Search Results (655)

Based on a realistic three-dimensional geometric model, this study numerically investigates the influence of yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) on the aerothermal performance of an annular combustor by employing a conjugate heat transfer (CHT) and non-premixed reactive flow coupling approach. Considering the inner and outer liners, double-wall exhaust bends, and the full configuration of cooling holes, two cases—with and without the TBCs—were analyzed. The results reveal that the application of TBCs markedly modifies the near-wall flow structures and heat transfer characteristics. The cooling air mass flow rate decreases from 0.1211 kg/s to 0.1023 kg/s, corresponding to a 15.5% reduction in cooling load. The main recirculation zone becomes more compact, with enhanced vortex intensity, smoother velocity distribution, and improved flame stability. The high-temperature core region extends further downstream, and the peak temperature increases by approximately 80–100 K, indicating more complete combustion and greater heat retention. The outlet temperature distribution factor (OTDF) decreases from 57.34% to 44.48%, leading to a 22.4% improvement in temperature uniformity. The average wall temperatures of the inner liner, outer liner, and exhaust bend decrease by 3.7%, 8.8%, and 7.5%, respectively, with local peak reductions exceeding 250 K. The study demonstrates that the YSZ TBCs enhances the combustor’s thermal protection capability, flow stability, and temperature uniformity through a coupled mechanism of “thermal insulation–flow reconstruction–energy redistribution.” It should be noted that this study considers only the effect of the ceramic top coat of the TBCs, excluding the metallic bond coat and the thermally grown oxide (TGO) layer. Full article

Ensuring the purity of water sources is a paramount global challenge, necessitating the development of highly sensitive and rapid detection technologies. In this work, a novel Zeonex-based photonic crystal fiber (PCF) sensor is designed and numerically analyzed for the effective differentiation of pure and polluted water by identifying their unique fingerprints in the terahertz (THz) spectrum. The proposed structure features a rectangular core for analyte infiltration, surrounded by a unique hybrid cladding, meticulously engineered with four inner “mode-shaping” rectangular air holes and an outer “confinement” ring of elliptical air holes. This complex topology is strategically designed to maximize the core-power fraction while ensuring robust mode confinement, enabling the exceptional performance metrics observed. The guiding properties and sensing performance of the sensor are rigorously scrutinized using the Finite Element Method (FEM) over a broad frequency range of 0.5 to 3 THz, accommodating analytes with refractive indices from 1.33 to 1.46. This range is specifically chosen to cover the refractive index of pure water (≈1.33) and a broad spectrum of common chemical and biological pollutants. The simulation results demonstrate the exceptional performance of the sensor. For polluted water, the sensor achieves an ultra-high relative sensitivity of 99.6% with a negligible confinement loss of 1.4 × 10⁻¹¹ dB/m at an operating frequency of 3 THz. In contrast, pure water exhibits a high sensitivity of 96% and a confinement loss 9.4 × 10⁻⁶ of dB/m at the same frequency, showcasing a remarkable capability to distinguish between different water qualities. The superior sensitivity, extremely low loss, and structurally feasible design make the proposed PCF sensor an up-and-coming candidate for real-time water quality monitoring within the THz domain. Full article

Thin films of nickel oxide (NiO) were deposited on a 5° miscut magnesium oxide (MgO)(100) substrate using electron-beam evaporation to pursue morphology-directed resistive switching. The atomic force microscope (AFM) confirmed a stepped surface with a terrace width of ~85 nm and a step height of ~7 nm. After deposition, the film resistance decreased from 200 MΩ to 25 MΩ by annealing under ambient air at 400 °C, attributed to the increase in the p-type conductivity through nickel vacancy formation. Top electrodes of Ag (500 nm width, 180 nm gap) were patterned parallel or perpendicular to the substrate steps using UV and electron-beam lithography. Devices aligned parallel to the step showed reproducible unipolar switching with 100% yield between forming voltages 20–70 V and HRS/LRS~10² at ±5 V. In contrast, devices formed perpendicular to the steps (8/8) subsequently failed catastrophically during electroforming, with scanning electron microscopy (SEM) showing breakdown holes on the order of ~100 nm at the step crossings. The anisotropic electrodynamic response is due to step-guided electric field distribution and directional nickel vacancy migration, illustrating how substrate morphology can deterministically influence filament nucleation. These results highlighted stepped MgO as a template to engineer the anisotropic charge transport of NiO, exhibiting a reliable ReRAM as well as directional electrocatalysis for energy applications. Full article

