Development status and prospect of cold chain logistics of fruits,vegetables,and agricultural products based on intelligent technology

The cold chain in the production area of fruits and vegetables is the primary link to reduce product loss and improve product quality,but it is also a weak link.With the application of big data technology in cold chain logistics,intelligent devices,and technologies have become important carriers for improving the efficiency of cold chain logistics in fruit and vegetable production areas,extending the shelf life of fruits and vegetables,and reducing fruit and vegetable losses.They have many advantages in fruit and vegetable pre-cooling,sorting and packaging,testing,warehousing,transportation,and other aspects.This article summarizes the rapidly developing and widely used intelligent technologies at home and abroad in recent years,including automated guided vehicle intelligent handling based on electromagnetic or optical technology,intelligent sorting based on sensors,electronic optics,and other technologies,intelligent detection based on computer vision technology,intelligent transportation based on perspective imaging technology,etc.It analyses and studies the innovative research and achievements of various scholars in applying intelligent technology in fruit and vegetable cold chain storage,sorting,detection,transportation,and other links,and improves the efficiency of fruit and vegetable cold chain logistics.However,applying intelligent technology in fruit and vegetable cold chain logistics also faces many problems.The challenges of high cost,difficulty in technological integration,and talent shortages have limited the development of intelligent technology in the field of fruit and vegetable cold chains.To solve the current problems,it is proposed that costs be controlled through independent research and development,technological innovation,and other means to lower the entry threshold for small enterprises.Strengthen integrating intelligent technology and cold chain logistics systems to improve data security and system compatibility.At the same time,the government should introduce relevant policies,provide necessary financial support,and establish talent training mechanisms.Accelerate the development and improvement of intelligent technology standards in the field of cold chain logistics.Through technological innovation,cost control,talent cultivation,and policy guidance,we aim to promote the upgrading of the agricultural industry and provide ideas for improving the quality and efficiency of fruit and vegetable cold chain logistics.

Design and Experiment of Electronic-hydraulic Loading Test-bed Based on Tractor's Hydraulic Steering By-wire

An Electro-hydraulic loading system is designed based on a test-bed of tractor's hydraulic steering by-wire. To simulate the steering resistance driving tractor in many kinds of soils and roads,the loading force is controlled to make proportional and continuous variable by an electro-hydraulic proportional relief valve. A steering resistance loading test-bed is built to test three kinds of steering resistance including constant,step and sine style. Tire lateral resistance is also tested under different steering conditions. The result shows that the electro-hydraulic loading system has high stability and following performance. Besides,the system's steady state error is lower than 3. 1%,and it meets the test requirement of tractor's hydraulic steering by-wire.

A binary gridding path-planning method for plant-protecting UAVs on irregular fields

The use of plant-protecting unmanned aerial vehicles(UAVs)for pesticide spraying is an essential operation in modern agriculture.The balance between reducing pesticide consumption and energy consumption is a significant focus of current research in the path-planning of plant-protecting UAVs.In this study,we proposed a binarization multi-objective model for the irregular field area,specifically an improved non-dominated sorting genetic algorithm–II based on the knee point and plane measurement(KPPM-NSGA-ii).The binarization multi-objective model is applied to convex polygons,concave polygons and fields with complex terrain.The experiments demonstrated that the proposed KPPM-NSGA-ii can obtain better results than the unplanned path method whether the optimization of pesticide consumption or energy consumption is preferred.Hence,the proposed algorithm can save energy and pesticide usage and improve the efficiency in practical applications.

Review of the field environmental sensing methods based on multi-sensor information fusion technology

Field environmental sensing can acquire real-time environmental information,which will be applied to field operation,through the fusion of multiple sensors.Multi-sensor fusion refers to the fusion of information obtained from multiple sensors using more advanced data processing methods.The main objective of applying this technology in field environment perception is to acquire real-time environmental information,making agricultural mechanical devices operate better in complex farmland environment with stronger sensing ability and operational accuracy.In this paper,the characteristics of sensors are studied to clarify the advantages and existing problems of each type of sensors and point out that multiple sensors can be introduced to compensate for the information loss.Secondly,the mainstream information fusion types at present are outlined.The characteristics,advantages and disadvantages of different fusion methods are analyzed.The important studies and applications related to multi-sensor information fusion technology published at home and abroad are listed.Eventually,the existing problems in the field environment sensing at present are summarized and the prospect for future of sensors precise sensing,multi-dimensional fusion strategies,discrepancies in sensor fusion and agricultural information processing are proposed in hope of providing reference for the deeper development of smart agriculture.

