Search Results (25)

In view of the problem that the qualified index of grain spacing deteriorates during high-speed operation of the pneumatic corn seed dispenser, a new method of homologous dual-action positive-pressure-assisted seed filling and seed release is proposed, and a pneumatic corn seed dispenser with assisted inflow filling is designed. The structure and working principle of the seed dispenser are explained, and a theoretical analysis is carried out on the seed filling and seed release process in the seed guide tube. The key structural parameters of the conical deflector-groove seed metering disc and the homologous airflow-assisted seed release mechanism are determined. The test factors were working pressure and operating speed, and the evaluation indicators were the qualified particle spacing index, missed sowing index, resowing index, and qualified particle spacing variation coefficient. A full-factor bench test was carried out, and the test results showed that when the sowing speed was 6 km/h and the working pressure was 5 kPa, the qualified particle spacing index was 96.37%, the missed sowing index was 0.30%, the resowing index was 3.33%, and the coefficient of variation in the qualified particle spacing was 17.37%. The results of the field test showed that when the operating speed was 6 km/h and the working pressure was 5 kPa, the qualified particle spacing index was 95.30%, the missed sowing index was 2.33%, and the resowing index was 2.37%. All indicators met the technical requirements for precision single-seed maize sowing. Full article

This innovative method improves the inefficient optimization of the parameters of a pneumatic drum seed metering device. The method applies a backpropagation neural network (BPNN) to establish a predictive model and multi-objective particle swarm optimization (MOPSO) to search for the optimal solution. Six types of small vegetable seeds were selected to conduct orthogonal experiments of seeding performance. The results were used to build a dataset for building a BPNN predictive model according to the inputs of the physical properties of the seed (thousand-grain weight, kernel density, sphericity, and geometric mean diameter) and the parameters of the device (vacuum pressure, drum rotational speed, and suction hole diameter). From this, the model output the seeding performance indices (the missing and reseeding indexes). The MOPSO algorithm uses the BPNN predictive model as a fitness function to search for the optimal solution for three types of seeds, and the optimized results were verified through bench experiments. The results show that the predicted qualified indices for tomato, pepper, and bok choi seeds are 85.50%, 85.52%, and 84.87%, respectively. All the absolute errors between the predicted and experimental results are less than 3%, indicating that the results are reliable and meet the requirements for efficient parameter optimization of a seed metering device. Full article

To enhance the uplift resistance of micropiles used in soil slope reinforcement and ensure the stability and safety of slope structures, a novel micropile incorporating a small-scale pneumatic device and anchorage components was developed, and its uplift performance was evaluated. Through field uplift tests, the uplift load–vertical displacement relationship of the new micropile and conventional micropile in silty clay strata was compared. Numerical simulations were also conducted to reveal the uplift mechanism and analyze the influence of an anchorage component layout on the micropile’s uplift resistance. The field tests showed that the ultimate uplift capacity of a 3 m long novel micropile increased by 161.7% compared to that of a conventional micropile, with a 14.7% reduction in displacement. When the anchorage components were deployed without grouting, the novel micropile achieved 70.7% of the uplift capacity of a conventional micropile, indicating a certain level of uplift resistance. Numerical simulation results indicated that the novel micropile altered the stress state of the surrounding soil, and the anchorage components changed the load transfer mechanism during micropile uplift from vertical interfacial friction to a combination of anchorage pressure and soil friction, significantly enhancing uplift resistance. For an 8 m long micropile without anchorage components, the ultimate uplift capacity was 489.9 kN. With the addition of 1 m of anchorage length, the capacity increased to 661.5 kN, a 35.0% improvement. Subsequently, each additional meter of anchorage length increased the micropile’s capacity by 10.9% to 16.0%, with a cost increase of only 5.7%. The research findings provide valuable scientific references for the design and remediation of soil slope reinforcement. Full article

