Search Results (7)

Spiral separators commonly face the issue of particle misplacement during fine particle separation, which severely limits separation accuracy. This study employs a coupled CFD-DEM numerical simulation method to systematically investigate the influence mechanism of transverse inclination angle (10°, 15°, 20°) on particle moving behavior. The results show that the separation process exhibits distinct stage characteristics, which can be divided into an initial stage (first 1/3 turn), a transition stage (1/3 to 2 turns), and a quasi-steady stage (after 2 turns). A steeper angle (20°) optimizes the flow field, reducing the inner low-velocity zone and widening the high-velocity core, which promotes inward migration of particles. This enhances the enrichment of high-density particles while effectively suppressing their mixing into the clean coal product at the outer edge. For difficult-to-separate fine particles below 0.1 mm, although complete separation is challenging, increasing the transverse inclination angle still shows a clear reduction in the misplacement of high-density particles, providing a controllable approach for improving the quality of the outer edge product. This study offers theoretical insights and design guidance for optimizing spiral separator structures and enhancing fine coal separation efficiency. Full article

The dynamic migration of mineral particles within spiral separators and its control via structural parameters are not yet fully understood, hindering efficiency improvements. To this end, a set of spiral separators with systematically adjusted structural parameters was designed. Extensive sampling of a 1–0.25 mm coal slurry yielded 120 samples from 6 separators, across 5 turns and 4 radial streams. Sink-float analysis revealed a well-defined three-stage separation mechanism: the roughing stage involves rapid segregation of light and heavy particles, while intermediate-density particles remain widely distributed; the intensified cleaning stage governs the radial migration of intermediate-density particles while simultaneously enriching the high-density and low-density fractions; and the final cleaning stage stabilizes the particle distribution and redirects misplaced particles. The influence of key structural parameters was also quantified: the composite cross-section outperformed cubic parabolic and elliptical profiles, markedly enhancing the separation of high-density and medium-high-density particles from the lighter product; increasing the trough inclination angle significantly promoted the radial inward migration of medium-high-density particles; a reduced pitch-to-diameter ratio effectively concentrated high-density and medium-high-density particles within inner and middle regions. Based on these insights, a “process intensification” strategy was proposed and materialized in a novel spiral separator design featuring stage-optimized, multi-parameter coordination. Performance evaluation demonstrated a separation efficiency of 94.74% under equivalent product quality constraints, a substantial improvement over conventional design. This work provides a fundamental, stage-specific understanding of particle separation dynamics and establishes a practical basis for the advanced design of high-efficiency spiral separation systems. Full article

Objectives: The injection of bioactive compounds into the delicate urethral sphincter muscle to facilitate sphincter regeneration in incontinent patients poses a surgical challenge. In previous preclinical animal studies, approximately half of the 96 pigs treated by transurethral needle injection exhibited misplaced cells or cell loss. We, therefore, investigated whether pressure-controlled waterjet injections delivered nano- and microparticles or liquids more precisely in the urethra and without a risk of full penetration. Methods: Fresh cadaveric urethrae were prepared from 12 female pigs. Nano- and microparticles or liquids were injected by waterjet in a proximal (i.e., H5) and distal (i.e., H10) position of the urethral tissue samples employing waterjet pressures of effect 40 (E40), E60, and E80. The injection depths and widths were investigated by histochemistry. Results: E40 injections were not sufficient to inject particles into the tissue, while E60 and E80 injections delivered the components into the urethral mucosa, submucosa and close to the urethral muscle. However, employing E80 increased the risk of full penetration of the urethrae. Significant differences in injection depth were not observed between nano- and microparticles. Liquids, however, penetrated the tissue somewhat deeper. Using the optimised pressure protocols facilitated the injection of cells by a novel waterjet prototype with excellent viability into capture fluid. Conclusions: Target-specific and pressure-controlled waterjet injections deliver liquids and particles with high precision in the urethra. For future injections of bioactive components, including cells, waterjet injections into the urethrae of incontinent pigs with a pressure of E60 are most promising to investigate the efficacy of regenerative therapies in animal models of urinary incontinence and other diseases or malfunctions. Full article

