Abstract:There were some problems of artificial and sensor measurement for tree canopy volume, such as inefficiency, low precision, high cost, complex operation. In order to solve those problems, a new measurement method based on machine vision was proposed. The previous research indicated that there was significant correlation between tree canopy area and canopy. Based on this, the new method was proposed. Firstly, tree canopy image was obtained by machine vision according to the set standards. Secondly, tree canopy area was extracted by using a series of image processing operations. Meanwhile, the least square method and the 5-point calibration method were used to obtain the model of tree canopy volume. Finally, the corresponding volume was got. Experimental result showed that the average prediction error of the model of pear tree and Osmanthus fragrans were 13.73% and 10.18%, respectively. In view of the conditions of tree canopy, the structure estimation method was used to fit ellipsoid structure according to the contour of tree canopy that without a series of samples. Then, the volume of tree canopy was got by the compensation formula. Experimental result showed that the average prediction error of the model of peach trees and Osmanthus fragrans was about 10%. Consequently, characteristics extraction method of fruit tree canopy images was effective and feasible. The tree canopy volume characteristics can be perfectly expressed by tree canopy area and contour.

Abstract:In farmland with complex environment, guidance line recognition of agricultural machinery based on machine vision is subjected to illumination variation, weed noise, etc. In addition, the conventional path detection algorithms have the drawbacks of low processing speed and poor anti-interference. The visual navigation path detection under natural environment was conducted. Firstly, to reduce the influence of illumination changes on the quality of image segmentation, Cg component was constructed on the base of YCrCb color mode and the 2Cg—Cr—Cb factor was selected to preprocess the image. Secondly, the clustering segmentation of the image was performed based on improved K-means algorithm to achieve the respective clusters of soil and green crop information. Then, the weed interference information in the binary image was eliminated by morphological filtering algorithm so as to obtain the complete and clear crop information. Finally, according to the characteristics of the crop rows in the image, linear equation constraints of crop rows were established. An algorithm of crop lines detection based on particle swarm optimization (PSO) was designed. Experiment results showed that the image segmentation based on 2Cg—Cr—Cb gray image can effectively identify crop from soil background under different illumination conditions. The segmentation images were less affected by change of illumination and no background noise was contained. The guidance line recognition method based on PSO can quickly and accurately detect the navigation line. Furthermore, it had good fitness for different crops and nice adaptability for different crop growth stages in the farmland. Compared with conventional guidance line recognition algorithms, the designed algorithm had the advantages of high speed and good robustness.

Abstract:A combined algorithm for image recognition and boundary segmentation of overlapped objectives under natural and unstructured environments was proposed. The algorithm dealt with the challenging problem of image processing applied to the agriculture with complicated external factors, such as illumination changes in unstructured natural environment, objective feature overlapping. Firstly, the image noise on the original image received from the camera was filtered out using bilateral algorithm. Secondly, overlapped objectives in the filtered image were recognized by OTSU algorithm based on the improved operator. Then the single object position was obtained by using K-means clustering algorithm on the pixels of the overlapped objectives. Afterwards using Sobel operator or Canny operator, the approximate area of the single object was recognized by connected domain analysis on the edge detection results and the domain growth. Finally, after internal and external reception basins received from the area of the object, the position of the single object boundary was confirmed, the precise contour of the single object was obtained by using watershed algorithm on the restricted area which was the area between internal and external reception basins. In order to verify the effectiveness and applicability of the proposed algorithm, several experiments were carried out, and only two experiments were shown due to the limited space. The first experiment chose a relatively simple image with overlapped tomatoes under the simple image composition, the second experiment chose a complicated image to further verify the adaptability of the algorithm. The experimental results showed that the proposed algorithm can recognize the overlapped objectives under natural environments and it can also segment the single object from the overlapped objectives.

Abstract:In order to explore the internal flow characteristics of mixed-flow pump and optimize and improve the design method of the mixed-flow impeller and guide vane, the internal flow field of mixed-flow pump was measured based on the particle image velocimetry (PIV). The streamline and velocity distribution of impeller section at different phases and the vorticity distribution under small flow rate conditions were analyzed. The results showed that radial trend of flow was appeared in the impeller due to influence of vortex flow on the blade pressure surface and flow separation of suction surface under small flow rate conditions, and the flow was turbulent. With the increase of flow rate, the streamline was turned gradually in the axial direction and flows along with the contour line of hub. Under the large flow rate conditions, the vortex structures near blade pressure surface and close to the wall were obvious. At 0.6 times of the working condition, when impeller inlet came to the shooting section, clockwise rotation vortex was formed within the impeller; when impeller outlet came to the shooting section, the positive vorticity concentrated area appeared near the guide vane inlet edge and this region was moved in the inlet direction with rotation of impeller. When the blade outlet kept away from the shooting section, the negative vorticity concentrated area was appeared near the guide vane inlet. The causes of mixed-flow pump energy loss were revealed during the process of rotor-stator interaction between impeller and guide vane. The research results provided reference for revealing the internal flow characteristics and expanding the operation ranges of the mixed-flow pump.

Abstract:The unsteady numerical method was applied to simulate the flow field and pressure field in the single-stage centrifugal pump with vane diffuser by using SST k—ω turbulent model. The static pressure recovery, energy loss and pressure fluctuation in the diffuser and volute were analyzed and the results showed that the performance using the numerical method was in good agreement with data obtained from experimental investigation. The total pressure loss and static pressure recovery in the diffuser and volute presented periodic fluctuation due to interaction between impeller and diffuser, and they were much bigger than those in volute. The pressure loss in vane diffuser was increased as the increase of flow rate. The static pressure recovery was got small as the flow rate came large. Pressure loss and pressure recovery in volute presented the same trend. The difference between the maximum and minimum pressure losses was increased as the increase of operating flow rate, as well as the pressure recovery. The pressure pulsation intensity distributed on impeller was got stronge as the increase of operating flow rate. The pressure pulsation intensity distributed on guide blade was increased at low flow rate and reached the maximum value, and then it was decreased as the increase of flow rate. The large number of vorticity in the diffuser moved to exit was induced by the vane leading edge, but it was provoked by the vane trialing in volute. The maximum pressure fluctuation intensity coefficient (Csdv) in impeller was concentrated at the impeller exit, and it was concentrated on the vane leading edge and the volute exit in the diffuser and volute, respectively.

Abstract:Experiment and numerical simulation research were conducted on a designed mixed flow pump with the low specific speed of 148.8. By comparing the mixed-flow pump performances at different flow rates, the numerical results and the test results were in good agreement. Monitoring points in the internal flow field were set to capture the pressure fluctuations from rotor-stator interface to the guide vane exit in both the experiment and the numerical simulation. Through analyzing the pressure fluctuations of mixed flow pump at the different flow rates, the pressure fluctuations in guide vane were mainly affected by impeller rotation, and the frequency was impeller blade frequency. From rotor-stator interface to the guide vane exit, the average pressure was increased gradually, and the amplitude of pressure fluctuations gradually became weaker. At the off-design points, the pressure fluctuations became more complex. At low flow rate, there were many low frequencies of the vortex fluctuation with low amplitude, which was consistent with flow field in the test. At high flow rate, the main frequency was also the impeller blade frequency, and there were some low frequencies of the vortex fluctuation with low amplitude, which were better than the low flow rate. These results can be useful for further optimization design of mixed flow pump.

Abstract:At present, tobacco topping and sprout inhibition is mainly by artificial means, existing machinery can only be achieved ‘make it rigidly uniform’ . In order to improve work efficiency of tobacco topping and sprout inhibition, to reduce labor intensity，the machine vision technology is applied to tobacco topping and sprout inhibition operation, to realize intelligent detection of tobacco height. Firstly, the color characteristics of tobacco leaves and tobacco flowers within the visible light band were analyzed, and the dyeing cloth similar to green leaves was selected as image background by using Pantone which can reduce the extraction difficulty of tobacco flower. Then the common camera was used as the image acquisition device, and the industrial control computer was used for processing the color characteristics of the collected image. Based on single line adaptive threshold value judgment method and taking volume as a unit, R value and G value of different characteristics were used to find the location of tobacco flowers, according to the proportion relationship to determine the specific topping height. Finally, the industrial machine was combined with microcontroller to control the stepper motor and solenoid valve, so as to realize the real-time online tobacco topping and sprout inhibition. The test shows that the intelligent tobacco topping and sprout inhibition machine operation efficiency is 2~3 seconds per tree, tobacco flower detection accuracy is about 96％, topping accuracy rate is about 90%, sprout inhibition accuracy rate is about 80%, the machine can meet the design requirement, and can effectively improve the operating efficiency and operation effect.

Abstract:Currently, the automation level of sand samplers used for farmland soil wind erosion is very low. In addition, they can’t record the sediment data real-timely and have no functions of wireless transmission and networking. So it brings many difficulties and other issues to the study on motion characteristics of the soil wind erosion particles at different stages in the transport process. To solve these problems, a new type of automatic multi-channel wireless sand sampler based on wireless sensor network technology and the reverse hedge sand separator was designed. It was dedicated to study agricultural soil wind erosion and realize these functions of automatic acquisition of quantity of soil wind erosion, wireless transmission and real-time data processing. The results showed that the system can circularly scan up to six testing points, the eight channels of each testing point and automatically collect wind erosion data, and the maximum response time was no more than 2s. The rotating start-up wind speed of the sand sampler was 3.4m/s, and the maximum weighing range was 0~180g; the precision of weighing sensors was up to 0.01g and 10 hours continuous measurement error was within ±0.04g with sampling efficiency more than 85%. The length of data packet was 32 bytes and the effective transmission distance can reach 1000m under the conditions of 1kb/s transfer rate and maximum transmitting power. Communication setup time was less than 5s. The system had advantages of low power consumption, easy to use, simple operation and automatic data acquisition, it can meet the needs of research on farmland soil wind erosion.

