Search Results (23,994)

Mesozooplankton are pivotal for Black Sea food webs, yet they are highly vulnerable to hydrographic variability, eutrophication, and human pressures. This study analysed mesozooplankton dynamics along the Romanian coast (2013–2020) across three sectors (north, central, and south) and two distinct periods (cold and warm seasons), integrating Abundance–Biomass Comparison (ABC) curves with Fuzzy Cognitive Mapping (FCM). Results revealed a clear disturbance gradient: the Danube-influenced north supported high abundances of small-bodied taxa; the central sector maintained the most resilient and functionally diverse assemblages; and the southern sector showed chronic degradation with Noctiluca scintillans dominance. ABC curves quantified disturbance, with curve convergence in the north and near overlap in the south during summer, while FCM highlighted network simplification and reduced functional redundancy. Climate scenario simulations projected further declines in cladocerans and meroplankton under warming and freshening, whereas copepods showed relative resilience. Collectively, the findings demonstrate progressive simplification of mesozooplankton and declining energy transfer efficiency, underscoring the need to integrate zooplankton-based indicators into Black Sea monitoring and management frameworks. Full article

Background/Objectives: Immediate implant placement in the esthetic zone can shorten treatment time but maintaining peri-implant soft tissue stability is challenging. Conventional multi-stage workflows require multiple visits and may disturb peri-implant tissues. Placing a definitive one-time abutment at surgery can preserve soft tissue contours by avoiding multiple abutment changes. This case report introduces a digital one-stage approach delivering a definitive zirconia crown with delayed occlusal veneering at surgery to streamline treatment and preserve tissue stability. Methods: A 60-year-old male with a failing maxillary canine underwent immediate implant placement using guided surgery. A customized healing abutment preserved the emergence profile for the definitive restoration. A zirconia crown with an occlusal cut-back was fabricated and delivered at surgery on the one-time abutment without occlusal contact. After 12 weeks, a ceramic overlay was bonded extraorally to the crown to restore the occlusal surface. Results: At 2-year follow-up, the implant exhibited stable bone and healthy peri-implant soft tissues, with no complications. The one-time approach preserved tissue contours by eliminating provisional stages, and delayed occlusal veneering provided excellent esthetic integration. The patient was satisfied with the immediate result and fewer visits. This one-stage approach required fewer interventions than conventional provisional workflows. Conclusions: Immediate implant placement with a one-time abutment and delayed occlusal loading preserved peri-implant tissue architecture and achieved excellent functional and esthetic outcomes at 2 years. This one-stage workflow is a tissue-preserving alternative to multi-stage protocols; further studies are needed to confirm its long-term efficacy. Full article

Noticing the low efficiency caused by fluid flow retention phenomena and the high pressure loss in the shell-and-tube heat exchanger with common segmental baffle, an embedded louver shell-and-tube heat exchanger is designed, and numerical simulation of fluid heat transfer and flow characteristics of this novel heat exchanger is carried out. Results reflect that the structure with embedded louvers can significantly reduce the area of the flow retention zone and increase the fluid disturbance on the leeward side of the baffle, making the pressure drop of the shell side fluid 20.5–21.3% lower and the heat transfer coefficient 8.75–16.4% higher. At the shell side fluid inlet, outlet, and middle section of the heat exchanger, the average fluid temperatures are 0.34 °C, 2.12 °C, and 3.08 °C higher, respectively, compared to those in the common segmental baffle shell-and-tube heat exchanger. On this basis, the influence of the louver geometrical parameters, including louver angle and louver length, on the performance is also analyzed. The comprehensive evaluation factor is proposed and applied to evaluate the improvement of heat exchangers with different design parameters. The results showed that the evaluation factor is higher when the louver angle is 60°. However, when the louver length increases from 1/7 to 1/3 of the distance between adjacent baffles, the evaluation factor is almost unchanged. Full article

