Abstract:Intelligent control is the key technology for the intelligentization of agricultural equipment. From the aspects of intelligent perception, intelligent control, intelligent decision-making, autonomous operation, and intelligent control of agricultural equipment, this paper analyzes the development status and trends of intelligent agricultural machinery at home and abroad. The latest technological advances in agricultural machinery intelligent control by agricultural machinery enterprises, as well as the gap between China’s intelligent agricultural machinery and foreign countries, the key issues restricting the development of agricultural machinery intelligent control in China. In order to realize China’s transformation from a big country in agricultural machinery manufacturing to a strong country in agricultural machinery manufacturing, integrating cutting-edge technologies in information fields such as big data, cloud computing, the Internet of Things, artificial intelligence, etc. New ideas for the development of intelligent agricultural machinery systems, namely, intelligent field control, intelligent cloud decision-making, and mobile terminal monitoring and dispatching.

Abstract:Aiming at the path planning in rice harvesting visual navigation, a method for extracting the boundary line of rice harvesting area was presented. Camera distortions were eliminated by camera calibration. According to the ultra-red characteristics model 2R-G-B, binary images were carried out based on integrated threshold method. Noise was eliminated by using the opening operation and closing operation in morphology. The ROI area was dynamically set according to the image grayscale vertical projection value. Crop line fitting key points were obtained by horizontal scanning. The boundary line of rice to be harvested was extracted by multi-segment cubic B-spline curve fitting method. Laboratory tests showed that the average error of distance information extracted based on the proposed image processing method was 9.9mm, the deviation rate was 2.0%, the average error of angle information was 0.77°, and the error rate was 2.7%. The field experiment of harvesting path extraction was carried out for two crops, Zhongjing 798 and Lindao 20 under four different light environments，direct sunlight, backlight, strong light and weak light，respectively. For the harvest image of Zhongjing 798, the average pixel error of crop line key point recognition was 28.7 pixel, the average distance error was 39.7mm, and the average relative error was 2.7%. The minimum average pixel error was 26.2 pixel in strong light, the minimum average distance error was 23.9mm in weak light, the minimum average relative error was 2.0% in strong light, in direct sunlight the algorithm was most stable with a standard deviation of 6.8 pixel. For the harvested image of Lindao 20, the average pixel error of crop line key point recognition was 36.5 pixel, the average distance error was 45.0mm, and the average relative error was 2.8%. All minimum value of each indicator was in backlight, the minimum average pixel error was 29.5 pixel, the minimum average distance error was 36.9mm, the minimum average relative error was 2.3% and the minimum standard deviation was 10.8 pixel. The average processing time of single frame image was 38ms, which can provide reference for crop line detection and automated navigation in harvesting.

Abstract:In the process of three-dimensional (3D) path planning for robots, the efficiency of path planning is greatly affected by the algorithm itself. For the purpose of the shortest distance, a robot 3D path planning method was proposed based on ant colony parameter transfer algorithm. Ant colony algorithm was used to find the shortest path in the robot environment model which was established by grid method. For the parameter selection problem of the ant colony algorithm, the parameter transfer algorithm was used to obtain the optimal parameters. The known environment model and its corresponding ant colony optimal parameters were used as source tasks, and the source tasks were mapped to high-dimensional spaces. Connecting different source tasks through transfer parameters, the parameter transfer graph was established based on the knowledge of graph theory. The parameter transfer map was extended to include the target task, and a set of ant colony optimal parameters was assigned to the random unknown environment model. Simulation results showed that the ant colony algorithm based on parameter transfer can complete the robot 3D path planning quickly and effectively. Compared with the traditional parameter selection method and other intelligent optimization methods, the ant colony parameter transfer algorithm can greatly reduce the time required for path planning and improve the path planning performance.

Abstract:In order to solve the problem of missing seeding caused by small impurities or damaged seeds blocking suction holes under the action of adsorption force in the process of filling, clearing and carrying seeds, the unloading mechanism was optimized. The installation position of seed unloading mechanism was improved to ensure that the seed metering device could adsorb seeds well in the seed-carrying area, prevent flying seeds, and reduce collision and bounce. The probability of seed falling off at the end of the air chamber in the seed-carrying area was reduced by 1.67% compared with that before the improvement. A gear tooth surface curve suitable for the coordination between the unloading wheel and the seed plate was deduced. By means of ADAMS simulation, three indexes of meshing force, radial force and axial force were extracted, and the rationality of the unloading gear tooth design was verified by simulation. The curve equation can be used to design unloading wheels with different kinds of plate and suction holes, which made the meshing stable and reliable and had good versatility. A comprehensive test was carried out with the unloading mechanism, forward speed and wind pressure as factors. By analyzing the significant difference between unloading mechanism and wind pressure at different speeds and the overall variance of the experiment, the key factors affecting the qualified index, multiple index and missing index were determined. The optimized new unloading mechanism was selected for regression analysis, through regression equation, the optimum operating parameters of the designed metering device at operating speeds of 10km/h, 12km/h and 14km/h were obtained, and the experimental verification was carried out. The results showed that the new unloading mechanism can effectively improve the qualified index and reduce the missing index of high-speed operation. When the operating speed was 10~14km/h and the wind pressure was -3.81~-3.43kPa, the qualified index can reach more than 96.8%, the missing index was not more than 2.0%, and the multiple index was not more than 1.2%. All the indexes were better than the requirements of national standards and can achieve effective seeding.

Abstract:Facing the problem of existing maize precision planting control system cannot quickly drive the seed sowing of multiple types corn precision seed meters, an on-site seeding rate calibration system was designed based on the controller area network (CAN) bus motor-driving corn planting technology. From the corresponding relationship between the motor control signal and the rotate speed of seed plate, the system got the seed meter driving curve in the filed using piecewise linear interpolation to realize the seeding rate control. Taking a domestic corn air-suction seed meter and a corn finger pick-up seed meter as the test objects, the speed control performance of seed plate in simulative travel speed was respectively evaluated. In the experiment of rotate speed control performance of corn air-suction seed meter, the seed spacing was set to be 25cm and the travel speed was set to be 3~12km/h with increment of 3km/h, the greatest response time was 0.80s, the biggest steady-state error was 0.81r/min and the lowest accuracy of seed plate rotate speed control was 97.42%. In the experiment of rotate speed control performance of corn finer pick-up seed meter, the seed spacing was set to be 20cm, 25cm and 32cm and the travel speed was set to be 4~9km/h with increment of 1km/h, the results showed that the average response time of the whole rotate speed of seed meter was 1.09s with standard deviation of 0.26s;the average steady-state error of the whole experiments was 0.38r/min with standard deviation of 0.23r/min;the average accuracy of rotate speed control of the whole experiments was 98.30% with standard deviation of 1.01%. Compared the seed plate rotate speed control system with the sectional proportion integration differentiation (PID) method, the system supported seed plate rotate speed on-line calibration had a better adaptability, the average response time was decreased by 0.51s, the average steady-state error was increased by 0.16r/min and the average accuracy of rotate speed control was decreased by 0.63 percentage points. The planting uniformity experiment in field was performed, taking the finger pick-up seed meter as the material. In the experiment of planting uniformity in field, the seed spacing was set to be 20cm and the travel speed was 4~7km/h with increment of 1km/h, the results showed that the quality of feed index was greater or equal to 84.26%, and the coefficient of variation was less than or equal to 18.29%. The above results indicated that the system can precisely control the rotate speed of motor driving planting through the way of calibrating the planting rotate speed control curve of corn precision seed meter on site with high accuracy.

Abstract:Aiming at promoting the research of mechanical fertilization in potato micro-seed planting, and enhancing the development level of potato industry in China, a kind of fertilizing device corresponding to the former designed potato micro-seed planter was developed. The fertilizing device mainly consisted of a fertilizer box, four fertilizer feeders, eight fertilizer guiding tubes and eight fertilizing openers. Combining with kinematic analysis and discrete element simulation, the whole structure of fertilizer feeder was designed and key parameters were confirmed. The length of spiral blade at single-rotation was 120mm, the outer diameter and pitch of spiral blade was 56mm and 45mm, respectively. The whole structure of fertilizing opener was designed, and parameters of the key parts such as ditching discs and tension spring were determined by theoretic analysis. For ditching discs, the diameter was 350mm, the angle between ditching discs at the place of cluster point was 60°, and the angle between ditching discs was 10°. As indicated in the static experiment of machine, the CV of uniformity of fertilizer discharge was 2.29%. Results showed that fertilizer feeders had good stability for fertilizer discharge. Furthermore, in order to test the performance of the whole fertilizing device, field experiment was conducted. Results showed that the mean horizontal and vertical spacing between fertilizer and potato seeds were 51.2mm and 63.5mm, respectively, which can be confirmed that the overall fertilization performance of the fertilizing device met the agronomic requirements.

