Abstract:Accurate data sensing and processing are basic of quantitative decision-making in smart agriculture management. Image sensing provide multi-dimensional information for agriculture detection, such as color, visible-near infrared spectroscopy, 3D and thermal radiation. The traditional way to analyze these images focuses on the characteristics of color, morphology, texture, spectral reflection and so on. The limitations of sample mounts and extracted features always lead to the problems such as insufficient noise reduction and low accuracy of the recognition and detection models, especially for complex background changes and unknown samples. Deep learning (DL), a subset of machine learning approaches, emerged and combined neural networks to extract and represent the high-level features of image. It provided a versatile tool to assimilate and explore distribution and features from heterogeneous data. It could help to build reliable predictions of complex and uncertain phenomena in agriculture. In order to explain the application potential and further direction, the applied sensors, specific models and dataset sources were examined from five areas, including plant recognition and detection, disease and pest identification, remote sensing classification and monitoring, products detection and grading, and animal detection. Finally, several avenues of researches were outlined.

Abstract:In unstructured and complicated filed operation environment, the realization of autonomous navigation turning of agricultural machinery at the headland area of field is one of the key technical bottlenecks for achieving the autonomous navigation walking of agricultural machinery throughout the field. The primary task of realizing the former is to timely and accurately perceive the spatial position information of the headland area, especially the location information of the headland boundary. Based on machine vision technology, whether the headland appeared in the image or not was firstly determined according to the jumping characteristics of the gray values of pixels inside and outside the field. Specifically, two metric values of positive and negative distribution deviations were established to describe the positive and negative dispersion degree between the average pixel gray values of different rows in the image. When one of the two metric values was larger than the judgment threshold, that was, the distribution of the average values was relatively dispersed, it can be considered that the jumping characteristics had occurred and it was judged that the headland was appearing in the image. Subsequently, the image was evenly divided into eight sub-processing regions along the horizontal direction. For each sub-processing region, the distribution curve of the row gray average values was obtained and smoothed by local weighted regression method. The in-order outlier parameter was established, and based on the degree of sequential outlier of the row gray average values corresponding to the peak points or trough points on the smoothed curve, the position coordinates of the jumping peak point and pre-jumping trough point were determined, and accordingly the pixel coordinates of the jumping feature points were determined. Finally, all the jumping feature points were fitted linearly based on the robust regression method to obtain the main-body extended azimuth line of the irregular headland boundary. In the end, the main-body extension azimuth line was moved down in parallel until the average gray value of the pixels on the line was close to the corresponding gray distribution characteristic of the pixels inside the field, which was considered to be shifted to the safe position, thus the boundary line for safe turning of agricultural machinery at the current headland of field was obtained. The test results showed that the accuracy rate of judging whether the headland appeared or not was not less than 96%, the detection accuracy rate of headland boundary line was not less than 92%, and the processing time of single frame image was not higher than 0.52s based on Matlab platform. It can provide a fast, accurate and reliable technical support for agricultural machinery to implement automatic navigation turning safely at the headland of field

Abstract:The detection, identification and precise positioning of fruit under natural conditions based on machine vision is very important for the development of intelligent picking robots. In order to solve the problem that the traditional fruit detection model for the small target grapefruit missed detection and the leaf was falsely detected as the expansion period grapefruit, an improved feature fusion single multibox detector (InceptionV3-feature fusion single shot-multibox detector, IFSSD) was designed. The feature fusion single multibox detector (feature fusion single shot-multibox detector, FSSD) was used as a base detector and optimized in two ways. On the one hand, the improved InceptionV3 network was used instead of very deep convolutional networks 16 (VGG16) as the backbone network to improve computational efficiency. On the other hand, the Focal Loss function was used instead of the Multibox Loss function, which improved the mischeck ingresss of the detector due to the imbalance of positive and negative samples. Finally, the test data set was verified, and the results showed that the model achieved an average accuracy of 93.7% (mAP) (IoU was greater than 0.5). The time of one image was 29s. The model proposed can automatically detect the grapefruit in the grapefruit tree and locate it accurately in real time, which effectively promoted the development of intelligent picking robot.

Abstract:In order to recognize the sound and broken grains of wheat quickly and accurately, an image detection system of wheat grain integrity based on convolution neural network (CNN) was designed and implemented, and successfully applied to actual detection. The images of sound and broken kernels were captured and the image database and morphological characteristics database of single wheat grain were established after some image processing (segmentation and filtering). Both databases were divided into a training set and validation set according to the ratio of 7∶3. Four typical convolutional neural networks (LeNet-5, AlexNet, VGG-16 and ResNet-34) were used to build wheat grain integrity recognition model and compared with the other two traditional algorithms of machine learning (SVM and BP neural network). The results showed that the training speed of the two traditional models was faster, and SVM gave the highest accuracy of 92.25%. By contrast, all four kinds of convolutional neural networks had an accuracy rate of about 98%. Among them, the accuracy of test set of AlexNet, which had the best recognition performance, was 98.02%, and the recognition speed of it was at a rate of 0.827ms per grain. Therefore, a wheat grain integrity image detection system was developed based on this model, and used for actual detection. The detection results showed that the detecting time of 100 wheat grains was 26.3s, among which, the average image acquisition time was 21.2s, and the average image processing and recognition time was 5.1s, and the average recognition accuracy was 96.67%. The system was easy to operate, which had stable performance, and provided a reference for the design of wheat grain image detection system. 

Abstract:In order to realize wheat precision seeding under clay-wet soil conditions of rice-wheat rotation area, a pneumatic wheat precision seed casting device was developed that casting wheat to clean seedbeds fast and accurately by pneumatic acceleration. The influence of key structural parameters of outlet chamber diameter, throat distance and convergent chamber diameter on velocity of steady gas flow and inlet negative pressure, as test indicators, were studied by numerical simulation and analysis of Fluent software. Analysis results by Fluent showed that the parameter combination of pneumatic wheat precision seed casting device was as follows: diameter of outlet chamber was 6mm, throat distance was 10mm and convergent chamber diameter was 32mm obtained by single factor test as well as three factors and three levels orthogonal experiment. Under this parameter conditions, the velocity of steady gas flow was 524m/s and inlet negative pressure was 15.966kPa, by simulation. Wheat seed casting performance experiment, based on better parameter combination, by test-bed indicated that wheat seed can be casted into soil at high speed to achieve accurate and stable single seed sowing without damage while working speed was 1.2m/s, casting height was 0.1m and air pressure was 0.5MPa. Moreover, the average vesting velocity was 43.8m/s, average depth was 6.78mm, and the coefficient of variation of vesting velocity and average depth was 8.3% and 5.8%, respectively, which showed the stable performance of pneumatic seed casting.

Abstract:According to the declining seed quality of the air suction seed metering device guided with assistant seed-filling caused by high speed operation in the field, the design of the seed metering device was optimized. The structure parameters of seed plate to be optimized was defined by analyzing the factors of obstructions during seed filling process. According to the determinacy tracking model of the grain model, the gas-solid two-phase flow of the seed metering device was calculated by introducing the pressure gradient force model into coupled analysis of EDEM-CFD. Critical points of seed filling process in each stage was divided on the scales of macro and micro. The most suitable factors of seed filling state during each state were analyzed. Three factors quadratic rotation orthogonal combination tests were carried out with the index of the stable time during seed adsorption, the resistance during seed removing stage and the local void ratio at the hole, with the test factors of the Curvature coefficient of seed guide groove curve of seed plate, the depth of seed guide groove, the slope angle of seed guide groove. The optimal parameter combination of seed guide groove of seed metering plate was determined by multiple regression analysis of test results and multi-objective optimization method. The results were given as follows: the curvature coefficient of seed guide groove curve was 0.265, the depth of the seed guide groove was 2.57mm, and the slope angle of seed guide groove was 15.33°. In order to verify the results of optimal design, the static tests were carried out on the bench of seed metering device, the indoor vibration environment simulation tests of the seed meter device were carried out according to the vibration signal of the seed meter collected from operating in the field. By comparing the optimized seed plate with original seed plate and the other two testing plates, the result showed that the optimized seed plate had a better performance at high speed and vibration conditions. The seed filling performance was more stable, and the miss rate was 1.26% when the operating speed was 14km/h, the main excitation frequency of random vibration was 9.5Hz, and the peak value of power spectral density was 0.428(m/s2)2/Hz.

Abstract:Aiming at the problems of no-till corn planter, such as difficulty of passing through stubble fields, mixing of grass and soil in the seeding strip and the poor operation quality, a grass-soil separation device with combination of stubble cutting and grass guiding was designed based on the technical idea of combined operation of driving stubble cutting and passive guide grass. Several functions were achieved using the device, including cutting, poking, throwing, guiding, separation and flowing of both straw and grass. Based on the theoretical analysis of the interaction law between the key components (e.g., concave notched disc cutter and guide grass board) and straw and grass, key influencing factors and their value ranges were investigated. The optimal parameters of the guide board were determined by using CFD simulation software. To determine the optimal combination of structural parameters of concave notched disc cutter, the interaction model of grass-soil separation device-soil-straw was established by using EDEM discrete element simulation technology. The results showed that the main structural parameters affecting the tool performance were embedded depth, the height of cutter tooth and the angle of blade. When the embedded depth, blade height and knife dish angle were 73.63mm, 69.70mm and 23.41°, respectively, the performance of the device was the best, as indicated by good passage of the device with seeding straw cleaning rate of 90.16% and soil disturbance of 20.85%, which could meet the agronomic and technical requirements of no-till corn planter. Moreover, the device working performance was stable. 

