Heshan, a city in Southwest China, has been built over an old coal mining area. Due to low level of reclamation, coal gangue had been stacked in large heaps and caused geological environ- mental problems. To facilitat...Heshan, a city in Southwest China, has been built over an old coal mining area. Due to low level of reclamation, coal gangue had been stacked in large heaps and caused geological environ- mental problems. To facilitate designing management project of coal gangue, we made an investigation of the largest coal gangue heap in Dongkuang Mine of Heshan. Firstly, the grain composition of coal gangue was estimated through the sieving method, then the representative grading curve was drawn through the statistics method of coarse grain content, and lastly the relationship between the repose an- gle and grain grading was studied by piling up coal gangue with different mix proportion. The result indicates that there is a wider range of grain size in the upper part of coal gangue heap, and the repre- sentative grain grading is well graded and easy to be compacted as filling materials. Besides, the wavy relationship curve of repose angle and coarse grain content shows that the content of 70% is the infiec- tion point of ascent stage and 85% the inflection point of descent stage of the repose angle. What＇s more, the repose angle corresponding to the representative grading of coal gangue is approximately 38.4° and this has guiding significance for management project of coal gangue.展开更多
The repose angle is one of the most significant macroscopic parameters in describing the behavior of granular materials. Under a static condition, the repose angle is the steepest angle at which sediment particles can...The repose angle is one of the most significant macroscopic parameters in describing the behavior of granular materials. Under a static condition, the repose angle is the steepest angle at which sediment particles can rest without motion. In this paper, we use existing data and aeolian physics to analyze the main factors that influence the repose angle of sand dunes, and we investigate different repose angles involving various states and types of materials. We have determined that different factors have differential influence on the magnitude of the repose angle. Our results show that for powdery （〈400-μm diameter） desert sands, the main influential factor on the magnitude of repose angle is the molecular force among particles. Particle size does not influence the repose angle of desert sands directly, but has an indirect impact by affecting the grit sphericity and surface roughness, of which the grit sphericity acts as a major factor. Even at the same average particle size, the repose angle differs with different grain compositions. Furthermore, with increasing unevenness in grain composition, the repose angle increases correspondingly. Sand texture also has a direct influence on the repose angle of desert sands. In two sand samples having the same grain composition but different textures, the repose angles may be different. Water content has a stronger influence on the repose angle than any other factor. However, the relationship between the repose angle and water content is not a simple direct proportion. In fact, with increasing water content, the repose angle first increases and then decreases. These research results will be useful for understanding the mechanisms of dune transport, variations of dune morphology, and the stability and fluidity of dune sands.展开更多
Shape has an undeniable impact on particle behaviour,and the shapes of naturally occurring granular matter are typically irregular.Computational studies of irregularly shaped particles are challenging but necessary to...Shape has an undeniable impact on particle behaviour,and the shapes of naturally occurring granular matter are typically irregular.Computational studies of irregularly shaped particles are challenging but necessary to gain a better understanding of the flow of particulate matter.This study focuses on the behaviour of irregular sinter particles and applies the discrete element method to examine the effects of static and rolling friction coefficients and particle shape on the angle of repose and porosity of sinter piles.A three-dimensional model of an irregular sinter particle reconstructed by close-range photogrammetry served as the template for generating multi-sphere particles with varying numbers of sub-spheres(1,3,7,22,and 135)and sphericity ranging from 1 to 0.69.Simulations of particle piles were conducted for a range of values of the coefficients of static and rolling friction.The results indicate that the angle of repose increases with static friction and also increases with rolling friction coefficient when it is lower than the static coefficient.The angle of repose shows clear dependence on particle shape,particularly for lower rolling friction coefficients.The friction coefficients for particles of five different shapes were individually determined through bulk calibration,and irregularly shaped particles in DEM were found to require lower friction coefficients.Porosity was marginally affected by the static and rolling friction coefficients for spherical particles,while non-spherical particles showed porosity increasing with the rolling friction coefficient.The relationship between particle sphericity and porosity was nonlinear:as sphericity decreases from 1.00 to 0.69,the porosity first decreases to a minimum and then increases.The findings confirmed that both friction and particle shape have a significant influence on the structure of sinter piles,with implications for material handling and processing in industrial applications.展开更多
Corn kernel shape is an important feature to improve the accuracy of simulation results,also the repose angle is often used to calibrate model parameters in simulation.In this study,the effects of the corn kernel shap...Corn kernel shape is an important feature to improve the accuracy of simulation results,also the repose angle is often used to calibrate model parameters in simulation.In this study,the effects of the corn kernel shapes on the behavior during corn kernels accumulation were investigated in detail.Firstly,the DEM models of three typical shapes of corn kernels were developed.Secondly,the influences of the corn kernel shapes on the process of forming repose angle were investigated,such as corn kernels distance change,energy conversion,and the contact number between corn kernels.Results show that the corn kernel shape has a significant effect on the repose angle formation.The irregular shape of corn kernels limit their rolling when adding the corn kernel length in one or two directions.In addition,the irregular shapes of corn kernels increase the contact number and extend simulation time.Regular shape corn kernels need to be mixed with irregular shape corn kernels to improve their flowability.Finally,observation of the trajectory of corn kernel repose angles indicates that spherical corn kernels contact the bottom plate early,and forming small cone first,then the cone becomes bigger to change the direction of other corn kernels from top to bottom.展开更多
The flowability of five kinds of microencapsulation powders,with differentβ-carotene contents and by two alternative particle-forming technologies i.e.spray-drying and starch-catching beadlet technology,was meas- ure...The flowability of five kinds of microencapsulation powders,with differentβ-carotene contents and by two alternative particle-forming technologies i.e.spray-drying and starch-catching beadlet technology,was meas- ured.The actual flow properties of the five powders were compared based on bin-flow test,and three flow indexes (Hausner ratio,repose angle and flow index)were measured.It was found that the repose angle is the most suitable index to reflect the flowability of these powders for the particle properties would not be altered due to compaction or tapping during the measuring process.Particle size and particle size distribution play most important roles in the flowability of these granular materials,which was also influenced by other factors like shape,surface texture,sur- face roughness,etc.Microcapsules with wall material of gelatin and a layer of modified starch absorbed on the sur- face showed excellent flowabilities and good mechanical properties,and they are favorable for tabletting to supply β-carotene.展开更多
