Search Results (17,632)

Using bidirectional fluid–structure interaction technology, the dorsal–ventral motion of the dolphin tail fin was simulated, and the feasibility of the numerical simulation method was validated through underwater motion experiments. This study investigated the effects of structural parameters and motion modes of bionic dolphin tail fins on their propulsion performance. The results show that flexible tail fins can enhance propulsion performance. Compared to equal-thickness flexible tail fins, variable-thickness flexible tail fins that conform to the structural characteristics of real dolphin tail fins exhibit better propulsion performance. Asymmetric motion modes have a certain thrust-enhancing effect, but altering the frequency ratio $F$ and amplitude ratio $H$ of heaving motion leads to an increase in pitching moment, reducing swimming stability. Additionally, the greater the difference in frequency and amplitude between the up-and-down motions, the larger the pitching moment. The study results provide references for the optimized design and motion control of bionic tail fins. Full article

In the domain of fire-resistant steels, the characteristics of precipitates significantly influence material properties. This study developed a novel heat treatment protocol to concurrently achieve both interphase precipitation and random precipitation. Samples were subjected to isothermal treatments at various temperatures and durations, while techniques such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to thoroughly analyze the coarsening behavior of the two types of precipitate and reveal their thermal stability differences. The results show that the growth and coarsening rates of interphase precipitates are substantially lower than random precipitates. Coarsening kinetics analysis reveals that the radius of random precipitates follows a 1/3 power law with time at 600 °C and 650 °C, whereas the radius of interphase precipitates adheres to a 1/6 power law at 600 °C and a 1/5 power law at 650 °C. Furthermore, interphase precipitation demonstrates excellent size uniformity, which hinders the formation of a concentration gradient, thereby reducing the coarsening rate and enhancing thermal stability. After prolonged tempering treatment, interphase precipitation maintains a higher strengthening contribution than random precipitation. This study provides novel insights and theoretical foundations for the design and development of fire-resistant steels. Full article

Shale gas, as an important component of unconventional energy, holds enormous potential value in the energy sector. However, due to the complex geological characteristics and fluid flow mechanisms of shale gas reservoirs, its exploitation faces numerous challenges. This study focuses on the optimization of intermittent production methods for shale gas wells in the Changning block. In this study, a dynamic coordination model of formation recharge and wellhead output was established using real-time pressure monitoring and historical production records as key inputs. Based on this, the dimensionless production efficiency index was optimized by finely regulating the switching timing of the wellhead, thus significantly enhancing the cumulative oil production of the well. The conclusions indicate that the optimization methods proposed in this study can effectively guide the production operations of shale gas wells in the Changning block, thereby enhancing production yield and stability. This research contributes practical value to the field by offering theoretical support and practical guidance for shale gas exploitation, addressing technical challenges in the process. Full article

As a weak part of the concrete tower in wind turbines, the insufficient shear capacity of vertical joints can cause the local shear failure of the tower, reduce the overall bearing capacity and stability of the tower, and lead to safety issues. At present, the splicing of tower vertical joints mainly uses epoxy resin filling and arc bolt connections. However, sometimes the concrete near the vertical joints is damaged due to compression after applying pretension to the arc bolts, which will affect the bearing capacity and stability of the entire tower structure. If other interface processes are used for vertical joint splicing, the shear performance will be directly affected. Therefore, in order to study the influence of different interface processes on the shear performance of vertical joints in concrete tower tubes, four vertical joint specimens were designed for a pull-out test under shear load and the failure mode of the specimens and the shear capacity of the vertical joint interface were analyzed and studied. The results showed that with an increase in epoxy thickness and the application of an interface chiseling treatment, as well as injecting epoxy resin into the channels, the shear performance of vertical joints could be enhanced. Finally, based on existing research and standardized design methods, the shear capacity of vertical joints in wind turbine concrete towers was predicted, which showed that the existing design methods were not yet fully applicable to the shear capacity design of vertical joints in wind turbine concrete towers with different interface processes. Further research is needed to supplement and improve them. Full article

