Search Results (387)

The conveying hose is an important piece of equipment in the field of Marine engineering. Its spatial configuration and force conditions affect the normal operation of the Marine engineering system. This paper proposes a flexible, fully hose-based conveyance method for the field of deep-sea mining and mainly uses Orcaflex software to simulate and analyze the characteristics of the conveying hose in this system. This paper studies the influences of the top spacing, incoming flow direction, and placement and recovery processes on the configuration characteristics and force conditions of the hose. The conclusion drawn is that the conveying hose studied in this paper can maintain a good spatial configuration underwater and has a stable force condition. When the top spacing is 20 m, the transition of the curved section at the bottom of the hose is relatively smooth. The top tension of the hose has a good adaptability to the top spacing and the direction of the incoming flow. The conveying hose can stably complete the deployment and recovery operations. Full article

This study investigates the dynamic response mechanisms of discharge capacity in the Han River Estuary to hydrological process changes at the Yangtze–Han River confluence. By constructing a one-dimensional hydrodynamic model for the 265 km Xinglong–Hankou reach, we quantitatively decouple the synergistic effects of riverbed scouring (mean annual incision rate: 0.12 m) and Three Gorges Dam (TGD) operation through four orthogonal scenarios. Key findings reveal: (1) Riverbed incision dominates discharge variation (annual mean contribution >84%), enhancing flood conveyance efficiency with a peak flow increase of 21.3 m³/s during July–September; (2) TGD regulation exhibits spatiotemporal intermittency, contributing 25–36% during impoundment periods (September–October) by reducing Yangtze backwater effects; (3) Nonlinear interactions between drivers reconfigure flow paths—antagonism occurs at low confluence ratios (R < 0.15, e.g., Cd increases to 45 under TGD but decreases to 8 under incision), while synergy at high ratios (R > 0.25) reduces Hanchuan Station flow by 13.84 m³/s; (4) The 180–265 km confluence-proximal zone is identified as a sensitive area, where coupled drivers amplify water surface gradients to −1.41 × 10⁻³ m/km (2.3× upstream) and velocity increments to 0.0027 m/s. The proposed “Natural/Anthropogenic Dual-Stressor Framework” elucidates estuary discharge mechanisms under intensive human interference, providing critical insights for flood control and trans-basin water resource management in tide-free estuaries globally. Full article

Sediment accumulation in irrigation channels poses a significant challenge to water resource management, impacting hydraulic efficiency and agricultural sustainability. This study introduces an innovative multidisciplinary framework that integrates advanced image analysis (FIJI/ImageJ 1.54p), statistical validation (RStudio), and vector field modeling with a novel Sinusoidal Morphodynamic Bedload Transport Equation (SMBTE) to predict sediment deposition patterns with high precision. Conducted along the Malacatos River in La Tebaida Linear Park, Loja, Ecuador, the research captured a natural sediment transport event under controlled flow conditions, transitioning from pressurized pipe flow to free-surface flow. Observed sediment deposition reduced the hydraulic cross-section by approximately 5 cm, notably altering flow dynamics and water distribution. The final SMBTE model (Model 8) demonstrated exceptional predictive accuracy, achieving RMSE: 0.0108, R²: 0.8689, NSE: 0.8689, MAE: 0.0093, and a correlation coefficient exceeding 0.93. Complementary analyses, including heatmaps, histograms, and vector fields, revealed spatial heterogeneity, local gradients, and oscillatory trends in sediment distribution. These tools identified high-concentration sediment zones and quantified variability, providing actionable insights for optimizing canal design, maintenance schedules, and sediment control strategies. By leveraging open-source software and real-world validation, this methodology offers a scalable, replicable framework applicable to diverse water conveyance systems. The study advances understanding of sediment dynamics under subcritical (Fr ≈ 0.07) and turbulent flow conditions (Re ≈ 41,000), contributing to improved irrigation efficiency, system resilience, and sustainable water management. This research establishes a robust foundation for future advancements in sediment transport modeling and hydrological engineering, addressing critical challenges in agricultural water systems. Full article