Discrete element modelling(DEM)is a numerical method for examining the dynamic behavior of granular media.In order to build an accurate simulation model and provide more comprehensive soil characteristic parameters fo...Discrete element modelling(DEM)is a numerical method for examining the dynamic behavior of granular media.In order to build an accurate simulation model and provide more comprehensive soil characteristic parameters for the design and optimization of various soil contact machinery,in this paper,the discrete element simulation method(EDEM)combined with experimental approach is used to investigate the soil contact characteristic parameters in East Asia.In this study,Hertze-Mindlin(no slip)was used as a particle contact model by taking particle contact parameters and soil JKR(Johnson-Kendall-Roberts)surface energy as determinants,and repose angle,internal friction angle,and cohesive force as evaluation indexes.The method of Plackett-Burman,Stepest ascent,and Box-Behnken were used to gradually reduce the range of parameters needed for simulation until the most accurate value was determined.The results show that the restitution coefficient,static friction coefficient,and rolling friction coefficient between soil particles have significant effects on the DEM model,and their value of them are 0.596,0.725,and 0.16,respectively.Based on these parameters used for the repose angle test and direct shear stress test,the value of repose angle is 31.97°,the internal friction angle is 27.61°,and the cohesive force is 33.06 kPa.The relative errors with the actual measured values are 9.54%,1.87%,and 2.31%,respectively.In order to further test whether the simulation parameters of soil obtained by repose angle test and direct shear stress test are consistent with the real soil,comparison test between field test and discrete element simulation was used.The results show that the error in height of ridge between the simulated soil and the actual soil is 4.06%,which is within the acceptable range.It also indicates that the calibrated and optimized soil simulation model can accurately represent the real soil.The research provides theoretical basis and technical support for the study of soil contact parts by using the discrete element method,combined with repose angle test and direct shear stress test.展开更多
Sunflower(Helianthus annuus L.)is one of the four major oil crops in the world and has high economic value.However,the lack of discrete element method(DEM)models and parameters for sunflower seeds hinders the applicat...Sunflower(Helianthus annuus L.)is one of the four major oil crops in the world and has high economic value.However,the lack of discrete element method(DEM)models and parameters for sunflower seeds hinders the application of DEM for computer simulation in the key working processes of sunflower seed sowing and harvesting.The present study was conducted on two varieties of sunflower,and the DEM model of sunflower seeds was established by using 3D scanning technology based on the distribution of triaxial dimensions and volumes of the geometric model of sunflower seeds.Similarly,the physical characteristics parameters of sunflower seeds were determined by physical tests and the simulation parameters were screened for significance based on the Plackett-Burman test.Our results show that the coefficient of static friction between sunflower seeds and the coefficient of rolling friction have significant effects on the repose angle of the simulation test.Furthermore,the optimal range of the significance parameters was further determined by the steepest climb test,and the second-order regression model of the significance parameters and the repose angle was obtained according to the Box-Behnken design test and Response Surface Methodology(RSM),with the repose angle measured by the physical test as the optimized target value to obtain the optimal parameter combination.Finally,a two-sample t-test for the repose angle of the physical test and the repose angle of the simulation test yielded P>0.05.Our results confirms that the repose angle obtained from simulation is not significantly different from the physical test value,and the relative errors between the repose angle of the simulation test and the physical test are 1.43%and 0.40%,respectively,for the optimal combination of parameters.Based on these results it can be concluded that the optimal parameters obtained from the calibration can be used for DEM simulation experiments related to the sunflower seed sowing and harvesting process.展开更多
A conception of exposure degree is used in this article to account for the hiding and exposure mechanism of nonuniform sediment transport. The force arms of particles on the bed slope are assumed to be a function of t...A conception of exposure degree is used in this article to account for the hiding and exposure mechanism of nonuniform sediment transport. The force arms of particles on the bed slope are assumed to be a function of the exposure degree, which is stochastically related to the size and gradation of bed materials. Based on this conception, the formula for the angle of repose of nonuniform sediment is developed. The angle of repose of nonuniform sediment is experimentally investigated in rotation drum at the rolling motion of sediment particles. The nonuniform sediment is gotten from the mixture of two kinds of uniform sediment with different weight ratios and two experimental plans that one for changing the weight ratio of two kinds of uniform sediment from 1：9 to 9：1 and the other changing the uniform sediment size and weight ratio are used. The effect of the rotation speed and the filling degree on the angle of repose is investigated, too. Finally, the formula has been tested against a wide range of laboratory data, the prediction by the newly proposed formulas is very good.展开更多
We explore the effect of particle shape on the angle of repose (AoR) in granular packing using a three-dimensional discrete element method.Non-spherical particles were modeled using super-ellipsoids characterized by a...We explore the effect of particle shape on the angle of repose (AoR) in granular packing using a three-dimensional discrete element method.Non-spherical particles were modeled using super-ellipsoids characterized by aspect ratio and blockiness.The relationship between AoR and particle shape was examined,followed by a series of analyses on the origin of AoR from a microscopic perspective.Results show that,with blockiness deviating from unity,AoR has an approximate "M" shape that exhibits a strong to weak trend with aspect ratio,matching results of previous reports.Another finding suggests a parabolic relationship between normalized AoR and normalized coordination number,AoR increases with anisotropy related more with the anisotropy of particle orientation than with the anisotropy of contact normal.Particle shape is more likely to affect AoR by affecting the tangential force than the normal contact force.An analysis based on traction indicates that dips in stress associated with the tangential force (compared with the normal force) and non-spherical particles (compared with spheres) are more significant.For various particle shapes,AoR is positively correlated with friction mobilization but is negatively correlated with friction mobilization for various coefficient of friction.展开更多
Dambreak-induced bed scouring may undermine the foundation of bridge piers and other structures,and that destruction can pose a serious threat.Consequently,this paper aims at exploring the mechanisms of scouring and a...Dambreak-induced bed scouring may undermine the foundation of bridge piers and other structures,and that destruction can pose a serious threat.Consequently,this paper aims at exploring the mechanisms of scouring and armoring.Firstly,the incipient velocity for nonuniform sediment particles was studied,and a formula was derived based on the angle of repose of nonuniform sediment.The results showed that the mechanism of incipient motion for sand and fine gravel differed from that for coarse gravel and cobbles.Also,comparison between experimental and field data shows that the results from the proposed formula agree well with those observed for all conditions.Secondly,a birth-death,immigration-emigration Markov process was developed to describe the bed load transport rate associated with scouring and armoring.The comparison between experimental data and computed results shows that our model can predict the bed load transport rate,although there may be some limitations,the chief of which is that there are many variables in the model to be determined through experiment.This makes its application in river engineering inconvenient.展开更多
