Search Results (2,341)

One of the most critical challenges in gas turbine design is preventing the ingestion of hot mainstream gases into the disk space between the stator and rotor disks. Rim seals and superposed sealant flows are commonly used to mitigate the risk of component overheating. However, leakage paths inevitably form between the mating interfaces of adjacent components due to the complex architecture of the engine. Therefore, the interaction between the different flows present within the disk space complicates the accurate determination of the optimal sealing flow quantity. For this reason, this study experimentally investigates fluid dynamics inside a stator–rotor cavity, with a particular focus on leakage flows. In particular, this work examines the impact of multiple parameters, including injection radius position, number of leakage holes, and injection angle, on the sealing effectiveness values measured on the stator side of the cavity through CO${}_2$ gas sampling measurements. By comparing the effectiveness values with the swirl measurements derived from static and total pressure readings, the development of flow structures and the impact of leakage injection on sealing performance were finally evaluated. The results indicate that leakage injection has a minimal effect on the sealing effectiveness above the injection point, but significantly improves the performance at a lower radius. Moreover, it was observed that for a given mass flow rate, using a lower number of holes results in worse sealing performance due to a higher jet momentum, which causes the leakage flow to penetrate through the cavity toward the rotor side. In the end, employing two distinct injection angles—both aligned with the rotor’s direction of rotation—showed no substantial impact on sealing effectiveness. Full article

We present a comprehensive investigation into the emergence of interface-bound states, particularly Majorana zero modes (MZMs), in a lateral heterostructure composed of two three-dimensional topological insulators (TIs), Bi₂Se₃ and Sb₂Te₃, under the influence of proximity-induced superconductivity from niobium (Nb) contacts. We develop an advanced two-dimensional Dirac model for the topological surface states (TSS), incorporating spatially varying chemical potentials and s-wave superconducting pairing. Using the Bogoliubov–de Gennes (BdG) formalism, we derive analytical solutions for the bound states and compute the local density of states (LDOS) at the interface, revealing zero-energy modes characteristic of MZMs. The topological nature of these states is rigorously analyzed through winding numbers and Pfaffian invariants, and their robustness is explored under various physical perturbations, including gating effects. Our findings highlight the potential of this heterostructure as a platform for topological quantum computing, with detailed predictions for experimental signatures via tunneling spectroscopy. Full article

ORF8 is the second most mutated protein in SARS-CoV-2. It can form oligomers such as trimers and can bind to the IL-17RA/RC receptor. To understand the possible role of ORF8 in SARS-CoV-2, the first step of this study involved predicting the ORF8 trimer structure and the complex structure of the ORF8 monomer bound to the IL-17RA receptor using docking and molecular dynamics simulation methods. It was found that ORF8 molecules bound to the central ORF8 molecule through covalent and noncovalent interactions exhibit similar RMSD and RMSF values as the central ORF8 molecule and form a similar buried surface area, but display different numbers of hydrogen bonds and varying dynamic correlations. Additionally, trimer formation increases the dynamic correlation of the noncovalently bound ORF8 unit. ORF8 can bind with the IL-17RA receptor stably. Regions on ORF8, including C25–I47, L60–S67, T80–C90, and S103–E110, and regions on IL-17RA, including L1–H63 and D122–M165, are involved in the binding interface of the complex. ORF8 becomes less rigid when bound to IL-17RA than in its monomer, dimer, and trimer forms. Based on dihedral angle correlation predictions, binding of ORF8 to IL-17RA reduces internal correlations within ORF8 while strengthening correlations within IL-17RA. The G50–T80 region of ORF8 appears to be critical for interaction with IL-17RA, and the L1–V150 region of IL-17RA should be critical for its dynamics once bound to ORF8. These results help elucidate the structure and dynamics of ORF8 in SARS-CoV-2. Full article

The investigation of fluid flow channeling and viscous fingering during immiscible two-phase displacement in subsurface porous media is crucial for optimizing CO₂ geological sequestration and improving hydrocarbon recovery. In this study, we develop a pore-scale numerical framework for unsteady state immiscible displacement based on a body-centered cubic percolation network, which explicitly captures the coupled effects of pore-scale heterogeneity, capillary number, and unfavorable viscosity ratio on flow channeling and viscous fingering. The simulations reveal that viscous fingering and flow channeling preferentially occur along overlapping high conductivity pathways that conform to the minimum energy dissipation principle. Along these preferential routes, the local balance between viscous and capillary forces governs the stability of the two-phase interface and gives rise to distinct patterns and intensities of viscous fingering in the invading phase. Building on these insights, we establish a theoretical framework that quantifies how the critical pore radius and capillary number control the onset and growth of interfacial instabilities during immiscible displacement. The model demonstrates that lowering the injection rate, and hence, the effective capillary number, suppresses viscous fingering, leading to more stable displacement fronts. These findings provide practical guidance for the design of injection schemes, helping to enhance oil and gas recovery and improve the storage efficiency and security of CO₂ geological sequestration projects. Full article

