Abstract:Biochar has a bright prospect due to its good surface properties, pore structure and broad raw materials of its production. It has already been a hotspot in the fields of environment, agriculture and energy. It can be produced from a variety of biomass feedstock, such as agricultural residues, manures, wood, bone and so on, under oxygen-limited conditions. It has great potentials for heavy metal remediation and waste water treatment due to its unique properties, low price, easy processing and wide range of preparation material. The existing literature was incorporated to understand the overall sorption research of heavy metals on biochar adsorbents. However, there was still lack of information on the roles of different sorption mechanisms for biochar. The effects of feedstock materials and pyrolysis temperature on biochar characteristics and metal adsorption capacity were discussed. The interaction mechanisms between biochar and heavy metals, such as ion exchange, complexation, physical sorption, precipitation and electrostatic interactions were analyzed in detail. The influence of adsorption conditions and heavy metal species on heavy metals adsorbed by biochar was also included. At the end, the future research directions on sorption of heavy metals by biochar were proposed. The review would help to build important theory and methodology foundation for directly controlling production and scientific utilization of biochar.

Abstract:According to the requirements of flexible and nondestructive grape-picking, a kind of grape-picking device with a grasping and rotary-cut type of underactuated double fingered hand was developed based on the underactuated principle and cooperative working mode of grasping and rotary-cut. To realize the separation of the fruit from the stalk, an electric motor drove a double fingered hand with four knuckles by a linkage mechanism, and the hand approached from the middle of the grape and enveloped it. Its rotary-cut device installed on the hand drove the cutting disc to cut off the stalk by the jigging and telescopic motion. Based on this design idea, the dimensions and rotation angle range of two knuckles of underactuated finger mechanism were firstly determined by analyzing equatorial diameter of grape. Then, the static model of the underactuated finger mechanism was established, and the driven linkage size was determined according to the requirements of optimal force transfer and well-distributed contact force. Combining with the contact force analysis and squeezing-bursting test of the grapes, maximum contact force of grasping 2kg grape without damage was obtained, which was equal to 20N. Thrust force of the electric motor was obtained by solving the static model of the underactuated finger mechanism, and type choice of the electric motor was directed according to the thrust force. The control system of grape-picking device was designed, and the effective control of maximum contact force was realized according to real-time feedback of contact force from four pressure sensors fixed on knuckles. The motion of the rotary-cut device was realized by adopting the control mode of acceleration and deceleration, cutting disc can effectively cut off the stalk with the speed of 1200r/min. By picking 50 bunches of grapes with the equatorial diameter ranged from 95mm to 200mm, the results of grape-picking tests showed that the picking success rate of the device was 100%, extrusion wound rate of grapes was 5.2%, and average cost time of the device was 29.4s without consideration of time consuming of vision localization of grape and its stalk to complete a grasping and rotary-cut motion.

Abstract:In order to analyze the impact of robot grasping control modes on mechanical damage of tomato, the Burgers model was used to express the deformation characteristics of tomato, and the viscoelastic parameters of tomato were obtained by the creep experiment. Three kinds of variations of speed, i.e., motion with uniform deceleration, deceleration after uniform motion and motion with variable deceleration were selected to indicate different grasping control modes. The linear function, Butterworth amplitude square function and exponential function were used to represent different grasping control modes during the robot grasping process. On this basis, the model of plastic deformation of tomato was solved, and the rules of tomato plastic deformations in different grasping control modes were analyzed when the grasping time was constant. Then, the optimal grasping strategy was selected based on the minimum plastic deformation. Experimental results indicated that the third grasping control mode was selected as the best grasping strategy, when the grasping speed was 1mm/s, the grasping time was 1s, the plastic deformation of tomato was the smallest, the early maturity and middle maturity of plastic deformations were 0.0026mm and 0.0098mm, respectively. Using the third grasping control mode to carry out the grasping control experiment, the simulation results were highly identical with measured results, the determination coefficient R2 was 0.99, which proved the rationality and feasibility of the third mode as the optimal grasping control mode. This research can offer a reference for robots grasping process optimization.

Abstract:Fruit and vegetable production occupy an important position in agriculture with wide market and huge economic benefit. Currently, due to the diversity of picking object, most of fruit harvesting in our country depends on manual work. It’s not only time-consuming, but also technic-demanding. The labor cost of harvesting tends to occupy one-third to one-half of the whole labor cost in fruit production process. Thus, fruit harvesting robot needs to be developed to increase the efficiency and lower the costs. Since the working task of harvesting robot grows in natural environment with various shapes and complex structure, visual system needs to be built to recognize the target. This article focusing on litchi picking process, a visual system for litchi images was built and used to recognize litchi. Firstly, a visual system for litchi picture acquisition was built and a method of nighttime litchi recognition and picking point calculation was proposed. For comparison, pictures of same cluster of litchis were captured at daytime with different natural illumination and nighttime with artificial illumination. By analyzing color features of same litchi picture in different color models, the YIQ color model was proved to be the model with best practicability for nighttime litchi recognition and picking point calculation. The background of nighttime picture was firstly removed using Otsu algorithm, then fruit was segmented from stem using Fuzzy C-means clustering algorithm. Circle detection was performed to recognize fruits respectively using Hough circle fitting method. The experiments showed that nighttime litchi recognition accuracy was 95.3% with the average recognition time of 0.46s, and the method for litchi recognition at night time had better accuracy and higher real-time. This research provided technical support for visual localization technology of litchi picking robots. Based on machine vision, the recognition of litchi fruit was realized. It could provide technical support for litchi picking robot, bring practical significance with high harvest efficiency and low labor cost.

Abstract:The scale variation, deformation and occlusion are the important reasons for model drift. In order to overcome the effect of model drift on robust tracking, a multiple model tracking algorithm based on object proposals was proposed. Firstly, as object proposals can reflect the general object material properties, the proposed tracker replaced traditional sliding sampling with object proposals to adapt the displacement and scale variation in the tracking process. And then, in order to enhance the object representation ability, the deep convolutional feature was used to characterize the target. During this process, although the previous size of object proposals may be different, the deep convolutional feature of each object proposal can be extracted quickly by a ROI pooling layer, and each object proposals feature had the same length, which can help to model training and further improve the robustness of the tracker. Lastly, the multi-models selection mechanism was used to undo past bad model updates by selecting the best tracking model, and adjusting the searching area can achieve object re-detection. These measures can inhibit the effect of model drift on robust tracking. In order to verify the superiority of the algorithm, the OTB 2013 benchmark and UAV 20L benchmark, and some classic contrast algorithms recently were used to evaluate the proposed tracker. The results showed that the proposed tracker achieved the best performance on precision and success rate, and the effect of model drift on robust tracking can be effectively suppressed.

Abstract:According to the present situation of the sowing effect of original inside-filling air-blowing seed metering device for flat seeds is better than circles, the phenomenon of drag force greatly affects the cleaning and pressing effect was found through the force analysis of seed in cleaning and pressing process for optimization the sowing effect of circle and mixed seeds. For analyzing the changing of drag force of different seed metering discs in the process of working under the same operational parameter, the bonded particle model was used to model maize based on theory of discrete element method, the coupling analysis method of EDEM-CFD was applied to couple simulation circle seeds with three different hole structures of seed metering discs. The value of drag force of seed in the hole during rotation of seed metering disc was taken as indicator, the changing situation of drag force of seed was analyzed under the operational parameter of inlet air velocity was 30m/s and forward speed was 8km/h with different seed metering discs. Simulation results showed that the drag force of big circle seed was larger than that of small circle due to different particle windward areas in the same type seed metering disc under the same working conditions. In other words, large granular seeds were more likely to be cleaned out of holes. Based on cleaning and pressing performance analysis of different seed discs, the drag force and pressing force in the hole of seed disc with block slot were both larger. And due to the volume of seed filling in the holes was increased compared with other discs, the effect of seed disc with block slot sowing circle and mixed seeds were both better through simulation. The single factor test of working pressure was carried out when forward speed of the different seed discs was 8km/h, experimental results showed that the qualified rate of seed disc with block slot was increased gradually with the increase of working pressure, which was better than the other two. The full factorial experiments were conducted on the seed disc with block slot forward speed of 4~12km/h and working pressure of 4~8kPa, experimental results showed that the qualified rate was increased gradually with the increase of forward speed and working pressure, the qualified rate was close to 96% and leakage rate was less than 1% when working pressure was above 6kPa.

Abstract:In the wheat-maize rotation area of North China Plain, it is widely recognized that there are some problems in the wheat broadcast sowing under the condition of the maize straw mulching, such as straw blockage and wheat seeds planted on the maize straw. In order to solve these problems, taking advantage of the soil-thrown model of down-cut rotation tillage to form soil and straw sequential cover, a straw post-covering wheat planter was designed, which could implement the following function at one time: rotary tillage, uniform-broadcast sowing, anti-blocking, covering soil and straw and compacting. The planter included the following nine parts: suspension frame, gearbox, rotary tillage device, soil-oriented plate, seed-dividing device, soil-straw separation device, multifunctional ground wheel, frame, seeding device, and so on. The layout of rotary blades was symmetrical helix arrangement, and the maximum height of the thrown granule was calculated as 0.52m, the maximum displace in the horizontal direction was 0.79m, and the position parameters of the soil-oriented plate were determined. By means of the performance test, it was preferable that the distance between the seeding-dividing device and the horizontal direction was 35° and the distance between the seed-dividing plates was 50mm. The planter field experiment was conducted in Zhuozhou Experimental Station of Hebei Province, China. And the results indicated that the down-cut rotary tiller could effectively throw the soil and straw and avoid maize straw blockage. The depth of tillage was around 148~152mm, the stability coefficient of tillage depth was 95.5%, slip rate of multi-function walking wheel was about 5.3%, the passing ability of the planter was good and the performance can meet national standards;the weights of maize straw was 1.07kg/m2 after sowing, which can reach 80% of straw amount before sowing;the depth of sowing was around 30~35mm, sowing pass rate was 91.1%, the mean number of wheat seeds in the rectangular frame of 10cm×25cm in different positions was around 29~30, which met the agronomic requirements.

