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.

Fast and accurate detection of kiwifruits in the natural environment using improved YOLOv4

Real-time detection of kiwifruits in natural environments is essential for automated kiwifruit harvesting. In this study, a lightweight convolutional neural network called the YOLOv4-GS algorithm was proposed for kiwifruit detection. The backbone network CSPDarknet-53 of YOLOv4 was replaced with GhostNet to improve accuracy and reduce network computation. To improve the detection accuracy of small targets, the upsampling of feature map fusion was performed for network layers 151 and 154, and the spatial pyramid pooling network was removed to reduce redundant computation. A total of 2766 kiwifruit images from different environments were used as the dataset for training and testing. The experiment results showed that the F1-score, average accuracy, and Intersection over Union (IoU) of YOLOv4-GS were 98.00%, 99.22%, and 88.92%, respectively. The average time taken to detect a 416×416 kiwifruit image was 11.95 ms, and the model’s weight was 28.8 MB. The average detection time of GhostNet was 31.44 ms less than that of CSPDarknet-53. In addition, the model weight of GhostNet was 227.2 MB less than that of CSPDarknet-53. YOLOv4-GS improved the detection accuracy by 8.39% over Faster R-CNN and 8.36% over SSD-300. The detection speed of YOLOv4-GS was 11.3 times and 2.6 times higher than Faster R-CNN and SSD-300, respectively. In the indoor picking experiment and the orchard picking experiment, the average speed of the YOLOv4-GS processing video was 28.4 fps. The recognition accuracy was above 90%. The average time spent for recognition and positioning was 6.09 s, accounting for about 29.03% of the total picking time. The overall results showed that the YOLOv4-GS proposed in this study can be applied for kiwifruit detection in natural environments because it improves the detection speed without compromising detection accuracy.

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.

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.

Determination of damaged wheat kernels with hyperspectral imaging analysis

Hyperspectral imaging was applied to classify the damaged wheat kernels and healthy kernels.The spectral information was extracted from damaged wheat kernels and healthy kernels samples.The effective wavelengths were obtained from spectral of 865-1711 nm by X-loadings of principal component analysis(PCA)and successive projection algorithm(SPA)method,respectively.Partial least square method(PLS)and least square-support vector machine(LS-SVM)were then used to build classification models on full spectral data and effective wavelengths dataset,respectively.The results showed that the classification accuracy of every LS-SVM model was the best,being 100%.While the accuracy of the PLS model was slightly lower,still over 97%.The confusion matrix showed that several damaged wheat kernels samples were misclassified as healthy samples,while all healthy samples were correctly classified.The overall results indicated that hyperspectral imaging could be used for discriminating the damaged wheat kernels and could provide a reference for detecting other grain kernels grading degrees.Further,this study can provide a research basis for the development of online or portable detectors on grain damaged kernels recognition,which will be beneficial for grain grading or post-harvest quality processing of other grains.

Optimizing the drying parameters of a fixed bed with reversing ventilation for peanut using computer simulation

To obtain the optimal operation parameters of fixed-bed reversing ventilation drying of peanuts,a set of partial differential equations indicating the heat and mass transfer relationships between the peanut pods and air during drying was proposed.Then,a series of discretized models were established for simulation,and the time consumed,unevenness,and energy consumption for batch drying were calculated.The results showed that reversing ventilation and segmented drying was helpful to these issues for high drying ability.The optimal operation parameters were determined by uniform design experimentation of mathematical simulation.The result showed that when the moisture content(wet basis)was above 22%,a ventilation velocity of 0.46 m/s was optimal;when the moisture content was between 8%and 22%,a ventilation velocity of 0.20 m/s was optimal.Using the optimal parameters,the computer simulating result was compared with the experimental results.The correlation coefficients between the simulating and the experimental values for the temperature and moisture content were all above 0.98 and the quality of dried peanuts was close to that of natural sun-dried ones,which indicates that the optimization results of the drying parameters are highly reliable.

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.

Design and parameters optimization for cutting-conveying mechanism of ramie combine harvester

In order to solve the problems of uneven stubble,low cutting efficiency and frequent breaking and blocking in the cutting and conveying links of ramie combine harvester,a reciprocating double movable blades cutter and a double-layer chain conveyor were designed,and the operating parameter test and optimization were carried out by using the central combination test design theory,with the emphasis on the influence of the forward speed,the cutting speed of the cutter and the conveying speed of the chain on the cutting efficiency,the failure rate and the conveying rate,and the multi-objective optimization was carried out based on these response indicators.Firstly,the structure and operating parameters of the cutting-conveying mechanism of ramie combine were studied.Then,the experiment was designed by the quadratic orthogonal rotation combination test method,and the data is processed by Design-Expert.The regression mathematical model of cutting efficiency,failure rate and conveying rate was established and variance analysis was carried out.By analyzing the effect of interaction of various factors on cutting efficiency,failure rate and conveying rate by response surface methodology,and performing multi-objective optimization on the regression model according to the importance of the optimization target,the optimal combination of the operating parameters of the cutting-conveying parts of the ramie combine harvester was obtained:when the forward speed was 0.85 m/s,the cutting speed was 1.40 m/s,and the chain conveying speed was 1.33 m/s,the cutting efficiency and conveying rate were the maximum and the failure rate was the minimum,with the values of 44.36 plants/s,93.60%and 4.16%,respectively.The optimized parameters were verified in the field on the ramie combine harvester.In the field test,the cutting efficiency,conveying rate,and failure rate were 43.80 plants/s,92.45%,and 4.52%,respectively,and the relative errors with the optimized values were 1.3%,1.2%,and 8.7%,respectively,which was relatively consistent.