Abstract:In the hilly and mountainous areas, it is unable to use large-scale foreign sowing machines, and the traditional mechanical miniature potato seeder has the problems of serious seed-injury and poor filling effect. In order to meet the conditions of small plot operation in hilly and mountainous areas and enhance the mechanization level of minituber, a precision single-row air-suction planter of minituber was designed. The planter consisted of seeding device, fan, ditching device, and soil and ridging device, which can complete ditching, sowing and soil covering work at one time. The working principle of the precision air-suction type planter of minituber was expounded, and the main structural parameters were determined. The "Lishu No.6" minituber was used as the research object, the single factor test and the quadratic regression rotation orthogonal test method were used to test the seeding performance of the planter, the vibration frequency, vibration amplitude, suction negative pressure and working speed were selected as experimental factors. The mathematical models of the qualified-seeding index, the miss-seeding index and the multiple-seeding index were established, the influence of the interaction of each test factor on the qualification rate was analyzed. The best combination of working parameters was obtained by four factors and five levels quadratic regression rotary orthogonal test. After optimizing the test parameters, when the suction negative pressure was 10kPa, the working speed was 2.5km/h, the qualified-seeding index was greater than 90%, the miss-seeding index was less than 5%, and the multiple-seeding index was less than 5%. After field test, the qualified-seeding index of the planter was 93.28%, the miss-seeding index was 3.25% and the multiple-seeding index was 3.47%. The air-suction planter had stable operation quality and met the requirements of national standards. The results showed that the air-suction planter could fully meet the agronomic requirements of minituber planting.

Abstract:In order to solve the problems that the integrity of the pot destroyed by the transplanting mechanism, the poor perpendicularity of planting caused by the asymmetry of the hole, and the poor quality of planting caused by the process of punching and planting, a kind of potted vegetable seedling transplanting mechanism with punching hole was put forward. The process of punching and planting could be alternately implemented by the mechanism. The punching process at the planting position of the previous potted seedling was completed by the puncher when a seedling was planted by the transplanting arm, which ensured the planting sequence. The holes formed by the puncher were symmetrical, the soil reflux was even and conducive to ensure the perpendicularity of planting. The protruding seedling picking device was used in the seedling picking process to protect the integrity of the potted seedling matrix. Based on the kinematic mechanism analysis of potted vegetable seedling transplanting mechanism with punching hole, the optimization design software was developed and the parameter optimization design was completed. The virtual simulation experiment and a series of bench tests of transplanting mechanism were carried out. The attitude of key positions such as seedling picking, punching and planting was analyzed. Trajectory and attitude verification experiments showed that the specific trajectory and attitude formed by the mechanism could complete the process of seedling picking, transporting, punching and planting in turn. The seedling picking experiment showed that the process seedling picking was realized and the integrity of potted vegetable seedlings matrix was effectively ensured.

Abstract:Aiming to prevent the backfilling of soil in front of the machine due to the reverse-rotary during straw deep buried into field. The rice straw full quantity deep buried and returned machine was designed, combined with the operation process of rice straw deep buried into the field. By analyzing the process of reverse-rotary operation, the reason of soil backfilling in front of the machine was explored and the mathematical model of relative position between soil and cutting tool in each stage of machine work were established and the mathematical model was established by Matlab, the angle of bending line was defined as 55°, the rotation speed of the cutter roller was defined as 190r/min, the bending angle was defined as 77° and the width of the cutting tool was defined as 80mm. At the same time, the arrangement of the cutting tool was designed. The completed machine configuration field tests showed that the machine could complete the operation under different operating environments with stubble height less than 260mm and operating speed less than 3km/h, the problem of soil backfilling in front of the machine was solved and the returning rate could be reached more than 85%, soil fragmentation rate and ground flatness could be reached more than 95%. All the indexes could meet the technical requirements and the adaptability test was carried out under the relatively wet and sticky working environment. All the indexes were higher than the agricultural requirements, which proved the applicability of the machine and tools.

Abstract:Aiming at the problem of seeding omission of sugarcane transverse planter in the process of planting, a kind of replanting device with hierarchical transmission was designed. Through the kinematics and dynamics simulation analysis of filling, storing, supplying, protecting and throwing process, the main factors affecting the effect of replanting were determined, and the key components of replanting system were designed. A sugarcane real-time replenishment system based on 51 single chip computer was developed. The AT89C52 chip and three pairs of laser sensors were used to collect signals of sugarcane seed leakage, replenishment box and sugarcane storage tank for insufficient sugarcane seed reserve. The signal was counted and displayed. The alarm circuit realized the alarm of insufficient sugarcane seed reserve, and the stepper motor was used for the alarm. For power source, the driving roll rake rotated to complete the seed replenishment process. The bench test showed that by choosing two factors, i.e. the traveling speed and the number of grooves, and taking the success rate and the replacement rate as the performance index, the orthogonal rotation test of two factors and five levels was carried out. It was concluded that the traveling speed had a very significant influence on the success rate of replanting, followed by the number of grooves. The quadratic regression equation analysis with Excel showed that the success rate of replanting was 93.97% and the replacement rate was 1.69% when the traveling speed was 3km/h and the number of grooves was 10. The performance of the real-time seeding replenishment system was stable and reliable, which solved the problem of seeding leakage in the process of seeder operation.

Abstract:Aiming at the serious mechanical damage of potato tuber during the lifting process of potato excavator, through the kinematic analysis of potato lifting process and the energy analysis method of potato and bar collision process, through the establishment of the mathematical model of damage energy in the process of lifting and separating, the main factors influencing the mechanical damage of potato during the lifting process are the drop height, lifting chain speed and the angle of the lifting chain. At the same time, the range of test values of main factors is determined. Taking the damage comprehensive index and the injury rate of potato as the evaluation index, taking the drop height, the inclination angle of the secondary lifting chain and the linear speed of the secondary lifting chain as the experimental factors, the quadratic orthogonal rotation regression test was carried out. The regression mathematical model between each index and factor was established, and the influence rule of each factor on the evaluation index was analyzed. AccorIng to the regression model, the parameters were optimized. When the linear speed of the lifting chain is 1.42m/s, the Ip angle is 27° and the drop height is 220mm, the damage comprehensive index is 0.43, and the injury rate is 3.6%, which is significantly lower than the mechanical damage of potato block of potato excavator without parameter optimization, and meets the requirements of potato harvesting.

Abstract:In view of the industrial aquaculture, it is necessary to classify the fry in different growth stages according to their sizes with high efficiency and accuracy, so as to meet the requirement of separate cultivation, a roller-type fry sorting test prototype was designed. The coupling model of fry-mechanical components was established by using discrete element software. As the working parameters of the sorting machine were used for the experimental factors, and the sorting efficiency and accuracy of fish-dividing were used for evaluation indexes, the simulation results were obtained and verified by experiments. Finally, the single factor and orthogonal influence simulation analysis was carried out based on the established coupled simulation model, and the primary and secondary order for each working parameter and the optimal parameter combination were determined. The results showed that the primary and secondary order of the influence factor for the sorting accuracy was: roller lifting angle, fish intake and roller speed, and the primary and secondary order of the sorting efficiency was: roller lifting angle, fish intake and roller speed. Based on the principle of improving the sorting accuracy and efficiency, the parameters were optimized by Design-Expert 8.0.5 software, and the optimal combination was determined as follows: the roller speed was 138.40r/min, the roller lifting angle was 10.47°, and the fish intake was 3.00 tails/s. The research results would provide an important reference for the optimization design of the following fry grading equipment.

