Search Results (695)

Forest fires cause societal damage, including injuries, burns, and the development and exacerbation of cardiorespiratory diseases. One of the damaging factors of forest fires is carbonaceous particles heated up to high temperatures. These particles are carried from the forest fire front and can interact with human tissue. Three scenarios for the interaction of a heated carbonaceous particle with human tissue are considered. The first scenario involves particle impact on the skin. The second scenario involves particle impact on the nasopharyngeal mucosa. The third scenario involves the impact on the tissues of the upper airways. A two-dimensional mathematical statement is considered in the “carbonaceous particle–human tissue” system. Mathematically, the heat transfer process is described by non-stationary parabolic partial differential equations with corresponding initial and boundary conditions. The problem is solved using locally one-dimensional and finite-difference methods. Difference analogs of the differential equations are solved using the marching method. Temperature distributions for particles of varying sizes and initial heat contents were obtained. The software realization was implemented using the high-level Object Pascal programming language in the RAD Studio environment. Conclusions were drawn regarding the potential practical applications of the developed software in healthcare and environmental protection. Full article

A vortex reducer is employed to reduce the pressure drop during the radially inward air bleeding process in aero-engines. The vortex reducer with deswirl nozzles (DVR) has the advantage of structural robustness; however, its complex, non-monotonic flow rate–pressure drop characteristic limits its widespread application. In an effort to resolve this issue, the current study employs both experimental and numerical methodologies to investigate the effects of nozzle geometric parameters on the flow characteristics of the DVRs, which are currently deficient. The findings indicate that, irrespective of variations in nozzle radial position or flow area, an elevation in the design point flow rate invariably results in an augmented pressure drop, and this coupling effect cannot be circumvented by modifying the geometric parameters. When the nozzle radial position is lowered to below b₁ = 130 mm or the flow area is reduced to below d₂ = 1.19 mm, the flow characteristic of the DVRs becomes monotonic; nevertheless, due to the severely limited flow capacity, such a monotonic characteristic lacks practical engineering significance. Therefore, both the nozzle radial position and the flow area should be regarded as separate independent variables in optimization calculations during the design process, necessitating the development of a rapid and accurate low-dimensional model. Full article

While double-layer insulation structures are widely adopted, their thermal performance is critically dependent on the thermophysical behavior of the interstitial air cavity, a variable often oversimplified in current design practices. This article moves beyond generic material descriptions to investigate the specific mechanism of heat transfer transition within sealed air gaps sandwiched between graphite polystyrene boards. The innovation of this experiment lies in the rigorous isolation of air gap thickness as the primary independent variable within a 1 × 1 × 1 m closed building model, instrumented with high-precision GPRS temperature and humidity sensors to capture real-time thermal gradients under the authentic climate conditions of Anyang, Henan. The results demonstrate a non-monotonic relationship between gap thickness and effective thermal resistance, governed by the competition between molecular conduction and buoyancy-driven natural convection. Specifically, the data validates that a 20 mm air gap represents the statistically significant optimum, thereby maximizing insulation efficiency while minimizing radiative heat loss. Using this optimized structure reduces steady-state heat flux compared to monolithic equivalents and aligns with the energy conservation target. Unlike previous studies limited by simulation assumptions or short-term testing, this research provides empirically verified, long-term field data that bridges the gap between theoretical fluid dynamics and practical building envelope engineering. These findings offer a robust, physics-based reference for optimizing double-layer insulation systems in the Central Plains, directly supporting the low-carbon retrofitting of existing building stocks. Full article

