Abstract:Taking the multi--directional valve as the research object, this paper analyzed the working principle and structure features of the valve, and the state equations of the multi-directional valve were built by using the pressure-flow equation, flow continuity equation and valve spool force balance equation, then the static and dynamic characteristics of the valve were simulated by using the Fourth-Order Runge-Kutta algorithm in the software Matlab/Simulink. Based on the test platform of closed center load-sensing hydraulic system, experimental study of the multi-directional valve were conducted, results showed that pressure loss of the whole hydraulic system was about 1.5MPa. During step changes of the displacement of valve spool, the pressure shock of multi directional valve was small and the response characteristics were good. In addition, the function of load compensation can be realized under the step changes of load pressure, meanwhile, the system flow rate was only concerned with the opening size of the flow control orifice in the multi-directional control valve, so it had a good speed regulating performance without being affected by load variations. The multi-directional valve can meet the requirements of heavy tractor electro-hydraulic hitch.

Abstract:A proportional controller for the electro-hydraulic hitch system was developed based on the microprocessor MC9S12XS128 of Freescale. According to the analysis of the structure, type and characteristic of present proportional controllers for the hitch system, the controller architecture was put forward following the control requirements. The software was designed in the environment of CodeWarrior, and the PID control algorithm was adopted to realize three control modes including traction, position and mixed control for hitch system. By taking the heavy tractor with electro hydraulic hitch system as the test platform, the field experiment of the proposed proportional controller was carried out, the response time of traction control was 3.89s while 0.81s of position control. The results showed that the proportional controller for hitch system comprehensive control in high-power tractor possessed of the features of rapid response, high precision, strong stability, etc. Meanwhile, it can not only improve the field operating efficiency in the guarantee of ride comfort and working quality of tractor, but also can reduce the driver’s labor intensity.

Abstract:According to the irregularities and complexities of farmland in rough terrains such as hill and mountain areas, a kind of agricultural driving chassis which can operate via four groups of tracked driving device with planetary structure (TDDPS) was designed. The device’s configuration characteristic, structural change and moving condition of running on the flat road, terrain adaptive locomotion in the field and overcoming the obstacles by turnover, and the passing principles of terrain adaptive locomotion or turnover were analyzed. The maximum height by terrain adaptive locomotion and the limit geometric height by turnover were calculated. The experiment proved that the chassis prototype had excellent off-road abilities, which can meet requirements for running and working in rough agricultural terrain.

Abstract:In order to solve the problem of high reseeding, miss seeding and instability issue in the vegetable tray precision seeder, the seedling performance was detected in the tray precision seeder based on machine vision technology. The performance detective device was setting in the tray precision seeder. Double camera took tray images one by one after the tray was detected by photosensor, and then these images were transferred to the computer in real time. The images were processed and analyzed by the vision algorithm software, the seeds could be seen in the tray and the results and photos were displayed on the screen together. The test showed that the reseeding detection accuracy was 98.94% and miss-seeding detection accuracy was 99.33%.

Abstract:A mechanical performance testing device for planter openers based on PLC was designed. The testing device mainly included control mechanism of working depth, six component testing device, hydraulic system and PLC control system. In order to improve the stability of working depth, closed loop feedback was adopted for real time control. Six component method was used to measuring mechanical performance of opener. The results showed that the measurement precision and the maximum relative error about the traction resistance was 1.49% FS and 3.7%, the vertical counterforce was 2.1% FS and 5.1%, and the lateral force of modified was 0.98% FS and 1.9% with the calibration. The precision of testing device can meet requirements, and the performance testing device can test the force and working depth of different types of openers in high accuracy.

Abstract:In order to study working parameters’ effect on flow field distribution in side positive pressure seeding device, LES (large eddy simulation) of Fluent software was used to analyze positive pressure flow field in seed-metering device. Simulation analysis and contrast experiment for positive pressure flow field were performed under different working parameters. Results showed that pressure field changed slightly in seeding device with increase of plate rotation speed when inlet pressure was set. According to velocity field, performance of seed metering was poor due to higher plate rotation speed. When plate rotation speed was set, pressure variation had non significant effect on seeding performance. According to seeding experiment results, seeding qualified index reached 91.30% when inlet pressure was 1.2kPa and plate rotation speed was 16r/min. Rotation speed of seed-metering plate was the significant affecting factor of seed metering performance.

Abstract:Based on problem that metering holes of centrifugal metering device were easily blocked and led to broken rows, the influential factors on blocking of metering hole was analyzed to develop a new structure of metering hole. The critical diameter of metering hole which only took one seed, two seeds or three seeds were determined via the model of relationship among rotation speed, structural parameters of hole and geometric properties of rapeseed. Combined with simulation of trajectory of seeds via discrete element method (DEM) software EDEM, the relevant critical diameter values of metering hole which only took one seed, two seeds or three seeds were 2.6mm, 3.5mm and 3.8mm, respectively. The test research was carried out to achieve the relationship of hole diameter, rotate speed and the performance of metering device. Experiment results showed that when the hole diameter was 3.8mm, variation coefficient of spacing row consistency and stability of full seeding quantity were less than 16.4% and 14.8%, respectively, and there was no blocked hole.

Abstract:Based on the mechanical and physical properties study of forage grass seeds, a 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 working length of central metering sheave relative to metering device housing. The stirrer inside of the sheave housing was used to prevent seeds overhead. And metering of different sizes of seed was adjusted by changing the position of internal components of slot wheel mechanism. Innovative design on 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 was a one-to-one correspondence between scale values and sowing quantity per hectare of different kinds of seed.

Abstract:To meet the dry land punch planting needs, a gear linkage cam combination planting mechanism which is composed of planetary gear, planetary carrier, connecting rod, groove cam and plant apparatus was designed. Through the modeling software Pro/E, the virtual prototype model of the plant mechanism was established and it was imported into the rigid kinematics simulation software ADAMS. Simulating the trajectories of the two duck-billed when the motion parameter λ in different conditions as λ<1, λ=1 and λ>1, the results showed that only when λ=1 the motion of plant mechanism could meet the zero velocity for seedling motion requirements and get better seeding status, testing the correctness and rationality of the parameter selection and mechanism design. Taking the self-made automatic vegetable transplanter as experimental prototype and planting mechanism as the research object, the experiment has carried out in two aspects: the planting uniformity and the upright degree of pot seedling. Experiments showed that seedling distance error rate was only 2.22% and seedling perpendicularity was good, proved that the designed planting mechanism could meet the planting requirements.

