Significant Temperature Differences Research Articles

Can pin-site inflammation be detected with thermographic imaging? A cross-sectional study from the USA and Denmark of patients treated with external fixators.

Patients with external fixators are at risk of pin-site infection. A tool for objective monitoring of pin sites for evolving signs of infection is warranted. We aimed to investigate the temperature (MaxTp) difference between clean and visually inflamed pin sites using thermography and to establish the optimal cut-off value of MaxTp using thermography as a screening tool for inflammation detection. This was a cross-sectional study performed in the USA and Denmark of patients with circular external fixators. Pin sites were visually judged by a surgeon or a nurse as clean or as showing signs of inflammation. The MaxTp was obtained at the pin site by thermographic imaging using an infrared camera (FLIR T540). We included 1,970 pin sites from 83 patients. The mean MaxTp for clean pin sites (n = 1,739) was 33.1°C (95% confidence interval [CI] 32.8-33.4) and the mean MaxTp for visual inflamed pin sites (n = 231) was 34.0°C (CI 33.6-34.3). The mean difference, when adjusted for repeated observations of patients and pin sites, was statistically significant with a difference of 0.9°C (CI 0.7-1.1) (P < 0.001). The area under the receiver operating characteristic curve for MaxTp as a screening tool to detect visual signs of inflammation was 0.71 (CI 0.65-0.76). The empirically optimal cut-off value was 34.1°C with a sensitivity of 65%, a specificity of 72%, a positive predictive value of 23%, and a negative predictive value of 94%. We found a statistically significant difference in mean temperature between pin sites with and without visual signs of inflammation. Thermography could be a promising tool for future point of care technology for monitoring inflammation around pin sites.

Thermal Stress Analysis of Compact Heat Exchanger Produced by Additive Manufacturing

Abstract Compact heat exchangers are renowned for their high heat transfer rates and efficiency, achieved by incorporating mini and micro-channels in their core design. However, operating under conditions of high-pressure fluctuations and significant temperature differences between hot and cold streams can potentially induce fatigue failure. To the best of our knowledge, this study represents the first investigation into the thermal stresses experienced by heat exchanger samples manufactured by selective laser melting technology, focusing on circular channels. Experiments were conducted using hot water in the inner channel, while the remaining channels and the sample surface were subjected to natural convection in ambient air. Strain gauges, thermocouples, and RTDs were employed to measure strain and temperature variations over time. These data were utilized as inputs for a numerical model based on finite element method. The strain measurements were compared with those obtained from the numerical model, revealing an average difference of approximately 20%. Lastly, a thermal fatigue analysis based on the maximum equivalent stresses predicted by the numerical model is presented. The evaluation considered both S-N curves: outlined in the ASME standard and the one obtained with specimens produced through selective laser melting. In the case of circular channels manufactured through additive manufacturing evaluated in this work, thermal stresses alone are insufficient to cause component failure due to fatigue. However, significant pressure cycles superimposed on the model can reverse this situation, making the combined effect of thermal and mechanical stresses influential in determining the component's fatigue behavior.

Fire Resistance Performance of Constrained H-Shaped Steel Columns with Uneven Vertical Temperature Distributions

Steel columns, which are widely used in building frameworks and spatial structures, are susceptible to capacity degradation during fires, potentially leading to the overall collapse of buildings. Existing research on the fire resistance of steel columns assumes that the temperature loads encountered by steel columns are evenly distributed vertically. However, real-world fire scenarios often feature significant vertical temperature differences. Therefore, this study comprehensively investigated these variations to derive a temperature curve that accurately represents real fire conditions. Subsequently, the fire resistance limits of steel columns were studied using this temperature curve, leading to a revised calculation formula for the critical fire resistance temperatures of steel columns. The following conclusions were drawn: (1) Nonuniform longitudinal temperature distributions are influenced by parameters such as the fire source distance, the heights of ventilation openings, and the distance between a vent and the temperature measurement point. Among them, the fire source distance has the greatest impact, with the maximum longitudinal temperature difference reaching over 500 °C. (2) Variations in the load ratio and longitudinal temperature differences alter the failure positions of steel columns, reducing their critical temperatures by up to 200 °C. (3) The revised critical fire resistance temperature formula is more accurate and safer compared with that outlined in the “Technical Code for Fire Protection of Steel Structures” (GB51249-2017). These findings offer valuable insights for the fire designs of steel columns.

