Thermal Response Research Articles

Experimental and numerical study on post-fire flexural capacity of corroded reinforced concrete beams under various cooling methods

This paper investigates the flexural behavior of corroded reinforced concrete (RC) beams after various cooling methods. Twenty-eight RC beams were fabricated, with four beams remaining unexposed to fire and twenty-four subjected to fire damage. The study examined three concrete cover thicknesses (20 mm, 30 mm, and 40 mm), three fire exposure times (60 min, 90 min, and 120 min), and two cooling methods (natural cooling and water cooling) to analyze their impacts on the flexural properties of corroded RC beams. The results revealed that the minimum temperatures experienced by the steel bars were observed with a concrete cover thickness of 40 mm, indicating a reduction of up to 18.19 % compared to a cover thickness of 20 mm. After a 120 min fire exposure, water cooling resulted in brittle failure of corroded RC beams. Relative to room temperature, the peak load of non-corroded specimens with a 20 mm concrete cover thickness decreased by 18.2 % and 26.6 % at 90 and 120 min, respectively. For fire exposure durations of 60, 90, and 120 min, water spraying cooling resulted in a reduction of the peak load of corroded RC beams with a 20 mm cover thickness by approximately −3.9 %, 4.7 %, and 18.9 %, respectively, compared to natural cooling. After 120 min of fire exposure, the bearing capacity of water-cooled specimens increased with increasing concrete cover thickness. Numerical simulations utilizing the finite element method were employed to analyze the thermal response and flexural properties of corroded RC beams. The residual flexural capacity of corroded RC beams post high-temperature exposure was evaluated using three design codes: GB 50010–2010, ACI 318–19, and EN 1992–1-1.

Towards the Automation of Non-destructive Fault Recognition: Enhancement of Robustness and Accuracy Through AI Powered Acoustic and Thermal Signal Analysis in Time, Frequency- and Time-Frequency Domains

AbstractNon-destructive inspection and analysis techniques are crucial for quality assessment and defect analysis in various industries. They enable for screening and monitoring of parts and products without alteration or impact, facilitating the exploration of material interactions and defect formation. With increasing complexity in microelectronic technologies, high reliability, robustness and thus, successful failure analysis is essential. Machine learning (ML) approaches have been developed and evaluated for the analysis of acoustic echo signals and time-resolved thermal responses for assessing their ability for defect detection. In the present paper different ML architectures were evaluated, including 1D and 2D convolutional neural networks (CNNs) after transforming time domain data into the spectral- and wavelet domains. Results showed that 2D CNNs processing data in wavelet domain representation performed best, however at the expense of additional computational effort. Furthermore, ML-based analysis was explored for lock-in thermography to detect and locate defects in the axial dimension based on thermal emissions. While promising, further research is needed to fully realize its potential.

SU-8-meta-phenylenediamine-conjugated thin film for temperature sensing.

Polymers have distinctive optical properties and facile fabrication methods that have been well-established. Therefore, they have immense potential for nanophotonic devices. Here, we demonstrate the temperature-sensing potential of SU8-meta-phenylenediamine (SU8-mPD), produced by epoxy amination of the SU-8 polymer. Its properties were examined through a series of molecular structural techniques and optical methods. Thin layers have demonstrated optical emission and absorption in the visible range around 420 and 520 nm, respectively, alongside a strong thermal responsivity, characterized by the 18 ppm °C-1 expansion coefficient. A photonic chip, comprising a thin 5-10 μm SU8-mPD layer, encased between parallel silver and/or gold thin film mirrors, has been fabricated. When pumped by an external light source, this assembly generates a pronounced fluorescent signal that is superimposed with the Fabry-Pérot (FP) resonant response. The chip undergoes mechanical deformation in response to temperature changes, thereby shifting the FP resonance and encoding temperature information into the fluorescence output spectrum. The time response of the device was estimated to be below 1 s for heating and a few seconds for cooling, opening a new avenue for optical sensing using SU8-based polymers. Thermoresponsive resonant structures, encompassing strong tunable fluorescent properties, can further enrich the functionalities of nanophotonic polymer-based platforms. This article is part of the theme issue 'Celebrating the 15th anniversary of the Royal Society Newton International Fellowship'.

