This study was conducted to further classify threshed strips, so as to broaden the usable range of raw material and facilitate the effective utilization of to- bacco resource. During the threshing and redwing process,...This study was conducted to further classify threshed strips, so as to broaden the usable range of raw material and facilitate the effective utilization of to- bacco resource. During the threshing and redwing process, various process param- eters including the rotating speeds of threshing drums of threshing machioe, draught fans and fling drums were scientifically and rationally set according to the actual quality of the raw material. According to the characteristic that strips with close in- herent quality have basically the same specific gravity and leaf thickness, the strips from each discharge hole were accurately evaluated, and classified, followed by redrying and packaging. The results showed that the threshing and separating pro- cedure could improve the separating effect and precision according to tobacco qual- ity, so as to satisfy the separation and classification requirements for tobacco.展开更多
Mechanical threshing used when preparing maize seeds for planting subjects seed to damage and reduces seed quality.The purpose of this study was to assess the effect of mechanical threshing on the quality of maize see...Mechanical threshing used when preparing maize seeds for planting subjects seed to damage and reduces seed quality.The purpose of this study was to assess the effect of mechanical threshing on the quality of maize seed threshed at different moisture contents(MCs).Seeds of dent maize JK968 and flint maize DD2 were threshed at 12,15,18,21,and 24% MC.The damage degree was determined by iodine staining,and seed vigor was assessed by standard germination(SG),cold test germination(CTG),accelerated aging germination(AAG),seedling emergence rate,and seedling root and shoot length.The results showed that the damage percentage increased,and the seed vigor parameters decreased with increasing seed MC during threshing in both cultivars.For obtaining high seed quality,indicated by at least 90,85,and 80% of SG,AAG,and CTG,respectively,JK 968 and DD2 should be threshed at MC lower than 15 and 18%,respectively.Furthermore,the damage mainly occurred in the apical part of seeds,irrespective of the threshing MC in both cultivars.When the embryo was damaged,seedling emergence rates were significantly reduced with great influence on shoot length.Damage to the endosperm resulted in little effect on seedling performance.Flint maize DD2 was more tolerant to mechanical threshing than dent maize JK968.These results provided technical reference for the production and processing of high vigor maize seeds.展开更多
This paper focused on the influence of the shape and size of threshing frames as well as the grades of tobacco leaves on the structure of threshed leaves.The testing tobacco leaves all came from the hilly ecological r...This paper focused on the influence of the shape and size of threshing frames as well as the grades of tobacco leaves on the structure of threshed leaves.The testing tobacco leaves all came from the hilly ecological region of Nanling and belonged to burnt sweet,alcoholic sweet and scent category.The comprehensive evaluating value S was taken as the test index.Results showed that,without considering the influence of tobacco grade on leaf structure,the shapes of first-stage thresher five-link frames were all hexagons,and the combination with the sizes of 3.5,3.0,3.5,3.0,3.0 inches had the highest evaluating value S of 2.49.For tobacco grade C2FH,the shapes of first-stage thresher five-link frames were also hexagons,and the evaluating value S reached the highest value of 3.40 with sizes of 3.5,3.0,3.5,3.0,3.0 inches.Comprehensive analysis showed that:3.0 inch frame performed better in controlling the percentage of large-sized strips than 3.5 inch frame did;rhombic frames were better than hexagon frames in reducing the breakage rate of tobacco leaves;different shapes or sizes of nonadjacent two-link frames can help to improve the threshing quality.展开更多
In this research, the effects of initial moisture content and needed impact energy on threshing of soybean pods were studied. An impact device was built based of pendulum mechanism. In the experiments, threshing perce...In this research, the effects of initial moisture content and needed impact energy on threshing of soybean pods were studied. An impact device was built based of pendulum mechanism. In the experiments, threshing percentage of soybean pod samples were measured at three initial moisture content levels of 16.25% and 35% w.b. and three energy levels of 173,284 and 446 mJ. The results of analysis of variance showed that moisture content and energy have significant effects on the threshing percentage. By increasing impact energy, amount of pod threshing increased. Also in all the energy levels, maximum threshing occurred at minimum moisture. Maximum threshing percentage was 83.4%, which was at 16% moisture content and 446 mJ levels, also minimum threshing percentage was 3.3% which was at 35% moisture content and 174 mJ levels. Soybean pod with higher moisture, contact between its edges of the pod was stronger than lower moisture, so more energy was needed to separate two edges at 35% moisture.展开更多
Two main types of in situ grain harvesttng machine are introduced. The comparison of their working principles and advantages are given. The limitations and prospects for stripper header are discussed.