Energy consumption mechanism simulation and experimental study of reciprocating vibration for Chinese wolfberry picking

In order to find out the matching principle of excitation force and energy consumption of reciprocating vibrating Chinese wolfberry picking device,the energy consumption mechanism of reciprocating vibrating Chinese wolfberry picking device is studied.According to the structural characteristics and operating principle of the picking device,the no-load and load movement and force characteristics of the crank bearing and vibrating component are analyzed,and the theoretical model of energy consumption of the reciprocating vibration picking device is jointly constructed,and the simulation analysis is carried out.The results show that the vibrating component and load mass have a significant influence on torque,the load air resistance phase has a significant effect on torque,and the load air resistance and friction coefficient have no significant influence on torque.Subsequently,by building an AC servo motor torque detection system and a torque sensing detection system,verification experiments are carried out,the maximum torque of the preset system is 1.3 N∙m,the rated power is 400 W,the motor frequency is 20 Hz,the amplitude is 15 mm,and the total mass of the vibrating component is 0.143 kg.Test results show that,the no-load operation,the change trend of detected torque is consistent with simulation,the torque model is verified to be accurate.The maximum torque of simulation and detection are 0.52 N∙m and 0.57 N∙m respectively,and the error between test and simulation is 9.6%.For load operation,the maximum torque of five groups of branch loads of 20 g,60 g,100 g,140 g,180 g and 220 g are detected to be 0.73 N∙m,0.74 N∙m,0.75 N∙m,0.82 N∙m and 0.83 N∙m,respectively,and the relationship model between load and torque is obtained by fitting.The research results can provide a theoretical basis which can configure a suitable motor in the reciprocating vibration Chinese wolfberry picking device with a certain load limit.

Performance test of a half-feed peanut-cleaning picker suitable for clay hill areas in southern China

To solve the problems of excessive soil lumps,broken branches and seedlings in pods and difficulty in removing impurities in the harvested pods of peanuts in the hilly areas of southern China,which is due to the high soil viscosity and easy hardening,and to improve the soil removal effect of the peanut half-feed pod picker in hilly areas of China,this article designed a half-feed peanut-cleaning picker suitable for southern clay hilly areas and provided a detailed introduction to the overall structure,working principle,and adjustment methods of various operating parameters.Through field measurement experiments,the influencing factors and laws of soil removal performance indicators,such as the comprehensive soil removal rate and POD drop rate,were studied.The results showed that the comprehensive soil removal rate gradually increased with increasing soil patting frequency,soil patting amplitude,and picking roller speed,first increased and then decreased with increasing picking roller gap and gradually decreased with increasing soil patting plate gap and clamping conveyor chain speed.The comprehensive soil removal rate of the soil patting plate using the opposite patting method was greater than that of the swinging patting method.The soil removal pod drop rate increased gradually with increasing soil patting frequency and amplitude and decreased with increasing soil patting plate gap and clamping conveyor chain speed.The soil removal pod drop rate of the soil patting plate using swing patting was lower than that using the opposite patting method.The speed and gap of the picking roller had no effect on the soil removal pod drop rate.The frequency,amplitude,form,and gap of the soil patting plate had extremely significant impacts on the rate of decrease in the number of soil removal pod drop rate.The clamping conveyor chain speed had a significant impact,while the speed and gap of the picking roller had no significant impact.The influence of all factors on the comprehensive soil removal rate was extremely significant.This study provides a theoretical basis and technical reference for parameter optimization research on peanut-cleaning picking machines in the clay hilly areas of southern China.