Abstract:In order to investigate the influence of cavitation on pressure pulsation in ultralow specific speed centrifugal pump, combining experimental and numerical simulation methods, the frequency domain and amplitude characteristics of pressure fluctuation were analyzed at different positions in an IB 50-32-250 ultralow specific speed centrifugal pump with different net position suction head available (NPSHa). The results showed that cavitation can induce low frequency and broadband frequency fluctuation. When there was no cavitation, the pressure pulsation in impeller flow passage was mainly related to the impeller rotation frequency and its harmonic frequency;while in the volute, because of the interference between impeller and volute tongue, the main dominant frequency of pressure pulsation was the blade pass frequency and its harmonic frequency, and the pressure pulsation near tongue was the strongest. With the decrease of NPSHa, pressure fluctuation of most monitors in the impeller passage was weakened, but that in the edge of cavitation zone was enhanced. The main frequency of pressure pulsation near the impeller inlet was changed from rotation frequency to 1/6 rotation frequency at the critical cavitation. Besides, the developing ununiformity of flow field in volute caused the amplitude of pressure fluctuation strengthened. The main frequency of the volute and pump outlet was still blade pass frequency, but 1/6 rotation frequency became the secondary frequency with larger amplitude. The research can provide necessary basis for the reduction of vibration and noise intensified by cavitation in the ultralow specific speed centrifugal pump.

Abstract:Aiming to study the cavitation characteristics under different cavitation numbers based on the pump-turbine of a pumpedstorage power station, the SST k-ω turbulence model and the Zwart cavitation model were used to calculate the full flow path under different cavitation numbers. The unsteady numerical calculations were carried out and compared with the experimental results. The turbulent kinetic energy distribution of the intermediate flow surface and the distribution of cavitation on the blades under different cavitation numbers were analyzed. The correlation between cavitation distribution area and the runner inner channel vortices were discussed. The results showed that when the pump-turbine was operated under pump conditions, its vaneless had obvious turbulent kinetic energy, and the turbulent energy distribution was obvious, showing an irregular ring shape distributed. The bubble distribution of the blade was mainly on the suction surface of the blade, and the turbulent energy of the suction surface of the blade was higher than that of the pressure surface. The vortex inside the runner was mainly generated near the exit of the runner, and close to the suction surface of the blade. The size and number of vortices had a certain relationship with the distribution of bubble on the blades. The generation of bubble led to the poor flow path and exacerbated the generation of vortices. 

Abstract:Drought was an important factor restricting agricultural production and economic development. It was of great significance for promoting economic development and ensuring food security to study the law of occurrence and development of drought and effectively predict the local future drought situation. The purpose was to verify the applicability of vegetation temperature condition index (VTCI) in the drought prediction during summer maize growing season. Taking the central plain of Hebei as the research area and the time series of drought monitoring results of vegetation temperature condition index as the data source, and autoregressive integrated moving average (ARIMA) model and seasonal autoregressive integrated moving average (SARIMA) model were used to forecast agricultural drought. First of all, based on the time series of vegetation temperature condition index of 49 meteorological stations, the VTCI data of different lengths were used to build ARIMA prediction models, and the variation characteristics of ARIMA model prediction accuracy with the increase of VTCI time series length were analyzed. The results showed that there existed no clear dependence between the performance of the model and the training lengths corresponding to the historical datasets of VTCI, but the prediction accuracy of the model tended to be stable with the increase of time series length. Then, the VTCI time series data from early July 2010 to late August 2017 was used as modeling data, the ARIMA model and SARIMA model were applied to predict VTCI in September 2017, and the prediction accuracy of the two models was evaluated. The results showed that the prediction accuracy of the ARIMA model was higher than that of the SARIMA model. The root mean square error of the 1-step VTCI prediction of the ARIMA model was 0.06 lower than that of the SARIMA model, and the 2-step prediction was 0.07 lower, and the 3-step prediction was 0.09 lower. Therefore, the ARIMA model was more suitable for the drought prediction during the summer maize growing season in the study area. Finally, the ARIMA model with better performance was modeled pixel by pixel to obtain the VTCI prediction results from early September to late September, 2016—2018. The results showed that the ARIMA model had a good prediction accuracy for 1-step, 2-step and 3-step of VTCI during summer maize growth season in different years. The average percentage of pixels with absolute error larger than 0.20 in 1-step, 2-step and 3-step in 2016—2018 was only 5.84%, 6.38% and 8.72%, respectively.

Abstract:The remote sensing of unmanned aerial vehicle (UAV) is accurate, flexible and fast. It is of great significance for large-scale agricultural management and water efficiency evaluation to establish yield estimation model of summer maize based on drone remote sensing. It was reported such an effort for summer maize in Inner Mongolia by using UAV multi-spectral platform. Six kinds of linear models for the measured summer maize yield maize as function of various vegetation indices derived at various growth stages were constructed by using Newton-trapezoidal integral and least squares method. And the threshold filtering method was used to reduce the influence of soil noise on the accuracy of the model. The results showed that there were significant differences in the accuracy of the models at different growth stages. In single growth period, the model precision from high to low was ordered as tasseling silking, wax maturity, and jointing, and the optimal vegetation index was EVI2 (R2=0.72,RMSE was 485.46kg/hm2).For most growth periods the superior vegetation index was GNDVI (R2=0.89,RMSE was 299.35kg/hm2). After soil filtration, the increase of R2 in jointing stage and multiple growth stages was significant. The correlation coefficient R2 was increased to above 0.87 for the multifertility estimation model based on vegetation indices GNDVI, MASVI2 and EVI2. In summary, the UAV yield estimation model can quickly and effectively diagnose and assess crop growth and yield. The estimation accuracy of the model in multiple growth periods was better than that in a single one, and GNDVI was the optimal model parameter. The threshold filtering method can effectively improve the estimation accuracy.

Abstract:Aiming to explore the effect of fractional-order derivatives (FOD) combined with support vector machine discriminant analysis-random forest model (SVMDA-RF) on hyperspectral monitoring of desert soil organic matter content (SOM). The desert soil samples collected in the Sde Boker area of Israel were analyzed. These soil samples were through pretreatment, physical and chemical analysis, soil classification (divided into sandy soil (SS) and clay loam soil (CLS)), indoor spectral acquisition and spectral resampling (interval 10nm). In order to avoid the influence of soil quality on the inversion model, the support vector machines discriminant analysis (SVMAD) was established based on the average reflectance of the spectrum. The spectral reflectance was processed by 0~2 order (interval 0.2) FOD. Then NDI was constructed by using the spectral data that through fractional order derivatives processing and the twodimensional correlation between SOM and NDI was analyzed. In order to obtain all different FOD enhancedNDI, the highest coefficient of determination (R2) of 0-order NDI was used as the threshold (sand soil R2>0.901, clay loam soil R2>0.763). By using the different FOD enhanced-NDI to establish random forest (RF) models. All models based on different soils were compared and analyzed, the best models of different soils were combined to establish the SVMDA-RF model. The results showed that SVMDA based on spectral average reflectance, the classification rate of soil texture could reach 100%. Fractional order derivatives coupling normalized spectral index, which had ability to amplify SOMrelated implicit information between bands, but it had different effects on different soils. For the paper, clay loam soil was superior to sandy soil, and two soils of the FOD-enhanced sensitive index peaked at 0.6-order, but the number of sensitive index of clay loam soil was much larger than that of sandy soil. In the sandy soil RF models, the model based on 1.2-order NDI was the best（R2C=0.962，R2P=0.920，RMSEP was 0.435g/kg，and RPD was 3.658）. In the loam RF models, the model based on 0.6-order NDI was the best（R2C=0.942，R2P=0.944，RMSEP was 0.554g/kg，and RPD was 4.316）. Combining the optimal models of the two soils to get the high-precision SVMDA-RF model, R2P=0.979，RMSEP was 0.481g/kg，and RPD was 7.004. The model could provide effective support for quickly assessing the desert soil types and fertility.

Abstract:Shandong Province is a large agricultural province in China. In recent years, agricultural greenhouses have developed rapidly. The promotion of greenhouse technology played an important role in increasing agricultural production and efficiency in Shandong Province. Therefore, it is necessary to monitor the dynamic changes of agricultural greenhouses in Shandong Province. However, accurately obtaining the distribution of agricultural greenhouses in a large-scale space and performing dynamic monitoring of longterm sequences are difficult, such as large data volume, low computational efficiency, and low precision. In response to the above problems, the Google Earth Engine (GEE) cloud platform was used to access and process massive satellite data. Based on multi-temporal Landsat images, time series spectral features and texture features were extracted. Random forests were used to complete the classification of agricultural greenhouses in Shandong Province. Finally, the thematic map of spatial distribution and spatialtemporal dynamic changes of agricultural greenhouses in Shandong Province in recent 30 years were generated. The experimental results showed that the classification process proposed had better classification accuracy with the average classification accuracy of 91.63% and the Kappa coefficient of 0.8642. After analysis, the area of agricultural greenhouse in Shandong Province was increased from 6.67km2 in 1990 to 9919.40km2 in 2018, with a growth rate of 354.03km2 per year. By studying the dynamic changes of agricultural greenhouses in Shandong Province in recent 30 years, it can not only provide better planning suggestions for further development, but also provide reference for the development of agricultural greenhouses in other provinces in China.