The precision of simulation plays a pivotal role in determining the design parameters of the pressure pipe and distributor in a pneumatic centralized seeding system. This study adopted the discrete element method (DEM) to investigate wheat seed models and their motion characteristics within a pneumatic precision seed-metering device. Using Xinchun No. 6 wheat as the experimental subject, multi-sphere combination models (5, 7, 9, and 11 balls) were employed to describe the seed particle morphology. Moreover, by utilizing the coupling method of the Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD), along with bench tests, the air suspension velocity of seeds and the motion characteristics of the seed-supplying device were analyzed under different particle models. The physical properties of the wheat seeds were measured during the experiments. The simulation results indicated that, as the seed supply rate increased, the airflow velocity distribution within the model became more uniform, enhancing the stability of the suspension velocity. Comparisons between experiments and simulations validated the reliability of the particle models, with the minimum relative error in the suspension velocity determined as 0.21% for the 9-balls model. In addition, compared to the other models, the 9- and 5-balls models more accurately simulated the dynamic behavior of seeds within the seed-supplying device. For the 9-balls model, the relative error of particle velocity in the seed-supplying device is 1.39%, and, in the simulation of displacements in the X and Y directions of the seed-supplying device, the average error is 9.51%. The effectiveness of the multi-sphere combination models was verified, indicating their ability to accurately reflect the dynamic behavior of wheat seeds and improve the design and optimization efficiency of pneumatic precision seed-metering devices. Full article

To meet the diverse seeding requirements of super hybrid rice, common hybrid rice, and conventional rice—which vary from 1 to 3 seeds, 2 to 4 seeds, and 5 to 8 seeds per hole, respectively—this study developed a branched air-chamber type pneumatic seed metering device for rice. The device utilizes an air chamber control board to manage the branched air chamber casing, enabling precise adjustments to the seeding quantity. This study presents a theoretical analysis of the seed metering device’s operation and its critical components. Structural parameter optimization was conducted using Ansys-Fluent (2021 R1) software, followed by multi-objective optimization of operational parameters through bench testing. Simulation results indicated that optimal vacuum pressure in the seed metering disc pores reached a maximum of 857 Pa with a chamber depth of 22 mm, an angle of 100°, and a cavity depth of 25 mm, achieving a minimal coefficient of variation of 0.86%. Bench test results showed that for seeding targets of 1 to 3 rice seeds per hole, the optimal operational parameters were: two openings, a working vacuum of 1355 Pa, and a rotor speed of 32.78 r/min, resulting in a missed seeding rate of 4.70%, a qualification rate of 85.81%, and a re-seeding rate of 9.49%. For targets of 2 to 4 seeds per hole, the best parameters included three openings, a working vacuum of 1357 Pa, and a speed of 32.87 r/min, with a missed seeding rate of 4.60%, a qualification rate of 85.59%, and a re-seeding rate of 9.81%. For 5 to 8 seeds per hole, optimal parameters were six openings, a vacuum of 1339 Pa, and a rotor speed of 31.07 r/min, yielding a missed seeding rate of 4.09%, a qualification rate of 87.27%, and a re-seeding rate of 8.64%. These findings demonstrate that the branched air-chamber type pneumatic seed metering device effectively meets the varied direct seeding requirements of rice, enhancing the adaptability of pneumatic seed metering devices to different seeding quantities in rice and potentially informing the design of pneumatic seeders for other crops. Full article

Background and Objectives: Bedridden patients are at a high risk of venous thromboembolism (VTE). Passive devices such as elastic compression stockings and intermittent pneumatic compression are common. Leg exercise apparatus (LEX) is an active device designed to prevent VTE by effectively contracting the soleus muscle and is therefore expected to be effective in preventing disuse of the lower limbs. However, few studies have been conducted on the kinematic properties of LEX. Therefore, this study aimed to compare the exercise characteristics of LEX with those of an ergometer, which is commonly used as a lower-limb exercise device, and examine its effect on the two domains of muscle activity and circulatory dynamics. Materials and Methods: This study used a crossover design in which each participant performed both exercises to evaluate the exercise characteristics of each device. Fifteen healthy adults performed exercises with LEX and an ergometer (Terasu Erugo, SDG Co., Ltd., Tokyo, Japan) for 5 min each and rested for 10 min after each exercise. Muscle activity was measured using surface electromyography (Clinical DTS, Noraxon, Scottsdale, AZ, USA), and circulatory dynamics were recorded using a non-invasive impedance cardiac output meter (Physioflow Enduro, Manatec Biomedical, Paris, France). The primary outcome was the mean percentage of maximum voluntary contraction (%MVC) of the soleus muscle during exercise. Results: The mean %MVC of the soleus muscle was significantly higher in the LEX group, whereas no significant differences were observed across the periods and sequences. Heart rate, stroke volume, and cardiac output increased during exercise and decreased thereafter; however, the differences between the devices were not significant. Conclusions: LEX may not only have a higher thromboprophylaxis effect, but also a higher effect on preventing muscle atrophy as a lower-extremity exercise device. Additionally, LEX could potentially be used safely in patients who need to be monitored for changes in circulatory dynamics. Full article