Abstract:Aiming at the problems of the root of rice seedling were damaged because of the existing rice transplanting mechanism without mulch cutting device or the structure of the mulch cutting device was complicated causing poor synchronization and missing transplanting, the high-speed transplanter with extensible mulch cutting mechanism in the mulching cultivation system was designed based on the agronomic requirements of rice transplanting. The working principles of theoretical model was analyzed and a kinematic model of the rice transplanting mechanism was established. Computer-aided analysis and optimization software based on the Visual Basic 6.0 was developed and used to obtain a set of structure parameters and the trajectory of seedling-picking needle tip point and mulch cutting knife endpoint trajectory, which satisfied the transplanting requirements, the optimized parameters were as follows: seedling-picking angle was 16.01°, seedling-pushing angle was 62.43°, the mulch slit length was 44.31mm,the deviation of the mulch slit was 5.02mm, and planting position was 21.63mm. The 3D simulation model was combined with high speed photography test, the prototype machine test results were consistent with the theoretical analysis and virtual simulation results, the correctness and rationality of the design of extensible mulch cutting slit mechanism were verified. The soil bin transplanting experiment was conducted, the test showed that when the speed ratio characteristic coefficient was 1.57, the mechanism can finish cutting mulch and transplanting at the same time, the mulch slit length and plant location deviation of measured value with the theoretical values were less than 4mm, which reflected the practicality of the rice transpalnter with extensible mulch cutting mechanism.

Abstract:Multi-factor and multi-level machine-soil interaction experiment is the basis of structural design and determination of optimal working parameters for rotary tiller components. Existing indoor soil-bins have the disadvantages of backward control and measurement methods and inconveniences in replacement of blades rollers. At the same time, the problems of uncontrollable soil environmental factors exist in field experiments. In view of the above problems, a special intelligent test bench for performance test of rotary tiller components was presented, and its design principle, control mode and measurement method were expounded. The test bench consisted of a test trolley and a track system. The test bench was composed of the test trolley and the track system. The test trolley integrated the functions of rotary tillage, soil leveling, soil compaction, and tillage depth adjustment. With relatively independent functions, the test bench can realize rapid replacement of rotary blade rollers. The track system was assembled by multiple sections, for which the total length can be expanded, the height can be adjusted and the position can be moved. Electric drive mode was adopted in driving, rotary tillage, and tillage depth adjustment of the test trolley. Taking PLC as control core, radio frequency LoRa communication control technology was used to achieve wireless control input, which guaranteed the convenience in operation and maintenance of the test bench. The debugging results showed that the forward speed, rotary tillage speed and tillage depth can be adjusted continuously, which were in ranges of 0~1.17m/s, 0~340r/min and 0~30cm, respectively. Multi-measuring functions were completed in the test bench, such as forward speed, working torque, rotary speed, and power consumption. The test channels were designed to be extensible. What’s more, wireless data transmission mode was adopted to realize wireless connection between sensor data and computer. Power consumption experiments of rotary blade rollers were carried out on the test bench. Taking forward speed, rotary speed and tillage depth as the experimental factors, and power consumption as experimental index, the rotating perpendicular combination experiment was conducted on standard rotary blade roller. The effects of the three factors on power consumption were studied and the regression (equation) of the experimental index and factors was established. In addition, the comprehensive experiment was carried out on combined rotary blade roller with the index of power consumption, and the effects of width and installation angle of the helical blade were analyzed. The above experiments verified that the presented test bench can meet the requirements of multi-factor and multi-level experiment, and the good adaptability to different rotary blade components.

Abstract:The image-based approach used to evaluate inline mixing efficacy for the pesticides mixers has advantages of not disturbing flow fields and achieving convenient and quick uniformity evaluation. Inline mixing tests for a jet mixer were carried out by using plastic particles to simulate water dispersible granules (WDG) pesticides. Distribution of particles flowing in the detectable region of the mixer was collected with the help of a high-speed camera and a total reflection prism to receive images from both horizontal and vertical viewing directions. For the acquired images, the particle images were pre-processed based on the morphological method, and segmented by the iterative thresholding method. Then, the particle center of gravity coordinates and normalized moment of inertia (I) parameters were extracted from each image in two viewing directions. The particle matching and 3D reconstruction based on the multi-viewing images were realized according to the consistency of the corresponding particle abscissa. The method for calculating the uniformity of the particle spatial distribution was proposed. Furthermore,according to the reconstructed three-dimensional images,the matching of the particles between frames was completed, and the calculation method to obtain the particle velocity distribution and measure the performance of the mixer was proposed. The actual verification results of the four kinds of plastic particles used to simulate WDG of differing physical properties by the above method showed that the particles with lower sedimentation velocity (caused by small particle diameter and density similar to water) under the condition of horizontal placement of the mixer led to high mixing uniformity. Accordingly, they did not tend to have downward velocity vectors, which allowed the actual WDG to have uniform distribution after dispersing and dissolving, and sufficient mixing efficacy.

Abstract:Whole plastic mulching and furrow planting has been widely adopted as a drought resistant cultivation model in the northwest arid area of China in recent years. For further integration agronomic requirement of cultivation pattern of double width filming and covering soil on double ridges and improving the level of mechanization construction performance and efficiency of seedbed, a combined operation machine for double width filming and covering soil on double ridges was designed, which synchronously realized institutional operation once such as rotary tillage, ridging, fertilization, double width filming and covering soil and suppressing on double ridges. Based on the transmission route of combined operation machine, the key parts were designed and selected, and the operation parameters and power dissipation of rotary blades, fertilizing device and soil elevating-seedbed covering mechanism were determined. The operation process of scraper type soil lifting device and horizontal two-way spiral soil conveyer were analyzed, and the necessary work conditions to make sure that the covering soil on the all parts of double width filming seedbed were analyzed and calculated. The discrete element method was applied to simulate the device with soil elevating-seedbed covering mechanism dynamic operation process of soil elevating, transporting and covering. The characteristics of soil transporting and covering in each working link were analyzed, the related factors that affected the effect of covering soil were discussed. The field experimental results showed that under the condition of operation speed of 1.10m/s, the mechanical damage degree of day lighting surface of plastic film was 39.8mm/m2, the qualified rates of soil width covered on seedbed film edge was 94.5%, the qualified rates of soil width covered on center of large ridge was 91.6%, the qualified rates of soil depth covered on seedbed was 97.5% and the qualified rates of ridging height was 93.2%, which were up to the relevant work quality evaluation specification requirements, and the experimental results met the design requirements of combined operation machine. The field test conditions was consistent with the simulation result. The research results would provide an important reference for researching and developing the supporting agricultural machinery equipment which constructed seedbed of whole plastic-film mulching on double ridges in northwest arid area of China.

Abstract:Power measurement is one of the important methods for the detection of feed rate of combine harvester. In order to more accurately analyze the accuracy of the feed rate detection methods at different positions, two feed rate detection methods and devices were designed based on power of header driving shaft and power of tilting conveyor. Winter wheat in Hebei Province was used as the test object, and Xinjiang-3 harvester was used as a test platform and a system test was performed. The feeding amount detection system included a header active shaft torque sensor, a tilting conveyor power shaft torque sensor, a header active shaft speed sensor, and an on-board industrial computer. Through field experiments, two feed rate detection methods were analyzed and compared, and the calculation models were established based on the test data. The test results showed that the relative error of the method based on the power of driving shaft of cutting table was 19.6%, and the relative error of the method based on power of tilting conveyor was 16.1%. The detection accuracy of both methods can meet the needs of field application to a certain extent. The detection accuracy of feed quantity based on power of inclined conveyor was slightly higher than that based on power of driving shaft of cutting table.

Abstract:In order to reduce the problem of low cleaning performance of oats cleaning device, the structure of single fan three cylinder screen cleaning device was improved according to the physical characteristics of oats, and a cylinder screen oats cleaning device with arc grid screen re-cleaning was designed. A skip plate structure was installed on the large cylinder screen, which can make the material jump up and fully separate. The arc grid baffle screen and re-cleaning parts was designed and installed to reduce the impurity content and the entrainment loss. Based on the performance parameters of traditional single fan three cylinder screen cleaning device, the cleaning principle and function of skip plate of large cylinder screen and arc grid baffle screen was analyzed theoretically. Taking the rotating speed of centrifugal fan, the rotating speed of large cylinder screen and the angle of arc grid baffle screen as the experimental factors, and the impurity content and loss rate of oat grain as the experimental indexes, the indoor ternary quadratic orthogonal rotation combined test was carried out. The results showed that when the rotating speed of centrifugal fan was 1500r/min, the rotating speed of large cylinder screen was 110r/min, and the angle of the arc grid baffle screen was 41°, the cleaning effect of the device was the best, the impurity content rate was 1.96%, and the loss rate was 2.64%. A field test was carried out. Under the optimum parameters, the impurity content rate was 1.97%, and the loss rate was 2.68%, which provided a reference for the optimization of the structure of the oat cleaning device and the improvement of the whole structure of oat combine harvester.

