DESIGN AND EXPERIMENTAL STUDY OF FLEXIBLE THRESHING UNIT FOR CHINESE CABBAGE SEEDS

In order to solve the problems of low efficiency of artificial harvesting method and high breakage rate and undepurated rate of traditional threshing method, a new flexible threshing device of Chinese cabbage seeds was designed, which was composed of flexible round head nail teeth and circular tube concave plate. Hertz contact collision theory was used to analyze and determine the structural parameters of the new threshing unit. The interaction force of different threshing elements materials were analyzed by using EDEM. The feasibility of the flexible threshing unit was verified by the comparison test of the distribution of threshed mixture. Finally, the orthogonal test was carried out to study the influence of the movement parameters of each structure on the cleaning rate and the rate of undepurated, and the weight matrix method was used to optimize it. The results indicate that under the condition the rotating speed of the threshing cylinder 750 rpm, the concave clearance 20 mm, and the feeding rate 1.4 kg/s, the threshing performance of the flexible threshing unit was the best. At this time, the breaking rate was 0.064%, and the un-threshing rate was 0.67%, which both met the relevant industry standards.

Optimization Design and Experiment of Ear-Picking and Threshing Devices of Corn Plot Kernel Harvester

In order to solve the problems of easy-to-break kernels and substantial harvest losses during kernel harvesting in breeding trials plot of corn, an ear-picking device and a threshing device of corn plot kernel harvester has been optimized. To automatically change the gap of the ear-picking plate, a self-elastic structure with compression spring and connecting rod is used. The ear-picking plate is glued, and an elastic rubber gasket is placed underneath it, which effectively improves the adaptability of the ear-picking device and reduces corn kernel collision damage during ear-picking. To ensure the self-purification of the ear-picking device, a combination of auger sieve hole cleaning device and lateral pneumatic auxiliary cleaning system is used. A dual-axial flow threshing device is designed, which uses a “U”-shaped conveying system to transport maize ears in the threshing chamber. The spacing of the concave sieve may be adjusted, and the residual kernels in the threshing chamber can be cleaned up after harvesting one plot by combining three cleanings, which meets the requirements of no mixing between plots. The force analysis of corn ears in the threshing chamber determines the best design plan for the forward speed, the speed of the second threshing drum, and the threshing gap. The breakage rate and non-threshing rate regression models were created using the quadratic regression orthogonal combination test, and the parameters were optimized using MATLAB. The verification test results showed that when the forward speed was 0.61 m/s, the second threshing drum speed was 500 r/min, and the threshing gap was 40 mm, the breakage rate was 1.47%, and the non-threshing rate was 0.89%, which met the kernel harvesting requirements in corn plots.

Kinetic and Microhydrodynamic Modeling of Fenofibrate Nanosuspension Production in a Wet Stirred Media Mill

This study examined the impact of stirrer speed and bead material loading on fenofibrate particle breakage during wet stirred media milling (WSMM) via three kinetic models and a microhydrodynamic model. Evolution of median particle size was tracked via laser diffraction during WSMM operating at 3000–4000 rpm with 35–50% (v/v) concentration of polystyrene or zirconia beads. Additional experiments were performed at the center points of the above conditions, as well as outside the range of these conditions, in order to test the predictive capability of the models. First-order, nth-order, and warped-time kinetic models were fitted to the data. Main effects plots helped to visualize the influence of the milling variables on the breakage kinetics and microhydrodynamic parameters. A subset selection algorithm was used along with a multiple linear regression model (MLRM) to delineate how the breakage rate constant k was affected by the microhydrodynamic parameters. As a comparison, a purely empirical correlation for k was also developed in terms of the process/bead parameters. The nth-order model was found to be the best model to describe the temporal evolution; nearly second-order kinetics (n ≅ 2) was observed. When the process was operated at a higher stirrer speed and/or higher loading with zirconia beads as opposed to polystyrene beads, the breakage occurred faster. A statistically significant (p-value ≤ 0.01) MLRM of three microhydrodynamic parameters explained the variation in the breakage rate constant best (R2 ≥ 0.99). Not only do the models and the nth-order kinetic–microhydrodynamic correlation enable deeper process understanding toward developing a WSMM process with reduced cycle time, but they also provide good predictive capability, while outperforming the purely empirical correlation.

Integrated Design and Evaluation of a Soil-Covering and Film-Mulching Device for Sugarcane Transverse Planters

To solve the problem that the covering device of sugarcane cannot be adequate for the agronomic standards of seed cane setts planting, a soil-covering and film-mulching device for sugarcane transverse planting was designed. The device includes a soil-covering part, soil-compacting part, and film-mulching part. Through theoretical analysis of key components, the factors affecting the cane seed covering quality for the device were obtained. A quadratic orthogonal rotation regression test was conducted by a homemade prototype to explore the effects of disk diameter, central distance, disk depth in soil, and dip angle on soil covering thickness. The results showed that the above factors all have an extremely significant effect on the soil covering thickness, and the effect degree of each factor from high to low is central distance, disk depth in soil, dip angle, and disk diameter within the range of test parameters. The optimal parameter combination, with the disk diameter, the dip angle, the central distance, the disk depth in soil, and the diameter of the soil-compacting wheel being 304.7 mm, 55.1°, 386.5 mm, 32.4 mm, and 300 mm, respectively, was obtained by Design-Expert software and verified by comprehensive field tests. The results showed that the covering thickness is in the range of 94–111 mm, the average value is 102.6 mm, and the breakage rate is no more than 2.6%. The emergence rate is 86.4%, which is an improvement of 9.3% over that of a traditional covering device. The results suggested that the device can conform to the agricultural covering standard of sugarcane planting and provide a design basis for the application and popularization of the soil-covering and film-mulching device.

