Abstract:Peanut is a very important crop for production and trade of edible oil in the world and in China. China is the largest peanut producer in total annual production which accounted for about 40% and the second-largest in peanut area planted accounted for about 20% in the world just followed India. However, although to be not as the large peanut producers as China, India and Nigeria, the United States, Argentina and Brazil all are the quite important peanut exporters in the world and respectively accounted for 16.03%, 23.58% and 4.72% of the world export peanut in 2016. Especially in the United States, the peanut area planted only accounted for about 2.46%, but total annual peanut production accounted for about 6.11% and export peanut accounted for 16.03% in 2016, which made the United States become the strongest peanut nation in the world. Based on comprehensively analysis, the main reason why the United States has been the strongest peanut nation is that high level harvest mechanization played an important role in peanut production. Harvesting is a key part in peanut production, it accounted for more than 60% labor employment of the whole process. China and the United States are both the important peanut production and export superpowers in the world, but the Chinese peanut production level especially harvest mechanization level is far below that of the United States, which causes peanut export international competition difference. The American two-stage mechanization harvesting pattern and peanut harvest mechanization technology lead to its peanut production with high yield, quality, efficiency and great international market competitive advantages. However, there are several peanut mechanization harvest pattern coexisted in China and of which the low harvest mechanization level restricted its peanut production benefit and export competitiveness. Based on systematic analysis about large relevant literature and practices on peanut production, the development and technology status, history and main reasons of peanut harvest mechanization of China and the United States were deeply analyzed. The structure principles and characteristics of the newest peanut harvest machine, including peanut digger, peanut combine and peanut harvester in two stages in both China and the United States were respectively introduced and contrasted. Through comprehensive studies on the natural condition, history and social surroundings of peanut production development, the main promoting factors which enhanced American peanut harvest mechanization and the main restricting factors of China were discovered, which had important significance to accurately comprehend the improvement of peanut production and harvest mechanization of the two countries. In the end, the development trend and key point for studying on Chinese peanut harvest mechanization were put forward, which had certain reference value for enhancing Chinese peanut harvest mechanization development, and taking some suitable measures to accelerate Chinese peanut harvest mechanization development.

Abstract:Because the sowing performance of precision rice seeders is influenced not only by the operational parameters but also by the physical properties of seeds, during the rice seedling nursery process, sowing quantity in plug tray varies from time to time. Therefore, monitoring of sowing quantity by workers is needed. In order to solve the problem that human labor spends much time on working in outdoor environment and its low efficiency, a rice nursery tray images wireless transmission system based on embedded machine vision was designed. The embedded machine vision system was composed of embedded development platform Tiny4412, WiFi gateway, network camera, infrared sensor module and remote computer. The embedded Linux operating system, camera driver, GPIO port driver and network file system configuration were installed in embedded development platform. Applications for the device were programmed with Qt development tool. The applications included image acquisition, real-time images displaying on screen and friendly interactive interface. Jpeglib static library was used to compress the images. Through the WiFi network, embedded system and remote server achieved socket communication in accordance with the provision of protocol data transmission. The remote server achieved collecting, validating, displaying and saving the images based on the Netty framework. The test results showed that the transmission of BMP and the compressed JPEG images could meet the operational requirements of automated rice sowing test line. The transmission rate of JPEG images was greatly improved. The embedded data acquisition terminal could collect stable seeding tray images, and successfully upload to the server. The network average packet loss rate was 0.23% and the error rate was 0.23%. The design of the system laid the experimental platform for the achievement of remote control to the rice sowing quantity of rice sowing test line and the development of embedded-machine-vision-based system for rice nursery trays sowing quantity detection.

Abstract:The picking robot in unstructured environment has practical value in visual localization of disturbed grape. Firstly, the shape of grape was analyzed based on model of “flexible rod-hinge-rigid rod-mass ball” and its disturbed state was decomposed into pendulum of XOY plane and YOZ plane, and then fruit and stalk of grape were obtained by Otsu function from multi frame image in video of which captured disturbed grape. Then centroid of grape in each frame image was calculated, and curve fitting of grape centroid of each frame image was made. The period of grape pendulum movement and swing angle were calculated to judge whether current disturbed of the grape was suitable for visual positioning. For disturbed grape that can achieve visual positioning, choosing grape images corresponding to location in the middle of centroid point of pendulum motion, Canny edge detection was carried out on the upper rectangular region. The method of Hough line fitting and angle constraint were used to localize picking point of disturbed grape. Experiment results of visual localization showed that the accuracy of visual localization for disturbed grape picking points under different illuminations were more than 80% in natural environment, which provided theoretical basis for the application of picking robot in practical production.

Abstract:A smooth path planning method for mobile robot with A* ant colony optimization was proposed based on dynamic feedback for mobile robot. First of all, in order to overcome the disadvantage about slow convergence speed of ant colony algorithm, simplified A* algorithm was presented to optimize the initial pheromone settings, which was able to solve the blindness of the first search. In this step, the planning path with the minimum value of the valuation function was obtained by the evaluation function of A* algorithm. And the presented multi-evolutionary strategy mechanism which could increase search space was used to strengthen the global search ability of the algorithm. Secondly, in order to further improve the adaptability of algorithm about the problem of local minimum and stagnation in the path planning, the key parameters of the algorithm were systematically analyzed and the closed-loop feedback idea was adopted to adjust the parameters of ant colony optimization algorithm dynamically. Finally, combining with the cubic B spline curve method, the planning path was smoothed to meet the practical movement route of mobile robot. The simulation experiment results showed that compared with traditional ant colony (AC), A* ant colony optimization based on dynamic feedback could reduce 10.4% of the average path cost and shorten 65.8% of the computing time in average. In addition, compared with ant colony system (ACS), the average path cost could be reduced by 5.9%, the calculation time could be shortened by 52.6%. The improved ant colony optimization algorithm could plan a smooth and high quality path in both the dynamic and static environments.

Abstract:The spray deposition uniformity is an important measure index to evaluate spray quality. Through improving the spray deposition uniformity, the pesticides can be saved under the premise of high pesticide effect. Aiming at studying the uniformity characteristics of dynamic spray deposition for PWM variable spray system, the carmine solution was used as spray reagent and matrix tray with holes was put on the conveyor to collect droplets, and then the spray deposition concentrations of each hole were calculated by the method of concentration-absorbance measurement. The impacts of spray pressure, frequency and duty cycle of PWM signal on spray deposition uniformity for single nozzle were tested from three aspects of whole area, forward moving and spray bar direction. The research results suggested that for single nozzle, the frequency of PWM signal had bigger impact on spray deposition uniformity in forward moving direction than that in spray bar direction and there was no need to set too large value of frequency unless it was required to guarantee the continuity of spray. Moreover, before the duty cycle of PWM signal reached a certain value that the flow rate of spray became stable, the duty cycle only influenced the spray deposition uniformity in forward moving direction significantly for single nozzle, and when the duty cycle was bigger than the value, it can influence the spray deposition uniformity in both the forward moving and spray bar directions for single nozzle. The results also indicated that the spray pressure had opposite effect on spray deposition uniformity in forward moving and spray bar directions for single nozzle. These results could provide references for setting operating parameters of spray work and studying the uniformity characteristics of dynamic spray deposition for multi nozzles.

Abstract:The liquid-level data is one of the most important informations for flying operators of spaying UAV. During the operation, the liquid content in the pesticide tank is dynamic, the flying operators have always to pay attention to the liquid content so that they can make suitable decisions for the flight control according to the liquid content adjustment in the pesticide tank. Therefore, the liquid-level monitoring method for pesticide tank is important in the design of key components of spraying UAV. In order to explore the feasible method for liquid-level monitoring of pesticide tank in spraying UAV, several major methods about contact and non-contact liquid-level monitorings were reviewed, including differential pressure, floating electrode, capacitance, ultrasonic, laser, photoelectric, flowmeter, machine vision and radar. Spraying UAV has special requirements, such as liquid surface violent fluctuation, different physical and chemical properties of different pesticides, different shapes in different tanks and high anti-corrosion requirements and small size of tank. Lots of limitations of the above mentioned methods when they were used in spraying UAV were pointed out. And then solutions called air-pressure wireless liquid-level monitoring (APWLLM), a kind of non-contact liquid-level monitoring method, which was suitable for use in spraying UAV, were proposed. It would provide a reference for the further development of liquid-level monitoring device for pesticide tank in spraying UAV.

Abstract:Accurate measurement of tillage resistance for cultivate component is critical. The related resistance testing device has complex structure, high maintenance cost, lack of overload protection and difficulty in collection in farmland. Aiming at the problems of the related resistance testing device, the tillage resistance testing device (TRTD) for sliding cultivate component was designed. TRTD consisted of component library, torsional spring, rotation axis, positioning plate and encoder. The force analysis of double-wings subsoiler was carried out. A measurement method of tillage resistance was established which contained the relationship of correction factor k as a function of spring corner θ, tilling depth H, tilling speed v, soil bulk density ρ and subsoiler structure parameters. In order to evaluate the TRTD, a soil bin contrast test with traditional testing device (TTD) was conducted under six tillage condition treatments. The test results showed that the mean and variance of the measured sample from both testing devices had no significant difference. The results of precision analysis showed that the maximum relative error of TRTD was 1.34% compared with TTD. The results of fluctuation analysis showed that the fluctuation amplitude of TRTD was similar with that of TTD and both relative deviations were not more than 5%. TRTD met the requirement of accuracy and stability and possessed the function of overload protection as well as providing condition for acquisition of tillage resistance.