To optimize the corrosion mitigation process in the annular space of oil and gas well pipelines, this study introduces a secondary acceleration pneumatic conveying device for particles within the confined spaces of offshore oil and gas wells. This approach addresses the limitations of traditional offshore hydraulic transportation, which can lead to corrosion failure of drug particles. The study investigates the motion mechanisms of drug particles within the pipeline and identifies the critical structural parameters that influence the smooth transport of these particles. A DEM-CFD coupled simulation methodology was employed to conduct single-factor experiments on the minimum air pressure and particle injection quantity required for stable transportation. The results demonstrate that at an air pressure of 0.25 MPa, no particle retention or accumulation occurs within the pipeline, thereby satisfying the engineering requirements. A Box–Behnken three-factor, three-level experimental design was used to perform response surface analysis on the pneumatic device. The findings reveal that the particle outlet velocity initially increases and then decreases with the air injection angle, while the outlet velocity progressively increases with the diameter of the conveying hole and the number of small holes. The maximum outlet velocity achieved is 8 m/s, with the optimal structural parameters identified as an air injection hole diameter of 2.96 mm, an air injection angle of 47°, and 24 small holes. The simulation model was calibrated and validated through fluidized bed experiments, and the simulation optimization was further confirmed via bench-scale particle transportation tests. This research provides a theoretical framework and engineering guidance for optimizing pneumatic particle transport in the confined spaces of offshore oil and gas wells. Full article

A new criticality indicator for Water Distribution Networks (WDNs) is presented. The new indicator is based on the minimum pressure (MP) model, which relies on the assumption that air can enter the pipes, e.g., when failure occurs in water scarcity scenarios, and maintain a minimum pressure equal to zero in the whole network. The proposed indicator properly integrates topological features, provided by structural hole theory, with the hydraulic constraints provided by the WDN steady-state solution, with a particular focus on pipes where occurring free surface flow leads to a serious reduction in the quality of the network service. The new indicator leads to a new criterion for the prioritized maintenance of pipes in existing networks, as well as for the design and planning of new ones, which is different from the one derived from other popular indicators. Three real-life WDNs are selected as test cases. Full article

Nitrogen oxides (NO_x) are major atmospheric pollutants, and their escalating emissions, driven by rapid economic development and urbanization, pose a severe threat to both the ecological environment and human health. Conventional denitrification technologies are often hampered by high costs, significant energy consumption, and stringent operational conditions, making them increasingly inadequate in the face of tightening environmental regulations. In this context, photocatalytic technology, particularly systems based on graphitic carbon nitride (g-C₃N₄), has garnered significant research interest for NO_x removal due to its visible-light responsiveness, high stability, and environmental benignity. To advance the performance of g-C₃N₄, numerous modification strategies have been explored, including morphology control, elemental doping, defect engineering, and heterostructure construction. These approaches effectively broaden the light absorption range, enhance the separation efficiency of photogenerated electron-hole pairs, and improve the adsorption and conversion capacities for NO_x. Notably, constructing heterojunctions between g-C₃N₄ and other materials (e.g., metal oxides, noble metals, metal–organic frameworks (MOFs)) has proven highly effective in boosting catalytic activity and stability. Furthermore, the underlying photocatalytic mechanisms, encompassing the generation and migration pathways of charge carriers, the redox reaction pathways of NO_x, and the influence of external factors like light intensity and reaction temperature, have been extensively investigated. From an application perspective, g-C₃N₄-based photocatalysis demonstrates considerable potential in flue gas denitrification, vehicle exhaust purification, and air purification. Despite these advancements, several challenges remain, such as limited solar energy utilization, rapid charge carrier recombination, and insufficient long-term stability, which hinder large-scale implementation. Future research should focus on further optimizing the material structure, developing greener synthesis routes, enhancing catalyst stability and poison resistance, and advancing cost-effective engineering applications to facilitate the practical deployment of g-C₃N₄-based photocatalytic technology in air pollution control. Full article

