Drum Speed Research Articles

RAP chunks produced in cold milling operation of asphalt pavement: Evaluation, mechanism, and engineering investigation in China

Cold milling is a widely used method for rehabilitating asphalt pavement, generating reclaimed asphalt pavement (RAP) chunks. Within this process, aggregates within the asphalt pavement will be crushed, forming RAP agglomerates and aggregate breakdown. However, the mechanism of these phenomena has remained unclear, and a unified evaluation method has yet to be established. In this study, RAP agglomeration and aggregate fragmentation were characterized, five distinct methods were systematically assessed, and the mechanism of RAP agglomeration and breakdown was analyzed by discrete element method (DEM) simulation based on setting different particle contact parameters, then followed by a mechanical analysis, and demonstrated in engineering. The results revealed that both agglomeration and aggregate breakdown occur within RAP particles of various sizes, with the five methods showing similar trends in quantifying these effects. Through DEM simulations and mechanical analyses, the aggregate breakdown predominantly occurs at the cutter's motion trajectory of the cutter and during crack propagation, while agglomeration was mainly related to the sliding surface's area. The milling speed and depth positively impact RAP agglomeration, while negatively affecting aggregate breakdown, and milling drum speed exerts minimal influence on these phenomena. RAP agglomeration varies considerably in different engineering projects, and cold milling parameters should be determined based on the material composition of the asphalt pavement and design requirements to control agglomeration and breakdown rates of RAP.

Dynamic diffusion characteristics of airflow and coal dust during the mining process based on MRF: A numerical simulation study

Turbulence generated by rotation of shearer has a great impact on the distribution of dust. The MRF method of multiple reference frame was employed to simulate airflow and dust distribution during mining process. The distribution of cutting dust under different airflow velocities, cutting speeds, and cutting direction (against or follow the direction of airflow) were compared and analyzed. Results show that the generated cutting dust using MRF method tends to move horizontally and vertically. As the speed of airflow increases, vertical characteristics diminish. Simultaneously, horizontal dissipation rises with the deviation of airflow speed. The increase of rotational speed augments the distance covered by cutting airflow, including vertical offset and windward motion. Moreover, the elevated drum speed amplifies airflow speed in the sidewalk and the primary influence range is approximately 80 m. When cutting in the downwind direction, the airflow exhibits a pronounced vertical and horizontal offset behind the drum. Conversely, when cutting in the upwind direction, these characteristics are less evident, resulting in a more uniform spatial distribution of cutting dust in the downwind direction. The majority of dust generated when cutting against the airflow tends to move in the low-altitude area, contributing to a more disordered pattern.

Comparison of simplex and duplex drum brakes linings with transverse slots in vehicles

In this paper, experimental comparison between Simplex and Duplex drum brake units performance for three different drum lining profile designs is carried out. The three linings profiles are normal (no slot), with one slot and with three slots. In this study, brake test rig has been designed to represent the actual braking process environment. Brake oil pressure and drum speed are the operational parameters that are varied during the experimental work. From the experimental work and mathematical models for brake force, brake factor, and final friction temperature, the comparisons were carried out. The final conclusions indicate that lining with one slot profile is the most suitable, since the percentage improvement of mean brake force and brake factor of duplex drum brake (D) linings versus simplex drum brake (S) linings reaching 84.09% and 82.73% higher than three slots lining profile but lower than lining with normal profile at low pressure 5 bar and low speed 50 rpm. Also, the percentage improvement of mean primary shoe final friction temperature reduction for the one slot profile reaches 30.00% higher than normal lining profile but lower than lining with three slots profile at high pressure 20 bar and drum speed 50 rpm.