An experimental study on the angle of repose （AoR） of pulverized coal with different particle sizes and different moisture contents （MC） was conducted. Three different measurement methods, free-base piling, fixed-...An experimental study on the angle of repose （AoR） of pulverized coal with different particle sizes and different moisture contents （MC） was conducted. Three different measurement methods, free-base piling, fixed-base piling and sliding, were used. The data were analyzed by one-way and two-way analysis of variance. The results showed that the AoRs of pulverized coal with particle sizes smaller than 150 μm were in the range of 30-50°. The characterization of the flowability of pulverized coal was some cohesiveness or true cohesiveness. The increase of MC will increase AoR and thus decrease the flowability of the powder. However, the particle size effect is bifurcated. Below a critical size, the decrease of particle size decreases the flowability; while above the critical size, the decrease of particle size increases the flowability. It was found that the value of the critical size strongly depends on the powder density. Moreover, the AoR dependence on particle size could be linked with the Geldart＇s particle classification. The critical size at the turning point is on the boundary between Group A and Group B in Geldart＇s classification diagram. Based on the experimental results, there is no significant cross interaction between particle size and MC. The AoRs measured by free-base method and fixed-base method are close, but both remarkably smaller than that measured by the sliding method.展开更多
The discrete element method(DEM)is widely used in the realistic simulation of the shapes of particles.Researchers have considered the simplification of particle shapes owing to the high computational cost of such simu...The discrete element method(DEM)is widely used in the realistic simulation of the shapes of particles.Researchers have considered the simplification of particle shapes owing to the high computational cost of such simulation.In this regard,the modeling of calibrated particles is a major challenge owing to the simultaneous effects of particle properties.The angle-of-repose test is a standard test method used to calibrate the bulk behavior of simulated particles.In the present study,the hollow-cylinder(slump)test was modeled for the verification of discrete element simulations.In this regard,a sensitivity analysis was conducted for all effective parameters,namely the static friction,rolling friction,restitution coefficient,sphericity,roundness,particle size distribution,and number of ballast particles.The results indicate that the rolling friction,roundness,number of particles,and size of particles are the most important parameters in the determination of the angle of repose(AOR).For particles in the range of ballast(20-60 mm),the effect of the number of particles on the angle of repose is reduced when the number is greater than 426.Additionally,it is concluded that angular particles can be replaced with sub-angular particles(R≈0.2-0.45)with a higher rolling friction coefficient(μ_(r)>0.14).展开更多
[Objectives]To optimize the drying technology and formation process of Naomai Xingshen Capsules.[Methods]The yield of paste powder and moisture content as evaluation indicators were taken as indicators,the relative de...[Objectives]To optimize the drying technology and formation process of Naomai Xingshen Capsules.[Methods]The yield of paste powder and moisture content as evaluation indicators were taken as indicators,the relative density of feed liquid,inlet air temperature and dosage of excipients were selected as investigation factors,the orthogonal experiment method was used to optimize the spray drying process.The moisture absorption rate and angle of repose were taken as evaluation indicators,the types of forming excipient were screened,and the critical relative humidity was determined.[Results]The optimum spray drying process was that the relative density of liquid medicine was 1.05(60℃),the air inlet temperature was 200℃,and the dosage of excipients was 2%.The effect of using dextrin as a forming excipient was better,and the relative humidity of the production environment should be controlled below 65%.[Conclusions]The optimized process is stable,feasible,scientific and reasonable,and can be used for large-scale industrial production.展开更多
The coefficient of static friction(SF),the coefficient of rolling friction(RF)for particles are two key parameters affecting the repose angle formation and flow characteristics.In this paper,the interaction effects of...The coefficient of static friction(SF),the coefficient of rolling friction(RF)for particles are two key parameters affecting the repose angle formation and flow characteristics.In this paper,the interaction effects of SF and RF on the formation process of corn repose angle was investigated by the discrete element method.Firstly,five shape kinds of corn models(horse tooth,spherical cone,spheroid,oblate,and irregular shape)were established.Secondly,aluminum cylinder and organic glass box were used to conduct the simulation experiments with taking SF and RF as independent factors and seeing the repose angle as dependent value.Based on simulation results the regression equations were established.Simulation results showed the relation between two factors and the rotational kinetic energy is not nonlinear,and SF does not significantly restrict the flow of corn models after increasing the flow direction,and the effect of SF on the contact number between corns and the bottom plate is remarkable,while the effect of RF on the contact number is not remarkable.Finally,the interaction effect of two factors on the repose angle was analyzed by variance analysis and results showed SF and RF all have a significant impact on the repose angle.Moreover,their interaction effect has an impact on the repose angle.展开更多
Since natural restoration combined with artificial auxiliary measures may achieve a relatively rapid restoration effect at a lower cost,it has become an essential measure for the ecological restoration of rock slopes....Since natural restoration combined with artificial auxiliary measures may achieve a relatively rapid restoration effect at a lower cost,it has become an essential measure for the ecological restoration of rock slopes.Previous studies have focused heavily on the relationship between substrate nutrients and water conditions and the development of mosses on the rock surface,but quantitative characterization of substantial effect of rock surface texture(e.g.,microrelief)on moss growth is absent.The undulating microrelief on the rock surface can increase the heterogeneity of the microhabitat,which may be an important factor affecting the development of mossdominated biocrusts.In this study,the roughness of rock surfaces,moss coverage and biomass,weight and major nutrient contents of soils within the biocrusts were measured in the western mountainous area of Sichuan Province,Southwest China to further examine the role of rock surface microrelief in the biocrusts.The results showed that three main factors affecting the development of the biocrusts were bryophyte emergence,soil accumulation,and lithology.The presence of moss accelerates soil formation on rock surfaces and lead to the accumulation of nutrients so that all parts of the moss-dominated biocrusts system can develop synergistically.It was found that a microrelief structure with a roughness between 1.5 and 2.5 could gather soil and bryophyte propagules effectively,which may have a strong relationship with the angle of repose.When the roughness is 1.5,the corresponding undulation angle is very close to the theoretical minimum value of the undulation angle calculated according to the relationships between the undulation angle of the protrusion,slope and angle of repose.展开更多
Binder jet additive manufacturing is used for producing molds and cores for sand casting,by using granular material and proper binder.The conventional system uses a layer-by-layer gantry motion.The new continuous prin...Binder jet additive manufacturing is used for producing molds and cores for sand casting,by using granular material and proper binder.The conventional system uses a layer-by-layer gantry motion.The new continuous printing machine is a helical motion system.It includes a recoating blade for the granular material which has been investigated.This study focuses on analysing the behaviour of the recoating blade when it moves in a circular or the helical motion,as well as assessing the quality of the layer surface.Discrete Element Method(DEM)simulations was conducted using various blade geometry,and the results were compared with experimental models.The input parameters of the sand material were calibrated using a reverse calibration model,which iteratively adjusts the parameter values until they match the bulk response observed in real experiments.This research study employed experimental testing and DEM modeling,initially using a normal blade to produce an annular disc,and then optimizing the blade shape to achieve full disc printing.展开更多