Abstract:The soil separation device, composited with vibration unit and transformation unit, was designed by using AIP software. The proposed device was assembled at the type QM-500 fruit seedling lifter came with a 58.8kW tractor. The experiments were carried out in the fruit seedling breeding base of Lixian county. Experiments showed that when the eccentric distance was 52mm, the tilt angle was 13.72°, the coefficient of travel speed variation was 1.02, the polar angle was 2.03°. The field experiments showed that the lifting efficiency was 1.6 plants per second. The manpower was decreased by 50.85% which reduced the labor intensity and realized the simplified operation of the apple seedling lifter.

Abstract:Unstable operation performance of mechanism for collecting plastic film results in low rate of collecting used plastic film. A crank-rocker mechanism for collecting plastic film was presented. The geometry and mathematic models of the proposed machine were built for simulating, analyzing and optimizing the work mechanism, then the working requirement for picking-up and removing the used plastic film was met. Field experiment showed that, the working efficiency of machine was higher than 0.4hm2/h, and the rate of collecting used plastic film was 88.5%. Basically, no operation wound problems were found during the whole experiment.

Abstract:According to brush features and height advantage of stellera chamaejasme during its early budding stage, a kind of targeted spraying device for its removed was proposed. The design of the frame system, spraying system, electrical control system and machine structure of the device were completed. By means of radar range sensor technology, the stellera chamaejasme could be automatically identified and site specific accurately sprayed. The results of real test showed that this device could effectively eliminate stellera chamaejasme with 87.1% pesticide adherent rate. This device could improve the efficiency of stellera chamaejasme removed and reduce the amount of pesticide used, which was benefit for reducing the environmental pollution caused by high amount of continuous spraying.

Abstract:Three structure and operation parameters which had effect on vertical axial-flow corn single panicle thresher were optimized. The quadratic rotary orthogonal experiments were carried out. Taking linear velocity of threshing cylinder, negative pressure value of fan, moisture content of cluster as effect factors, and broken rate, impurities, loss of entrapped grains, gettering drift loss as objective function, the structure size and operation parameters were experimented and optimized design. The result showed that when the linear velocity of threshing cylinder was 4.6~5.5m/s, the moisture content of cluster was 14.4%~15.9%, the negative pressure value of fan was 6.3MPa, the broken rate was less than 1.1%, impurities rate was less than 0.86%, loss rate of entrapped grains was less than 1.1%, and gettering drift loss rate was less than 0.44%. This experiment’s analysis could provide theory basis for the optimization design and operation parameter selection for the vertical axial single panicle threshing corn product.

Abstract:In order to separate, recycle and second thresh the no cleaned pod effectively, the Fluent software was used for optimization analysis of two different models of cyclone separator with or without bucket. The simulation results showed that there was no significant difference in pressure drop between the two models, cyclone with bucket had higher separation efficiency. Effect of bucket diameter and length on the capture time was not significant. The mathematical relationship model was established between bucket length, diameter and escape time, loss rate and pressure drop. Bucket diameter mainly affected velocity of spiral flow, and bucket length mainly affected the air flow distribution of entrance field. The best parameters of bucket were determined, i.e., the bucket length was 94mm and diameter was 196mm. Test was carried out to verify the improved model based on these parameters, and results showed that the loss rate was reduced to 2.2%.

Abstract:For the problem of the picking roller of present half-feeding peanut harvester was easily wrapped in plastic membrane, a kind of peanut removing device used spiral knife was designed. The structure optimization and experiment analysis were also carried out. The helical blade was modeled based on UG software. The best arrangement of the blade was confirmed by stress nephogram. Through the analysis of experimental data and processing, the best structure and operating parameters of the proposed device were got: the clearance was 5.3mm, speed of picking roller was 326r/min, and arranging blade angle was 43°. After optimizing, the breaking membrane rate value reached to 95.66%.

Abstract:In order to take advantage of the characteristics of growth and maturity of rape, overcome the disadvantage of high loss ratio and power consumptive of rape combine harvester, 4SY-1.8 type rape windrower was investigated. The novel windrower was designed for matching to walking tractor to meet both agro-mechanization and rape planting actuality in southern China. The design and construction characteristics of cutting, dividing, laying and hitching unit and considerations in the migration of rape stalks were analyzed. The results of field experiment showed that the windrower could complete the work of middle dividing and laying on both sides efficiently. The mean laying angle of rape stalk was 36.4°, which was less than 45°with 75.8% probability. The mean width of the piled stalk was 1072.6mm, which was less than 1150mm with 81.1% probability. The mean of stubble height was 278.2mm, which was between 230mm and 330mm with 85.2% probability. The test results indicated that it had a rational design and reliable function and its working quality can be easily met the agricultural requirement.

Abstract:In order to analyze the cutting performance of wheat straw, reciprocating cutting test bench for simulating the cutting process of wheat straw in laboratory was designed. The designed test bench was composed of body frame, chopped header, crank connecting link, AC motor and etc. The forward speed was 0~1.8m/s, cutting speed was 0~1.6m/s, cutting angle was 0~30°, and adjustable blade gap was in the range of 0.8~3mm. The paper mainly focused on the working performance of test bench and cutting performance for wheat straw. Orthogonal test with four factors and four levels and single factor test was carried out. The results showed that: with the range R, the order of factors affected the cutting performance could be determined as: cutting position, cutting speed, blade gap and cutting angle. With a given experimental factors and levels, the optimum combination of parameters were: cutting speed of 1.4m/s, cutting angle of 20°, blade gap of 1mm and cutting position of the third section of wheat straw.

Abstract:The basic structure and work principal of trail-type V-shape folding hay rake were introduced. The structure of the finger wheel which was the main working part of the machine was designed and the motion trail of the tooth was analyzed. The finger wheel of the machine was studied with simulation analysis by the ADAMS software. The double-hydraulic system was designed to realize automation control. Experiment results indicated that the hay rake had good performance and reasonable structure, the variation coefficient of uniformity of windrow was 15.8%, miss raking rate was 1.2% and leaf loss rate was 2.3%. The hay rake could fold or unfold into a V-shape, so the working raking width could be changed, it could be transported without any difficulties. The whole finger wheels could be risen and fallen automatically and its single finger wheel was adjustable, so it had a good profile modeling ability. The hay rake could perform rake and tedding simultaneously.