Robust Solid–Solid Phase Change Coating Encapsulated Glass Fiber Fabric with Electromagnetic Interference Shielding for Thermal Management and Message Encryption

AbstractElectromagnetic interference (EMI) shielding composites with both thermal response/management functions and message transfer/encryption behavior are ideal for use in fields such as aerospace, construction engineering, and military equipment. In this work, a self‐cross‐linking supramolecular solid–solid phase change polyethylene glycol (ScPEG) coating is prepared based on multiple hydrogen bonds, which is used for encapsulating glass fiber fabric (GFF) modified with silver nanowires (AgNWs). The solid–solid phase change coating is obtained through the hydrolysis‐condensation of PEG with a reactive silanol end group. Polyethylene glycol molecular chains can store and release heat by switching between the crystalline and amorphous state. The silanol groups can form supramolecular networks through the physical cross‐linking of multiple hydrogen bonds, resulting in an excellent thermal stability. In particular, hydrogen bonds between ScPEG and AgNW‐modified GFF (A‐GFF) enhance interfacial interactions, and the resulting robust structure enables an efficient stress transfer. ScPEG‐coated A‐GFF can achieve a tensile strength of up to 191 MPa and a tunable EMI shielding effectiveness (SE) of 40 to 72 dB depending on the number of fabric layers. Moreover, the fabric exhibits a flexible thermal response characteristic, an outstanding thermal management capability, and potential message encryption behavior.

Feed additives supplementation: a potential strategy to ameliorate heat stress in sheep

Abstract Given a significant climate-flexible and socio-economic role in developing nations, environmental heat stress imposes a major financial impact on sheep production systems globally endangering their production, reproduction, and growth. In this regard, the adverse effects of heat stress on sheep production systems have to be addressed through adoption of effective heat alleviation measures like animal management, nutritional management and genetic interventions of which the nutritional interventions seems to be the most cost effective way to alleviate heat stress. Nutritional manipulation for heat stress alleviation in sheep involves the use of antioxidant supplements (Vitamin B; Vitamin E and Selenium; Selenium; Zinc sulphate and folic acid; Vitamin C, Vitamin E, Selenium and Zinc; Naringin; Opuntia ficus-indica f. inermis; Açai oil and Brown seaweed like Ascophyllum nodosum and Sargassum latifolium). Further, electrolyte supplements (Dietary Electrolyte Balance (DEB); Sodium bicarbonate and potassium bicarbonate; Sodium hydroxide) have a beneficial effect on thermal responses, respiratory activities, gas exchange parameters, rumen fermentation, blood buffering capacity and acid-base balance. The mineral mixture supplements (Mineral blocks; Mineral mixture and antioxidants; Chromium; Zinc) play a crucial role in increasing the efficiency of antioxidant defence system, immunity-related parameters, production, reproduction, feed digestibility and insulin sensitivity. Probiotic supplements (Lactobacillus acidophilus, Saccharomyces cervisiae, Propionibacterium freudenreichii, Lactobacillus casei, Enterococcus faecium, Lactobacillus lactis, Bacillus subtilis, Propionibacterium freudenreichii, Pediococcus cerevisiae, Megaspha eraelsdenii, Bacillus licheniformis, Aspergillus oryzae, Schizochytrium limacinum, Trichoderma reesei and Saccharomyces cerevisiae) improve lactational performance, dietary energy utilization and productivity. The probiotics (live Saccharomyces cerevisiae) and prebiotics (mannan oligosaccharide plus b-glucans) used in heat stress alleviation improve dietary energy utilisation. Furthermore, the vital role of herbal supplements (Rosemary, Cinnamon, Turmeric, Clove, Naringin, Chestnut tannins, Giloy stem powder, Curcumin, Rocket oil (watercress oil), Flaxseed, Cornus, Oregano, Thyme, Chamomile flowers, Moringa oleifera, Betaine) has been highlighted to promote feed intake, antioxidant status, growth performance, feed utilization, reproductive performance and immune response. Effective adoption of nutritional strategies can thus ensure sustainable sheep production in this changing climate scenario.