Aiming at solving the problem of a wide variety of crop planting and addressing the concept of precision agriculture, a pneumatic universal seed-metering device suitable for corn and soybean was designed. According to the physical size of the above two crops crop planting, a seeding plate, a hole, and a guide tube were designed. The pressure distribution inside the seeding plate was studied, when the pressure, the diameter of the hole, and the rotation speed of the metering plate changed. Through the coupling simulation method of DEM and CFD, the effects of the air suction hole diameter, the air pressure intensity, and the seeding plate speed on the seeding performance were explored. The results showed that when the air suction hole diameter was 5.9 mm, the air pressure intensity was 3.5 kPa, and the seeding plate speed was 23.8 r/min, and the performance of corn seeding was the best, among which the seeding qualification index was 95.35%, the replay index was 1.45%, and the missed seeding index was 3.23%. When the air suction hole diameter was 6.1 mm, the air pressure intensity was 3.5 kPa, and the rotation speed of the seed plate was 24 r/min, the performance of soybean sowing was the best, in which the sowing qualification index was 95.76%, the reseeding index was 3.47%, and the missed sowing index was 0.77%. The bench verification test and the comparative test were carried out. The results showed that the seed-metering device had good seeding performance and could be applied to the general seeding operation of corn and soybean. Full article

Winter oilseed rape (Brassica napus L.), Europe’s foremost oilseed crop, is significantly impacted by hailstorms, leading to substantial yield reductions that are difficult to predict and measure using conventional methods. This research aimed to assess the effectiveness of photosynthetic efficiency analysis for predicting yield loss in winter rapeseed subjected to hail exposure. The aim was to pinpoint the chlorophyll fluorescence parameters most affected by hail stress and identify those that could act as non-invasive biomarkers of yield loss. The study was conducted in partially controlled conditions (greenhouse). Stress was induced in the plants by firing plastic balls with a 6 mm diameter at them using a pneumatic device, which launched the projectiles at speeds of several tens of meters per second. Measurements of both continuous-excitation and pulse-modulated-amplitude chlorophyll fluorescence were engaged to highlight the sensitivity of the induction curve and related parameters to hail stress. Our research uncovered that some parameters such as F_s, F_m’, Φ_PSII, ETR, F_o, F_v/F_m, and F_v/F_o measured eight days after the application of stress had a strong correlation with final yield, thus laying the groundwork for the creation of new practical protocols in agriculture and the insurance industry to accurately forecast damage to rapeseed crops due to hail stress. Full article

This paper proposes a solution to the problem of tight population in the filling area of traditional air suction seed metering devices during quinoa sowing, which leads to inaccurate adsorption. The proposed method disperses the population into a stable seed flow and absorbs the seeds in a flow posture. The flow adsorption precision seed metering device is designed and improved, and the key structure parameters are optimized based on the shape and size parameters of quinoa seeds. A four-factor and three-level response surface orthogonal test is conducted using the Box–Behnken experimental design. The number of seeds, flow angle, negative pressure at the suction hole, and advancing speed are taken as experimental factors, and the qualified index of grain number per hole, qualified index of hole distance, and coefficient of variation of hole distance are used as evaluation indices. The results are optimized using extreme value theory, and it is found that when the seed amount is 5.82 mm, the flow angle is 31.08°, the negative pressure of the air chamber is 1.7 kPa, and the advancing speed is 3.82 km·h⁻¹, and the qualified index of hole number is 94.37%, the qualified index of hole distance is 95.39%, and the coefficient of variation of hole distance is 4.51%. The results are in general agreement with the prediction through the bench validation test, which meets the requirements of quinoa seed metering devices. Full article

In order to solve the problems of domestic and foreign vegetable precision metering devices that easily damage seeds and have low seeding efficiency and poor qualification rate, this paper designs a one-machine for two-row pneumatic combination seeder, which is mainly composed of a pneumatic seeding mechanism and a honeycomb seeding mechanism. The mechanism and other components and theoretical analysis of the working process of the combined seed metering device clarifies the minimum negative pressure for adsorbing a seed during the suction stage, along with the negative pressure required for the seed-carrying stage. It also establishes the seeding speed and movement during planting with the trajectory parameter equation and uses ADAMS software to conduct virtual experiments on the influence of the number of holes, diameters, and heights of different types of honeycomb seeding disks on the success rate of seeding. Based on research on previous pneumatic seeding mechanisms, single factor tests, orthogonal tests, and high-speed photography tests of the honeycomb seeding disk of the combined seeder were carried out on the number of holes, the diameter of holes, and the height of seeding. The results of tests conducted on okra seeds showed that when the rotating speed of the pneumatic seeding disc was 18 r/min, the diameter of the pneumatic seeding disc hole was 2.4 mm, the vacuum degree was 3.5 kPa, the number of honeycomb seeding disc holes was 24, the hole diameter was 13 mm, and the seed height was 60 mm, the working performance of the combined seed meter reached the optimal level, which provides a reference for the development of a small seed vegetable precision seeder. Full article