Early microbial exposure during embryogenesis may shape post-hatch gut development in poultry, yet the effects of sublethal pathogenic exposure and in ovo synbiotics remain unclear. This model-establishment study preliminarily established in ovo Salmonella Enteritidis (SE) infection and synbiotic (SYN) delivery models and evaluated their effects on hatchability, cecal microbiota, intestinal morphology, epithelial turnover, and barrier function in newly hatched chicks. In one group, the air cells of specific pathogen-free White Leghorn eggs were injected with SE on embryonic day 12; in another group, a synbiotic consisting of Lactobacillus plantarum, Pediococcus acidilactici, and inulin was injected into the amniotic cavity on embryonic day 17.5. Sterile saline was injected as the vehicle-only procedural control at the corresponding time points and injection sites. Based on their impacts on hatchability, SE1-L and SYN-H were selected. SE1-L reduced cecal microbial diversity, expanded Proteobacteria and Escherichia–Shigella, increased ileal apoptosis and crypt depth, decreased the villus height-to-crypt depth ratio, downregulated jejunal tight-junction genes, upregulated ileal MYD88 and TNF-α, and increased plasma lipopolysaccharide and D-lactate. In contrast, SYN-H maintained hatchability, promoted early Pediococcus colonization, suppressed potential pathogens, increased ileal villus height and villus height-to-crypt depth ratio, enhanced proliferation, reduced apoptosis, and improved mucosal barrier-related indices. These findings provide preliminary evidence that embryonic SE infection and synbiotic delivery differentially influence early intestinal microbiota succession and gut development in newly hatched chicks. Full article

Textile membrane systems are increasingly used in sports halls because of their low structural weight, rapid assembly, and ability to span large areas. Their operational performance, however, is strongly affected by local climate conditions, envelope configuration and the limited thermal inertia of membrane materials. This study presents a comparative EnergyPlus-based assessment of textile membrane sports halls in six representative climate contexts: Helsinki, Berlin, Niš, Barcelona, Dawadmi and Bangkok. A conventional masonry hall was used as the reference case and compared with a single-layer PVC-coated polyester membrane system and double-layer membrane systems with air gaps of 0.4, 0.5 and 0.6 m, including mechanically ventilated air-cavity variants. The assessment combines four performance indicators: annual operational energy demand, carbon emissions, indicative global cost and thermal comfort expressed through Fanger’s Predicted Percentage of Dissatisfied (PPD) index. The results show that the dominant energy demand is climate-dependent, with heating prevailing in cold climates and cooling becoming decisive in hot-arid and hot-humid climates. Double-layer cases usually show lower operational energy demand and lower associated carbon dioxide emissions than the single-layer membrane case. This improvement, however, is not uniform; it depends on the climatic setting and on the width of the air gap. The comfort results lead to a similar but more limited conclusion. Although PPD is reduced in the double-layer configurations, the values remain above conventional comfort acceptance levels in all tested cases. The double-layer membrane should therefore be understood as a measure that reduces thermal dissatisfaction, not as a complete comfort solution. The economic assessment indicates that membrane systems have substantially lower initial capital costs than masonry construction, while their long-term performance depends on operational energy costs, membrane replacement assumptions and the selected analysis horizon. The study provides a climate-specific comparative framework for early-stage envelope selection in textile membrane sports halls, emphasizing that energy demand, carbon emissions, cost and thermal comfort should be considered together rather than as separate outputs. Full article

Cavity flame holders are core stabilization components for Ma 1.6 low-supersonic scramjet combustors, where the axial location of upstream fuel injection significantly affects fuel-air mixing, flame holding, and combustion performance. Two four-orifice injection schemes (Far-Upstream Injection, FUI: 30 mm upstream of cavity leading edge (CLE); Near-Upstream Injection, NUI: 10 mm upstream of CLE) were experimentally studied under Ma 1.6 inflow ($T_0=660 \mathrm{K}, \varphi =0.2$) via synchronized high-speed schlieren and CH* chemiluminescence diagnostics. Results showed that FUI produced greater cold-flow jet penetration, but generated stronger shock structures and flow instabilities. Under combustion, the penetration gap between schemes narrowed substantially due to heat-release-induced thermal expansion, with NUI benefiting more. NUI achieved superior flame stabilization, uniform full-cavity heat release, and suppressed combustion instability through broadband flow fluctuations, whereas FUI exhibited a high-energy discrete dominant frequency and flame oscillation. Full article