Abstract:Aiming at the need of precision rice hill-direct-seeding, the precision hill-direct-seeding seed-metering device for rice was designed with the rebound dipper, the work principle of seed-metering device was stated and the movement track of rice seed was analyzed in the process of seeder’s dropping by means of the Matlab software, the evaluation test of the seed-metering device was conducted by using three kinds of rice, which were Longdao 6, Longqingdao 2 and Longqingdao 3, and rotational quadratic orthogonal experiments was carried out to further analyze the effects of qualified rate, reseeding rate and missing rate on seeding performance, including rotation speed of spinning disk and height of hopper. The JPS-12 detecting and experimental set of seed-metering device was selected to test sowing performances. Experimental data was analyzed by Design-Expert software so as to establish the mathematical model between the experimental factors and indexes. The result showed that the best operational parameter combination was that as the rotation speed of spinning disk was 29.34r/min and height of seed hopper was 60mm, the qualified rate and reseeding rate of Longdao 6 were 87.23% and 9.56%, the qualified rate and reseeding rate of Longqingdao 2 were 90.86% and 6.97%, the qualified rate and reseeding rate of the Longqingdao 3 were 89.12% and 7.46%, The sowing performance can meet the requirement of precision rice hill-direct-seeding. The research provided a theoretical reference for the improvement design of precision hill-direct-seeding seed-metering device for rice.

Abstract:The machine-harvested cotton was processed through multistage seed cotton cleaning and lint cleaning, and cotton fiber was damaged inevitably. With the balance of appearance quality and inherent quality, the research method and testing program for process optimization control of machine-harvested cotton processing technology were proposed. According to the latest cotton quality inspection standard, nine parameters optimization targets such as trash area, trash count, reflectance, yellowness, upper half mean length, length uniformity, short fiber index, micronaire and strength were determined, and global optimization goal for the maximum transaction price of lint processing products was established. Seven rotational speed variables of cleaning machines, including inclined seed cotton cleaners I and II, recovery seed cotton cleaner, upper cotton gin, stripper and stick cleaner, saw lint cleaners I and II were selected as optimized control variables, which had significant effect on cotton cleaning. Architecture model based on monitoring layer, control layer and equipment layer was adopted, and upgrading key equipment automation was completed. The data model between control targets and control variables was built by using central composite design of response surface methodology. Taking global optimization control goal as fitness evaluation function, genetic algorithm was proposed to calculate the multivariate data model solution. Seven rotational speeds were 495r/min, 484r/min, 727r/min, 472r/min, 1131r/min, 822r/min, 763r/min, respectively. The test results showed that the change rate of trash area for processed lint products was reduced by 7 percentage points, the change rate of upper half mean length was increased by 2 percentage points, and product quality was more stable. The suggested method guaranteed fiber quality effectively with reduction of impurity content.

Abstract:According to the deficiencies in uneven soil compaction and insufficient intensity in hilly region，the bidirectional profiling and strength adjustable press device was designed based on the hilly agricultural mechanical characteristics, which mainly consisted of profiling adjusting mechanism，strength adjusting mechanism and press wheel. The interaction model of soil and press wheel was established. Force analysis of press wheel was carried out to determine working process of press wheel. Force analysis of press device was carried out to determine the reasonable range of spring deformation (suppression of strength). The contrast test was done to verify the device performance of profiling, and the orthogonal tests were done to verify the hilly terrain repression wheel, soil interaction models along the correctness of draft force (activity-based costing) and ratio of root to shoot (crop growth state), and the factors affecting the changing rule of performance test. The effects of device under type of press wheel， intensity of the suppression and forward velocity were studied. In order to achieve the purpose of balancing the various indicators, the best combination was determined by using comprehensive weighted scoring method. The results of orthogonal tests of L9(34) showed that the primary sequence of factors was as following: press wheel, suppress strength and forward velocity, and the optimal combination was: rubber press wheel, spring deformation amount of 20mm and forward velocity of 1m/s. Under the conditions, the rate of draft force was 22.3N, and the ratio of root to cap was 0.271. The result of contrast test showed that profiling press device was good in ensuring the uniformity of soil compaction. The result provided valuable information for the design of press wheel of planter.

Abstract:Aiming to the bad performance of pricking hole with liquid fertilizer applicator for deep-into type, and explore the changing rule of dynamics of pricking hole mechanism with deformation elliptical gears in the working parameters, equation of gear pitch curves of pricking hole mechanism with deformation gears was built, the simulation software of kinematics analysis was compiled, which was written for pricking hole mechanism with deformation elliptical gears based on Visual Basic 6.0 development platform, some parameters like the semi-major axis, eccentricity ratio and deformation coefficient of deformation elliptical gears were adjusted, and the optimal parameters were obtained. Bench of dynamics test of pricking hole mechanism with deformation elliptical gears was also set up. Scheme of test design of rotation center composite was used, with speed of planet frame and forward speed of bench car as test factors, and torque of sun shaft and tension and pressure of spray fertilizer needle into the soil as the test optimizing index. The torque of sun shaft and tension and pressure of spray fertilizer needle into the soil were measured by using torque sensor, signal acquisition instrument and DASP-10 processing software on the test bench, the regression equation and diagram of response surface were obtained, experimental data was analyzed by using Design-Expert 8.0.10. Test results showed that when the speed of planet frame was 64.4r/min, the forward speed was 0.61m/s, the torque of sun shaft was 5.05N·m, tension and pressure of spray fertilizer needle was 20.03N, the dynamics performance of mechanism was optimal under above conditions. The test was verified by applying these parameters to validate its rationality. The research results can guarantee pricking hole mechanism to have a good pricking hole performance under many working parameters and provide theoretical reference for structure optimization design.

Abstract:The power consumption of tractor’s electrical components has a great effect on its economic performance, which was awfully neglected in the past. By matching the electrical components properly, and keeping its work condition in the economic zone of engine, the engine’s combustion efficiency can be improved greatly. The integrated virtual testing system for tractor electrical performance was designed, which aimed to meet the research requirements on the tractor power consumption test, electrical components match, etc. Firstly, the hardware selection was determined based on the requirement analysis of tractor electrical performance test. Then, the test system based on NI cRIO controller was designed, which can complete the synchronous acquisition of battery and generator terminal voltage and current, engine speed and tractor velocity, temperature, and so on. Consequently, the virtual software design of the test system was described in detail, including FPGA software, realtime software and PC data acquisition and analysis software. Finally, the field tests were conducted, which included the engine start test, the power consumption tests for each electrical component, and the electrical balance test for the whole tractor electrical circuit when the engine was started. According to the current accuracy comparison tests and tractor field tests, both the current samples accuracy and the system work function and reliability were validated. The research result provides an effective means to comprehensively evaluate and analyze the tractor electrical performance.

Abstract:Small-scale pellet mill has many advantages, such as small mass production, less energy and raw materials consumption and low costs. Recently many researches were focused on the pelleting experiments, but the lack of small-scale pellet feed machine had become a problem of the influence of different formulas and processing conditions on pellet feed quality. To solve the problem, a structure of small-scale pellet mill was designed, which consisted of ring die and its matching components, roller and its matching components, transmission mechanism, etc. The prototype was manufactured and the production experiment was conducted. The adjusting mechanism for the roller was located outside the chamber, so the gap between roller and ring die could be real-timely adjusted when the production was in process. The structure could ensure that the production of pellet feed would be non-stop. Based on elastic-plastic theory and continuum mechanics, the software Abaqus and its built-in Drucker-Prager Cap material model were used for the numerical simulation and analysis of the pelleting process. The simulation results showed that the gap between roller and ring die should be adjusted with the friction coefficient of raw materials;proper increase of raw materials’ friction coefficient could avoid internal sliding and energy consumption, which could help to improve the yield and quality of pellet feed. Some suckling pig feed formula was taken as raw material to be produced, and the performance indicators of the pelleting mill were determined. The experiment results showed that the moisture content was 13.53%, diameter of the pellet feed was 3mm, pellet durability index was 94.34%, hardness of pellet feed was 176.03N, and productivity of the pelleting mill was about 42kg/h. All the indexes met the design requirements, which could meet the production need of small-scale pellet mill. The design of the pelleting mill and experiment research provided reference for the pelleting technology and development of the similar equipments.

Abstract:A new rectangular bale multipack was designed to solve the difficulty of low efficiency, high costs and transportation inconvenience in the process of collecting rectangular bale. The rectangular bale multipack was composed of chassis, pickup, pushing bale device, raising bale device, pressuring line device and unloading bale device, etc. Based on EPEC2024 controller, the pump, motors and cylinders were drived to make some rectangular bales into one big rectangular bale. In operation, the rectangular bale multipack had the ability of collecting 12 rectangular bales at one time. The maximum driving speed of the rectangular bale multipack exceeded 20.5 km/h and the maximum hydraulic flow was 101.6 L/min. The field experiments for picking up rectangular bale and straw rectangular bale were carried out in Inner Mongolia and Liaoning Province, respectively. The test results showed that collecting bale rate and collecting bale productivity of the rectangular bale multipack was 89.5% and 12 bdl/h, respectively. Compared with artificial operation, the collecting bale efficiency was improved by 34.5%, meanwhile, the artificial costs and composite expenses were declined by 62.5% and 18.2%, respectively. The preparation cycle for long-distance transportation was also cut down. All of the works, including picking up and packing some rectangular bales were done by one operator driving the tractor simultaneously, and the rectangular bale multipack can meet reality needs.