A machine learning-driven modeling and optimization approach for enhancing cassava mash production quality in cassava graters

Machine performance modeling and optimization have emerged as crucial steps for process enhancement and efficiency. This study explored machine learning to model and optimize the cassava grating chamber of cassava grater for the quality production of gari. This domain remains unexplored thus far. A total of 196 graters were studied. Key variables studied included tooth diameter (TD), tooth height (TH), inter-tooth spacing (ITS), drum speed (DS), clearance (C), and moisture content of cassava (MC). Geometric mean diameter (GMD) represented mash quality. Feature importance rankings emphasized TH (0.488784), C (0.243284), TD (0.112682), ITS (0.103547), DS (0.036261), and MC (0.015442) in determining particle size (GMD) of grated mash. Machine learning models efficiently interpreted these attributes, including gradient boost regressor, linear regression, neural network, and random forest. The Gradient boost regressor was the best predictive model achieving 95.34 % accuracy, RMSE (0.3291), and MAE (0.2303). The study provides a GMD predictive equation and optimized parameters for specific gari sizes production, offering valuable insights for tailored machinery in the cassava grating activity.

Research on the Collection Characteristics of a Hydraulic Collector for Seafloor Massive Sulfides

Ore collection is very important in deep-sea mining for seafloor massive sulfide (SMS). In view of the characteristics of SMS ores produced by mechanical crushing, which contain coarse particles and a wide particle size distribution, in-depth research on the collection process with a device combining a rotary crushing head and a flat suction mouth was conducted. In this paper, solid–liquid two-phase flow in the hydraulic collection process with a drum rotation is carried out using the computational fluid dynamics-discrete element method (CFD-DEM), and the flow field characteristics and particle motion characteristics are analyzed. The results indicate that particles with a maximum diameter of 20 mm can be effectively collected when the suction velocity is 3 m/s. The collection process of SMS mainly goes through three stages: particle disturbance start-up, partial particle influx, and stable collection. In addition, the appropriate drum speed facilitates the collection of SMS ore. Finally, the correctness of the numerical method was assessed using similarity experiments. This work can be used to guide the design of underwater mining equipment.

Effects of washing on structural parameters of medical compression stockings

PurposeThis study aims to evaluate how the structure of medical compression stockings, including three compression levels and five cross-sections from the ankle to the thigh part, will be changed after washing in different conditions and further investigate the effect of the washing parameters on the medical compression stockings.Design/methodology/approachBy washing medical compression stockings in different conditions and measuring the structures (including the density, the girth, the transversal and lengthwise dimension, the weight per unit area and the thickness) of medical compression stockings from the knee to the thigh part.FindingsIt was concluded that the density, the weight per unit and the thickness increase and the girth, the transversal and lengthwise dimension, the weight per unit and the thickness decrease. The change degree of Class one and Class two is greater than Class 3. Moreover, the washing temperature is the most significant factor affecting all the structures of medical compression stockings. Meanwhile, the mechanical actions of the washing machine, like drum speed and washing time, also influence different medical compression stockings structures to different degrees.Research limitations/implicationsThe washing parameter not only includes the temperature and washing cycles but also has other factors, such as the drum speed and washing time. In addition, different kinds of factors will be influenced by each other.Originality/valueThis study can provide consumers advices on the washing of medical compression stockings, and attribute to the optimization of materials and structures to maintain its properties for manufacturers.

Integrated design and optimization of a conceptual double drum dryer for drying of wheat flour slurry: Experimental validation and computational analysis