[Objectives]The paper was to study the occurrence regularity and life history of cigarette beetle Lasioderrma serricorne(Fabricius)in tobacco leaf threshing and redrying workshop.[Methods]With the tobacco leaf threshi...[Objectives]The paper was to study the occurrence regularity and life history of cigarette beetle Lasioderrma serricorne(Fabricius)in tobacco leaf threshing and redrying workshop.[Methods]With the tobacco leaf threshing and redrying workshop as the survey site,the occurrence regularity of L.serricorne was investigated,and the life history table was inferred according to its biological characteristics.The temperature,humidity and duration of tobacco leaf threshing and redrying were simulated in the laboratory to study the survival rate of all states of L.serricorne in this environment.[Results]The lifecycle of L.serricorne in tobacco leaf threshing and redrying workshop was:the overwintering generation pupated in late February;the pupa began to emerge in early March,and reached its peak in late March.The first-generation eggs started hatching in late March,pupated in late May,emerged in early June,and reached the peak eclosion of the first-generation adults in mid-July.The second-generation eggs began to hatch in late July,pupated in mid-August,emerged in late August,and reached the peak eclosion of the second-generation adults in mid-September.The third-generation eggs began to hatch in mid-September;most of the larvae began to overwinter,some pupated in mid-November and survived the winter as pupae,and some pupae emerged to adults.The survival test results of different states of L.serricorne under simulated temperature,humidity and duration in the tobacco leaf threshing and redrying process showed that the mortality rates of eggs in simulated 1,2 and 3 conditions were about 51.22%,90.24% and 100%,and the mortalities of larvae in simulated 1,2 and 3 conditions were about 18.30%,81.25%and 100%,respectively.The mortalities of pupae in simulated 1,2 and 3 conditions were about 69.39%,100% and 100%,and the mortalities of adults in simulated 1,2 and 3 conditions were about 100%,100% and 100%,respectively.[Conclusions]L.serricorne of different states can be killed by appropriately raising the temperature during threshing and redrying.展开更多
Improving the stability of the homogenization process to achieve the homogeneity of tobacco products is one of important targets for the redrying industry.According to the specification for threshing and redrying proc...Improving the stability of the homogenization process to achieve the homogeneity of tobacco products is one of important targets for the redrying industry.According to the specification for threshing and redrying process,a total of 14 indicators in three categories that affect the quality of the threshing and redrying process were selected.Using analytic hierarchy process,combined with expert experiences,a judgment matrix was constructed to conduct consistency test.The weights of indices in production were obtained.This will help in evaluating the actual production quality,finding the weak links of process and adjusting the parameters of the corresponding links in a targeted manner,thereby improving the quality of production process.展开更多
To make up for the gap in the research on high water content maize threshing by airflow,this study took high-speed,low flow,low-speed high flow airflow,and high water content maize ear as the research basis.The variat...To make up for the gap in the research on high water content maize threshing by airflow,this study took high-speed,low flow,low-speed high flow airflow,and high water content maize ear as the research basis.The variation of air flow impacted threshing in numerical simulation,and the variation process of smoke visualization in the threshing area was compared.Taking the maize ear direction,the angle between the maize ear and the air pipe,the diameter of the air pipe,and the flow rate of the air compressor as factors,single-factor and quadratic regression orthogonal rotation combination tests were carried out,and the parameters were optimized.Finally,high-speed photography was used to shoot the maize kernels’shelling process,and movement rules were analyzed from both the front and side views.The results showed that the velocity changes of each section under the numerical simulation are consistent with the flow state changes of smoke.The velocity reached its maximum on the circumference of the maize ear surface and presented a symmetrical distribution.Due to the velocity gradient and pressure gradient difference,the high-speed airflow would entrain the phenomena of the low-speed airflow.When the transverse maize ear,the angle between the maize and the airflow tube)was 45°,the diameter of the airflow tube was 7 mm,the flow rate of the airflow tube was 33 m/s,the loose amount was 10 pieces,the threshed amount was 15 pieces,and the damage rate was below 3%.Through high-speed photography,it was found that the cyclic force circle was destroyed after the maize kernel fell off,the motion of the removed maize kernel was similar to the oblique throwing motion,and the threshing process was carried out in the unit of“arrangement unit”.The threshing process followed the“arrangement law”,and the threshing track was“spiral”.The results of this research can provide ideas for the mechanical design and development of high-moisture-content maize threshing by air.展开更多
The existing discrete element model of wheat plants lacks the glume,which hinders the simulation of the entire threshing process.To address this issue,this paper takes wheat at the harvest stage as the research object...The existing discrete element model of wheat plants lacks the glume,which hinders the simulation of the entire threshing process.To address this issue,this paper takes wheat at the harvest stage as the research object and constructs a complete discrete element model of wheat plants with glumes based on the Hertz-Mindlin with bonding model in the EDEM simulation software.The parameter calibration of wheat glumes discrete element model is studied through collision bounce experiments,slope experiments,and accumulation experiments.The results show that the coefficient of restitution,coefficient of static friction,and coefficient of rolling friction between glume and steel are 0.488,0.625,and 0.048,respectively,and the coefficient of restitution,coefficient of static friction,and coefficient of rolling friction between glume and glume are 0.232,0.966,and 0.059,respectively.The relative errors between the simulation results and the measured values are less than 5%,and the calibration parameters are effective.Based on the structural parameters of the self-developed experiment-bed of tangential axial-flow grain threshing device,a three-dimensional model of the wheat threshing device is established to simulate the whole threshing process of the complete wheat plant,and the bench-scale experiments are carried out with the non-threshing rate as the performance index.The results indicate that the model can completely simulate the separation process of glume and grain and the movement law of different grains,and the relative error of non-threshing rate between the simulation experiments and bench-scale experiments is 4.36%.This further demonstrates that the proposed model can provide a reference for the wheat threshing process research and device performance optimization design.展开更多
This article is concerned with large time behavior of solutions to the Neumann or Dirichlet problem for a class of Newtonian filtration equations ｜x｜λ＋Эt^-Эu=div（｜x｜^k∨u^m）＋｜x｜λ＋ku^p with 0 〈 m 〈...This article is concerned with large time behavior of solutions to the Neumann or Dirichlet problem for a class of Newtonian filtration equations ｜x｜λ＋Эt^-Эu=div（｜x｜^k∨u^m）＋｜x｜λ＋ku^p with 0 〈 m 〈 1,p 〉 1,λ≥0, k ∈ R. An interesting phenomenon is that there exist two thresholds k∞ and kl for the exponent k, such that the critical Fujita exponent pc for p exists and is finite if k E （k∞, k1）, otherwise, pc is infinite or does not exist.展开更多
Wireless sensors networks consist of a number of sensors nodes connected through a wireless network that collect data to be treated locally or relayed to the sink node using multi-hop wireless transmission. Several so...Wireless sensors networks consist of a number of sensors nodes connected through a wireless network that collect data to be treated locally or relayed to the sink node using multi-hop wireless transmission. Several solutions were proposed to minimize the amount of information flowing within the network. Clustering algorithms is one solution and mechanism that enables the creation of sensor’s clusters;each sensor is dominated by elected routers. In order to limit energy consumption, the clustering around the sensor is established: sensors linked to the router transmit relayed data thereafter outward. The number of messages sent and the transmission range are thus reduced. This article tackles this issue by unveiling proposed techniques in the same line of researches and proposing a clustering mechanism based on the amount of energy remaining in the sensors. The simulation results show that proposed method can achieve higher network lifetime by comparison to original LEACH.展开更多
