Search Results (34)

Lung cancer remains the leading cause of cancer-related mortality worldwide, with early detection critical for improving survival rates, yet conventional methods like CT scans often yield high false-positive rates. This study introduces M-GNN, a graph neural network framework leveraging GraphSAGE, to enhance early lung cancer detection through metabolomics. We constructed a heterogeneous graph integrating metabolomics data from 800 plasma samples (586 cases, 214 controls) with demographic features and Human Metabolome Database annotations, employing GraphSAGE and GAT layers for inductive learning on 107 metabolites, pathways, and diseases. M-GNN achieved a test accuracy of 89% and an ROC-AUC of 0.92, with rapid convergence within 400 epochs and robust performance across ten random seeds; key predictors included age, height, choline, Valine, Betaine, and Fumaric Acid, reflecting smoking and metabolic dysregulation. This framework offers a scalable, interpretable tool for precision oncology, surpassing benchmarks by capturing complex biological interactions, though limitations like synthetic data biases and computational demands suggest future validation with real-world cohorts and optimization. M-GNN advances lung cancer screening, promising improved survival through early detection and personalized strategies. Full article

This study analyzed the temperature characteristics of ceiling jets in corridor spaces by conducting experiments with varying heat release rates and ceiling heights and comparing the results with predictive equations based on the energy conservation equation. The smoke layer formed at a lower height than in open spaces, and the ceiling jet temperature near the wall was higher than that along the central axis. Predictions were generally accurate at a ceiling height of 3.0 m but were overestimated at 1.5 m and underestimated at 4.5 m. The temperature attenuation trend aligned with Oka’s equations, though the temperature near the wall remained higher. Full article

There are obvious differences in shape and space between the large-span spatial structure and the traditional steel structure, and there will be openings at the top of the spatial structure. However, there are few studies on the fire of the spherical dome large space building with openings at the top, which makes the classical plume model inapplicable. The axial temperature of the plume centerline predicted by the traditional plume model is quite different from the real results. Therefore, this paper investigates the temperature dynamics within large-span spatial structures during large-scale fire scenarios, utilizing a combination of theoretical analysis and finite element numerical simulations. It meticulously assesses how different natural ventilation inlet areas affect both the smoke exhaust capacity and the temperature field distribution within these structures. The research expands on the traditional plume model by introducing an enhanced formula for calculating the plume center velocity, specifically designed for large-span structures with top openings. Additionally, using an improved two-region model, the paper derives a logarithmic model that describes the temperature variation as a function of vertical height within the structure. This theoretical model is then compared with numerical simulation results. The study finds that increasing the natural ventilation inlet area significantly enhances the efficiency of smoke exhaust and reduces temperatures within the fire smoke layer of large-span spatial structures. The derived temperature logarithmic curve model shows high precision in predicting the spatial temperature distribution after the fire reaches a quasi-steady state, with an average relative error of 6% between predicted and simulated temperatures, confirming its accuracy. The conclusion is of great significance to the study of fire smoke movement in large-span spatial structures. The obtained logarithmic curve model of temperature under fire provides an important basis for the fire protection design of spherical dome spatial structures under natural smoke exhaust. Full article

Utilizing the intermediate air shaft for smoke exhaust is one of the crucial emergency ventilation methods in metro tunnel fires. To study the impact of metro tunnel slope on smoke exhaust performance of intermediate air shaft, this paper employs numerical simulation to conduct research from the following aspects: the longitudinal distribution of ceiling smoke temperature, visibility distribution, smoke layer height, and the smoke exhaust efficiency of intermediate air shaft. The results demonstrate that as the tunnel slope increases, the maximum ceiling temperature decreases, and the visibility at dangerous height increases. The smoke layer height on the downhill side of a sloped tunnel is higher than that of a horizontal tunnel, while the smoke layer height on the uphill side is lower. Under single-side smoke exhaust mode, the smoke exhaust efficiency of the 2# intermediate air shaft rises as the tunnel slope increases. However, under air supply plus smoke exhaust mode, the smoke exhaust efficiency of the 2# intermediate air shaft decreases with the growing tunnel slope. Full article