Abstract:The size of turbulence is of great significance to the accuracy of numerical calculation. In addition, the variation of gas-liquid two-phase mixed density in the cavitation zone has a great influence on the cavitation development process. In order to investigate the effect of turbulence models on numerical simulation of cavitating flows in thermo-fluids, combined filter-based model (FBM) with density-corrected model (DCM), three turbulence models (k-ε, RNG k-ε and SST k-ω) were modified based on the local mesh size and the density of vapor-liquid mixture. The original turbulence models and modified models were used in the numerical simulation of single-phase flow and gas-liquid two-phase flow around the NACA0015 hydrofoil in varying temperatures water. The numerical results were compared with experimental data. The results showed that the modified k-ε model eliminated the effect of turbulence scale. In addition, the law of development of cavity was well consistent with the experimental results, according to the results calculated by the modified RNG k-ε model. The modified RNG k-ε revealed the law of cavitation with temperature variation simultaneously, i.e. as the temperature of the fluid increased, the vapor volume fraction was decreased, the cavitation intensity was weakened, and the cavity area became smaller. The adverse pressure gradient became smaller in the closed region of the cavity tail, and the gas-liquid interface became blurred, which reflected better corrected effect. According to validation calculations and composite comparison with the experiment, the modified RNG k-ε was applicable for numerical simulation of gas-liquid two-phase flow in thermo-fluids which can provide theoretical basis and guidance for numerical simulation of low temperature thermal cavitating flow.

Abstract:Cavitation is a physical phenomenon of centrifugal pump internal flow, during the operation of centrifugal pump, cavitation will directly lead to deterioration of hydraulic performance, and it seriously affects the safety and stability of the pump system. Therefore, it is of great significance to seek ways to improve the cavitation performance of centrifugal pump for safe and stable operation of centrifugal pump system. In order to further improve the cavitation characteristics of centrifugal pump，a method to suppress cavitation by moving the balance hole to the back of blade was proposed. According to the characteristics of centrifugal pump cavitation flow field，based on RNG k-ε turbulence model and Zwart-Gerber-Belamri cavitation model，the cavitation flow field with different cavitation numbers in the model before and after balance hole offset was calculated and analyzed. The results showed that compared with the experimental values of the original model, the head was decreased within 4% and the efficiency was decreased within 5% after balance hole offset. The critical cavitation number was decreased after the balance hole offset at flow rates of 1.2Qe, Qe and 0.8Qe. After the offset of balance hole, the distribution of static pressure zone on the back of the blade was changed. And the velocity in the low-pressure area on the back of the blade was reduced, at the same time, the turbulent kinetic energy in the flow passage can be effectively improved and it can inhibit the cavitation at all stages. Balanced hole offset can effectively reduce the volume fraction of the flow passage, improve the flow condition in impeller runner and reduce the blockage of flow passage by cavitation. The bubble volume in impeller was decreasesd obviously after balance hole offset and the fluctuation amplitude was decreased in a rotation period. The axial force was reduced and the mechanical condition of centrifugal pump was improved.

Abstract:Based on the survey data of agricultural machinery purchase of small and medium-sized farmers in Weifang, Shandong Province in 2006 and 2018, respectively, the influence of different periods of agricultural machinery purchase subsidies, characteristics of agricultural machinery purchase decision makers and family characteristics on farmers’ purchase intention was calculated by using Logit model. The results showed that with the passage of time, the purchasing behavior of agricultural machinery tended to be rational, and the efficiency of agricultural machinery purchase subsidy was greatly reduced. Keeping other conditions unchanged, the purchase subsidy of agricultural machinery increased by 1%, the probability ratio of farmers’ purchase was increased by 9.04% in 2006, and decreased to 2.27% in 2018;the income of farmers increased by 1%, the probability ratio of purchasing machines was increased by 0.46% in 2006, and decreased to 0.13% in 2018;the income of farmers’ planting industry increased by 1%, the probability ratio of farmers’ purchase was increased by 0.29% in 2006, and decreased to 0.08% in 2018;the cultivated land area of farmers increased by 1%, the probability ratio of purchasing machines was increased by 0.33% in 2006, and decreased to 0.02% in 2018. According to the calculation results, some policy suggestions were put forward, such as meeting the needs of farmers, improving the efficiency of subsidies, increasing the types of subsidies, and reasonably determining the amount of subsidies.

Abstract:Accurate estimation of crop chlorophyll content using spectral information is an important part of field crop growth assessment and the basis for precise fertilization and scientific management of crops. The rice in Northeast China was taken as the research object, a new hybrid modeling method was proposed to improve the accuracy of chlorophyll estimation and model interpretability. Firstly, based on the PROSAIL model, the canopy spectra of rice was simulated, and a lookup table for chlorophyll content was established to initially inversion chlorophyll content. Then the least squares support vector machine (LSSVM) method was used to establish the error model to compensate the PROSAIL output deviation, which can compensate for the error caused by PROSAIL modeling. To verify the proposed model’s ability to estimate, totally 13 vegetation indices that were more closely related to crop chlorophyll was selected, and then the four optimal vegetation indices were screened out through the simulation analysis of different statistical models, and the optimal prediction model for single factor input was established, including power model for GNDVI, RSI, (SDr-SDb)/(SDr+SDb), exponent model for MCARI. In addition, combined with the four vegetation indexes as input, the multi-factor prediction model of rice chlorophyll content was constructed by using partial least square method (PLS), LSSVM, BP neural network and the proposed hybrid modeling method, and the predictive model was estimated and verified. The results showed that the hybrid model had a large advantage and a low prediction bias than the optimal prediction model with single factor input. The R2 of modeling set was 0.7406, the root mean square error (RMSE) was 0.9852mg/dm2;and the R2 of verification model was 0.7332, RMSE was 1.0843mg/dm2. Compared with other multi-factor prediction models, the proposed method also had certain advantages, with high estimation accuracy and good robustness. In addition, the hybrid modeling method was based on the PROSAIL model, which the physical meaning was clear and the interpretability of the prediction model was improved. Therefore, the proposed modeling method can provide ideas and methods for chlorophyll content inversion, and provide reference for the diagnosis of rice nitrogen and monitoring of rice growth.

Abstract:The change of canopy statistical temperature eigenvalue is one of the important index for crop pest identification. However, with the effects of environmental temperature and humidity fluctuations, when canopy temperature is used directly in the time series for pest evaluation, the healthy plants must be set for comparison. Therefore, the method is not operable in practical production applications. In order to find an effective method for evaluating the canopy statistical temperature eigenvalues of rice plants after brown planthopper infestation, the brown planthopper susceptible rice variety “TN1” was taken as the object, and two treatments of brown planthopper infestation and non-infestation were set. The infrared canopy was used to obtain the canopy of rice. The temperature eigenvalues were evaluated by using a machine learning classifier to evaluate the temperature characteristics of rice canopy-induced thermal images of rice canopy. In data analysis, three canopy statistical temperature eigenvalues extracted from the thermal images were used, and the features that best reflected the differences were selected. The cumulative difference of the canopy temperature coefficient of variation was 30.78. And then, combined with air temperature, relative humidity and water temperature, the logistic regression and support vector machine were used to fit the evaluation model. For determining brown rice planthopper damage by the logistic regression algorithm，when three canopy statistical temperature eigenvalues were used as input vector, the accuracy of the logistic regression test set was 87.15%, the recall rate was 86.54%, and the F1-measure was 86.55%. Support vector machine algorithm test set accuracy rate was 86.74%, recall rate was 86.90%, and F1-measure was 86.53%. In practical applications, the statistical eigenvalue of the canopy thermal image of rice can be obtained by calculating the air temperature, relative humidity and water temperature information to evaluate whether the inversion showed the invasion of brown rice planthopper. It was of great significance for the health monitoring and diagnosis of rice.

Abstract:In order to solve the problem of accuracy of inversion of corn canopy LAI, it is necessary to study the effect of specular reflection on the image reflectance of unmanned aerial vehicle (UAV), which is independent of canopy structure. The wavelet transform was used to set the threshold of different bands of UAV image, and the specular reflection was weakened without affecting the diffuse reflection. The vegetation indices: NDVI, GNDVI, SAVI and EVI were constructed by using multispectral UAV images of the Hebei Agricultural University Xinji Test Station acquired on July 15th and 26th, 2018. The single-variable inversion model of maize canopy LAI was constructed, and the accuracy of LAI inversion was evaluated by R2 and RMSE. The results showed that when the maize plants were sparse on July 15th, the R2 of vegetation indices and measured LAI after removing specular reflection were raised from 0.7190, 0.5598, 0.6241 and 0.5985 to 0.7633, 0.6940, 0.6497 and 0.6194, and the RMSE was also decreased from 0.2244, 0.2526, 0.2214 and 0.2245 to 0.1880, 0.1958, 0.1918 and 0.1987, which showed that removing specular reflection can improve the accuracy of LAI inversion. On July 26th, when the maize plants were relatively dense, the R2 of the four indices were also increased after the removal of specular reflection, which proved that the removal of specular reflection could improve the correlation between vegetation indices and LAI. However, in this case, NDVI and GNDVI tended to be saturated, and reducing the reflectivity by threshold method would aggravate the saturation phenomenon, so the two indices could not fully reflect the change of LAI. Meanwhile, SAVI and EVI were amplified by adding a canopy background adjustment factor, and their R2 of fitting model with ln(LAI) were both over 0.6 after removing specular reflection. Thus SAVI and EVI were more suitable for LAI inversion when vegetation cover was dense.