Structure design and rice threshing performance of the variable-speed inertial pulley for simulating artificial threshing

Due to the small models and compact structures,small harvesters have also caused problems such as poor threshing separation performance and large loss rates.In order to solve unstable cleaning effects of small harvesters when they facing different working conditions,this study selected rice plants in hilly areas for the experiment.Tensile breaking force of different parts of mature rice was tested,which revealed the fracture mechanism of each part under the combined force.Inertial threshing method was used to simulate artificial plate bin and design three kinds of non-circular pulley variable speed transmission threshing mechanism.With the help of transient inertia force,threshing force was compensated.This paper tested the harvesting performance of the variable speed threshing device with the help of the harvest performance test.Results show when facing the small rice planting area,the T/2 variable speed threshing device has better cleaning performance,and also the harvest loss rate of T/4 variable speed threshing device is the lowest.Compared with the constant speed threshing device,the impurity content rate of the variable speed threshing device is increased by 0.64%to 8.76%;the loss rate is reduced by 0.45%to 1.79%,which provides a basis for the optimization design of small combine harvester in hilly areas.

Investigation of distribution uniformity of distributor for biogas slurry application based on CFD analysis

A horizontal distributor for biogas slurry application was proposed to explore the distribution performance through CFD analysis and verified by field test.The rheological properties of biogas slurry were analyzed at first,and key parameters were obtained for the next simulation.The effects of distribution modes,inlet direction,and outlets number on the velocity distribution of flow field and mass flow rate of the horizonal distributor were investigated by CFD simulations.Results of rheological properties indicated that biogas slurry was a non-Newtonian fluid and exhibited shear-thinning behavior.It can be well described by power-law model.The simulation results showed that the geometry of rotor,especially the block numbers was the main factor that determining the fluid movement and trajectory of distribution and output.The mode rotor 1 with two blocks reached the lowest variable coefficient of mass flow rate(4.49%),indicating a higher degree of uniformity.The upward inlet direction would obtain less dead zone,and the distributor with an even outlets number would possess more uniform distribution and less dead zone.The field test of the distributor with rotor 1,upward inlet direction,and 24 outlets has been carried on to verify the simulation results,the variable coefficient of mass flow was 13.06%,which was slightly higher than the simulation(9.23%),but it still within the range of requirement(<15%).The proposed model and the findings of this work are of guiding significance for the study of the utilization technology and equipment of liquid biogas residue.

Experiment and parameter optimization of an automatic row following system for the traction beet combine harvester

To improve the automation level and operation quality of China's beet harvester and reduce the loss due to damaged and missed excavation,this study used a self-developed sugar beet combine harvester and field simulation experiment platform,based on the single-factor bench test of the automatic row following system in the early stage,taking hydraulic flow A,spring preload B,and forward speed C which have significant influence on performance indices as test factors,and taking the missed excavation rate,breakage rate and reaction time as performance indices,the orthogonal experimental study on the parameter optimization of the three-factor and three-level automatic row following system with the first-order interaction of various factors was carried out.The results of the orthogonal experiments were analyzed using range analysis and variance analysis.The results showed that there were differences in the influence degree,factor priority order and first-order interaction,and the optimal parameter combination on each performance index.A weighted comprehensive scoring method was used to optimize and analyze each index.The optimal parameter combination of the overall operating performance of the automatic row following system was A 2B 2C 1,that is,the hydraulic flow was 25 L/min,the forward speed was 0.8 m/s,and the spring preload was 198 N.Under this combination,the response time was 0.496 s,the missed excavation rate was 2.35%,the breakage rate was 3.65%,and the operation quality was relatively good,which can meet the harvest requirements.The comprehensive optimization results were verified by field experiments with different ridge shapes and different planting patterns.The results showed that the mean values of the missed excavation rate of different planting patterns of conventional straight ridges and extremely large"S"ridges were 2.23%and 2.69%,respectively,and the maximum values were 2.39%and 2.98%,respectively;the average damage rates were 3.38%and 4.14%,and the maximum values were 3.58%and 4.48%,which meet the industry standards of sugar beet harvester operation quality.The overall adaptability of the automatic row following system is good.This study can provide a reference for research on automatic row following harvesting systems of sugar beets and other subsoil crop harvesters.