Performance assessment of residential heat pumps operating in extreme cold climates using zeotropic mixtures

Extremely cold climates subject residential heat pumps to significant temperature differences between the heat source and the ambient being heated, which may lead to system failure and reduced compressor performance. The present study considers the possibility of improving the performance of heat pump systems that are simultaneously used for residential space and domestic water heating while subjected to climates varying from -25 °C to 5 °C by exploring the use of zeotropic mixtures. CO2-based binary mixtures composed of low-GWP (global warming potential) refrigerants are considered – R32, R1234yf, and R290 – aiming to benefit from environmentally friendly and flame suppressants characteristics of CO2, as well as the improved thermal efficiency granted by the addition of a secondary refrigerant. A thermodynamic model was developed for a standard vapor-compression heat pump cycle and used to maximize the coefficient of performance limited by the minimum pinch point in the heat exchangers. Our analysis explores the effect of several parameters, such as, the mixture components, mass fractions, space and water heating demands, and heat source temperature on the heat pump's performance. For cold climates, the mixture of R32 (90%)/CO2 (10%) yields the highest COP and CO2-rich mixtures exhibit the lowest. However, by increasing the mass fraction of CO2 within the zeotropic mixture, the pressure ratio of the heat pump was improved. When considering combined performance criteria, such as the volumetric heating effect and the total heat delivered related to heat pump size, CO2-rich mixtures tend to allow more compact systems, especially in colder climates.

Exploration of new function for thermal energy storage: Temperature stabilizer

Thermal energy storage (TES) is a technology that stores thermal energy by heating or cooling a storage medium so that the stored energy can be used when needed. TES is usually used in greenhouse heating, centralized solar power, and industrial waste heat recovery to improve the efficiency of energy utilization. This article explores a new application of TES, which relies on its constant outlet temperature to provide stable working conditions for other components. A simulation consisting of 10 cycles with a total length of 100 h is designed. Each cycle contains 5 h of discharge and 5 h of charge, achieved by adjusting the inlet temperature. Rock and NaNO3 are selected as materials for sensible and latent heat storage. This paper discusses the temperature distribution and thermal storage capacity of TES under alternating inlet temperature. The results indicate that the outlet temperature of sensible heat storage will fluctuate and the maximum amplitude is 4.56 K. For latent heat storage, the outlet temperature is constant, and fluid temperature and liquid phase ratio distribution do not change with the number of cycles. There is a significant temperature difference between fluid and solid in phase transition stage, with a maximum value of 10.72 K. Mathematical relationship between latent heat storage parameters and the minimum length of TES is obtained.

Microscopic alterations and adaptation in the lungs of the Japanese quail exposed to acute or chronic heat stress

BackgroundGlobal warming causes heat stress, a significant bioclimatic factor affecting poultry welfare. The effects of heat stress on the morphology of the Japanese quail lungs were investigated in this study. A total of 16 adult Japanese quail were randomly distributed into four groups: a control group (CT), acute heat stress (AH), chronic heat stress with 7 days (CH1) and chronic heat stress with 28 days exposure (CH2). The CT group were maintained at 25 °C temperature, the AH group were exposed to 38 °C temperature for 24 h, and the CH groups were exposed to 35 °C for seven and 28 days. At the end of exposure, the birds were euthanised, and lung tissues were collected and processed for microscopy. Tissue sections were stained using H&E stain, Gomori’s stain and immunofluorescence labelling.ResultsThis study showed no significant difference in body weight, cloacal temperature, respiratory rate and lung parameters in heat-stressed groups compared with the control group. However, microscopic analyses revealed blood congestion, leakage of blood into the airway, inflammatory response and tissue breakage in the heat-stressed groups.ConclusionsHeat stress harmed the lungs of the Japanese quail based on duration and intensity. The negative impact could cause instant mortality, but if the quail survives the initial impact, it can adapt to the heat stress with long-term consequences on its performance.

