Search Results (17,398)

Autonomous ship control faces significant challenges due to the diversity of ship types, the complexity of task scenarios, and the uncertainty of dynamic marine environments. These factors limit the effectiveness of traditional control approaches that rely on explicit dynamics modeling and handcrafted control laws. With the rapid advancement of computing and artificial intelligence, imitation learning offers a promising alternative by directly learning expert behaviors from data. This paper proposes a Generative Adversarial Imitation Learning (GAIL) method for heading and path-following control of autonomous surface ships. It employs an adversarial learning structure, in which a generator learns control policies that reproduce expert behavior while a discriminator distinguishes between expert and learned trajectories. In this way, the control strategies can be learned from expert demonstrations without requiring explicit reward design. The proposed method is validated through simulations on a model-scale tug. Compared with a behavioral cloning (BC) baseline controller, the GAIL-based controller achieves superior performance in terms of path-following accuracy, heading stability, and control smoothness, confirming its effectiveness and potential for real-world deployment. Full article

Cobalt-based bulk metallic glasses (Co-based BMGs) offer a combination of high strength, corrosion resistance, and soft magnetic properties, yet their limited glass-forming ability (GFA) and poor room-temperature ductility restrict broader application. In this study, a microalloying strategy was applied to the Co₆₁Nb₈B₃₁ base composition to develop Co-Nb-B-Si and Co-Fe-Nb-B-Si systems. The effects of Si addition and Fe substitution on GFA, thermal stability, and mechanical properties were systematically investigated. Si doping combined with Co/B ratio tuning broadened the supercooled liquid region and increased the critical glass-forming diameter from 1 mm to 3 mm. Further addition of 5 at.% Fe expanded the supercooled liquid region and enabled the fabrication of a fully amorphous plate with 1 mm thickness. The optimized Co₆₃Nb₈B₂₇Si₂ alloy exhibited a compressive strength of 5.18 GPa and a plastic strain of 3.81%. Fracture surface analysis revealed ductile fracture features in the Si-containing alloy and brittle characteristics in Fe-rich compositions. These results demonstrate that microalloying is effective in optimizing the balance between GFA and mechanical performance of Co-based BMGs, offering guidance for composition and processing design. Full article

Nickel-based metal–organic frameworks (Ni-MOFs) have received enormous amounts of attention from the scientific community due to their excellent porosity, larger specific surface area, tunable structure, and intrinsic redox properties. In previous years, Ni-MOFs and their hybrid composite materials have been extensively explored for electrochemical sensing applications. As per the reported literature, Ni-MOF-based hybrid materials have been used in the fabrication of electrochemical sensors for the monitoring of ascorbic acid, glucose, L-tryptophan, bisphenol A, carbendazim, catechol, hydroquinone, 4-chlorophenol, uric acid, kaempferol, adenine, _L-cysteine, etc. The presence of synergistic effects in Ni-MOF-based hybrid materials plays a crucial role in the development of highly selective electrochemical sensors. Thus, Ni-MOF-based materials exhibited enhanced sensitivity and selectivity with reasonable real sample recovery, which suggested their potential for practical applications. In addition, Ni-MOF-based hybrid composites were also adopted as electrode modifiers for the development of supercapacitors. The Ni-MOF-based materials demonstrated excellent specific capacitance at low current densities with reasonable cyclic stability. This review article provides an overview of recent advancements in the utilization of Ni-MOF-based electrode modifiers with metal oxides, carbon-based materials, MXenes, polymers, and LDH, etc., for the electrochemical detection of environmental pollutants and biomolecules and for supercapacitor applications. In addition, Ni-based bimetallic and trimetallic catalysts and their composites have been reviewed for electrochemical sensing and supercapacitor applications. The key challenges, limitations, and future perspectives of Ni-MOF-based materials are discussed. We believe that the present review article may be beneficial for the scientific community working on the development of Ni-MOF-based materials for electrochemical sensing and supercapacitor applications. Full article