Mining activities are conducted to extract valuable minerals from the Earth, which are used to manufacture many objects. However, these operations generate landform alterations, such as deep excavations, artificial embankments, and landscape reshaping. In this study, landform changes were monitored in a mining area in Mazapil, Zacatecas, Mexico, using geomatic techniques. Multitemporal Landsat satellite images and digital elevation models (DEMs) from different years were used to detect and quantify landform alterations and estimate the volumes of removed material. The results show ground depressions greater than −333 m and waste material accumulations greater than +152 m, with an average standard deviation of ±3.6 m. A total excavation volume of 413.524 million m³ and a total fill volume of 431.194 million m³ were quantified, with an estimated standard deviation of ±810 m³. The proposed methodology proved effective for the remote quantification of large-scale relief disturbances in open-pit mining areas. It can also be used for environmental monitoring and hydrological risk assessment in active and inactive mining areas. Full article

The simultaneous sintering of chips with different specifications generates differential auxiliary sintering pressures, which create eccentric loads on the substrate. These loads disrupt the horizontal alignment of the chip-loading mold and adversely affect sintering quality. To overcome the challenge, an electro-hydraulic servo leveling system featuring active moment compensation is developed, incorporating high-precision pressure control to counteract the influence of eccentric loading. The system design is guided by static analysis to identify the eccentric load distribution, resulting in an optimized mechanical configuration. A feedforward-based Nussbaum gain backstepping adaptive controller is proposed to compensate for multiple nonlinear disturbances, including time-varying hydraulic parameters and external loads, while a feedforward strategy is integrated to improve the dynamic response of the pressure control loop. The effectiveness of the moment compensation leveling system and control algorithm has been validated through simulations and physical experiments on silver sintering equipment. The results show that the baseline deviation of the lower mold platform is reduced by 95%, achieving micron-level precision (≤5 μm). The proposed control algorithm reduces the dynamic tracking error by 42.4% and the steady-state fluctuation error by 50.6%. The introduction of the moment compensation leveling system to the existing silver sintering equipment addresses the issue of chip fracture caused by eccentric loading. The shear strength of the sintered layer is increased by 40.6%, and the thickness uniformity is improved by 65.8%. This study contributes to improved packaging quality and efficiency for power semiconductors, providing a theoretical basis for the development of advanced sintering equipment. Full article

In agricultural production, numerous nonlinear, time-lagged, and continuously disturbed deterministic processes require effective regulation. This study proposed a window AI control method driven by mechanism and data, which was studied and applied in continuous grain drying process based on the concepts of micro-environment absolute water potential and water potential accumulation. A control system for continuous grain drying was established based on absolute water potential accumulation, and three sets of experiments were conducted: constant temperature drying (water potential accumulation control window, hot air temperatures of three drying sections: 40 °C, 40 °C, 40 °C; relative humidity: 35–40%), increasing temperature drying (water potential accumulation control window, hot air temperatures of three drying sections: 35 °C, 40 °C, 45 °C; relative humidity: 35–40%), and a control experiment (equivalent accumulated temperature control window, hot air temperatures of three drying sections: 40 °C, 40 °C, 40 °C; relative humidity: 35–40%). The results showed that the outlet moisture content ranged from 15.08% to 15.86%, 15.30% to 15.91%, and 15.10% to 15.95%, respectively. The outlet moisture control accuracy ranged from −0.42% to 0.36%, −0.2% to 0.41%, and −0.4% to 0.45%, respectively. Analysis of grain quality indicators (damage percentage, germination percentage, fatty acid value) and microscopic structure revealed the following order: increasing temperature drying > constant temperature drying > control experiment. Compared with the control experiment adopting the equivalent accumulated temperature window control method, the proposed method exhibited higher control accuracy and stability. By integrating coupled temperature and humidity parameters into the variables, the quality of dried grains was effectively guaranteed. Full article