Analysis of the fracture behavior and mechanism of PIP-C/SiC composites at high temperatures

The high-temperature fracture toughness of C/SiC composites is of great significance for the tolerance assessment and safety application of components in service. In this work, combining the high-temperature experimental technique and phase field method, the fracture toughness of PIP-C/SiC composites at 25–1600 ℃ in inert atmosphere was tested, and the microcrack propagation at different temperatures was simulated. The fracture model considers the effects of residual stress, temperature-dependent properties of constituents and interfacial graphitization on the crack propagation process. The results show that the fracture toughness and modes of C/SiC composites have significant temperature dependence and difference in in-plane and out-of-plane orientations. As the increase of temperature, the cracks exhibit three typical modes of deflection, penetration and long-debonding at the fiber–matrix interphase. It is worth noting that C/SiC composites show a unique fracture mode at 1600 ℃ with the work of fracture increasing significantly. Overall, the work provides a guidance for the damage tolerance assessment of C/SiC composites in engineering.

Cultural adaptation and validation of the Ghent global IAD monitoring tool (GLOBIAD-M) for Brazilian Portuguese

BackgroundIncontinence-associated dermatitis (IAD) poses a significant challenge for individuals experiencing incontinence, characterized by irritative contact dermatitis due to prolonged exposure to urine and/or faeces. ObjectiveThis study aimed to culturally adapt the Ghent Global IAD Monitoring Tool – GLOBIAD-M to Brazilian Portuguese and to assess the adapted version's measurement properties quality. MethodA clinimetric study was conducted, comprising cultural adaptation and psychometric assessment. Cultural adaptation followed international guidelines, while psychometric properties were evaluated for content validity, inter-rater reliability, and correlation with other variables (thermography). Inter-rater reliability was assessed through clinical and photographic evaluations. The study samples included linguists and, IAD specialists, nurses, and adult patients with IAD according to the cultural adaptation or psychometric evidence assessment. ResultThe process of cultural adaptation resulted in a cumulative coefficient of variation ratio (CVR) of 0.66. Subsequently, the study included 57 patients and 57 nurses for clinical assessments, totalling 166 evaluations of IAD. The inter-rater reliability among nurses was deemed satisfactory, with a Gwet coefficient of 0.77. Moreover, out of 215 photographic assessments conducted by 54 nurses, there was a 92.1 % concurrence in the categorization of IAD. Furthermore, thermography analysis revealed significant temperature differences between healthy individuals and those with IAD, particularly in patients categorized under IAD Cat. 1B, showing a difference of 1.90 °C. Conclusionand Impact on Clinical Practice: The results confirm the availability of the GLOBIAD-M in its Brazilian Portuguese version. This tool will allow health professionals to obtain a standardized IAD classification and monitoring in Brazil, enhancing its diagnostic accuracy and aiding clinical decision-making.

Enhancing thermodynamic performance with an advanced combined power and refrigeration cycle with dual LNG cold energy utilization

Utilizing waste heat to drive thermodynamic systems is imperative for improving energy efficiency, thereby improving sustainability. A combined cooling and power systems (CCP) utilizes heat from a temperature source to deliver both power and cooling. However, CCP systems utilizing LNG cold energy suffers from low second law efficiency due to significant temperature differences. To address this, an “Advanced Power and Cooling with LNG Utilization (ACPLU)” system is proposed, integrating a cascaded transcritical carbon dioxide (TCO2)-LNG cycle with an Organic Rankine cycle (ORC) for improved power generation and an absorption refrigeration system (ARS) for simultaneous cooling. This study evaluates the second law efficiency, net work output, and exergy destruction performance through a sensitivity analysis, optimizing variables such as heat source temperature, superheater temperature difference, ORC and CO2 turbine inlet and condenser pressures, evaporator temperature, and pinch point temperatures of heat exchangers and generator. Compared to previous studies on CCP systems, the ACPLU shows a superior performance, with a second law efficiency of 27.3 % and a net work output of 11.76 MW. Cyclopentane as an ORC working fluid resulted in the highest second law efficiency of 29.06 % and net work output of 12.27 MW. Parametric analysis suggested that heat source temperature significantly impacts net power output. The exergy analysis concluded that a high-pressure ratio and good thermal match between the heat exchangers enhance overall performance. Utilizing artificial neural network (ANN) to produce a multiple-input-multiple-output (MIMO) objective function and performing multi-objective optimization (MOO) using genetic algorithm (GA), an improved second law efficiency and net power output by 28.11 % and 14.16 MW respectively, with pentane as the working fluid, is demonstrated. An average cost rate of 9.121 $/GJ was observed through a thermo-economic analysis. The ACPLU system is promising for medium temperature waste heat recovery, such as, pharmaceutical manufacturing plants.