Abstract:In order to solve the problem of forage recognition under natural conditions, a convolutional neural network method based on double-pooling feature weighting and multi-scale convolution kernel feature weighting structure was proposed. The spatial information and significance information of the image were fully utilized by using the dual-pooling feature weighted structure. Two groups of feature graphs were obtained by max-pooling and mean-pooling of feature graphs output from the convolution layer, and then these two groups of features were spliced. Finally, a feature re-calibration strategy was introduced to weight the importance of current tasks according to the feature graphs of each channel, so as to enhance useful features and suppress useless features. Image information was more fully mined by using multi-scale feature weighting structure. The 3×3 and 5×5 convolution kernels were used at the same time, and the features of the first several layers of the network were spliced with the features of the current layer to improve feature utilization rate. Feature re-calibration strategy was also introduced to weight features. The recognition experiments of ten pasture images showed that the recognition rate of the method was 94.1%, which was 5.7 percentage points higher than that of VGG-13 network, the double pooling and multi-scale feature weighting structure effectively improved the recognition accuracy.

Abstract:Aiming to solve the problem of variable-rate pesticide spraying in sparse branch orchard, a method of target leaf area calculation based on mobile laser scanning (MLS) technology was proposed to provide basic data for real-time variable-rate pesticide spraying. To eliminate the influence of LiDAR detection distance and vehicle speed on the density of point cloud, the resolution of each measurement point in vehicle moving direction and LiDAR scanning direction was calculated, and the variable-scale grid was established for MLS point cloud data. The grid area was taken as the leaf area covered by laser beam, and the regression model of real total leaf area (TLA) and total grid area (TGA) was established. In the experiment, simulation tree was used to simulate the target of thinning fruit trees, and an MLS measurement system was built to collect the cloud data of the target points. Through changing the detection distance and moving speed, totally 108 sample data for four targets with different thinning degrees were obtained. The experimental results showed that the number of target cloud was decreased significantly with the increase of detection distance and the decrease of moving speed with variation coefficient over 0.9209, while the area of target grid can be extracted stably with variation coefficient less than 0.0537. The r-squared of linear fitting of TLA and TGA was 0.9090, and the mean value of relative error of TLA measurement was 9.16%.

Abstract:With the rapid development of mobile internet, short text data of APPs has exploded. In the field of agriculture, tens of thousands of questions about agricultural technology have been put forward in agro-technical extension community. Accurate classification is the basis of agricultural intelligent Q&A and the guarantee of precise information service. In order to improve the performance of data classification，a short text classification method based on BiGRU_MulCNN model was proposed to overcome the limitations of the classification process, such as few vocabulary, sparse features, large amount of data, lots of noise and poor normalization. In the model, Jieba word segmentation tools and agricultural dictionary were selected to text segmentation, then TF-IDF algorithm was adopted to expand the text characteristic and weighted word vector according to the text of key vector, and bi-directional gated recurrent unit was applied to catch the context feature information, multi-convolutional neural networks was finally established to gain local multidimensional characteristics of text. Batch-normalization, Dropout, Global Average Pooling and Global Max Pooling were involved to solve over-fitting problem. The results showed that the model could classify questions accurately, with an accuracy of 95.9%. Compared with other models, such as CNN model, RNN model and CNN/RNN combinatorial model, BiGRU_MulCNN had obvious advantages in classification performance in intelligent agro-technical information service.

Abstract:There are two main problems in obtaining key information of forestry text, firstly, the key information is mainly considered from the perspective of keywords, and the information types of words are neglected；secondly, there is no unified description structure for forestry text on the Internet, which makes it difficult to extract word information types. Through combining the two characteristics of “keywords+information types”, a method about forestry text key information extraction was proposed based on inproved TextRank and clusters filtering. The main contents were as follows: the first step was to extract the text keywords according to the keywords extraction formula. The second step was to characterize the keywords with Word2Vec vectorization. The third step was to improve the TextRank algorithm, mainly by merging the word features and introducing the edge weights to construct the graph model of the text. The fourth step was to obtain the stable graph structures through iterative convergence, and then merged them to form clusters. And the clusters’s quality was evaluated from three aspects: the uniformity of elements distribution, the size of the clusters, and the universality of the clusters. The fifth step was to form the final clusters’set in combination with the TextRank algorithm. The final step was to label the final clusters about information types. The data used in the experiments were 2000 forestry texts related to forestry policies and news. The experimental results showed that compactness of the final clusters’ set was 0.9680, the separation of the final clusters’ set was 0.0572, and the F1-measure of the final clusters’ set was 0.8871. It showed that the information types of the clusters can be clearly marked. For a text’s keywords, their information type was obtained by calculating the cosine similarity of the keywords’ vector and the clusters’ heart. The combination of keywords and information types constituted key information of a foresty text. Meanwhile, manually labeled 400 texts, comparing with the six algorithms such as TextRank, TF-IDF, this method achieved the better results in MRR, Bpref, accuracy, and F1-measure. It showed that this method had advantages in extracting forestry text keywords.

Abstract:In order to strengthen the protection of quantity, quality and ecology of arable land, it is necessary to grasp the situation of farmland comprehensively. From the perspective of cultivated land and its surrounding ecosystem, the framework of cultivated land health productivity was constructed as “demand-function-dimension-element-index”, which included two dimensions of cultivated land productivity and cultivated land health, and five dimensions of climatic conditions, soil characteristics, utilization status, environmental stress status and beneficial ecological status. Then, according to the characteristics of the study area, the evaluation index system of cultivated land health productivity was established. At the same time, the key indicators such as vegetation coverage and biodiversity were obtained by using domestic GF-1 remote sensing data, and the healthy productivity of cultivated land was evaluated objectively. Finally, Da’an City, Jilin Province, in the Songnen Plain of China, was selected as the research area to carry out case studies. The results showed that in Da’an City, totally 40.35% and 52.07% of the total cultivated land were health-superior and health-inferior cultivated lands, respectively, while 7.58% was sub-health-superior and sub-health-inferior cultivated land. The health status of cultivated land was generally good, and the productivity of cultivated land was relatively low;the healthy productivity of cultivated land was mainly affected by the utilization and beneficial ecological conditions, and the influence of soil characteristics was the second. The evaluation system of farmland health productivity was an extension of the existing evaluation methods of cultivated land, which can provide scientific support for rational utilization and sustainable development of cultivated land.

Abstract:The spatial scale of landscape pattern has become the basis of landscape ecology research. By analyzing the characteristics and changing rules of the same landscape pattern in different scales and clarifying the scale effect of regional landscape pattern characteristics, it can be known more about the real situation of landscape pattern. Wengniute Banner of Chifeng City, Inner Mongolia was taken as the research area. The remote sensing images of the same month in 2008, 2013 and 2018 were used to combine the land use data of Wengniute Banner area. Landscape types were divided into six categories: cultivated land, woodland, grassland, water area, construction land and unused land. Landscape pattern index was analyzed. Six landscape indices at patch type level and six landscape indices at landscape level were selected to analyze the effects of different grain sizes on landscape pattern indices. The results showed that in landscape level pattern index, the number of patches was decreased from 5391 to 4231, the density of patches was decreased from 0.40 per hectare to 0.32 per hectare, the diversity of Shannon was increased from 1.37 to 1.45, and the evenness of Shannon was increased from 0.76 to 0.81, which indicated that the dominant landscape had not yet been formed, and the fragmentation of landscape was increased. At the level of patch type, the percentage of patch area had no obvious change with the change of grain size, and other landscape types were changed with the change of grain size. Among them, in 2013 and 2018, the granularity effect of water area on patch density was strong, which was from 0.005 per hectare to 0.046 per hectare and 0.010 per hectare to 0.046 per hectare, respectively. The granularity effect of unused land on effective network size was strong, which was from 24596m2 to 40697m2. The granularity effect of construction land on aggregation and cohesion was strong, which was from 0.9 to 0.3 and 94% to 49%, respectively.