Canopy deposition characteristics of different orchard pesticide dose models

Pesticide dose model based on canopy characteristics is the guidance basis for spray parameters adjustment.In this study,the calculation formula and canopy deposition characteristics of leaf wall area(LWA)model,tree row volume(TRV)model,and optimal coverage method(OCM)model were described and compared.A tower air-assisted spray test bench was applied to provide fine quality droplets,suitable wind speed and demand spray flow rate for corresponding models,an electric flat board vehicle was applied to drive tree in a straight line to simulate the sprayer movement speed,and droplet deposition distribution were tested in different leaf area density canopy.The results showed that the spray flow rates of three pesticide dose models decreased gradually.LWA model was only related to canopy height,TRV model was related to canopy height and canopy diameter,while OCM model was related to canopy height,canopy diameter and leaf area density.Whether dense or sparse canopy,TRV model basically satisfied the requirement of coverage rate greater than 33%in the entire canopy,OCM model met the requirement of coverage density greater than 70 droplets/cm^(2).However,LWA model,for dense canopy,unit area deposition of outermost leaves near sprayer was 3.6 times of the apple leaf maximum retention,which had a high loss risk;for sparse canopy,penetration rates of outermost leaves far away sprayer,that is,the drift rate was 21.4%.The discussion leads to the conclusion that for conventional spraying,TRV model represented a substantial improvement compared to LWA model,and OCM model was a reasonable low volume spraying model.This study provides a reference to different growth seasons spray amount adjustments in orchard.

Formation mechanism for the laying angle of hemp harvester based on ANSYS-ADAMS

Aiming at the problem of large differences in the laying angle and posture of plants cut by the hemp harvester,which is unfavorable for the subsequent picking-up,this paper analyzed the laying process and laying angles,and built a conveyorplant rigid-flexible coupling model for simulating the laying of hemp plant.Moreover,the operating parameters were tested and optimized based on the central composite design theory,and carried out multi-objective optimization with the minimum laying angle as the response index.Firstly,the formation mechanism of the laying angle of hemp harvester was studied.Secondly,a test was designed with the quadratic orthogonal rotational combination test method,with the data being processed by Design-Expert.A regression mathematical model of the laying angle was built,and the influence of the interactions between factors on the laying angle was analyzed with the response surface method.Furthermore,multi-objective optimization was conducted on the regression model according to the actual production design requirements.As a result,the best combination was obtained,that is,when the forward speed is 0.7 m/s,speed ratio 1.40,and stubble height 95 mm,the minimum laying angle can be obtained,namely 124.9°.The optimization parameters were verified by the simulation and field tests.The simulation test showed that the simulated laying angle is 125.2°,with a relative error of 0.24%from the theoretical value,under the best combination of parameters.The field test showed that the average laying angle of hemp plant is 121.8°,with a relative error of 2.5%from the theoretical value,under the best combination of parameters.The results may provide a reference for the structural improvement and operating parameter control of hemp harvesters.

Research and optimization of the hand-over lifting mechanism of a sweet potato combine harvester based on EDEM

In order to meet the challenge of high loss rate and high tuber injury rate during the operation of the 4UZL-1 sweet potato combine harvester,the sweet potato tuber hand-over lifting mechanism was designed based on a comprehensive analysis of the entire structure of the harvester.Taking the average normal force on conveying sweet potato tubers as evaluation indexes,the EDEM simulation experiment was carried out considering the factors of the angle of the excavating and conveying mechanism,the conveying angle of the scraper chain,the speed of the excavating and conveying mechanism,and the speed of the scraper chain conveying.The experimental findings indicated that the optimal operational performance of the hand-over lifting mechanism was achieved at a speed of 1.15 m/s for the excavating and conveying mechanism,an angle of 24°for the excavating and conveying mechanism,a conveying speed of 0.66 m/s for the scraper chain,and a conveying angle of 60°for the scraper chain.Field experiments were conducted based on the EDEM simulation experiment,using the loss rate and the injury rate of conveying sweet potato tubers as evaluation indexes.The results showed that the hand-over lifting mechanism demonstrated optimal operational effectiveness with an excavating and conveying mechanism angle of 20°,a scraper chain angle of 68°,an excavating and conveying mechanism speed of 1.2 m/s,and a scraper chain speed of 0.66 m/s,while the machine running speed was maintained at 1 m/s.At the moment,the hand-over lifting structure exhibited a loss rate of 1.12%and a tuber injury rate of 0.94%.The conclusions obtained serve as a valuable reference for future research and optimization of sweet potato combines.