Abstract:Aiming at the design requirements on the main equipments of the forageseed processing line—not only work continuously on set, but also work independently—the processing line was designed. The processing line adapted the style of host plane layout and hopper feeding at different sites, and combined series conveying material by head-shaped lifter. The structure of the tee with door, pipe connection clip and dust removal pipe air separation unit was designed. Taken the Elymus nutans Griseb with purity 85%~88% as processing object, the experiment was finished. The results showed that the productivity was no less than 800kg/h, the purity was no less than 97%, the percentage of chosen seed was no less than 95%, the Kilowatt hour productivity was no less than 25kg/(kW·h), the effective use degree was no less than 95%, and the dust concentration was no less than 0.3mg/m3.

Abstract:To acquire better flattening performance of the alfalfa cutting and flattening machine, a kind of test bench was proposed. According to alfalfa flattening impact factors, including flattening gap and velocity, alfalfa growth, machine walking velocity and so on, the flattening device, drive system and data acquisition system have been designed. The multi-factors orthogonal test for alfalfa flattening was executed by changing the flattening roll gap, flattening roll rotational speed and feeding rate on test bench. The results of validity test showed that the pressure values between flattening rolls showed a regular change, and the most significant impact factor of the nutrient content of alfalfa is the spreading quantity, followed by the roll gap, feeding rate and roll rotational speed. This alfalfa flattening test bench can simulate the actual operation effectively, and provide the guidance of alfalfa cutting and flattening machine design.

Abstract:Heavy metal pollution caused enormous risks to human health and ecosystem. In this paper, soil heavy metal concentration was determined through sampling from different land use types in the watershed of Binzhou. With DEM data and remote sensing image, the main routes of pollution from non-point sources, i.e., surface runoff and soil erosion of different land use types were estimated based on SCS-CN model and RUSLE model. The precision of the model was validated and analyzed and heavy metal copper (Cu), lead (Pb) pollution loads from non-point sources in the watershed of Yellow River were estimated. The results showed that big differences exited among the soil heavy metal concentration background values from different land use types in the study area: in industrial land, mining land and grassland, the background value of Cu and Pb was high; in woodland, the value was low. The total loads of Cu and Pb was about 651913kg/a and 268004kg/a. The variation ranges of heavy metal pollution loads from soil erosion were large as well: the values in sparse woodland and grassland were the highest; in woodland and irrigable land were the lowest. The value of heavy metal pollution loads from surface runoff also differed greatly: the value in grassland and sparse woodland was much higher than in woodland and dry land. The research could be used for further analyzing the characteristics of the transfer of heavy metals, studying the heavy metal loads from non point source, and adjusting the land use structure reasonably.

Abstract:Based on researches of light-temperature production potential, availability and regional planning of rice in Hubei province using GIS method, this paper reported the establishment of GIS based database by combination of mechanism method and experience approach, with the support of data of sub counties’ (cities, districts) rice actual production, meteorological data, terrain and etc. in Hubei province between years 1993—2012. The potential productivities of light, temperature, climate, arable land, yield-increasing potential and potential increase space were calculated by considering rules of production and development of middle-season rice. The yield potential was divided into five districts and the charts were drawn respectively. Natural resources and utilization status in different middle-season rice growing regions of sub-counties and cities in Hubei province were investigated further. The potential yield of middle-season rice in Hubei province is great and the theoretical value can reach 11877957 tons. The main limiting factors of potential yield are the arable land and the climate. The results of this study and the established database will provide valuable referees for guidance and plan of rice cultivation, industrial restructuring and implementation of high technology project in Hubei province.

Abstract:The water droplets impact of irrigation equipment is an important technical indicator for measuring nozzle performance. The impact force of water droplets hit the surface of the soil would erode the soil, causing soil compaction, resulting in runoff affect the infiltration effect, while water droplets impact would cause foliar damage, which affects crop growth. This paper developed a droplet impact automatic detection system to measure the water droplets impact force. The PVDF piezoelectric sensor was chosen as the sensing element, and the water droplets automatically generating device was designed by a stepping motor drive and system was controlled by a microcontroller. The USB7333 high speed data acquisition card was used and the program was written in LabWindows/CVI based computer data acquisition and process procedures to detect the water impact force. As the result, in the frequency of water droplets, the size of the stability control experimental conditions, the detection system could achieve the dynamic measurement of different droplets size to show that the PVDF piezoelectric sensor for detecting water droplet impact with good dynamic response. The result proved that the water droplets micro force sensor output voltage had a good linear relationship, and the trend line with the actual data fitting degree of 0.936, the system measurement error less than 10%. This droplet impact force detection system solves the traditional manual measurement method of water droplets instability problems and has great practical application value.

Abstract:At present, substrate cultivation has been widely used for planting a variety of fruits, vegetables and flowers. Since the invention of nutrient solution used in substrate culture techniques, the decision making irrigation methods mainly adopted three ways in greenhouse, i.e. irrigation scheduling respective by time clock and radiation, and a way based on Penmen equation. But there were some defects above the three ways, the first two ways were not considered the demand for water of crops in different time in a day and growth period, leading to the supply more or less, and there were too many parameters to be determined in the last way. The negative pressure irrigation system could supply water for the plants timely and accurately according to the consumption by the plants themselves at any time of a day and the influence of different external environment, which only involved a parameter—consumption, and was easy to operate. An automatic decision making method and system of irrigating nutrient solution in substrate culture in greenhouse based on negative pressure, which allowed us to decide the supply amount for most crops based on a small amount of crops consumption. This automated decision-making system ensured the plant roots in the balanced condition of water and nutrient (EC and pH value), which achieved a more efficient nutrient solution management in the substrate culture. This automated decision-making system adopted the consumed amount of nutrient solution in a line of plants in a certain time, in which line the negative pressure irrigation system was installed. The value obtained from consumed amount of plants of a line multiplying by a leaching-coefficient was used as supply volume for the other plants in substrate culture by drip irrigation system in the next time. The coefficient is related to the amount of drained nutrient solution. Commonly, 25%~30% of the applied nutrient solution should to be drained, which could prevent salt accumulation in the substrate. Moreover, the time and frequency for supply in other lines in one day was determined by the consumed amount of nutrient solution in a line. The consumed amount in a line was measured by flow sensor which was connected with the singlechip in a fixed time, then an order was given by the singlechip to control the work of the magnetic valve and collect the values from flow sensors in the other lines. At the same time, tomato plants in the substrate culture lines were irrigated nutrient solution by time clock as control test. Experimental results showed that the yield per plant of tomatoes that the automatic decision-making system based on negative pressure increased by 6.70% compared with the irrigation scheduling by time clock, while the consumption of nutrient solution decreased by 28.13%. It proved that the automatic decision-making system ran well and was able to supply the tomato plants nutrient solution timely and accurately according to the water requirement regularity of tomato plants per day.