To address the issue of poor film–soil separation in traditional subsoil residual film recovery machines, which leads to recovered film containing excessive soil, a film–soil conveying and separation device was designed. By establishing a mechanical model for the balanced conveyance of the film–soil composite, the range of conveyor chain inclination angles enabling stable transport was determined. Using RecurDyn 2023 simulation software, a sensitivity analysis was conducted on the effects of vibrating wheel speed, vibrating wheel mounting distance, and conveyor chain inclination angle on vibration characteristics. This analysis revealed that vibrating wheel speed and mounting distance have a significant impact on the vibrating mechanism. Based on the DEM–MBD (Discrete Element Method—Multi-Body Dynamics) coupling approach, a discrete element simulation model was built for the film–soil vibrating conveyor device, residual film, and soil. Using the primary conveyor chain speed, vibrating wheel speed, and mounting distance as experimental factors, and soil content rate and film leakage rate as experimental indicators, single-factor tests and a three-factor, five-level orthogonal rotational composite design test were performed. The results showed that, at a primary conveyor chain speed of 1.61 m/s, a vibrating wheel speed of 186.2 r/min, and a mounting distance of 688.2 mm, the soil content rate was 18.11% and the film leakage rate was 7.61%. The film–soil conveying and separation process was also analyzed via simulation. Field validation tests using the optimal parameter combination yielded relative errors of 3.43% and 5.51%, respectively, demonstrating effective film–soil separation. This research provides a theoretical foundation and equipment support for addressing residual film pollution in the cultivated layer of Xinjiang region. Full article

This study investigates the impact of pipe installation height on the hydraulic performance of a combined canal–pipe water conveyance system (CCPS) and provides practical recommendations. A combined experimental and numerical simulation approach was conducted to systematically analyze and evaluate the impact of different pipe installation heights (0, 1, 3, and 5 cm) and flow rates (18.40, 21.21, 24.74, 28.27, 33.58, and 38.88 L/s) on the system’s behavior. The results indicated that the canal water depths obtained from the numerical simulations were in close agreement with the measurements from the experiments. The water depth in the upstream canal remained nearly parallel to the canal bottom. At the junction, the trend of water depth varies under different flow rates. When the flow rate is low, the water depth sharply decreases. Conversely, when the flow rate is higher, the water depth rises significantly. Cross sections farther from the junction exhibit a higher uniformity in flow velocity distribution. As the height of the pipe installation increases, the range of influence of the junction on the flow velocity distribution in the upstream canal decreases. The elevation of the pipe installation height has been instrumental in enhancing the uniformity of flow velocity distribution across the section. However, the local head loss gradually increases as the installation height increases. Turbulent kinetic energy (TKE) and turbulent eddy dissipation rate (TED) are negatively correlated with the distance between the section and the junction point, and the maximum value decreases gradually with increasing values of the pipe installation height. Considering the hydraulic performance and engineering construction investment, the recommended pipe installation height under the conditions of this study is 1 cm. Full article

The effective management of river networks in coastal plains is crucial to flood control, water quality improvement, and sustainable flow distribution. This study aims to optimize the hydrodynamic performance of a plain river network in eastern China through water diversion and circulation scheduling, addressing challenges such as channel narrowing and sedimentation. This research study utilized a partitioned water allocation approach modeled in MIKE11 to simulate the effects of various diversion projects, including locks and connecting rivers, on the primary conveyance channel and supporting rivers. The simulation results indicated that flow velocities exceeded 0.1 m/s in most rivers, with significant improvements in flood discharge and water quality in the main conveyance channel and one supporting river. However, some sections of the network showed poor hydrodynamic performance due to narrow channels, encroachment, and sedimentation, and smaller rivers exhibited inadequate flow capacity. The findings provide critical insights for optimizing hydrodynamic regulation in coastal plain river systems, emphasizing the need to address specific issues to enhance overall network performance and flood resilience. Full article

