Search Results (192)

Difficult, extreme operating conditions of parabolic antennas under precipitation and sub-zero temperatures require the creation of effective heating systems. The purpose of the research is to develop a multilayer coating containing two metal-ceramic layers, epoxy composite layers, carbon fabric, and an outer layer of basalt fabric, which allows for effective heating of the antenna, and to study the properties of this coating. The multilayer coating was formed on an aluminum base that was subjected to abrasive jet processing. The first and second metal-ceramic layers, Al₂O₃ + 5% Al, which were applied by high-speed multi-chamber cumulative detonation spraying (CDS), respectively, provide maximum adhesion strength to the aluminum base and high adhesion strength to the third layer of the epoxy composite containing Al₂O₃. On this not-yet-polymerized layer of epoxy composite containing Al₂O₃, a layer of carbon fabric (impregnated with epoxy resin) was formed, which serves as a resistive heating element. On top of this carbon fabric, a layer of epoxy composite containing Cr₂O₃ and SiO₂ was applied. Next, basalt fabric was applied to this still-not-yet-polymerized layer. Then, the resulting layered coating was compacted and dried. To study this multilayer coating, X-ray analysis, light and raster scanning microscopy, and transmission electron microscopy were used. The thickness of the coating layers and microhardness were measured on transverse microsections. The adhesion strength of the metal-ceramic coating layers to the aluminum base was determined by both bending testing and peeling using the adhesive method. It was established that CDS provides the formation of metal-ceramic layers with a maximum fraction of lamellae and a microhardness of 7900–10,520 MPa. In these metal-ceramic layers, a dispersed subgrain structure, a uniform distribution of nanoparticles, and a gradient-free level of dislocation density are observed. Such a structure prevents the formation of local concentrators of internal stresses, thereby increasing the level of dispersion and substructural strengthening of the metal-ceramic layers’ material. The formation of materials with a nanostructure increases their strength and crack resistance. The effectiveness of using aluminum, chromium, and silicon oxides as nanofillers in epoxy composite layers was demonstrated. The presence of structures near the surface of these nanofillers, which differ from the properties of the epoxy matrix in the coating, was established. Such zones, specifically the outer surface layers (OSL), significantly affect the properties of the epoxy composite. The results of industrial tests showed the high performance of the multilayer coating during antenna heating. Full article

This study focuses on the analysis of soliton solutions within the framework of the time-fractional cubic–quintic nonlinear Schrödinger equation (TFCQ-NLSE), a powerful model with broad applications in complex physical phenomena such as fiber optic communications, nonlinear optics, optical signal processing, and laser–tissue interactions in medical science. The nonlinear effects exhibited by the model—such as self-focusing, self-phase modulation, and wave mixing—are influenced by the combined impact of the cubic and quintic nonlinear terms. To explore the dynamics of this model, we apply a robust analytical technique known as the sub-ODE method, which reveals a diverse range of soliton structures and offers deep insight into laser pulse interactions. The investigation yields a rich set of explicit soliton solutions, including hyperbolic, rational, singular, bright, Jacobian elliptic, Weierstrass elliptic, and periodic solutions. These waveforms have significant real-world relevance: bright solitons are employed in fiber optic communications for distortion-free long-distance data transmission, while both bright and dark solitons are used in nonlinear optics to study light behavior in media with intensity-dependent refractive indices. Solitons also contribute to advancements in quantum technologies, precision measurement, and fiber laser systems, where hyperbolic and periodic solitons facilitate stable, high-intensity pulse generation. Additionally, in nonlinear acoustics, solitons describe wave propagation in media where amplitude influences wave speed. Overall, this work highlights the theoretical depth and practical utility of soliton dynamics in fractional nonlinear systems. Full article