Abstract:Soil pretreatment parameters play significant impacts on the accuracy of ion-selective electrode (ISE) in direct soil slurry detection. In this paper, the average relative error (RE) was used to evaluate the influences of three main pretreatment factors, including mesh size, shaking time, and settling time. First, the range of three factors was determined based on the single factor experiment. And then, a 3level, 3-factor Box Behnken experimental design was conducted to investigate their effects. The relationship between RE and three factors was quantitatively described by a multivariate quadratic model through the response surface method. The results showed that settling time was the most influencing one among three tested factors. Mesh size was less significant than shaking time. Coupling settling time and mesh size, the optimal pretreatment parameters were obtained to minimize the detection error, the mesh size was 2mm, settling time was 1.4h, and shaking time was chosen to be 22min. Under the optimized parameters, the RE of the validation soil group were all less than 7.5%, which indicated the prediction accuracy, and the predicted results had a high fitting degree with the measurements. In all, the model was promising for accuracy prediction and analysis in the ISE-based soil slurry measurement.

Abstract:In order to find optimal regulated deficit irrigation scheduling with saline water for better oil quality, higher yield and safer management of high oleic oil sunflower, a pot experiment was conducted and the principle component analysis method was used to establish a comprehensive irrigation quality index of saline water by the weighted sum of different evaluation indices. Then, this index was applied to evaluate and analyze the performance of saline water deficit irrigation effect. The results showed that comprehensive irrigation quality principle component obeyed normal distribution significantly, and included 93.29% primordial quality attribute variation information with better representation and objectivity, and thus it could be used as the overall oil sunflower regulated deficit irrigation with saline water evaluation index. The critical concentration of saline water for oil sunflower in Hetao Irrigation District is 3.5g/L, and the most suitable period of water deficit is the floral initiation stage. When the concentration of saline water is low (less than 3.5g/L), the regulated deficit irrigation with saline water has less effect on the yield and quality of oil sunflower. When the concentration is 3.5g/L, irrigation scheduling with mild deficit（80%） in floral initiation stage and 27828mm water amount during the total growth period should be the optimal irrigation pattern for saline water of regulated deficit irrigation with the coordinated yield and quality of oil sunflower.

Abstract:Heliogreenhouse has become the major protected horticulture industry in China due to its environmental friendly and energy saving features, however, the healthy development of heliogreenhouse is still limited by many problems. In view of extremely CO2 deficient and water resources waste caused by lax water management in heliogreenhouse, we investigated the growth and photosynthetic characteristics of tomato plants under four different CO2 levels, i.e., ambient CO2 concentration in heliogreenhouse (about 450μmol/mol), elevated CO2 concentrations are (700±50)μmol/mol (low), (1000±50)μmol/mol (moderate), (1300±50)μmol/mol (high) combined with three different water levels, i.e., substrate water content are 35%~45% (low), 55%~65% (moderate), 75%~85% (high) of saturated substrate water content. The results showed that biomass of below ground, net photosynthetic rate, chlorophyll contents (SPAD) were increased and plants bloomed 6~11 d earlier in moderate and high CO2 level plants. AQY and ACE were markedly increased by 45%~118% and 66%~81%, respectively; meanwhile, LCP was significantly reduced by 34%~57% in CO2 enrichment plants under moderate water condition. Compared with low water level, Pmax was markedly increased by 42.8% and 52.1%; AQY was markedly increased by 10.7% and 25.9%; LCP was reduced by 29.1% and 63.4%; CCP was reduced by 20.8% and 8.3% in moderate and high water level plants under the measured high CO2 condition, respectively. Compared with the plants grown under ambient CO2 concentration, the MDA content reduced by 4%~10% in CO2 elevated plants under low water condition, this indicated that CO2 enrichment could alleviate oxidative damage of tomato plants that subjected to low water condition. Compared with the plants that grown in moderate water level under ambient CO2 concentration, blooming time was 3~7 d earlier and yield of first spike fruit was increased by 18%~44% in low water level plants under CO2 elevated conditions, meanwhile, compared with the plants that grown in high water level under ambient CO2 concentration, blooming time was 8 and 10 d earlier and yield of first spike fruit was increased by 42.8% and 34.0% in moderate water level plants under moderate and high CO2 condition, respectively, this indicated that water use efficiency which related to yield was enhanced by elevating CO2 concentration.

Abstract:Taking “Zhongza 105” tomato as tested material, the experiment focused on the effect of different CO2 enrichment concentrations and different nutrient supply intensities on the growth of tomato cultivated in substrate in solar greenhouse. This study set up 4 CO2 levels, including no enrichment (C0), (700±50)μmol/mol (C1), (1000±50) μmol/mol (C2), (1300±50)μmol/mol (C3) and 3 nutrient levels based on a dose (S) of Yamazaki tomato recipe nutrient solution concentration, including 1/2S (F1), 1S (F2), 2S (F3). The results indicated that stem diameter, SPAD value of leaves, fresh and dry weight of plants, nitrogen content of leaves and weight of the first spike fruit were increased significantly with increasing nutrient quantity at the same CO2 level, and blooming date was advanced. CO2 enrichment increased stem diameter, SPAD value of leaves, fresh and dry weight of plants and weight of the first spike fruit, but reduced the position of the first inflorescence and made blooming date ahead of time at the same nutrient. When the concentration of CO2 enrichment was (1000±50)μmol/mol or (1300±50)μmol/mol, the nitrogen content of leaves was elevated. The promoting effect of CO2 enrichment on the growth of tomato was associated with nutrient quantity, under low and moderate nutrient conditions, CO2 enrichment at (1000±50) μmol/mol was adequate for reducing the position of the first inflorescence of 1.0 compared with the control (C0F1 or C0F2), advancing the florescence for 5~8d and increasing the weight of the first spike fruit significantly. Under high nutrient condition, CO2 enrichment at (1300±50)μmol/mol made the position of the first inflorescence lowest, 1.7 lower than the control (C0F3), the florescence was the earliest, which was 10d earlier than the control, and the weight of the first spike fruit was the maximum, 24.15% higher than the control. The response of position of the first inflorescence, florescence and weight of the first spike fruit to CO2 enrichment depended strongly on the level of nutrient supply. High nutrient level improved the response of these indexes to CO2 enrichment. According to the entire growth index, C3F3 was the best combination of CO2 and nutrient, its stem diameter and weight of the first spike fruit were the maximum, position of the first inflorescence was the lowest and blooming date was the earliest.

