Search Results (146)

The present work analyzes light propagation in asymmetric waveguides with dielectric cores and anisotropic multilayer claddings based on nanometric planar hyperbolic metamaterials. A generalized definition of asymmetry, incorporating both structural and physical parameters, is introduced by varying metal composition and filling ratios in the claddings. The influence of wavelength, material permittivity, metal filling fraction, and core thickness on surface wave modes is examined using effective medium theory and considering experimentally derived material data. Propagation distances on the order of 400 µm have been achieved for optimized waveguide configurations operating within the C-band used in optical telecommunications. Full article

Machine learning (ML)-assisted design of epsilon-negative polymer nanocomposites requires a clear connection between experimentally controllable synthesis parameters, core–shell nanoparticle geometry, and the resulting effective optical response. The targeted optical response is unusual because the polymer film is predicted to exhibit near-zero or negative real effective permittivity in selected visible spectrum regions, arising from Ag core plasmonic polarizability, SiO₂-mediated dielectric spacing, nanoparticle filling factor, and effective medium coupling rather than from the intrinsic polymer matrix. In this study, a two-stage ML-assisted synthesis-to-optics framework is developed for Ag@SiO₂ core–shell nanoparticle/polymer composite films intended for visible spectrum effective permittivity screening. In the first stage, Stöber synthesis parameters, including water volume, ethanol volume, TEOS content, catalyst volume, reaction time, Ag nanoparticle size, and Ag nanoparticle concentration, were used to predict SiO₂ shell thickness. In the second stage, Ag core size, SiO₂ shell thickness, wavelength, and nanoparticle filling factor were used to screen the real effective permittivity of Ag@SiO₂/polymer nanocomposites within an effective medium design space. Using a duplicate-aware validation workflow, Gradient Boosting provided the strongest held-out test performance for shell thickness prediction, with a test R² of 0.8997, MAE of 7.1822 nm, RMSE of 8.8344 nm, and cross-validation R² of 0.5371 ± 0.4648. The relatively large cross-validation variability indicates that the model is useful for interpolation-based synthesis screening but should not be interpreted as fully robust across heterogeneous literature-derived data. For the optical response task, the highest held-out test performance was obtained by a Decision Tree model (test R² = 0.7586), but cross-validation results were unstable, indicating that the epsilon model should be interpreted as a design space screening tool rather than a generalizable predictor. Design window analysis identified candidate negative effective permittivity regions primarily at 400 nm and high nanoparticle filling factor, with predicted $\mathrm{R}\mathrm{e}\left({\epsilon }_{\mathrm{e}\mathrm{f}\mathrm{f}}\right)$ values ranging from −5.4229 to −0.2086 across selected windows. The main contribution of this work is the treatment of SiO₂ shell thickness as a bridge variable between Stöber-derived synthesis control and effective permittivity screening. Experimental validation remains necessary to confirm the predicted design windows, particularly because shell uniformity, Ag core polydispersity, nanoparticle aggregation, polymer dispersion, high-filling-factor feasibility, and effective medium validity can strongly influence the measured optical response. Full article

