In this paper,the gas and seed flow characters in the air-blowing seed metering device are investigated by using the coupled computational fluid dynamics and discrete element method(CFD-DEM)in three dimensions(3D).The...In this paper,the gas and seed flow characters in the air-blowing seed metering device are investigated by using the coupled computational fluid dynamics and discrete element method(CFD-DEM)in three dimensions(3D).The method of establishing boundary model based on the computer-aided design(CAD)drawing,has been used to build the boundary model of seed metering device.The 3D laser scanning technique and multi-element method are adopted to establish the particle model.Through a combined numerical and experimental effort,using 3D CFD-DEM software,which is based on the in-house codes,the mechanisms governing the gas and solid dynamic behaviors in the seed metering device have been studied.The gas velocity field and the effect of different rotational speeds and air pressures on the seeding performance and particle velocity have been studied,similar agreements between numerical and experimental results are gained.This reveals that the 3D CFD-DEM model established is able to predict the performance of the air-blowing seed metering device.It can be used to design and optimize the air-blowing seed metering device and other similar agriculture devices.展开更多
Based on the mechanical and physical properties study of forage grass seeds, multi-line with one-device type metering device was designed. It was composed of adjustable screw, stirrer, metering device housing and cent...Based on the mechanical and physical properties study of forage grass seeds, multi-line with one-device type metering device was designed. It was composed of adjustable screw, stirrer, metering device housing and central metering sheave and so on. The sowing rate can be set by turning the screw to change the working length of the central metering sheave relative to the metering device housing. The stirrer inside of the sheave housing is used to prevent seeds overhead. And metering of different sizes of seed is adjusted by changing the position of internal components of the slot wheel mechanism. Innovative design on the structure of the central metering sheave was finished. According to the structure parameters and physical characteristic parameters, different seed sowing rate of per hectares was calculated. And then the working length scale of the central metering groove wheel was made. And there is a one-to-one correspondence between scale values and sowing quantity per hectare of different kinds of seed.展开更多
There are many design parameters in precision planters to be considered such as cell diameter, peripheral speed of roller, number of cells, manner of feeding seeds into cell and travel speed. In precision planters eac...There are many design parameters in precision planters to be considered such as cell diameter, peripheral speed of roller, number of cells, manner of feeding seeds into cell and travel speed. In precision planters each cell must contain only one seed. Therefore, sliding the seed to the cell is important and depends on several parameters such as seed repose angle, seed dimensions and physics of cell. To help the seed to repose in the cell, making a groove on the roller would be very useful. Dimensions of this groove are very important and are considered as basic design parameters. This research was performed to determine some design parameters such as roller speed, travel speed, length and depth of groove for tomato seeds precision planting. In this regard, seeds with a diameter of 4 mm were used. The range of variation was based on calculations obtained. A roller with 42 mm width, 118 mm diameter and 15 cells on the surface was used in the experiment. For each cell, a triangular groove was created on the roller. The groove depth varied from zero at the beginning to the maximum value where the groove connected to the cell. The test unit had a continued and wide belt with 1 l m length. In each replication, planter worked for 20 s to reach a stable state. Thereafter, seeds were allowed to drop on the grease belt. Number of seeds and their spacing were measured on the 4.5 m of the belt. Results showed that the roller speed of 41.5 rpm, the planter travel speed of approximately 1 km/h, groove length of 6-8 mm and groove depth of 1.5 mm can improve planter performance for tomato pelleted seed.展开更多