Abstract:To determine the variation of tillage on carbon dioxide (CO2) and methane (CH4) fluxes from winter wheat fields in Beijing’s suburb, different tillage methods were experimented in Qingyundian Town, Daxing District, Beijing. CO2, CH4 fluxes were measured using static chamber-gas chromatographic techniques during two seasons of winter wheat (October 2011-July 2012 and October 2012-July 2013). The experimental results of the four tillage methods, i.e., no tillage (NT), subsoiling tillage (ST), rotary tillage (RT) and conventional tillage (CT) showed that soils with winter wheat were the emission sources of atmospheric CO2, and the sink of atmospheric CH4 during crop growth seasons. Daily and seasonal variation of CO2 and CH4 fluxes changed significantly for NT, ST, RT and CT treatments, respectively. The maximal daily emission flux of CO2 appeared at 0:00 am, and the minimum emission appeared at 10:00 am. The maximal seasonal emission flux of CO2 appeared at seedling and maturing stages of winter wheat and the minimum emission appeared at winter dormancy stage. Daily and seasonal variation of CH4 fluxes under four tillage treatments showed a significant difference, but no significant variety regulation. The seasonal CO2 flux positively correlated with soil temperature in 0~20cm soil layer, while negative correlation was found between the CO2 emission and soil moisture in 0~30cm soil layer. The seasonal CH4 flux positively correlated with soil temperature in 0~20cm soil layer. In winter wheat fields, the seasonal mean CO2 emission flux demonstrated as CT>RT>ST>NT, and the seasonal mean CH4 absorption flux demonstrated as RT>CT>NT>ST. Compared with RT and CT, NT decreased soil CO2 emission flux by 23.3%~27.1%, and increased soil CH4 absorption flux by over 20%. Generally, all the four treatments (NT, ST, RT and CT) enhanced CH4 assimilation at different levels, and no tillage would be a better tillage practice to reduce CO2 emission for winter wheat fields in Beijing’s suburb.

Abstract:This paper took rape straw as the research object. Based on the TG/DSC-FTIR-MS technology, the dynamic characteristics of combustion were studied systematically with different air flow rates and sample particle sizes. And the qualitative and quantitative characterization analysis of main gas emissions was conducted. The results showed that there was no significant difference on combustion characteristics under different factor-levels. During each burning process, most gas escaped, including a larger amount of CO2 and a smaller amount of alkane gases such as NOx, SO2 and HCl with a diminishing magnitude. Also intensity curves of gases released corresponded to the characteristics of thermal weight loss rate. Quantitative study on the dynamic characteristics of combustion and gas emissions using TG/DSC-FTIR-MS technology could provide basic data and methodological support for the rape straw as environmentally friendly renewable energy.

Abstract:Taking corn stalks in Beijing Daxing District as the main raw material, and the peanut shells and wheat straw as affixation, the combustion characteristics of mixed materials were studied by using thermogravimetric analysis. The combustion dynamics was analyzed by using Coats-Refern method to offer practical and theoretical data for crop straw combustion. Studies showed that combustion curve of three samples had two distinct peaks, which could be divided into four basic stages: water evaporated to dryness, the combustion of volatiles, fixed carbon combustion and burnout. At the same time, a larger overlapping area was laid in the entire combustion stage. The combustion characteristics and kinetic parameters of mixed materials were influenced by adding peanut shells, and less affected on adding wheat straws.

Abstract:Xylooligosaccharides producing solid waste (XPSW) was the main solid waste of xylooligosaccharides producing from corn cobs. To utilize that biorefinery waste, biodegradable seeding pots were prepared using XPSW as main ingredient through dry thermo compression molding method. The most economical formula of raw powders for XPSW based seeding pots was screened out as XPSW∶wheat bran∶adhesive∶release agent=68∶26∶6.3∶1 by weight. Also the molding parameters were optimized by orthogonal test, and the optimal compression temperature, compression pressure and holding time was 180℃, 180MPa and 4.5s, respectively. Under those conditions, the dry compress strength of XPSW based seeding pots was 2251N, and wet compress strength was 417N. Compare to corn cobs, higher lignin content and lower hemicellulose content of XPSW made the XPSW based seedling pots had better mechanical strength and lower water absorption. Fungal-growth test showed that the XPSW based seedling pots had good biodegradability.

Abstract:In order to solve the low control accuracy and tracking error in the maximum power point tracing (MPPT) control in traditional photovoltaic, which was easily occurred under the natural dramatically changing environment, the paper presented a voltage predicting model based on least squares support vector machine (LS-SVM) for the prediction of the voltage of the maximum power output in the PV system, through which the maximum operating point voltage could be predicted, then the reference voltage of constant voltage control method could be modified and MPPT control of the PV system could be eventually realized. Simulation results showed that the model had higher accuracy in prediction, the relative error was less than 004, and the modified control method could guarantee maximum power tracking of the PV system quickly and stably, avoided the phenomenon of tracking error.