In this study,the discrete element software EDEM was applied to establish a simulation model of non-uniform-sized particle units for Broussonetia papyrifera stalks,which aimed to address the low utilization rate of ex...In this study,the discrete element software EDEM was applied to establish a simulation model of non-uniform-sized particle units for Broussonetia papyrifera stalks,which aimed to address the low utilization rate of existing Broussonetia papyrifera harvesting machinery,the significant variation between the simulated model of Broussonetia papyrifera stalks and their actual appearance,as well as the absence of contact parameter calibration.Through a combination of the free-fall collision method,inclined plane sliding method,and inclined plane rolling method,numerical simulation was conducted to analyze the pattern of variations in contact parameters between Broussonetia papyrifera stalks and the steel material of the machinery.Accordingly,these parameters were calibrated.The results showed that the coefficient of restitution between Broussonetia papyrifera stalks and steel materials was 0.321,the static friction factor was 0.589,and the rolling friction factor was 0.078.With the parameters of contact between Broussonetia papyrifera stalks as variables and the experimentally measured pile angle as the objective of optimization,the steepest ascent experiment and the three-factor five-level rotation combination experiment were conducted.In this way,a second-order response model was constructed to analyze the relationship between the contact parameters and the pile angle.Through the optimization analysis of experimental data,it was determined that the coefficient of restitution between Broussonetia papyrifera stalks was 0.21,the static friction factor was 0.24,and the rolling friction factor was 0.03.Furthermore,the calibration results were validated through experimentation to show that the relative error between the obtained pile angle under the context of optimal parameter combination and the actual one was 4.11%.In addition,the relative error of mass flow rate in spiral transport was within a reasonable range,this study lays a foundation both theoretically and statistically for the simulation of contact parameters for Broussonetia papyrifera stalk harvesting processing,mechanical harvesting,and so on.展开更多
To improve the survival rate of larvae during material separation after biotransformation of existing residual film mixtures of Protaetia brevitarsis larvae,this paper adopts the method of combining physical test and ...To improve the survival rate of larvae during material separation after biotransformation of existing residual film mixtures of Protaetia brevitarsis larvae,this paper adopts the method of combining physical test and EDEM simulation test,and selects Hertz Mindlin with JKR contact model to calibrate the discrete element simulation contact parameters of the Protaetia brevitarsis larvae and the frass mixture.First,the cylinder lifting method was used to determine the actual repose angle of the mixture of larvae and frass.The collision recovery coefficients between larvae-frass and steel,static friction coefficient,kinetic friction coefficient and the collision recovery coefficient between larvae were measured through physical tests such as the inclined plane method.The Plackett-Burman test was then used to screen out the factors that have a significant impact on the repose angle:Poisson’s ratio of frass,frass-frass rolling friction coefficient,frass JKR surface energy,frass-larvae JKR surface energy.The optimal value intervals of four significant factors were determined based on the steepest climb test,Based on the Box-Behnken response surface analysis test,the second-order regression model between the repose angle and four significant factors was determined,and variance and interaction effects were analyzed.And with the actual repose angle as the goal,the significant factors were optimized and the optimal parameter combination of the four significant factors was determined.The simulation test of material repose angle and screening was carried out with the optimal parameter combination,and compared with the physical test.It was found that the maximum relative errors of the two tests were 1.48%and 3.79%respectively,indicating that the calibrated parameter values are true and reliable,It can provide a reference for the discrete element simulation of the transportation and separation of the Protaetia brevitarsis larvae-frass mixture.展开更多
This study constructed a numerical model using the discrete element software EDEM to address the current lack of calibrated contact parameters for peanut seedling membranes and the absence of precise simulation model ...This study constructed a numerical model using the discrete element software EDEM to address the current lack of calibrated contact parameters for peanut seedling membranes and the absence of precise simulation model parameters for mechanized separation. The Hysteretic Spring Contact Model (HSCM) was employed to calibrate the contact parameters of peanut seedling membranes. The angle of repose of peanut seedling membranes was determined through image processing combined with the least squares method. Through central composite design (CCD), a second-order response model linking the contact parameters to the angle of repose was established. Optimization was achieved by using the angle of repose obtained from physical tests as the objective. Secondary simulation tests were conducted with the calibrated parameters, revealing a relative error of 1.37% between the simulated and physical angles of repose. This confirmed the effectiveness of the parameters in calibrating peanut seedling membrane characteristics. The findings offer theoretical and empirical support for discrete element simulations of peanut seedling membrane separation and peanut straw pulverization processes.展开更多
In view of the fact that the existing cotton stem simulation models are simplified and have a large discrepancy from the actual appearance and the contact parameters have not been calibrated.In this study,the simulati...In view of the fact that the existing cotton stem simulation models are simplified and have a large discrepancy from the actual appearance and the contact parameters have not been calibrated.In this study,the simulation model and numerical simulation were established using the discrete element software EDEM.Then a second-order response model between contact parameters and repose angle had been constructed.The test result showed that the static friction coefficient,rolling friction coefficient,and coefficient of restitution between cotton stems were crucial factors affecting the repose angle.The determination coefficient corrected determination coefficient and p-value of the second-order response model were R^(2)=0.959,R^(2)_(adj)=0.921,and p<0.0001 respectively.The error values of the comparison between the simulation test results and the corresponding physical test values were all less than 10%,which showed that the model was reliable and had high interpretation and predictability,this study can provide a certain theoretical basis and data support for the setting of contact parameters in the data simulation of cotton stem harvesting and processing,mechanically-harvested film residue crushing and film stem separation,etc.展开更多
文摘Heshan, a city in Southwest China, has been built over an old coal mining area. Due to low level of reclamation, coal gangue had been stacked in large heaps and caused geological environ- mental problems. To facilitate designing management project of coal gangue, we made an investigation of the largest coal gangue heap in Dongkuang Mine of Heshan. Firstly, the grain composition of coal gangue was estimated through the sieving method, then the representative grading curve was drawn through the statistics method of coarse grain content, and lastly the relationship between the repose an- gle and grain grading was studied by piling up coal gangue with different mix proportion. The result indicates that there is a wider range of grain size in the upper part of coal gangue heap, and the repre- sentative grain grading is well graded and easy to be compacted as filling materials. Besides, the wavy relationship curve of repose angle and coarse grain content shows that the content of 70% is the infiec- tion point of ascent stage and 85% the inflection point of descent stage of the repose angle. What＇s more, the repose angle corresponding to the representative grading of coal gangue is approximately 38.4° and this has guiding significance for management project of coal gangue.