Simulation and analysis of the pneumatic recovery for side-cutting loss of combine harvesters with CFD-DEM coupling approach

A novel pneumatic recovery method was proposed to curb the problem of high losses caused by side-cutting in a rapeseed combine harvester header.The influence of recovery method and material status changes on the recovery effect was studied via the CFD-DEM(computational fluid dynamic-discrete element method)coupling simulation.The effect of airflow action on the recovery effect was compared and analyzed,and the composite pneumatic recovery method was determined.In addition,the influence of material status changes and material feeding rate on the recovery effect was explored,and the critical condition of material blockage in the recovery device was configured.As such,the relationship model between air velocity and recovery rate was constructed and the air distribution ratio of the flow field in the device under this condition was optimized,had verified the rationality of this pneumatic recovery method was verified by a series of field tests.The average rapeseed recovery rate of 92.95%was achieved with the application of the recovery device,and the total loss rate of the header reduced by 52.26%,which is of great significance in reducing the total loss rate of the combine harvesters and improving the operation performance of machinery.The research results can provide a reference for the design of the header structure of a rape combine harvester.

Influence of nozzle enabling strategy on spray deposition of crop protection unmanned aerial system

Proper nozzles arrangement is significant to improve spray deposition of crop protection unmanned aerial system(UAS).Besides fuselage structure,the control strategy is another nozzle location changing method when there are multiple sets of nozzles.A four-rotor crop protection UAS equipped with four centrifugal nozzles was used to conduct a field experiment in the rupturing stage of rice.Two sets of nozzles in the front and rear of the fuselage were enabled independently to investigate spray deposition,including spray coverage and droplet density on the sampling cards.Various nozzle rotating speeds and flight speeds were employed in the experiment to study the influence of nozzle location on the deposition.With different nozzle rotating speeds,the droplet spectrum could be controlled.The results show that the average coverage and average cumulative droplet density are negatively correlated with flight speed.Average droplet density is also negatively correlated with the droplet size.Spray deposition of front nozzles is significantly reduced compared with that of the rear nozzles under the same spray parameters,especially when the droplet size is too large or the flight speed is too fast.The reduction is mainly concentrated in the center area of the spray swath.As a result,the average cumulative droplet density of the front nozzles decreases by 25.96%in total.The average droplet density decreases by 18.54%when the droplet size is smaller than 100μm,decreases by 25.02%when between 100μm and 200μm,and decreases by more than half when larger than 200μm.This research can provide guidance for the installation of UAS nozzles and spray control strategy design.

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.

Effects of tillage on soil nitrogen and its components from rice-wheat fields in subtropical regions of China

It is of great significance to explore the effects of different tillage practices on total nitrogen and its components in rice-wheat rotation farmland.The experiment was carried out in Jiangyan County,Jiangsu Province of China,and a total of four treatments were set up:minimum tillage(MT),rotary tillage(RT),conventional tillage(CT),and conventional tillage without straw retention(CT0).The total nitrogen(TN),light fraction nitrogen(LFN),heavy fraction nitrogen(HFN),particulate nitrogen(PN),and mineral-associated nitrogen(MN)in 0-20 cm soil were determined.The results show that MT increased TN concentration by2.26%-27.57%compared with the other treatments in 0-5 cm soil,but it lost this advantage in 5-10 cm and 10-20 cm soil.MT altered the concentration of LFN by 6.03%-95.86%,of HFN by 1.68%-20.75%,of PN by 12.58%-96.83%,and of MN by−1.73%-9.83%as compared to RT,CT,and CT0 in 0-5 cm soil,respectively.With the deepened of soil depth,the concentration of TN,LFN,HFN,PN,and MN decreased quickly in MT,which was lower than that in RT and CT at 10-20 cm soil depth.Straw return increased the concentration of TN and its components in 0-20 cm soil.The concentration of TN was extremely significantly positively correlated with that of LFN,HFN,PN,and MN(p<0.01).The variation of TN was significantly positively correlated with that of LFN,HFN,PN,and MN(p<0.01),and LFN showed the highest sensitivity to tillage practice.In general,minimum tillage combined with straw retention increased the concentration of soil TN and its components in topsoil.LFN was the best indicator to indicate the change in soil total nitrogen affected by tillage practice.

Experimental research on optimization of compression molding process parameters of pineapple rind residue

Currently,the process parameters for compression molding of pineapple rind residue are not clear.In view of this problem,a single die hole compression molding test device was designed in this study,and the force of material in a mold hole was analyzed.Using the test device,a three-factor three-level orthogonal test was carried out by using the particle size,moisture content,and die hole length-to-diameter ratio of pineapple rind residue as the factors and the particle molding rate,relax density,and specific energy consumption as the indicators.The test results were analyzed by range analysis,variance analysis,and fuzzy comprehensive evaluation.The test results show that the main and secondary factors affecting the comprehensive performance of pineapple rind residue compression molding are length-to-diameter ratio,particle size,and moisture content.The optimal parameter combination is the material particle size of 6-9 mm,moisture content of 16%,and length-to-diameter ratio of 4:1.The best indicators under these conditions are particle molding rate of 97.80%,relax density of 1.32 g/cm,and specific energy consumption of 44.17 J/g.These research results can provide a reference for the selection of processing parameters and the design of molding equipment.