This study establishes a dynamic evolution model of the physical and mechanical properties of lunar simulant as a function of sampling-induced disturbance on the lunar surface, aiming to eliminate design errors in sampling missions caused by neglecting the disturbance of lunar soil. A standard probe was inserted into the lunar soil simulant both before and after disturbance, and the variation in penetration resistance at the exact location was proposed as an indicator of the regolith’s disturbance state. Compression tests and disturbance tests were conducted on CUG-1A lunar soil simulant, with the experimental results subjected to regression analysis and neural network prediction. Based on the compression tests, a regression equation was derived relating the slope of the probe penetration resistance to the internal friction angle and density of the lunar soil simulant, showing a strong correlation between predicted and actual values. The disturbance tests provided penetration resistance curves under various disturbance conditions. By integrating these two components, a correspondence was established between the disturbance conditions and the internal friction angle and density of the lunar soil simulant. The predictive performance of three typical neural network algorithms—LM, BR, and SCG—with varying numbers of neurons was compared. The LM algorithm with 10 neurons was selected for its superior performance. Ultimately, a sampling disturbance model was developed to predict the internal friction angle and density of the lunar soil simulant based on disturbance conditions, demonstrating an extremely high correlation between predicted and actual values. Full article

Quadrotor UAVs require robust control methods to handle complex dynamics, model uncertainties, and external disturbances during trajectory tracking. This paper presents a trajectory tracking control method combining Sliding Mode Control with an Improved Extended State Observer (SMC-IESO). The control system uses a hierarchical structure with position and attitude control loops, employing a third-order Extended State Observer to estimate disturbances in real-time. The improved sliding mode control law incorporates observation error compensation to reduce the required sliding mode gain. Lyapunov stability analysis proves the asymptotic convergence of tracking errors. Simulation results demonstrate that SMC-IESO achieves better tracking accuracy and disturbance rejection than conventional sliding mode control, while significantly reducing control signal chattering, making it more suitable for practical quadrotor applications. Full article

Background: Sport-related concussion is common in rugby union, yet female players remain underrepresented in research. This study examined seasonal changes in cerebral oxygenation, cardiac function, and concussion symptomology in adult female rugby players, and explored acute physiological responses following a single documented concussion. Methods: A total of 29 adult females (19 amateur rugby, 10 control) completed pre-, mid-, and end-season assessments. Measures included functional near-infrared spectroscopy (fNIRS) of the pre-frontal cortex, seismocardiography (SCG)-derived cardiac timing indices, and Sport Concussion Assessment Tool 6 (SCAT6). Group and time effects were analysed using general linear models and statistical parametric mapping. Typical error (TE) and its 90% confidence intervals (90% CI) were used to determine meaningful changes post-concussion. Results: Rugby players reported more SCAT6 symptoms (number: p = 0.006, η²_p = 0.23; severity: p = 0.020, η²_p = 0.17). They also had shorter systolic time (p = 0.002, η²_p = 0.19) and higher twist force values (p = 0.014, η²_p= 0.21) than controls. fNIRS revealed higher right-hemisphere oxyhaemoglobin (ΔO₂Hb) responses for both tasks (ps < 0.001, η²_p = 0.77 and η²_p = 0.80) and lower activation in specific prefrontal channels. No seasonal changes occurred in global oxygenation or frequency band activity. In the exploratory single-concussion case, symptomology, SCG twist force, ΔO₂Hb, and cardiac band power exceeded TE and its 90% CI at 5 days post-injury. Conclusions: The multimodal approach detected stable group-level physiology alongside localised cortical and cardiac differences, and acute changes following concussion. While these results highlight the potential of combined fNIRS and SCG measures to capture physiological disturbances, the small sample size and single-concussion case necessitate cautious interpretation. Further validation in larger, longitudinal cohorts is required before any biomarker utility can be inferred. Full article