Abstract:The UHD185 imaging spectrometer and ASD spectroradiometer were used to acquire imaging and nonimaging hyperspectral data during three wheat growth stages, including flagging stage, flowering stage and filling stage. The corresponding ground leaf area index (LAI) data were also collected. Firstly, the ASD and the UHD185 spectrometer data were compared and their precision was evaluated. Then, the correlation analyses were conducted between LAI and seven LAI related spectral parameters, linear regression and exponential regression were used to select the optimal estimation parameters. Finally, for each growth stage, multivariate linear regression, partial least squares, random forest, artificial neural network and support vector machine were used to construct LAI estimation models for winter wheat. The experimental results showed that UHD185 hyperspectral spectrometer reflectance was highly consistent with ASD ground hyperspectral spectrometer reflectance in the rededge region. The coefficients of determination between them were 0.9959, 0.9990 and 0.9968 for flagging stage, flowering stage and filling stages, respectively. The parameters with the highest correlation with LAI were NDVI (r=0.738) for flagging stage, SR (r=0.819) for flowering stage, and NDVI×SR (r=0.835) for filling stage. LAI-MLR was the best estimation model for winter wheat. The highest accuracy for flowering stage with R2 of 0.6788, RMSE of 0.69 and NRMSE of 19.79% for calibration, and with R2 of 0.8462, RMSE of 0.47 and NRMSE of 16.04% for validation.

Abstract:China is a big country in the production of duck eggs and ducks. The duck egg hatching industry has a huge output. It needs to incubate billions of ducklings every year to meet the production needs. At present, the method of removing the infertile eggs in the duck egg hatching industry in China is to visually recognize the eggs by artificially photographing the eggs about 7 days after hatching. This method is inefficient and has no edible value after 7 days of incubation, which will cause huge waste of resources. Machine vision technology was used to hatch the third day of the duck eggs. The end-to-end characteristics of the deep convolutional neural network was used to the image of the duck egg on the third day of incubation, and it was directly input into the neural network, and the Alexnet neural network. The convolutional layer was used to replace the fully connected layer, and the size of the convolution kernel was changed. An egg net fertilization information recognition network (Eggnet) model was established to realize the nondestructive discrimination of the fertilization information in the early hatching of the duck eggs. The test results showed that the accuracy rate of the method for the classification of the duck eggs in the third day of hatching was as high as 98.87%, the accuracy of the verification set was 97.97%, and the average single egg detection time was only 0.24s. This technology can be used in the actual production of duck egg hatching industry in the later stage. It would replace the artificial egg method to select the infertile egg. It can solve the problem of automatic device installation in the egg hatching industry. It had broad application space.

Abstract:In order to detect plant leaf element deficiency, a visual detection method of soybean leaf element deficiency based on neural network was proposed. After analyzing the characteristics of soybean deficient leaves, deep learning technology was used. The Mask R-CNN model was used to segment the leaf images collected by a fixed camera, and the VGG16 model was adopted to classify the deficient leaves. Firstly, after collecting hydroponic soybean images, the outline of soybean leaves was marked manually in the images, establishing training set and test set of segmentation task. Through pre-training, the initial parameters of the Mask R-CNN model were determined, and then using lower learning rate to train the model. For segmentation task on single leaf images and on multiple leaves on a complex background in the test set, the Matthews correlation coefficient (MCC) of the final trained model reached 0.847 and 0.788 respectively. The training set and test set of the soybean leaf image classification task were established by segmenting the leaves through the trained Mask R-CNN network and manually marking them. The initial parameters of the VGG16 model were determined through pre-training, and then the whole connection layers of the VGG16 model were replaced before training to adapt to the leaf classification task. The classification accuracy of the final trained model on the test set was 89.42%. When analyzing the result, the leaves with obvious deficiency features were classified into two types of nitrogen deficiency and four types of phosphorus deficiency to discuss the inadequacy of the method. The average running time of the algorithm to detect a picture of 1 million pixels was 0.8s. The algorithm had a good detection result on the classification of soybean leaf deficiency under complex background, which can provide technical support for the estimation of plant deficiency in agricultural automation production.

Abstract:Regional landscape ecological quality assessment and research of its spatial and temporal differentiation would help to locate regional ecological function, optimize resource allocation and maintain regional sustainable development. The evaluation index system of landscape ecological quality was constructed on the basis of landscape quality and ecological quality, which covered eight comprehensive indexes. Based on GIS and GeoDa platform, the weight of indexes were determined by using the mixed model of AHP and mean variance decision method, the spatiotemporal evolution characteristics of the landscape ecological quality were studied in the village of Chaohu Basin during 2005—2010 in the context of rapid urbanization from the aspects of gradation and index difference, the spatial autocorrelation method was used to analyze the spatial differentiation and aggregation characteristics and the corresponding ecological planning suggestions were put forward. The results showed that the landscape ecological quality in the Chaohu Basin was mainly stable in 2005—2010, but its local degradation was 28.61% and 29.90% respectively higher than that of improvement in ratio of villages’ number and area, in which the western part of the study area was improved and the north, east and south parts were degraded. From the index difference of landscape ecological quality, the degraded area of landscape ecological quality in 2010 accounted for 7865% of the study area compared with 2005, and distributed densely in the north, northeast, east and south of the study area and sporadically in the west. The spatial agglomeration of landscape ecological quality, which was stronger in 2005, was decreased with time from 2005 to 2010. According to the characteristic zoning of high-high, low-low, high-low and low-high zones in the two phases, some related planning suggestions were put forward in the aspects of ecological land protection, industrial layout optimization, land use and low efficiency industrial land control, green infrastructure and ecological corridor. The research results can provide a scientific reference for the regional ecological landscape planning, ecological management and protection, and the sustainable development of landscape ecosystem.

Abstract:The concentration of ammonia nitrogen is one of the key indexes in the process of marine aquaculture. Excessive levels of ammonia nitrogen in the water produce strong neurotoxins, leading to large-scale death of aquatic organisms. Therefore, it is very important to monitor the concentration of ammonia nitrogen in water in real time and accurately. Due to many factors affecting seawater quality, and the complex factors often affect each other, there is no instrument to realize the real-time detection of seawater ammonia nitrogen concentration at present. Firstly, the current research status of ammonia nitrogen monitoring in water of aquaculture was reviewed. Then, the formation and nitrification process of ammonia nitrogen in marine aquaculture water was analyzed，and the parameters (temperature, conductivity, pH value and dissolved oxygen concentration) related to ammonia nitrogen concentration were selected as auxiliary variables. A soft measurement model of ammonia nitrogen concentration was established by using a stochastic configuration networks with high convergence speed and strong generalization ability. In order to verify the effectiveness, the proposed method was compared with other neural network modeling methods by using the measured data of the turbot intensive marine aquaculture system independently established by the laboratory. The results showed that the proposed method had higher generalization ability, higher prediction accuracy and faster running speed. Finally, the aquaculture water quality monitoring system was developed, and this method was embedded in the upper computer WinCC software to realize online monitoring of ammonia nitrogen concentration.

Abstract:Accurate identification of orchard trunks can provide effective information for orchard robot localisation and navigation. The traditional tree trunk segmentation algorithm has low segmentation accuracy and poor real time performance. To solve this problem, a fast segmentation of tree trunks based on depth and texture features was proposed to improve segmentation accuracy and real time performance. Firstly, a Realsense depth camera was used to capture color and depth images of tree trunks. Then, a superpixel segmentation algorithm was proposed to segment color images, and fuse adjacent superpixel blocks with similar depth and texture values. Finally, plant trunks were distinguished from notrunk targets in candidate superpixel blocks based on trunk width threshold setting in depth images and hue value matching in color images. Both indoor and outdoor experiments were conducted to compare the proposed tree trunk segmentation algorithm with traditional GrabCut algorithm and K-means algorithm. The average recall rate and average accuracy of the new algorithm were 87.6% and 95.0%, respectively, while that of the GrabCut algorithm was only 78.0% and 92.8%, respectively, and the K-means algorithm was 80.2% and 89.1%, respectively. Meanwhile, the average time of the proposed algorithm was 0.20s, while the GrabCut algorithm was 0.66s, and the K-means algorithm was 4.42s. The experimental results showed that the proposed algorithm was effective in fast segmentation, and can be applied to tree trunk segmentation.