Thermal biology diversity of bee pollinators: Taxonomic, phylogenetic, and plant community‐level correlates

AbstractCommunity‐wide assembly of plant–pollinator systems depends on an intricate combination of biotic and abiotic factors, including heterogeneity among pollinators in thermal biology and responses to abiotic factors. Studies on the thermal biology of pollinators have mostly considered only one or a few species of plants or pollinators at a time, and the possible driving role of the diversity in thermal biology of pollinator asemblages at the plant community level remains largely unexplored. More specifically, it is unknown whether diversity in the thermal biology of bees, a major pollinator group worldwide, contributes to the assembly and maintenance of diverse bee communities; broadens the spectrum of possibilities available to bee‐pollinated plants; facilitates interspecific partitioning of ecological gradients across habitats, seasons, and time of day; and/or enhance plant pollination success through complementarity effects. The objectives of this study were to assess the diversity in thermal biology of the bee assemblage that pollinates plants in a Mediterranean montane area, evaluate its taxonomic and phylogenetic underpinnings, and elucidate whether there existed seasonal, daily, between‐habitat, or floral visitation correlates of bee thermal biology which could contribute to partition ecological gradients among plant and bee species. Thermal biology parameters were obtained in the laboratory (K, intrinsic warming constant) and the field (thoracic and ambient temperature at foraging site, Tth and Tair) on individual bees of a diverse sample (N = 204 bee species) comprising most bee pollinators of the regional plant community. Species‐specific thermal biology parameters were combined with quantitative field data on bee pollinators and flower visitation for the regional community of entomophilous plants (N = 292 plant species). Results revealed that the regional bee assemblage harbored considerable diversity in thermal biology features; that such diversity was mostly taxonomically, phylogenetically, and body‐size structured; and that the broad interspecific heterogeneity in thermal biology represented in the bee community as a whole eventually translated into daily, seasonal, among‐habitat, and flower visitation patterns at the plant community level. This lends support to the hypothesis that broad diversity in thermal biology of bees can enhance opportunities for bee coexistence, spatiotemporal partitioning of floral resources, and plant pollination success.

The thermal responses of composite box girder bridges with corrugated steel webs under solar radiation

Owing to the direct exposure to complex atmospheric environments, the temperature field of composite box girder bridge with corrugated steel webs (CBGB-CSW) is likely non-uniformly distributed. Whereas, the current researches regarding the thermal responses of CBGB-CSW are insufficient, and the thermal responses of CBGB-CSW under solar radiation are still unknown. Therefore, this paper conducted a long-term temperature experiment on a scaled model to explore the temperature distribution characteristics in CBGB-CSW. Meanwhile, a three-dimensional thermal–mechanical coupling Finite Element (FE) model is established to simulate the temperature field in the experiment girder. The accuracy and effectiveness of the developed FE model has been verified by the measured temperature data. Therewith, the thermal responses (i.e., stress and displacement) of a full-scale continuous CBGB-CSW with a span of 150 m are numerically investigated. The results indicate that the maximum stresses always occur at the midspan section (with a depth of 5 m) of the continuous CBGB-CSW, and considerable concentrations of stress are observed in the steel-concrete junction. The maximum longitudinal tensile and compressive normal stresses within 0.4 m of the upper junction can reach 5.55 MPa and −8.46 MPa respectively, and those of the lower junction can reach 6.96 MPa and −7.05 MPa respectively. Besides, owing to the impacts of vertical and horizontal temperature gradients, significant displacements of the whole bridge can also be observed. The maximum vertical displacement (5.33 mm) of the CBGB-CSW is estimated at the top plate in the midspan, while the maximum horizontal displacement (0.74 mm) is estimated at the trough of the southern corrugated steel web in the midspan. Notably, the outcomes of this paper can provide some useful references for engineers and scholars to understand the thermal responses of the CBGB-CSW.

Encapsulation of Hydrophobic-but-Not-Lipophilic Perfluoro Liquids Based on a Self-Assembled Double Emulsion Template via Solvent Evaporation Method.