Rivomarginella morrisoni is a freshwater snail endemic to Thailand, yet its behavioral ecology remains poorly understood. This study described the feeding behavior of R. morrisoni, focusing on its foraging activity, behavioral patterns, and food detection mechanisms under laboratory conditions using specimens collected from four river basins in central Thailand. Daily monitoring revealed nocturnal emergence, peaking between 21:00 and 22:00 h, with stable rhythms established 72 h post-feeding. Feeding trials revealed a preference for aged shrimp over fresh or decayed ones. Behavioral observations confirmed that food localization in R. morrisoni was mediated by chemical cues. Light–dark tests indicated a slight tendency toward darkness, but no significant phototactic response was observed. These findings suggest that R. morrisoni is a generalist scavenger with chemosensory-driven foraging and nocturnal activity. Its apparent sensitivity to habitat disturbance underscores the relevance of behavioral studies for informing future conservation and captive breeding efforts. Full article

DC distribution networks exhibit inherent symmetry in their balanced power distribution and modular structure, offering high operational flexibility and making them particularly suitable for the integration of distributed generation and modern loads. This symmetric framework positions DC networks as a vital component of new power systems and a key development direction for future power supply systems in industrial and mining enterprises. However, pole-to-pole short-circuit faults disrupt this symmetry, characterized by low system damping, high fault currents, and extremely rapid current rise rates, which pose serious threats to system security and necessitate ultra-fast fault clearance. To address this issue, this paper proposes a novel pilot protection scheme inspired by symmetry principles, based on the slope of the line-mode current for pole-to-pole short-circuit faults in DC distribution networks. First, an equivalent circuit of the system before converter blocking under a pole-to-pole fault is established, and an analytical expression of the fault current is derived, incorporating symmetric analysis of modal components. Subsequently, the variation trends, amplitudes, and phase characteristics of the fault current under faults occurring in different zones of the DC line are analyzed from the perspective of modal symmetry, highlighting the symmetric and asymmetric behaviors of line-mode and zero-mode currents. Furthermore, considering the distinct symmetric properties of these currents during lightning disturbances and pole-to-pole faults, the least squares method is employed to perform linear fitting on the line-mode current, thereby capturing its symmetric variation trend. A pilot protection scheme utilizing the slope of the line-mode current is then proposed, leveraging symmetry in fault discrimination. Finally, simulation models built in MATLAB/Simulink (R2022a) are used for validation. The results demonstrate that the proposed protection method can quickly identify faults within 1.5 ms while exhibiting strong tolerance to a 20 Ω transitional resistance and 50 dB signal noise, indicating good feasibility and broad applicability, with symmetry-based analysis enhancing robustness. Full article

This paper studies spacecraft control under communication congestion, multi-source uncertainties, and input constraints. To reduce communication load, a static event-triggered mechanism is used so that transmissions occur only when necessary. Unknown nonlinearities are estimated online by a radial basis function neural network (RBFNN). To address sensor outliers and external disturbances, an event-triggered stubborn composite disturbance observer (ESCDO) is proposed, and sufficient conditions are derived to ensure its globally uniformly bounded stability. Based on this, an MPC-based composite anti-disturbance controller is designed to satisfy input constraints, and conditions are provided to guarantee the uniform bounded stability of the closed loop. Numerical simulations are conducted to demonstrate the effectiveness of the proposed approach. Full article

Cooperative path planning is recognized as a critical technology for Autonomous Underwater Vehicle (AUV) clusters to execute complex marine operations. Through multi-AUV cooperative decision-making, perception limitations of individual robots can be mitigated, thereby significantly enhancing the efficiency of tasks such as deep-sea resource exploration and submarine infrastructure maintenance. However, the underwater environment is characterized by severe disturbances and limited communication, making cooperative path planning for AUV clusters particularly challenging. Currently, this field is still in its early research stage, and there exists an urgent need for the integration of scattered technical achievements to provide theoretical references and directional guidance for relevant researchers. Based on representative studies published in recent years, this paper provides a review of the research progress in three major technical domains: heuristic optimization, reinforcement and deep learning, and graph neural networks integrated with distributed control. The advantages and limitations of different technical approaches are elucidated. In addition to cooperative path planning algorithms, the evolutionary logic and applicable scenarios of each technical school are analyzed. Furthermore, the lack of realism in algorithm training environments has been recognized as a major bottleneck in cooperative path planning for AUV clusters, which significantly limits the transferability of algorithms from simulation-based validation to real-sea applications. This paper aims to comprehensively outline the current research status and development context of the field of AUV cluster cooperative path planning and propose potential future research directions. Full article