Mechanization of field experiments is the only way to improve crop breeding and seed propagation effects.In order to further clarify and improve the working performance of tapered threshing device for plot breeding,an...Mechanization of field experiments is the only way to improve crop breeding and seed propagation effects.In order to further clarify and improve the working performance of tapered threshing device for plot breeding,and reduce the remaining seeds in the device,the numerical simulation was carried out on the motion process of materials in the longitudinal-axial tapered cylinder threshing and transmission device of the plot wheat breeding combine harvester based on CFD-DEM method.Simulation results showed that,threshing and transmission of particles and short stalks at axial direction could be realized under the influence of air flow.Meanwhile,the material transference and distribution rule and stream field distribution rule of air flow in the threshing and transmission device were obtained,the variations of velocity and displacement of particles and short stalks with time were obtained;the motion trajectories and forms of particles in different types of retention were also studied.At rotating speed of 1300-1600 r/min for the tapered threshing cylinder in the verification test,the particle retention rate in the enclosure was 0-0.13%,while in the simulation the particle retention rate in the enclosure was 0-0.11%,only a 0.02%difference between them.The results proved a favorable feasibility to simulate the working performance of the tapered threshing and transmission device for plot breeding through gas-solid coupling method.展开更多
In order to further clarify and improve the working performance of separating cleaning device of flax threshing material,and study the motion law and characteristics of components of flax threshing material,in this pa...In order to further clarify and improve the working performance of separating cleaning device of flax threshing material,and study the motion law and characteristics of components of flax threshing material,in this paper,numerical simulation was carried out on the separating cleaning process of flax threshing material based on CFD-DEM method.Simulation results showed that the components of flax threshing material were separated and cleaned under the influence of airflow field,meanwhile,variation curves of quantity and mean velocity of flax seeds in the separating cleaning system were obtained.By referring to streamline distribution of gas-solid coupling,the quantity variation law of components of flax threshing material with time was explored and their motion curves and variation tendency of average velocity were studied.Verification test results showed that the cleaning rate of separating cleaning device for flax threshing material was 92.66%with 1.58%of total separation loss.Compared with simulation results,the test results were 1.34%and 0.93%lower,showing that it is feasible to apply the gas-solid coupling theory and method to simulate the separating and cleaning operation of flax threshing material.展开更多
Threshing is the most important function of grain harvester.Grain loss and damage in harvesting are significantly related to threshing theory and technology.There are four kinds of threshing principles including impac...Threshing is the most important function of grain harvester.Grain loss and damage in harvesting are significantly related to threshing theory and technology.There are four kinds of threshing principles including impact,rubbing,combing and grinding.Four types of contact models between grain and threshing components have been constructed correspondently.Grain damage can be regarded as a function of peripheral velocity and contact pattern of impacting.Grain loss can be regarded as a function of contact pattern of rasp bars.Grain loss coming from cleaning and separation in the subsequent process of combing threshing was significantly decreased.Tangential and axial threshing technologies have been applied in grain threshing system widely.It showed that in the combined application,tangential rolls are used to accelerate grain flow,and axial rolls are used to increase threshing quality especially lower loss and damage.Conical concave may take the place of the traditional cylindrical one.With the development of sensor technology and communication technology,intelligent harvesting robot and automatic threshing system will be integrated together to improve grain quality and operation comfort.展开更多
In order to further clarify and improve the working performance of separating cleaner for flax threshing materials,and study the migration law and characteristics of components of flax threshing materials during separ...In order to further clarify and improve the working performance of separating cleaner for flax threshing materials,and study the migration law and characteristics of components of flax threshing materials during separating and cleaning,in this paper,a gas-solid coupling simulation model was established on the separation cleaner for flax threshing materials and a numerical simulation was carried out on the separating and cleaning process.Simulation results showed that,the separating and cleaning effect of the components of flax threshing materials was good under the air-and-screen gas-solid coupling flow field.Meanwhile,the form distribution and the vector distribution of air volume and velocity of flax threshing materials in the air-and-screen devices were obtained.By referring to the migration trajectories of the flax threshing materials in the vibration sieve device,double channel residue collection device and dust absorber,the volume variation,motion trajectories and variation of migration velocity of the components of flax threshing materials over time in different regions were explored.Verification test results showed that,the content impurity rate of the separation cleaner for flax threshing materials was 2.06%,and loss rate in cleaning was 3.08%.Compared with simulation results,the verification test results were 1.23%and 0.42%higher,showing that the established discrete element model on the flax threshing materials and parameter setting were basically feasible.The verification test also verified the correctness of the simulation results of the separating and cleaning process of the flax threshing materials based on gas-solid coupling theory and the feasibility of the research method.展开更多
In order to explore the aerodynamics characteristics of flax threshing material,and accurately obtain the movement trajectory of the material of each component in air-screen cleaning,the suspension velocities of flax ...In order to explore the aerodynamics characteristics of flax threshing material,and accurately obtain the movement trajectory of the material of each component in air-screen cleaning,the suspension velocities of flax grains,capsules,short stalks and capsule husks at different stages were measured by means of the suspension velocity device.The experimental results showed that the suspension velocity range was 4.55-8.64 m/s for flax grains,6.46-10.90 m/s for flax capsules,3.23-7.75 m/s for flax short stalks,and 1.06-4.21 m/s for flax capsule shells.Based on the experimental results,the overall interval distribution of each component of flax threshing material and the separation characteristics were discussed and the discrete element model of each component of the flax threshing material was established.Through simulation measurement of angle of repose of the material and the sliding friction angle with steel,the reliability of the established model was verified.The gas-solid coupling method was used to simulate the suspension velocity of each component of the flax threshing material,and the suspension velocity of the four components of flax threshing material was obtained.The simulation measurement results were within the actual measurement range,showing that the test results were basically in line with the simulation results.The simulation on the suspension velocity of different components of flax threshing material based on gas-solid coupling had high precision degree.Therefore,the feasibility of the suspension velocity of the flax threshing material measured in the simulation test based on CFD-DEM coupling was verified.展开更多