To support mode-division multiplexing with reduced inter-modal crosstalk, we propose a novel polarization-maintaining few-mode fiber design with a uniform doping profile and no air holes. The fiber employs two placed low-index inclusions to lift modal degeneracy and achieve strong birefringence while maintaining compatibility with standard MCVD and OVD fabrication processes. A genetic algorithm is used to optimize the geometrical and refractive index parameters. Finite element simulations show that the optimized design supports ten guided modes with a minimum effective index difference exceeding $3.8\times {10}^{-4}$ across the C+L band. The fiber exhibits moderate dispersion and strong modal isolation. Tolerance analysis confirms good robustness against index fluctuations and moderate sensitivity to dimensional variations. These features suggest that the proposed PM-FMF is a promising candidate for short-reach spatial-division multiplexing applications where intrinsic polarization and mode separation are desired. Full article

The reverse circulation drill bit is the key component for the efficient and smooth implementation of the pneumatic hollow-through down-the-hole (DTH) hammer reverse circulation continuous coring (sampling) technology. To obtain the structural form of a reverse circulation drill bit with better reverse circulation performance, revealing its local flow fields by computational fluid dynamics (CFD) simulation is an effective approach. Taking the inner jet holes-type reverse circulation drill bit as the research object, three kinds of symmetrical and asymmetrical structures of inner jet holes were proposed. The CFD simulation results show that increasing the air volume supply and the number of inner jet holes leads to an increase in the velocity of air flow jet within the inner jet holes, an increase in the negative pressure formed in the central through channel below the inner jet holes, an enhancement of the reverse circulation performance and suction capacity formed by the reverse circulation drill bit, and an acceleration of the upward flow velocity of the rock cores (samples) located at the bottom of the borehole. Additionally, the reverse circulation performance formed by the reverse circulation drill bit with staggered arranged inner jet holes is superior to that of the reverse circulation drill bit with uniformly distributed inner jet holes. Under the same simulation conditions, the static pressure (i.e., negative pressure) and the upward flow velocity formed by the JB6 model are 2.34 kPa and 30.778 m/s higher than those formed by the JB3-3 model, while these two values formed by the JC6 model are 0.197 kPa and 3.689 m/s higher than those formed by the JB6 model, respectively. In conclusion, an asymmetric structural design would be more reasonable for the design of the inner jet holes-type reverse circulation drill bit. Full article

Funerary archaeoentomology is the discipline that studies insects and other arthropods in archaeological contexts, with a particular focus on the funerary domain. The presence of specific species, such as necrophagous beetles or saprophagous flies, can provide crucial evidence regarding post-mortem conditions—whether bodies were left exposed to the air or buried suddenly after death—and whether they underwent particular preservation practices, such as desiccation or embalming. This study concentrates on entomological specimens collected from three mummified bodies at the Sanctuary of Madonna della Corona in the province of Verona (northeast Italy), aiming to reconstruct aspects of funerary practices, especially the season of death and the authenticity of the garments worn by the mummified individuals. Insects were manually collected from bodies belonging to three hermits living between the 17th and 19th centuries. A complex entomofauna consisting of Diptera, Coleoptera, Lepidoptera, and minor taxa was collected and analyzed. Diptera puparia, primarily from the families Calliphoridae, Muscidae, and Fanniidae, were the most abundant entomological elements recovered. Their presence suggests potential exposure of the bodies before burial and indicates that death likely occurred during a mild period of the year (end of spring/beginning of autumn). The co-occurrence of holes caused by maggots on the hermits’ skin and their garments allows us to speculate about the authenticity of the clothing used during the funerary rituals. By combining entomological evidence with textile analysis, this research offers a more precise understanding of historical funerary practices within this devotional context. It sheds light on methods of managing human remains, burial traditions, and preservation techniques, particularly regarding the clothing of the deceased. Full article