基金supported by the National Natural Science Foundation of China (Grant No. 50879033)the National Science Fund for Fostering Talents in Basic Research of the National Natural Science Foundation of China (Grant No.J0730536)
文摘The repose angle is one of the most significant macroscopic parameters in describing the behavior of granular materials. Under a static condition, the repose angle is the steepest angle at which sediment particles can rest without motion. In this paper, we use existing data and aeolian physics to analyze the main factors that influence the repose angle of sand dunes, and we investigate different repose angles involving various states and types of materials. We have determined that different factors have differential influence on the magnitude of the repose angle. Our results show that for powdery （〈400-μm diameter） desert sands, the main influential factor on the magnitude of repose angle is the molecular force among particles. Particle size does not influence the repose angle of desert sands directly, but has an indirect impact by affecting the grit sphericity and surface roughness, of which the grit sphericity acts as a major factor. Even at the same average particle size, the repose angle differs with different grain compositions. Furthermore, with increasing unevenness in grain composition, the repose angle increases correspondingly. Sand texture also has a direct influence on the repose angle of desert sands. In two sand samples having the same grain composition but different textures, the repose angles may be different. Water content has a stronger influence on the repose angle than any other factor. However, the relationship between the repose angle and water content is not a simple direct proportion. In fact, with increasing water content, the repose angle first increases and then decreases. These research results will be useful for understanding the mechanisms of dune transport, variations of dune morphology, and the stability and fluidity of dune sands.
基金funded by China Scholarship Council(grant No.202106890009).
文摘Shape has an undeniable impact on particle behaviour,and the shapes of naturally occurring granular matter are typically irregular.Computational studies of irregularly shaped particles are challenging but necessary to gain a better understanding of the flow of particulate matter.This study focuses on the behaviour of irregular sinter particles and applies the discrete element method to examine the effects of static and rolling friction coefficients and particle shape on the angle of repose and porosity of sinter piles.A three-dimensional model of an irregular sinter particle reconstructed by close-range photogrammetry served as the template for generating multi-sphere particles with varying numbers of sub-spheres(1,3,7,22,and 135)and sphericity ranging from 1 to 0.69.Simulations of particle piles were conducted for a range of values of the coefficients of static and rolling friction.The results indicate that the angle of repose increases with static friction and also increases with rolling friction coefficient when it is lower than the static coefficient.The angle of repose shows clear dependence on particle shape,particularly for lower rolling friction coefficients.The friction coefficients for particles of five different shapes were individually determined through bulk calibration,and irregularly shaped particles in DEM were found to require lower friction coefficients.Porosity was marginally affected by the static and rolling friction coefficients for spherical particles,while non-spherical particles showed porosity increasing with the rolling friction coefficient.The relationship between particle sphericity and porosity was nonlinear:as sphericity decreases from 1.00 to 0.69,the porosity first decreases to a minimum and then increases.The findings confirmed that both friction and particle shape have a significant influence on the structure of sinter piles,with implications for material handling and processing in industrial applications.
基金This work was supported by the Fostering Foundation for the Excellent Ph.D.Dissertation of Gansu Agricultural University(YB2020003)the Chinese Natural Science Foundation(52065004).
文摘Corn kernel shape is an important feature to improve the accuracy of simulation results,also the repose angle is often used to calibrate model parameters in simulation.In this study,the effects of the corn kernel shapes on the behavior during corn kernels accumulation were investigated in detail.Firstly,the DEM models of three typical shapes of corn kernels were developed.Secondly,the influences of the corn kernel shapes on the process of forming repose angle were investigated,such as corn kernels distance change,energy conversion,and the contact number between corn kernels.Results show that the corn kernel shape has a significant effect on the repose angle formation.The irregular shape of corn kernels limit their rolling when adding the corn kernel length in one or two directions.In addition,the irregular shapes of corn kernels increase the contact number and extend simulation time.Regular shape corn kernels need to be mixed with irregular shape corn kernels to improve their flowability.Finally,observation of the trajectory of corn kernel repose angles indicates that spherical corn kernels contact the bottom plate early,and forming small cone first,then the cone becomes bigger to change the direction of other corn kernels from top to bottom.
基金Supported by the National-Natural Science Foundation of China （No.20576118） and National High Technology Research and Development Program of China （863 Program, No.2006AA02Z210）.
文摘The flowability of five kinds of microencapsulation powders,with differentβ-carotene contents and by two alternative particle-forming technologies i.e.spray-drying and starch-catching beadlet technology,was meas- ured.The actual flow properties of the five powders were compared based on bin-flow test,and three flow indexes (Hausner ratio,repose angle and flow index)were measured.It was found that the repose angle is the most suitable index to reflect the flowability of these powders for the particle properties would not be altered due to compaction or tapping during the measuring process.Particle size and particle size distribution play most important roles in the flowability of these granular materials,which was also influenced by other factors like shape,surface texture,sur- face roughness,etc.Microcapsules with wall material of gelatin and a layer of modified starch absorbed on the sur- face showed excellent flowabilities and good mechanical properties,and they are favorable for tabletting to supply β-carotene.
基金This work was financially supported by the National Science and Technology Major Project of China(Grant No.2019YFD 1002502)the National Natural Science Foundation of China(Grant No.51675239)+2 种基金The Natural Science Fund Project of Colleges in Jiangsu Province of China(Grant No.19KJA430018)The Important Development Program of Ningxia Province of China(Grant No.2018BBF02020)The Research and Development Program of Zhenjiang Province of China(Grant No.NY2019015).