Abstract:Straw fiber is a kind of huge renewable biological macromolecule material, and using crop straw as the raw material to manufacture plant fiber mulch is an ideal way of promoting comprehensive utilization of straw resource. Tensile strength of plant fiber mulch is a measure of damage caused by external stress. In order to accurately and effectively predict the tensile strength, reduce production cost and improve the utilization rate of raw materials, based on pilot-production line of plant fiber mulch, particle swarm optimization (PSO) used to optimize support vector machine regression (SVR) combined with the orthogonal test method (L25(56)) was proposed, namely, the PSO-SVR. The production processes variables were chosen, and the PSO-SVR model was established in Matlab 2011b. The input parameters affecting plant fiber mulch tensile strength through mechanism analysis were beating degree, dosage of wet strength agent, regulator, basis weight and mixture ratio;the evaluation index was tensice strength. The results were compared in terms of prediction accuracy with three prediction models respectively based on support vector machine regression (SVR), back propagation neural network regression (BP) and radial basis function neural network regression (RBF). The results obtained by using the PSO-SVR model showed that the mean square error was 0.117N2, the coefficient of determination was 0.915 and the root mean square error was 0.342N. The punishment factor and kernel parameter of SVR can select by PSO automatically. Compared with other intelligent algorithms, such as SVR, BP and RBF， PSO-SVR algorithm possessed superior applicability and stability. Therefore, this method can better reflect the actual tensile strength of plant fiber film, which can be used as a theoretical basis for the intelligent controlling under different process conditions.

Abstract:Taking the SPOT5 satellite images of Heilongjiang Province and national forest inventory data as data source, the image texture, spectral features and topographic information of the sample plots were obtained, forest information of sample plots survey data was extracted as the true value. Through multiple linear regression analysis, forest structural parameters (forest stand quadratic mean diameter, basal area, stand volume and species diversity index) estimation models were established by combination of texture, spectral features and topographic information as independent variables, so as to select the optimal texture feature generation window and the optimal forest structure parameter inversion model. The results indicated that the texture, spectral features of SPOT5 images and forest structure parameters had a strong correlation, and the 9×9 window was the optimal texture generation window;the accuracy of the model was greatly improved after introducing the topographic factor. The estimation model of tree species diversity index R2adj was more than 0.72, and stand volume estimation model was the optimal model with R2adj of 0.864 and root mean square error of 21.260m3/hm2. The study suggested that using high resolution satellite image texture, spectral and topographic features to estimate the forest structural parameters had good application prospect.

Abstract:It is meaningful to research the delineation method of permanent basic farmland on the county scale. The comprehensive model was presented to evaluate the farmland and delineate the border of permanent basic farmland. The hierarchy of the model was firstly introduced accounting for these factors such as natural resources, infrastructure development, social-economic condition and location condition. Then, as a case study, the model was used in Dingzhou City of Hebei Province and the comprehensive scores for the patches were produced. The farmland patches in Dingzhou City might be divided into four regions: priority protection region (PPR), key protection region (KPR), suitable control region (SCR) and further regulation region (FRR). The area of PPR was 28389.22hm2 with scores higher than 76.00. Besides, PPR was distributed mainly in surrounding area of the city and major towns and it was the important grain production base. The area of KPR was 39084.13hm2 with scores between 68.91 and 76.00. Besides, KPR was mainly distributed in Pangcun Town, Daluzhuang Town and Yangjiazhuang Town and it was the important construction area of permanent basic farmland. The area of SCR was 16831.95hm2 with scores between 60.00 and 68.91. Besides, SCR was distributed separately and the diversified land consolidation projects were needed to be implemented. The area of FRR was 5126.82hm2 with scores lower than 60.00. FRR was mainly distributed in west district, north district and Xizong Town and it was not suitable for delineating permanent basic farmland. These results would provide the scientific basis for delineation of permanent basic farmland and the relative basic farmland plans in Dingzhou City.

Abstract:To improve the connectivity of high standard prime farmland regions, on the basis of arable land comprehensive quality evaluation and the arable land connected network, a local farmland connectivity calculation formula was proposed to evaluate arable lands connectivity, and four-quadrant method was adopted to space couple farmland quality and connectivity. Firstly, arable land comprehensive quality evaluation system was built from natural quality, site environment and ecological quality by using the analytic hierarchy process. Secondly, on the basis of contiguous thresholds and contiguous rules, the arable land connected network and arable lands connectivity evaluation system was built. Finally, four-quadrant method was adopted to zone high standard prime farmland, which included prioritized construction area, important construction area and conditional construction area, and it can provide reference for the construction of high standard prime farmland. The results showed that the area for prioritized construction was 24803.45hm2, where the arable lands had better quality and higher connectivity; the area for important construction was 19688.77hm2 and 19538.64hm2 for conditional construction area, each region included three types of construction and each construction had different sequences. A global farmland connectivity calculation formula was also proposed. Compared with the method of accumulation area, the connectivity of prioritized construction area was improved by 15.55%, while the connectivity of conditional construction area was decreased by 37.82%, indicating that the method significantly improved the connectivity of high standard prime farmland construction area.

Abstract:The regional ecosystem service value of Haidian District in Beijing was estimated in the 500m×500m grid scale by using present regional land use data. The research area was divided into different types of sub-regions according to the distribution of ecosystem service values. The land use structure and landscape pattern of different sub-regions were analyzed through the software of GIS and FRAGSTAS. The results showed that the ecosystem service value of Haidian District was ranged from -2.35 million yuan to 2.08 million yuan, which was increased from the south to northwest. The land use structure and ecosystem service value were different in different sub-regions. The main land use types were urban green space in high value regions, cultivated land and forest land in mid value regions and construction land in low value regions. There were also large differences of landscape pattern index among different sub-regions of ecosystem service value. The fragmentation of the landscape pattern was gradually increased from low value regions to high value regions, indicating that the influence of human activities on the ecological environment was increased, and the disturbing of human activities on the landscape structure was also increased. The results of this research can provide a reference for the intensive evaluation of regional ecosystem service, and serve as a scientific basis for the structure adjustment, sustainable utilization of regional land and ecological landscape construction.

Abstract:Monitoring on heavy metal pollution and pollution degree of crops is a hot spot in hyperspectral remote sensing research. By conducting the potted-corn experiment stressed by copper, on the basis of the measured spectra and Cu2+ contents of corn leaves under Cu2+ stress with different concentrations, the research was carried out on the effective differentiating method of similar spectra according to the thinking that the corn leaves’spectra with different Cu2+ stress concentrations still have very high similarity and it is difficult to distinguish the different pollution degrees by using the traditional spectral measurement methods. The ED-T-DSGA spectral analysis model was proposed for spectral similarity measurement with the Euclidean distance (ED) and the tangent of spectral differential gradient angle (DSAG), which was proved to be feasible and effective in distinguishing the very small difference of extreme similarity spectra by comparing the traditional spectral measurement method, harmonic analysis (HA) technique and the results of spectral reconstruction of five HA decomposition times. Meanwhile, the ED-T-DSGA spectral analysis model can be used to measure spectral difference and monitor pollution degree of corn leaves stressed by different Cu2+concentrations. The experiment results showed that the greater the value of ED-T-DSGA spectral analysis model was, the greater the Cu2+ stress concentration was, which meant that corn was more seriously polluted by heavy metal copper. And some effective sub-band intervals such as the “yellow edge”, “red valley”, “red edge” and “near-peak B” were extracted by further study based on the ED-T-DSGA analysis model, these interval positions were the spectral responses of Cu2+ stress, the sensitive positions could be used as some favorable basis to monitor Cu2+ pollution degrees.

Abstract:With the development of 3D acquisition devices, 3D modeling method emerges in endlessly. In recent years, 3D reconstruction based on real data is focused on scanning and TOF imaging method. The main drawback of the former is that needs extensive man-machine interaction. The latter can transform a wide range of scene depth information into plant 3D point cloud data in a short time. Most plant reconstruction method based on TOF technology is center on brance structure, but for herbaceous plant, leaves are not easy to operate. So a 3D model reconstruction algorithm was presented based on depth information segmentation and clustering for potted and elevated strawberry. Firstly, the algorithm took discrete depth information as a significant reference standard for object segmentation while taking the depth-dimensional image as a global reference standard to extract discrete point cloud through depth stepping. Then, the algorithm used clustering algorithm based on density to filter out random noise, jump-edge noise as well as background noise. By applying Harris algorithm between color image and the intensity image, a robust registration result was got and an index relationship between point cloud and pixel points was found. Ultimately, 3D strawberry canopy morphology with full color information was reconstructed after following all those steps. Experimental results showed that the algorithm had achieved good effects on segmentation clustering and coloring for potted and elevated strawberry leaves. The accuracy of single-leaf length was around 93% while A-B line accuracy was close to 97%, which indicated that the reconstructed model accuracy met the requirements of phenotypic parameters extraction. The 3D model can provide a new strategy for picking robot in spatial structure research domain.