Complex field environments,diverse crop conditions,and varying feed rate fluctuations commonly result in a decline in the threshing performance and the clogging of the threshing cylinder for maize harvesters.In order ...Complex field environments,diverse crop conditions,and varying feed rate fluctuations commonly result in a decline in the threshing performance and the clogging of the threshing cylinder for maize harvesters.In order to overcome these problems,an electric-hydraulic concave clearance automatic control system for the threshing unit was developed based on the maize feed rate monitoring,which can automatically realize the best match between the concave clearance and diverse feed rates during harvesting.The threshing performance of the electric-hydraulic control system was evaluated for varying and uneven maize feed rate fluctuations,such as the feed rate increased(6-8-10 kg/s),the feed rate decreased after an increase(6-10-8 kg/s,8-10-6 kg/s),the feed rate increased after a decrease(8-6-10 kg/s,10-6-8 kg/s),and the feed rate decreased(10-8-6 kg/s).In particular,the threshing rotor shaft peak torque,the range of threshing rotor shaft torque,the rate of broken grains(BGR),and the rate of unthreshed grains(UGR)with and without the electric-hydraulic control system were tested.Treatments with the electric-hydraulic control system were adjustable concave clearance with the value of 45 mm,50 mm,and 55 mm.Treatments without the electric-hydraulic control system were constant concave clearance(50 mm).Results demonstrate that the threshing unit with the electric-hydraulic control system outperformed the one without the electric-hydraulic control system,with threshing rotor peak torque,the range of threshing rotor axis torque,the BGR,and the UGR decreasing by 18.38%,38.27%,2.08%,and 0.10%,respectively.Moreover,the rate of broken grains was lower than 5.00%,better than the national standard.Thus,the feed rate fluctuations and timely adjustment of the concave clearance were able to avoid blocking the rotor and improve the threshing performance compared to the constant concave clearance.展开更多
Kernel broken rate is an important index to evaluate the maize kernel direct harvesting quality.In view of the problem of the high kernel broken rate in the present maize harvester,a new threshing cylinder was designe...Kernel broken rate is an important index to evaluate the maize kernel direct harvesting quality.In view of the problem of the high kernel broken rate in the present maize harvester,a new threshing cylinder was designed in this study.This device utilized rasp bar to achieve low damaged maize ears threshing.In order to determine the structure and working parameters of threshing device,the“crop-crop”contact model and the“crop-mechanical”interaction system were established and analyzed based on the discrete element method first,and the mathematical expressions of the related kinematic response of maize kernel under the external force were obtained.Then,the structure parameters of rasp bar were studied through EDEM simulation experiment,and the working parameters were determined through test-bed experiment.Finally,the simulation experiment results and test-bed experiment results were verified through field experiment.The results showed that when the threshing cylinder speed was 356 r/min,the concave clearance was 40 mm,the installation distance of rasp bar was 250 mm with 50Mn steel,and the feeding amount was 8 kg/s,the kernel broken rate was 1.93%,which satisfied the requirements of maize harvest standard.This study proved that the DEM(Discrete Element Method)can be adopted to guide the optimization design of mechanical structure,and it has certain value for the research and development of operation equipment of other agricultural crops.展开更多
Rosemary(Rosmarinus officinalis L.)is an important perennial medicinal and aromatic plant belonging to the Lamiaceae family.Rosemary is widely produced in Turkey for its oil which can be extracted from the plants when...Rosemary(Rosmarinus officinalis L.)is an important perennial medicinal and aromatic plant belonging to the Lamiaceae family.Rosemary is widely produced in Turkey for its oil which can be extracted from the plants when flowers are in buds.In Turkey,a significant amount of domestic and foreign trade of rosemary is conducted.In 2018-2020,2088 t of rosemary plants were imported,while in the same years 2077 t were exported.In this study,the performance indexes of a threshing and separating unit designed according to the physicomechanical properties of the rosemary were determined.The operating parameters of the machine were determined at three different moisture contents and adjusted according to the harvest moisture values.The threshing efficiency,work efficiency,power requirement,and specific energy consumption values of the threshing unit were determined,while separating efficiency,work efficiency and specific power consumption of separating unit of the developed system were determined.According to the study results,the threshing efficiency of the rosemary plant varied between 44.00%and 96.97%.Work efficiency of the thresher varied between 1.18 and 15.34 kg/h.Power requirements and specific energy consumption of the threshing unit were obtained as 0.19-1.05 kW and 0.02-0.37 kW·h/h,respectively.On the other hand,the separating efficiency of the separating unit for the rosemary plant varied between 44.27%and 85.24%.Maximum and minimum values of work efficiency were found as 0.75 kg/h and 5.52 kg/h.Specific power consumption of the unit ranged from 3.95 to 39.95 kW/kg.展开更多
Aiming at the problems of stalks winding and poor threshing performance in the process of mechanical harvesting of oats,a type of threshing and crushing experimental device was designed.The device was composed of a be...Aiming at the problems of stalks winding and poor threshing performance in the process of mechanical harvesting of oats,a type of threshing and crushing experimental device was designed.The device was composed of a belt conveyor,a tangential-flow threshing drum,an axial-flow threshing drum,a high-speed camera and a testing device.According to a regression orthogonal test method,using the rotation speed of the axial-flow drum,the horizontal center distance,and the vertical height difference of the two threshing drums as experimental factors;using the mass fraction of long stalks and the threshing rate as experimental indexes,a mathematical regression model of factors and indexes was established,and combined parameters were analyzed for the threshing quality and crushing ability.Experimental results showed that this device had the best crushing performance when the rotation speed of the axial-flow drum was 850 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 10 mm,and this device had optimal threshing performance when the rotation speed of the axial-flow drum was 760 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 20 mm.The parameters were optimized by Design-Expert 11 to obtain an optimization result that the rotation speed of the axial-flow drum was 800 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 10 mm.A verification experiment was carried out by using a high-speed camera,and the two groups of parameters were selected for a comparative experiment.Images of material movement between the two threshing drums were captured by the high-speed camera.Experimental results showed that the optimized parameters were beneficial to improving the threshing performance and anti-winding performance of the oat threshing process.This study provides a technical basis for the research and development of oat combine harvesters.展开更多
文摘This study was conducted to further classify threshed strips, so as to broaden the usable range of raw material and facilitate the effective utilization of to- bacco resource. During the threshing and redwing process, various process param- eters including the rotating speeds of threshing drums of threshing machioe, draught fans and fling drums were scientifically and rationally set according to the actual quality of the raw material. According to the characteristic that strips with close in- herent quality have basically the same specific gravity and leaf thickness, the strips from each discharge hole were accurately evaluated, and classified, followed by redrying and packaging. The results showed that the threshing and separating pro- cedure could improve the separating effect and precision according to tobacco qual- ity, so as to satisfy the separation and classification requirements for tobacco.