Abstract:At present, no-tillage planters in Northeast China mainly depend on the weight to increase pressure to ensure the ditching depth. Aiming at this, a lightweight 2BQM-2 type maize ridge planter was designed. Its weight was half of the general no-tillage planter, so as to reduce the soil compaction. The new lightweight no-tillage planter was connected with a tractor to be a operating unit by hydraulic hitch equipment. The operating unit used the hydraulic structure of the tractor and the mechanical structure of the planter to jointly adjust the stubble breaking depth, seeding depth and depth stability. In order to verify the performance of the operation unit and get the best combination of working conditions, a quadratic orthogonal rotary composite experiment was designed with the planter speed, seeding depth and straw coverage quantity as experiment factors to evaluate tillage resistance of the planter and qualified rate of seed spacing. The optimum working conditions were as follows: the planter speed was 1.21m/s, the sowing depth was 4.96cm, and the straw coverage was 0.73kg/m2, the working resistance of the seeder was 3.62kN, and the seed-distance qualified rate was 93.63%. The validation test results showed that the test indexes met the requirements of the national industry standards. It proved that it was feasible to use the hydraulic system of tractor to exert the pressure on the stubble breaking device of the seeder. Through the optimum design, the weight of no-tillage planter was effectively reduced, the manufacturing cost of the machine and the energy consumption were reduced. By field measurements, the average soil depth of the compacted wheel was 10mm. It had satisfactory efficiency compared with the machines which flattened ridges. It can provide scientific basis and method of evaluation and improvement of maize no-tillage planter in Northeast China.

Abstract:An embedded pneumatic picking-up mechanism was designed to solve the problem of complex structure and control instability existing in the traditional mechanical picking-up mechanism. According to the design requirements of picking-up mechanism, the constitution of mechanism, working principle and kinematics model of embedded pneumatic picking-up mechanism were clarified, and the control system based on singlechip was developed. The influence of mechanism parameter variation on the phase-trajectory of picking-up seedlings and the posture of picking-up arms were studied based on ADAMS software. The simulation results showed that the straightness deviation of picking-up trajectory was related to the length of lAD, lDE and l1, the height of picking-up trajectory was related to the length of lAD and lAC. The optimization combination of structural parameters achieved was as follows: lAD of 220mm, lAC of 170mm, lDE of 160mm and l1 of 313mm, while the height of picking-up trajectory was 130mm. When the height of picking-up trajectory was 80mm, the straightness deviation of picking-up trajectory was less than 2mm, the angle of declination was less than 4° at taking seedling stage，and the angle of declination was less than 1° at throwing seedling stage. The consistency verification experiment was carried out using high speed photography system. According to the seedling picking-up experiment, the success rate of seedling pick-up reached 93.0% and the success rate of dropping seedling attained to 89.5%, which satisfied the requirements of actual testing. The research for the automatic picking-up mechanism provided an important theoretical basis and reference for the design, analysis and further study on automatic picking-up and transplanting mechanism.

Abstract:Considering the facts that the winter rapeseed is vulnerable to waterlogging, the furrow should be ditched while mechanical planting. The soil of middle and lower reaches of Yangtze River is sticky and its moisture content fluctuates greatly, which leads the stability of the furrow difficult to be guaranteed at the time of planting. In order to solve the above problems, the design of ditching furrows system for direct rapeseed seeder was carried out, and a combined ship type opener was proposed to achieve ditching the furrow. According to the principle of soil sliding and plow forming, the main structure and technical parameters of combined ship type opener were analyzed and determined. Based on the 2BFQ-8 direct rapeseed seeder whose work width was 2300mm, the ditching performance experiment on rear plow, ship type plow and combined ship type opener was carried out in rice stubble field, whose moisture content was 21.4%, 31.4% and 46.6%, soil compactness was 1320kPa, 846kPa and 539kPa. The furrow sections of furrows were mapped. The ditching performance experiment results indicated that shape of furrows ditched by ship type opener were more stable than that ditched by rear plow, and the width of seed bed which measured after ditched furrows by ship type opener was stable . The width and depth of furrows which ditched by combined ship type opener was 244.0~271.7mm and 194.0~229.5mm, its width stability coefficient and depth stability coefficient were more than 90%. The width of seed bed after ditching was 2039.0~2051.5mm. The experiment result revealed that the furrows ditched by combined ship type opener satisfied the actual production requirements of ditching furrows. The research conclusion had great theoretical value and practical significance to the design of opener which worked under the condition of soil with high moisture content.

Abstract:The objectives were to study on operating parameters influence of the covering soil performance and covering soil quality with the device, and analyzing the process and regulation of covering soil on plastic-film, setting up the key parameters equation of process of elevating and covering soil on plastic-film, and determining the test factors and its scope. Quadratic rotation orthogonal combination experiment was carried out. Parameters such as soil elevating scraper belt device speed, operation machine speed, level of two-way spiral filling device speed were selected as independent variables, which would influence qualified rate of soil cover. The mathematical model was established, and then the effects of various parameters and their interactions were analyzed as well. The test results showed that effects order of three parameters on qualified rate of soil cover were as follows: level of two-way spiral filling device speed, soil elevating scraper belt device speed and operation machine speed. The optimal working parameters of device were level of two-way spiral filling device speed of 432r/min, soil elevating scraper belt device speed of 1.56m/s and operation machine speed of 0.50m/s. Confirmatory tests showed that the average value of qualified rate of soil cover was 99.6%, which was promoted significantly compared with that before optimization. Discrete element method was applied to simulate the device with elevating and covering soil on plastic-film dynamic operation process under the condition of optimal parameters of elevating, conveying and covering soil. The simulation result was consistent with the field test conditions, which showed that the device optimization operation parameters calculation was accurate and reliable.

Abstract:Plastic film mulching cultivation technique has the characteristics of increasing temperature and conserving soil moisture and improving the crop fertility conditions. It is an effective measure to realize the early maturing, high quality, high yield and high economic benefit. However, with the expansion of plastic mulching planting area, the plastic film had a serious impact on the root growth, emergence and yield of crops. The mechanized film recycling is an effective means to solve the problem of residual film pollution. There are many ways of recycling equipment, but from the actual use of view, there are some problems. Aiming at the problems of low film recycling rate and high impurity rate, the idea of putting spading film and picking film together was proposed, and a combined type (synchronous spading and picking up) residual film collector device was designed. By analyzing the mechanism of spade film formation, the parametric equation and the main structural parameters of spalling surface were established. Through the analysis of movement and force of pick-up roller, the necessary conditions for the tine to “tie” the residual film were determined. Design-Export 8.0.6 was used to test the key parameters of the combined residual film pick-up device. The ternary quadratic regression model was established, which included penetrating angle of film releasing shovels, rotational speed of picking roller, forward speed of machine, and film recycling rate and impurity rate. The nonlinear optimization method was used to optimize the influence factors. The results showed that the film recycling rate was 90.3% and the impurity rate was 4.1% when the angle of film releasing shovels was 30°, the rotational speed of picking roller was 120r/min, and the forward speed was 1.0m/s. The film recycling rate was increased by 5.3 percentage points and the impurity rate was decreased by 4.8 percentage points, compared with the spade and tine step by step. Test indicators reached the national and industry standards, and the test results met the design requirements.

Abstract:Middle-mounted Wheel High-mobility Universal Frame Platform for Wide-breadth Farm Implements

Abstract:Aiming at solving the blocking of screw conveyor on header of rape combine harvester, an automatic clearance adjusting mechanism was designed. The maximum pretension and displacement were determined to be 366N and 50mm, respectively, through statics and kinematics analyses of the screw conveyor. Torque sensor and high-speed camera technique were used respectively to record torque on the shaft of conveyor and displacement，parameters tests of the mechanism were conducted and the results indicated when pretension was 293N and stiffness was 12.65N/mm，maximum torque of conveyor was 8.267N·m，which was decreased by 40.7%，maximum displacement of the slider was 10.2mm， and parameters of adjusting mechanism were optimal. The influence of the adjusting mechanism on performance of conveyor tests showed that adding the adaptive adjusting mechanism could obviously reduce torque and increase maximum feed quantity，when speed was in range of 150~300r/min, the feed quantity was 1.5~3.5kg/s. Torque was decreased by 23% when speed was 150r/min，feed quantity was increased by 0.5kg/s in experimental group，which was increased by 17.8%. When feed quantity was fluctuated from 1.0kg/s to 3.0kg/s and 1.0kg/s and from 3kg/s to 1.0kg/s and 3.0kg/s， maximum torque was decreased compared with steady feeding quantity of 3kg/s. Field experiment showed that the clearance adaptive adjusting mechanism could adjust the clearance between screw conveyor and bottom plate in time according to the change of feed quantity during harvesting operation，therefore，it could improve the adaptability of header to fluctuation of feed quantity and relieve blocking.

Abstract:To support rapid design of an axial flow threshing-separating-cleaning unit of combine harvester, a formal methodology, which is a parametric approach based on the throughput was proposed. By building a mathematical model to establish the relationship between the throughput and the related data, the parameters of parametric design can be obtained. On the basis of analysis of the hierarchical relationship and dependency between the parameters, a computer platform was developed to realize the simplified design by using the Petri net model to solve the complicated parameter transfer structure. The results showed that the system can automatically generate the required structural parameters (e.g., area of crosswise axial-flow threshing unit grate-type concave and area of longitudinal axial-flow threshing unit grate-type concave, area of scales sieve and area of shutters scales sieve, finger-tooth quantity of whole-feeding axial-flow threshing cylinder and finger-tooth quantity of head-feed threshing cylinder) and relevant working parameters (e.g. air volume and power ) for a given throughput and some relevant data. By importing the result parameters into UG environment, the 3D model of the component can be reconstructed with these parameters. According to data comparison with the developed products, the design parameters of the computer model were accurate and reliable, and 3D model met the design requirements. Parametric design platform not only can carry out the standardized series design and improve the design efficiency, but also can help quickly refine the parameters of the existing products.

