Search Results (45)

Portugal’s increasing wildfire frequency has led to home destruction, large areas burned, ecological damage, and economic loss, emphasizing the need for effective fire exposure assessments. This study builds on a Canadian approach to wildfire exposure and evaluates wildfire exposure in the Portuguese municipality of Mafra, using artificial territories (AT) as a proxy for the wildland–urban interface (WUI) and integrates land use land cover (LULC) data with a neighborhood analysis to map exposure at the municipal scale. Fire exposure was assessed for three fire transmission distances: radiant heat (RH, <30 m), short-range spotting (SRS, <100 m), and longer-range spotting (LRS, 100–500 m) using fine resolution (5 m) LULC data. Results revealed that while AT generally exhibited lower exposure (<16% “very high” exposure), adjacent hazardous LULC subtypes significantly increase wildfire hazard, with up to 51% of LULC subtypes classified as “very high exposure”. Field validation confirmed the accuracy of exposure maps, supporting their use in wildfire risk reduction strategies. This cost-effective, scalable approach offers actionable insights for forest and land managers, civil protection agencies, and policymakers, aiding in fuel management prioritization, community preparedness, and the design of evacuation planning. The methodology is adaptable to other fire-prone regions, particularly mediterranean landscapes. Full article

Wood, in the form of cladding or furniture, is often placed in close proximity to heat radiant sources. This research focused on samples, which are Norway spruce (Picea abies L.), Red spruce (Picea rubens Sarg.), cherry (Prunus avium), and oak (Quercus spp.). The aim of this paper was to observe the effect of the distance of the selected wood samples from the radiant heat source on the process of thermal degradation of wood. Additionally, this research aimed to identify significant effects of wood species and sample distance on this process. A hot-plate device, an electric plate heated according to a temperature–time curve, was used as the initiating source. Samples were placed directly on the plate, as well as at two different distances from the plate (12 and 32 mm). During the experiment, the temperature history on the heat-exposed side of the sample, its mass loss, and the formation of a charred layer were monitored. Additionally, the progression of thermal degradation and related effects (smell, smoldering, and charring layer) were visually observed. The highest level of degradation was observed in the spruce sample placed directly on the plate, which started to smolder after 540 s of exposure to radiant heat at 291.2 °C. Full article

This study investigates fire separation distances as essential means of passive fire protection in building design. The focus is on the inner corner configuration of building exterior walls, which represents the worst-case scenario for façade fire spread outside of a building. The inner-corner configuration appears to increase the intensity of the radiative heat flux due to reflection and reradiation of heat. Comprehensive approaches for determining fire separation distances around the various façade geometries can be found, but none of them is focused on detailed descriptions of the unprotected area in an inner corner. A medium-scale scenario was chosen and was experimentally validated with a radiant panel for a better understanding of heat flux spread. This paper compares the experiment with analytical and numerical models. The analytical model is based on the Stefan–Boltzmann law and the calculated configuration factor as per Eurocode 1. The numerical model combines radiative and convective components of the heat flux because convection is non-negligible near the heat source. Experimental data confirm the prediction based on the numerical and analytical model and show agreement. The final increase in heat flux due to the corner configuration investigated at the medium scale reaches up to 29%. Full article

The increased demand for contactless services has facilitated a rapid increase in logistics facilities. There are shorter distances between the shelf racks used in mezzansine racks in such facilities compared to standard racks and can store various items; however, research on fire safety related to this remains insufficient. In this study, we visited four logistics facilities with mezzanine racks and one logistics facility using shelf racks to investigate their fundamental characteristics. Considering the characteristics of logistics facilities that store various combustibles, a fire test was conducted using unit shelf racks with packaging materials, boxes, and expandable polystyrene (EPS). Shelf racks loaded with corrugated fiberboard, cardboard boxes, and EPS exhibited the highest fire risk and were set as combustibles inside the rack. Before the experiment, the radiative heat flux was measured by considering the spacing distances of mezzanine racks observed on-site. The most frequently measured range was 43.7–67.3 kW/m² at 1.0–1.5 m. After beginning the fire experiment, when simulating mezzanine racks with aisle widths of 1.2–2.0 m, fire owing to radiative heat occurred within 5 min in the separated shelf racks. Based on the results, we estimate that the minimum separation distance required to prevent radiant heat-based fires between shelving racks inside a mezzanine is 3.2 m. These findings are expected to be utilized in fire prevention by increasing the understanding of the spread of fire in shelf racks. Full article