基金supported by the earmarked fund for China Agriculture Research System(CARS-02-10)the Special Fund for Agro-scientific Research in the Public Interest,China(201303002)the National Natural Science Foundation of China(31771891)
文摘Mechanical threshing used when preparing maize seeds for planting subjects seed to damage and reduces seed quality.The purpose of this study was to assess the effect of mechanical threshing on the quality of maize seed threshed at different moisture contents(MCs).Seeds of dent maize JK968 and flint maize DD2 were threshed at 12,15,18,21,and 24% MC.The damage degree was determined by iodine staining,and seed vigor was assessed by standard germination(SG),cold test germination(CTG),accelerated aging germination(AAG),seedling emergence rate,and seedling root and shoot length.The results showed that the damage percentage increased,and the seed vigor parameters decreased with increasing seed MC during threshing in both cultivars.For obtaining high seed quality,indicated by at least 90,85,and 80% of SG,AAG,and CTG,respectively,JK 968 and DD2 should be threshed at MC lower than 15 and 18%,respectively.Furthermore,the damage mainly occurred in the apical part of seeds,irrespective of the threshing MC in both cultivars.When the embryo was damaged,seedling emergence rates were significantly reduced with great influence on shoot length.Damage to the endosperm resulted in little effect on seedling performance.Flint maize DD2 was more tolerant to mechanical threshing than dent maize JK968.These results provided technical reference for the production and processing of high vigor maize seeds.
文摘This paper focused on the influence of the shape and size of threshing frames as well as the grades of tobacco leaves on the structure of threshed leaves.The testing tobacco leaves all came from the hilly ecological region of Nanling and belonged to burnt sweet,alcoholic sweet and scent category.The comprehensive evaluating value S was taken as the test index.Results showed that,without considering the influence of tobacco grade on leaf structure,the shapes of first-stage thresher five-link frames were all hexagons,and the combination with the sizes of 3.5,3.0,3.5,3.0,3.0 inches had the highest evaluating value S of 2.49.For tobacco grade C2FH,the shapes of first-stage thresher five-link frames were also hexagons,and the evaluating value S reached the highest value of 3.40 with sizes of 3.5,3.0,3.5,3.0,3.0 inches.Comprehensive analysis showed that:3.0 inch frame performed better in controlling the percentage of large-sized strips than 3.5 inch frame did;rhombic frames were better than hexagon frames in reducing the breakage rate of tobacco leaves;different shapes or sizes of nonadjacent two-link frames can help to improve the threshing quality.
文摘In this research, the effects of initial moisture content and needed impact energy on threshing of soybean pods were studied. An impact device was built based of pendulum mechanism. In the experiments, threshing percentage of soybean pod samples were measured at three initial moisture content levels of 16.25% and 35% w.b. and three energy levels of 173,284 and 446 mJ. The results of analysis of variance showed that moisture content and energy have significant effects on the threshing percentage. By increasing impact energy, amount of pod threshing increased. Also in all the energy levels, maximum threshing occurred at minimum moisture. Maximum threshing percentage was 83.4%, which was at 16% moisture content and 446 mJ levels, also minimum threshing percentage was 3.3% which was at 35% moisture content and 174 mJ levels. Soybean pod with higher moisture, contact between its edges of the pod was stronger than lower moisture, so more energy was needed to separate two edges at 35% moisture.
文摘Two main types of in situ grain harvesttng machine are introduced. The comparison of their working principles and advantages are given. The limitations and prospects for stripper header are discussed.
基金Supported by Science and Technology Project of China Tobacco Guizhou Provincial Corporation(201918)Guizhou Province Academic Pioneer and Academic Pioneer Construction。
文摘[Objectives]The paper was to study the occurrence regularity and life history of cigarette beetle Lasioderrma serricorne(Fabricius)in tobacco leaf threshing and redrying workshop.[Methods]With the tobacco leaf threshing and redrying workshop as the survey site,the occurrence regularity of L.serricorne was investigated,and the life history table was inferred according to its biological characteristics.The temperature,humidity and duration of tobacco leaf threshing and redrying were simulated in the laboratory to study the survival rate of all states of L.serricorne in this environment.[Results]The lifecycle of L.serricorne in tobacco leaf threshing and redrying workshop was:the overwintering generation pupated in late February;the pupa began to emerge in early March,and reached its peak in late March.The first-generation eggs started hatching in late March,pupated in late May,emerged in early June,and reached the peak eclosion of the first-generation adults in mid-July.The second-generation eggs began to hatch in late July,pupated in mid-August,emerged in late August,and reached the peak eclosion of the second-generation adults in mid-September.The third-generation eggs began to hatch in mid-September;most of the larvae began to overwinter,some pupated in mid-November and survived the winter as pupae,and some pupae emerged to adults.The survival test results of different states of L.serricorne under simulated temperature,humidity and duration in the tobacco leaf threshing and redrying process showed that the mortality rates of eggs in simulated 1,2 and 3 conditions were about 51.22%,90.24% and 100%,and the mortalities of larvae in simulated 1,2 and 3 conditions were about 18.30%,81.25%and 100%,respectively.The mortalities of pupae in simulated 1,2 and 3 conditions were about 69.39%,100% and 100%,and the mortalities of adults in simulated 1,2 and 3 conditions were about 100%,100% and 100%,respectively.[Conclusions]L.serricorne of different states can be killed by appropriately raising the temperature during threshing and redrying.