As a core component of aero-engines, double-row ball bearings’ lubrication performance directly impacts the operational stability of the aircraft engine. However, existing under-race lubrication designs primarily rely on empirical knowledge, with insufficient understanding of the complex oil–air two-phase flow mechanisms, leading to bottlenecks in optimizing lubrication efficiency. Therefore, based on the computational fluid dynamics (CFD) method, a two-phase flow model for double-row ball bearings was established to systematically analyze the influence patterns of key parameters—including rotational speed, oil supply rate, number of under-race holes, diameter of under-race holes, and oil properties (viscosity, density)—on the distribution of the oil–air two-phase flow. The findings reveal that (1) the oil in the circumferential direction of the bearing cavity exhibits periodic distribution characteristics correlated with the number of under-race holes; (2) the self-rotation effect of balls hinders the migration of oil toward the outer raceway region, resulting in a significant reduction in the oil volume fraction within the bearing cavity; (3) compared with the single-sided oil supply configuration, the double-sided oil supply structure demonstrates superior lubrication performance. These research results provide theoretical support and reference data for the optimal design of under-race lubrication systems for double-row ball bearings. Full article

This study investigates the impacts of the gas environment, water matrix, and reactive species on the TiO₂-mediated photocatalytic degradation of safranin O (SO), a dye commonly found in wastewater. A slurry reactor (UVA, 365 nm) was used to quantify SO oxidation while systematically varying the SO concentration (5–40 mg/L), the TiO₂ loading (0–3 g/L), the temperature (15–45 °C), and the pH (2–12). The dissolved gases (air, nitrogen, and argon) and matrices (deionized water, mineral water, and seawater) were also examined. Eight mechanistic probes (ascorbic acid, methanol, azide, nitrite, benzoquinone, oxalate, sucrose, and phenol) were used to identify active oxidants. UVA/TiO₂ achieved rapid decolorization in approximately 90 min at 10 mg/L of SO and 0.4 g/L of TiO₂. Decolorization rates decreased with increasing SO concentration due to active-site competition and inner-filter effects. Rates also exhibited a bell-shaped dependence on TiO₂ loading due to light scattering and aggregation at high solids concentrations. Temperature exhibited a non-monotonic profile with an optimum around 25 °C, and the pH displayed an optimum range with maximal removal occurring around pH 10 and declining at pH 12. Air saturation outperformed N₂ and Ar, indicating that O₂ is the terminal electron acceptor. Photocatalytic performance decreased in the order deionized water > mineral water > seawater, owing to bicarbonate/chloride scavenging and ionic-strength effects. Scavenger tests converged on ^•OH dominance, with measurable contributions from superoxide/hydrogen peroxide (O₂^•−/H₂O₂) and valence-band holes (h⁺); singlet oxygen (¹O₂) played a minor role. These findings underscore the critical interplay between operational and environmental factors and offer a practical framework for scaling TiO₂-based SO abatement in real waters. Full article

The eccentric decoupled charge (EDC) is widely used in blasting engineering, but the combined effects of decoupling ratio, coupling medium, and explosive position (eccentricity coefficient) on blast pressure propagation and rock damage remain insufficiently understood. In this study, the RHT material model in LS-DYNA is calibrated using fracture patterns from laboratory tests, and a series of cubic single-hole numerical models is established to examine the influence of charging parameters on pressure evolution and rock damage. The results show that EDC blasting generates a clear eccentricity effect in pressure propagation: the coupled side exhibits a higher peak pressure and faster loading, while the decoupled side experiences delayed wave arrival and lower peak pressure. This asymmetry intensifies with increasing decoupling ratio and eccentricity coefficient. Pressure decay follows a nonlinear power function, with attenuation in the axial direction being greater than in the radial direction. The total damage volume decreases with increasing decoupling ratio, but the eccentricity of the damage pattern becomes more evident, especially in the crushed zone. Different coupling media influence this effect: air/sand coupling readily produces eccentricity effects, while water coupling requires a larger decoupling ratio to do so. From an energy perspective, the evolving asymmetry in fracture behavior is closely linked to the redistribution of internal energy between the coupled and decoupled sides, as governed by the charging configuration. Full article

