Search Results (3,339)

The article is devoted to the synthesis, implementation, simulation and experimental study of a real-time Lyapunov-based two-degree-of-freedom model reference adaptive controller (MRAC) for an axial-piston pump. The controller of the developed real-time system determinates control signal values applied to the electro-hydraulic proportional valve. The proportional valve is an actuator for driving the swash plate swivel angle of the pump. The swash plate swivel angle determines the displacement volume of the flow rate of the pump. The MRAC is synthesized based on the experimentally identified mathematical model. To conduct the identification and experimental investigation of the controller, the authors have used an existing laboratory test setup. The comparison of the designed MRAC with conventional PI controller is performed. The control performance analysis is based on integral square error (ISE) in transient responses of the pump flow rate at different flow rate references and loads. Full article

An effective understanding of sediment deposition and erosion in river basins, particularly floodplains, is critical for modeling geomorphic evolution, managing flood risks, and maintaining ecological integrity. However, most related studies have been limited to hydraulic or hydrodynamic modeling approaches. Therefore, this study integrated Sentinel-1 differential interferometric synthetic aperture radar (DInSAR) coherence, Sentinel-2 normalized difference vegetation index, and soil surface moisture index data with one-dimensional hydraulic modeling to assess flood-induced sediment deposition and erosion in the Gamcheon River basin under non-flood, short flood, and long flood scenarios. The DInSAR deformation analysis revealed a clear pattern of upstream erosion and downstream deposition during flood events, indicating a total depositional uplift of 0.33 m during the long flood scenario but dominant erosion with a total measured surface lowering of −2.03 m during the non-flood scenario. These results were highly consistent with the predictions from the hydraulic model and supported by the hysteresis curves for in situ suspended sediment concentration. The findings of this study demonstrate the effectiveness of the proposed integrated approach for quantifying floodplain sediment dynamics, offering particular application value in data-scarce or inaccessible floodplains. Furthermore, the proposed approach provides practical insights into sediment management, flood risk assessment, and ecosystem restoration efforts. Full article

As a fundamental element in industrial fluid transportation, the main pump fulfills an irreplaceable function in critical infrastructure, including the energy, water conservancy, petrochemical, and sewage treatment industries. As the core component of key power equipment, its operating condition is intrinsically connected to the safety, stability, and reliability of the entire system. This paper provides a systematic review of the latest advances in fault mechanism analysis and diagnosis methods for main pump systems. First, the typical structural composition and functional characteristics of the main pump system are examined, and the occurrence mechanisms and evolution rules of typical faults, such as mechanical malfunctions and performance degradation caused by hydraulic imbalance, are discussed in detail. Second, the main technical approaches to fault diagnosis are summarized and reviewed, including diagnosis methods based on signal processing, modeling, data-driven techniques, and multi-source information fusion. The advantages, limitations, and application scopes of these approaches are comparatively analyzed. On this basis, the development trends in main pump fault diagnosis technology and the key challenges faced—such as strong noise, small sample size, and multiple fault coupling—are identified and discussed. Finally, future research prospects are put forward in view of the limitations of current research. This review aims to provide theoretical insights and technical support for advancing condition monitoring, fault diagnosis, and health management of main pump systems. Full article

A high-load partial nitrification reactor (HLPNR) was operated to treat high-ammonia wastewater by varying the hydraulic retention time (HRT). The associated shifts in the microbial community were analyzed using PCR-DGGE and high-throughput sequencing. The results indicated that the reactor achieved a maximum nitrogen loading rate (NLR) of 10.14 kg·N/(m³·d) at an HRT of 1.5 h, with a nitrite accumulation rate (NAR) of 86%. PCR-DGGE analysis revealed Proteobacteria and Nitrosomonas as the dominant phylum and genus, respectively, whose relative abundances varied significantly with HRT. Specifically, the relative abundance of Nitrosomonas sp. G1 increased from 15% to 40%, indicating that the abundances of Proteobacteria and Nitrosomonas were directly related to the load of the HLPNR. High-throughput sequencing revealed a marked decline in both the diversity and abundance of the HLPNR’s microbial community under conditions of reducing load. The dominant genus changed; however, the stability of the HLPNR was not destroyed. It can be inferred that the stability of the HLPNR primarily depended on the enrichment of key functional bacteria rather than on the overall microbial community composition. Full article