To address the lack of systematic quantitative studies on waterborne epoxy resin (WER)-modified emulsified asphalt regarding its rheological optimization and engineering applicability, this study fills the gap by preparing WER-modified emulsified asphalt via a two-step process. New findings reveal that 20% WER content significantly enhances elastic components, creep–recovery, fatigue life, and fracture energy. The main objective is to establish a theoretical basis for high-performance pavement materials. Modified emulsified asphalt specimens with different waterborne epoxy resin contents were prepared using a two-step method of “emulsification followed by compounding”. The stability of the emulsions was quantitatively evaluated by zeta potential, storage stability, particle size distribution, and demulsification time. Their rheological parameters, multi-stress creep–recovery characteristics, fatigue life, and low-temperature crack resistance were systematically tested across the full temperature range using a dynamic shear rheometer and a bending beam rheometer. In addition, the bonding performance, strength development behavior, and water resistance durability were comprehensively assessed through pull-out tests, Marshall stability and splitting strength tests, as well as freeze–thaw cycle tests. These properties were compared with those of unmodified emulsified asphalt (UEA-0) and SBR-modified emulsified asphalt (SBR-EA). With an increase in waterborne epoxy resin content, the elastic component of the modified asphalt improved significantly, and the phase angle continuously decreased. The specimen with 20% waterborne epoxy resin content (WER-EA-20) exhibited the best performance: its phase angle was lower than those of the other groups under high-, medium-, and low-temperature conditions. After seven creep–recovery cycles, its creep–recovery rate remained at 33%, substantially higher than the 8% observed for the unmodified specimen. The fatigue life reached 15,000 cycles under a shear stress of 2.1 MPa. At −10 °C, the fracture strength was 0.92 MPa, and the fracture energy reached 21.4 J. Furthermore, the pull-out strength of WER-EA-20 was 0.86 MPa, with the failure mode identified as asphalt cohesive failure. After 37 days of curing, the Marshall stability reached 22.5 kN, and the splitting strength was 1.36 MPa. After 40 freeze–thaw cycles, the freeze–thaw splitting strength ratio (TSR) of WER-EA-20 remained above 75%, representing an improvement of more than 110% compared to the unmodified UEA-0 (TSR ≈ 35.5%), which highlights the significant enhancement in water resistance imparted by the waterborne epoxy resin. Compared to SBR-EA, WER-EA-20 has a higher softening point, a lower suitable mixing temperature, and better anti-aging properties. Waterborne epoxy resin can effectively improve the viscoelastic properties and overall road performance of emulsified asphalt, and the modification effect increases with increasing dosage. Full article

In order to address the problems of manual dependence, low replenishment efficiency, and insufficient operational continuity in unmanned field operations of large sprayers, an autonomous docking device for an unmanned replenishment vehicle was designed. The device is composed of three principal components: a robotic-arm docking system, a pesticide delivery system, and a docking control system. RTK positioning information is utilised to determine the relative position between the unmanned replenishment vehicle and the large sprayer. The robotic arm approaches the high-position filling port, and the end effector completes guidance, flexible compensation, and electromagnetic coupling. A geometric model of the robotic arm was established, and its workspace was analysed using the Monte Carlo method. Single-factor tests and response surface optimization tests were conducted to optimize the key parameters of the end effector, and robotic arm control accuracy tests and field collaborative docking tests were carried out to evaluate the performance of the device. The results showed that the workspace of the designed robotic arm covered the elevated filling-port area of the large sprayer and met the docking requirements within a vehicle spacing of 0.25–1.25 m. After parameter optimization, the predicted cumulative docking time of the end effector was 2.051 s. The field collaborative docking test showed that, within a vehicle spacing range of 25–125 cm, 56 of 60 docking trials were successful, giving an overall success rate of 93.33%. Within the medium-spacing range, stable docking was achieved with an average docking time of 44.10–47.89 s. The results indicate that the proposed autonomous docking device can support unmanned vehicle approach, robotic arm positioning, end-effector guidance, and stable pesticide replenishment of large sprayers. Full article

Background/Objectives: Early childhood caries (ECC) is a chronic inflammatory condition that may impose a systemic burden in pediatric patients. This study aimed to evaluate the association between dental caries severity, classified by dmft (decayed, missing, and filled teeth for primary dentition) scores, and preoperative systemic inflammatory markers derived from routine complete blood counts (CBC). Methods: This retrospective study included 159 children aged 36–71 months. Participants were categorized into three groups based on dmft scores: low (0–3), medium (4–8), and high (≥9). Hematological parameters and inflammatory indices, including neutrophil-to-lymphocyte ratio (NLR) and systemic immune-inflammation index (SII), were analyzed using one-way ANOVA with post hoc comparisons. Results: Significant differences were observed among dmft groups for neutrophil and lymphocyte percentages (p = 0.026 and p = 0.027) and lymphocyte count (p = 0.020). The medium severity group demonstrated higher neutrophil levels and lower lymphocyte values compared to the high severity group (p < 0.05). Although overall group differences for NLR and SII were not statistically significant (p > 0.05), both markers were significantly higher in the medium group than in the high group (p < 0.05). No significant differences were found in hemoglobin, RDW, or platelet parameters. Conclusions: A non-linear trend was observed, with relatively elevated inflammatory markers in the moderate dmft group. These findings suggest that systemic inflammation in ECC is more closely related to disease characteristics than to caries burden alone. CBC-derived parameters may provide supportive but limited value for assessing systemic inflammatory status in pediatric dental patients. Full article