This study presents a comprehensive structural optimization workflow for a railway motor bogie frame, aimed at developing an innovative and lightweight design compliant with the reference European standards. The methodology integrates a two-stage topology optimization process, supported by an extensive numerical simulation campaign and a dedicated sensitivity analysis to identify the most critical load scenarios. In the first optimization stage, a global evaluation of the frame performance revealed that increasing the number of optimization parameters leads to a rise of approximately 50% in solver iterations. Symmetry constraints proved essential for simplifying both the optimization and the subsequent geometric reconstruction. The minimum feasible feature dimension strongly affected the final solution, modifying the material distribution and enabling a mass reduction of about 18%. The second optimization stage, focused on the cross beams, highlighted the relevance of manufacturing constraints in guiding the solver toward practical configurations. Static and fatigue assessments confirmed stress distributions consistent with the original frame, providing designers with a reliable basis for future material upgrades. Finally, the dynamic analysis showed a first natural frequency above 60 Hz, with variations in the first eigenvalue within 1% and preservation of the local flexural mode shape, ensuring full compatibility with the original frame interfaces and enabling seamless replacement with the optimized configuration. Full article

Reinforced concrete (RC) beams strengthened with carbon-fabric-reinforced cementitious matrix (CFRCM) systems have shown potential for restoring flexural performance, yet their effectiveness under different corrosion levels remains insufficiently understood. This study presents a numerical investigation of the flexural behaviour of simply supported RC beams externally strengthened with CFRCM plates. Refined finite element models (FEMs) were developed by explicitly incorporating the steel–concrete bond-slip behaviour, the carbon fabric (CF) mesh–cementitious matrix (CM) interface, and the CFRCM–concrete substrate interaction and were validated against experimental results in terms of failure modes, load–deflection responses, and flexural capacities. A parametric study was then conducted to examine the effects of CFRCM layer number, steel corrosion level, and longitudinal reinforcement ratio. The results indicate that the baseline flexural capacity can be fully restored only when the corrosion level remains below approximately 15%; beyond this threshold, none of the CFRCM configurations achieved full recovery. The influence of the reinforcement ratio was found to depend on corrosion severity, while increasing CFRCM layers enhanced flexural performance but exhibited saturation effects for thicker configurations. In addition, corrosion level and CFRCM thickness jointly influenced the failure mode. Comparisons with design predictions show that bilinear CFRCM constitutive models are conservative, whereas existing FRP-based design codes provide closer agreement with numerical and experimental results. Full article

Influenza A viruses exhibit broad host tropism, infecting multiple species including humans, avian species, and swine. Swine influenza virus (SIV), while primarily circulating in porcine populations, demonstrates zoonotic potential with sporadic human infections. In this investigation, we identified two H1N1 subtype swine influenza A virus strains designated A/swine/China/SD6591/2019(H1N1) (abbreviated SD6591) and A/swine/China/SD6592/2019(H1N1) (abbreviated SD6592) in Shandong Province, China. The GenBank accession numbers of the SD6591 viral gene segments are PV464931-PV464938, and the GenBank accession numbers corresponding to each of the eight SD6592 viral gene segments are PV464939-PV464946. Phylogenetic and recombination analyses suggest potential evolutionary differences between the isolates. SD6591 displayed a unique triple-reassortant genotype: comparative nucleotide homology assessments demonstrated that the PB2, PB1, NP, NA, HA, and NEP genes shared the highest similarity with classical swine-origin H1N1 viruses. In contrast, SD6592 maintained genomic conservation with previously characterized H1N1 swine strains, although neither of these two isolates exhibited significant intrasegmental recombination events. Through comprehensive sequence analysis of these H1N1 SIVs, this study provides preliminary insights into their evolutionary history and underscores the persistent risk of cross-species transmission at the human–swine interface. These findings establish an essential foundation for enhancing national SIV surveillance programs and informing evidence-based prevention strategies against emerging influenza threats. Full article