The automation technology of electric energy measurement covers all levels of electric energy measurement points. The electric energy data acquisition of power users has realized remote automatic acquisition. The tool...The automation technology of electric energy measurement covers all levels of electric energy measurement points. The electric energy data acquisition of power users has realized remote automatic acquisition. The tool for remote automatic collection of electric energy data is various metering automation terminals installed on the site. The data transmission of the automation terminal depends on various communication channels. When the field signal strength is insufficient and the communication module of the metering automation terminal cannot work normally, the terminal is offline and the data collection fails. At this time, it is necessary to solve the problem of insufficient signal through other methods, ensure the real-time communication of the terminal. This paper will introduce a technology to enhance the communication ability of terminal communication module, and illustrate the whole picture of the device through practical cases.展开更多
This paper analyzes the main reasons of abnormal power metering device, discusses the monitoring method of abnormal state of power metering device, studies the abnormal detection measures of power metering device, in ...This paper analyzes the main reasons of abnormal power metering device, discusses the monitoring method of abnormal state of power metering device, studies the abnormal detection measures of power metering device, in order to promote the stable development of power metering device.展开更多
To design a Double-Pole Four-Throw (DP4T) RF switch, measurement of device parameters is required. In this DP4T RF switch CMOS is a unit cell, so with a thin oxide layer of thickness 628 ? which is measured optically....To design a Double-Pole Four-Throw (DP4T) RF switch, measurement of device parameters is required. In this DP4T RF switch CMOS is a unit cell, so with a thin oxide layer of thickness 628 ? which is measured optically. Some of the material parameters were found by the curve drawn between Capacitance versus Voltage (C-V) and Capacitance versus Frequency (C-F) with the application of Visual Engineering Environment Programming (VEE Pro). To perform the measurement processing at a distance, from the hazardous room, we use VEE Pro software. In this research, to acquire a fine result for RF MOSFET, we vary the voltage with minor increments and perform the measurements by vary the applying voltage from +5 V to –5 V and then back to +5 V again and then save this result in a data sheet with respect to temperature, voltage and frequency using this program. We have investigated the characteristics of RF MOSFET, which will be used for the wireless telecommunication systems.展开更多
The cup-chain metering device is commonly used in potato planters despite its problems of missing-seeding,double-seeding and ground wheel sliding.A mechanical-electrical design was developed for planters to resolve th...The cup-chain metering device is commonly used in potato planters despite its problems of missing-seeding,double-seeding and ground wheel sliding.A mechanical-electrical design was developed for planters to resolve these problems.A regression experiment was conducted with three factors(chain speed,chain tightening distance and cup tilting)and two indicators(missing-seeding rate and double-seeding rate).Based on the results of regression experiment,a numerical regression model was built and a multi-objective optimization method was used to get an optimal solution.Subsequently,the optimized device was tested in the field.The device design presents a tilting seed cup with a guard plate and an electric control system.The laboratory test showed that the missing-seeding rate increased with the chain speed.It initially decreases and then increases with the chain tightening distance and cup tilting angle.The double-seeding rate declines with chain speed.It increases initially and declines afterward with the chain tightening distance.The optimization resulted in a missing-seeding rate of 4.39%and a double-seeding rate of 8.78%under the parameters of 0.32 m/s seeding speed,0.94×10-3 m tightening distance,and 12.5°cup tilting angle.The field test demonstrated that electric control instead of ground wheel-driven chain enables fast seeding and precise intra-row seeding distance.展开更多
In order to address the issues of narrow seeding adjustment range and low accuracy of grain placement in the existing rice seeders,a mechanically and pneumatically adjustable precision hole-type seeder is designed.It ...In order to address the issues of narrow seeding adjustment range and low accuracy of grain placement in the existing rice seeders,a mechanically and pneumatically adjustable precision hole-type seeder is designed.It is primarily composed of a seeding disk,air chamber,seed box,and seed discharge device.The design incorporates a symmetrical structure with dual disks and dual casings,enabling both single-sided and double-sided single-row and synchronized seeding.Based on theoretical analysis of seed charging,seed protection,and seed release,the following parameters were determined:seeding disk diameter of 192 mm,suction hole diameter of 1.48-1.52 mm,suction hole spacing of 3.04-9.41 mm,type