In order to meet the high uniformity calibration requirements for scientific-grade, large-size space detectors used in the CHES Extrasolar Planet Exploration Mission, this paper presents the design of a wide dynamic range, high uniformity spectral irradiance source (WHUIS). Utilizing a cascade integrating sphere design, and optimizing the overlapping area radiant flux adjustment structure and illumination light path, we achieve a wide dynamic range and high uniformity irradiance output. We established an irradiance transmission model based on the new assumption and analyzed the influence of factors such as illumination distance, stray light, and non-uniform radiance on the uniformity of irradiance output. The model is then validated by building experimental equipment. The findings show that in a circular area of 40 mm, the irradiance uniformity of our light source system exceeds 99.9%, and constant color temperature is adjustable within six orders of magnitude, consistent with the uniformity level predicted by the model. Full article

Background: This study assesses the effects of the ‘Radiant’ image enhancement technique on fetal nuchal translucency (NT) measurements during first-trimester sonographic exams. Methods: A retrospective analysis of 263 ultrasound images of first-trimester midsagittal sections was conducted. NT measurements were obtained using a semi-automatic tool. Statistical methods were applied to compare NT measurements with and without ‘Radiant’ enhancement. An in vitro setup with predefined line distances provided additional data. Results: Incremental increases in NT measurements were observed with varying levels of ‘Radiant’ application: an average increase of 0.19 mm with ‘Radiant min’, 0.24 mm with ‘Radiant mid’, and 0.30 mm with ‘Radiant max.’ The in vitro results supported these findings, showing consistent effects on line thickness and measurement accuracy, with the smallest mean deviation occurring at the ‘Radiant mid’ setting. Conclusions: ‘Radiant’ image enhancement leads to significant increases in NT measurements. To avoid systematic biases in clinical assessments, it is advisable to disable ‘Radiant’ during NT measurement procedures. Further studies are necessary to corroborate these findings and to consider updates to the NT reference tables based on this technology. Full article

Adherence to fire safety regulations for wood is one of the most important tasks in its use in structural and architectural applications. This article deals with determining the influence of heat flux on the ignition process of spruce (Picea abies L. Karst.) and beech wood (Fagus sylvatica L.). The heat flux was generated by an electric radiant panel. The analysed parameters included the ignition time of the spruce and beech wood samples, the influence of wood density, and sample moisture, and the course of sample combustion, both with and without flame, was observed. The heat flux was maintained at constant values, depending on the distance of the examined sample from the panel, along with the specific power of the radiation panel. The power of the radiation panel was set to constant values of 5 kW and 10 kW. The samples were placed at distances of 50, 70, 100, 150, and 200 mm from the heat source, and heat fluxes in the range of 13–92 kW·m⁻² were observed. At a power of 5 kW and a heat flux of 64 kW·m⁻², neither the sample of beech nor that of spruce wood, placed at the distance of 100 mm from the radiation panel, exhibited flaming combustion. The ignition time for the beech wood was approximately twice that of the spruce wood, likely due to the higher average wood density. It can be stated that wood density, as one of the main factors, significantly influences the ignition phase of burning. The statistical analysis examined variables including wood type, radiant panel output, distance, and heat flux in relation to ignition time. The analysis revealed a significant difference between ignition time and distance (p-value = 0.0000, H = 37.51583) as well as between ignition time and heat flux (p-value = 0.0000, H = 37.69726). Similarly, the time to ignition for all tested beech wood samples was longer than for spruce wood. Full article

The standard for ergonomics of the thermal environment provides information on the calculation of optimal thermal comfort. Operative temperature (OT) is one of the essential elements of thermal comfort and is a function of air temperature, mean radiant temperature (MRT), and air velocity. This paper investigates the impact of diverse influences on MRT in an office room based on occupant position and posture (seated and standing). A comparative simulation study of the varied thermal transmittance (U-value) of the only external wall with a window in an office room depending on the wide-ranging outdoor temperature is conducted in the MATLAB tool Simulink. The air temperature and air velocity are assumed according to the standards, and the MRT is simulated. The angle factors, U-value of walls/windows, occupant position, occupant posture, and outdoor temperature are the critical parameters that affect MRT. The results show varied responses from MRT for each of the five outdoor temperature scenarios simulated for three types of exterior walls. Seated occupants have equal MRT, whereas standing occupants have minor discrepancies when exposed to a window at the same distance in all outdoor scenarios. When the placement of occupants is not equally exposed to the window, the seated occupants have a higher MRT difference than the standing occupants. Full article