文摘Discrete element modelling(DEM)is a numerical method for examining the dynamic behavior of granular media.In order to build an accurate simulation model and provide more comprehensive soil characteristic parameters for the design and optimization of various soil contact machinery,in this paper,the discrete element simulation method(EDEM)combined with experimental approach is used to investigate the soil contact characteristic parameters in East Asia.In this study,Hertze-Mindlin(no slip)was used as a particle contact model by taking particle contact parameters and soil JKR(Johnson-Kendall-Roberts)surface energy as determinants,and repose angle,internal friction angle,and cohesive force as evaluation indexes.The method of Plackett-Burman,Stepest ascent,and Box-Behnken were used to gradually reduce the range of parameters needed for simulation until the most accurate value was determined.The results show that the restitution coefficient,static friction coefficient,and rolling friction coefficient between soil particles have significant effects on the DEM model,and their value of them are 0.596,0.725,and 0.16,respectively.Based on these parameters used for the repose angle test and direct shear stress test,the value of repose angle is 31.97°,the internal friction angle is 27.61°,and the cohesive force is 33.06 kPa.The relative errors with the actual measured values are 9.54%,1.87%,and 2.31%,respectively.In order to further test whether the simulation parameters of soil obtained by repose angle test and direct shear stress test are consistent with the real soil,comparison test between field test and discrete element simulation was used.The results show that the error in height of ridge between the simulated soil and the actual soil is 4.06%,which is within the acceptable range.It also indicates that the calibrated and optimized soil simulation model can accurately represent the real soil.The research provides theoretical basis and technical support for the study of soil contact parts by using the discrete element method,combined with repose angle test and direct shear stress test.
基金funding for this study from Nature Science Foundation of China,Grant No.(51865047).
文摘Sunflower(Helianthus annuus L.)is one of the four major oil crops in the world and has high economic value.However,the lack of discrete element method(DEM)models and parameters for sunflower seeds hinders the application of DEM for computer simulation in the key working processes of sunflower seed sowing and harvesting.The present study was conducted on two varieties of sunflower,and the DEM model of sunflower seeds was established by using 3D scanning technology based on the distribution of triaxial dimensions and volumes of the geometric model of sunflower seeds.Similarly,the physical characteristics parameters of sunflower seeds were determined by physical tests and the simulation parameters were screened for significance based on the Plackett-Burman test.Our results show that the coefficient of static friction between sunflower seeds and the coefficient of rolling friction have significant effects on the repose angle of the simulation test.Furthermore,the optimal range of the significance parameters was further determined by the steepest climb test,and the second-order regression model of the significance parameters and the repose angle was obtained according to the Box-Behnken design test and Response Surface Methodology(RSM),with the repose angle measured by the physical test as the optimized target value to obtain the optimal parameter combination.Finally,a two-sample t-test for the repose angle of the physical test and the repose angle of the simulation test yielded P>0.05.Our results confirms that the repose angle obtained from simulation is not significantly different from the physical test value,and the relative errors between the repose angle of the simulation test and the physical test are 1.43%and 0.40%,respectively,for the optimal combination of parameters.Based on these results it can be concluded that the optimal parameters obtained from the calibration can be used for DEM simulation experiments related to the sunflower seed sowing and harvesting process.
基金supported by the National Natural Science Foundation of China (Grant Nos.50739002,50979064)
文摘A conception of exposure degree is used in this article to account for the hiding and exposure mechanism of nonuniform sediment transport. The force arms of particles on the bed slope are assumed to be a function of the exposure degree, which is stochastically related to the size and gradation of bed materials. Based on this conception, the formula for the angle of repose of nonuniform sediment is developed. The angle of repose of nonuniform sediment is experimentally investigated in rotation drum at the rolling motion of sediment particles. The nonuniform sediment is gotten from the mixture of two kinds of uniform sediment with different weight ratios and two experimental plans that one for changing the weight ratio of two kinds of uniform sediment from 1：9 to 9：1 and the other changing the uniform sediment size and weight ratio are used. The effect of the rotation speed and the filling degree on the angle of repose is investigated, too. Finally, the formula has been tested against a wide range of laboratory data, the prediction by the newly proposed formulas is very good.
基金the Fundamental Research Funds for Central Universities,State Key Laboratory of Subtrop-ical Building Science(2017KA04)partially by Science and Technology Program of Guangzhou(201707020047)。
文摘We explore the effect of particle shape on the angle of repose (AoR) in granular packing using a three-dimensional discrete element method.Non-spherical particles were modeled using super-ellipsoids characterized by aspect ratio and blockiness.The relationship between AoR and particle shape was examined,followed by a series of analyses on the origin of AoR from a microscopic perspective.Results show that,with blockiness deviating from unity,AoR has an approximate "M" shape that exhibits a strong to weak trend with aspect ratio,matching results of previous reports.Another finding suggests a parabolic relationship between normalized AoR and normalized coordination number,AoR increases with anisotropy related more with the anisotropy of particle orientation than with the anisotropy of contact normal.Particle shape is more likely to affect AoR by affecting the tangential force than the normal contact force.An analysis based on traction indicates that dips in stress associated with the tangential force (compared with the normal force) and non-spherical particles (compared with spheres) are more significant.For various particle shapes,AoR is positively correlated with friction mobilization but is negatively correlated with friction mobilization for various coefficient of friction.
基金supported by 973 Program (2008CB425803)the National Natural Science Foundation of China (Grant No. 50979064)
文摘Dambreak-induced bed scouring may undermine the foundation of bridge piers and other structures,and that destruction can pose a serious threat.Consequently,this paper aims at exploring the mechanisms of scouring and armoring.Firstly,the incipient velocity for nonuniform sediment particles was studied,and a formula was derived based on the angle of repose of nonuniform sediment.The results showed that the mechanism of incipient motion for sand and fine gravel differed from that for coarse gravel and cobbles.Also,comparison between experimental and field data shows that the results from the proposed formula agree well with those observed for all conditions.Secondly,a birth-death,immigration-emigration Markov process was developed to describe the bed load transport rate associated with scouring and armoring.The comparison between experimental data and computed results shows that our model can predict the bed load transport rate,although there may be some limitations,the chief of which is that there are many variables in the model to be determined through experiment.This makes its application in river engineering inconvenient.