Fire is a significant cause of fatalities and property loss. In tall spaces, early smoke dispersion is hindered by thermal barriers, and initial flames with limited smoke production may be obscured by ground-level structures. Consequently, smoke, temperature, and other fire sensor signals are weakened, leading to delays in fire detection by sensor networks. This paper proposes a multi-height and heterogeneous fusion discriminant model with a multilayered LSTM structure for the robust detection of weak fire signals in such challenging situations. The model employs three LSTM structures with cross inputs in the first layer and an input-weighted LSTM structure in the second layer to capture the temporal and cross-correlation features of smoke concentration, temperature, and plume velocity sensor data. The third LSTM layer further aggregates these features to extract the spatial correlation patterns among different heights. The experimental results demonstrate that the proposed algorithm can effectively expedite alarm response during sparse smoke conditions and mitigate false alarms caused by weak signals. Full article

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 < 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 $\frac{\Delta T}{T_0}=A{e}^{B\left(\frac{D-X}{H}\right)+C}$ 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. Full article

Loose-fill thermal composite insulation produced from surface-modified wood scobs has been explored as a potential fire-resistant material for building envelopes. This work involves fire resistance behavior comparisons between four coating systems consisting of liquid glass, liquid glass-tung oil, liquid glass-expandable graphite, and liquid glass-tung oil-expandable graphite. The techniques of thermogravimetric and differential thermogravimetric analyses, gross heat combustion via a calorimetric bomb, cone calorimetry, SEM imaging of char residues, and energy dispersive spectrometry for elemental analysis, as well as propensity to undergo continuous smoldering, were implemented. The coating technique resulted in greater thermal stability at a higher temperature range (500–650 °C) of the resulting loose-fill thermal composite insulation, reduced flame-damaged area heights after the exposure of samples at 45° for 15 s and 30 s, with a maximum of 49% decreased gross heat combustion, reduced heat release and total smoke release rates, improved char residue layer formation during combustion and changed smoldering behavior due to the formation of homogeneous and dense carbon layers. The results showed that the highest positive impact was obtained using the liquid glass and liquid glass-expandable graphite system because of the ability of the liquid glass to cover the wood scob particle surface and form a stable and strong expanding carbon layer. Full article

Wildfires pose a direct threat to the property, life, and well-being of the population of Montana, USA, and indirectly to their health through hazardous smoke and gases emitted into the atmosphere. Studies have shown that elevated levels of particulate matter cause impacts to human health ranging from early death, to neurological and immune diseases, to cancer. Although there is currently a network of ground-based air quality sensors (n = 20) in Montana, the geographically sparse network has large gaps and lacks the ability to make accurate predictions for air quality in many areas of the state. Using the random forest method, a predictive model was developed in the Google Earth Engine (GEE) environment to estimate PM2.5 concentrations using satellite-based aerosol optical depth (AOD), dewpoint temperature (DPT), relative humidity (RH), wind speed (WIND), wind direction (WDIR), pressure (PRES), and planetary-boundary-layer height (PBLH). The validity of the prediction model was evaluated using 10-fold cross validation with a R² value of 0.572 and RMSE of 9.98 µg/m³. The corresponding R² and RMSE values for ‘held-out data’ were 0.487 and 10.53 µg/m³. Using the validated prediction model, daily PM2.5 concentration maps (1 km-resolution) were estimated from 2012 to 2023 for the state of Montana. These concentration maps are accessible via an application developed using GEE. The product provides valuable insights into spatiotemporal trends of PM2.5 concentrations, which will be useful for communities to take appropriate mitigation strategies and minimize hazardous PM2.5 exposure. Full article