This work investigates heat transfer experimentally and numerically within a ventilated cavity, both with and without an internal heat source, simulating a room with a person at the interior at 1:3 scale. This setup has applications in building energy systems, cooling of electronic equipment, solar energy collectors, etc. The experimental configuration consists of a cube in which the left vertical wall is subjected to a uniform heat flux, and the opposing wall is maintained at a constant temperature. A rectangular parallelepiped heat source was placed inside. The remaining walls are thermally insulated, and air is the thermal fluid. Air enters and exits through square ports on the top surface. Experimental temperature profiles were recorded at multiple depths and heights. Corresponding numerical results for temperature fields, flow patterns, turbulent viscosity, and turbulent kinetic energy were generated using the Ansys Fluent 18 CFD software, with six turbulence models assessed against experimental data under steady-state conditions. A key finding is that the Nusselt number and the convective heat transfer coefficients (average) for the hot wall remain negligibly affected by the incorporation or status (on/off) of a heat source at the interior of the cavity, the biggest temperature difference (experimental vs numerical) corresponds to the rkε model with 6.2% when there is no thermal source in the cavity and the lowest difference for the average convective heat transfer coefficient is with the rslrso model with 5.2%. Full article

At present, research on the long-term stability of multi-cavern coordinated injection–production operations for salt cavern compressed air energy storage (CAES) remains limited. Large-capacity energy storage utilizing multiple interconnected salt caverns has become an inevitable development trend for modern CAES power stations, highlighting the necessity and importance of stability evaluation and design optimization for underground salt cavern storage clusters. Based on the Anning 350 MW CAES demonstration project, this paper takes the abandoned salt caverns of the project as research objects. A three-dimensional geological and cavern model is established using the FLAC3D numerical simulation method, and stability analysis is carried out under static conditions and three long-term gas injection and production scenarios (the pressure conditions are provided by ground-based equipment). The characteristics of the plastic zone, displacement, stress distribution, and volume shrinkage of the caverns are systematically investigated. The results show that under static conditions, the internal pressure significantly controls the development of the plastic zone, and the caverns are generally stable at pressures above 4 MPa. During long-term operation, the plastic zones of each cavern gradually expand, displacements accumulate continuously, and stresses tend to stabilize after an initial accumulation period. After 30 years of operation, no through-going plastic zones appear in any cavern, and all volume shrinkage rates are below 30%. Among the three cases, Case 1 exhibits the best stability, while enhanced monitoring is required for local high-stress regions in Case 3. This study verifies that the salt cavern development for the Anning CAES project is safe and controllable during long-term operation. The layout spacing of caverns is reasonably designed and fully satisfies the stability requirements of salt cavern CAES power stations. The research results can provide a technical guarantee for the construction of the first CAES power station in Yunnan Province and also offer a reliable reference for the design and construction of similar multi-cavity salt cavern CAES projects. Full article

Syrian hamsters (SHs) are widely used in research and as pets. However, their head anatomy has not yet been evaluated using sectional anatomy and imaging despite their unique features, which are important for studying ischemia–reperfusion injury, cancer, oral tumors, and common stomatognathic and ocular conditions. This study was conducted to correlate the planar anatomy of the heads of eight healthy male and female SHs with micro-CT and MRI images to establish a descriptive, imaging-based anatomical reference. Clinically important head structures observed in transverse, dorsal, and sagittal anatomical sections were correspondingly identified on micro-CT and/or MRI images. In SHs, head micro-CT was shown to be particularly effective for visualizing mineralized structures (e.g., dental and osseous tissues) and air-filled cavities (e.g., the ear canal and tympanic bulla), whereas MRI was demonstrated to provide superior assessment of soft tissues, including the brain, vertebral canal and spinal cord, musculature, intervertebral disks, major salivary glands, eye, and harderian and extraorbital lacrimal glands. The present investigation provides a descriptive and imaging-based anatomical reference of the SH head by integrating anatomical sections, in situ topographical anatomy, and dry-skull photographs with micro-CT and MRI datasets, thereby serving as a foundational resource for the interpretation of cross-sectional imaging in both research and clinical contexts. Full article

