Abstract:The cultivated land is the basis of food security and the foundation of state. In order to regulate the cultivated land in China synthetically and three-dimensionally, according to Chinese national conditions, trinity comprehensive regulatory system about the quantity, quality and ecology of the cultivated land was studied from the perspective of system theory and public administration. Through literature analysis method combined with cutting-edge technology, the ecological regulation theory was improved based on the current relatively mature theory of cultivated land quantity, quality supervision system, the innovation of ecological regulation theory was researched, the index of cultivated land quantity, quality and ecology was constructed, and then a trinity comprehensive index system was built on this basis. Through data acquisition system of remote sensing technology, the internet of things and the internet to real-timely acquire multi-source data, and through cleansing and integration, to build cloud database that is a supervision technology system can be promoted and easy to replicate in the test points all over the country. Researching regulatory index rapid computing technology, the trinity comprehensive regulatory system was set up based on multi-source data, distributed service-oriented cultivated land. The cultivated land trinity supervision platform was constructed, it would make idea into a finished product, and provided service for government departments and regulatory decisions. The trinity supervision system of the cultivated land can provide technical support for the regulation and maintenance of the cultivated land in China.

Abstract:For the purpose of decreasing the investment of labour force in the process of vegetable grafting, a vegetable grafting robot operated by one person for Cucurbitaceous seedlings cultivated in plug trays was designed. The machine utilized the root-cutting grafting method. During working, the operator delivered respectively the stock and scion seedlings from plug trays on the left-hand and right-hand sides to seedling-providing platforms. The seedlings triggered the touching switches and then the machine completed automatically the subsequent motions of gripping, cutting, jointing, fixation and discharge controlled by PLC program. A theoretical analysis of promotion of grafting efficiency was done. In theory, the operating efficiency for one person of this robot can be promoted by 100%, compared with the old type of 2JSZ—600II grafting robot. And the analysis suggested that with the operating qualification promoting, the efficiency would be higher. Experiment results showed that the grafting success rate of the machine could reach up 95% and its grafting speed was approximately 455 seedlings per hour. Compared with previous grafting robots whose grafting efficiency was merely 600 seedlings per hour operated by two people, the machine’s working efficiency of per capita was improved by more than 50%. Therefore, the upgraded machine operated by one person was quite capable of developing the grafting labour efficiency.

Abstract:To increase the working efficiency of full automatic grafting machines for whole - row vegetable seedlings in a cell tray, the field of automatic feeding of grafting clips was studied and a grafting-clip transporting mechanism was presented. In a working cycle, this mechanism could transport five grafting clips and clamp whole-row grafting seedlings synchronously. There were three parts in a grafting-clip transporting mechanism, including an automatic grafting-clip sorting and feeding mechanism, a grafting-clip transporting platform and a linear motion mechanism. In the mechanism, automatic orientation and sorting of grafting clips were realized by a vibration device and automatic feeding was driven by a cylinder; automatic transporting of five grafting clips was achieved by a linear motion mechanism which was driven by a stepping motor; cylinders and pneumatic grippers were applied to drive and control the grafting-clip opening to clamp five grafting seedlings synchronously. The experimental study on the mechanism was completed and relative performance parameters were confirmed. The experimental results indicated that the time spent on a working cycle of the grafting-clip transporting mechanism was about 12.5s, the success rate of grafting-clip feeding could reach 94.7%, and the success rate of grafting-seedling clamping was 92%. Consequently, the grafting-clip transporting mechanism could meet the requirements of the technology of whole-row grafting; the research results laid a solid foundation for the further study on full automatic grafting machines for whole-row vegetable seedlings in a cell tray.

Abstract:The agricultural machinery positioning, dynamic tracking and working area calculation in greenhouse were focused on, and an optimum indoor positioning algorithm was proposed based on multi-source data fusion theory. The above method firstly relied on inertia navigation measurement technology to estimate initial value of target positioning; then wireless RSSI ranging technology and weighted centroid algorithm were adopted to obtain positioning measurements; and optimum calculation was conducted with Kalman filtering algorithm to eliminate errors in the end, which were common in present measurement using single measurement technology and caused by data drift, signal obstruction, electromagnetic interference and other factors, in order to acquire accurate positioning information, realize real-time dynamic tracking and calculate working area. In Matlab simulation analysis, the positioning algorithm evaluation indexes were established to assess positioning effect and it was found that the proposed algorithm had better positioning accuracy and stability than single wireless RSSI indoor positioning algorithm. In the field test, the results showed that indoor positioning accuracy was not more than 0.125m and error was less than 0.4%, which could effectively meet demands of agricultural machinery positioning and real-time dynamic tracking in greenhouse.

Abstract:In order to improve the guiding migration performance of pickup finger precision seed metering device, the steady migratory mechanism of guiding-seed system was studied. The kinematics and dynamics models of guiding-seed and dropping-seed processes were established based on its working principle. The influences of various factors on dropping trajectory and migration stability were analyzed. The quadratic general rotary unitized design was carried out by taking the rotational speed of seed meter and tilt angle as experiment factors, and the seeding qualified index and variation coefficient as experiment indexes. Based on experimental data, a mathematical model was built by using the Design—Expert 6.0.10 software, and the experiment factors were optimized, the best combination was achieved. On this basis, a kind of dropping trajectory measuring test platform was designed and built based on the theory of mirror reflection. And then the three-dimensional space velocities of the falling corn were measured and analyzed by high-speed photography and target tracking technology. The single factor tests for factors, including rotational speed and tilt angle, were carried out and the corresponding regression equations were obtained by analysis. Experimental results showed that when the rotational speed was between 15r/min and 45r/min and the tilt angle was 0°, the horizontal displacements of trajectories of frontal and profile dropping seed were increased with the increase of rotational speed and the variation coefficient of seeding was decreased with the increase of rotational speed. As the rotational speed was greater than 35r/min, the trajectories and landing positions of corn grains were gradually discrete and the variation coefficient of seeding was significantly increased, and its horizontal displacements of frontal trajectory were stabilized within the range of 12.9~14.3mm, the horizontal displacements of profile trajectory were stabilized within the range of 3.7~4.8mm, and the average variation coefficient was 15.13%. The dropping seed angle was decreased with the increase of tilt angle at rotational speed of 30r/min and tilt angle of -12°~12°. The results can provide guidance and direction for the research of mechanical precision seed metering device and its seed tube.

Abstract:Planting devices driven by double-stage planetary non-circular gear pairs can meet the requirements of ideal planting better. A total of 25 kinds of planting devices can be obtained by using gear pair composed of elliptic gear and conjugated non-circular gear, eccentric gear and conjugated non-circular gear, Pascal curve non-circular gears, Fourier curve non-circular gears or sinusoidal non-circular gears, which were used to design this type of planting device. To quickly and easily get structural parameters that can make the planting devices meet the requirements of ideal planting, kinematic multi-objective parameter optimization model was established, but the optimization results were a set of Pareto solutions. To obtain the optimal structural parameters, dynamic analysis and optimization should be implemented. So the planting device driven by eccentric gears and elliptic gears, whose first-stage planetary gear pair was composed of eccentric gear and conjugated non-circular gear and second-stage planetary gear pair was composed of elliptic gear and conjugated non-circular gear, was chosen as the research object. Its dynamic analysis model and optimization model were deduced firstly. Then dynamic optimization of this device was implemented and the optimal structural parameters were obtained. During the process of optimization, the constraint conditions were got form its Pareto solutions of kinematic optimization. A test bed for measurement of dynamics characteristics of planting device was manufactured based on the optimal parameters, and the force on the support was tested when the speed was 40r/min. The comparison between the results of test and theoretical analysis showed that the dynamic analysis model was reliable and it was able to provide reliable mathematical model for dynamic optimization. The research also provided theoretical basis and experiment instructs for other kinds of planting devices driven by double-stage planetary non-circular gear pairs.

Abstract:Optimization of tillage system for paddy soil requires a precise quantification of soil disturbance, soil structure and tillage energy efficiency. An in-situ tillage test plateform was applied for precise control on the working parameters of a subsoiler, which was a chisel design and was evaluated in five depths (i.e., 10cm, 15cm, 20cm, 25cm and 30cm). Traction, specific resistance, disturbed soil profile and soil fragment distribution were measured to evaluate the performance of the subsoiler. Results showed an increased traction with respect to the engaging depth, which satisfied a secondorder equation. In the 20cm tilling depth the degree of soil disturbance, soil surface humping, soil cracking and longitudinal humping were found the maximum. The bumping height, width, disturbed area of soil profile, mean weight diameter were 16.3cm,42.2cm, 0.0305m2 and 28.77cm, respectively. Specific resistance in this depth was the minimum,i.e. 62kN/m2. When surpassing 20cm depth, the bumping height, width, disturbed soil profile area, mean weight diameter were significantly decreased, which were 10.3cm,31.2cm, 0.0268m2 and 19.12cm, respectively, for the 30cm depth. Compared with the 20cm depth, these parameters were decreased by 36.8%,26.1%,12.1% and 33.54%, respectively. Meanwhile, the specific resistance was 195kN/m2 for the 30cm depth which was increased by 214.5% compared with 20cm depth. In considerating the overall effect of tillage-induced soil struction,soil tilth quality and energy use efficiency, tilling the paddy soil into 20cm provided the best results.