AbstractThis study presents a novel conceptual laboratory‐scale double drum dryer (LDD) optimized for the efficient drying of wheat flour slurry into flakes. The research stems from the need to address the complexities of previous methodologies, lack of studies on industrial‐sized dryers, and high cost. The methodology involved designing dryer components, transmission system, creating engineering drawings, and simulating LDD with varied operating parameters. Verification was done using industrial double drum dryer (IGD) data and MATLAB simulations. Parameters were explored including temperature (120–140°C), drum dimension (0.1–0.7 m), and film thickness (0.3–0.6 mm). The design closely matched real‐world performance metrics with mean relative deviations of 2.67%, 3.30%, 10.12% for drum speed, water content, and throughput respectively. The predictive model outperformed the IGD, achieving a 9.13% increase in throughput. Optimal LDD parameters were identified 0.7 m length, 0.2 m diameter, 0.3 mm film thickness, 40% slurry TSS, 120°C temperature, and 4.47 rpm rotational speed, resulting in 3.00% water content and 132.78 kgh−1 throughput offering valuable insights for similar applications in the food industries.Practical applicationsThe research on the novel laboratory‐scale double drum dryer for drying wheat flour‐based slurry holds significant practical implications in the food industry. Firstly, the optimized design and simulation‐based approach offer a cost‐effective and efficient solution for small‐scale food processing businesses aiming to produce wheat flour flakes. By identifying optimal drying parameters, including temperature, drum dimensions, and film thickness, the research enables precise control over the drying process, leading to enhanced product quality and throughput. Moreover, the close agreement between simulation results and industrial observations validates the effectiveness of the proposed methodology, instilling confidence in its practical applicability. The development of a prototype based on these findings facilitates the adoption of this technology by small‐scale enterprises, empowering them to improve their production processes and competitiveness. Overall, this research contributes to advancing drying technology in the food industry, offering tangible benefits in terms of product quality, efficiency, and operational cost reduction.

纵轴流玉米锥形脱粒装置优化设计与仿真分析

Aiming at the high crushing rate and impurity rate of corn kernel machine harvesting in the Huanghuaihai region, a longitudinal flow conical variable pitch threshing device is designed, which adopts the combined threshing element of "plate teeth + ribs" and the combined threshing concave plate of "leftward round tube type + vertical round tube type". The cob model was established, and the force analysis of the cob threshing process was carried out, and the type of threshing drum and the installation angle of the threshing concave plate round tube were determined as the main influencing factors, and the collision force on the corn cob was taken as the test index. Using EDEM discrete element simulation software, simulation tests were carried out on different types of threshing drums and threshing concave plates with different installation angles of round tubes with corn cobs, and the better threshing method was finally determined: a conical threshing drum at a drum speed of 450 r/min, and a combination of left-facing round-tube-type+vertical round-tube-type threshing concave plates with an installation angle of 10° (front-sparse and back-dense type) were used. Compared with the vertical circular tube type threshing concave plate, the corn cob contact force decreased from 313.5N to 247.3N, which was optimal for threshing in the range allowed by the corn kernel destructive force.

Demonstrating autonomous controls on hardware test beds is a necessity for successful missions to Mars and beyond

NASA and the Department of Defense are planning for a mission to Mars in the 2030s–2040s using nuclear thermal propulsion (NTP). NTP uses a nuclear reactor to heat flowing hydrogen and create thrust. A serious concern for crewed and uncrewed missions to Mars is the loss of reactor control. The reactor startup and initial rocket impulse are initiated in cislunar or near-earth orbital regions; therefore, radio communications between ground control and the NTP engine should occur in real time. However, radio communications can take more than 20 min, depending on planet positions, to reach Mars orbiters from ground control. To address this delay, local autonomous controls are implemented onboard the NTP engine to ensure acceptable operation. However, autonomous controls have not been demonstrated or implemented in research or power reactor contexts because of safety and reliability concerns. To enable autonomous controls development, demonstration, and validation, Oak Ridge National Laboratory has created a nonnuclear hardware-in-the-loop test bed. Sensors throughout the test bed relay system status and hardware response to the user control algorithm, including measurements of temperature, flow, pressure of a loop, control drum position, and drum speed. This paper discusses the development of this facility and user accessibility.