Constructions located in rivers play a critical role in mitigating flood risks and supporting sustainable economic development. However, the specific impacts of bridge construction on local flood dynamics have not been thoroughly examined. This study addresses this research gap using hydrodynamic modeling with the one-dimensional MIKE11 module in MIKE Zero. A case study of the Nanyang (NY) Road Bridge in Zhejiang Province analyzed backwater effects at critical locations, including the Shili (SL) River outlet and Chengqing (CQ) Harbor. Unsteady flow simulations quantified changes in backwater height and backwater length upstream and downstream of the bridge, assessing their influence on flood conveyance capacity. The results indicate a narrowing of the river channel by approximately 4.8 m at the bridge location. Additionally, under flood conditions corresponding to 5-year, 10-year, and 20-year return periods, upstream water levels increased by 1 cm (6.53 m), 4 cm (7.15 m), and 5 cm (7.75 m), respectively. This research provides valuable insights and a scientific basis for developing flood control strategies, optimizing bridge design, and planning infrastructure projects, thereby enhancing regional flood safety and supporting sustainable economic development. Full article

Under the “dual-carbon” strategy, accurately quantifying carbon emissions in water conservancy projects is crucial to promoting low-carbon construction. However, existing life cycle assessment (LCA) methods for carbon emissions during the mechanical construction stage often fail to reflect actual processes and are limited by high costs and lengthy data collection, potentially leading to inaccurate estimates. To address these challenges, this paper proposes a carbon emission evaluation method for the mechanical construction stage, based on carbon footprint theory and discrete event simulation (DES). This method quantifies equipment operation time and energy consumption during the drilling and blasting processes, enabling a detailed and dynamic emission analysis. Using the Fumin Pumped Storage Power Station Tunnel Project as a case study, a comparative analysis is conducted to examine the carbon emission characteristics of drilling and blasting operations under different surrounding rock conditions based on DES. The validity of the proposed model is confirmed by comparing its results with monitoring data and LCA results. The results show a clear upward trend in carbon emission intensity as surrounding rock conditions deteriorate, with emission intensity rising from 8405.82 kgCO₂e/m for Class II to 16,189.30 kgCO₂e/m for Class V in the headrace tunnel. The total carbon emissions of the water conveyance tunnels reach 40,019.64 tCO₂e, with an average intensity of 13,565.98 kgCO₂e/m. This study presents a refined and validated framework for assessing the carbon emissions of pumped storage tunnels. It addresses key limitations of traditional LCA methods in the mechanical construction stage and provides a practical tool to support the green transition of hydraulic infrastructure. Full article

Conveyance tube manufacturing via a hot-finished, welded route is an energy-intensive process that promotes the rapid surface oxidation of curved surfaces. Previous studies have used computational and theoretical techniques to assess the oxidation of curved surfaces. However, experimental techniques for assessing the oxidation of curved surfaces, as well as for validating existing computational and analytical studies, have significant limitations that impact their ability to accurately recreate industrial processes. The challenges of thermogravimetric analysis (TGA) for in situ tests for the oxidation of cylindrical geometries were investigated, using an as-welded conveyance tube, and compared to an equivalent tube normalised in industry as well as computational predictions for the same geometry and thermal conditions. A core element of this work was the use of a refractory dummy sample to quantify thermal buoyancy and flow-induced vibration. There was a strong agreement between the oxide mass gain predicted by a computational model compared to that of the TGA sample, with only a 5% discrepancy. However, oxide thickness gain, measured using electron microscopy, showed poor agreement, particularly when comparing industrial and experimental results. This was attributed to the need for further work to account for transient heating, oxide porosity, atmospheric composition variation, and the effect of thermomechanical operations during conveyance tube manufacturing, e.g., hydraulic descaling. Full article