Abstract:Aiming at the problem of that the power consumption of disc type ditcher is difficult to test, a virtual test platform evaluation disc type ditcher set power consumption method was proposed. Firstly, the dynamics model of disc type ditcher was established. In order to shorten the operation time, the secondary characteristics such as chamfer, fillet and connection were omitted. The boundary conditions and loads were set up. The virtual simulation of power consumption in disc type ditcher was carried out with trenching depths of 400mm and 500mm, forward speeds of 0.8km/h and 1.5km/h, rotation speeds of 180r/min and 220r/min, respectively. The power curve of ditch process showed that at the beginning of soil cutting, power consumption was increased quickly, the reason for which was a great deal of power consumption was needed during the process of soil deformation and broken. After that the power consumption was tended to be stable, for the reason of which was the binding force was tended to be less after the soil particle was destroyed. Then the field power test system was built and the relative errors were 6.88% and 7.73%, respectively, compared with simulation results. The accuracy and feasibility of the proposed method were verified. Finally, totally 18 conditions (three trenching depths, two forward speeds, and three rotating speeds) were selected to carry out the simulation. The results showed that with a certain trenching depth, the disc type ditcher had an increasing linear relationship with forward speed and rotation speed. With a certain ditching depth and forward speed, the lowest power consumption was appeared at rotation speed of 200r/min. Moreover, with a large trenching depth and forward speed, the effect of rotation speed on power consumption was obvious. When the rotary speed was 200r/min，both low and high speeds, disc type ditcher had the lowest power consumption value. According to comparison at rotary speed of 219r/min in different ditching depths and forward speeds, the power consumption at rotary speed of 200r/min was decreased by 8.5kW, 9.6kW and 4.6kW, the results provided a theoretical basis for power consumption measurement of rotary ditcher.

Abstract:According to the problems of field plastic film pollution caused by the cultivation pattern of potato big ridge double line which was promoted in large area in Northwest China, the combined operation machine for potato harvesting and plastic film pneumatic auxiliary collecting was designed, which had synchronous implementation function of potato harvesting and plastic film pneumatic collecting. Based on design and selection of key operation parts for the prototype, the structure and operation parameters of ladder digging blade, soil-potato dither conveyor device and floating pneumatic curl-up film mechanism were determined. The operation process of floating pneumatic curl-up film mechanism was analyzed and the conditions to make sure that the floating pneumatic curl-up film mechanism did not produce the phenomenon of plastic film remained and jam, tensile and skid were achieved, the conditions of wheel did not slip but rolling in the field were analyzed and calculated. For the relevant work performance test of prototype, the field experiment results showed that when the operation speed of the combined operation machine was 1.8~2.0km/h, the plastic film collecting ratio was 91.6%, the obvious ratio of potato was 96.8% and the injury ratio of potato was 2.3%, which met the relevant work quality evaluation specification requirements, and also the experiment results met the design requirements of combined operation machine. The research achievement would provide an important reference for root-tuber crop collecting machine development under plastic film mulching cultivation.

Abstract:Aiming to resolve the problem the space structure of rope cutting and releasing mechanism of knotter was very complex and the structure parameter influencing the motion of rope cutting and releasing was unknown. Kinematics analysis of rope cutting and releasing mechanism and other mechanism were carried out. The parametric design theory about rope cutting and releasing mechanism was established. The relationship of parameter matching between rope cutting and releasing mechanism and other mechanism was described. The important structure parameters influencing the motion of rope cutting and releasing were analyzed. The design requirements of rope releasing platform and cutting knife were calculated. The results showed that the distance between center of gyration of rope cutting and releasing mechanism and the rope releasing platform were 27~35mm, the distance between centre of gyration of rope cutting and releasing mechanism and the platform of rope cutting knife were 47~53mm, the cutting edge size of rope cutting knife was decided by the position size of platform of rope cutting knife. In order to verify the accuracy of the model, a modular rope cutting and releasing mechanism was designed and manufactured based on the range of key size of rope cutting and releasing mechanism. The designed rope cutting and releasing mechanism can adjust the position size and structure size of rope releasing platform and cutting knife, it was very convenient for the validation of structural parameters of rope cutting and releasing mechanism. The wheat straw baling test on the designed mechanism was conducted in the interior, eleven experimental groups were designed. Results showed that if the design size met the design requirements, the effect of rope cutting and releasing was good, otherwise the effect of rope cutting and releasing was poor. Therefore, it can be found that the calculating structural size parameters of rope cutting and releasing mechanism were confirmed to the requirements of D-knotter, and the model was accurate and it could guide the optimal design of D-knotter.

Abstract:Sliding mesh method is one of the most important methods for analyzing transient rotor-stator coupling of centrifugal pump. The shape and position of sliding mesh interface have direct impacts on the calculation results of transient flow field. However, until now there was no uniform view on how to select the sliding mesh interface. A centrifugal pump was taken as study object. Five different sliding mesh interface schemes were used to simulate the transient flow field. Results showed that the average simulation errors of pump efficiencies for scheme I (i.e., the short line-shaped interface close to impeller outlet) and scheme V (i.e., the inverted U-shaped interface surrounding impeller) were both about 1%. The streamlines in meridian plane and velocities in volute inlet for both schemes were in line with existed experimental results. Specially, the scheme V can give more reasonable gradient of velocity in pump chamber, and gain right results of pressure fluctuation in tongue area. Both scheme Ⅲ (i.e., the long line-shaped interface close to impeller outlet) and scheme Ⅳ (i.e., the long line-shaped interface close to base circle of spiral casing) set the pump chamber to a rotating domain, and gave the simulation errors of pump efficiency as 5.2% and 9.2%, respectively, which also resulted in incorrect streamlines in meridian plane. Both scheme Ⅳ and scheme Ⅱ (i.e., the short line-shaped interface close to base circle of volute casing) set the rotating domain close to tongue, and caused shearing action of tongue to be enlarged. The inlet velocities in tongue area were decreased seriously. In summary, the schemes that made the entire pump chamber into rotating domain or made the interface close to the tongue would make the simulation results unreasonable. The scheme taking the inverted U-shaped interface surrounding impeller as interface was suggested. This scheme can guarantee the simulation accuracy and reflect the real characteristics of the flow field.

Abstract:In order to study the flow characteristics of centrifugal pumps when transporting the gas—liquid mixture, water and air were chosen as the working medium, numerical simulation was conducted on a centrifugal pump under different conditions of inlet gas volume fraction （IGVF） based on the Eulerian—Eulerian inhomogeneous model. The drag force was approximated by the Schiller Nauman model. No other interfacial forces were considered. The gas distribution and velocity streamline in the impeller were obtained to discuss the gas and water flow characteristics of the pump. The results showed that gas concentration was high at the inlet pressure side of the blade, where the vortex would exist, indicating that the gas concentration had a great relationship with the vortex aggregation in the impeller passages. When the IGVF was increased to 10%, phase separation had obviously appeared at the suction side of the blades in the impeller passages, and gas had a movement trend along the suction side to the outlet of the impeller. Gas was moved from the center of the passages to the front and back shroud, and with IGVF increased, gas fraction in the back shroud near the leading edge and back shroud would be increase. Gas fraction in the front shroud near the trading edge was increased significantly than that in the back shroud, and the gas may eventually choke the passages. Within a rotation period, the outlet pressure of impeller was cyclically changed, when IGVF was increased from 1% to 10%, the outlet pressure of impeller was gradually decreased, and pressure pulsation frequency of the monitors was near the blade passing frequency at different IGVF values. When the IGVF was not higher than 10%, IGVF had no obvious effects on the pressure pulsation frequency and time frequency of the monitoring points. By comparing the experimental results with the numerical results, the reliability of the mathematical model and calculation methods was confirmed.

Abstract:In order to better understand the hydraulic performance of cube-type pump system with inlet and outlet conduits, based on CFD numerical simulation and DOE orthogonal experimental design method of a model test, a three dimensional parametric model of the inlet and outlet conduits was constructed with the velocity uniformity of outlet-section for inlet passage and the hydraulic loss as objective function. The five factors and four levels orthogonal test was designed in view of the inlet flare tube, the water-guide cone, the outlet flare tube and the control size of outlet-guide piers. Aiming at the design flow point, totally 16 numerical simulation schemes of the inlet passage and outlet passage were calculated respectively by means of CFD numerical simulation to analyze the effect of different control sizes on the performance of inlet and outlet conduits. The reliability of optimization numerical results was validated through the model test finally. As shown in the numerical simulation and experimental results, the inlet conduit optimization design by means of DOE orthogonal design method, the influence of control parameters on hydraulic loss of an inlet passage and the primary and secondary effects on the uniformity of export section can be got. The largest hydraulic loss was 8.56cm, the smallest hydraulic loss was 3.91cm, the optimized hydraulic loss was 3.65cm, and the uniformity of outlet velocity was 93.07%, the optimization design made the hydraulic loss reduced by 1.31cm and the uniformity of outlet velocity increased by 1.17 percentage points compared with the initial plan. The largest hydraulic loss of outlet conduit was 46.07cm, the hydraulic loss of outlet conduit for the optimal combination scheme was 32.53cm,which was reduced by 7.96cm compared with the original plan. According to the whole characteristic curve of the pump system, it can be learned that the pump hydraulic loss of outlet conduit was minimum under the design condition, the highest efficiency was 70.04%, the highest running head was 4.0m under the design condition with head of 1.36m, the efficiency was 66.82%, and the corresponding flow rate was 34.31m3/s. The highest efficiency of the model test can be up to 71.5% under the design condition with head of 1.36m, the test efficiency was around 64%, which was in good agreement with the numerical simulation results. It illustrated that the better scheme can be designed by using the orthogonal design method, this study also provided reference for the similar optimization design of pump station.