Abstract:A variety of harvesting machines were developed to finish different harvesting works，such as combine-harvester for wheat and rice, harvesting boat for aquatic plants in rivers and lakes, trailer mower for grassland. But these machines are not suitable for aquatic plants growing in orderly arranged pools in large-scale greenhouses, which are used to purify tail water from sewage plants, because water in these pools is deep and space inside greenhouses is not enough for these machines to work in. Additionally, combustion engines are usually used to supply power for existing harvesters, consequently noises and exhaust pollution are serious problems in closed greenhouses. Aquatic plants grow rapidly and need to be cut regularly, which need a lot of labor. To satisfy the need of plants harvesting in greenhouses, research work on the functions, the basic structure, as well as the design of electric control system of a new type of harvester were done. A group of batteries was used in the new harvester to supply power for motors, which were used to drive cutting device, walking system and rotating mechanism separately. When it was working, the harvester walked along two parallel tracks above pools in greenhouses, cut grass in pools and transferred the grass from the left to the right, and then laid down grass on passages between two adjacent rows of pools. By experiments and calculation, the key parameters for the above mentioned mechanisms, such as main sizes, cutting power consumption, motor power, and walking speed were decided. Harvesting tests showed that when the machine walked at 0.75~0.92m/s and average cutting speed of the cutter was 0.92m/s, good results can be achieved, there were no repeated-cutting or uncut areas. Harvesting efficiency reached 7500~9000m2/h, which was more than 20 times of artificial work.

Abstract:With the impact of rainfall, soil nutrient transported along soil particles and water into surface runoff. It decreased soil fertility, polluted water resources in surface and ground, and then induced a series of ecological environmental problems, which attracted more attentions of researchers at home and abroad. The objectives of the study mainly focused on the development of both the mechanism and controlling measures of soil nutrient transport proposed by researchers all over the world. For the mechanism, the impact of different factors on soil nutrient transport was mainly discussed, and the empirical models and physical based mathematical models were also discussed. Besides, all mentioned physical based models were based on the inner mechanism of nutrient transfer, including the theory of mixing depth, convection and dispersion, the impact of raindrop and water scouring. For the controlling measures, methods protecting soil and nutrients from erosion and runoff were proposed with consideration of serious erosion phenomenon in China. Meanwhile, the existed problem and further study work were also discussed.

Abstract:It is one of the important ways of solving water shortage to develop the drip irrigation technology. However, a series of problems brought by the rapid development need rethink profoundly. Based on the description of the drip irrigation technology application status and policy support to develop the drip irrigation, the environmental problems brought by the great success of drip irrigation technology used in Xinjiang Province were described in detail. A low-carbon environment friendly drip irrigation technology system is necessary, whose basic connotation is to realize the goal of “three lows and two highs”, including “low-energy”, “low-pollution”, “low-emission”, “high-effect” and “high-benefit”. At the same time, the key technologies were stated in detail. The technology of “consumption reduction” contains self-pressure drip irrigation technology and construction technology for low-pressure or micro-pressure drip irrigation system. The technology of “pollution abatement” contains security drip irrigation with poor quality water and drip irrigation with biodegradable mask or under mulch. The technology of “emission reduction” contains emission reduction of farmland greenhouse gas in drip irrigation and drip irrigation with clean energy to get water. The technology of “effect-raising” contains treatment technology of water quality, sedimentation and filtration technology, and product development of long-lasting anti-clogging drip irrigation emitters. The technology of “high-gain” contains irrigation with integration of water and fertilizer and so on. Eventually, the future research priorities and the key issues need to be resolved about low-carbon environment friendly drip irrigation technology were proposed.

Abstract:The soil nitrate-nitrogen (NO-3-N) is essential element for crop growth. Because of the obvious advantages on cost, applicability and easy-implementation, the nitrate ion-selective electrode (ISE) was demonstrated potentials in both laboratory and in-field researches on soil available nitrogen detections. However, problems of unidealistic selectivity and potential drift usually limited the application of ISE. The extreme learning machine algorithm was used to decouple the signals of nitrate ion-selective electrode from the interference of chloride. Three data processing algorithms, including drift correction, Nernstian model and extreme learning machine were systemically analyzed. Experiments were carried out on the self-designed multi-channel nutrient detection platform. Totally 150 soil samples were selected for the system validation. The experimental results indicated that the accuracy and consistency of sensor’s scaling equations were effectively improved by drift correction algorithm. The variations of response slope and intercept potential were reduced by 3.67% and 7.25%, respectively. The neuron number in hidden layer of the extreme learning machine was 14，which were tested as optimized parameter. The extreme learning machine could effectively decouple the interference of chloride from nitrate ion-selective electrode in saline alkali soil. The maximum absolute error and root mean square error were 6.36mg/L and 4.02mg/L, respectively. In conclusion, the research results can provide references in the related studies for soil detection by ion-selective electrode.

Abstract:To evaluate the applicability of farmland irrigation and drainage in southern Xinjiang, adopting the experiment of water supplied by Markov bottle, of fixed disc infiltrometer, of cotton indoor seeding and growth, the effect of farmland irrigation and drainage on infiltration characteristics of the soil water at point source and non-point source, cotton emergence rate and growth was studied. The experiment results showed that during the test of soil water point source infiltration, the horizontal migration at different salinity irrigation water infiltration was more obvious than the longitudinal direction. When drainage salinity was over 2g/L, the soil water content values in the horizontal direction showed a significant downward trend with the increasing of salinity. During the test of soil water non-point source infiltration, the amount of soil water infiltration decreased with the increasing salinity at the same water head. And the amount significantly decreased with the decrease of water head. According to steady-state non-point source infiltration, soil saturated hydraulic conductivity Ks increased first and then decreased after different salinity irrigation, but the model parameters λc changed oppositely, when drainage salinity was at 2g/L, Ks and λc reached inflection point, and the effect was more obvious with the higher salinity. The cotton had a normal growth when water salinity was below 3g/L, while there was a obvious damage to the cotton emergence rate when it was at 5g/L. There was a low effect on cotton seeding growth when the salinity was below 4g/L, however, cotton growing was slowed significantly when the salinity was over 4g/L.

Abstract:To make effective use of shallow ground saline water resource for relieving the water crisis in Hebei Low Plain, a three-year field experiment was conducted to study the effects of irrigation with saline water of different salinities on soil water and salt contents, soil evaporation, stage water consumption of cotton, seed cotton yield and water use efficiency. The experiment included four treatments with different salinity levels of 1g/L, 3g/L, 5g/L and 7g/L of irrigation water, which were denoted as S1, S2, S3 and S4. Results showed that during cotton growing period, soil water and salt contents were increased with the increment of irrigation water salinity, especially for soil salt content. Significant differences of soil water and salt contents for each treatment were appeared during experimental years. In wet years, soil water content of root zone was high and a large proportion of salt was leached out; while in arid years, soil water content in root zone was low and salt was accumulated. After threeyear continuous irrigation with saline water, soil salt content in cotton root zone was not accumulated year by year. During the whole growth period, average soil evaporation intensity was higher in S3 and S4 treatments than that in S1 treatment, but there was little difference between S1 and S2 treatments. Irrigation with saline water of salinity lower than 7g/L had a certain influence on cotton water consumption process, but the differences in total water consumption were not significant. S2 treatment obtained the highest average seed cotton yield and water use efficiency, which was followed by S1, S3 and S4 treatments. Compared with S1 treatment, the average seed cotton yield and water use efficiency of S2 treatment were increased by 2.43% and 1.15%, and those for S3 and S4 treatments were decreased by 1.67% and 0.25%, 8.88% and 7.31%, respectively. There were no significant differences in seed cotton yield and water use efficiency among S1, S2 and S3 treatments, however, those for S4 treatment were significantly reduced. The study can provide important theoretical support for developing the use of shallow ground saline water resource in cotton irrigation.

Abstract:Water and fertilizer are the two important material resources in agricultural production, which are closely related to the yield and quality of crop. In order to discuss the effects of water and fertilizer coupling on growth, yield and quality of grape under drip irrigation with film mulching, the experiment of fertilization under drip irrigation with film mulching was conducted in plastic greenhouse. There were four irrigation levels with irrigation depth of 180mm (W1), 270mm (W2), 360mm (W3) and 450mm (W4), respectively; and four fertilization levels, including N 150kg/hm2+ P2O5 120kg/hm2+ K2O 165kg/hm2 (F1), N 225kg/hm2+ P2O5 180kg/hm2+ K2O 248kg/hm2 (F2), N 300kg/hm2+ P2O5 240kg/hm2+ K2O 330kg/hm2 (F3) and N 450kg/hm2+ P2O5 360kg/hm2+ K2O 495kg/hm2 (F4). A total of 16 treatments were designed. The experimental results showed that the new shoots of grape plant under the treatment F2 with W2 grew better among the treatments, and the chlorophyll content in grape leaves was at a high level in the whole growth period, which was 3.28mg/g, 3.77mg/g,3.65mg/g and 3.53mg/g at new shoots growth, anthesis, fruit enlargement and fruit coloring stages, respectively. The fruit shape index of treatment F3 coupled with W4 was the highest among all treatments; however, the differences between each other groups were not significant except treatments F1W1 and F1W2. In addition, the analysis of fruit yield and quality indicated that the grape fruit yield of treatment F2W2 was not the highest, but there was no significant difference between the yield of treatments F2W2 and F2W3, which got the highest yield. Besides, the fruit quality of treatment F2W2 was more perfect compared with the other treatments. The soluble solids content of fruit of treatment F2W2 was the highest among all treatments, which reached 19.64%. The soluble sugar content and hardness index of fruit of treatment F2W2 also showed advantage, which were 17.00% and0.71kg/cm2, respectively. Comprehensive analysis results showed that the fertilizer application rate of treatment F2 coupled with irrigation depth of treatment W2 had a positive significance on increasing yield and improving quality of grape fruit.