Abstract:In view of the gripping and conveying device which belongs to the existing vertical corn harvest header with low gripping uniformity, stability and high failure rate, a clearance located gripping and conveying device with simple structure, favorable conveying effect and high reliability was developed. The device solved the stem gesture adjusting, breaking stem and blocking problems in the working process of vertical corn reaper;ensured that the stem would be located, stably conveyed and directionally fed;and improved the reliability of vertical roller corn harvest header. A corn clearance located and conveyed method was proposed and the designation method of the main structure and motion parameter of clearance located gripping and conveying device was analyzed, its main structure and working parameters that influenced the reliability of ordered located conveying were explored and then the relevant design theory was established. A theory reference was provided for design of vertical roller gripping and conveying device. The main parameter influenced the gripping and conveying quality was determined by orthogonal test method which included the clearance of the gripping and conveying track, the velocity of the clearance gripping and conveying chain and the length of the clearance gripping and conveying chain, and the optimal result showed that the best combination was A2B3C3 group that the length of the clearance gripping and conveying chain was 130cm, the clearance of track was 3.1cm, the velocity of the clearance gripping and conveying chain was 4.5m/s. And the corresponding performance indexes were as follows: the success ratio of stem gesture feeding was 92.5%, the ration of break stem was 0.25%, the conveying process was stable and without blocking, which could completely satisfy the requirement of the vertical roller corn reaper. This research can supply the study basis to structure improvement and performance optimizaiton of delivery mechanism for vertical-rollers type of corn harvester.

Abstract:Aiming at solving artificial picking, low efficiency and time-consuming, shear-sucting mountain chrysanthemum picking machine was designed to achieve mechanization. The picking machine mainly consisted of container, lithium battery, negative air compressor, transmission pipeline, picking box, comb-teeth, synchronous wheel, transmission shaft, separating teeth, DC stepper motor, DC motor speed controller, digital controller, a machine frame and four wheels. Comb-teeth gap was larger than the diameter of bud and less than diameter of chrysanthemum receptacle. The relative motion between comb-teeth and separating teeth pulled from the receptacle. Under the pressure of negative air compressor, the flower was transported to the container. Single factor tests of comb-teeth gap selected 7mm, 8mm, 9mm, 10mm and 11mm five levels. The machine worked well at the gap of 8~9mm. The picking rate was 87.50%~93.11%, the broken rate was 0~0.34%, the drop rate was 1.99%~2.39%, the impurity rate was 4.87%~6.48%, the leakage rate was 3.30%~4.96%. The orthogonal tests showed that the best combination was comb-teeth gap, comb radius, wind speed and rotational speed. When the comb-teeth gap was 8mm, the radius was 50mm, the wind speed was 8m/s and the rotational speed was 30r/min, the machine would work better. The picking rate was 94.54%, the broken rate was 0.57%, the drop rate was 2.05%, the impurity rate was 1.48%, and the leakage rate was 1.36%.

Abstract:Aiming at the problems that the length of lifting chain, jitter separation ability and separation effect of the mixture of potatoes were not matched, the new type of lifting chain device of potato digger under the condition of heavy soil was designed. Based on the theoretical analysis of the separation, deliver and disintegration of the mixture and the mixture of potato and soil on the lifting chain, the main factors influenced the separation effect of the dispersion and crushing were obtained, and the range of lifting chain length and structure parameters of jitter that affected the process of transportation was got. The combination design of orthogonal and quadratic regression equation for the flail was adopted. Taking the length of the second elevator chain, forward speed of machine and velocity of lifting chain as the experimental factors, the field experiment was carried out to test the obvious potato rate and the injured potato rate. The test was implemented in agricultural sciences of academy in Heilongjiang Province at the beginning of September, 2016. The experimental data was processed and optimized by software Design-Expert 8.0.6. The importance of main factors affecting obvious rate was the second elevator chain length and the forward speed of machine. The importance of main factors affecting injury rate was the second elevator chain length, the forward speed of machine and the velocity of the lift chain. Test results showed that when the second elevator chain length was 3.1m, the forward speed of machine was 1.2m/s, lifting chain line speed was 1.5m/s, the obvious potato rate was 98.1%, and the injured potato rate was 1.1%. The function of machine was fully suitable for the potato excavator harvesting requirements. The relationship between the structure and position of jitter on digger, the installation position of the jitter, and the effects of separation and dripped of potato that suited the condition of heavy soil was determined. The research provided an important theoretical support and reference for the improvements and optimization of the lifting chain conveyor separation parts on potato digger.

Abstract:In order to solve the problems of ambiguous separating mechanism of swing separation sieve and the obvious contradiction between the obvious performance and the abrasion performance caused by the improper match of operation parameters, high speed camera was used to capture the distribution of mixture of potato and soil of different crank rotational speed, the screen surface inclination and the machine forward speed. The variation of the distribution height of potato-soil mixture was counted and analyzed, and the separation mechanism was revealed based on these counted results. Finally, the experimental value range of the main factors which affected the separation performance of swing separation sieve was obtained. The rate of obvious and abrasion were used as the evaluation index to establish the regression mathematical model between the indexes and the factors by applying Box-Behnken response surface test method, thus optimizing the structure and working parameters which affected the separation performance of the swing separation sieve. The results showed that the primary and secondary order of the effect of factors on obvious rate and abrasion rate were crank rotational speed, screen surface inclination and machine forward speed. The crank rotational speed of 230r/min, screen surface inclination of 19.42° and machine forward speed of 2.04km/h were the best combination factors, the obvious rate and abrasion rate were 99.4% and 0.002%, respectively after optimizing. According to the limitation of operating parameters, the best parameters were adjusted as follows: when the crank rotational speed was 230r/min, screen surface inclination was 21.1° and machine forward speed was 2.03km/h, the obvious rate was 98.94% and the abrasion rate was 0.21%， the obvious rate was increased by 1.68 percentage points, and the abrasion rate was decreased by 9.6 percentage points compared with that before optimization. The results of parameter optimization were better than the national standard.

Abstract:As the important resource of biomas energy convension and feed utilization, corn stalk needs to be smashed to improve the effective utilization rate. In order to study the performance of hammer mill for corn stalk, the process and performance of smashing corn stalk was studied by hammer mill. Based on the analysis of smashing process by high-speed photography, main smashing types of corn stalk were decided as following: impact smashing, hit smashing and rub smashing, and the impact smashing and rub smashing had greater influences, it could be obtained that the linear velocity of the hammer (the rotation speed) and moisture content of corn stalk had greater influences on the smashing performance of the hammer mill. Then, the main factors that affected the smashing performance of hammer mill (the rotation speed, moisture content of corn stalk and screen size) were chosen as the experimental factors, the output per kW·h was decided as the evaluation index, and experiments were conducted. The experimental results showed that the sequence of various factors’ influence on the output per kW·h was screen size, moisture content of corn stalk and the rotation speed. Parameters were optimized based on regression models. With the maximum output per kW·h as the optimization object, the ranges of the factors were chosen as follows: the moisture content of 10%~50%, the rotation speed of 2000~3500r/min and the screen size was 6mm. Parameter optimization results showed that when the moisture content of corn stalk was 10%~32%, the rotation speed was 2000r/min, when the moisture content of corn stalk was 33%~50%, the rotation speed was 2020~2452r/min, and the rotation speed was increased with the increase of moisture content of corn stalk. The research can provide theoretical and technical basis for design of hammer mill for corn stalk.

Abstract:Geometrical characteristic of the target is the basis to calculate pesticide dosage. In domestic and international research, volume was calculated usually as the control input of variable-rate spraying system. Compared with the volume parameter, leaf area density can avoid the errors caused by irregular canopy shape and lots of gaps in the canopy. Therefore, a method to extract the leaf area density based on the three-dimensional laser point cloud data was proposed. This method corresponded to the law that the branches and leaves were more, the leaf area was larger and the point clouds were more. A target detection system was set up, including a laptop, a light detection and ranging sensor, an incremental photoelectric encoder and an electronic slide. Three-dimensional laser point cloud of the target was obtained through the detection system moving along the line between the trees. According to the structure of the spraying system, the spraying area was partitioned into several spaces with the same scale, and the number of point clouds and leaves was counted respectively by computers and men in each sub-region. Based on the assumption which the leaf areas were almost the same in each spraying area, the function relationship between the number of point clouds and leaves was analyzed based on Matlab software cftool. The curve fitting results showed that the correlation coefficients between the leaf number and laser point number were 0.9257, 0.931 and 0.9364, respectively, with Gaussian function, polynomial function and exponential function, and the exponential function was the best. On the other hand, based on the above three functions, the minimum relative error of the thick area was 11.46%, the minimum relative error of the area between thick and sparse was 11.05%, and the minimum relative error of the sparse area was 35.5%. Then the leaf area density was calculated by the decided function and coefficient transformation. The calculation of the leaf area density from three-dimensional laser point provided a extra information for calculating the pesticide dosage. A statistic analysis on the real fruit trees and a optimizing for the target detection system were needed, more accurate function relationship between the laser point density and leaf area density would be calculated via the added correction coefficient.