Abstract:In order to study blue ear epidemic early warning and monitoring method in large-scale pig farms, the non-contact ear automatic color detection method was proposed. Pig’s thermal infrared images and visual images were collected at the same time and the same viewing angle. Two pictures were used together to find the optimal scale factor of matching. By the optimal scale factor, pig ear root section can be found in visible image, and then the ear root central point can be confirmed. According to active shape model method, pig ear root central point was selected as the first feature point, the ear tip as 18th feature points, and both middle point of outlines as 9th and 26th feature points, and 34 pig ears outline feature points in all were selected by human-computer interaction. ASM search scope was defined in pig head region, thus pig ear outline could be extracted correctly. Then the extracted pig ear color was compared with the color of normal pig ears, the ear color detection accuracy could be above 77%, and it could be easily found whether there was the risk of blueear pig disease. The results showed that due to the limited search scope method, the pig ear contour could be extracted accurately, and it could be applied to auto ear color detection in swine house.

Abstract:The recognition of cows’ body parts is essential for providing accurate details of the cows’ shape, which is the fundamental prerequisite for locomotion scoring, posture detection and behavioral quantifications. The objective was to develop a robust depth feature in order to reduce the difficulty in building the classifier and detect cows’ body parts with higher accuracy. Therefore, a method for segmenting cows’ body parts was proposed, including the head, neck, body, forelimbs, hind limbs and tail, with high accuracy on the basis of depth image processing and machine learning. The local binary patterns of each pixel under several sampling radii were used as the features with which the filtering rules were designed, and a decision forest was trained and tested to classify the pixels into six groups. Furthermore, totally 288 depth images were captured from 30 cows;150 images were randomly selected to build three decision trees, and the rest images were used for testing. The results showed that when the number of sampling radii and training layers were 30 and 20, respectively, the recognition rate reached 95.15%. Among the cows’ body parts, the recognition rate of tail was 54.97%, and the minimum recognition rate of other parts was 89.22%. In some cases that tail was too close to trunk to segment tail from trunk by human marker, the decision trees recognized the tail successfully. The average recognition time for pixel were 0.38ms and 0.25ms, and the recognition time for cow target were 20.30s and 15.25s for the conventional method and new method, respectively. This LBP-based depth image feature was translation-invariant and rotation-invariant and had fewer parameters. The results showed that the new method proposed was more effective in recognizing small and complex structures of the cow target with higher accuracy. Compared with the typical depth image features, the new feature employed was capable of extracting the details of cows’ body and recognizing complex parts more accurately with fewer parameters and simple model.

Abstract:The greenhouse gases such as methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) were increased in atmospheric concentration since 1750, which attracted more and more attention regarding climate change. Agriculture activities contributed to the increase of greenhouse gas concentration in the atmosphere, resulting in high global warming potential, which was estimated to contribute about 47%~58% of the total anthropogenic emissions of CH4 and N2O. Film mulching is reported to be a significant agricultural factor which greatly affected greenhouse gas (GHG) emissions and the carbon footprint. The annual GHG emissions (CO2, CH4 and N2O) from a wheat-maize rotation system during 2014—2015 were monitored by using the static opaque chamber and gas chromatography technique in Guanzhong Plain of China. Four mulching treatments were no mulching (CK), semi-film mulching (BM), ridge-furrow planting with film mulching over ridge (LM) and whole film mulching (QM). Net global warming potential (NGWP) and carbon footprint were used to evaluate the effect of film mulching on GHG emissions and composition of carbon footprint production. The results showed that compared with CK, the BM, LM and QM treatments increased annual crop yield by 9.0%, 16.5% and 26.6%, respectively. Similarly, the BM, LM and QM treatments increased annual CO2 emission by 33.9%, 9.3% and 31.6% and annual N2O emission by 22.9%, 14.3% and 47.1%, respectively. However, annual CH4 emissions showed no significant difference compared with CK. In addition, NGWP was increased by 9.0%, 16.7% and 26.0%, respectively. The carbon footprint of LM and QM treatments was 33.2% and 21.9% lower than that of CK, while BM treatment showed no significant difference compared with CK. Compared with carbon footprint per unit crop yield of CK, that of BM treatment was increased by 16.3%, while that of LM treatment was decreased by 13.1%. Meanwhile, QM treatment showed no significant difference. Considering both the economic and environmental effects of different mulching treatments, ridge-furrow planting with film mulching over ridge in the wheat-maize rotation system was recommended for carbon sequestration and greenhouse gas reduction in Guanzhong Plain of China with the purposes of water saving and carbon sequestration.

Abstract:Under the premise that targets of the reservoir’s original flood control and water supply were unaffected, in order to reduce the influence of reservoirs on river ecosystems, in allusion to the situation that the scheduling results satisfied the constraint of minimum ecological flux rather than the appropriate ecological flux, a model to solve ecological scheduling of Nierji reservoir under the condition of incomplete ecological constraints was proposed. The model was based on the scheduling results of constraints of the minimum ecological flux, the solving method of non-sufficient ecologically constrained flux approached the constraint of appropriate ecological flux step by step, and by introducing relaxation variables, the firefly algorithm (FA) was used to optimize the scheduling process which led to the establishment of the relation curve between the degree of the ecological assurance and the generated energy and the confirmation of the optimal equilibrium point under the restriction of the non-sufficient ecological flux by the Tennant evaluation through comparing the Kmin with Kmax-1 methods. The results showed that according to the non-sufficient ecological constraint flux inquired by the used model, the ecological water consumption and the minimum ecological constraints could be increased by 4.415 billion m3, 3.655 billion m3, 5.596 billion m3, 4.626 billion m3, 3.790 billion m3 and 5.481 billion m3, respectively, in the six cases when compared with low flow years and normal years. It was indicated that there was still much room for ecological flow restriction, therefore, when the scheduling results satisfied the constraint of the minimum ecological flux rather than the appropriate ecological flux, it was inappropriate to select result of the constraint of the minimum ecological flux as the scheduling scheme;according to the established relation curve and Kmax-1 method, the degree of ecological guarantee of optimal scheduling scheme under six constraints were 60%, 80%, 40%, 60%, 70% and 70%, respectively and their generated energy were corresponded to 0.60657 billion kW·h, 0.60312 billion kW·h, 0.68513 billion kW·h, 0.66796 billion kW·h, 0.59682 billion kW·h and 0.67859 billion kW·h. In conclusion, the new scheduling model could effectively solve the problem of ecological scheduling under this kind of circumstance, improve the degree of ecological assurance, ensure certain economic benefits and provide a more reasonable scheduling approach for decision-makers and new ideas for these issues.

Abstract:To provide soil hydraulic parameters for simulating soil hydrological processes, classical statistics were used to characterize the spatial distribution of soil bulk density (BD) within different soil depths (0~10cm, 10~20cm and 20~40cm) along south to north transect of the Loess Plateau. Furthermore, the multiple stepwise regressions, pedotransfer functions and the first order autoregressive statespace models were applied to simulate the distribution of BD. The magnitude of BD variability in the 0~20cm soil layer was moderate according to the coefficient of variations, while the BD variability in the 20~40cm soil layer was weak. The key factors affecting the spatial distribution of BD differed in different soil depths. Soil organic carbon, clay and sand contents were the key factors in the 0~10cm soil layer;soil organic carbon content, clay and sand contents and precipitation were the key factors in the 10~20cm soil layer;while in the 20~40cm soil layer, clay and sand contents, precipitation and land use were the key factors to affect the spatial distribution of BD along south to north transect. State-space models were consistently more effective than multiple stepwise regression functions and pedotransfer functions for estimating spatial distribution of BD. State-space model that included clay and sand contents, precipitation and land use factors showed the best simulation result, and the combination of such variables explained 92.3% of the total variation of BD. State-space models were recommended for studying spatial relations between soil bulk density and other variables on the Loess Plateau.

Abstract:Groundwater monitoring is limited by practical conditions, and only limited monitoring results can be obtained when it is observed. As a kind of geostatistical interpolation method, cooperative Kriging (co-Kriging) method can effectively represent the transformation of discrete point-like information to planar continuous information. Dengkou County, a typical county in the arid region of Northwest China, was selected as the study area. The sampled data from 40 groundwater sampling sites in 2015 was selected as the main variable. And this data optimized by EnKF was used as the basic data of co-Kriging interpolation. The evapotranspiration results and NDVI data were selected as the covariates. Co-Kriging interpolation was carried out by using the sampled data from 40 groundwater sampling sites in August, 2015, as the main variable, which were optimized by EnKF, and the evapotranspiration results and NDVI data were used as the covariates. Meanwhile, the results of coKriging interpolation without using EnKF model and Kriging interpolation optimized by EnKF model were used to verify the accuracy. The results showed that the spatial distribution trend of groundwater depth was basically the same at large scale, the value in the southern desert region was higher, and the spatial distribution showed obvious geography regularity. The most significant improvement was achieved with EnKF model. Based on this improvement, the mean error, root mean square error and mean standard error were all better than those without assimilation, with the mean error of 0.2705m. Compared with the ordinary Kriging interpolation method, co-Kriging model took the synergistic effect of evapotranspiration and NDVI into consideration, and the precision was obviously improved. The mean error was decreased by 0.4097m, the root mean square error was decreased by 0.0784m and the mean standard error was decreased by 1.0167m. This study can provide a scientific basis for spatial visualization simulation and reasonable management of water resources in arid areas.