A study on surface temperature of different materials

Excessive buildings took over green vegetation, which aggravated the greenhouse effect. If we use vegetation as roofs and exterior walls of buildings, the areas of plants will not reduce, and even the temperature around the building will decrease. Therefore, we planned to detect the surface temperature of different materials to provide evidence for ideal materials. We detected surface temperature of different materials with an infrared temperature gun (DELIXI, DM-5002). Detected materials included turf, suffruticosa plant, and soil under them, tile or concrete, wood, water with different depths of 1cm, 5cm, 10cm. We detected different materials under different weather conditions. The surface temperature of turf was significantly decreased compared with tile or concrete, wood (p&lt;0.05). There was no significant difference between wood and tile/concrete temperature. Compared with tile/concrete or wood, the surface temperatures of water, turf, suffruticosa plant, and soil under plant significantly decreased (p&lt;0.05). There was no significant difference of temperature between water with different depths. There was no significant difference in temperature between turf, suffruticosa plant, and the soil under them, too. The surface temperatures of turf, suffruticosa plant, and water were significantly lower than those of tile/concrete and wood we used as raw materials of buildings. Plants can be recommended as new materials covering roofs and exterior walls to decrease temperature around buildings in summer.

Temperature Rise and Pain Following the Use of 810 and 980 nm Diode Lasers for Second-Stage Dental Implant Surgery: A Clinical Trial.

Introduction: Many surgical procedures in a soft tissue are performed using diodes lasers. This study aimed to assess the temperature rise and pain following the use of 810 and 980 nm diode lasers for second-stage dental implant surgery. Methods: This clinical trial was conducted on 24 osseointegrated dental implants that were randomly divided into two groups of 810 nm and 980 nm diode lasers. The temperature rise in each group was measured right after uncovering by the laser and 15 minutes later by a thermocouple, compared with the baseline temperature of gingival tissue. The level of pain was also measured at 24 hours postoperatively by using a visual analog scale. Data were analyzed by ANOVA, Tukey's test, and t test (alpha=0.05). Results: Within-group comparisons by ANOVA showed a significant difference in tissue temperature between the three time points in both groups (P<0.0001). Pairwise comparisons by Tukey's test showed that the temperature at baseline (P<0.0001) and 15 seconds after uncovering was significantly lower than that immediately after uncovering in both groups (P<0.0001). The mean tissue temperature and the mean pain score in the 980 nm laser group were significantly higher than the corresponding values in the 810 nm laser group (P<0.05). Conclusion: According to the results, temperature rise in the use of the 980 nm laser was higher than the 810 nm laser. The use of 810 nm diode laser was associated with lower temperature rise and significantly lower pain score after 24 hours.

COMPARATIVE EVALUATION OF THE ADAPTIVE RESPONSES OF YANKASA AND SUDAN FAT-TAILED SHEEP IN THE TROPICAL HOT-DRY SEASON

The aim of the study was to comparatively evaluate the variation in physiological parameters of Yankasa (n=10) and recently introduced, Sudan Fat-tailed (n=10) sheep during the peak of the hot-dry season in the Guinea Savannah climate. Results revealed that the rectal, skin, eye and hair temperatures, as well as respiratory and pulse rate were significantly higher in the afternoon as compared with the morning and evening hours in both breeds. The Sudan Fat-tailed exhibited lower (P &lt;0.05) skin and hair temperatures in the morning, while in the afternoon hours, they had higher (P &lt; 0.05) eye temperature and heart rate compared with Yankasa sheep. There was no significant breed difference in respiratory rate and rectal temperature. It was concluded that although both breeds of sheep showed some variation in physiological response to the heat stress during the peak of the hot- dry season, they are equally adapted to the peak of the heat stress in the Guinea Savannah climate. However, the adaptive responses of Sudan Fat-tailed to other seasons need to be evaluated.