Abstract:In order to objectively monitor and evaluate the effectiveness of land consolidation, a new method to identify filed patch data was proposed, which was based on remote sensing imagery and taking arable land polygon data as constraints. The field patch data identified by using this method not only had regional characteristics, but also considered ownership information to some extent. On this basis, evaluation index system in field and regional levels was respectively built for cultivated field patch fragmentation’s degree. Patch area, regularity, compactness and connectivity were chosen as evaluation indexes in field level and mean area, density of field patch, LAI, LSI and PAFRAC were chosen as evaluation indexes in regional level. And then the indexes in two levels were made to be dimensionless respectively. The method was applied to Guangxi hilly areas and Hainan plains. The results of experiment showed that after consolidation, the majority of comprehensive evaluation index in field level of Guangxi region was improved from 50~70 to 70~90, and that in Hainan plains was improved from 70~90 to 90~100.The comprehensive evaluation index in regional level of Guangxi hilly areas was increased from 41 to 83 after land consolidation, and that in Hainan plains was increased from 63 to 92. The proposed method for identifying field patch can support the monitor and evaluation of land consolidation projection aimed at land fragmentation, no matter study areas located in hilly areas or plain areas. Hence, the research result can provide support for remote sensing monitor and evaluation in land consolidation areas and remote sensing discerning of well-facilitated farmland.

Abstract:Slope is one of the key factors which had a close relationship with soil and water losses and land use planning, and it is one of the most important pieces of information in many natural source spatial databases. Slope was usually extracted from digital elevation model (DEM) in regional scale. However, it is difficult to obtain DEMs with grid size less than 10m from continental or country scale topographic maps that are needed to include topographic changes due to terraces because of manpower and financial restrictions. Thus the high resolution DEMs were usually obtained by super-resolution reconstruction or down scaling from low resolution DEMs. As a basic data source, high resolution DEMs created by super-resolution methods do influence the extraction of slope. Dry terraced fields in the hilly loess region around Longquan of Yuzhong County were taken as study area. DEMs and orthophotos obtained in March, 2015 by UAV-based photogrammetry were used. The resolution of the DEMs data was generated in 5m, 10m, 20m and 40m respectively for slope produce. Sparse mixed estimation method (SME), nearest method, bilinear method and cubic method were used for DEMs reconstruction. Finally, the slope was calculated from original DEMs and reconstructed DEMs. The result showed that the SME method was the best method in DEMs super resolution reconstruction for extraction of slope.

Abstract:Recently, researchers adopted object-oriented method to extract wetland distributions. Multi-temporal and multi-sources of data can facilitate the extraction process but meanwhile it enlarges the amount of features. It needs a large quantity of experiment based on the expert knowledge to determine the optimal feature sets and the threshold values. In order to improve the classification accuracy and relief the researchers from large amount of work, a filter-wrapper hybrid feature selection method combining relief F, multi-objective genetic algorithm and random forest was proposed, which was a two-step method. In the first step, relief F algorithm was adopted to select features with class separability. In the second step, multi-objective genetic algorithm based on random forest (MOGARF) was built. Four measures such as out-of-bag (OOB) error of random forest algorithm, dimension of the feature space, correlations among features and the variable weight of relief F algorithm were acted as four objectives of MOGA. The probability whether the feature was expressed was determined by the variable importance measures from random forest algorithm. The crowded distance of each feature collection was calculated and the feature collection with the least crowded distance was the optimal feature set. Nanweng river basin was taken as the study site. Object-oriented classification using random forest classifier was conducted based on the optimal feature set. Then the result was compared with three other random forest classification schemes by using the entire feature set or the feature set selected by relief F algorithm or the Boruta algorithm. The classification scheme with MOGARF had the best performance and the feature dimension was reduced to 10% of the entire one. The overall accuracy reached 92.61% which was 0.35%~1.94% higher than those of the other three schemes with Kappa coefficient of 0.9306. The OOB error of MOGARF was 7.77% which was 0.91%~1.48% lower than those of the other schemes. All these indicated that the MOGARF feature selection method was an effective feature selection method when it was combined with random forest classifier.

Abstract:Aiming to reveal the coupling relationship between land use spatial autocorrelation patterns and natural—social—economic factors of Xiaolihe watershed located in loess hilly-gully region, the global and local spatial autocorrelation patterns of land use types were analyzed by the methods of Moran’s I, Moran scatter plot and Anselin local Moran’s I in the 500m×500m grid scale, meanwhile, the relationships between local cluster zones and the selected environmental factors were analyzed at the p<0.05 significant level based on GIS technology. The selected environmental factors included elevation, slope, aspect, water, roads and residential areas. The results showed that all land use types showed positive global spatial autocorrelation, but it was gradually decreased with the increase of distance. Within the distance of 32km, spatial attenuation intensity of autocorrelation of each land use type was different from the extension of distance. The spatial distribution of cultivated land and grassland showed significant HH (high value—high value) and LL (low value—low value) cluster trends, and that of garden land, forest land, construction land and unused land showed significant HH cluster trend. The HH cluster zones of grassland were mainly distributed in hills or mountains of the midstream and upstream watershed, the HH cluster zones of forest land were mainly distributed in gullies of the downstream watershed and mountains of the upstream watershed, and those of others were mainly distributed in wide loess ridges and wide river valleys of the downstream watershed. With the increase of elevation and slope, the areas of HH and LL cluster zones of each land use type were increased firstly and then decreased. The region, which was located in the elevation area of 1000~1300m, the slope area of 15°~25°, the sunny area and shady slope area, was the most diverse and concentrated area of HH cluster distribution of land use types. The HH cluster zones of construction land and forest land were mainly distributed in the elevation area of 1000~1100m, the HH cluster zones of cultivated land, garden land and unused land were mainly distributed in the elevation area of 1100~1200m, and those of grassland were mainly distributed in the elevation area of 1200~1300m. According to the average slope of HH cluster zones of each land use type in ascending order, the order was as follows: construction land, cultivated land, garden land, forest land, unused land and grassland. The HH cluster zones of construction land, garden land and cultivated land were mainly distributed in sunny area and semisunny area, in which the distribution area in sunny area was larger. The HH cluster zones of forest land and garden land were mainly distributed in shady slope area and sunny area, in which the distribution area in shady slope area was larger. With the increase of distance from water and roads, the areas of HH cluster zones of each land use type showed a declining trend except for unused land. With the increase of distance from residential areas, the areas of HH cluster zones of grassland were increased firstly and then decreased, and those of others showed a declining trend. The HH and LL cluster zones of each land use type were mainly distributed within the distance of 1.5km from water and roads as well as within the distance of 3km from residential areas. The areas of HH cluster zones of construction land, garden land and cultivated land were increased rapidly with the decrease of distance to water, roads and residential areas. Compared with HH cluster zones, the LL cluster zones of cultivated land were mainly distributed in the elevation area of greater than 1200m,and the average slope of the LL cluster zones was increased. The distribution area of the LL cluster zones of cultivated land in the sunny area was slightly larger than those in other aspects. The LL cluster zones of cultivated land were farther away from water and residential areas, and the areas of which were firstly increased and then decreased. While the LL cluster zones of grassland were mainly distributed in the elevation area of 1000~1200m and the slope area of 15°~35°, and the distribution area of the LL cluster zones in each aspect was similar. The LL cluster zones of grassland were closer to water, roads and residential area, and the areas of which showed a declining trend.

Abstract:A method of information extraction for maize at jointing stage was described by using the high-resolution visible images, which were obtained by the unmanned aerial vehicle (UAV) remote sensing system. The 27 texture features of five ground objects were calculated separately, including maize, wheat, sunflower, sapling and bare land in the region of interest obtained by using co-occurrence measures and convolutions low pass. Comparing the variation coefficient of five ground objects and the relative difference with maize, the mean of green, homogeneity of blue and texture low pass vegetation index (TLVI) were chosen as the feature to obtain planting information of maize. In order to distinguish the maize land and sapling land, the TLVI was built by using scatter diagram in which the X axis was the lowpass red band and the Y axis was the low-pass blue band of maize land and sapling land. In the preliminary result, it was found that there were patches which had the same feature with maize land in wheat land and sapling land and patches of other kinds in the maize land. By analyzing the uniqueness of shape and area of two kinds of patches, the other patches were removed and the patches of maize land were retained. In order to verify the applicability and the reliability of the method, two different images which were in the same period with the region of interest were chosen to process by using the same method. The results indicated that the method could extract planting information of maize through using the high-resolution visible images obtained by the UAV remote sensing system and the area extraction error was less than 20%.