hole distribution circle radius of about 62.1-77.0 mm,type hole diameter of 9 mm,stirrer plate length of 4.705-9.410 mm,and stirrer plate inclination angle of 0°-30°.Using a coupled simulation method of EDEM-Fluent,the impact of different type hole distributions,stirrer plate lengths,and inclination angles on seeding performance was analyzed.The results indicate that the main and secondary influencing factors on seed charging qualification rate are type hole diameter,stirrer plate inclination angle,and stirrer plate length.The optimal performance is achieved with a type hole diameter of 6 mm,stirrer plate length of 5 mm,and stirrer plate inclination angle of 10°,resulting in a seed charging qualification rate of 71.42%.Furthermore,Fluent software was utilized to analyze the influence of different suction hole spacings,diameters,and air chamber radii on seeding performance.The results revealed that the suction of rice seeds by the hole can be better realized with a suction hole spacing of 6 mm,a suction hole diameter of 1.5 mm,and an air chamber radius of 62 mm,at which the average negative pressure in the suction hole center was about 2824.56 Pa.A bench test and a field test were further performed on the device.The results showed that increasing the number of type holes and suction holes can contribute to more stable regulation of the seeding amount.The optimal single-sided seed metering could achieve a maximum qualified rate of 82.5%,a missing rate of 12.5%,and a repeating rate of 5%;while the optimal double-sided seed metering could obtain a maximum qualified rate,missing rate,and repeating rate of 72.5%,15%,and 12.5%,respectively.This adjustable precision seeder can meet the requirements of precision sowing of Huanghuazhan rice varieties,and the research findings can provide reference for the structural optimization of precision rice seeders.展开更多
The model describing the forces acting on rice seeds within seed metering systems significantly impacts the design and structural parameters of rice pneumatic seed metering mechanisms.To formulate a mathematical repre...The model describing the forces acting on rice seeds within seed metering systems significantly impacts the design and structural parameters of rice pneumatic seed metering mechanisms.To formulate a mathematical representation of the device during seed suction,a DEM-CFD bidirectional coupling approach was utilized to simulate and model the seed-suction process.The dynamic behavior of rice seeds under the airflow at the suction port was examined,and force models for various seed-suction positions were developed.Simulation analyses were conducted under varying conditions,including different rotation speeds of the seed-suction plate and different levels of negative suction pressure.The effects of these variables on seed suction were investigated,leading to the development of a drag force model.Optimal seeding parameters and precision were determined from the simulation results.Verification and analysis were conducted through empirical experiments,and the optimal seeding performance was attained at a negative suction pressure of 1.6 kPa and a plate rotation speed of 30 r/min.The results indicated a seeding qualification rate of 95.7%,a reattachment rate of 2.4%,and a leakage suction rate of 1.9%.The simulation findings were consistent with experimental data,demonstrating that the seed-metering device satisfies the requirements for field seeding.展开更多
Positive and negative pressures determine the performance of pneumatic precision metering device for rapeseed.In order to investigate the relationship between positive and negative pressures of nozzles,fluid models of...Positive and negative pressures determine the performance of pneumatic precision metering device for rapeseed.In order to investigate the relationship between positive and negative pressures of nozzles,fluid models of chamber were developed to simulate the airflow,and the k-εturbulence model was conducted to capture the pressure and velocity of nozzles.Through these efforts linear models were achieved.Meanwhile,the three-factor factorial split-split experiment was designed with negative pressure,positive pressure and the rotating speeds varying from-1000 to-4500 Pa,50 to 250 Pa and 10 to 45 r/min,respectively.The mathematical models were developed through employing the stepwise regression method.The sequence of influential factors on the quality of feed index was positive pressure,negative pressure and rotating speed.To obtain the match regulation of negative and positive pressures with“good”performance,the ratio coefficient K of negative and positive pressures was introduced to build mathematical models.Models relating ratio coefficient K with positive pressure were fitted in different rotating speeds.The results showed that the ratio coefficient was matchedГ∈[f1(x),f2(x)]from the fitting equations with the rotating speed of 10-30 r/min;while the rotating speed has greater influence when it was 35-40 r/min and the setsΛ∈[g1(x),g2(x)]were achieved,where x∈[100,250].This study could be conducted to adjust the rotating speed of the pneumatic system to optimize the ideal performance of the seeder.展开更多