To elaborate on the effects of hydraulic projects and physicochemical factors on the spatiotemporal distribution of phytoplankton communities, we monitored the phytoplankton communities and related water parameters in the Ganjiang River’s main channel over a five-year period. The survey revealed 65 species across six phyla, with Chlorophyta, Cyanophyta and Bacillariophyta as the most diverse groups. Phytoplankton abundance and biomass exhibited significant seasonal variations (p < 0.001), peaking in summer and autumn and reaching their lowest values in winter and spring. Spatially, phytoplankton abundance and biomass were not significantly different (p > 0.05), the abundance and biomass of Cyanophyta were higher in the two reservoir areas compared to the upstream sampling points. This suggests that the hydraulic projects altered the river’s flow and velocity, which led to a succession in phytoplankton community composition. Correlation analysis showed a strong positive association between the abundance and biomass of both Cyanophyta and Chlorophyta and water temperature (p < 0.001), but showed a significant negative relationship with nitrogen (p < 0.05). In contrast, Bacillariophyta abundance and biomass were positively and significantly correlated with ammonium nitrogen (p < 0.05). Redundancy analysis confirmed that water temperature and nitrogen are the primary environmental variables influencing the phytoplankton community’s succession. The direct alteration of river hydrodynamic characteristics by hydraulic projects, coupled with the reservoir-induced water stratification and its influence on vertical water temperature distribution, ultimately results in the profound reshaping of the phytoplankton community structure through coupled effects with nitrogen cycling. The findings from this study can scientifically inform the ecological scheduling, water quality management and water supply security of the Ganjiang River basin’s cascade reservoirs. Full article

The removal of primer from aircraft skin epoxy resin primer plates was investigated by using an adaptive hydraulically controlled polishing tool in conjunction with an industrial robot. This study examined the effects of several key process parameters—grinding force, rotational speed, feed speed, and abrasive grit size—on primer removal depth and surface roughness. Through both single-factor analysis and response surface methodology (RSM), the variation patterns of removal depth and surface roughness with respect to these parameters were elucidated. RSM was employed to develop regression models for the primer removal depth and removal rate. The relative errors of these regression models were found to be within 8%, while the maximum relative error of the backpropagation neural network prediction model for surface roughness Ra is 9.5%. These models exhibit high accuracy in predicting the material removal depth, material removal depth rate, and surface roughness of the primer plates. The optimal parameters for the adaptive hydraulically controlled polishing tool were identified as flows: a polishing force of 20 N, a feed speed of 40 mm·s⁻¹, a rotational speed of 2000 rpm, and 80-grit sandpaper. Under these conditions, the maximum removal depth reaches 27.5 µm, the highest removal rate is 5.501 µm·s⁻¹, and the surface roughness Ra is 1.897 µm. Full article

This study employed Computational Fluid Dynamics (CFD) simulations using FLOW-3D v11.2 software to systematically investigate the hydraulic characteristics of Asymmetric Triangular Labyrinth Weirs (ATLWs), with a comparative analysis against conventional Symmetric Triangular Labyrinth Weirs (STLWs). The Volume of Fluid (VOF) method and the Renormalization Group (RNG) k-ε turbulence model were adopted to accurately capture the free-surface and turbulence behaviors. The results demonstrate that ATLWs induce significant flow deflection, leading to the formation of distinctive local cavities and a unique flow regime characterized by the coexistence of fully aerated nappe flow and local submergence. Compared to STLWs, this asymmetric configuration generates more complex three-dimensional flow structures and altered pressure distribution patterns. Under low headwater conditions, the hydraulic performance (C_d and Q/Q_n) of both weir types is similar; however, under high headwater conditions, the C_d of STLWs is approximately 5.4–14.3% higher than that of ATLWs. A noteworthy finding is that increasing the cycle number (n) significantly enhances the discharge capacity of ATLWs, whereas this effect is not pronounced in STLWs. Based on comprehensive parametric analysis, this study developed a generalized empirical formula with exceptionally high predictive accuracy for estimating C_d, providing a practical tool for optimizing ATLW designs in engineering applications. Full article