Abstract:In order to determine an optimal fertilization depth for winter oilseed rape (Brassica napus L.), barrel experiment was conducted in 2013—2014 and 2014—2015 with six treatments, including no fertilizer (F0), and fertilization depths of 0cm (CK), 5cm (D5), 10cm (D10), 15cm (D15) and20cm (D20). The effects of different fertilization depths on above-ground dry weight of taproot and lateral root, and the length, volume, area of lateral root, nutrient uptake and yield of winter oilseed rape were systematically analyzed and compared. The results showed that D15 treatment significantly increased the taproot dry weight in 5~20cm and deeper than 20cm soil depths, while the reduction of taproot dry weight in 0~5cm soil depth was not great compared with CK and D5, thus the total taproot dry weight was significantly increased. The maximum lateral root dry weight, length, volume and area in the 10~20cm soil layer at both seedling stage and flowering stage were found in D15 treatment, which were also significantly higher than those in CK and D5. Above-ground dry matter and shoot nutrient uptake in D15 were the highest at both flowering and harvest stages of all the treatments, and D15 treatment achieved the greatest rapeseed yield and the most N, P, K uptakes in the seed at harvest, while the above-ground dry matter, shoot nutrient uptake, rapeseed yield in CK and D5 were significantly lower than those in D15 treatment. Compared with CK, the N, P, K uptakes of shoot at harvest in D15 treatment across the two growing seasons were increased by 48.07%, 52.18%, 62.96% and 25.75%, 30.19%, 33.41% in comparison with D5 treatment, respectively. In two growing seasons, the yield in D15 treatment was 85.10%, 45.47% and 31.26% higher than those in CK, D5 and D10, respectively. Considering the root distribution, nutrient uptake and yield of winter oilseed rape among all the treatments, fertilization depth of 15cm (D15) could be recommended as the optimal fertilization depth in oilseed rape cultivation.

Abstract:Field experiments (2013 and 2014) were carried out to improve nitrogen use efficiency and decrease nitrate nitrogen leaching for summer maize. Two nitrogen fertilizers, including urea (with nitrogen application rates of 0, 80, 160 and 240kg/hm2, 40% of nitrogen fertilizer was applied as basic and 60% of it was top dressed at bell stage; namely N0, N80, N160 and N240) and controlled-release fertilizer (with nitrogen application rates of 0, 60, 120, 180 and 240kg/hm2, all applied as basic fertilization; namely K0, K60, K120, K180 and K240) were chosen to investigate the effects of different nitrogen application rates on root growth, yield, nitrogen absorption and nitrogen use efficiency of summer maize and nitrate nitrogen distribution in soil. The results showed that characteristic parameters of summer maize root at filling stage presented a trend of increase and then decreased along with the improvement of nitrogen application rate for both of the two nitrogen fertilizers. The characteristic parameters of summer maize root were higher in N160 of the urea treatments and higher in K120 of the controlled-release fertilizer treatments than those of the other treatments. In addition, compared with root surface area, total root length and yield had higher correlation. This meant that root length of summer maize played an important role in yield improvement under different nitrogen application rates. Furthermore, the nitrate nitrogen accumulation of the controlled-release fertilizer treatments agreed much better with the plant requirement for nitrogen than that of the urea treatments. In contrast to urea treatments, nitrate nitrogen content of the controlledrelease fertilizer treatments had less variation and the maximum nitrate nitrogen content was shallower in 0~200cm soil layer at harvest. Among the two nitrogen fertilizers treatments, N160 and K120 had greater yield, nitrogen harvest index and nitrogen use efficiency than other treatments. And K120 was potential in saving fertilizer and increasing efficiency, which could averagely increase nitrogen harvest index by 5.38% and improve nitrogen use efficiency by 4.96% compared with N160 in two years. In conclusion, the nitrogen application rate of treatment K120 was appropriate for summer maize cultivation in Guanzhong Region, Shaanxi Province.

Abstract:The effects of environmental factors, such as soil moisture (SW), air temperature (T), air relative humidity (RH) and photosynthetic active radiation (PAR) on stomatal conductance (Gs) and total hydraulic conductance of soil—plant system (Kt) under steady flow condition were analyzed, and regulation effects of these impact factors on plant transpiration were investigated. Greenhouse cucumber was used as the experimental material, based on the design of composite quadratic orthogonal regressive rotation where the artificial climate box was adopted, the main effects, single effects and marginal effects of four environmental impact factors on Gs and Kt were interpreted. The results showed that all environmental factors exerted positive effect on Gs and Kt, interaction effect was also found between SW and PAR, T and RH on Gs and Kt. The single effect of RH can be described by a parabolic function and those of other impact factors were described as linear function, which were increased with increase of Gs and Kt. The marginal effects of each impact factor on Gs and Kt showed that RH was the main regulating path for Gs, and all the impact factors except PAR efficiently regulated Kt. The regulating effects of the four environmental factors, Gs and Kt on transpiration were analyzed with paths and correlation analyses. The results showed that T, PAR and Gs mainly exerted indirect positive effect on transpiration bystrengthening Kt, which was followed by the direct positive effect on transpiration. SW mainly exerted indirect positive effect on transpiration by strengthening both Kt and Gs. RH exerted direct negative effect, while its main effect path was exerting indirect positive effect on transpiration by promoting Gs and Kt. Both Gs and Kt were remarkably responded to the four environmental impact factors and interactively regulated the transpiration synergistically.

Abstract:To explore soil shrinkage characteristics during soil drying process, loam soil from Shandong Province (SD) and silty clay loam soil from Shaanxi Province (SX) were selected. The initial bulk density of the two different types of soil was set at 1.30, 1.40 and 1.50g/cm3. A centrifuge method was adopted for soil—water characteristic curve measurement, and the axial and radial shrinkages during drying process were measured and quantitatively analyzed. Results showed that firstly, as for SD and SX soils, soil moisture was decreased with the increase of suction, but the decreasing range was different due to different bulk densities. When suction was increased from 0 to 7000cm, soil moisture was decreased with different rates. Secondly, linear shrinkage ratio increased with decrease of soil moisture during drying process, and the nonlinear relationship between linear shrinkage ratio and soil moisture could be well fitted by the Logistic model, with high determination coefficients (R2) ranged from 0.96 to 0.99. Thirdly, axial shrinkage strain (δs), radial shrinkage strain (δr) and volume shrinkage strain (δV) all decreased with the increase of soil bulk density. And further analyses indicated that the mainly shrinkage characteristics for SD and SX soils were horizontal shrinkage and vertical shrinkage, respectively. Meanwhile, correlation analyses showed that δs, δr and δV were all negatively correlated with sand content and positively correlated with silt and clay contents. And the correlation between the three types of shrinkage strains (i.e., δs, δr and δV) and soil particle content was obviously influenced by bulk density. Detailedly, as for SD soil, δs and δr were significantly correlated with clay and silt contents, however, δV was significantly correlated with sand content; as for SX soil, δs, δr and δV were all significantly or highly significantly correlated with sand and silt contents, but there was no significant correlation with clay content.

Abstract:In order to evaluate the reliability and applicability of dual crop coefficient approach on calculating actual evapotranspiration and crop coefficient of fruit tree in the North China Plain, the evapotranspiration and crop coefficient of peach tree were measured by sap flow and water balance methods in an orchard of Beijing, China in 2012 and 2013, and the corresponding values were also calculated by dual crop coefficient approach. Experimental results showed that daily evapotranspiration rates calculated by dual crop coefficient approach and measured by sap flow and water balance methods were increased firstly and then decreased with time during peach tree growth period, and the calculated values had significantly positive correlation with those obtained by the twp measurement methods (R2>0.77** and R2>0.76**). The relative error of total actual evapotranspiration in the whole growth period calculated by dual crop coefficient approach was less than 4.5% compared with the measured values by sap flow and water balance methods, but the calculated soil evaporation was 59.5%~64.8% smaller than that measured by micro-lysimeter, and the calculated transpiration was 25.6%~26.0% greater than that measured by sap flow method. The crop coefficients obtained by dual crop coefficient approach, sap flow and water balance methods also showed a increasing trend firstly and then they were decreased with time during the growth period of peach tree, and the average values during the whole growth period were 0.90, 0.89, and 0.95, respectively, for dual crop coefficient approach, sap flow and water balance methods. By calculation and analyses on the ratio of root mean square error to the standard deviation of measured data (RSR) and the Nash—Sutcliffe efficiency (NSE), it can be concluded that dual crop coefficient approach is an effective method to calculate actual evapotranspiration and crop coefficient of peach tree under full irrigation in arid and semi-arid areas.