The facile encapsulation of perfluoro liquids that are hydrophobic but not lipophilic into liposomes or microcapsules presents a significant challenge in the fields of biomedicine, dynamic optics, functional chemical applications, etc. This is due to their chemical inertness and physical immiscibility, particularly those with low boiling points. In this study, a novel strategy based on a double emulsion template via solvent evaporation is proposed after investigating the mechanism of three-phase emulsion systems. The perfluoro liquid droplets can be easily emulsified into a polymer solution as the second emulsion layer, where the polymer shell is formed during solvent evaporation in the continuum medium under proper processing controls. The morphology of particles is predictable and fits well with the linear model derived from Neumann's triangle in three-phase systems. Furthermore, a comprehensive study on the encapsulation of perfluoro ketone, which is widely used as a green fire extinguisher agent, is conducted as an example. The encapsulated perfluoro ketone showed instant thermal response upon heating while maintaining a good shelf life at room temperature. The remarkable fire suppression performance exhibited great potential for practical applications. This work offers more insight into the encapsulation of "naughty" perfluorinated chemicals and provides more possibilities for extended applications.

Multifunctional Thermochromic Dye‐Integrated Hybrid Nanogenerators for Mechanical Energy Harvesting and Real‐Time IoT Sensing

AbstractHybrid nanogenerators are advanced mechanical energy harvesters capable of simultaneously scavenging multiple types of energy. Additionally, thermochromic materials provide a practical and visually assessable method for real‐time temperature monitoring. In this report, a novel energy harvester and sensing patch (EHSP) is introduced, that utilizes combined piezoelectric and triboelectric effects to harvest mechanical energy efficiently. To optimize the EHSP, various energy harvester configurations are fabricated and tested, and the dielectric properties of triboelectric films are systematically investigated. These improvements are implemented to augment the overall energy harvesting capability. The thermochromic properties of the EHSP are also explored to enhance both the electrical performance and thermal responsiveness. The EHSP demonstrates the ability to generate maximum voltage and current outputs of 350 V and 20.4 µA, respectively. Moreover, it can detect temperature changes within seconds, making it suitable for both energy harvesting and sensing applications. The EHSP is tested in practical scenarios, proving its efficiency as an energy harvester and sensor for everyday human activities. Furthermore, its integration with multiple hybrid nanogenerators showcases its potential for industrial and wearable sensing applications.

Indoor Thermal Environment Improvement Based on Switchable Radiation/Convection-Combined Intermittent Heating: Comparison between Conventional Terminals and Integrated Novel Terminal

Intermittent heating is an energy-saving heating mode, which can save energy in terms of time, and thus is worth promoting, particularly in residential heating scenarios. Conventional radiant heating terminals, that is floor heating, and convective heating terminals, that is fan coils, cannot achieve both intermittent and thermal comfort during intermittent heating. Therefore, this study proposes a switchable convective-radiant heating regulation method for floor heating and fan coils to achieve a comfortable indoor environment with high thermal response speed. Furthermore, a novel combined radiant-convective heating terminal was proposed for a reliable and effective solution. Results showed that the proposed switchable method could increase both intermittence and thermal comfort. In addition, the heating terminal showed better heating performance than the combination of two conventional terminals at the key points of heating capacity, flexibility, and thermal response. It could initially heat up a typical residential space within 20–40 min and then stabilize the room temperature in a comfortable range of 18–22 °C, showing great potential for intermittent heating in room-scale heating conditions. This study provides a reference technique for intermittent heating with reduced system complexity and precise environmental control.

Application of microscale methods to study the heat-induced delamination in engineered wood products bonded with one-component polyurethane adhesives

One-component polyurethanes (1-c-PUR) are commonly used adhesives for the manufacture of cross-laminated timber (CLT). Typically, these adhesives do not govern the mechanical response of CLT under normal service temperatures. However, when subjected to heating from a fire, failures may transition from within the timber to the bond line interphase zones. CLT bonded with 1-c-PUR has been shown to be prone to heat induced delamination (HID), which may compromise its structural performance at elevated temperatures. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic thermo-mechanical analysis (DTMA) were used to study the thermal and thermo-mechanical responses of engineered wood products and components (i.e. adhesives and timber) and their interphase (i.e. bond line). Two commercially available 1-c-PUR adhesive films from the same manufacturer, two timber species (Norway Spruce and Radiata Pine, as sawdust or as veneers), and four different veneer shear lap combinations, were studied. Shear lap specimens bonded with a conventional 1-c-PUR adhesive consistently experienced bond line mechanical failure in DTMA at about 220–240 °C. The same adhesive films tested via DSC and TGA softened at 240–260 °C. Conversely, a different 1-c-PUR adhesive, formulated specifically for enhanced performance at elevated temperature, displayed no detectable softening in DSC and TGA, and shear lap specimens in DTMA consistently failed within the timber; even at elevated temperatures. The presented thermo-mechanical methods allow identification of failure modes and temperatures, whilst the thermal microscale methods (i.e. TGA, DSC, DTMA) assist in understanding the various factors contributing to failures.