In order to meet the agronomy demand for hybrid rice direct seeding,a novel precise pneumatic rice seed metering device was designed with groups of sucking holes plate,by which 3-4 seeds could be synchronously sucked ...In order to meet the agronomy demand for hybrid rice direct seeding,a novel precise pneumatic rice seed metering device was designed with groups of sucking holes plate,by which 3-4 seeds could be synchronously sucked and synchronously dropped into the paddy field.The plate was divided into five sections:seed sucking,seed clearing,seed carrying,seed dropping,and blank sections.The seeds were sucked in sucking section by the vacuum,carried and rotated to the dropping section with the plate,blown away in dropping section by the positive pressure air,and thrown into the dropping tube.The influences of the hole diameter,vacuum degree,and clear-up equipment on precision of metering device were discussed.Experiments were conducted to investigate the seeding precision and simulate the field emergence rates on the indoor seeding test-bed.The subjects were pregnant Indic hybrid Peizataifeng under two kinds of moisture content(23.43%and 26.07%).Other experiment conditions included the vacuum degree of 2.60 kPa,the rotation speed of seed sucking plate of 30 r/min,three sucking holes with a diameter of 1.6 mm,and the seed layer thickness of 25 mm.The seeding results showed that,in condition of no more than two seeds per hill,the emergence probabilities under the two moisture contents were 11.82%and 11.95%,respectively,and in condition of 3-4 seeds per hill,the results were 64.81%and 65.84%,respectively.With 2-5 seeds per hill,the results were 92.08%and 92.60%,respectively.If the emergence probability was 80%,under the two moisture contents,the no seed per hill probabilities were 1.33%and 0.80%respectively;the probabilities with 3-4 seeds per hill were 56.13%and 56.40%respectively;the probabilities with 5 or more seeds per hill were 10.67%and 10.13%respectively;the probabilities with 2-5 seeds per hill were 87.60%and 88.13%respectively.The results showed the simulated experiment was an efficient and economic method to assess the capability of pneumatic rice seed drilling metering device,and the precise pneumatic rice seed drilling metering device had a good prospect in practical application.展开更多
A ripple surface type pickup finger was designed to improve the performance of pickup finger precision maize seed metering device and to provide a solution for precision maize planter.The main structure and working pr...A ripple surface type pickup finger was designed to improve the performance of pickup finger precision maize seed metering device and to provide a solution for precision maize planter.The main structure and working principle of seed metering device were detailed in this paper.The dimension size distributions of maize seeds in different types were studied,the gestures of seeds clamped by pickup finger were analyzed,and the clamping dynamical model of pickup finger was established by theoretical analysis.To optimize the structural parameters of ripple surface type pickup finger,the discrete element method(DEM)model of pickup finger precision maize seed metering device was established by the discrete element software EDEM.The numerical simulations of orthogonal seeding performance experiments were conducted to analyze the influences of these factors on the quality of seeding.The rotational speed,wavelength of ripple surface and amplitude of ripple surface were selected as the experimental factors.The average seeding qualified index and the average seeding coefficient of variation on four different types of maize seeds were chosen for evaluating the seeding performance.The results showed that,the average seeding qualified index was 93.35%and the average seeding coefficient of variation was 11.23%under conditions of the 25 r/min rotational speed,8 mm wavelength of ripple surface and 2 mm amplitude of ripple surface.Under the same condition,the bench test was done which showed that the results of test and simulation were consistent.The maximum error of qualified index was 1.95%and the qualified index of improved seed metering device exceeded the original one by 12.34%.The working performance can meet the requirements of precision maize seeding.展开更多
基金The authors would like to express appreciation for the support of Australia Research Council(IH140100035)Nature Science Foundation of China(51675218)+1 种基金Doctor Starting Foundation of Jiangxi University of Science and Technology(JXXJBS17078)Science and Technology Project of the Education Department of Jiangxi Province(GJJ180426).