Abstract:The spatial pattern optimization and land consolidation of rural settlement is of great significance to carry forward rural revitalization by zoning and classification based on scientific recognition of suitable development types for various village. The rational spatial layout optimization of rural settlements can promote the intensive use of land resources and improve rural production and living environment, and while activate the idle land resource in rural and coordinate the rural and urban development. In order to scientifically divide the types of rural settlement, taking Lijin County as an example, a comprehensive zoning system was put forward, which firstly zoned the whole rural settlement into three different evolution direction regions, and then classified the former results into different types of rural settlement guiding the future land consolidation under the planning regulation which reflected the impact of planning and the urban core area on the future development of the countryside. That following steps were in process: first of all, considering planning constraints of urban developing boundary and historical cultural conservation planning, the rural settlement was divided into three different evolution direction regions which was urbanization, historical cultural conservation zone and general rural region. The rural settlement located in the urbanization or conservation zone were identified as urbanrural integration village (URIV) and historical and cultural village (HCV), respectively. Then, a comprehensive evaluation index system was established in five dimensions of resources, population, economic conditions, infrastructure and location environment for the general rural region. Among the index system, the entropy weight method was applied to assign the weight of indictors, and the Ward hierarchical clustering was used for classifying the general rural region into different types on the basis of similarity or diversity: cluster developing village (CDV), keeping and limiting village (KLV) and dismantling and consolidate village (DCV). Finally, according to the evolution direction and resource condition of rural settlements, the land consolidation strategy of different rural classifications was put forward for rural revitalization and improvement of living environment. The results showed that thinking of the first zoning and then classification for the whole rural settlements was more scientific and reliable for classifying the different type of rural settlement, which can effectively implement regulation and guiding for the rural developing under the control of the urban developing boundary and historical cultural conservation planning. Compared with the traditional zoning method, the Ward hierarchical clustering method system can efficiently reflex the similarity among regions and diversity between the different zoning to the full extent, which can be superior to the all indictor comprehensive evaluation. The total rural settlement in Lijin County can be divided into five different types, which was urbanrural integration village (107 villages), historical and cultural village (6 villages), cluster developing village (21 villages), keeping and limiting village (180 villages) and dismantling and consolidate village (198 villages), and then a more specific strategy of land consolidation was put forward from the aspects of infrastructure, land reclamation, social security and environmental improvement. The framework of spatial pattern optimization and land consolidation of rural settlement can provide a new idea and method for the rural revitalization practice, building the beautiful countryside and improving the living environment in regional scale.

Abstract:As the carrier of regional urban development, land has been attached great importance to spatial planning and development policy. In order to explore the sustainable development mechanism of “land use-ecology” in the middle-eastern urban agglomerations in the southeast coast, taking the central Zhejiang urban agglomeration as an example, the FRAGSTATS was used to measure the landscape fragmentation index of the central Zhejiang urban agglomeration by analyzing the five remote sensing image data from 1996 to 2016, including the horizontal value of the key time nodes of landscape shape index and landscape diversity index, and the evolution characteristics of the comprehensive landscape structure of the land use in the study area;and then the land use ecology of the central Zhejiang urban agglomeration in different periods was analyzed through the ARCGIS evolution regional ecological risk spatial differentiation. It was found that from 1996 to 2016, the transfer situation between various types of land use was significantly enhanced. The area of construction land was increased by nearly three times;the proportion of forest land area showed a slow growth trend;the land area of water resources and water conservancy facilities was decreased from 5.85% to 3.89% in 2006—2016, with a large decline;the unused land was reduced by nearly 21a. The most common ratio was followed by cultivated land. The actual reduced area of cultivated land was more than that of unused land. In the field and grassland, it was mainly distributed in the northeast direction and northwest direction of the central Zhejiang urban agglomeration. The overall increase in grassland was generally reduced. Increased and reduced areas account for a small proportion of total land use area. The overall landscape pattern quality of land use in central Zhejiang urban agglomerations showed a trend of “first decline-then rise-overall decline”. The specific performance was as follows: from 1996 to 2016, the overall landscape fragmentation index was increased, and the local year was declined. The landscape shape index and landscape diversity index were decreased overall, and the local year was increased. The transfer of various types of land tended to be complex and volatile. Based on 2016 time node spatial evolution characteristics of the horizon to ecological risk analysis of middle of Zhejiang, the ecological risk index of Yiwu, Dongyang and Wuyi was between 0.69~0.82, for Ⅳ and Ⅴ level areas, ecological risk level was high or higher;the ecological risk index of Wu City, Jindong Area and Pujiang County was between 0.56~0.59, for Ⅲ level area, ecological risk was moderate;the ecological risk index of Lanxi City, Yongkang City, Zhuji City, Panan County, Longyou County and Jinyun County was below 0.49, for Ⅰ or Ⅱ level, ecological risk level was low or relatively low. From 1996 to 2016, the spatial risk of land use ecological risk grades in central Zhejiang urban agglomerations was quite different, and the spatial distribution showed the phenomenon of “convergence club” and “concentration-distribution”, that was, higher ecological risk. The area and high ecological risk area were spatially directed to the central part of the middle-middle urban agglomeration and there was a gathering situation;the lower ecological risk area and the low ecological risk area were spatially dispersed in the northwest, southeast and southwest areas of the Zhejiang city group. The research and judgment of the sustainable use of land in central Zhejiang urban agglomeration provided ideas and methods to promote the sustainable development of land use and ecological environment in central Zhejiang urban agglomerations.

Abstract:The nitrogen (N) transport and transformation processes in rice field is more complex than that in dry land. Process-based soil-rice system model requires many input parameters and it is difficult to calibrate, which severely restricts the model application in rice production region. To improve the calibration efficiency and reduce uncertainty in simulations, both Morris and Sobol’ methods were used to analyze the global sensitivities of input parameters (soil hydraulic, crop, and N transformation parameters) of the WHCNS_Rice model and guide model calibration. Two years of rice field experiments were conducted in the middle reaches of the Yangtze River. Ponding water depth, evapotranspiration (ET), dry matter weight and crop N uptake were all collected and used to evaluate the model. Results showed that the selected sensitive parameters were almost consistent for two methods, but the Morris method could quickly and effectively screen out sensitive parameters with small calculation workload, which is an effective global sensitivity analysis method for the WHCNS_Rice model. Among all model input parameters, the soil hydraulic parameters and crop parameters had the greatest influence on the output variables of crop growth, water and N fates compared with N transformation parameters. Within the soil hydraulic parameters, saturated moisture, field capacity and saturated hydraulic conductivity of the plowpan were the most sensitive parameters. For crop parameters, LAI, yield, dry matter weight, crop N uptake and ET were sensitive to total accumulated temperature, maximum specific leaf area and crop coefficient in different periods. Among the N turnover parameters, only the first order kinetic constant for volatilization and the denitrification empirical coefficient had some effects on ammonia volatilization and denitrification processes, respectively. Based on the results of sensitivity analysis, the sensitive parameters were calibrated to minimize error between simulated and observed measurements. The results showed that the simulated dry matter weight, crop N uptake, ET and ponding water depth were in good agreement with the measured values. Both the slopes of the linear regression equation and correlation coefficients between the simulated and measured values were close to 1 (P<0.01), indicating that the model could be used to simulate soil water movement, soil N fates, and rice growth for paddy soil in the region. These results suggested that sensitivity analysis based on the Morris method can significantly improve the model calibration efficiency and reduce uncertainty in simulation, which provided technical support for parameter calibration and application of the process-based WHCNS_Rice model.

Abstract:Dry matter accumulation (DM) and yield assessment are the key issues of maize production management and market of silage and deep processing. A three-year experiment (2017—2019) was carried out in maize fields of Changchun, Jilin Province, monitoring soil temperature (20cm and 40cm) in root zone, air temperature, canopy temperature and dry matter accumulation in maize growth stages. The Logistic model and the normalized Logistic model were established based on different effective accumulated temperatures with the observation in each year, separately. Then the validations of each normalized Logistic model were implemented by the observations in the others two years. Results showed that the Logistic models were varied in parameters with the data in different locations and years, based on the four effective accumulated temperatures (soil temperature at 20cm and 40cm, air temperature and crop canopy temperature) to simulate dry matter of single maize. However, the normalized Logistic model made a good performance in simulating maize dry matter accumulation under the normalized method. The statistical parameters of root mean square error, relative error, the coefficient of determination, and the index of model agreement reached good values between the simulation and observation. Especially for the normalized Logistic model in 2019, it was run better in the validation of 2017 and 2018. At the same time, the simulations effect was better in effective accumulated canopy temperature of normalized Logistic model. Thus it can be seen that the crop canopy temperature would be more available in regional irrigation management with its scale extension. These research results could support the precision irrigation system and management in irrigation district.