An ultra-high-strength press-hardening steel (PHS) and a high-strength dual-phase steel (DP) were butt-joined by the gas metal arc welding (GMAW) process, aiming to assess the effects of a high heat input welding process on the structure-property relationship and residual stress. The post-weld microstructure, the microhardness profile, the tensile behavior, and the experimentally obtained residual stresses (by x-ray diffraction) of the steels in dissimilar (PHS-DP) and similar (PHS-PHS, DP-DP) pair combinations have been analyzed. Results indicated that the ultimate tensile strength (UTS) of the dissimilar pair PHS-DP achieves a similar strength to the DP-DP joint, whereas the elongation was similar to that of the PHS-PHS weldment. The failure location of the tensile specimens was expected and systematically observed at the tempered and softer sub-critical heat-affected zone (SC-HAZ) in all welded conditions. Compressive residual stresses were consistently observed along the weldments in all specimens; the more accentuated negative RS were measured in the PHS joint attributed to the higher volume fraction of martensite; furthermore, the negative RS measured in the fusion zone (FZ) could be well correlated to weld restraint due to the sheet anchoring during the welding procedure, despite the presence of predominant ferrite and pearlite microstructures. Full article

The production of AISI 304 stainless steel (a corrosion-resistant alloy prone to solidification defects from high alloy content) particularly benefits from twin-roll strip casting—a short-process green technology enabling sub-rapid solidification (the maximum cooling rate exceeds 1000 °C/s) control for high-performance steels. However, the internal phenomena within its molten pool remain exceptionally challenging to monitor. This study developed a multiscale numerical model to simulate coupled fluid flow, heat transfer, and solidification in AISI 304 stainless steel twin-roll strip casting. A quarter-symmetry 3D model captured macroscopic transport phenomena, while a slice model resolved mesoscopic solidification structure. Laboratory experiments had verified that the deviation between the predicted temperature field and the measured average value (1384.3 °C) was less than 5%, and the error between the solidification structure simulation and the electron backscatter diffraction (EBSD) data was within 5%. The flow field and flow trajectory showed obvious recirculation zones: the center area was mainly composed of large recirculation zones, and many small recirculation zones appeared at the edges. Parameter studies showed that, compared with the high superheat (110 °C), the low superheat (30 °C) increased the total solid fraction by 63% (from 8.3% to 13.6%) and increased the distance between the kiss point and the bottom of the molten pool by 154% (from 6.2 to 15.8 mm). The location of the kiss point is a key industrial indicator for assessing solidification integrity and the risk of strip fracture. In terms of mesoscopic solidification structure, low superheat promoted the formation of coarse columnar crystals (equiaxed crystals accounted for 8.9%), while high superheat promoted the formation of equiaxed nucleation (26.5%). The model can be used to assist in the setting of process parameters and process optimization for twin-roll strip casting. Full article

Accurate modeling of ore materials is fundamental to high-precision simulations in mineral processing and remains a key research focus. To address the modeling challenges arising from the inherent heterogeneity and strength diversity of ores, this study proposes a novel method based on the bonded particle model (BPM) in the Discrete Element Method (DEM), incorporating multi-sized sub-particle stochastic generation and assembly, as well as bond strength parameter design. The method was applied to model and simulate impact crushing of 30 mm size fraction gold, iron, and copper ores with varying strengths. The resulting particle size distributions of fragmented ores were analyzed. Furthermore, drop weight tests were conducted on ore samples of the same size fraction, and the experimental mass distribution of fragmented particles demonstrated good consistency with simulation results. These findings validate the capability of the proposed method to effectively characterize the strength diversity of natural ores, offering an advanced approach for high-fidelity modeling of mineral materials. Full article