基金Science and Technology Foundation of Hunan Branch of China National Tobacco Corporation(HN2020KJ14,HN2020KJ17).
文摘Improving the stability of the homogenization process to achieve the homogeneity of tobacco products is one of important targets for the redrying industry.According to the specification for threshing and redrying process,a total of 14 indicators in three categories that affect the quality of the threshing and redrying process were selected.Using analytic hierarchy process,combined with expert experiences,a judgment matrix was constructed to conduct consistency test.The weights of indices in production were obtained.This will help in evaluating the actual production quality,finding the weak links of process and adjusting the parameters of the corresponding links in a targeted manner,thereby improving the quality of production process.
基金funded by the National Natural Science Foundation of China(Grant No.52275245)the Henan Science and Technology Research Project(Grant No.222103810041)。
文摘To make up for the gap in the research on high water content maize threshing by airflow,this study took high-speed,low flow,low-speed high flow airflow,and high water content maize ear as the research basis.The variation of air flow impacted threshing in numerical simulation,and the variation process of smoke visualization in the threshing area was compared.Taking the maize ear direction,the angle between the maize ear and the air pipe,the diameter of the air pipe,and the flow rate of the air compressor as factors,single-factor and quadratic regression orthogonal rotation combination tests were carried out,and the parameters were optimized.Finally,high-speed photography was used to shoot the maize kernels’shelling process,and movement rules were analyzed from both the front and side views.The results showed that the velocity changes of each section under the numerical simulation are consistent with the flow state changes of smoke.The velocity reached its maximum on the circumference of the maize ear surface and presented a symmetrical distribution.Due to the velocity gradient and pressure gradient difference,the high-speed airflow would entrain the phenomena of the low-speed airflow.When the transverse maize ear,the angle between the maize and the airflow tube)was 45°,the diameter of the airflow tube was 7 mm,the flow rate of the airflow tube was 33 m/s,the loose amount was 10 pieces,the threshed amount was 15 pieces,and the damage rate was below 3%.Through high-speed photography,it was found that the cyclic force circle was destroyed after the maize kernel fell off,the motion of the removed maize kernel was similar to the oblique throwing motion,and the threshing process was carried out in the unit of“arrangement unit”.The threshing process followed the“arrangement law”,and the threshing track was“spiral”.The results of this research can provide ideas for the mechanical design and development of high-moisture-content maize threshing by air.
基金supported by the Major Scientific and Technological Project of Henan Province(Grant No.231100110200)the Open Subject of State Key Laboratory of Intelligent Agricultural Power Equipment(Grant No.SKLIAPE2023015)the Open Subject of Key Laboratory of Agricultural Equipment Technology for Hilly and Mountainous Areas(Grant No.2023KLOP03).
文摘The existing discrete element model of wheat plants lacks the glume,which hinders the simulation of the entire threshing process.To address this issue,this paper takes wheat at the harvest stage as the research object and constructs a complete discrete element model of wheat plants with glumes based on the Hertz-Mindlin with bonding model in the EDEM simulation software.The parameter calibration of wheat glumes discrete element model is studied through collision bounce experiments,slope experiments,and accumulation experiments.The results show that the coefficient of restitution,coefficient of static friction,and coefficient of rolling friction between glume and steel are 0.488,0.625,and 0.048,respectively,and the coefficient of restitution,coefficient of static friction,and coefficient of rolling friction between glume and glume are 0.232,0.966,and 0.059,respectively.The relative errors between the simulation results and the measured values are less than 5%,and the calibration parameters are effective.Based on the structural parameters of the self-developed experiment-bed of tangential axial-flow grain threshing device,a three-dimensional model of the wheat threshing device is established to simulate the whole threshing process of the complete wheat plant,and the bench-scale experiments are carried out with the non-threshing rate as the performance index.The results indicate that the model can completely simulate the separation process of glume and grain and the movement law of different grains,and the relative error of non-threshing rate between the simulation experiments and bench-scale experiments is 4.36%.This further demonstrates that the proposed model can provide a reference for the wheat threshing process research and device performance optimization design.
文摘This article is concerned with large time behavior of solutions to the Neumann or Dirichlet problem for a class of Newtonian filtration equations ｜x｜λ＋Эt^-Эu=div（｜x｜^k∨u^m）＋｜x｜λ＋ku^p with 0 〈 m 〈 1,p 〉 1,λ≥0, k ∈ R. An interesting phenomenon is that there exist two thresholds k∞ and kl for the exponent k, such that the critical Fujita exponent pc for p exists and is finite if k E （k∞, k1）, otherwise, pc is infinite or does not exist.
文摘Wireless sensors networks consist of a number of sensors nodes connected through a wireless network that collect data to be treated locally or relayed to the sink node using multi-hop wireless transmission. Several solutions were proposed to minimize the amount of information flowing within the network. Clustering algorithms is one solution and mechanism that enables the creation of sensor’s clusters;each sensor is dominated by elected routers. In order to limit energy consumption, the clustering around the sensor is established: sensors linked to the router transmit relayed data thereafter outward. The number of messages sent and the transmission range are thus reduced. This article tackles this issue by unveiling proposed techniques in the same line of researches and proposing a clustering mechanism based on the amount of energy remaining in the sensors. The simulation results show that proposed method can achieve higher network lifetime by comparison to original LEACH.
基金The authors acknowledge that this work was financially supported by China Agriculture Research System(CARS-14-1-28)Discipline construction fund project of Gansu Agricultural University(GAU-XKJS-2018-189)National Natural Science Foundation of China(Grant No.51365003).