Hydrocyclones can be used to concentrate the entrained sands in sewage and alleviate the clogging and erosion of the drainage network, but in practical application, there are problems such as low concentrations of underflow and a high content of fine particles, which cause a significant load on the subsequent sand dewatering and recycling. This paper designs five spigot structures of hydrocyclones and investigates the separation performance by numerical simulation, aiming to improve the applicability of hydrocyclones in the sewage treatment process by optimizing the spigot structure. The research results show that a large cone spigot delays the external downward swirling flow and reduces fine particle content in the underflow, but its effective separation space is reduced, and the turbulence in the cone section area is more intensive, which influences the separation accuracy. An elongated spigot has a reduced underflow water distribution; fine particles are more enriched in the internal swirling flow, and the underflow recoveries of 1 μm and 5 μm particles drop by 2.34% and 2.31%. The spigot structure affects the downward fluid and air intake states; complicated spigot structures contribute to increasing the resistance of particle discharge through underflow, alleviating fine particle misplacement. Full article

Due to the lack of water resources, the main agricultural planting method used in the northwest region of China is plastic film mulching, with precision hole sowing performed on the film after mulching. However, conventional hole-forming devices damage the compactness of the soil hole while moving on the plastic film, causing seed misplacement. Therefore, this study designed a bionic hole-forming device based on the oriental mole cricket. In order to explore the interaction between the hole-forming device and the soil, a typical soil discrete element particle model was established, and its contact parameters were calibrated. An experiment was conducted to compare the performance of the bionic hole-forming device with a conventional device using discrete element method and multi-body dynamics (DEM-MBD) coupled simulations. The results revealed that the bionic hole-forming device caused less soil disturbance during the hole-forming process and could reduce the sowing operation resistance compared to the traditional device. Compared to traditional square and cone-shaped hole-forming devices, the soil resistance of the bionic hole-forming device was the smallest, at 7.51 N. This work provides a reference for the optimization of hole-forming devices for plastic film sowing. Full article

The pitch-diameter ratio is an important design indicator affecting the separation performance of spirals. Based on the numerical simulation method, this paper systematically investigated the variation of flow hydrodynamic parameters in the spiral concentrator with the regulation of the pitch-diameter ratio. The radial distribution and variation trend of hematite and quartz particles with different particle sizes are further analyzed. Additionally, the separation indices of hematite and quartz with different particle size combinations were predicted. The results show that the tangential velocity, maximum radial velocity, velocity shear rate, and Reynolds number of fluid in each region decrease with the increase of the pitch-diameter ratio. The range of laminar flow gradually expands as the pitch-diameter ratio increases. There are significant differences in depth of water, ratio of inward and outward flows, and secondary flow velocity in different regions. Some flow hydrodynamic parameters at the inner trough reach relative equilibrium at a pitch-diameter ratio of 0.675. Hematite and quartz particles form a selective distribution in the trough surface, which comprehensively reflects the density effect, particle size effect, following flow effect of fine particles, and the effect of interstitial trickling of high-density fine particles. Fine hematite and coarse quartz form a large amount of misplaced material, and there is a corresponding mixing area. With the increase in pitch-diameter ratio, coarse and fine hematite particles migrate inward and outward, respectively. With the increase in pitch-diameter ratio, the misplaced amount of quartz on the inner trough decreases, but the outward migration distance of coarse quartz is smaller. Increasing the pitch-diameter ratio is beneficial to the separation of combined feedings of coarse hematite and quartz but unfavorable to that of fine hematite and quartz. The maximum separation efficiency of coarse hematite and fine quartz can reach 85.74%, and the iron grade of the inner product can reach 65.96% when the pitch-diameter ratio is 0.675 and the splitter location is 115 mm. The changing trend of separation indices in this feeding is closely related to the variation of fluid parameters and the change in the radial distribution of single mineral particles. The research results can provide references for the structural design of spirals, the selection of feed particle size, and the adjustment of splitter location. Full article

In this paper, a new optimization algorithm called motion-encoded electric charged particles optimization (ECPO-ME) is developed to find moving targets using unmanned aerial vehicles (UAV). The algorithm is based on the combination of the ECPO (i.e., the base algorithm) with the ME mechanism. This study is directly applicable to a real-world scenario, for instance the movement of a misplaced animal can be detected and subsequently its location can be transmitted to its caretaker. Using Bayesian theory, finding the location of a moving target is formulated as an optimization problem wherein the objective function is to maximize the probability of detecting the target. In the proposed ECPO-ME algorithm, the search trajectory is encoded as a series of UAV motion paths. These paths evolve in each iteration of the ECPO-ME algorithm. The performance of the algorithm is tested for six different scenarios with different characteristics. A statistical analysis is carried out to compare the results obtained from ECPO-ME with other well-known metaheuristics, widely used for benchmarking studies. The results found show that the ECPO-ME has great potential in finding moving targets, since it outperforms the base algorithm (i.e., ECPO) by as much as 2.16%, 5.26%, 7.17%, 14.72%, 0.79% and 3.38% for the investigated scenarios, respectively. Full article