基金supports by National Basic Research Program of China(2010CB227006)National High-tech R&D Program(2009AA05Z216)
文摘An experimental study on the angle of repose （AoR） of pulverized coal with different particle sizes and different moisture contents （MC） was conducted. Three different measurement methods, free-base piling, fixed-base piling and sliding, were used. The data were analyzed by one-way and two-way analysis of variance. The results showed that the AoRs of pulverized coal with particle sizes smaller than 150 μm were in the range of 30-50°. The characterization of the flowability of pulverized coal was some cohesiveness or true cohesiveness. The increase of MC will increase AoR and thus decrease the flowability of the powder. However, the particle size effect is bifurcated. Below a critical size, the decrease of particle size decreases the flowability; while above the critical size, the decrease of particle size increases the flowability. It was found that the value of the critical size strongly depends on the powder density. Moreover, the AoR dependence on particle size could be linked with the Geldart＇s particle classification. The critical size at the turning point is on the boundary between Group A and Group B in Geldart＇s classification diagram. Based on the experimental results, there is no significant cross interaction between particle size and MC. The AoRs measured by free-base method and fixed-base method are close, but both remarkably smaller than that measured by the sliding method.
文摘The discrete element method(DEM)is widely used in the realistic simulation of the shapes of particles.Researchers have considered the simplification of particle shapes owing to the high computational cost of such simulation.In this regard,the modeling of calibrated particles is a major challenge owing to the simultaneous effects of particle properties.The angle-of-repose test is a standard test method used to calibrate the bulk behavior of simulated particles.In the present study,the hollow-cylinder(slump)test was modeled for the verification of discrete element simulations.In this regard,a sensitivity analysis was conducted for all effective parameters,namely the static friction,rolling friction,restitution coefficient,sphericity,roundness,particle size distribution,and number of ballast particles.The results indicate that the rolling friction,roundness,number of particles,and size of particles are the most important parameters in the determination of the angle of repose(AOR).For particles in the range of ballast(20-60 mm),the effect of the number of particles on the angle of repose is reduced when the number is greater than 426.Additionally,it is concluded that angular particles can be replaced with sub-angular particles(R≈0.2-0.45)with a higher rolling friction coefficient(μ_(r)>0.14).
基金Medical Research Project of Zhongshan City Health and Family Planning Bureau,Guangdong Province(2015J050).
文摘[Objectives]To optimize the drying technology and formation process of Naomai Xingshen Capsules.[Methods]The yield of paste powder and moisture content as evaluation indicators were taken as indicators,the relative density of feed liquid,inlet air temperature and dosage of excipients were selected as investigation factors,the orthogonal experiment method was used to optimize the spray drying process.The moisture absorption rate and angle of repose were taken as evaluation indicators,the types of forming excipient were screened,and the critical relative humidity was determined.[Results]The optimum spray drying process was that the relative density of liquid medicine was 1.05(60℃),the air inlet temperature was 200℃,and the dosage of excipients was 2%.The effect of using dextrin as a forming excipient was better,and the relative humidity of the production environment should be controlled below 65%.[Conclusions]The optimized process is stable,feasible,scientific and reasonable,and can be used for large-scale industrial production.
基金by the Excellent Ph.D.Dissertation of Gansu Agricultural University(YB2020003)the Chinese Natural Science Foundation(52065004).
文摘The coefficient of static friction(SF),the coefficient of rolling friction(RF)for particles are two key parameters affecting the repose angle formation and flow characteristics.In this paper,the interaction effects of SF and RF on the formation process of corn repose angle was investigated by the discrete element method.Firstly,five shape kinds of corn models(horse tooth,spherical cone,spheroid,oblate,and irregular shape)were established.Secondly,aluminum cylinder and organic glass box were used to conduct the simulation experiments with taking SF and RF as independent factors and seeing the repose angle as dependent value.Based on simulation results the regression equations were established.Simulation results showed the relation between two factors and the rotational kinetic energy is not nonlinear,and SF does not significantly restrict the flow of corn models after increasing the flow direction,and the effect of SF on the contact number between corns and the bottom plate is remarkable,while the effect of RF on the contact number is not remarkable.Finally,the interaction effect of two factors on the repose angle was analyzed by variance analysis and results showed SF and RF all have a significant impact on the repose angle.Moreover,their interaction effect has an impact on the repose angle.
基金supported by the Project of Assessment on Post-quake Ecosystem and Environment Recovery in Jiuzhaigou under Grant 5132202020000046the National Key Research and Development Programme of China under Grant 2017YFC0504902。
文摘Since natural restoration combined with artificial auxiliary measures may achieve a relatively rapid restoration effect at a lower cost,it has become an essential measure for the ecological restoration of rock slopes.Previous studies have focused heavily on the relationship between substrate nutrients and water conditions and the development of mosses on the rock surface,but quantitative characterization of substantial effect of rock surface texture(e.g.,microrelief)on moss growth is absent.The undulating microrelief on the rock surface can increase the heterogeneity of the microhabitat,which may be an important factor affecting the development of mossdominated biocrusts.In this study,the roughness of rock surfaces,moss coverage and biomass,weight and major nutrient contents of soils within the biocrusts were measured in the western mountainous area of Sichuan Province,Southwest China to further examine the role of rock surface microrelief in the biocrusts.The results showed that three main factors affecting the development of the biocrusts were bryophyte emergence,soil accumulation,and lithology.The presence of moss accelerates soil formation on rock surfaces and lead to the accumulation of nutrients so that all parts of the moss-dominated biocrusts system can develop synergistically.It was found that a microrelief structure with a roughness between 1.5 and 2.5 could gather soil and bryophyte propagules effectively,which may have a strong relationship with the angle of repose.When the roughness is 1.5,the corresponding undulation angle is very close to the theoretical minimum value of the undulation angle calculated according to the relationships between the undulation angle of the protrusion,slope and angle of repose.
文摘Binder jet additive manufacturing is used for producing molds and cores for sand casting,by using granular material and proper binder.The conventional system uses a layer-by-layer gantry motion.The new continuous printing machine is a helical motion system.It includes a recoating blade for the granular material which has been investigated.This study focuses on analysing the behaviour of the recoating blade when it moves in a circular or the helical motion,as well as assessing the quality of the layer surface.Discrete Element Method(DEM)simulations was conducted using various blade geometry,and the results were compared with experimental models.The input parameters of the sand material were calibrated using a reverse calibration model,which iteratively adjusts the parameter values until they match the bulk response observed in real experiments.This research study employed experimental testing and DEM modeling,initially using a normal blade to produce an annular disc,and then optimizing the blade shape to achieve full disc printing.