Oleogels have been a revolutionary innovation in food science in terms of their health benefits and unique structural properties. They provide a healthier alternative to traditional solid or animal fats. They have improved oxidative stability and nutritional value to maintain the desirable sensory qualities of lipid-based foods. Moreover, oleogels offer an ideal carrier for poorly water-soluble bioactive compounds. The three-dimensional structure of oleogels can protect and deliver bioactive compounds in functional food products. Bioactive compounds also affect the crystalline behavior of oleogelators, the physical properties of oleogels, and storage stability. Generally, different incorporation techniques are applied to entrap bioactive compounds in the oleogel matrix depending on their characteristics. These approaches enhance the bioavailability, controlled release, stability of bioactive compounds, and the shelf life of oleogels. The multifunctionality of oleogels extends their applications beyond fat replacements, e.g., food preservation, nutraceutical delivery, and even novel innovations like 3D food printing. Despite their potential, challenges such as large-scale production, cost efficiency, and consumer acceptance remain areas for further exploration. This review emphasizes the understanding of the relationship between the structure of oleogels and their functional properties to optimize their design in different food applications. It also highlights the latest advancements in bioactive oleogels, focusing on how they incorporate bioactive compounds such as polyphenols, essential oils, and flavonoids into oleogels. The impact of these compounds on the gelation process, storage stability, and overall functionality of oleogels is also critically examined. Full article

Salt caverns are recognized as an excellent medium for energy storage. However, due to the unique characteristics of China’s bedded salt formations, which contain numerous salt layers and a high concentration of insoluble impurities, significant accumulation at the bottom of salt caverns occurs, leading to the formation of extensive sediment voids. These sediment voids offer a potential space for underground oil storage, referred to as sediment void oil storage (SVOS). Oil recovery process from these sediment voids is a critical process. This paper summarizes the oil recovery technologies for SVOS and identifies four key factors—geological evaluation, stability evaluation, tightness evaluation, and oil storage capacity—all of which influence enhance oil recovery from sediment voids. This paper also outlines the overall oil recovery process, presents oil recovery experiments, and discusses oil recovery methods for enhancing oil recovery from sediment void. Additionally, it addresses the challenges of oil recovery in SVOS and explores its potential advantages and applications. The findings suggest that salt cavern sediment voids, as a promising storage space, provide a new approach to realize oil recovery and can overcome the limitations associated with cavern construction in high-impurity salt mines. The oil recovery from the sediment void is feasible, and China has rich rock salt and other convenient conditions to develop SVOS technology. Full article

Aeromagnetic surveying technology detects minute variations in Earth’s magnetic field and is essential for geological studies, environmental monitoring, and resource exploration. Compared to conventional methods, residence time difference (RTD) fluxgate sensors deployed on unmanned aerial vehicles (UAVs) offer increased flexibility in complex terrains. However, measurement accuracy and reliability are adversely affected by environmental and sensor noise, including Barkhausen noise. Therefore, we proposed a novel denoising method that integrates Particle Swarm Optimization (PSO) with Wavelet Neural Networks, enhanced by a dynamic compression factor and an adaptive adjustment strategy. This approach leverages PSO to fine-tune the Wavelet Neural Network parameters in real time, significantly improving denoising performance and computational efficiency. Experimental results indicate that, compared to conventional wavelet transform methods, this approach reduces time difference fluctuation by 23.26%, enhances the signal-to-noise ratio (SNR) by 0.46%, and improves sensor precision and stability. This novel approach to processing RTD fluxgate sensor signals not only strengthens noise suppression and measurement accuracy but also holds significant potential for improving UAV-based geological surveying and environmental monitoring in challenging terrains. Full article

This study explores for the first time the impact of a 6-day germination process on the structure (FTIR), antioxidant activity, nutritional/safety attributes (ACE-I inhibitory activity, digestibility, and cytotoxicity), and functional properties of fractions of variable molecular weight (W > 5 kDa; 3 kDa < MW < 5 kDa; and MW < 3 kDa) isolated from proteins extracted from lentils. FTIR results indicated a substantial increase in β-sheet contents during germination. The digestibility of proteins increased from day 0 (16.32–17.04%) to day 6 of germination (24.92–26.05%) with variable levels of digestibility depending on their MW. ACE-I inhibitory activity improved during germination in all fractions, reaching IC₅₀ values of 0.95, 0.83, and 0.69 mg/mL after 6 days of germination. All antioxidant activities analyzed notably increased, particularly in low-MW fractions (MW < 3 kDa). The functional properties of low-MW fractions were also the most promising, displaying the highest water and fat binding capacities and emulsifying and foaming capacities but lower foaming and emulsifying stability compared to high-MW fractions. Cytotoxicity tests on L929 cells revealed the slight adverse effects of low-MW fractions during germination. This study provides insights into the enhanced nutritional and functional attributes of lentil proteins following germination, emphasizing their potential application in functional foods. Full article