文摘In this paper,the gas and seed flow characters in the air-blowing seed metering device are investigated by using the coupled computational fluid dynamics and discrete element method(CFD-DEM)in three dimensions(3D).The method of establishing boundary model based on the computer-aided design(CAD)drawing,has been used to build the boundary model of seed metering device.The 3D laser scanning technique and multi-element method are adopted to establish the particle model.Through a combined numerical and experimental effort,using 3D CFD-DEM software,which is based on the in-house codes,the mechanisms governing the gas and solid dynamic behaviors in the seed metering device have been studied.The gas velocity field and the effect of different rotational speeds and air pressures on the seeding performance and particle velocity have been studied,similar agreements between numerical and experimental results are gained.This reveals that the 3D CFD-DEM model established is able to predict the performance of the air-blowing seed metering device.It can be used to design and optimize the air-blowing seed metering device and other similar agriculture devices.
文摘Based on the mechanical and physical properties study of forage grass seeds, multi-line with one-device type metering device was designed. It was composed of adjustable screw, stirrer, metering device housing and central metering sheave and so on. The sowing rate can be set by turning the screw to change the working length of the central metering sheave relative to the metering device housing. The stirrer inside of the sheave housing is used to prevent seeds overhead. And metering of different sizes of seed is adjusted by changing the position of internal components of the slot wheel mechanism. Innovative design on the structure of the central metering sheave was finished. According to the structure parameters and physical characteristic parameters, different seed sowing rate of per hectares was calculated. And then the working length scale of the central metering groove wheel was made. And there is a one-to-one correspondence between scale values and sowing quantity per hectare of different kinds of seed.
文摘There are many design parameters in precision planters to be considered such as cell diameter, peripheral speed of roller, number of cells, manner of feeding seeds into cell and travel speed. In precision planters each cell must contain only one seed. Therefore, sliding the seed to the cell is important and depends on several parameters such as seed repose angle, seed dimensions and physics of cell. To help the seed to repose in the cell, making a groove on the roller would be very useful. Dimensions of this groove are very important and are considered as basic design parameters. This research was performed to determine some design parameters such as roller speed, travel speed, length and depth of groove for tomato seeds precision planting. In this regard, seeds with a diameter of 4 mm were used. The range of variation was based on calculations obtained. A roller with 42 mm width, 118 mm diameter and 15 cells on the surface was used in the experiment. For each cell, a triangular groove was created on the roller. The groove depth varied from zero at the beginning to the maximum value where the groove connected to the cell. The test unit had a continued and wide belt with 1 l m length. In each replication, planter worked for 20 s to reach a stable state. Thereafter, seeds were allowed to drop on the grease belt. Number of seeds and their spacing were measured on the 4.5 m of the belt. Results showed that the roller speed of 41.5 rpm, the planter travel speed of approximately 1 km/h, groove length of 6-8 mm and groove depth of 1.5 mm can improve planter performance for tomato pelleted seed.
文摘The automation technology of electric energy measurement covers all levels of electric energy measurement points. The electric energy data acquisition of power users has realized remote automatic acquisition. The tool for remote automatic collection of electric energy data is various metering automation terminals installed on the site. The data transmission of the automation terminal depends on various communication channels. When the field signal strength is insufficient and the communication module of the metering automation terminal cannot work normally, the terminal is offline and the data collection fails. At this time, it is necessary to solve the problem of insufficient signal through other methods, ensure the real-time communication of the terminal. This paper will introduce a technology to enhance the communication ability of terminal communication module, and illustrate the whole picture of the device through practical cases.