Comparison between conduction models and models including the energy balance along the flow, for the simulation of U-tube borehole heat exchangers

Most ground-coupled heat pumps exchange heat with the ground by means of a borehole-heat-exchanger (BHE) field. The time evolution of the fluid temperature at the outlet of the BHE field, employed for the design of the heat pump, is often determined starting from that of the mean temperature of the surface between the BHEs and the ground, evaluated by means of a dimensionless function called g-function. In order to obtain an accurate thermal response to peak loads, this method must be coupled with a short-term simulation tool. Simulation models that yield accurately the time evolution of either the outlet fluid temperature or the mean fluid temperature both in the short and in the long term are also available. The simplest of these models, called here conduction models, represent the fluid by a solid that receives or generates heat. Models that include the energy balance for the flow along the pipes, called here complete models, have also been proposed. Complete models are the most accurate, but can hardly be applied for long-term simulations. In this paper, the results of finite-element simulations of U-tube BHES performed by conduction models are compared with those obtained by complete models, implemented through the COMSOL Pipe Flow Module. It is shown that there is an excellent agreement between the models in the short term, while complete models yield slightly higher values of the mean fluid temperature in the medium and long term. It is also shown that one can obtain by a conduction model the same time evolution of the mean fluid temperature that would be yielded by a complete model, replacing the real 2D BHE thermal resistance, Rb2D, with a virtual one, equal to the asymptotic value of the 3D thermal resistance yielded by the complete model, RbPF. For BHEs with length 100 m, diameter 152 mm, grout thermal conductivity 1.6 W/(m K), ground thermal conductivity 1.8 W/(m K) and flow rate 14 L per minute, the ratio RbPF/Rb2D is, for instance, 1.032 for a single U-tube BHE with shank spacing s = 94 mm, and 1.090 for a double U-tube BHE with s = 85 mm. Dimensionless correlations yielding the value of RbPF/Rb2D for any U-tube BHE will be provided in a future paper.

Bridging micro nature with macro behaviors for granular thermal mechanics

The connection between micro-level characteristics and macroscopic properties in granular heat transfer and mechanics is fundamental and crucial. This study proposes a novel discrete element approach incorporating granular heat transfer, contact bonding, and granular stress tensor models to investigate the mechanical and thermal responses of continuum media composed of constituent spheres. Eight benchmark tests were devised to bridge the long-standing gap between micro and macro properties in granular materials. Through these tests, the numerical solutions obtained from discrete element modeling match well with existing analytical or finite element solutions derived from continuum-based theory. This validation underscores the rationality and reliability of the granular heat transfer model, contact bonding model, and granular stress tensor model. Moreover, the study highlights the consistency between continuum-based theory and discontinuum-based theory. A minor distinction between continuum-based models and discrete element models emerges near the boundaries due to variations in the specification of boundary conditions. This discrepancy can be clarified by Saint-Venant's Principle, thus validating the accuracy of the microscale heat transfer and mechanics theory for granular materials. Five mono-disperse packing structures, including simple cubic (SC), body-centered cubic (BCC), face-centered cubic (FCC), hexagonal close packing (HCP), and random packing (Random), were further analyzed to examine their influence on heat transfer performance. Numerical results reveal that higher coordination numbers and solid volume fractions correspond to higher apparent thermal conductivity of granular assemblies, thus elucidating the connection between micro packing configurations and macroscopic heat transfer properties. The apparent thermal conductivity for different crystal configurations follows the sequence: HCP ≒ FCC > BCC ≒ Random > SC. To improve the accuracy and physical relevance of the proposed model, the effect of particle contact area needs to be further incorporated into the granular heat transfer model.