Abstract:Canopy gap characteristics and spatial distribution play an important role in forest structure optimization and function restoration. Based on airborne laser scanning data and field evidence across sites, descriptive statistics were used to identify and examine gap characteristics. Ripley’s K function analysis was applied to test gap spatial patterns at a range of scales, and spatial point pattern analysis was used to quantify the relative importance of specific influences on patterns of gap occurrence. The results revealed that the average gap size was 78.9m2 and that 12.8 gaps occurred per hectare. In addition to more gaps, the mean gap size was smaller and the shape was more complex in the secondary forest site than in two managed sites. Large differences in gap characteristics were observed among natural disturbances and artificial gap. Gaps generally showed a clustered distribution at large scales, whereas spatial patterns varied with gap damage types at different sites. The occurrence of gaps was strongly related to slope and topographic position at the secondary forest site, whereas slope, stem density, and human accessibility (proximity to pathways) were the most important factors affecting gap occurrence at the managed sites. The purpose was to clarify the mechanism of forest gap disturbance and provide methodological reference and technical support for forest management to adapt to climate change. 

Abstract:Sensitivity analysis plays an essential role in the processes of crop model localization. It is important to quantify the sensitivity of input parameters of model for crop model calibration and application. In order to quantify the effects of input parameters variation on the sensitivity of CROPGRO-Tomato output variables, the extended Fourier amplitude sensitivity test method was applied to perform global sensitivity analysis. The most sensitive parameters for anthesis, fruit set and maturity date were the photothermal days in the early flowering period (EMFL) among the cultivar parameters, and the average minimum air temperature among climate parameters, while the phenology of tomato was not affected by soil parameters in the model. Among the cultivar parameters, the most sensitive parameters for leaf area index and canopy height was EMFL, while the most sensitive parameters for growth of root and stem was the maximum fraction of daily growth. The growth of root, stem and leaf was affected sensitively by the average maximum air temperature (TMXD) and the soil field capacity (SDUL) among climate and soil parameters, respectively. The most sensitivity parameters for the tops weight at maturity and fresh fruit weight was EMFL, while the most sensitivity parameter for number of fruits at maturity and single fruit weight was maximum weight per seed among cultivar parameters. TMXD and SDUL were also the most sensitivity parameters for tomato production among climate and soil parameters. The research result indicated that EFAST method was a feasible way for CROPGRO-Tomato model calibration and application.

Abstract:In order to find out the response mechanism of wheat/maize intercropping population under different water stresses, three intercropping treatments with sufficient water stress levels and two sufficient irrigation singles were used for the control treatment. The results showed that the water capture equivalent ratio of wheat strips was higher than that of corn strips in the intercropping period. With the increase of water stress, the trend became more and more obvious. With the growth of the growth period, the trend became weaker and even appeared reverse, while the relative competitiveness of water between the belts showed a gradual decline. In terms of root distribution characteristics, the average root distribution depth of the intercropped population under full irrigation was 17.15~17.24cm, and the root mass density was 90.42%~90.77% distributed in the plough layer, of which 87.49%~88.70% was wheat and 92.63%~92.81% was corn, and water stress can significantly affect the spatial distribution of intercropping population roots. In terms of intercropping advantages, it was necessary to have the intercropping advantage to satisfy the field water holding rate of at least 80% per water. With the increase of water stress degree, the land equivalent ratio of the intercropping group showed a slight increase and then declined, and the intercropping of corn was partial land. The rate of decline in equivalence ratio was faster than that of intercropped wheat. In terms of relative competition ability between species, it showed that with the increase of water stress, the wheat was decreased rapidly and gradually disappeared after it was slightly increased. In short, the particularity of the intercropping group caused the difference in soil moisture between the two crops in time and space, which in turn caused the difference in irrigation water infiltration rate and total infiltration, and water stress increased this trend, which was certain to the extent that the optimal location of irrigation water was satisfied, the water use efficiency of the intercropping group was improved, and the mechanism of water saving and yield increase of the intercropping group was revealed.

Abstract:In order to explore the model of critical nitrogen dilution curve of maize under the integrated mode of drip irrigation and water fertilization, local maize main variety “Tianci 19” of Ningxia Hui Autonomous Region was used as the experimental material, and six nitrogen levels (0kg/hm2, 90kg/hm2, 180kg/hm2, 270kg/hm2, 360kg/hm2 and 450kg/hm2) were set, the dynamic changes of aboveground biomass and nitrogen accumulation in drip irrigation maize were studied, a critical nitrogen dilution curve model of maize was constructed, and a nitrogen absorption model and nitrogen accumulation deficit model were built on this basis to achieve rapid diagnosis of nitrogen nutrition status of drip irrigation maize. The results showed that the dry matter quality and nitrogen uptake of the aboveground drip irrigation were affected by the nitrogen application level, and it was increased with the progress of the growth process. The excessive or too low nitrogen accumulation was not conducive to the formation of yield, and the nitrogen of maize plants, the luxury consumption phenomenon existed. The critical nitrogen concentration, the highest and the lowest nitrogen concentrations of the drip irrigation maize can be expressed by the power function equation, and the average coefficient of determination R2 was 0.976, 0.903 and 0.941, respectively, which reached extremely significant level. The nitrogen uptake model and the nitrogen accumulation deficit model based on the critical nitrogen concentration were consistent with the results of nitrogen nutrition diagnosis during the growth period of drip irrigation maize, and the fitting curve of comprehensive nitrogen application rate and yield, recommending the nitrogen application rate of drip irrigation maize in Ningxia Yellow River Irrigation District as 270~311kg/hm2. The research result provided a theoretical reference for the precise fertilization and optimized nitrogen management of drip irrigation maize in Ningxia Yellow River Irrigation District.

Abstract:In order to research the migration mechanism of the surface ponding infiltration, the HYDRUS software was used to simulate and verify the process of surface ponding infiltration based on Darcy law and mass conservation principle. The relationship between the ratio of horizontal wetting front to vertical wetting front and soil hydraulic parameters (air-entry suction, shape coefficient and saturated water conductivity) was analyzed, and a horizontal wetting front migration model was established by using soil saturated diffusion rate. The results showed that the shape of wetting pattern of fine soil was approximately an ellipsoid with the center at ponding center, and the vertical and horizontal wetting fronts were the long and short semi-axes, respectively. However, the center of the coarse soil wetting pattern was located below the ponding center, thus the short semi-axis was larger than the horizontal wetting front, and the long semi-axis was smaller than the vertical wetting front. Wetting front ratios of fine soil was changed little with time and can be assumed as a constant. There was no significant functional relationship between wetting front ratio and shape coefficient or saturated water conductivity, but it was linearly increased with the increase of air-entry suction with R2=0.999. The power function of infiltration time can be used to describe the wetting front migration and the coefficient and index in power function can be estimated by the first and second polynomials of soil saturated diffusivity. It was verified that wetting front model had a good effect within the allowable error range. The research result can provide a more rational tool for the analyzing of surface ponding water migration. Meanwhile, it also provided a scientific theory for design of drip irrigation system in arid and semi-arid regions in northern China and improving the agricultural irrigation water use efficiency.

Abstract:The rational use of rainwater resources can not only reduce the source of soil erosion, but also provide effective water supply to the local area. The Loess Plateau has less precipitation, large evaporation, and very scarce surface water resources. Therefore, the use of rainwater resources has become an important means for the Loess Plateau to deal with soil erosion, drought and water shortage. The core issue of rainwater resource utilization is to scientifically evaluate the local rainwater resource potential and its spatial and temporal distribution. For this reason, the distributed hydrological simulation technology was introduced to construct a distributed rainwater harvesting potential assessment model. It was dedicated to solving the core problems of rainwater resource utilization and evaluate the potential of local rainwater resources. The following conclusions were drawn by studying the typical Helong Region of the Loess Plateau. Under the dual influences of climate change and human activities, the surface runoff, soil water increment and the rainwater harvesting potential in Helong Region showed an upward trend after 1980s. The rainwater resources of most sub-basins in the Helong Region had a growing trend, and the rainwater resources could basically meet the water consumption under the current vegetation coverage. Climate change had a positive impact on rainwater resources with the contribution rate of 63.4% and the land use/cover change had a negative impact with the contribution rate of -36.6%. Therefore, the human activities imposed great effect on rainwater utilization pattern, and to fully develop the rainfallrunoff regulation technologies and improve the rainwater using efficiency were the key countermeasures to realize the ecology-economy synergetic development in the Loess Plateau.