The Influence of the Distribution Law and Uniformity of a Threshed Mixture with the Working Parameters of a Soybean Threshing Device

Soybean plants cultivated using mulched drip irrigation planting technology have the following characteristics during the harvest period: green stems and leaves, and a high straw/grain ratio. Moreover, the threshing device of a soybean combine harvester is difficult to adapt to, resulting in an increase in the accumulation and unevenness of the threshed mixture. This leads to an increase in impurity content and the loss rate. We conducted a single-factor experiment on a self-developed longitudinal/axial-flow soybean threshing and separation test bench, employing drum speed, feeding rate, and threshing clearance as experimental factors. The influence of the soybean threshing and separation device’s working parameters on the distribution and uniformity of the threshed mixture in the axial and radial directions of the drum was explored through experiments. The results showed that the mass of the threshed mixture and soybean seeds showed a trend of first rapidly increasing and then slowly decreasing in the axial direction of the drum. Additionally, the mass showed a distribution feature of large values on both sides and small values in the middle in the radial direction. A lower drum speed, greater threshing clearance, and a smaller feeding rate make the radial distribution of a threshed mixture more uniform. Based on the combination of the crushing rate and unthreshed rate, the optimal working parameter combination was determined to be as follows: a drum speed of 500 r/min, a feeding rate of 6 kg/s, and a threshing clearance of 25 mm. The findings of this research offer valuable insights for the structural optimization and design enhancement of threshing and cleaning mechanisms within soybean combine harvesters.

Enhancing high-speed EDM performance of hybrid aluminium matrix composite by genetic algorithm integrated neural network optimization

Hybrid aluminium matrix composites (HAMCs) are highly valued in manufacturing sectors but are difficult to machine conventionally due to reinforcements' inherent hardness and abrasiveness. This research finds high-speed wire electric discharge machining (WEDM) to be a potent solution for machining stir-squeeze-casted HAMC (AA2024 with ceramic nanoparticles: Al2O3, SiC, Si3N4, BN) and creating complex profiles with superior erosion characteristics. The erosion performance has been assessed in terms of material removal rate (MRR) for different profiles (plane, angular, and curve), and wire wear ratio (WWR) by employing machining variables, i.e., pulse voltage (PV), pulse current (PI), wire feed rate (WFR), pulse (P), and drum speed (DS). Results revealed that MRR_curve has highest MRR (37.84 mm3/min), followed by MRR_angular (36.07 mm3/min) and MRR_plane (34.40 mm3/min). The lowest WWR (0.0094%) was achieved at lower magnitudes of machining variables. The microscopic observations unveil shallow craters, minute-sized melt redeposits, and micro-pores on machined surface under the conditions of PV = 90 V, PI = 2 A, WFR = 13 m/min, P = 20 mu, and DS = 40 Hz. Optimization using non-dominated-sorting-genetic algorithm (NSGA-II) resulted in significant enhancements of 75.37, 73.90, and 76.01% in MRR_plane, MRR_angular, and MRR_curve, respectively, and a depreciation of 16.50% in WWR.

Optimization and Prediction of Operational Parameters for Enhanced Efficiency of a Chickpea Peeling Machine

Chickpeas hold significant nutritional and cultural importance, being a rich source of protein, fiber, and essential vitamins and minerals. They are a staple ingredient in various cuisines worldwide. Peeling chickpeas is considered a crucial pre-consumption operation due to the undesirability of peels for some uses. This study aimed to design, test, and evaluate a small chickpea seed peeling machine. The peeling prototype was designed in accordance with the chickpeas’ measured properties; the seeds’ moisture content was determined to be 6.96% (d.b.). The prototype was examined under four different levels of drum revolving speeds (100, 200, 300, and 400 rpm), and three different numbers of brush peeling rows. The prototype was tested with rotors of four, eight, and twelve rows of brushes. The evaluation of the chickpea peeling machine encompassed several parameters, including the machine’s throughput (kg/h), energy consumption (kW), broken seeds percentage (%), unpeeled seeds percentage (%), and peeling efficiency (%). The obtained results revealed that the peeling machine throughput (kg/h) exhibited an upward trend with increases in the rotation speed of the peeling drum. Meanwhile, the throughput decreased as the number of peeling brushes installed on the roller increased. The highest recorded productivity of 71.29 kg/h was achieved under the operational condition of 400 rpm and four peeling brush rows. At the same time, the peeling efficiency increased with the increase in both of peeling drum rotational speed and number of peeling brush rows. The highest peeling efficiency (97.2%) was recorded at the rotational speed of 400 rpm and twelve peeling brush rows. On the other hand, the lowest peeling efficiency (92.85%) was recorded at the lowest drum rotational speed (100 rpm) and number of peeling brush rows (4 rows). In the optimal operational condition, the machines achieved a throughput of 71.29 kg/h, resulting in a peeling cost of 0.001 USD per kilogram. This small-scale chickpea peeling machine is a suitable selection for small and medium producers.