Design and modelling of the full-feed peanut picking device with selfadaptive adjustable working clearance and feeding rate

To improve the declining performance of a full-feed peanut picking device or solve the mechanical failures that occur due to fluctuations in the feeding rate during operation,the 4HLJI-3000 peanut intelligent picking combine harvester,which is a picking device with a self-adaptive adjustment of the working clearance,was developed as the research object in this study.Moreover,the key components,such as the picking roller,concave plate sieve and clearance adjustment mechanism of the concave plate sieve,were designed and analysed.Through the force analysis of the concave plate sieve of the picking device,the mathematical model of the concave plate sieve displacement of the picking device and feeding rate was obtained.The software system for monitoring,storing and analysing the concave plate sieve displacement of the picking device based on EasyBuilder Pro was designed,and the road monitoring test of displacement variation of concave plate sieve of the picking device and feeding rate was carried out.The linear function,power function,exponential function,quadratic function,compound function,logarithmic function and cubic function fitting were used to perform regression analysis of the test results by using IBM SPSS software.The results showed that the cubic function model had a higher fitting precision,and its determination coefficient was 0.992.Model verification experiments were proposed,and the results showed that the established cubic function model had a good accuracy.The absolute deviation rate ranged from 0 to 4.83%,and the average deviation rate was 2.22%.The deviation rate increased with an increasing feeding rate.The field experiments also proved that there was a cubic function relationship between the feeding rate and concave plate sieve displacement,the measured concave plate sieve displacement deviation rate ranged from 0 to 6.19%,and the average deviation rate was 2.73%compared with the calculated results.This study can provide a reference for the optimization design of the structure of full-feeding picking devices for peanuts and other crops and the intelligent measurement and control of the feeding rates.

Operation analysis and parameter optimization of the conveying device for uniform crushed straw throwing and seed-sowing machines

Uniform crushed straw throwing and seed-sowing machines can achieve the processes of straw chopping,straw transport,sowing,fertilization,and straw mulching at the same time,which is widely used in many areas of China.Conveying device is one of the important components used to convey,elevate and throw straw.However,the problems of high power consumption and congestion affect the promotion of the machine.Therefore,the conveying device of uniform crushed straw throwing and seed-sowing machine was analyzed in order to determine its device operation mechanism.Kinematic and dynamic analyses of particles of crushed rice straw during lifting and dispersion are used to develop a flexible-body model of rod-shaped and agglomerate-shaped crushed straw and a coupling model including the mechanical structure of the device.By integrating computational fluid dynamics and the discrete element method,the gas-solid coupling theory in numerical simulations and motion analysis of crushed straw particles is used to determine how the flow field and motion characteristics affect the conveying performance.Besides,regression equations to describe the relationships between the factors and each assessment index were established by using the regression analysis and response surface analysis with the software Design-Expert.The effect of throwing blade speed X_(1),conveying volume of crushed straw X_(2),and pipeline diameter X_(3) on the throwing speed of crushed straw Y_(1) and specific power consumption Y2 were investigated.The highest throwing speed of crushed straw and lowest specific power consumption are the optimization goal.The results of optimization showed that the predict the best optimal parameters were 2000 r/min throwing blade rotational speed,1.4 kg/s conveying volume,and 220 mm pipeline diameter,the planter achieved a throwing speed of 12.2 m/s and specific power consumption of 9179 m^(2)/s^(2).And then a field test verification was conducted.The planter achieved a throwing speed 12.4 m/s and specific power consumption 9070 m^(2)/s^(2) while selecting the best optimal parameters.Thus,the optimal parameters can provide a high-performance operation and satisfy the actual operation requirements The results provide a theoretical basis and data support for seeding technology innovation and equipment optimization to ensure uniform crushed straw throwing in dense rice stubble fields.