Abstract:An electrode for the detection of rutin in tea and pill was produced and fabricated, which was modified by the glass carbon electrode (GCE) surface by graphene (GR) nanometer materials and n-octylpyridinum hexafluorophosphate (OPFP). Different electrochemical methods such as cyclic vohammetry, impedance spectroscopy and square wave voltammetry were used to investigate the electrochemical behaviors of rutin on IL/GR/GCE, indicating that greatly improved the electrochemical performance and detection response due to ionic conductivity and adhesiveness of room temperature and the large specific surface area and high electron transfer of graphene. Under the optimal conditions using square wave voltammetry, the rutin oxidative peak current was linearly related to its concentration in the range from 0.05μmol/L to 11μmol/L with the detection limit estimated to 0.01μmol/L(S/N=3) and the linear regression coefficient was 0.997. Finally, the developed electrode was successfully applied to detect the content of rutin in real samples, which displays good stability and excellent anti-interference ability.

Abstract:Neutrase hydrolysis of WPC produces hydrolysates that were proved to enhance iron uptake by Caco-2 cells. The objectives of this study were to investigate effects of components of hydrolysates and digestion products of hydrolysates of neutrase treated WPC on iron uptake. The hydrolysates of WPC treated with neutrase were separated by ultrafiltration. Effect of different components of hydrolysates on iron uptake was studied by in vitro digestion combined with Caco-2 cell model. The results showed that low-molecular components (below 10kDa) enhanced iron bioavailability significantly (p<0.05). The components of 3 kR（3~10kDa）and 3kF（below 3kDa）increased iron bioavailability to 23.32% and 24.23%, respectively, compared to untreated WPC (2.58%). Bioavailability of iron from ferrous sulfate added with different components of the hydrolysates was significantly associated with iron absorption (r=0.935, p<0.01), while there was no significant relation between iron dialyzability and bioavailability. The hydrolysates of neutrase treated WPC was digested by pepsin and trypsin gradually to obtain the digestion products, and then separated into four components of differentmolecular weight by Sephadex G-25. Iron absorption was studied by Caco-2 cells. The results suggested that the components at molecular weight no more than 1kDa significantly (p<0.05) increased iron absorption to 90.47% compared with 25.13% in the control, while the components with molecular weight at 1~5kDa acted as inhibitor.

Abstract:There are a number of problems on the application of frozen dough technology which is developing rapidly and used widely on baking industry or other flour products industry now，such as the decrease of yeast activity, longer fermentation time, deterioration of dough quality, smaller product volume and a rough crumb. However, the use of hydrocolloids can enhance the properties of either frozen or unfrozen dough. Several researches have been done to discuss the application of a few hydrocolloids on frozen dough technology. The objective of this study was to systematically understand the effect of hydrocolloids on bread dough and the influence of xanthan gum (X), sodium caseinate (SC) and gum arabic (A) on the tensile properties, yeast fermenting power and freezable water content of fresh and frozen dough by using FTC texture analyzer, absorption titration method and differential scanning calorimeter. The result showed that three gum all could significantly enhance the tensile resistance of the dough (both fresh and frozen dough), and X caused most obvious increase by 76% and 58%, which made the maximum tensile resistance of fresh and frozen dough. For yeast fermenting power, dough with X or A both showed a higher yeast power of gas, which improved the gas production of fresh and frozen dough by 119% and 208%, 83% and 113%, respectively, while SC had no effect. For freezable water, the three kinds of gum reduced freezable water content in frozen dough，which played a role in protection of yeast during freezing, and the effect from large to small was A, X and SC. To realize the influence of hydrocolloids on bread quality, the bread made of fresh and frozen dough added X, SC or A with the indicators of bread specific volume and textural properties of crumb were evaluated by texture analyzer. The results showed that A improved either fresh or frozen dough bread quality, which increased the specific volume of bread made with fresh and frozen dough by 9% and 16%, respectively. X and SC had no positive effects on overall bread quality, but X had a positive effect on improving the resilience of frozen dough bread crumb.

Abstract:The high intensity pulsed electric fields (PEF) technique was applied for assisted extraction of mussel polysaccharides to improve the efficiency of mussel polysaccharides extraction. The single factor test and Box Behnken design results showed that electrical field strength and pulse number were the significant affecting factors on the extraction efficiency of mussel polysaccharides. With mathematical regression model analysis of extraction efficiency and the impact factor, the optimal combination of parameters was found that electrical field strength was 25kV/cm, pulse number was 8, water powder ratio was 40mL/g. Under the optimized condition, the extraction rate of 2g mussel was up to 4.99% (polysaccharides wet weight sample ratio). Compared with ultrasonic technique, high intensity pulse electric fields is less time consuming with higher extraction efficiency. The study can provide a reference for further studies of extraction of mussel polysaccharides.

Abstract:Chinese jujube originated in China and has a long historical standing. China is the only country which can produce a great amount of Chinese jujube in the world. Modern research showed that the nutrition of Chinese jujube is abundant. Chinese jujube has great medicinal and food value, with high economic value and good prospects for development. Shrinkage characteristics of dates generally refer to volume shrinkage characteristics of whole dates. Large fruit and plump grain appearance of dates is the first choice of consumers to buy elements. The volume of dried jujube points to the consumer’s heart, and is an important indicator of consumers whether to buy. Jujube processing enterprises grade the date in accordance with its size, different grades dates have different value and price. Therefore, drying is the most important steps during the dates processing as it affects directly the quality of the product, and the shrinkage characteristics is the most important quality characteristic of Chinese jujube after drying. However, the traditional natural desiccation and desiccation in the drying room of the red dates has many problems. The conventional drying method for Chinese jujube has some disadvantages of severe shrinkage, long drying time and large energy consumption etc. Therefore, in order to improve the quality of dried Chinese jujube and reduce the shrinkage, it is imperative to replace the traditional drying method with the modern technologies. Air impingement drying technology was applied to dry Chinese jujube. The drying characteristics of shrinkage, moisture effective diffusivity considering shrinkage characteristics and the activation energy of Chinese jujube shrinkage were investigated under different air temperatures (55, 60, 65 and 70℃) and air velocities (6, 9, 12 and 15m/s). The dynamic changes of the regular pattern for the shrinkage characteristic of Chinese jujube in the air impingement drying process were studied, the results showed that the volume relative shrinkage ratio of Chinese jujube appeared to increase and then decrease with the increase of air temperature and air velocity. Considering shrinkage characteristics, the moisture effective diffusivity of Chinese jujube in the air impingement drying process through the Fick’s second law was obtained. The diffusivity appeared to increase and then decrease with the decrease in moisture content in dry basis of Chinese jujube. The Arrhenius equation calculated the shrinkage activation energy of the Chinese jujube was 1281kJ/mol. This research provided technical basis for shrinkage characteristics of Chinese jujube using air impingement drying technology.