Background and Objectives: Chronic non-specific low back pain (CNSLBP) is defined as back pain that lasts longer than 12 weeks. Capacitive and resistive electric transfer (TECAR) therapy utilizes radiant energy to generate endogenous heat and is widely used for the treatment of chronic musculoskeletal pain. The aim of this study was to investigate the efficacy of manual therapy (MT) program combined with TECAR therapy in individuals with CNSLBP. Materials and Methods: Sixty adults with CNSLBP were randomly divided equally into three groups. The first group followed an MT protocol in the lumbar region (MT group), the second group followed the same MT protocol combined with TECAR therapy (MT + TECAR group) using a conventional capacitive electrode as well as a special resistive electrode bracelet, and the third group (control group) received no treatment. Both intervention programs included six treatments over two weeks. Pain in the last 24 h with the Numeric Pain Rating Scale (NPRS), functional ability with the Roland–Morris Disability Questionnaire (RMDQ), pressure pain threshold (PPT) in the lumbar region with pressure algometry, and mobility of the lumbo-pelvic region through fingertip-to-floor distance (FFD) test were evaluated before and after the intervention period with a one-month follow-up. Analysis of variance with repeated measures was applied. Results: In the NPRS score, both intervention groups showed statistically significant differences compared to the control group both during the second week and the one-month follow-up (p < 0.001). Between-group differences were also noticed between the two intervention groups in the second week (p < 0.05). Differences in the RMDQ score were detected between the intervention groups and the control group in the second week and at the one-month follow-up (p < 0.001), while differences between the two intervention groups were only detected at the one-month follow-up (p < 0.001). Regarding the PPT values, differences were found mainly between the MT + TECAR group and the control group and between the MT + TECAR group and the MT group (p < 0.05), with the MT + TECAR group in most cases showing the greatest improvement compared to the other two groups, which remained statistically significant at the one-month follow-up (p < 0.05). Finally, both intervention groups improved the mobility of the lumbo-pelvic region at both time points compared to the control group without, however, statistically significant differences between them (p > 0.05). Conclusions: The application of an MT protocol with TECAR therapy appeared more effective than conventional MT as well as compared to the control group in reducing pain and disability and improving PPT in individuals with CNSLBP. No further improvement was noted in the mobility of the lumbo-pelvic region by adding TECAR to the MT intervention. Full article

Radiation cooling, as a new terminal mode that has been gradually emerging in recent years, has attracted more and more attention. However, the problem of condensation has become a vital bottleneck restricting the broad application of radiation-cooling technology. This paper used the numerical simulation method of Ansys Fluent to study the effect of different water supply parameters on the concrete radiant roof’s heat transfer performance, temperature uniformity analysis, and anti-condensation temperature control strategy. The accuracy of the simulation model was verified by comparing the numerical simulation values and measured values of temperature monitoring points. In thermal performance research, the inlet temperature significantly impacted the cooling capacity and radiant surface temperature compared with the inlet flow velocity. In the uniformity study, the distance between the serpentine pipes area and the concrete edge was easily neglected, which was also an important factor affecting the distribution of temperature uniformity. Regarding anti-condensation and performance improvement research, first supplying water at low temperatures and then dynamically adjusting high-temperature water could effectively avoid condensation and improve the radiant roof’s heat transfer performance. The research results could provide technical references for the practical application of radiation roof anti-condensation temperature control technology. Full article

A safe separation distance (SSD) needs to be considered during firefighting activities (fire suppression or people evacuation) against wildfires. The SSD is of critical interest for both humans and assets located in the wildland–urban interfaces (WUI). In most cases, the safety zone models and guidelines assume a flat terrain and only radiant heating. Nevertheless, injuries or damage do not result exclusively from radiant heating. Indeed, convection must be also considered as a significant contribution of heat transfer, particularly in the presence of the combined effects of sloping terrain and a high wind velocity. In this work, a critical case study is considered for the village of Sari-Solenzara in Corsica (France). This site location was selected by the operational staff since high-intensity fire spread is likely to occur in the WUI during wind-blown conditions. This study was carried out for 4 m high shrubland, a sloping terrain of 12° and a wind speed of 16.6 m/s. The numerical simulations were performed using a fully physical fire model, namely, FireStar2D, to investigate a case of fire spreading, which is thought to be representative of most high wildfire risk situations in Corsica. This study is based on the evaluation of the total (radiative and convective) heat flux received by two types of targets (human bodies and buildings) located ahead of the fire front. The results obtained revealed that the radiation was the dominant heat transfer mode in the evaluation of the SSD. In addition, the predictions were consistent with the criterion established by the operational experts, which assumes that in Corsica, a minimum SSD of 50 m is required to keep an equipped firefighter without injury in a fuelbreak named ZAL. This numerical work also provides correlations relating the total heat flux to the SSD. Full article