With the increasing demand for urban rail transit capacity, shield tunneling has become the predominant method for constructing underground metro systems in densely populated cities. However, the spatial interaction between shield tunnels and adjacent retaining structures poses significant engineering challenges, potentially leading to excessive ground settlement, structural deformation, and even stability failure. This study systematically investigates the deformation behavior and associated risks of retaining systems during adjacent shield tunnel construction. An orthogonal multi-factor analysis was conducted to evaluate the effects of grouting pressure, grout stiffness, and overlying soil properties on maximum surface settlement. Results show that soil cohesion and grouting pressure are the most influential parameters, jointly accounting for over 72% of the variance in settlement response. Based on the numerical findings, a Bayesian network model was developed to assess construction risk, integrating expert judgment and field monitoring data to quantify the conditional probability of deformation-induced failure. The model identifies key risk sources such as geological variability, groundwater instability, shield steering correction, segmental lining quality, and site construction management. Furthermore, the effectiveness and cost-efficiency of various grouting reinforcement strategies were evaluated. The results show that top grouting increases the reinforcement efficiency to 34.7%, offering the best performance in terms of both settlement control and economic benefit. Sidewall grouting yields an efficiency of approximately 30.2%, while invert grouting shows limited effectiveness, with an efficiency of only 11.6%, making it the least favorable option in terms of both technical and economic considerations. This research provides both practical guidance and theoretical insight for risk-informed shield tunneling design and management in complex urban environments. Full article

The role of science and technology in enhancing beer quality is crucial amid growing market demands. This pilot study assessed the clarity and physicochemical stability of laboratory beers treated post fermentation with three clarifying (fining) agents: two chitosan-based and one collagen-based (fish bladder/isinglass). The beers were brewed with Polish barley malt and hops (alpha acids 7.5% and 14.5%). The measured parameters included pH, colour, turbidity, viscosity, surface tension, and foam volume. Within this small-scale, low-power dataset, both the collagen- and chitosan-based agents improved clarity, with the collagen agent showing the lowest turbidity in this sample. The clarifying agents also influenced the colour and surface tension, while the pH was largely unchanged. The foam volume increased with fining. Shelf-life checks suggested improved stability in clarified beers, with no clear differences between agents under these conditions. These findings are preliminary. The results should be interpreted cautiously due to the limited number of replicates. Larger scale studies with adequate replication are required before translating these observations into brewing practice. Chitosan's effectiveness as a clarifying agent aligns with its high charge density and ability to coagulate suspended particles. This study underscores the importance of selecting appropriate clarifying agents to optimize beer clarity and stability while maintaining essential physicochemical properties. These findings contribute to the brewing industry's efforts to meet consumer expectations for high-quality, stable beer products. Full article

Foam acidification is often employed as a clean and efficient method to remove blockages from wells and promote oil and gas production. In order to effectively control the diffusion of H⁺ in the acid solution into the rock surface, reduce the acid–rock reaction rate, and achieve deep acidification, a foam-retarding acid with foam stability, temperature and salt resistance, and excellent retarding performance was prepared by studying the synergistic effect of the foaming agent and foam stabilizer. ZG-A was used as the foaming agent, and ZG-B was added as a foam stabilizer to achieve foam stabilization. When the ZG-A/ZG-B ratio was 0.67%/0.33%, the foam exhibited the best comprehensive performance. By measuring and comparing the acid–rock reaction rate under different conditions, the results showed that the average acid–rock reaction rate of the 10% compound acid was 1.412 × 10⁻³ mg/(cm²·s), while the average acid–rock reaction rate of the foam-retarding acid system was reduced to 6.622 × 10⁻⁵ mg/(cm²·s), representing a reduction of two orders of magnitude, and the slow rate reached 95.31%. Foam fluid diversion experiments were carried out on cores with different permeabilities. The results showed that the foam could increase the diversion flow rate of low-permeability cores and reduce the diversion flow rate of high-permeability cores. Thus, the foam fluid could be uniformly propelled in cores with different permeabilities. Based on this principle, foam acid acidification can increase the amount of acid injection into the low-permeability layer and reduce the amount of acid absorption in the high-permeability layer, thereby improving the acidification effect. Full article