基金the Natural Science Foundation of Hunan Province,China(Grant No.2023JJ30310)Scientific Research Fund of Hunan Provincial Education Department(Grant No.22A0169).
文摘In this study,the discrete element software EDEM was applied to establish a simulation model of non-uniform-sized particle units for Broussonetia papyrifera stalks,which aimed to address the low utilization rate of existing Broussonetia papyrifera harvesting machinery,the significant variation between the simulated model of Broussonetia papyrifera stalks and their actual appearance,as well as the absence of contact parameter calibration.Through a combination of the free-fall collision method,inclined plane sliding method,and inclined plane rolling method,numerical simulation was conducted to analyze the pattern of variations in contact parameters between Broussonetia papyrifera stalks and the steel material of the machinery.Accordingly,these parameters were calibrated.The results showed that the coefficient of restitution between Broussonetia papyrifera stalks and steel materials was 0.321,the static friction factor was 0.589,and the rolling friction factor was 0.078.With the parameters of contact between Broussonetia papyrifera stalks as variables and the experimentally measured pile angle as the objective of optimization,the steepest ascent experiment and the three-factor five-level rotation combination experiment were conducted.In this way,a second-order response model was constructed to analyze the relationship between the contact parameters and the pile angle.Through the optimization analysis of experimental data,it was determined that the coefficient of restitution between Broussonetia papyrifera stalks was 0.21,the static friction factor was 0.24,and the rolling friction factor was 0.03.Furthermore,the calibration results were validated through experimentation to show that the relative error between the obtained pile angle under the context of optimal parameter combination and the actual one was 4.11%.In addition,the relative error of mass flow rate in spiral transport was within a reasonable range,this study lays a foundation both theoretically and statistically for the simulation of contact parameters for Broussonetia papyrifera stalk harvesting processing,mechanical harvesting,and so on.
基金supported by the Autonomous Region Key R&D Program of Xinjiang,China(Grant No.2022B02046).
文摘To improve the survival rate of larvae during material separation after biotransformation of existing residual film mixtures of Protaetia brevitarsis larvae,this paper adopts the method of combining physical test and EDEM simulation test,and selects Hertz Mindlin with JKR contact model to calibrate the discrete element simulation contact parameters of the Protaetia brevitarsis larvae and the frass mixture.First,the cylinder lifting method was used to determine the actual repose angle of the mixture of larvae and frass.The collision recovery coefficients between larvae-frass and steel,static friction coefficient,kinetic friction coefficient and the collision recovery coefficient between larvae were measured through physical tests such as the inclined plane method.The Plackett-Burman test was then used to screen out the factors that have a significant impact on the repose angle:Poisson’s ratio of frass,frass-frass rolling friction coefficient,frass JKR surface energy,frass-larvae JKR surface energy.The optimal value intervals of four significant factors were determined based on the steepest climb test,Based on the Box-Behnken response surface analysis test,the second-order regression model between the repose angle and four significant factors was determined,and variance and interaction effects were analyzed.And with the actual repose angle as the goal,the significant factors were optimized and the optimal parameter combination of the four significant factors was determined.The simulation test of material repose angle and screening was carried out with the optimal parameter combination,and compared with the physical test.It was found that the maximum relative errors of the two tests were 1.48%and 3.79%respectively,indicating that the calibrated parameter values are true and reliable,It can provide a reference for the discrete element simulation of the transportation and separation of the Protaetia brevitarsis larvae-frass mixture.
基金supported by the National Natural Science Foundation of China(Grant No.52175238)the Xinjiang Key Research and Development Program(Grant No.2022B02022-1)+1 种基金the Engineering Research and Development of High-efficiency Intelligent Residue Film Recycling Equipment in 2022(Second Batch)(Grant No.CEIEC-2022-ZM02-0226)the Integrated Pilot Project for Research,Development,Manufacturing,and Promotion of Agricultural Machinery in Shandong Province(Grant No.NJYTHSD-202321).
文摘This study constructed a numerical model using the discrete element software EDEM to address the current lack of calibrated contact parameters for peanut seedling membranes and the absence of precise simulation model parameters for mechanized separation. The Hysteretic Spring Contact Model (HSCM) was employed to calibrate the contact parameters of peanut seedling membranes. The angle of repose of peanut seedling membranes was determined through image processing combined with the least squares method. Through central composite design (CCD), a second-order response model linking the contact parameters to the angle of repose was established. Optimization was achieved by using the angle of repose obtained from physical tests as the objective. Secondary simulation tests were conducted with the calibrated parameters, revealing a relative error of 1.37% between the simulated and physical angles of repose. This confirmed the effectiveness of the parameters in calibrating peanut seedling membrane characteristics. The findings offer theoretical and empirical support for discrete element simulations of peanut seedling membrane separation and peanut straw pulverization processes.
基金financially supported by the Less Developed Regions of the National Natural Science Foundation of China(Grant No.52065058)the Graduate Education Innovation Project of Xinjiang Uygur Autonomous Region(Grant No.XJ2022G085)+1 种基金the Open Fund of Jiangsu Province and Education Ministry Co-sponsored Synergistic Innovation Center of Modern Agricultural Equipment,(Grant No.XTCX2006)the key industry innovation development support plan of southern Xinjiang(Grant No.2020DB008).
文摘In view of the fact that the existing cotton stem simulation models are simplified and have a large discrepancy from the actual appearance and the contact parameters have not been calibrated.In this study,the simulation model and numerical simulation were established using the discrete element software EDEM.Then a second-order response model between contact parameters and repose angle had been constructed.The test result showed that the static friction coefficient,rolling friction coefficient,and coefficient of restitution between cotton stems were crucial factors affecting the repose angle.The determination coefficient corrected determination coefficient and p-value of the second-order response model were R^(2)=0.959,R^(2)_(adj)=0.921,and p<0.0001 respectively.The error values of the comparison between the simulation test results and the corresponding physical test values were all less than 10%,which showed that the model was reliable and had high interpretation and predictability,this study can provide a certain theoretical basis and data support for the setting of contact parameters in the data simulation of cotton stem harvesting and processing,mechanically-harvested film residue crushing and film stem separation,etc.