DAILY THERMOREGULATORY RESPONSE OF FOUR BREEDS OF NON-PREGNANT COWS IN IBADAN, NIGERIA

The thermoregulatory responses of 4 non-pregnant cow breeds (Jersey, N'Dama, White Fulani and Sokoto Gudali) totaling 20 with corresponding replicates n = 4, 4, 4, 8 respectively were determined in an experiment. They were housed under similar conditions, fed same diet, fairly evenly aged (2-21⁄2 years) with weights ranging from 270 to 315kg. Pulse rate, heart rate, respiratory rate and rectal temperature of the animals were measured twice daily-before (7:30a.m.) and after grazing (3:00 p.m.). Ambient temperature and relative humidity were also recorded. The pulse rate (beats/minute) in Jersey cows (57.27) was significantly (P&lt;0.05) higher than that in N'Dama cows (55.84) which had the least value. Heart rate (beats/minute) was significantly (P&lt;0.05) higher in Jersey cows (57.94) than N'Dama cows (56.21). Respiratory rate (beats/minute) in Jersey cows (48.25) was significantly (P&lt;0.05) higher than that of N'Dama cows (40.50), White Fulani cows (41.25) and Sokoto Gudali cows (41.88). There was no significant difference in rectal temperature across the breeds. All parameters evaluated were within the normal hysiological range for cows. The high respiratory rate in Jersey cows indicated that they reflected heat bette than other cow breeds (N'Dama, White Fulani and Sokoto Gudali) examined. Key words: Thermoregulatory response, pre-gestating cows, humid tropical environment.

STUDIES ON THE CURATIVE AND PROPHYLACTIC CONCENTRATIONS OF ISOMETAMIDIUM CHLORIDE IN THE TREATMENT OF EXPERIMENTAL Trypanosoma congolense INFECTION IN RED SOKOTO BUCKS

The effectiveness of therapeutic and prophylactic drug concentrations of isometamidium chloride (ISMTX) was studied in Trypanosoma congolense infected Red Sokoto bucks (RSB). Sixteen R.S.B were divided into four groups of four animals each: Group I (1 % ISMTX), Group II (2 % ISMTX), Group III (3% ISMTX) and Group IV (uninfected and untreated-Control). Groups I, II and III bucks were inoculated with approximately 1x10 trypanosomes intravenously each. Parasitemia was monitored on wet-mount and mHCT throughout the study. Clinical signs, rectal temperature, PCV, Total white blood cell count (TWBCC), differential leucocyte count were monitored. Group I, II and III were treated with 1 %, 2%, and 3 % isometamidium chloride at the dose rate of 0.5 mg/kg body weight intramuscularly. 2 % and 3 % ISMTX groups were re-infected post-treatment to test their chemoprophylaxis. Statistical analysis using One way -ANOVA was employed P&lt;0.05 considered significant. The 1% ISMTX had relapse post-treatment while the parasite in 2 % and 3 % ISMTX groups appeared following re-infection. Pale mucous membranes, pyrexia, inappetance, depression, epiphora and nasal discharges were among the clinical signs observed. There was a significant difference (P&lt;0.001) in the daily mean rectal temperature post-infection and post-treatment between the test groups and the control group. A significant difference (P&lt;0.001) in the PCV was also noted in all the three groups post-infection and post-treatment. The TWBCC in all the three test groups differed significantly (P&lt;0.001) post-infection and post-treatment compared with the control group. A significant (P&lt;0.01) lymphopenia was noted post-infection and post- treatment respectively. The 1% isometamidiuim was effective in the treatment of trypanosomiosis according to this study but not curative while the 2 % and 3 % isometamidium chloride were both effective and curative for the period of observation. The chemoprophylaxis of the 2 % and 3 % isometamidium chloride based on this study was five weeks and four weeks respectively.

Observations on the Clinical Effects of Music Therapy on Premature Infants in Neonatal Intensive Care Units.

This study aimed to explore the clinical effects of music therapy (MT) on premature infants in neonatal intensive care units (NICUs). A total of 78 premature infants in NICUs admitted from January 2021 to January 2022 in Wuhan Children's Hospital, Tongji Medical College, and Huazhong University of Science and Technology were selected as the reference group and received routine management. Wuhan Children's Hospital implemented MT from February 2022 to February 2023, and 74 premature infants in NICUs admitted during the same period were selected as the observation group. The corresponding management mode was implemented on the second day of NICU admission for premature infants. Amplitude-integrated electroencephalogram (aEEG) and neonatal behavioral neurological assessment (NBNA) were adopted to evaluate the brain function, specifically the neurological function of neonates, after the end of management. The degree of parent-child attachment was measured using the pictorial representation of attachment measure (PRAM) in a nonverbal (visual) manner. The temperature, pulse, respiratory rate (RR), the number and duration of crying, and incidence of complications were all compared between the two groups. SPSS showed that no difference existed in the aEEG and NBNA scores between the two groups (P > 0.05). The distance of PRAM self-baby-distance was smaller in the observation group compared with the reference group (P < 0.05). Furthermore, there was no significant difference in temperature between the two groups (P > 0.05). The observation group had significantly lower pulse and RR values than the reference group (P < 0.05). Finally, no significant difference existed in the incidence of complications between the two groups (P > 0.05). MT has a certain application value for premature infants in NICUs and can thus be applied to newborns in other NICUs. However, further studies are required to completely verify the research results.