Abstract:In order to construct the high spatial-temporal dataset of evapotranspiration (ET), the Landsat and MODIS data were used to achieve spatial downscaling of ET by using the enhanced spatial and temporal adaptive reflectance fusion model (ESTARFM). The result of data fusion was evaluated by field ET output from root zone water balance model. According to crop planting structure information from 2000 to 2015 in the study area, the water consumption of different crops was exacted during their growth and non-growth periods. Based on the fusion ET, the interannual variation of total agricultural water consumption was analyzed since the implement of water-saving project in large irrigation district. The result showed that the process of fusion ET was more consistent with ET output from water balance. In the correlation analysis of water balance and fusion ET, the determination coefficients (R2) of maize, wheat and sunflower reached 0.85, 0.79 and 0.82, respectively. During the growth period, the root mean square errors (RMSE) of maize (May to October), wheat (April to October) and sunflower (June to October) were lower than 0.70mm/d, the mean absolute error (MAD) was all lower than 0.75mm/d, and the relative error (RE) was all less than 16%. On the spatial scale, the spatial characteristics of fusion results were consistent with the Landsat ET. The correlation coefficients of July 23, August 24 and September 1 reached 0.85, 0.81 and 0.77, the mean values of the differences were 0.24mm, 0.19mm and 0.22mm, and the standard deviations were 0.81mm, 0.72mm and 0.61mm, respectively. The high resolution ET based on ESTARFM fusion algorithm was reliable and had good fusion precision. The water consumption of different crops varied greatly both in the growth period and non-growth period. During the growth period, the maximum water consumption was 637mm for interplanting (April to October), followed by maize and sunflower, which were 598mm (May to October) and 502mm (June to October), respectively, the minimum water consumption of wheat was 412mm (April to July). During the non-growth period, wheat (August to October) had the highest water consumption with an annual average of 214mm, and those of maize (April) and sunflower (April to May) were 42mm and 128mm, respectively. Due to the difference of average annual water consumption of different crops was not significant during April to October, the variation of total water consumption for different crops was varied with the changes of crop acreage.

Abstract:Critical hydraulic characteristics of soil detachability are essential factors for soil erosion predicting. There is still insufficient knowledge on key factors and governing mechanism of soil detachability, especially for various near-surface soil water conditions. The typical eroded yellow soil area in the upper and middle Yangtze River was taken as the research area. In order to illustrate the response of critical condition of soil detachment under different subsurface soil water conditions, scour flume was used to measure hydrodynamics parameters. Five antecedent soil moisture contents (5%~23%) and five slope gradients (1.0°~10.0°) were designed. Results showed that critical flow velocity, flow depth and flow pattern of soil detachment all showed power function decreasing trends with the increase of slope gradient and antecedent soil moisture content. When the slope gradient was smaller than 5.0°, critical hydrodynamics parameters of soil detachment were influenced by coupling effects of slope gradient and antecedent soil moisture content;otherwise, it would be mainly influenced by slope gradient. It was also proposed that the simplified power function equation could be used accurately when slope gradient was larger than 5.0°. Most of the flow patterns belonged to laminar flow and subcritical flow. The slope gradient and antecedent soil moisture content played an important role in the overland flow Darcy-Weisbach friction factor. When Reynolds number and critical discharge per unit width were increased, the Darcy-Weisbach friction factor was decreased as power function.

Abstract:In order to investigate the impact factors and mechanism of high water use efficiency under water-saving irrigation technology, experiment with two irrigation treatments was carried out in rice field, including flooding irrigation (FI) and nonflooding controlled irrigation (NFI). In the FI rice fields, a depth of 3~5cm standing water was always maintained after transplantation, except during the drainage period in later tillering and yellow maturity stages. In the NFI rice fields, the pond water was kept between 5mm and 25mm during the first 7~8d after transplantation at the regreening stage. At other stages, irrigation was applied only to keep the soil moist and flooding was avoided;standing water up to 5cm depth in NFI fields was maintained for less than 5d just to meet the requirements for the pesticide or fertilizer application. The relationships between stomatal regulation, environmental factors and leaf water use efficiency were studied, meanwhile, the regression equations of leaf water use efficiency were established, and the path analysis method was applied to analyze the impact factors. The results showed that there was a quadratic regression equation between stomatal conductance (Gs) and transpiration rate (Tr), photosynthetic rate (Pn), leaf water use efficiency (LWUE) under NFI treatment, to maintain high LWUE, optimal stomatal conductance was 0.54mol/(m2·s), and the peak value was appeared earlier than that of FI treatment. There was also a quadratic regression equation between LWUE and environmental factors, including air temperature (Ta), leaf temperature (Tl), leaf-air temperature difference (ΔT) , air CO2 concentration (Ca) and photosynthesis available radiation (Par). While LWUE was negatively related to intercellular CO2 concentration (Ci) and positively correlated with soil moisture (θ), the relationship between LWUE and relative humidity (Rh) was exponential. The temperature factors composed of Ta, Tl and ΔT contributed 39.19% to LWUE，while the CO2 concentration factors composed of Ca and Ci contributed 17.81%, the vapor factor composed of Rh and θ contributed 17.81%, and the light factor composed of Par contributed 9.01%. Furthermore, the regression equation of LWUE was established, and the path analysis method was applied to analyze the impact factors, as for the NFI treatment, it was found that Par, Gs and θ may not be the main influence factors, the sensitive indicators affecting the LWUE were Ci, Tl and Rh.

Abstract:Aiming to have insights into characteristics of soil moisture transfer of porous ceramic infiltration irrigation, soil moisture transfer experiment was conducted by using porous ceramic emitter, of which the working head was 0m, meanwhile, subsurface drip irrigation tape with working head of 10m was used to carry out a control test. The comparisons of cumulative infiltration, emitter discharge, wetting soil characteristic and change of soil water content of two different irrigation methods were made. The results indicated that when the irrigation time was the same, the cumulative infiltration, wetting front and wetting zone sectional area of porous ceramic infiltration irrigation were less than those of subsurface drip irrigation. The discharge of porous ceramic infiltration irrigation was decreased gradually with the increase of time, which was closed to 0L/h at last, in contrast, the discharge of subsurface drip irrigation was relatively stable. In the late experimental period, soil water contents in the wetting zone of porous ceramic infiltration irrigation were changed slightly. While water contents of subsurface irrigation were increased continuously, and then they got decreased after stopping irrigation because of soil water redistribution. Because porous ceramic infiltration irrigation was a continuous irrigation method, thus it could provide a constant soil moisture environment for crops. But subsurface drip irrigation was a passive and intermittent irrigation method, and soil moisture environment for crops was alternate drying-wetting. The present study provided valuable information for the popularization and application of porous ceramic infiltration irrigation.

Abstract:In view of the present measurement of soil compactness based on the cone index, eliminating the influence of soil friction on compactness measuring is impossible.It needs to ensure sensor is inserted into the soil at constant speed, thus it is difficult to use and the accuracy is not high. In order to improve the real-time measurement precision and maneuverability of soil compactness, a real-time soil compactness detection sensor was designed based on the cone index, and the synchronous measurement of acceleration was realized, which eliminated the error caused by different speed in the process of the metal rod inserting into soil, as well as improved soil compactness measuring precision. Homemade sensor had good static characteristics and dynamic characteristics through a large number of test. Measuring range was 0~7800kPa, sensibility was 0.041896, the stability of the standard deviation was 5kPa, measuring accuracy was ±0.02%FS, overshoot was 7.81%, and transient time was 0.632s. Compared with SC-900 soil compactness meter of the United States, its accuracy of the linear fitting coefficient of decision reached more than 0.96. The results showed that the homemade soil compactness sensor and SC-900 soil compactness meter had consistency of performance in the actual measurement, and homemade soil compactness sensor was more convenient and cheaper.

Abstract:Pointing at the main problems existing in the utilization of point scale in soil moisture measurement, a linear scale measurement method was put forward and a sensor system of soil profile moisture information measurement was designed based on standing wave ratio method. With the help of a high frequency electromagnetic field simulation software HFSS and vector network analyzer, electric field distribution and impedance characteristics of sensor ring probe were analyzed and studied to determine the adaptation and sensitive areas of the ring probe. Two kinds of soil in different textures were taken as experimental samples, the output and the corresponding measured value of soil moisture sensors were executed polynomial fitting, and the results showed that the determination coefficient was above 0.99 and the steady and dynamic performances of sensors could satisfy the requirement of soil profile moisture measurement. The experiments of multi-layer moisture through the soil column showed the system could meet the soil profile moisture real-time measurements demand in linear scale and it had high measurement precision and stability. Meanwhile, the system was satisfied with needs of practical application and it had high application promotion value.

Abstract:The cucumber of solar greenhouse was selected to study the effect of biochar of corn straw on fungal abundance of rhizosphere soil and root growth of cucumber in fruiting period. The influence mechanism was found by the test. In the test, treatments were amounts of 20t/hm2, 40t/hm2 and 60t/hm2 of biochar which were respectively applied to the soil of solar greenhouse. The results showed that root number, root volume and root activity were improved in various degrees, the fungal abundances of Ascomycota, Zygomycota were increased significantly, and the fungal abundances of Basidiomycota, Chytridiomycota and Glomeromycota were promoted but the proportion of hybrid bacterium was reduced greatly, when the amount of biochar was 20～60t/hm2 in fruiting period of cucumber. The results also showed that the fungal abundances of Incertae sedis 27, Chaetomiaceae, Microascaceae, Lasiosphaeriaceae, Pseudeurotiaceae, Onygenaceae, Gymnoascaceae, Nectriaceae, Incertae sedis 3, Cephalothecaceae, Coniochaetaceae, Mortierellaceae, Glomeraceae, Bolbitiaceae and Spizellomycetaceae were improved by the application of biochar. Results showed that the effect of biochar on promoting root growth was more obvious for the fungi of Incertae sedis 27, Chaetomiaceae, Pseudeurotiaceae, Cephalothecaceae and Mortierellaceae, and these fungi promoted the root growth of cucumber by means of organizing in the root, promoting root to absorb nutrient, increasing organic matter and nutrient content, and promoting the decomposition of organic material. By comprehensive comparison, the effect of application rate of 20t/hm2 of biochar was better than those of other treatments, and the treatment of 20t/hm2 significantly improved the root number, root volume and root activity by 20.52%, 50.73% and 16.11%, respectively, compared with the test control in fruiting period of cucumber.