Abstract:Chlorophyll fluorescence is a useful indicator as it gives important information about the stress and health state of plant. In order to detect plant water stress and growth state accurately and intuitively, plants under different drought stress conditions were experimented by using chlorophyll fluorescence imaging method combined with the chlorophyll fluorescence kinetics parameters. The chlorophyll fluorescence was excited by 460nm LEDs, and acquired by EMCCD equipped with 690nm band pass filter. The average pixel value was calculated for each image of 4000 pictures which were acquired in four different sampling periods individually. The intensity of each image was plotted according to the time sequence, thus the chlorophyll fluorescence kinetics curve could be concluded, and chlorophyll fluorescence kinetics parameters could be calculated. Meanwhile, images were processed for noise reduction, calculation of multiplication and division and so on. And then they were displayed by pseudo color, thus various factors led to uneven distribution of fluorescence could be intuitively analyzed. Fast water stress and slow water stress experiments were conducted for easy to dehydrate and not easy to water loss leaves, respectively. The results showed that the fluorescence ratio Rfd and the time of second peak of kinetics curve were changed with the increase of stress, and both had high fitting determination coefficient with leaf water content (0.86 and 0.98). Therefore, the method combined the chlorophyll fluorescence imaging with chlorophyll fluorescence kinetics parameters could improve the accuracy and intuition of plant drought stress earlier prediction, and it could be a rapid means of remote sensing for site continuous monitoring the growth status of plants, all kinds of stress, pest and disease and so on.

Abstract:Animal behaviors are reflective of its welfare state. They contain important information that can enable producers to better manage livestock. Yet it is more difficult in recognizing the behaviors of group laying hens than other big size animals. Large numbers of hens, homogeneous in appearance, high stocking density and variable body size all contribute to this situation. A computer vision-based system was developed which can automatically recognize group behaviors (distribution index, horizontal activity index and vertical activity index) and individual behaviors (feeding, lying, standing and sitting) of group hens. The system consisted of a 3D camera that simultaneously acquired digital and depth images and a software program that detected and identified the behaviors. The computational algorithm for the analysis of depth images was presented and its performance in recognizing the behaviors as compared with manual recognition was analyzed. The images were acquired at 5s intervals in 10d period. The algorithm had the following accuracy of individual behavioral classification: 90.3% in feeding, 91.5% in lying, 87.5% in standing and 56.2% in sitting. The lower classification accuracy for the sitting presumably stemmed to imprecise segmentation valve value between sitting and standing and sometimes mistook hen’s standing behavior (exploring in ground) for sitting which could be improved in later test. Hence the reported system provided an effective way to automatically process and classify hen’s group and individual behaviors. This tool was conducive to investigate behavioral responses and time budget of laying hens and facility design and management practice.

Abstract:Crop disease is an important factor to restrict high-yielding, high-quality and high efficiency of products. Soybean is a critical crop, but incidence of soybean diseases increases year by year during their growth, so diagnosis of soybean diseases timely and accurately can provide reliable basis for prevention and control of soybean. Therefore, aiming at the fuzzy and uncertainty between disease traits and diseases of soybean leaf diseases, combining digital image possessing and neural network technology, the diagnosis model of soybean diseases was proposed based on improved cascade neural network after the potential rules of disease traits and diseases was fully mined. Firstly, the diseases images were acquitted by home-made slide template, the 14 dimensional characteristic parameters were calculated based on the geometry characteristic, color characteristic and texture characteristic of disease areas. Secondly, in order to highlight all aspects of characteristics for different kinds of diseases, the first level of each parallel neural network was constructed, the output of the first level was the input of the second level. Thirdly, the two slopes cascade neural network model was established for diagnosis soybean leaf diseases automatically, which based on inference rules of diseases using respective advantages of multidimensional characteristics, the simulation accuracy was 97.67%. Meanwhile, the cascade neural network parameters were optimized by quantum genetic algorithm. The average number of iterations was 743, and the average network error was 0.000995445. The proposed method realized the automatic diagnosis and precise forwards, which also provided important theory basis for disease monitoring and smart pesticide spraying.

Abstract:In the process of maize breeding, the development degree of maize ear is one of the most important parameters for yield related traits. In order to improve the degree of automation and accuracy of maize ear development degree detection, a measurement method was proposed based on machine vision technology. An identification model was constructed on the basis of random forest principal at first. The model was composed of a group of weak classifiers which were independent and identically distributed. The weak classifiers selected samples from the input training samples randomly along columns and rows. The experiment which compared random forest model with decision tree model on the classification effect showed that random forest classifier could not only avoid over-fitting and local convergence effectively but also have good generalization ability. Then, in order to determine the optimal number of weak classifiers, six random forest models were built. Their weak classifier number were separately one-eightieth, one-fortieth, one-twentieth, one-tenth, one-fifth, one-fourth of training samples count. The results showed that the model had good accuracy and stability when the number of weak classifiers was one-twentieth of training samples count. Finally, the optimal random forest model was used as the classifier to build the automatic maize ear development degree detection method. The experiment results showed that the measurement accuracy on length of each area was more than 95% and the measurement speed was more than 30 maize ears per minute.

Abstract:In order to explore the movement characteristics of water and salt in soil under moistube-irrgation with brackish water, an indoor soil box simulation experiment was conducted under five different mineralization degree treatments with distilled water as control in 72h. The results showed that with the rise of mineralization degree, the maximum migration distance presented a trend of first increase and then decrease in different directions and reached the highest when the degree of mineralization was 3.0g/L. And the distances of wetted front under treatments of brackish water were all greater than that of distilled water. Then the cumulative infiltration was substituted into the Kostiakov infiltration equation and the infiltration coefficient showed a trend of rise first and then fall with the increase of mineralization degree, while infiltration index continued to decline. The soil conductivity was increased constantly to all around with the moistube-irrgation zone as axis and reached the peak at the wet front. The desalting area was related to the shape of the wetted body and distributed in circular shape. There was no significant difference in the average salt content of soil profile between brackish and distilled water after infiltration. The desalination radius was decreased linearly with the increase of mineralization degree. Both surface and bottom convergence phenomenon existed and the salification in soil surface was more serious under moistube-irrgation.

Abstract:In order to make full use of saline water resources, the impacts of different patterns (totally five treatments: CK, fresh water irrigation;T1, blended irrigation by mixing fresh water and saline water into 1.8g/L salty water;T2, rotated irrigation of 3.6g/L saline water with fresh water;T3, direct irrigation with 3.6g/L salty water and T4, no irrigation) of salty water irrigation on photosynthetic characteristics and soil salt of winter wheat were studied in 2013—2015 based on a long-term saline water irrigation experiment. The results showed that treatments T3 and T4 significantly decreased plant height, leaf area index, leaf area duration, chlorophyll content, maximum photosynthetic rate (Pnmax), apparent quantum yield (φ), dark respiration rate (Rd) and grain yield compared with fresh water irrigation (CK). Continuous irrigation with 3.6g/L salty water (T3) led to soil salt accumulation, thus it was not suitable for directly continuous irrigation of winter wheat. In comparison with CK, treatments T1 and T2 had no significant differences in plant height and photosynthetic characteristics, while there was an increasing tendency in soil salt content, the plant growth was not impacted. From the aspects of soil ecological environment and grain yield, the rotated irrigation pattern and the blended irrigation pattern of saline water utilization did not cause yield reduction and obvious soil secondary salinization, but it can save fresh water, therefore they were comparatively better ways for salty water utilization in winter wheat irrigation. The study provided an important reference for developing saline water irrigation of winter wheat.

Abstract:Arabica coffee has the habit of shading cultivation and its growth often is inhibited by soil drought stress. Shade changes micro-climate of coffee growth and further affects photosynthetic characteristics and water consumption. The object was to explore suitable management mode of water and light, using three levels of deficit irrigation, i. e., light deficit irrigation (DIL, (65%~75%) field capacity), medium deficit irrigation (DIM, (55%~65%) field capacity) and severe deficit irrigation (DIS, (45%~55%) field capacity), respectively, and three levels of shade,i.e., no shade (S0, natural light), light shade (SL, 50% natural light) and severe shade (SS, 30% natural light). The effect of deficit irrigation and shading levels on daily mean photosynthetic characteristics, growth and water—radiation use efficiency of arabica coffee was studied by pot experiments, and regression model was established under different deficit irrigation and shade levels. The results showed that compared with DIL, DIS reduced coffee leaf net photosynthetic rate, stomatal conductance and radiation use efficiency by 17.61%, 22.99% and 27.43%, respectively, and reduced the total dry mass by 6.29%, but DIM had no significant effects on leaf net photosynthetic rate, stomatal conductance, radiation use efficiency and total dry mass. Leaf radiation use efficiency of S0 was the lowest, SL was the second and SS was the highest. S0 or SS inhibited net leaf photosynthetic rate and water use efficiency, and SL increased dry mass by 11.14%. Compared with DILS0, shading under deficit irrigation reduced leaf transpiration rate but increased light use efficiency significantly. Leaf radiation use efficiency showed a significant exponential relation with photosynthetically active radiation. Irrigation water use efficiency was increased first and then decreased with the increase of water deficit level and shading degree. On the basis of high dry mass accumulation and water use efficiency, the suitable mode of water and light management of arabica coffee was the combination of light deficit irrigation and light shade (DILSL). The study results can provide scientific basis for irrigation and shade management of arabica coffee. In addition, this experiment was only focused on coffee growth, dry matter and water—radiation use, and yield, quality and flavor were not involved. Further systematic discussion of arabica coffee was needed under different irrigation and shade conditions.