Fractional cointegration has been extensively examined in time series analysis, but its extension to heterogeneous panel data with unobserved heterogeneity and cross-sectional dependence remains underdeveloped. This paper develops a robust framework for testing fractional cointegration in heterogeneous panel data, where unobserved heterogeneity, cross-sectional dependence, and persistent shocks complicate traditional approaches. We propose the Bayesian Tapered Narrowband Least Squares (BTNBLS) estimator, which addresses three critical challenges: (1) spectral leakage in long-memory processes, mitigated via tapered periodograms; (2) precision loss in fractional parameter estimation, resolved through narrowband least squares; and (3) unobserved heterogeneity in cointegrating vectors (${\theta }_i$) and memory parameters ($\nu ,\delta$), modeled via hierarchical Bayesian priors. Monte Carlo simulations demonstrate that BTNBLS outperforms conventional estimators (OLS, NBLS, TNBLS), achieving minimal bias (0.041–0.256), near-nominal coverage probabilities (0.87–0.94), and robust control of Type 1 errors (0.01–0.07) under high cross-sectional dependence ($\rho =0.8$), while the Bayesian Chen–Hurvich test attains near-perfect power (up to 1.00) in finite samples. Applied to Purchasing Power Parity (PPP) in 18 fragile Sub-Saharan African economies, BTNBLS reveals statistically significant fractional cointegration between exchange rates and food price ratios in 15 countries ($p<0.05$), with a pooled estimate ($\widehat{\theta }=0.33$, $p<0.001$) indicating moderate but resilient long-run equilibrium adjustment. These results underscore the importance of Bayesian shrinkage and spectral tapering in panel cointegration analysis, offering policymakers a reliable tool to assess persistence of shocks in institutionally fragmented markets. Full article

This study focuses on optimizing the thermal performance of hydrogen turbine blades through a sensitivity analysis using generalized fractional calculus. The approach is designed to capture the transient temperature dynamics and optimize thermal profiles by analyzing the influence of a fractional-order parameter on the system’s behavior. The model was implemented in Python, using Monte Carlo simulations to evaluate the impact of the parameter on the temperature evolution in different thermal regimes. Three distinct regions were identified: the Quasi-Uniform Region (where fractional effects are negligible), the Sub-Classical Region (characterized by delayed thermal behavior), and the Super-Classical Region (exhibiting enhanced heat accumulation). Regression analyses reveal quadratic and cubic dependencies of blade temperature on the fractional-order parameter, confirming the robustness of the model with R² values greater than 0.96. The study highlights the potential of using fractional calculus to optimize the thermal response of turbine blades, helping to identify the most suitable parameters for faster stabilization and efficient heat management in hydrogen turbines. Furthermore, it was found that by adjusting the fractional-order parameter, the system can be optimized to reach equilibrium more rapidly while achieving higher temperatures. Importantly, the equilibrium is not altered but rather accelerated based on the chosen parameter, ensuring a more efficient thermal stabilization process. Full article

Altered body condition and diminished growth in wildlife in the Alberta Oil Sands Region (AOSR) are prompting investigations into the impact of oil sands industrial activity on wildlife in the region. Chemical constituents from bitumen-influenced waters, including oil sands process-affected water (OSPW), can disrupt endocrine signaling, leading to aberrant lipid accumulation and altered glycemic control in mammals. This study aimed to investigate the effects of naphthenic acid fraction components (NAFCs), derived from OSPW, on energy homeostasis using the McA-RH7777 rat hepatocyte model. Cells were exposed to NAFCs at nominal concentrations of 0, 0.73, 14.7, and 73.4 mg/L for 24 and 48 h. We assessed gene expression related to lipid and glucose metabolism and measured triglyceride accumulation, glucose, and fatty acid uptake. NAFC exposure (14.7 and 73.4 mg/L) reduced triglyceride levels and glucose uptake and increased fatty acid uptake and the expression of beta-oxidation genes, suggesting a metabolic switch from glucose to fatty acid oxidation. This switch in substrate availability signifies a shift in cellular energy dynamics, potentially linked to altered mitochondrial function. To investigate this, we conducted adenosine triphosphate (ATP), mitochondrial membrane potential, and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assays to measure cellular ATP levels, mitochondrial membrane potential, and apoptosis, respectively. At both time points, 73.4 mg/L NAFC exposure resulted in increased ATP levels, induced mitochondrial membrane hyperpolarization, and increased apoptosis. These results suggest that mitochondrial efficiency is compromised, necessitating metabolic adaptations to maintain energy homeostasis. Given that cells exhibit metabolic flexibility that allows them to dynamically respond to changes in substrate availability, we further demonstrated that the kynurenine–tryptophan ratio (KTR) serves as a marker for a shift in energy metabolism under these stress conditions. This work provides a mechanistic framework for understanding how bitumen-derived organic contaminants may disrupt metabolic function in wildlife living in the AOSR. These findings further support the use of molecular markers like KTR to evaluate sub-lethal metabolic stress in environmental health monitoring. Full article