Abstract:Pyrolysis is a relatively simple, inexpensive, and robust thermochemical technology for transforming biomass into bio-oil, biochar and syngas. While the intention of slow pyrolysis is to produce mainly charcoal, fast pyrolysis is meant to convert biomass to a maximum quantity of liquids (bio-oil). Biochar can be used with existing infrastructure as a replacement for pulverized coal, bio-oil can be used as a fuel in existing industrial boilers. The pyrolysis of sawdust contains volatile bio-oil and non-condensing gas, so the condensation characteristics are different from those of other simple mixture. Based on the test system of biomass pyrolysis volatile matter condensation characteristic parameter, the experiment of condensation characteristics of pyrolysis volatile was carried out at 450℃, 550℃ and 650℃. The condensation characteristics of volatile matter produced at different pyrolysis temperatures were tested, and the heat transfer coefficient, the thermal resistance and thickness of condensation liquid film were calculated. Based on the one-dimensional heat transfer characteristics of liquid condensation, the condensate film formation process had three stages: formation, accumulation and flow of liquid film. The results showed that the first stage condensation heat transfer coefficient was decreased with the increase of temperature, biomass volatile surface heat transfer coefficient at 450℃ was the highest，which was 671.02Ｗ/（m2·K）;with the increase of temperature, the heat transfer coefficient of the second stage was increased first and then decreased, biomass volatile surface heat transfer coefficient at 550℃ was the highest, which was 1.484×105Ｗ/（m2·K）. According to the experimental value and the hypothesis of condensate film, in the film formation and accumulation stage, the film thickness was gradually increased and the thermal resistance was decreased;early in the liquid film flow stage, with the decrease of the film thickness, the thermal resistance was decreased;in the steady flow stage, resistance was remained stable. The research result can provide reference for the on-line collection of bio-oil and the design of bio-oil condenser in continuous pyrolysis equipment.

Abstract:With the increasing depletion of fossil energy, people pay more and more attention to renewable energy. Biomass energy is considered to be the most potential energy, which is a research hotpoint for its cleanness, efficiency and safety. The development and utilization of biomass energy plays an important role in achieving sustainable development, improving the living environment and reducing carbon dioxide. Owing to the flourishing pore structure, biochar as a main product of biomass conversion has been widely used in the fields of adsorption separation, catalytic carrier and fuel and so on. The biochar prepared from Camellia oleifera shell pyrolysis and adhesive as raw materials was molded by using universal testing machine. By analyzing the compressive strength, relax density and specific energy consumption of molding fuel, the effects of different adhesives on physical quality of molding fuel were made sure. The influence of molding pressure, temperature, moisture content and lignin content was studied with lignin as molding fuel adhesive. The results showed that the fuel quality was the best at molding pressure of 6kN, molding temperature of 80~100℃, moisture content of 20% and lignin content of 8%~9%. Scanning electron microscopy (SEM) was used to study the microstructure of the fuel. The results showed that lignin can promote the formation of carbon powder particles, the structure of the fuel is complete and the surface is smooth. The combustion characteristics and kinetics of the fuel were studied by thermogravimetric analysis. The results showed that the combustion process included four periods: the dehydration stage of the raw material, the precipitation and combustion of volatile components, the combustion stage of the fixed carbon and the burnout stage, and the ignition temperature and burnout temperature was 356.9℃ and 553.3℃, respectively. The volatile combustion was a first order reaction, and the fixed carbon combustion was a two stage reaction. The significance of the research was to provide theoretical basis for the preparation of biomass carbon fuel which was easy to transport and storage.

Abstract:With the aim to study the performance regulation and mechanism of different biochar-based biomasses, cellulose, hemicellulose and lignin were used as the raw materials to prepare biochar by pyrolysis in vacuum atmosphere furnace. The results manifested that the pyrolysis temperature of cellulose and hemicellulose ranged from 300℃ to 500℃, and the yields of biochar decreased from 35.38% (cellulose), 46.28% (hemicellulose) to 20.93%, 29.40%, respectively. Meanwhile, the pyrolysis temperature range of lignin was 300~600℃, and the yields of biochar decreased from 81.22% to 51.53%. Moreover, the effect of pyrolysis temperature on C, H, O and N contents of prepared biochar were similar in the three feedstocks. The content of C raised up gradually according to the temperature increase, while the contents of H, O, N decreased gradually. Detailly, the content of C increased from 69.42%, 72.92%, 54.75% to 96.39%, 77.26%, 67.97% for cellulose, hemicellulose and lignin, respectively. The effect of pyrolysis temperature on the content of ash, volatile, fixed carbon and the calorific value was basically the same in the three feedstocks. The volatile relatively decreased, and the ash, fixed carbon and calorific value increased gradually. Specifically, the volatile from the cellulose, hemicellulose and lignin fell to 7.63%, 5.52%, 14.41% from 50.67%, 44.89%, 39.99%, respectively. The fixed carbon increased from 47.95%, 55.03%, 35.41% to 90.18%, 94.11%, 53.70%, respectively. The calorific value rose to 34602.52kJ/kg, 33965.15kJ/kg, 24142.62kJ/kg from 25652.58kJ/kg, 26681.81kJ/kg, 21173.29kJ/kg, respectively. The significant effect of pyrolysis temperature on the specific surface area and pore size distribution of the prepared biochar was observed for lignin, however, insignificant effect was shown for cellulose and hemicellulose. The optimal surface area and pore volume of the biochar produced from cellulose and hemicellulose was obtained at 500℃, and the lignin was at 600℃. Besides, when the pyrolysis temperature was at 500℃, the iodine adsorption value of the biochar from cellulose and hemicellulose reached their respective maximum values at 422.46mg/g and 115.06mg/g. Meanwhile, at the pyrolysis temperature of 600℃, the iodine adsorption value of the biochar from lignin reached the maximum point of 460.35mg/g.

Abstract:Based on niche-fitness model, the suitability to habitat conditions of crops under four patterns was evaluated in order to reveal the optimal intercropping pattern of lettuce. And the four patterns were intercropping of lettuce with Chinese cabbage, radish, pea seedling and coriander, respectively. The niche-fitness values of intercropping patterns of lettuce with Chinese cabbage, radish and pea seedling were higher and closer, which showed that the habitat conditions of the three patterns can meet the needs of crops and the habitat conditions were more suitable for their growth. Then TOPSIS model was used to optimize the evaluation results. The relative approaching degrees of the three intercropping patterns with the ideal scheme were 0.557, 0.800 and 0.265, respectively. It was showed that the intercropping pattern of lettuce with radish was relatively close to the ideal scheme, which meant that the intercropping pattern of lettuce with radish was the best pattern among the four intercropping patterns. Considering the actual physiological indexes, it can be drawn that the intercropping pattern of lettuce with radish not only had better effect on the growth of aerosol cultured lettuce, but also had better effect on reducing the nitrate content in lettuce leaves. The combination of niche-fitness model and TOPSIS model had a certain practical significance and it can be used for the optimal selection of different intercropping patterns of lettuce. Limiting factor model was used to analyze, and the results showed that the limiting factor of the intercropping pattern of lettuce with radish was the content of potassium in nutrient solution. The results provided reference for the quantitative analysis of optimization of intercropping patterns.

Abstract:In order to investigate the characteristics of temperature decreasing of mashed potatoes without packages during freezing in an air blast freezer，a three-dimensional unsteady numerical model was established to simulate the freezing process of mashed potatoes. According to the thermo-physical properties of mashed potato, the process of the temperature decreasing during freezing was simulated by Fluent，after which the airflow information in the container was obtained．A test was done to verify the accuracy of the model，and it was found that the simulation values and test values were in good agreement，the maximum temperature difference between the test data and simulation result was 7.1K and the relative error of freezing time was 3.9%. After that，two design parameters (air velocity and air temperature) which would affect the freezing process were analyzed．Improving the air velocity can shorten the time of freezing but would improve the maximum temperature difference between the mashed potato’s core and edge. The variation coefficient of temperature among mashed potatoes was firstly increased and then decreased with the increase of air velocity, and it was minimum when the air velocity was 6m/s. When the air velocity was bigger than 6m/s，the freezing rate trended to be steady along with the growing of air velocity. Reducing the air temperature can effectively improve the temperature decreasing of mashed potatoes during freezing but also would improve the variation coefficient of temperature among mashed potatoes. The results reviewed some characteristics of the freezing of mashed potatoes without packages in an air blast freezer, which can provide a reference value for the optimization of the equipments and technologies for the freezing of foodstuffs．

Abstract:In order to achieve rapid non-destructive identification of apple varieties, the methodology of near-infrared hyperspectral imaging on identification of apple varieties was investigated. Near infrared hyperspectral images with wavelength from 865~1711nm of total 90 sample fruits were collected from three different varieties (“Jonagold”, “Fuji” and “Qinguan” apples), and hyperspectral image area of the apple was selected as a region of interest (ROI). Reflection intensity data of the average reflex spectrum were extracted with resolution rate of 2.8nm, then they were calculated with K-nearest neighbor (KNN) and the support vector machine (SVM) methods, respectively, which were checked with 5-fold cross-validation method. The results showed that the hyperspectral images of three varieties of apples all became clear within wavelength of 941~1602nm. Among ten distance-types’ judgment of KNN with average reflection intensity at 200 wavelength-points, the identification accuracy of Chebychev, Euclidean and Minkowski reached the highest of 100% when the parameter K was set at 3 or 5. While using the support vector machine-radial basis function (SVM-RBF) model, the accuracy rate reached above 92% when the value of γ fell within 2-8～1. The highest recognition rate of this model reached 96.67% when γ was set at 2-5 and C took the value of 16 amd 32 at the same time. The results demonstrated that near-infrared hyperspectral imaging in combination with KNN was excellent and reliable for the rapid identification of apple varieties. This method could provide reference for identifying apple varieties in production.