Design and experiment of the bionic disc cutter for kenaf harvesters

Aiming to ease the cutting of kenaf stalks via bionics,the bionic disc cutter was designed.The upper jaw of the Batocera horsfieldi was used as a bionic prototype.Further,to explore its dynamic performance,an indoor multi-stalk cutting experimental bench was used to simulate the field operation process.A three-factor and two-level interaction orthogonal experiment was carried out;cutting speed,stalk conveying speed(machine forward speed),and blade type(ordinary disc cutter and bionic disc cutter)were used as experiment factors.The cutting pass rate and cutting specific energy consumption were selected as evaluation indexes.The range,variance,and fuzzy comprehensive evaluation analysis were carried out on the experiment results.Moreover,the main order factors affecting the bionic cutter performance were determined-blade type,conveying speed,the interaction between the cutter speed and conveying speed,and cutter speed.The optimal parameter combination scheme had a cutter speed of 1000 r/min,conveying speed of 0.4 m/s,and included bionic blades.Under this condition,the best index was the 92%cutting pass rate,with a specific energy consumption of 4.38 J/stalk.The variance analysis has shown that,with 95%confidence,the blade type has a rather significant influence on the comprehensive index.Additionally,the conveying speed also significantly influenced it,while other factors and interactions had no notable effect.The experimental comparison under the same working condition shows that the bionic blade has better cutting effect.This study provides a reference for the development of cutter and the selection of kenaf harvester operational parameters.

Spatial-channel transformer network based on mask-RCNN for efficient mushroom instance segmentation

Edible mushrooms are rich in nutrients;however,harvesting mainly relies on manual labor.Coarse localization of each mushroom is necessary to enable a robotic arm to accurately pick edible mushrooms.Previous studies used detection algorithms that did not consider mushroom pixel-level information.When these algorithms are combined with a depth map,the information is lost.Moreover,in instance segmentation algorithms,convolutional neural network(CNN)-based methods are lightweight,and the extracted features are not correlated.To guarantee real-time location detection and improve the accuracy of mushroom segmentation,this study proposed a new spatial-channel transformer network model based on Mask-CNN(SCT-Mask-RCNN).The fusion of Mask-RCNN with the self-attention mechanism extracts the global correlation outcomes of image features from the channel and spatial dimensions.Subsequently,Mask-RCNN was used to maintain a lightweight structure and extract local features using a spatial pooling pyramidal structure to achieve multiscale local feature fusion and improve detection accuracy.The results showed that the SCT-Mask-RCNN method achieved a segmentation accuracy of 0.750 on segm_Precision_mAP and detection accuracy of 0.638 on Bbox_Precision_mAP.Compared to existing methods,the proposed method improved the accuracy of the evaluation metrics Bbox_Precision_mAP and segm_Precision_mAP by over 2%and 5%,respectively.

Efficiency-first spraying mission arrangement optimization with multiple UAVs in heterogeneous farmland with varying pesticide requirements

Combining multiple crop protection Unmanned Aerial Vehicles(UAVs)as a team for a scheduled spraying mission over farmland now is a common way to significantly increase efficiency.However,given some issues such as different configurations,irregular borders,and especially varying pesticide requirements,it is more important and more complex than other multi-Agent Systems(MASs)in common use.In this work,we focus on the mission arrangement of UAVs,which is the foundation of other high-level cooperations,systematically propose Efficiency-first Spraying Mission Arrangement Problem(ESMAP),and try to construct a united problem framework for the mission arrangement of crop protection UAVs.Besides,to characterise the differences in sub-areas,the varying pesticide requirement per unit is well considered based on Normalized Difference Vegetation Index(NDVI).Firstly,the mathematical model of multiple crop-protection UAVs is established and ESMAP is defined.Furthermore,an acquisition method of a farmland’s NDVI map is proposed,and the calculation method of pesticide volume based on NDVI is discussed.Secondly,an improved Genetic Algorithm(GA)is proposed to solve ESMAP,and a comparable combination algorithm is introduced.Numerical simulations for algorithm analysis are carried out within MATLAB,and it is determined that the proposed GA is more efficient and accurate than the latter.Finally,a mission arrangement tested with three UAVs was carried out to validate the effectiveness of the proposed GA in spraying operation.Test results illustrated that it performed well,which took only 90.6%of the operation time taken by the combination algorithm.

