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To evaluate the safety of the bulb tubular turbine, the dynamic hydraulic characteristics of a hydropower station system during the load rejection process are studied through numerical simulations and a prototype test. In the developed model, a dynamic grid technology (DGT) controls the closure of the guide vane and the blade, whilst the moment balance equation and the user-defined function (UDF) provide the runner’s rotation speed. The 3-D transient simulation method can well predict the rotation speed and mass flow curves in the state of load rejection. The simulation outcomes of the system performance are basically consistent with the measurement data of the prototype. As observed, the runner is subjected to the reversely increased torque and axial force, the system is in a braking phase, and the maximum speed peaks at 144.6% of the rated speed. Moreover, the internal flow of the runner is greatly affected by the closure of the guide vane, and the draft tube forms an eccentric spiral vortex rope. It breaks downstream, aggravating the instability of the draft tube. Overall, the transient characteristics span for the first five seconds, demonstrating the importance of establishing an efficient governing controller. The obtained results are useful for designing the turbine’s flow channel with a double regulating function and comprehending the turbine’s transient characteristics.

Existing support systems for thermal pipeline trenches often fail to meet the specific needs of narrow strips, tight timelines, and short construction periods in urban environments. This study introduces a novel recyclable, non-embedded support system composed of corrugated steel plates, retractable horizontal braces, angle steel, and high-strength bolts designed to address these challenges. The system’s effectiveness was validated through prototype testing and optimized using Abaqus finite element simulations. The research hypothesizes that this new support structure will enhance construction efficiency, reduce installation costs, and provide adaptable and sustainable solutions in urban trench applications. Prototype tests demonstrated that the proposed support had maintained safety and stability in trenches of 2 m and 3 m depth under a 58 kPa load and rainfall, as well as the 4 m deep trenches under asymmetric loading of 80 kPa. Optimization of the proposed system included installing two screw jacks on each horizontal brace and adjusting the corrugated plates, resulting in reduced weight, improved node strength, and enhanced screw jack adjustability. Numerical simulations confirmed the optimized system’s reliability in trenches up to 3 m deep, with caution required for deeper applications to avoid structural failure. The proposed support system offers notable advantages over traditional methods by improving construction efficiency, flexibility, and adaptability while also reducing costs, ensuring safety, and promoting environmental sustainability. Its modular design allows for rapid installation and disassembly, making it suitable for projects with strict deadlines and diverse construction conditions. The findings uphold the initial hypotheses and demonstrate the system’s practicality in urban trench projects.

In order to enhance the comprehensive processing quality and production efficiency of seed melons, a seed melon crushing and seed-extraction separator has been developed and designed. Aiming at the issues of high impurity rate and scratch rate of melon seeds in the process of seed–flesh separation, the structure and parameters of the seed–flesh separation device were optimized in this study by simulation analysis and field testing. The simulation model of melon seed, melon flesh, and the seed–flesh separation device based on the discrete element method (DEM) was established, and the simulation parameters were calibrated. Subsequently, the melon seed impurity rate (G1) and the melon seed scratch rate (G2) were used as the evaluation indexes. The single-factor simulation test was carried out on the separation roller speed (A). The spacing between the scraper and the screen (B), the separation roller scraper inclination angle (C), and the influence rules of each factor on the separation effect of the seed–flesh were obtained. Finally, the three-factor and three-level orthogonal test was carried out. Using the method of ANOVA and multi-objective optimization, the optimal working parameters of the device were obtained as A-117.53 r/min, B-5 mm, and C-10°, at which time the optimal evaluation indexes were G1-5.59% and G2-2.85%. The prototype test was carried out with the optimization results. The values of G1 and G2 were measured at 5.71% and 2.91%, respectively, and the relative errors with the simulation values were 2.15% and 2.11%, respectively, which were basically the same between the simulation model and the prototype test. The results indicate that the designed separation roller speed, spacing between the scraper and screen, and separation roller scraper inclination angle can meet the requirements of seed–flesh separation in the seed melon crushing and seed-extraction separator. The results of the DEM study can provide a reference for the optimal design of the seed–flesh separation device.

In this article, a mathematical model of hydrodynamic force was established to model the influence of wall in realizing the precise control and maneuverability of a complex-shaped underwater robot. A hydrodynamic model of a robot for use in a nuclear reaction pool was presented containing not only hydrodynamics coefficients but also a wall hydrodynamic force term, which was often ignored for robots used at sea. First, hydrodynamic coefficients in the model, including viscous and inertial coefficients, were solved by simulating steady-state and unsteady-state motion by computational fluid dynamics. Next, the wall hydrodynamic force was calculated by computational fluid dynamics for different velocities and distances from the wall, and the scope of influence of the wall was identified. Finally, hydrodynamic coefficients without the wall effect and with the wall hydrodynamic force under different conditions were measured experimentally in a circulating water tank. The result demonstrated the accuracy of hydrodynamic calculation by computational fluid dynamics and verified the reliability of the hydrodynamic mathematical model.