文摘This paper analyzes the main reasons of abnormal power metering device, discusses the monitoring method of abnormal state of power metering device, studies the abnormal detection measures of power metering device, in order to promote the stable development of power metering device.
文摘To design a Double-Pole Four-Throw (DP4T) RF switch, measurement of device parameters is required. In this DP4T RF switch CMOS is a unit cell, so with a thin oxide layer of thickness 628 ? which is measured optically. Some of the material parameters were found by the curve drawn between Capacitance versus Voltage (C-V) and Capacitance versus Frequency (C-F) with the application of Visual Engineering Environment Programming (VEE Pro). To perform the measurement processing at a distance, from the hazardous room, we use VEE Pro software. In this research, to acquire a fine result for RF MOSFET, we vary the voltage with minor increments and perform the measurements by vary the applying voltage from +5 V to –5 V and then back to +5 V again and then save this result in a data sheet with respect to temperature, voltage and frequency using this program. We have investigated the characteristics of RF MOSFET, which will be used for the wireless telecommunication systems.
基金the State's Key Project of Research and Development Plan(2016YFD0700103)National Natural Science Foundation of China(31301241).
文摘The cup-chain metering device is commonly used in potato planters despite its problems of missing-seeding,double-seeding and ground wheel sliding.A mechanical-electrical design was developed for planters to resolve these problems.A regression experiment was conducted with three factors(chain speed,chain tightening distance and cup tilting)and two indicators(missing-seeding rate and double-seeding rate).Based on the results of regression experiment,a numerical regression model was built and a multi-objective optimization method was used to get an optimal solution.Subsequently,the optimized device was tested in the field.The device design presents a tilting seed cup with a guard plate and an electric control system.The laboratory test showed that the missing-seeding rate increased with the chain speed.It initially decreases and then increases with the chain tightening distance and cup tilting angle.The double-seeding rate declines with chain speed.It increases initially and declines afterward with the chain tightening distance.The optimization resulted in a missing-seeding rate of 4.39%and a double-seeding rate of 8.78%under the parameters of 0.32 m/s seeding speed,0.94×10-3 m tightening distance,and 12.5°cup tilting angle.The field test demonstrated that electric control instead of ground wheel-driven chain enables fast seeding and precise intra-row seeding distance.
基金supported by the Outstanding Young and Middle-aged Science and Technology Innovation Team Program of Colleges and Universities of Hubei Province(Grant No.T201934)the Development and Application of Rice and Camellia Fruit Mechanized Short Board Machine(Grant No.HBSNYT202208).
文摘In order to address the issues of narrow seeding adjustment range and low accuracy of grain placement in the existing rice seeders,a mechanically and pneumatically adjustable precision hole-type seeder is designed.It is primarily composed of a seeding disk,air chamber,seed box,and seed discharge device.The design incorporates a symmetrical structure with dual disks and dual casings,enabling both single-sided and double-sided single-row and synchronized seeding.Based on theoretical analysis of seed charging,seed protection,and seed release,the following parameters were determined:seeding disk diameter of 192 mm,suction hole diameter of 1.48-1.52 mm,suction hole spacing of 3.04-9.41 mm,type hole distribution circle radius of about 62.1-77.0 mm,type hole diameter of 9 mm,stirrer plate length of 4.705-9.410 mm,and stirrer plate inclination angle of 0°-30°.Using a coupled simulation method of EDEM-Fluent,the impact of different type hole distributions,stirrer plate lengths,and inclination angles on seeding performance was analyzed.The results indicate that the main and secondary influencing factors on seed charging qualification rate are type hole diameter,stirrer plate inclination angle,and stirrer plate length.The optimal performance is achieved with a type hole diameter of 6 mm,stirrer plate length of 5 mm,and stirrer plate inclination angle of 10°,resulting in a seed charging qualification rate of 71.42%.Furthermore,Fluent software was utilized to analyze the influence of different suction hole spacings,diameters,and air chamber radii on seeding performance.The results revealed that the suction of rice seeds by the hole can be better realized with a suction hole spacing of 6 mm,a suction hole diameter of 1.5 mm,and an air chamber radius of 62 mm,at which the average negative pressure in the suction hole center was about 2824.56 Pa.A bench test and a field test were further performed on the device.The results showed that increasing the number of type holes and suction holes can contribute to more stable regulation of the seeding amount.The optimal single-sided seed metering could achieve a maximum qualified rate of 82.5%,a missing rate of 12.5%,and a repeating rate of 5%;while the optimal double-sided seed metering could obtain a maximum qualified rate,missing rate,and repeating rate of 72.5%,15%,and 12.5%,respectively.This adjustable precision seeder can meet the requirements of precision sowing of Huanghuazhan rice varieties,and the research findings can provide reference for the structural optimization of precision rice seeders.