Land surface temperature (LST) is an important environmental parameter in many fields. However, many studies require high-spatial- and high-temporal-resolution LST products to improve the coarse spatial resolution of moderate-resolution imaging spectroradiometer (MODIS) LSTs. Numerous approaches have downscaled MODIS LST images to a finer spatial resolution using pixel-based image analysis (PBA). Meanwhile, object-based image analysis (OBIA) methods, which have developed rapidly in the analysis of high-spatial-resolution visible and near-infrared (VNIR) band data, have received little attention in the LST downscaling field. In this paper, we propose an object-based downscaling (OBD) method for MODIS LST using high-spatial-resolution multispectral images (e.g., Landsat Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)) as auxiliary data. The fundamental principle of this method is to preserve the thermal radiance of the “object”, which is composed of several MODIS LST pixels (partly or entirely) and is unchanged after disaggregation into subpixels in the resulting LST image. The decomposition process consists of two key parts: the thermal radiance (TR) estimation of the object from MODIS LST products and the weight calculation of sub-objects or subpixels. Objects were generated from VNIR data and remote sensing indices (e.g., the normalized difference vegetation index (NDVI), the normalized difference built-up index (NDBI), and fractions of different endmembers) using a multiscale segmentation method. The radiance of subpixels or sub-objects was calculated based on the weights of their parent objects, which were estimated by the relationships between the remote sensing indices and the LST. The accuracy and the efficiency of the OBD method were validated using a pair of ASTER and MODIS datapoints that were acquired at the same time. The decomposed LST results showed that the spatial distribution of the downscaled LST image closely resembled the true LST of the ASTER, with an RMSE of 2.5 K for the entire image. A comparison with PBA methods for pixel downscaling also indicated that the OBD method achieves the lowest root mean square error (RMSE) across different landcovers, including urban areas, water bodies, and natural terrain. Therefore, the proposed OBD method significantly enhances the capability of increasing the spatial resolution of coarse MODIS LST, providing an alternative for improving the spatial resolution of MODIS LST images and expanding their applicability to studies that require high-temporal- and high-spatial-resolution LST products. Full article