Effect of two-dam coexistence on thermal regime: A special withdrawal measure in Fengman reservoir, China

The Fengman Reservoir in China employs a distinctive approach termed two-dam coexistence to mitigate the risks associated with aging and hazardous dams. This method involves the partial demolition of the old dam and construction of a new dam downstream, which allows the remaining part of the old dam to act as a retaining wall for selective water withdrawal. Through a comprehensive study, long-term water temperature data were analyzed, along with the characteristics of the two-dam coexistence system, to comprehend its effects on thermal stratification in the main basin near the dams and the withdrawal water temperature (WWT) regime. The results revealed that the metalimnion shifted upwards, strengthening stratification, and the temperature gradient expanded from 0–0.9 °C/m to 0–10.5 °C/m compared to that under the one-dam condition. Vertical mixing was reduced, causing the temperature difference between surface and bottom waters to range from 6.8 to 26.8 °C. This enhanced the stratification stability by 1.8 times compared with the one-dam condition, with some annual variability. Thus, the buoyancy frequency decreased accordingly. Furthermore, two-dam coexistence influenced the WWT, resulting in higher WWT during the warming period (averaging 4.3 °C from May to June) and lower WWT during the freeze-up period (averaging 0.1 °C from January to February) than that of the one-dam condition. The most significant temperature difference between the main basin near the old dam and the one near the new dam occurred at the bottom of the reservoir (ranging from 3.5 to 12.0 °C), confirming that the old dam functioned as a retaining wall, allowing the thermal regime to change. Owing to the two-dam coexistence, the withdrawal layer shifted by 20.0 m from near the intake to close to the demolition elevation. These changes in stable stratification and variations in WWT play crucial roles in reservoir management. This study offers practical insights for treating similar aging and hazardous reservoirs and serves as a reference for optimizing water quality management strategies.

Research on temperature distribution in container ship with Type-B LNG fuel tank based on CFD and analytical method

The liquefied natural gas (LNG) fuel tank in a large container ship is loaded with liquid LNG at an ultra-low temperature (-163°C), there is a significant temperature difference in the cargo hold area where the entire fuel tank is located, which will have an important impact on the steel grade design and structural safety of the cargo tank in container ship. This paper develops two heat transfer models using Computational Fluid Dynamics method (CFD method) and an analytical method to analyze the temperature distribution in a large container ship equipped with Type-B LNG fuel tank. These models incorporate the arrangement and heat transfer characteristics of LNG fuel tanks. The temperature field analysis is conducted under typical the environmental conditions specified in the Code for the Construction and Equipment of Ships Transporting Liquefied Gas in Bulk (IGC Code) and the United States Coast Guard Code (USCG Code), based on the CFD method and the analytical method, and the results of temperature field distribution are compared. Additionally, a parametric analysis of the hull temperature field is further carried out, the results show that the thermal conductivity of the insulation layer in LNG storage tanks and the types of the loaded liquid cargo have a limited impact on the final temperature field distribution in hull structure. However, the selection of steel grade in the local structure of the cargo hold, especially in the inner hull part, may lead to significant changes.

