry
No full textOptical topography measurements are of high interest in a lot of industrial and academic fields. One of the most common associated measurement methods is coherence scanning interferometry, but even though it provides sub-nanometer axial resolution, its lateral resolution is diffraction limited. Not only the feature size is a limiting factor for optical measurements, but also steep surface slopes may lead to problems, since the acceptance angle of the objective lens limits the maximum surface slope angles that can be measured. Here we use a Linnik-type interferometer with objective lenses of numerical apertures of 0.95 in order to maximize the measurable surface slope angle. We demonstrate that silicon V-groove structures with a slope angle of 54.74° can be measured. We compare the directly measured surface slope angle with an angle calculated from light that is reflected two times by the V-grooves. To verify our measurement we compare the measurement results to rigorous FEM simulations
Sky cooling-driven radiant-capacitive hydronic system for all-day building cooling
No full textDaytime Radiative Cooling (DRC) surfaces enable heat rejection by emitting infrared radiation to the sky while reflecting solar radiation, allowing for sub-ambient cooling even under direct sunlight. This study develops and validates a transient numerical model of a DRC-based hydronic cooling system designed for building applications. The system integrates ceiling-mounted radiant capacitive modules (RCMs) with outdoor sky radiators (SRs) that dissipate indoor heat to outer space, cooling down a heat transfer fluid. The model is validated using experimental data from a full-scale demonstrator using a commercially available DRC emitter and is employed to assess system performance for a single-family building during a typical cooling season in the cities of Madrid and Rome. Compared to a system limited to nighttime radiative cooling, the DRC-enhanced setup delivers seasonal energy performance improvements of +6.2 % with a commercial DRC material and +10.3 % with an ideal broadband emitter. The study further investigates the effects of varying the surface area ratio between SRs and RCMs and alternative SR placements (rooftop vs. external surface). A fully passive building model with a DRC roof is also considered for comparison. Results show that the DRC-hydronic system can consistently maintain indoor thermal comfort throughout the cooling season, achieving seasonal energy efficiency ratios (SEER) up to 35 times higher than those of conventional air conditioning systems for the case studies analyzed, although the two systems differ in controllability and application scenarios. These findings highlight the strong potential of DRC-integrated hydronic cooling as a highly energy-efficient and sustainable alternative for the climate control of residential buildings