In order to solve the problems of poor seed filling performance and the low compensation accuracy of large- and medium-sized missed seeding compensation devices under medium- to high-speed conditions, a pneumatic missed seeding automatic compensation system based on speed synchronization was designed. The key structure and parameters in terms of the seed metering plate and seed feeding arm were determined by theoretical analysis. A universal compensation control system for single-seed missed seeding and continuous missed seeding was designed. With regards to exploring the working performance, some relevant bench tests were carried out, with Zhengdan-958 corn seeds and Zhonghuang-37 soybean seeds serving as the test objects. First of all, a single-factor test was conducted to determine the optimal level ranges of the factors that influence seed filling performance, such as suction hole diameter, seed stirring bar thickness, and negative pressure. The test indicators were qualified seed filling rate, multiple seed filling rate, and missed seed filling rate. Next, the Box–Behnken design test was executed to explore to the influence law of each test indicator on corn seed filling performance. Then, the parameter optimization module was applied to achieve the best combination of operating parameters for the test factors. The optimal combination of parameters was a suction hole diameter of 5.3 mm, seed stirring bar thickness of 2.9 mm, and negative pressure of 4.1 kPa. Based on the optimal combination, a verification test of corn seed filling performance was performed, and the corresponding evaluation indexes were a qualified seed filling rate of 95.46%, multiple seed filling rate of 2.47%, and missed seed filling rate of 2.07%. Lastly, a seed feeding performance verification test was employed with the seeding speed as the impact factor to verify the compensation accuracy of single-seed missed seeding and continuous missed seeding compensation. The results of the verification test indicate that, for corn seeds, when the seeding speed falls within the range of 8 to 12 km/h, the effective single-seed feeding rate exceeds 88%, the average single-seed feeding time is less than 0.18 s, the qualified seed feeding rate is higher than 90%, the multiple seed feeding rate is lower than 3%, and the missed seed feeding rate is below 7%. For soybean seeds, the effective single-seed feeding rate is higher than 85%, the average single-seed feeding time is less than 0.17 s, the qualified seed feeding rate exceeds 86%, the multiple seed feeding rate is less than 4%, and the missed seed feeding rate is below 10%. This system meets the agronomic requirements for the automatic compensation of missed seeding with respect to large- and medium-sized precision seeders, which could help to improve the operational performance of seeding machines. Full article

The planter plate is the most important component of the pneumatic hill-drop seed metering system for rapeseed. The structural parameters of the planter plate are the primary determinants of rape planting. The key structural and operational parameters, such as the layout of the suction hole, its diameter, and its shape, were determined through theoretical analysis. Fluent is used to simulate the flow field of various types of suction holes, and the effect of suction hole shape on the change in the flow field of the suction chamber shell is analyzed. Under the same boundary conditions, the results indicate that the maximum velocity of the end face of the horn hole and the average pressure of the section are the highest. Using a high-speed camera, the effects of suction hole diameter and shape on seed filling performance were studied, and the results of Fluent simulation analysis were validated. The optimal seed metering device operating parameters were as follows: planter plate speed of 30–70 r/min and negative pressure of −2.5–−1.5 kPa. The influence of working negative pressure and the rotational speed of the planter plate on seed arrangement performance was studied within the optimal operating parameter range. In order to improve the performance of rational close planting in the seed planter, the multi-objective optimization design of working parameters and the verification test were also conducted. The results showed that with the best combination of working parameters, the empty broadcast rate does not go above 3%, the hole number qualified rate does not go below 96%, and the difference between them and the theoretical optimization result does not go above 5.5%. Full article