Numerous skarn-type Sn and hydrothermal vein-type Pb–Zn–Ag deposits occur in the northern Yidun Terrane, China. The Gongjuelong skarn Sn polymetallic deposit, adjacent to the Haizishan granite, is situated in the central region of Yidun Terrane. The genesis of the Gongjuelong Sn deposit and its relationship with the adjacent Pb–Zn–Ag deposits remains controversial. The ore-forming process can be divided into three stages: the prograde stage (I), marked by the formation of garnet and pyroxene; the retrograde stage (II), which includes the epidote–actinolite sub-stage (II-1) and the quartz-cassiterite sub-stage (II-2); and the sulfide stage (III), consisting of the chalcopyrite–pyrrhotite sub-stage (III-1) and the arsenopyrite–sphalerite sub-stage (III-2). Two types of garnet (Grt-I and Grt-II) have been identified in stage I and both belong to the grossular–andradite solid solution. Grt-II (Gro_52-73And_25-45Spe+Pyr+Alm_2-3) contains slightly more Fe than Grt-I (Gro_64-76And_20-28Spe+Pyr+Alm_2-10). Grt-I is enriched in heavy rare-earth elements (HREEs) and depleted in light rare-earth elements (LREEs), whereas Grt-II is enriched in LREEs and depleted in HREEs. Grt-I has higher U contents and lower Th/U ratios than those of Grt II, indicating a lower oxygen fugacity for the earlier skarn alteration. In contrast to Grt-I, Grt-II shows a more significant negative Eu anomaly along with lower LREEs/HREEs. Therefore, Grt-I and Grt-II likely formed under mildly acidic and near-neutral conditions, respectively. The W (350–3015 ppm) and Fe (235–3740 ppm) contents and Zr/Hf ratios (18.7–49.4) of cassiterite from Gongjuelong are similar to those of cassiterite from the granite-related Sn deposits, as well as the Xiasai hydrothermal vein-type Pb–Zn–Ag deposit in the northern Yidun Terrane. The Ti/Ge ratio (0.06–1.13) and P contents (13.9–173 ppm) of quartz are also similar to those from the Xiasai Pb–Zn–Ag deposit, both of which resemble those of skarn-type deposits and Sn-associated quartz. Furthermore, the Ti/Zr ratio (average 33.2) of cassiterite at Gongjuelong are much higher than that of cassiterite at Xiasai (average 3.7), indicating that the Pb–Zn–Ag veins could represent the distal product of the “parent” granite. On the basis of combined evidence from geology, geochemistry, and published geochronology data, we propose that the proximal skarn-type Sn deposits and distal hydrothermal vein-type Pb–Zn–Ag±Sn deposits in the northern Yidun Terrane constitute an integrated ore system, which is genetically related to the late Cretaceous highly fractionated granites. This proposed hypothesis highlights the potential prospecting of Sn mineralization beneath the hydrothermal Pb–Zn–Ag veins, as well as the hydrothermal Pb–Zn–Ag veins controlled by faults/fractures within the strata around the Sn deposits and highly fractionated granites. Full article

Pleopeltis crassinervata has demonstrated antimicrobial effects, including anti-Toxoplasma activity, which has been attributed to the presence of compounds such as terpenes and fatty acid methyl esters. In this study, the effects of P. crassinervata hexane subfraction one (Hsf1) on the Toxoplasma gondii tachyzoite ultrastructure were evaluated using TEM and SEM, and lytic cycle processes such as adhesion, invasion, and proliferation were evaluated using phase-contrast microscopy. Additionally, the antioxidant capacity of the subfraction and its main compounds (phytol and hexadecenoic acid methyl ester) were determined as well as their effects on parasite viability. Hsf1 exhibited a dose-dependent inhibitory effect on the lytic process at a concentration of 47.2 µg/mL. Among the eighteen compounds identified in this subfraction, six were evaluated, of which two (phytol and hexadecanoic acid methyl ester) significantly reduced the viability of T. gondii to 0.11% and 16.6%, respectively, at a concentration of 100 µg/mL. Additionally, Hsf1 demonstrated an antioxidant capacity of 30% as assessed using the ORAC method. The two active compounds also exhibited antioxidant properties, with antioxidant capacities of 13.33% and 33% for hexadecanoic acid methyl ester and phytol, respectively, at concentrations up to 15.4 mg/mL. Hsf1 showed membrane damage and conoid extrusion in T. gondii tachyzoites, suggesting direct interference with the lytic cycle of the parasite. These findings underscore the therapeutic potential of Hsf1 as a promising tool for controlling infections caused by T. gondii, thereby providing an alternative in the search for new antiparasitic agents. However, further research is required to determine the in vivo pharmacological effects and properties of these compounds with potential anti-Toxoplasma activity. Full article