Mechanized chili harvesting is essential for improving efficiency, reducing costs, and alleviating labor intensity in production. However, issues such as low harvesting efficiency, high rates of breakage, and contamination continue to severely hinder the development of mechanized chili harvesting. This study provides an overview of global chili production regions and varieties, examining three harvesting approaches: single-pass, multi-stage, and multi-pass approaches. It describes the operational principles of key harvesting mechanisms, including the helical spiral-type, drum finger-type, long-rod comb-type, and belt-mounted comb finger-type mechanisms, and summarizes research progress in major producing countries, such as the United States and China. The paper evaluates both airflow-based and mechanical cleaning–separation devices, highlighting the combined airflow mechanical systems as the most promising approach and reviews their current development status. It also addresses structural challenges in chassis, frameworks, and conveyance systems. Finally, the paper analyzes solutions to the existing challenges, emphasizing the integration of intelligent technologies to resolve mechanical issues, and outlines the future prospects of intelligent development in mechanized chili harvesting. Full article

This paper applies a semi-quantitative approach to review the diversity, environmental controls, detection methods, human health risks, and mitigation of cyanotoxins in drinking water systems (DWSs). It discusses the environmental factors controlling the occurrence of cyanotoxins, presents the merits and limitations of emerging methods of their detection (qPCR, liquid chromatography–mass spectrometry, and electrochemical biosensors), and outlines the human exposure pathways and health outcomes with identification of high-risk groups and settings. High-risk groups include (1) communities relying on untreated drinking water from unsafe, polluted water sources and (2) low-income countries where cyanotoxins are not routinely monitored in DWSs. The fate and behavior processes are discussed, including removing cyanotoxins in DWSs based on conventional and advanced treatment processes. The available methods for cyanotoxin removal presented in this paper include (1) polymer-based adsorbents, (2) coagulation/flocculation, (3) advanced oxidation processes, (4) ultra- and nanofiltration, and (5) multi-soil layer systems. Future research should address (1) detection and fate in storage and conveyance facilities and at the point of consumption, (2) degradation pathways and toxicity of by-products or metabolites, (3) interactive health effects of cyanotoxins with legacy and emerging contaminants, (4) removal by low-cost treatment techniques (e.g., solar disinfection, boiling, bio-sand filtration, and chlorination), (5) quantitative health risk profiling of high-risk groups, and (6) epidemiological studies to link the prevalence of human health outcomes (e.g., cancer) to cyanotoxins in DWSs. Full article

Jordan is a relatively small country with limited natural resources, but it faces a burgeoning demand for water, energy, and food to accommodate a growing population, refugee migration, and the challenges of climate change that will persist through the rest of this century. Jordan’s Main Water Conveyance System is the backbone of distributing scarce water resources to meet domestic and agricultural demands. Therefore, understanding how the future energy requirements of this system may change is critical for managing the country’s water, energy, and food resources. This paper applied a water balance model to calculate the energy consumption of Jordan’s Main Water Conveyance System between 2015 and 2050, and the results point to high energy requirements for the future of distributing Jordan’s water. In the base year of 2015, the unmet water demand was 134.55 MCM, and the supplied water volume delivered was 438.75 MCM, while the energy consumption was 1496.7 GWh. The energy intensities for water conveyance and water treatment were 7.11 kWh/m³ and 0.5 kWh/m³, respectively. We examined five scenarios of future water and energy demand within Jordan: a reference scenario, a continuation of current behavior, two scenarios incorporating improved water management strategies, and a pessimistic scenario with no interventions. According to all scenarios, the energy consumption is expected to be doubled by the year 2050, reaching approximately 3172 GWh. It is recommended that Jordan prioritizes solar-powered conveyance and pumping to reduce the projected doubling of energy demand by 2050. Across all scenarios, the demand for nonrenewable energy associated with water conveyance is projected to rise significantly, particularly in the absence of renewable integration or efficiency interventions. Total water demand is expected to increase by up to 35% by 2050, with urban and agricultural sectors being the primary contributors. Full article