Abstract:The residual plastic film seriously affected the soil water infiltration and evaporation. Five residual plastic film treatments were conducted to study the effects of different residual plastic film amounts (0kg/hm2,50kg/hm2, 100kg/hm2, 200kg/hm2 and 400kg/hm2) on soil water infiltration and evaporation characteristics, and the infiltration front, infiltration rate, cumulative infiltration, cumulative evaporation and the evaporation rate were mainly studied based on the different residual plastic film quantities for sandy loam and sandy soil, and then the performance of main soil infiltration and evaporation model with residual plastic film was evaluated. The results showed that with the increase of residual plastic film quantity in the soil, the infiltration rates of sandy loam and sandy soil were decreased slowly, the time required for wetting front migration was increased significantly, and the sandy loam with 400kg/hm2 residual plastic film treatment (SL5) was increased by 27.56% compared with that of nonresidual plastic film treatment (SL1) at 30cm soil layer. In addition, the cumulative infiltration amount was significantly decreased (P<0.05) in the same infiltration time, and the cumulative infiltration amount of SL5 treatment was reduced by 52.01mL (23.12%) compared with SL1 at the end of infiltration. The evaporation rate and cumulative evaporation were significantly reduced (P<0.05) with the increase of residual plastic film quantity, the cumulative evaporation rate of SL5 treatment was 30.63% less than that of SL1 after evaporation, and the influence of different residual plastic film amounts on sandy loam was greater than that of sandy soil. The four major soil water infiltration and evaporation model were evaluated, it was showed that both Kostiakov and Philip infiltration models can well simulate the soil water infiltration for the soil with residual plastic film, but the Philip model had better performance than Kostiakov model, and had better adaptability for sandy soil with plastic film residue. The fitting accuracy of Black evaporation model was decreased with the increase of residual plastic film quantity, but the Rose evaporation model was less influenced by the amount of residual plastic film. So it can be concluded that the Rose evaporation model was more suitable for the plastic film residual soil cumulative evaporation estimation.

Abstract:Concerning the increasing of plant density is one of important ways to achieve high yield, field experiments were conducted to investigate the effects of increasing plant density and plastic film mulching on the growth and yield of spring maize, and crop evapotranspiration. The results showed that film mulching accelerated growth and development of maize. It also increased height and leaf area index of the plant at early growth stage of maize. At the late growth stage of maize, plant height of maize without film mulching was decreased with the increase of density, but no significant difference was found for plastic film mulching. Whether mulching or un-mulching, leaf area index of maize was increased with the increase of the density. Evapotranspiration increased with the increase of the density, however, film mulching reduced consumption of water and alleviated the contradiction between increase of water consumption because of the increased plant density and plant height and insufficient precipitation. Film mulching significantly increased maize yield and water use efficiency by 52.79% and 60.55% compared with un-mulching. The grain yield and the water use efficiency of un-mulching and film mulching treatments were all increased with the increase of the plant density until a plateau and then declined. The difference was that the maximum yield of un-mulching was 8466.02kg/hm2 and it was achieved at 52500 plants/hm2, however, the maximum yield of film mulching was 12778.47kg/hm2 and it was achieved at 82500 plants/hm2. As a result, the optimum planting densities on eastern Loess Plateau for film mulching and un-mulching of spring maize were 52500 plants/hm2 and 82500 plants/hm2.

Abstract:A field experiment was conducted to explore the effect of vermicompost on the root absorption characteristics and humus composition of cowpea rhizosphere soil. The effects of different treatments, i.e., CK (neither urea nor vermicompost was applied), CF (100% of nitrogen was provided by urea), VC(100% of nitrogen was provided by vermicompost), and VC+CF (vermicompost and urea each provided 50% of nitrogen) on soil physical property, root activity, root morphological characteristics and root exudates, as well as humus composition in the rhizosphere soil of cowpea were studied. The results indicated that in comparison with CF treatment, the VC and VC+CF treatments evidently decreased soil bulk density, and significantly increased soil total porosity, capillary porosity and non-capillary porosity. Different fertilization treatments had no significant effect on root characteristics and humus composition in the rhizosphere soil at the seedling stage of cowpea. While at the stretch tendril period and flowering and pods formation stage, VC+CF treatment significantly increased root activity and obviously increased the total root length, specific root length, root surface area, root volume and root tip number, while the root average diameter was apparently decreased compared with CF treatment. The root surface area in the VC+CF treatment was increased by 144.88%, 80.73% and 36.82% at the flowering and pods formation stage compared with the treatments of CK, CF and VC, respectively. Meanwhile, VC+CF treatment also significantly increased the contents of root exudates and humic acid, and increased the ratio of humic acid to fulvic acid, showing 4519%, 37.06% and 7.69% increases in humic acid content over the treatments of CK, CF and VC at the flowering and pods formation stage, respectively. Additionally, the VC+CF treatment could significantly increase yield and improve quality of cowpea, which had statistically significant differences with other treatments. Along with the extension of cowpea growth period, the impact of vermicompost co-applied with urea on root growth and soil physic-chemical properties of cowpea presented a gradually increasing trend. As a result, the application of vermicompost co-applied with urea was beneficial to root absorption characteristics and humus composition in the rhizosphere soil and soil nutrient-supply capacity improvement as well as growth with high-yield and high-quality of cowpea.

Abstract:With the development of earth’s critical zone, the crucial hydropedological problems are needed to be solved. The quantitative expression of preferential flow and soil structure and stratification, water flow in situ and solute transport is the key research to the earth’s critical zone. Phosphorus loss from soils and water flow has been a vital water quality issue because of the critical role that phosphorus plays in eutrophication. Preferential flow pathways (PFPs) are one of main factors that affect subsurface phosphorus transport, which are the direct connections between soil surface and groundwater. The phosphorus fractions of two types of soil, Regosols from Gongga Mountain and Stagnosol from Ore Mountain, were investigated by using the modified Hedley sequential phosphorus extraction method. Regosols in Gongga Mountain was developed by the moraine colonization by plants in the relatively mild and humid climate. PFPs were identified by the dye tracer experiments using brilliant blue FCF. The tracerinfiltration patterns were parameterized by dye coverage ratio (Dc) and evaluation index of PFPs (Cv). The impact of PFPs on the distribution of phosphorus fractions was evaluated by the Pearson correlations and T-test. The results indicated that dye coverages of Regosols from Gongga Mountain and Stagnosol from Ore Mountain were 31% and 52%, respectively. The degree of preferential flow in Ore Mountain Stagnosol soil was tended to be larger than that in Regosols soil from Gongga Mountain;PFPs in Gongga Mountain were important contributors to the potential bioavailable inorganic phosphorus (PBPi) and organic phosphorus load, while PFPs in Ore Mountain were important contributors to the readily bioavailable inorganic phosphorus (RBPi). In conclusion, the results showed that soil types could affect both the infiltration patterns of PFPs and the transfer process of phosphorus fractions.

Abstract:The inducing mechanism of emitters clogging with fertigation was explored. A laboratory experiment was conducted to investigate the influence of three factors (fertilizer types, fertilizer concentration and flow path structure) on anti-clogging performance of drip emitters. The intermittent drip irrigation experiment was studied by using two flow path types of non-pressure compensating emitters (arc-shaped saw-tooth and cup-shaped saw-tooth), four levels of fertilization concentration (0.5%, 1.0%, 2.0% and 3.0%) and four types of fertilizer (urea, calcium superphosphate, potassium sulfate and water soluble compound fertilizer) and the system was allowed to run for 20 h. The mathematical analysis methods in combination with field scanning electron microscope (FESM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) technology were then used to quantitatively and qualitatively analyze the variations of the emitter’s average relative flow rate, surface topographical characteristics and components of the clogging materials internal emitters. Results showed that fertilizer characteristic was an important factor in deciding the emitter clogging type and degree (P<0.01), and the influence of the two flow path structures on the accelerating effect of emitter clogging performance needed to consider the path structural size and style. The accelerating effect of fertilizer application on emitter was not obvious when the concentration of fertilizer solution was less than 0.5%. When the concentration was increased to 0.5%～2.0%, there were obvious changes in the quantities of outflow discharge occurred in phosphate-fertigation, which made it clog easily, followed with urea-fertigation, the applicability of potassium-fertigation and compoundfertigation was better than that of the former. When the concentration was risen to 2.0%～3.0% or higher, the clogging degree was so serious with ureafertigation, the flow rate was decreased by 1026%, which was significantly higher than those of phosphate-fertigation (7.85%), potassium-fertigation (4.07%) and compound-fertigation (2.74%). Fertilization can promote the clogging of the emitters. These fertilizer types had different water quality, hence resulting into different emitter clogging risk and inducing mechanism. Emitters clogging with urea fertigation were caused by the role of aggregation and adhesion with both crystallization of the molecular urea state and suspended particles in the water. The adsorption function that particulate impurities to phosphorus promoted flocculation while precipitation among solid particles was as a result of inducing mechanism of emitter clogging with phosphate fertigation. The main inducing mechanism for emitter clogging with potassium-fertigation was chemical precipitation because of the ion-exchange action, while emitter clogging with compound-fertigation had the lowest risk. Therefore, fertigation with different fertilizer types should adopt different emitter clogging controlling management strategy.