Modelling the Smoke Flow Characteristics of a Comprehensive Pipe Gallery Fire with Rectangular Section

In this study, a numerical model of the cable cabin of a comprehensive pipe gallery was established to study the smoke flow diffusion behaviour of a comprehensive pipe gallery fire under a rectangular cross-section. The effects of fire source power (Q = 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 MW) and fire source location (D = 10, 20, 40, 50, 60, 80, 100 m) on the smoke flow characteristics—such as smoke layer height and thickness, longitudinal airflow velocity, and ceiling temperature distribution—were analysed, and the corresponding prediction model was fitted. The results show the following: (1) The height of the smoke layer decreases with increasing fire power, and the predictive model of the smoke layer thickness obtained from the fitting is proportional to the smoke mass flow rate and inversely proportional to the aspect ratio of the pipe gallery. (2) Longitudinal air velocity prediction models of D &lt; 50 m and D ≥ 50 m are fitted, and the average error between them and the numerical simulation values is 9.611%. (3) The temperature decay gradient of the smoke decreases gradually with increasing distance from the fire source, while there is a significant temperature difference between the two sides of the fire source. The average relative errors of the dimensionless temperature rise models fitted upstream and downstream of the fire source in the form of ΔTT0=AeBD−XH+C exponentials with respect to the numerical simulations were 11.688% and 7.296%, respectively. The results of the study can provide a reference for smoke flow and fire prevention and control in comprehensive pipe galleries.

Termografia rozległego zielonego dachu przedszkola w Brno-Komín

The article deals with the behavior of an extensive green roof in winter. The behavior of the green roof of the Kindergarten Brno – Komín is described in the case study. The condition of the roof was determined using thermovisual technology. An extensive green roof shows significant temperature differences in winter compared to roofs without vegetation. The vegetation layer on roofs partially acts as an insulating layer. From this structure, the ventilation shafts and sanitary equipment emerge thermally. As part of thermography, the influence of the revision segment on heat conduction was determined. The overall thermal technical condition was evaluated using a thermal camera.

Observing and identifying fouled ballast bed: On-site testing with infrared thermography (IRT) and uncovering thermodynamic transfer mechanisms within the ballast bed

The ballast bed serves as the foundation of the ballasted track, and its performance is maintained through periodic ballast cleaning. Early detection of fouled ballast bed significantly reduces maintenance workload and capital investment. Some scholars have studied the feasibility of utilizing infrared thermography (IRT) for detecting fouled ballast bed (DBF) and have made some progress. Existing studies have predominantly employed simulated boxes to simulate the ballast bed. To better reflect real-world conditions, this study established two sections of ballast bed on a newly constructed line: one with clean ballast and the other fouled, with a volumetric fouling rate (VFR) of 27.6 % (FI ≈ 21.5 %). Moreover, this paper takes a pivotal step in exploring the thermodynamic transfer mechanisms within the ballast bed, the influences of meteorological factors on the detection effectiveness of IRT, and other detection indicators that could be used for DBF.The results demonstrate that the different void fractions and composition substances of the clean and fouled ballast beds (CFB) contribute to their distinct thermodynamic properties. Furthermore, the high specific heat capacity of water exacerbates the thermodynamic property difference between the CFB. In terms of meteorological factors, both the solar radiation intensity (S) and air temperature (T) have a significant positive impact on the temperature of the ballasted structure (STT) and the temperature difference between the CFB (CF-S). Throughout the day, as the S and T increase, the ballast bed surface absorbs more solar heat than it loses, leading to an increase in its surface temperature. When it exceeds the soil temperature (S-S), heat is transferred downward. Since the poor heat conduction of the clean ballast bed, it has a higher surface temperature. As the S and T decrease, heat convection and conduction become dominant, leading to a decrease in the surface temperature of the ballast bed (BT-S). When the BT-S is lower than the S-S, heat is transferred upward, causing the surface temperature of the fouled ballast bed (F-S) to potentially exceed that of the clean ballast bed (C-S). Furthermore, the humidity (H) has a strong negative impact on the STT, while on sunny days following rain, it has a significantly positive impact on the CF-S. The effects of wind speed (W) on the STT and the CF-S are not prominently observed due to its low values during the experiment. Without considering rainfall, higher S and T, combined with reduced W, result in a greater CF-S and are more conducive to advancing fouling detection. Hence, the CF-S can reach up to about 3 °C on a sunny day and may even rise to about 5 °C after rainfall. Nonetheless, the CF-S is only around 0.71 °C on a cloudy day and 0.25 °C at night. Unexpectedly, there is a significant temperature difference between the sleeper and the ballast bed or the steel rail. These indicators could potentially be used for DBF on cloudy days. Overall, these findings demonstrate the feasibility of using IRT for DBF in the field, provding a broader theoretical support for its advancement and implementation.