As a key component of a drip irrigation system, the performance of the drip irrigation emitters is mainly determined by the flow channel structures and structural parameters. In this study, a novel type of circular water-retaining labyrinth channel (CWRLC) structure emitter was proposed, inspired by the effect of roundabouts that make vehicles slow down and turn. Using the single-factor experiment method, the influence of the hydraulic performance of CWRLC emitters was researched under different circular radii. The internal flow characteristics and energy dissipation mechanism were analyzed by a computational fluid dynamics (CFD) simulation. It can be seen from the analysis that the energy dissipation abilities of the flow channel depend on the proportion of low-speed vortex areas. The larger the proportion of low-speed vortex areas, the smaller the flow index of the CWRLC emitter. Quadrate water-retaining labyrinth channel (QWRLC) and stellate water-retaining labyrinth channel (SWRLC) structures were obtained by structural improvements for increasing the proportion of low-speed vortex areas. The simulation results showed that the flow indexes of two improved structural emitters were significantly decreased. CWRLC, QWRLC, SWRLC, and widely used tooth labyrinth channel (TLC) emitters were manufactured by using technologies of electrical discharge machining (EDM) and injection molding (IM). The physical test results showed that the SWRLC emitter achieved the best hydraulic performance compared with the other three emitters. Therefore, the SWRLC emitter has a broad prospect of application in water-saving irrigation.

Torque ripple in a brushless DC motor (BLDCM) seriously restricts its application in high-performance fields. This paper proposes a commutation torque ripple suppression strategy based on a Zeta converter. The expected output voltage of a Zeta converter that suppresses the commutation torque ripple is obtained, according to the effect of the duty ratio of the Zeta converter on the turn-off phase freewheeling duration and the turn-on phase rising duration, during commutation. Based on the analysis of the dynamic response of the Zeta converter, the Zeta converter is adjusted to ensure that the Zeta converter reaches stability in sufficient time. During the commutation, the output voltage of the Zeta converter is connected to the main circuit to reduce the torque ripple during commutation, and the expected regulated duty cycle of the Zeta converter during the next commutation is calculated to adjust the output voltage of the Zeta converter. Based on this analysis, the experimental results verify the effectiveness of the proposed method.

Drip irrigation system performance is largely governed by emitter hydraulic characteristics. This study systematically compares the hydraulic performance of a novel cylindrical asteroid-shaped channel emitter against a conventional toothed labyrinth design. Standardized specimens were produced using precision molds and integrated into drip tapes at 300 mm spacing. To comprehensively analyze flow behavior, pressure–discharge relationships, flow indices, and internal flow fields, a combination of physical experiments and CFD simulations was employed. Experimental results showed that across 20–200 kPa, the cylindrical asteroid-shaped emitter delivered flow rates 24–28% higher than the labyrinth type while maintaining a lower flow index, demonstrating enhanced hydraulic stability. Flow field analysis at 100 kPa revealed that the divergent asteroid geometry generates more intense and sustained turbulent kinetic energy throughout the channel units, resulting in superior energy dissipation. The cylindrical asteroid-shaped unit achieved a pressure drop of 17.5 kPa, exceeding the 15.3 kPa observed in the labyrinth channel, with outlet velocities of 1.6 m/s versus 1.76 m/s. Additionally, the flow pattern promotes comprehensive wall scouring through large-scale vortices, indicating improved resistance to clogging. These findings validate the design superiority of the cylindrical asteroid-shaped emitter and offer a theoretical reference for developing high-uniformity, water-saving irrigation devices.

Thermoelectric generators are high-profile energy conversion devices that can convert heat energy into electricity. In this study, a novel 1D resistance model was established to evaluate the performance of a segmented thermoelectric generator (STEG) with variable properties, and the genetic algorithm was adopted to optimize the performance. Then, influence factor analysis, multi-parameter optimization, and sensitivity analysis for an STEG couple were conducted. The results showed the great influence of geometric sizes on performance. Moreover, the optimal length ratio between the length of the high-temperature segment and the total leg length increased when the temperature difference (ΔT) was raised, but it remained unchanged as the convective heat transfer coefficient (h) changed. Furthermore, the ratio of the leg length to its cross-sectional area is affected by thermal conditions and the length ratio, while the cross-sectional area ratio between P- and N-type thermoelectric legs was not affected by the convective heat transfer coefficient. Under the conditions of ΔT = 300 K and h = 2000 W/m²K, the maximum power increased by 11.02%. Finally, the global sensitivity analysis found that material properties, especially the Seebeck coefficient, dominate the influence on optimal power. These results could contribute to the optimal design of STEGs.

How suspended grains traverse energy-dissipating micro-passages determines whether sediment-laden water can be used without rapid emitter deterioration. A novel cylindrical asteroid-shaped drip emitter was investigated through laboratory anti-clogging tests and two-way coupled computational fluid dynamics–discrete element method (CFD–DEM) simulations. The laboratory tests comprised 20 intermittent irrigation cycles at five pressures ranging from 60 to 140 kPa, with relative discharge used to characterize hydraulic performance. The simulations tracked particle motion, wall collisions, and mass transmission over a 0.20 s observation window to examine the effects of operating pressure, injected particle mass, and flow-path radius. Numerical cases isolated hydraulic forcing and, at 100 kPa, changes in solids dose and cavity radius. Measured discharge retention occupied a narrow 96.45–97.83% interval, whereas the fraction of particulate mass leaving the domain spanned 81.3–92.7%. Despite representing different responses, both indices followed pressure in a closely associated manner (Pearson r = 0.975, p = 0.0046). Stronger forcing extended the high-speed portion of individual trajectories and brought the final wall contacts forward in time, although contact totals did not follow a monotonic sequence. Changing the dose between 1.0 and 2.0 × 10⁻⁶ kg altered the selected upper-speed statistics by only +1.8% and −2.1% but reshaped the contact histories. Expanding the radius from 0.65 to 0.85 mm produced much larger reductions of 28.1% and 91.3%; the latter record then showed sustained near-stagnation with relatively few impacts. Thus, low collision frequency cannot independently demonstrate effective sediment passage. Combining effluent mass balance with trajectory and contact information provides a mechanistic basis for diagnosing retention in irrigation microchannels.