Canine Distemper Virus (CDV) is a highly contagious disease that affects a wide range of wildlife species, posing a serious threat to biodiversity and conservation efforts. Despite its ecological significance, the transmission dynamics of CDV in wildlife remain poorly understood, especially in tropical ecosystems. One of the main challenges in studying CDV transmission is the lack of reliable epidemiological data and the difficulty in capturing and monitoring wild animals for surveillance purposes. Thus, this study aims to develop a model to estimate the potential transmission of CDV in wildlife populations using spatial heat mapping and the basic reproduction number (R₀) as key indicators. A combination of field observation records, environmental data, and reported CDV cases were used to generate predictive heat maps and simulate disease spread across susceptible wildlife hosts. Results showed that certain environmental factors and animal density hotspots significantly contribute to higher transmission potential of CDV. Preliminary results suggest that high-risk zones can be identified based on overlapping wildlife movement corridors and human interface areas. This modeling approach offers a valuable tool to guide targeted monitoring, early detection and conservation strategies against CDV outbreaks in wildlife. Full article

The mechanical properties of carbon fiber composites (CFRCs) are governed by the carbon fibers (CFs) themselves and the fiber–matrix interface (FMI), with the synergy between the two being crucial. This study focused on how microstructural heterogeneity affects the compression after impact (CAI) of the same epoxy resin (EP) composites. The research was conducted using two variants of dry-jet wet-spun T800G CFs, labeled CF-low and CF-high. The results indicated that while CF-low exhibited a higher number of deep axial grooves and a greater surface micro-zone compressive modulus, their pronounced skin–core structure and the excessively strong interfacial bonding formed by mechanical interlocking aggravated fiber core collapse and stress concentration under mechanical loading. In contrast, the homogeneous structure and moderate interfacial characteristics of CF-high facilitated efficient stress transfer between the CFs and EP. Compared with CF-low composites, CF-high composites exhibited a 9% increase in CAI strength and a 35% reduction in damage area, significantly improving the damage tolerance of the composites. This research underscores that optimizing the synergy between the fiber properties and the interfacial behavior is key to enhancing CFRC performance. Full article

Due to their unique properties resulting from the combination of metals with different properties, bimetallic sheets are desirable in the energy, petrochemical, and shipbuilding industries. In this article, explosively welded EN AW-1050/Cu-ETP (Al/Cu) plates were used as the test material. One of the greatest advantages of Al/Cu bimetallic plates is their high deformability, which allows for easy plastic forming. The aim of this study was to determine the effect of severe plastic deformation on the microstructure and microhardness of explosively welded EN AW-1050/Cu-ETP plates. Bimetallic samples were processed using the Twist Channel Angular Pressing (TCAP) process. This process consisted of varying the number of passes and the sample orientation relative to the helical exit channel of the TCAP die. For comparative purposes, a microstructural analysis and the microhardness testing of the as-welded samples were also carried out. Microstructural analysis of TCAP-processed samples showed that the sample deformed along route Bc exhibited the most deformed weld interface profile. No cracking or delamination was observed in the Al/Cu interfacial transition layer of TCAP-processed samples. The number of passes and orientation of the bimetallic material relative to the die exit channel affected the final microhardness in the individual layers of explosively welded EN AW-1050/Cu-ETP bimetallic plate. Full article

Canine parvovirus type 2 (CPV-2) is a primary etiological agent of acute gastroenteritis in domestic dogs. Although molecular and serological evidence have confirmed its circulation in wild carnivores, the clinical impact of spillover events in wildlife hosts remain insufficiently characterized. In this study, we investigated CPV-2 from wild coyote pups (Canis latrans) presenting with clinical gastroenteritis in northeastern Mexico. CPV-2 was successfully isolated in MDCK cells, and whole-genome sequencing was performed on two isolates, B55 and B56 (GenBank accession numbers PQ065988 and PQ065989). A comprehensive analysis identified 23 nucleotide mutations, eight of which were missense mutations resulting in amino acid substitutions in structural (VP) and non-structural (NS) proteins. Notably, amino acid substitution L354V was identified in the NS1 helicase domain of both isolates, a region critical for viral replication. Phylogenetic analysis confirmed that isolates B55 and B56 cluster within the CPV-2c subtype, showing high genetic relatedness to circulating Mexican and US canine strains which strongly suggests recent cross-species transmission between domestic dogs and wild coyotes. This study provides the first complete genomic characterization of a clinical CPV-2 infection in wild coyotes in Mexico, underscoring the immediate risk of CPV-2c transmission at the domestic animal–wildlife interface. Full article