Abstract:Aiming to analyze the effects of saline-alkali land improvement measures on water consumption and yield control of wheat under the condition of spring water limitation, and provide theoretical basis for promoting the increase of winter wheat yield and the improvement of water use efficiency in saline-alkali wheat areas. The positioning monitoring test was adopted in the three consecutive wheat growing seasons from 2015 to 2018. Four processing was set, respectively was with biological organic fertilizer (FF), mixed with Yellow River sediment (SS) and the biological organic fertilizer and Yellow River sediment mixed (SF), and CK treatment as control. The results showed that the annual yield was 3317.77~5449.52kg/hm2 for three consecutive years, and SF treatment with Yellow River sediment and biological organic fertilizer had the highest grain yield. Compared with the control treatment, SF treatment increased the grain yield by 35%~51%. The variation amplitude of total water consumption was 352.85~394.89mm, and the total water consumption between different treatments was the lowest in CK (352.85~386.17mm). The water use efficiency of each treatment was 9.01~13.96kg/(hm2·mm).SF (12.02~13.96kg/(hm2·mm)) had the highest water use efficiency, which was higher than that of CK by 33%~48%, followed by FF (organic fertilizer) and SS (Yellow River sediment), which were respectively higher than that of control by 9%~32% and 9%~18%. Mixing Yellow River sediment (SS) or biological organic fertilizer mixing (FF) treatment can increase water storage in soil layer 0~200cm before jointing, increase water consumption from jointing to maturity stage and its proportion in total water consumption, promote the utilization of water storage in soil and deep soil water of winter wheat, and finally improve biomass and grain yield of winter wheat. The grain yield of winter wheat was positively correlated with dry matter accumulation and grain number per panicle. WUE had a conic relation with water consumption and yield of winter wheat. With the increase of grain yield, WUE was increased rapidly. Under this research conditions, with the increase of water consumption, trend of WUE was different among different treatments. Taking yield, harvest index and water use efficiency into consideration, mixing Yellow River sediment and applying biological organic fertilizer (SF) was the best treatment under the conditions of this study.

Abstract:In order to explore the effects of biochar on soil water retention, soil nutrients and soybean growth in the black soil area, a four-year observation experiment was conducted on the runoff plot of 3° sloping farmland in the northeast black soil area. In 2015, C0 (0t/hm2), C25 (25t/hm2), C50 (50t/hm2), C75 (75t/hm2), and C100 (100t/hm2) were set according to the amount of biochar applied. For each treatment, the same amount of biochar was continuously applied in 2016, 2017 and 2018. The results showed that the soil water storage in the 0~60cm soil layer was increased and then decreased with the increase of carbon loading for four consecutive years, but the effect on water storage capacity in 60~100cm soil layer was not significant. The saturated water content was increased gradually with the increase of carbon application. In 2015, the water holding capacity and the coefficient of wilting was increased gradually with the increase of carbon application. The growth rate was decreased first and then decreased from 2016 to 2018;applying biochar for four consecutive years increased the plant height and leaf area of soybean growth stages. The optimal treatments were C75, C50, C50 and C25 respectively;the canopy coverage and charcoal content of the four consecutive years showed a parabola change (R2>0.89, P<0.01). The continuous increase of C50 treatment for two years had the largest increase in each growth period, which was 81.4%, 36.7%, 31.5% and 39.6% higher than that of C0. The soil pH value, organic matter and available potassium content were increased gradually with the increase of carbon application for four consecutive years. The alkali nitrogen and available phosphorus were increased first and then decreased. The relatively better fouryear treatments were C50, C50, C25 and C25. The comprehensive fertility index calculated by the improved Nemerow index model was positively correlated with yield (R2=0.8615, P=0.0012, RMSE was 0.75). The biochar application mode with the highest level of soil comprehensive fertility was summarized, that was, 50t/hm2 of biochar applied for two consecutive years. The research result can provide a theoretical basis for the application of biochar in the black soil region.

Abstract:Nitrogen mineralization is an important ecological process that determines ability of soil nitrogen supply. In order to provide theoretical basis for efficient fertilizer application in salinized soil, the effect of organic and inorganic fertilizers on the soil net nitrification, ammonification and nitrogen mineralization under different soil salinity were determined. By laboratory aerobic incubation, under four salt levels (0.46dS/m, 0.98dS/m, 1.55dS/m and 1.97dS/m), the same amount of nitrogen of 0.0895g/kg (dry weights of pure fertilizer/dry weights of purple soil) was applied to different treatments, and five fertilization treatments (the fertilization proportion of the organic fertilizer was 0, 25%, 50%, 75% and 100%, respectively) and one blank control were provided, which were designated as U1, U3O1, U1O1, U1O3, O1 and CK, respectively. Main conclusions were as follows: soil salt concentration was decreased with the increase of proportion of organic fertilizer applied;the increase of salt content had a strong inhibition on the amination of inorganic fertilizer. When the EC was less than 0.98dS/m, the application of organic fertilizer would reduce the effect of salt on amination, while when the EC was raised above 1.55dS/m, it would obviously delay the amination process of organic fertilizer, but it would not be completely suppressed. There was a threshold value for the effect of salinity on the formation rate of NO-3N. When the EC was less than 0.98dS/m, the increase rate of NO-3N was increased with the increase of salinity level, while the continuous increase of salinity would inhibit the formation rate of NO-3N. Compared with no fertilizer, fertilizer significantly increased the amount of net nitrogen mineralization in each salt soil, and the same salt level showed that the larger proportion of inorganic fertilizer was applied, the greater amount of net nitrogen mineralization was. Compared with the application of organic fertilizer under 0.46dS/m, the difference of net nitrogen mineralization between the treatments under 0.98dS/m salt level was decreased, while when the salt content was increased to 1.55dS/m and above, salt obviously delayed the mineralization process of organic fertilizer. It was recommended that the suitable fertilizer modes for different salt levels were as follows: non-saline soil (50% urea+50% organic fertilizer), mild saline soil (100% organic fertilizer), moderate and heavily saline soil (75% urea+25% organic fertilizer). 

Abstract:In order to find out the effect of lower limit of soil moisture control on microporous infiltration irrigation of Lingwuchangzao (Ziziphus jujuba Mill.cv. ‘Lingwuchangzao’) and the optimal irrigation amount in each growth period, the six-year-old Lingwuchangzao was used as the research object. Adopting the GC-003 Internet of Things control system and soil moisture sensor monitoring, six different treatments for different lower limits of soil moisture were set for the four growth periods of jujube trees. The relationship between the change of photosynthetic characteristics, and morphological indicators, water use efficiency, yield, water consumption law and irrigation water amount of jujube trees was studied. The results showed that the increase of lower soil water limit during flowering and fruiting bearing periods and during fruit expansion was beneficial to the photosynthesis of jujube trees;the decrease of lower water limit during sprouting and leaf spreading period and the increase of lower water limit during flowering and fruit bearing period were favorable for the growth of morphological indicators of jujube trees. T6 treatment, that was, the lower limits of soil moisture during sprouting and leaf spreading period was 65%θf (θf was field water holding capacity), and during flowering and fruiting bearing period was 75%θf, during fruit expansion was 75%θf, and during fruit maturation was 65%θf, the lower limit was higher in each growth period, which had significantly different photosynthetic characteristics and morphological indicators from other treatments (P<0.05). With the increase of the lower water limit, the water consumption and yield of jujube trees were increased. The water consumption and yield of T6 treatment were the highest, but the water use efficiency of T3 treatment（the lower limits of soil moisture during sprouting and leaf spreading period was 55%θf, during flowering and fruiting period was 75%θf, during fruit expansion was 65%θf, and during fruit maturation was 65%θf）was the best, and there was no significant difference with the yield of T6 treatment(P>0.05). The yield of T6 treatment was only 5.68% (2018) and 0.90% (2019) higher than that of T3 treatment. Compared with T6 treatment, T3 treatment decreased the irrigation water volume by 22.57% (2018) and 13.59% (2019). The most suitable lower limit of irrigation water during the four growth periods of jujube were: during sprouting and leaf spreading period was 55% θf, during flowering and fruiting bearing period was 75%θf, during fruit expansion was 65%θf, and during fruit maturation was 65%θf, and all the upper limit were 90% θf. The study results can provide scientific basis for planting Ningxia Lingwuchangzao with microporous infiltration irrigation and water management.

Abstract:In order to address the effects of different seedbed treatment on the morphological characteristics and population uniformity of maize seedlings under no-tillage seeding manners, a field positioning experiment was conducted in June 2018 at the Wanbei Comprehensive Experimental Station in Suzhou, Anhui Province. Four different no-tillage seeding manners were investigated after wheat straw returning to field, including stripe rotary tillage (ST-X), straw mulching tillage (SMT-Y), stripe vertical tillage (ST-Z) and stripe subsoiling tillage (SST). The seedbed soil flatness, transverse maximum height difference, seedling morphological characteristics (leaf age, plant height, stem diameter and root length per plant) and population’s uniformity were determined. Experiment results showed that the average soil flatness of ST-X, SMT-Y and ST-Z was decreased by 7.67mm, 16.33mm and 11.00mm as compared with that of SST of strip subsoiling, respectively, however, only SMT-Y showed significant effect;the seedbed surface flatness from high to low was SMT-Y, ST-Z, ST-X and SST. In addition, the population’s uniformity of maize seedling stage of ST-X, SMT-Y and ST-Z was significantly increased by 4.34, 1.10 and 10.18 percentage points, respectively. The better the surface flatness effect of the seedbed was, the better the population’s uniformity, the worse the soil flatness effect, and the more serious the size of seedlings were. The population’s uniformity from large to small was SMT-Y, ST-Z, ST-X and SST. Due to the large amount of straw covered by the side-slumped (SMT-Y) seedbed, it was difficult to break through the straw layer after germination of maize seeds. Thus the average plant height, the stem diameter and the root length of seedlings were the lowest. Correlation analysis showed that there was a linear and significant negative correlation between soil flatness (SMN), horizontal maximum height difference (Δh) and population’s uniformity of the seedling stage (Q), the correlation coefficients were 0.963 and 0.914, respectively. In summary, the surface flatness effect of the seedbed helped to improve the population’s uniformity of maize seedling stage, the stripe vertical tillage antiblocking manner was preferred among the four no-tillage seeding manners, which could effectively improve the soil structure of plough layer, provide a clean and flat seedbed, inhibit the waterlogging catastrophe of the gully to promote the growth of seedling, therefore this was the most suitable seedbed straw treatment for summer maize no-tillage seeding in Shajiang black soil region of Huaibei Plain.