Research on the mechanism of coal wall fragmentation and dust production characteristics in the perspective of differentiated discrete elements

In order to efficiently and accurately control coal dust pollution in coal mining faces, this study addresses the insufficient research on the dust generation mechanism during cutting. Firstly, a similar experimental platform for simulating coal wall cutting with a drum cutter was used to investigate the changes in coal wall fragmentation and dust generation at drum speeds of 35 r/min, 50 r/min, 65 r/min, and 80 r/min. The experimental results revealed that the degree of coal wall fragmentation and dust generation increased with the increase in rotational speed, leading to a wider range of particle size distribution and an increase in the generation of fine dust particles. A 1:1 scale discrete element simulation of coal wall cutting with a drum cutter was conducted based on the experiments. The results indicated that, under the four rotational speeds, the cracks generated during coal wall fracture were predominantly tensile cracks, accounting for over 76% of the total crack count. The total number of cracks increased from 10,600 to 11,200, the number of free single particles increased from 2555 to 2728, and the fragmentation volume increased from 0.021607 to 0.023024 m3. The range and degree of coal wall fragmentation increased with the increase in drum speed.

Performance Evaluation of Diesel Engine Operated Cassava Grating Machine

This research work was carried out to assess the performance of a diesel engine-operated cassava grating machine. The factorial design was used to conduct the experiment and the collected data were analysed using Statistix 8 software. The results of the analysis of variance revealed that the speed, feeding rate, as well as their interaction effect, were significant at the 5% level. The highest throughput capacity of 471.4 kg h-1 was observed at a speed of 1400 r min-1, at a feeding rate of 5 kg min-1, while the lowest throughput capacity was 272.5 kg h-1 observed at a speed of 1100 r min-1, at a feeding rate of 5 kg min-1. The highest grating efficiency of 97.3% was observed at a speed of 1400 r min-1, at a feeding rate of 15 kg min-1, while the lowest grating efficiency was 81.6% observed at a speed of 1100 r min-1, at a feeding rate of 5 kg min-1. The lowest percentage of mechanical loss of 2.45% was observed at a speed of 1400 r min-1, at a feeding rate of 15 kg min-1, while the highest percentage of mechanical loss was 18.4% observed at a speed of 1100 r min-1, at a feeding rate of 5 kg min-1. The fuel consumption of the machine was measured as 1.82 L h-1. Finally, the regression analysis results for throughput capacity showed that 95% of throughput capacity was recorded with both independent variables together, F (2, 33) = 311.17, R = 0.974, p = 0.000. This machine was recommended for cassava grating at an operating drum speed of 1400 r min-1.

Development and Evaluation of a Low-cost Rice Milling Machine

A low-cost rice milling machine was designed, fabricated and evaluated to reduce post-harvest loss being faced by the peasant farmers using traditional methods and to meet up with the demand for high quality and well processed rice at a cheaper and avoidable price. The machine was designed to dehusk paddy rice, separate the husk and remove unwanted foreign materials. It consists of a hopper, sheller, cleaner, separator (sieve), delivery unit and the frame. The machine operates on the principle of impact using centrifugal force. Four cylinder speeds of 400 rpm, 450 rpm, 500 rpm and 550 rpm as well as four feed weights of 1 kg, 2 kg, 3 kg and 4 kg were used for performance testing. Results of the performance evaluation carried out on the machine showed the highest milling efficiency of 88% and cleaning efficiency of 91% at a speed of 550 rpm, while the highest seed loss of 27% was obtained at a speed of 400 rpm. The effectiveness of the machine was dependent on the paddy conditions, drum speed and milling duration.