文摘Mechanization of field experiments is the only way to improve crop breeding and seed propagation effects.In order to further clarify and improve the working performance of tapered threshing device for plot breeding,and reduce the remaining seeds in the device,the numerical simulation was carried out on the motion process of materials in the longitudinal-axial tapered cylinder threshing and transmission device of the plot wheat breeding combine harvester based on CFD-DEM method.Simulation results showed that,threshing and transmission of particles and short stalks at axial direction could be realized under the influence of air flow.Meanwhile,the material transference and distribution rule and stream field distribution rule of air flow in the threshing and transmission device were obtained,the variations of velocity and displacement of particles and short stalks with time were obtained;the motion trajectories and forms of particles in different types of retention were also studied.At rotating speed of 1300-1600 r/min for the tapered threshing cylinder in the verification test,the particle retention rate in the enclosure was 0-0.13%,while in the simulation the particle retention rate in the enclosure was 0-0.11%,only a 0.02%difference between them.The results proved a favorable feasibility to simulate the working performance of the tapered threshing and transmission device for plot breeding through gas-solid coupling method.
基金The authors acknowledge that this work was financially supported by China Agriculture Research System(CARS-14-1-28)Discipline construction fund project of Gansu Agricultural University(GAU-XKJS-2018-189).
文摘In order to further clarify and improve the working performance of separating cleaning device of flax threshing material,and study the motion law and characteristics of components of flax threshing material,in this paper,numerical simulation was carried out on the separating cleaning process of flax threshing material based on CFD-DEM method.Simulation results showed that the components of flax threshing material were separated and cleaned under the influence of airflow field,meanwhile,variation curves of quantity and mean velocity of flax seeds in the separating cleaning system were obtained.By referring to streamline distribution of gas-solid coupling,the quantity variation law of components of flax threshing material with time was explored and their motion curves and variation tendency of average velocity were studied.Verification test results showed that the cleaning rate of separating cleaning device for flax threshing material was 92.66%with 1.58%of total separation loss.Compared with simulation results,the test results were 1.34%and 0.93%lower,showing that it is feasible to apply the gas-solid coupling theory and method to simulate the separating and cleaning operation of flax threshing material.
基金This work was supported by the National Natural Science Foundation of China(51705193)National Key Research and Development Project(2017YFD0700302)the Science and Technology Development Project of Jilin Province(20170204016NY).
文摘Threshing is the most important function of grain harvester.Grain loss and damage in harvesting are significantly related to threshing theory and technology.There are four kinds of threshing principles including impact,rubbing,combing and grinding.Four types of contact models between grain and threshing components have been constructed correspondently.Grain damage can be regarded as a function of peripheral velocity and contact pattern of impacting.Grain loss can be regarded as a function of contact pattern of rasp bars.Grain loss coming from cleaning and separation in the subsequent process of combing threshing was significantly decreased.Tangential and axial threshing technologies have been applied in grain threshing system widely.It showed that in the combined application,tangential rolls are used to accelerate grain flow,and axial rolls are used to increase threshing quality especially lower loss and damage.Conical concave may take the place of the traditional cylindrical one.With the development of sensor technology and communication technology,intelligent harvesting robot and automatic threshing system will be integrated together to improve grain quality and operation comfort.
基金The authors acknowledge that this work was financially supported by China Agriculture Research System of MOF and MARA(Grant No.CARS-14-1-28)Fuxi Young Talents Fund of Gansu Agricultural University(Grant No.Gaufx-03Y01)Key Research and Development Project of Gansu Province(Grant No.20YF3WA019).
文摘In order to further clarify and improve the working performance of separating cleaner for flax threshing materials,and study the migration law and characteristics of components of flax threshing materials during separating and cleaning,in this paper,a gas-solid coupling simulation model was established on the separation cleaner for flax threshing materials and a numerical simulation was carried out on the separating and cleaning process.Simulation results showed that,the separating and cleaning effect of the components of flax threshing materials was good under the air-and-screen gas-solid coupling flow field.Meanwhile,the form distribution and the vector distribution of air volume and velocity of flax threshing materials in the air-and-screen devices were obtained.By referring to the migration trajectories of the flax threshing materials in the vibration sieve device,double channel residue collection device and dust absorber,the volume variation,motion trajectories and variation of migration velocity of the components of flax threshing materials over time in different regions were explored.Verification test results showed that,the content impurity rate of the separation cleaner for flax threshing materials was 2.06%,and loss rate in cleaning was 3.08%.Compared with simulation results,the verification test results were 1.23%and 0.42%higher,showing that the established discrete element model on the flax threshing materials and parameter setting were basically feasible.The verification test also verified the correctness of the simulation results of the separating and cleaning process of the flax threshing materials based on gas-solid coupling theory and the feasibility of the research method.
基金supported by China Agriculture Research System of MOF and MARA(Grant No.CARS-14-1-28)Fuxi Young Talents Fund of Gansu Agricultural University(Gaufx-03Y01)Key Research and Development Program of Gansu Province(20YF3WA019).
文摘In order to explore the aerodynamics characteristics of flax threshing material,and accurately obtain the movement trajectory of the material of each component in air-screen cleaning,the suspension velocities of flax grains,capsules,short stalks and capsule husks at different stages were measured by means of the suspension velocity device.The experimental results showed that the suspension velocity range was 4.55-8.64 m/s for flax grains,6.46-10.90 m/s for flax capsules,3.23-7.75 m/s for flax short stalks,and 1.06-4.21 m/s for flax capsule shells.Based on the experimental results,the overall interval distribution of each component of flax threshing material and the separation characteristics were discussed and the discrete element model of each component of the flax threshing material was established.Through simulation measurement of angle of repose of the material and the sliding friction angle with steel,the reliability of the established model was verified.The gas-solid coupling method was used to simulate the suspension velocity of each component of the flax threshing material,and the suspension velocity of the four components of flax threshing material was obtained.The simulation measurement results were within the actual measurement range,showing that the test results were basically in line with the simulation results.The simulation on the suspension velocity of different components of flax threshing material based on gas-solid coupling had high precision degree.Therefore,the feasibility of the suspension velocity of the flax threshing material measured in the simulation test based on CFD-DEM coupling was verified.
基金This study was financially supported by the China Agriculture Research System of MOF and MARA,Mount Tai Industry Leading Talents Project(LJNY201708)the Soil-Machine-Plant Key Laboratory of the Ministry of Agriculture of China.