Abstract:For the modern intelligent irrigation system, a moisture sensor with high measurement accuracy, low power consumption, low price, small structure and simple calibration process is urgently needed. A capacitive low-cost soil moisture sensor and its signal processing circuit was presented based on the principle of RC steady-state response peak detection. The characteristic of the sensor circuit was that a RC series circuit realized slow charge and fast discharge by adding a discharge diode. The influence of the sensor’s sensitive area, electrical characteristics, calibration model, temperature drift and conductivity on the output signal was tested. Experimental data analysis showed that the average sensitivity of the sensor for measuring volumetric water content was 12.187mV, and the sensitive area was 3.8cm×2.5cm×7.2cm;the output signal of the sensor was not affected by the supply voltage, and the current consumption was only 3~4mA;by calibrating in different dielectric constant solutions and combining TOPP’s empirical formula, based on working principle the exponential calibration model of the sensor can be well fitted to the relationship between relative dielectric constant and soil volumetric moisture content, and the determination coefficient R2 was greater than 0.96. In the range of 5~50℃, the measurement error caused by the temperature drift of the sensor was about 0.5%. In the range of 0~2000μS/cm, the maximum measurement error of the sensor caused by conductivity was less than 4.2%. The measured data in Loess and cinnamon soil showed that the maximum error of the sensor was 2.17%. Compared with similar sensors, the test accuracy was comparable, and the cost-effective advantage was obvious. It was especially suitable for large-scale wireless soil moisture sensor detection systems.

Abstract:Bio-oil organic phases were prepared by microwave pyrolysis of biomass with the compound absorber of TiC/SiC. The effects of mass ratios of TiC to SiC, absorber to biomass and microwave power to biomass on the yield of organic phase were analyzed by response surface methodology. The effects of pure SiC and compound absorber on the yields and chemical compositions of organic phase were analyzed and compared under the optimal conditions, and the characterization and analysis of bio-char were also carried out, to explore the properties and potential of organic phase and bio-char. The results showed that all factors had obvious effects on organic yield with interactions between the factors. The optimal yield was 28.60% under conditions of TiC to SiC mass ratio of 20%, absorber to biomass mass ratio of 53% and microwave power to biomass mass ratio of 9.5W/g, which was similar to the predicted value of 28.69%. When the pure SiC was used under the optimal conditions, the organic yield was reduced to 23.35%. The pyrolysis products from cellulose and hemicellulose could be retained more by introducing appropriate amount of TiC, which could increase the organic yield and reduce the relative content of acids, ketones and phenols at the same time. A relatively large number of furans, alcohols and phenols and their relatively concentrated carbon atom distribution made organic phase have high potential as chemical raw materials. The NMR analysis showed that the ratio of aliphatic hydrogen/carbon to aromatic hydrogen/carbon in organic phase obtained by using compound absorber was increased significantly, which verified the accuracy of the analysis. In addition, the bio-char obtained by using the compound absorber had higher carbonization degree and adsorption performance, and its specific surface area and pore volume were 360m2/g and 0.22cm3/g respectively. It had high potential to make active materials. The research result provided experimental and theoretical basis for further industrial application research.

Abstract:In order to explore drying characteristics and the change law of moisture of straw-based nutrient seedling-growing bowl tray during the drying process, under the conditions of different drying temperatures (50℃, 55℃, 60℃, 65℃ and 70℃), hot air speed (1.0m/s, 1.5m/s, 2.0m/s, 2.5m/s and 3.0m/s) and microwave power (180W, 360W, 540W,720W and 900W), the microwave coupled with hot air drying experiment was carried out for strawbased nutrient seedling-growing bowl tray to study the effects of different drying factors on drying rate and effective moisture diffusion coefficient, and establish a dry kinetic model. The results showed that there were only two stages: falling speed drying and rising speed drying, and there was no obvious constant-speed drying stage during the microwave combined hot air drying process of straw-based nutrient seedling-growing bowl tray. The microwave coupled with hot air drying can significantly increase the moisture diffusion capacity inside the materials and improve the effective moisture diffusion coefficient, and the change law of Deff with variation range of value from 2.29641×10-8m2/s to 6.14736×10-8m2/s was consistent with the law of MR. By fitting 12 dry kinetic mathematical models, the Midilli et al model had the largest R2 average value, the smallest χ2 and eRMSE average values, and there was a good consistency between the value of MR obtained from experiment and the prediction value based on Midilli et al model under different conditions, which indicated that the model was suitable for predicting the change law of moisture content during the drying process of the microwave coupled with hot air. The research results can provide theoretical basis and technical support for the application of microwave coupled hot air drying technology in drying straw-based nutrient seedling-growing bowl tray and other materials. 

Abstract:Distributed in the eastern Qinghai-Tibet plateau where the environmental condition is unique, Oula lamb is of distinction owing to the quality of its meat. Aiming to establish the fingerprint of volatile flavor for Oula lamb meat. The lamb meat was obtained from four kinds of lamb: Oula lamb, Hu lamb, Dorper lamb and Tan lamb. Extraction and analysis of the volatile compounds were carried out by headspace solidphase microextraction and gas chromatography-mass spectrometry respectively. At the same time, gas chromatography-olfactometry was used to assess the fragrant compounds. Principal component analysis and cluster analysis were applied to determine the chemical variability among four kinds of lamb meat. The results showed that 53 volatile components of Oula lamb meat were identified and quantified, including aldehydes, heterocycles, hydrocarbons, alcohols and ketones, among which 77% possessed perceptible aromas. Totally 20 kinds of aldehydes with their content accounting for 62% contributed the most to flavor. Grouping of samples highlighted a good classification of the results, providing a significant separation between Oula lamb meat and other three kinds of lamb meat. Characteristic flavor compounds of Oula lamb meat mainly included (E)-2-hexenal, (E,E)-2,4-heptadienal, (E,E)-2,4-octadienal, 3-octen-2-one and other unsaturated aldehydes and ketones, together with some hydrocarbons, such as p-cymene, and other flavor compounds such as benzothiazole, providing fruits, nuts and grass odors. The findings provided the volatile fingerprint of Oula lamb meat, which can promote the development of related products of Oula lamb.

Abstract:In order to investigate the effects of covalent interaction of black kidney bean protein isolate (BKPI) and different concentrations of chlorogenic acid (CA) on the function of the protein, the effects of the covalent interaction of BKPI and different concentrations of CA on protein structure were studied. The relationship between structural change and the functional properties of the complexes was analyzed through dynamic light scattering, fluorescence spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The results showed that the turbidity and the bonding content of CA in the complexes were increased, and its content of free amino group was decreased with the increase of CA concentration, the covalent interaction made the distribution of droplets in the solution more uniform. The secondary structure of BKPI was changed and the contents of α-helix and unordered decreased, while the contents of β-sheet were increased, and resulting in its conformational change. The decrease in fluorescence intensity with the increase of CA concentration, indicating the unfolding of the protein structure. The addition of CA improved the antioxidant activities and emulsification properties of BKPI. When the concentration of CA was 0.25g/(100mL), the antioxidant activities (168.95μmol/g) and emulsifying properties of BKPI were the best. These results suggested that CA-BKPI complexes could be used as efficient antioxidants and potential emulsifiers in emulsion-food systems.

Abstract:In order to expand the working range of heat pump and improve the applicable range and annual utilization rate of heat pump system, an air source heat pump unit with vapor injection technology was designed. The heat recovery device was used to recover the waste heat from the dryer exhaust gas to preheat the fresh air. The heat pump unit consisted of three sets of heat pumps with different powers. The heat pump unit’s start-stop combination adapted to different process requirements and environmental conditions, heat pump can improve the annual energy efficiency ratio by this way, and the enhanced vapor injection technology improved the performance of the heat pump system in low temperature environment. The designed heat pump unit was tested. When the ambient temperature was -5℃, the air supply temperature of the heat pump was 40℃ and the COP of the heat pump was 2.21, the air supply temperature of the heat pump used enhanced vapor injection was 45℃ and the COP of the heat pump used enhanced vapor injection was 2.33. The experimental results showed that the validity of vapor injection technology and the designed heat pump can meet the operating requirements of recirculation drier under different environmental conditions. This study was of great practical significance for the development of green and energy-saving drying process equipment system. The results showed that the heat pump dryer can be applied to rice and wheat drying operations in the Jianghuai region.