Sarcodon aspratus fruiting polysaccharides (SAFP) exhibit multiple therapeutic properties. In this study, a type 2 diabetes mellitus (T2DM) mouse model was established using a high-fat diet (HFD) and streptozotocin to evaluate the antidiabetic potential of SAFP. Then the benefits of SAFP on glucolipid metabolism, gut barrier integrity and intestinal microbiota were evaluated. The results indicated that SAFP alleviated disturbances in glycolipid metabolism and insulin resistance through activating Adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK) signaling pathway. Furthermore, SAFP ameliorated hepatic inflammation and hepatic steatosis, as well as restored dysbiosis in hepatic function. Notably, SAFP enhanced intestinal mucosal architecture and strengthened epithelial barrier functionality through upregulated expression of tight junction components such as Zonula occludens-1(ZO-1), Claudin-1, and Occludin proteins. The 16S rRNA analysis indicated that SAFP has the potential to restore the intestinal microbial barrier in T2DM mice through elevation of short-chain fatty acids (SCFAs) concentrations and regulation of microbial community imbalances. This research offers foundational evidence supporting the utilization of SAFP as an innovative dietary supplement or prospective prebiotic component in functional food formulations targeting diabetes management. Full article

Background: High-throughput metabolomics studies have promoted the discovery of candidate biomarkers linked to atherosclerosis (AS). This narrative systematic review summarises metabolomics studies conducted in (1) individuals with subclinical AS (assessed by imaging techniques such as carotid intimal media thickness, IMT, and coronary artery calcium, CAC), (2) patients with established atherosclerotic plaques, and (3) individuals with AS risk factors. Methods: The systematic search was conducted in the PubMed database according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. The inclusion criteria were as follows: (i) publication date between 2009 and 2024; (ii) identification of potential biomarkers for AS in subjects with a diagnosis of AS or with one or more traits characteristic of the disease (i.e., CAC or IMT); (iii) identification of potential AS biomarkers in subjects with atherogenic clinical conditions (i.e., Down’s syndrome, DS, polycystic ovarian syndrome, PCOS, and systemic lupus erythematosus, SLE); (iv) metabolomic studies; and (iv) studies in human samples. Exclusion criteria comprised the following: (i) studies on lipid metabolic diseases unrelated to AS, (ii) “omics” results not derived from metabolomics, (iii) reviews and studies in animal models or cell cultures, and (iv) systematic reviews and meta-analyses. Of 90 eligible studies screened, 24 met the inclusion criteria. Results: Across subclinical and overt AS, consistent disturbances were observed in amino acid, lipid, and carbohydrate metabolism. Altered profiles included branched-chain amino acids (BCAAs), aromatic amino acids (AACs) and derivatives (e.g., kynurenine–tryptophan pathway), bile acids (BAs), androgenic steroids, short-chain fatty acids (FAs)/ketone intermediates (e.g., acetate, 3-hydroxybutyrate, 3-HB), and Krebs cycle intermediates (e.g., citrate). Several metabolites (e.g., glutamine, lactate, 3-HB, phosphatidylcholines, PCs/lysophosphatidylcholines, lyso-PCs) showed reproducible associations with vascular phenotypes (IMT/CAC) and/or clinical AS. Conclusions: The identification of low-weight metabolites altered in both subclinical and overt AS suggests their potential as candidate biomarkers for early AS diagnosis. Given the steady increase in deaths from cardiovascular disease, a manifestation of advanced AS, this finding could have significant clinical relevance. Full article