To investigate the fire risk in a complex tunnel with varying cross-sections, sloped structures, and dense upper cover beams, this study considered four fire source positions: the immersed tube section, confluence section, highway auxiliary road section, and four-lane sections of the main line. It also considered four beam spacings: 1 m, 1.8 m, 3.6 m, and 7.2 m. The Fire Dynamics Simulation Software FDS was utilized to create a comprehensive tunnel model. The analysis focused on temperature and visibility changes at a 2 m height under a 20 MW fire condition for different fire source positions. These changes were then compared with critical danger values to assess the safety of evacuating personnel within the tunnel. Subsequently, this study proposed corresponding emergency rescue strategies. The findings indicated that when the beam grid spacing exceeded 3.6 m, the upper dense beam gap showed a robust smoke storage capacity, leading to a reduced distance of high-temperature smoke spread. However, this increased smoke storage disrupted the stability of the smoke layer, resulting in a heightened smoke thickness. The location of the ventilation vent at the entrance of the immersed tunnel section caused a non-uniform ventilation flow under the girder, deflecting the smoke front towards the unventilated side and decreasing visibility in the road auxiliary area. In comparison to scenarios without a beam lattice, the presence of a beam lattice in the tunnel amplified fire hazards. When the beam lattice spacing was 3.6 m or greater, the extent of the hazardous environment, which is unfavorable for personnel evacuation, expanded. With the exception of the scenario where the fire source was located in the highway auxiliary roadway, all other conditions surpassed 150 m, which is roughly one-third of the tunnel length. Consequently, more targeted strategies are necessary for effective evacuation and rescue efforts. Full article

The aerosol layer height (ALH) is an important parameter that characterizes aerosol interaction with the environment. An estimation of the vertical distribution of aerosol is necessary for studies of those interactions, their effect on radiance and for aerosol transport models. ALH can be retrieved from satellite-based radiance measurements within the oxygen absorption band between 760 and 770 nm ($O_2$A band). The oxygen absorption is reduced when light is scattered by an elevated aerosol layer. The Ocean and Land Colour Imager (OLCI) has three bands within the oxygen absorption band. We show a congruent sensitivity study with respect to ALH for dust and smoke cases over oceans. Furthermore, we developed a retrieval of the ALH for those cases and an uncertainty estimation by applying linear uncertainty propagation and a bootstrap method. The sensitivity study and the uncertainty estimation are based on radiative transfer simulations. The impact of ALH, aerosol optical thickness (AOT), the surface roughness (wind speed) and the central wavelength on the top of atmosphere (TOA) radiance is discussed. The OLCI bands are sufficiently sensitive to ALH for cases with AOTs larger than 0.5 under the assumption of a known aerosol type. With an accurate spectral characterization of the OLCI $O_2$A bands better than 0.1 nm, ALH can be retrieved with an uncertainty of a few hundred meters. The retrieval of ALH was applied successfully on an OLCI dust and smoke scene. The found ALH is similar to parallel measurements by the Tropospheric Monitoring Instrument (TROPOMI). OLCI’s high spatial resolution and coverage allow a detailed overview of the vertical aerosol distribution over oceans. Full article

Fire smoke decontamination equipment, such as fire-fighting robots and smoke exhaust robots, is mainly used in long and narrow spaces such as underground garages. In several recent decades, the study of fire smoke spread in narrow spaces and fire smoke decontamination equipment stimulated the interests of many researchers. However, present equipment cannot eliminate insoluble toxic gases such as CO and may decrease the height of the smoke layer, causing great difficulty to rescue. In this study, a novel mobile fire smoke decontamination process and system are proposed. The experimental study and theoretical prediction of the system are conducted. The results show that the developed equipment is able to eliminate fire smoke particles and CO, cool the space, and improve the visibility of the fire site. The developed equipment can reduce the space temperature to below 60 °C, reduce the CO concentration to below 145 ppm, and enhance the visibility to more than 50 m in the rectangular tunnel after operating for 30 min under 4 MW fire condition. Full article

The smoke layer height in the ship engine room under forced ventilation has been experimental and theoretical investigated in this work. A series of test were carried out in a scaled engine cabin experimental platform to obtain the influence of air supply volume and air inlet height on the burning parameters, including the mass loss rate, smoke temperature, etc. The research results show that under the experimental conditions, the fire source mass loss rate increases exponentially, and smoke layer height also increases gradually with the increase in the air supply volume. The empirical formula of smoke layer height under different air supply conditions was given. Then, a prediction model of smoke layer height under different forced ventilation conditions was constructed through theoretical analysis based on conservation equations. Within the range of experimental air volume and air inlet height, the relative error between theoretical prediction results and experimental results was less than 11%, which could effectively predict the smoke layer height in the ship cabin fire. Full article