To effectively solve the problem of land sanding and improve the water- and element-retaining properties of sandy soil, a thermal-activated coal gangue (TACG) was used as an ameliorating material to prepare a composite soil mixed with sandy soil to enhance the water-retaining and fertilizer-fixing properties of the sandy soil and reduce the evaporation of water in the soil. The structure and thermal stability of the gangue were characterized using Fourier transform infrared spectroscopy and thermogravimetric analysis. By applying different dosages and different calcination temperatures of the TACG, the water-holding capacity of the mixed soil was determined, and changes in pore structure were observed. When the dosage was 15% and the calcination temperature was 600 °C, the mixed soil possessed the most excellent distribution of pore structure and could effectively prevent water evaporation. Meanwhile, the application of the TACG in sandy soil improved its adsorption of K⁺, which showed the potential application of thermally activated gangue materials in the field of soil improvement. Full article

The spatiotemporal variability of precipitation profoundly influences terrestrial carbon fluxes, driving shifts between carbon source and sink dynamics through gross primary productivity (GPP) and ecosystem respiration (ER). As a result, the sensitivities of GPP and ER to precipitation (S_GPP and S_ER), along with their differential responses, are pivotal for understanding ecosystem reactions to precipitation changes and predicting future ecosystem functions. However, comprehensive evaluations of the spatiotemporal variability and differences in S_GPP and S_ER remain notably scarce. In this study, we utilized eddy covariance flux data to investigate the spatial patterns, temporal dynamics, and differences in S_GPP and S_ER. Spatially, S_GPP and S_ER were generally strongly correlated. Among different ecosystems, the correlation between S_GPP and S_ER was lowest in mixed forest and highest in broadleaf and needleleaf forest. Within the same ecosystem, S_GPP and S_ER exhibited considerable variation but showed no significant differences. In contrast, they differed significantly across ecosystems, with pronounced variability in their magnitudes. For example, shrubland exhibited the highest values for S_GPP, whereas needleleaf forest showed the highest values for S_ER. Temporally, S_ER demonstrated more pronounced changes than S_GPP. Different ecosystems displayed distinct trends: shrubland exhibited an upward trend for both metrics, while grassland showed a downward trend in both S_GPP and S_ER. Forest, on the other hand, maintained stable S_GPP but displayed a downward trend in S_ER. Additionally, S_GPP and S_ER exhibited a notable non-linear response to changes in the aridity index (AI), with both showing a rapid decline followed by stabilization. However, S_ER demonstrated a wider adaptive range to precipitation changes. Generally, this research enhances our understanding of the spatiotemporal variations in ecosystem carbon fluxes under changing precipitation patterns. Full article

This paper focuses on the modeling, control, and simulation of an over-actuated htr. This configuration implies that two of the six actuators are independently tilted using servomotors, which provide high maneuverability and reliability. This approach is predicted to maintain zero pitch throughout the trajectory and is expected to improve the aircraft’s steering accuracy. This arrangement is particularly beneficial for pa applications where accurate monitoring and management of crops are critical. The enhanced maneuverability allows for precise navigation in complex vineyard environments, enabling the uav to perform tasks such as aerial imaging and crop health monitoring. The employed control architecture consists of cascaded p-pid controllers using the slc method on the five controlled dof. Simulated results using Gazebo demonstrate that the htr achieves stability and maneuverability throughout the flight path, significantly improving precision agriculture practices. Furthermore, a comparison of the htr with a traditional hexacopter validates the proposed approach. Full article