UV radiation is used for sterilization but has adverse health effects in humans. UV-A radiation has lower antimicrobial effect than UV-B and UV-C but constitutes a lower health risk, opening up the possibility to sanitize environments with human presence in controlled exposure conditions. We investigated this possibility by identifying safe exposure conditions to a UV-A lamp along with efficient sanitization of the environment. The human exposure limits were calculated following the guidelines provided by the International Commission on Non-Ionizing Radiation Protection and the International Commission on Illumination. Antibacterial activity was evaluated on Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The maximum human exposure duration has been identified at different irradiation distance and angle, increasing with the increase of both parameters. Bactericidal activity was observed in all microorganisms and was higher with higher exposure time and at lower distance from the source. Noteworthily, in equal conditions of radiant exposure, the exposure time impacts on the bactericidal activity more than the distance from the source. The modulation of factors such as distance from the source, exposure time and irradiation angle can enable effective antibacterial activity and human safety. Prolonged direct irradiation of the surfaces associated with indirect human exposure represents the condition of greater efficacy and safety. Full article

Flame radiation is one of the important causes of wildland–urban interface (WUI) fires. PMMA, pine needle and pine wood are the most common fuels in WUI fires, but the radiant distance effect on the flaming ignitions as well as the subsequent burning behavior is still poorly understood. This work represents an experiment to investigate the flaming autoignition of PMMA, pine-needle and pine-wood fuel beds with different radiant distances (25 mm–100 mm) under a uniform incident radiant heat flux, 25 kW/m² The experiment results show that for PMMA and pine wood, they all transition from gas-phase ignition near the cone heater to solid-phase ignition. For pine needle, it has smoldering ignition and smoldering-to-flaming ignition. The relationship between radiant distance and ignition delay time is an approximately inverted u-shape curve, and there exists a critical radiant distance (D = 60 mm) for the minimum ignition delay time. For pine wood and PMMA, when D < 60 mm, there exists a linear relationship between radiant distance, D, and $t_{ig}^{-1/2}$. Full article

Light-curing units (LCUs) are often subject to clinician-determined factors such as infection control barriers (ICBs) and different positionings of the light tip that may reduce their radiant exposure. The objective of this study was to investigate the individual and cumulative effects of ICBs and LCU positioning on light output. One LCU was used, in combination with five different ICBs and five different distances and angles. ICBs were also tested when placed correctly to manufacturers’ guidelines, and with creases or seams obstructing the light tip. All variables were tested in isolation and in combination with other variables. Measurements were taken from a laboratory-grade spectrometer, giving values of radiant exposure, irradiance and spectral emission. All ICBs, angles and distances showed significant reductions in light output compared to the control (p < 0.001). With increasing angle and distance, the light output was decreased further, with the greatest reduction of 80.6% from the control seen at 40° and 8 mm with an incorrectly placed ICB. When used with an ICB, an increasing angle also showed a protective relationship on the light output. When ICBs are used or when an increase in distance/angle is unavoidable, clinicians should consider compensating for the loss in radiant exposure by increasing curing times. Full article

The continuous acquisition of spatial distribution information for offshore hydrocarbon exploitation (OHE) targets is crucial for the research of marine carbon emission activities. The methodological framework based on time-series night light remote sensing images with a feature increment strategy coupled with machine learning models has become one of the most novel techniques for OHE target extraction in recent years. Its performance is mainly influenced by machine learning models, target features, and regional differences. However, there is still a lack of internal comparative studies on the different influencing factors in this framework. Therefore, based on this framework, we selected four different typical experimental regions within the hydrocarbon basins in the South China Sea to validate the extraction performance of six machine learning models (the classification and regression tree (CART), random forest (RF), artificial neural networks (ANN), support vector machine (SVM), Mahalanobis distance (MaD), and maximum likelihood classification (MLC)) using time-series VIIRS night light remote sensing images. On this basis, the influence of the regional differences and the importance of the multi-features were evaluated and analyzed. The results showed that (1) the RF model performed the best, with an average accuracy of 90.74%, which was much higher than the ANN, CART, SVM, MLC, and MaD. (2) The OHE targets with a lower light radiant intensity as well as a closer spatial location were the main subjects of the omission extraction, while the incorrect extractions were mostly caused by the intensive ship activities. (3) The coefficient of variation was the most important feature that affected the accuracy of the OHE target extraction, with a contribution rate of 26%. This was different from the commonly believed frequency feature in the existing research. In the context of global warming, this study can provide a valuable information reference for studies on OHE target extraction, carbon emission activity monitoring, and carbon emission dynamic assessment. Full article