3D printing of liquid metal circuits on fabric for stretchable heater application

Abstract Liquid metals (LMs), due to their excellent stretchability, low resistance, and high thermal conductivity, has become an ideal material for preparing stretchable circuits. 3D printing technology can produce patterns with complex structures with high precision and is suitable for low-cost large-scale production of circuits. However, the high surface tension of liquid metals limits the practical application of 3D printing of LMs. In this work, we proposed a method for preparing a mixed ink based on thermoplastic polyurethane, Cyrene solvent, and LMs, and producing stretchable LMs-based electrodes through 3D printing on a fabric substrate. The stretchable LMs-based electrode prepared by this method shows a wide range of strain response and excellent tensile recovery performance, providing theoretical guidance for the application of LMs electrodes. In addition, the LMs-based heaters showed good Joule thermal response at low voltages, as well as good tensile stability, providing a new strategy for wearable heaters.

Titanium dioxide/graphene oxide synergetic reinforced composite phase change materials with excellent thermal energy storage and photo-thermal performances

The development of advanced composite solid-solid phase change materials (SSPCMs) is urgent to explore for improving solar energy harvesting and storage. Herein, novel composite SSPCMs with synergetic cross-linking structure were fabricated through polymerization using GO and TiO2 constructed on the polyurethane framework skeleton. GO and TiO2 synergetic enhanced polymer framework played a role as skeletal structure to encapsulate PEG in the molecular chains, and provided as highly thermal conductive pathways for the composite SSPCMs. TiO2 nanoparticles performed as extended surface on the skeletal structure for further improvement in thermal conductivity. The composite SSPCMs exhibited a remarkably improved thermal conductivity as high as 0.7 W/(m‧K) and fast thermal response rate. The good light adsorption property of TiO2 enhanced the light absorbance efficiency of the composite SSPCMs by 94.4%. And the photo-thermal conversion efficiency of the composite SSPCMs highly reached 93.5%. Meanwhile, the composite SSPCMs exhibited excellent anti-leakage performance and shape stability under high temperature. Consequently, the as-prepared composite SSPCMs possessed a potential for applications in thermal energy storage and solar energy utilization systems.

Thermal and Frequency Response Analysis on Friction Stir Welding Tool with Different Materials by Using FEA Method

Friction stir welding (FSW) is a solid-state joining technique that joins two facing workpieces without melting the workpiece material. It makes use of a deceased item. The region surrounding the FSW tool softens due to heat produced by friction between the revolving tool and the workpiece material. We are now working on specialised applications (lap and butt welding) while concentrating on test sorts. In addition to being faster than the state of the art, both provide lap welds that are 190% of the plate thickness, improve weld honesty, and lessen upper plate decline. Friction stir welding, or FSW for short, is a popular solid state joining method for soft materials like aluminium alloys. For stronger alloys like steel and titanium alloys, the FSW process's economic sustainability hinges on the creation of long-lasting, moderately cost equipment that reliably yields welds with outstanding structural integrity. The performance of the tool, weld quality, and cost are all impacted by material design and choice. This research reviews and critically examines many key FSW tool components, including process economics, geometry and load bearing capacity, frequency response analysis, tool degradation mechanisms, and tool material selection. The Finite Element Method (FEM) approach is used to characterise the process and provide a more comprehensive knowledge of the thermal effects and thermal inaccuracies on the tool materials.

Forecasting regional in-situ thermal conductivity of soil based on tree-based ensemble learning

Borehole heat exchanger is essential component in ground-source heat pumps (GSHPs) for developing geothermal energy, where device efficiency depends on the thermal conductivity of soil. Although the thermal response test is generally used to measure this parameter, its time-consuming and susceptibility to test conditions can impact the accuracy of the test. To address this issue, the study conducted shallow geothermal surveys to establish a comprehensive dataset, enabling the construction of the in-situ thermal conductivity predictive model. By selecting seven input features, four classic tree-based ensemble learning models and stacking algorithms were used. Among all the post-tuned models examined, XGBoost-RF emerged as the standout performer, boasting an impressive R2 value of 0.9809 along with the lowest RMSE and MAE. Notably, it demonstrated generalization capabilities, with errors consistently staying within 5 % during the validation process. Additionally, the SHapley Additive exPlanations (SHAP) was used to enhance the interpretability of the model. Among these, the weighted thermal conductivity of the geotechnical was the most influential feature, while groundwater conditions such as permeability coefficient and aquifer thickness were also significant factors. This study provides a rapid and precise prediction of regional in-situ thermal conductivity. It leads to effective decision-making in the design stage of GSHPs.