In this study, 10% nitric acid was employed to remove the aluminum coating on the cobalt-based superalloy K6509, with a focus on elucidating the corrosion mechanism and evaluating the effect of ultrasonic on the removal process. The results shows that ultrasonic treatment (40 kHz) significantly improves coating removal efficiency, increasing the maximum corrosion rate by 46.49% from 2.5413 × 10⁻⁷ g·s⁻¹·mm⁻² to 4.7488 × 10⁻⁷ g·s⁻¹·mm⁻² and reducing removal time from 10 min to 6 min. This enhancement is attributed to cavitation effect of ultrasonic bubbles and the shockwave-accelerated ion diffusion, which together facilitate more efficient coating degradation and results in a smoother surface. In terms of corrosion behavior, the difference in phase composition between the outer layer and the interdiffusion zone (IDZ) plays a decisive role. The outer layer is primarily composed of β-(Co,Ni)Al phase, which is thermodynamically less stable in acidic environments and thus readily dissolves in 10% HNO₃. In contrast, the IDZ mainly consists of Cr₂₃C₆, which exhibit high chemical stability and a strong tendency to passivate. These characteristics render the IDZ highly resistant to nitric acid attack, thereby forming a protective barrier that limits acid penetration and helps maintain the integrity of the substrate. Full article

Aim: This study evaluated the effect of manual and electronic toothbrushes on the color stability (∆E*) and surface roughness (Ra) of four CAD/CAM ceramics after their immersion in coffee for 2 and 4 weeks. Methodology: A total of 160 specimens (Vitablocs Mark II, Ceramill Zolid zirconia, Vita Triluxe Forte, and IPS e.max CAD) were divided into four brushing subgroups (manual, sonic, oscillating–rotating, and ionic). The samples underwent daily coffee staining, thermocycling (5–55 °C), and twice-daily brushing. Color parameters (L, a, and b) were assessed and measured utilizing a spectrophotometer (Vita Easyshade) at baseline, 2 weeks, and 4 weeks. ∆E* was calculated using the CIEDE2000 formula, and surface roughness (Ra, µm) was assessed via contact profilometry at the study’s conclusion. Data were analyzed using Kruskal–Wallis and Mann–Whitney tests (α = 0.05). Results: Among the tested samples, IPS e.max ceramic with manual toothbrushing exhibited the highest ΔE* values after 2 and 4 weeks (∆E* = 4.424 and ∆E* = 4.802) of immersion. Moreover, Ceramill Zolid zirconia demonstrated the highest ΔE* values with ionic brushing (∆E* = 4.883 at 2 weeks; ΔE* = 4.760 at 4 weeks). Significant differences were observed among ceramics and cleaning methods, with manual/ionic brushing causing the greatest changes (p < 0.05). IPS e.max had the highest Ra with manual brushing (0.745–0.789 µm), whereas Ceramill Zolid zirconia with ionic brushing showed the highest Ra values among the electric methods (0.745–0.757 µm). Conclusions: Manual brushing induced clinically unacceptable color changes in IPS e.max CAD, whereas ionic brushing adversely affected Ceramill Zolid zirconia. All brushing methods increased surface roughness beyond acceptable limits. Full article

This research has successfully addressed the technical challenge of generating nanobubbles in diesel fuel, which inherently lacks hydrophilic structures and charged ions, enabling the effective production of high-concentration nanobubble diesel fuel. This breakthrough lays a solid foundation for subsequent research into the combustion performance and combustion mechanism of high-concentration nanobubble fuels. Furthermore, it holds promising potential to advance high-concentration nanobubble fuel as a viable new type of energy source. A specialized device was designed to generate nanobubble-embedded diesel, and particle tracking analysis with n-hexadecane dilution was employed to quantify nanobubble concentration. The results demonstrate that the nanobubble concentration in diesel increases with both circulation time and pressure, reaching up to 5 × 10⁸ ± 3.1 × 10⁷ bubbles/mL under a pressure of 2.5 MPa. Stability tests indicate an initial rapid decay (50% reduction within one week), followed by a slower decline, which stabilizes at 4.5 × 10⁷ ± 3.13 × 10⁶ bubbles/mL after two months. Notably, nanobubble concentration has a minimal impact on the density and viscosity of diesel but slightly decreases its surface tension. This study presents a feasible method for preparing high-concentration nanobubble diesel, which lays a foundation for investigating the combustion mode and mechanism of nanobubble diesel fuel. With the goal of enhancing combustion efficiency and reducing pollutant emissions, this work further paves the way for the application of high-concentration nanobubble diesel as a new energy source in fields including automotive, marine, and aerospace industries. Full article