In extremely cold environments, inhaling frigid, dry air can pose significant health risks, potentially leading to airway inflammation and respiratory injury. While previous studies have examined thermal exchange within lung airways under hot-air inhalation, the majority have focused on localized regions rather than the entire respiratory tract. This study expands the scope of inquiry by simulating airflow and heat transfer throughout a more complete computed tomography (CT)-based respiratory tract, from the nasal cavity to the larynx and trachea and extending down to the 13th generation of the bronchial tree, under two cold-air inhalation scenarios at −5 °C and −20 °C. Using computational fluid dynamics, this study integrates Large Eddy Simulation with the Smagorinsky–Lilly subgrid-scale model to capture the complex interaction of turbulent flow and thermal transport in the human respiratory system. By analyzing temperature distributions, heat flux, heat-transfer coefficients, Nusselt numbers, and mass flux across the airways, the research shows how varying degrees of cold inhalation influence respiratory thermodynamics and associated biomechanical responses. As such, this study establishes a rigorous scientific foundation for the development of more sophisticated and predictive respiratory-tract models in sub-zero environments in future work. Full article

Salt cavern Compressed Air Energy Storage (CAES) is one of the critical technologies for energy storage and an important infrastructure supporting the construction of new power systems and facilitating the achievement of the dual carbon goals. The salt rock resources in China are primarily composed of continental strata salt rocks, characterized by high heterogeneity, well-developed thin-layer interbedding, dissolution resistance among different lithologies, and significant creep variations. These features, to some extent, limit the improvement of wellbore construction accuracy, the reliability of abandoned well sealing, the safety of natural gas storage operations, and enhancements in gas injection–brine displacement efficiency. This study takes the continental bedded salt rock in the Dawenkou Basin as the research object and adopts a method combining theoretical analysis and field engineering verification to improve the systematic construction technology system, covering the whole process of drilling engineering, abandoned well plugging, the design of an injection and brine extraction device, and gas injection and brine drainage. The research results optimize four key technologies, including precise wellbore trajectory control, dual-section milling, and multi-stage redundant plugging of abandoned wells and long-term anti-corrosion completion with laser cladding, and dual-mode adaptive gas injection and brine drainage, and improve the technical system from wellbore construction to salt cavity formation. This study can provide valuable theoretical references and engineering demonstration guidance for underground space development projects in similar salt basins in China. Full article

Plastic injection molding in cleanrooms involves high thermal loads and strict particle limits. The hot surfaces of the injection molding machine and peripherals increase the cooling demand of the heating, ventilation, and air conditioning system to an undefined amount. Moreover, the generation of buoyancy-driven plumes has the potential to disturb the cleanroom airflow around the injection mold, thereby risking cross contamination of the manufactured components. The present study quantifies the global heat load of injection molding machines in an ISO Class 7 cleanroom with a laminar flow microenvironment around the mold. Therefore, a measurement-based method to determine the heat load of a complete injection molding production cell is applied to a hydraulic and an electric machine. This method revealed that the heat load of the isolated machines is process-independent, whereas the total heat load of the complete production cell scales linearly with mold temperature. Moreover, the emitted heat to the cleanroom is considerable lower than the injection molding machine’s installed power. Secondly, the airflow regime and particle transport in the mold area are analyzed. This is achieved by means of schlieren visualization and aerosol measurements. The introduction of a modified Archimedes number, incorporating mold size and convective heat flux, has led to the observation of a correlation between flow regimes and the resulting particle load. This enables the selection of case-dependent FFU velocities that deviate from the conventional recommendation of an air speed of 0.45 m/s ± 20%. Despite the presence of a filter-fan unit, the particle load near the injection mold cavity increases for flow conditions that exceed a critical Archimedes number. Full article