Abstract:In order to reveal the residual situation of fertilizer nitrogen in paddy soil under water and biochar management, the method of combining field plot experiment with micro-plot was used to label basal fertilizer, tillering fertilizer and panicle fertilizer respectively. Compared with traditional flooding irrigation, the residual situation of basal fertilizer, tillering fertilizer, panicle fertilizer and whole fertilizer in paddy soil after rice harvest and the distribution law of nitrogen residue in different depths soil layer of fertilizer applied at different stages under different water and biochar management modes were studied. The results showed that the total nitrogen residues in paddy soils under different biochar application levels was 28.16%~34.42% under dry-wet-shallow irrigation mode, and the nitrogen residues of basal fertilizer, tillering fertilizer and panicle fertilizer were 27.53%~41.35%, 34.32%~43.50% and 11.58%~25.67%, respectively. When the application amount of biochar was below 12.5t/hm2, the residual amount of basal fertilizer and tillering nitrogen in paddy soil was increased with the increase of biochar application amount under the two irrigation modes after harvest, while the residual amount of panicle fertilizer nitrogen in paddy soil was decreased with the increase of biochar application amount. Under the same application level of biochar, the residual rate of fertilizer nitrogen in soil was significantly higher than that in conventional flooding irrigation (P<0.05), the residual amount of fertilizer nitrogen in the same soil depth under the same biochar application level was significantly different between the two irrigation modes (P<0.05). The residual amount of nitrogen fertilizer applied at different stages under different biochar application levels in paddy field under dry-wet-shallow irrigation mode was higher than that under conventional flooding irrigation, while the residual amount in 40~60cm soil layer was lower than that under conventional flooding irrigation. And the application of biochar as 25t/hm2 had a negative effect on the residual nitrogen of basal fertilizer, tillering fertilizer and panicle fertilizer in paddy soil under dry-shallow-wet irrigation mode. Reasonable water and biochar management model can increase the residual amount of fertilizer nitrogen in plough soil (0~20cm), reduce the loss of fertilizer nitrogen, inhibit the movement of fertilizer nitrogen to deep soil, and reduce the risk of pollution of fertilizer nitrogen residue in soil to paddy ecological environment. The results can provide theoretical basis and technical support for the application of water and carbon management model in paddy field in cold and black soil region.

Abstract:Substrate cultivation is the development direction of greenhouse cultivation mode, and it is of great significance to study the modern precision irrigation method for substrate cultivation. Ondemand irrigation is one of the main methods of modern precision irrigation. It is inseparable from realtime monitoring and feedback of water content. The water content is an important parameter in modern precision irrigation methods. Moisture sensor based on the principle of frequency domain reflection (FDR) was used in a substrate environment for monitoring water content. The moisture detection module of JZH-0 sensor adopted the principle of FDR, which had good performance on the soil moisture testing. However, it needed to be calibrated before using in different kinds of substrate. In order to further optimize the closed cultivation irrigation method in solar greenhouse and improve the water and fertilizer utilization rate, based on the theoretical research of ondemand irrigation, the existing integrated irrigation system of water and fertilizer, air temperature sensor and soil moisture sensor were mainly used for irrigation and realtime data monitoring and collection. The study on the irrigation strategy of closed greenhouse cultivation of strawberry in greenhouse was carried out by collecting the moisture content of the substrate under the experience of irrigation and the temperature in the greenhouse. The variation of moisture content of substrate in different time scales was firstly summarized. The result showed that the substrate water content of each irrigation rose rapidly, reaching a peak at the end of each irrigation time, with an average increase of about 21.5 percentage points;the second stage decreased rapidly, with an average decrease of 3.5 percentage points in 20min;the third stage of the trendwas stabilized, with an average decrease of 1.2 percentage points in 30min. During each irrigation cycle, the water content of the substrate showed a linear downward trend, and the slope of the substrate could better reflect the daily variation of the matrix moisture. During the whole fruiting period of strawberry, the slope was increased with the increase of daily average temperature, which was increased from 0.0114 to 0.0365, reflecting the positive significance of temperature increase on crop water demand. Then, the daily variation of the moisture content of substrate was approximated to the daily water requirement of the crop to study the water requirement of the crop. Among the many factors affecting the water demand of crop, temperature with convenient measurement and high accuracy was chosen as the independent variables, because its influence effect was obvious and had strong coupling relationship with light intensity and relative humidity of air. The data was classified by K-means clustering algorithm. According to the classification results, an interval quantitative automatic irrigation strategy based on daily average temperature was proposed in closed greenhouse cultivation: three temperature intervals were set (13, 18]℃, (18, 22.5]℃, (22.5, 27)℃ and in turn corresponded to the daily variation of water content of three substrates as 0.88 percentage points, 1.76 percentage points and 2.63 percentage points, respectively;calculating the daily average temperature of the day, and selecting the appropriate daily variation of moisture content of substrate according to the temperature range to which it belonged and irrigated the next day;it was revised on Monday in a weekly cycle. Theoretically only 4.51L water was needed per strawberry plant in fruit stage, which can save 15.4% water. Under this strategy theoretically based on K-means clustering algorithm, the water and fertilizer utilization were effectively improved, and the closed greenhouse irrigation methods in solar greenhouses were further enhanced. 

Abstract:The ever-increasing worldwide production of peanuts has led to a large accumulation of shells. The usage of these residues has been limited due to their high lignin content. Vermicomposting was used to stabilize the peanut shells (PS). Chopped PS was mixed with cow dung at a ratio of 60:40 (on a dry weight basis). Eisenia fetida was selected. The experiment was classified into two treatments: the control, which contained 1000g of the mixed substrates without earthworms, and the treatment with earthworms, which contained the mixed substrates and 120 individuals of Eisenia fetida. The duration of the experiment was 48 days. The C/N ratio of the initial substrate was approximately 37.00. The C/N ratio in the treatment with earthworms was less than 15.00 on day 48, whereas it was 23.17 in the control. This suggested that earthworms stimulated the decomposition of shells. The mortality rate of Eisenia fetida was 19% by the end of the experiment. Cocoons and juvenile earthworms were observed during vermicomposting, indicating that the earthworms adapted to the high lignin content of the shells. The Shannon-Wiener index of fungi in the initial mixed material was 1.33. By the end of the vermicomposting, the values were 2.59 and 1.66 in the treatment with earthworms and in the control, respectively. This indicated that the diversity of fungi was promoted by the presence of earthworms. A significant increase in the abundance of Rhodococcus, Arthrobacter, unclassified_f_Peptostreptococcaceae, Sporosarcina, Cercophora, unclassified_c_Dothideomycetes, Preussia and unclassified_f_Lasiosphaeriaceae in the treatment with earthworms was observed.

Abstract:The effect of ultrasonic-assisted heats treatment on Escherichia coli and functional properties in egg white liquid was investigated. The inactivation kinetic of Escherichia coli was analyzed by fitting with Weibull model. The result showed that the reduction in Escherichia coli was enhanced with an increase in ultrasonic power, temperature or time. The reduction in Escherichia coli was enhanced from 0.67lg CFU/mL to 1.24lg CFU/mL with the increase of ultrasonic power from 100W to 600W (50.0℃, 3min). The reduction in Escherichia coli was enhanced from 1.01lg CFU/mL to 1.80lg CFU/mL with the increase of temperature from 45.0℃ to 57.5℃ (600W, 3min). The Weibull model provided a good fit to the inactivation curves of Escherichia coli at different ultrasonic-assisted heats treatment. The simplified Weibull model could be used to predict the process of ultrasonic-assisted heats treatment inactivation kinetic of Escherichia coli and provide a theoretical basis of microbial safety control in the ultrasonic-assisted heats treatment processing of egg white liquid. At the same time, when the ultrasonic power was 300W (55.0℃, 3min), the gel hardness was increased by 101.04%, while the foam capacity was increased by 50%. In conclusion, ultrasonic-assisted heats treatment could control the microbial content of egg white liquid effectively and improve the functional properties.