Abstract:Quantitative expression of spatial and temporal variability of crop information is an important step to realize distributed control of water and soil resources in precise agriculture. In order to reveal spatial and temporal variability of crop information in corn field in black soil region, multifractal characteristics of crop information, multi-scale correlations between crop information of different sampling dates and the ones between different crop information were studied with multifractal and joint multifractal methods based on the results of experiments in 48m×48m field in Xiangfang Experimental Base of Northeast Agricultural University. The results showed that multifractal characteristic of corn chlorophyll content was not obvious, and stem diameter and plant height had obvious multifractal characteristics. As sampling date changed, the local information that caused spatial variability of chlorophyll content and stem diameter were different, the ones that caused spatial variability of plant height were the same, spatial variability intensity of chlorophyll content and stem diameter was firstly decreased and then increased, and that of plant height was reduced gradually. At the single scale and multi-scale, when sampling date was different, correlation degrees between chlorophyll contents were different, there was difference in correlation degrees between stem diameters, and correlation degrees between plant heights were different; there was difference in sorting of correlation degree of chlorophyll content, stem diameter and plant height. As sampling date changed, correlation degrees between different crop information at the single scale and multiscale were different, which were decreased gradually. Compared with research results at the single scale, the correlation degrees between chlorophyll contents were increased, the ones between stem diameters were enhanced, the ones between different crop information were augmented, and correlation degrees between plant heights were sometimes increased or decreased at multi-scale.

Abstract:Free search (FS), which was set up based on the group of animal behavior, was adopted as an optimization algorithm to calibrate the Sacramento (SAC) model and the Xin’anjiang (XAJ) model. Calculation of the calibrated SAC model and XAJ model were conducted for the three watersheds of Songhua River System and Liao River System. Applicability of the SAC model was validated in cold and arid regions of Northeast China via comparison of the simulation results between the SAC model and XAJ model. The results indicated that the iterative calculation process of FS was simple and needed a few settings of the algorithm parameters, and it exhibited relatively high efficiency in the process of SAC model and XAJ model calibration; the simulation result of the SAC model was better than that of the XAJ model under the same conditions and its Nash—Sutcliffe model efficiency coefficient was higher than that of XAJ model. Whereas, the simulation accuracy of the SAC model needed to be improved in the case of application to the cold and arid region of Northeast China, and the performance of the SAC model needed further development and improvement.

Abstract:Urbanization caused hydrological change and increased stormwater runoff volumes, which led to flooding, erosion and the degradation of instream ecosystem health. Low impact development (LID) options had been proposed as an alternative approach to mimic the natural flow regime by using decentralized designs to control stormwater runoff at the source, rather than at a centralized location in the watershed. Hydrological regulation performances of these LID practices can be influenced by rainfall characteristics, such as rainfall intensity and duration. To evaluate the impacts of different rainfall reappearance periods, rainfall analysis was conducted to determine the rainfall characteristics and SCS II type was selected for the analysis. A modeling approach based on SWMM was described to incorporate these LID practices into an existing hydrological model to estimate the impacts of LID practices on the surface runoff. Results demonstrated that the LID practices led to significant stormwater control for different rainfall reappearance periods. Hydrological regulation performances of the LID practices were varied with rainfall reappearance periods. For LID practices with the same surface area, the detention pond performed the best in reducing peak flow rate, which was followed by infiltration trench, bioretention cell and porous pavement. Detention pond was capable to reduce the peak flow rate of 100-year storm to the value of 10year storm, indicating significant performances. Differences in peak flow reduction were due to structure differences in the LID practices. For the infiltration regulation performances, infiltration trench had the highest recharge ratio for all the rainfall reappearance periods, followed by bioretention cell and porous pavement. Porous pavement, though made of 100% pervious material, infiltrated small runoff which was limited by the native soil infiltration rate when the rainfall volume exceeded the storage capacity. Deep analysis was conducted to determine the reasons that the LID practices performed differently when they had the same surface area. Results showed that the “effective storage”, which was the water volume that a facility can contain, was the crucial factor. When rainfall intensity was larger than native soil infiltration rate, the excessive water was stored in the facility, and then it was released or infiltrated to the groundwater, depending on the facility structure. Consequently, the water exceeded the “effective storage” was flowed over the LID practices and made contribution to the surface runoff directly. Calculation results showed that the “effective storage” for the detention pond was 1861.20m3, which was the largest among the four LID practices, and it explained the reason that detention pond worked the best in peak flow reduction. The “effective storage” for the infiltration trench, porous pavement and bioretention cell were 744.48m3, 80.37m3 and 565.14m3, respectively.

Abstract:Clogging is one of the main factors for long-term stable operation of subsurface drainage systems. It also should be paid attention during the application and popularization of subsurface drainage system. The main issues of applying improved subsurface drainage are choosing specifications for filter, preventing clogging, lowering the attenuation of discharge and reducing soil losses. Based on soil column experiment, two filter paving patterns, two kinds of geotextile and three laying locations of the geotextile were considered, the attenuation of discharge process, mass of geotextile clogging and mass of soil losses were simulated under single defense measure of filter or geotextile, and defense measures of filter and geotextile were combined respectively, the reasonable distribution of filter and geotextile for improved subsurface drainage was proposed. The results indicated that Terzaghi critera was reasonable and feasible for choosing specifications of gravel filter and it had good effect on preventing the attenuation of discharge for layered filter and mixed filter. By setting geotextile around the pipe, both layered and mixed filters worked well on slowing down the attenuation of discharge and clogging and soil losses. Furthermore, from the comprehensive view of attenuation of discharge and clogging and soil losses, considering the long-term safe and stable operation of the improved subsurface drainage, priority should be given to the combined measure of layered filter and geotextile around the pipe.

Abstract:Application of biochar in soil is being increasingly discussed as a mean to sequestrate carbon and improve chemical and physical properties for plant growth. Compared with the studies assessing the impact on water retention, little research has been published elucidating the mechanisms which were responsible for the change of water stable isotope extraction time. The impacts of biochar on water retention of three types soil (sandy, loam and clay) with different biochar application rates were investigated by extraction timing curve and mean proportional contribution. The mixtures were extracted by cryogenic vacuum distillation and analyzed with isotope ratio infrared spectroscopy. The results showed that the minimum extraction time (Tmin) was 30min for sandy soil, 45min for loam soil and 60min for clay soil. The biochar application rates changed the Tmin, as well as the water hydrogen isotope value and mean proportional contribution. The isotopic composition of extracted sandy soil water was more depleted in 2H with the increase of biochar application rates at Tmin, while the extent of deviation to the standard values displayed peak for loam and clay soil water hydrogen isotope. The results indicated that biochar application rate was directly correlated to the water retention of sandy soil, and it was increased with the increase in water retention of loam and clay soils, but not all biochar application rates had the same impact. The loam soil was more sensitive than the clay soil to the biochar application.

Abstract:The synthesis principle of cellulose water retention agent is polymerization initiated by free radical and the grafting mechanism usually includes chain initiation, chain growth, chain termination, and oxidation. In the presence of initiator, the free radical is generated on the cellulose macromolecule skeleton firstly, and then with the help of chain transfer, the graft copolymer is formed by reacting with monomer. Applying N,N’-methylene bisacrylamide as crosslinker, potassium peroxydisulfate as free radical evocating agent, acrylic acid as grafting monomer, cellulose in corn straw biogas residue was purified by nitric acid-ethanol method to synthesize water retention agent. Through single factor experiment and orthogonal experiment, the synthesis process was optimized, and the absorbency, infrared spectra and surface morphology of obtained water retention agent in the experiment were characterized. The experimental result showed that the optimal process of corn straw residue water retention agent was as follows: the mass ratio of acrylic acid to actived straw residue at 7, neutralization degree at 70.0%, the dosage of initiator (mass ratio to the monomer) and crosslinker (mass ratio to the monomer) at 2.0%, 0.1%, respectively. Furthermore, 9 min microwave moderate heating then 1 min higher heating were needed in the continuous experiment. Under this experimental conditions, the straw residue water retention agent had stronger water absorbency, and the maximum water absorption rate was 382.22g/g as well as with a certain thermal stability. Infrared absorption spectrum showed that there were C—O stretching vibration peaks of acrylic at 1200cm-1 and O—H bending vibration zone of acrylic acid near 1350cm-1. Furthermore, the neutralized —COO- reduced the C=O in acrylic acid, and the absorption peak of C=O appeared at 1557.98cm-1. All of above indicate that grafting polymerization of corn straw residue cellulose water retention agent is successful.