In indoor thermal analyses, the effect of humid air as a radiatively participating medium that absorbs and emits energy is often neglected. This simplification can underestimate important values in the results. This study presents a numerical investigation of the humid air that participates radiatively in the conjugate heat and mass transfer convection into a room modeled as a two-dimensional square cavity with a semitransparent wall (glass). The governing equations for mass, momentum, energy, species transport, turbulence, and radiative heat transfer were solved using the Finite Volume Method and coupled with the SIMPLEC algorithm. Two scenarios were analyzed: a radiatively participating medium (RPM) and a non-participating medium (NPM), under two climatic conditions (hot and cold). Results show that considering the radiatively participating medium breaks the symmetric patterns observed in the case of NPM. The energy absorbed by humid air enhances turbulent viscosity, buoyant forces, and indoor temperature. Humid air absorbs approximately 30–32% of the incident energy entering the enclosure. Finally, a correlation for the average temperature is proposed. The results provide insight into the influence of radiatively participating humid air on indoor-like thermal behavior. The study focuses on the analysis of fundamental transport mechanisms. Full article

Noise is an environmental factor that negatively affects the health of living organisms and must therefore be mitigated. One effective approach to noise reduction is the use of passive materials for sound absorption. Moreover, with the increasing use of 3D printing technology, it is now possible to produce complex material structures for noise reduction that cannot be manufactured using conventional manufacturing techniques. This study investigates the sound absorption performance of novel 3D-printed concentric tubular structures made of acrylonitrile styrene acrylate (ASA) with intermediate lattice inserts. The sound absorption properties of these structures were experimentally evaluated in the frequency range of 200–1600 Hz using a two-microphone acoustic impedance tube. Various factors influencing sound absorption properties were investigated, including the number of concentric tubes, sample height, strut diameter, and back air cavity thickness. The experimental results show that the sound absorption performance depends significantly on the design parameters of the proposed system. The average sound absorption coefficient (α_avg) increased with the number of concentric tubes and reached a maximum value of 0.264 for the configuration with five tubes. The highest sound absorption peak (α_max = 0.623) was achieved for the structure with two concentric tubes, a strut diameter of 3 mm, a height of 30 mm, and a back air cavity of 10 mm at a frequency of approximately 1548 Hz. Furthermore, increasing the strut diameter and sample height generally improved sound absorption performance, while the presence of a back air cavity significantly shifted the absorption peak toward lower frequencies, thereby enhancing low-frequency sound absorption. Full article

In this work, a Fabry–Perot (F–P) antenna based on metal integrated suspended lines (MISLs) at the K-band for microwave wireless power transmission (MWPT) is proposed. The antenna’s contribution lies in its adaptation of the MISL structure and its all-metal design, which achieves low loss, high gain, and high-power capability. The entire antenna structure is dielectric-free, further reducing apparent dielectric loss at high frequencies. Meanwhile, the radiation structure is surrounded by a metallic wall to minimize radiation loss. A metal partially reflective surface (PRS) on the top of the antenna, together with a metal ground plane, constitutes an air-filled resonant cavity. The reflection and transmission of electromagnetic waves in the PRS are effectively controlled to be in phase, thereby enhancing its gain by optimizing the PRS and resonant cavity dimensions. A simple slot antenna is employed as the primary source for the F–P resonant cavity. The antenna is processed layer by layer and then assembled to lower machining costs and complexity. Experimental results indicate that the proposed F–P antenna achieves an aperture efficiency over 60% and a measured peak gain of 18.4 dBi at 23.85 GHz with an aperture size of 2.86 λ₀ × 2.86 λ₀. Full article