The evaluation of the fracturing effect of coalbed methane (CBM) wells is crucial for the efficient development of CBM reservoirs. Currently, studies focusing on the evaluation of the hydraulic fracture stimulation effect of coal seams and the integrated analysis of “drilling-fracturing-monitoring” are relatively insufficient. Therefore, this paper takes three drainage and production wells in the coalbed methane block on the northwest wing of the Xiangxia anticline in the Bijie Experimental Zone of Guizhou Province as the research objects. In view of the complex geological characteristics of this area, such as multiple and thin coal seams, high gas content, and high stress and low permeability, the paper systematically summarizes the results of drilling and fracturing engineering practices of the three drainage and production wells in the area, including the application of key technologies such as a two-stage wellbore structure and the “bentonite slurry + low-solid-phase polymer drilling fluid” system to ensure wellbore stability, low-solid-phase polymer drilling fluid for wellbore protection, and staged temporary plugging fracturing. On this basis, a study on microseismic signal acquisition and tomographic energy inversion based on a ground dense array was carried out, achieving four-dimensional dynamic imaging and quantitative interpretation of the fracturing fractures. The results show that the fracturing fractures of the three drainage and production wells all extend along the direction of the maximum horizontal principal stress, with azimuths concentrated between 88° and 91°, which is highly consistent with the results of the in situ stress calculation from the previous drilling engineering. The overall heterogeneity of the reservoir leads to the asymmetric distribution of fractures, with the transformation intensity on the east side generally higher than that on the west side, and the maximum stress deformation influence radius reaching 150 m. The overall transformation effect of each well is good, with the effective transformation volume ratio of fracturing all exceeding 75%, and most of the target coal seams are covered by the fracture network, significantly improving the fracture connectivity. From the perspective of the transformed planar area per unit fluid volume, although there are numerical differences among the three wells, they are all within the effective transformation range. This study shows that microseismic fracture monitoring technology can provide a key basis for the optimization of fracturing technology and the evaluation of the production increase effect, and offers a solution to the problem of evaluating the hydraulic fracture stimulation effect of coal seams. Full article

Understanding urbanization and its impact on flooding and flood risk is crucial to better manage flood risk in the future. This study analyzed land use/land cover changes and how urbanization would impact flooding and flood risk in Kathmandu Valley of Nepal, and assessed flood risk by integrating flood hazards based on hydrologic–hydraulic modeling with the Analytic Hierarchy Process-based Multi-Criteria Decision Analysis (AHP-MCDA) approach. Land cover maps for past years were generated using Landsat satellite images, and land use/land cover maps for future years were projected based on machine learning techniques. Flood simulations were conducted using a rainfall runoff inundation model with land cover maps for different flood scales to analyze the impact of urbanization and land cover changes on flood runoff, flood inundation extent, and flood inundation volume. Then, we comprehensively assessed flood risk by integrating hazard conditions simulated under different land cover conditions using a hydrologic–hydraulic model and the AHP-MCDA approach. The results showed that the flood inundation extent and the peak inundation volume for a 200-year flood may increase in the future by 10.66% and 15.04%, respectively, as a result of urbanization. The results also highlighted that urbanization may lead to an expansion of high-risk and very-high-risk areas in the future by 3.2% and 9.4%, respectively, indicating an increase in the valley’s flood vulnerability and greater severity of flood hazards. Full article