Abstract:In order to combine the traditional rotary mechanical disturbance characteristic with the inert bed material heat storage properties, a new type of rotary gasifier was designed. On the basis of the new type of rotary gasifier, a staged gasification and combustion experimental platform was designed and the thermal state test of the system was completed. The effects of rotational speed, equivalence ratio, temperature and other parameters on the gasification reaction system were investigated. The experimental results showed that when rotary furnace speed was controlled at 1~4r/min, the rotary furnace mixed disturbance characteristics were enhanced with the increase of rotary speed, and temperature distribution was more uniform in the furnace, different parameters were improved in the experimental range, good gas production was got at rotary furnace speed of 3r/min. When temperature was controlled in the range of 550~700℃, the gasification parameters were increased with the increase of temperature, and gas calorific value and gasification efficiency were affected greatly by temperature. Under the experimental conditions with temperature of 600~650℃, the calorific value of combustible gas, gasification efficiency and other indicators were greatly improved. The equivalent ratio (ER) was changed in the range of0.2~0.4, and it had great impact on gas production of the indicators, with the increase of equivalence ratio, the gas production rate and bed temperature were increased to a certain degree, the change trend of other gasification parameters were firstly increased and then decreased, good gasification results were obtained with ER of 0.3.The typical result showed that gas composition of rotary gasifier was close to that of the fluidized bed, considering the sensible enthalpy, the gasification efficiency was about 79.3% and the carbon conversion rate was about 81.3%. The gasifier energy balance was calculated, and the output efficiency of the system was 86.8%, with heat dissipation as main energy loss way. It was found from the separation of the bottom ash with bed material that about 86% of the total ash content was remained in the bed material area, and more than 90% of it was distributed in the bottom of the bed material area. Experimental results were optimized by controlling the variables for operation and design of new type of gasifier improvement to provide reference.

Abstract:A method to identify different varieties of red bean based on hyperspectral imaging technology was proposed. The hyperspectral imaging system with spectrum range of 390~1050nm was used to capture the hyperspectral images of 162 red bean samples, which were collected from three different areas (Anhui, Shandong and Jiangsu Provinces). ENVI software was adopted to determine the region of interest (ROI) in the hyperspectral image and extract the hyperspectral data by averaging the reflectance from all the pixels in the ROI images, and the original spectra were preprocessed by Savitzky—Golay (SG) smoothing. As there was a large number of noise and redundant information in the raw hyperspectral images and hyperspectral data, some data processing methods should be used to remove the noise, accelerate the processing efficiency and improve the performance of the models. The method of feature extraction was SPA, the number of characteristic wavelengths was determined as 9 by using the leave-one-out cross-validation. The methods of feature selection were PCA and ICA. According to the standard of the cumulative contribution rate of variance was more than 85%, seven characteristic wavelengths were selected. Through test and verification, 17 was the best number of characteristic wavelengths of ICA. Finally, the selected optimal characteristic wavelengths and principal components were used as the inputs of the model. However, the results did not meet the expected accuracy, the threshold of PNN neural network and hidden layer nodes were optimized by GA. The recognition rate of the model was higher than 85%, and the recognition rate of the highest SPA—GA—PNN model reached 97.5%. The results demonstrated that it was feasible to use hyperspectral imaging technology for the identification of red bean variety. PNN neural network model can identify red bean variety fast, effectively and nondestructively and provide theoretical basis and technical means for the realization of red bean variety identification based on hyperspectral image technology.

Abstract:Based on the difference of forchlorfenuron residue and organic component, non-destructive identification method of treated and control kiwifruits was studied using hyperspectral imaging system. Firstly, the representative samples were got by field experiment, and the hyperspectral image was got. The instrument parameters of hyperspectral image were as follows: exposure time 10ms, scanning speed 20mm/s and object distance 20mm/s. Secondly, the spectral regions of 1040~1120nm and 1335~1500nm were selected, totally 116 wave bands were produced, and the average hyperspectral value of each sample was calculated. Finally, all data of hyperspectral image were calculated by Matlab, and the non-destructive identification method of two types of kiwifruit was established. The residue of forchlorfenuron was determined by HPLC, organic component in kiwifruit was analyzed according to the national standard. The results showed that correct identification rate of PCA—LDA and support vector machine (SVM) mathematical models was 94.4%; forchlorfenuron residue level of treated kiwifruit and control kiwifruit were 0.03mg/kg and 0mg/kg, respectively; the content of organic components were different, such as total sugar, total phenols, vitamin C, titratable acid，17 kinds of amino acids and eight trace elements. Therefore, the high spectrum technology was an efficient method for non-destructive identification of PGR (plant growth regulation) kiwifruit.

Abstract:A nonlinear chemical fingerprint method for determining the content of dextrin in milk powder was developed. Firstly, the content of dextrin in milk powder was rapidly determined by using the dynamic nonlinear chemical fingerprint method. Using sulfuric acid, manganese sulfate, acetone and sodium bromate as reaction system, the dextrin with different contents was added into milk powder as milk powder standard samples. The nonlinear chemical fingerprints of milk powder standard samples were obtained, and there was a linear relationship between inductive time or undulatory end time and the content of dextrin in milk powder standard samples, respectively. Then, the content of dextrin in milk powder was calculated by the least square method. The results showed that within 0～30% of mass fraction of dextrin, there was a good linear relationship between the content of dextrin in milk powder and inductive time or undulatory end time, the determination coefficient was 0.9972～0.9991, the recovery was 94.00%～104.89%, the relative standard deviation was 0.17%～1.17%, the determination range of dextrin content in milk powder was 0～30%, and the detection limit of 1.3×10-3～4.7×10-3mg/g was obtained. The developed method was a practical and feasible method for determining the content of dextrin in milk powder, and it had advantages of good accuracy, low cost, simple operation and no sample pretreatment. In addition, the method can be used to determine the dextrin content in different batches of the same brand of milk powder or different brands of milk powder, it can also be used as an approach for the determination of other components in other complex samples.

Abstract:In order to provide theoretical guidance for producing liquid smoking sturgeon fillets, the liquid smoking processing technology and effects of liquid smoking process on the quality of sturgeon fillets were studied. The type and concentration of liquid smoke, smoking time and drying time of liquid smoking process were optimized. The results indicated that desirable sensorial characteristics with intense and pleasant taste were acquired when diped in 5% hawthorn kernel smoked flavor II for 3h and dried at 85℃ for 2h. Microbiology, moisture content, crude protein, crude fat, salt content, pH value, total volatile basic nitrogen (TVB-N), benzopyrene and volatile components were determined to evaluate the effect of liquid smoking process on sturgeon fillets. The results showed that total viable count was reduced from 2×103 CFU/g to 5×102 CFU/g and the relative content of phenolic compounds was increased from 0.89% to 8.62% during the process. Meanwhile, the moisture content was decreased and crude protein content and crude fat content were increased. In addition, theliquid smoked sturgeon fillets contained no pathogenic bacteria and 0.22μg/kg benzopyrene. The results suggested that the liquid smoking processing technology of sturgeon fillets should be proposed in market promotion for the products, and it meets national standards in microbiology and benzopyrene with desirable taste.

Abstract:Minimally modified low density lipoprotein (mm-LDL) plays an important role in the progression of atherosclerosis. In order to further study the inhibition effect of effective fraction of clove (EFC) on mm-LDL, antioxidation was induced by ferrous sulfate in vitro and inhibition effect was examined by the following methods: determination of conjugated dienes (CD), thiobarbituric acid reactive substances (TBARS), UV-visible spectra, LDL-tryptophan fluorescence, free amino groups on lysine. The results indicated that EFC (2.5μg/mL) effectively delayed the CD to be generated, and this delay effect of EFC was better than that of positive control-BHT (0.5μg/mL) in the course of oxidation propagation. EFC （50μg/mL）also put off the generation of TBARS during the decomposition of LDL, this delay effection of EFC was better than that of BHT(10μg/mL). Likewise, the UV-visible spectra of LDL during the course of oxidation could be protected from being changed by EFC with certain concentrations (1.25μg/mL, 1.5μg/mL). Meanwhile, EFC (5μg/mL) could significantly inhibit the decay of free amino groups on lysine in terms of protection on protein (apoB—100) oxidation of LDL , and this fraction (1μg/mL) may effectively protect LDL-tryptophan from destruction (P<0.05), furthermore, this distinction of inhibition effect was not significant with BHT(1.25μg/mL). In conclusion, these results proved that EFC had a significantly antioxidant activity on mild oxidation of LDL，which provides reference for further research and development of functional food.

Abstract:The method for the preparation of ginger oil nano-emulsions using ultrasonic emulsification with OSA starch Purity Gum 2000 (PG), Hi Cap 100 (HC) and C001（F）as emulsifier was studied. Then the stability of ginger oil nano-emulsions was also studied. Through single factor and response surface optimization experiment, OSA starch PG and HC were chosen as emulsifiers. The optimum parameters to prepare ginger oil nano-emulsion with PG as emulsifier were ultrasonic power 430W, ginger oil concentration 9% and PG concentration 0.1g/mL. The average particle size of PG ginger oil nano-emulsion was (148±4.23)nm. The optimum parameters to prepare ginger oil nano-emulsion with HC as emulsifier were ultrasonic power 410W, ginger oil concentration 9.2% and HC concentration 0.125g/mL. The average particle size of HC ginger oil nano-emulsion was (162±3.25)nm. The PG and HC ginger oil nano-emulsions both have good pH resistance ability. Acidic solution are better for ginger oil nano-emulsions to keep stable. Both of PG and HC ginger oil nano-emulsions also have good ionic resistance ability and the ability of PG ginger oil nano-emulsion is stronger than HC. The influence of Ca ion on stability of ginger oil nano-emulsions is greater than Na ion. The addition of malt dextrin can improve the freeze-thaw stability of PG and HC ginger oil nano-emulsions. PG ginger oil nano-emulsion shows better freeze-thaw stability than HC ginger oil nano-emulsion. This study contributes to the further application of ginger oil nano-emulsions in food industry.