Abstract:A three-dimensional inverse design of a submersible axial-flow pump was performed and the loading distributions of both the impeller and guide vane were studied. The hydraulic efficiency was set as the design objective, the optimized loading distributions of the impeller and the guide vane were attained based on numerical simulation results. The orthogonal experimental design, univariate analysis and the numerical simulation were used to study the influence of the loading distribution parameters on both the flow characteristics and hydraulic performance of the submersible axial-flow pump. In order to get superior hydraulic efficiency, the impeller should be fore loaded on both the hub and the shroud, and the guide vane should be mid loaded for the hub and fore loaded for the shroud. Specifically, the range of the loading parameters were as follows: for the impeller blades, the loading slope was in the range of -1~0, which was a front loaded kind, the front loading point was in the range of 0.25~0.45, and the after loading point was in the range of 0.55~0.75;for the guide vane, the hub slope was close to 0 which was a mid loaded kind, the shroud slope was ranged from 0 to 0.75 which was after loaded kind, the hub front loading point was in the range of 0.25~0.45, the shroud front loaded point was close to 0.25, the hub after loading point was in the range of 0.55~0.75. In the impeller design, it was found that the front loaded blade can suppress secondary flows in the blade outlet near the hub. Due to the diffusion structure of the guide vane, the seperation vortex near the wall was inclined to happen. In the design of guide vane, it was found that the separation vortex near the wall was suppressed in the hub-mid-loaded and shroud-fore-loaded diffuser. The impeller and guide vane with the above loading distributions were matched with each other, which can give a better design outcome for the submersible axial-flow pump.

Abstract:In order to research the internal sound field characteristics and reduce the running noise of self-priming vortex pump at low-flow rate, the CFD and Lighthill sound analogy theory was adopted to solve the internal acoustic field and optimize the noise of self-priming vortex pump. Firstly, the pressure fluctuation of self-priming vortex at 0.4Qd，0.8Qd and Qd were obtained from the unsteady simulation with the RNG k-ε turbulence model in CFX software. The datum of pressure fluctuation were extracted and input into the ACTRAN acoustics software, the SPL of the pump discharge, internal sound pressure distribution and main noise source in pumps at different flows were got by acoustic field calculation. Then，according to the laws of the Ewald frequency modulation, four different types of unequal spacing impellers were designed with modulation angle A of 2°, 4°，6°and 8°. Finally, the acoustic field calculation of four different impellers was conducted, the impeller with unequal spacing and A value of 4°had lower noise, whose sample made by 3D printing was chosen to conduct the performance and noise reduction test. The simulation results showed that the flow-induced noise of self-priming vortex pump was closely related to the pressure fluctuation which mainly caused by rotor-stator interaction，both of them had the same frequency characteristic，the maximum sound pressure appears at two times blade passing frequency. With the decrease of the flow rate, the SPL of the pump discharge was increased, the sound source of the self-priming vortex pump was mainly distributed in the channel and the tongue close to the pump discharge. The noise test results showed that the impeller sample with A value of 4°had little effect on the performance of the self-priming vortex pump and can reduce noise at low-flow rate, under the design point, noise can be decreased by 4dB, and it can be decreased by 2dB when low flow was 0.4Qd.

Abstract:In order to study the mechanism of bottom vortex generation in the suction passage of pumping station, and explore the relationship between pressure pulsation and vortex generation under flare pipe at bottom of suction passage, 20 pressure pulsation monitoring points were evenly arranged at the bottom of suction passage in the form of concentric circular ring. At speed of 2200r/min, the pressure pulsations experiment under different flow conditions was done. By analyzing the time domain and frequency domain of pressure fluctuation and pressure distribution at the bottom of suction passage, the law of pressure pulsation at the bottom of suction passage of the axial flow pump was revealed. According to the analysis of pressure fluctuation time domain, the pressure fluctuation amplitude of the bottom water flow at the bottom of inlet basin was decreased and then increased with the increase of flow rate. The maximum pressure of the flow pressure was fluctuated under the large flow condition, which was the same as the design flow. No vortex and whirlpool occurred mainly in the case of large flow conditions. The experimental results showed that the pressure pulsation at the bottom of the suction passage was twice as high as that of the impeller, and there was no dominant frequency at impeller frequency, which indicated that the pressure pulsation at the bottom of the suction passage under the bell-tube of the axial flow pump was still affected by impeller rotation. Under large flow conditions, the vortex under the bell-tube was easy to produce with high frequency of occurrence and long duration. The position of the vortex under different working conditions was corresponded to the position of the low pressure zone at the bottom of suction below the bell-tube.

Abstract:In order to acquire clean energy from the natural environment and supply power to the wireless sensors and communication modules, a vortex-induced vibration self-generating device was designed based on the principle of vortex-induced vibration and resonant acoustic amplification. The device mainly consisted of a cavity, a cylinder, a piezoelectric cantilever composite structure, a base and two Helmholtz resonators. Firstly, mechanical analysis of the piezoelectric cantilever composite structure in the self-generating device was carried out. Secondly, based on the computational fluid dynamics method, the dynamic characteristics of the flow field of self-generating device under different plate lengths were analyzed. And the influence of length of cantilever beam on vortex frequency, lift and drag coefficient was clarified. The finite element software ANSYS was used to simulate the transverse reciprocating vibration of piezoelectric cantilever composite structure to finish the structural design. Finally, the structural dimensions of the Helmholtz resonator on both sides of the device were optimized to make the flow field vortex shedding frequency. And the first-order transverse vibration frequency of piezoelectric cantilever composite structure and the resonant frequency of the resonator was consistent. The experimental results demonstrated that the self-generating device can produce an open-circuit voltage with a peak-to-phase voltage of 6.0V at wind speed of 5m/s, and the above three frequencies were consistent. The experimental results also showed that the speed of 4~6.25m/s was the self-locking wind speed range of the self-generating device. Within the wind speed range, the self-generating device can produce the maximum voltage amplitude. The results of the study provided a reference for the structural design of the vortex-induced vibration self-generating device.

Abstract:The arid and semi-arid areas of Northwest China are ecologically fragile areas, the construction of ecological networks can connect broken habitat patches and enhance connectivity between landscapes. The layout optimization of ecological nodes can reduce energy consumption and increase stability, which is of great significance to maintain the stability and security of regional ecological environment. Therefore, based on the typical ecologically vulnerable area—Dengkou County, remote sensing image interpretation data in 2015 was used as the research material. Eco existing network infrastructure, with improved H&V algorithm (force-directed model) optimized by optimizing the layout of ecological network node. The results showed that compared with the H&V algorithm, the optimized ecological node layout coverage of force-model optimization was 90.79%, which was increased by 4.08 percentage points. The average clustering coefficient was increased to 0.071, which was 1.4 times of that of the unmodified H&V algorithm. The distribution uniformity was reduced to 2.629, which was 0.629 lower than that of the unmodified H&V algorithm. By model optimization, the network structure was clear, the ecological node layout was uniform, and the node coverage was higher, indicating that the optimized ecological network structure was more stable.

Abstract:The development of canal irrigation technology was briefly reviewed. In order to realize the precise control of irrigation canal water delivery in farmland, a remote intelligent control system of canal irrigation sluice was designed based on the Internet of things (IOT) and cloud architecture. The system was consisted of integrated rotary sluice, local control software, remote terminal access system and cloud middleware. Rotating structure was used to spool of the sluice in order to reduce the driving power consumption when opening and closing gates. An embedded local control system based on ARM was established to implement local control and data acquisition. Wireless communication module and photovoltaic power supply system were integrated to solve the problems of complicated wiring and difficult power supply in the field. Remote data transfer and control instruction delivery were implemented through database and cloud middleware in Ali cloud server. A cloud control model of gate opening based on double feedback of water level and flow was established to achieve intelligent operation of sluice groups. According to the rotating angular velocity variation of sluice at opening and closing stage, an abnormal warning method of sluice operation was put forward. Remote terminal access system, including B/S version and APP version was developed for users to monitor operation state data of the sluice group, remotely control any sluice, and carry out reasonable dispatch of water resources in the irrigation area. Experimental results showed that the remote intelligent control system had the characteristics of safe and reliable operation, fast response, high control accuracy and low maintenance cost. The intelligent control system of canal irrigation sluice could satisfy the precise control for water conveyance and distribution in the small and mediumsized irrigation canals.

Abstract:To investigate the effect of different tillage methods on soil organic carbon pool, straw returning apparent humification coefficient and maize yield, an eight-year（2008—2015）field experiment with six tillage measures under straw returning in dark loessial soil on Loess Plateau was conducted. The tillage measures included three single continuous tillages (no-tillage (NN), subsoiling (SS) and conventional tillage (CC)), and three rotational tillages (no-tillage-subsoiling (NS), subsoiling-conventional tillage (SC) and conventional tillage-no-tillage (CN)). The results showed that compared with the conventional tillage, the measures of NN, SS and rotational tillage increased the content of soil organic carbon (SOC), microbial biomass carbon (MBC), water-soluble organic carbon (WSOC) in 0~10cm soil layer, improved the ratios of MBC to SOC and WSOC to SOC. Although there was no significant difference in the hardly oxidized carbon (HOC) content for different treatments in 0~10cm soil layer, the ratio of HOC to SOC was increased by SS, NN and rotational tillage in the soil layer of 10~20cm, 35~50cm and 20~35cm, respectively. The store of HOC was increased significantly in the NN treatment in 0~50cm soil layer. Compared with conventional tillage, the yield of corn and the dry mass of corn straw were increased in the treatments of SS, NN and rotational tillage, the maximum increment was found to be in the treatment of NS, by 13.79% for grain yield and 12.04% for straw dry mass, respectively. After eight-year straw returning, the apparent humification coefficient of straw in conventional tillage treatment was 8.94%，which was lower than those in the treatments of NN, SS and rotational tillage. The apparent humification coefficient of returning straw was 14.09% in the NS treatment, which was the highest among all the treatments. Based on soil carbon pool and corn yield, the tillage of NS was the most suitable measure for the local soil conditions.