The study aims to promote environmental restoration by shedding light on the potential use of moringa waste as an inexpensive, eco-friendly adsorbent for treating wastewater contaminated with Chromium (VI). FTIR was used to characterise the surface functional groups of moringa waste. The one-factor-at-a-time method was used to study the initial concentration in milligrams per litre, contact time in minutes, temperature in degrees Celsius, pH, and adsorbent dosage in milligrams per litre. The output was the removal percentage. Furthermore, adsorption isotherms, kinetics, and thermodynamic models were applied to understand the process behaviour. FTIR examination revealed the moringa waste structure’s stability and aromaticity, confirmed by peaks located around 1596 cm⁻¹ and the stretching of the hydroxyl group around 3321 cm⁻¹, which are important for enhancing Cr (VI) adsorption due to their capability to establish strong bonds with metal ions. Aromatic rings contribute to a large surface area and porosity and are stable; this is important for adsorption applications. At 60 min of contact time with a pH of 6 and 0.5 g of adsorbent dosage at 45 °C for a concentration of 100 mg/L, the highest removal percentage was found to be 77.03%. Adsorption data values indicated a good fit to the Langmuir isotherm model. The thermodynamic study showed that the process is endothermic and spontaneous, hence making the application of moringa waste in wastewater treatment viable. Full article

This research explores the effect of a composite support of SiO₂ and Al₂O₃ with Fe and Co incorporated as catalysts for Fischer–Tropsch synthesis (FTS) using a 3D-printed stainless steel (SS) microchannel microreactor. Two mesoporous catalysts, FeCo/SiO₂Al₂O₃ and Co/SiO₂Al₂O₃, were synthesized via a one-pot (OP) method and extensively characterized using N₂ physisorption, XRD, SEM, TEM, H₂-TPR, TGA-DSC, FTIR, and XPS. H₂-TPR results revealed that the synthesis method significantly affected the reducibility of metal oxides, thereby influencing the formation of active FTS sites. SEM-EDS and TEM further revealed a well-defined hexagonal matrix with a porous surface morphology and uniform metal ion distribution. FTS reactions, carried out in the 200–350 °C temperature range at 20 bar with a H₂/CO molar ratio of 2:1, exhibited the highest activity for FeCo/SiO₂Al₂O₃, with up to 80% CO conversion. Long-term stability was evaluated by monitoring the catalyst performance for 30 h on stream at 320 °C under identical reaction conditions. The catalyst was initially active for the methanation reaction for up to 15 h, after which the selectivity for CH₄ declined. Correspondingly, the C₄⁺ selectivity increased after 15 h of time-on-stream, indicating a shift in the product distribution toward longer-chain hydrocarbons. This trend suggests that the catalyst undergoes gradual activation or restructuring under reaction conditions, which enhances chain growth over time. The increase in C₄⁺ products may be attributed to the stabilization of the active sites and suppression of methane or light hydrocarbon formation. Full article

A hierarchical photoanode composed of amorphous indium phosphate (InPO_x)-coated titanium dioxide nanowires (TiO₂ NWs) was successfully fabricated via a hydrothermal method followed by dip-coating and thermal phosphidation. Structural characterization revealed the formation of a uniform InPO_x shell on the surface of vertically aligned TiO₂ NWs, without altering their 1D morphology. X-ray photoelectron spectroscopy confirmed the incorporation of phosphate species and the presence of oxygen vacancies, which contribute to enhanced interfacial charge dynamics. Photoelectrochemical (PEC) measurements demonstrated that the InPO_x/TiO₂ NWs significantly improved photocurrent density, with the 0.1 M InCl₃-derived sample achieving 0.36 mA·cm⁻² at 1.0 V—an enhancement of approximately 928% over pristine TiO₂. This enhancement is attributed to improved charge separation and injection efficiency (91%), as well as reduced interfacial resistance verified by electrochemical impedance spectroscopy. Moreover, the Mott–Schottky analysis indicated a four-order increase in carrier density due to the InPO_x shell. The modified electrode also exhibited superior stability under continuous illumination for 3 h. These findings highlight the potential of amorphous InPO_x as an effective cocatalyst for constructing efficient and durable TiO₂-based photoanodes for solar-driven water-splitting applications. Full article