Abstract:In the identification of haploid maize based on pollen xenia effect, it is of vital importance to determine oil content threshold between haploid and diploid rapidly, accurately and efficiently for automatic classification of haploid by automatic magnetic sorting system in large quantities. A new method based on the least square error was proposed to discriminate haploid from diploid maize seed. Aiming at 10 crosses of maize, through incrementing the number of samples contained in each training set, the size of the training set which can get ideal recognition rate was determined. Principle of least square error used to classify haploid from diploid maize seed was described, and then several experiments were conducted to verify the effectiveness of the proposed method. Seed oil content was measured by nuclear magnetic resonance (NMR) analyzer in the experiments. The least square error method can rapidly determine oil content threshold between haploid and diploid with low amount of samples to realize the practical goal that the haploid correct recognition rate and the diploid correct rejection rate reached more than 90%, and it would provide parameters guidance for the haploid automatic nuclear magnetic resonance (NMR) verification system in the later large-scale classification and improve the efficiency of separation. It was very practical to obtain good classification result with low cost, and it would provide support for the development of haploid engineering.

Abstract:The late frost injury of winter wheat usually occurs during the jointing-heading stage and may result in severe yield loss in large areas, thus it is of significant importance to monitor and assess late frost injury of winter wheat real-timely and accurately. The simultaneous heat and water (SHAW) model is a detailed process model of heat and water movement in plant—snow—residue—soil system, and it has the capability to simulate heat and water transfer within the canopy. The SHAW model was applied to simulate air temperature within winter wheat young ear layer at the sensitive period after jointing stage in Shangqiu City on the basis of field experiment in 2015, and it was also adopted to monitor occurrence and damage level of late frost injury combining with the days after jointing stage. The results indicated that the air temperature within young ear layer (20~60cm) was accurately simulated as a whole, in which about 44.7% and 72.5% of the absolute errors of simulated value were less than 1℃ and 2℃, respectively, and the simulated air temperature at night was better than that in the daytime. Compared with the minimum air temperature measured at the height of 1.5m at the meteorological station, the simulated minimum air temperature within the young ear layer of winter wheat and the low temperature duration can well express the low temperature environment of young ear when late frost injury was occurred. There were large differences among the minimum air temperature measured at the meteorological station, the minimum air temperature measured at 2m height in the winter wheat fields and within the young ear layer because of the influence of field microclimate. The method which transformed air temperature data from the meteorological station into air temperature data at 2m height in the winter wheat fields was better than the method which used air temperature data from the meteorological station as driving data of SHAW model directly, the minimum air temperature simulated by the former method was close to the measured one, and the late frost injury level evaluated by using the former method was in good agreement with the field surveyed one. Therefore, using SHAW model to monitor late frost injury of winter wheat is feasible and applicable, and compared with the traditional monitoring index of air temperature data from the meteorological station it can enhance the accuracy for monitoring the occurrence and damage level of late frost injury.

Abstract:To collect the meteorological data dispersed in various industries, fields and disciplines in a comprehensive and real-time way, and meet the needs of scientific research departments for data, an efficient directional crawler was developed based on Google’s full-Stack technology called MEAN (MongoDB + Express +AngularJS + Node.js) Stack and an fast flex Javascript Document Object Model module called CheerIO, the functions such as fast-gathering weather information, information analysis and processing by data storage, query, automatic mapping, statistical analysis, forecasting of GIS were realized. An application system deployed on Alicloud server which can real-timely update and forecast meteorological data was created, and it can also provide practical functions of massive data storage, convenient search and query. An efficient and practical web application system was built, which not only provided effective solutions for scattered online data collection but show people date intuitively by using HTML5 data visualizing technology. In actual project, it offered a great number of data support and example to the weather-related fields, such as forestry and preventive medicine. GIS data visualization is a constantly evolving concept, whose borders are expanding fast. At the age of the internet, especially in the globalization of information, the long-term value of data has been gained more and more recognition and affirmation from small companies to national political decision-making. It should be recognized what really it is and how it can help us.

Abstract:Taking the stock volume of continuous forest inventory in Miyun District of Beijing as research object, and combining auxiliary factors associated with stock volume, the spatial interpolation analysis of the stock volume was carried out by using the ordinary Kriging and Co-Kriging methods, and the results were compared with those of reference 25 in the same study area based on the partial least squares regression method. The results show that based on the auxiliary information, Co-Kriging method is superior to ordinary Kriging and partial least squares regression method, the correlation coefficient between the estimated value and the measured value based on Co-Kriging method was 0.845, the correlation coefficient between the estimated value and the measured value based on ordinary Kriging method was 0.389, and the correlation coefficient between the estimated value and the measured value based on partial least squares regression method was 0.766, respectively. Co-Kriging can significantly improve the prediction accuracy compared with ordinary Kriging, generating the root mean square error decreased by 71%, respectively, and the correlation coefficient between predicted values and measured values increases by 54%. Finally, the spatial distribution map of forest stock volume in Miyun was generated. The research shows that the application of geo-statistical methodology has a good application prospect, and it can provide a feasible method for the estimation of forest stock.

Abstract:It takes an important role to measure the DBH and position of standing tree by a 2D laser detection in current forestry surveying and mapping. A compensation scheme in short distances contraposing the two variables was put forward on three common geometry algorithms (arc length method, tangent method, dual-cosine method), and a compensation angle was used in the scheme. The functionary relation of compensation angles for arc length method and tangent method with distances was researched specifically, the regression analysis was also carried on, and the fitting equations were obtained (R2>0.85 for each fitting equation). Verification test for trunks using the fitting equations in the range of 0~5.5m was carried out in which five poplar trunks were selected. The accuracies of measured values of radius and the distance were all improved by algorithms compensation. Thereinto, the measure precisions of radius values from arc length compensation algorithm and tangent compensation algorithm were respectively increased by 10.6 percent and 10.7 percent, and the mean absolute errors were 4.8mm and 3.8mm; the mean absolute errors of measured values of distance were controlled within 66.0mm and 15.9mm respectively after algorithms compensation. Experiments proved that the two compensation geometric algorithms could both be used as forestry surveying and mapping algorithms in short distances, and the tangent compensation algorithm is better.

Abstract:The dissolved oxygen (DO) concentration is of great importance to wastewater treatment due to its influence on effluent quality and operational costs. However, the DO concentration is difficult to be controlled owing to the timevarying and nonlinear characteristics. Considering these issues, a neural network predictive controller (NNPC) based on Levenberg—Marquardt (LM) algorithm was proposed. Firstly, a simplified DO model was established after reasonable hypotheses and constrains in terms of activated sludge model No.1 (ASM1) proposed by International Water Association (IWA). Then the NNPC was applied to the simplified DO model through system identification with BP neural network and model prediction. Furthermore, the LM algorithm integrated the advantages of the gradient steepest descent and Newton methods was used to improve the general BP neural network, which overcame the drawbacks of falling into local minimum easily and slow convergence speed. The simulation results indicated that the improved neural network had good performance in system identification with error less than 3%. Compared with conventional PID control and model predictive control (MPC), the NNPC achieved smoother and better tracking performance and brought obvious improvement. Finally, two measured disturbances were added and good adaptability and robustness were obtained by NNPC. In this way, this method not only can achieve the standard of effluent water quality, but also can reduce the energy consumption of aeration significantly.

Abstract:The conductivity of tracheid is closely related to the flow characteristics of water through the pit. The aim was to investigate flow resistance characteristics of border pits with different structures. The Bernoulli mathematical model of the torus-margo border pit was established based on the energy conservation law. According to the obtained mathematical model, the geometrical structures of pit, such as the pit diameter, aperture diameter, torus diameter, pore diameter and porosity of margo, were the main factors that affected the pit flow resistance characteristics. The flow through the pit was simulated with CFD software package Fluent 6.3, the pit margo was worked as porous medium, and the turbulent structure was modeled by low Re k—ε model. In the simulation, the influences of various pit structures on flow distribution in the pit were studied and analyzed. Resistance of pits were varied with morphology as predicted, the pit flow resistance was inversely proportional to pit diameter, aperture diameter, pit depth and margo pore size, and the pit flow resistance was proportional to torus size and margo thickness. The results supported the hypothesis of valve effect of the pit torus, when the distance between torus and center position was increased, pit flow resistance was decreased at the beginning，and then it was increased, the pit flow resistance was increased with decrease of distance between margo and pit aperture. The research results provided theoretical basis for further study on the hydrodynamic characteristics of plant conduits.