Chromium nitride (CrN) can be used as a coating material deposited via physical vapour deposition (PVD), thereby improving the corrosion and wear resistance of the substrate. However, this level of corrosion protection may not be sufficient in an aggressive corrosion environment. The coatings often contain intrinsic microstructural defects, such as microcraters, which can serve as pathways for the corrosive medium to reach the substrate, thereby initiating and promoting corrosion. In this study, the influence of parameters on the formation of a TiO₂ layer using the ALD technique was investigated. In particular, the work focused on assessing the effectiveness of the TiO₂ layer as a sealing barrier for CrN coatings (PVD) applied to austenitic 316L steel. The TiO₂ ALD coatings were produced at a constant temperature of 200 °C with a varying number of cycles, ranging from 200 to 1000 cycles. Structural investigations were carried out using scanning electron microscopy SEM and atomic force microscopy. Electrochemical properties were investigated using a potentiodynamic test and electrochemical impedance spectroscopy (EIS) in a 3.5% NaCl solution. SEM observations indicate that the morphology of the hybrid coatings is strongly influenced by the number of ALD cycles. The TiO₂ layer conformally reproduces the underlying PVD topography while progressively sealing the coating by filling intrinsic defects and discontinuities. Hybrid coatings (PVD/ALD) with titanium oxide deposited at 500 ALD cycles were found to have the best corrosion resistance. The polarisation resistance for these coatings was nearly four times higher than that of both the single PVD (CrN) coating and the uncoated stainless steel 316L substrate. At the same time, the corrosion current density was several times lower than that of the reference systems. The corrosion mechanisms were investigated by observing the surfaces of the samples after corrosion testing using SEM. Abrasion resistance tests using the pin-on-disc method and adhesion tests (scratch tests) were also performed, which showed that appropriate optimisation of the layer architecture in the PVD/ALD hybrid system significantly improves its tribological durability, interlayer stability, and adhesion to the substrate. Full article

A preliminary analysis of aircraft refueling using liquid hydrogen (LH2) for a future short–medium-range aircraft is presented. The focus is on how selected refueling parameters influence pressure buildup and the release of boil-off gas (BOG), in order to establishing guidelines towards efficient refueling. The flow physics uses a 0-D multi-phase lump model, which accounts for the effects of the injected LH2, BOG release, heat fluxes and phase changes. Refueling is controlled by volumetric compression during the filling, and relaxation afterwards. Mass-flow profile and refueling protocol have little influence on the amount of BOG vented (~1%), but control the duration of the process, with variations close to 50%. Low initial pressure can significantly reduce the amount of BOG. Full article

Introduction: The growing demand for traditional medicines and health supplements (TMHS) in Malaysia has raised concerns regarding microbial contamination in hard-shell capsule products. Despite regulatory oversight, recurring recalls highlight persistent non-compliance with Good Manufacturing Practice (GMP) standards. This study examines the risks of microbial contamination, recall patterns, and encapsulation practices among TMHS hard-shell capsule manufacturers in Malaysia. Methods: A cross-sectional approach was employed, comprising a review of regulatory guidelines, analysis of NPRA recall data from 2020 to 2024, and a structured survey of 86 TMHS manufacturers on equipment and production parameters. Results: Review of GMP guidance indicated that greater automation and reduced manual handling in capsule-filling processes help minimise microbial contamination. In line with this, TMHS products were recalled at a rate of 4.73%, more than 4 times the pharmaceutical recall rate (1.09%). Among the 245 TMHS recalls, 68 involved hard-shell capsule products that failed microbial testing, primarily total aerobic microbial count (73.53%). Additionally, manufacturers with 50–100 registered products had significantly higher odds of recall (OR = 10.0, 95% CI: 2.35–42.47). However, no significant associations were found between recall status and equipment type, capsule size, or production frequency. Conclusions: Microbial contamination remains a critical issue in TMHS hard-shell capsule products. Regulatory efforts should focus on medium-scale manufacturers and reinforce risk-based GMP adherence to enhance product safety and public health protection. Full article