文摘Complex field environments,diverse crop conditions,and varying feed rate fluctuations commonly result in a decline in the threshing performance and the clogging of the threshing cylinder for maize harvesters.In order to overcome these problems,an electric-hydraulic concave clearance automatic control system for the threshing unit was developed based on the maize feed rate monitoring,which can automatically realize the best match between the concave clearance and diverse feed rates during harvesting.The threshing performance of the electric-hydraulic control system was evaluated for varying and uneven maize feed rate fluctuations,such as the feed rate increased(6-8-10 kg/s),the feed rate decreased after an increase(6-10-8 kg/s,8-10-6 kg/s),the feed rate increased after a decrease(8-6-10 kg/s,10-6-8 kg/s),and the feed rate decreased(10-8-6 kg/s).In particular,the threshing rotor shaft peak torque,the range of threshing rotor shaft torque,the rate of broken grains(BGR),and the rate of unthreshed grains(UGR)with and without the electric-hydraulic control system were tested.Treatments with the electric-hydraulic control system were adjustable concave clearance with the value of 45 mm,50 mm,and 55 mm.Treatments without the electric-hydraulic control system were constant concave clearance(50 mm).Results demonstrate that the threshing unit with the electric-hydraulic control system outperformed the one without the electric-hydraulic control system,with threshing rotor peak torque,the range of threshing rotor axis torque,the BGR,and the UGR decreasing by 18.38%,38.27%,2.08%,and 0.10%,respectively.Moreover,the rate of broken grains was lower than 5.00%,better than the national standard.Thus,the feed rate fluctuations and timely adjustment of the concave clearance were able to avoid blocking the rotor and improve the threshing performance compared to the constant concave clearance.
基金This work was financially supported in part by the National Natural Science Foundation of China(Grant No.52175258)the Major Scientific and Technological Innovation Projects of Shandong Province(Grant No.2018CXGC0217).
文摘Kernel broken rate is an important index to evaluate the maize kernel direct harvesting quality.In view of the problem of the high kernel broken rate in the present maize harvester,a new threshing cylinder was designed in this study.This device utilized rasp bar to achieve low damaged maize ears threshing.In order to determine the structure and working parameters of threshing device,the“crop-crop”contact model and the“crop-mechanical”interaction system were established and analyzed based on the discrete element method first,and the mathematical expressions of the related kinematic response of maize kernel under the external force were obtained.Then,the structure parameters of rasp bar were studied through EDEM simulation experiment,and the working parameters were determined through test-bed experiment.Finally,the simulation experiment results and test-bed experiment results were verified through field experiment.The results showed that when the threshing cylinder speed was 356 r/min,the concave clearance was 40 mm,the installation distance of rasp bar was 250 mm with 50Mn steel,and the feeding amount was 8 kg/s,the kernel broken rate was 1.93%,which satisfied the requirements of maize harvest standard.This study proved that the DEM(Discrete Element Method)can be adopted to guide the optimization design of mechanical structure,and it has certain value for the research and development of operation equipment of other agricultural crops.
基金supported a part of by the TUBITAK-3501-National Young Researchers Career Development Program(CAREER)the Determination of Threshing and Separation System Parameters of Some Medicinal Aromatic Plants and Development of Prototype(Grant No.111O179).
文摘Rosemary(Rosmarinus officinalis L.)is an important perennial medicinal and aromatic plant belonging to the Lamiaceae family.Rosemary is widely produced in Turkey for its oil which can be extracted from the plants when flowers are in buds.In Turkey,a significant amount of domestic and foreign trade of rosemary is conducted.In 2018-2020,2088 t of rosemary plants were imported,while in the same years 2077 t were exported.In this study,the performance indexes of a threshing and separating unit designed according to the physicomechanical properties of the rosemary were determined.The operating parameters of the machine were determined at three different moisture contents and adjusted according to the harvest moisture values.The threshing efficiency,work efficiency,power requirement,and specific energy consumption values of the threshing unit were determined,while separating efficiency,work efficiency and specific power consumption of separating unit of the developed system were determined.According to the study results,the threshing efficiency of the rosemary plant varied between 44.00%and 96.97%.Work efficiency of the thresher varied between 1.18 and 15.34 kg/h.Power requirements and specific energy consumption of the threshing unit were obtained as 0.19-1.05 kW and 0.02-0.37 kW·h/h,respectively.On the other hand,the separating efficiency of the separating unit for the rosemary plant varied between 44.27%and 85.24%.Maximum and minimum values of work efficiency were found as 0.75 kg/h and 5.52 kg/h.Specific power consumption of the unit ranged from 3.95 to 39.95 kW/kg.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFD0701802)the Subject of Educational Science Planning in Henan Province(Grant No.2020YB0265).
文摘Aiming at the problems of stalks winding and poor threshing performance in the process of mechanical harvesting of oats,a type of threshing and crushing experimental device was designed.The device was composed of a belt conveyor,a tangential-flow threshing drum,an axial-flow threshing drum,a high-speed camera and a testing device.According to a regression orthogonal test method,using the rotation speed of the axial-flow drum,the horizontal center distance,and the vertical height difference of the two threshing drums as experimental factors;using the mass fraction of long stalks and the threshing rate as experimental indexes,a mathematical regression model of factors and indexes was established,and combined parameters were analyzed for the threshing quality and crushing ability.Experimental results showed that this device had the best crushing performance when the rotation speed of the axial-flow drum was 850 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 10 mm,and this device had optimal threshing performance when the rotation speed of the axial-flow drum was 760 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 20 mm.The parameters were optimized by Design-Expert 11 to obtain an optimization result that the rotation speed of the axial-flow drum was 800 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 10 mm.A verification experiment was carried out by using a high-speed camera,and the two groups of parameters were selected for a comparative experiment.Images of material movement between the two threshing drums were captured by the high-speed camera.Experimental results showed that the optimized parameters were beneficial to improving the threshing performance and anti-winding performance of the oat threshing process.This study provides a technical basis for the research and development of oat combine harvesters.