Abstract:The relationship between grain yield response of winter wheat and soil water under different soils was simulated based on the calibrated Aquacrop model, and the expansion at regional scale was conducted to the results from the model simulation, combined with the soil distribution and the actual planting of winter wheat in Daxing District, Beijing, on the basis of which the variations of the water consumption, the yield and the water productivity of winter wheat under different irrigation schedules were analyzed, and the deficit irrigation schedule for winter wheat that was suitable for the actual situation of the water resources in North China was recommended. The results showed that the application of Aquacrop model can better simulate the dynamic changeable process of the soil moisture and the canopy coverage during the growth period of winter wheat as well as the biomass and the yield, and the calibrated model can be used to study the relationship between grain yield response of winter wheat and soil water. When the irrigation quota was within the range of 300mm, the water consumption was increased with the increase of irrigation amount;under the condition of the same number of irrigation times, the difference of the water consumption was significant due to the variation of the transpiration amount since the irrigation date was different. Under the same treated conditions, the yield was higher in the years with excessive precipitation on the whole, while the yield was increased with the increase of irrigation amount under different treated conditions;with the same irrigation times, the selection of irrigation date for key growing stage was essential to the yield formation of the winter wheat and the increase of water productivity. Based on the principle of production-increasing and efficiency-improving of the winter wheat, in the case of the irrigation for one time, the key guarantee should be on the water demand for the jointing-heading-stage;in the case of the irrigation for two times, the key guarantee should be on the water demand for the returning-green-jointing stage and heading-milky-ripe-stage;in the case of the irrigation for three times, the key guarantee should be on the water demand for the returning-green-jointing stage, the jointing-heading-stage and the heading-milky-ripe-stage. Aiming at the actual situation of the serious shortage of water resources in North China, it was recommended that the deficit irrigation schedule with two times of irrigation should be adopted for the winter wheat in Daxing District, Beijing, which can reduce the irrigation quantity and water consumption respectively by 140mm and 65mm to ensure 75% of the yield, compared with the condition of the irrigation for four times. Thus it can be seen that the selection of proper deficit irrigation schedule can greatly reduce the regional irrigation amount and water consumption in the areas of shortage of water resource similar to North China, which had important practical significance in stabilizing the yield of winter wheat and conserving water sources in the region.

Abstract:The earth surface soil, especially cultivated soil, contact angles of soil may be changed by external factors. Hydrophilic soil will translate into hydrophobic soil because of the bigger contact angle. Repellent soil will bring a series of agricultural and environmental problems. To develop the study to the pore water-air shape distribution in different contact angle soils, some tests were carried out. The experimental results showed that the increase of contact angles between soil particles and pore water can make the thickness of the closed-water soil layer reduced. When the contact angle was increased to a certain value, the closed-water soil layer thickness would remain unchanged. With the increase of the contact angle, the thickness of closed-air layer was reduced. It was different from the continuous solid surface, the contact angel of soil granule was less than 90°, even reduced to 36°, it would also appear the water-repellent phenomenon obviously, but with the increase of the saturation degree in the sand, the water-repellent phenomenon would disappear. The corresponding saturation of water repellent and hydrophilic conversion was basically consistent with the corresponding saturation of closed-water system and bi-opened system transformation. Therefore, the critical water content of hydrophilicity to hydrophobicity was closely related to pore water-air configurations. The matric suction in different pore water-air configurations was analyzed with ideal models, the causes of this phenomenon was the disappearance of water-air surface centers of curvature in water side (contact angle was less than 90°), the matric suction caused by water-air surface was greater than zero. The results suggested that it was not enough to focus on chemical property of soil water repellency, the mechanics of interface was also an important aspect of repellent soil study.

Abstract:Mustard biomass and heavy metal enrichment and transfer characteristic under the separate furrow irrigation was studied, which plays an important role in the phytoremediation of soil heavy metals pollution. The experiment was conducted from March, 2014 through November, 2015, the irrigation frequency (I3, I4 and I5 were irrigated 3, 4 and 5 times, respectively, and the irrigation amount was 0.15m) and frequency of fertilizer (base fertilizer was 0.74g/m3, fertilizer amount was 1.3g/m3, according to water consumption of 0.01 m, according to frequency of F0, F1, F2, F3 and F4) were set up as two factors. Results showed that under the influence of irrigation frequency, mustard leaves of super oxide dismutase (sod) activity and proline were increased with the increase of irrigation frequency, malondialdehyde was on the decline. Biomass, cadmium mass fraction, cadmium enrichment coefficient, cadmium total accumulated amount of cadmium of I4 was increased by 12.33%~89.71%, 5.00%~44.33%, 0.50%~55.36% and 22.22%~114.81%, and those of I5 were increased by 19.21%~87.37%, 24.00%~93.51%，13.44%~112.30% and 77.42%~168.75%, respectively, compared with those of I3. The growth of biomass in the aboveground was greater than that of the root, but the root of the cadmium mass fraction, the cadmium concentration coefficient and the total amount of cadmium accumulation were greater than the ground. In the influence of fertilization frequency, mustard of biomass, cadmium mass fraction, cadmium total cadmium accumulation and cadmium enrichment coefficient under high frequency fertilization (F4) were increased by 22.55%~99.71%, 30.68%~87.40%, 37.80%~112.20% and 71.43%~213.51% than those under low frequency fertilization (F1), respectively, the roots growing rate was greater than the grounds in low frequency irrigation, and the middle and higher frequencies of irrigation the ground was lower than the roots. In addition, the cadmium transfer coefficient was decreased slightly with the increase of supply of water and fertilizer, but the overall maintenance level was high. Through model simulation and verification, the result showed that the ability of mustard heavy metal repair to be consistent with the frequency response of water and fertilizer.

Abstract:Soil nitrogen (N) mineralization is a critical ecological process of N cycling that plays an important role in determining soil N-supplying capacity. Based on a long-term fertilization experiment on paddy field in the Dongting Lake region, China, the responses of organic N mineralization in 0~20cm soil layer and associated temperature sensitivity to different fertilization were studied. The experiment included five treatments: CK (without fertilization), CF (farmers’ practice of applying chemical fertilizer NPK), NK (application of chemical fertilizer NK), NPK (balanced application of chemical fertilizer NPK), HOM (combined application of chemical fertilizer NPK and organic fertilizer). All sampled soils were waterlogged incubated for 42d at different temperatures (5℃, 15℃, 25℃ and 35℃), and accumulated mineralized N was analyzed. Compared with CK treatment, the accumulated mineralized N produced during 42d incubation increased significantly (P<0.05) under different fertilization treatments while the increases gradually decreased from 32.7%~80.4% to 14.9%~59.7% along with the increment of temperature. The relationship between cumulative mineralization and effective accumulated temperature well fitted the effective accumulated temperature model (EATM) in all treatments at 25℃ and 30℃, and the values of K and n associated parameters in EATM in all fertilization treatments were higher by 2.7% ~ 39.5% and 4.0% ~21.3% than those in CK treatments, respectively, suggesting long-term fertilization presented obvious increased effects on both soil N supplying intensity at initial stage and later N mineralization rate. Moreover, the potentially mineralizable N (No) and mineralizable ratio of soil N were significantly (P<0.05) increased by 22.4% ~72.4% and 7.8% ~ 39.0%, respectively, when fertilization was adopted, and the HOM treatment presented the best results. The values of temperature sensitive coefficient (Q10) of soil N mineralization rate constant was ranged from 1.77 to 2.09 within the temperature range of 5 ~ 35℃;the values of Q10 and activation energy (Ea) for soil N mineralization were significantly (P<0.05) lower in all fertilization treatments than those of no fertilizer treatment, which followed the descending order of CK, CF, NK, NPK and HOM. The Q10 value for each treatment was higher from 5℃ to 15℃ than that from 15℃ to 25℃ and from 25℃ to 35℃, indicating that the most sensitive scope for response of N mineralization to soil temperature was at 5 ~ 15℃. It can be concluded that HOM treatment presented better effects in improving soil N mineralization capacity, optimizing N mineralization process and decreasing associated temperature sensitivity as compared with any other chemical fertilizer treatment, suggesting combined application of chemical N, P, K and organic fertilizer should be proposed for the rice production in the studied area.

Abstract:The development of new fertilizers from agricultural and industrial wastes could be both environmentally-friendly and low-cost. High-value utilization of chicken feather (CF) and cellulose (Cell) has always been a challenging endeavor. A multi-functional zinc-rich fertilizer was developed by cross-linking CF and Cell with KOH/H2O/CO(NH2)2 (KOH, 1.5mol/L;CO(NH2)2, 0.12g/mL) being a composite solvent, which was named Cell-CF. The main procedures were: the CF was firstly gone through alkaline hydrolysis in the composite solvent with ratio of solid to water of 1∶10 at temperature of 75℃ for 2h, then the polypeptide solution was obtained and cooled at -12℃;secondly, the Cell (0.06g/mL) was immersed into the polypeptide solution and the Cell-CF hydrogel was obtained after high-intensity stirring for 30min;thirdly, dilute H2SO4 solution was used to adjust the pH value of Cell-CF gel to 6.5;fourthly, ZnSO4·7H2O was added to the gel followed by constant stirring of 1h;finally, the above gel was prilled with a 1cm×1cm×1cm cubic mould and dried at 60℃ in oven. Chemical analyses of the granulated Cell-CF fertilizer showed that it contained nitrogen of 150.6mg/g, potassium of 136.7mg/g and zinc of 13.9mg/g. Water sorption measurement indicated that Cell-CF had good swelling capacity in water. Hydrostatic nutrients release experiment revealed that Cell-CF could slow down the release of potassium and zinc into water. The formation mechanism of cross-linking structure of Cell-CF was investigated by FTIR and X-ray. It was demonstrated that the crystal structures of CF and Cell were destroyed after being treated with the composite solvent, and there was hydrogen bond interaction between the polypeptide and Cell. After the Cell-CF was immersed into water for 8h, strong fluorescence signal was detected from the crossed Cell-CF while there was no fluorescence around Cell-CF, meaning that the polypeptide was not dissolved in water and the molecular interactions between Cell and CF were strong. Photoelectron spectroscopy results showed that zinc was chelated with the functional groups of Cell-CF. Soil incubation experiment and pot experiment showed that Cell-CF could release high bio-available zinc in a long term.