Abstract:The ambient air dehumidification needs cooling down the air temperature in conventional heat pump dehumidification system. However, it decreased the temperature of hot air to the grain dryer, which reduced rice drying rate and increased energy consumption at the same time. A heat pipe heat exchanger was installed on the two sides of evaporator of heat pump dehumidification system, which was used for pre-cooling and pre-heating of ambient air respectively, so that dehumidifying capacity can be enhanced and the hot air temperature can be increased. Experiential results showed that with heat pipe in the system, the energy consumption of dehumidification were reduced by 9.6%~28.4% when air relative humidity was 60%~78% at 27℃. Meanwhile, the results demonstrated that dehydrating 1kg water from rice consumed 1560kJ energy when inlet air with relative humidity of 80.2% at 26.2℃, and saved 18.2% of energy compared with traditional heat pump dehumidification system.

Abstract:For strawberry harvesting, when strawberries are overlapping or covered by leaves, high positional accuracy of end-effector is required and the recognition and detection algorithm is very complex and time-consuming, otherwise the strawberries will be abandoned. To solve the problem mentioned above, a large misalignment tolerance end-effector, which can be used for picking up multi strawberries at one time, was designed. The end-effector, using the harvesting method of collecting strawberries down to up and away from obstacle, clamping and cutting stems, was composed of a collecting-clamping cutting device and profiling ridge device. The end effector was mounted on harvesting manipulators. Experiments were conducted and results showed that the proposed end effector had satisfactory performance when positional error in the range of ±7mm, and could pick up three ripe strawberries at one time without separating overlapped ripe strawberries; while fruits area containing single fruit, two fruits, or three fruits, the average time of picking one time respectively was 2.00s, 2.13s, 2.28s, and the success ratio of harvesting was no less than 97.7%.

Abstract:To improve the grafting rate and automation of grafting robot used currently in seedling production, a high efficiency vegetable grafting robot operated by one person for cucurbitaceous seedlings cultivated in humus pots was designed based on splice grafting method. The machine consisted of six units, i.e., a scion gripping and transporting unit, a scion straight cutting unit, a stock gripping and transporting unit, a stock rolling cutting unit, a clip auto arranging and sending unit and a grafted seeding bowl auto arranging unit. Experiments were conducted in laboratory and field. Results showed that the success rate of grafting was 92% and the practical grafting rate was 285 plants per hour (with the theoretical grafting rate of 440 plants per hour). Under the same success rate of grafting, the grafting rate of this machine was 36% higher than the grafting machine for cucurbitaceous seedlings cultivated in humus pots operated by two persons.

Abstract:To accurately detect the baseline of crop row in real time, a navigation line extraction method that combine boundary detection and scan-filter (BDSF) was proposed. Firstly, the binary image that contained the crop row information was obtained correctly after image preprocessing, including gray scale processing which adopted the G-R color feather method, and binary processing which use the OSTU method. Secondly, the position of crop row was calculated by vertical projection of the image top and bottom. Thirdly, numbers of rectangle bars of width equity was used to scan the effective information of image points in the rectangle boxes. Finally, the navigation line was extracted according to the scanning results. The experimental results showed that, the BDSF algorithm could quickly and accurately extract the navigation line. The time consumption for single image of 640 pixels×480 pixels was about 67ms. Compared with Hough transform and LSM algorithm, the designed algorithm had the advantages of high speed and good robustness.

Abstract:GNSS controlled (Global navigation satellite system) land leveling technology plays an important role in improving the landform of field surface, also in enhancing use efficiency of water and irrigation efficiency. Aiming at improving the working efficiency of GNSS controlled land leveling system, the application of real-time intelligent navigation technology, which provided decision-making aid in land precise leveling, had explored. A tension sensor was added into this GNSS controlled land leveling system to realize the load monitoring of the forklift. The model of real-time land planning and navigation during the time of land leveling was set up, using mathematical modeling methods. The destination point of tractor was calculated with the load data and the terrain around it, in the principle of reducing the times of overload and empty load situations. Therefore, the turning angle could be calculated to give the navigation information to the users. Farmlands experiments were taken in the end and it turned out that: firstly, this method could be used to guide the driving in the process of land leveling quite well. Secondly, within the same leveling time in these experiments, the leveling effects with land planning and navigation functions showed to be much better than those of without. Finally, the sum proportion of overload and empty load when the land planning and navigation functions worked was no more than 69%, much better than the situation of without these functions.

Abstract:In order to evaluate comprehensively lettuce leaves phosphorus content and precisely control phosphorus fertilizer quantity, the specific aim of this study was to attempt a strategy for measurement of phosphorus content integrating spectroscopy together with synergy interval partial least square (siPLS) and back propagation artificial neural network (BPANN). Leaves reflectance was acquired with a Fieldspec 3 spectroradiometer that provides measurements in the 350~2500nm spectral range, and then five points smoothed and first order derivative transform were used to eliminate noise effects. siPLS was used to search for the optimal spectral intervals, which corresponded to 950~1070nm, 1430~1549nm,1906~2025nm and 2144~2263nm. 63 wavelengths were selected from 350~2500nm and 25 wavelengths were selected from four optimal intervals by successive projections algorithm (SPA). Principal component analysis (PCA) was implemented on the spectra intervals or variables, finally 7, 4 and 5 PCs were obtained. The siPLS+BPANN, SPA+BPANN, siPLS+SPA+BPANN models were achieved when the number of neurons in the hidden layer was 7, 5 and 3. It was conclude that spectroscopy combined with siPLS+SPA+BPANN were feasible to measure phosphorus content in lettuce, which had better performance than others model, correlation coefficient for the prediction set was 0.911, root mean square error of the prediction set was 479mg/kg.

Abstract:In order to meet the requirements of the periodic cutting and cleaning of aquatic plants in river crab aquaculture, a small and medium sized intelligent automatic aquatic plant cleaning ship based on ARM was designed. Then the mechanical structure and working principle of the integration of harvest were introduced, and the ship’s main structure characteristics were also put forward, such as the paddle propeller without a rudder, rotary cutting device, cut deep automatic adjustment regulator and so on. The closed loop control system of GPS navigation for the ship was designed with PD and PI control technology of intelligent mobile robot, and high precision GPS navigation control technology. The experiment results showed that the control precision of linear track could be controlled precisely within the scope of ±30 cm. On the basis of meet harvest requirement, the control system can avoid the repeat cutting or miss cutting caused by yaw effectively.