Design and experiment of a six-row air-blowing centralized precision seed-metering device for Panax notoginseng

Panax notoginseng is grown mainly in Yunnan Province.Under the present high-density planting patterns for the plant,to solve the problems of a high rate of seed damage and the inability to use a traditional single air-blowing metering device,this paper designs a six-row air-blowing centralized precision seed-metering device for P.notoginseng to realize mechanized precision seeding of this species.This paper describes the working principle of the seed-metering device,and the main structural parameters are determined by combining theoretical calculations with simulation analysis.A mechanics model of the seed filling,cleaning and pressing processes of the seed-metering device was constructed.The seeds of P.notoginseng in Yunnan Province were selected as experimental subjects.An experimental study on the seed-metering performance of the seed-metering device was carried out using the quadratic rotation orthogonal combination test method.The outlet pressure of the air nozzle,forward velocity and cone angle of the hole were selected as test factors.Mathematical models of the grain spacing qualified index,miss index,multiple index and the coefficient of variation of the row displacement consistency were established to analyze the order of factors affecting indicators.Through parameter optimization,the optimum combination of parameters was determined as follows:the cone angle of the hole is 50°,the forward velocity is less than 0.73 m/s,and the outlet pressure of the air nozzle is 0.32-0.52 kPa.The qualified index of grain spacing is higher than 94%,the miss index is less than 3%,the multiple index is less than 5%,and the coefficient of variation of the row displacement consistency is less than 5%.The test results are essentially consistent with the optimization results.The metering device meets the requirements of precision seeding of P.notoginseng.This study provides a basis for the design of a six-row air-blowing centralized precision seed-metering device for P.notoginseng.

Design and test of two-wheeled walking hemp harvester

Aiming at the planting characteristics of hemp in southern hilly regions,a two-wheeled walking hemp harvester suitable for harvesting hemp in southern hilly regions is studied and designed.The harvester mainly consists of a header frame,single-moving cutter,cutter mechanical transmission,stalk lifter and reel,stalk divider,stalk horizontal conveyor,wheeled chassis,motor,gearbox,etc.To improve the cutting performance of the two-wheeled walking hemp harvester,response surface tests of three levels are conducted for three factors influencing the operation quality,including the cutting speed,blade length,and forward speed,on the constructed hemp cutting test bench.Moreover,test results are analyzed with the response surface method,and multi-objective optimization is carried out for the regression mathematical model with Design-Expert software.Results show that when the cutting speed is 1.2 m/s,the blade length is 120 mm,forward speed is 0.6 m/s,the cutting efficiency is 38.92 stalks/s,the cutting power is 776.37 W and the failure rate is 6.24%.Trial production of sample machine and field trial are finished according to the optimized parameters and structural design scheme,and the test results reveal that the cutting rate can reach 92.5%,the rate of transmission can reach 86.7%,the productivity is 0.18 hm2/h,and all performance indexes can meet the design requirements.This research can provide references for resolving the mechanical harvesting of hemp.

Experimental determination of restitution coefficient of garlic bulb based on high-speed photography

Restitution coefficient(RC)of garlic bulb is an important mechanical property that is required to establish the kinematics model of bulb collision and research the damage mechanism of bulb collision.In this study,kinetic equations of bulb collision were established based on Hertz's contact theory.The kinematics characteristics,elastoplastic deformation and contact damage during bulb collision were analyzed by using high-speed photography.The effects of bulb mass,moisture content,collision material,material thickness and release height on the RC were investigated by mixed orthogonal experiments and single-factor experiments.The results showed that the movement of bulb in the compression stage was translation,and the movement in the rebound stage was translation and rotation.During collision,the larger the rotational angular velocity of the bulb was,the smaller the measured RC would be.The contact damage of bulb included internal damage of the tissue,epidermis stretch and tear.The significance of effects of factors on RC decreased with the following sequence:collision material,release height,material thickness,bulb mass,and moisture content.Collision material,release height,material thickness,and bulb mass were significant factors.The RC between the bulb and Q235,nylon,and rubber decreased sequentially.The RC decreased with the increase of release height and bulb mass.The RC increased with the increase of material thickness of Q235,while it decreased with the increase of material thickness of rubber or Nylon.The determination coefficients of the regression equations between the significant factors and the RC were all greater than 0.96.The results will be helpful for damage mechanism analysis and design of garlic production equipment.