Fires significantly influence the ecosystems of Western Siberia’s forest–tundra zone. Namely, they alter soil processes, including the transformation of different forms of iron and the redistribution of carbon flows. Recent climate change, associated with increased fire frequency, has had a long-term effect on the Arctic and sub-Arctic soil systems. Iron plays a key role in stabilizing organic carbon through the sorption and coagulation processes, yet the long-term changes in iron’s fractional composition under post-fire conditions remain insufficiently studied. This research investigates the impact of natural fires on the transformation of iron forms (amorphous, crystalline, and mobile), as well as on the dynamics of organic carbon in soils within the northern boundary of the forest–tundra natural zone in Western Siberia, between the Pur and Taz rivers. In our study, we have relied on granulometric and chemical analyses, magnetic susceptibility measurements, and iron fraction extractions. Our findings reveal that in post-fire areas, the depth of the seasonally thawed layer increases, accompanied by changes in the thermal and water regimes. This leads to reduced organic carbon content, particularly in intermediate horizons (5–30 cm), and the transformation of amorphous iron into a crystalline form. Crystallization growth is confirmed by increased magnetic susceptibility. Our results highlight the dual role of iron compounds: they contribute to the long-term stabilization of organic carbon, as well as causing its accelerated mineralization by affecting redox conditions. This study is crucial for understanding the biogeochemical processes associated with climate change and increasing fire frequency. Full article

Icicles are elongated structures formed from water flowing over hangings and crystallizing in sub-freezing conditions. These features are ubiquitous in several parts of the world that experience severe to moderate winter seasons. It has been suggested that they could be a source of recharge to groundwater. Icicles are presumed to affect groundwater quality via incorporation of atmospheric and roof top contaminants. Relatively little attention has been paid to these wintry features, insofar as only a few theoretical models have attempted to describe their formation. Stable isotope measurements (δ¹⁸O and δ²H) of icicles that were melted stepwise into fractions are presented as support for the models that invoke the rapid formation of icicles. Icicles exhibit minimal fraction to fraction isotope variation, suggesting a lack of isotope equilibrium and that kinetic effects dominate the freezing process. Deviations from the Global Meteoric Water Line (GMWL), which is similar to the Local Meteoric Water Line (LMWL), indicate that post-depositional processes, namely sublimation, may occur throughout the freezing process. Isotopic evidence lends support to a “growth-cessation-growth” variation of the already proposed methods of rapid icicle formation, where a cessation period occurs between pulses of rapid freezing during icicle growth. Full article

In this study, we investigated the effect of particle size and solids loading on the magnesite yield in the direct aqueous mineral carbonation of heat-activated lizardite. Experimentation was conducted under single-step reaction conditions (130 bar partial pressure of carbon dioxide (CO₂) and 150 °C, with 0.64 M sodium bicarbonate (NaHCO₃) and 15 wt% solids) as developed by the Albany Research Center (ARC). The objective of the study was to enhance the understanding of the direct aqueous mineral carbonation process in heat-activated lizardite. Furthermore, we aimed to shed light on how variations in particle size could affect the reaction rate, yield, and the development of protective silica layers. Our experimental data suggest that the extraction of magnesium from finer particles (sub 20 µm) is marginally more effective than from the larger size fractions. This difference likely stems from the larger surface area of fine particles (sub 20 µm) in both low and high solids loading experiments. The highest magnesite yield was 50% after 60 min, and this was achieved for both solids loadings (5 and 15 wt%), demonstrating that the solids loading had no impact on the yield. Our findings indicate rapid heat-activated lizardite reaction within 20 min, which achieved 34% and 40% conversion for 5 wt% and 15 wt% solids loading, respectively. This is followed by declining rates with increasing solids loading. Full article

The Kuralay-II system (K-IIS) plays a pivotal role in modeling sophisticated nonlinear wave processes, particularly in the field of optics. This study introduces novel soliton solutions for the K-IIS, derived using the Riccati–Bernoulli sub-ODE method combined with Bäcklund transformation and conformable fractional derivatives. The obtained solutions are expressed in trigonometric, hyperbolic, and rational forms, highlighting the adaptability and efficacy of the proposed approach. To enhance the understanding of the results, the solutions are visualized using 2D representations for fractional-order variations and 3D plots for integer-type solutions, supported by detailed contour plots. The findings contribute to a deeper understanding of nonlinear wave–wave interactions and the underlying dynamics governed by fractional-order derivatives. This work underscores the significance of fractional calculus in analyzing complex wave phenomena and provides a robust framework for further exploration in nonlinear sciences and optical wave modeling. Full article