Lidar measurements of 11 smoke layers recorded at Măgurele, Romania, in 2014, 2016, and 2017 are analyzed in conjunction with the vegetation type of the burned biomass area. For the identified aerosol pollution layers, the mean optical properties and the intensive parameters in the layers are computed. The origination of the smoke is estimated by the means of the HYSPLIT dispersion model, taking into account the location of the fires and the injection height for each fire. Consequently, for each fire location, the associated land cover type is acquired by satellite-derived land cover products. We explore the relationship between the measured intensive parameters of the smoke layers and the respective land cover of the burned area. The vegetation type for the cases we analyzed was either broadleaf crops or grasses/cereals. Overall, the intensive parameters are similar for the two types, which can be associated with the fact that both types belong to the broader group of agricultural crops. For the cases analyzed, the smoke travel time corresponding to the effective predominant vegetation type is up to 2.4 days. Full article

This paper presents work on investigating the effect of the initial size of water mist droplets on the evaporation and removal of heat from the fire-induced hot gas layer while travelling through the air in a compartment. The histories of the temperature, diameter and position of droplets with different initial diameters (varied from 100 µm to 1000 µm) are determined considering surrounding air temperatures of 75 °C and 150 °C and a room height of 3.0 m. A water droplet evaporation model (WDEM) developed in a previous study (Fire and Materials 2016; 40:190–205) is employed to navigate this work. The study reveals that tiny droplets (for example, 100 µm) have disappeared within a very short time due to evaporation and travelled a very small distance from the spray nozzle because of their tiny size. In contrast, droplets with a larger diameter (for example, 1000 µm) reached the floor with much less evaporation. In the case of this study, the relative tiny droplets (≤200 µm) have absorbed the highest amount of energy from their surroundings due to their complete evaporation, whereas the larger droplets have extracted less energy due to their smaller area/volume ratios, and their traverse times are shorter. One of the key findings of this study is that the smaller droplets of spray effectively cool the environment due to their rapid evaporation and extraction of heat from the surroundings, and the larger droplets are effective in traversing the hot air or smoke layer and reaching the floor of the compartment in a fire environment. The findings of this study might help in understanding the behaviour of water-mist droplets with different initial diameters in designing a water-mist nozzle. Full article

In this study, a series of numerical simulations were carried out to investigate the effect of fire shutter descending height on the smoke extraction efficiency in a large space atrium. Based on the full-scale fire experiments, this paper carried out more numerical simulations to explore factors affecting the smoke extraction efficiency in the atrium. The smoke flow characteristics, temperature distribution law and smoke extraction efficiency of natural and mechanical smoke exhaust systems were discussed under different heat release rates and fire shutter descending heights. The results show that the smoke spread rate and the average temperature of the smoke are higher with a greater heat release rate. After the mechanical smoke exhaust system is activated, the smoke layer thickness and smoke temperature decrease, and the stable period of heat release rate is shorter. In the condition of natural smoke exhaust, the smoke extraction efficiency increases exponentially with the increase of heat release rate and the descending height of the fire shutter, and the maximum smoke extraction efficiency is 48.8%. In the condition of mechanical smoke exhaust, the smoke extraction efficiency increases with the increase of mechanical exhaust velocity. When the velocity increases to the critical value (8 m/s), the smoke extraction efficiency is essentially stable. The smoke extraction efficiency is increased first with the increase of fire shutter descending height and then has a downward trend when the descending height drops to half, and the maximum smoke extraction efficiency is 70.3% in the condition of mechanical smoke exhaust. Empirical correlations between the smoke extraction efficiency and the dimensionless fire shutter descending height, the dimensionless heat release rate and the dimensionless smoke exhaust velocity have been established. The results of this study can provide a reference for the design of smoke prevention and exhaust systems in the atrium. Full article