Process Investigation on Robust Electrospinning of Non-Aligned and Aligned Polyvinylidene Fluoride Nanofiber Mats for Flexible Piezoelectric Sensors.

Polyvinylidene fluoride (PVDF) nanofiber mats have played a significant role in wearable electronic devices that have been in great demand in recent decades. Although manifold PVDFbased freely stacked or well-aligned nanofiber mats created via the electrospinning process have been demonstrated to achieve multisensory capabilities with high sensitivity and long detection range, rarely have any of them proved their ability with a stable process and accurate processing parameters. In this work, we successfully developed freely stacked and well-aligned PVDF nanofiber mats with diameters ranging from micrometers to nanometers, providing stable performance for wearable electronic devices. Through in-depth investigations into material preparation, electrospinning, and fiber collection processes, we revealed the relationship between the nanofiber morphology, β-phase fraction, and piezoelectric output with various process parameters. Characterized by analytical methods, we have established a mature, reliable nanofiber mat fabrication system capable of mass-producing PVDF nanofibers with the required diameter and consistent properties. At 18 kV voltage and 60% RH humidity, the uniformity of the fiber diameter and β-phase content was maintained in a favorable range. When the drum speed increased to 2000 r/s, the fiber orientation and β-phase content increased. We assembled aligned PVDF nanofiber mats with conductive fabric in a flexible piezoelectric sensor that successfully monitored different body movements and produced an output voltage of 0.1 V. This study provides the necessary process parameters for the large-scale production of high-quality PVDF nanofiber mats and provides clear guidance for beginners in the field of nanofiber mat manufacturing.

Heat transfer studies in a rotating drum containing non-spherical particles

In chemical and pharmaceutical industries, rotating drums are commonly used as mixers, dryers, granulators, and reactors for processing particulate materials (Rutgers, 1965). Most of the earlier studies are limited to the spherical particles and have focused on understanding granular flow in drums operating under a rolling regime. However, there are numerous industrial operations in which non-spherical particles are heated in a rotating drum operating in the cascading regime. In the present work, we attempt to understand the heat transfer process between hot air and non-spherical particles in a rotating drum. Non-spherical particles, considered for the simulations, mimic pharmaceutical tablets having standard round convex (SRC) and oblong shapes. The multi-sphere approach is used to model the tablet shapes. Collisions between the tablets are captured through the interaction between candidate spheres of non-spherical particles. The focus here is to study the heat transfer between hot air and particles and the heat conduction between the particles. The effects of drum speed, particle shape, and air inlet temperature on the bed temperature distribution are investigated. Analysis of average bed temperature profiles shows that the bed temperature remains constant regardless of the drum speed but is influenced by the temperature of the incoming air. The logarithmic mean temperature is not impacted by the incoming air temperature but is influenced by particle shape. The logarithmic mean curve shows a steeper slope for SRC particles due to higher surface area-to-volume ratio and better radial mixing compared to Oblong particles

Enhancing Seed Germination and Seedlings Growth of Khao Dawk Mali 105 Rice Cultivar via Seed Coating and Infrared Drying Apparatus