Abstract:The objective was to clarify the characteristics of soil water geochemistry and the relationships between soil water and soil environmental factors in karst peak-cluster area. Soil water samples and soil samples were collected from the depths of 0~20cm and 20~40cm in each sampling site. And all samples were tested to meet groundwater testing standards and soil testing standards respectively. The methods of grey relational analysis (GRA) and canonical correspondence analysis (CCA) were employed to reveal the characteristics of soil water geochemistry and the relationships between soil water and soil environmental factors. The results revealed that geochemical properties of soil water and its corresponding geochemical indicators of soil were with different levels of spatial heterogeneity. And the variable coefficient of pH value was the smallest among the indicators, just ranging from 2.48% to 10.44%. Except Mg2+ and Cl-, the variation coefficients of soil water geochemistry were decreased with the increase of depth. The properties of soil water geochemistry in the depth of 20～40cm were more stable than that of 0～20cm. HCO-3, Ca2+ and SO2-4 were the main factors affecting the soil water geochemical characteristics, with HCO-3 as a leading role. Furthermore, the CCA results showed that the correlations between geochemical properties of soil water and soil environmental factors were different. Among the main soil environment factors influencing soil water geochemistry, the total potassium (TK), exchangeable magnesium (EMg), available zinc (AZn) and soil particles of 0.2～2mm and 0.002～0.02mm diameters influenced the Mg2+, HCO-3 and pH value of soil water;the available copper (ACu), humic acid (HA) and humin (HM) mainly impacted Na+ and K+ of soil water;rapidly available potassium (AK), soil water content and soil composed of particles of diameter less than 0.002mm, and influenced soil water geochemistry by Na+, K+, Cl-, SO2-4 and so on.

Abstract:The observed data of surficial precipitation stations were used as benchmark data, the Hulan River Basin of the alpine region was used as typical study area, the precision of the new generation satellite rainfall products TRMM（the tropical rainfall measuring mission） 3B42V7, 3B42RT and CHIRPS （Climate hazards group infrared precipitation with station data）, IDWP precipitation data based on IDW（inverse distance weighted）were evaluated in day, month, quarter and spatial scales. The precipitation stations and satellite data were used to drive SWAT model, the SUFI-2 algorithm was used to calculate the model and sensitivity of parameters, simulate the daily flow process, and evaluate the application ability of multi satellite precipitation in watershed hydrological simulation and prediction. The research results showed that in the average watershed scale, the amount of 3B42V7, 3B42RT and CHIP over ground rainfall were 5.43%, 41.24% and 3.37%, 3B42V7 was very close to the ground precipitation in monthly, quarterly time scales. The cumulative probability distribution of daily precipitation intensity of 3B42RT was close to the surficial precipitation. The simulated results of 3B42V7 and CHIP were both very well in the rate of calibrated and validated period of the daily flow simulation results, NSCE was 0.77 and 0.84 in calibrated period, in the verification period it was 0.67 and 0.56, respectively. 3B42RT for the peak simulation of the flow was poor. The change of water quantity of CHIP was close to that of rainfall station, and the groundwater quantity of 3B42RT into the river was smaller than that of others, but the runoff depth and soil water content were larger. TRMM 3B42V7 and CHIRPS can be used as a basic application of precipitation data in cold regions for water resources management, drought monitoring and flood forecast research in ungauged and data-deficiency region. The next step would be to study the correction method of satellite precipitation data for cold region which would provide more reliable data for the future application of satellite precipitation data to carry out related research in the cold region.

Abstract:Benggang erosion is an important erosion type, which frequently occurs in Southeastern China. Colluvial deposits of Benggang is an important source of the Benggang sediment. Based on simulated rainfall experiments and three-dimensional (3D) laser scanning, the characteristics of spatial-temporal differentiation of soil erosion processes on the colluvial deposits of Benggang were investigated. An indoor rainfall experiment was conducted with a 30° slope of the Benggang deposit and a rainfall erosion intensity of 3.33mm/min, which represented a typically higher rain intensity in the study region. Rainfall simulation experiments were conducted in 2016 in the rainfall simulation hall of Laboratory of Red Soil Erosion and Flow Hydraulic in South China in Guangzhou City, Guangdong Province. The results showed that point cloud data from the 3D laser scanning can reflect the characteristics of soil erosion, deposition and sediment yield before and after rainfall events. Total amount of rill erosion，sheet erosion were 0.0366m3 and 0.1135m3, respectively. Slope position had little influence on sheet erosion, while it had a significant impact on rill erosion. Roughness of soil surface was increased first and then decreased with time during the experiment. The values of roughness of soil surface were in a descending sequence of lower slopes, middle slopes and upper slopes, and it varied with time at different slope positions. Roughness of soil surface on lower and middle slope was increased firstly and then decreased with time during the experiment, while it was increased constantly with time on the upper slope. No significant variation of soil erosion on upper slopes occurred with rainfall events. The soil erosion amount and sediment yield were decreased logarithmically with time. The difference of erosion amount between upper and lower slopes was significant, whereas slope positions showed insignificant influence on soil erosion and sediment yield.

Abstract:Sediment delivery ratio （SDR) is a critical transfer parameter for investigating soil erosion and sediment yield in a watershed, which is a matter of concern not only because of the sediment yield input to river but also due to its important effects such as safety-operation and flood control in reservoirs. Currently, there is limited information on the quantitatively estimation of SDR for different periods in the catchments of the Three Gorges Reservoir Region (TGRR), and its temporal changes of estimates are also scarcely analyzed. Thus, Huangchongzi and Gongnonggou catchments, located in the central part of the TGRR were selected as study areas, which represented one of the typical purple soil areas. In order to investigate the SDR of the past 52 years in the central part of the TGRR strictly according to the definition of SDR, annual average soil erosion was precisely estimated with an integration of geographic information system (GIS) and the revised universal loss equation (RUSLE). Sediment yields for different periods from 1963 to 2014 were identified by pond sedimentation amount based on the dating results of the comprehensive utilization of 137Cs and 210Pb tracer techniques, and these results made use of calculation of SDR for different time-interval. Results showed that the average soil erosion amount was 119.72t and 86.86t and its coefficient of variation (CV) was 0.76 and 0.86 during 1963—2014 in Huangchongzi and Gongnonggou catchments, respectively. The average soil erosion amounts in 2001—2014 were obviously lower than that in 1963—2000 for these two catchments. The main reason was the benefit of grain to green, which started in 2001. The 137Cs time mark dating-results were in agreement with results by 210Pbex constant rate of supply (CRS) model. Based on this analysis, sedimentation core for Huangchongzi and Gongnonggou ponds was segmented with 19 and 12 time-intervals and its CV of the corresponding sediment yields was 0.28 and 0.19 from 1963 to 2014, respectively. The SDR fluctuated distinctly from 1963 to 2014, which were especially intensity after human-activities. The CV of the SDR for different time-interval was 0.33 and 0.82 from 1963 to 2014 for Huangchongzi and Gongnonggou catchments, respectively. The results estimated strong variations in SDR from 0.07 to 0.9 for different time-intervals in the catchments, and this emphasized that the reasonable selection of time-interval played an critical role in estimating SDR, particularly when benefit assessment for soil and water conservation was implemented.

Abstract:The national water resources monitoring capacity building project which started in 2012 in China is an important way to improve the level of water conservancy information. It requires that the historical time-series monitoring data of water resources should be complete and reliable so that it can be used to support data analysis and decision making. The basic scenarios for monitoring abnormal data were summed up and a comprehensive model was proposed, aiming at abnormal data detection and recovery. Moving average fitting and ensemble empirical mode decomposition (EEMD) method were introduced to identify both observable and non-observable abnormal monitoring data. The particle swarm optimization based least squares support vector machine (PSO-LSSVM) was then adopted for abnormal data recovery and imputation. All above methods were tested with the daily water consumption monitoring data of water company. Results showed that the feature vector that contained exception data could be well preserved by moving average fitting and EEDM method and the effective reconstruction of water monitoring data was achieved, exhibiting better applicability than traditional statistical methods. Moreover, it can be observed that the PSO-LSSVM model had the ability to further improve the fitting results of the time-series data that excluded outliers. The fitted curve conformed to the seasonal fluctuation rule and it was consistent with the actual state of water demand. Accordingly, the objective of recovering the excluded data exception could be achieved reasonably by using this method. Furthermore, these methods can be applied to the analysis of monitoring data in other areas.

Abstract:Bio-oil is the main product of biomass pyrolysis, which is considered as a promising replacing fuel for fossil oil. But the high oxygen, high viscosity, low heat value and poor stability of bio-oil make it difficult to apply directly. Thus study on the improvement of bio-oil quality is very necessary. Different mass fractions (5%~25%) of methanol, ethanol, octanol and its two mixed alcohols were used to improve the heavy oil quality which was pyrolysed from pine nut. The physical and chemical properties and storage time of heavy oil with alcohol additive were investigated. The results showed that the addition of alcohol additives could significantly reduce the viscosity, water content and pH value of heavy oil, and enhance its heat value. Simultaneously, the contents of phenols, polycyclic aromatic hydrocarbons and ketones in the heavy oil were decreased, and the contents of aliphatic hydrocarbons, aromatic hydrocarbons and alcohols were increased. The heavy oil adding mixed alcohol showed a better stability, and its viscosity and water content were only increased slightly after 56d. After adding methyl-octanol mixture and stored for 56d, the viscosity of the heavy oil was 980mPa·s, and water content was 21.02%. The growth rate was only a half of the original heavy oil. With the increase of methyl-octanol mixture additive amount, the heat value of heavy oil was increased. When the addition amount was 25%, the heat value was 32.66MJ/kg. However, it was found that the combustion performance was the best when adding 20% of methyl-octanol mixture;the weight loss rate of combustion section was the largest and the amount of ash after combustion was minimal.