Abstract:In order to reduce the operation cost of ammonia nitrogen and phosphorus removal from biogas slurry (BS) through the “thermal-alkaline stripping” process, biomass ash (BA) addition was put forward to elevate the value of pH and precipitate the phosphorus in BS. Totally four types of BA were added into BS and pure water, including rice straw ash (RS), groundnut shell ash (GDS), cotton straw ash (CTS) and corn straw ash (CNS). Main water qualities of those solutions, including chemical oxygen demand (COD), concentration of suspended solid (SS), total phosphorus (TP) and total ammonia content (TAN), pH values, as well as calcium (Ca) and magnesium (Mg) contents were tested. The germination index (GI) values of Chinese cabbage seeds treated by these biogas slurries after CO2 saturated were evaluated as well. Among those BAs, CTS had the highest solubility of about 12.97% and GDS had the lowest value of 1067%. The results showed that when the BAs were added into the pure water, the pH value of water can reach 10.0~12.5. But when the same dosages of BAs were added into BS, the pH value of BS can only be elevated to 9.5~11.0 from 7.87 due to the good buffering characteristics of BS. The main reason of pH value improvement of BS might be the precipitation of CO2 in BS by Ca2+ or Mg2+ leached from BA. This relatively high pH value could meet the requirement of “thermal-alkaline stripping” process for ammonia nitrogen removal, which may contribute to reducing the operation cost greatly. On the other hand, phosphorus removal efficiency was generally increased with the increase of BA dosage. The highest phosphorus removal efficiency of 78.74% was acquired when 100g/L CTS was added into BS, but the efficiency was decreased inversely when BA dosage was increased to 200g/L. The results also showed that when the BA dosage was increased to 200g/L, the removal efficiency of COD and SS were above 50%. For the higher value of pH and phosphorus removal efficiency obtained by CTS addition, CTS was considered as the optimal type of BA. The germination index of Chinese cabbage seeds treated by CO2-rich BS solutions after BA addition was generally higher than 0.8, implying the low phytotoxicity. Therefore, the addition of BA into BS may be beneficial to ammonia nitrogen and phosphorus removal, and may not result in a rapid increase in phytotoxicity.

Abstract:With the rapid development of economy and improvement of people’s living standard, aquaculture was developed rapidly over the past years. And a large amount of livestock wastewater was produced meanwhile. Thus effective treatment of livestock wastewater becomes the much urgent problem to be solved. Anaerobic treatment technology is recognized as one of the most promising wastewater treatment technologies in environmentally sustainable development. The design of anaerobic reactor is the key for developing anaerobic treatment technology of livestock wastewater. In order to describe and simulate the process of anaerobic reaction, guide the optimization of process parameters and design of reactor in the practical production, the kinetic model of livestock wastewater was established. The experiments were carried out in an external loop reactor. The orthogonal experiments with three factors and three levels were designed by taking temperature, matrix COD and pH value as factors. Temperature parameters were introduced to improve the Monod equation, and the dynamic models of matrix consumption and product formation were established. By linear and nonlinear regression, the model parameters and the corresponding dynamic equations were established, and the effects of reaction temperature and substrate concentration on reaction rate were revealed. The results showed that the reaction activation energy was very low, and the effect of temperature on reaction rate could be neglected. Temperature could affect the production rate of CH4 and CO2. The production of CO2 would be increased with the increase of temperature. The new livestock wastewater anaerobic reaction dynamics model could fit the experimental data well, which had positive significance for the development and design of new anaerobic reactor.

Abstract:Due to the long-term summer in southern China, the crops in greenhouses suffer from high temperature seriously. In order to improve the cooling effect and reduce the energy consumption of ventilation, it is necessary to optimize the design and control strategy for the mechanical ventilation system of greenhouses. A full-scale 3-D transient and steady CFD simulation model was established for a typical multi-span plastic greenhouse in southern China. By using evenly distributed temperature, humidity and light sensors inside and outside the greenhouse, the variation and distribution of temperature driven by the mechanical ventilation were measured. The comparison between the experimental and simulation results showed that the CFD model was valid. Under the high ambient temperature, the CFD model was carried out to investigate the impact of design parameters, such as the number of working fans, length of greenhouse, inlet temperature and outside environment temperature, on cooling effect of mechanical ventilation. And then the cooling effect under different control strategies of mechanical ventilation was simulated to reduce the energy consumption. The proposed CFD model can provide optimized parameters for the design and control of multi-span plastic greenhouse mechanical ventilation in summer, which can be applied to improve the cooling effect and reduce energy consumption of ventilation.

Abstract:Crude polyphenols were extracted from two types of grape skins and two wines. Total antioxidant activities and in vitro DPPH free radical scavenging activities of the extracts were evaluated. Meanwhile, the effect of those extracts on angiogenesis inhibition was investigated by using transgenic zebrafish model. After zebrafish embryos were treated with the crude polyphenol extracts for 22h, the inhibitory effect on the intersegmental vessel (ISV) of zebrafish was investigated. The results indicated that the wines and grape skins all had in vitro antioxidant activities. However, the DPPH free radical scavenging activity and total antioxidant activity of wines were higher than those of grape skins. Wine 1 had the highest DPPH free radical scavenging activity (89.42%), which was 1.29 percentage points higher than that of wine 2. Wine 2 had the highest total antioxidant activity of 223.24U/mL. Compared with control groups, zebrafish treated with crude polyphenol extracts of wines had significantly less ISV formation. Wine 1 had better inhibitory activity on ISV and dorsal longitudinal anastomotic vessel (DLAV) formation. However, the crude polyphenol extracts of grape skins showed little inhibitory effects on ISV and DLAV formation of zebrafish.

Abstract:Influence of GA—zein core-shell structure on the curcumin embedding efficiency and status of curcumin after embedding treatment was investigated by taking advantage of the zein delivery functionality and stabilizing with Arabic gum, parameters such as mean particle diameters, zeta potential and absorbance were measured. The result showed that evenly dispersed globular nanoparticles were formulated under low zein concentration condition, as the increase of zein concentration, adhesion, aggregating and meltdown etc. transformation effects were occurred among the nanoparticles. It is necessary to add stabilizer to enhance the stability of zein delivery system. Stabilizing efficiency of different types of stabilizer were compared, and the result showed that stability of GA—zein—cur dispersed system reached peak when the system was stabilized with 0.3g Arabic gum;GA—zein—cur nanoparticles were the most stable when the quality ratio of curcumin and zein reached 1∶10, and the embedding efficiency was 95.90%, an even, stable and highly transparent curcumin aqueous solution was formulated.

Abstract:An artificial olfaction system based on visualization sensor array was employed to identify different ages of vinegar. In the image processing module of this system, the influence of different methods on the localization of the target image center was compared, including minimum enclosing rectangle, ellipse fitting and one-order moment. Since the target image was similar to the circle, all of the three methods could obtain center coordinates exactly, except that the last method consumed less time. Moreover, the characteristic region was reselected, which could better represent features of the target image. Usually, feature values are extracted based on the RGB color space. Then, each component and coordinate value in RGB, HSV and Lab color spaces were extracted and used as eigenvalues. The result showed that the data obtained from the Lab space had high stability. In order to identify different ages of vinegar, five different years of vinegar samples from 2011 to 2015 were selected in the experiment. The characteristic data from three kinds of color spaces was analyzed with principal component analysis (PCA) and linear discriminant analysis (LDA). Although the samples of vinegar in different years had a certain clustering tendency, especially in the Lab color space, there were still some samples overlapping each other and difficult to separate by PCA alone. Then this data was used as the input of LDA classifier for discriminate analysis. The recognition accuracy rate in the training set and testing set achieved 98% and 94% respectively in Lab color space, while the detection accuracies were not higher than 90% in other color spaces.

Abstract:For the purpose of testing the watermelon’s interior quality nondestructively, the sub-band spectrum centroid of the impact vibration response was employed as the characteristic parameter to describe and model the soluble solid content (SSC) and the flesh color of watermelon. A total of 76 watermelon samples were used in the experiments, for both the nondestructive vibration tests and the destructive SSC and color tests. Different impact methods and positions were attempted to validate the robustness of the sub-band spectrum centroid as a characteristic parameter. The results showed that the sub-band spectrum centroid had low dependency on different impact methods and positions, which could greatly simplify the complexity of the testing system. The optimized sub-bands were obtained for modeling the SSC and the a* value of color with determination coefficients of 0.8124 and 0.7336, respectively, which were higher than that when the resonant frequencies were used as the characteristic parameter. Linear models were made for both SSC and a* value. The vibration subband spectrum centroid was gone down monotonously along with the SSC (sub-band 144~416Hz) and a* (sub-band 148~428Hz) value, with the slope of -1.361 and -1.019, respectively. However, the subband spectrum centroid had low ability of describing the L* and b* values in color testing, whose determination coefficients were only 0.52 and 0.148, respectively.

Abstract:The model of air leakage flow was constructed based on air infiltration mechanism of multi-temperature refrigerated truck. Theoretical analyses and experimental measurement were conducted with the established model, such as internal partition coefficient, load coefficient, internal flow disturbance coefficient, heat pressure difference and other parameters. It was shown that the air leakage rate was mainly affected by air tightness of the vehicle itself, speed, internal partition, loading condition and airflow disturbance. Specifically, the internal partition could improve air tightness of the vehicle with diminishing utility. The internal partition coefficient was 0.6~0.9 in double temperature refrigerated truck, and it was 0.45~0.85 in the three temperature refrigerated truck. The internal loading capacity had limited effect on air infiltration. The load coefficient was 0.98, 0.96, 0.92 and 0.87 when load was 25%, 50%, 75% and 100%, respectively. The influences of internal airflow disturbance were different with different speeds. The internal flow disturbance coefficient was 0.68, 0.85, 0.94, 0.97 and 0.98 when speed was 20km/h, 40km/h, 60km/h, 80km/h and 100km/h, respectively. Since the multi-temperature refrigerated truck used for city distribution is often at low speed, the internal circulation wind could stop air leakage at a certain degree. In addition, the heat pressure difference caused by temperature difference between inside and outside of the truck was small because the height of refrigerated truck was small. Theoretical analyses showed that temperature difference of 25K corresponded to pressure difference of 1Pa. Such effect was so insignificant in engineering practice that the air infiltration of refrigerated truck can be regarded approximately as a result of simple wind pressure.