Abstract:The kiwifruit automatic grading machine is an important machine for postharvest processing of kiwifruit. A set of practical automatic kiwi fruit grading machine was designed based on technologies of mechanical separation and conveyance, image capture and processing as well as intelligent control. This set of equipment mainly consisted of material storage bin, single line positioning system, image capture system and grading executive system. And it also has programs of image capture, image processing, grade determination and human-machine interaction for the host computer as well as control programs for the slave computer. By testing, this machine was capable of grading by three features of size, shape and surface defect and their grading accuracy could reach to 88.9%, 91% and 94%, respectively. And the accuracy of integrated grading could reach to 86%.

Abstract:In order to simulate the natural growing environment of Schizothorax prenanti as well as come up with an intelligent facilities fishpond design, the fishponds achieved micro flow effect and intelligent monitoring of water quality parameters by taking use of concrete structure, combined with water pipe, water pump, solenoid valve, water quality parameters detection sensor and ZigBee network. Based on 32 bit embedded MCU and WinCE 6.0 embedded operating system, PDA form gateway nodes were designed. By transplanting embedded SQlite database on gateway nodes, ZigBee network site management was achieved. Control instruction was obtained through analyzing data with fuzzy neural network method, and then closed loop control was achieved. Further experimental tests showed that average packets loss rate of ZigBee network was 0.52%, micro flow deviation was within the range of ±1.8cm/s, temperature deviation was within the range of ±0.5℃, dissolved oxygen deviation was within the range of ±0.4mg/L, pH value deviation was within the range of ±0.3. The water quality parameters completely meet the requirements of Schizothorax prenanti breeding environment; therefore network monitoring could be applied to breeding factories with different scales.

Abstract:The construction of farmland conduit is a major part of irrigation facilities. Most farmland conduit is built by human and general excavator in China, the shape of conduit is not standard and the surface is very coarse. It is a main reason that a lot of water was wasted in the transportation process, so improving the quality of conduit construction has a significant role in achieving the target of agricultural water conservation. According to the status of special equipment for farmland conduit construction is exile, 1KY-40 hydraulic drive ditcher for farmland conduit was researched and designed in order to meet the needs of high quality farmland conduit construction. The ditcher is a tractive structure and its operating principle is that the symmetrical cutter is driven by an independent hydraulic power system so as to cut soil, the cutter can cut and throwing soil, the ditcher is dragged by tractor and the conduit with trapezoidal section can be excavated. The GPS automatic navigation system was integrated in the tractor, which can improve the trenching operations to improve linear precision of ditching. The test showed that the ditching depth of the ditcher was 407mm, the operating speed can be up to 0.12m/s, the stability of the ditching depth was 97.1%, the top width of conduit was 984mm and bottom width was 305mm, the linear deviation of ditching was less than 90mm when soil water content was 15.8% and soil compactbility was 0.31MPa under the condition of using the GPS automatic navigation system. The application experiments of 1KY-40 hydraulic drive ditcher for farmland were completed in Beijing, Jiangsu and Heilongjiang of China. The experimental results indicate that it can meet the construction of trapezoidal section conduit under the local soil conditions.

Abstract:A sun tracking system was developed in order to improve the collection efficiency of solar air collector and receive more solar energy．Several main tracking modes were briefly introduced. The passive tracking mode was likely to be perplexed by weather condition and the active tracking mode could not avoid the cumulative error．A single axe automatic tracking mode which combined active tracking mode and passive tracking mode wais presented．The proposed combined mode overcame the shortcomings of the two modes．Experiments showed that this system works with high precision，good stability and little loss of solar energy．Automatic tracking system could make the collector outlet temperature increased an average of 15℃, so that the collector efficiency was improved.

Abstract:Based on the characteristics of morphology and hardness distribution of scapharca shell surface, a bio inspired model of the material coupled with pattern was proposed. The major and minor relationship and optimal combination of the main factors which affected the erosion resistance of the bio inspired surface was obtained through experiments. Erosion resistant tests were carried out under the following test conditions: abrasive was the compound of silica sand of 80~140 mesh size and water; wear time was 30h; and the rotating speed of 1400r/min. Compared with the smooth testing samples, the erosion resistance of the smooth testing sample of alloying with laser, the smooth one of laser hardening, the bio inspired model with the non smooth pattern and the bio inspired model of the material coupled with pattern can improve the anti erosion performance of the samples surface. The bio inspired model of the material coupled with pattern was the best one among all the testing samples. The order of major and minor factors affecting the relative wear rate of samples was laser hardening, amplitude, periodic and the stripe direction. Results showed that the testing sample with optimal anti erosion performance was the one with laser surface strengthening, amplitude of 3mm, period of 10mm and the direction of the stripes normal to the flow direction of particles.

Abstract:Molluscan shells lived in harmony with nature upon the combination of multiple factors, e.g., surface morphologies, multilevel structures and component materials, and achieved an optimum adaptation to the surroundings based on such biological coupling functions. The Polyplacophora usually has complex surface topography and specific living behaviors which showed exceptional anti erosion property. Thus, the chiton Acanthochiton rubrolineatus was selected to study its bionic anti erosion mechanism. According to biological coupling and bionic anti erosion property of chiton, the explicit dynamic software ANSYS/LS-DYNA was used to simulate the erosive process of uni bionic model of configuration and configuration groove/convex morphology dual bionic coupled model imitating the shell surface of chiton. The mechanism of erosion of each model was comparatively analyzed. The overall erosion resistance of the three models was sorted as convex curved plate, groove curved plate and smooth curved plate. However, in the peak of the curved plate, the stress dispersion effect of groove was much better than that of convex, whereas the stress dispersion effect of convex was better than that of groove at the pterion region. The simulation results indicated that the shell plate of chiton evolved an optimum combination of morphologies with thick riblets distributed in the peak (grooves were formed between the riblets) and convexes scattered around the pterion region, and thus the chition was endowed with exceptional anti erosion property. The current research result could be further used in the series of agricultural irrigation machinery, such as water pump, turbine pump, spray irrigation equipment and drip irrigation system.