Abstract:With regard to the distributed bio-char production technology that combusting pyrolysis volatiles for its heat resource, and aimed at eliminating charcoal particles, decreasing heavy components and increasing light components in pyrolysis volatiles, thereby improving the combustion characteristics of pyrolysis volatiles, by using an auger reactor for continuous pyrolysis of biomass and an oxygen-lean conditioning reactor for pyrolysis volatiles, with the stoichiometric air rate of combusting charcoal particles in pyrolysis volatiles as the basis, the experimental study on in-situ oxygen-lean conditioning on biomass pyrolysis volatiles was carried out. The influences of conditioning temperatures and air rates on the components of pyrolysis volatiles were analyzed. The experimental conditions were as follows: pyrolysis temperature of 550℃, biomass feeding rate of 527g/h, pyrolysis residential time of 10min, and the control temperature for charcoal tank was 250℃;the conditioning temperatures were 350℃, 400℃, 450℃ and 500℃, respectively, and the air rates were 20mL/min, 40mL/min, 60mL/min and 80mL/min, respectively. The results showed that the particle size of charcoal in the pyrolysis volatiles was 1~2μm, and it was difficult to collect the particles at the conditioning temperature of 350℃ with air rate of 20mL/min, in-situ oxygen-lean conditioning may eliminate the charcoal particles in pyrolysis volatiles;in-situ oxygen-lean conditioning had less influences on the gas components of pyrolysis volatiles, the changing rates of H2 and CO2 were all within ±5%, the influences were even weak for CO and CH4 whose changing rates were within ±2%;along with the elevating of conditioning temperature and the increase of the air rate, the contents of alkyl group chemicals in the heavy components of pyrolysis volatiles showed obvious decrease while the phenols showed evident increase, a little bit of increase in contents was found for the lower-content chemicals such as furans, alcohols, indenes and aldehydes. The contents of lower carbon compounds were increased while the higher carbon compounds were decreased;the relative contents of alkyl group, acids, ketones and phenols in light components of pyrolysis volatiles showed obvious changes, and the changes of phenols’ absolute contents were not obvious due to their chemical stabilities, similar to that in the heavy components of pyrolysis volatiles, the lower carbon compounds in light components of pyrolysis volatiles had also shown increases. Due to the feasibility of eliminating the charcoal particles, decreasing heavy components and increasing light components in pyrolysis volatiles, in-situ oxygen-lean conditioning may improve the combustion characteristics of pyrolysis volatiles, the research results could be used as reference for distributed bio-char production which pyrolysis volatiles were combusted for pyrolysis.

Abstract:Hemicellulose, cellulose and lignin are the main components of biomass. Different structures and components of the three components may have important effects on the product properties and reaction process of biomass hydrothermal carbonization. However, in the past few years, there were limited reports on HTC of xylose and its effect on the structure changes of cellulose and lignin during HTC. In order to study the hydrothermal carbonation characteristics of xylan, hydrothermal carbonation experiment was carried out in the batch reactor at 160~240℃ for 120min. The effects of xylan on the hydrothermal process of cellulose and lignin were investigated at 220℃ for 120min. It was found that the xylan hydrochar appearred at 200℃, and its yield was gradually increased with the increase of reaction temperature. When the temperature reached 240℃, the yield reached 13%. Xylose was also mixed with cellulose and lignin respectively according to the proportion of three components in wheat straw, and the mixture was hydrothermally treated at the temperature of 220℃ for 120min. The results showed that xylan had little effect on the yield of cellulose hydrochar, while the carbon mass fraction was increased from 42% of the cellulose hydrochar to 48% of the cellulose and xylose hydrochar. The yield of xylan and lignin hyrchar was decreased by 23 percentage points and the carbon mass fraction changed little compared with those of lignin hydrochar. The functional groups were decreased with the increase of temperature, while the C=C, C=O and aromatic peaks were gradually enhanced, and the thermogravimetric analysis presented a good thermal stability of xylan. Fourier transform infrared spectroscopy, X-ray diffraction analysis and thermogravimetric analysis showed that xylan can promote the fracture, polymerization and aromatization of the molecular structures for cellulose and lignin during hydrothermal carbonization, and improve the aromatic properties of hydrochars.

Abstract:The emission of ammonia in manure high temperature aerobic composting not only polluted the air but also reduced the nitrogen content of organic fertilizer. Therefore, the control of composting process of ammonia volatilization is the key of reducing nitrogen loss and environment ordor emission. In order to study the effect of membrane covered on reducing the emission of ammonia in manure aerobic composting, pig manure and wheat straw were used as experimental materials, and Gore film with selective permeability was used as covering material, the aerobic composting trial was carried out in a lab-scale intelligent membrane-covered aerobic composting reactor system for 27d. There were membrane-covered treatment and control treatment in this trial. Air blown at an hourly interval (flow velocity of 3L/min through the pipe at the bottom of the reactor diffused through the composting material to maintain aerobic conditions. The composting temperature, oxygen content and ammonia concentration were measured during the composting. The results showed that the high temperature duration of the membrane-covered group was longer than that of the control group, and it was more beneficial to kill the harmful pathogens. Compared with the control group, the NH3 emission in the membrane-covered group was decreased by 18.87%. Compared with the peak time of the temperature, the peak time of NH3 peak in both groups was delayed, and the delay time of the membrane-covered group was longer, and the phenomenon that peak value of NH3 lagged temperature was further revealed.

Abstract:In order to explore an energy-efficient thermal environment control model in greenhouse, based on heat pump technology, a new type of air-soil dual-source heat pump system matched with the greenhouse model was designed and built, and the system performance was also tested. This system was compounded of air source heat pump and soil source heat pump, and adopted the plate heat exchanger in series form. The air-soil dual-source heat pump system had four kinds of heating modes, including air source mode with single plate heat exchanger, air source mode with double plates heat exchanger, soil source mode with single plate heat exchanger and soil source mode with double plates heat exchanger. These working modes can be converted by controlling the on-off of the electromagnetic valve. The soil source heat pump mode can solve the adaptability problem of air source heat pump under low temperature condition, while the air source heat pump mode can alleviate the problem of imbalance of the acquisition and release of the soil source heat pump. In the winter and spring test period, the COP (coefficient of performance) and temperature rise rate of the heat pump system in air source mode with single and double plates heat exchanger were tested by heating the water in the heat insulating water tank. The operation results in spring were better than that in winter. In spring, the COP of the heat pump system in single and double plates air source mode were 2.1 and 3.1, respectively, and the COP of the heat pump system in single and double plate soil source mode were 2.2 and 2.3, respectively. The energy-saving effect of air source mode with double plates heat exchanger was the most significant, the energy-saving rate was up to 50.4%. During the winter test period, the air source mode with double plates heat exchanger could raise the temperature in the greenhouse model in the typical sunny days. The indoor temperature was higher than the outdoor temperature about 15.7℃ on average. According to the results, the performance of the double plate heat exchanger was both better than that of the single plate heat exchanger during the winter and spring. The results also showed that both the amount of heating medium and system pressure can affect the effect of the dual-source heat pump system. In conclusion, this air-soil dual-source heat pump system can make use of air energy and geothermal energy efficiently to realize the energy conservation of solar greenhouse in winter.

Abstract:The solar greenhouse is only greenhouse type for China. Indoor thermal environment of solar greenhouse is improved via the heat storage and heat release of wall body. The soil wall body, which has good characteristic of heat storage and heat release, is applied to solar greenhouse extensively in China. The thickness of soil wall body is determined by the builder’s experience due to lack construction standards. At present, the study on the heat release characteristic of different thicknesses soil wall is hot spot, which can provide the theoretical basis for the simplification and thickness optimization of soil wall body. The solar greenhouse No.1 (the top and bottom width of the soil wall body was 2.0m and 6.0m, respectively) and solar greenhouse No.2 (the top and bottom width of the soil wall body was 1.3m and 3.0m, respectively) were chosen as research object in Tai’an, Shandong Province, China. The greenhouse No.1 and No.2 had the same length (50.0m) and width (10.0m). Five testing layers of temperature at the same height of the north wall of both greenhouses were arranged. The testing period was from Dec. 20th, 2015 to Jan. 20th, 2016. The outdoor weather conditions, indoor air temperature and interior wall temperature in the sunny day (from Dec. 30th, 2015 to Jan. 2th, 2016) and cloudy day (Jan. 4-6th, 2016) were used to analyze the temperature distribution and the heat release characteristic of each testing layer in the greenhouses No.1 and No.2. The results showed that during the sunny day, the heat storage and release quantity of the greenhouse No.1 was higher than that of the greenhouse No.2, but the difference was little, which was 82.3kJ and 45.0kJ, respectively. For the three cloudy days, the heat release characteristic of wall body of the solar greenhouses No.1 and No.2 was analyzed based on the data of the wall body temperature and indoor temperature. The results showed that the heat release quantity of greenhouse No.1 was higher than that of the greenhouse No.2, the difference was 615.9kJ, but the air temperature of the greenhouse No.1 was only 0.6℃ higher than that of the greenhouse No.2 during the cloudy day. The analysis of relative temperature stability part of wall showed that the heat storage of the greenhouse No.1 was very higher than that of the greenhouse No.2. This heat relative temperature stability part for the thick wall greenhouse should be used via efficient heat exchange equipment to improve the thermal environment of greenhouse.