Abstract:In order to solve the standing wave problem generated by single-frequency ultrasound, the whole egg liquid was dried by double-frequency ultrasonic vacuum. The mechanism of dual-frequency ultrasound was studied. The digital simulation results showed that under other conditions, dual-frequency ultrasound had better cavitation effect than single-frequency ultrasound. Compared with single-frequency ultrasound, when using double-frequency ultrasonic drying of whole egg liquid, the drying time was shortened by 30%, the average drying rate was increased by 41.6%, and the effective diffusion coefficient of water was increased by one times, which showed that dual-frequency ultrasound was beneficial to shorten the drying time of materials, increase the drying rate, and thus improving energy efficiency. Low field nuclear magnetic resonance and magnetic resonance imaging techniques were used to analyze the effects of single-frequency and dual-frequency ultrasound on internal water state and migration during whole egg liquid drying. The results showed that with dual-frequency ultrasound, the change of the overall peak area on the inversion spectrum was more significant than that of single-frequency ultrasound, indicating that dual-frequency ultrasound was beneficial to improve the fluidity of the water in the material and was more conducive to drying. In the initial stage of drying, the amplitude of the signal corresponding to free water in the inversion spectrum was gradually reduced, and the transverse relaxation time was gradually shortened. In the middle and late stages of drying, with the large amount of free water removed, the drying was mainly to remove the combined water and semi-bound water. The results of magnetic resonance imaging showed that the dual-frequency ultrasonic drying had lower brightness than the single-frequency ultrasonic drying H+ proton density image during the same time period, indicating that dual-frequency ultrasound was more likely to promote the internal moisture removal of whole egg liquid.

Abstract:In drying of paddy, the mechanical stress inside paddy kernels is caused by moisture content gradient and glass transition temperature (GTT). The stress results inside kernel crack during the milling process. The hot-air drying method was employed to investigate the effects of stepwise changes of air temperature determining GTT on stress cracking index, head rice yield and drying duration of paddy. To achieve the objectives, the concepts of glass transition for paddy and temperature and moisture distribution of material layer were determined by using numerical modeling method. The center combination tests of three-factor with five-level were employed to analyze and optimize the parameters of drying process for paddy under constant temperature. The surface temperature, initial moisture content of paddy and the hot-air speed were selected as the influencing factors. In terms of the stepwise changes of air temperature, the drying experiments were conducted at temperatures above the GTT based on the optimal parameters determined by constanttemperature drying process. The rising amplitudes of temperature were 5℃, 10℃ and 15℃, respectively. The results showed that the GTT of paddy was negatively correlated with its moisture content. The optimum parameters of constant-temperature drying were developed as temperature was 47℃ and the initial moisture content was 22.0% for paddy, and hotair speed was 0.50m/s, respectively, and the evaluation indexes were as follows: the stress cracking index was 70, head rice yield was 57.67%, and process duration was 195min, respectively. Compared with the constanttemperature drying, under the stepwise changes of air temperature of 5℃ and 10℃, the quality of paddy dried was improved as the stress cracking index was decreased by 20 and 10, the head rice yield was increased by 12.6 pencentage points and 7.7 percentage points, respectively, and drying duration was shortened by 30min and 60min, respectively. Therefore, the stepwise changes temperature of hot-air drying can improve the drying efficiency and quality of paddy based on glass transition theory. The results may provide references for the hot-air drying process and quality control of paddy.

Abstract:The vitamin B12 is an essential vitamin and participates in the biochemical reaction of the human body, including folic acid conversion and methionine synthesis. However, it is easy to lose its nutrition and function in the food processing process and storage such as light, heating and pH value. In order to improve the stability of the vitamin B12 and the vitamin B12 nutrition fortified food, the interaction between vitamin B12 and soybean protein isolate and the effect of vitamin B12 on protein structure were studied by using spectroscopic techniques (fluorescence spectrum, ultraviolet spectrum, infrared spectrum and circular dichroism spectrum). The result of fluorescence spectrum showed that the fluorescence intensity of soybean protein isolate was decreased with the increase of vitamin B12 concentration. The quenching mode of vitamin B12 on soybean protein isolate was static quenching by calculating the Stern-Volmer equation. Soybean protein isolate and vitamin B12 were bound by Van der Waals force and hydrogen bonding and binding site was one. Synchronous fluorescence spectrum indicated that the binding site of vitamin B12 and soybean protein isolate was located near tryptophan. Ultraviolet absorption spectrum presented that vitamin B12 enhanced hydrophobicity of the microenvironment near the tryptophan residue and changed the structure of protein molecules. The results of infrared spectrum and circular dichroism spectrum showed that the secondary structure of soybean protein isolate was changed with the addition of vitamin B12, which represented that the contents of α-helix and β-rotation were increased, and the contents of β-fold and irregular curl were decreased. 

Abstract:The fresh-keeping transportation container with controlled atmosphere by liquid nitrogen injection is an advanced and efficient equipment for transporting fruits and vegetables. The temperature of liquid nitrogen is -196℃. When liquid nitrogen was injected directly into the container, fruits and vegetables would be damaged. A heat exchanger with low control precision of the outlet temperature was used in the container. In order to improve the control precision of the outlet temperature of heat exchanger and utilization rate of cold quantity, a liquid nitrogen injection heat exchanger capable of storing energy was designed. A test platform was set up to study the effects of copper tube length, the type of phase change materials and liquid nitrogen flow rate on the operation characteristics of the heat exchanger. Based on heat transfer theory, a calculation model for heat exchanger outlet temperature was established. Calculated value was basically consistent with the experimental value, and the relative error values were 2.01% and 8.06%. The test results showed that the copper tube length, the type of phase change materials and liquid nitrogen flow rate had a significant effect on the operation characteristics of the heat exchanger, the copper tube length and liquid nitrogen flow rate had linear relationship with the injection time. When the copper tube length increased or the liquid nitrogen flow rate decreased, the linear relationship correlation coefficient was higher. When the coil length was 3m, the liquid nitrogen flow rate was 0.0075kg/s and the phase change materials was water, the heat exchange efficiency of heat exchanger was better. When the coil length was 3m, the liquid nitrogen flow rate was 0.01kg/s and phase change materials was water, the thermal storage efficiency of heat exchanger was better. The results provided references for control outlet temperature of heat exchanger accurately and recycle of cooling capacity.

Abstract:In order to cope with the energy crisis and environmental pollution, the research and development process of electric tractors was accelerated at home and abroad, but there was no electric tractor products to meet the needs of tractor operation. The tractor test technology can be applied to the performance test of the whole tractor and its components. The indoor bench test played an important role in the development, test and performance improvement of new tractor products. In order to speed up the development of domestic electric tractors, a multiperformance test system was developed for electric tractors, which can realize the performance test of electric tractors’ power system and energy system, as well as vehicle performance analysis. Through the force analysis and power system modeling of electric tractor plough operation, the discharge characteristics of battery packs in energy system and the efficiency characteristics of motor in power system had great influence on the operation performance of electric tractor, such as operation time and traction power. The functional requirements of electric tractor test bench were put forward, and the related characteristics of energy system and power system can be tested. According to the results of the scheme design, the design method of main equipment parameters of electric tractor test bench was put forward, including power system test module loading motor, energy system test module battery test system and DC battery simulator, and the components of the test bench were selected. The multi-functional test system of electric tractor was developed, which can complete the power system test and energy system test of electric tractor, realize the multifunction of the test bench developed, and meet the functional requirements of electric tractor development. By testing the battery pack and the motor of the power system of the electric tractor under development, the discharge performance and motor efficiency map of the battery pack can be tested, and the operation performance of the electric tractor can be further obtained. The test results showed that the developed multi-performance testbed of the electric tractor can effectively test the related performance of the motor and the battery pack, as well as the related performance of the electric tractor. The test results have good consistency with the simulation executed early, the maximum deviation is less than 10%, which means the accuracy of designed multifunction test system can meet the requirements of the development of new products of electric tractor.