A study on detection of roving tension and fine control of yarn breakage

The fine control of yarn breakage is essential for the production of better yarn quality by reducing the tension fluctuationof roving. The detection of roving tension provides important information regarding the yarn formation during spinning.In the present work, we developed a device for roving-tension detection and regulation, which greatly reduces the yarnbreakage rate and improves the production efficiency of ring spinning. By analysing the factors affecting the rovingtensions, we used a signal acquisition system in conjunction with the tension detection device to regulate the spindlerotate speed to realize the fine control of yarn breakage. Our results indicate that the proposed method can ensure auniform spinning tension of the yarn in ring spinning, which significantly reduces the yarn breakage rate, and boost theyarn production. Our work paves the way toward the rational production of high-quality yarn

Damage evaluation of a PCCP joint with a localized soil void and broken wires

During the service life of a pipeline, the surrounding soil may erode locally around the pipe due to seepage and leakage, making the pipe partially unsupported and weakening the pipe–soil interaction. The presence of soil voids provides the possibility for broken wires and further accelerates damage. In this paper, the stress and strain of PCCP joint in service under a localized soil void and with broken wires were investigated using the general finite element software ABAQUS, and the structural damage of the pipe joint under superimposed defects was evaluated. The numerical model contained two PCCP segments, a flexible joint and the surrounding soil. The preliminary study suggests that the superimposed defects of a soil void and broken wires can cause increased damage to the PCCP joint. With the addition of the soil void, the micro cracks of both the concrete core and mortar coating transform into visible cracks, and the relative wire breakage rate with coupling defects is reduced by approximately 36% to reach the elastic limit state of the pipe. The findings of this research highlight the importance of good pipe–soil interactions and could provide a theoretical reference for damage assessment and further repair strategies.

Development and Testing of a Cam Disc Comb-Type Picking Machine for Chrysanthemum (Dendranthema morifolium Ramat. Tzvelev)

HighlightsA practical cam disc comb-type chrysanthemum picking machine was developed.A three-dimensional model of the picking machine was designed in SolidWorks.The working principle and motion trajectory of the picking comb teeth were analyzed.The best working parameters of the picking machine were obtained with field tests.Abstract. Aiming at the problems of labor, picking efficiency, and mechanization, a small practical cam disc comb-type chrysanthemum picking machine was designed. The picking machine, mainly composed of a wheeled frame, power transmission system, cam disc, picking comb, and cleaning comb sleeve, uses the pulling force of comb teeth to pick chrysanthemum flowers. The comb teeth rotate on a central shaft, and their swing angle is determined by a groove on the cam disc. One rotation of the comb teeth completes the process of picking, lifting, and unloading. In this study, the parameters of the cam profile were designed using an analytical method. To ensure reliability of the components, the trajectory of the comb teeth and their structure and motion parameters were analyzed, and the conditions for picking chrysanthemums were determined. The physical parameters of chrysanthemum plants were measured, and a prototype picking machine was built. Field tests were conducted using the comb rotational speed, comb teeth spacing, and comb working depth as the test factors and the picking rate, impurity rate, breakage rate, and drop rate as the evaluation indexes. The effects of each factor and the interaction of any two factors on the picking effectiveness were obtained. The test results suggested that the most effective harvesting was achieved when the comb rotational speed was 40 rpm, the comb teeth spacing was 8 mm, and the comb working depth was 200 mm. With these parameters, the picking rate was 93.28%, the breakage rate was 1.21%, the impurity rate was 8.38%, and the drop rate was 6.61%. The prototype machine achieved good picking effectiveness, and this study provides a technical foundation for the realization of mechanized chrysanthemum harvesting. Keywords: Cam, Chrysanthemum, Comb teeth, Motion track, Picking machine.

The Horseshoe whip snake (Hemorrhois hippocrepis) on Ibiza: predator release in an invasive population

The key to fighting a biological invasion may lie in understanding every variable that can explain its success. The Enemy Release Hypothesis (ERH) states that when an invader arrives to a new environment, the absence of its common enemies (predators, parasites and competitors) facilitates the invasion success. The Horseshoe whip snake (Hemorrhois hippocrepis) has been recently introduced from the Iberian Peninsula to the island of Ibiza, and it is currently threatening the only endemic vertebrate, the Ibiza wall lizard (Podarcis pityusensis). We hypothesized that the snake invasion success is caused by the absence of natural predators, and we checked the ERH by relating the tail breakage rate to predation pressure. The invasive population showed a much lower incidence of tail breakage than the source population, which is in agreement with the almost absence of snake predators among the Ibizan reduced and naïve native vertebrate community. These results confirm the ERH, and support the prolongation of invasive snake trapping campaigns.