Fiber-reinforced flexible pipes are subjected to large axial tension loads in deep-water applications, which may result in the excessive deformation of the pipes. Owing to the anisotropy of the composite materials, accurately describing the tensile behavior of these pipes is difficult. Theoretical, numerical, and experimental methods are employed in this study to investigate the mechanical characteristics of a glass fiber-reinforced unbonded flexible pipe under axial tensile loads. Based on the load–strain relationship of each pipe layer, analytical equations considering the effect of anisotropy and radial deformation are first proposed to calculate the axial tensile stiffness of the pipe. A detailed numerical model is established to simulate the tensile behavior of the pipe. A prototype test is performed on a 4500 mm long sample using a tensile testing machine. The leading roles of outer tensile reinforcement layers in axial tensile capacity are illustrated by the strain energy of the pipe layers obtained by the numerical model. Subsequently, a comparison analysis of the mean fiber direction strains of the selected sections are performed between numerical and experimental results, which validates the numerical model. Additionally, the stress distributions of different pipe layers are discussed based on the results of the numerical analysis. Finally, the comparison of axial tensile stiffness results validates the accuracy of the analytical model considering radial deformation. This study proposes effective theoretical and numerical models to predict the tensile behavior of a fiber-reinforced flexible pipe, which provides useful references for the design and structural analysis of these pipes.

Metal foams are newly developed engineered materials with attractive mechanical properties such as lightness, high resistance-to-weight ratio, and insulation capabilities. Lately, applications of these technologies have demonstrated the possibility of obtaining high-performance sandwich panels with steel skins and metal foam core, with potential applications across various fields. Within this framework, this work aims to assess the response of sandwich panels made of steel and aluminium foam to develop a new system of dry-assembled composite floors. The present study investigates a novel screwed steel–aluminium foam–steel (SSAFS) sandwich panel. This paper mainly describes and discusses the results of experimental tests devoted to evaluating the structural performance, mechanical properties, and suitability for practical applications of SSAFS. The fabrication process and the detailing of the steel skins and aluminium foam core assembly are also described. The results from the experimental tests revealed the potentialities of using SSAFS sandwich panels in terms of strength and stiffness, thus making them suitable for lightweight structural systems.

This paper focuses on the hydraulic header leveling system of grain combine harvesters, and comprehensively uses methods of theoretical analysis, simulation optimization and experimental research to deeply explore its dynamic characteristics. By establishing mathematical models of key components of the system, conducting simulation analysis with AMESim software, and carrying out prototype tests, the laws of dynamic characteristics of each component in the system are clarified, and the effectiveness of the optimization scheme is verified. This provides an important basis for the design and improvement of the hydraulic system of grain combine harvesters.

In order to solve problems: the existing household bean sprouts cultivation device is relatively simple; bean sprouts are easy to be contaminated in the open cultivation tank which affects the quality of bean sprouts, and the automation is poor. The bean sprouts device by soilless automatic cultivation adopts cylindrical closed culture bin structure, and the temperature and humidity sensor is set in the culture bin, which can monitor the environment in real time. At the same time, the heating plate, fan and humidifier are set in the culture bin to heat up, cool down and humidify the environment, so as to realize automatic bean sprouts cultivation. The prototype test showed that: at the temperature 26°C-30°C, humidity 85%-95%, the diameter of mung bean sprouts can reach 2.5mm, and the height can reach 150mm. the diameter of yellow bean sprouts can reach 3mm, and the height can reach 160mm. The average yield of the two sprouts was 98%. The device has the advantages of soilless, intelligence, miniaturization and simple operation, which can meet the requirements of automatic bean sprouts cultivation. It is a necessary product for household in the future.

The muon linac has been developed at J-PARC to accelerate muons from thermal energy (25 meV) to 212 MeV using electrostatic extraction and four different types of radio-frequency cavities: RFQ, IH-DTL, DAW-CCL, and disk-loaded structures. Although some of the technologies employed were relatively novel, most proof-of-principle demonstrations have been successfully completed through prototype testing and actual production. Based on these experiences, it has become possible to propose a shorter or more efficient schematic design derived from the current design. In this poster, the new schematic design will be presented.

To enhance the efficiency and reliability of buckling in rectangular parts, we conducted a mathematical analysis of the crimping equipment designed for these parts. This analysis focused on the double wedge angle of the inclined wedge structure. We derived the relationship between the wedge angle, stroke ratio, incremental force ratio, and transmission efficiency. Using ADAMS software for host kinematics simulation analysis and buckling prototype test analysis, the peak buckling pressure of the device is 2.9*106N, the working cycle is 9s, and the hourly yield rate reaches 98%. To study the buckling behavior of rectangular parts, this equipment aims to provide a reference basis for further industrial automation.