基金funding from the National Natural Science Foundation of China(Grant No.32201669)the Guangzhou Science and Technology Plan Project(Grant No.2023A04J0865)+5 种基金Key Discipline Research Capability Enhancement Project in Guangdong Province(Grant No.2024ZDJS081)Guangdong Provincial Junior Innovative Talents Project for Ordinary Universities(Grant No.2022KQNCX122)the project was supported by Open Fund of State Key Laboratory of Agricultural Equipment Technology,South China Agricultural University(Grant No.SKLAET-202405)Guangzhou College of Commerce Campus Project(Grant No.2021XJYB06)Guangdong Provincial Key Laboratory of Agricultural Artificial Intelligence Open Plan Project(Grant No.GDKL-AAI-2022002GDKL-AAI-2022003).
文摘The model describing the forces acting on rice seeds within seed metering systems significantly impacts the design and structural parameters of rice pneumatic seed metering mechanisms.To formulate a mathematical representation of the device during seed suction,a DEM-CFD bidirectional coupling approach was utilized to simulate and model the seed-suction process.The dynamic behavior of rice seeds under the airflow at the suction port was examined,and force models for various seed-suction positions were developed.Simulation analyses were conducted under varying conditions,including different rotation speeds of the seed-suction plate and different levels of negative suction pressure.The effects of these variables on seed suction were investigated,leading to the development of a drag force model.Optimal seeding parameters and precision were determined from the simulation results.Verification and analysis were conducted through empirical experiments,and the optimal seeding performance was attained at a negative suction pressure of 1.6 kPa and a plate rotation speed of 30 r/min.The results indicated a seeding qualification rate of 95.7%,a reattachment rate of 2.4%,and a leakage suction rate of 1.9%.The simulation findings were consistent with experimental data,demonstrating that the seed-metering device satisfies the requirements for field seeding.
基金The research was funded by the National Science Foundation of China under grant 51275197National Rapeseed Industrial System Special Foundation CARS-13,National Science and Technology Support Project 013BAD08B02and High School Science Research Foundation 2014PY033.
文摘Positive and negative pressures determine the performance of pneumatic precision metering device for rapeseed.In order to investigate the relationship between positive and negative pressures of nozzles,fluid models of chamber were developed to simulate the airflow,and the k-εturbulence model was conducted to capture the pressure and velocity of nozzles.Through these efforts linear models were achieved.Meanwhile,the three-factor factorial split-split experiment was designed with negative pressure,positive pressure and the rotating speeds varying from-1000 to-4500 Pa,50 to 250 Pa and 10 to 45 r/min,respectively.The mathematical models were developed through employing the stepwise regression method.The sequence of influential factors on the quality of feed index was positive pressure,negative pressure and rotating speed.To obtain the match regulation of negative and positive pressures with“good”performance,the ratio coefficient K of negative and positive pressures was introduced to build mathematical models.Models relating ratio coefficient K with positive pressure were fitted in different rotating speeds.The results showed that the ratio coefficient was matchedГ∈[f1(x),f2(x)]from the fitting equations with the rotating speed of 10-30 r/min;while the rotating speed has greater influence when it was 35-40 r/min and the setsΛ∈[g1(x),g2(x)]were achieved,where x∈[100,250].This study could be conducted to adjust the rotating speed of the pneumatic system to optimize the ideal performance of the seeder.