Niobium is a strategic critical mineral that supports emerging energy and high-end manufacturing. The geophysical parameters of carbonatite-alkaline rock-type niobium deposits constitute essential baseline data for regional geophysical exploration and prospecting target delineation. To clarify the geophysical response characteristics and exploration the significance of the Dagele niobium deposit in the Eastern Kunlun Region (western China). This study focuses on drill hole ZK3202. Samples from ore bodies, mineralized zones, and wall rocks of different lithologies were continuously measured. Combined with 1001.8 m of full-hole core digital logging data, statistical methods, including box plots, histograms, multi-parameter cross-plots, and correlation coefficient analysis, were applied to quantitatively investigate the physical property responses of lithologies such as calcite-biotite rock (ore body), calcite-bearing pyroxenite (mineralized zone) and amphibolite in the vertical profile. Lithological identification thresholds were established to divide the drill-hole into lithological and mineralized ore layers. The results show that the ore-bearing lithofacies exhibit a distinctive geophysical signature characterized by high density, strong magnetism, medium-low resistivity, high polarizability, and slightly elevated natural radioactivity, which clearly distinguishes them from surrounding from wall rocks. Based on five key parameters—density, magnetic susceptibility, resistivity, polarizability, and natural gamma—a lithological identification model for amphibolite and mineralized altered rock assemblages was established. This study also summarizes the multi-parameter coupling mechanism of ore-bearing lithofacies, which can effectively delineate favorable niobium-bearing horizons. This work fills a gap in the geophysical property characterization of carbonatite-alkaline complex-type niobium deposits in the Eastern Kunlun region and provides data support and regional reference for integrated gravity-magnetic-electrical-radioactive geophysical exploration, prospecting target delineation, and the exploration of similar niobium deposits in western China. Full article

The operation of the gas–steam–electricity multi-energy coupling system in iron and steel enterprises faces critical challenges: conflicts between energy efficiency and economic objectives, insufficient scheduling accuracy, and low energy utilization caused by source–load fluctuations. To address these issues, this paper proposes a hybrid scheduling model based on condition awareness and multi-objective optimization. The model integrates three key components. First, an energy fluctuation prediction technology based on working condition changes is developed. By acquiring real-time production signals and gas flow data, combined with a condition definition management module, it enables automatic identification and tracking of equipment operation status. A working condition sample curve superposition method is used to calculate energy medium imbalances, generating visual prediction curves for key parameters such as blast furnace, coke oven, and converter gas holder levels, achieving an average prediction accuracy of ≥95%. Second, a peak-shifting and valley-filling scheduling model for gas holders is designed, leveraging time-of-use electricity prices. During valley price periods, power purchases are increased and surplus gas is stored; during peak price periods, gas power generation is increased to reduce purchased electricity. A nonlinear model capturing the load–efficiency relationship of boilers and generators is established to dynamically optimize scheduling strategies. This reduces the proportion of peak hour power purchases by 10.3%, energy costs by 3.12%, and system energy consumption by 2.16%. Third, a multi-period and multi-medium energy optimization scheduling model is formulated as a mixed-integer nonlinear programming (MINLP) problem, with dual objectives of minimizing operating cost and energy consumption. Constraints include energy supply–demand balance, equipment operating limits, gas holder capacity, and generator ramp rates. The Pareto optimal solution set is obtained using the AUGMECON2 method and efficiently computed with the IPOPT solver. Application results demonstrate that the model achieves zero gas emissions, a dispatching instruction accuracy of 95%, and a 0.8% increase in the proportion of peak–valley-level self-generated power, outperforming comparable technologies. It provides technical support for the safe, efficient, and economic operation of multi-energy systems in iron and steel enterprises. Full article