Abstract:Nowadays, due to changes in consumer life style and health awareness, brown rice is receiving increased interest as a source of healthy attributes. Compared with white rice, brown rice is rich in several health beneficial nutrients such as vitamins, dietary fiber, minerals, antioxidants and essential amino acids. It is necessary to study the influence of processing on nutrients of brown rice, because these nutrients are easily lost during processing. High pressure processing (HPP) is a new non-thermal preservation technology that enhances food safety and retains the food original nutrients. Up to date, the research on the effect of HPP on nutritional property of brown rice is limited. Phenolic, flavonoid content and antioxidant activity of brown rice after HPP (100~400MPa) by single step (5min and 10min of holding time) or two step process (two cycles, 5min of holding time each) were investigated. The antioxidant activity was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS+·) scavenging assays. Results showed that phenolic, flavonoid contents and antioxidant activity of brown rice were increased with the increase of pressure. Moreover, under the same pressure level, the phenolic, flavonoid contents and antioxidant activity of brown rice under two step HPP were higher than those from single step HPP. Percentage retention of phenolic and flavonoid content in brown rice treated by two step process at 300MPa was 97%. These findings suggested that the HPP was an effective non-thermal processing to retain antioxidants in brown rice.

Abstract:In order to solve paddy quality loss during drying process and storage, a natural cold resource (NCR) warehouse, which used the nature environment ice for providing cold energy to store high moisture paddy and reduce deterioration of paddy during storage period was designed. The NCR warehouse was composed by refrigeration system, paddy storehouse, ice storehouse, equipment room and control system. The paddy storehouse was a closed chamber with size of 3.8m×3m×2.8m, the ice storage room was 0.5m below ground with size of 4m×3m×2.5m. When the warehouse temperature was higher than the set temperature, the temperature sensor sent the signal to RMA411 remote input capture module, then the data output adopted the distal RM4024 analog output module, achieving real time communication between the host computer and output mold, through the RS485 serial series sent out command to start water pumps. The cold water which exchanged the cold energy from ice as coolant flowed from top to bottom in the finned tube heat exchanger by use of a water pump. The heat exchanged between hot air and heat exchanger under the action of the fan, and then the cool air was blown into warehouse to keep the paddy storage temperature at 10℃. The ice which collected in the winter provided cold energy for NCR warehouse. The paddy with inertial moisture content of 16.5% was packed on the weight of 10kg by woven bag. The paddy bags were stacked 5 layers and 12 bags per layer which stored in the NCR warehouse from May to September and another part of paddy was stored in an ordinary temperature warehouse stored in the same way as a control group. The physiological characters and processing characters of the paddy were evaluated at the end of every month. The result showed that moisture contents of paddy in the NCR warehouse was decreased less than the ordinary warehouse. The fatty acid value of paddy in the NCR warehouse was 18.3mg/（100g）. The germination rate of paddy in the NCR was 86.75%, and the total of molds was 5.1×104CFU/g. Cracked rate of paddy in the NCR warehouse and ordinary warehouse was increased by 2.77 percentage points and 16.65 percentage points, respectively. The storage character of paddy in NCR warehouse was superior to ordinary warehouse paddy. The result indicated that NCR warehouse showed a better performance on storing high moisture paddy in high temperature season.

Abstract:The separation arrangement of magnetorheological damper (MRD) and sensor in the vehicle semi-active suspension system will result in large installation space, low system reliability and high maintenance cost, especially the external environment interference for the sensor signal. Aiming at these shortcomings, an improved displacement differential self-induced magnetorheological damper (DDSMRD) was developed. There were two layer copper coils wounded on the damper piston head, one was the inner coil, the other was the outer coil. The inner coil can be acted as damping excitation coil, which can control the damping force by adjusting the applied current. The outer coil can be acted as the induced coil, which can generate an induction signal. When the outer coil was input the high frequency AC excitation signal, the self-induced coils wounded on the winding cylinder can generate the displacement signal with the same frequency. Thus, the displacement differential self-induced voltages can be obtained. The mathematical model of the relationship between the self-induced voltage and the damper displacement was derived. A static test rig was built to analyze the self-induced ability, and the results showed that the selfinduced voltage was linear to the piston displacement under static tension. Through the dynamic tests, an amplitude voltage of 0.3V, 0.6V and 0.9V was obtained under the piston displacement of 5mm, 10mm and 15mm, respectively, which also showed a good linearity. When the inner coil was applied 1A current, the proposed damper can generate 360N damping force.

Abstract:A vehicle road way coastdown virtual test system with compensation of wind speed & direction and road slope was developed to satisfy the requirements of reducing environmental influences and improving test accuracy and efficiency. Firstly, based on the American SAE J-2263 standard and the sixth stage’s fuel consumption test standard of China, the CompactRIO was employed in the test system as the key controller which was made by American National Instrument Company. The test method of wind speed and direction, road slope, tire pressure and temperature, etc., and the sensor layouts were systematically introduced. Secondly, the systematic data processing method was proposed, including the connection of segmented coastdown test data, the compensation of wind speed, the elimination of abnormal data, and the coastdown model building based on the test system. Finally, the test system was installed on a passenger car and the systematic coastdown tests were conducted. All the tests indicated that the test system worked reliably and met the test precision requirements. The processing results of the test data showed that the repetition of the coastdown resistances with the compensation of wind speed & direction and road slope was 2.2%. And the systematic deviation between the compensated and none compensated coastdown resistances was 3.7%. The designed coastdown system improved the test precision of coastdown resistance effectively and provided the means for vehicle resistance compensation for the vehicle performances test on the chassis dynamometer.

Abstract:Control of the air-fuel ratio (AFR) in gasoline engines is of imminent importance when aiming at minimizing calibration effort and meeting performance requirements. People have higher demands on the gasoline engine, which has less exhaust emission, better economic efficiency and favorable engine power performance. In order to keep the air-fuel ratio close to the stoichiometric value under transient conditions, AFR precise control was achieved by employing triple-step method which was easily to be implemented in engineering. The structure of the designed controller consisted of three parts: steady-state control, feed-forward control concerning the reference variations and error feedback control. When the desired AFR was a constant, the steady-state control would play a dominant role. And the feed-forward control would react immediately when the desired AFR was changed on account of the torque requirements changed. The feedback control would amendment AFR measured by the exhaust gas oxygen (EGO) sensor which can enhance the close-loop performance and rearranged into a state-dependent PI. A straightforward design process was provided, and the structure of the designed non-linear controller was easily achieved, which was comparable to those widely used in current automotive control. Furthermore, taking the implement delay of the injection into consideration, it can be compensated by feed-forward control based on predicting the intake manifold pressure. Finally, the simulation results in the environment of en-DYNA with a reasonable common fourcylinder engine model showed the efficiency of the proposed method. And the predicted intake manifold pressure was visibly advanced to that without prediction one in the simulation result.

Abstract:According to the parallel mechanism design theory and systematical method based on position and orientation characteristic (POC), a total topological structures analysis was performed on seven typical new SCARA parallel mechanisms (PMs) with proposed practical value. Five major topological features were revealed, which were POC set, degree of freedom (including the selection of drive pair), over-constraint degree, coupling degree and input-output motion decoupling relationship of PMs. It was found that the coupling degree of these PMs were bigger with κ=2, which meant that the forward kinematics solutions and inverse dynamic solution of the PMs were very complete. Therefore, decoupling and optimization of these PMs were completed based on the proposed mechanism topological structural decoupling principles, and 14 new equivalent mechanisms with lower coupling degree which had the same POC and DOF were achieved. Thus the 4-DOF mechanism with three translations and one rotation which can achieve Schonflies motion can be enriched greatly, and the forward kinematics solutions and inverse dynamic solution of these PMs can be obtained easily, and the numerical solution can be gotten conveniently by using one dimensional searching method. The research provided a theoretical basis for the kinematics synthesis and analysis, design and applications for these new SCARA PMs.

Abstract:The accuracy of the Z-axis in the vertical direction of the machine determines the overall performance of the three-dimensional measurement of the micro-nano coordinate measuring machine to a large extent. In order to improve the measurement accuracy of the coordinate measuring machine, it is necessary to study the Z-axis measuring system of the coordinate measuring machine. Firstly, based on the idea of minimizing Abbe error, a Z-axis measurement platform with symmetrical structure of gravity compensator was designed. Secondly, the probe system was composed of scanning electrostatic force microscope. Finally, two separate tests were carried out to verify the rationality and effectiveness of the design. The feasibility of the measurement system with gravity compensator in the static and dynamic was verified separately by the experiment, and then the validity of the scanning electrostatic force microscope probe system compensated with the double height method was verified. The experimental results showed that the novel Z-axis coordinate measuring system had a spatial resolution of 0.6nm with an effective stroke range of 50mm, and had a measurement capability for some non-conductors. The research extended the applicable range of micro-nano coordinate measuring machine and had high application value.

Abstract:Digital microfluidics based on electrowetting-on-dielectric is an emerging popular technology that manipulates single droplets at the microliter or even the nanoliter level. It has the unique advantages of rapid response, low reagent consumption and high integration. Electrowetting-on-dielectric device based digital microfluidics has shown enormous advantages in biology, medicine and chemistry and so on, and it has been used extensively in these subjects for driving single droplet. However, the lack of feedback on droplet position will result in a phenomenon that the droplet cannot be successfully driven. In that case, the droplet fails to complete the programming path. The principle of droplet position estimator based on the equivalent capacitance was adopted, and the equivalent capacitance of two adjacent driving electrodes and droplet was used as the feedback control object. The electrode capacitance was used, which was an inherent electrical property of electrowetting-on-dielectric digital microfluidics devices, to determine the position of any droplet composition in the interval of two electrodes. Capacitance was an electrical property which was sensitive to the presence of a droplet and independent of actuation signal frequency. The dimensionless nature of this droplet position estimator was independent of the droplet compositions, and its applicability was more extensive. Finally, the experimental results showed that the droplet position estimator based on the equivalent capacitance can greatly improve the success rate of the continuous motion. Thus the droplet can be driven to the established destination according to the programming path. A capacitance-based position estimator was implemented which can continuously track the displacement of a droplet within the interval of two adjacent electrodes. The displacement of a droplet was estimated through a dimensionless ratio of two electrode capacitances.