Abstract:A rotating tray microwave vacuum (RTMV) dryer was designed to solve the problems of uneven heating of materials, difficult control of hot spots and poor dried quality. The machine was composed of drying box, control system, vacuum system, transmission system, water circulation system and heating system. In order to make the material heating uniformly, the main axis with five evenly distributed rotating bracket was placed into the microwave vacuum drying chamber and driven by a stepper motor. During the drying process, the material was rotated constantly around the main axis with a horizontal level. The vacuum system can remove the moisture evaporated from the material in time during the vacuuming process. The combination of dryer and water circulation system ensured the normal operation of vacuum pump, so as to maintain the vacuum pressure of drying chamber consistently. The control system can be divided into five modules: the main control, A/D conversion, expansion, output control and display screen. The system took the P89V51RD2FN chip as the core to control the coordination of each module, which can adjust the drying pressure in the drying room between vacuum and normal pressure precisely. The papaya was used as the material for the performance test and compared with the traditional microwave drying method. The results showed that the carrying capacity of the dryer was increased by 80% compared with the latter. And the drying time was shortened by 43.8% at the same time. The unit energy consumption of papaya slices treated by RTMV dryer was about 29.8% lower than that by the conventional way. And the dehydration uniformity reached up to 97% with consistent color distribution between inner and outer of the dried sample, showing good drying uniformity of RTMV drying technology. The designed dryer ensured the uniform heating of materials, improved the drying efficiency and guaranteed the drying quality of materials, which provided a reference for the subsequent application.

Abstract:Aiming at the problems of low heat energy utilization rate, uneven heating of tea and low productivity, etc., in order to improve the quality and yield of tea processing, a drum-type tea hot air redryer machine was designed. The basic structure and working principle of the dryer were explained, and the key components were analyzed theoretically. The key design parameters such as the drum speed, installation angle of roller, and hot air control cabinet were determined. The CFD-DEM coupling simulation method was used to analyze the separation ratio and temperature change of tea particles in the barrel at different rotation speeds of the drum. It was found that when the rotation speed of the drum was 15r/min, the tea particles separation ratio and temperature were changed optimally, and the re-dryer effect reached the optimum. Based on the design and simulation experiments, a set of traditional tumbler tea dryers were designed to be compared with the designed re-dryer. The test results showed that when the average speed of the drum was 15r/min, the average working temperature was 130℃, when three fresh leaves were used as raw materials, the productivity, moisture content, tea break rate, power consumption rate, and effective working temperature of the re-dryer were 65kg/h, 3.5%, 0.8%, 0.6kW·h/kg and 130℃, respectively. At 130℃, the tea leaves processed by the redryer machine can reach the superstandard standards, and each index was better than that of traditional machines, which met the working requirements of the re-dryer machine.

Abstract:Tire force information is the basis of research on vehicle dynamics control system and vehicle reliability, and the most effective means for tire force testing is force-measuring wheel sensor (i.e. force-measuring wheel). At present, the research on force-measuring wheel mainly focused on elastomer components, and in view of the significant influence of tire on the motion characteristics of vehicle, the whole force-measuring wheel, including elastomer and rubber tire body was modeled and tested. Firstly, the structure of force-measuring wheel was introduced in detail. Besides, the method of modeling tire carcass and the method of dealing with contact problems between components were clarified, and a finite element model of the force-measuring wheel prototype (meridian tire 195/65R15) was established. Then, based on the tire stiffness machine, the bench test of vertical working condition, lateral working condition and longitudinal working condition of force-measuring wheel prototype was carried out. Finally, the finite element simulation analysis of force-measuring wheel under three working conditions were executed. The comparative analysis of test and simulation results showed that the maximum absolute values of the relative error of strain values of each measuring point under the three working condition were 4.86%, 3.92% and 3.15%, which indicated that the modeling method determined was feasible, and the model can accurately reflect the wheel force under steadystate conditions. The rubber carcass and elastomer as a whole were studied, which laid a foundation for the decoupling optimization of the multi-dimensional force structure of force-measuring wheel. 

Abstract:A new rapid design method for agricultural machinery was proposed to promote agricultural design reuse technology. The method was implemented based on shape distribution model retrieval. Firstly, the CAD models in agricultural database were normalized. According to mesh area, all the triangular meshes that belong to each model were divided into Max, Mid and Min groups. The Sobol quasi-random sequence was used to sample feature point from each group. Then three points were defined as the basic sample unit, which was used to fuse the D2, D3, C1 and A3 features together. The variation coefficient of each feature was calculated and the proportion was regarded as sub-feature weight of fusion feature. Thereafter, the multi-feature histogram of shape distribution was formed by connecting different weighted features. The χ2 distance was selected to measure the similarity between feature histograms. Finally, the effectiveness of the proposed method was proved with selfbuilt agricultural model database using VS2010, Matlab 2016b and Open Cascade. The results showed that the retrieval precision of distance D2 feature was higher than that of curvature C1, angle A3 and area D3 features in agricultural model database. The proposed method of adaptive weighted shape distribution (AWSD) performed better than D2 when retrieval recall was ranged from 0 to 0.5, and as effective as D2 in the range of 0.5~1.0. Compared with D2 retrieval method, the comprehensive retrieval precision of AWSD method was increased by 8.5%. The retrieval cases of tractor wheel hub and harvester picking board demonstrated AWSD outperformance in the aspect of objective retrieval satisfaction. The new model retrieval method that could fuse multi-shape distribution features injected fresh energy to agricultural machinery rapid design.

Abstract:In order to obtain users’ massive innovative resources and real user needs, enterprises open product innovative design process to users. Due to the involvement of a large number of unorganized and autonomous individuals, the dynamic and complex evolution of the design process has gradually attracted attention. Unlike the existing literature, which regarded the user’s proposed product solution as a constant, the process of user participation in design was regarded as a dynamic gradient process. Therefore, the user’s individual solution and the product model interacted and iterated in the process. Firstly, the typical results of individual interaction of the user were studied. Based on the game theory, the game model was established and its Nash equilibrium was solved. Secondly, the dynamic evolution of user groups was analyzed and its growth process was simulated. The simulation results were compared with the definition of the scalefree network, and the conclusion was drawn that the user group involved in the design was a typical scalefree network. According to the user’s individual interaction model and the user group network model, the software simulation was carried out. The coal crusher design project was used as a case study to verify the correctness of the theoretical model and simulation results. The conclusion that the product model tended to converge in different communication environments was obtained. This conclusion provided a theoretical basis for the application of a large number of users to participate in the design. According to the discrete point simulation and the surface fit, the convergence speed distribution of product solution with user’s game income as the argument was obtained. It was concluded that the convergence speed of the overall solution of the product was related to the parameters of the interactive environment, which was more complex and irregular. Therefore, dynamic monitoring was important when users were involved in the product design process.

Abstract:Aiming at suppressing the amplitude and time of oscillation, the uncertainties of the disturbance of unknown external disturbances of the stay cable-magnetorheological damper control system and uncertainties in the parameters of the damping controller. Based on linear matrix inequality (LMI) theory, the H∞ performance index and nonfragile control were used to suppress external disturbances and closed-loop system parameter perturbation problems, respectively. Regional pole configuration was used to characterize the fastness and stability of vibration reduction control, and variance was used to represent small amplitude and vibration speed. The LMI toolbox in Matlab was used to solve the convex optimization problem with multiple LMI constraints and linear objective functions, and a non-fragile vibration damping controller design form with multiple performance index constraints was given. Finally, the cablestayed cables C22 and C13 of a crosssea bridge in Zhejiang Province were taken as an example for simulation verification, and the vibration reduction effects were analyzed and compared. The results showed that the vibration damping controller designed by this method not only had good immunity and stability under different random disturbances, but also could reduce the amplitudes of different cable vibration states by 57.805% and 74.395%, the reduction of convergence time was 56.705% and 77.845%, and the vibration reduction effect was better, which could meet the needs of marine engineering applications.

Abstract:The aircraft has the characteristics of many parts, complicated structure and high assembly accuracy requirements, and its assembly has requirements for safety assembly and less reversible assembly and so on. Based on the key product characteristics (KPC) and key control characteristics (KCC) parameters of aircraft, a theoretical method for assembly error sensitivity quantification analysis based on the state space model was proposed. And the error sensitivities in the precision assembly process of the buttedjoint assembly of the aircraft were elaborated and defined, which were divided into three levels: feature level, position level and system level. The relationship between input vector and input matrix was obtained by solving the state space model of aircraft and its output equation, and the state transition matrix was obtained, and then the theoretical expressions of different levels of error sensitivity were obtained. The random assembly feature error value which obeys normal distribution was substituted into system matrix. Monte Carlo simulation was used to calculate the sensitivity indexes of different assembly features. And the sensitivity indexes of feature level obtained by theoretical calculation and Monte Carlo simulation respectively were compared and analyzed. The results showed that it was feasible to apply the sensitivity analysis method of dynamic system to the accuracy prediction and analysis of the buttedjoint assembly of the aircraft. The analysis method of aircraft assembly error sensitivity analysis based on state space model proposed was accurate and reasonable. This research method had positive significance for the accuracy evaluation of the buttedjoint precise assembly process of the aircraft.