To address the problems of local optima and insufficient convergence accuracy in parameter identification of primary frequency regulation (PFR) for steam turbines, this paper proposed a hybrid identification method that integrated an Improved Bayesian Optimization (IBO) algorithm and an Improved Whale Optimization Algorithm (IWOA). By initializing the Bayesian parameter population using Tent chaotic mapping and the reverse learning strategy, employing a radial basis kernel function hyperparameter training mechanism based on the Adam optimizer and optimizing the Expected Improvement (EI) function using the Limited-memory Broyden–Fletcher– Goldfarb–Shanno with Bounds (L-BFGS-B) method, IBO was proposed to obtain the optimal candidate set with the smallest objective function value. By introducing a nonlinear convergence factor and the adaptive Levy flight perturbation strategy, IWOA was proposed to obtain locally optimized optimal solutions. By using the reverse-guided optimization mechanism and employing a fitness-oriented selection strategy, the optimal solution was chosen to complete the closed-loop process of reverse learning feedback. Nine standard test functions and the Proportional Integral Derivative (PID) parameter identification of the electro-hydraulic servo system in a 330 MW steam turbine were presented as examples. Compared with Particle Swarm Optimization (PSO), Whale Optimization Algorithm (WOA), Bayesian Optimization (BO) and Particle Swarm Optimization-Grey Wolf Optimizer (PSO-GWO), the Improved Bayesian Optimization-Whale Optimization Algorithm (IBO-WOA) proposed in this paper has been validated to effectively avoid the problem of getting stuck in local optima during complex optimization and has high parameter recognition accuracy. Meanwhile, an Out-Of-Distribution (OOD) Test based on noise injection had demonstrated that IBO-WOA had good robustness. The time constant identification of the steam turbine were carried out using IBO-WOA under two experimental conditions, and the identification results were input into the PFR model. The simulated power curve can track the experimental measured curve well, proving that the parameter identification results obtained by IBO-WOA have high accuracy and can be used for the modeling and response characteristic analysis of the steam turbine PFR. Full article

This study presents a forensic investigation of the catastrophic failure of the La Luciana Tailings Storage Facility (TSF) in Reocín, Spain, in 1960. The collapse released approximately 300,000 m³ of tailings, causing 18 fatalities, extensive flooding of farmland and lakes, and the contamination of the Besaya River, leading to long-term environmental degradation. The analysis integrates historical documentation, cartographic evidence, in situ testing, laboratory analyses, and numerical modelling to reconstruct the failure sequence and identify its causes. Geotechnical characterization based on cone penetration tests (CPTs), shear wave velocity profiles, and laboratory testing revealed pronounced heterogeneity, with alternating contractive and dilative layers. Hydraulic analyses indicate permeabilities from 10⁻⁵ m/s in sand dam materials to 10⁻⁹ m/s in fine-grained pond deposits, with evidence of capillary saturation exceeding 20 m, favouring excess pore-pressure accumulation. Limited equilibrium and finite element analyses show that when the decant pond was within ~20 m of the dam, the factor of safety dropped to unity, triggering retrogressive flowslides consistent with field evidence. The results underline critical lessons for TSF governance: maintaining unsaturated tailings, ensuring efficient drainage and decant systems, and monitoring pond proximity to the dam. These are essential to prevent flow failures. This research also demonstrates a replicable forensic methodology applicable to other historical TSF failures, enhancing predictive models and informing modern frameworks such as the EU Directive 2006/21/EC and the Global Industry Standard on Tailings Management (GISTM). Full article

An operational test and degradation analysis of a hydraulic fluid based on synthetic esters was performed in three types of work machines. To enhance its performance, ZDDP anti-wear agents were added. Hydraulic fluids are susceptible to degradation by oxidation; therefore, to ensure the long service life of the equipment, it is essential to monitor their current condition through laboratory analyses during machine operation. Emission spectrometry was used to determine the presence of contaminants and the concentration of additive substances in the oil. Pollution was assessed by cleanliness code analysis according to ISO 4406-2021, alongside Total Acid Number (TAN) analysis and LNF analysis of wear and contamination in lubricants. The combination of cleanliness code analysis and LNF analysis of particle type and origin allows for monitoring not only the count but also the origin of contaminating metallic particles, which increases the probability of correct diagnostics and successful detection and resolution of wear problems. All three machines were still operational at the end of the test interval, meaning the tested hydraulic fluid is a suitable alternative to mineral variants. However, in all three pieces of equipment, it is necessary to replace the hydraulic fluid and flush the system before further operation. Furthermore, we recommend replacing the filter elements and inspecting the internal spaces of rotating parts with an increased potential for wear. From the oil’s perspective, it is advisable to add more anti-wear additives (ZDDP), which are depleted the fastest. Full article