Abstract:During heat pump drying (HPD) of Penaeus vannamei meat physical and chemical changes are destined to occur which result in a decreased quality attributes. However, the mechanism of quality degradation was not explicated. The gravimetric method and differential scanning calorimetry were employed to investigate the moisture desorption isotherm and the glass transition temperature (Tg) of Penaeus vannamei meat, respectively. GAB model and Gordon—Taylor equation were selected to fit the experimental data of desorption isotherm and Tg, respectively. Penaeus vannamei meat was dehydrated at 35℃ and 1.5m/s air velocity by using HPD. The quality attributes (such as hardness, toughness, shrinkage, total color difference and astaxanthin content) were analyzed at time interval of 1.0h during HPD. The mechanism of quality degradation was explicated based on glass transition theory. The results showed that at the present drying conditions, Penaeus vannamei meat sample was in a rubbery state, characterized by a great mobility and remained this state until the end of drying process. The quality attributes were changed as drying continued, which can be related to the rubbery state of matrix during HPD.

Abstract:In order to meet the energy recovery and performance optimization of hydraulically interconnected suspension, a hydraulically interconnected energy-regenerative suspension was proposed. Combined with the structural characteristics of the reverse interconnected suspension, the energy-regenerative mechanism was introduced, and the dynamic model of a 4-DOF vehicle suspension was established. The vehicle dynamic performance and the energy-regenerative effect were simulated by using the joint simulation AMEsim/Simulink. The α-method was used to calculate the weight coefficient of evaluation indexes. The parameters of the spring stiffness and hydraulic cylinder diameter were extracted from eight potential parameters by means of design of experiment to perform optimization with genetic algorithm in Isight. Both vehicle dynamic performance and energy-regenerative effect were optimized. Based on simulative computation, the bench test of full vehicle was carried out under linear condition on a random road using the 4-poster road simulator. The results showed that the vehicle dynamic performance of the new suspension was slightly worse than that of the traditional interconnected suspension, but it can meet the most road conditions and recover part of vibration energy under the premise of maintaining ride comfort.

Abstract:For the deficiency of current electric vehicle regenerative braking, a new-type electromagnetic—mechanical coupled regenerative braking system was proposed. The new-type electromagnetic—mechanical coupled regenerative braking system overcame independent control of friction braking and regenerative braking. Based on the system, two degrees of freedom vehicle dynamic model with the lateral force limitation was taken as reference model. Meanwhile, electric vehicle stability control strategy was proposed based on direct braking input distribution and fuzzy-compensation control. According to the test conditions and evaluation indicators of American regulation FMVSS126, the lateral stability, handling response and braking energy recovery efficiency were analyzed and contrasted with or without ESC control by vehicle dynamic co-simulation platform of Matlab/Simulink and CarSim. The results showed that the vehicle equipped with ESC passed the sine with dwell tests of regulation successfully. The proposed fuzzy-compensation stability control algorithm had better robustness and yaw stability, which reduced the tracking error of vehicle slip angle and yaw rate effectively. The electric vehicle stability control strategy integrated regenerative braking not only can increase the driving safety of electric vehicles, but also had the recovery efficiency. The research results of the new-type electromagnetic—mechanical coupled regenerative braking system were focused on the vehicle stability, and involved with some braking energy recovery.

Abstract:Track terramechanics, of which the track stress distribution is the bottleneck, plays an important role in the areas of track mechanism’s design, optimizing, control and simulation. Semi-empirical method and soil trough experiment were combined. Soil shear flow and distribution of slip line during the movement of track mechanism were analyzed on the basis of KARAFIATH concept. The algorithm of amount of soil loss caused by slip, which was used to correct the traditional track-terrain stress distribution model, was raised. Sinkage data of track gathered from soil trough experiment was input to the established model, and then the distributions of normal and shear stresses were obtained. The experimental system of track mechanism—soil interaction composed of soil trough and track-type trolley device as well as its supporting driving element and real-time test system through which can obtain parameters such as driving moment of the motor, horizontal displacement of trolley, sinkage in the traveling process of the trolley, inclined angle of the vehicle body, and motor speed, as well as the variation from the start to the smooth operation of the trolley device was designed and constructed according to the new test system of soil bin developed by the Key Laboratory of Bionic Engineering of Ministry of Education. Laser range finder was constructed with turnplate to realize the stage extraction of shape of track not in contact with a road wheel. The vehicle load, track width and slip rate were taken as experimental factors, the mechanism sinkage was taken as experimental index, and orthogonal experiment design method was adopted. The relative error between numerical calculation and experiment results of normal stress in vertical direction of track mechanism was less than 15%, and correlation coefficient was equal to or more than 0.83 when the weight was 6kg and slip rate was varied from 0.23 to 0.71. The stress model can be used to build mathematical model of interaction between tracked vehicle and terrain.

Abstract:In order to solve the strong kinematics coupling problem of parallel mechanisms obtained by the normal type synthesis approach, a systematic method for structural synthesis of the uncoupled spatial translational parallel mechanisms (USTPM) was presented based on the actuation wrench screw theory. Firstly, mathematic model mapping the relationship between the inputs and the outputs of USTPM was set up. Secondly, both the actuation wrench screw and actuated twist screw’s forms of the kinematical chains were obtained according to the condition that the velocity Jacobian matrix was a diagonal one. Then the rules to determine the non-actuated screws of the limbs were established in terms of the reciprocal product principle. Both criterion and steps of the limb’s type synthesis were proposed as well. Finally, the mechanisms with the expected motion characteristics were designed by selection three limbs synthesized above to connect the platform and the base. Totally 60 symmetrical USTPMs were designed. Among them, 47 mechanisms were nonoverconstrained and 29 mechanisms were composed of the open single kinematic chains with idle joints. The Jacobian was a diagonal matrix of the synthesized parallel mechanisms. It was more interesting that some mechanisms’ Jacobian was the identical matrix, in which there existed one-to-one linear mapping relationship between the input velocities of the actuated joints and the output velocities of the moving platform for these mechanisms, and condition number of their Jacobians was equal to 1. So these mechanisms showed fully-isotropic throughout their whole workspace. Meanwhile, they performed very well with regard to motion and force transmission. This work contributed to enriching and improving the structural synthesis theory of the parallel mechanisms.

Abstract:A novel 3—PRRR three-dimensional translational parallel mechanism was proposed. Its Jacobian matrix was constant, when its prismatic pairs were chosen as the actuators. The degrees of freedom of the parallel mechanism was analyzed based on screw theory. The forward/inverse kinematic solution models were established to obtain its workspace by the vector method. Jacobian matrix of the mechanism was solved by the main twist screw and transmission wrench screw. Then, the curves of the output speed and force were drawn. According to the figures, the curves were completely coincident in different poses when the input parameters were certain. Thus, the conclusion that the Jacobian matrix of the 3—PRRR parallel mechanism kept constant was verified. On this basis, the transmissibility performance of the mechanism was further analyzed in order to obtain relationship between transmission power and angle β (the angle between axis of the prismatic pair and its nearest pairthe revolute pair ) of each limb. Finally, another important conclusion was got. It can be expressed as: when the input power was definite and invariant, the transmission power of the mechanism was decreased with the increase of β. Comparison was made between output speed and force curves in two cases that β were equal to 0° and 30°, the transmissibility performance of the mechanism varied with β and the former was better than the latter. Similarly, after the transmissibility performances with other values of β were analyzed, the performance was optimal when β was 0°.

Abstract:A fast numerical algorithm for the forward kinematics optimization of 3—RPS parallel manipulator was presented. Through numerical optimization methods, the problem of forward kinematics of parallel robot was inverted to minimization problem. According to the optimization of forward kinematics for 3—RPS parallel manipulator, the forward kinematic functions, which were the multi-objective nonlinear equations with constraint, were built based on numerical method. The fitness function was established to achieve the optimization of single objective, and the minimum optimization was solved based on the global-best artificial bee colony algorithm. The information carried by employed bees was exchanged among the neighboring bees. The position information was exchanged randomly and the neighborhood bees were chosen randomly as the standard artificial bee colony algorithm. In addition, for the global-best artificial bee colony algorithm, the global best bee which carried the best position information would guide all bees to move to the better position, and convergence fast to the best position. As the simulation result of 3—RPS forward numerical kinematics showed, compared with continuous ant colony algorithm and standard artificial bee colony algorithm, the global-best artificial bee colony algorithm was an effective way, which with high precision and high speed, to solve forward kinematics of parallel manipulators.

Abstract:By a combination of the numerical iteration method and the intelligent optimization algorithm, the adaptive weight particle swam optimization with secant method (AWPSO—SM) was presented which was applied for solving the parallel mechanism forward kinematics problems. Then, the 3—UCU (U is universal pair, C is cylindrical pair) parallel mechanism was treated as the research object, and then the detailed solving process of AWPSO—SM was given, namely, the inverse kinematics model of 3—UCU parallel mechanism was established firstly;based on the model, the iterated function and fitness function was designed, and then the forward kinematics of the 3—UCU parallel mechanism was solved by AWPSO—SM.Finally, the effectiveness and accuracy of AWPSO—SM was verified via several numerical examples of 3—UCU parallel mechanism, 3—PPR (P is prismatic pair, R is revolute joint) parallel mechanism and 4—SPS (S is spherical joint) parallel mechanism which were the typical parallel mechanisms in Matlab environment. From simulation results, AWPSO—SM avoids the effects of the local convergence and the initial value on the calculation results, and could solve the forward kinematics of the 3—UCU parallel mechanism effectively. Moreover, AWPSO—SM avoids the complicated derivation process and has simple calculating process. AWPSO—SM has better accuracy with little iteration times and universality than AWPSO and secant method.