Aiming to solve the problems of the poor uniformity of seed flow discharge and serious damage of traditional straight grooved wheels to improve the performance of air-assisted maize high-speed precision seed metering devices, a staggering symmetrical spiral grooved feeding wheel with maize seeds was designed. To explore the influence of the spiral groove inclination angle and the length of the staggered symmetrical spiral groove feed wheel on the uniformity of seed flow discharge, the spiral groove length l and the spiral groove inclination angle ρ were used as the experimental factors, and the variation coefficient of the increase in seed, a full-factor simulation test was carried out for the test indicators, and it was found that both the inclination angle and the length of the spiral groove have an influence on the uniformity of seed flow discharge, and the influence of the inclination angle of the groove is more significant. Comparing the force of a single seed in the traditional straight grooved wheel and that of the spiral feeding wheel, it is found that the staggered symmetrical spiral grooved feeding wheel can reduce the damage of seed fertilizer. Through a bench test, the spiral groove length was found to be 50 mm, and the groove inclination angles are 30°, 45° and 90°. The test results show the variation trend and simulation results of the fluctuating coefficient of variation of the seed flow discharge in the bench test. The trend of change is basically the same. The inclination angle of the spiral groove is 45° and the uniformity of seed flow discharge is the best when the groove length is 50 mm, indicating that this structure can effectively improve the uniformity of material discharge, and the variation coefficient of seed flow discharge fluctuation is 3.12% and the seed breakage rate is 0.69%. Through the seeding performance test, it is verified that the staggered symmetrical spiral grooved feeding wheel can improve the seeding performance of the pneumatic high-speed precision metering device. When the metering device runs smoothly, the qualified rate reaches more than 90%, and the leakage rate is reduced to 0%. Therefore, the results of this study can provide a reference for research on uniform seeding, drill seeding and the uniform application of granular fertilizer. Full article

The seeding performance of a pneumatic seed-metering equipment for rapeseed has a significant bearing on the sowing effect. When the negative pressure falls abruptly, the pneumatic system experiences a significant loss of negative pressure. This will prevent rapeseed from being entirely absorbed by the seed plate, resulting in inconsistent seeding quantities along each row. In this study, CFD simulations were used to analyze the airflow field affecting the airflow transmission of an airflow distribution device. The essential structural characteristics of a conical cylinder conical-arranged kind of airflow distribution device were found, and the causes of negative pressure loss were analyzed from the standpoint of fluid kinematics. The optimal structural type of airflow distribution device was determined using fluid simulation. In addition, an orthogonal examination of the ideal type’s essential structural characteristics was conducted to minimize negative pressure loss during airflow transmission. Then, the influence of the negative pressure loss rate of the airflow distribution device on the variation coefficient of seeding quantity in each row of the seed-metering device was investigated using a bench test involving three factors: seed plate rotational speed, working negative pressure, and structure type. It was discovered that three parameters have highly substantial impacts on the negative pressure loss rate and the variation coefficient of seeding quantity in each row, and that the negative pressure loss rate correlates positively with the variation coefficient of the seeding quantity in each row. When negative pressure fell to 500 Pa, the negative pressure loss rate of the optimal structure type and the variation coefficient of seeding amount in each row of the seed-metering device fell by 6.25% and 3.45%, respectively. Field experiments reveal that the negative pressure loss rate of an airflow distribution device was below 20% and that the variation coefficient of seeding amount in each row of seed-metering devices was below 3.5%. The results can be used to analyze the construction of the pneumatic system and enhance the performance of the seed-metering equipment. Full article

In order to improve the single-grain seeding rate of the pneumatic single seed metering device, an airflow seed cleaning device was designed in combination with positive pressure airflow. The influence of the position of the seed cleaning mechanism on the seed cleaning effect is theoretically analyzed and a flow field simulation test analysis of different nozzle structures was carried out by using Fluent software (ANSYS, Inc., Canonsburg, PA, USA). The results of this test show that a nozzle with a Witoszynski curve has good airflow concentration and uniform air pressure distribution. In order to verify the performance of the seed cleaning mechanism, a 0.7 times coated seed (hybrid rice Wuyou 1179) was used as the test material and a quadratic regression test with three levels was carried out with the rotation speed of the seed plate, the negative pressure of the suction chamber, and the positive pressure of the seed cleaning as the test factors. The results showed that when the speed of sucking plate was 30 r/min, the negative pressure of the suction chamber was 1.8 kPa and the positive pressure of the seed cleaning was 0.2 kPa; the seeding effect was at its best and the qualified rate of the seed metering device was the highest at 86.43%, the minimum leakage rate was 3.81%, and the multiple rate was 9.76%. The proposed seed cleaning mechanism effectively improves the accuracy of seeding and provides a certain theoretical basis for the single-grain sowing of hybrid rice. Full article