Background/Objectives: Conventional live oral poliovirus vaccines (OPVs) effectively prevent poliomyelitis. These vaccines are derived from three attenuated Sabin strains of poliovirus, which can revert within the first week of replication to a neurovirulent phenotype, leading to sporadic cases of vaccine-associated paralytic poliomyelitis (VAPP) among vaccinees and their contacts. A novel OPV2 vaccine (nOPV2) with enhanced genetic stability was developed recently; type 1 and type 3 nOPV strains were engineered using the nOPV2 genome as a backbone by replacing the capsid precursor polyprotein (P1) with that of Sabin strains type 1 and type 3, respectively. The nOPV vaccines have a high degree of sequence homology with the parental Sabin 2 genome, and some manufacturing facilities produce and store both Sabin OPV and nOPV. Therefore, detecting Sabin virus contaminations in nOPV lots is crucial. Methods: This study describes the development of pan quantitative reverse transcription polymerase chain reaction (panRT-PCR) and multiplex one-step RT-PCR (mosRT-PCR) assays for the straightforward detection and identification of contaminating Sabin viruses when present in significantly higher amounts of nOPV strains. Results: The two assays exhibit high specificity, reproducibility, and sensitivity to detect 0.0001% and 0.00001% of Sabin viruses in nOPV, respectively. Additionally, an analysis of 12 trivalent nOPV formulation lots using both methods confirmed that the nOPV lots were free from Sabin virus contamination. Conclusions: The results demonstrated that the RT-PCR assays are sensitive and specific. These assays are relevant for quality control and lot release of nOPV vaccines. Full article

Fibroin, a protein extracted from silk, offers advantageous properties such as non-immunogenicity, biocompatibility, and ease of surface modification, which have been widely utilized for a variety of biomedical applications. However, in vivo studies have revealed critical challenges, including rapid enzymatic degradation and limited stability. To widen the scope of this natural biomacromolecule, the grafting of polymers onto the protein surface has been advanced as a platform to enhance protein stability and develop smart conjugates. This review article brings into focus applications of fibroin-hybrid systems prepared using chemical modification of the protein with polymers and inorganic compounds. A selection of recent preclinical evaluations of these hybrids is included to highlight the significance of this approach. Full article

High-entropy alloys, since their development, have demonstrated great potential for applications in extreme temperatures. This article reviews recent progress in their mechanical performance, microstructural evolution, and deformation mechanisms at low and high temperatures. Under low-temperature conditions, the focus is on alloys with face-centered cubic, body-centered cubic, and multi-phase structures. Special attention is given to their strength, toughness, strain-hardening capacity, and plastic-toughening mechanisms in cold environments. The key roles of lattice distortion, nanoscale twin formation, and deformation-induced martensitic transformation in enhancing low-temperature performance are highlighted. Dynamic mechanical behavior, microstructural evolution, and deformation characteristics at various strain rates under cold conditions are also summarized. Research progress on transition metal-based and refractory high-entropy alloys is reviewed for high-temperature environments, emphasizing their thermal stability, oxidation resistance, and frictional properties. The discussion reveals the importance of precipitation strengthening and multi-phase microstructure design in improving high-temperature strength and elasticity. Advanced fabrication methods, including additive manufacturing and high-pressure torsion, are examined to optimize microstructures and improve service performance. Finally, this review suggests that future research should focus on understanding low-temperature toughening mechanisms and enhancing high-temperature creep resistance. Further work on cost-effective alloy design, dynamic mechanical behavior exploration, and innovative fabrication methods will be essential. These efforts will help meet engineering demands in extreme environments. Full article

This paper presents the application of a proposed hybrid control strategy that is designed to enhance the performance and robustness of a grid-connected wind energy conversion system (WECS) using a Five-Phase Permanent Magnet Synchronous Generator (FP-PMSG). The proposed approach combines the second-order terminal sliding mode control technique (SO-STA) with the super-twisting algorithm (STA), with the main goal of benefitting from both their advantages while addressing their limitations. Indeed, the sole application of the SO-STA ensures rapid convergence and robust performances in nonlinear systems, but it leads to chattering and reduces the whole system’s efficiency. Therefore, by incorporating the STA, the obtained hybrid control can mitigate this issue by ensuring smoother control actions and a superior dynamic response. This designed hybrid control strategy improves the adaptability of the control system to wind fluctuations and enhances the system’s robustness against external disturbances and uncertainties, leading to higher reliability and efficiency in the wind energy conversion system. Furthermore, the proposed hybrid control allows optimizing the power extraction and boosting the WECS’s efficiency. It is worth clarifying that, besides this proposed control, a sliding mode controller is used for the grid side converter (GSC) and DC link voltage to ensure stable power transfer to the grid. The obtained simulation results demonstrate the effectiveness of the proposed strategy in improving the stability, robustness, and efficiency of the studied WECS under dynamic conditions, creating a promising solution for control in renewable energy systems operating under severe conditions. Full article