Gas injection displacement technology plays a critical role in enhancing coalbed methane (CBM) and mine gas extraction efficiency. Numerical simulation is essential for revealing multi-field coupling mechanisms and optimizing process parameters, effectively addressing challenges such as high field test costs and limited laboratory scalability. This study systematically reviews progress in modeling physical fields (e.g., flow and diffusion), focusing on multi-physical field coupling mechanisms and permeability model evolution. It conducts iterative numerical model analysis—from basic flow–diffusion to fully coupled THMC models—compares simulation software (COMSOL shows greater coupling depth and compatibility than COMET3), and characterizes key mechanisms. By systematically reviewing the key advancements in the fields of numerical simulation in recent years (including important achievements such as the Buddenberg–Wilke equation and the improved Palmer–Mansoori model), a decision-making framework was proposed based on these achievements, covering “Multi-physical Field Coupling Equation Selection, Key Parameter Calibration, Permeability Equation Selection, Model Validation and Error Correction” simulation error ≤10% in heterogeneous coal seams. Although general-purpose tools enable high-precision multi-physics coupling, improvements are still needed in modeling flow–diffusion mechanisms, heterogeneity, and chemical field integration. This study provides a systematic methodological reference for the engineering application of gas injection displacement numerical simulation, and the framework constructed hereby can also be extended to shale hydraulic fracturing and other related fields. Full article

Relief well designs mainly focus on conventional parameters such as well diameter and well spacing by engineering experience, lacking rigorous analysis. The impact of wellhead elevation remains unclear. This paper proposes a multi-objective optimization method for determining the design parameters (i.e., the wellhead elevation and number of wells) of relief wells. MODFLOW is used to develop a three-dimensional transient seepage numerical model of the levee. The design parameters of relief wells are optimized by balancing the safety factor and the economic cost by non-dominated sorting genetic algorithm-II (NSGA-II). To remove computational burden within NSGA-II, random forest (RF) is used to establish an intelligent surrogate model for evaluating the hydraulic characteristics of levees. The final optimal design parameters are determined by entropy weight and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). Finally, the proposed approaches are illustrated using the Wuhan Yangtze River Levee, China. Results show that compared with the empirical approach, the optimal design parameters obtained by the proposed approaches can not only meet the safety threshold for the levee, but also reduce the costs by 15%. The importance of wellhead elevation on the hydraulic gradient is about six times that of the number of wells. Full article

Understanding cyanobacterial dominance in tropical reservoirs is crucial for water management. This study examined the dynamics of water quality in the João Leite Reservoir, situated in the Brazilian Cerrado, utilising 30 months of monitoring data from five sites. Physical, chemical, and biological parameters, including fluorometric chlorophyll-a, using multivariate statistics (Cluster Analysis, Principal Component Analysis, PCA; Canonical Correlation Analysis, CCA), were analysed alongside the Trophic State Index (TSI). Results showed temporal variations exceeded spatial differences. Cyanobacteria were dominant despite generally low nutrient levels and an oligotrophic TSI classification. Principal Component Analysis revealed that temperature is strongly associated with cyanobacterial density. However, Canonical Correspondence Analysis and correlations revealed limited direct statistical influence of measured physicochemical parameters, including nutrients, on cyanobacterial abundance. Findings suggest that in this warm, tropical system, high temperatures combined with stable hydrodynamics, resulting from long hydraulic retention times (>180 days), likely facilitate cyanobacterial success, overriding direct nutrient limitation. Full article