Abstract:With the aim to definite the visual sensitivity selection difference of locusts biological response inspired by the visual excitation effect of spectral and polarized light, and determine the visual excitation factor and the visual sensitivity information of locusts phototactic and polartactic selection, based on the investigated experiment of swarm locusts biological selection effect responding to spectral light and polarized light respectively, the visual regulating function of locusts phototactic and polartactic selection disparity, the visual sensitivity factors and the visual exciting intensity of locusts stimulated by spectral light and polarized light were analyzed. Results show that locusts light aggregation degree induced by the superimposition function of spectral and spectral polarized light presented the sensitivity difference of physiological response to the regulation of polarized light vector, but when light stimulus intensity increased, the sensitive polarization vector of locusts visual response orientation changed, and the photosensitive biology aggregation response effect stimulated by the coupling light stimulation effect of 210°, 120° vector of violet polarized light and violet light, 210° vector of orange polarized light and orange light was the better, while that of 270° vector of violet polarized light and violet light was the worst. Locusts visual light selectivity with the visual excitation state tended to polarized light with the weaker stimulation intensity, spectral light stimulation intensity and polarized light vector sensitive degree weakened locusts positioning control behavior, and locusts polartactic vision sensitivity inspired by UV and violet polarization vector was the stronger while blue and orange polarization vector was the weaker, but 90°, 270° vector of polarized light made the stimulation effect of spectral light dominate light selectivity intensity. Moreover, the enhanced degree of locust visual sensitivity selection to violet polarized light, 120° vector of UV polarized light caused by the increment of the stimulating intensity was the stronger and the weaker respectively, and the weakened degree of spectral light selectivity caused by 90° vector of blue polarized light was the stronger. Thus, the aggregation difference of locusts response to spectral light coupling with polarized light and the selection intensity difference between spectral light and polarized light, originated from the regulated output effect of light reaction synergistically or antagonistically generated by the incentive of polarized light vector and the stimulation of spectral light, and spectral light intensity could weaken the intensity of selection to polarization vector information, but locusts bio-photosensitive response and spectral light sensitivity presented significant correlation, and the light gradient of spectral light coupling with polarized light, significantly affected locusts sensitive response intensity, while light stimulation intensity effect was not significant. Research results provide theoretical support for the manufacture of the agricultural pest induction machinery product and locusts visual response mechanism.

Abstract:For the trend and necessary to limit water exchange and control disease, biofloc technology (BFT) has been widely applied in aquaculture. The carbon source supplement is the base and core of BFT, which will significantly affect the water quality, food conversion ratio (FCR) and the immune capacity in rearing animals. To explore the influence of carbon source supply tactics on the treatment of waste water discharged by recirculating aquaculture system (RAS), research was conducted, based on simulated aquaculture wastewater as the research object. In addition, the sucrose, sodium acetate and glycerol were used as carbon source, and three kinds of C/N ratio (5, 10 and 15) were evaluated for each type of carbon source respectively. Results showed that nitrification and assimilation occurred in the experimental groups. At the low C/N ratio (C/N ratio is 5), the nitrification intensity of different carbon source had extremely difference（P<0.05), but in the stable stage of each system, ammonia nitrogen removal rates all achieved over 90%. Moreover, sodium acetate system was quicker to reach the stable stage (4d), and less affected by C/N ratio. While with the C/N ratio increasing, the groups of sucrose and glycerol required less time to achieve stabilization (24d reduce to 12d), and the ammonia nitrogen removal efficiencies were improved gradually(sucrose, increasing from 87% to 99%; glycerol, from 83% to 98%). Secondly, different carbon source and C/N ratio had various effects on alkalinity of biofloc system. At system stable stage, with the increase of C/N ratio, the alkalinity of sodium acetate groups was raised slowly, and maintained high concentrations, which were not suitable for aquaculture reuse, but the groups of sucrose and glycerol were relatively stable, which were all less than 200mg/L (CaCO3). In addition, combined with biofloc sludge volume index (SVI), settlement performance of biofloc had no significant influence on the removal efficiency of ammonia nitrogen（P>0.05). At a low C/N ratio(C/N ratio is 5), the difference of EPS polysaccharide contents of three carbon source was not significant （P>0.05), and with the increase of C/N ratio, EPS polysaccharide of three carbon source had different contents and change tendencies.

Abstract:It is not easy for large engineering machinery equipment to start smoothly and successfully, because the starting torque is much larger than its rated torque. In order to improve the starting torque without increasing the installed power of system, a new driving system, which was composed of electric motor, flywheel and hydro-viscous clutch (HVC), was proposed. Based on the mathematics model of new driving system and oil film bearing capacity, the AMESim simulation model of HVC system was built up. According to the influence analysis of flywheel rotary inertia and oil film thickness control method on the dynamic engagement performance of HVC, curves of torque, rotational speed and jerk degree were obtained. The simulation results showed that compared with wet clutch, HVC can effectively avoid the start-up shock by reasonable control of oil film thickness, and the variable decreasing speed of oil film thickness was a good method to increase the starting torque and reduce the jerk degree. To verify the theoretical analysis and simulation, a test rig of the HVC system was established. The experimental results showed that the viscous torque curve with twice of the load torque and duration of 50s were achieved by controlling the oil film thickness of HVC, which can satisfy the demands of big starting torque and small impact for large engineering machinery equipment.

Abstract:In order to improve the breakup condition of oil beams and increase their initial turbulent kinetic energy at the exit of the nozzle, the high injection pressure of 180MPa was used. The changing relationship between the physical properties of the non-normal fuel and the pressure under the influence of the high pressure injection was derived. The spraying flash photography test bench based on the high pressure constant vessel was set up. The three-dimensional CFD model of nozzle inner flow field was established on software AVL FIRE. The simulation model was modified according to the spraying test results. The three-dimensional flow state and cavitation flow characteristics of nozzle inner gas-liquid two-phase flow field were analyzed. The results show that when the temperature is constant, the density, the speed of sound and the bulk modulus of fuel increase with the ascent of pressure, the change of these physical parameters of non normal fuel is beneficial to the production of cavitation gas and enhance the cavitation effect; increasing the fuel injection back pressure restrains the flow of cavitation gas and fuel, so the cavitation effect is weakened; with the increase of nozzle diameter, the high speed region of fuel becomes more extensive and the cavitation effect becomes more prominent. The increase of the injection angle also helps to enhance the cavitation effect, but the effect is not obvious due to the limitation of the structure form. So the reasonable matching relationship between the nozzle diameter and injection angle is helpful to improve the initial turbulent kinetic energy intensity at the outlet of the nozzle, and obtain a better jet state.

Abstract:The kinematics performance analysis and optimal design of 4—UPS—RPU (4-universal joints-prismatic pairs-spherical joints/revolute joints-prismatic pairs-universal joints) redundant actuation parallel mechanism was studied. The Jacobian matrix of the mechanism was established, and the three dexterity measures, which were conditional number, the smallest singular value and operation, were obtained. On this basis, the global dexterity coefficient, which was used to evaluate the dexterity of various configurations, was defined. And the distribution of different dexterity measures when parallel mechanism was kept in different attitudes, such as in single attitude of different Euler angles α and different Euler angles β, at the same Euler angle α and different Euler angles β, in the workspace were analyzed, respectively. Finally, based on the global dexterity coefficient, the structure parameters which include the distribution angle on stationary platfrom and motion platform and the distribution radius on stationary platfrom and motion flatfrom, were optimized by genetic algorithm. Compared with the global dexterity coefficient before and after optimization, it was found that the global dexterity coefficient after optimization was bigger than that before optimization. Thus the kinematic performance of 4—UPS—RPU redundant actuation parallel mechanism after optimization was much better than that before optimization, and the optimized effect was obvious. This research can provide important theoretical base of the structure design for the redundant actuation parallel mechanism.

Abstract:Kinematic decoupling of parallel mechanisms is a significant characteristic. Parallel mechanism with decoupling features is easy in kinematic analysis, real-time control and industrial applications. The topic was dealt by many scientists and some kinematic decoupled parallel mechanisms were proposed. The design theory for parallel mechanisms was used based on the position and orientation characteristics (POC) and the ordered single-open-chain (SOC), the existed input-output decoupled parallel mechanisms covered 2-DOF to 6-DOF were analyzed for their topology analysis and motion decoupling analysis, from which it can be known that kinematic decoupling can be viewed simultaneously into the topology decoupling and kinematic parameters decoupling. Based on this investigation, four general design rules and principles and the corresponding methods for decoupling parallel mechanisms were proposed respectively, which were based on the synthesis and decomposition of basic kinematic chain (BKC), sub parallel mechanisms, reasonable chosen base point and special prismatic joints configuration. The corresponding examples were designed to illustrate each method. Fifteen novel decoupled parallel mechanisms were totally proposed. Among them, the kinematic decoupling can be divided into position-posture separate decoupling, position-posture internal decoupling, which can be regarded as the direction and roadmap of the kinematic decoupling. The research enriched the numbers of decoupled parallel mechanisms and provided an effective methodology for decoupled parallel mechanisms design.

Abstract:Parallel mechanisms with linear moving platform (LMP) have good practical application value, but it was rarely studied. Firstly, using structure coupling-reducing theory based on the position and orientation characteristics (POC) and the ordered single-open-chain (SOC) units, five 5—SPS parallel mechanisms with LMP were designed, and four of them were novel ones. Secondly, the “existence criterion of mechanism” was proposed. Each 5—SPS parallel mechanisms with LMP had its own advantages and applications. Accordingly, the existence of five 5—SPS and the non-existence of 6—SPS, 4—SPS, 3—SPS, 2—SPS parallel configurations with LMP were proved. As a consequence, the criterion can be used to determine the existence of mechanisms. Then, the three important topological characteristics, including coupling degree, the output POC and the input-output motion decoupling, as well as the position workspace characteristics, of the five 5—SPS parallel mechanisms with LMP were separately calculated and compared. It was shown that the coupling degree of mechanisms and difficulty of solving forward displacement analysis can be reduced, but the workspace would be reduced simultaneously when the collinearing or coinciding of the spherical joints on the moving platform was occurred. And the mechanisms with triple-spherical-joint structure had input-output motion decoupling. These results can provide theoretical basis for engineering design, optimal selection and potential use of the five 5—SPS parallel mechanisms with LMP.