As a key low-expansion material for high-end equipment such as aerospace and precision instruments, the surface quality of Invar alloy directly determines the operational performance of devices. To fill the research gap in the multi-parameter synergy and mechanism of Invar alloy laser polishing, this study performs polishing experiments on Invar alloy using a burst-mode femtosecond laser, with a repetition rate of 1 MHz and four sub-pulses per burst. The results indicate that energy density plays a dominant role in the polishing effect: with the increase in energy density, the surface roughness first decreases and then increases. A stable molten pool is formed under medium energy density (0.47–0.64 J/cm²), and under the optimal parameter conditions, the surface roughness is reduced to 394 ± 50 nm, representing a 52% reduction compared to the original surface (821 nm). Scanning speed and scanning pitch affect the polishing effect by synergistically regulating energy input: increasing scanning speed under high energy density can inhibit the rise in roughness, while a small scanning pitch can lower the threshold of optimal energy density. Amplitude spectrum analysis reveals that the medium-scale surface undulations are significantly improved after polishing. A four-layer Fully Connected Neural Network (FCNN) model is established to achieve high-precision prediction of polishing effects with a coefficient of determination R² = 0.92, which enables rapid prediction of unknown polishing parameter combinations and provides a new solution path for the optimization of polishing effects. This study clarifies the interaction mechanism between a burst-mode laser and Invar alloy, proposes an efficient ultra-precision polishing method for Invar alloy, and lays a theoretical foundation for its application in the field of high-end manufacturing. Full article

This paper investigates the linear stability of Navier–Stokes–Voigt (NSV) fluid flow in a channel filled with a homogeneous porous medium under general asymmetric slip boundary conditions. This study bridges the research gap between idealized theoretical models (uniform coating) and realistic engineering surfaces in superhydrophobic channels. In practice, manufacturing defects often lead to non-uniform slip distributions. By solving the generalized eigenvalue problem using the Chebyshev spectral collocation method, we quantify the sensitivity of the critical Reynolds number to symmetry breaking. The results reveal that symmetric slip achieves optimal stability, whereas symmetry breaking causes a significant destabilizing effect. Energy analysis clarifies the physical origin of this instability. Furthermore, we find that increasing the porous medium permeability parameter or the Voigt regularization parameter effectively counteracts the slip-induced instability. Specifically, flow stability can be restored even under highly asymmetric slip conditions if the porous damping or the viscoelastic regularization effect is sufficiently strong. This implies that inevitable manufacturing defects in engineering can be compensated for by optimizing the porous medium matrix. Full article

Two challenges that have a permanent presence on the Moon are solar and cosmic radiation, as well as the large surface temperature variation between lunar day and night. To address these problems, we propose a lunar pathfinder mission concept that uses robotic systems to investigate whether regolith-filled bags can be used as a versatile construction medium for lunar surface structures and sensors to obtain data on the lunar regolith. The primary objectives of this mission are as follows: evaluation of the surface and subsurface regolith as fill material, lunar excavation using a robotic manipulator equipped with a bucket scoop, bag filling using a proposed robotic bagging system, the stacking of the filled bags with a robotic manipulator into a simple berm structure, and verification of the completed regolith-filled bag berm. Additional objectives include assessing the local radiation environment and testing Wi-Fi technology for use in and around a lunar surface station, such as the proposed Artemis Base Camp. Where possible, high TRL technologies are presented for each mission objective, which will be carried to the lunar surface on a Commercial Lunar Payload Services (CLPS) lander. A novel regolith bagging system concept is presented. The feasibility of the overall mission concept is studied by investigating key mission parameters, which shows the presented technologies fulfill all mission parameters. Potential extended mission concepts that exercise increased levels of autonomy are also presented, which may provide additional data to inform the development of this technology for future, at-scale, deployment. Full article