Abstract:Yak (Bos grunniens) lives at plateau area of more than 3500 altitude meter, in this case, yak still maintains normal physiological activity. Besides, yak meat is rich in protein and low in fat, which does not contain anabolic steroids. Proteomics research with bioinformatics approach combined with the established two dimensional electrophoresis (2DE) platforms was studied by comparing yak with beef cattle muscle. Aiming to illustrate the causes and pathway of different meat qualities in yak and beef cattle, establish the optimal 2DE system and analyze protein bioinformatics pathways, different lysis buffer components, isoelectric focusing procedures and staining methods were studied by using longissimus dorsi muscle of yak. Proteomic profiling by 2DE and mass spectrometry identified 19 proteins that were differentially expressed in longissimus dorsi muscle of yak and beef cattle. Then the identified proteins were analyzed by gene ontology (GO) annotations and Kyoto encyclopedia of genes and genomes (KEGG) pathway. Results showed that the optimal protein extraction methods were lysis buffer component II, progressive fast boosting program and improved coomassie blue staining method. And protein spots in yak and beef cattle were 553 and 479, respectively. Totally 19 protein spots exhibiting a teo fold or more intensity difference in the meantime associated with 5% statistical significance (P<0.05) were considered differentially abundant. The differentially abundant proteins between yak and beef cattle could be divided into three main functional categories: metabolism proteins, structure proteins and stress proteins. The method of GO annotation provided three detailed and structured terms that included cellular component, molecular function and biological process. The differentially expressed proteins in yak and beef cattle muscle were concentrated in cellular processes, carbohydrate metabolism, genetic information processing and energy metabolism pathways by KEGG pathway analysis. In conclusion, the research result demonstrated the functions of identified proteins and provided a more detailed molecular view of the processes behind meat quality in yak and beef cattle.

Abstract:Garlic is one of the species in onion genus, which has been used as both a flavoring agent and a complementary medicine. Although garlic has many active components that contribute to its health benefits, including allicin and its derivatives, consumption of unprocessed raw garlic is limited due to its characteristic odor, taste and tendency to cause stomach upset. Aged black garlic was prepared through natural fermentation of whole garlic at controlled high temperature and humidity, a process that resulted in black cloves. Aiming to obtain a non-fermented black garlic with low cost of ownership, which combined the steaming process with roasting process. The influences of steaming temperature, steaming time, roasting temperature and roasting time on preparation process for black garlic were investigated. The optimum processing parameters for the preparation of black garlic were determined by combined use of single factor and orthogonal experiments. The results showed that the optimal combination was steaming temperature of 127℃, steaming time of 70min, roasting temperature of 95℃ and roasting time of 6.5h. Under the optimum conditions, the black garlic had total phenols of 11.15mg/g, moisture of 27.41%, reducing sugar of 7.87g/(100g) and total acid of 36.09g/kg, reducing capacity of black garlic was more than 1.4 times of that of vitamin C in the 0.06~0.18mg/mL concentration range. This showed black garlic possessed strong antioxidant capacity. Compared with the fermentation process, the research significantly shortened the preparation time of black garlic, improved production efficiency, reduced energy consumption, provided technical basis for the development and utilization of functional garlic products.

Abstract:The rapid prosperity of automotive market in China poses serious environmental problems. Therefore, combustion emissions such as NOx and soot draw much attention in recent years. However, in addition to them, fuel evaporation emissions account for large proportion of pollution from automobiles. The fuel evaporation control system in the gasolineengine vehicle effectively inhibits the fuel vapor emission, which is beneficial to both pollution reduction and improvement of heat efficiency. Solenoid valve is one of the key parts in the fuel evaporation control system. It can accurately control the mass of gasoline vapor which strip out from the carbon canister by opening or closing the solenoid valve and ensure the smooth operation of the gasoline engine. Dynamic response characteristics of the solenoid valve have an important influence on the capacity of inhaling gasoline vapor into the intake manifold, thereby it attracts much attention. Actually, due to advantages such as structural simplicity, rapid action, low manufacturing cost and low energy consumption, solenoid valves are widely used in machinery, vehicle, aerospace and other industries. The effects of coil number of turns, wire diameter, core materials and armature mass on the response behavior, impact noise and energy consumption were explored by means of the software Ansoft Maxwell and orthogonal design method. Finally, optimization on the integrated performance of the solenoid valve was achieved to get the best comprehensive performance.

Abstract:Effects of diluent gases composition on ignition delays of dimethyl ether (DME) were investigated at compressed pressure of 1.5MPa, compressed temperature from 670K to 795K and equivalence ratio of 1 by using a rapid compression machine (RCM). The diluent gases considered were nitrogen (N2), mixture of N2 and argon (Ar) at mole ratio of 50% to 50% and mixture of Ar and carbon dioxide (CO2) at mole ratio of 61.2% to 38.8%. The simulation study was performed over a wider temperature range based on CHMKIN-PRO software. The results showed that diluent gases composition had little impact on the first-stage ignition delay. However, significant differences in the total ignition delay were observed, especially in the negative temperature coefficient (NTC) region. Compared with N2, mixture of N2 and Ar decreased the total ignition delay by 30%. The chemical effect of diluent gases composition on the first-stage and total ignition delays was negligible. The thermal effect was dominant factor in the low temperature and NTC regions, however, the chemical effect of CO2 enhanced and exceeded the thermal effect in the temperature region beyond the NTC region. With the increase of N2 dilution ratio, the first-stage ignition delay was slightly increased, while a significant increase in the total ignition delay was observed. Moreover, the NTC behavior of total ignition delay was noted to become more pronounced at high N2 dilution ratio.

Abstract:Fuel spray atomization strongly affected engine economic performance and emissions, which in turn was significantly influenced by nozzle cavitation phenomenon with the high injection pressure in diesel and GDI engine. Aiming to study the influence of noncondensable gases and turbulent pressure fluctuations on modeling of nozzle cavitation, Schnerr and Sauer cavitation model and Singhal cavitation model were used to model nozzle cavitation, which were both coupled with homogeneous equilibrium multiphase model and realizable k-ε turbulence model. Then, the Singhal cavitation model was used to model nozzle cavitation with homogeneous equilibrium model and different turbulence models. The comparison of simulation results and experimental results showed that noncondensable gases and turbulent pressure fluctuations had significant impact on modeling nozzle cavitation. The simulation result ignoring noncondensable gases and turbulent pressure fluctuations seriously underestimated the volume fraction of gas phase in nozzle, which was just 42% of the experimental results, while the volume fraction of gas phase calculated by the one considering turbulent pressure fluctuations and noncondensable gases agreed well with experimental results, which was 96% of the experimental results. The results indicated that considering noncondensable gases and turbulent pressure fluctuations would improve accuracy of nozzle cavitation simulation. The calculated gas phase considering noncondensable gases and turbulent pressure fluctuations was diffused to some extent at the end of gas phase region, which was caused by the expansion of noncondensable gases in fluid. Turbulence viscosity slightly affected the distribution of gas phase by affecting the velocity and pressure of fluid.

Abstract:Based on the theories of linear quadratic regulator (LQR) control and linear matrix inequality (LMI), a scheme of discrete-time optimal preview position control algorithm for automotive electronic throttle control (ETC) system was proposed. The presented throttle valve position tracking control algorithm consisted of the state-feedback control, discrete integrator, and preview feed-forward control. The closed-loop controller was realized by only utilizing a low-cost sliding potentiometer which was used to measure the angle position of the throttle valve. To track the position of automotive electronic throttle valve, the discrete-time state space model was firstly established for the automotive ETC system. Then, the augmented error system which contained future position reference information was built by using the state transformation method instead of the traditional difference method, which helped to simplify the structure of the augmented error system. In simulations, the physical parameters uncertainty and external disturbance torque of the real automotive electronic throttle control system were also considered, and the simulation results were verified by bench tests for throttle through utilization of the rapid control prototyping (RCP) technology. Both simulation and test results demonstrated that the proposed discrete-time optimal preview position control algorithm was able to effectively improve the transient performance and robustness of the ETC system while guaranteeing the tracking accuracy. Hence, the application of the presented control scheme on the ETC system can further improve the fuel economy, dynamic and exhaust performance of gasoline engine.