Thermal Analysis of Composite Slabs Based on Experiment and Numerical Simulations

AbstractThis paper presents an experimental and numerical investigation on the thermal response of composite slabs under fire condition, considering various slab geometries. Fire tests were conducted on six composite slabs to obtain the temperature distributions exposed to the ISO 834 standard fire curve for a duration of 210 min. The results indicated that the depth of the concrete significantly affects the temperature of the unexposed surface, while the height of the steel deck has minimal impact. During heating, water vapor and condensation occurred on all tested slabs, causing a delay in the early temperature development of the concrete. The temperature distribution across slab cross-sections was subsequently calculated using numerical simulations. The numerical models were then validated using experimental data. The challenge of precisely simulating the interface between steel deck and concrete was resolved in this numerical model.

Nutrient availability influences the thermal response of marine diatoms

AbstractUnderstanding how phytoplankton growth responds to temperature is critical for forecasting marine productivity in a warming ocean. While previous laboratory studies have shown that phytoplankton thermal traits such as optimal temperature (Topt) can be affected by nutrient availability, it is unclear whether this can be extrapolated to natural communities. To address this, we tested the impacts of nutrient availability on the thermal responses of two cosmopolitan diatom genera, Pseudo‐nitzschia and Leptocylindrus, through a series of in situ manipulation experiments on natural phytoplankton communities. Analysis of the thermal performance curves revealed that nutrient limitation during summer not only limited the growth of these two genera but also reduced their Topt and the maximum growth rates (μmax). Topt was close to or lower than in situ temperature under ambient nutrient conditions, suggesting that further warming may have a detrimental effect on their growth. However, increasing nutrient supply could counteract this by enhancing Topt and μmax. To further confirm the interactive effects of nutrients and temperature on diatoms, we analyzed a 20‐yr monitoring dataset on Pseudo‐nitzschia, Leptocylindrus, and the whole diatom assembly in Hong Kong coastal waters. We found that the abundances of marine diatoms were significantly higher at high temperatures under nutrient‐rich environments while relatively low under low nutrient concentrations. Findings on natural diatom cell density align with the growth performance derived from in situ manipulation experiments, suggesting that abundant nutrients bolster marine diatoms in coping with warming. Our results highlight the importance of considering the influence of nutrient availability on thermal response of phytoplankton growth, which sheds light on how marine primary production may change under climate warming.

The Significance of Body Surface Area to Mass Ratio for Thermal Responses to a Standardized Exercise-Heat Stress Test.

To evaluate the significance of body surface area-to-mass ratio (BSA/mass) on the heat-tolerance test (HTT) results. We hypothesized that individuals defined as heat tolerant (HT) would have on average higher BSA/mass compared to heat intolerant (HI) individuals. A retrospective reanalysis of the HTT results of 517 soldiers (age: 18-38 yrs., M/F: 96/4%), who were tested by the Israel Defense Forces (IDF) HTT protocol. The criterion for heat tolerance in the current analysis was a rectal temperature (Tre) plateau during the second hour of the test. A logistic regression analysis to evaluate the predictive power of BSA/mass for heat intolerance was performed; the spline model was applied to show the odds for heat intolerance across BSA/mass. In men BSA/mass of HI individuals was lower than HT individuals (248 ± 19 vs. 262 ± 18 cm2/kg, p < 0.01, d = 0.76). In women a similar trend was noted but with no statistical significance between HT and HI groups. The odd ratio for heat intolerance for every unit increase in BSA/mass was 0.97 (CI 95% 0.95-0.99). The spline model plateaued above BSA/mass of 270 cm2/kg. The results imply that body-core temperature responses to a standard exercise-heat stress (fixed external work rate and climatic conditions) are influenced by BSA/mass. More specifically, lack of a steady state in Tre (indicating heat intolerance) was more likely to occur with every unit decrease in BSA/mass. These findings contribute to a better understanding of the role of body anthropometry in the response to a standard exercise-heat task that might have an implication on clinical decision-making about return to duty/play of soldiers, athletes and others who deemed to be identified as HI.