Innovative solutions are needed for urban flooding exacerbated by climate change. In light of this, this study developed an integrated framework for urban wetland flood control that combines Morphospatial Pattern Analysis (MSPA), minimum cumulative resistance (MCR) modeling, and complex network theory for optimizing an ecological network of flood control and mitigation wetlands in Changchun, China. The results show that the optimized ecological network significantly improved connectivity and flood mitigation efficiency. The node degree increased from 2.737 to 3.433, and the average clustering coefficient exhibited an increase from 0.074 to 0.231, enhancing material flow efficiency. Robustness analysis revealed that the optimized network’s connectivity robustness improved by 12.6%, 18.4%, and 24.1% under random, malicious, and controlled attack scenarios, respectively. Additionally, ecological corridors with a width of 30–50 m were identified as the optimal range for water conveyance potential, effectively dispersing peak runoff and reducing flood risk. This study provides both a transferable methodology for flood-resilient planning and specific policy actions, including priority conservation of high-betweenness nodes and restoration of fragmented wetlands, offering practical solutions for high-density cities facing similar climate challenges. Full article

To address the challenge of optimizing system adaptability, disturbance rejection, control precision, and convergence speed simultaneously in four-wheel steering (4WS) stability control, a 4WS controller with a variable steering ratio (VSR) strategy and fast adaptive super-twisting (FAST) sliding mode control is proposed to control and output the steering angles of four wheels. The ideal VSR strategy is designed based on the constant yaw rate gain, and a cubic quasi-uniform B-spline curve fitting method is innovatively used to optimize the VSR curve, effectively mitigating steering fluctuations and obtaining precise reference front wheel angles. A controller based on FAST is designed for active rear wheel steering control using a symmetric 4WS vehicle model. Under double-lane change conditions with varying speeds, the simulations show that, compared with the constant steering ratio, the proposed VSR strategy enhances low-speed sensitivity and high-speed stability, improving the system’s adaptability to different operating conditions. Compared with conventional sliding mode control methods, the proposed FAST algorithm reduces chattering while increasing convergence speed and control precision. The VSR-FAST controller achieves optimization levels of more than 7.3% in sideslip angle and over 41% in yaw rate across different speeds, achieving an overall improvement in the stability control performance of the 4WS system. Full article

Riparian vegetation reduces the conveyance capacity and increases the likelihood of floods. Studies that consider vegetation in flow modeling rely on unmanned aerial vehicle (UAV) data, which restrict the covered area. In contrast, this study explores advances in remote sensing and machine learning techniques to obtain vegetation data for an entire river by relying solely on satellite data, superior to UAVs in terms of spatial coverage, temporal frequency, and cost effectiveness. This study proposes a machine learning method to obtain key vegetation parameters at a resolution of 10 m. The goal was to evaluate the applicability of remotely sensed vegetation data using the proposed method on a dynamic roughness distributed runoff model in the Abukuma River to assess the effect of vegetation on the typhoon Hagibis flood (12 October 2019). Two machine learning models were trained to obtain vegetation height and density using different satellite sources, and the parameters were mapped in the river floodplains with 10 m resolution based on Sentinel-2 imagery. The vegetation parameters were successfully estimated, with the vegetation height overestimated in the urban areas, particularly in the downstream part of the river, then integrated into a dynamic roughness calculation routine and patched into the RRI model. The simulations with and without vegetation were also compared. The machine learning models for density and height obtained fair results, with an R² of 0.62 and 0.55, respectively, and a slight overestimation of height. The results showed a considerable increase in water depth (up to 17.7% at the Fushiguro station) and a decrease in discharge (28.1% at the Tateyama station) when vegetation was considered. Full article