基金Financial support for this study was provided by National Natural Science Foundation of China(Grant No.51105147)Chinese Agriculture Commonweal Projects(Grant No.201203059)+1 种基金National High Technology Research and Development Program 863(Grant No.2014AA10A605-8)Fundamental Research Funds for the Central Universities(Grant No.2013PY123,2014PY043).
文摘In order to meet the agronomy demand for hybrid rice direct seeding,a novel precise pneumatic rice seed metering device was designed with groups of sucking holes plate,by which 3-4 seeds could be synchronously sucked and synchronously dropped into the paddy field.The plate was divided into five sections:seed sucking,seed clearing,seed carrying,seed dropping,and blank sections.The seeds were sucked in sucking section by the vacuum,carried and rotated to the dropping section with the plate,blown away in dropping section by the positive pressure air,and thrown into the dropping tube.The influences of the hole diameter,vacuum degree,and clear-up equipment on precision of metering device were discussed.Experiments were conducted to investigate the seeding precision and simulate the field emergence rates on the indoor seeding test-bed.The subjects were pregnant Indic hybrid Peizataifeng under two kinds of moisture content(23.43%and 26.07%).Other experiment conditions included the vacuum degree of 2.60 kPa,the rotation speed of seed sucking plate of 30 r/min,three sucking holes with a diameter of 1.6 mm,and the seed layer thickness of 25 mm.The seeding results showed that,in condition of no more than two seeds per hill,the emergence probabilities under the two moisture contents were 11.82%and 11.95%,respectively,and in condition of 3-4 seeds per hill,the results were 64.81%and 65.84%,respectively.With 2-5 seeds per hill,the results were 92.08%and 92.60%,respectively.If the emergence probability was 80%,under the two moisture contents,the no seed per hill probabilities were 1.33%and 0.80%respectively;the probabilities with 3-4 seeds per hill were 56.13%and 56.40%respectively;the probabilities with 5 or more seeds per hill were 10.67%and 10.13%respectively;the probabilities with 2-5 seeds per hill were 87.60%and 88.13%respectively.The results showed the simulated experiment was an efficient and economic method to assess the capability of pneumatic rice seed drilling metering device,and the precise pneumatic rice seed drilling metering device had a good prospect in practical application.
基金the National Science and Technology Support Plan Project(2014BAD06B04).
文摘A ripple surface type pickup finger was designed to improve the performance of pickup finger precision maize seed metering device and to provide a solution for precision maize planter.The main structure and working principle of seed metering device were detailed in this paper.The dimension size distributions of maize seeds in different types were studied,the gestures of seeds clamped by pickup finger were analyzed,and the clamping dynamical model of pickup finger was established by theoretical analysis.To optimize the structural parameters of ripple surface type pickup finger,the discrete element method(DEM)model of pickup finger precision maize seed metering device was established by the discrete element software EDEM.The numerical simulations of orthogonal seeding performance experiments were conducted to analyze the influences of these factors on the quality of seeding.The rotational speed,wavelength of ripple surface and amplitude of ripple surface were selected as the experimental factors.The average seeding qualified index and the average seeding coefficient of variation on four different types of maize seeds were chosen for evaluating the seeding performance.The results showed that,the average seeding qualified index was 93.35%and the average seeding coefficient of variation was 11.23%under conditions of the 25 r/min rotational speed,8 mm wavelength of ripple surface and 2 mm amplitude of ripple surface.Under the same condition,the bench test was done which showed that the results of test and simulation were consistent.The maximum error of qualified index was 1.95%and the qualified index of improved seed metering device exceeded the original one by 12.34%.The working performance can meet the requirements of precision maize seeding.