Abstract:In case of the difficulty in modeling for exoskeleton robot, an adaptive fuzzy logic control was presented to directly approximate the equivalent control without estimating the unknown parameters in advance. And an adaptive law in controller was designed to adjust its parameters according to parameter changes of the control system. In order to decrease the steady-state error and prevent from the integrator windup, a new nonlinear saturation function derived from quasi-natural potential function was designed to improve the performance of traditional integral sliding mode control. When the error beyond a boundary layer, the integral action was restricted by adjusting factor to avoid the large overshoot and long adjustment time. When the error was small, the integral action was completed so as to reduce the steady-state error and improve the robustness. The stability of the proposed controller was proved by using Lyapunov method. Furthermore, the chattering of sliding mode control was alleviated by simplifying the fuzzy control instead of switching function without deteriorating the system reliability and robustness. Finally, without acknowledging the model parameters of hydraulic-driven exoskeleton robot system, experiments were implemented to demonstrate the robustness and effectiveness of the method. And the results showed that the control output can follow the reference position signal quickly and smoothly with anti-interference ability.

Abstract:In order to improve the atomizing performance and decrease the consumption, the effect of air flow and water flow on the atomizing characteristics of twin-fluid impact nozzle was researched, the twin-fluid atomizing flow field was tested under different working conditions by an open atomizing test bench which was based on phase Doppler particle analyzer (PDPA). The atomizing characteristics which included spray cone angle, atomizing range, droplets diameter distribution, droplets velocity distribution and droplets numbers distribution were analyzed systematically according to the test results. It could be concluded from the test results, with the increase of air flow and decrease of water flow, the spray cone angle was increased remarkably, the droplets Sauter mean diameter (SMD), droplets velocity and droplets numbers were decreased, but the atomizing range showed an increasing trend with the increase of air flow and water flow. The distributions of droplets SMD, droplets velocity and droplets numbers were increased along the axial direction. Moreover, the distribution of droplets SMD was increased while the droplets velocity and droplets numbers were increased firstly and then decreased along the radial direction. Furthermore, the turbulence and hedging in the region between the nozzle exit and vibrating head were affected obviously by the air flow and water flow, and then the atomizing characteristics was markedly influenced. The air flow and water flow were decreased by 15.79% and 12.50%, respectively, after optimization when they were 0.8m3/h and 35L/h, meanwhile, the SMD was decreased by 21.50%, the atomizing range was increased by 10.26%, the droplets velocity and droplets numbers were increased by 39.08% and 61.54%, and it can be concluded that the atomizing performance was improved and the consumption of the nozzle was decreased.

Abstract:Deform-X flexure hinge was designed, and its equivalent stiffness was analyzed by using differential methods, and the theoretical calculation formula of the equivalent stiffness of Deform-X flexure hinge was derived. Through theoretical analysis and ABAQUS simulation analysis of Deform-X flexure hinge in a size, the correctness of calculation formula of the equivalent stiffness of Deform-X flexure hinge was verified. By comparing the performance of X-shaped flexure hinge with the same shape and size as the Deform-X flexure hinge, the bending deflection angle of the Deform-X flexure hinge was about three times of that of the X-shaped flexible hinge under the same torque. Bending failure analysis of X-shaped flexure hinge and Deform-X flexure hinge was carried out, and the results showed that the available using range of Deform-X flexure hinge was wider than that of X-shaped flexure hinge. The four-bar mechanism model based on Deform-X flexure hinge was manufactured. The test and simulation analysis showed that the Deform-X flexure hinge can realize the expected deformation. In addition, the four-bar mechanism model based on X-shaped flexure hinge was established in ABAQUS. Through the comparative simulation analysis, in the case of the same size, the bend deformation performance of four-bar mechanism based on Deform-X flexure hinge was better than that of four-bar mechanism based on X-shaped flexure hinge.

Abstract:Exechon parallel kinematic machine (PKM) has been applied to machining, assembling and aerospace industries due to its high rigidity and high dynamics. However, its rotational ability is comparatively weak. In order to improve the rotational ability of the Exechon PKM, an Exe-Variant PKM was proposed whose topology was a 2RPU&1RPS parallel mechanism. And the mechanical structure of the proposed Exe-Variant PKM was designed. In order to achieve a thorough understanding of stiffness characteristics of the Exe-Variant PKM, the stiffness model of the parallel module was designed by substructure synthesis technique. According to its structure feature, the Exe-Variant PKM was divided into several subsystems, including a moving platform subsystem, three limb subsystems and a fixed base subsystem. Meanwhile, the elasticity of joints and limbs was considered. Based on the proposed stiffness model, the stiffness distributions throughout the workspace were discussed and the parameters analysis on the stiffness of an Exe-Variant PKM was conducted. Results showed that the stiffness distributions of the Exe-Variant PKM were symmetric about a certain plane throughout the workspace, and the key design parameters had a great influence on the rigidity of the Exe-Variant PKM. Furthermore, the elastic deformation of joints seemed to have a greater influence on stiffness in z direction than those in x and y directions of the Exe-Variant PKM. It was worthy to point out that the analysis conducted can provide theoretical foundation for structure optimization.

Abstract:To develop reconfigurable manufacturing systems with a short changeover time, parallel mechanisms with multiple operation modes had received much attention from researchers. However, the current researches on multiple modes were mostly concentrated on the 3-DOF parallel mechanisms. A simple method of type synthesis and operation mode analysis for 4-DOF parallel mechanisms with both two-dimension translation and two-dimension rotational operation mode and three-dimension translation and one-dimension rotational operation mode was put forward. Type synthesis of 4-DOF parallel mechanisms was introduced based on the theory of position and orientation characteristics. And one family of 4-DOF parallel mechanisms with two operation modes was presented. Then, one topology was selected from the different possibilities of parallel manipulators after imposing some practical requirements. The selected parallel manipulator had instantaneously five degrees of freedom at the constraint singular configuration. The parallel manipulator must pass through singular configuration when it was switched from one operation mode to another. Redundant actuators were used to ensure that the parallel manipulator can pass through the singular configuration. Finally, the forward and inverse kinematic equations of the parallel manipulator with bifurcated motion in different operation modes were derived. The parallel manipulator presented was intended to be used in manufacturing application.

Abstract:Existing models of variant design process were mostly built at part level, and activity relationship definition was coarsely grained. Design process planning had to traverse all of the possible design activities, which resulted in low design efficiency and bad dynamic adaptation. A dynamic planning method for variant design process based on design structure matrix (DSM) was presented. Firstly, the variant design activity hierarchy model was built, including product level, feature level and parameter level. According to the hierarchy model, the product design activities can be divided into six types. The constraint relationships and their priority values between design activities at each level were defined. Then, the concept of virtual activity was proposed considering that traditional DSM cannot deal with the dynamics of design process. By packaging and decomposition operations of virtual activities, dynamic planning of the design process under complex coupling condition was achieved based on DSM. The design process planning and execution were alternated with each other. With the selection of dynamic design activities, the design process planning was adjusted continuously so as to ensure optimal execution sequence of the design activities. Finally, the method presented was applied to develop the bearing design wizard. Compared with traditional methods, the method presented was easier to adapt to dynamic design process, and it improved process planning efficiency and shortened design time.

Abstract:High-accuracy servo control of pneumatic systems requires nonlinear model-based control techniques based on full-state knowledge of the system. For the consideration of cost or light-weight design, non-linear pressure observers in place of pressure sensors were constructed to acquire the pressure states in the chambers of the pneumatic cylinder. Firstly, the global stability of the proposed pressure observer was demonstrated based on Lyapunov-stability theory. Secondly, the pressure observer’s polytropic exponent was analyzed and determined experimentally. Moreover, to check the fast convergence of the proposed pressure observer, a set of experiments for tracking a 0.5 Hz sinusoidal trajectory were performed under condition that the initial states of both chambers should be pressurized and the initial values of the observed pressures were intentionally set different from the actual values. Furthermore, to verify the load-independent of the presented pressure observer, the valve-controlled pneumatic cylinder system acted upon by a variable-stiffness loading force was adopted to carry out pneumatic servo control. A three-way on-off solenoid value was configured as two-way valve. Thus, four two-way on-off solenoid valves controlled with pulse width modulation (PWM) in lieu of one or two proportional valves were employed to govern the pneumatic cylinder for achieving the pneumatic servo control. Finally, extensive experiments validated the effectiveness and feasibility of the proposed pressure observer for high-accuracy pneumatic servo control of the valve-controlled pneumatic cylinder system.

Abstract:Dimensional analysis on parameters of wheel-soil interaction system was performed, and the parameters’ scales were also acquired when the density and cohesion of simulant regolith were kept consistent, respectively. The lightweight model method was adopted to eliminate the influence of low gravity environment, and a 1/2 scale lunar rover model was designed. The slope angle and wheel velocity were taken as the experimental factors, the wheel sinkage and slip ratio were taken as the experimental index, test on lunar rover’s slope trafficability was carried out, and the experimental factors’ influences on the wheel sinkage and slip ratio were analyzed. Variation laws of the driving torque, drawbar pull and traction coefficient with the slip ratio under different slope conditions were analyzed. Results indicated that the influence of slope angle on trafficability was more obvious than that of wheel velocity. With the increase of slip ratio, the driving torque and drawbar pull presented increasing trend, and the maximum values of the driving torque and drawbar pull were up to 3.6N·m and 10.5N, respectively. The traction coefficient was increased first and then decreased with the increase of slip ratio, and it was up to its maximum value of 0.18 when the slip ratio was 21.6%. In order to ensure that the lunar rover had safe and reliable trafficability, the exploring slope angle within 20° was reasonable. The research result would provide a reference for the evaluation of lunar rover’s slope trafficability under low gravity environment.