Abstract:The effective description method for hand gesture is the most important in intelligent coordination assembly process based on human computer interaction. And effective hand finger knuckle detection is beneficial to the description of hand gesture.The structure characteristics of hand knuckles image are fuzzy and it is difficult to feature modeling. The extraction and learning method of excursion characteristic for hand knuckles image was presented and the hand knuckle was recognized by hand image based on Log Gaussian Cox random image model theory. The approximations of image excursion representation were given combined with level set decomposition of random image when the priori hypothesis was absented in Cox process image model. On the basis of nonparametric kernel estimation of image gray distribution, excursion characteristic was enhanced by nonlinear anisotropic filtering. And the Bayesian form of excursion measurement was established. The model learning and feature fusion algorithm on excursion characteristics with different excursion parameters was presented. And the features fusion representation of hand knuckle image was acquired. The hand knuckles image recognition results with many different hierarchical excursion data models were compared. The knuckle detection algorithm on hand image was presented. The ROC curves statisical law of hand knuckles detection with defferent models showed that the classification ablility of this method was correct and stable.The results also showed that the knuckle recognition ability of the model had some difference for different knuckle categories, and there were some differences in the deep distribution of image data between far knuckles and mid-knuckles. And the method was feasible.

Abstract:Hydraulic valves were designed with two dimensional (2D) concept uniquely integrated pilot stage and power stage into single spool by taking advantage of both translational and rotary degrees of freedom. It was featured with simple structure, excellent anti-pollution capability, high ratio of power to weight and fast dynamic response, which attracted considerable attention in several areas of modern industry. In order to solve the problem that hydraulic servo screw of direct position feedback 2D servo valve had deficiency of complicated structure and high manufacturing cost，a novel paddle wing torque motor with feedback function was proposed. The motor could be used as electromechanical converter and directly connected with spool to constitute a novel force feedback 2D servo valve with simple structure and low manufacturing cost, which was suitable for civil servo valve application. Three types of prototype motors with different inclined angles of paddle wing were manufactured and the test rig was built. The relationships between feedback torque and armature displacement were studied by using methods of magnetic circuit analysis, FEM simulation and experiments. The experimental results were agreed with the simulated results. It was indicated the characteristics between feedback torque and armature displacement were close to linear relationship and its amplitude was raised with the increase of displacement, whose magnitudes reached about 0.098N·m, 0.132N·m and 0.16N·m with paddle wing’s inclined angles of 9°, 12°and 15°, respectively. It was proved that increasing inclined angle was an effective approach to increase feedback torque.

Abstract:Due to the problem of nonlinear and time-varying exists in the model of the pneumatic artificial muscle (PAM) trajectory tracking control system, the modeling of the trajectory tracking control of PAM driven by fast switching valves was detailed in order to enhance the trajectory tracking control accuracy of PAM and reduce the cost of control scheme. A feedback PID controller based on the experimental model of PAM was proposed to achieve its high accuracy trajectory tracking control. The control system was divided into three subsystems, which were pneumatic artificial muscle, fast switching valve and the PWM signal. Firstly, the static model of PAM was established by the isometric experiment, and then the dynamic characteristic model of PAM was developed based on the polytropic equation, in which the air mass flow rate through the fast switching valve was evaluated by using the Sanville equation. The PWM signal that was used to control the fast switching valves was generated referring to the pulse signal modulation method. Sequentially, the pressure and trajectory tracking control models of PAM were derived by means of feedback PID controller, based on which the simulations of pressure and trajectory tracking control were implemented in the environment of Matlab/Simulink. The results indicated that the control model can achieve satisfactory performance and accuracy, which validated the feasibility of the proposed model and control scheme. Thus, it provided an effective approach for high accuracy trajectory tracking control of PAM.

Abstract:It’s essential to establish a dynamic model of flexible multi-link mechanism with clearance for ultra-precision press to analyze its dynamic response. Traditionally, the rigid model of multi-link mechanism often neglects the effect of revolute and spherical clearance joints, and flexibility of crank shaft and linkage, which reduces the analysis precision. To investigate its dynamics more accurately, an improved dynamic model of flexible multi-link mechanism with clearance was established, which considered the effect of revolute and spherical clearance joints, and flexibility of crank shaft and linkage. It was demonstrated that the revolute and spherical clearance affected the dynamic response of the mechanism dramatically and the motion of the crank shaft center and ball center of spherical joint were mainly characterized by only two phases: free flight and impact motion. In addition, the influence of the clearance size and speed of crank shaft on the dynamic characteristics of the multi-ink mechanism was also investigated. The results showed that with the increase of the clearance size, the position of the slider’s lower dead center was moved up simultaneously, the peak values of velocity and acceleration were decreased to a minimum and then increased with the increase of clearance size and speed. With the increase of crankshaft speed, the position of the slider’s lower dead center and the maximum deviation value were also increased gradually, and the values of velocity and acceleration were increased significantly.

Abstract:Installed between the motor’s shaft and the hoist power input one, an integrate sensor could output not only the total torque signal related to the change for hoist’s load but also 60 pulses per revolution for motor’s shaft. The hoist’s opening could be calculated by associating the number of those pulses with some parameters of the hoist. In the integrate sensor, those rotary circuits could be powered from the rotary secondary of transformer whose primary was fixed with the sensor’s metal shell, which was used as a part of magnetic core of the transformer. By using the photoelectric coupling method, non-contact transmission for the sensor’s signals about the total torque and the opening was realized. Besides the torque caused by constant load, the total one also included some other torques shown as fluctuation and unsteadiness because of those factors, such as friction existing in the hoist’s mechanical structure. In order to get the actual load from the total torque signal, two phases were selected for hoist’s load detection. Firstly, the analog-to-digital converter (ADC) output value corresponding to the total torque was corrected though gray correlation analysis, and the corrected ADC value whose fluctuation and unsteadiness had been greatly reduced was selected to be as the result of the first phase. In the second phase, by using the result of the first phase as input variable, the hoist’s load predicted model was founded according to the least square support vector regression (LS—SVR) or partial least square regression (PLSR). Taking the first predicted value as the expected data sequence and implementing the correction based on the gray correlation analysis again, the hoist actual load was finally attained. Experiment result showed that the error of the result of load detection was less than ±0.6% for LS—SVR and below ±1% for PLSR model cooperated with the correction based on the gray correlation analysis. Meanwhile, since the integrate sensor was directly installed between the motor shaft and the hoist one, the number of pulses would be greatly increased during the hoist’s moving up and down which could well improve the opening detection resolution. The resolution of the hoist opening detection was far below 1mm.

Abstract:In order to reveal the characteristics of droplet mixing in a microfludic T-junction, the dynamic mixing process in droplet was studied by numerical simulations and experiments. The microfluidic chip was manufactured by soft lithography based on polydimethylsiloxane (PDMS), and the experiment phenomena of droplet formation and mixing process were analyzed with microscope system. The research results showed that the mixing efficiency was significantly influenced by the twirling effect which controlled the initial distributions of mixture during the droplet formation stage. While the droplet was separated from the dispersed phase in the junction region, the combined effect of viscous shear exerted by the continuous phase and the re-orientation of flow induced a vortex in the dispersed phase. As the two-phase interface in the droplet was rotated by the twirling effect, the mixed solutions were distributed to the front and back parts of the droplets. Therefore, the internal recirculation flow can bring in convection mechanism thus improving mixing. The twirling effect was noticeably influenced by the velocity of continuous phase. When the velocity of the continuous phase was slow, the twirling effect cannot distribute effectively for long droplets because of the large amount of fluid contained in the droplets. In contrast, the twirling effect appeared to be very effective for short droplets as the amount of fluid was small. When the flow velocity of the continuous phase was 0.04μL/min, the mixing index was 0.82, which was two times higher than that of the mixing index when the flow velocity of the continuous phase was 0.005μL/min. This study provided the insight of droplet formation and mixing performance inside the droplet in droplet-based microfluidics and it should be helpful for microdevice design and optimization.

Abstract:With the wide application of microchannel heat exchanger, more and more researches focus on the microchannels and the pressure drop characteristics are important research object. Pure refrigerant R141b was used as working fluid in microchannels to carry out boiling flow experiments and explore the effect of surface energy on flow boiling pressure drop characteristics. Fluoroalkylsilane solution in different concentrations was used to modify the surface energy of different microchannel tests with size of 2.0mm×1.0mm, and tests were obtained with different surfaces energy. The flow boiling pressure drop characteristics were experimentally investigated through the tests by using R141b refrigerant. The influence of surface energy on pressure drop were investigated, and then a modified model was got. The results showed that the surface energy of tests were low with long immersion time and high concentration, and the tests with low surface energy had big numerical value of frictional pressure drop. The twophase frictional pressure drop was increased by 5.1% and 12.7%, respectively. The predicted values of different correlated models were compared with experiment values, and a modified model which had a better predicted result was obtained, the mean absolute error was decreased obviously. The result provided supplement for the research on flow boiling resistance characteristics.