Abstract:In order to further study and solve the problems of the driving force coordination of parallel machine tool with redundant actuation, build a control system based on dynamics and realize the force-position hybrid control, the original 5UPS/PRPU parallel machine tool was taken as research object, and a drive for middle PRPU constraint branch was increased to make it a redundant actuation branch. Finally, the 5UPS/PRPU parallel machine tool with redundant actuation was built. The Kane equation of higher computation efficiency was taken to establish the dynamics model. The mechanical structure was introduced, the kinematics property of the parallel machine tool was analyzed from the three aspects of speed, partial speed and acceleration. The dynamics model of the system was established, and the redundant driving force was solved. By using ADAMS software, the no-load translation example driving force was simulated and compared with the no-load translation example driving force obtained by Kane dynamic model of the parallel machine tool. The results showed that the simulated and calculated driving forces were very similar, the maximum deviation absolute value was only 0.068N. It proved the validity of Kane dynamical model and obtained the mechanism of driving force coordination and distribution. Redundant actuation can effectively reduce the peak value of driving force of the parallel machine tool and make the driving forces change slowly during the motion process. Besides, it has the advantages of high rigidity, high bearing capacity, good stability and so on. The correct establishment of the dynamic model was the prerequisite of realizing real-time control strategy. It was of great significance to the research on redundant actuation of the parallel machine tool.

Abstract:A novel coupled mechanism was synthesized based on the particular geometrical construction and high symmetry of the regular tetrahedron. Firstly, two simple types of substitutive element component were designed and implanted in the location of all vertexes and edges contained in the regular solid respectively. An equivalent geometrical basic model was obtained with combination of the element parts connected by revolution joints according to frame of regular tetrahedron. The relative studies of the basic geometrical model with four congruent sub-structures were converted into a 6-bar closed-loop linkage. Secondly, the mobility of geometrical basic model was determined on the basis of independent motion shunting measurement method. The approach of adding chains was adopted to allocate the constraint sets and rearrange the components spatially when the closed-loop linkage was rigid on the basis of the screw theory. The element unit loop structure was abstracted by the means of modifying the constraint set of the 6-bar closed-loop linkage with the corresponding added chains symmetrically. Finally, the novel quasi-regular tetrahedron coupled mechanism was established with regroup of the identical elementary units according to the same way of combining the equivalent geometrical model. To define the motion of the new mechanism, a three-dimensional model was developed based on the SolidWorks for simulation analysis and the displacement variation of the output part and the other two symmetrical node components was provided by Matlab. The results showed that the new-designed coupled mechanism had two translational degrees of freedom which belonged to a plane perpendicular to the base and the three node components located in the vertexes had the same radial motion trend directed to the geometrical centre of the new structure. The mobility and the centripetal characteristic of the mechanism were verified correctively. This new structure can be applied to the executing structure of the deployable mobile robot.

Abstract:A new kind of flexure hinge, which was used on LEMs, named Triple—LET was proposed via connecting three outside LET flexure hinges, and its 3D structure was designed and analyzed. The equivalent bending stiffness of the Triple—LET flexure hinge was deduced and a modified coefficient was presented to optimize the results. Based on the modified formula of equivalent bending stiffness, the theoretical calculation of the design example was deduced，and the finite element simulation model of the design example was established and analyzed. Through comparing theoretical calculation results with finite element simulation results of the design example, the feasibility of the Triple—LET flexure hinge was verified. In order to verify the availability of the new flexure hinge in practical application, the Triple—LET flexure hinge was applied to a lamina emergent slider mechanism. The pseudo-rigid-body model of the lamina emergent slider mechanism was established based on the modified equivalent bending stiffness, and the physical model of the lamina emergent slider mechanism was made of beryllium bronze material based on the series Triple—LET flexure hinge. The theoretical calculation results and experimental results were basically consistent, therefore, the correctness of the theoretical model and the feasibility of the design example were verified, and it also indicated that the lamina emergent slider mechanism can implement large deformation and maintain a good stability in working status.

Abstract:Nowadays, plunger pumps are being developed in the direction of high pressure and large flow. Therefore, the friction pairs in the pump adhesive wear and burn phenomenon has become increasingly serious. To solve these problems, the dynamic performance of the pump and lubrication characteristics were improved, the structure was optimized and high wear-resistant materials were used by most researchers. However, the wear problems were not solved fundamentally. In order to solve the wear problems of swash plate piston pump fundamentally, a new type of axial piston pump was proposed. The swash plate was replaced by double curve-face gear, the friction pairs were replaced by gears. By using the transmission principle of curve-face gear pair, the movement characteristics models of the piston pump, the single piston and six pistons of double curve-face gear were established, and the movement law of the piston was obtained. In order to verify the accuracy of the above theory, the motion simulation analysis and theoretical simulation results were compared and analyzed. By using the virtual prototype of ADAMS, the simulation model of movement characteristics of piston pump was established, and the piston movement feasibility of the new piston pump was validated. The piston movement characteristics of piston pump were tested by using the test-bed and the result was obtained. The comparison between test and theoretical results indicated that the test result was basically agree with the theoretical result, and the relative error between test and theoretical results was within 5%，the correctness of theoretical movement characteristics model of piston pump was testified. This experimental results showed that the flow pulsation performance of the piston pump can be better than the current level when the structural parameters were fully optimized.

Abstract:As one of the most important performance indexes for electromagnetic actuator with tooth structure, linearity has major impact on the vibration controlling effect. However, traditional fixed tooth electromagnetic actuator has poor linearity. To solve this problem, the analytical model of variable tooth electromagnetic actuator was worked out by analyzing magnetic circuit. Influence rules of several parameters, such as air gap, the difference between tooth width of stator and active cell, coil turns and the radius of the active cell, on actuator performance were analyzed based on the analytical model, indicating that the difference between tooth width of stator and active cell had great influence on the linearity of variable tooth electomagnetic actuator. And the necessity of applying variable tooth to gain good linearity was revealed theoretically and the realization of good linearity needed to be at the expense of decreasing electromagnetic force. To improve the linearity of variable tooth electromagnetic actuator as much as possible and minimize the decrease of electromagnetic force at the same time, genetic algorithm was applied to the optimal design. The results showed different setting for genetic algorithm parameters had negligible effect on optimization results and that compared with the fixed tooth electromagnetic actuator, variable tooth electromagnetic actuator can improve linearity by 93.08% under the condition of electromagnetic force was only dropped by 8.22%. Finally, the simulating calculation for optimized scheme was carried out with the finite model which was verified by the experimental results of the processed prototype, and calculation result proved that the optimized actuator had good linearity in the displacement range of 0~3mm, meanwhile, it validated the analytical model.

Abstract:Micro scale 3D printing based on electrohydrodynamic (electrohydrodynamic jet printing, E-jet printing) is an emerging and promising micro/nano scale 3D printing processes, which was demonstrated with outstanding strengthens and high potentials in terms of high resolution, low cost and easy operation. Micro scale 3D printing was utilized in various areas, including tissue engineering, electronics, micro fuel cell, composite materials, etc. Different from the traditional jet printing technology, the EHD jet is driven by electric field to draw a very fine jet from the top of the liquid cone. The forming mechanism of micro scale 3D printing based on EHD was complex, and there were several influencing factors and process parameters. The stress state of Taylor cone was analyzed theoretically, and then the finite element simulation and experimental methods were used to verify the theory. Through the investigation, the jetting mechanism of the micro scale 3D printing method was explored, and the influences of voltage and pressure of cone-jet mode on E-jet printing were revealed, and some useful conclusions were achieved. The result showed that the Taylor cone was shortened with the increase of voltage, and it was lengthened with the increase of inlet. Meanwhile, it was shown that the printing can be carried out in a certain range of voltage and pressure, rather than specific values of voltage or pressure, so the cone jet and printing quality can be improved by adjusting the voltage and air pressure. A printing example of light curing resin material was given, and the printing quality was good. The research results provided theoretical basis and guidance for improving the forming accuracy and control performance of micro scale 3D printing based on EHD.

Abstract:The parameters calibration of the articulated arm coordinate measuring machine is the key to ensure the working accuracy of the measuring machine. The disadvantages in the process of the parameters calibration for articulated arm coordinate measuring machine are as follows: complex calibration method and algorithms, poor operability and costly calibration tools production. To solve this problem, the symmetry point method was used to calibrate the parameters of the articulated arm coordinate measuring machine. This calibration method can separate the parameters and make the calibration process more simply. Firstly，the mathematical model of the articulated arm coordinate measuring machine was established based on the quasi spherical coordinate system. The quasi spherical coordinate system was proposed based on the D—H method. This mathematical model can be used to make the parameters orthogonal between the joints. Then, the kinematics equation was deduced. The fixing device was designed according to the requirement of experiment. The experiment was performed on the ROMER Infinite 2.0 articulated arm coordinate measuring machine. The standard ball with a diameter of 15.8754mm was used to test the accuracy of the calibration parameters. The experimental results were as follows: a5=78.312mm, a7=25.962mm, b3=747.489mm, b5=531.880mm, b7=178.383mm, d7=176.484mm. Through experiments, the relative error of the standard ball diameter was 0.3836%. The results of the experiments showed that this symmetry point method was feasibility and the experimental results were accurate. It establishes the foundation for improving the measuring accuracy of the articulated arm coordinate measuring machine.