Indoor air quality management has become increasingly critical for public health, particularly after the global COVID-19 respiratory disease outbreaks that highlighted airborne pathogen transmission risks. This review investigates an advanced air and surface purification method that is used in devices utilising heterogeneous photocatalysis with tungsten oxide (W₁₈O₄₉) and zinc oxide (ZnO) catalyst systems to generate controlled concentrations of hydrogen peroxide for continuous indoor sanitisation. The photocatalytic system converts ambient water vapour into aerosolised hydrogen peroxide at concentrations of 0.04–0.05 ppm, significantly below established safety thresholds, while maintaining effective antimicrobial activity. The W₁₈O₄₉ catalyst demonstrates superior visible-light absorption compared to conventional titanium dioxide (TiO₂) systems, with ZnO serving as an effective cocatalyst to reduce electron–hole recombination and enhance reactive oxygen species generation. Safety analysis based on OSHA, WHO, and ACGIH guidelines confirms that continuous exposure to these low hydrogen peroxide concentrations poses no health risks to occupants. Real-world applications demonstrate up to 90% reduction in airborne pathogens and a 20–30% decrease in sick leave rates in office environments. The technology offers significant economic benefits through reduced healthcare costs and improved productivity while providing environmentally sustainable air purification without harmful residues. This photocatalytic approach represents a scientifically validated, safe, and economically viable solution for next-generation indoor air quality management across healthcare, educational, commercial, and residential sectors. Full article

Early detection of cancer remains a key challenge because current SPR-PCF sensors lack both sensitivity and robust light–analyte interaction. To overcome these limitations, this study proposed and validated an SPR biosensor utilizing MXene-functionalized PCF. By introducing a composite structure of MXene nanomaterials and Au, the detection performance of the sensor was significantly improved. The sensor adopts a circular air hole arrangement and double-groove morphology design and leverages MXene’s high conductivity and gold’s chemical stability to simultaneously enhance plasmonic coupling and biocompatibility. Through FEM-based structural optimization of the air hole diameter, Au layer thickness, and groove shape, the sensor exhibited outstanding refractive-index detection performance with a wavelength sensitivity of 11,072 nm/RIU, an impressive quality factor reaching 201.3 RIU⁻¹, and a resolution as fine as 9.03 × 10⁻⁶ RIU. The simulation results demonstrated the capability of the sensor to discriminate six distinct cancer-cell types (cervical cancer HeLa, leukemia Jurkat, pheochromocytoma PC-12, triple-negative breast cancer MDA-MB-231, and breast cancer MCF-7) with high sensitivity and verify its ability to detect pan-cancer species. This study demonstrates an innovative approach for constructing a high-performance SPR sensing platform that has important application potential in the context of the early detection of multiple cancers. Full article

Reducing the anthropogenic impact on the environment is an increasingly urgent challenge, particularly in the energy and heat generation sectors. This study presents the results of an experimental investigation into the combustion characteristics of four nozzle types in a burner system. The experiments focused on emissions of NOx and CO under varying equivalence ratios. This study presents an experimental investigation of combustion with one swirl-stabilized nozzle and two multihole plates under varying equivalence ratios (φ). The swirl-stabilized configuration produced the highest NOx, reaching 54.4 ppm at φ = 0.9, which we attribute to higher flame temperatures and longer effective residence. In contrast, the multihole plates—122 holes of 1.0 mm and 36 holes of 4.0 mm in a 100 mm insert—exhibited lower NOx and lower temperatures owing to more effective fuel–air mixing. CO showed a strong dependence on both geometry and φ; the lowest levels occurred near φ ≈ 0.9, consistent with optimal combustion. The findings underscore the importance of nozzle geometry and air–fuel ratio in optimizing combustion efficiency and minimizing harmful emissions, providing valuable insights for the development of low-emission combustion systems in modern energy applications. Full article