Abstract:A novel robust approach of speed control was adopted for PMSM during the agricultural electric vehicle’s preshift process. Considering the twogear electric vehicle electric driveline, the gearshift process was studied and the preshift process was introduced, electromagnetic speed synchronization of the driving motor was considered specifically. Based on the structure of the driveline and the agricultural working condition, dynamic modeling was completed. And a nonlinear robust control approach was introduced to complete the robust control task of electromagnetic speed synchronization. The adopted control algorithm was characterized by errorbased and modelbased algorithm inheriting from traditional PID control and robust control. The control algorithm consisted of a modelbased algorithm component, a PD component as a feedback control and a piecewise function component as a robust feedback control, in which the system uncertainties and external disturbance were lumped. These system uncertainties and external disturbance were assumed to have upper bound. Based on the Lyapunov method, it theoretically proved the proposed control algorithm had render uniform boundedness and uniform ultimate boundedness. The effectiveness and robustness of the proposed control method for speed synchronization control of permanent magnet synchronous motor were verified by numerical simulation and bench test. By comparing with the traditional PD control, the proposed robust controller had obvious advantages under the same PD control parameters considering the load fluctuation conditions of agricultural electric vehicles. Average speed synchronization error and standard deviation were obviously better than those of traditional PD control in simulation result， which was 30% better in test result. The precise robust control paved the way for synchronization of synchronizer in the later stage and played an important role in improving shift quality.

Abstract:The homogeneous charge compression ignition (HCCI) and reactivity controlled compression ignition (RCCI) engines are very sensitive to the incylinder compression temperature, the spatial distribution of fuel and air, and the component of fuels. Variation of these facts will result in the cyclic variation in IC engine. Based on the needs of cyclic variation research in HCCI engine and RCCI engine, an online cylinder pressure acquisition and real-time combustion analysis system adopting in-cylinder pressure sensor, data acquisition card, photoelectric encoder and LabVIEW software was built. In order to improve the real-time performance of combustion analysis system, only single cycle cylinder pressure was collected and calculated. There were much pressure fluctuation in single cycle cylinder pressure resulting from channel effect and other effect, and a real-time filtering of in-cylinder pressure was adopted to reduce the interference error of single cycle in-cylinder pressure data. The filtering methods based on spectrum analysis, like fast Fourier transformation (FFT), linear interpolation and inverse fast Fourier transform (IFFT), can realize the online adaptive identification and auto pressure smooth for the single cycle in-cylinder pressure, which made the real-time combustion analysis system for HCCI and RCCI mode possible. Then, based on the smoothed cylinder pressure, some important combustion parameters such as the maximum pressure increase rate, combustion heat release rate and in-cylinder peak pressure were calculated. In order to further improve the real-time performance of the combustion analysis system, the producer/consumer operation mode which can achieve the synchronized process of real-time data calculation and fast data storage was used. The improved data sharing ability can improve the real-time ability of the combustion calculation. Different accuracy levels of calculation methods were adopted for different working stages in engine, which can reduce the calculation time for intake, exhaust, compression and expansion stages. In combustion stage, which had the largest calculating workload, the appropriate simplified calculation formulas and formula node operation modules were adopted to improve the real-time performance. Finally, the real-time performance of the combustion analysis system was analyzed and an experimental verification of the combustion analysis system was carried out. 

Abstract:Different from the existing methods by using constraint singularity or the chain singularity to synthesis metamorphic parallel mechanisms, based on the 3-RRR spherical parallel mechanism (Sm), according to the method of screw theory, a class of multimode actuated metamorphic parallel mechanisms with active hybrid suitable constrained branched chain by way of opening and locking actuated kinematic pair was presented. Using the screw theory, the degree freedom of the whole configurations of 3-SPS/SmPU multimode actuated metamorphic parallel mechanism of the proposed actuated metamorphic parallel mechanism with active hybrid suitable constrained branched chain was analyzed, the mechanism kinematics was studied according to the structure characteristics and geometric constraints of 3-SPS/SmPU actuated metamorphic parallel mechanism. The method of type synthesis multimode actuated metamorphic parallel mechanism with active hybrid suitable constrained branched chain can be also applied to type synthesis other actuated metamorphic parallel mechanisms, the metamorphic method was simple and effective, the inverse kinematics of the whole configurations was easy to solve, and constraint singularity and the chain singularity could be avoided effectively in the metamorphic process.

Abstract:In order to realize the stable and precision control of elastic beams in large overall rotation at high speed, its nonlinear dynamic model must be built and the decoupling work should be completed. Flexible rod was assumed by Euler-Bernoulli beam. The approach of assumed modes was applied to discrete the coordinates, and the Galerkin method and Hamilton principle were adopted to establish the flexible dynamic model. The regular perturbation formula was deduced with perturbation theory. Multiscale method was used to improve the perturbation formula by separating two-time parameters. The decoupling accuracy was deeply analyzed for the regular perturbation method and the improved perturbation method.The validity and feasibility of the proposed method were verified by Runge-Kutta method. The simulation data indicated that the improved perturbation solution owned high decoupling accuracy, little computation and good rapidity. The problem of low decoupling accuracy was solved compared with the common regular perturbation method which was limited by effective time series. The proposed decoupling method also avoided much calculation caused by high-order perturbation to improve the computation’s accuracy. It provided an important theoretical basis and data support for dynamic decoupling about complex multi-body flexible systems.

Abstract:The parallel mechanisms with analytic positive position solution and partial motion decoupling are of great benefit to subsequent research such as error analysis, workspace solution, singularity analysis and stiffness analysis, dynamic performance analysis, motion trajectory planning and control. Firstly, a class of two 2T1R parallel mechanisms with analytic positive position solutions and partial motion decoupling were proposed according to the design theory and method of parallel mechanism (PM) based on position and orientation characteristics equation (POC). The main topological performance, including position and orientation characteristics, degree of freedom and coupling degree calculation, was performed. Secondly, according to the method for kinematics modeling based on topological characteristics by the author, the analytic positive solution of one of the PMs was solved in detail. Then, based on the derived position inverse solution, the workspace, singular configuration, velocity and acceleration variation of the PM were analyzed. Finally, the difference between the two PMs in the above various performance indexes was compared and analyzed. Based on this, the preferred PM was selected. Because of its simple structure, good kinematics and dynamic performance, it had potential applications in the manufacturing, which was especially suitable for handling, grabbing, loading and unloading of workpieces with large length in the longitudinal direction. The research result laid a theoretical foundation for the dynamic analysis and prototype development of the preferred PM.

Abstract:While five-axis machining for the freeform surface, deviation is easily produced between the cutter contacting (CC) points and the given linear CC path because of the two rotation coordinates participating in the linear interpolation process, and the nonlinear error of the CC path is simultaneously formed. In order to effectively reduce the error, a nonlinear error compensation and correction method based on the ideal CC path was proposed. By analyzing the mechanism of the nonlinear error of CC path caused by the cutter’s attitude being changed, the machine tool kinematics transformation model and the model of the CC path nonlinear error were established respectively. The CC point was obtained firstly according to the current interpolation cutter center point. Secondly, the foot point coordinate and the spatial distance between the CC point and the CC path were calculated. The third step was to determine the compensation distance and direction of the nonlinear error respectively. After the position of the tool center point being real-time corrected, the servo control of the five feed axes would be carried out. The simulation results showed that the method can effectively reduce the nonlinear error of the CC path and had practical value for improving the control accuracy of the CC point trajectory during five-axis linear interpolation.

Abstract:The marine economy plays a very important and positive role in the national economy and social development. Because the ocean surges have a great impact on the safety and efficiency of marine logistics hoisting machine. At present, the wave motion compensation is mostly based on ship-specific sensors such as IMU or MRU, and the cost is high. A combination of logos was used, and a vision-based robotic hoisting motion following control method was proposed. Firstly, the kinematics analysis and hand-eye calibration of the manipulator were carried out. By using visual marker, the target objects in complex environments can be detected and identified. The man direction and direct linear transfer algorithm was used to calculate the orientation and position of the marker. A combination marker resisting image noise and occlusion issues with pose confusion scheme was designed. A quaternion based Kalman filter was used for pose estimation of combined marker. Then by establishing the hoist system model, the pseudodifferential feedback compound control algorithm was used on the speed loop. Trajectory tracking performance was improved. Based on the double S-shaped curve motion planning algorithm, the target motion tracking and path replanning were performed, and the acceleration/deceleration method was used to generate motion trajectory. Based on the comprehensive experimental platform of marine automatic and intelligent lifting equipment which can simulate the offshore working environment, the visual-based hoisting robot arm winch lifting and following control method was studied. And static targets and dynamic target following experiments were performed, the feasibility of the hoisting lift control and the effectiveness of the follow-up control strategy were verified.