Since the number of existing steel-reinforced concrete buildings affected by carbonation-induced corrosion is steadily increasing, there is a high demand for durable repair methods. Chemical re-alkalization (CRA) represents one such approach, relying on the transport of alkaline pore solution from a repair mortar into carbonated concrete. With the introduction of clinker-reduced binder systems such as hybrid alkali-activated binders (HAABs), their suitability for CRA and governing material parameters require further clarification. In this study, material-related chemical and structural influences on CRA were investigated using an adapted form of Fick’s second law of diffusion, incorporating a time-dependent attenuation factor, β(t). The CRA progression was evaluated over 28 days, distinguishing between an initial suction phase and a subsequent diffusion phase. The results show that a high initial alkalinity of the mortar pore solution (pH > 14) significantly enhances re-alkalization during the suction phase, reflected by suction factors a > 1. In contrast, progression during the diffusion phase is primarily governed by the potassium concentration gradient at the mortar–concrete interface, while structural parameters such as capillary porosity show no systematic correlation with the deceleration factor b (−0.46 ≤ b ≤ −0.26). The findings indicate that, within the investigated range, mortar pore solution chemistry has a stronger influence on CRA than structural properties, providing guidance for the targeted design of alkaline repair mortars. Full article

The island of Gran Canaria (Spain) has undergone a significant transformation in wildfire dynamics over the past two decades, characterized by a decline in wildfire frequency but a marked increase in the severity and spatial impact of extreme events, particularly within the wildland–urban interface (WUI). This study analyzes wildfire activity between 2000 and 2020 using official datasets and statistical trend analyses, incorporating robust severity indicators and measures of burned area concentration. Results show a statistically significant decreasing trend in the number of wildfires, while burned area is extremely concentrated in a small number of high-intensity events, with four large wildfires accounting for more than 97% of the total affected area. Climatic influences on wildfire activity were assessed through the analysis of long-term meteorological indicators, focusing on trends in extreme heat days and precipitation as proxies for thermal stress and fuel moisture availability. The results indicate a substantial modification of the background climatic framework under which wildfires develop, although no direct causal relationships are inferred. In parallel, territorial processes—such as rural abandonment, increased fuel continuity, and the expansion of dispersed housing beyond consolidated settlements—act as key amplifiers of wildfire risk. Overall, the findings highlight a transition from emergency-oriented fire suppression toward resilience-based wildfire management, emphasizing the need to integrate climate adaptation, territorial planning, and stricter land-use regulation in WUI areas. Full article

In the present work, off-design operating condition is considered to be the ability of the turbine to operate down to 50% to 20% of its nominal intake air flow rate. An important consequence of these off-design points is the change in the inlet incidence angle, which varied from nominal to −20°. Tests were performed on a seven-blade rotor cascade with platform cooling through an upstream slot simulating the stator-to-rotor interface gap. To model the impact of rotation on purge flow injection, a set of fins were installed inside the slot to give the coolant flow a tangential direction. Different cascades’ off-design operating conditions were tested, covering downstream velocity values up to Ma_2is = 0.55, with two inlet turbulence intensity levels of 0.6% a and 7%. A thermal measurement campaign was conducted with the Thermochromic Liquid Crystal technique to measure the adiabatic film cooling effectiveness at various coolant-to-main-flow mass flow ratios, different incidence angles, mainstream Mach numbers, and turbulence levels. The results describe the complexity of the turbine operating under off-design operating conditions, relating the improvement in the platform thermal protection to the reduced secondary-flows activity induced by negative incidence. Full article

We present the design and characterisation of a 4.2-megapixel, wafer-scale CMOS image sensor, achieving over 5000 frames per second at full resolution. The sensor has a pixel pitch of 58 µm square pixels, thus being as large as a full 200 mm wafer. The sensor is read out on two sides and features column-parallel programmable gain amplifiers (PGAs) as well as analogue-to-digital converters (ADCs). The array has 2052 columns and 2064 rows; 12 rows are read in parallel, so that the total number of ADCs is 24,624. The data is transmitted through 216 sub-LVDS lanes running at 1 Gbps in double data rate (DDR). Besides the row and column control, the sensor generates the necessary voltages and currents on a chip. The programming is performed through a serial-to-parallel interface (SPI). The sensor was optimised for direct detection of electrons, but it can also detect photons. Thus, it could be a good candidate for applications where high speed is needed, such as wavefront sensing. Full article