Seed coating techniques had emerged as a promising approach for precise planting and safeguarding crops against environmental stresses. Simultaneously, infrared drying, renowned for its cost-effectiveness and efficiency, held promises for enhancing the quality of drying processes. This investigation delved into the procedures applied to Khao Dawk Mali 105 rice seeds during the coating and drying process using a prototype of the hexagonal drum. The results found that the drying temperature (factor B) and duration of drying time (factor C) had substantial primary effects (p ≤ 0.05), while the drum rotational speed (factor A) did not exert a noteworthy influence. Additionally, meaningful interactions were observed among the factors AB, AC, BC, and ABC. Impressively, it resulted in germination rates of 80.56 and 80.25 %, coupled with germination indices of 84.88 and 85.47 %, when utilizing a drum speed of 20 rpm, a drying temperature of 45 °C, and a drying time of 8 min (R-204508), and a drum speed of 10 rpm, a drying temperature of 45 °C, and a drying time of 8 min (R-104508), respectively. Additionally, the mean germination time amounted to 9.64 days, and the length of the rice seedling stem reached 13.66 cm when employing a drum speed of 20 rpm, a drying temperature of 50 °C, and a drying time of 8 min (R-205008). These discoveries emphasized the potential of the prototype's seed coating and infrared drying technology integration to improve rice germination and subsequent growth. This enhancement could ultimately result in higher yields and increased productivity, especially in small-scale agricultural settings. HIGHLIGHTS These discoveries emphasized the potential of the prototype's seed coating and infrared drying technology integration to improve rice germination and subsequent growth. This enhancement could ultimately result in higher yields and increased productivity, especially in small-scale agricultural settings. Ensuring precise control over drying temperature and duration is of paramount importance in establishing optimal and consistent conditions for the germination and subsequent growth of rice seeds, thereby augmenting plant vigor and overall yield The investigation determined optimal coating and drying conditions, encompassing a drum speed of 20 rpm, a drying temperature of 45 °C, and a drying duration of 8 min (treatment R-204508), along with a drum speed of 20 rpm, a drying temperature of 45 °C, and a drying time of 8 min (treatment R-104508). These conditions resulted in the highest mean germination rates and germination indices. GRAPHICAL ABSTRACT

Design and Experimental Study of a Biomimetic Pod-Pepper-Picking Drum Based on Multi-Finger Collaboration

In order to reduce ground drop loss during mechanical pepper picking and improve the net recovery rate, a drum snap finger picking device was designed. The picking device is mainly composed of a picking drum and auxiliary picking components; the picking finger arrangement was designed biomimetically and its structure and operating parameters were optimized by the DEM (discrete element method). According to the physical and mechanical characteristics of the pepper and the simplified three-dimensional model of the picking device, a virtual simulation model of the pepper-picking device was established using the EDEM software. Through simulation analysis and using the orthogonal test method, the main factors which affect the ground drop loss rate of pepper and their optimal parameter combination values were determined. The simulation results were verified by a pepper-picking field experiment. Orthogonal tests show that, when the picking drum speed (V′) is 210 rpm, the pepper-feeding speed (V″) is 1100 mm·s−1, the bending angle of each picking spring tooth (C) is 162°, and each group of circumferential fingers has rows, the picking device has a good picking effect. At this time, the ground drop loss rates in both the simulation and field test were 7.50% and 7.85%, respectively, and the drop error was only 4.46%, which was within the allowable range. The design form and parameter optimization simulation method in this paper provide an important reference for the design and optimization of pepper-harvesting machinery.

A Study of the Distribution of the Threshed Mixture by a Double Longitudinal Axial Flow Corn Threshing Device

In order to determine the distribution pattern of the threshed mixture in the double longitudinal axial flow threshing device, single-factor experiments were conducted on the self-developed experimental platform for the double longitudinal axis threshing device. The experimental factors included drum speed, threshing clearance, and feed rate. The variations in the distribution of the threshed material along the axial and radial directions were examined. The results indicate that the mixed material after threshing exhibits uneven distribution both axially and radially. Along the axial direction, the mass of corn kernels initially increases and then decreases and is predominantly distributed in the front one-third section of the drum. Meanwhile, the mass of corn cobs continuously increases. In the radial direction, the mass of corn kernels and cobs is higher in the middle and on both sides, with the corn kernels being most concentrated in the middle and the corn cobs mostly on the sides. Combining the corn kernel breakage rate and the unthreshed rate, the optimal operating conditions were determined as follows: a drum speed of 400 r/min, a concave clearance of 50 mm, and a feed rate of 16 kg/s.