The development of biomaterials with tailored properties is indispensable for biomedical applications. In this study, amorphous silica/sodium alginate (SiO₂/SA) hybrids were synthesized via the sol–gel method by incorporating 2, 5, and 8% sodium alginate into the silica matrix. The hybrids were characterized to evaluate their structural, surface, thermal, moisture-responsive, and biological properties. FTIR and XRD analyses confirmed the formation of organic–inorganic networks and amorphous structures. BET measurements revealed a specific surface area of 325 m²/g for SiO₂/SA2%, decreasing with higher SA content to 104.3 m²/g for SiO₂/SA8%; the moisture sorption capacity followed a similar trend. Thermal analysis indicated improved stabilization of the polymer within the silica matrix. Cytotoxicity tests on HaCaT (human keratinocyte) cells line revealed moderate toxicity for the SiO₂/SA2% hybrid (~40% cell viability inhibition (CVI)), while increasing the SA content reduced cytotoxicity, with a CVI of 33% for SiO₂/SA5% and ~15% for SiO₂/SA8%, all within non-toxic ranges according to ISO standards. The SiO₂/SA5% hybrid demonstrated the best balance between functional properties and biocompatibility. These preliminary results suggest that further optimization with intermediate SA concentrations (e.g., 6–7%) could further reduce cytotoxicity while maintaining desirable properties, supporting the potential of silica/sodium alginate hybrids in future biomedical applications. Full article

Controlled thermal stratification in water is crucial for applications such as testing the thermal stealth of underwater vehicles and studying aquatic ecosystems. However, existing laboratory methods for generating such stratified environments often lack stability and uniformity. This study systematically investigates the influence of various hot water injection methods on the stability of thermal stratification. A computational fluid dynamics model, incorporating the overlapping dynamic mesh technique and the Volume of Fluid free-surface capturing method, was used to compare four generation strategies: single-side fixed discharge, towed horizontal discharge, towed vertical upward discharge, and multi-nozzle towed vertical upward discharge. The results indicate that towed discharge methods produce more stable and uniform thermal stratification compared to the fixed discharge method, achieving a 10.1% increase in the water body’s vertical stability coefficient and a 4.5% increase in the Richardson number, while the maximum surface temperature difference was significantly reduced from 0.98 K to 0.37 K. Among the towed methods, vertical upward discharge demonstrated superior stability over horizontal discharge, as it directly transports the high-temperature plume to the upper layer, minimizing thermal exchange with the lower layer, with its vertical stability coefficient and Richardson number being 17.9% and 23% higher, respectively. While maintaining a constant heat input per unit volume, the multi-nozzle configuration yielded ${\mathrm{N}}^2$ and Ri values comparable to the single-nozzle version, while further improving the temperature uniformity at the free surface. Consequently, the towed vertical upward discharge emerges as a highly efficient method for establishing stable and uniform thermal stratification, with the multi-nozzle configuration showing significant promise for large-scale applications. This study provides a valuable reference for creating stratified fluid environments and for related engineering fields. Full article

In order to study the influence of rock mechanical behavior under different saturation conditions on the stability of deep caverns, this paper establishes a mechanical model for bottom drum failure in deep chambers based on Pratt’s pressure arch theory and the upper bound theorem of limit analysis, comprehensively considering the effect of rock saturation. An analytical solution for the surrounding rock pressure under the nonlinear Hoek–Brown criterion is derived, and the optimal upper bound solution is obtained. The study systematically investigates the influence of rock saturation, geostress, and Hoek–Brown parameters (GSI, σ_c0, σ_c100, m_i, D) on the surrounding rock pressure and the characteristics of potential failure surfaces. The results indicate that the surrounding rock pressure exhibits two-stage variation with saturation degree (S_r): when S_r = 0~0.6, the surrounding rock pressure increases significantly, and the growth rate slows and tends to stabilize when S_r exceeds 0.6. Increases in ground stress field parameters (σ_v, λ) significantly raise the surrounding rock pressure and expand the potential failure zone. Among the Hoek–Brown parameters, increases in GSI, σ_c0, σ_c100, and m_i enhance the stability of the surrounding rock, while an increase in the disturbance factor D reduces its bearing capacity. The results of this paper can provide theoretical guidance for the stability evaluation of deep underground chambers. Full article