Composting chicken manure is a source of significant ammonia (NH₃) emissions, which, because of propagation, contributes to the eutrophication of the environment and decreases in air quality. Therefore, it is reasonable to use methods to limit its emission into the atmosphere. Biofiltration, using the metabolic activity of nitrifying and heterotrophic microorganisms capable of oxidizing ammonia, is an effective method to reduce ammonia emissions. In addition, the performance of the biofiltration process depends on operational parameters such as the humidity of the medium, the temperature, the contact time of the gas with the biofiltering medium, and the chemical composition and structure of the filter material. The aim of the study was to evaluate the effectiveness of biofilter fillings in reducing ammonia emissions from composting chicken manure along with the identification of factors allowing us to determine the proposed design solution as the most advantageous in terms of efficiency. Experiments on reducing odour emissions with biofiltration were carried out in two compact composting reactors, in which a compost mixture with a C:N ratio of 10:1 was used. The mixture was prepared in a ratio of 5:1 of chicken manure to the structuring material, with wheat straw used as the structuring material. Based on the results of the research on the course of the composting process, high values of ammonia concentration were recorded. Ammonia concentrations of 886 ppm (composter 1) and 811 ppm (composter 2) were recorded, which confirms the intensive nature of this gas emissions during the process of stabilizing the chicken manure. As part of the conducted research, the effectiveness of biofiltration in reducing ammonia emissions was evaluated by analysing the influence of the aeration intensity of the biofilter (20 dm³/h and 50 dm³/h), directly determining the time of contact of the gas with the bed (EBCT—Empty Bed Contact Time). Coconut-activated carbon was used as a filter bed, which was an effective carrier for the development of microorganisms responsible for the biological removal of ammonia from waste gases generated during composting. In addition, this material showed the ability to physically adsorb ammonia, thus supporting the process of its elimination. Each of the test stations has been equipped with a biofiltration installation. To determine the effectiveness of biological removal of ammonia and to assess the legitimacy of the use of selected strains of microorganisms in the process of biological removal of ammonia, the bed of one of the biofilters (biofilter 2) was inoculated with a strain of nitrifying bacteria. During the study, the high efficiency of ammonia removal because of biofiltration was noted in each of the configurations. In the case of an aeration intensity of 20 dm³/h, a reduction in emissions of 99% was achieved; with a higher aeration value, i.e., 50 dm³/h, the efficiency was 89%. These results indicate that the intensity of aeration has a significant impact on the efficiency of the biofiltration process. The analysis of a biofilter enriched with a strain of nitrifying bacteria requires long-term testing. This is important to reliably determine the effect of inoculation on the efficiency of the biological removal of ammonia in biofilters. It has been shown that optimizing these factors allows us to achieve a reduction in ammonia emissions of up to 90%, while minimizing the formation of unpleasant odours. The use of biofiltration in composting systems for organic waste of animal origin is an effective, sustainable solution that fits into the idea of sustainable development, combining the efficiency of air purification technology with environmental protection and the responsible management of resources. This study demonstrates that biofiltration using coconut-shell-activated carbon is an effective and economical method for reducing ammonia and odour emissions from composting chicken manure. The results provide valuable theoretical and practical information on emissions management in organic waste composting processes. Data from this study could be useful in developing strategies to minimize odour emissions, including from the agricultural sector. Full article

Foam lightweight soil (FLS) has emerged as a promising material in geotechnical engineering due to its low density, high load-bearing capacity, and ability to incorporate industrial by-products such as fly ash. It offers significant advantages in mitigating settlement and improving stability for embankments constructed on soft soil foundations. However, the combined influence of key parameters—including layered filling thickness, bulk density, and geogrid reinforcement—on the long-term performance of FLS embankments remains insufficiently understood. This study investigates the settlement behavior and stability of FLS embankments through a combination of field experiments and finite element simulations over a 15-year period. The results indicate that layered filling thicknesses of 500–600 mm achieve the best balance between settlement control and construction feasibility. When the thickness exceeds 800 mm, not only does the uniformity deteriorate, but the settlement also increases. Experimental results showed that a medium bulk density of 6 to 8 kN/m³ is optimal as a balance between strength and settlement behavior. Furthermore, geogrid reinforcement significantly improved stability, with safety factors increasing by up to 1.87 compared to unreinforced sections. The findings provide practical guidelines for the design and construction of FLS embankments, particularly for bridge approaches and soft soil foundations. In addition to improving structural performance, the incorporation of industrial by-products highlights the potential of FLS as a sustainable and cost-effective material for future infrastructure development. Full article